Anticipated Degradation Modes of Metallic Engineered Barriers for High-Level Nuclear Waste Repositories

Science.gov (United States)

Rodríguez, Martín A.

2014-03-01

Metallic engineered barriers must provide a period of absolute containment to high-level radioactive waste in geological repositories. Candidate materials include copper alloys, carbon steels, stainless steels, nickel alloys, and titanium alloys. The national programs of nuclear waste management have to identify and assess the anticipated degradation modes of the selected materials in the corresponding repository environment, which evolves in time. Commonly assessed degradation modes include general corrosion, localized corrosion, stress-corrosion cracking, hydrogen-assisted cracking, and microbiologically influenced corrosion. Laboratory testing and modeling in metallurgical and environmental conditions of similar and higher aggressiveness than those expected in service conditions are used to evaluate the corrosion resistance of the materials. This review focuses on the anticipated degradation modes of the selected or reference materials as corrosion-resistant barriers in nuclear repositories. These degradation modes depend not only on the selected alloy but also on the near-field environment. The evolution of the near-field environment varies for saturated and unsaturated repositories considering backfilled and unbackfilled conditions. In saturated repositories, localized corrosion and stress-corrosion cracking may occur in the initial aerobic stage, while general corrosion and hydrogen-assisted cracking are the main degradation modes in the anaerobic stage. Unsaturated repositories would provide an oxidizing environment during the entire repository lifetime. Microbiologically influenced corrosion may be avoided or minimized by selecting an appropriate backfill material. Radiation effects are negligible provided that a thick-walled container or an inner shielding container is used.

Degradation diagnosing method for low voltage electric wire and cable in nuclear facility

International Nuclear Information System (INIS)

Kamimura, Seiji; Seki, Ikuo; Yagyu, Hideki; Onishi, Takao; Kusama, Yasuo.

1991-01-01

A considerable skill is required for a visual inspection method which has been used most widely for determining the degradation of low voltage electric wires and cables used mostly in facilities such as nuclear power plants. It is extremely difficult to determine the degradation accurately and appropriately even for skilled inspectors because of individual difference. Then, a small amount of organic insulation materials is taken as a sample from insulators or sheath materials actually disposed. The pyrolytic temperature of the sample is measured by thermal gravimetric analysis to determine the extent of the degradation of the electric wire and cable based on the relationship between the degradation and the elongation. Since there is a close relationship between the temperature at which the measured weight of the sample is reduced by 5% and the degradation behavior of the mechanical property, analysis can be conducted effectively by an extremely small amount of the sample. Since the insulation degradation of relatively low voltage electric wires and cables can be determined in a non-destructive manner at high accuracy, the lifetime can be forecasted. (N.H.)

Using data visualization tools to support degradation assessment in nuclear piping

International Nuclear Information System (INIS)

Jyrkama, M.I.; Pandey, M.D.

2012-01-01

Nuclear utilities collect a vast amount of in-service inspection data as part of periodic inspection plans and the detailed assessment and monitoring of various degradation mechanisms, such as fretting, corrosion, and creep. In many cases, the focus is primarily on ensuring that the observed minimum or maximum values are within the acceptable regulatory limits, while the rest of the (often costly) surveillance data remains unused and unanalyzed. The objective of this study is to illustrate how data visualization tools can be used effectively to analyze and consider all of the in-service inspection data, and hence provide valuable support for the degradation assessment in nuclear piping. The 2D and 3D visualization tools discussed in this paper were developed mainly in the context of flow accelerated corrosion (FAC) assessment in feeder piping, where the complex pipe geometries and flow conditions have a significant impact on the ultrasonic (UT) wall thickness measurements. The visualization of eddy current inspection results from the assessment of pitting corrosion of steam generator tubing will also be discussed briefly. The visualization tools provide a more comprehensive view of the degree and extent of degradation, and hence directly support the planning of future inspection of critical components by identifying key locations and areas for detailed monitoring. The results furthermore increase the confidence and reliability of fitness-for-service (FFS) assessments and life cycle management (LCM) planning decisions with respect to component repair or replacement. (author)

Nuclear-waste-package materials degradation modes and accelerated testing

International Nuclear Information System (INIS)

1981-09-01

This report reviews the materials degradation modes that may affect the long-term behavior of waste packages for the containment of nuclear waste. It recommends an approach to accelerated testing that can lead to the qualification of waste package materials in specific repository environments in times that are short relative to the time period over which the waste package is expected to provide containment. This report is not a testing plan but rather discusses the direction for research that might be considered in developing plans for accelerated testing of waste package materials and waste forms

Water chemistry: cause and control of corrosion degradation in nuclear power plants

International Nuclear Information System (INIS)

Kain, Vivekanand

2008-01-01

The corrosion degradation of a material is directly determined by the water chemistry, material (composition, fabrication procedure and microstructure) and by the stress/strain in the material under operating conditions. Water chemistry plays an important role in both uniform corrosion and localized forms of corrosion of materials. Once we understand how water chemistry is contributing to corrosion of a material, it is logical to modify/change that water chemistry to control the corrosion degradation. In nuclear power plants, different water chemistries have been used in different components/systems. This paper will cover the origin of corrosion degradation in the Primary Heat Transport system of different reactor types, Steam Generator tubing, secondary circuit pipelines, service water pipelines and auxiliary systems and establish the role of water chemistry in causing corrosion degradation. The history of changes in water chemistry adopted in these systems to control corrosion degradation is also described. It is shown by examples that there is an obvious limitation in changing water chemistry to control corrosion degradation and in those cases, a change of material or change of the state of stresses/fabrication procedure becomes necessary. The role of water chemistry as a causative factor and also as a controlling parameter on particular types of corrosion degradation e.g. stress corrosion cracking, flow accelerated corrosion, pitting, crevice corrosion is illustrated. It will be shown that increase in dissolved oxygen content (due to radiolysis in nuclear reactors) is sufficient to make even the de-mineralized water to cause stress corrosion cracking in Boiling Water Reactors. Hydrogen Water Chemistry (by hydrogen injection) to control dissolved oxygen is shown to control the stress corrosion cracking. However, it is not possible to control dissolved oxygen at all parts of the Boiling Water Reactors. Therefore, a further refinement in terms of noble metal

Transfer coefficients in a four-cusp duct simulating a typical nuclear reactor channel degraded by accident

International Nuclear Information System (INIS)

Souza Dutra, A. de.

1985-01-01

An experimental study on forced convection in a four-cusp duct simulating a typical nuclear reactor channel degraded by accident is presented. Transfer coefficients were obtained by using the analogy between heat and mass tranfer, with the naphtalene sublimation technique. The experiment consisted in forcing air past a four-cusp naphthalene moulded duct. Mass transfer coefficients were determined in nondimensional form as Sherwood number. Experimental curves correlating the Sherwood number with a nondimensional length, x + , were obtained for Reynolds number varying from 891 to 30.374. This range covers typical flow rates that are expected to exist in a degraded nuclear reactor core. (Author) [pt

Proteasome-mediated degradation of integral inner nuclear membrane protein emerin in fibroblasts lacking A-type lamins

International Nuclear Information System (INIS)

Muchir, Antoine; Massart, Catherine; Engelen, Baziel G. van; Lammens, Martin; Bonne, Gisele; Worman, Howard J.

2006-01-01

We previously identified and characterized a homozygous LMNA nonsense mutation leading to the absence of A-type lamins in a premature neonate who died at birth. We show here that the absence of A-type lamins is due to degradation of the aberrant mRNA transcript with a premature termination codon. In cultured fibroblasts from the subject with the homozygous LMNA nonsense mutation, there was a decreased steady-state expression of the integral inner nuclear membrane proteins emerin and nesprin-1α associated with their mislocalization to the bulk endoplasmic reticulum and a hyperphosphorylation of emerin. To determine if decreased emerin expression occurred post-translationally, we treated cells with a selective proteasome inhibitor and observed an increase in expression. Our results show that mislocalization of integral inner nuclear membrane proteins to the endoplasmic reticulum in human cells lacking A-type lamins leads to their degradation and provides the first evidence that their degradation is mediated by the proteasome

Predictive based monitoring of nuclear plant component degradation using support vector regression

International Nuclear Information System (INIS)

Agarwal, Vivek; Alamaniotis, Miltiadis; Tsoukalas, Lefteri H.

2015-01-01

Nuclear power plants (NPPs) are large installations comprised of many active and passive assets. Degradation monitoring of all these assets is expensive (labor cost) and highly demanding task. In this paper a framework based on Support Vector Regression (SVR) for online surveillance of critical parameter degradation of NPP components is proposed. In this case, on time replacement or maintenance of components will prevent potential plant malfunctions, and reduce the overall operational cost. In the current work, we apply SVR equipped with a Gaussian kernel function to monitor components. Monitoring includes the one-step-ahead prediction of the component's respective operational quantity using the SVR model, while the SVR model is trained using a set of previous recorded degradation histories of similar components. Predictive capability of the model is evaluated upon arrival of a sensor measurement, which is compared to the component failure threshold. A maintenance decision is based on a fuzzy inference system that utilizes three parameters: (i) prediction evaluation in the previous steps, (ii) predicted value of the current step, (iii) and difference of current predicted value with components failure thresholds. The proposed framework will be tested on turbine blade degradation data.

A holistic framework of degradation modeling for reliability analysis and maintenance optimization of nuclear safety systems

International Nuclear Information System (INIS)

Lin, Yanhui

2016-01-01

Components of nuclear safety systems are in general highly reliable, which leads to a difficulty in modeling their degradation and failure behaviors due to the limited amount of data available. Besides, the complexity of such modeling task is increased by the fact that these systems are often subject to multiple competing degradation processes and that these can be dependent under certain circumstances, and influenced by a number of external factors (e.g. temperature, stress, mechanical shocks, etc.). In this complicated problem setting, this PhD work aims to develop a holistic framework of models and computational methods for the reliability-based analysis and maintenance optimization of nuclear safety systems taking into account the available knowledge on the systems, degradation and failure behaviors, their dependencies, the external influencing factors and the associated uncertainties.The original scientific contributions of the work are: (1) For single components, we integrate random shocks into multi-state physics models for component reliability analysis, considering general dependencies between the degradation and two types of random shocks. (2) For multi-component systems (with a limited number of components):(a) a piecewise-deterministic Markov process modeling framework is developed to treat degradation dependency in a system whose degradation processes are modeled by physics-based models and multi-state models; (b) epistemic uncertainty due to incomplete or imprecise knowledge is considered and a finite-volume scheme is extended to assess the (fuzzy) system reliability; (c) the mean absolute deviation importance measures are extended for components with multiple dependent competing degradation processes and subject to maintenance; (d) the optimal maintenance policy considering epistemic uncertainty and degradation dependency is derived by combining finite-volume scheme, differential evolution and non-dominated sorting differential evolution; (e) the

Ligands specify estrogen receptor alpha nuclear localization and degradation

Directory of Open Access Journals (Sweden)

Caze-Subra Stéphanie

2010-12-01

Full Text Available Abstract Background The estrogen receptor alpha (ERα is found predominately in the nucleus, both in hormone stimulated and untreated cells. Intracellular distribution of the ERα changes in the presence of agonists but the impact of different antiestrogens on the fate of ERα is a matter of debate. Results A MCF-7 cell line stably expressing GFP-tagged human ERα (SK19 cell line was created to examine the localization of ligand-bound GFP-ERα. We combined digitonin-based cell fractionation analyses with fluorescence and immuno-electron microscopy to determine the intracellular distribution of ligand-bound ERα and/or GFP-ERα. Using fluorescence- and electron microscopy we demonstrate that both endogenous ERα and GFP-ERα form numerous nuclear focal accumulations upon addition of agonist, 17β-estradiol (E2, and pure antagonists (selective estrogen regulator disruptor; SERD, ICI 182,780 or RU58,668, while in the presence of partial antagonists (selective estrogen regulator modulator; SERM, 4-hydroxytamoxifen (OHT or RU39,411, diffuse nuclear staining persisted. Digitonin based cell fractionation analyses confirmed that endogenous ERα and GFP-ERα predominantly reside in the nuclear fraction. Overall ERα protein levels were reduced after estradiol treatment. In the presence of SERMs ERα was stabilized in the nuclear soluble fraction, while in the presence of SERDs protein levels decreased drastically and the remaining ERα was largely found in a nuclear insoluble fraction. mRNA levels of ESR1 were reduced compared to untreated cells in the presence of all ligands tested, including E2. E2 and SERDs induced ERα degradation occurred in distinct nuclear foci composed of ERα and the proteasome providing a simple explanation for ERα sequestration in the nucleus. Conclusions Our results indicate that chemical structure of ligands directly affect the nuclear fate and protein turnover of the estrogen receptor alpha independently of their impact on

A recommended approach for calculating degraded voltage relay setpoints for nuclear generating stations

International Nuclear Information System (INIS)

Jancauskas, J.R.

1994-01-01

The purpose of degrading voltage relays (DVRs) is to ensure that adequate voltage is available to operate all Class 1E loads at all voltage distribution levels. Should voltage drop below the setpoint of the DVRs, the Class 1E power system is disconnected from its supply and resequenced onto the diesel generators in order to restore system voltages to acceptable levels. These relays represent one of the two levels of voltage protection required for the onsite power system. Determining the proper setpoint for degraded voltage relays in nuclear generating stations is a complex task which requires a complete understanding of the Class 1E power distribution system. Despite the importance of degraded voltage relay setpoint calculations, most of the available references only give clues on how not to set these relays rather than provide guidance on how to determine the appropriate setpoint. This paper presents an approach for performing these calculations which attempts to ensure that all of the relevant design issues are addressed

13th International conference on environmental degradation of materials in nuclear power systems

International Nuclear Information System (INIS)

2007-01-01

The 13th International Conference on Environmental Degradation of Materials in Nuclear Power Systems was held on August 19-23, 2007 in Whistler, British Columbia, Canada. More of a scientific meeting than a convention, this conference series is the premier nuclear industry corrosion meeting where the 225 registrations consisted of world experts of the field from utilities, engineering and service organizations, manufacturers, research establishments and universities gathered to listen to 144 technical papers on new work and to explore new insights into corrosion mechanisms in the many water cooled systems in nuclear power plants. Over 225 delegates attended the conference, over 144 technical papers were presented in the following sessions: IASCC; Waste; PWR Secondary; Ni-Base Welds; Operating Experience; Low Alloy Steels; Alloy 800 Steam Generator Tubing; Zirconium Alloys; Crack Growth; SCWR; PWR Primary; BWR SCC; Irradiation Effects; Flow Accelerated Corrosion; and, Nobel Metal

Reviewing fluid systems for age-related degradation

International Nuclear Information System (INIS)

Smith, Stan

1991-01-01

Yankee Atomic Electric Company has developed the component degradation assessment tool (CoDAT), an expert system, that aids in handling and evaluating the large amounts of data required to support the license renewal process for nuclear power station fluid systems. In 1990, CoDAT evaluated the Yankee Nuclear Power Station fluid systems for age-related degradation. Its results are now being used to help focus the plant's maintenance programs and manage the expected degradation. CoDAT uses 'If-Then' rules, developed from industry codes, standards and publications, to determine the potential for 19 age-related degradation mechanisms. Other nuclear utilities pursuing the license renewal option also could use CoDAT. (author)

Some Materials Degradation Issues in the U.S. High-Level Nuclear Waste Repository Study (The Yucca Mountain Project)

Energy Technology Data Exchange (ETDEWEB)

F. Hua; P. Pasupathi; N. Brown; K. Mon

2005-09-19

The safe disposal of radioactive waste requires that the waste be isolated from the environment until radioactive decay has reduced its toxicity to innocuous levels for plants, animals, and humans. All of the countries currently studying the options for disposing of high-level nuclear waste (HLW) have selected deep geologic formations to be the primary barrier for accomplishing this isolation. In U.S.A., the Nuclear Waste Policy Act of 1982 (as amended in 1987) designated Yucca Mountain in Nevada as the potential site to be characterized for high-level nuclear waste (HLW) disposal. Long-term containment of waste and subsequent slow release of radionuclides into the geosphere will rely on a system of natural and engineered barriers including a robust waste containment design. The waste package design consists of a highly corrosion resistant Ni-based Alloy 22 cylindrical barrier surrounding a Type 316 stainless steel inner structural vessel. The waste package is covered by a mailbox-shaped drip shield composed primarily of Ti Grade 7 with Ti Grade 24 structural support members. The U.S. Yucca Mountain Project has been studying and modeling the degradation issues of the relevant materials for some 20 years. This paper reviews the state-of-the-art understanding of the degradation processes based on the past 20 years studies on Yucca Mountain Project (YMP) materials degradation issues with focus on interaction between the in-drift environmental conditions and long-term materials degradation of waste packages and drip shields within the repository system during the 10,000 years regulatory period. This paper provides an overview of the current understanding of the likely degradation behavior of the waste package and drip shield in the repository after the permanent closure of the facility. The degradation scenario discussed in this paper include aging and phase instability, dry oxidation, general and localized corrosion, stress corrosion cracking and hydrogen induced

Some Materials Degradation Issues in the U.S. High-Level Nuclear Waste Repository Study (The Yucca Mountain Project)

International Nuclear Information System (INIS)

Hua, F.; Pasupathi, P.; Brown, N.; Mon, K.

2005-01-01

The safe disposal of radioactive waste requires that the waste be isolated from the environment until radioactive decay has reduced its toxicity to innocuous levels for plants, animals, and humans. All of the countries currently studying the options for disposing of high-level nuclear waste (HLW) have selected deep geologic formations to be the primary barrier for accomplishing this isolation. In U.S.A., the Nuclear Waste Policy Act of 1982 (as amended in 1987) designated Yucca Mountain in Nevada as the potential site to be characterized for high-level nuclear waste (HLW) disposal. Long-term containment of waste and subsequent slow release of radionuclides into the geosphere will rely on a system of natural and engineered barriers including a robust waste containment design. The waste package design consists of a highly corrosion resistant Ni-based Alloy 22 cylindrical barrier surrounding a Type 316 stainless steel inner structural vessel. The waste package is covered by a mailbox-shaped drip shield composed primarily of Ti Grade 7 with Ti Grade 24 structural support members. The U.S. Yucca Mountain Project has been studying and modeling the degradation issues of the relevant materials for some 20 years. This paper reviews the state-of-the-art understanding of the degradation processes based on the past 20 years studies on Yucca Mountain Project (YMP) materials degradation issues with focus on interaction between the in-drift environmental conditions and long-term materials degradation of waste packages and drip shields within the repository system during the 10,000 years regulatory period. This paper provides an overview of the current understanding of the likely degradation behavior of the waste package and drip shield in the repository after the permanent closure of the facility. The degradation scenario discussed in this paper include aging and phase instability, dry oxidation, general and localized corrosion, stress corrosion cracking and hydrogen induced

Precision Diagnosis, Monitoring and Control of Structural Component Degradation in Nuclear Power Plants

International Nuclear Information System (INIS)

Han, J. H.; Choi, M. S.; Lee, D. H.; Hur, D. H.; Na, J. W.; Kim, K. M.; Hong, J. H.; Kim, H. S.

2007-06-01

The occurrence of structural material degradations in NPPs and their progress during operation are directly related to the safety and the integrity of NPPs. The various kinds of material degradation are usually examined by methods of material integrity evaluation and non-destructive evaluation(NDE). Material integrity evaluation is well known as classical method to interpret cause and mechanism of degradation and failure, however, this method has a limitation of detection and diagnosis for actual condition of flaws and defects occurring during plant operation, particularly for their formation in the early stage. NDE used widely for detection of defects formed on structural materials provides many information for safety regulation, plant management, repairing, however, this technique has a generic problem in its reliability due to low detectability and ability of signal analysis, etc. The objective of this research project is to develop the advanced technologies ensuring a precision diagnosis on the various kind of defects in structural materials of NPP and a high performance in material degradation evaluation. Many of the advanced technologies were developed in the 1st phase of this project. They contributed to interpret more precisely the root causes of degradation, failure and to establish the proper measures for the safety and integrity of NPPs. The accomplishment of comprehensive technology developed as planned will be practically applied to the nuclear industries and contributed to improve the safety and integrity of NPPs

A characterization of check valve degradation and failure experience in the nuclear power industry

International Nuclear Information System (INIS)

Casada, D.A.; Todd, M.D.

1993-09-01

Check valve operating problems in recent years have resulted in significant operating transients, increased cost and decreased system availability. As a result, additional attention has beau given to check valves by utilities (resulting in the formation of the Nuclear Industry Check Valve Group), as well as the US Nuclear Regulatory Commission and the American Society of Mechanical Engineers Operation and Maintenance Committee. All these organizations have the fundamental goal of ensuring reliable operation of check valves. A key ingredient to an engineering-oriented reliability improvement effort is a thorough understanding of relevant historical experience. A detailed review of historical failure data, available through the Institute of Nuclear Power Operation's Nuclear Plant Reliability Data System, has been conducted. The focus of the review is on check valve failures that have involved significant degradation of the valve internal parts. A variety of parameters are considered, including size, age, system of service, method of failure discovery, the affected valve parts, attributed causes, and corrective actions

Ageing degradation mechanisms in nuclear power plants: lessons learned from operating experience

International Nuclear Information System (INIS)

Bieth, M.; Zerger, B.; Duchac, A.

2014-01-01

This paper presents main results of a comprehensive study performed by the European Clearinghouse on Operating Experience Feedback of Nuclear Power Plants (NPP) with the support of IRSN (Institut de Surete Nucleaire et de Radioprotection) and GRS (Gesellschaft fuer Anlagen und Reaktorsicherheit mbH). Physical ageing mechanisms of Structures, Systems and Components (SSC) that eventually lead to ageing related systems and components failures at nuclear power plants were the main focus of this study. The analysis of ageing related events involved operating experience reported by NPP operators in France, Germany, USA and to the IAEA/NEA International Reporting System on operating experience for the past 20 years. A list of relevant ageing related events was populated. Each ageing related event contained in the list was analyzed and results of analysis were summarized for each ageing degradation mechanism which appeared to be the dominant contributor or direct cause. This paper provides insights into ageing related operating experience as well as recommendations to deal with the physical ageing of nuclear power plant SSC important to safety. (authors)

Evaluation of the degradation of the service water system in nuclear plants; Evaluacion de la degradacion del sistema de agua de servicio en plantas nucleares

Energy Technology Data Exchange (ETDEWEB)

Salaices A, E. [IIE, Av. Reforma 113, Col. Palmira, Cuernavaca, Morelos (Mexico)

2003-07-01

The service water system, the circulation water system, the cooling water system and the protection against fires system so much in nuclear plants as in fossils plants they are being degraded by a wide variety of mechanisms. These mechanisms include microbiologically influenced corrosion, cavitation, erosion-corrosion, erosion by solid particles, corrosion in cracks, stings, general corrosion, galvanic corrosion, sedimentation and obstructions and incrustations in the heat exchangers. In the last years were developed predictive models for the more common degradation forms and were installed in a new application of the CHECWORKS{sup TM} code called Cooling Water Application (CWA). This application of the code provides a new technology that so much nuclear facilities as fossil ones can use to modelling specific systems and to carry out corrosion predictions in each one of its components. Presently work the results of the employment of the CHECWORKS CWA code are described to carry out predictions of 12 different corrosion mechanisms that affect to the service water system of a nuclear plant, as well as the recommendations and options that the plant can to consider to reduce indexes of damages. This work can be used for to optimize inspections to the service water system and it gives the bases for similar changes in other nuclear plants. (Author)

Modelling of the degradation of cement in a nuclear waste repository

International Nuclear Information System (INIS)

Haworth, A.; Sharland, S.M.; Tweed, C.J.

1989-01-01

The current UK concept for a low- or intermediate-level nuclear waste repository includes a largely cementitious backfill. The cement provides a high pH environment in which the general corrosion rate of the metal canisters is reduced and the solubilities of many nuclides low. It has previously been assumed that this high pH will exist for a period of 10 7 years, however cement will degrade due to leaching of the solid components and attack from aqueous species in groundwater. In this paper the authors describe the preliminary stages of a model of the degradation of cement in a repository. The modelling involves the incorporation of a thermodynamic description of cement into the static code PHREEQE. This is then used in a coupled chemistry-transport model of simple leaching of cement using the code CHEQMATE. This preliminary modelling also provides a useful verification of CHEQMATE as a direct comparison with a THCCDM (a coupled code based on CHEMTRN) model is possible. Results from this preliminary model suggest that the fall in pH due to leaching is slow

CRM1-mediated nuclear export is required for 26 S proteasome-dependent degradation of the TRIP-Br2 proto-oncoprotein.

Science.gov (United States)

Cheong, Jit Kong; Gunaratnam, Lakshman; Hsu, Stephen I-Hong

2008-04-25

Overexpression of the proto-oncogene TRIP-Br2 (SERTAD2) has been shown to induce E2F activity and promote tumorigenesis, whereas ablation of TRIP-Br2 arrests cell proliferation. Timely degradation of many cell cycle regulators is fundamental to the maintenance of proper cell cycle progression. Here we report novel mechanism(s) that govern the tight regulation of TRIP-Br2 levels during cell cycle progression. TRIP-Br2 was observed to be a short-lived protein in which the expression level peaks at the G(1)/S boundary. TRIP-Br2 accumulated in cells treated with 26 S proteasome inhibitors. Co-immunoprecipitation studies revealed that TRIP-Br2 forms ubiquitin conjugates. In silico analysis identified a putative leucine-rich nuclear export signal (NES) motif that overlaps with the PHD-Bromo interaction domain in the acidic C-terminal transactivation domain (TAD) of TRIP-Br2. This NES motif is highly conserved in widely divergent species and in all TRIP-Br family members. TRIP-Br2 was shown to be stabilized in G(2)/M phase cells through nuclear entrapment, either by deletion of the acidic C-terminal TAD, which includes the NES motif, or by leptomycin B-mediated inhibition of the CRM1-dependent nuclear export machinery. Mutation of leucine residue 238 of this NES motif abolished the interaction between CRM1 and TRIP-Br2, as well as the nuclear export of TRIP-Br2 and its subsequent 26 S proteasome-dependent degradation. These data suggest that CRM1-mediated nuclear export may be required for the proper execution of ubiquitin-proteasome-dependent degradation of TRIP-Br2.

A High Integrity Can Design for Degraded Nuclear Fuel

International Nuclear Information System (INIS)

Holmes, P.A.

1999-01-01

A high integrity can (HIC), designed to meet the ASME Boiler and Pressure Vessel Code (Section III, Div. 3, static conditions) is proposed for the interim storage and repository disposal of Department of Energy (DOE) spent nuclear fuel. The HIC will be approximately 5 3/8 inches (134.38mm) in outside diameter with 1/4 inch (6.35mm) thick walls, and have a removable lid with a metallic seal that is capable of being welded shut. The opening of the can is approximately 4 3/8 inches (111.13mm). The HIC is primarily designed to contain items in the DOE SNF inventory that do not meet acceptance standards for direct disposal in a geologic repository. This includes fuel in the form of particulate dusts, sectioned pieces of fuel, core rubble, melted or degraded (non-intact) fuel elements, unclad uranium alloys, metallurgical specimens, and chemically reactive fuel components. The HIC is intended to act as a substitute cladding for the spent nuclear fuel, further isolate problematic materials, provide a long-term corrosion barrier, and add an extra internal pressure barrier to the waste package. The HIC will also delay potential fission product release and maintain geometry control for extended periods of time. For the entire disposal package to be licensed by the Nuclear Regulatory Commission, a HIC must effectively eliminate the disposal problems associated with problem SNF including the release of radioactive and/or reactive material and over pressurization of the HIC due to chemical reactions within the can. Two HICs were analyzed to envelop a range of can lengths between 42 and 101 inches. Using Abacus software, the HIC's were analyzed for end, side, and corner drops. Hastelloy C-22 was chosen based upon structural integrity, corrosion resistance, and neutron adsorption properties

Development of evaluation technique on ageing degradation of organic polymer in nuclear power plant

Energy Technology Data Exchange (ETDEWEB)

Kim, Ki Yup; Nho, Young Chang; Jung, Sung Hee; Park, Eun Hee

1999-03-01

Radiation degradation of chlorosulfonated polyethylene (CSPE, Hypalon), crosslinked polyethylene (XLPE), poly (tetrafluoroethylene) (PTFE), poly (vinylidene fluoride) (PVDF), and ethylene rubber (EPR) of experimental formulation as cable insulating and sheathing materials were performed by accelerated ageing tests and was investigated by measuring the properties such as tensile strength, elongation, insulation resistance, melting temperature, oxygen index and thermal stimulated current. The status of radiation ageing test was reviewed and the requirement of qualification of nuclear equipment was documented.

Development of evaluation technique on ageing degradation of organic polymer in nuclear power plant

International Nuclear Information System (INIS)

Kim, Ki Yup; Nho, Young Chang; Jung, Sung Hee; Park, Eun Hee

1999-03-01

Radiation degradation of chlorosulfonated polyethylene (CSPE, Hypalon), crosslinked polyethylene (XLPE), poly (tetrafluoroethylene) (PTFE), poly (vinylidene fluoride) (PVDF), and ethylene rubber (EPR) of experimental formulation as cable insulating and sheathing materials were performed by accelerated ageing tests and was investigated by measuring the properties such as tensile strength, elongation, insulation resistance, melting temperature, oxygen index and thermal stimulated current. The status of radiation ageing test was reviewed and the requirement of qualification of nuclear equipment was documented

Resolution of Generic Safety Issue 29: Bolting degradation or failure in nuclear power plants

International Nuclear Information System (INIS)

Johnson, R.E.

1990-06-01

This report describes the US Nuclear Regulatory Commission's (NRC's) Generic Safety Issue 29, ''Bolting Degradation or Failure in Nuclear Power Plants,'' including the bases for establishing the issue and its historical highlights. The report also describes the activities of the Atomic Industrial Forum (AIF) relevant to this issue, including its cooperation with the Materials Properties Council (MPC) to organize a task group to help resolve the issue. The Electric Power Research Institute, supported by the AIF/MPC task group, prepared and issued a two-volume document that provides, in part, the technical basis for resolving Generic Safety Issue 29. This report presents the NRC's review and evaluation of the two-volume document and NRC's conclusion that this document, in conjunction with other information from both industry and NRC, provides the bases for resolving this issue

Determination of possible damage/degradation of the Sandia National Laboratories Personal Nuclear Accident Dosimeter (PNAD)

International Nuclear Information System (INIS)

Potter, Charles Augustus; Ward, Dann C.

2008-01-01

This report describes the results of an inspection performed on the existing stock of SNL Personal Nuclear Accident Dosimeters (PNADs). The current stock is approximately 20 years old, and has not been examined since their initial acceptance. A small random sample of PNADs were opened (a destructive process) and the contents visually examined. Sample contents were not degraded and indicate that the existing stock of SNL PNADs is acceptable for continued use

A multivariate statistical methodology for detection of degradation and failure trends using nuclear power plant operational data

International Nuclear Information System (INIS)

Samanta, P.K.; Teichmann, T.

1990-01-01

In this paper, a multivariate statistical method is presented and demonstrated as a means for analyzing nuclear power plant transients (or events) and safety system performance for detection of malfunctions and degradations within the course of the event based on operational data. The study provides the methodology and illustrative examples based on data gathered from simulation of nuclear power plant transients (due to lack of easily accessible operational data). Such an approach, once fully developed, can be used to detect failure trends and patterns and so can lead to prevention of conditions with serious safety implications

Evaluation and mitigation of the degradation by corrosion in the components of the service water system of a nuclear power plant

International Nuclear Information System (INIS)

Salaices A, E.; Salaices, M.; Ovando, R.

2005-01-01

One of the main problems that face the nuclear power stations is the degradation by corrosion in the service water systems. The corrosion causes lost substantial in energy generation and a high cost in maintenance and repairs. In this work, the results of a study of the degradation by the MIC mechanisms (microorganisms influenced corrosion), incrustations in heat exchangers and erosion for solid particles in the components of a typical service water system of a nuclear plant are presented. Diverse mitigation options are analyzed for these mechanisms. In the analysis, it was used the CHECWORKS-CWA code to carry out the evaluation of the degradation so much as well as the mitigation of the caused damage. The results are presented in susceptibility indexes and degradation rates component-by-component. A significant decrement could be observed in the susceptibility to MIC when changing the operation conditions of stagnated flow to continuous flow. With respect to the erosion by solid particles, it was found a significant reduction of the damage it when adding filters to the system. Finally, in the case of the heat exchangers, it is shown that one of the more viable options to diminish incrustations and existent calcium deposits it is the reduction of the pH of the service water. (Author)

Long-Term Waste Package Degradation Studies at the Yucca Mountain Potential High-Level Nuclear Waste Repository

International Nuclear Information System (INIS)

Mon, K. G.; Bullard, B. E.; Longsine, D. E.; Mehta, S.; Lee, J. H.; Monib, A. M.

2002-01-01

The Site Recommendation (SR) process for the potential repository for spent nuclear fuel (SNF) and high-level nuclear waste (HLW) at Yucca Mountain, Nevada is underway. Fulfillment of the requirements for substantially complete containment of the radioactive waste emplaced in the potential repository and subsequent slow release of radionuclides from the Engineered Barrier System (EBS) into the geosphere will rely on a robust waste container design, among other EBS components. Part of the SR process involves sensitivity studies aimed at elucidating which model parameters contribute most to the drip shield and waste package degradation characteristics. The model parameters identified included (a) general corrosion rate model parameters (temperature-dependence and uncertainty treatment), and (b) stress corrosion cracking (SCC) model parameters (uncertainty treatment of stress and stress intensity factor profiles in the Alloy 22 waste package outer barrier closure weld regions, the SCC initiation stress threshold, and the fraction of manufacturing flaws oriented favorably for through-wall penetration by SCC). These model parameters were reevaluated and new distributions were generated. Also, early waste package failures due to improper heat treatment were added to the waste package degradation model. The results of these investigations indicate that the waste package failure profiles are governed by the manufacturing flaw orientation model parameters and models used

Detection of pump degradation

International Nuclear Information System (INIS)

Greene, R.H.; Casada, D.A.; Ayers, C.W.

1995-08-01

This Phase II Nuclear Plant Aging Research study examines the methods of detecting pump degradation that are currently employed in domestic and overseas nuclear facilities. This report evaluates the criteria mandated by required pump testing at U.S. nuclear power plants and compares them to those features characteristic of state-of-the-art diagnostic programs and practices currently implemented by other major industries. Since the working condition of the pump driver is crucial to pump operability, a brief review of new applications of motor diagnostics is provided that highlights recent developments in this technology. The routine collection and analysis of spectral data is superior to all other technologies in its ability to accurately detect numerous types and causes of pump degradation. Existing ASME Code testing criteria do not require the evaluation of pump vibration spectra but instead overall vibration amplitude. The mechanical information discernible from vibration amplitude analysis is limited, and several cases of pump failure were not detected in their early stages by vibration monitoring. Since spectral analysis can provide a wealth of pertinent information concerning the mechanical condition of rotating machinery, its incorporation into ASME testing criteria could merit a relaxation in the monthly-to-quarterly testing schedules that seek to verify and assure pump operability. Pump drivers are not included in the current battery of testing. Operational problems thought to be caused by pump degradation were found to be the result of motor degradation. Recent advances in nonintrusive monitoring techniques have made motor diagnostics a viable technology for assessing motor operability. Motor current/power analysis can detect rotor bar degradation and ascertain ranges of hydraulically unstable operation for a particular pump and motor set. The concept of using motor current or power fluctuations as an indicator of pump hydraulic load stability is presented

Detection of pump degradation

Energy Technology Data Exchange (ETDEWEB)

Greene, R.H.; Casada, D.A.; Ayers, C.W. [and others

1995-08-01

This Phase II Nuclear Plant Aging Research study examines the methods of detecting pump degradation that are currently employed in domestic and overseas nuclear facilities. This report evaluates the criteria mandated by required pump testing at U.S. nuclear power plants and compares them to those features characteristic of state-of-the-art diagnostic programs and practices currently implemented by other major industries. Since the working condition of the pump driver is crucial to pump operability, a brief review of new applications of motor diagnostics is provided that highlights recent developments in this technology. The routine collection and analysis of spectral data is superior to all other technologies in its ability to accurately detect numerous types and causes of pump degradation. Existing ASME Code testing criteria do not require the evaluation of pump vibration spectra but instead overall vibration amplitude. The mechanical information discernible from vibration amplitude analysis is limited, and several cases of pump failure were not detected in their early stages by vibration monitoring. Since spectral analysis can provide a wealth of pertinent information concerning the mechanical condition of rotating machinery, its incorporation into ASME testing criteria could merit a relaxation in the monthly-to-quarterly testing schedules that seek to verify and assure pump operability. Pump drivers are not included in the current battery of testing. Operational problems thought to be caused by pump degradation were found to be the result of motor degradation. Recent advances in nonintrusive monitoring techniques have made motor diagnostics a viable technology for assessing motor operability. Motor current/power analysis can detect rotor bar degradation and ascertain ranges of hydraulically unstable operation for a particular pump and motor set. The concept of using motor current or power fluctuations as an indicator of pump hydraulic load stability is presented.

Learning from nuclear regulatory self-assessment. International peer review of the CSN report on lessons learnt from the essential service water system degradation event at the Vandellos nuclear power plant

International Nuclear Information System (INIS)

2006-01-01

Nuclear regulatory self-assessment together with the benchmarking of regulatory practices against those of other countries operating nuclear power plants are key elements in maintaining a high level of nuclear safety. In that light, the Spanish Consejo de Seguridad Nuclear (CSN) formally asked the OECD Nuclear Energy Agency (NEA) to establish an international peer review team to assess the CSN report on the lessons learnt as a result of the 2004 Vandellos II event involving essential service water system degradation. The International Review Team considers the CSN report prepared in follow-up to the Vandellos event to be a commendable effort in regulatory self-assessment. The report, complemented by this international peer review, should enable the CSN to take appropriate action to ensure that its regulatory supervision is in line with best international practice. (authors)

TALSPEAK Solvent Degradation

Energy Technology Data Exchange (ETDEWEB)

Leigh R. Martin; Bruce J. Mincher

2009-09-01

Understanding the radiolytic degradation behavior of organic molecules involved in new or existing schemes for the recycle of used nuclear fuels is of significant interest for sustaining a closed nuclear fuel cycle. Here we have conducted several lines of investigation to begin understanding the effects of radiolysis on the aqueous phase of the TALSPEAK process for the separation of the trivalent lanthanides from the trivalent actinides. Using the 60-Co irradiator at the INL, we have begun to quantify the effects of radiation on the aqueous phase complexants used in this separation technique, and how this will affect the actinide lanthanide separation factor. In addition we have started to develop methodologies for stable product identification, a key element in determining the degradation pathways. We have also introduced a methodology to investigate the effects of alpha radiolysis that has previously received limited attention.

3'-5' RNA degradation pathways in human cells

DEFF Research Database (Denmark)

Lubas, Michal Szymon

RNA synthesis and degradation are key steps in the regulation of gene expression in all living organisms. During the course of his PhD studies, Michal Lubas centred his research on the nuclear and cytoplasmic RNA turnover of both noncoding and coding RNAs in human cells. His proteomic studies...... revealed the interaction network of the main 3'-5' RNA degradation machinery – the RNA exosome complex. One of the key findings was the identification and characterisation of the Nuclear Exosome Targeting (NEXT) complex, important for nuclear functions of the exosome. Michal Lubas also studied the role...

Degraded voltage protection at nuclear plant safety buses

International Nuclear Information System (INIS)

Haddad, S.Z.; Berger, W.E.

1989-01-01

This paper reviews the events that led to the NRC's degraded voltage protection requirement and outlines the related NRC positions. It describes problems that have occurred with the protection scheme and identifies the measures required to minimize the occurrence of these problems. The paper recommends new guidelines for degraded voltage protection and proposes a protection scheme logic that aims at enhancing the reliability of the safety systems

Stabilization and Degradation Mechanisms of Cytoplasmic Ataxin-1

Directory of Open Access Journals (Sweden)

Mayumi F. Kohiyama

2015-01-01

Full Text Available Aggregation-prone proteins in neurodegenerative disease disrupt cellular protein stabilization and degradation pathways. The neurodegenerative disease spinocerebellar ataxia type 1 (SCA1 is caused by a coding polyglutamine expansion in the Ataxin-1 gene ( ATXN1 , which gives rise to the aggregation-prone mutant form of ATXN1 protein. Cerebellar Purkinje neurons, preferentially vulnerable in SCA1, produce ATXN1 protein in both cytoplasmic and nuclear compartments. Cytoplasmic stabilization of ATXN1 by phosphorylation and 14-3-3-mediated mechanisms ultimately drive translocation of the protein to the nucleus where aggregation may occur. However, experimental inhibition of phosphorylation and 14-3-3 binding results in rapid degradation of ATXN1, thus preventing nuclear translocation and cellular toxicity. The exact mechanism of cytoplasmic ATXN1 degradation is currently unknown; further investigation of degradation may provide future therapeutic targets. This review examines the present understanding of cytoplasmic ATXN1 stabilization and potential degradation mechanisms during normal and pathogenic states.

DSNF AND OTHER WASTE FORM DEGRADATION ABSTRACTION

International Nuclear Information System (INIS)

CUNNANE, J.

2004-01-01

Several hundred distinct types of DOE-owned spent nuclear fuel (DSNF) may potentially be disposed in the Yucca Mountain repository. These fuel types represent many more types than can be viably individually examined for their effect on the Total System Performance Assessment for the License Application (TSPA-LA). Additionally, for most of these fuel types, there is no known direct experimental test data for the degradation and dissolution of the waste form in repository groundwaters. The approach used in the TSPA-LA model is, therefore, to assess available information on each of 11 groups of DSNF, and to identify a model that can be used in the TSPA-LA model without differentiating between individual codisposal waste packages containing different DSNF types. The purpose of this report is to examine the available data and information concerning the dissolution kinetics of DSNF matrices for the purpose of abstracting a degradation model suitable for use in describing degradation of the DSNF inventory in the Total System Performance Assessment for the License Application. The data and information and associated degradation models were examined for the following types of DSNF: Group 1--Naval spent nuclear fuel; Group 2--Plutonium/uranium alloy (Fermi 1 SNF); Group 3--Plutonium/uranium carbide (Fast Flux Test Facility-Test Fuel Assembly SNF); Group 4--Mixed oxide and plutonium oxide (Fast Flux Test Facility-Demonstration Fuel Assembly/Fast Flux Test Facility-Test Demonstration Fuel Assembly SNF); Group 5--Thorium/uranium carbide (Fort St. Vrain SNF); Group 6--Thorium/uranium oxide (Shippingport light water breeder reactor SNF); Group 7--Uranium metal (N Reactor SNF); Group 8--Uranium oxide (Three Mile Island-2 core debris); Group 9--Aluminum-based SNF (Foreign Research Reactor SNF); Group 10--Miscellaneous Fuel; and Group 11--Uranium-zirconium hydride (Training Research Isotopes-General Atomics SNF). The analyses contained in this document provide an ''upper-limit'' (i

15 years in promoting the use of isotopic and nuclear technique for combating land degradation and soil erosion: the contribution of the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture

Science.gov (United States)

Mabit, Lionel; Toloza, Arsenio; Heng, Lee

2017-04-01

The world population will exceed 9 billion by the year 2050 and food production will need to be approximately doubled to meet this crucial demand. Most of this increase will occur in developing countries, where the majority of the population depends on agriculture and their land for their livelihoods. Reports from the Intergovernmental Panel on Climate Change (IPCC) predicted negative impact of climate change, threatening global food security. In addition, the intensification of agricultural activities has increased pressure on land and water resources, resulting in different forms of soil degradation, of which soil erosion and associated sedimentation are worsening. Worldwide economic costs of agricultural soil loss and associated sedimentation downstream have been estimated at US 400 billion per year. As a result of climate change, world average soil erosion is expected to further increase significantly. Adapting to climate change requires agricultural soil and water management practices that make agricultural production systems resilient to drought, floods and land degradation, to enhance the conservation of the natural resource base for sustainable upland farming. These current concerns with ensuring sustainable use and management of agroecosystems create an urgent need for reliable quantitative data on the extent and magnitude of soil resource degradation over several spatial and time scales to formulate sound policies and management measures. Integrated isotopic approaches can help in targeting adapted and effective soil-water conservation measures to control soil degradation and therefore contribute to positive feedback mechanisms to mitigate climate change impact on soil and water resources. Set up 60 years ago as the world's centre for cooperation in the nuclear field, the International Atomic Energy Agency (IAEA) promotes the safe, secure and peaceful use of nuclear technologies. Since the end of the 1990s, the Joint FAO/IAEA Division of Nuclear

Degradation of fastener in reactor internal of PWR

Energy Technology Data Exchange (ETDEWEB)

Kim, D. W.; Ryu, W. S.; Jang, J. S.; Kim, S. H.; Kim, W. G.; Chung, M. K.; Han, C. H

2000-03-01

Main component degraded in reactor internal structure of PWR is fastener such as bolts, stud, cap screw, and pins. The failure of these components may damage nuclear fuel and limits the operation of nuclear reactor. In foreign reactors operated more than 10 years, an increasing number of incidents of degraded thread fasteners have been reported. The degradation of these components impair the integrity of reactor internal structure and limit the life extension of nuclear power plant. To solve the problem of fastener failure, the incidents of failure and main mechanisms should be investigated. the purpose of this state-of-the -art report is to investigate the failure incidents and mechanisms of fastener in foreign and domestic PWR and make a guide to select a proper materials. There is no intent to describe each event in detail in this report. This report covers the failures of fastener and damage mechanisms reported by the licensees of operating nuclear power plants and the applications of plants constructed after 1964. This information is derived from pertinent licensee event report, reportable occurrence reports, operating reactor event memoranda, failure analysis reports, and other relevant documents. (author)

DSNF AND OTHER WASTE FORM DEGRADATION ABSTRACTION

Energy Technology Data Exchange (ETDEWEB)

J. CUNNANE

2004-11-19

Several hundred distinct types of DOE-owned spent nuclear fuel (DSNF) may potentially be disposed in the Yucca Mountain repository. These fuel types represent many more types than can be viably individually examined for their effect on the Total System Performance Assessment for the License Application (TSPA-LA). Additionally, for most of these fuel types, there is no known direct experimental test data for the degradation and dissolution of the waste form in repository groundwaters. The approach used in the TSPA-LA model is, therefore, to assess available information on each of 11 groups of DSNF, and to identify a model that can be used in the TSPA-LA model without differentiating between individual codisposal waste packages containing different DSNF types. The purpose of this report is to examine the available data and information concerning the dissolution kinetics of DSNF matrices for the purpose of abstracting a degradation model suitable for use in describing degradation of the DSNF inventory in the Total System Performance Assessment for the License Application. The data and information and associated degradation models were examined for the following types of DSNF: Group 1--Naval spent nuclear fuel; Group 2--Plutonium/uranium alloy (Fermi 1 SNF); Group 3--Plutonium/uranium carbide (Fast Flux Test Facility-Test Fuel Assembly SNF); Group 4--Mixed oxide and plutonium oxide (Fast Flux Test Facility-Demonstration Fuel Assembly/Fast Flux Test Facility-Test Demonstration Fuel Assembly SNF); Group 5--Thorium/uranium carbide (Fort St. Vrain SNF); Group 6--Thorium/uranium oxide (Shippingport light water breeder reactor SNF); Group 7--Uranium metal (N Reactor SNF); Group 8--Uranium oxide (Three Mile Island-2 core debris); Group 9--Aluminum-based SNF (Foreign Research Reactor SNF); Group 10--Miscellaneous Fuel; and Group 11--Uranium-zirconium hydride (Training Research Isotopes-General Atomics SNF). The analyses contained in this document provide an &apos

Technical evaluation report on the proposed design modifications and technical-specification changes on grid voltage degradation for the San Onofre Nuclear Genetating Station, Unit 1

International Nuclear Information System (INIS)

Selan, J.C.

1982-01-01

This report documents the technical evaluation of the proposed design modifications and Technical Specification changes for protection of Class 1E equipment from grid voltage degradation for the San Onofre Nuclear Generating Station, Unit 1. The review criteria are based on several IEEE standards and the Code of Federal Regulations. The evaluation finds that the proposed design modifications and Technical Specification changes will ensure that the Class 1E equipment will be protected from sustained voltage degradation

Technical evaluation report on the proposed design modifications and technical specification changes on grid voltage degradation for the Millstone Nuclear Power Station, Unit 1

International Nuclear Information System (INIS)

Selan, J.C.

1982-01-01

This report documents the technical evaluation of the proposed design modifications and Technical Specification change for protection of Class 1E equipment from grid voltage degradation for the Millstone Nuclear Power Station, Unit 1. The review criteria are based on several IEEE standards and the Code of Federal Regulations. The evaluation finds that the licensee has not provided sufficient information on the undervoltage protection system to allow a complete evaluation into the adequacy of protecting the Class 1E equipment from sustained voltage degradation

The Arabidopsis CROWDED NUCLEI genes regulate seed germination by modulating degradation of ABI5 protein.

Science.gov (United States)

Zhao, Wenming; Guan, Chunmei; Feng, Jian; Liang, Yan; Zhan, Ni; Zuo, Jianru; Ren, Bo

2016-07-01

In Arabidopsis, the phytohormone abscisic acid (ABA) plays a vital role in inhibiting seed germination and in post-germination seedling establishment. In the ABA signaling pathway, ABI5, a basic Leu zipper transcription factor, has important functions in the regulation of seed germination. ABI5 protein localizes in nuclear bodies, along with AFP, COP1, and SIZ1, and was degraded through the 26S proteasome pathway. However, the mechanisms of ABI5 nuclear body formation and ABI5 protein degradation remain obscure. In this study, we found that the Arabidopsis CROWDED NUCLEI (CRWN) proteins, predicted nuclear matrix proteins essential for maintenance of nuclear morphology, also participate in ABA-controlled seed germination by regulating the degradation of ABI5 protein. During seed germination, the crwn mutants are hypersensitive to ABA and have higher levels of ABI5 protein compared to wild type. Genetic analysis suggested that CRWNs act upstream of ABI5. The observation that CRWN3 colocalizes with ABI5 in nuclear bodies indicates that CRWNs might participate in ABI5 protein degradation in nuclear bodies. Moreover, we revealed that the extreme C-terminal of CRWN3 protein is necessary for its function in the response to ABA in germination. Our results suggested important roles of CRWNs in ABI5 nuclear body organization and ABI5 protein degradation during seed germination. © 2015 Institute of Botany, Chinese Academy of Sciences.

Steam Generator Analysis Tools and Modeling of Degradation Mechanisms

International Nuclear Information System (INIS)

Yetisir, M.; Pietralik, J.; Tapping, R.L.

2004-01-01

The degradation of steam generators (SGs) has a significant effect on nuclear heat transport system effectiveness and the lifetime and overall efficiency of a nuclear power plant. Hence, quantification of the effects of degradation mechanisms is an integral part of a SG degradation management strategy. Numerical analysis tools such as THIRST, a 3-dimensional (3D) thermal hydraulics code for recirculating SGs; SLUDGE, a 3D sludge prediction code; CHECWORKS a flow-accelerated corrosion prediction code for nuclear piping, PIPO-FE, a SG tube vibration code; and VIBIC and H3DMAP, 3D non-linear finite-element codes to predict SG tube fretting wear can be used to assess the impacts of various maintenance activities on SG thermal performance. These tools are also found to be invaluable at the design stage to influence the design by determining margins or by helping the designers minimize or avoid known degradation mechanisms. In this paper, the aforementioned numerical tools and their application to degradation mechanisms in CANDU recirculating SGs are described. In addition, the following degradation mechanisms are identified and their effect on SG thermal efficiency and lifetime are quantified: primary-side fouling, secondary-side fouling, fretting wear, and flow-accelerated corrosion (FAC). Primary-side tube inner diameter fouling has been a major contributor to SG thermal degradation. Using the results of thermalhydraulic analysis and field data, fouling margins are calculated. Individual effects of primary- and secondary-side fouling are separated through analyses, which allow station operators to decide what type of maintenance activity to perform and when to perform the maintenance activity. Prediction of the fretting-wear rate of tubes allows designers to decide on the number and locations of support plates and U-bend supports. The prediction of FAC rates for SG internals allows designers to select proper materials, and allows operators to adjust the SG maintenance

Modeling the degradation of nuclear components

International Nuclear Information System (INIS)

Stock, D.; Samanta, P.; Vesely, W.

1993-01-01

This paper describes component level reliability models that use information on degradation to predict component reliability, and which have been used to evaluate different maintenance and testing policies. The models are based on continuous time Markov processes, and are a generalization of reliability models currently used in Probabilistic Risk Assessment. An explanation of the models, the model parameters, and an example of how these models can be used to evaluate maintenance policies are discussed

Clad Degradation - FEPs Screening Arguments

International Nuclear Information System (INIS)

E. Siegmann

2004-01-01

The purpose of this report is to document the screening of the cladding degradation features, events, and processes (FEPs) for commercial spent nuclear fuel (CSNF). This report also addresses the effect of some FEPs on both the cladding and the CSNF, DSNF, and HLW waste forms where it was considered appropriate to address the effects on both materials together. This report summarizes the work of others to screen clad degradation FEPs in a manner consistent with, and used in, the Total System Performance Assessment-License Application (TSPA-LA). This document was prepared according to ''Technical Work Plan for Waste Form Degradation Modeling, Testing, and Analyses in Support of LA'' (BSC 2004a [DIRS 167796])

Nuclear plant license renewal

International Nuclear Information System (INIS)

Gazda, P.A.; Bhatt, P.C.

1991-01-01

During the next 10 years, nuclear plant license renewal is expected to become a significant issue. Recent Electric Power Research Institute (EPRI) studies have shown license renewal to be technically and economically feasible. Filing an application for license renewal with the Nuclear Regulatory Commission (NRC) entails verifying that the systems, structures, and components essential for safety will continue to perform their safety functions throughout the license renewal period. This paper discusses the current proposed requirements for this verification and the current industry knowledge regarding age-related degradation of structures. Elements of a license renewal program incorporating NRC requirements and industry knowledge including a schedule are presented. Degradation mechanisms for structural components, their significance to nuclear plant structures, and industry-suggested age-related degradation management options are also reviewed

DSNF AND OTHER WASTE FORM DEGRADATION ABSTRACTION

International Nuclear Information System (INIS)

Thornton, T.A.

2000-01-01

The purpose of this analysis/model report (AMR) is to select and/or abstract conservative degradation models for DOE-(US. Department of Energy) owned spent nuclear fuel (DSNF) and the immobilized ceramic plutonium (Pu) disposition waste forms for application in the proposed monitored geologic repository (MGR) postclosure Total System Performance Assessment (TSPA). Application of the degradation models abstracted herein for purposes other than TSPA should take into consideration the fact that they are, in general, very conservative. Using these models, the forward reaction rate for the mobilization of radionuclides, as solutes or colloids, away from the waste fondwater interface by contact with repository groundwater can then be calculated. This forward reaction rate generally consists of the dissolution reaction at the surface of spent nuclear fuel (SNF) in contact with water, but the degradation models, in some cases, may also include and account for the physical disintegration of the SNF matrix. The models do not, however, account for retardation, precipitation, or inhibition of the migration of the mobilized radionuclides in the engineered barrier system (EBS). These models are based on the assumption that all components of the DSNF waste form are released congruently with the degradation of the matrix

DSNF and other waste form degradation abstraction

Energy Technology Data Exchange (ETDEWEB)

Thornton, Thomas A.

2000-12-20

The purpose of this analysis/model report (AMR) is to select and/or abstract conservative degradation models for DOE-(US. Department of Energy) owned spent nuclear fuel (DSNF) and the immobilized ceramic plutonium (Pu) disposition waste forms for application in the proposed monitored geologic repository (MGR) postclosure Total System Performance Assessment (TSPA). Application of the degradation models abstracted herein for purposes other than TSPA should take into consideration the fact that they are, in general, very conservative. Using these models, the forward reaction rate for the mobilization of radionuclides, as solutes or colloids, away from the waste fondwater interface by contact with repository groundwater can then be calculated. This forward reaction rate generally consists of the dissolution reaction at the surface of spent nuclear fuel (SNF) in contact with water, but the degradation models, in some cases, may also include and account for the physical disintegration of the SNF matrix. The models do not, however, account for retardation, precipitation, or inhibition of the migration of the mobilized radionuclides in the engineered barrier system (EBS). These models are based on the assumption that all components of the DSNF waste form are released congruently with the degradation of the matrix.

Waste degradation and mobilization in performance assessments for the Yucca Mountain disposal system for spent nuclear fuel and high-level radioactive waste

International Nuclear Information System (INIS)

Rechard, Rob P.; Stockman, Christine T.

2014-01-01

This paper summarizes modeling of waste degradation and mobilization in performance assessments (PAs) conducted between 1984 and 2008 to evaluate feasibility, viability, and assess compliance of a repository for spent nuclear fuel and high-level radioactive waste at Yucca Mountain in southern Nevada. As understanding of the Yucca Mountain disposal system increased, the waste degradation module, or succinctly called the source-term, evolved from initial assumptions in 1984 to results based on process modeling in 2008. In early PAs, waste degradation had significant influence on calculated behavior but as the robustness of the waste container was increased and modeling of the container degradation improved, waste degradation had much less influence in later PAs. The variation of dissolved concentrations of radionuclides progressed from simple probability distributions in early PAs to functions dependent upon water chemistry in later PAs. Also, transport modeling of radionuclides in the waste, container, and invert were added in 1995; and, colloid-facilitated transport of radionuclides was added in 1998. - Highlights: • Progression of modeling of waste degradation in performance assessments is discussed for the proposed repository at Yucca Mountain. • Progression of evaluating dissolved concentrations of radionuclides in the source-term is discussed. • Radionuclide transport modeling in the waste, container, and invert in 1995 and thereafter is discussed. • Colloid-facilitated transport in the waste, container, and invert in 1998 and thereafter is discussed

Aminopeptidase-resistant peptides are targeted to lysosomes and subsequently degraded

NARCIS (Netherlands)

Gillis, Judith M.; Benckhuijsen, Willemien; van Veen, Henk; Sanz, Alicia Sanz; Drijfhout, Jan W.; Reits, Eric A.

2011-01-01

Most cytoplasmic and nuclear proteins are degraded via the ubiquitin-proteasome system into peptides, which are subsequently hydrolyzed by downstream aminopeptidases. Inefficient degradation can lead to accumulation of protein fragments, and subsequent aggregation and toxicity. Whereas the role of

An overview of environmental degradation of materials in nuclear power plant piping systems

International Nuclear Information System (INIS)

Shack, W.J.

1988-01-01

Several types of environmental degradation of piping in light water reactor (LWR) power systems have already had significant economic impact on the industry. These include intergranular stress corrosion cracking (IGSCC) of austenitic stainless steel piping, erosion-corrosion of carbon steel piping in secondary systems, and a variety of types of fatigue failures. In addition, other problems have been identified that must be addressed in considering extended lifetimes for nuclear plants. These include the embrittlement of cast stainless steels after extended thermal aging at reactor operating temperatures and the effect of reactor environments on the design margin inherent in the ASME Section III fatigue design curves especially for carbon steel piping. These problems are being addressed by wide-ranging research programs in this country and abroad. The purpose of this review is to highlight some of the accomplishments of these programs and to note some of the remaining unanswered questions

Use of nuclear fusion systems for spent nuclear fuel degradation

International Nuclear Information System (INIS)

Nieto, M.; Ramos, G.; Herrera V, J. J. E.

2009-10-01

One of the severe problems of the nuclear industry that should be resolved to facilitate its acceptance like viable energy alternative is of the wastes. In spite of having alternative of fuel reprocessing, many of them have been abandoned by economic or security reasons. In the present work, the alternative is described for using reactors of nuclear fusion as sources of fast neutrons with two important applications in mind: the plutonium burning and the transmutation of the elements that contribute in way more important to their radioactivity, mainly the smaller actinides and the fission products of long half life. (Author)

DOCUMENTATION OF NATIONAL WEATHER CONDITIONS AFFECTING LONG-TERM DEGRADATION OF COMMERCIAL SPENT NUCLEAR FUEL AND DOE SPENT NUCLEAR FUEL AND HIGH-LEVEL WASTE

International Nuclear Information System (INIS)

W. L. Poe, Jr.; P.F. Wise

1998-01-01

The U.S. Department of Energy (DOE) is preparing a proposal to construct, operate 2nd monitor, and eventually close a repository at Yucca Mountain in Nye County, Nevada, for the geologic disposal of spent nuclear fuel (SNF) and high-level radioactive waste (HLW). As part of this effort, DOE has prepared a viability assessment and an assessment of potential consequences that may exist if the repository is not constructed. The assessment of potential consequences if the repository is not constructed assumes that all SNF and HLW would be left at the generator sites. These include 72 commercial generator sites (three commercial facility pairs--Salem and Hope Creek, Fitzpatrick and Nine Mile Point, and Dresden and Morris--would share common storage due to their close proximity to each other) and five DOE sites across the country. DOE analyzed the environmental consequences of the effects of the continued storage of these materials at these sites in a report titled Continued Storage Analysis Report (CSAR; Reference 1 ) . The CSAR analysis includes a discussion of the degradation of these materials when exposed to the environment. This document describes the environmental parameters that influence the degradation analyzed in the CSAR. These include temperature, relative humidity, precipitation chemistry (pH and chemical composition), annual precipitation rates, annual number of rain-days, and annual freeze/thaw cycles. The document also tabulates weather conditions for each storage site, evaluates the degradation of concrete storage modules and vaults in different regions of the country, and provides a thermal analysis of commercial SNF in storage

STRUCTURAL PERFORMANCE OF DEGRADED REINFORCED CONCRETE MEMBERS

International Nuclear Information System (INIS)

Braverman, J.I.; Miller, C.A.; Ellingwood, B.R.; Naus, D.J.; Hofmayer, C.H.; Bezler, P.; Chang, T.Y.

2001-01-01

This paper describes the results of a study to evaluate, in probabilistic terms, the effects of age-related degradation on the structural performance of reinforced concrete members at nuclear power plants. The paper focuses on degradation of reinforced concrete flexural members and shear walls due to the loss of steel reinforcing area and loss of concrete area (cracking/spalling). Loss of steel area is typically caused by corrosion while cracking and spalling can be caused by corrosion of reinforcing steel, freeze-thaw, or aggressive chemical attack. Structural performance in the presence of uncertainties is depicted by a fragility (or conditional probability of failure). The effects of degradation on the fragility of reinforced concrete members are calculated to assess the potential significance of various levels of degradation. The fragility modeling procedures applied to degraded concrete members can be used to assess the effects of degradation on plant risk and can lead to the development of probability-based degradation acceptance limits

Prefoldins Negatively Regulate Cold Acclimation in Arabidopsis thaliana by Promoting Nuclear Proteasome-Mediated HY5 Degradation.

Science.gov (United States)

Perea-Resa, Carlos; Rodríguez-Milla, Miguel A; Iniesto, Elisa; Rubio, Vicente; Salinas, Julio

2017-06-05

The process of cold acclimation is an important adaptive response whereby many plants from temperate regions increase their freezing tolerance after being exposed to low non-freezing temperatures. The correct development of this response relies on proper accumulation of a number of transcription factors that regulate expression patterns of cold-responsive genes. Multiple studies have revealed a variety of molecular mechanisms involved in promoting the accumulation of these transcription factors. Interestingly, however, the mechanisms implicated in controlling such accumulation to ensure their adequate levels remain largely unknown. In this work, we demonstrate that prefoldins (PFDs) control the levels of HY5, an Arabidopsis transcription factor with a key role in cold acclimation by activating anthocyanin biosynthesis, in response to low temperature. Our results show that, under cold conditions, PFDs accumulate into the nucleus through a DELLA-dependent mechanism, where they interact with HY5, triggering its ubiquitination and subsequent degradation. The degradation of HY5 would result, in turn, in anthocyanin biosynthesis attenuation, ensuring the accurate development of cold acclimation. These findings uncover an unanticipated nuclear function for PFDs in plant responses to abiotic stresses. Copyright © 2017 The Author. Published by Elsevier Inc. All rights reserved.

Nuclear plant aging research program

International Nuclear Information System (INIS)

Eissenberg, D.M.

1987-01-01

The U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, has established the Nuclear Plant Aging Research (NPAR) program in its Division of Engineering Technology. Principal contractors for this program include Oak Ridge National Laboratory, Brookhaven National Laboratory, Idaho National Engineering Laboratory, and Pacific Northwest Laboratory. The program goals are: to identify and characterize time-dependent degradation (aging) of nuclear plant safety-related electrical and mechanical components which could lead to loss of safety function; to identify and recommend methods for detecting and trending aging effects prior to loss of safety function so that timely maintenance can be implemented; and to recommend maintenance practices for mitigating the effects of aging. Research activities include prioritization of system and component aging in nuclear plants, characterization of aging degradation of specific components including identification of functional indicators useful for trending degradation, and testing of practical methods and devices for measuring the functional indicators. Aging assessments have been completed on electric motors, snubbers, motor-operated valves, and check valves. Testing of trending methods and devices for motor-operated valves and check valves is in progress

A ΩXaV motif in the Rift Valley fever virus NSs protein is essential for degrading p62, forming nuclear filaments and virulence.

Science.gov (United States)

Cyr, Normand; de la Fuente, Cynthia; Lecoq, Lauriane; Guendel, Irene; Chabot, Philippe R; Kehn-Hall, Kylene; Omichinski, James G

2015-05-12

Rift Valley fever virus (RVFV) is a single-stranded RNA virus capable of inducing fatal hemorrhagic fever in humans. A key component of RVFV virulence is its ability to form nuclear filaments through interactions between the viral nonstructural protein NSs and the host general transcription factor TFIIH. Here, we identify an interaction between a ΩXaV motif in NSs and the p62 subunit of TFIIH. This motif in NSs is similar to ΩXaV motifs found in nucleotide excision repair (NER) factors and transcription factors known to interact with p62. Structural and biophysical studies demonstrate that NSs binds to p62 in a similar manner as these other factors. Functional studies in RVFV-infected cells show that the ΩXaV motif is required for both nuclear filament formation and degradation of p62. Consistent with the fact that the RVFV can be distinguished from other Bunyaviridae-family viruses due to its ability to form nuclear filaments in infected cells, the motif is absent in the NSs proteins of other Bunyaviridae-family viruses. Taken together, our studies demonstrate that p62 binding to NSs through the ΩXaV motif is essential for degrading p62, forming nuclear filaments and enhancing RVFV virulence. In addition, these results show how the RVFV incorporates a simple motif into the NSs protein that enables it to functionally mimic host cell proteins that bind the p62 subunit of TFIIH.

Rapid quantification of TBP and TBP degradation product ratios by FTIR-ATR

International Nuclear Information System (INIS)

Gillens, A.R.; Powell, B.A.; Clemson University, Clemson, SC

2013-01-01

Tri-n-butyl phosphate (TBP) is the key complexant within the plutonium and uranium reduction extraction process used to extract uranium and plutonium from used nuclear fuel. During reprocessing TBP degrades to dibutyl phosphate (DBP), butyl acid phosphate (MBP), butanol, and phosphoric acid over time. A method for rapidly monitoring TBP degradation is needed for the support of nuclear forensics. Therefore, a Fourier transform infrared spectrometry-attenuated total reflectance (FTIR-ATR) technique was developed to determine approximate peak intensity ratios of TBP and its degradation products. The technique was developed by combining variable concentrations of TBP, DBP, and MBP to simulate TBP degradation. This method is achieved by analyzing selected peak positions and peak intensity ratios of TBP and DBP at different stages of degradation. The developed technique was tested on TBP samples degraded with nitric acid. In mock degradation samples, the 1,235 cm -1 peak position shifts to 1,220 cm -1 as the concentration of TBP decreases and DBP increases. Peak intensity ratios of TBP positions at 1,279 and 1,020 cm -1 relative to DBP positions at 909 and 1,003 cm -1 demonstrate an increasing trend as the concentration of DBP increases. The same peak intensity ratios were used to analyze DBP relative to MBP whereas a decreasing trend is seen with increasing DBP concentrations. The technique developed from this study may be used as a tool to determine TBP degradation in nuclear reprocessing via a rapid FTIR-ATR measurement without gas chromatography analysis. (author)

Degradation of organochloride pesticides by molten salt oxidation at IPEN: spin-off nuclear activities

International Nuclear Information System (INIS)

Lainetti, Paulo E.O.

2013-01-01

Nuclear spin-off has at least two dimensions. It may provide benefits to the society such as enlarge knowledge base, strengthen infrastructure and benefit technology development. Besides this, to emphasize that some useful technologies elapsed from nuclear activities can affect favorably the public opinion about nuclear energy. In this paper is described a technology developed initially by the Rockwell Int. company in the USA more than thirty years ago to solve some problems of nuclear fuel cycle wastes. For different reasons the technology was not employed. In the last years the interest in the technology was renewed and IPEN has developed his version of the method applicable mainly to the safe degradation of hazardous wastes. This study was motivated by the world interest in the development of advanced processes of waste decomposition, due to the need of safer decomposition processes, particularly for the POPs - persistent organic pollutants and particularly for the organ chlorides. A tendency observed at several countries is the adoption of progressively more demanding legislation for the atmospheric emissions, resultants of the waste decomposition processes. The suitable final disposal of hazardous organic wastes such as PCBs (polychlorinated biphenyls), pesticides, herbicides and hospital residues constitutes a serious problem. In some point of their life cycles, these wastes should be destroyed, in reason of the risk that they represent for the human being, animals and plants. The process involves using a chemical reactor containing molten salts, sodium carbonate or some alkaline carbonates mixtures to decompose the organic waste. The decomposition is performed by submerged oxidation and the residue is injected below the surface of a turbulent salt bath along with the oxidizing agent. Decomposition of halogenated compounds, among which some pesticides, is particularly effective in molten salts. The process presents properties such as intrinsically safe

Some scenarios of degradation of concrete structures that are used as protective barriers in nuclear power industry

International Nuclear Information System (INIS)

Vasil'chenko, V.N.; Zhigalov, Ya.A.; Sandul, G.A.; Nosovskij, A.V.

2013-01-01

The articles discusses kinetics of physical and chemical processes of destruction of the material for reinforced concrete containers that are used as protective (safety) barriers in the nuclear power industry. Characteristics of constructive concrete materials were analyzed and generalized, including those for manufacturing of RAW containers. Some chemical reactions and mechanisms are considered that have an influence on the strength properties of the containers material. Kinetics of the degradation processes in the concrete of RAW containers was studied and the analysis was made on concentration dynamics of the local destruction centers in the concrete due to influence of the considered physical and chemical processes during the operation.

HYDRIDE-RELATED DEGRADATION OF SNF CLADDING UNDER REPOSITORY CONDITIONS

International Nuclear Information System (INIS)

McCoy, K.

2000-01-01

The purpose and scope of this analysis/model report is to analyze the degradation of commercial spent nuclear fuel (CSNF) cladding under repository conditions by the hydride-related metallurgical processes, such as delayed hydride cracking (DHC), hydride reorientation and hydrogen embrittlement, thereby providing a better understanding of the degradation process and clarifying which aspects of the process are known and which need further evaluation and investigation. The intended use is as an input to a more general analysis of cladding degradation

Evaluation and mitigation of the degradation by corrosion in the components of the service water system of a nuclear power plant; Evaluacion y mitigacion de la degradacion por corrosion en los componentes del sistema de agua de servicio de una planta nuclear

Energy Technology Data Exchange (ETDEWEB)

Salaices A, E.; Salaices, M.; Ovando, R. [IIE, Av. Reforma 113 Col. Palmira, 62490 Cuernavaca, Morelos (Mexico)]. e-mail: sal@iie.org.mx

2005-07-01

One of the main problems that face the nuclear power stations is the degradation by corrosion in the service water systems. The corrosion causes lost substantial in energy generation and a high cost in maintenance and repairs. In this work, the results of a study of the degradation by the MIC mechanisms (microorganisms influenced corrosion), incrustations in heat exchangers and erosion for solid particles in the components of a typical service water system of a nuclear plant are presented. Diverse mitigation options are analyzed for these mechanisms. In the analysis, it was used the CHECWORKS-CWA code to carry out the evaluation of the degradation so much as well as the mitigation of the caused damage. The results are presented in susceptibility indexes and degradation rates component-by-component. A significant decrement could be observed in the susceptibility to MIC when changing the operation conditions of stagnated flow to continuous flow. With respect to the erosion by solid particles, it was found a significant reduction of the damage it when adding filters to the system. Finally, in the case of the heat exchangers, it is shown that one of the more viable options to diminish incrustations and existent calcium deposits it is the reduction of the pH of the service water. (Author)

Sleeve type repair of degraded nuclear steam generator tubes

International Nuclear Information System (INIS)

Ayres, P.S.; Stark, L.E.; Feldstein, J.G.; Fu, T.

1986-01-01

A sealable sleeve is described for insertion into the repair of a degraded tube which consists of: a hollow core inner member of the same material as the degraded tube; a thinner outer member of substantially pure nickel and resistant to corrosive attack, the outer member being metallurgically bonded with the inner member; an expanded portion of the sleeve at one end for positioning in the tube within a tube sheet; a multiplicity of grooves formed in and adjacent to the other end of the sleeve which extends into the free-standing portion of the tube beyond the tube sheet, and a noble metal braze material contained in the grooves

Materials Degradation in Light Water Reactors: Life After 60,

International Nuclear Information System (INIS)

Busby, Jeremy T; Nanstad, Randy K; Stoller, Roger E; Feng, Zhili; Naus, Dan J

2008-01-01

Nuclear reactors present a very harsh environment for components service. Components within a reactor core must tolerate high temperature water, stress, vibration, and an intense neutron field. Degradation of materials in this environment can lead to reduced performance, and in some cases, sudden failure. A recent EPRI-led study interviewed 47 US nuclear utility executives to gauge perspectives on long-term operation of nuclear reactors. Nearly 90% indicated that extensions of reactor lifetimes to beyond 60 years were likely. When polled on the most challenging issues facing further life extension, two-thirds cited plant reliability as the key issue with materials aging and cable/piping as the top concerns for plant reliability. Materials degradation within a nuclear power plant is very complex. There are many different types of materials within the reactor itself: over 25 different metal alloys can be found with can be found within the primary and secondary systems, not to mention the concrete containment vessel, instrumentation and control, and other support facilities. When this diverse set of materials is placed in the complex and harsh environment coupled with load, degradation over an extended life is indeed quite complicated. To address this issue, the USNRC has developed a Progressive Materials Degradation Approach (NUREG/CR-6923). This approach is intended to develop a foundation for appropriate actions to keep materials degradation from adversely impacting component integrity and safety and identify materials and locations where degradation can reasonably be expected in the future. Clearly, materials degradation will impact reactor reliability, availability, and potentially, safe operation. Routine surveillance and component replacement can mitigate these factors, although failures still occur. With reactor life extensions to 60 years or beyond or power uprates, many components must tolerate the reactor environment for even longer times. This may increase

[Assessment of soil degradation in regions of nuclear power explosions at Semipalatinsk Nuclear Test Site].

Science.gov (United States)

Evseeva, T I; Geras'kin, S A; Maĭstrenko, T A; Belykh, E S

2011-01-01

Degree of the soil cover degradation at the "Balapan" and "Experimental field" test sites was assessed based on Allium-test of soil toxicity results and international guidelines on radioactive restriction of solid materials (IAEA, 2004) and environment (Smith, 2005). Soil cover degradation maps of large-scale (1 : 25000) were made. The main part of the area mapped belongs to high-contaminated toxic degraded soil. A relationship between the soil toxicity and the total radionuclide activity concentrations was found to be described by power functions. When the calculated value (equal to 413-415 Bq/kg of air dry soil) increases, the soil becomes toxic for plants. This value is 7.8 times higher than the maximal value for background territories (53 Bq/kg) surrounding SNTS. Russian sanitary and hygienic guidelines (Radiation safety norms, 2009; Sanitary regulations of radioactive waste management, 2003) underestimate the degree of soil radioactive contamination for plants.

Identification and Assessment of Material Models for Age-Related Degradation of Structures and Passive Components in Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Nie,J.; Braverman, J.; Hofmayer, C.; Kim, M. K.; Choi, I-K.

2009-04-27

When performing seismic safety assessments of nuclear power plants (NPPs), the potential effects of age-related degradation on structures, systems, and components (SSCs) should be considered. To address the issue of aging degradation, the Korea Atomic Energy Research Institute (KAERI) has embarked on a five-year research project to develop a realistic seismic risk evaluation system which will include the consideration of aging of structures and components in NPPs. Three specific areas that are included in the KAERI research project, related to seismic probabilistic risk assessment (PRA), are probabilistic seismic hazard analysis, seismic fragility analysis including the effects of aging, and a plant seismic risk analysis. To support the development of seismic capability evaluation technology for degraded structures and components, KAERI entered into a collaboration agreement with Brookhaven National Laboratory (BNL) in 2007. The collaborative research effort is intended to continue over a five year period with the goal of developing seismic fragility analysis methods that consider the potential effects of age-related degradation of SSCs, and using these results as input to seismic PRAs. In the Year 1 scope of work BNL collected and reviewed degradation occurrences in US NPPs and identified important aging characteristics needed for the seismic capability evaluations that will be performed in the subsequent evaluations in the years that follow. This information is presented in the Annual Report for the Year 1 Task, identified as BNL Report-81741-2008 and also designated as KAERI/RR-2931/2008. The report presents results of the statistical and trending analysis of this data and compares the results to prior aging studies. In addition, the report provides a description of U.S. current regulatory requirements, regulatory guidance documents, generic communications, industry standards and guidance, and past research related to aging degradation of SSCs. This report

Assessment of degradation and aging of nuclear power plants concrete structures

International Nuclear Information System (INIS)

Busby, J.; Naus, D.; Graves, H.; Sheikh, A.; Le Pape, Y.; Rashid, J.; Saouma, V.; Wall, J.

2015-01-01

This paper summarizes the results of an expert-panel assessment of ageing degradation modes and mechanisms of concrete structures in NPPs, where, based on specific operating environments, degradation is likely to occur, or may have occurred; to define relevant aging and degradation modes and mechanisms; and to perform systematic assessment of the effects of these age-related degradation mechanisms on the future life of those materials and structures. The following 7 degradation modes and mechanisms have been identified as having the greatest potential impact on the ability of concrete structures to fulfill their safety related functions during long-term NPP operation. 1) Corrosion of conventional reinforcement is difficult to assess because of inaccessibility to inspection; 2) Creep of pre-stressed concrete containments continuously affects the internal stress state and adds to tendon relaxation and gradual loss of prestress; 3) Irradiation of concrete lacks sufficient data to for a clear evaluation of its effects on long-term operations; 4) Alkali-silica reaction potential consequences on the structural integrity of the containment; 5) Fracture/cracking, which is a well understood behavior characteristic of concrete structures and is accounted for in structural design, plays a unique role in post-tensioned containments during de-tensioning and re-tensioning operations which may be undertaken as part of life extension retrofit work, resulting in delamination, and may evolve with time as a creep-cracking interaction mechanism; 6) Boric acid attack of concrete in the spent fuel pool involves knowledge gaps related to the kinetics and the extent of the attack (role of the concrete mix design); 7) Corrosion of the inaccessible side of the spent fuel pool and containment liners and the stress corrosion cracking of the tendons are important degradation modes due to the absence of in-service inspection. The potential impact of these mechanisms may be mitigated by

Apoptotic DNA Degradation into Oligonucleosomal Fragments, but Not Apoptotic Nuclear Morphology, Relies on a Cytosolic Pool of DFF40/CAD Endonuclease*

Science.gov (United States)

Iglesias-Guimarais, Victoria; Gil-Guiñon, Estel; Gabernet, Gisela; García-Belinchón, Mercè; Sánchez-Osuna, María; Casanelles, Elisenda; Comella, Joan X.; Yuste, Victor J.

2012-01-01

Apoptotic cell death is characterized by nuclear fragmentation and oligonucleosomal DNA degradation, mediated by the caspase-dependent specific activation of DFF40/CAD endonuclease. Here, we describe how, upon apoptotic stimuli, SK-N-AS human neuroblastoma-derived cells show apoptotic nuclear morphology without displaying concomitant internucleosomal DNA fragmentation. Cytotoxicity afforded after staurosporine treatment is comparable with that obtained in SH-SY5Y cells, which exhibit a complete apoptotic phenotype. SK-N-AS cell death is a caspase-dependent process that can be impaired by the pan-caspase inhibitor q-VD-OPh. The endogenous inhibitor of DFF40/CAD, ICAD, is correctly processed, and dff40/cad cDNA sequence does not reveal mutations altering its amino acid composition. Biochemical approaches show that both SH-SY5Y and SK-N-AS resting cells express comparable levels of DFF40/CAD. However, the endonuclease is poorly expressed in the cytosolic fraction of healthy SK-N-AS cells. Despite this differential subcellular distribution of DFF40/CAD, we find no differences in the subcellular localization of both pro-caspase-3 and ICAD between the analyzed cell lines. After staurosporine treatment, the preferential processing of ICAD in the cytosolic fraction allows the translocation of DFF40/CAD from this fraction to a chromatin-enriched one. Therefore, the low levels of cytosolic DFF40/CAD detected in SK-N-AS cells determine the absence of DNA laddering after staurosporine treatment. In these cells DFF40/CAD cytosolic levels can be restored by the overexpression of their own endonuclease, which is sufficient to make them proficient at degrading their chromatin into oligonucleosome-size fragments after staurosporine treatment. Altogether, the cytosolic levels of DFF40/CAD are determinants in achieving a complete apoptotic phenotype, including oligonucleosomal DNA degradation. PMID:22253444

Risk-informed assessment of degraded containment structures

International Nuclear Information System (INIS)

Spencer, B.W.; Kunsman, D.M.; Graves, H.L.

2003-01-01

As nuclear power plants age, a number of degradation mechanisms may begin to affect the ability of critical containment structures to prevent radiation release during a severe accident. A research program is underway to quantify the effects of various types of containment degradation in a risk-informed manner. In this paper, corrosion is assumed to occur in the liner of a reinforced concrete containment at a 'typical' U.S. pressurized water reactor nuclear power plant, and its effect is investigated. Latin hypercube sampling is used in conjunction with finite element models of a typical steel-lined reinforced concrete containment to generate overpressurization fragilities of the containment with and without corrosion. An existing probabilistic risk assessment model of the plant is then used with these fragilities to determine the increase in risk caused by the corrosion. (author)

Drift Degradation Analysis

International Nuclear Information System (INIS)

D. Kicker

2004-01-01

Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal stress. (3) The DRKBA

Drift Degradation Analysis

Energy Technology Data Exchange (ETDEWEB)

D. Kicker

2004-09-16

Degradation of underground openings as a function of time is a natural and expected occurrence for any subsurface excavation. Over time, changes occur to both the stress condition and the strength of the rock mass due to several interacting factors. Once the factors contributing to degradation are characterized, the effects of drift degradation can typically be mitigated through appropriate design and maintenance of the ground support system. However, for the emplacement drifts of the geologic repository at Yucca Mountain, it is necessary to characterize drift degradation over a 10,000-year period, which is well beyond the functional period of the ground support system. This document provides an analysis of the amount of drift degradation anticipated in repository emplacement drifts for discrete events and time increments extending throughout the 10,000-year regulatory period for postclosure performance. This revision of the drift degradation analysis was developed to support the license application and fulfill specific agreement items between the U.S. Nuclear Regulatory Commission (NRC) and the U.S. Department of Energy (DOE). The earlier versions of ''Drift Degradation Analysis'' (BSC 2001 [DIRS 156304]) relied primarily on the DRKBA numerical code, which provides for a probabilistic key-block assessment based on realistic fracture patterns determined from field mapping in the Exploratory Studies Facility (ESF) at Yucca Mountain. A key block is defined as a critical block in the surrounding rock mass of an excavation, which is removable and oriented in an unsafe manner such that it is likely to move into an opening unless support is provided. However, the use of the DRKBA code to determine potential rockfall data at the repository horizon during the postclosure period has several limitations: (1) The DRKBA code cannot explicitly apply dynamic loads due to seismic ground motion. (2) The DRKBA code cannot explicitly apply loads due to thermal

Fragility Analysis Methodology for Degraded Structures and Passive Components in Nuclear Power Plants - Illustrated using a Condensate Storage Tank

Energy Technology Data Exchange (ETDEWEB)

Nie, J.; Braverman, J.; Hofmayer, C.; Choun, Y.; Kim, M.; Choi, I.

2010-06-30

The Korea Atomic Energy Research Institute (KAERI) is conducting a five-year research project to develop a realistic seismic risk evaluation system which includes the consideration of aging of structures and components in nuclear power plants (NPPs). The KAERI research project includes three specific areas that are essential to seismic probabilistic risk assessment (PRA): (1) probabilistic seismic hazard analysis, (2) seismic fragility analysis including the effects of aging, and (3) a plant seismic risk analysis. Since 2007, Brookhaven National Laboratory (BNL) has entered into a collaboration agreement with KAERI to support its development of seismic capability evaluation technology for degraded structures and components. The collaborative research effort is intended to continue over a five year period. The goal of this collaboration endeavor is to assist KAERI to develop seismic fragility analysis methods that consider the potential effects of age-related degradation of structures, systems, and components (SSCs). The research results of this multi-year collaboration will be utilized as input to seismic PRAs. In the Year 1 scope of work, BNL collected and reviewed degradation occurrences in US NPPs and identified important aging characteristics needed for the seismic capability evaluations. This information is presented in the Annual Report for the Year 1 Task, identified as BNL Report-81741-2008 and also designated as KAERI/RR-2931/2008. The report presents results of the statistical and trending analysis of this data and compares the results to prior aging studies. In addition, the report provides a description of U.S. current regulatory requirements, regulatory guidance documents, generic communications, industry standards and guidance, and past research related to aging degradation of SSCs. In the Year 2 scope of work, BNL carried out a research effort to identify and assess degradation models for the long-term behavior of dominant materials that are

Study on degradation of dimefuron in soil by nuclear technique

International Nuclear Information System (INIS)

Pakkong, P.; Vadeilai, J.

1996-01-01

Study on degradation of herbicide dimefuron in soil by using bio meter flask experiment was conducted under laboratory condition, 14 C-dimefuron was applied to three conditions of sterile soil normal and bio fertilizer added soil. Every month 14 CO 2 was collected from 1 N KOH in bio meter flask with in eight months period. Carbon-14 activity was analyzed by liquid scintillation counter. The result of dimefuron degradation as 14 CO 2 in sterile normal and bio fertilizer added soil were 0.96 percent 6.31 percent and 9.36 percent. It can be concluded that increasing in dimefuron degradation rate was involved by micro-organism activity. After eight month extracted and bounded residue of dimefuron in soil were analysed. Radioassay show that extracted and bounded residue were 58.62 and 29.58 percent in sterile soil 45.73 and 41.91 percent in normal soil 45.28 and 36.3 percent in bio fertilizer added soil

Generic Degraded Configuration Probability Analysis for the Codisposal Waste Package

International Nuclear Information System (INIS)

S.F.A. Deng; M. Saglam; L.J. Gratton

2001-01-01

In accordance with the technical work plan, ''Technical Work Plan For: Department of Energy Spent Nuclear Fuel Work Packages'' (CRWMS M and O 2000c), this Analysis/Model Report (AMR) is developed for the purpose of screening out degraded configurations for U.S. Department of Energy (DOE) spent nuclear fuel (SNF) types. It performs the degraded configuration parameter and probability evaluations of the overall methodology specified in the ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2000, Section 3) to qualifying configurations. Degradation analyses are performed to assess realizable parameter ranges and physical regimes for configurations. Probability calculations are then performed for configurations characterized by k eff in excess of the Critical Limit (CL). The scope of this document is to develop a generic set of screening criteria or models to screen out degraded configurations having potential for exceeding a criticality limit. The developed screening criteria include arguments based on physical/chemical processes and probability calculations and apply to DOE SNF types when codisposed with the high-level waste (HLW) glass inside a waste package. The degradation takes place inside the waste package and is long after repository licensing has expired. The emphasis of this AMR is on degraded configuration screening and the probability analysis is one of the approaches used for screening. The intended use of the model is to apply the developed screening criteria to each DOE SNF type following the completion of the degraded mode criticality analysis internal to the waste package

Recovery of acid-degraded tributyl phosphate by solvent extraction

International Nuclear Information System (INIS)

Young, G.C.; Holladay, D.W.

1981-01-01

During nuclear fuel reprocessing the organic solvent becomes loaded with various acidic degradation products, which can be effectively removed through solvent extraction. Studies have been made with a small bench-scale solvent extraction system to optimize such parameters as pH of aqueous phase, phase ratio, residence time, flow rates, and temperature. The necessary decontamination factors have been obtained for various degradation products during continuous solvent extraction in one stage, with the aqueous phase being recycled. The aqueous phase contains compounds that can be degraded to gases to minimize waste disposal problems

Materials Degradation Issues in the U.S. High-Level Nuclear Waste Repository

Energy Technology Data Exchange (ETDEWEB)

K.G. Mon; F. Hua

2005-04-12

This paper reviews the state-of-the-art understanding of the degradation processes by the Yucca Mountain Project (YMP) with focus on interaction between the in-drift environmental conditions and long-term materials degradation of waste packages and drip shields within the repository system during the first 10,000-years after repository closure. This paper provides an overview of the degradation of the waste packages and drip shields in the repository after permanent closure of the facility. The degradation modes discussed in this paper include aging and phase instability, dry oxidation, general and localized corrosion, stress corrosion cracking, and hydrogen induced cracking of Alloy 22 and titanium alloys. The effects of microbial activity and radiation on the degradation of Alloy 22 and titanium alloys are also discussed. Further, for titanium alloys, the effects of fluorides, bromides, and galvanic coupling to less noble metals are considered. It is concluded that the materials and design adopted will provide sufficient safety margins for at least 10,000-years after repository closure.

Materials Degradation Issues in the U.S. High-Level Nuclear Waste Repository

International Nuclear Information System (INIS)

Mon, K.G.; Hua, F.

2005-01-01

This paper reviews the state-of-the-art understanding of the degradation processes by the Yucca Mountain Project (YMP) with focus on interaction between the in-drift environmental conditions and long-term materials degradation of waste packages and drip shields within the repository system during the first 10,000-years after repository closure. This paper provides an overview of the degradation of the waste packages and drip shields in the repository after permanent closure of the facility. The degradation modes discussed in this paper include aging and phase instability, dry oxidation, general and localized corrosion, stress corrosion cracking, and hydrogen induced cracking of Alloy 22 and titanium alloys. The effects of microbial activity and radiation on the degradation of Alloy 22 and titanium alloys are also discussed. Further, for titanium alloys, the effects of fluorides, bromides, and galvanic coupling to less noble metals are considered. It is concluded that the materials and design adopted will provide sufficient safety margins for at least 10,000-years after repository closure

Materials Degradation and Detection (MD2): Deep Dive Final Report

Energy Technology Data Exchange (ETDEWEB)

McCloy, John S.; Montgomery, Robert O.; Ramuhalli, Pradeep; Meyer, Ryan M.; Hu, Shenyang Y.; Li, Yulan; Henager, Charles H.; Johnson, Bradley R.

2013-02-01

An effort is underway at Pacific Northwest National Laboratory (PNNL) to develop a fundamental and general framework to foster the science and technology needed to support real-time monitoring of early degradation in materials used in the production of nuclear power. The development of such a capability would represent a timely solution to the mounting issues operators face with materials degradation in nuclear power plants. The envisioned framework consists of three primary and interconnected “thrust” areas including 1) microstructural science, 2) behavior assessment, and 3) monitoring and predictive capabilities. A brief state-of-the-art assessment for each of these core technology areas is discussed in the paper.

Aging and low-flow degradation of auxilary feedwater pumps

International Nuclear Information System (INIS)

Adams, M.L.

1992-01-01

This paper documents the results of research done under the auspices of the Nuclear Regulatory Commission Nuclear Plant Aging Research Program. It examines the degradation imparted to safety related Auxiliary Feedwater System pumps at nuclear plants due to the low flow operation. The Auxiliary Feedwater (AFW) System is normally a stand-by system. As such it is operated most often in the test mode. Since few plants are equipped with full flow test loops, most testing is accomplished at minimum flow conditions in pump by-pass lines. It is the vibration and hydraulic forces generated at low flow conditions that have been shown to be the major causes of AFW pump aging and degradation. The wear can be manifested in a number of ways, such as impeller or diffuser breakage, thrust bearing and/or balance device failure due to excessive loading, cavitation damage on such stage impellers, increase seal leakage or failure, sear injection piping failure, shaft or coupling breakage, and rotating element seizure

Aging and low-flow degradation of auxiliary feedwater pumps

International Nuclear Information System (INIS)

Adams, M.L.

1991-01-01

This paper documents the results of research done under the auspices of the Nuclear Regulatory Commission Nuclear Plant Aging Research Program. It examines the degradation imparted to safety Auxiliary Feedwater System pumps at nuclear plants due to the low flow operation. The Auxiliary Feedwater (AFW) System is normally a stand-by system. As such it is operated most often in the test mode. Since few plants are equipped with full flow test loops, most testing is accomplished at minimum flow conditions in pump by-pass lines. It is the vibration and hydraulic forces generated at low flow conditions that have been shown to be the major causes of AFW pump aging and degradation. The wear can be manifested in a number of ways, such as impeller or diffuser breakage, thrust bearing and/or balance device failure due to excessive loading, cavitation damage on such stage impellers, increase seal leakage or failure, sear injection piping failure, shaft or coupling breakage, and rotating element seizure

Generic Degraded Congiguration Probability Analysis for DOE Codisposal Waste Package

Energy Technology Data Exchange (ETDEWEB)

S.F.A. Deng; M. Saglam; L.J. Gratton

2001-05-23

In accordance with the technical work plan, ''Technical Work Plan For: Department of Energy Spent Nuclear Fuel Work Packages'' (CRWMS M&O 2000c), this Analysis/Model Report (AMR) is developed for the purpose of screening out degraded configurations for U.S. Department of Energy (DOE) spent nuclear fuel (SNF) types. It performs the degraded configuration parameter and probability evaluations of the overall methodology specified in the ''Disposal Criticality Analysis Methodology Topical Report'' (YMP 2000, Section 3) to qualifying configurations. Degradation analyses are performed to assess realizable parameter ranges and physical regimes for configurations. Probability calculations are then performed for configurations characterized by k{sub eff} in excess of the Critical Limit (CL). The scope of this document is to develop a generic set of screening criteria or models to screen out degraded configurations having potential for exceeding a criticality limit. The developed screening criteria include arguments based on physical/chemical processes and probability calculations and apply to DOE SNF types when codisposed with the high-level waste (HLW) glass inside a waste package. The degradation takes place inside the waste package and is long after repository licensing has expired. The emphasis of this AMR is on degraded configuration screening and the probability analysis is one of the approaches used for screening. The intended use of the model is to apply the developed screening criteria to each DOE SNF type following the completion of the degraded mode criticality analysis internal to the waste package.

Phenomenology of BWR fuel assembly degradation

Science.gov (United States)

Kurata, Masaki; Barrachin, Marc; Haste, Tim; Steinbrueck, Martin

2018-03-01

Severe accidents occurred at the Fukushima-Daiichi Nuclear Power Station (FDNPS) which required an immediate re-examination of fuel degradation phenomenology. The present paper reviews the updated knowledge on the phenomenology of the fuel degradation, focusing mainly on the BWR fuel assembly degradation at the macroscopic scale and that of the individual interactions at the meso-scale. Oxidation of boron carbide (B4C) control rods potentially generates far larger amounts of heat and hydrogen under BWR accident conditions. All integral tests with B4C control rods or control blades have shown early failure, liquefaction, relocation and oxidation of B4C starting at temperatures around 1250 °C, well below the significant interaction temperatures of UO2-Zry. These interactions or reactions potentially influence the progress of fuel degradation in the early phase. The steam-starved conditions, which are being discussed as a likely scenario at the FDNPS accident, highly influence the individual interactions and potentially lead the fuel degradation in non-prototypical directions. The detailed phenomenology of individual interactions and their influence on the transient and on the late phase of the severe accidents are also discussed.

Seepage into drifts with mechanical degradation

International Nuclear Information System (INIS)

Li, Guomin; Tsang, Chin-Fu

2002-01-01

Seepage into drifts in unsaturated tuff is an important issue for the long-term performance of the potential nuclear waste repository at Yucca Mountain, Nevada. Drifts in which waste packages will potentially be emplaced are subject to degradation in the form of rockfall from the drift ceiling induced by stress relief, seismic, or thermal effects. The objective of this study is to calculate seepage rates for various drift-degradation scenarios and for different values of percolation flux for the Topopah Spring middle nonlithophysal (Tptpmn) and the Topopah Spring lower lithophysal (Tptpll) units. Seepage calculations are conducted by (1) defining a heterogeneous permeability model on the drift scale that is consistent with field data, (2) selecting calibrated parameters associated with the Tptpmn and Tptpll units, and (3) simulating seepage on detailed degraded-drift profiles, which were obtained from a separate rock mechanics engineering analysis. The simulation results indicate (1) that the seepage threshold (i.e., the percolation flux at which seepage first occurs) is not significantly changed by drift degradation, and (2) the degradation-induced increase in seepage above the threshold is influenced more by the shape of the cavity created by rockfall than the rockfall volume

Metal complexation in near field conditions of nuclear waste repository - stability constant of copper complexation with cellulose degradation products, in alkaline conditions

International Nuclear Information System (INIS)

Guede, Kipre Bertin

2005-11-01

Copper is a stable element and spent fuel component which constitutes the radioactive waste. The reaction of Copper with cellulose degradation products in alkaline conditions was performed to mimic what occurs in near field conditions of nuclear waste repository. From the characteristics of Cu (II), this thesis aims at inferring the behaviour of radionuclides vis a vis the degradation products of cellulose. The contribution of the present work is therefore the assessment of the stability of the major cellulose degradation product, its affinity for Copper and the extent of the complexation function 13 between Cu (II) and the organic moieties. The formation of cellulose degradation products was followed by measurement of p11, Conductivity, Angle of rotation, relative abundance of aliphatics and aromatics (E4/E6 ) aid by UV-visible spectroscopy. The TOC was determined using the Walkley and Black titration after respectively 31 weeks and 13 weeks of degradation for the reaction mixtures T and A, N. The stability of the major degradation products gave the following figures: ISA(A): - 13 43.39 <ΔG -10639.88 ISA(N): - Ii 436.45<ΔG< -9103.6. The study of the characteristics of Gluconic Acid, as a model compound, was carried out in an attempt to give a general picture of the roper ties of cellulose degradation products. The Complexation between Cu (II) and the organic ligand (Cellulose degradation products) was performed using UV-visible spectroscopy and Ion Distribution technique. The Log B value obtained from the complexation studies at 336 nm for 1 = 0. I Ni NaClO4 and I = 0.01 M NaClO4, falls within a range of 3.48 to 3.74 for the standard reference material (Gluconic Acid), and within I .87 to 2.3 I, and I .6 to 2.01, respectively for the degradation Products ISA (A) and ISA(N). The ion distribution studies showed that: • In (he absence of the degradation product ISA and at pH = 3.68. 56. 17 % of Cu (II) was bound to the resin. • In the presence of ISA and at 2

Ubiquitin ligase RNF123 mediates degradation of heterochromatin protein 1α and β in lamin A/C knock-down cells.

Directory of Open Access Journals (Sweden)

Pankaj Chaturvedi

Full Text Available The nuclear lamina is a key determinant of nuclear architecture, integrity and functionality in metazoan nuclei. Mutations in the human lamin A gene lead to highly debilitating genetic diseases termed as laminopathies. Expression of lamin A mutations or reduction in levels of endogenous A-type lamins leads to nuclear defects such as abnormal nuclear morphology and disorganization of heterochromatin. This is accompanied by increased proteasomal degradation of certain nuclear proteins such as emerin, nesprin-1α, retinoblastoma protein and heterochromatin protein 1 (HP1. However, the pathways of proteasomal degradation have not been well characterized.To investigate the mechanisms underlying the degradation of HP1 proteins upon lamin misexpression, we analyzed the effects of shRNA-mediated knock-down of lamins A and C in HeLa cells. Cells with reduced levels of expression of lamins A and C exhibited proteasomal degradation of HP1α and HP1β but not HP1γ. Since specific ubiquitin ligases are upregulated in lamin A/C knock-down cells, further studies were carried out with one of these ligases, RNF123, which has a putative HP1-binding motif. Ectopic expression of GFP-tagged RNF123 directly resulted in degradation of HP1α and HP1β. Mutational analysis showed that the canonical HP1-binding pentapeptide motif PXVXL in the N-terminus of RNF123 was required for binding to HP1 proteins and targeting them for degradation. The role of endogenous RNF123 in the degradation of HP1 isoforms was confirmed by RNF123 RNAi experiments. Furthermore, FRAP analysis suggested that HP1β was displaced from chromatin in laminopathic cells.Our data support a role for RNF123 ubiquitin ligase in the degradation of HP1α and HP1β upon lamin A/C knock-down. Hence lamin misexpression can cause degradation of mislocalized proteins involved in key nuclear processes by induction of specific components of the ubiquitin-proteasome system.

Physical degradation assessment of generator station cables

International Nuclear Information System (INIS)

Stonkus, D.J.

1988-01-01

Preliminary studies of fossil-fired and nuclear generator station cables indicate that the low voltage PVC insulated cables are in relatively good condition. The insulation is flexible and in the case of nuclear cables can withstand a design basis event after nearly 15 years of service. Cables insulated with styrene butadiene rubber have been found embrittled and cables insulated with SBR should be closely inspected in any plant assurance program. Thermal analysis using oxidative induction technique shows promise to indicate cable insulation degradation. Long term reliability assurance and plant life extension studies are being actively pursued at Ontario Hydro. A major study is currently underway to extend the life of the oldest operating fossil-fuel station, the 8-unit, 2400 MW Lakeview TGS in operation since the 1960s. Plant life assurance programs have been initiated at the 2000 MW Lambton TGS in operation since 1969, and for the oldest operating nuclear plant, Pickering NGS A in operation since the early 1970s. As cables are considered one of the critical components in a generator station due to the extreme difficulty and cost of cable replacement, test programs have been initiated to evaluate the physical degradation of the cables and relate the results to electrical diagnostic tests and to chemical changes. The decommissioning of two small nuclear stations, the 20 MW Nuclear Power Demonstration (NPD) and the 200 MW Douglas Point NGS, which were placed in service in 1962 and 1967 respectively, will provide an opportunity to perform destructive electrical and physical evaluation on field aged cables

Age-related degradation of Westinghouse 480-volt circuit breakers

International Nuclear Information System (INIS)

Subudhi, M.; Shier, W.; MacDougall, E.

1990-07-01

An aging assessment of Westinghouse DS-series low-voltage air circuit breakers was performed as part of the Nuclear Plant Aging Research (NPAR) program. The objectives of this study are to characterize age-related degradation within the breaker assembly and to identify maintenance practices to mitigate their effect. Since this study has been promulgated by the failures of the reactor trip breakers at the McGuire Nuclear Station in July 1987, results relating to the welds in the breaker pole lever welds are also discussed. The design and operation of DS-206 and DS-416 breakers were reviewed. Failure data from various national data bases were analyzed to identify the predominant failure modes, causes, and mechanisms. Additional operating experiences from one nuclear station and two industrial breaker-service companies were obtained to develop aging trends of various subcomponents. The responses of the utilities to the NRC Bulletin 88-01, which discusses the center pole lever welds, were analyzed to assess the final resolution of failures of welds in the reactor trips. Maintenance recommendations, made by the manufacturer to mitigate age-related degradation were reviewed, and recommendations for improving the monitoring of age-related degradation are discussed. As described in Volume 2 of this NUREG, the results from a test program to assess degradation in breaker parts through mechanical cycling are also included. The testing has characterized the cracking of center-pole lever welds, identified monitoring techniques to determine aging in breakers, and provided information to augment existing maintenance programs. Recommendations to improve breaker reliability using effective maintenance, testing, and inspection programs are suggested. 13 refs., 21 figs., 8 tabs

Thermal degradation of CR-39 polymer in an inert atmosphere

International Nuclear Information System (INIS)

Kalsi, P.C.; Pandey, A.K.; Iyer, R.H.; Singh Mudher, K.D.

1995-01-01

The thermal degradation of CR-39 (allyl diglycol carbonate), a polymer widely used in nuclear science and technology, in an inert atmosphere has been studied using thermogravimetric analysis (TGA) and differential thermal analysis (DTA) techniques. The results are compared with the thermal degradation data of the polymer in an air atmosphere. The present studies showed that the thermal degradation of the polymer proceeds in two steps in an argon atmosphere as compared to three steps in air atmosphere. The mass losses in air are higher than that in argon due to the oxidative decomposition of the residue. The kinetics of the different stages of degradation were also evaluated from the TG curves. (author). 7 refs., 1 tab

A Procedure for Determination of Degradation Acceptance Criteria for Structures and Passive Components in Nuclear Power Plants

Energy Technology Data Exchange (ETDEWEB)

Nie, J.; Braverman, J.; Hofmayer, C.; Choun, Y-S.; Hahm, D.; Choi, I-K.

2012-01-30

The Korea Atomic Energy Research Institute (KAERI) has been collaborating with Brookhaven National Laboratory since 2007 to develop a realistic seismic risk evaluation system which includes the consideration of aging of structures and components in nuclear power plants (NPPs). This collaboration program aims at providing technical support to a five-year KAERI research project, which includes three specific areas that are essential to seismic probabilistic risk assessment: (1) probabilistic seismic hazard analysis, (2) seismic fragility analysis including the effects of aging, and (3) a plant seismic risk analysis. The understanding and assessment of age-related degradations of structures, systems, and components and their impact on plant safety is the major goal of this KAERI-BNL collaboration. Four annual reports have been published before this report as a result of the collaboration research.

Nuclear power plant life management. An overview of identification of key components in relation with degradation mechanism - IAEA guidelines presentation

International Nuclear Information System (INIS)

Bezdikian, Georges

2005-01-01

Nuclear Power Plant (NPP) lifetime has a direct bearing on the cost of the electricity generated from it. The annual unit cost of electricity is dependent upon the operational time, and also annual costs and the capital cost assumptions function of Euros/kw. If the actual NPP lifetime has been underestimated then an economic penalty could be incurred. But the ageing degradation, of nuclear power plants is an important aspect that requires to be addressed to ensure: - that necessary safety margins are maintained throughout service life; - the adequate reliability and therefore the economic viability of older plants is maintained; - that unforeseen an uncontrolled degradation of critical plant components does not foreshorten the plant lifetime. Accommodating the inevitable obsolescence of some components has also to be addressed during plant life. Plant lifetime management requires the identification and life assessment of those components which not only limit the lifetime of the plant but also those which cannot be reasonably replaced. The planned replacement of major or 'key' components needs to be considered - where economic considerations will largely dictate replacement or the alternative strategy of power plant decommissioning. The necessary but timely planning for maintenance and replacements is a necessary consideration so that functions and reliability are maintained. The reasons for the current increasing attention in the area of plant life management are diverse and range from the fact that many of the older plants are approaching for the oldest plants more than 30 years in operation, and for important number of NPPs between 20 and 30 years. The impact of plant life management on the economics of generating electricity is the subject of ongoing studies and it can readily be seen that there can be both savings and additional costs associated with these activities. Not all degradation processes will be of significance in eroding safety margins and there is a

Failure analysis of leakage on titanium tubes within heat exchangers in a nuclear power plant. Part II: Mechanical degradation

Energy Technology Data Exchange (ETDEWEB)

Gong, Y.; Yang, Z.G. [Department of Materials Science, Fudan University, Shanghai (China); Yuan, J.Z. [Third Qinshan Nuclear Power Co. Ltd., Haiyan, Zhejiang Province (China)

2012-01-15

Serious failure incidents like clogging, quick thinning, and leakage frequently occurred on lots of titanium tubes of heat exchangers in a nuclear power plant in China. In the Part I of the whole failure analysis study with totally two parts, factors mainly involving three kinds of electrochemical corrosions were investigated, including galvanic corrosion, crevice corrosion, and hydrogen-assisted corrosion. In the current Part II, through microscopically analyzing the ruptures on the leaked tubes by scanning electron microscopy (SEM) and energy dispersive spectrometry (EDS), another four causes dominantly lying in the aspect of mechanical degradation were determined - clogging, erosion, mechanical damaging, and fretting. Among them, the erosion effect was the primary one, thus the stresses it exerted on the tube wall were also supplementarily evaluated by finite element method (FEM). Based on the analysis results, the different degradation extents and morphologies by erosion on the tubes when they were clogged by different substances such as seashell, rubber debris, and sediments were compared, and relevant mechanisms were discussed. Finally, countermeasures were put forward as well. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Light Water Reactor Sustainability Program: Survey of Models for Concrete Degradation

Energy Technology Data Exchange (ETDEWEB)

Spencer, Benjamin W. [Idaho National Lab. (INL), Idaho Falls, ID (United States). Fuel Modeling and Simulation; Huang, Hai [Idaho National Lab. (INL), Idaho Falls, ID (United States). Energy and Environment Science and Technology

2014-08-01

Concrete is widely used in the construction of nuclear facilities because of its structural strength and its ability to shield radiation. The use of concrete in nuclear facilities for containment and shielding of radiation and radioactive materials has made its performance crucial for the safe operation of the facility. As such, when life extension is considered for nuclear power plants, it is critical to have predictive tools to address concerns related to aging processes of concrete structures and the capacity of structures subjected to age-related degradation. The goal of this report is to review and document the main aging mechanisms of concern for concrete structures in nuclear power plants (NPPs) and the models used in simulations of concrete aging and structural response of degraded concrete structures. This is in preparation for future work to develop and apply models for aging processes and response of aged NPP concrete structures in the Grizzly code. To that end, this report also provides recommendations for developing more robust predictive models for aging effects of performance of concrete.

Through wall degradation problem of the turbine extraction steam drain piping due to liquid drop impingement and measures taken for this problem at Fukushima Dai-ichi Nuclear Power Plant Unit 6

International Nuclear Information System (INIS)

Inagaki, Takeyuki; Kobayashi, Teruaki; Shimada, Shigeru; Inoue, Ryousuke; Usuba, Satoshi; Kimura, Takeo

2011-01-01

Through wall degradation was found on the extraction steam drain piping of Unit 6 of Fukushima Dai-ichi Nuclear Power Plant owned by Tokyo Electric Power Company after replacement of the turbine rotors with those of higher thermal efficiency. The mechanism of this degradation was loss of material due to liquid drop impingement. Since the estimated life time of the piping based on wall thickness measurements before the replacement was at least 9 years, the rapid wall thinning occurred after the replacement. This paper describes a summary of the phenomenon, its degradation mechanism and root cause, a temporary measurement taken for an immediate action and permanent measures taken during the next refueling outage. (author)

Physical and mechanical properties of degraded waste surrogate material

International Nuclear Information System (INIS)

Hansen, F.D.; Mellegard, K.D.

1998-03-01

This paper discusses rock mechanics testing of surrogate materials to provide failure criteria for compacted, degraded nuclear waste. This daunting proposition was approached by first assembling all known parameters such as the initial waste inventory and rock mechanics response of the underground setting after the waste is stored. Conservative assumptions allowing for extensive degradation processes helped quantify the lowest possible strength conditions of the future state of the waste. In the larger conceptual setting, computations involve degraded waste behavior in transient pressure gradients as gas exits the waste horizon into a wellbore. Therefore, a defensible evaluation of tensile strength is paramount for successful analyses and intentionally provided maximal failed volumes. The very conservative approach assumes rampant degradation to define waste surrogate composition. Specimens prepared from derivative degradation product were consolidated into simple geometries for rock mechanics testing. Tensile strength thus derived helped convince a skeptical peer review panel that drilling into the Waste Isolation Pilot Plant (WIPP) would not likely expel appreciable solids via the drill string

Advanced Cell Development and Degradation Studies

International Nuclear Information System (INIS)

O'Brien, J.E.; Stoots, C.M.; Herring, J.S.; O'Brien, R.C.; Condie, K.G.; Sohal, M.; Housley, G.K.; Hartvigsen, J.J.; Larsen, D.; Tao, G.; Yildiz, B.; Sharma, V.; Singh, P.; Petigny, N.; Cable, T.L.

2010-01-01

The Idaho National Laboratory (INL) has been researching the application of solid-oxide electrolysis cells for large-scale hydrogen production from steam over a temperature range of 800 to 900 C. From 2003-2009, this work was sponsored by the DOE Nuclear Hydrogen Initiative (NHI). Starting in 2010, the HTE research program has been sponsored by the Next Generation Nuclear Plant (NGNP) program. HTSE research priorities in FY10 are centered on understanding and reducing cell and stack performance degradation to an acceptable level to advance the technology readiness level of HTSE and to justify further large-scale demonstration activities. This report provides a summary of our FY10 experimental program, which has been focused on advanced cell and stack development and degradation studies. Advanced cell and stack development activities are under way at five technology partners: MSRI, Versa Power, Ceramatec, NASA Glenn, and St. Gobain. Performance evaluation of the advanced technology cells and stacks has been performed by the technology partners, by MIT and the University of Connecticut and at the INL HTE Laboratory. Summaries of these development activities and test results are presented.

Advanced Cell Development and Degradation Studies

Energy Technology Data Exchange (ETDEWEB)

J. E. O' Brien; C. M. Stoots; J. S. Herring; R. C. O' Brien; K. G. Condie; M. Sohal; G. K. Housley; J. J. Hartvigsen; D. Larsen; G. Tao; B. Yildiz; V. Sharma; P. Singh; N. Petigny; T. L. Cable

2010-09-01

The Idaho National Laboratory (INL) has been researching the application of solid-oxide electrolysis cells for large-scale hydrogen production from steam over a temperature range of 800 to 900ºC. From 2003 – 2009, this work was sponsored by the DOE Nuclear Hydrogen Initiative (NHI). Starting in 2010, the HTE research program has been sponsored by the Next Generation Nuclear Plant (NGNP) program. HTSE research priorities in FY10 are centered on understanding and reducing cell and stack performance degradation to an acceptable level to advance the technology readiness level of HTSE and to justify further large-scale demonstration activities. This report provides a summary of our FY10 experimental program, which has been focused on advanced cell and stack development and degradation studies. Advanced cell and stack development activities are under way at five technology partners: MSRI, Versa Power, Ceramatec, NASA Glenn, and St. Gobain. Performance evaluation of the advanced technology cells and stacks has been performed by the technology partners, by MIT and the University of Connecticut and at the INL HTE Laboratory. Summaries of these development activities and test results are presented.

Organic analyses of mixed nuclear wastes

International Nuclear Information System (INIS)

Toste, A.P.; Lucke, R.B.; Lechner-Fish, T.J.; Hendren, D.J.; Myers, R.B.

1987-04-01

Analytical methods are being developed for the organic analysis of nuclear wastes. Our laboratory analyzed the organic content of three commercial wastes and an organic-rich, complex concentrate waste. The commercial wastes contained a variety of hydrophobic and hydrophilic organics, at concentrations ranging from nanomolar to micromolar. Alkyl phenols, chelating and complexing agents, as well as their degradation products, and carboxylic acids were detected in the commercial wastes. The complex concentrate waste contained chelating and complexing agents, as well as numerous degradation products, at millimolar concentrations. 75.1% of the complex concentrate waste's total organic carbon content has been identified. The presence of chelator fragments in all of the wastes analyzed, occasionally at elevated concentrations, indicates that organic diagenesis, or degradation, in nuclear wastes is both widespread and quite vigorous. 23 refs., 3 tabs

Detection of pump degradation

International Nuclear Information System (INIS)

Casada, D.

1994-01-01

There are a variety of stressors that can affect the operation of centrifugal pumps. Although these general stressors are active in essentially all centrifugal pumps, the stressor level and the extent of wear and degradation can vary greatly. Parameters that affect the extent of stressor activity are manifold. In order to assure the long-term operational readiness of a pump, it is important to both understand the nature and magnitude of the specific degradation mechanisms and to monitor the performance of the pump. The most commonly applied method of monitoring the condition of not only pumps, but rotating machinery in general, is vibration analysis. Periodic or continuous spectral vibration analysis is a cornerstone of most pump monitoring programs. In the nuclear industry, non-spectral vibration monitoring of safety-related pumps is performed in accordance with the ASME code. Although vibration analysis has dominated the condition monitoring field for many years, there are other measures that have been historically used to help understand pump condition: advances in historically applied technologies and developing technologies offer improved monitoring capabilities. The capabilities of several technologies (including vibration analysis, dynamic pressure analysis, and motor power analysis) to detect the presence and magnitude of both stressors and resultant degradation are discussed

NuPEER Dijon 2005 Symposium. Ageing issues in nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Emond, David (ed.) [BCCN, Autorite de Surete Nucleaire, ASN, 6, place du Colonel Bourgoin, 75572 Paris Cedex 12 (France)

2005-07-01

The French Nuclear Safety Authority (ASN) organized an international symposium on regulatory aspects of ageing issues for nuclear pressure equipment. The ageing of nuclear pressure equipment is an issue of growing importance for nuclear regulators and material experts worldwide as age-related degradation of major pressure-retaining components challenges the remaining operating life of nuclear power plants. This symposium aimed at providing a forum for technical exchange among the staffs responsible for nuclear pressure equipment within the safety authorities and the associated expertise organisations. The contents of the symposium is as follows: 1. Control and supervision of safety of nuclear pressure equipment in France and abroad; 1.1. Position of the French Nuclear Safety Authority (1 paper); 1.2. Regulatory practices worldwide (4 papers); 1.3. Licence renewal: Field experience (2 papers); 1.4. Role of international organisations (1 paper); 2. Management of equipment and materials: From design to degradation mechanisms; 2.1. Operation and equipment (4 papers); 2. Evolution of materials (4 papers); 2.3. Fatigue degradation mechanisms (3 papers); 2.4. Contribution of research and development (4 papers); 3. In-service inspection: Evolutions, methods and strategies; 3.1. Methods and evolution (1 paper); 3.2. Qualification of methods (2 papers); 3.3. Surveillance strategies (2 papers); 4. Testimonies and points of view of utilities (3 papers); 5. Ageing issues taken into account in non nuclear fields (2 papers). The symposium began with workshops devoted to: Operation and equipment; Behaviour of materials; Fatigue degradations; Contributions of research and development. The symposium continued with plenary session that addressed the following issues: Control and supervision of safety of nuclear pressure equipment; Role of international organisations; In-service inspection: Objectives, methods and strategies; Point of view of utilities; Technical summary and

A Markov chain model for CANDU feeder pipe degradation

International Nuclear Information System (INIS)

Datla, S.; Dinnie, K.; Usmani, A.; Yuan, X.-X.

2008-01-01

There is need for risk based approach to manage feeder pipe degradation to ensure safe operation by minimizing the nuclear safety risk. The current lack of understanding of some fundamental degradation mechanisms will result in uncertainty in predicting the rupture frequency. There are still concerns caused by uncertainties in the inspection techniques and engineering evaluations which should be addressed in the current procedures. A probabilistic approach is therefore useful in quantifying the risk and also it provides a tool for risk based decision making. This paper discusses the application of Markov chain model for feeder pipes in order to predict and manage the risks associated with the existing and future aging-related feeder degradation mechanisms. The major challenge in the approach is the lack of service data in characterizing the transition probabilities of the Markov model. The paper also discusses various approaches in estimating plant specific degradation rates. (author)

Characterization of Radiation Fields for Assessing Concrete Degradation in Biological Shields of NPPs

Science.gov (United States)

Remec, Igor; Rosseel, Thomas M.; Field, Kevin G.; Pape, Yann Le

2017-09-01

Life extensions of nuclear power plants (NPPs) to 60 years of operation and the possibility of subsequent license renewal to 80 years have renewed interest in long-term material degradation in NPPs. Large irreplaceable sections of most nuclear generating stations are constructed from concrete, including safety-related structures such as biological shields and containment buildings; therefore, concrete degradation is being considered with particular focus on radiation-induced effects. Based on the projected neutron fluence values (E > 0.1 MeV) in the concrete biological shields of the US pressurized water reactor fleet and the currently available data on radiation effects on concrete, some decrease in mechanical properties of concrete cannot be ruled out during extended operation beyond 60 years. An expansion of the irradiated concrete database is desirable to ensure reliable risk assessment for extended operation of nuclear power plants.

Technical evaluation of the proposed design modifications and technical specification changes on grid voltage degradation (Part A) for the Pilgrim Nuclear Power Station, Unit 1

International Nuclear Information System (INIS)

White, R.L.

1980-01-01

This report documents the technical evaluation of the proposed design modifications and Technical Specification changes for protection of Class 1E equipment from grid voltage degradation for the Pilgrim Nuclear Power Station. The review criteria are based on several IEEE standards and the Code of Federal Regulations. The evaluation compares the submittals made by the licensee with the NRC staff positions and the review criteria and presents the reviewer's conclusion on the acceptability of the proposed system

Bacterial degradation of naphtha and its influence on corrosion

International Nuclear Information System (INIS)

Rajasekar, A.; Maruthamuthu, S.; Muthukumar, N.; Mohanan, S.; Subramanian, P.; Palaniswamy, N.

2005-01-01

The degradation problem of naphtha arises since hydrocarbon acts as an excellent food source for a wide variety of microorganisms. Microbial activity leads to unacceptable level of turbidity, corrosion of pipeline and souring of stored product. In the present study, biodegradation of naphtha in the storage tank and its influence on corrosion was studied. The corrosion studies were carried out by gravimetric method. Uniform corrosion was observed from the weight loss coupons in naphtha (0.024 mm/yr) whereas in presence of naphtha with water, blisters (1.2052 mm/yr) were noticed. The naphtha degradation by microbes was characterized by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). IR study reveals the formation of primary alcohol during degradation process. It was found that microbes degrade (CH 2 -CH 2 ) n to R-CH 3 . Iron bacteria, manganese oxidizing bacteria, acid producers, and heterotrophic bacteria were enumerated and identified in the pipeline. SRB could not be noticed. Since water stratifies in the pipeline, the naphtha-degraded product may adsorb on pipeline, which would enhance the rate of microbial corrosion. On the basis of degradation and corrosion data, a hypothesis for microbial corrosion has been proposed

Hydrolytic Degradation Behaviors of Poly(p-dioxanone) in Ambient Environments

Institute of Scientific and Technical Information of China (English)

You Yuan; Song-dong Ding; Yin-qiao Zhao; Yu-zhong Wang

2014-01-01

The effects of temperature and relative humidity on the hydrolytic degradation of poly(p-dioxanone) (PPDO) were investigated.The hydrolytic degradation behaviors were monitored by tracing the changes of water absorption,mechanical and crystalline properties,molecular weight and its distribution,surface morphologies,as well as infrared absorption peaks and hydrogen chemical shifts during the degradation.It is found that the water absorption increases whilst the intrinsic viscosity,tensile strength and elongation at break decrease as the temperature or relative humidity increases.With degradation time growing,the molecular weight drops and its distribution broadens.The crystallinity of PPDO has a tendency to increase at first and then to decrease,while the crystalline structure is not significantly changed.At the same time,some cracks are observed on the surface and keep growing and deepening.All results show that temperature plays more significant roles than relative humidity during the degradation.The analyses of Fourier transform infrared spectroscopy and hydrogen nuclear magnetic resonance spectroscopy reveal that the degradation of PPDO is a predominant hydrolysis of ester linkages.

Ubiquitination is absolutely required for the degradation of hypoxia-inducible factor - 1 alpha protein in hypoxic conditions

International Nuclear Information System (INIS)

Wang, Ronghai; Zhang, Ping; Li, Jinhang; Guan, Hongzai; Shi, Guangjun

2016-01-01

The hypoxia-inducible factor (HIF) is recognized as the master regulator of hypoxia response. HIF-α subunits expression are tightly regulated. In this study, our data show that ts20 cells still expressed detectable E1 protein even at 39.5° C for 12 h, and complete depletion of E1 protein expression at 39.5° C by siRNA enhanced HIF-1α and P53 protein expression. Further inhibition of E1 at 39.5 °C by siRNA, or E1 inhibitor Ube1-41 completely blocked HIF-1α degradation. Moreover, immunoprecipitations of co-transfection of HA-ubiquitin and FLAG–HIF–1α plasmids directly confirmed the involvement of ubiquitin in the hypoxic degradation of HIF-1α. Additionally, hypoxic HIF-1 α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization. Taken together, our data suggest that constitutive HIF-1α protein degradation in hypoxia is absolutely ubiquitination-dependent, and unidentified E3 ligase may exist for this degradation pathway. - Highlights: • HIF-1α protein is constitutively degraded in hypoxic conditions. • Requirement of ubiquitination for HIF-1α degradation in hypoxia. • Hypoxic HIF-1α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization.

Ubiquitination is absolutely required for the degradation of hypoxia-inducible factor - 1 alpha protein in hypoxic conditions

Energy Technology Data Exchange (ETDEWEB)

Wang, Ronghai [Department of Urology, Linzi District People' s Hospital, Zibo, 255400 (China); Zhang, Ping, E-mail: zpskx001@163.com [Department of Gynecology, Qingdao Municipal Hospital, Qingdao, 266011 (China); Li, Jinhang [Department of Gynecology, Qingdao Municipal Hospital, Qingdao, 266011 (China); Guan, Hongzai [Laboratory Department, School of Medicine, Qingdao University, Qingdao, 266071 (China); Shi, Guangjun, E-mail: qdmhshigj@yahoo.com [Department of Hepatobiliary Surgery, Qingdao Municipal Hospital, Qingdao, 266071 (China)

2016-01-29

The hypoxia-inducible factor (HIF) is recognized as the master regulator of hypoxia response. HIF-α subunits expression are tightly regulated. In this study, our data show that ts20 cells still expressed detectable E1 protein even at 39.5° C for 12 h, and complete depletion of E1 protein expression at 39.5° C by siRNA enhanced HIF-1α and P53 protein expression. Further inhibition of E1 at 39.5 °C by siRNA, or E1 inhibitor Ube1-41 completely blocked HIF-1α degradation. Moreover, immunoprecipitations of co-transfection of HA-ubiquitin and FLAG–HIF–1α plasmids directly confirmed the involvement of ubiquitin in the hypoxic degradation of HIF-1α. Additionally, hypoxic HIF-1 α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization. Taken together, our data suggest that constitutive HIF-1α protein degradation in hypoxia is absolutely ubiquitination-dependent, and unidentified E3 ligase may exist for this degradation pathway. - Highlights: • HIF-1α protein is constitutively degraded in hypoxic conditions. • Requirement of ubiquitination for HIF-1α degradation in hypoxia. • Hypoxic HIF-1α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization.

The study of evaluation methodology of the aging and degradation researches

International Nuclear Information System (INIS)

Cho, C. J.; Park, Z. H.; Jeong, I. S.

2001-01-01

To judge the usefulness of aging related researches like PLIM (Plant lifetime Management) and aging related degradation, et. al. in PSR(Periodic Safety Review), the evaluation methodology of the R and D have been proposed up to now are reviewed. The infometric methodology is considered to be the optimum method for the evaluation of the nuclear related researches. And finally, to increase the objectiveness and reliability of the infometric methodology in the aging and degradation researches, the indexes of safety, technology and economics are introduced. From this study, the infometric methodology has the advantage of the actual engineering evaluation in the nuclear related researches with other methodologies, but for the further research, the effective construction of DB and survey of various statistics in the technical reports and papers are needed

Proceedings of the topical meeting on nuclear power plant life extension

International Nuclear Information System (INIS)

Anon.

1988-01-01

This book contains the proceedings of the topical meeting on nuclear power plant life extension. The sessions are organized under the following headings: Perspectives on nuclear power plant life extension, the potential for additional years of power production, NRC and industry life extension initiatives, concrete and structures degradation and evaluation of useful remaining life, plant life extension programs, Reactor pressure vessel and intervals degradation and evaluation of useful remaining life, life extension decision making issues and institutions, systems degradation and evaluation of remaining life, monitoring and repair, design records and maintenance activities for life extension, Mechanical and electrical component degradation and evaluation of remaining life, expert systems and other techniques for enhanced and continued operation, life extension aspect of codes, standards, and related technologies, piping and valve degradation and evaluation of useful remaining life

Single HIV-1 Imaging Reveals Progression of Infection through CA-Dependent Steps of Docking at the Nuclear Pore, Uncoating, and Nuclear Transport.

Science.gov (United States)

Francis, Ashwanth C; Melikyan, Gregory B

2018-04-11

The HIV-1 core consists of capsid proteins (CA) surrounding viral genomic RNA. After virus-cell fusion, the core enters the cytoplasm and the capsid shell is lost through uncoating. CA loss precedes nuclear import and HIV integration into the host genome, but the timing and location of uncoating remain unclear. By visualizing single HIV-1 infection, we find that CA is required for core docking at the nuclear envelope (NE), whereas early uncoating in the cytoplasm promotes proteasomal degradation of viral complexes. Only docked cores exhibiting accelerated loss of CA at the NE enter the nucleus. Interestingly, a CA mutation (N74D) altering virus engagement of host factors involved in nuclear transport does not alter the uncoating site at the NE but reduces the nuclear penetration depth. Thus, CA protects HIV-1 complexes from degradation, mediates docking at the nuclear pore before uncoating, and determines the depth of nuclear penetration en route to integration. Copyright © 2018 Elsevier Inc. All rights reserved.

OECD/NEA component operational experience, degradation and ageing project

International Nuclear Information System (INIS)

Gott, K.; Nevander, O.; Riznic, J.; Lydell, B.

2015-01-01

Several OECD Member Countries have agreed to establish the OECD/NEA 'Component Operational Experience, Degradation and Ageing Programme' (CODAP) to encourage multilateral co-operation in the collection and analysis of data relating to degradation and failure of metallic piping and non-piping metallic passive components in commercial nuclear power plants. The scope of the data collection includes service-induced wall thinning, part through-wall cracks, through-wall cracks with and without active leakage, and instances of significant degradation of metallic passive components, including piping pressure boundary integrity. CODAP is the continuation of the 2002-2011 'OECD/NEA Pipe Failure Data Exchange Project' (OPDE) and the Stress Corrosion Cracking Working Group of the 2006-2010 - OECD/NEA SCC and Cable Ageing project - (SCAP). OPDE was formally launched in May 2002. Upon completion of the 3. Term (May 2011), the OPDE project was officially closed to be succeeded by CODAP. In May 2011, 13 countries signed the CODAP first Term agreement. The first Term (2011-2014) work plan includes the development of a web-based relational event database on passive, metallic components in commercial nuclear power plants, a web-based knowledge base on material degradation, codes and standards relating to structural integrity and national practices for managing material degradation. The work plan also addresses the preparation of Topical Reports to foster technical cooperation and to deepen the understanding of national differences in ageing management. These Topical Reports are in the public domain and available for download on the NEA web site. Published in 2014, a first Topical Report addressed flow accelerated corrosion (FAC) of carbon steel and low alloy steel piping. A second Topical Report addresses operating experience with electro-hydraulic control (EHC) and instrument air (IA) system piping

Study of the degradation of organic molecules complexing radionuclides by using Advanced Oxidation Processes

International Nuclear Information System (INIS)

Rekab, K.

2014-01-01

This research thesis reports the study of the application of two AOPs (Advanced Oxidation Processes) to degrade and mineralise organic molecules which are complexing radio-elements, and thus to allow their concentrations by trapping on mineral matrices. EDTA (ethylene diamine tetraacetic acid) is chosen as reference organic complexing agent for preliminary tests performed with inactive cobalt 59 before addressing actual nuclear effluents with active cobalt 60. The author first presents the industrial context (existing nuclear wastes, notably liquid effluents and their processing) and proposes an overview of the state of the art on adsorption and precipitation of cobalt (natural and radioactive isotope). Then, the author presents the characteristics of the various studied oxides, the photochemical reactor used to perform tests, experimental techniques and operational modes. Results are then presented regarding various issues: adsorption of EDTA and the Co-EDTA complex, and cobalt precipitation; determination of the lamp photon flow by chemical actinometry and by using the Keitz method; efficiency of different processes (UV, UV/TiO 2 , UV/H 2 O 2 ) to degrade EDTA and to degrade the Co-EDTA complex; processing of a nuclear effluent coming from La Hague pools with determination of decontamination factors

Detection of pump degradation

International Nuclear Information System (INIS)

Casada, D.

1995-01-01

There are a variety of stressors that can affect the operation of centrifugal pumps. Although these general stressors are active in essentially all centrifugal pumps, the stressor level and the extent of wear and degradation can vary greatly. Parameters that affect the extent of stressor activity are manifold. In order to assure the long-term operational readiness of a pump, it is important to both understand the nature and magnitude of the specific degradation mechanisms and to monitor the performance of the pump. The most commonly applied method of monitoring the condition of not only pumps, but rotating machinery in general, is vibration analysis. Periodic or continuous special vibration analysis is a cornerstone of most pump monitoring programs. In the nuclear industry, non-spectral vibration monitoring of safety-related pumps is performed in accordance with the ASME code. Pump head and flow rate are also monitored, per code requirements. Although vibration analysis has dominated the condition monitoring field for many years, there are other measures that have been historically used to help understand pump condition; advances in historically applied technologies and developing technologies offer improved monitoring capabilities. The capabilities of several technologies (including vibration analysis, dynamic pressure analysis, and motor power analysis) to detect the presence and magnitude of both stressors and resultant degradation are discussed

Nuclear plant-aging research on reactor protection systems

International Nuclear Information System (INIS)

Meyer, L.C.

1988-01-01

This report presents the rsults of a review of the Reactor Trip System (RTS) and the Engineered Safety Feature Actuating System (ESFAS) operating experiences reported in Licensee Event Reports (LER)s, the Nuclear Power Experience data base, Nuclear Plant Reliability Data System, and plant maintenance records. Our purpose is to evaluate the potential significance of aging, including cycling, trips, and testing as contributors to degradation of the RTS and ESFAS. Tables are presented that show the percentage of events for RTS and ESFAS classified by cause, components, and subcomponents for each of the Nuclear Steam Supply System vendors. A representative Babcock and Wilcox plant was selected for detailed study. The US Nuclear Regulatory Commission's Nuclear Plant Aging Research guidelines were followed in performing the detailed study that identified materials susceptible to aging, stressors, environmental factors, and failure modes for the RTS and ESFAS as generic instrumentation and control systems. Functional indicators of degradation are listed, testing requirements evaluated, and regulatory issues discussed

Evaluation of cable aging degradation based on plant operating condition

International Nuclear Information System (INIS)

Kim, Jong-Seog

2005-01-01

Extending the lifetime of nuclear power plant [(hereafter referred simply as ''NPP'')] is one of the most important concerns in the world nuclear industry. Cables are one of the long live items which have not been considered to be replaced during the design life of NPP. To extend the cable life beyond the design life, we need to prove that the design life is too conservative compared with the actual aging. Condition monitoring is one of the useful ways for evaluating the aging condition of cable. In order to simulate the natural aging in nuclear power plant, a study on accelerated aging needs to be conducted first. In this paper, evaluations of mechanical aging degradation for cable jacket were performed after accelerated aging under the continuous heating and intermittent heating. Contrary to general expectation, the intermittent heating to cable jacket showed low aging degradation, 50% break-elongation and 60% indenter modulus, compared with continuous heating. With the plant maintenance period of 1 month after every 12 or 18 months operation, we can easily deduce that the life time of cable jacket can be extended much longer than estimated through the general EQ (Environmental Qualification) test, which adopts continuous accelerated aging for determining cable life. Therefore, a systematic approach which considers the actual environment condition of nuclear power plant is required for determining the life of cables. (author)

Experimental study of radioactive aerosols emission during the thermal degradation of organic materials in nuclear facilities

International Nuclear Information System (INIS)

Fernandez, Yvette

1993-01-01

Radioactive products may be released during a fire in nuclear fuel cycles facilities. These products must be confined to avoid a contamination spread in the environment. It is therefore necessary to be able to predict the amount and the physico-chemical forms of radioactive material that may be airborne. The aim of this study is to determine experimentally the release of contamination aerosols in a typical fire scenario involving plutonium oxide in a glove box. Firstly, this phenomenon has been studied in a small scale test chamber where samples of polymethylmethacrylate (Plexiglas) contaminated by cerium oxide (used as a substitute for plutonium oxide) were submitted to thermal degradation (pyrolysis and combustion). The release of radioactive material is determined by the quantity of contaminant emitted, the kinetics of the release and the particle size distribution of aerosols. Secondly, the development of an experimental procedure allowed to realize large scale fires in more realistic conditions. The experimental tools developed in the course of this study allow to consider application to other scenarios. (author) [fr

Finite element analysis of degraded concrete structures - Workshop proceedings

International Nuclear Information System (INIS)

1999-09-01

This workshop is related to the finite element analysis of degraded concrete structures. It is composed of three sessions. The first session (which title is: the use of finite element analysis in safety assessments) comprises six papers which titles are: Historical Development of Concrete Finite Element Modeling for Safety Evaluation of Accident-Challenged and Aging Concrete Structures; Experience with Finite Element Methods for Safety Assessments in Switzerland; Stress State Analysis of the Ignalina NPP Confinement System; Prestressed Containment: Behaviour when Concrete Cracking is Modelled; Application of FEA for Design and Support of NPP Containment in Russia; Verification Problems of Nuclear Installations Safety Software of Strength Analysis (NISS SA). The second session (title: concrete containment structures under accident loads) comprises seven papers which titles are: Two Application Examples of Concrete Containment Structures under Accident Load Conditions Using Finite Element Analysis; What Kind of Prediction for Leak rates for Nuclear Power Plant Containments in Accidental Conditions; Influence of Different Hypotheses Used in Numerical Models for Concrete At Elevated Temperatures on the Predicted Behaviour of NPP Core Catchers Under Severe Accident Conditions; Observations on the Constitutive Modeling of Concrete Under Multi-Axial States at Elevated Temperatures; Analyses of a Reinforced Concrete Containment with Liner Corrosion Damage; Program of Containment Concrete Control During Operation for the Temelin Nuclear Power Plant; Static Limit Load of a Deteriorated Hyperbolic Cooling Tower. The third session (concrete structures under extreme environmental load) comprised five papers which titles are: Shear Transfer Mechanism of RC Plates After Cracking; Seismic Back Calculation of an Auxiliary Building of the Nuclear Power Plant Muehleberg, Switzerland; Seismic Behaviour of Slightly Reinforced Shear Wall Structures; FE Analysis of Degraded Concrete

Evaluation of proposed degradation algorithms for multiburst environments

International Nuclear Information System (INIS)

Olness, D.U.; Warshawsky, A.S.

1993-01-01

This work is part of an ongoing effort of the Defense Nuclear Agency's Intermediate Dose Program to investigate the effects of intermediate radiation doses on combat unit performance. The objective of this study is to develop an improved technique for applying performance degradation factors to combat crews in simulated battles following multiple radiation doses on the tactical battlefield. A further objective of the study is to quantify differences in Janus results when crew performance factors, following multiple radiation doses, are obtained from the improved technique instead of from the technique used previously. In this paper, the authors describe and evaluate three methods previously identified for determining performance degradation from multiple exposures. They also present the observed quantitative differences in outcomes of conventional battles begun a few hours after multiple radiation exposures when alternate techniques for calculating combat crew performance degradation factors are included in the Janus combat simulation

Modeling the degradation of a metallic waste form intended for geologic disposal

International Nuclear Information System (INIS)

Bauer, T.H.; Morris, E.E.

2007-01-01

Nuclear reactors operating with metallic fuels have led to development of robust metallic waste forms intended to immobilize hazardous constituents in oxidizing environments. Release data from a wide range of tests where small waste form samples have been immersed in a variety of oxidizing solutions have been analyzed and fit to a mechanistically-derived 'logarithmic growth' form for waste form degradation. A bounding model is described which plausibly extrapolates these fits to long-term degradation in a geologic repository. The resulting empirically-fit degradation model includes dependence on solution pH, temperature, and chloride concentration as well as plausible estimates of statistical uncertainty. (authors)

Dutch nuclear power and the environmental implications of uranium mining and milling

International Nuclear Information System (INIS)

Thornton, S.J.

1986-04-01

This report is aimed at furthering the understanding of some of the international impacts of Dutch nuclear power generation. It has two principle objectives: 1. To clarify the connection between nuclear power generation in the Netherlands and environmental degradation elsewhere as a result of the mining and milling of uranium. 2. To establish the relevance of this environmental degradation to the formulation of Dutch energy policy. (Auth.)

Contribution to the study of the degradation of the solvent used in a nuclear fuel reprocessing plant

International Nuclear Information System (INIS)

Goasmat, F.

1984-01-01

The degradation of a mixed solvent (tributylphosphate - hydrocarbons) in a fuel reprocessing plant (UP 2 at La Hague, France) is studied in this thesis. Laboratory studies on degradation mechanisms, decomposition products and regeneration processes are reviewed in a bibliographic synthesis. Solvent degradation is investigated on a real solvent from a reprocessing plant. Influence of degradation on solvent performance is shown and regeneration processes should be improved. Many regeneration processes are tested on solvent from the plant and results are discussed. Separation and analysis of degradation products show the polyfunctional structure of compounds formed [fr

Seismic soil–structure interaction analysis of a nuclear power plant building founded on soil and in degraded concrete stiffness condition

International Nuclear Information System (INIS)

Farahani, Reza V.; Dessalegn, Tewodros M.; Vaidya, Nishikant R.; Bazan-Zurita, Enrique

2016-01-01

Highlights: • Three dimensional finite element modeling of a Nuclear Power Plant (NPP) building founded on soil is described. • A simplified technique to consider degraded stiffness of concrete members in seismic analysis of NPP buildings is presented. • The effect of subsurface profiles on the seismic response of a NPP building is investigated. - Abstract: This study describes three-dimensional (3-D) finite element (FE) modeling and seismic Soil-Structure Interaction (SSI) analysis of a Nuclear Power Plant (NPP) Diesel Generator Building (DGB) that is founded on soil in degraded concrete stiffness condition. A new technique is presented that uses two horizontal and vertical FE models to consider the concrete stiffness reduction of NPP buildings subjected to orthogonal ground motion excitations, in which appropriate stiffness reduction factors, based on the input motion orientation, are applied. Seismic SSI analysis is performed for each model separately, and dynamic responses are calculated in the three global directions. The results of the analysis for the two FE models are then combined, using the square-root-of-the-sum-of-squares (SRSS) combination rule. A sensitivity analysis is also performed to investigate the subsurface profile effect on the In-Structure (acceleration) Response Spectra (ISRS) of the building when subjected to site-specific Foundation Input Response Spectra (FIRS) that exhibit high spectral amplifications in the high-frequency range. The sensitivity analysis considers three strain-compatible subsurface profiles that represent Lower-Bound (LB), Best-Estimate (BE), and Upper-Bound (UB) conditions at the DGB site. The sensitivity analysis results indicate that the seismic response of the DGB founded on soil highly depends on the subsurface profile; i.e., each of the LB, BE, and UB subsurface profiles can maximize building seismic response when subjected to FIRS that exhibit high spectral amplifications in the high-frequency range

Evolution of the feedback from experience on degradations of French nuclear power plants condensers and foreseen solutions

Energy Technology Data Exchange (ETDEWEB)

Mayos, M.; Chanel, F.; Copin, E.; Carlier, L. [EDF/DIN/CEIDRE, Saint-Denis (France); Coquio, N.; Garbay, E. [EDF/DIN/CEIDRE, Avoine (France); Bastian, C. [EDF/DPN/UNIE, Saint-Denis (France)

2011-07-01

The materials constituting the condenser tubes of French nuclear power plants display a great diversity and are subject to different degradations, known from the operational feedback from experience. Copper alloys (mainly brass), which were bound to disappear in renovated condensers, are still significantly present, due to their unique bacteriostatic ability. Brass tubes lifetime is still governed in general by steady abrasion, as evaluated by eddy current nondestructive testing. However, an atypical NDE (non-destructive evaluation) behavior has led to spot a new damage: localized under-deposit pitting corrosion on the raw water side, caused by the particular quality of water chemistry and heavy scaling of the tube surface. This damage is likely to overcome steady abrasion for tube life prediction. Prevention includes a tighter look at NDE indications and improved descaling solutions (chemical or mechanical). Other specific damages have been reported from operation feedback: the main one was accidental stress corrosion cracking, which has occurred on some recently renovated brass condenser tube bundles. Thanks to a metallurgical and mechanical study, its cause was found in the manufacturing process. This experience has resulted in tightened specifications for brass tubes manufacturing. Stainless steel and titanium still appear more damage-resistant and represent a safe solution when no microorganism issue is present. The degradation feedback, confirmed by NDE inspections, is very low in French power plants. However, titanium hydriding still represents an issue when cathodic protection is present. Furthermore, some other damages have been reported on titanium, like isolated steam erosion. Vibration fatigue damage has been observed on stainless steel tubes, but it is more in relationship with the condenser design than with the material itself. (authors)

Degradation of ion spent resin using the Fenton's reagent

International Nuclear Information System (INIS)

Araujo, Leandro Goulart de

2013-01-01

The most common method for spent radioactive ion exchange resin treatment is its immobilization in cement, which reduces the radionuclides release into the environment. Although this method is efficient, it increases considerably the final volume of the waste due to the low incorporation capacity. The objective of this work was to develop a degradation method of spent resins arising from the nuclear research reactor located at the Nuclear and Energy Research Institute (IPEN-CNEN/SP), using an Advanced Oxidation Process (AOP) with Fenton's reagents. This method would allow a higher incorporation in cement. Three different resins were evaluated: cationic, anionic and a mixture of both resins. The reactions were conducted varying the catalyst concentration (25, 50, 100 and 150 mM), the volume of hydrogen peroxide (320 to 460 mL), and three different temperatures, 50, 60 and 70 deg C. Degradation of about 98% was achieved using a 50 mM catalyst solution and 330 mL of hydrogen peroxide solution. The most efficient temperature was 60 deg C. (author)

Mecanical Properties Degradation by Hydrogen Embrittlement

International Nuclear Information System (INIS)

Bertolino, G; Meyer, G; Perez Ipina J

2001-01-01

The presence of hydrogen-rich media during nuclear plant operation motivates the study of the zirconium alloys degradation of their mechanical properties influenced by hydrogen content and temperature.In this work we study samples with a microstructure of equiaxial grains resulted from hot-rolled, and with different homogeneous hydrogen content obtained by electrochemical charge and a thermal treatment.The influence of hydrogen content and temperature was analyzed from the results of fracture-mechanical tests on CT (compact test) probes using the J-criteria

Zircaloy cladding degradation under repository conditions

International Nuclear Information System (INIS)

Santanam, L.; Raghavan, S.; Chin, B.A.

1990-12-01

Creep, a potential degradation mechanism of Zircaloy cladding after repository disposal of spent nuclear fuel, has been investigated. The deformation and fracture map methodology has been used to predict maximum allowable initial storage temperatures to achieve a thousand year life without rupture as a function of spent-fuel history. Maximum allowable temperatures are 340 degree C (613 K) for typically stressed rods (70--100 MPa) and 300 degree C (573 K) for highly stressed rods (140--160 MPa). 10 refs., 2 figs

Nuclear containment systems and in-service inspection status of Korea nuclear power plants

Energy Technology Data Exchange (ETDEWEB)

Jihong, Park; Jaekeun, Hong; Banuk, Park [Korea Institute of Machinery and Materials, Dept. of Authorized Test and Evaluation, Kyungnam (Korea, Republic of)

2007-07-01

20 unit nuclear power plants in Korea have been operated and maintained since the first unit started in commercial service in 1978. Most recently 4 units were under construction and several units were planned to be constructed. by industries. 4 types of nuclear containment systems have been constructed until now: first, metal containments, then pre-stressed concrete containments with grouted tendon systems, followed by pre-stressed concrete containments with un-grouted tendon systems, and Korea standard nuclear containments. All the nuclear containments should be inspected periodically. Therefore for periodic in-service inspection, several appropriate technical requirements should be applied differently depending on the specific nuclear containment types. With the changes of times, nuclear containment systems have undergone a remarkable change, and finally nuclear containment system of Korea standard nuclear power plant was settled down, and as a matter of course it dominates the trend of present and future nuclear containment systems. Overall in-service inspection results of most Korea nuclear containments have not showed any serious evidence of degradation.

Aging of control and service air compressors and dryers used in nuclear power plants

International Nuclear Information System (INIS)

Moyers, J.C.

1990-07-01

This report was produced under the Detection of Defects and Degradation Monitoring of Nuclear Plant Safety Equipment element of the Nuclear Plant Aging Research Program. This element includes the identification of practical and cost-effective methods for detecting, monitoring, and assessing the severity of time-dependent degradation (aging) of control and service air compressors and dryers in nuclear power plants. These methods are to provide capabilities for establishing degradation trends prior to failure and developing guidance for effective maintenance. The topics of this Phase 1 assessment report are failure modes and causes resulting from aging, manufacturer--recommended maintenance and surveillance practices, and measurable parameters (including functional indicators) for use in assessing operational readiness, establishing degradation trends, and detecting incipient failure. the results presented are based on information derived from operating experience records, manufacturer-supplied information, and input from plant operators. For each failure mode, failure causes are listed by subcomponent, and parameters potentially useful for detecting degradation that could lead to failure are identified. 13 refs., 9 figs., 16 tabs

Sustainable nuclear energy dilemma

Directory of Open Access Journals (Sweden)

Afgan Naim H.

2013-01-01

Full Text Available Sustainable energy development implies the need for the emerging potential energy sources which are not producing adverse effect to the environment. In this respect nuclear energy has gained the complimentary favor to be considered as the potential energy source without degradation of the environment. The sustainability evaluation of the nuclear energy systems has required the special attention to the criteria for the assessment of nuclear energy system before we can make firm justification of the sustainability of nuclear energy systems. In order to demonstrate the sustainability assessment of nuclear energy system this exercise has been devoted to the potential options of nuclear energy development, namely: short term option, medium term option, long term option and classical thermal system option. Criteria with following indicators are introduced in this analysis: nuclear indicator, economic indicator, environment indicator, social indicator... The Sustainability Index is used as the merit for the priority assessment among options under consideration.

Chemical degradation of proton conducting perflurosulfonic acid ionomer membranes studied by solid-state nuclear magnetic resonance spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Ghassemzadeh, L. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Institut fuer Physikalische Chemie, Universitaet Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany); Marrony, M. [European Institute for Energy Research, Emmy-Noether-Strasse 11, D-76131 Karlsruhe (Germany); Barrera, R. [Edison, Via Giorgio La Pira, 2, I-10028 Trofarello (Italy); Kreuer, K.D.; Maier, J. [Max-Planck-Institut fuer Festkoerperforschung, Heisenbergstrasse 1, D-70569 Stuttgart (Germany); Mueller, K. [Institut fuer Physikalische Chemie, Universitaet Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart (Germany)

2009-01-15

The degradation of two different types of perfluorinated polymer membranes, Nafion and Hyflon Ion, has been examined by solid-state {sup 19}F and {sup 13}C NMR spectroscopy. This spectroscopic technique is demonstrated to be a valuable tool for the study of the membrane structure and its alterations after in situ degradation in a fuel cell. The structural changes in different parts of the polymers are clearly distinguished, which provides unique insight into details of the degradation processes. The experimental NMR spectra prove that degradation mostly takes place within the polymer side chains, as reflected by the intensity losses of NMR signals associated with SO{sub 3}H, CF{sub 3}, OCF{sub 2} and CF groups. The integral degree of degradation is found to decrease with increasing membrane thickness while for a given thickness, Hyflon Ion appears to degrade less than Nafion. (author)

Degradation of polyethylene by Trichoderma harzianum--SEM, FTIR, and NMR analyses.

Science.gov (United States)

Sowmya, H V; Ramalingappa; Krishnappa, M; Thippeswamy, B

2014-10-01

Trichoderma harzianum was isolated from local dumpsites of Shivamogga District for use in the biodegradation of polyethylene. Soil sample of that dumpsite was used for isolation of T. harzianum. Degradation was carried out using autoclaved, UV-treated, and surface-sterilized polyethylene. Degradation was monitored by observing weight loss and changes in physical structure by scanning electron microscopy, Fourier transform infrared spectroscopy, and nuclear magnetic resonance spectroscopy. T. harzianum was able to degrade treated polyethylene (40%) more efficiently than autoclaved (23%) and surface-sterilized polyethylene (13%). Enzymes responsible for polyethylene degradation were screened from T. harzianum and were identified as laccase and manganese peroxidase. These enzymes were produced in large amount, and their activity was calculated using spectrophotometric method and crude extraction of enzymes was carried out. Molecular weight of laccase was determined as 88 kDa and that of manganese peroxidase was 55 kDa. The capacity of crude enzymes to degrade polyethylene was also determined. By observing these results, we can conclude that this organism may act as solution for the problem caused by polyethylene in nature.

CLAD DEGRADATION - FEPS SCREENING ARGUMENTS

International Nuclear Information System (INIS)

R. Schreiner

2004-01-01

The purpose of this report is to evaluate and document the screening of the clad degradation features, events, and processes (FEPs) with respect to modeling used to support the Total System Performance Assessment-License Application (TSPA-LA). This report also addresses the effect of certain FEPs on both the cladding and the commercial spent nuclear fuel (CSNF), DOE-owned spent nuclear fuel (DSNF), and defense high-level waste (DHLW) waste forms, as appropriate to address the effects on multiple materials and both components (FEPs 2.1.09.09.0A, 2.1.09.11.0A, 2.1.11.05.0A, 2.1.12.02.0A, and 2.1.12.03.0A). These FEPs are expected to affect the repository performance during the postclosure regulatory period of 10,000 years after permanent closure. Table 1-1 provides the list of cladding FEPs, including their screening decisions (include or exclude). The primary purpose of this report is to identify and document the analysis, screening decision, and TSPA-LA disposition (for included FEPs) or screening argument (for excluded FEPs) for these FEPs related to clad degradation. In some cases, where a FEP covers multiple technical areas and is shared with other FEP reports, this report may provide only a partial technical basis for the screening of the FEP. The full technical basis for shared FEPs is addressed collectively by the sharing FEP reports. The screening decisions and associated TSPA-LA dispositions or screening arguments from all of the FEP reports are cataloged in a project-specific FEPs database

Identification and Assessment of Recent Aging-Related Degradation Occurrences in U.S. Nuclear Power Plants

International Nuclear Information System (INIS)

Choi, In Kil; Kim, Min Kyu; Choun, Young Sun; Hofmayer, Charles; Braverman, Joseph; Nie, Jinsou

2008-11-01

This report describes the research effort performed by BNL for the Year 1 scope of work. This research focused on collecting and reviewing degradation occurrences in US NPPs and identifying important aging characteristics needed for the seismic capability evaluations that will be performed in the subsequent evaluations in the years that follow. The report presents results of the statistical and trending analysis of this data and compares the results to prior aging studies. In addition, this report provides a description of current regulatory requirements, regulatory guidance documents, generic communications, industry standards and guidance, and past research related to aging degradation of SSCs. Finally, this report provides the conclusions reached from this research effort, which includes a summary of the findings from the identification and evaluation effort of degradation occurrences, an assessment of the degradation trending results, and insights into the important aging characteristics that should be considered in the tasks to be performed in the Year 2 through 5 research effort

The degradation of zirconium alloys in nuclear reactors - a review

International Nuclear Information System (INIS)

Lim, D.; Graham, N.A.

1986-01-01

This report presents the findings of a survey of available non-Canadian literature on the oxidation and hydriding of zirconium alloys. Much of the literature was found to address the Zircaloys, particularly when used as fuel cladding subjected to a radioactive and oxidizing environment. Hydriding of Zircaloys is mainly attributed to oxidation. The survey revealed that Zr-Nb alloys have been included in some investigations; however, data on the long-term degradation of Zr-2.5 wt% Nb, in particular, were scarce. The reviewed literature did not lead to conclusions regarding the potential for accelerated hydriding due to corrosion at crevices and/or second-phase particles, nor did it lead to conclusions as to the potential for a 'breakaway' in oxidation and hydrogen acquisition in long service life of Zr-Nb alloys. Specific information on service experience in U.S.S.R. power reactors could not be obtained; however, most of the information surveyed leads to the conclusion that fuel channels having Zr-2.5 wt% Nb pressure tubes should perform satisfactorily with respect to degradation from corrosion and hydriding provided they are installed correctly and are not operated under conditions that are far removed from those anticipated in design. 91 refs

Role of apoptosis-inducing factor (AIF in programmed nuclear death during conjugation in Tetrahymena thermophila

Directory of Open Access Journals (Sweden)

Endoh Hiroshi

2010-02-01

Full Text Available Abstract Background Programmed nuclear death (PND, which is also referred to as nuclear apoptosis, is a remarkable process that occurs in ciliates during sexual reproduction (conjugation. In Tetrahymena thermophila, when the new macronucleus differentiates, the parental macronucleus is selectively eliminated from the cytoplasm of the progeny, concomitant with apoptotic nuclear events. However, the molecular mechanisms underlying these events are not well understood. The parental macronucleus is engulfed by a large autophagosome, which contains numerous mitochondria that have lost their membrane potential. In animals, mitochondrial depolarization precedes apoptotic cell death, which involves DNA fragmentation and subsequent nuclear degradation. Results We focused on the role of mitochondrial apoptosis-inducing factor (AIF during PND in Tetrahymena. The disruption of AIF delays the normal progression of PND, specifically, nuclear condensation and kilobase-size DNA fragmentation. AIF is localized in Tetrahymena mitochondria and is released into the macronucleus prior to nuclear condensation. In addition, AIF associates and co-operates with the mitochondrial DNase to facilitate the degradation of kilobase-size DNA, which is followed by oligonucleosome-size DNA laddering. Conclusions Our results suggest that Tetrahymena AIF plays an important role in the degradation of DNA at an early stage of PND, which supports the notion that the mitochondrion-initiated apoptotic DNA degradation pathway is widely conserved among eukaryotes.

AGE RELATED DEGRADATION OF STEAM GENERATOR INTERNALS BASED ON INDUSTRY RESPONSES TO GENERIC LETTER 97-06

International Nuclear Information System (INIS)

SUBUDHI, M.; SULLIVAN, JR. E.J.

2002-01-01

THIS PAPER PRESENTS THE RESULTS OF AN AGING ASSESSMENT OF THE NUCLEAR POWER INDUSTRY RESPONSES TO NRC GENERIC LETTER 97-06 ON THE DEGRADATION OF STEAM GENERATOR INTERNALS EXPERIENCED AT ELECTRICITE DE FRANCE (EDF) PLANTS IN FRANCE AND AT A UNITED STATES PRESSURIZED WATER REACTOR (PWR). WESTINGHOUSE (W), COMBUSTION ENGINEERING (CE), AND BABCOCK AND WILCOX (BW) STEAM GENERATOR MODELS, CURRENTLY IN SERVICE AT U.S. NUCLEAR POWER PLANTS, POTENTIALLY COULD EXPERIENCE DEGRADATION SIMILAR TO THATFOUND AT EDF PLANTS AND THE U.S. PLANT. THE STEAM GENERATORS IN MANY OF THE U.S. PWRS HAVE BEEN REPLACED WITH STEAM GENERATORS WITH STEAM GENERATORS WITH IMPROVED DESIGNS AND MATERIALS. THESE REPLACEMENT STEAM GENERATORS HAVE BEEN MANUFACTURED IN THE U.S. AND ABROAD. DURING THIS ASSESSMENT, EACH OF THE THREE OWNERS GROUPS (W,CE, AND BW) IDENTIFIED FOR ITS STEAM GENERATOR, MODELS ALL THE POTENTIAL INTERNAL COMPONENTS THAT ARE VULNERABLE TO DEGRADATION WHILE IN SERVICE. EACH OWNERS GROUPDEVELOPED INSPEC TION AND MONITORING GUIDANCE AND RECOMMENDATIONS FOR ITS PARTICULAR STEAM GENERATOR MODELS. THE NUCLEAR ENERGY INSTITUTE INCORPORATED IN NEI 97-06 STEAM GENERATOR PROGRAM GUIDELINES, A REQUIREMENT TO MONITOR SECONDARY SIDE STEAM GENERATOR COMPONENTS IF THEIR FAILURE COULD PREVENT THE STEAM GENERATOR FROM FULFILLING ITS INTENDED SAFETY-RELATED FUNCTION. LICENSEES INDICATED THAT THEY IMPLEMENTED OR PLANNED TO IMPLEMENT, AS APPROPRIATE FOR THEIR STEAM GENERATORS, THEIR OWNERS GROUPRECOMMENDATIONS TO ADDRESS THE LONG-TERM EFFECTS OF THE POTENTIAL DEGRADATION MECHANISMS ASSOCIATED WITH THE STEAM GENERATOR INTERNALS

Thermal shield support degradation in pressurized water reactors

International Nuclear Information System (INIS)

Sweeney, F.J.; Fry, D.N.

1986-01-01

Damage to the thermal shield support structures of three pressurized water reactors (PWRs) due to flow-induced vibrations was recently discovered during refueling. In two of the reactors, severe damage occurred to the thermal shield, and in one reactor the core support barrel (CSB) was damaged, necessitating extended outages for repairs. In all three reactors, several of the thermal shield supports were either loose, damaged, or missing. The three plants had been in operation for approximately 10 years before the damage was apparent by visual inspection. Because each of the three US PWR manufacturers have experienced thermal shield support degradation, the Nuclear Regulatory Commission requested that Oak Ridge National Laboratory analyze ex-core neutron detector noise data to determine the feasibility of detecting incipient thermal shield support degradation. Results of the noise data analysis indicate that thermal shield support degradation probably began early in the life of both severely damaged plants. The degradation was characterized by shifts in the resonant frequencies of core internal structures and the appearance of new resonances in the ex-core neutron detector noise. Both the data analyses and the finite element calculations indicate that these changes in resonant frequencies are less than 3 Hz. 11 refs., 16 figs

State-of-the-art review of OPG steam generator tubing degradation mechanisms

International Nuclear Information System (INIS)

Brennenstuhl, A.M.; Ramamurthy, S.; Good, G.M.

2009-01-01

Steam generator (SG) degradation has been a major cause of pressurized water reactor (PWR) incapability world-wide and has limited the useful life of SGs at some utilities. The vast majority of the degradation has been the result of SCC of the thin walled nickel alloy SG tubes and has been most prevalent in mill annealed (MA) Alloy 600. Fortunately, Ontario Power Generation (OPG) SG tubes are manufactured from alloys that have much better resistance to this form of localized corrosion than Alloy 600MA and as a consequence have not encountered SCC to date. Other forms of degradation nevertheless have been experienced; some units at Pickering - B in particular have had many Alloy 400 SG tubes removed from service due to severe underdeposit corrosion (UDC) and costly modifications have been made to Darlington SGs to prevent leaks as a result of SG tube fretting-wear at tube supports. Degradation other than UDC and fretting-wear which could pose a threat to the future reliable operation of OPG's nuclear fleet has also been observed. Important activities in effectively managing SG degradation include determining the mode of degradation and arriving at an understanding of the contributing factors. This is done by a combination of non-destructive examination (NDE) of SG tubing in-situ, SG tube removals for metallurgical examination and research and development. SG tube metallurgical examinations provide information that can be used in the timely development of a strategy dealing with the degradation in the short to intermediate timeframe. Determining the main causative factors at a mechanistic level helps to improve the predictive capability and increases the probability of dealing with the problem in the most cost-effective way. OPG has used this approach together with in-situ NDE inspections during planned outages of its nuclear reactors to minimize the possibility of unscheduled outages and provide the best possible fitness-for-service assessments. Many metallurgical

Probabilistic analysis of degradation incubation time of steam generator tubing materials

International Nuclear Information System (INIS)

Pandey, M.D.; Jyrkama, M.I.; Lu, Y.; Chi, L.

2012-01-01

The prediction of degradation free lifetime of steam generator (SG) tubing material is an important step in the life cycle management and decision for replacement of steam generators during the refurbishment of a nuclear station. Therefore, an extensive experimental research program has been undertaken by the Canadian Nuclear Industry to investigate the degradation of widely-used SG tubing alloys, namely, Alloy 600 TT, Alloy 690 TT, and Alloy 800. The corrosion related degradations of passive metals, such as pitting, crevice corrosion and stress corrosion cracking (SCC) etc. are assumed to start with the break down of the passive film at the tube-environment interface, which is characterized by the incubation time for passivity breakdown and then the degradation growth rate, and both are influenced by the chemical environment and coolant temperature. Since the incubation time and growth rate exhibit significant variability in the laboratory tests used to simulate these degradation processes, the use of probabilistic modeling is warranted. A pit is initiated with the breakdown of the passive film on the SG tubing surface. Upon exposure to aggressive environments, pitting corrosion may not initiate immediately, or may initiate and then re-passivate. The time required to initiate pitting corrosion is called the pitting incubation time, and that can be used to characterize the corrosion resistance of a material under specific test conditions. Pitting may be the precursor to other corrosion degradation mechanisms, such as environmentally-assisted cracking. This paper will provide an overview of the results of the first stage of experimental program in which samples of Alloy 600 TT, Alloy 690 TT, and Alloy 800 were tested under various temperatures and potentials and simulated crevice environments. The testing environment was chosen to represent layup, startup, and full operating conditions of the steam generators. Degradation incubation times for over 80 samples were

Detection and mitigating rod drive control system degradation in Westinghouse PWRs

International Nuclear Information System (INIS)

Gunther, W.; Sullivan, K.

1990-01-01

A study of the effects of aging on the Westinghouse Control Rod Drive (CRD) System was performed as part of the US NRC's Nuclear Plant aging Research (NPAR) Program. For the study, the CRD system boundary includes the power and logic cabinets associated with the manual control rod movement, and the control rod mechanism itself. The aging-related degradation of the interconnecting cables and connectors and the rod position indicating system also were considered. This paper presents the results of that study pertaining to the electrical and instrumentation portions of the CRD system including ways to detect and mitigate system degradation

Aging management of containment structures in nuclear power plants

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.R.; Graves, H.L. III; Norris, W.E.

1996-01-01

Research is being conducted by Oak Ridge National Laboratory under US nuclear regulatory commission (USNRC) sponsorship to address aging management of nuclear power plant containment and other safety-related structures. Documentation is being prepared to provide the USNRC with potential structural safety issues and acceptance criteria for use in continued service evaluations of nuclear power plants. Accomplishments include development of a structural materials information center containing data and information on the time variation of 144 material properties under the influence of pertinent environmental stressors or aging factors, evaluation of models for potential concrete containment degradation factors, development of a procedure to identify critical structures and degradation factors important to aging management, evaluations of non-destructive evaluation techniques, assessments of European and North American repair practices for concrete, review of parameters affecting corrosion of metals embedded in concrete, and development of methodologies for making current condition assessments and service life predictions of new or existing reinforced concrete structures in nuclear power plants. (orig.)

Epstein-Barr virus nuclear antigen 1 (EBNA1) induced cytotoxicity in epithelial cells is associated with EBNA1 degradation and processing

International Nuclear Information System (INIS)

Jones, Richard J.; Smith, Laura J.; Dawson, Christopher W.; Haigh, Tracy; Blake, Neil W.; Young, Lawrence S.

2003-01-01

Epstein-Barr virus nuclear antigen 1 (EBNA1) has a central role in the maintenance and segregation of the Epstein-Barr virus (EBV) episome and by virtue of a glycine-alanine repeat domain is prevented from being endogenously processed for recognition by HLA class I restricted cytotoxic T lymphocytes (CTLs). We found that EBNA1 expression resulted in growth inhibition and a G2/M arrest in human squamous epithelial cell lines (SCC12F, SVK) but not epithelial cell lines of glandular origin (Hela, Ad/AH). The cytotoxicity of EBNA1 was associated with EBNA1 degradation and both these effects were blocked in SCC12F cells expressing either the anti-apoptotic bcl-2 protein or the EBV homolog of bcl-2, BHRF1. The endogenous degradation of EBNA1 in SVK epithelial cells was associated with specific CTL recognition, an effect not evident in EBNA1-expressing Hela cells. Consistent with the inability of SVK cells to tolerate EBNA1 expression, studies with a recombinant EBV demonstrated that SVK cells are unable to maintain stable virus infection, whereas Hela cells are able to efficiently establish latent EBV infection. These data have important implications for both the cellular requirements necessary to sustain a stable EBV infection and for the possible role of CTL responses in controlling EBV infection of epithelial cells

Aging management of containment structures in nuclear power plants

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.R.

1994-01-01

Research is being conducted by Oak Ridge National Laboratory under U.S. Nuclear Regulatory Commission sponsorship to address aging management of nuclear power plant containment and other safety-related structures. Documentation is being prepared to provide the US-NRC with potential structural safety issues and acceptance criteria for use in continued service evaluations of nuclear power plants. Accomplishments include development of a Structural Materials Information Center containing data and information on the time variation of 144 material properties under the influence of pertinent environmental stressors or aging factors, evaluation of models for potential concrete containment degradation factors, development of a procedure to identify critical structures and degradation factors important to aging management, evaluations of nondestructive evaluation techniques, assessments of European and North American repair practices for concrete, review of parameters affecting corrosion of metals embedded in concrete, and development of methodologies for making current condition assessments and service life predictions of new or existing reinforced concrete structures in nuclear power plants. (author). 29 refs., 2 figs

Aging management of containment structures in nuclear power plants

International Nuclear Information System (INIS)

Naus, D.J.; Oland, C.B.; Ellingwood, B.R.; Graves, H.L. III; Norris, W.E.

1994-01-01

Research is being conducted by ORNL under US Nuclear Regulatory Commission (USNRC) sponsorship to address aging management of nuclear power plant containment and other safety-related structures. Documentation is being prepared to provide the USNRC with potential structural safety issues and acceptance criteria for use in continued service evaluations of nuclear power plants. Accomplishments include development of a Structural Materials Information Center containing data and information on the time variation of 144 material properties under the influence of pertinent environmental stressors or aging factors, evaluation of models for potential concrete containment degradation factors, development of a procedure to identify critical structures and degradation factors important to aging management, evaluations of nondestructive evaluation techniques. assessments of European and North American repair practices for concrete, review of parameters affecting corrosion of metals embedded in concrete, and development of methodologies for making current condition assessments and service life predictions of new or existing reinforced concrete structures in nuclear power plants

Prevention of bolting degradation or failure in pressure boundary and support applications

International Nuclear Information System (INIS)

Merrick, E.A.; Rivers, A.; Bickford, J.; Marston, T.U.

1986-01-01

A discussion is presented of bolting degradation or failure experience in pressure boundary and component support applications in US commercial nuclear plants and the industry program to prevent failures in the future. The focus turns to steps which plant owners can take today to guard against pressure boundary bolt failure or degradation for existing plants or units being constructed. 'Tools' or products which the plant owner can expect from current industry programs which will be available in the near future to aid in understanding and improving bolting practices are described. (author)

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

1988-04-01

This general review of the operation of the Finnish nuclear power plants concentrates on such events and discoveries related to nuclear and radiation safety as the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as noteworthy. The report also includes a summary of the radiation safety of the personnel and the environment, as well as tubulated data on the production and load factors of the plants. In the report period, no event essentially degraded plant safety nor posed a radiation hazard to the personnel or the environment

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

Heimburger, H.

1988-08-01

This general review of the operation of the Finnish nuclear power plants concentrates on such events and discoveries related to nuclear and radiation safety as the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as noteworthy. The report also includes a summary of the radiation safety of the personnel and the environment, as well as tabulated data on the production and load factors of the plants. In the report period, no event essentially degraded plant safety nor posed a radiation hazard to the personnel or the environment

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

Ottosson, C.

1989-05-01

This general review of the operation of the Finnish nuclear power plants concentrates on such events and discoveries related to nuclear and radiation safety as the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as noteworthy. The report also includes a summary of the radiation safety of the personnel and the environment, as well as tabulated data on the production and load factors of the plants. In the report period, no event essentially degraded plant safety nor posed a radiation hazard to the personnel or the environment

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

Haenninen, R.; Koponen, H.; Nevander, O.; Paltemaa, R.; Poellaenen, I.; Rannila, P.; Valtonen, K.; Vilkamo, O.

1988-02-01

This general review of the operation of the Finnish nuclear power plants concentrates on such events and discoveries related to nuclear and radiation safety as the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as noteworthy. The report also includes a summary of the radiation safety of the personnel and the environment, as well as tabulated data on the production and load factors of the plants. In the report period, no event essentially degraded plant safety nor posed a radiation hazard to the personnel or the environment

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

Haenninen, R.

1988-09-01

This general review of the operation of the Finnish nuclear power plants concentrates on such events and discoveries related to nuclear and radiation safety as the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as noteworthy. The report also includes a summary of the radiation safety of the personnel and the environment, as well as tabulated data on the production and load factors of the plants. In the report period, no event essentially degraded plant safety nor posed a radiation hzard to the personnel or the environment

Dissecting mechanisms of nuclear mRNA surveillance in THO/sub2 complex mutants

DEFF Research Database (Denmark)

Rougemaille, Mathieu; Gudipati, Rajani K; Olesen, Jens Raabjerg

2007-01-01

The nuclear exosome is involved in numerous RNA metabolic processes. Exosome degradation of rRNA, snoRNA, snRNA and tRNA in Saccharomyces cerevisiae is activated by TRAMP complexes, containing either the Trf4p or Trf5p poly(A) polymerase. These enzymes are presumed to facilitate exosome access...... is required for both retention and degradation of nuclear restricted mRNAs. We show here that Trf4p, in the context of TRAMP, is an mRNA surveillance factor. However, unlike Rrp6p, Trf4p only partakes in RNA degradation and not in transcript retention. Surprisingly, a polyadenylation-defective Trf4p protein...

Histone deacetylase inhibitor, Trichostatin A induces ubiquitin-dependent cyclin D1 degradation in MCF-7 breast cancer cells

Directory of Open Access Journals (Sweden)

Charles Coombes R

2006-02-01

Full Text Available Abstract Background Cyclin D1 is an important regulator of G1-S phase cell cycle transition and has been shown to be important for breast cancer development. GSK3β phosphorylates cyclin D1 on Thr-286, resulting in enhanced ubiquitylation, nuclear export and degradation of the cyclin in the cytoplasm. Recent findings suggest that the development of small-molecule cyclin D1 ablative agents is of clinical relevance. We have previously shown that the histone deacetylase inhibitor trichostatin A (TSA induces the rapid ubiquitin-dependent degradation of cyclin D1 in MCF-7 breast cancer cells prior to repression of cyclin D1 gene (CCND1 transcription. TSA treatment also resulted in accumulation of polyubiquitylated GFP-cyclin D1 species and reduced levels of the recombinant protein within the nucleus. Results Here we provide further evidence for TSA-induced ubiquitin-dependent degradation of cyclin D1 and demonstrate that GSK3β-mediated nuclear export facilitates this activity. Our observations suggest that TSA treatment results in enhanced cyclin D1 degradation via the GSK3β/CRM1-dependent nuclear export/26S proteasomal degradation pathway in MCF-7 cells. Conclusion We have demonstrated that rapid TSA-induced cyclin D1 degradation in MCF-7 cells requires GSK3β-mediated Thr-286 phosphorylation and the ubiquitin-dependent 26S proteasome pathway. Drug induced cyclin D1 repression contributes to the inhibition of breast cancer cell proliferation and can sensitize cells to CDK and Akt inhibitors. In addition, anti-cyclin D1 therapy may be highly specific for treating human breast cancer. The development of potent and effective cyclin D1 ablative agents is therefore of clinical relevance. Our findings suggest that HDAC inhibitors may have therapeutic potential as small-molecule cyclin D1 ablative agents.

U.S.-NPAR approach to managing aging in operating nuclear power plants

International Nuclear Information System (INIS)

Bosnak, R.; Vagins, M.; Vora, J.

1991-01-01

Aging degradation in operating nuclear power plants must be managed to prevent safety margins from eroding below the levels provided in plant design bases. The NPAR program and other aging-related programs conducted under the auspices of the US NRC Office of Nuclear Regulatory Research are developing needed technical bases and guidance for understanding and managing aging in operating nuclear power plants (NPP) of all ages. Results from these programs, together with relevant information developed by industry are implemented through various ongoing NRC and industry programs. The aging management process central to these efforts consists of three key element: 1) selection and prioritization of components, systems, and structures (CSS) in which aging must be managed, 2) understanding of the relevant aging mechanisms and rates of degradation processes in these CSS, and 3) managing degradation through effective inspection, surveillance, condition monitoring, trending, preventive and corrective maintenance, and mitigation. This paper provides a historical perspective on the aging related research programs sponsored by the Office of U.S. Nuclear Regulatory Research. Also, briefly described are the major element of the NPAR program and its status and results or accomplishments. In the process the authors emphasize the need for total industry commitment and participation in implementing programs for understanding and managing aging in operating nuclear power plants. 'Aging' is universal in nature. No industrial complex including NPP should be considered immune from its effects. For NPP aging is manageable its ti symptoms are recognized and predicted, if it is monitored and appropriate steps are taken for timely mitigation of age-related degradation. (author)

Microbial degradation of low-level radioactive waste. Final report

International Nuclear Information System (INIS)

Rogers, R.D.; Hamilton, M.A.; Veeh, R.H.; McConnell, J.W. Jr.

1996-06-01

The Nuclear Regulatory Commission stipulates in 10 CFR 61 that disposed low-level radioactive waste (LLW) be stabilized. To provide guidance to disposal vendors and nuclear station waste generators for implementing those requirements, the NRC developed the Technical Position on Waste Form, Revision 1. That document details a specified set of recommended testing procedures and criteria, including several tests for determining the biodegradation properties of waste forms. Information has been presented by a number of researchers, which indicated that those tests may be inappropriate for examining microbial degradation of cement-solidified LLW. Cement has been widely used to solidify LLW; however, the resulting waste forms are sometimes susceptible to failure due to the actions of waste constituents, stress, and environment. The purpose of this research program was to develop modified microbial degradation test procedures that would be more appropriate than the existing procedures for evaluation of the effects of microbiologically influenced chemical attack on cement-solidified LLW. The procedures that have been developed in this work are presented and discussed. Groups of microorganisms indigenous to LLW disposal sites were employed that can metabolically convert organic and inorganic substrates into organic and mineral acids. Such acids aggressively react with cement and can ultimately lead to structural failure. Results on the application of mechanisms inherent in microbially influenced degradation of cement-based material are the focus of this final report. Data-validated evidence of the potential for microbially influenced deterioration of cement-solidified LLW and subsequent release of radionuclides developed during this study are presented

Degradable polyphosphazene/poly(alpha-hydroxyester) blends: degradation studies.

Science.gov (United States)

Ambrosio, Archel M A; Allcock, Harry R; Katti, Dhirendra S; Laurencin, Cato T

2002-04-01

Biomaterials based on the polymers of lactic acid and glycolic acid and their copolymers are used or studied extensively as implantable devices for drug delivery, tissue engineering and other biomedical applications. Although these polymers have shown good biocompatibility, concerns have been raised regarding their acidic degradation products, which have important implications for long-term implantable systems. Therefore, we have designed a novel biodegradable polyphosphazene/poly(alpha-hydroxyester) blend whose degradation products are less acidic than those of the poly(alpha-hydroxyester) alone. In this study, the degradation characteristics of a blend of poly(lactide-co-glycolide) (50:50 PLAGA) and poly[(50% ethyl glycinato)(50% p-methylphenoxy) phosphazene] (PPHOS-EG50) were qualitatively and quantitatively determined with comparisons made to the parent polymers. Circular matrices (14mm diameter) of the PLAGA, PPHOS-EG50 and PLAGA-PPHOS-EG50 blend were degraded in non-buffered solutions (pH 7.4). The degraded polymers were characterized for percentage mass loss and molecular weight and the degradation medium was characterized for acid released in non-buffered solutions. The amounts of neutralizing base necessary to bring about neutral pH were measured for each polymer or polymer blend during degradation. The poly(phosphazene)/poly(lactide-co-glycolide) blend required significantly less neutralizing base in order to bring about neutral solution pH during the degradation period studied. The results indicated that the blend degraded at a rate intermediate to that of the parent polymers and that the degradation products of the polyphosphazene neutralized the acidic degradation products of PLAGA. Thus, results from these in vitro degradation studies suggest that the PLAGA-PPHOS-EG50 blend may provide a viable improvement to biomaterials based on acid-releasing organic polymers.

E1AF degradation by a ubiquitin-proteasome pathway

International Nuclear Information System (INIS)

Takahashi, Akiko; Higashino, Fumihiro; Aoyagi, Mariko; Yoshida, Koichi; Itoh, Miyuki; Kobayashi, Masanobu; Totsuka, Yasunori; Kohgo, Takao; Shindoh, Masanobu

2005-01-01

E1AF is a member of the ETS family of transcription factors. In mammary tumors, overexpression of E1AF is associated with tumorigenesis, but E1AF protein has hardly been detected and its degradation mechanism is not yet clear. Here we show that E1AF protein is stabilized by treatment with the 26S protease inhibitor MG132. We found that E1AF was modified by ubiquitin through the C-terminal region and ubiquitinated E1AF aggregated in nuclear dots, and that the inhibition of proteasome-activated transcription from E1AF target promoters. These results suggest that E1AF is degraded via the ubiquitin-proteasome pathway, which has some effect on E1AF function

In-operation inspection technology development-4 ''development of degradation prediction technology for motor-operated valves''

International Nuclear Information System (INIS)

Kikuo, Takeshima; Yuichi, Higashikawa; Masahiro, Koike; Kenji, Matsumoto; Eiji, O'shima

2001-01-01

A method for degradation predicting technology has been proposed for motor operated valves in nuclear power plants which is based on the concept of condition monitoring for maintenance. This method (degradation prediction technology) eliminates the unnecessary overhaul of valves and realizes high reliability and economy. The degradation mechanism was clarified by long time heating experiments of gasket and gland packing and the wear test for them and stem nut to research valve parts degradation by stress (pressure, temperature, etc) during plant operation. Effective electric power measurements for motor operated valves were confirmed to be useful discovering valve part failures. The motor operated valve degradation prediction system was developed on the basis of the experiment results and mechanism. The system is able to predict the degradation of valve parts (gasket/gland packing, stem, stem nut, etc) utilizing plant data (pressure, temperature, etc) and effective power of the motor. The life of valve parts can be estimated from the experimental results. (authors)

Control of nuclear β-dystroglycan content is crucial for the maintenance of nuclear envelope integrity and function.

Science.gov (United States)

Vélez-Aguilera, Griselda; de Dios Gómez-López, Juan; Jiménez-Gutiérrez, Guadalupe E; Vásquez-Limeta, Alejandra; Laredo-Cisneros, Marco S; Gómez, Pablo; Winder, Steve J; Cisneros, Bulmaro

2018-02-01

β-Dystroglycan (β-DG) is a plasma membrane protein that has ability to target to the nuclear envelope (NE) to maintain nuclear architecture. Nevertheless, mechanisms controlling β-DG nuclear localization and the physiological consequences of a failure of trafficking are largely unknown. We show that β-DG has a nuclear export pathway in myoblasts that depends on the recognition of a nuclear export signal located in its transmembrane domain, by CRM1. Remarkably, NES mutations forced β-DG nuclear accumulation resulting in mislocalization and decreased levels of emerin and lamin B1 and disruption of various nuclear processes in which emerin (centrosome-nucleus linkage and β-catenin transcriptional activity) and lamin B1 (cell cycle progression and nucleoli structure) are critically involved. In addition to nuclear export, the lifespan of nuclear β-DG is restricted by its nuclear proteasomal degradation. Collectively our data show that control of nuclear β-DG content by the combination of CRM1 nuclear export and nuclear proteasome pathways is physiologically relevant to preserve proper NE structure and activity. Copyright © 2017 Elsevier B.V. All rights reserved.

Classification of Feedwater Heater Performance Degradation Using Residual Sign Matrix

International Nuclear Information System (INIS)

Ha, Gayeon; Heo, Gyunyoung; Song, Seok Yoon

2016-01-01

Since a performance of Feedwater Heater (FWH) is directly related to the thermodynamic efficiency of Nuclear Power Plants (NPPs), performance degradation of FWH results in loss of thermal power and ultimately business benefit. Nevertheless, it is difficult to diagnose its degradation of performance during normal operation due to its minor changes in process parameters, for instance, pressure, temperature, and flowrate. In this paper, six degradation modes have been analyzed and the performance indices for FWH such as Terminal Temperature Difference (TTD) and Drain Cooling Approach (DCA) have been used to diagnose degradation modes. PEPSE (Performance Evaluation of Power System Efficiencies) simulation, which is a plant simulation software simulating plant static characteristic and building energy balance model, has been used to generate the data of performance indices of FWH and actual measurements of FWH from NPPs was used to validate the classification model. In this paper, six degradation modes have been analyzed and the performance indices for FWH have been used to diagnose what degradation mode occurs. The RSM was proposed as a trend identifier of variables. Using RSM, it is possible to obtain appropriate information of the variables in noise environment since noise can be compressed while the original information is being converted to a trend. The SVC has been performed to classify the degradation mode of FWH, and then actual measurements of FWH from NPPs was used to validate the classification model. Performance indices under various leakage conditions show different patterns. In further study, tube leakage simulations for the various cases will be needed

Classification of Feedwater Heater Performance Degradation Using Residual Sign Matrix

Energy Technology Data Exchange (ETDEWEB)

Ha, Gayeon; Heo, Gyunyoung [Kyung Hee University, Seoul (Korea, Republic of); Song, Seok Yoon [KHNP CRI, Daejeon (Korea, Republic of)

2016-10-15

Since a performance of Feedwater Heater (FWH) is directly related to the thermodynamic efficiency of Nuclear Power Plants (NPPs), performance degradation of FWH results in loss of thermal power and ultimately business benefit. Nevertheless, it is difficult to diagnose its degradation of performance during normal operation due to its minor changes in process parameters, for instance, pressure, temperature, and flowrate. In this paper, six degradation modes have been analyzed and the performance indices for FWH such as Terminal Temperature Difference (TTD) and Drain Cooling Approach (DCA) have been used to diagnose degradation modes. PEPSE (Performance Evaluation of Power System Efficiencies) simulation, which is a plant simulation software simulating plant static characteristic and building energy balance model, has been used to generate the data of performance indices of FWH and actual measurements of FWH from NPPs was used to validate the classification model. In this paper, six degradation modes have been analyzed and the performance indices for FWH have been used to diagnose what degradation mode occurs. The RSM was proposed as a trend identifier of variables. Using RSM, it is possible to obtain appropriate information of the variables in noise environment since noise can be compressed while the original information is being converted to a trend. The SVC has been performed to classify the degradation mode of FWH, and then actual measurements of FWH from NPPs was used to validate the classification model. Performance indices under various leakage conditions show different patterns. In further study, tube leakage simulations for the various cases will be needed.

Carbon-13 Labeling Used to Probe Cure and Degradation Reactions of High- Temperature Polymers

Science.gov (United States)

Meador, Mary Ann B.; Johnston, J. Christopher

1998-01-01

High-temperature, crosslinked polyimides are typically insoluble, intractible materials. Consequently, in these systems it has been difficult to follow high-temperature curing or long-term degradation reactions on a molecular level. Selective labeling of the polymers with carbon-13, coupled with solid nuclear magnetic resonance spectrometry (NMR), enables these reactions to be followed. We successfully employed this technique to provide insight into both curing and degradation reactions of PMR-15, a polymer matrix resin used extensively in aircraft engine applications.

Reliability residual-life prediction method for thermal aging based on performance degradation

International Nuclear Information System (INIS)

Ren Shuhong; Xue Fei; Yu Weiwei; Ti Wenxin; Liu Xiaotian

2013-01-01

The paper makes the study of the nuclear power plant main pipeline. The residual-life of the main pipeline that failed due to thermal aging has been studied by the use of performance degradation theory and Bayesian updating methods. Firstly, the thermal aging impact property degradation process of the main pipeline austenitic stainless steel has been analyzed by the accelerated thermal aging test data. Then, the thermal aging residual-life prediction model based on the impact property degradation data is built by Bayesian updating methods. Finally, these models are applied in practical situations. It is shown that the proposed methods are feasible and the prediction accuracy meets the needs of the project. Also, it provides a foundation for the scientific management of aging management of the main pipeline. (authors)

Diagnosis of Feedwater Heater Performance Degradation using Fuzzy Approach

International Nuclear Information System (INIS)

Kim, Hyeonmin; Kang, Yeon Kwan; Heo, Gyunyoung; Song, Seok Yoon

2014-01-01

It is inevitable to avoid degradation of component, which operates continuously for long time in harsh environment. Since this degradation causes economical loss and human loss, it is important to monitor and diagnose the degradation of component. The diagnosis requires a well-systematic method for timely decision. Before this article, the methods using regression model and diagnosis table have been proposed to perform the diagnosis study for thermal efficiency in Nuclear Power Plants (NPPs). Since the regression model was numerically less-stable under changes of operating variables, it was difficult to provide good results in operating plants. Contrary to this, the diagnosis table was hard to use due to ambiguous points and to detect how it affects degradation. In order to cover the issues of previous researches, we proposed fuzzy approaches and applied it to diagnose Feedwater Heater (FWH) degradation to check the feasibility. The degradation of FWHs is not easy to be observed, while trouble such as tube leakage may bring simultaneous damage to the tube bundle. This study explains the steps of diagnosing typical failure modes of FWHs. In order to cover the technical issues of previous researches, we adopted fuzzy logic to suggest a diagnosis algorithm for the degradation of FHWs and performed feasibility study. In this paper, total 7 modes of FWH degradation modes are considered, which are High Drain Level, Low Shell Pressure, Tube Pressure Increase, Tube Fouling, Pass Partition Plate Leakage, Tube Leakage, Abnormal venting. From the literature survey and simulation, diagnosis table for FWH is made. We apply fuzzy logic based on diagnosis table. Authors verify fuzzy diagnosis for FWH degradation synthesized the random input sets from made diagnosis table. Comparing previous researches, suggested method more-stable under changes of operating variables, than regression model. On the contrary, the problem which ambiguous points and detect how it affects degradation

Diagnosis of Feedwater Heater Performance Degradation using Fuzzy Approach

Energy Technology Data Exchange (ETDEWEB)

Kim, Hyeonmin; Kang, Yeon Kwan; Heo, Gyunyoung [Kyung Hee Univ., Yongin (Korea, Republic of); Song, Seok Yoon [Korea Hydro and Nuclear Power, Daejeon (Korea, Republic of)

2014-05-15

It is inevitable to avoid degradation of component, which operates continuously for long time in harsh environment. Since this degradation causes economical loss and human loss, it is important to monitor and diagnose the degradation of component. The diagnosis requires a well-systematic method for timely decision. Before this article, the methods using regression model and diagnosis table have been proposed to perform the diagnosis study for thermal efficiency in Nuclear Power Plants (NPPs). Since the regression model was numerically less-stable under changes of operating variables, it was difficult to provide good results in operating plants. Contrary to this, the diagnosis table was hard to use due to ambiguous points and to detect how it affects degradation. In order to cover the issues of previous researches, we proposed fuzzy approaches and applied it to diagnose Feedwater Heater (FWH) degradation to check the feasibility. The degradation of FWHs is not easy to be observed, while trouble such as tube leakage may bring simultaneous damage to the tube bundle. This study explains the steps of diagnosing typical failure modes of FWHs. In order to cover the technical issues of previous researches, we adopted fuzzy logic to suggest a diagnosis algorithm for the degradation of FHWs and performed feasibility study. In this paper, total 7 modes of FWH degradation modes are considered, which are High Drain Level, Low Shell Pressure, Tube Pressure Increase, Tube Fouling, Pass Partition Plate Leakage, Tube Leakage, Abnormal venting. From the literature survey and simulation, diagnosis table for FWH is made. We apply fuzzy logic based on diagnosis table. Authors verify fuzzy diagnosis for FWH degradation synthesized the random input sets from made diagnosis table. Comparing previous researches, suggested method more-stable under changes of operating variables, than regression model. On the contrary, the problem which ambiguous points and detect how it affects degradation

Technical and management challenges associated with structural materials degradation in nuclear reactors in the future

International Nuclear Information System (INIS)

Ford, F.P.

2007-01-01

There are active plans worldwide to increase nuclear power production by significant amounts. In the near term (i.e. by 2020) this will be accomplished by, (a) increasing the power output of the existing reactors and extending their life, and by, (b) constructing new reactors that are very similar to the current water-cooled designs. Beyond 2025-2030, it is possible that new reactors (i.e. the 'GEN IV' designs) will be very different from those currently in service. A full discussion of the technical and management concerns associated with materials degradation that might arise over the next 40 years would need to address a wide range of topics. Quite apart from discussing the structural integrity issues for the materials of construction and the fuel cladding, the debate would also need to cover, for example, fuel resources and the associated issues of fuel cycle management and waste disposal, manufacturing capacity, inspection capabilities, human reliability, etc., since these all impact to one degree or another on the choice of material and the reactor operating conditions. For brevity, the scope of this article is confined to the integrity of the materials of construction for passive components in the current water-cooled reactors and the evolutionary designs (which will dominate the near term new constructions), and the very different GEN IV reactor designs. In all cases the operating environments will be more aggressive than currently encountered. For instance, the concerns for flow accelerated corrosion and flow-induced vibration will be increased under extended power uprate conditions for the current water-cooled reactors. Of greater concern, the design life will be at least 60 years for all of the new reactors and for those current reactors operating with extended licenses. This automatically presents challenges with regard to managing both irradiation damage in metallic and non-metallic materials of construction, and environmentally assisted cracking. This

Minimize corrosion degradation of steam generator tube materials

International Nuclear Information System (INIS)

Lu, Y.

2006-01-01

As part of a coordinated program, AECL is developing a set of tools to aid with the prediction and management of steam generator performance. Although stress corrosion cracking (of Alloy 800) has not been detected in any operating steam generator, for life management it is necessary to develop mechanistic models to predict the conditions under which stress corrosion cracking is plausible. Experimental data suggest that all steam generator tube materials are susceptible to corrosion degradation under some specific off-specification conditions. The tolerance to the chemistry upset for each steam generator tube alloy is different. Electrochemical corrosion behaviors of major steam generator tube alloys were studied under the plausible aggressive crevice chemistry conditions. The potential hazardous conditions leading to steam generator tube degradation and the conditions, which can minimize steam generator tube degradation have been determined. Recommended electrochemical corrosion potential/pH zones were defined for all major steam generator tube materials, including Alloys 600, 800, 690 and 400, under CANDU steam generator operating and startup conditions. Stress corrosion cracking tests and accelerated corrosion tests were carried out to verify and revise the recommended electrochemical corrosion potential/pH zones. Based on this information, utilities can prevent steam generator material degradation surprises by appropriate steam generator water chemistry management and increase the reliability of nuclear power generating stations. (author)

Study on Developing Degradation Model for Nuclear Power Plants With Ageing Elements Affected on Operation Parameter

International Nuclear Information System (INIS)

Choi, Yong Won; Lim, Sung Won; Lee, Un Chul; Kim, Man Woong; Kim, Kab; Ryu, Yong Ho

2009-01-01

As a part of development the evaluation system of safety margin effects for degradation of CANDU reactors, it is required that the degradation model represents the distribution of each ageing factor's value during operating year. Unfortunately, it is not easy to make an explicit relation between the RELAP-CANDU parameters and ageing mechanism because of insufficient data and lack of applicable models. So, operating parameter related with ageing is used for range determination of ageing factor. Then, relation between operating parameter and ageing elements is analyzed and ageing constant values for degradation model are determined. Also the other ageing factor is derived for more accurate ageing analysis

Evaluation of diagnostic technique for degradation of low-voltage electric cables with silicone rubber insulator

International Nuclear Information System (INIS)

Mikami, Masao

2005-01-01

As a part of countermeasures against ageing problems of nuclear power plants, it is requested to establish non-destructive diagnostic technique for their degradation of low voltage electric cables and assessment standard of their life. Having aimed at investigating the degradation of low-voltage electric cable with silicone rubber insulator, change of its surface hardness at elevated temperature were measured by indenter modules. Moreover, we also measured the elongation at break, which is regarded as general degradation index of electric cables, and the surface hardness with a micro hardness meter. Consequently, it is seen that the indenter modulus measurement is (1) capable to obtain general feature of the thermal degradation of silicone rubber insulator, (2) applicable to diagnose the degree of degradation of the electric cable by converting the result to elongation at break, (3) well correlated with the hardness measurement of the electric cable with the micro hardness meter. (author)

Designing optimal degradation tests via multi-objective genetic algorithms

International Nuclear Information System (INIS)

Marseguerra, Marzio; Zio, Enrico; Cipollone, Maurizio

2003-01-01

The experimental determination of the failure time probability distribution of highly reliable components, such as those used in nuclear and aerospace applications, is intrinsically difficult due to the lack, or scarce significance, of failure data which can be collected during the relatively short test periods. A possibility to overcome this difficulty is to resort to the so-called degradation tests, in which measurements of components' degradation are used to infer the failure time distribution. To design such tests, parameters like the number of tests to be run, their frequency and duration, must be set so as to obtain an accurate estimate of the distribution statistics, under the existing limitations of budget. The optimisation problem which results is a non-linear one. In this work, we propose a method, based on multi-objective genetic algorithms for determining the values of the test parameters which optimise both the accuracy in the estimate of the failure time distribution percentiles and the testing costs. The method has been validated on a degradation model of literature

Significance of Alkali-Silica reaction in nuclear safety-related concrete structures

International Nuclear Information System (INIS)

Le Pape, Y.; Field, K.G.; Mattus, C.H.; Naus, D.J.; Busby, J.T.; Saouma, V.; Ma, Z.J.; Cabage, J.V.; Guimaraes, M.

2015-01-01

Nuclear Power Plant license renewal up to 60 years and possible life extension beyond has established a renewed focus on long-term aging of nuclear generating stations materials, and particularly, on concrete. Large irreplaceable sections of most nuclear generating stations include concrete components. The Expanded Materials Degradation Analysis, jointly performed by the Department of Energy, the U.S. Nuclear Regulatory Commission, the Academia and the Power Generation Industry, identified the need to develop a consistent knowledge base of alkali-silica reaction (ASR) within concrete as an urgent priority (Graves et al., 2014). ASR results in an expansion of Concrete produced by the reaction between alkali (generally from cement), reactive aggregate (like amorphous silica) and water absorption. ASR causes expansion, cracking and loss of mechanical properties. Considering that US commercial reactors in operation enter the age when ASR distress can be potentially observed and that numerous non-nuclear infrastructures (transportation, energy production) in a majority of the States have already experienced ASR-related concrete degradation, the susceptibility and significance of ASR for nuclear concrete structures must be addressed. This paper outlines an on-going research program including the investigation of the possibility of ASR in nuclear power plants, and the assessment of the residual shear bearing capacity of ASR-subjected nuclear structures. (authors)

Microbial-influenced cement degradation: Literature review

International Nuclear Information System (INIS)

Rogers, R.D.; Hamilton, M.A.; McConnell, J.W. Jr.

1993-03-01

The Nuclear Regulatory Commission stipulates that disposed low-level radioactive waste (LLW) be stabilized. Because of apparent ease of use and normal structural integrity, cement has been widely used as a binder to solidify LLW. However, the resulting waste forms are sometimes susceptible to failure due to the actions of waste constituents, stress, and environment. This report reviews literature which addresses the effect of microbiologically influenced chemical attack on cement-solidified LLW. Groups of microorganisms are identified, which are capable of metabolically converting organic and inorganic substrates into organic and mineral acids. Such acids aggressively react with concrete and can ultimately lead to structural failure. Mechanisms inherent in microbial-influenced degradation of cement-based material are the focus of this report. This report provides sufficient evidence of the potential for microbial-influenced deterioration of cement-solidified LLW to justify the enumeration of the conditions necessary to support the microbiological growth and population expansion, as well as the development of appropriate tests necessary to determine the resistance of cement-solidified LLW to microbiological-induced degradation that could impact the stability of the waste form

Multiscale Concrete Modeling of Aging Degradation

Energy Technology Data Exchange (ETDEWEB)

Hammi, Yousseff [Mississippi State Univ., Mississippi State, MS (United States); Gullett, Philipp [Mississippi State Univ., Mississippi State, MS (United States); Horstemeyer, Mark F. [Mississippi State Univ., Mississippi State, MS (United States)

2015-07-31

In this work a numerical finite element framework is implemented to enable the integration of coupled multiscale and multiphysics transport processes. A User Element subroutine (UEL) in Abaqus is used to simultaneously solve stress equilibrium, heat conduction, and multiple diffusion equations for 2D and 3D linear and quadratic elements. Transport processes in concrete structures and their degradation mechanisms are presented along with the discretization of the governing equations. The multiphysics modeling framework is theoretically extended to the linear elastic fracture mechanics (LEFM) by introducing the eXtended Finite Element Method (XFEM) and based on the XFEM user element implementation of Giner et al. [2009]. A damage model that takes into account the damage contribution from the different degradation mechanisms is theoretically developed. The total contribution of damage is forwarded to a Multi-Stage Fatigue (MSF) model to enable the assessment of the fatigue life and the deterioration of reinforced concrete structures in a nuclear power plant. Finally, two examples are presented to illustrate the developed multiphysics user element implementation and the XFEM implementation of Giner et al. [2009].

Assessment of inservice conditions of safety-related nuclear plant structures

International Nuclear Information System (INIS)

Ashar, H.; Bagchi, G.

1995-06-01

The report is a compilation from a number of sources of information related to the condition Of structures and civil engineering features at operating nuclear power plants in the United States. The most significant information came from the hands-on inspection of the six old plants (licensed prior to 1977) performed by the staff of the Civil Engineering and Geosciences Branch (ECGB) in the Division of Engineering of the Office of Nuclear Reactor Regulation. For the containment structures, most of the information related to the degraded conditions came from the licensees as part of the Licensing Event Report System (10 CFR 50.73), or as part of the requirement under limiting condition of operation of the plant-specific Technical Specifications. Most of the information related to the degradation of other Structures and civil engineering features was extracted from the industry survey, the reported incidents, and the plant visits. The report discusses the condition of the structures and civil engineering features at operating nuclear power plants and provides information that would help detect, alleviate, and correct the degraded conditions of the structures and civil engineering features

NPAR approach to controlling aging in nuclear power plants

International Nuclear Information System (INIS)

Christensen, J.A.

1990-01-01

Aging degradation in nuclear power plants must be controlled to prevent safety margins from declining below limits provided in plant design bases. The NPAR Program and other aging-related programs conducted under the auspices of the Nuclear Regulatory Commission (NRC) Office of Research are developing needed technical guidance for control of aging. Results from these programs, together with relevant information developed by industry and elsewhere, are implemented through various ongoing NRC and industry programs and initiatives as well as by means of conventional regulatory instruments. The aging control process central to these efforts consists of three key elements: (1) selection of components, systems, and structures (CSS) in which aging must be controlled, (2) understanding of the mechanisms and rates of degradation in these CSS, and (3) managing degradation through effective surveillance and maintenance. These elements are addressed in Good Practices Guidance that integrates information developed under NPAR and other studies of aging into a systems-oriented format that tracks directly with the safety analysis reports

Challenges in Modeling the Degradation of Ceramic Waste Forms

Energy Technology Data Exchange (ETDEWEB)

Devanathan, Ramaswami; Gao, Fei; Sun, Xin

2011-09-01

We identify the state of the art, gaps in current understanding, and key research needs in the area of modeling the long-term degradation of ceramic waste forms for nuclear waste disposition. The directed purpose of this report is to define a roadmap for Waste IPSC needs to extend capabilities of waste degradation to ceramic waste forms, which overlaps with the needs of the subconsinuum scale of FMM interests. The key knowledge gaps are in the areas of (i) methodology for developing reliable interatomic potentials to model the complex atomic-level interactions in waste forms; (ii) characterization of water interactions at ceramic surfaces and interfaces; and (iii) extension of atomic-level insights to the long time and distance scales relevant to the problem of actinide and fission product immobilization.

Challenges in Modeling the Degradation of Ceramic Waste Forms

International Nuclear Information System (INIS)

Devanathan, Ramaswami; Gao, Fei; Sun, Xin

2011-01-01

We identify the state of the art, gaps in current understanding, and key research needs in the area of modeling the long-term degradation of ceramic waste forms for nuclear waste disposition. The directed purpose of this report is to define a roadmap for Waste IPSC needs to extend capabilities of waste degradation to ceramic waste forms, which overlaps with the needs of the subconsinuum scale of FMM interests. The key knowledge gaps are in the areas of (i) methodology for developing reliable interatomic potentials to model the complex atomic-level interactions in waste forms; (ii) characterization of water interactions at ceramic surfaces and interfaces; and (iii) extension of atomic-level insights to the long time and distance scales relevant to the problem of actinide and fission product immobilization.

Degradation in steam of 60 cm-long B{sub 4}C control rods

Energy Technology Data Exchange (ETDEWEB)

Dominguez, C., E-mail: christina.dominguez@irsn.fr; Drouan, D.

2014-08-01

In the framework of nuclear reactor core meltdown accident studies, the degradation of boron carbide control rod segments exposed to argon/steam atmospheres was investigated up to about 2000 °C in IRSN laboratories. The sequence of the phenomena involved in the degradation has been found to take place as expected. Nevertheless, the ZrO{sub 2} oxide layer formed on the outer surface of the guide tube was very protective, significantly delaying and limiting the guide tube failure and therefore the boron carbide pellet oxidation. Contrary to what was expected, the presence of the control rod decreases the hydrogen release instead of increasing it by additional oxidation of boron compounds. Boron contents up to 20 wt.% were measured in metallic mixtures formed during degradation. It was observed that these metallic melts are able to attack the surrounding fuel rods, which could have consequences on fuel degradation and fission product release kinetics during severe accidents.

Land-based salmon aquacultures change the quality and bacterial degradation of riverine dissolved organic matter

DEFF Research Database (Denmark)

Kamjunke, Norbert; Nimptsch, Jorge; Harir, Mourad

2017-01-01

characterization of aquaculture DOM quality and its bacterial degradation using four salmon aquacultures in Chile. Fluorescence measurements, ultrahigh-resolution mass spectrometry, and nuclear magnetic resonance spectroscopy of the DOM revealed specific and extensive molecular alterations caused by aquacultures...

Online Sensor Calibration Assessment in Nuclear Power Systems

International Nuclear Information System (INIS)

Coble, Jamie B.; Ramuhalli, Pradeep; Meyer, Ryan M.; Hashemian, Hash

2013-01-01

Safe, efficient, and economic operation of nuclear systems (nuclear power plants, fuel fabrication and storage, used fuel processing, etc.) relies on transmission of accurate and reliable measurements. During operation, sensors degrade due to age, environmental exposure, and maintenance interventions. Sensor degradation can affect the measured and transmitted signals, including sensor failure, signal drift, sensor response time, etc. Currently, periodic sensor recalibration is performed to avoid these problems. Sensor recalibration activities include both calibration assessment and adjustment (if necessary). In nuclear power plants, periodic recalibration of safety-related sensors is required by the plant technical specifications. Recalibration typically occurs during refueling outages (about every 18 to 24 months). Non-safety-related sensors also undergo recalibration, though not as frequently. However, this approach to maintaining sensor calibration and performance is time-consuming and expensive, leading to unnecessary maintenance, increased radiation exposure to maintenance personnel, and potential damage to sensors. Online monitoring (OLM) of sensor performance is a non-invasive approach to assess instrument calibration. OLM can mitigate many of the limitations of the current periodic recalibration practice by providing more frequent assessment of calibration and identifying those sensors that are operating outside of calibration tolerance limits without removing sensors or interrupting operation. This can support extended operating intervals for unfaulted sensors and target recalibration efforts to only degraded sensors

The Component Operational Experience Degradation and Ageing Program (CODAP). Review and lessons learned (2011-2014)

International Nuclear Information System (INIS)

Dragea, Tudor; Riznic, Jovica R.

2015-01-01

The structural integrity of piping systems is crucial to continuous and safe operation of nuclear power plants. Across all designs, the pressure boundary and its related piping and components, form one of the many levels of defense in the continuous and safe operation of a nuclear power plant. It is therefore necessary to identify, understand, evaluate and catalogue all of the various degradation mechanisms and failures that affect various piping systems and components across all nuclear power plants (NPP's). This need was first recognized in 1994 by the Swedish Nuclear Power Inspectorate (SKI) which launched a five-year Research and Development (R and D) project to explore the viability of creating an international pipe failure database (SKI-PIPE) (Riznic, 2007). The project was considered to be very successful and in 2002, the Organization for Economic Co-operation and Development (OECD) Pipe Failure Data Exchange (OPDE) was created. OPDE was operated under the umbrella of the OECD Nuclear Energy Agency (NEA) and was created in order to produce an international database on the piping service experience applicable to commercial nuclear power plants. After the successful completion of OPDE, the OECD, as well as other international members, agreed to participate in OPDE's successor: the Component Operational Experience Degradation and Ageing Program (CODAP). The objective of CODAP is to collect information on all possible events related to the failure and degradation of passive metallic components in NPP's. With CODAP winding down to the completion of its first phase in December 2014, this report will focus on the conclusions and the lessons learned throughout the many years of CODAP's implementation. There are currently 14 countries participating in CODAP, many of whom are industry leaders (France, Canada, U.S.A., Germany, Japan, Korea etc.). This cooperation on an international scale provides a library of OPerational EXperience (OPEX) for all participating NPP

Palmitoylation regulates 17β-estradiol-induced estrogen receptor-α degradation and transcriptional activity.

Science.gov (United States)

La Rosa, Piergiorgio; Pesiri, Valeria; Leclercq, Guy; Marino, Maria; Acconcia, Filippo

2012-05-01

The estrogen receptor-α (ERα) is a transcription factor that regulates gene expression through the binding to its cognate hormone 17β-estradiol (E2). ERα transcriptional activity is regulated by E2-evoked 26S proteasome-mediated ERα degradation and ERα serine (S) residue 118 phosphorylation. Furthermore, ERα mediates fast cell responses to E2 through the activation of signaling cascades such as the MAPK/ERK and phosphoinositide-3-kinase/v-akt murine thymoma viral oncogene homolog 1 pathways. These E2 rapid effects require a population of the ERα located at the cell plasma membrane through palmitoylation, a dynamic enzymatic modification mediated by palmitoyl-acyl-transferases. However, whether membrane-initiated and transcriptional ERα activities integrate in a unique picture or represent parallel pathways still remains to be firmly clarified. Hence, we evaluated here the impact of ERα palmitoylation on E2-induced ERα degradation and S118 phosphorylation. The lack of palmitoylation renders ERα more susceptible to E2-dependent degradation, blocks ERα S118 phosphorylation and prevents E2-induced ERα estrogen-responsive element-containing promoter occupancy. Consequently, ERα transcriptional activity is prevented and the receptor addressed to the nuclear matrix subnuclear compartment. These data uncover a circuitry in which receptor palmitoylation links E2-dependent ERα degradation, S118 phosphorylation, and transcriptional activity in a unique molecular mechanism. We propose that rapid E2-dependent signaling could be considered as a prerequisite for ERα transcriptional activity and suggest an integrated model of ERα intracellular signaling where E2-dependent early extranuclear effects control late receptor-dependent nuclear actions.

Conceptual model for concrete long time degradation in a deep nuclear waste repository

International Nuclear Information System (INIS)

Lagerblad, B.; Traegaardh, J.

1996-04-01

Cement-based materials are fundamentally unstable in a long time perspective. With time the concrete will change properties both as a consequence of recrystallization and chemical interaction with the environment. One of the main difficulties with a conceptual model for concrete degradation is the change in the geochemical environment with time. During the first period the concrete will alter as a result of contact with atmospheric gases, especially CO 2 which will carbonate the surface. Later the degradation will mainly be governed by the composition of the groundwater with which it will try to equilibrate. Considering the chemical conditions at repository depths (500 m), it is possible that the groundwater will change composition from normal to saline. This may in fact be an advantage because the solubility of cement paste components decreases. However, the concrete will influence the groundwater composition and create an aureole with increased pH around it. Most of the components in both the fresh and saline water will not be harmful to concrete. One of the problems may be the chlorine anions, as this anion may substitute for sulfate in some of the cement phases. This will not degrade the concrete but the sulfates in the cement may be released to the groundwater. The end product of the concrete, after leaching and after the pH buffer capacity has been lost, will be a mix of metastable calcium silicate hydrates, zeolite and clay minerals. 72 refs

Fragility analysis methodology for degraded structures and passive components in nuclear power plantsIllustrated using a condensate storage tank

International Nuclear Information System (INIS)

Nie, Jinsuo; Braverman, Joseph; Hofmayer, Charles; Choun, Young Sun; Kim, Min Kyu; Choi, In Kil

2010-06-01

This report describes the seismic fragility capacity for a condensate storage tank with various degradation scenarios. The conservative deterministic failure margin method has been utilized for the undegraded case and has been modified to accommodate the degraded cases. A total of five seismic fragility analysis cases have been described: (1) undegraded case, (2) degraded stainless tank shell, (3) degraded anchor bolts, (4) anchorage concrete cracking, and (5) a perfect correlation of the three degradation scenarios. Insights from these fragility analyses are also presented. An overview of the methods for seismic fragility analysis and generic approaches to incorporate time-dependent degradation models into a fragility analysis is presented. Fundamental concepts of seismic fragility analysis are summarized to facilitate discussions in later sections. The seismic fragility analysis of the undegraded CST, which is assumed to have all of its components in design condition, is described. The subject CST was located in an operating Korean NPP. The baseline fragility capacity of the CST is calculated and the basic procedure of seismic fragility analysis is established. This report presents the results and insights of the seismic fragility analysis of the CST under various postulated degradation scenarios

Low cycle fatigue characteristics of duplex stainless steel with degradation under pure torsional load

International Nuclear Information System (INIS)

Kwon, Jae Do; Park, Joong Cheul

2002-01-01

Monotonic torsional and pure torsional low cycle fatigue (LCF) test with artificial degradation were performed on duplex stainless steel (CF8M). CF8M is used in pipes and valves in nuclear reactor coolant system. It was aged at 430 degree C for 3600hrs. Through the monotonic and LCF test, it is found that mechanical properties (i.e., yield strength, strain hardening exponent, strength coefficient etc.) increase and fatigue life (N f ) decreases with degradation of material. The relationship between shear strain amplitude (γ α ) and N f was proposed

Study on FPGA-Based Emulator for the Diagnosis of Gradual Degradation in Reciprocating Pump

Energy Technology Data Exchange (ETDEWEB)

Lim, Sang Sun; Kim, Wooshik [Sejong Univ., Seoul (Korea, Republic of); Kim, Tae Yun; Chai, Jang Bom [Ajou Univ., Suwon (Korea, Republic of)

2017-01-15

The purpose of this study is to develop a method for diagnosing the degree of gradual degradation of a reciprocating pump caused by continuous use as a water supply pump in a nuclear power plant. Normally, the progress of such degradation is too slow to be noticed. Hence, it is difficult to determine the degree of degradation using the existing diagnostic methods. In this paper, we propose a new method by which the normal state and the degraded state of the pump can be differentiated, so that the degree of degradation can be identified. First, an emulator was developed using FPGA by providing the parameters of the pump under normal state, so that the emulator generates the information of the pump in the healthy state. Then, by comparing this information with the parameters received from various output sensors of the emulator during the current state, it is possible to identify and measure the degree of gradual degradation. This paper presents some of the results obtained during the development process, and results that show how the emulator operates, by comparing the data collected from an actual pump.

Aging management and life assessment of buried commodities in nuclear power plants

International Nuclear Information System (INIS)

Park, J. H.; Jung, I. S.; Jo, H. S.; Kim, M. G.; Kim, S. T.; Lee, S. S.

2000-01-01

General field survey, inspection and life assessment were performed to establish effective aging management program of buried commodities in nuclear power plant. Basic informations on material characteristics, aging degradation experiences and maintenance history were gathered. Considering their degradation effects on power operation or safety, buried commodities were screened for the aging management priority. Various inspection techniques were applied in field survey and inspection, and their results were incorporated in the life assessment of buried commodities. In the aspect of aging degradation, general status of buried commodities were considered still sound while some revealed local degradation

Accelerated thermal and radiation-oxidation combined degradation of electric cable insulation materials

International Nuclear Information System (INIS)

Yagi, Toshiaki; Seguchi, Tadao; Yoshida, Kenzo

1986-03-01

For the development of accelerated testing methodology to estimate the life time of electric cable, which is installed in radiation field such as a nuclear reactor containment vessel, radiation and thermal combined degradation of cable insulation and jacketing materials was studied. The materials were two types of formulated polyethylene, ethylene-propylene rubber, Hypalon, and Neoprene. With Co-60 γ-rays the materials were irradiated up to 0.5 MGy under vacuum and in oxygen under pressure, then exposed to thermal aging at elevated temperature in oxygen. The degradation was investigated by the tensile test, gelfraction, and swelling measurements. The thermal degradation rate for each sample increases with increase of oxygen concentration, i.e. oxygen pressure, during the aging, and tends to saturate above 0.2 MPa of oxygen pressure. Then, the effects of irradiation and the temperature on the thermal degradation rate were investigated at the oxygen pressure of 0.2 MPa in the temperature range from 110 deg C to 150 deg C. For all of samples irradiated in oxygen, the following thermal degradation rate was accelerated by several times comparing with unirradiated samples, while the rate of thermal degradation for the sample except Neoprene irradiated under vacuum was nearly equal to that of unirradiated one. By the analysis of thermal degradation rate against temperature using Arrhenius equation, it was found that the activation energy tends to decrease for the samples irradiated in oxidation condition. (author)

Radiation degradation and hemolytic toxicity evaluation of mono azo reactive dyes

International Nuclear Information System (INIS)

Saeed, Q.U.; Bhatti, I.A.; Ashraf, A.

2017-01-01

Monoazo reactive dyes have been synthesized and subjected to degradation before their application. Advanced oxidation process has been recognized as a promising radiation technology for the remediation of hazardous organic compounds. Radiation induced degradation of two mono azo reactive dyes have been tried at different absorbed dose, 5 kGy,10 kGy and 15 kGy. Aqueous solutions of these dyes were treated with gamma radiation using Cs 137 radiation source at Nuclear Institute of Agriculture and Biology (NIAB) Faisalabad. Dyes were evaluated spectrophotometrically by UV-visible and fourier transform infra red (FT-IR) spectroscopic techniques before and after irradiation to analyse their percentage decolorization and degradation. Maximum percentage decolorization of 93% and 63% was achieved for mono azo dyes D1 and D2 at 15 kGy absorbed dose. Toxicity study of these dyes was also tested by haemolytic activity assay. Percentage haemolytic activity of untreated dyes was found within permissible limit showing non toxicity of dye solutions. (author)

Preliminary analysis for u tube degradation in CANDU steam generator using CATHENA

Energy Technology Data Exchange (ETDEWEB)

Shin, So Eun; Lee, Jeong Hun; Park, Tong Kyu; Hwang, Su Hyun [FNC Technology Co., Seoul (Korea, Republic of); Jung, Jong Yeo [KAERI, Daejeon (Korea, Republic of)

2012-10-15

The interest in plant safety and integrity has been increasing due to long term operation of nuclear power plants (NPPs) and lots of efforts have been devoted to developing the degradation evaluation model for all the Structure, System, and Components (SSCs) of NPPs in these days. The efforts, however, were mainly concentrated on pressurized light water reactors (PWRs) in domestic. In contrast, the study for the aging degradation of counterparts of CANDU (CANada Deuterium Uranium) reactors has been rarely performed, even though Wolsong unit 1 (WS1), that is a CANDU 6 NPP in Korea, has been operating for almost 30 years. Therefore, the assessment of the aging degradation is required and the proper and exact evaluation model for the aging degradation of SCCs of CANDU, especially WS1, is urgently needed. In this study, the aging degradation of steam generators (SGs) in WS1 was mainly discussed. Based on cases of the aging degradation of SGs in overseas CANDU reactors, the major potential aging mechanisms of SGs were estimated since there has been no case of accident due to degradation in CANDU NPPs in Korea . Some core parameters which are indicators of the degree of degradation were calculated by CATHENA (Canadian algorithm for thermal hydraulic network analysis). In the result of comparing two calculation cases; core parameters for only aged SGs in fresh plant and those for all the aged component, it can be concluded that aging of SGs is a main component in the degradation assessment of CANDU NPPs, and keeping the integrity of steam generator (SG) tubes is important to guarantee the safety of the NPPs.

Nuclear liquid wastes treatment: study of the reverse osmosis membranes degradation under γ irradiation

International Nuclear Information System (INIS)

Combernoux, Nicolas

2015-01-01

The treatment of nuclear liquid wastes by reverse osmosis (RO) involved issues of the water radiolysis and the membrane ageing due to γ irradiation effects. Membrane performances (permeability, strontium and cesium retention) were assessed after γ irradiation. Irradiation was carried out with an external 60 Co source in different conditions that simulated real used of the process (dose from 0.1 to 1 MGy, dose rate of 0.5 and 5 kGy.h -1 , with or without oxygen or water). Several analytical methods were performed to evaluate irradiation effects (ATR-FTIR, XPS, gas production, water soluble species released from the membrane). The methodology developed led to relevant information due to an innovative analytical protocol. Membrane performances started dropping between 0.2 and 0.5 MGy with oxygen and water (dose rate 0.5 kGy.h -1 ). This shift was linked to chains scissions inside the membrane active layer. The membrane degradation was weaker without oxygen or water or at high dose rate (5 kGy.h -1 ). Results showed that each analysis comforted each other. Membrane performances were also evaluated with three different types of liquid effluents, representing radioactive effluents from a post-disaster situation (groundwater type), disaster situation (seawater) or process water. Experiments were carried out at lab and pilot scales. Results indicated that the treatment of each effluent was possible by RO with an adequate choice of membrane and operating parameters. Finally, the time to reach an integrated dose threshold for the membrane in real conditions was estimated with the RABBI software: a dozen of days in the case of disaster situation to several years in the two other cases. (author) [fr

Proposed design modifications and technical specification changes on grid voltage degradation for the Point Beach Nuclear Plant, Units 1 and 2 (Docket Nos. 50-266 and 50-301). Technical evaluation report

International Nuclear Information System (INIS)

White, R.L.

1981-01-01

This report documents the technical evaluation of the proposed design mofifications and Technical Specification changes for protection of Class 1E equipment from grid voltage degradation for the Point Beach Nuclear Plant, Units 1 and 2. The review criteria are based on several IEEE standards and the Code of Federal Regulations. The evaluation compares the submittals made by the licensee with the NRC staff positions and the review criteria and presents the reviewer's conclusion on the acceptability of the proposed system

FRAMEWORK FOR STRUCTURAL ONLINE HEALTH MONITORING OF AGING AND DEGRADATION OF SECONDARY PIPING SYSTEMS DUE TO SOME ASPECTS OF EROSION

Energy Technology Data Exchange (ETDEWEB)

Gribok, Andrei V.; Agarwal, Vivek

2017-06-01

This paper describes the current state of research related to critical aspects of erosion and selected aspects of degradation of secondary components in nuclear power plants (NPPs). The paper also proposes a framework for online health monitoring of aging and degradation of secondary components. The framework consists of an integrated multi-sensor modality system, which can be used to monitor different piping configurations under different degradation conditions. The report analyses the currently known degradation mechanisms and available predictive models. Based on this analysis, the structural health monitoring framework is proposed. The Light Water Reactor Sustainability Program began to evaluate technologies that could be used to perform online monitoring of piping and other secondary system structural components in commercial NPPs. These online monitoring systems have the potential to identify when a more detailed inspection is needed using real time measurements, rather than at a pre-determined inspection interval. This transition to condition-based, risk-informed automated maintenance will contribute to a significant reduction of operations and maintenance costs that account for the majority of nuclear power generation costs. Furthermore, of the operations and maintenance costs in U.S. plants, approximately 80% are labor costs. To address the issue of rising operating costs and economic viability, in 2017, companies that operate the national nuclear energy fleet started the Delivering the Nuclear Promise Initiative, which is a 3 year program aimed at maintaining operational focus, increasing value, and improving efficiency. There is unanimous agreement between industry experts and academic researchers that identifying and prioritizing inspection locations in secondary piping systems (for example, in raw water piping or diesel piping) would eliminate many excessive in-service inspections. The proposed structural health monitoring framework takes aim at

Aging considerations for pressurizers in nuclear power plants

International Nuclear Information System (INIS)

Ware, A.G.

1988-01-01

This paper discusses the degradation mechanisms affecting the residual life of the nuclear pressurized water reactor (PWR) pressurizer and its subcomponents. The major sources of degradation for pressurizers are thermal transients such as plant heatups and cooldowns, internal pressure within the vessel, high intermittent flow through the spray nozzle, differential thermal movement causing rubbing of the immersion heater sheathes, and prolonged exposure to chemical and thermal conditions that can potentially lead to degradation. The latter includes thermal embrittlement of cast stainless steel spray heads and chemically assisted intergranular stress corrosion cracking of stainless steel. Steam leakage that interacts with lubricants used to assemble manway bolted joints can cause corrosion of bolts

The Effect of Degraded Digital Instrumentation and Control systems on Human-system Interfaces and Operator Performance

International Nuclear Information System (INIS)

O'Hara, J.M.; Gunther, B.; Martinez-Guridi, G.; Xing, J.; Barnes, V.

2010-01-01

Integrated digital instrumentation and control (I and C) systems in new and advanced nuclear power plants (NPPs) will support operators in monitoring and controlling the plants. Even though digital systems typically are expected to be reliable, their potential for degradation or failure significantly could affect the operators performance and, consequently, jeopardize plant safety. This U.S. Nuclear Regulatory Commission (NRC) research investigated the effects of degraded I and C systems on human performance and on plant operations. The objective was to develop technical basis and guidance for human factors engineering (HFE) reviews addressing the operator's ability to detect and manage degraded digital I and C conditions. We reviewed pertinent standards and guidelines, empirical studies, and plant operating experience. In addition, we evaluated the potential effects of selected failure modes of the digital feedwater control system of a currently operating pressurized water reactor (PWR) on human-system interfaces (HSIs) and the operators performance. Our findings indicated that I and C degradations are prevalent in plants employing digital systems, and the overall effects on the plant's behavior can be significant, such as causing a reactor trip or equipment to operate unexpectedly. I and C degradations may affect the HSIs used by operators to monitor and control the plant. For example, deterioration of the sensors can complicate the operators interpretation of displays, and sometimes may mislead them by making it appear that a process disturbance has occurred. We used the findings as the technical basis upon which to develop HFE review guidance.

Intrinsic immunogenicity of rapidly-degradable polymers evolves during degradation.

Science.gov (United States)

Andorko, James I; Hess, Krystina L; Pineault, Kevin G; Jewell, Christopher M

2016-03-01

Recent studies reveal many biomaterial vaccine carriers are able to activate immunostimulatory pathways, even in the absence of other immune signals. How the changing properties of polymers during biodegradation impact this intrinsic immunogenicity is not well studied, yet this information could contribute to rational design of degradable vaccine carriers that help direct immune response. We use degradable poly(beta-amino esters) (PBAEs) to explore intrinsic immunogenicity as a function of the degree of polymer degradation and polymer form (e.g., soluble, particles). PBAE particles condensed by electrostatic interaction to mimic a common vaccine approach strongly activate dendritic cells, drive antigen presentation, and enhance T cell proliferation in the presence of antigen. Polymer molecular weight strongly influences these effects, with maximum stimulation at short degradation times--corresponding to high molecular weight--and waning levels as degradation continues. In contrast, free polymer is immunologically inert. In mice, PBAE particles increase the numbers and activation state of cells in lymph nodes. Mechanistic studies reveal that this evolving immunogenicity occurs as the physicochemical properties and concentration of particles change during polymer degradation. This work confirms the immunological profile of degradable, synthetic polymers can evolve over time and creates an opportunity to leverage this feature in new vaccines. Degradable polymers are increasingly important in vaccination, but how the inherent immunogenicity of polymers changes during degradation is poorly understood. Using common rapidly-degradable vaccine carriers, we show that the activation of immune cells--even in the absence of other adjuvants--depends on polymer form (e.g., free, particulate) and the extent of degradation. These changing characteristics alter the physicochemical properties (e.g., charge, size, molecular weight) of polymer particles, driving changes in

Strategy - The after-Fukushima of the French nuclear sector - Nuclear must be an explicit choice - Siemens, leader of a nuclear-free Germany

International Nuclear Information System (INIS)

Dupin, L.

2012-01-01

A first article comments the consequences of the Fukushima accident for the French nuclear sector: the risk of an extreme accident must be taken into account; this will result in works and investments; the cost of the French nuclear-based electricity will increase; the debate on the dismantling costs will be on again. Despite these problems, the French nuclear industry relies on its development perspectives abroad, notably in China. In an interview, the chairman of Areva discusses his first six months of action, evokes the implementation of the strategic action plan and the consequences of France's financial degradation, evokes the UraMin affair, the consequences of the Fukushima accident on Areva's offer, the costs of works required by the ASN, the perspectives for the EPR reactor, Areva's activities in the renewable energy sector. A last article comments the strategy of the German company Siemens who decided to phase out nuclear, and to focus notably of wind energy

Aging assessment of large electric motors in nuclear power plants

International Nuclear Information System (INIS)

Villaran, M.; Subudhi, M.

1996-03-01

Large electric motors serve as the prime movers to drive high capacity pumps, fans, compressors, and generators in a variety of nuclear plant systems. This study examined the stressors that cause degradation and aging in large electric motors operating in various plant locations and environments. The operating history of these machines in nuclear plant service was studied by review and analysis of failure reports in the NPRDS and LER databases. This was supplemented by a review of motor designs, and their nuclear and balance of plant applications, in order to characterize the failure mechanisms that cause degradation, aging, and failure in large electric motors. A generic failure modes and effects analysis for large squirrel cage induction motors was performed to identify the degradation and aging mechanisms affecting various components of these large motors, the failure modes that result, and their effects upon the function of the motor. The effects of large motor failures upon the systems in which they are operating, and on the plant as a whole, were analyzed from failure reports in the databases. The effectiveness of the industry's large motor maintenance programs was assessed based upon the failure reports in the databases and reviews of plant maintenance procedures and programs

DEGRADATION MODES OF ALLOY 22 IN YUCCA MOUNTAIN REPOSITORY CONDITIONS

Energy Technology Data Exchange (ETDEWEB)

F. Hua; G.M. Gordon; R.B. Rebak

2005-10-13

The nuclear waste package design for Yucca Mountain (Nevada, USA), in its current configuration, consists of a double wall cylindrical container fabricated using a highly corrosion resistant Ni-based Alloy 22 for the outer barrier and type 316 stainless steel for the inner structural vessel. A mailbox-shaped drip shield fabricated primarily using Ti Grade 7 will cover the waste packages. The environmental degradation of the relevant materials have been extensively studied and modeled for over ten years. This paper reviews the state-of-the-art understanding of the degradation modes of Alloy 22 (N06022) due to its interaction with the predicted in-drift mountain conditions including temperature and types of electrolytes. Subjects discussed include thermal aging and phase stability, dry oxidation, general and localized corrosion, stress corrosion cracking and hydrogen induced cracking.

DEGRADATION MODES OF ALLOY 22 IN YUCCA MOUNTAIN REPOSITORY CONDITIONS

International Nuclear Information System (INIS)

Hua, F.; Gordon, G.M.; Rebak, R.B.

2005-01-01

The nuclear waste package design for Yucca Mountain (Nevada, USA), in its current configuration, consists of a double wall cylindrical container fabricated using a highly corrosion resistant Ni-based Alloy 22 for the outer barrier and type 316 stainless steel for the inner structural vessel. A mailbox-shaped drip shield fabricated primarily using Ti Grade 7 will cover the waste packages. The environmental degradation of the relevant materials have been extensively studied and modeled for over ten years. This paper reviews the state-of-the-art understanding of the degradation modes of Alloy 22 (N06022) due to its interaction with the predicted in-drift mountain conditions including temperature and types of electrolytes. Subjects discussed include thermal aging and phase stability, dry oxidation, general and localized corrosion, stress corrosion cracking and hydrogen induced cracking

Transients analysis able to lead Pressurised Water Reactors cores to degraded situations, analysis of resulting configurations

International Nuclear Information System (INIS)

Shin, Hyeong-Ki

1999-01-01

The severe accidents that occurred recently on nuclear reactors such as Chernobyl and T.M.1.2 have led many countries utilizing nuclear energy to examine their severe accident management. This thesis focuses on this problem and aims at analyzing, in terms of reactivity, degraded core behavior resulting from different accidental configurations. Two types of core degradation can be encountered: local degradation (the destruction of isolated assemblies in the core) or spreading degradation (the destruction of neighboring assemblies). The TMI accident is an example of spreading degradation in the core. The simplicity of implementing the control rod ejection accident calculation as compared to other accidental transients have motivated the choice of this accident as a determinant for local degraded core configurations. The control rod ejection accident presents important three dimensional effects and introduces neutronic/thermohydraulic coupling. The implementation and validation of already existing three dimensional coupled calculation scheme, allowed one to analyze the consequences of such an accident and to the conclusion that only unrealistic hypotheses of assembly permutation could lead to a partial core degradation. A reasonable estimate of stored energy in the assemblies with high bum up, in relation to the stored energy in the hot spot, was also obtained for the first time. The recently performed experiments (CABRI experiments) showed that in highly burned up assemblies, the capacity to store energy decreases strongly in relation to new assemblies. This first estimate of the distribution of produced energy between different assemblies, during the rod ejection accident, offers an important piece of knowledge in the study of the consequences of an eventual fuel cycle extension (presently under consideration by development companies). Finally, the analysis of degraded core reactivity itself has been performed for a vast range of the degraded core configurations

Plant polyphenols mobilize nuclear copper in human peripheral lymphocytes leading to oxidatively generated DNA breakage: implications for an anticancer mechanism.

Science.gov (United States)

Shamim, Uzma; Hanif, Sarmad; Ullah, M F; Azmi, Asfar S; Bhat, Showket H; Hadi, S M

2008-08-01

It was earlier proposed that an important anti-cancer mechanism of plant polyphenols may involve mobilization of endogenous copper ions, possibly chromatin-bound copper and the consequent pro-oxidant action. This paper shows that plant polyphenols are able to mobilize nuclear copper in human lymphocytes, leading to degradation of cellular DNA. A cellular system of lymphocytes isolated from human peripheral blood and comet assay was used for this purpose. Incubation of lymphocytes with neocuproine (a cell membrane permeable copper chelator) inhibited DNA degradation in intact lymphocytes. Bathocuproine, which is unable to permeate through the cell membrane, did not cause such inhibition. This study has further shown that polyphenols are able to degrade DNA in cell nuclei and that such DNA degradation is inhibited by neocuproine as well as bathocuproine (both of which are able to permeate the nuclear pore complex), suggesting that nuclear copper is mobilized in this reaction. Pre-incubation of lymphocyte nuclei with polyphenols indicates that it is capable of traversing the nuclear membrane. This study has also shown that polyphenols generate oxidative stress in lymphocyte nuclei which is inhibited by scavengers of reactive oxygen species (ROS) and neocuproine. These results indicate that the generation of ROS occurs through mobilization of nuclear copper resulting in oxidatively generated DNA breakage.

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

Reponen, H.; Viitasaari, O.

1985-09-01

These general reviews of the operation of the Finnish nuclear power plants concentrate on such events and discoveries related to reactor and radiation safety that the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as significant. In the report period, no event essentially degraded plant safety nor posed a radiation hazard to the personnel or the environment. The report also includes a summary of the radiation safety of the personnel and the environment and tabulated data on the production and capacity factors of the plants. (author)

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

Lehtinen, P.

1986-08-01

These general reviews of the operation of the Finnish nuclear power plants concentrate on such events and discoveries related to reactor and radiation safety that the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as noteworthy. The report also includes a summary of the radiation safety of the personnel and the environment, as well as tabulated data on the production and load factors of the plants. In the report period, no event essentially degraded plant safety nor posed a radiation hazard to the personnel or the environment. (author)

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

Reponen, H.; Viitasaari, O.; Lehtinen, P.

1985-11-01

These general reviews of the operation of the Finnish nuclear power plants concentrate on such events and discoveries related to reactor and radiation safety that the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as significant. In the report period, no event essentially degraded plant safety nor posed a radiation hazard to the personnel or the environment. The report also includes a summary of the radiation safety of the personnel and the environment and tabulated data on the production and load factors of the plants. (author)

The effect of soil mineral phases on the abiotic degradation of selected organic compounds. Progress report, June 31, 1990--May 31, 1993

Energy Technology Data Exchange (ETDEWEB)

Sandhu, S.S.

1993-05-31

Tetraphenylborate (TPB) is used to precipitate radioactive 137Cs from high-level nuclear waste water at the Defense Waste Processing Facility (DWPF) operated by the US DOE at the Savannah River Plant (SRP). The process is part of the procedure for the glassification of high-level nuclear waste in preparation for its long-term geological disposal. The decontaminated waste water contains millimolar quantities of TPB that will be processed into salt concretions. The transporation and use of large amounts of TPB can potentially result in the release of TPB into soil or aquatic environments. Previous study has shown that TPB degrades in soils to initially form diphenylborinic acid (DPBA) and biphenyl. DPBA appears to degrade further into other unidentified compounds which subsequently degrade into inorganic boron. The factors which promote the abiotic degradation of TPB need to be investigated since this chemical is used in the processing of radioactive wastes. TPB and its intermediate product, DPBA, have been reported to be toxic to microorganisms and plants, dependent on soil or water environments for their survival and growth.

Analysis for the Effects of Grid Voltage Degradation on APR1400 Operation, Case Study for Egypt

International Nuclear Information System (INIS)

Hassan, Mostafa Ahmed Fouad; Koo, Chang Choong

2015-01-01

Egypt is one of the countries planning to introduce a NPP into its electrical power system. Although the Egyptian power system has sufficient capacity to integrate any commercially available nuclear unit as the total installed capacity of the power system is more than 32GWe, which is more than 10 times capacity of any nuclear unit in the range of 1000 to 1700MWe, the system is vulnerable to extreme voltage variations, especially voltage degradation during peak load conditions. These conditions can lead to voltage collapse if a counter measure, usually load shedding, is not taken in a proper time. Hence, it is necessary to analyze the effect of such conditions on the safe and economic operation of the NPP. In this paper we analyzed the effects of grid voltage degradation on the safe and economic operation of the Advanced Power Reactor (APR1400) to determine any adverse effects on the plant auxiliary loads while operating in the Egyptian power system. In this paper the effects of grid voltage degradation on the safe and economic operation of APR1400 were investigated taking into account, generator operating limits, plant safety requirements, operation modes and loading categories in order to determine any adverse effect on the plant auxiliary loads while operating in the Egyptian power system. The results of the load flow and motor starting analysis demonstrated that during normal operation the automatic voltage regulator and transformers OLTCs can mitigate the effect of grid voltage degradation without any detrimental effect on the plant auxiliary loads. During the highly unlikely LOCA condition if the grid voltage degraded below 95%, the degraded voltage relays at Class 1E 4.16 kV buses will trip the supply and load breakers and reconnect the required safety loads to the EDG after 4 minutes time delay. During this period the safety loads required for LOCA can be started and accelerated to their rated speed safely even in the worst case of expected degraded voltage

Monitoring of radiolytic degradation of benzo(a)pyrene using γ-rays in aqueous media by HPLC

International Nuclear Information System (INIS)

Butt, S. Bilal; Qureshi, Rashid N.; Ahmed, Shafaat

2005-01-01

Poly nuclear aromatic hydrocarbons (PAHs) are generated in the environment by various industrial processes and anthropogenic activities. These compounds are quite stable and persist in the environment due to the aromatic bonding within the rings. Benzo(a)pyrene (B(a)P) is a potential carcinogenic and conditions for its degradation have been optimized by investigating γ-ray dose intensity, its concentration effect and the influence of surfactant presence. HPLC has been used to monitor the degree of degradation of B(a)P under the optimum conditions

VRK1 regulates Cajal body dynamics and protects coilin from proteasomal degradation in cell cycle.

Science.gov (United States)

Cantarero, Lara; Sanz-García, Marta; Vinograd-Byk, Hadar; Renbaum, Paul; Levy-Lahad, Ephrat; Lazo, Pedro A

2015-06-12

Cajal bodies (CBs) are nuclear organelles associated with ribonucleoprotein functions and RNA maturation. CBs are assembled on coilin, its main scaffold protein, in a cell cycle dependent manner. The Ser-Thr VRK1 (vaccinia-related kinase 1) kinase, whose activity is also cell cycle regulated, interacts with and phosphorylates coilin regulating assembly of CBs. Coilin phosphorylation is not necessary for its interaction with VRK1, but it occurs in mitosis and regulates coilin stability. Knockdown of VRK1 or VRK1 inactivation by serum deprivation causes a loss of coilin phosphorylation in Ser184 and of CBs formation, which are rescued with an active VRK1, but not by kinase-dead VRK1. The phosphorylation of coilin in Ser184 occurs during mitosis before assembly of CBs. Loss of coilin phosphorylation results in disintegration of CBs, and of coilin degradation that is prevented by proteasome inhibitors. After depletion of VRK1, coilin is ubiquitinated in nuclei, which is partly mediated by mdm2, but its proteasomal degradation occurs in cytosol and is prevented by blocking its nuclear export. We conclude that VRK1 is a novel regulator of CBs dynamics and stability in cell cycle by protecting coilin from ubiquitination and degradation in the proteasome, and propose a model of CB dynamics.

Damage Assessment Technologies for Prognostics and Proactive Management of Materials Degradation (PMMD)

International Nuclear Information System (INIS)

Bond, Leonard J.; Doctor, Steven R.; Griffin, Jeffrey W.; Hull, Amy B.; Malik, Shah

2009-01-01

There are approximately 440 operating reactors in the global nuclear power plant (NPP) fleet with an average age greater than 20 years and design lives of 30 or 40 years. The United States is currently implementing license extensions of 20 years on many plants, and consideration is now being given to the concept of 'life-beyond-60', license extension from 60 to 80 years and potentially longer. In almost all countries with NPPs, authorities are looking at some form of license renewal program. In support of NPP license renewal over the past decade, various national and international programs have been initiated. This paper discusses stressor-based prognostics and its role as part of emerging trends in Proactive Management of Materials Degradation (PMMD) applied to nuclear power plant structures, systems and components (SSC). The paper concisely explains the US Nuclear Regulatory Commission's (NRC) program in PMMD, the basic principles of PMMD and its relationship to advanced diagnostics and prognostics. It then provides an assessment of the state of maturity for diagnostic and prognostic technologies, including NDE and related technologies for damage assessment, and the current trend to move from condition-based maintenance to on-line monitoring for advanced diagnostics and stressor-based prognostics. This development in technology requires advances in sensors; better understanding of what and how to measure within a nuclear power plant; enhanced data interrogation, communication and integration; new prediction models for damage/aging evolution; system integration for real-world deployments and quantification of uncertainties in what are inherently ill-posed problems. Stressor-based analysis is based upon understanding which stressor characteristics (e.g., pressure transients) provide a percussive indication that can be used for mapping subsequent damage due to a specific degradation mechanism. The resulting physical damage and the associated decrease in asset

A study on the evaluation of material degradation using ball indentation method

International Nuclear Information System (INIS)

Kim, Jeong Pyo; Seok, Chang Sung; Ahn, Ha Neul

2000-01-01

As huge energy transfer systems like a nuclear power plant, steam power plant and petrochemical plant are operated for a long time, mechanical properties are changed by degradation. The life time of the systems can be affected by the mechanical properties. BI(Ball Indentation) test has a potential to replace conventional fracture tests like a uniaxial tensile test, fracture toughness test, hardness test and so on. In this paper, we would like to present the aging evaluation technique by the BI method. The four classes of the thermally aged 1Cr-1Mo-0.25V specimens were prepared using an artificially accelerated aging method. Tensile tests, fracture toughness tests, hardness tests and BI tests were performed. The results of the BI tests were in good agreement with fracture characteristics by a standard fracture test method. The IDE(Indentation Deformation Energy) of a BI technique as a new parameter for evaluating a degradation was suggested and the new IDE parameter clearly depicts the degradation degree

Technical strategy map to employing nuclear power plant aging management

International Nuclear Information System (INIS)

Sekimura, Naoto; Kanno, Masanori

2008-01-01

Stated in this report are back ground of technical strategy map for nuclear power plant aging management, result of the first road map, significance of technical strategy map, introduction scenario, technology map, road map, upgrade in every year, three groups of academia, industry and government, plan of technical strategy map, upgrade system, comprehensive introduction scenario, measures of nuclear power plant aging management in Japan and the world, new inspection system, outline of 'technical strategy map 2008', preparation of technical information bases in industry, academia and government, collaboration of them, safety researches of neutron radiation damage, stress corrosion crack, fatigue, piping thinning, insulation degradation, concrete degradation, thermal aging, evaluation technologies of earthquake resistance, preparation of rules and standards, ideal maintenance, and training talent. (S.Y.)

Financing nuclear power

International Nuclear Information System (INIS)

Sheriffah Noor Khamseah Al-Idid Syed Ahmad Idid

2009-01-01

Global energy security and climate change concerns sparked by escalating oil prices, high population growth and the rapid pace of industrialization are fueling the current interest and investments in nuclear power. Globally, a significant number policy makers and energy industry leaders have identified nuclear power as a favorable alternative energy option, and are presently evaluating either a new or an expanded role for nuclear power. The International Atomic Energy Agency (IAEA) has reported that as of October 2008, 14 countries have plans to construct 38 new nuclear reactors and about 100 more nuclear power plants have been written into the development plans of governments for the next three decades. Hence as new build is expected to escalate, issues of financing will become increasingly significant. Energy supply, including nuclear power, considered as a premium by government from the socio-economic and strategic perspective has traditionally been a sector financed and owned by the government. In the case for nuclear power, the conventional methods of financing include financing by the government or energy entity (utility or oil company) providing part of the funds from its own resources with support from the government. As national financing is, as in many cases, insufficient to fully finance the nuclear power plants, additional financing is sourced from international sources of financing including, amongst others, Export Credit Agencies (ECAs) and Multilateral Development Institutions. However, arising from the changing dynamics of economics, financing and business model as well as increasing concerns regarding environmental degradation , transformations in methods of financing this energy sector has been observed. This paper aims to briefly present on financing aspects of nuclear power as well as offer some examples of the changing dynamics of financing nuclear power which is reflected by the evolution of ownership and management of nuclear power plants

Interaction Profiling Identifies the Human Nuclear Exosome Targeting Complex

DEFF Research Database (Denmark)

Lubas, Michal Szymon; Christensen, Marianne Skovgaard; Kristiansen, Maiken Søndergaard

2011-01-01

from nucleoli, and consistently NEXT is specifically required for the exosomal degradation of promoter upstream transcripts (PROMPTs). We also detect putative homolog TRAMP subunits hTRF4-2 (Trf4p) and ZCCHC7 (Air2p) in hRRP6 and hMTR4 precipitates. However, at least ZCCHC7 function is restricted...... to nucleoli. Our results suggest that human nuclear exosome degradation pathways comprise modules of spatially organized cofactors that diverge from the yeast model....

Resistance temperature sensor aging degradation identification using LCSR (Loop Current Step Response) test

International Nuclear Information System (INIS)

Santos, Roberto Carlos dos; Goncalves, Iraci Martine Pereira

2013-01-01

Most critical process temperatures in nuclear power plants are measured using RTD (Resistance Temperature Detector) and thermocouples. In a PWR (Pressure Water Reactor) plant, the primary coolant temperature and feedwater temperature are measured using RTDs, and the temperature of the water that exits the reactor core is measured using thermocouples. These thermocouples are mainly used for temperature monitoring purposes and are therefore not generally subject to very stringent requirements for accuracy and response-time performance. In contrast, primary coolant RTDs typically feed the plant's control and safety systems and must, therefore, be very accurate and have good dynamic performance. The response time of RTDs and thermocouples has been characterized by a single parameter called the Plunge Time Constant. This is defined as the time it takes the sensor output to achieve 63.2 percent of its final value after a step change in temperature is impressed on its surface. This step change is typically achieved by suddenly immersing the sensor in a rotating tank of water, called Plunge Test. In nuclear reactors, however, plunge testing is inconvenient because the sensor must be removed from the reactor coolant piping and taken to a laboratory for testing. Nuclear reactor service conditions of 150 bar and 300°C are difficult to reproduce in the laboratory. Therefore, all laboratory tests are performed at much milder conditions, and the results are extrapolated to service conditions. This leads to significant errors in the measurement of sensor response times and an insitu test method called LCSR - Loop Current Step Response test was developed in the mid-1970s to measure remotely the response time of RTDs. In the LCSR method, the sensing element is heated by an electric current; the current causes Joule heating in the sensor and results in a temperature transient inside the sensor. The temperature transient in the element is recorded, and from this transient, the

Incomplete copolymer degradation of in situ chemotherapy.

Science.gov (United States)

Bourdillon, Pierre; Boissenot, Tanguy; Goldwirt, Lauriane; Nicolas, Julien; Apra, Caroline; Carpentier, Alexandre

2018-02-17

In situ carmustine wafers containing 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) are commonly used for the treatment of recurrent glioblastoma to overcome the brain-blood barrier. In theory, this chemotherapy diffuses into the adjacent parenchyma and the excipient degrades in maximum 8 weeks but no clinical data confirms this evolution, because patients are rarely operated again. A 75-year-old patient was operated twice for recurrent glioblastoma, and a carmustine wafer was implanted during the second surgery. Eleven months later, a third surgery was performed, revealing unexpected incomplete degradation of the wafer. 1H-Nuclear Magnetic Resonance was performed to compare this wafer to pure BCNU and to an unused copolymer wafer. In the used wafer, peaks corresponding to hydrophobic units of the excipient were no longer noticeable, whereas peaks of the hydrophilic units and traces of BCNU were still present. These surprising results could be related to the formation of a hydrophobic membrane around the wafer, thus interfering with the expected diffusion and degradation processes. The clinical benefit of carmustine wafers in addition to the standard radio-chemotherapy remains limited, and in vivo behavior of this treatment is not completely elucidated yet. We found that the wafer may remain after several months. Alternative strategies to deal with the blood-brain barrier, such as drug-loaded liposomes or ultrasound-opening, must be explored to offer larger drug diffusion or allow repetitive delivery.

Improving Farming With Nuclear Techniques

International Nuclear Information System (INIS)

Henriques, Sasha

2011-01-01

Soil erosion, land degradation, the excessive or inappropriate use of fertilisers in agriculture and poor water quality are threats to the environment and hamper development. IAEA projects apply nuclear technology to evaluate these risks and find ways to make better use of water and soil resources. Many countries have benefited from this programme, including Qatar, Chile, Kenya, Turkey, Vietnam and Bangladesh.

Aging of electric motors in nuclear power plants

International Nuclear Information System (INIS)

Subudhi, M.; Taylor, J.H.

1987-06-01

Motor degradation due to aging and service wear decreases reliability and increases the potential for failure during nuclear plant accident and post accident conditions. The impact of motor failures on plant safety is an important concern among the nuclear utilities and the government agency regulating this industry. Economic impacts, relating to plant availability and safety, as well as corrective maintenance, have prompted utilities to improve their maintenance programs to mitigate such aging effects. 2 refs., 3 figs

Determination of trace amounts of chemical warfare agent degradation products in decontamination solutions with NMR spectroscopy.

Science.gov (United States)

Koskela, Harri; Rapinoja, Marja-Leena; Kuitunen, Marja-Leena; Vanninen, Paula

2007-12-01

Decontamination solutions are used for an efficient detoxification of chemical warfare agents (CWAs). As these solutions can be composed of strong alkaline chemicals with hydrolyzing and oxidizing properties, the analysis of CWA degradation products in trace levels from these solutions imposes a challenge for any analytical technique. Here, we present results of application of nuclear magnetic resonance spectroscopy for analysis of trace amounts of CWA degradation products in several untreated decontamination solutions. Degradation products of the nerve agents sarin, soman, and VX were selectively monitored with substantially reduced interference of background signals by 1D 1H-31P heteronuclear single quantum coherence (HSQC) spectrometry. The detection limit of the chemicals was at the low part-per-million level (2-10 microg/mL) in all studied solutions. In addition, the concentration of the degradation products was obtained with sufficient confidence with external standards.

A Multi-State Physics Modeling approach for the reliability assessment of Nuclear Power Plants piping systems

International Nuclear Information System (INIS)

Di Maio, Francesco; Colli, Davide; Zio, Enrico; Tao, Liu; Tong, Jiejuan

2015-01-01

Highlights: • We model piping systems degradation of Nuclear Power Plants under uncertainty. • We use Multi-State Physics Modeling (MSPM) to describe a continuous degradation process. • We propose a Monte Carlo (MC) method for calculating time-dependent transition rates. • We apply MSPM to a piping system undergoing thermal fatigue. - Abstract: A Multi-State Physics Modeling (MSPM) approach is here proposed for degradation modeling and failure probability quantification of Nuclear Power Plants (NPPs) piping systems. This approach integrates multi-state modeling to describe the degradation process by transitions among discrete states (e.g., no damage, micro-crack, flaw, rupture, etc.), with physics modeling by (physic) equations to describe the continuous degradation process within the states. We propose a Monte Carlo (MC) simulation method for the evaluation of the time-dependent transition rates between the states of the MSPM. Accountancy is given for the uncertainty in the parameters and external factors influencing the degradation process. The proposed modeling approach is applied to a benchmark problem of a piping system of a Pressurized Water Reactor (PWR) undergoing thermal fatigue. The results are compared with those obtained by a continuous-time homogeneous Markov Chain Model

In-operation inspection technology development-4 ''development of degradation prediction technology for motor-operated valves''

Energy Technology Data Exchange (ETDEWEB)

Kikuo, Takeshima; Yuichi, Higashikawa [Hitachi Engineering and Production Div., Nuclear Systems Div., Hitachi, Ltd., Ibaraki (Japan); Masahiro, Koike [Power and Industrial Systems R and D Lab., Hitachi, Ltd., (Japan); Kenji, Matsumoto [Tokyo Research and Development Center, Japan Power Engineering and Inspection Corp. (Japan); Eiji, O' shima [Tokyo Institute of Technology (Japan)

2001-07-01

A method for degradation predicting technology has been proposed for motor operated valves in nuclear power plants which is based on the concept of condition monitoring for maintenance. This method (degradation prediction technology) eliminates the unnecessary overhaul of valves and realizes high reliability and economy. The degradation mechanism was clarified by long time heating experiments of gasket and gland packing and the wear test for them and stem nut to research valve parts degradation by stress (pressure, temperature, etc) during plant operation. Effective electric power measurements for motor operated valves were confirmed to be useful discovering valve part failures. The motor operated valve degradation prediction system was developed on the basis of the experiment results and mechanism. The system is able to predict the degradation of valve parts (gasket/gland packing, stem, stem nut, etc) utilizing plant data (pressure, temperature, etc) and effective power of the motor. The life of valve parts can be estimated from the experimental results. (authors)

Inspection of Nuclear Power Plant Containment Structures

Energy Technology Data Exchange (ETDEWEB)

Graves, H.L.; Naus, D.J.; Norris, W.E.

1998-12-01

Safety-related nuclear power plant (NPP) structures are designed to withstand loadings from a number of low-probability external and interval events, such as earthquakes, tornadoes, and loss-of-coolant accidents. Loadings incurred during normal plant operation therefore generally are not significant enough to cause appreciable degradation. However, these structures are susceptible to aging by various processes depending on the operating environment and service conditions. The effects of these processes may accumulate within these structures over time to cause failure under design conditions, or lead to costly repair. In the late 1980s and early 1990s several occurrences of degradation of NPP structures were discovered at various facilities (e.g., corrosion of pressure boundary components, freeze- thaw damage of concrete, and larger than anticipated loss of prestressing force). Despite these degradation occurrences and a trend for an increasing rate of occurrence, in-service inspection of the safety-related structures continued to be performed in a somewhat cursory manner. Starting in 1991, the U.S. Nuclear Regulatory Commission (USNRC) published the first of several new requirements to help ensure that adequate in-service inspection of these structures is performed. Current regulatory in-service inspection requirements are reviewed and a summary of degradation experience presented. Nondestructive examination techniques commonly used to inspect the NPP steel and concrete structures to identify and quantify the amount of damage present are reviewed. Finally, areas where nondestructive evaluation techniques require development (i.e., inaccessible portions of the containment pressure boundary, and thick heavily reinforced concrete sections are discussed.

9975 Shipping package component long-term degradation rates

Energy Technology Data Exchange (ETDEWEB)

Daugherty, W. L. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

2017-06-28

Special nuclear materials are being stored in the K-Area Complex using 3013 containers that are held within Model 9975 shipping packages. The service life for these packages in storage was recently increased from 15 to 20 years, since some of these packages have been stored for nearly 15 years. A strategy is also being developed whereby such storage might be extended beyond 20 years. This strategy is based on recent calculations that support acceptable 9975 package performance for 20 years with internal heat loads up to 19 watts, and identifies a lower heat load limit for which the package components should degrade at half the bounding rate or less, thus doubling the effective storage life for these lower wattage packages. The components of the 9975 package that are sensitive to aging under storage conditions are the fiberboard overpack and the O-ring seals, although some degradation of the lead shield and outer drum are also possible. This report summarizes degradation rates applicable to lower heat load storage conditions. In particular, the O-ring seals should provide leak-tight performance for more than 40 years in packages for which their maximum temperature is ≤135 °F. Similarly, the fiberboard should remain acceptable in performance of its required safety functions for up to 40 years in packages with a maximum fiberboard temperature ≤125 °F.

ENHANCEMENT OF RESISTANCE TO OXIDATIVE DEGRADATION OF NATURAL RUBBER THROUGH LATEX DEGRADATION

Institute of Scientific and Technical Information of China (English)

无

1998-01-01

A fully characterised natural rubber latex was subjected to mechanical degradation by stirring at intervals. The resistance to oxidative degradation of the different samples were studied by measuring the Plasticity retention indices (PRI).The results show that there is an enhancement of the PRI from 57% for the undegraded rubber to 79% for the one-hour degraded sample. Further degradation resulted in decrease of PRI as time of degradation increased. Therefore, the one-hour degraded sample is a special rubber with high oxidation resistance which is of great importance in engineering.

Significant incidents in nuclear fuel cycle facilities

Energy Technology Data Exchange (ETDEWEB)

NONE

1996-03-01

In contrast to nuclear power plants, events in nuclear fuel cycle facilities are not well documented. The INES database covers all the nuclear fuel cycle facilities; however, it was developed in the early 1990s and does not contain information on events prior to that. The purpose of the present report is to collect significant events and analyze them in order to give a safety related overview of nuclear fuel cycle facilities. Significant incidents were selected using the following criteria: release of radioactive material or exposure to radiation; degradation of items important to safety; and deficiencies in design, quality assurance, etc. which include criticality incidents, fire, explosion, radioactive release and contamination. This report includes an explanation, where possible, of root causes, lessons learned and action taken. 4 refs, 4 tabs.

Significant incidents in nuclear fuel cycle facilities

International Nuclear Information System (INIS)

1996-03-01

In contrast to nuclear power plants, events in nuclear fuel cycle facilities are not well documented. The INES database covers all the nuclear fuel cycle facilities; however, it was developed in the early 1990s and does not contain information on events prior to that. The purpose of the present report is to collect significant events and analyze them in order to give a safety related overview of nuclear fuel cycle facilities. Significant incidents were selected using the following criteria: release of radioactive material or exposure to radiation; degradation of items important to safety; and deficiencies in design, quality assurance, etc. which include criticality incidents, fire, explosion, radioactive release and contamination. This report includes an explanation, where possible, of root causes, lessons learned and action taken. 4 refs, 4 tabs

Progress on the degraded piping program - Phase II. Battelle Columbus Division

International Nuclear Information System (INIS)

Wilkowski, Gery; Ahmad, J.; Barnes, C.; Brust, F.; Guerrieri, D.; Kramer, G.; Landow, M.; Marschall, C.; Nakagaki, M.; Papaspyropoulos; Scott, P.

1988-01-01

The overall objective of the Degraded Piping Program is to verify and improve simple estimation schemes to predict the fracture behavior of circumferentially cracked pipe. The program is limited to quasi-static fracture and cracks in straight pipe. There are a variety of materials, flaw geometries, pipe sizes, and loading conditions evaluated. The Degraded Piping Program,which has been extended for one more year, will supply results that provide a basis for regulatory decisions regard applications for leak-before-break (LBB) and In-service flaw assessment. The significance of our results are summarized relative to how they may affect regulatory technical needs. The scope of the work in The Degraded Piping Program includes both analytical and experimental efforts. The experimental efforts have concentrated on testing circumferentially cracked pipe at 550 F (288 C) under si-static loading. Many of the tasks within this program were undertaken with the objective of determining if any detailed efforts were needed. This is true for both the analytical and experimental efforts. i e of the tasks have been slightly expanded during the course of the gram, while others were found to be of lesser concern and further efforts in those areas were not pursued. The results of this summary include the efforts of the third year. These efforts have contributed considerably to the understanding of the application of elastic-plastic fracture mechanics to nuclear piping systems. Rather than listing the significant technical contributions, these contributions are summarized below in relation to their application to LBB analyses, in-service flaw assessment criteria, and (3) material characterization and unusual behavior of nuclear piping materials at light water reactor (LWR) temperatures

Transient degradation of NF-κB proteins in macrophages after interaction with mast cell granules

Directory of Open Access Journals (Sweden)

Noriko Ito

1998-01-01

Full Text Available The exposure of the macrophage cell line, J774 to mast cell granules (MCG led to the form ation of altered nuclear transcription factor proteins (NFκBx, which had faster electrophoretic mobility than the p50 homodimer of NF-κB, but retained comparable DNA binding capacity. Antibodies to N-terminal peptides of p50, p52, p65 or c-Rel supershifted only a fraction of NF-κBx. Western blot analyses revealed that nuclear p65 and c-Rel were progressively degraded after exposure to MCG, whereas nuclear p50 appeared to be unaffected. In contrast, cytoplasmic p50, p65, c-Rel as well as IkBα remained intact after MCG treatment, although p52 was clearly degraded. In comparison to J774 cells, incubation of m ouse peritoneal macrophages with MCG resulted in more extensive alterations to NF-κB proteins. The alterations in NF-κB proteins did not affect the expression of inducible nitric oxide synthase (iNOS or TNF-α mRNA in J774 cells. These data indicate that exposure of J774 cells to MCG leads to generation of altered nuclear p52, p65 and c-Rel, which retain intact N-terminal peptides, specific oligonucleotide binding and transactivating activity. On the other hand, in peritoneal macrophages, MCG induce more extensive modifications to NF-κB proteins with associated inhibition of iNOS or TNF-α mRNA expression.

Enzyme-catalyzed degradation of biodegradable polymers derived from trimethylene carbonate and glycolide by lipases from Candida antarctica and Hog pancreas.

Science.gov (United States)

Liu, Feng; Yang, Jian; Fan, Zhongyong; Li, Suming; Kasperczyk, Janusz; Dobrzynski, Piotr

2012-01-01

Enzyme-catalyzed degradation of poly(trimethylene carbonate) homo-polymer (PTMC) and poly(trimethylene carbonate-co-glycolide) co-polymer (PTGA) was investigated in the presence of lipases from Candida antarctica and Hog pancreas. Degradation was monitored by gravimetry, size-exclusion chromatography (SEC), nuclear magnetic resonance (NMR), tensiometry and environmental scanning electron microscopy (ESEM). PTMC can be rapidly degraded by Candida antarctica lipase with 98% mass loss after 9 days, while degradation by Hog pancreas lipase leads to 27% mass loss. Introduction of 16% glycolide units in PTMC chains strongly affects the enzymatic degradation. Hog pancreas lipase becomes more effective to PTGA co-polymer with a mass loss of 58% after 9 days, while Candida antarctica lipase seems not able to degrade PTGA. Bimodal molecular weight distributions are observed during enzymatic degradation of both PTMC and PTGA, which can be assigned to the fact that the surface is largely degraded while the internal part remains intact. The composition of the PTGA co-polymer remains constant, and ESEM shows that the polymers are homogeneously eroded during enzymatic degradation. Contact angle measurements confirm the enzymatic degradation mechanism, i.e., enzyme adsorption on the polymer surface followed by enzyme-catalyzed chain cleavage.

Electrosleeve process for in-situ nuclear steam generator repair

International Nuclear Information System (INIS)

Barton, R.A.; Moran, T.E.; Renaud, E.

1997-01-01

Degradation of steam generator (SG) tubing by localized corrosion is a widespread problem in the nuclear industry that can lead to costly forced out-ages, unit de-rating, SG replacement or even the permanent shutdown of a reactor. In response to the onset of SG tubing degradation at Ontario Hydro's Pickering Nuclear Generating Station (PNGS) Unit 5, and the determined unsuitability of conventional repair methods (mechanically expanded or welded sleeves) for Alloy 400, an alternative repair technology was developed. Electrosleeve is a non-intrusive, low-temperature process that involves the electrodeposition of a nanocrystalline nickel microalloy forming a continuously bonded, structural layer over the internal diameter of the degraded region. This technology is designed to provide a long-term pressure boundary repair, fully restoring the structural integrity of the damaged region to its original state. This paper describes the Electrosleeve process for SG tubing repair and the unique properties of the advanced sleeve material. The successful installation of Electrosleeves that have been in service for more than three years in Alloy 400 SG tubing at the Pickering-5 CANDU unit, the more recent extension of the technology to Alloy 600 and its demonstration in a U.S. pressurized water reactor (PWR), is presented. A number of PWR operators have requested plant operating technical specification changes to permit Electrosleeve SG tube repair. Licensing of the Electrosleeve by the U.S. Nuclear Regulatory Commission (NRC) is expected imminently. (author)

Electrosleeve process for in-situ nuclear steam generator repair

International Nuclear Information System (INIS)

Renaud, E.; Brennenstuhl, A.M.; Stewart, D.R.; Gonzalez, F.

2000-01-01

Degradation of steam generator tubing by localized corrosion is a widespread problem in the nuclear industry that can lead to costly forced outages, unit derating, steam generator replacement or even the permanent shutdown of a reactor. In response to the onset of steam generator degradation at Ontario Power Generation's Pickering Nuclear Generating Station (PNGS) Unit 5, and the determined unsuitability of conventional repair methods (mechanically expanded or welded sleeves) for Alloy 400, an alternative repair technology was developed. Electrosleeve is a non-intrusive, low-temperature process that involves the electrodeposition of a nanocrystalline nickel microalloy forming a continuously bonded, structural layer over the internal diameter of the degraded region. This technology is designed to provide a long-term pressure boundary repair, fully restoring the structural integrity of the damaged region to its original state. This paper describes the Electrosleeve process for steam generator tubing repair and the unique properties of the advanced sleeve material. The successful installation of fourteen Electrosleeves that have been in service for more than six years in Alloy 400 tubing at the Pickering-S CANDU unit, and the more recent (Nov. 99) extension of the technology to Alloy 600 by the installation of 57 sleeves in a U.S. pressurized water reactor (PWR) at Callaway, is presented. The Electrosleeve process has been granted a conditional license by the U.S. Nuclear Regulatory Commission (NRC). In Canada, the process of licensing Electrosleeve with the CNSC / TSSA has begun. (author)

Kinetics of the degradation of sulfur mustard on ambient and moist concrete

International Nuclear Information System (INIS)

Brevett, Carol A.S.; Sumpter, Kenneth B.; Nickol, Robert G.

2009-01-01

The rate of degradation of the chemical warfare agent sulfur mustard, bis(2-chloroethyl) sulfide, was measured on ambient and moist concrete using 13 C Solid State Magic Angle Spinning Nuclear Magnetic Resonance (SSMAS NMR). Three samples of concrete made by the same formulation, but differing in age and alkalinity were used. The sulfur mustard eventually degraded to thiodiglycol and 1,4-oxathiane via the intermediate sulfonium ions CH-TG, H-TG, H-2TG and O(CH 2 CH 2 ) 2 S + CH 2 CH 2 OH on all of the concrete samples, and in addition formed 8-31% vinyl moieties on the newer, more alkaline concrete samples. This is the first observation of the formation of O(CH 2 CH 2 ) 2 S + CH 2 CH 2 OH on a solid substrate. The addition of 2-chloroethanol to concrete on which mustard had fully degraded to thiodiglycol and 1,4-oxathiane resulted in the formation of O(CH 2 CH 2 ) 2 S + CH 2 CH 2 OH, thus demonstrating the reversibility of sulfur mustard degradation pathways. The sulfur mustard degradation half-lives on ambient concrete at 22 deg. C ranged from 3.5 to 54 weeks. When the substrates were moistened, the degradation half-lives at 22 deg. C ranged from 75 to 350 h. The degradation of sulfur mustard occurred more quickly at elevated temperatures and with added water. The non-volatile toxic sulfonium ions persisted for months to years on concrete at 22 deg. C and weeks to months on concrete at 35 deg. C, before decomposing to the relatively non-toxic compounds thiodiglycol and 1,4-oxathiane

Safety and Radiation Protection at Swedish Nuclear Power Plants 2004

International Nuclear Information System (INIS)

2005-05-01

In 2004, no severe events occurred which challenged the safety at Swedish nuclear power plants. Two events were classified as Level 1 events on the 7-point International Nuclear Event Scale. The events are described in the chapter Operating Experience. During the year, relatively little new degradation and deficiencies were detected in the reactor barriers. The number of fuel defects is constantly decreasing. The same applies to the number of defects in the pressure-bearing systems. On the other hand, SKI has observed that damage is beginning to occur in the reactor containment. Applied control programmes are effective and capture most of the damage at an early stage before safety is affected. However, individual defects have been detected in material where such degradation was not anticipated and which is currently not regularly checked. SKI will follow up these observations thoroughly in order to judge whether there is a need for increased inspections. During the year, two defects found in the reactor containment were reported. The damage and degradation that occurred indicate that the causes were mainly due to defects during construction, or during subsequent plant modification. Taking into account the difficulty of inspecting the reactor containments and other vital building structures reliably, it is important for the licensees to continue to study possible ageing and degradation mechanisms that can affect the integrity and safety of the components. SKI continuously follows the progress of the degradation in the mechanical devices and building structures that form the plant barriers and defence-in-depth system. This includes both overall evaluations of the progress of degradation as a whole and the progress of degradation in each facility. Furthermore, the occurrence of different degradation mechanisms is followed. The power companies have intensified the rate of investment in nuclear power plants. Modernization work and safety reviews stipulated by the

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

Reponen, H.; Viitasaari, O.

1985-01-01

This general review of the operation of the Finnish nuclear power plants in the second quarter of the year 1984 concentrates on such events and discoveries related to reactor and radiation safety that the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as significant. In the report period, no event essentially degraded plant safety nor posed a radiation hazard to the personnel or the environment. The report also includes a summary of the radiation safety of the personnel and the environment and tabulated data on the production and availability of the plants. (author)

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

Reponen, H.; Viitasaari, O.

1985-05-01

This general review of the operation of the Finnish nuclear power plants in the third quarter of the year 1984 concentrates on such events and discoveries related to reactor and radiation safety that the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as significant. In the report period, no event essentially degraded plant safety nor posed a radiation hazard to the personnel or the environment. The report also includes a summary of the radiation safety of the personnel and the environment and tabulated data on the production and capacity factors of the plants. (author)

Mechanism of chromatin degradation in thymocytes of irradiated rats

International Nuclear Information System (INIS)

Zotova, R.N.; Umanskij, S.R.; Tokarskaya, V.I.

1983-01-01

A biphase change in poly (ADP-ribose) polymerase activity of the thymocyte chromatin was observed after 10 Gy irradiation of rats: during the first minutes the incorporation of 14 C-NAD increased by 40% then started decreasing to make 110, 60 and 35% after 1, 2 and 3 h, respectively. Irradiation of rat thymus chromatin in vitro sharply decreased poly (ADP-ribose) polymerase activity. The possible role of changes in the poly (ADP-ribose) synthesis in the activation of nuclear Ca/Mg-dependent endonuclease and in the postirradiation degradation of the thymocyte chromatin is discussed

Geochemistry Model Validation Report: Material Degradation and Release Model

Energy Technology Data Exchange (ETDEWEB)

H. Stockman

2001-09-28

The purpose of this Analysis and Modeling Report (AMR) is to validate the Material Degradation and Release (MDR) model that predicts degradation and release of radionuclides from a degrading waste package (WP) in the potential monitored geologic repository at Yucca Mountain. This AMR is prepared according to ''Technical Work Plan for: Waste Package Design Description for LA'' (Ref. 17). The intended use of the MDR model is to estimate the long-term geochemical behavior of waste packages (WPs) containing U. S . Department of Energy (DOE) Spent Nuclear Fuel (SNF) codisposed with High Level Waste (HLW) glass, commercial SNF, and Immobilized Plutonium Ceramic (Pu-ceramic) codisposed with HLW glass. The model is intended to predict (1) the extent to which criticality control material, such as gadolinium (Gd), will remain in the WP after corrosion of the initial WP, (2) the extent to which fissile Pu and uranium (U) will be carried out of the degraded WP by infiltrating water, and (3) the chemical composition and amounts of minerals and other solids left in the WP. The results of the model are intended for use in criticality calculations. The scope of the model validation report is to (1) describe the MDR model, and (2) compare the modeling results with experimental studies. A test case based on a degrading Pu-ceramic WP is provided to help explain the model. This model does not directly feed the assessment of system performance. The output from this model is used by several other models, such as the configuration generator, criticality, and criticality consequence models, prior to the evaluation of system performance. This document has been prepared according to AP-3.10Q, ''Analyses and Models'' (Ref. 2), and prepared in accordance with the technical work plan (Ref. 17).

Geochemistry Model Validation Report: Material Degradation and Release Model

International Nuclear Information System (INIS)

Stockman, H.

2001-01-01

The purpose of this Analysis and Modeling Report (AMR) is to validate the Material Degradation and Release (MDR) model that predicts degradation and release of radionuclides from a degrading waste package (WP) in the potential monitored geologic repository at Yucca Mountain. This AMR is prepared according to ''Technical Work Plan for: Waste Package Design Description for LA'' (Ref. 17). The intended use of the MDR model is to estimate the long-term geochemical behavior of waste packages (WPs) containing U. S . Department of Energy (DOE) Spent Nuclear Fuel (SNF) codisposed with High Level Waste (HLW) glass, commercial SNF, and Immobilized Plutonium Ceramic (Pu-ceramic) codisposed with HLW glass. The model is intended to predict (1) the extent to which criticality control material, such as gadolinium (Gd), will remain in the WP after corrosion of the initial WP, (2) the extent to which fissile Pu and uranium (U) will be carried out of the degraded WP by infiltrating water, and (3) the chemical composition and amounts of minerals and other solids left in the WP. The results of the model are intended for use in criticality calculations. The scope of the model validation report is to (1) describe the MDR model, and (2) compare the modeling results with experimental studies. A test case based on a degrading Pu-ceramic WP is provided to help explain the model. This model does not directly feed the assessment of system performance. The output from this model is used by several other models, such as the configuration generator, criticality, and criticality consequence models, prior to the evaluation of system performance. This document has been prepared according to AP-3.10Q, ''Analyses and Models'' (Ref. 2), and prepared in accordance with the technical work plan (Ref. 17)

Light Water Reactor Sustainability Program: survey of models for concrete degradation

International Nuclear Information System (INIS)

2014-01-01

Concrete has been used in the construction of nuclear facilities because of two primary properties: its structural strength and its ability to shield radiation. Concrete structures have been known to last for hundreds of years, but they are also known to deteriorate in very short periods of time under adverse conditions. The use of concrete in nuclear facilities for containment and shielding of radiation and radioactive materials has made its performance crucial for the safe operation of the facility. The goal of this report is to review and document the main aging mechanisms of concern for concrete structures in nuclear power plants (NPPs) and the models used in simulations of concrete aging and structural response of degraded concrete structures. This is in preparation for future work to develop and apply models for aging processes and response of aged NPP concrete structures in the Grizzly code. To that end, this report also provides recommendations for developing more robust predictive models for aging effects of performance of concrete.

CSNF WASTE FORM DEGRADATION: SUMMARY ABSTRACTION

Energy Technology Data Exchange (ETDEWEB)

J.C. CUNNANE

2004-08-31

The purpose of this model report is to describe the development and validation of models that can be used to calculate the release of radionuclides from commercial spent nuclear fuel (CSNF) following a hypothetical breach of the waste package and fuel cladding in the repository. The purpose also includes describing the uncertainties associated with modeling the radionuclide release for the range of CSNF types, exposure conditions, and durations for which the radionuclide release models are to be applied. This document was developed in accordance with Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package (BSC 2004 [DIRS 169944]). This document considers radionuclides to be released from CSNF when they are available for mobilization by gas-phase mass transport, or by dissolution or colloid formation in water that may contact the fuel. Because other reports address limitations on the dissolved and colloidal radionuclide concentrations (BSC 2004 [DIRS 169944], Table 2-1), this report does not address processes that control the extent to which the radionuclides released from CSNF are mobilized and transported away from the fuel either in the gas phase or in the aqueous phase as dissolved and colloidal species. The scope is limited to consideration of degradation of the CSNF rods following an initial breach of the cladding. It considers features of CSNF that limit the availability of individual radionuclides for release into the gaseous or aqueous phases that may contact the fuel and the processes and events expected to degrade these CSNF features. In short, the purpose is to describe the characteristics of breached fuel rods and the degradation processes expected to influence radionuclide release.

CSNF WASTE FORM DEGRADATION: SUMMARY ABSTRACTION

International Nuclear Information System (INIS)

CUNNANE, J.C.

2004-01-01

The purpose of this model report is to describe the development and validation of models that can be used to calculate the release of radionuclides from commercial spent nuclear fuel (CSNF) following a hypothetical breach of the waste package and fuel cladding in the repository. The purpose also includes describing the uncertainties associated with modeling the radionuclide release for the range of CSNF types, exposure conditions, and durations for which the radionuclide release models are to be applied. This document was developed in accordance with Technical Work Plan for: Regulatory Integration Modeling and Analysis of the Waste Form and Waste Package (BSC 2004 [DIRS 169944]). This document considers radionuclides to be released from CSNF when they are available for mobilization by gas-phase mass transport, or by dissolution or colloid formation in water that may contact the fuel. Because other reports address limitations on the dissolved and colloidal radionuclide concentrations (BSC 2004 [DIRS 169944], Table 2-1), this report does not address processes that control the extent to which the radionuclides released from CSNF are mobilized and transported away from the fuel either in the gas phase or in the aqueous phase as dissolved and colloidal species. The scope is limited to consideration of degradation of the CSNF rods following an initial breach of the cladding. It considers features of CSNF that limit the availability of individual radionuclides for release into the gaseous or aqueous phases that may contact the fuel and the processes and events expected to degrade these CSNF features. In short, the purpose is to describe the characteristics of breached fuel rods and the degradation processes expected to influence radionuclide release

Analytical measurements of fission products during a severe nuclear accident

Science.gov (United States)

Doizi, D.; Reymond la Ruinaz, S.; Haykal, I.; Manceron, L.; Perrin, A.; Boudon, V.; Vander Auwera, J.; tchana, F. Kwabia; Faye, M.

2018-01-01

The Fukushima accident emphasized the fact that ways to monitor in real time the evolution of a nuclear reactor during a severe accident remain to be developed. No fission products were monitored during twelve days; only dose rates were measured, which is not sufficient to carry out an online diagnosis of the event. The first measurements were announced with little reliability for low volatile fission products. In order to improve the safety of nuclear plants and minimize the industrial, ecological and health consequences of a severe accident, it is necessary to develop new reliable measurement systems, operating at the earliest and closest to the emission source of fission products. Through the French program ANR « Projet d'Investissement d'Avenir », the aim of the DECA-PF project (diagnosis of core degradation from fission products measurements) is to monitor in real time the release of the major fission products (krypton, xenon, gaseous forms of iodine and ruthenium) outside the nuclear reactor containment. These products are released at different times during a nuclear accident and at different states of the nuclear core degradation. Thus, monitoring these fission products gives information on the situation inside the containment and helps to apply the Severe Accident Management procedures. Analytical techniques have been proposed and evaluated. The results are discussed here.

Analytical measurements of fission products during a severe nuclear accident

Directory of Open Access Journals (Sweden)

Doizi D.

2018-01-01

Full Text Available The Fukushima accident emphasized the fact that ways to monitor in real time the evolution of a nuclear reactor during a severe accident remain to be developed. No fission products were monitored during twelve days; only dose rates were measured, which is not sufficient to carry out an online diagnosis of the event. The first measurements were announced with little reliability for low volatile fission products. In order to improve the safety of nuclear plants and minimize the industrial, ecological and health consequences of a severe accident, it is necessary to develop new reliable measurement systems, operating at the earliest and closest to the emission source of fission products. Through the French program ANR « Projet d’Investissement d’Avenir », the aim of the DECA-PF project (diagnosis of core degradation from fission products measurements is to monitor in real time the release of the major fission products (krypton, xenon, gaseous forms of iodine and ruthenium outside the nuclear reactor containment. These products are released at different times during a nuclear accident and at different states of the nuclear core degradation. Thus, monitoring these fission products gives information on the situation inside the containment and helps to apply the Severe Accident Management procedures. Analytical techniques have been proposed and evaluated. The results are discussed here.

Canonical Poly(A Polymerase Activity Promotes the Decay of a Wide Variety of Mammalian Nuclear RNAs.

Directory of Open Access Journals (Sweden)

Stefan M Bresson

2015-10-01

Full Text Available The human nuclear poly(A-binding protein PABPN1 has been implicated in the decay of nuclear noncoding RNAs (ncRNAs. In addition, PABPN1 promotes hyperadenylation by stimulating poly(A-polymerases (PAPα/γ, but this activity has not previously been linked to the decay of endogenous transcripts. Moreover, the mechanisms underlying target specificity have remained elusive. Here, we inactivated PAP-dependent hyperadenylation in cells by two independent mechanisms and used an RNA-seq approach to identify endogenous targets. We observed the upregulation of various ncRNAs, including snoRNA host genes, primary miRNA transcripts, and promoter upstream antisense RNAs, confirming that hyperadenylation is broadly required for the degradation of PABPN1-targets. In addition, we found that mRNAs with retained introns are susceptible to PABPN1 and PAPα/γ-mediated decay (PPD. Transcripts are targeted for degradation due to inefficient export, which is a consequence of reduced intron number or incomplete splicing. Additional investigation showed that a genetically-encoded poly(A tail is sufficient to drive decay, suggesting that degradation occurs independently of the canonical cleavage and polyadenylation reaction. Surprisingly, treatment with transcription inhibitors uncouples polyadenylation from decay, leading to runaway hyperadenylation of nuclear decay targets. We conclude that PPD is an important mammalian nuclear RNA decay pathway for the removal of poorly spliced and nuclear-retained transcripts.

Turnover of amyloid precursor protein family members determines their nuclear signaling capability.

Science.gov (United States)

Gersbacher, Manuel T; Goodger, Zoë V; Trutzel, Annette; Bundschuh, Diana; Nitsch, Roger M; Konietzko, Uwe

2013-01-01

The amyloid precursor protein (APP) as well as its homologues, APP-like protein 1 and 2 (APLP1 and APLP2), are cleaved by α-, β-, and γ-secretases, resulting in the release of their intracellular domains (ICDs). We have shown that the APP intracellular domain (AICD) is transported to the nucleus by Fe65 where they jointly bind the histone acetyltransferase Tip60 and localize to spherical nuclear complexes (AFT complexes), which are thought to be sites of transcription. We have now analyzed the subcellular localization and turnover of the APP family members. Similarly to AICD, the ICD of APLP2 localizes to spherical nuclear complexes together with Fe65 and Tip60. In contrast, the ICD of APLP1, despite binding to Fe65, does not translocate to the nucleus. In addition, APLP1 predominantly localizes to the plasma membrane, whereas APP and APLP2 are detected in vesicular structures. APLP1 also demonstrates a much slower turnover of the full-length protein compared to APP and APLP2. We further show that the ICDs of all APP family members are degraded by the proteasome and that the N-terminal amino acids of ICDs determine ICD degradation rate. Together, our results suggest that different nuclear signaling capabilities of APP family members are due to different rates of full-length protein processing and ICD proteasomal degradation. Our results provide evidence in support of a common nuclear signaling function for APP and APLP2 that is absent in APLP1, but suggest that APLP1 has a regulatory role in the nuclear translocation of APP family ICDs due to the sequestration of Fe65.

A Demonstration of Concrete Structural Health Monitoring Framework for Degradation due to Alkali-Silica Reaction

Energy Technology Data Exchange (ETDEWEB)

Mahadevan, Sankaran [Idaho National Lab. (INL), Idaho Falls, ID (United States); Agarwal, Vivek [Idaho National Lab. (INL), Idaho Falls, ID (United States); Neal, Kyle [Idaho National Lab. (INL), Idaho Falls, ID (United States); Nath, Paromita [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bao, Yanqing [Idaho National Lab. (INL), Idaho Falls, ID (United States); Cai, Guowei [Idaho National Lab. (INL), Idaho Falls, ID (United States); Orme, Peter [Idaho National Lab. (INL), Idaho Falls, ID (United States); Adams, Douglas [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kosson, David [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2016-04-01

Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high-confidence actionable information regarding structural integrity that supports operational and maintenance decisions. This ongoing research project is seeking to develop a probabilistic framework for health diagnosis and prognosis of aging concrete structures in a nuclear power plant that is subjected to physical, chemical, environment, and mechanical degradation. The proposed framework consists of four elements: monitoring, data analytics, uncertainty quantification and prognosis. This report focuses on degradation caused by ASR (alkali-silica reaction). Controlled specimens were prepared to develop accelerated ASR degradation. Different monitoring techniques – thermography, digital image correlation (DIC), mechanical deformation measurements, nonlinear impact resonance acoustic spectroscopy (NIRAS), and vibro-acoustic modulation (VAM) -- were used to detect the damage caused by ASR. Heterogeneous data from the multiple techniques was used for damage diagnosis and prognosis, and quantification of the associated uncertainty using a Bayesian network approach. Additionally, MapReduce technique has been demonstrated with synthetic data. This technique can be used in future to handle large amounts of observation data obtained from the online monitoring of realistic structures.

Classification of structural component and degradation mechanisms for containment systems

International Nuclear Information System (INIS)

Judge, R.C.B.

1994-01-01

UK licence requirements for operation of nuclear power plants is dependent, inter alia, upon the licensee making and implementing adequate arrangements for the regular and systematic examination, inspection, maintenance and testing of all plant which may affect safety (Licence Condition 28). Similarly, the US NRC's Maintenance Rule (published in 10CFR50.65) specifies that a maintenance programme should be developed for plant systems, structures and components determined to be sensitive to ageing which will be used for the balance of the current (and, if relevant, extended) operating licence period. Against this background, the plant operators are seeking to minimise operating and maintenance costs and to enhance plant availability. This leads to a need to optimise the plant inspection and monitoring regimes whilst meeting regulatory requirements. In this paper, a conceptual framework for classifying civil structures and significant ageing mechanisms is described. This provides a systematic approach to making quantitative assessments of the likelihood and of potential degradation mechanisms and forms a consistent framework and a logical basis for prioritising inspection and maintenance schedules. The proposed method is analogous to a fault tree assessment, in which the likelihood of degradation due to a specific mechanism is considered as an event. The structures are considered in terms of their subcomponents. For each subcomponent, the value assigned to the likelihood of degradation is progressively reduced by a sequence of factors which make allowance for the structural and safety significance of any degradation and for the potential for timely detection of any degradation. Illustrative values for these factors are quoted in the text; it is recommended that these values are reviewed following a trial application of the method. (author)

Inhibition of Prenylation Promotes Caspase 3 Activation, Lamin B Degradation and Loss in Metabolic Cell Viability in Pancreatic β-Cells

Directory of Open Access Journals (Sweden)

Khadija G. Syeda

2017-10-01

Full Text Available Background/Aims: Lamins are intermediate filament proteins that constitute the main components of the lamina underlying the inner-nuclear membrane and serve to organize chromatin. Lamins (e.g., lamin B undergo posttranslational modifications (e.g., isoprenylation at their C-terminal cysteine residues. Such modifications are thought to render optimal association of lamins with the nuclear envelop. Using human islets, rodent islets, and INS-1 832/13 cells, we recently reported significant metabolic defects under glucotoxic and endoplasmic reticulum (ER stress conditions, including caspase 3 activation and lamin B degradation. The current study is aimed at further understanding the regulatory roles of protein prenylation in the induction of the aforestated metabolic defects. Methods: Subcellular phase partitioning assay was done using Triton X-114. Cell morphology and metabolic cell viability assays were carried out using standard methodologies. Results: We report that exposure of pancreatic β-cells to Simvastatin, an inhibitor of mevalonic acid (MVA biosynthesis, and its downstream isoprenoid derivatives, or FTI-277, an inhibitor of farnesyltransferase that mediates farnesylation of lamins, leads to activation of caspase 3 and lamin B degradation. Furthermore, Simvastatin-treatment increased activation of p38MAPK (a stress kinase and inhibited ERK1/2 (regulator of cell proliferation. Inhibition of farnesylation also resulted in the release of degraded lamin B into the cytosolic fraction and promoted loss in metabolic cell viability. Conclusion: Based on these findings we conclude that protein prenylation plays key roles in islet β-cell function. These findings affirm further support to the hypothesis that defects in prenylation pathway induce caspase-3 activation and nuclear lamin degradation in pancreatic β-cells under the duress of metabolic stress (e.g., glucotoxicity.

LearnSafe. Learning organisations for nuclear safety

International Nuclear Information System (INIS)

Wahlstroem, B.; Kettunen, J.; Reiman, T.

2005-03-01

The nuclear power industry is currently undergoing a period of major change, which has brought with it a number of challenges. These changes have forced the nuclear power plants to initiate their own processes of change in order to adapt to the new situation. This adaptation must not compromise safety at any time, but during a rapid process of change there is a danger that minor problems may trigger a chain of events leading to a degraded safety. Organisational learning has been identified as an important component in ensuring the continued safety and efficiency of nuclear organisations. In response to these challenges a project LearnSafe 'Learning organisations for nuclear safety' was set up and funded by the European Community under the 5th Euratom Framework Programme. The present report gives an account of the LearnSafe project and its major results. (orig.)

A thermo-degradable hydrogel with light-tunable degradation and drug release.

Science.gov (United States)

Hu, Jingjing; Chen, Yihua; Li, Yunqi; Zhou, Zhengjie; Cheng, Yiyun

2017-01-01

The development of thermo-degradable hydrogels is of great importance in drug delivery. However, it still remains a huge challenge to prepare thermo-degradable hydrogels with inherent degradation, reproducible, repeated and tunable dosing. Here, we reported a thermo-degradable hydrogel that is rapidly degraded above 44 °C by a facile chemistry. Besides thermo-degradability, the hydrogel also undergoes rapid photolysis with ultraviolet light. By embedding photothermal nanoparticles or upconversion nanoparticles into the gel, it can release the entrapped cargoes such as dyes, enzymes and anticancer drugs in an on-demand and dose-tunable fashion upon near-infrared light exposure. The smart hydrogel works well both in vitro and in vivo without involving sophisticated syntheses, and is well suited for clinical cancer therapy due to the high transparency and non-invasiveness features of near-infrared light. Copyright © 2016 Elsevier Ltd. All rights reserved.

Organic matter degradation in Chilean sediments - following nature's own degradation experiment

DEFF Research Database (Denmark)

Langerhuus, Alice Thoft; Niggemann, Jutta; Lomstein, Bente Aagaard

ORGANIC MATTER DEGRADATION IN CHILEAN SEDIMENTS – FOLLOWING NATURE’S OWN DEGRADATION EXPERIMENT Degradation of sedimentary organic matter was studied at two stations from the shelf of the Chilean upwelling region. Sediment cores were taken at 1200 m and 800 m water depth and were 4.5 m and 7.5 m...... in length, respectively. The objective of this study was to assess the degradability of the organic matter from the sediment surface to the deep sediments. This was done by analysing amino acids (both L- and D-isomers) and amino sugars in the sediment cores, covering a timescale of 15.000 years. Diagenetic...... indicators (percentage of carbon and nitrogen present as amino acid carbon and nitrogen, the ratio between a protein precursor and its non-protein degradation product and the percentage of D-amino acids) revealed ongoing degradation in these sediments, indicating that microorganisms were still active in 15...

Meso-scale magnetic signatures for nuclear reactor steel irradiation embrittlement monitoring

Energy Technology Data Exchange (ETDEWEB)

Suter, J. D., E-mail: pradeep.ramuhalli@pnnl.gov; Ramuhalli, P., E-mail: pradeep.ramuhalli@pnnl.gov; Hu, S.; Li, Y.; Jiang, W.; Edwards, D. J.; Schemer-Kohrn, A. L.; Johnson, B. R. [Pacific Northwest National Laboratory, 902 Battelle Blvd, Richland, WA 99352 (United States); McCloy, J. S., E-mail: john.mccloy@wsu.edu; Xu, K., E-mail: john.mccloy@wsu.edu [Washington State University, PO Box 642920, Pullman, WA 99164 (United States)

2015-03-31

Verifying the structural integrity of passive components in light water and advanced reactors will be necessary to ensure safe, long-term operations of the existing U.S. nuclear fleet. This objective can be achieved through nondestructive condition monitoring techniques, which can be integrated with plant operations to quantify the “state of health” of structural materials in real-time. While nondestructive methods for monitoring many classes of degradation (such as fatigue or stress corrosion cracking) are relatively advanced, this is not the case for degradation caused by irradiation. The development of nondestructive evaluation technologies for these types of degradation will require advanced materials characterization techniques and tools that enable comprehensive understanding of nuclear reactor material microstructural and behavioral changes under extreme operating environments. Irradiation-induced degradation of reactor steels causes changes in their microstructure that impacts their micro-magnetic properties. In this paper, we describe preliminary results of integrating advanced material characterization techniques with meso-scale computational models. In the future, this will help to provide an interpretive understanding of the state of degradation in structural materials. Microstructural data are presented from monocrystalline Fe and are correlated with variable-field magnetic force microscopy and micro-magnetic measurements. Ongoing research is focused on extending the measurements and models on thin films to gain insights into the structural state of irradiated materials and the resulting impact on magnetic properties. Preliminary conclusions from these correlations are presented, and next steps described.

Modeling rates of DOC degradation using DOM composition and hydroclimatic variables

Science.gov (United States)

Moody, C. S.; Worrall, F.

2017-05-01

The fluvial fluxes of dissolved organic carbon (DOC) from peatlands form an important part of that ecosystem's carbon cycle, contributing approximately 35% of the overall peatland carbon budget. The in-stream processes acting on the DOC, such as photodegradation and biodegradation, can lead to DOC loss and thus contribute CO2 to the atmosphere. The aim of this study was to understand what controls the rates of DOC degradation. Water samples from a headwater, peat-covered catchment, were collected over a 23 month period and analyzed for the DOC degradation rate and dissolved organic matter (DOM) composition in the context of hydroclimatic monitoring. Measures of DOM composition included 13C solid-state nuclear magnetic resonance spectroscopy, bomb calorimetry, and elemental analysis. Regression analysis showed that there was a significant role for the composition of the DOM in controlling degradation with degradation rates significantly increasing with the proportion of aldehyde and carboxylic acid functional groups but decreasing with the proportion of N-alkyl functional groups. The highest rates of DOC degradation occurred when aldehyde functionality was at its greatest and this occurred on the recession limb of storm hydrographs. Including this knowledge into models of fluvial carbon fate for an 818 km2 catchment gave an annual average DOC removal rate of 67% and 50% for total organic carbon, slightly lower than previously predicted. The compositional controls suggest that DOM is primarily being used as a ready energy source to the aquatic ecosystem rather than as a nutrient source.

Sirtuin 6 prevents matrix degradation through inhibition of the NF-κB pathway in intervertebral disc degeneration

Energy Technology Data Exchange (ETDEWEB)

Kang, Liang [Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China); Hu, Jia [Department of Nuclear Medicine, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China); Weng, Yuxiong [Department of Hand Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China); Jia, Jie [Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China); Zhang, Yukun, E-mail: zhangyukuncom@126.com [Department of Orthopaedics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022 (China)

2017-03-15

Intervertebral disc degeneration (IDD) is marked by imbalanced metabolism of the extracellular matrix (ECM) in the nucleus pulposus (NP) of intervertebral discs. This study aimed to determine whether sirtuin 6 (SIRT6), a member of the sirtuin family of nicotinamide adenine dinucleotide-dependent deacetylases, protects the NP from ECM degradation in IDD. Our study showed that expression of SIRT6 markedly decreased during IDD progression. Overexpression of wild-type SIRT6, but not a catalytically inactive mutant, prevented IL-1β-induced NP ECM degradation. SIRT6 depletion by RNA interference in NP cells caused ECM degradation. Moreover, SIRT6 physically interacted with nuclear factor-κB (NF-κB) catalytic subunit p65, transcriptional activity of which was significantly suppressed by SIRT6 overexpression. These results suggest that SIRT6 prevented NP ECM degradation in vitro via inhibiting NF-κB-dependent transcriptional activity and that this effect depended on its deacetylase activity. - Highlights: • SIRT6 expression is decreased in degenerative nucleus pulposus (NP) tissues. • SIRT6 overexpression lowers IL-1β-induced matrix degradation of NP. • SIRT6 inhibition induces matrix degradation of NP. • SIRT6 prevents matrix degradation of NP via the NF-κB signaling pathway.

Sirtuin 6 prevents matrix degradation through inhibition of the NF-κB pathway in intervertebral disc degeneration

International Nuclear Information System (INIS)

Kang, Liang; Hu, Jia; Weng, Yuxiong; Jia, Jie; Zhang, Yukun

2017-01-01

Intervertebral disc degeneration (IDD) is marked by imbalanced metabolism of the extracellular matrix (ECM) in the nucleus pulposus (NP) of intervertebral discs. This study aimed to determine whether sirtuin 6 (SIRT6), a member of the sirtuin family of nicotinamide adenine dinucleotide-dependent deacetylases, protects the NP from ECM degradation in IDD. Our study showed that expression of SIRT6 markedly decreased during IDD progression. Overexpression of wild-type SIRT6, but not a catalytically inactive mutant, prevented IL-1β-induced NP ECM degradation. SIRT6 depletion by RNA interference in NP cells caused ECM degradation. Moreover, SIRT6 physically interacted with nuclear factor-κB (NF-κB) catalytic subunit p65, transcriptional activity of which was significantly suppressed by SIRT6 overexpression. These results suggest that SIRT6 prevented NP ECM degradation in vitro via inhibiting NF-κB-dependent transcriptional activity and that this effect depended on its deacetylase activity. - Highlights: • SIRT6 expression is decreased in degenerative nucleus pulposus (NP) tissues. • SIRT6 overexpression lowers IL-1β-induced matrix degradation of NP. • SIRT6 inhibition induces matrix degradation of NP. • SIRT6 prevents matrix degradation of NP via the NF-κB signaling pathway.

Nuclear plant aging research - an overview (electrical and mechanical components)

International Nuclear Information System (INIS)

Vora, J.P.

1985-01-01

As the operating nuclear power plants advance in age there must be a conscious national and international effort to understand the influence and safety implications of aging and service wear of components and structures in nuclear power plants and develop measures which are practical and cost effective for timely mitigation of aging degradation that could significantly affect plant safety. The Office of Nuclear Regulatory Research has, therefore, initiated a multi-year, multi-disciplinary program on Nuclear Plant Aging Research (NPAR). The overall goals identified for the program are as follows: 1) to identify and characterize aging and service wear effects associated with electrical and mechanical components, interfaces, and systems whose failure could impair plant safety; 2) to identify and recommend methods of inspection, surveillance and condition monitoring of electrical and mechanical components and systems which will be effective in detecting significant aging effects prior to loss of safety function so that timely maintenance and repair or replacement can be implemented; and, 3) to identify and recommend acceptable maintenance practices which can be undertaken to mitigate the effects of aging and to diminish the rate and extent of degradation caused by aging and service wear. The specific research activities to be implemented to achieve these goals are described

Seismic Fragility Analysis of a Condensate Storage Tank with Age-Related Degradations

Energy Technology Data Exchange (ETDEWEB)

Nie, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Braverman, J. [Brookhaven National Lab. (BNL), Upton, NY (United States); Hofmayer, C [Brookhaven National Lab. (BNL), Upton, NY (United States); Choun, Y-S [Brookhaven National Lab. (BNL), Upton, NY (United States); Kim, MK [Brookhaven National Lab. (BNL), Upton, NY (United States); Choi, I-K [Brookhaven National Lab. (BNL), Upton, NY (United States)

2011-04-01

The Korea Atomic Energy Research Institute (KAERI) is conducting a five-year research project to develop a realistic seismic risk evaluation system which includes the consideration of aging of structures and components in nuclear power plants (NPPs). The KAERI research project includes three specific areas that are essential to seismic probabilistic risk assessment (PRA): (1) probabilistic seismic hazard analysis, (2) seismic fragility analysis including the effects of aging, and (3) a plant seismic risk analysis. Since 2007, Brookhaven National Laboratory (BNL) has entered into a collaboration agreement with KAERI to support its development of seismic capability evaluation technology for degraded structures and components. The collaborative research effort is intended to continue over a five year period. The goal of this collaboration endeavor is to assist KAERI to develop seismic fragility analysis methods that consider the potential effects of age-related degradation of structures, systems, and components (SSCs). The research results of this multi-year collaboration will be utilized as input to seismic PRAs. This report describes the research effort performed by BNL for the Year 4 scope of work. This report was developed as an update to the Year 3 report by incorporating a major supplement to the Year 3 fragility analysis. In the Year 4 research scope, an additional study was carried out to consider an additional degradation scenario, in which the three basic degradation scenarios, i.e., degraded tank shell, degraded anchor bolts, and cracked anchorage concrete, are combined in a non-perfect correlation manner. A representative operational water level is used for this effort. Building on the same CDFM procedure implemented for the Year 3 Tasks, a simulation method was applied using optimum Latin Hypercube samples to characterize the deterioration behavior of the fragility capacity as a function of age-related degradations. The results are summarized in Section 5

Kinetics of the degradation of sulfur mustard on ambient and moist concrete

Energy Technology Data Exchange (ETDEWEB)

Brevett, Carol A.S. [SAIC, Gunpowder Branch, P.O. Box 68, APG, MD 21010-0068 (United States)], E-mail: carol.brevett@us.army.mil; Sumpter, Kenneth B. [U.S. Army Edgewood Chemical Biological Center, 5183 Blackhawk Road, Aberdeen Proving Ground, MD 21010-5424 (United States); Nickol, Robert G. [SAIC, Gunpowder Branch, P.O. Box 68, APG, MD 21010-0068 (United States)

2009-02-15

The rate of degradation of the chemical warfare agent sulfur mustard, bis(2-chloroethyl) sulfide, was measured on ambient and moist concrete using {sup 13}C Solid State Magic Angle Spinning Nuclear Magnetic Resonance (SSMAS NMR). Three samples of concrete made by the same formulation, but differing in age and alkalinity were used. The sulfur mustard eventually degraded to thiodiglycol and 1,4-oxathiane via the intermediate sulfonium ions CH-TG, H-TG, H-2TG and O(CH{sub 2}CH{sub 2}){sub 2}S{sup +}CH{sub 2}CH{sub 2}OH on all of the concrete samples, and in addition formed 8-31% vinyl moieties on the newer, more alkaline concrete samples. This is the first observation of the formation of O(CH{sub 2}CH{sub 2}){sub 2}S{sup +}CH{sub 2}CH{sub 2}OH on a solid substrate. The addition of 2-chloroethanol to concrete on which mustard had fully degraded to thiodiglycol and 1,4-oxathiane resulted in the formation of O(CH{sub 2}CH{sub 2}){sub 2}S{sup +}CH{sub 2}CH{sub 2}OH, thus demonstrating the reversibility of sulfur mustard degradation pathways. The sulfur mustard degradation half-lives on ambient concrete at 22 deg. C ranged from 3.5 to 54 weeks. When the substrates were moistened, the degradation half-lives at 22 deg. C ranged from 75 to 350 h. The degradation of sulfur mustard occurred more quickly at elevated temperatures and with added water. The non-volatile toxic sulfonium ions persisted for months to years on concrete at 22 deg. C and weeks to months on concrete at 35 deg. C, before decomposing to the relatively non-toxic compounds thiodiglycol and 1,4-oxathiane.

Ubiquitination is absolutely required for the degradation of hypoxia-inducible factor--1 alpha protein in hypoxic conditions.

Science.gov (United States)

Wang, Ronghai; Zhang, Ping; Li, Jinhang; Guan, Hongzai; Shi, Guangjun

2016-01-29

The hypoxia-inducible factor (HIF) is recognized as the master regulator of hypoxia response. HIF-α subunits expression are tightly regulated. In this study, our data show that ts20 cells still expressed detectable E1 protein even at 39.5° C for 12 h, and complete depletion of E1 protein expression at 39.5° C by siRNA enhanced HIF-1α and P53 protein expression. Further inhibition of E1 at 39.5 °C by siRNA, or E1 inhibitor Ube1-41 completely blocked HIF-1α degradation. Moreover, immunoprecipitations of co-transfection of HA-ubiquitin and FLAG-HIF-1α plasmids directly confirmed the involvement of ubiquitin in the hypoxic degradation of HIF-1α. Additionally, hypoxic HIF-1 α degradation is independent of HAF, RACK1, sumoylation or nuclear/cytoplasmic localization. Taken together, our data suggest that constitutive HIF-1α protein degradation in hypoxia is absolutely ubiquitination-dependent, and unidentified E3 ligase may exist for this degradation pathway. Copyright © 2016 Elsevier Inc. All rights reserved.

Preliminary degradation process study of infectious biological waste in a 5 k W thermal plasma equipment

International Nuclear Information System (INIS)

Xochihua S M, M.C.

1997-01-01

This work is a preliminary study of infectious biological waste degradation process by thermal plasma and was made in Thermal Plasma Applications Laboratory of Environmental Studies Department of the National Institute of Nuclear Research (ININ). Infectious biological waste degradation process is realized by using samples such polyethylene, cotton, glass, etc., but the present study scope is to analyze polyethylene degradation process with mass and energy balances involved. Degradation method is realized as follow: a polyethylene sample is put in an appropriated crucible localized inside a pyrolysis reactor chamber, the plasma jet is projected to the sample, by the pyrolysis phenomena the sample is degraded into its constitutive particles: carbon and hydrogen. Air was utilized as a recombination gas in order to obtain the higher percent of CO 2 if amount of O 2 is greater in the recombination gas, the CO generation is reduced. The effluent gases of exhaust pyrolysis reactor through are passed through a heat exchanger to get cooled gases, the temperature water used is 15 Centigrade degrees. Finally the gases was tried into absorption tower with water as an absorbent fluid. Thermal plasma degradation process is a very promising technology, but is necessary to develop engineering process area to avail all advantages of thermal plasma. (Author)

NAD(P)H quinone oxidoreductase 1 inhibits the proteasomal degradation of homocysteine-induced endoplasmic reticulum protein

Energy Technology Data Exchange (ETDEWEB)

Maeda, Tomoji, E-mail: t-maeda@nichiyaku.ac.jp [Department of Neuroscience, School of Pharmacy, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba-Cho, Shiwagun, Iwate, 028-3603 (Japan); Tanabe-Fujimura, Chiaki; Fujita, Yu; Abe, Chihiro; Nanakida, Yoshino; Zou, Kun; Liu, Junjun; Liu, Shuyu [Department of Neuroscience, School of Pharmacy, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba-Cho, Shiwagun, Iwate, 028-3603 (Japan); Nakajima, Toshihiro [Institute of Medical Science, Tokyo Medical University, 6-1-1 Shinjyuku, Shinjyuku, Tokyo, Tokyo, 160-8402 (Japan); Komano, Hiroto, E-mail: hkomano@iwate-med.ac.jp [Department of Neuroscience, School of Pharmacy, Iwate Medical University, 2-1-1 Nishitokuta, Yahaba-Cho, Shiwagun, Iwate, 028-3603 (Japan)

2016-05-13

Homocysteine-induced endoplasmic reticulum (ER) protein (Herp) is an ER stress-inducible key regulatory component of ER-associated degradation (ERAD) that has been implicated in insulin hypersecretion in diabetic mouse models. Herp expression is tightly regulated. Additionally, Herp is a highly labile protein and interacts with various proteins, which are characteristic features of ubiquitinated protein. Previously, we reported that ubiquitination is not required for Herp degradation. In addition, we found that the lysine residues of Herp (which are ubiquitinated by E3 ubiquitin ligase) are not sufficient for regulation of Herp degradation. In this study, we found that NAD(P)H quinone oxidoreductase 1 (NQO1)-mediated targeting of Herp to the proteasome was involved in Herp degradation. In addition, we found that Herp protein levels were markedly elevated in synoviolin-null cells. The E3 ubiquitin ligase synoviolin is a central component of ERAD and is involved in the degradation of nuclear factor E2-related factor-2 (Nrf2), which regulates cellular reactive oxygen species. Additionally, NQO1 is a target of Nrf2. Thus, our findings indicated that NQO1 could stabilize Herp protein expression via indirect regulation of synoviolin. -- Highlights: •Herp interacts with NQO1. •NQO1 regulates Herp degradation.

NAD(P)H quinone oxidoreductase 1 inhibits the proteasomal degradation of homocysteine-induced endoplasmic reticulum protein

International Nuclear Information System (INIS)

Maeda, Tomoji; Tanabe-Fujimura, Chiaki; Fujita, Yu; Abe, Chihiro; Nanakida, Yoshino; Zou, Kun; Liu, Junjun; Liu, Shuyu; Nakajima, Toshihiro; Komano, Hiroto

2016-01-01

Homocysteine-induced endoplasmic reticulum (ER) protein (Herp) is an ER stress-inducible key regulatory component of ER-associated degradation (ERAD) that has been implicated in insulin hypersecretion in diabetic mouse models. Herp expression is tightly regulated. Additionally, Herp is a highly labile protein and interacts with various proteins, which are characteristic features of ubiquitinated protein. Previously, we reported that ubiquitination is not required for Herp degradation. In addition, we found that the lysine residues of Herp (which are ubiquitinated by E3 ubiquitin ligase) are not sufficient for regulation of Herp degradation. In this study, we found that NAD(P)H quinone oxidoreductase 1 (NQO1)-mediated targeting of Herp to the proteasome was involved in Herp degradation. In addition, we found that Herp protein levels were markedly elevated in synoviolin-null cells. The E3 ubiquitin ligase synoviolin is a central component of ERAD and is involved in the degradation of nuclear factor E2-related factor-2 (Nrf2), which regulates cellular reactive oxygen species. Additionally, NQO1 is a target of Nrf2. Thus, our findings indicated that NQO1 could stabilize Herp protein expression via indirect regulation of synoviolin. -- Highlights: •Herp interacts with NQO1. •NQO1 regulates Herp degradation.

In-Operation Inspection Technology development. Development of the degradation prediction technique

International Nuclear Information System (INIS)

Nakamuta, Yasushi; Miyoshi, Toshiaki; O'shima, Eiji

1999-01-01

As In-Operation Inspection Technology (IOI) , we selected primary loop recirculation (PLR) pump, sea water pump, small diameter pipe branch in the steam generator (SG) room and motor driven valve for the typical component of the nuclear power plant, and we are developing the technology which can forecast the residual life of parts in the plan until FY2000. With respect to PLR pump and sea water pump, technical procedure for predicting the propagation of bearing wear, under the combined effect of several degradation conditions of each pump during the plant operation are under development. With respect to pipe branch, we are developing the non-contact laser sensors, and we are constructing the system which forecasts high cycle fatigue in the root of pipe branch by monitoring the vibration of pipe branch. With respect to motor driven valve, technical procedure for predicting the thermal degradation of gaskets and gland packing, technical procedure for predicting the stem nut wear and wear of hunging portion of valve disc, and technical procedure for detecting the degradation of driving parts, without disassembling the motor driven valve, are under development. (author)

Proactive Management of Materials Degradation - A Review of Principles and Programs

Energy Technology Data Exchange (ETDEWEB)

Bond, Leonard J.; Doctor, Steven R.; Taylor, Theodore T.

2008-08-28

The U.S. Nuclear Regulatory Commission (NRC) has undertaken a program to lay the technical foundation for defining proactive actions so that future degradation of materials in light water reactors (LWRs) is limited and, thereby, does not diminish either the integrity of important LWR components or the safety of operating plants. This technical letter report was prepared by staff at Pacific Northwest National Laboratory in support of the NRC Proactive Management of Materials Degradation (PMMD) program and relies heavily on work that was completed by Dr. Joseph Muscara and documented in NUREG/CR-6923. This report concisely explains the basic principles of PMMD and its relationship to prognostics, provides a review of programs related to PMMD being conducted worldwide, and provides an assessment of the technical gaps in PMMD and prognostics that need to be addressed. This technical letter report is timely because the majority of the U.S. reactor fleet is applying for license renewal, and many plants are also applying for increases in power rating. Both of these changes could increase the likelihood of materials degradation and underline, therefore, the interest in proactive management in the future.

The prospective environmental impacts of Iran nuclear energy expansion

Energy Technology Data Exchange (ETDEWEB)

Beheshti, Hamed, E-mail: Beheshti@zedat.fu-berlin.de [Renewable Energy Policy Planning, Freie Universitaet Berlin BC CARE, Berlin Center for Caspian Region Energy and Environment Studies, Ihnestrasse 22, 14195 Berlin (Germany)

2011-10-15

Nuclear energy has direct impacts on the environment. Uranium mining, milling, and enrichment affect the livelihoods around and stress on the water resources. In addition, nuclear power plants consume huge amount of water and elevate the water temperature of the ambient water resources. The Iranian nuclear program has pledged for 20,000 MW of nuclear energy by 2025. The fulfillment of such ambitious target stresses the environment and increases the environmental degradation cost of the country. Iran central semi-arid area and the Persian Gulf are the major regions with high risk of impacts from the current nuclear program. - Highlights: > Fragile ecosystem of the Persian Gulf would not tolerate the ambitious nuclear programs of its coastal countries. > Water resources in Iran inland area are depleting fast due to the unsustainable development on the past. > Iranian nuclear program is going to put an additional serious stress on the water resources of the country.

The prospective environmental impacts of Iran nuclear energy expansion

International Nuclear Information System (INIS)

Beheshti, Hamed

2011-01-01

Nuclear energy has direct impacts on the environment. Uranium mining, milling, and enrichment affect the livelihoods around and stress on the water resources. In addition, nuclear power plants consume huge amount of water and elevate the water temperature of the ambient water resources. The Iranian nuclear program has pledged for 20,000 MW of nuclear energy by 2025. The fulfillment of such ambitious target stresses the environment and increases the environmental degradation cost of the country. Iran central semi-arid area and the Persian Gulf are the major regions with high risk of impacts from the current nuclear program. - Highlights: → Fragile ecosystem of the Persian Gulf would not tolerate the ambitious nuclear programs of its coastal countries. → Water resources in Iran inland area are depleting fast due to the unsustainable development on the past. → Iranian nuclear program is going to put an additional serious stress on the water resources of the country.

The RNA-binding protein Celf1 post-transcriptionally regulates p27Kip1 and Dnase2b to control fiber cell nuclear degradation in lens development.

Directory of Open Access Journals (Sweden)

Archana D Siddam

2018-03-01

Full Text Available Opacification of the ocular lens, termed cataract, is a common cause of blindness. To become transparent, lens fiber cells undergo degradation of their organelles, including their nuclei, presenting a fundamental question: does signaling/transcription sufficiently explain differentiation of cells progressing toward compromised transcriptional potential? We report that a conserved RNA-binding protein Celf1 post-transcriptionally controls key genes to regulate lens fiber cell differentiation. Celf1-targeted knockout mice and celf1-knockdown zebrafish and Xenopus morphants have severe eye defects/cataract. Celf1 spatiotemporally down-regulates the cyclin-dependent kinase (Cdk inhibitor p27Kip1 by interacting with its 5' UTR and mediating translation inhibition. Celf1 deficiency causes ectopic up-regulation of p21Cip1. Further, Celf1 directly binds to the mRNA of the nuclease Dnase2b to maintain its high levels. Together these events are necessary for Cdk1-mediated lamin A/C phosphorylation to initiate nuclear envelope breakdown and DNA degradation in fiber cells. Moreover, Celf1 controls alternative splicing of the membrane-organization factor beta-spectrin and regulates F-actin-crosslinking factor Actn2 mRNA levels, thereby controlling fiber cell morphology. Thus, we illustrate new Celf1-regulated molecular mechanisms in lens development, suggesting that post-transcriptional regulatory RNA-binding proteins have evolved conserved functions to control vertebrate oculogenesis.

The CCR4-NOT complex physically and functionally interacts with TRAMP and the nuclear exosome.

Directory of Open Access Journals (Sweden)

Nowel Azzouz

Full Text Available BACKGROUND: Ccr4-Not is a highly conserved multi-protein complex consisting in yeast of 9 subunits, including Not5 and the major yeast deadenylase Ccr4. It has been connected functionally in the nucleus to transcription by RNA polymerase II and in the cytoplasm to mRNA degradation. However, there has been no evidence so far that this complex is important for RNA degradation in the nucleus. METHODOLOGY/PRINCIPAL FINDINGS: In this work we point to a new role for the Ccr4-Not complex in nuclear RNA metabolism. We determine the importance of the Ccr4-Not complex for the levels of non-coding nuclear RNAs, such as mis-processed and polyadenylated snoRNAs, whose turnover depends upon the nuclear exosome and TRAMP. Consistently, mutation of both the Ccr4-Not complex and the nuclear exosome results in synthetic slow growth phenotypes. We demonstrate physical interactions between the Ccr4-Not complex and the exosome. First, Not5 co-purifies with the exosome. Second, several exosome subunits co-purify with the Ccr4-Not complex. Third, the Ccr4-Not complex is important for the integrity of large exosome-containing complexes. Finally, we reveal a connection between the Ccr4-Not complex and TRAMP through the association of the Mtr4 helicase with the Ccr4-Not complex and the importance of specific subunits of Ccr4-Not for the association of Mtr4 with the nuclear exosome subunit Rrp6. CONCLUSIONS/SIGNIFICANCE: We propose a model in which the Ccr4-Not complex may provide a platform contributing to dynamic interactions between the nuclear exosome and its co-factor TRAMP. Our findings connect for the first time the different players involved in nuclear and cytoplasmic RNA degradation.

Degradation of resins in EPICOR-II prefilters from Three Mile Island

International Nuclear Information System (INIS)

McConnell, J.W. Jr.; Sanders, R.D. Sr.

1986-01-01

The Low-Level Waste Data Base Development--EPICOR-II Resin/Liner Investigation Program funded by the U.S. Nuclear Regulatory Commission is investigating the chemical and physical conditions of the synthetic ion exchange resins contained in several EPICOR-II prefilters. Those prefilters were used during cleanup of contaminated water from the Three Mile Island Nuclear Power Station after the March 1979 accident. This paper summarizes results and analyses of the second sampling of resins from prefilters PF-8 and -20. Results are compared with baseline data from tests performed on unirradiated resins supplied by Epicor, Inc. to determine if degradation has occurred due to the high internal radiation dose. Results also are compared with results from tests performed on resins obtained from the first sampling of those two prefilters

Upgrading of highly elapsed degradation damage evaluation of structural materials for the light water reactors

International Nuclear Information System (INIS)

Katada, Yasuyuki; Matsushima, Shinobu; Sato, Shunji

1998-01-01

In this study, for degradation of structural materials in accompanying with highly yearly lapse of the nuclear power plants, it was an aim to elucidate interaction between material degradation and degradation under high hot water environment. And, another aims consisted in intention of expansion protection and recovery evaluation of damage due to laser processing method and so on for welded portion showing extreme material degradation and in preparation of damage region diagram based on the obtained data. In this fiscal year, on interaction between materials and environmental degradation, it was found that as stress corrosion cracking of materials hardened by shot peening shows a resemble shapes of stress-strain curve in CERT and CLRT, shapes of load-time curve were much different. On comparison of the SP material and non-processing material, as peak current showing activity of newly created surface shows no difference, re-passivation of the SP material was found to be too late. And, on recovery evaluation of material degradation damage, as it was found that constant melt depth was essential to evaluate corrosion, a condition preparation aimed for melt depth of more than 1 mm. As only small amount of bubbles were observed at molten metal part on YAG laser processing, it was found that many small bubbles scatter at thermal effect part. (G.K.)

Operation of Finnish nuclear power plants. Quarterly report, 3. quarter 1988

International Nuclear Information System (INIS)

Koponen, H.

1989-02-01

This general review of the operation of the Finnish nuclear power plants concentrates on such events and discoveries related to nuclear and radiation safety as the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as noteworthy. The report also includes a summary of the radiation safety of the personnel and the environment, as well as tabulated data on the production and load factors of the plants. In the report period, no event essentially degraded plant safety nor posed a radiation hazard to the personnel or the environment

Operation of Finnish nuclear power plants. Quarterly report, 2. quarter 1988

International Nuclear Information System (INIS)

Koponen, H.

1988-12-01

This general review of the operation of the Finnish nuclear power plants concentrates on such events and discoveries related to nuclear and radiation safety as the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as noteworthy. The report also includes a summary of the radiation safety of the personnel and the environment, as well as tabulated data on the production and load factors of the plants. In the report period, no event essentially degraded plant safety nor posed a radiation hazard to the personnel or the environement

Operation of Finnish nuclear power plants. Quarterly report 3. quarter 1987

International Nuclear Information System (INIS)

Haenninen, R.

1988-06-01

This general review of the operation of the Finnish nuclear power plants concentrates on such events and discoveries related to nuclear and radiation safety as the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as noteworthy. The report also includes a summary of the radiation safety of the personnel and the environment, as well as tabulated data on the production and load factors of the plants. In the report period, no event essentially degraded plant safety nor posed a radiation hazard to the personnel o the environment

Degradation of microbial polyesters.

Science.gov (United States)

Tokiwa, Yutaka; Calabia, Buenaventurada P

2004-08-01

Microbial polyhydroxyalkanoates (PHAs), one of the largest groups of thermoplastic polyesters are receiving much attention as biodegradable substitutes for non-degradable plastics. Poly(D-3-hydroxybutyrate) (PHB) is the most ubiquitous and most intensively studied PHA. Microorganisms degrading these polyesters are widely distributed in various environments. Although various PHB-degrading microorganisms and PHB depolymerases have been studied and characterized, there are still many groups of microorganisms and enzymes with varying properties awaiting various applications. Distributions of PHB-degrading microorganisms, factors affecting the biodegradability of PHB, and microbial and enzymatic degradation of PHB are discussed in this review. We also propose an application of a new isolated, thermophilic PHB-degrading microorganism, Streptomyces strain MG, for producing pure monomers of PHA and useful chemicals, including D-3-hydroxycarboxylic acids such as D-3-hydroxybutyric acid, by enzymatic degradation of PHB.

Profiling microbial lignocellulose degradation and utilization by emergent omics technologies.

Science.gov (United States)

Rosnow, Joshua J; Anderson, Lindsey N; Nair, Reji N; Baker, Erin S; Wright, Aaron T

2017-08-01

The use of plant materials to generate renewable biofuels and other high-value chemicals is the sustainable and preferable option, but will require considerable improvements to increase the rate and efficiency of lignocellulose depolymerization. This review highlights novel and emerging technologies that are being developed and deployed to characterize the process of lignocellulose degradation. The review will also illustrate how microbial communities deconstruct and metabolize lignocellulose by identifying the necessary genes and enzyme activities along with the reaction products. These technologies include multi-omic measurements, cell sorting and isolation, nuclear magnetic resonance spectroscopy (NMR), activity-based protein profiling, and direct measurement of enzyme activity. The recalcitrant nature of lignocellulose necessitates the need to characterize the methods microbes employ to deconstruct lignocellulose to inform new strategies on how to greatly improve biofuel conversion processes. New technologies are yielding important insights into microbial functions and strategies employed to degrade lignocellulose, providing a mechanistic blueprint in order to advance biofuel production.

Polycyclic aromatic hydrocarbons degradation by marine-derived basidiomycetes: optimization of the degradation process.

Science.gov (United States)

Vieira, Gabriela A L; Magrini, Mariana Juventina; Bonugli-Santos, Rafaella C; Rodrigues, Marili V N; Sette, Lara D

2018-05-03

Pyrene and benzo[a]pyrene (BaP) are high molecular weight polycyclic aromatic hydrocarbons (PAHs) recalcitrant to microbial attack. Although studies related to the microbial degradation of PAHs have been carried out in the last decades, little is known about degradation of these environmental pollutants by fungi from marine origin. Therefore, this study aimed to select one PAHs degrader among three marine-derived basidiomycete fungi and to study its pyrene detoxification/degradation. Marasmiellus sp. CBMAI 1062 showed higher levels of pyrene and BaP degradation and was subjected to studies related to pyrene degradation optimization using experimental design, acute toxicity, organic carbon removal (TOC), and metabolite evaluation. The experimental design resulted in an efficient pyrene degradation, reducing the experiment time while the PAH concentration applied in the assays was increased. The selected fungus was able to degrade almost 100% of pyrene (0.08mgmL -1 ) after 48h of incubation under saline condition, without generating toxic compounds and with a TOC reduction of 17%. Intermediate metabolites of pyrene degradation were identified, suggesting that the fungus degraded the compound via the cytochrome P450 system and epoxide hydrolases. These results highlight the relevance of marine-derived fungi in the field of PAH bioremediation, adding value to the blue biotechnology. Copyright © 2018. Published by Elsevier Editora Ltda.

Applications of ultrasonic phased array technique during fabrication of nuclear tubing and other components for the Indian nuclear power program

International Nuclear Information System (INIS)

Kapoor, K.

2015-01-01

Ultrasonic phased array technique has been applied in fabrication of nuclear fuel and structural at NFC. The integrity of the nuclear fuel and structural components is most crucial as they are exposed to severe environment during operation leading to rapid degradation of its properties during its lifecycle. Nuclear Fuel Complex has mandate for the fabrication of the nuclear fuel and core structurals for Indian PHWRs/BWR, sub-assemblies for the PFBR and steam generator tubing for PFBR and PHWRs which are the most critical materials for the Indian Nuclear Power program. NDE during fabrication of these materials is thus most crucial as it provides the confidence to the designer for safe operation during its lifetime. Many of these techniques have to be developed in-house to meet unique requirements of high sensitivity, resolution and shape of the components. Some of the advancements in the NDE during the fabrication include use of ultrasonic phased array which is detailed in this paper

Ageing degradation in the Gentilly-1 concrete containment building

International Nuclear Information System (INIS)

Jaffer, S.; Pentecost, S.; Angell, P.; Shenton, B.

2015-01-01

Concrete containment buildings (CCBs) are designed for a service life up to 40 years, but nuclear power plant (NPP) refurbishment can extend service life beyond 60 years. Only limited testing can be conducted on an in-service CCB. The Gentilly-1 (G-1) NPP is in a safe, sustainable shutdown state and the G-1 CCB was available for testing to determine age-related degradation that may be relevant to operating CCBs. Visual observation of the G-1 CCB helped to identify various signs of degradation. However, field testing, via concrete removal, was performed to: (i) examine reinforcing bars and concrete to determine their condition and in-situ stresses and (ii) examine condition of post-tensioned (P-T) wires. The concrete was also subjected to laboratory tests to evaluate its physical, mechanical and chemical properties such as compressive strength, carbonation depth, chloride content and presence of internal degradation. The degradation mechanisms that were clearly visible include macro- and micro-cracking, efflorescence, and weathering. The reinforcing bars in the perimeter wall and dome exposed during the program showed no evidence of active corrosion. Corrosion products were observed on the surfaces of most exposed P-T wires in the perimeter wall, but none were present on P-T wires exposed in the dome. Laboratory testing on the concrete cores extracted from the CCB revealed compressive strength in excess of the design requirements, low carbonation depths (< 10 mm) and no appreciable chlorides. Micro-cracking was observed in the samples recovered from the wall and dome. To date, the observed micro-cracking has had no apparent visible affect on the performance of the CCB concrete. (authors)

Development of a seismic damage assessment program for nuclear power plant structures

Energy Technology Data Exchange (ETDEWEB)

Koh, Hyun Moo; Cho, Yang Heui; Shin, Hyun Mok [Seoul National Univ., Seoul (Korea, Republic of)] (and others)

2001-12-15

The most part of the nuclear power plants operating currently in Korea are more than 20 years old and obviously we cannot pretend that their original performance is actually maintained. In addition, earthquake occurrences show an increasing trend all over the world, and Korea can no more be considered as a zone safe from earthquake. Therefore, need is to guarantee the safety of these power plant structures against seismic accident, to decide to maintain them operational and to obtain data relative to maintenance/repair. Such objectives can be reached by damage assessment using inelastic seismic analysis considering aging degradation. It appears to be more important particularly for the structure enclosing the nuclear reactor that must absolutely protect against any radioactive leakage. Actually, the tendency of the technical world, led by the OECD/NEA, BNL in the United States, CEA in France and IAEA, is to develop researches or programs to assess the seismic safety considering aging degradation of operating nuclear power plants. Regard to the above-mentioned international technical trend, a technology to establish inelastic seismic analysis considering aging degradation so as to assess damage level and seismic safety margin appears to be necessary. Damage assessment and prediction system to grasp in real-time the actual seismic resistance capacity and damage level by 3-dimensional graphic representations are also required.

Development of a seismic damage assessment program for nuclear power plant structures

Energy Technology Data Exchange (ETDEWEB)

Koh, Hyun Moo; Cho, Ho Hyun; Cho, Yang Hui [Seoul National Univ., Seoul (Korea, Republic of)] (and others)

2000-12-15

Some of nuclear power plants operating currently in Korea have been passed about 20 years after construction. Moreover, in the case of KORI I the service year is over 20 years, so their abilities are different from initial abilities. Also, earthquake outbreak increase, our country is not safe area for earthquake. Therefore, need is to guarantee the safety of these power plant structures against seismic accident, to decide to maintain them operational and to obtain data relative to maintenance/repair. Such objectives can be reached by damage assessment using inelastic seismic analysis considering aging degradation. It appears to be more important particularly for the structure enclosing the nuclear reactor that must absolutely protect against any radioactive leakage. Actually, the tendency of the technical world, led by the OECD/NEA, BNL in the United States, CEA in France and IAEA, is to develop researches or programs to assess the seismic safety considering aging degradation of operating nuclear power plants. Regard to the above-mentioned international technical trend, a technology to establish inelastic seismic analysis considering aging degradation so as to assess damage level and seismic safety margin appears to be necessary. Damage assessment and prediction system to grasp in real-time the actual seismic resistance capacity and damage level by 3-dimensional graphic representations are also required.

Predicting the Lifetimes of Nuclear Waste Containers

Science.gov (United States)

King, Fraser

2014-03-01

As for many aspects of the disposal of nuclear waste, the greatest challenge we have in the study of container materials is the prediction of the long-term performance over periods of tens to hundreds of thousands of years. Various methods have been used for predicting the lifetime of containers for the disposal of high-level waste or spent fuel in deep geological repositories. Both mechanical and corrosion-related failure mechanisms need to be considered, although until recently the interactions of mechanical and corrosion degradation modes have not been considered in detail. Failure from mechanical degradation modes has tended to be treated through suitable container design. In comparison, the inevitable loss of container integrity due to corrosion has been treated by developing specific corrosion models. The most important aspect, however, is to be able to justify the long-term predictions by demonstrating a mechanistic understanding of the various degradation modes.

Spectrometry of degraded neutrons with SSNTDs

International Nuclear Information System (INIS)

Gopalani, Deepak; Kumar, S.; Jodha, A.S.; Reddy, A.R.

1993-01-01

Considerable interest has grown during the last decade in the use of solid state nuclear track detectors (SSNTDs) for routine neutron monitoring and dosimetry work. In addition, using these detectors neutron spectrometry has also been undertaken by some investigators. In spectrometry the energy of neutrons was determined either from minor axis of proton tracks observed on the surface of detector or from the use of polyethylene radiators of selected thickness with varying etching time. Using this latter method in the present work fast neutron spectrometry is made. The method involves the measurement of etch induction time, thickness of removed critical layer for constant radiator thickness with varying etching time. Besides a computer programme has been developed for the calculation of neutron sensitivity at different critical removal layers. The degraded neutron spectra of 252 Cf with shield materials of different thickness but of same composition and shield materials of same thickness but of different compositions have been obtained. The study shows that SSNTD films can be used for recording the transmitted neutron spectra from different shield materials. This spectrometric capability added to the technique advantages of SSNTDs such as integrating nature and small size make them important for nuclear engineering applications. (author). 7 refs., 4 figs., 1 tab

Ageing management of nuclear power plant concrete structures - Overview and suggested research topics

International Nuclear Information System (INIS)

Naus, J.

2009-01-01

Nuclear power plant concrete structures are described and their operating experience noted. Primary considerations related to management of their ageing are noted and an indication of their status provided: degradation mechanisms, damage models, and material performance; assessment and remediation (i.e., component selection, in-service inspection, non-destructive examinations, and remedial actions); and estimation of performance at present or some future point in time (i.e., application of structural reliability theory to the design and optimisation of in-service inspection/maintenance strategies, and determination of the effects of degradation on plant risk). Several activities are identified that provide background information and data on areas of concern with respect to non-destructive examination of nuclear power plant concrete structures: inspection of thick-walled, heavily-reinforced sections; basemat; and inaccessible areas of the containment metallic pressure boundary. Topics are noted where additional research would be of benefit to ageing management of nuclear power plant concrete structures. (author)

In-situ degradation of sulphur mustard using (1R)-(-)-(camphorylsulphonyl) oxaziridine impregnated adsorbents

Energy Technology Data Exchange (ETDEWEB)

Sharma, Abha, E-mail: abha_052002@yahoo.co.in [Industrial Toxicology Research Centre, Mahatam Gandhi Marg, Lucknow, UP (India); Saxena, Amit; Singh, Beer [Defence Research and Development Establishment, Jhansi Road, Gwalior, MP (India)

2009-12-30

Bis-2-chloroethyl sulphide (sulphur mustard or HD) is an extremely toxic and persistent chemical warfare agent. For in-situ degradation of HD and its analogues (simulants), i.e., dibutyl sulphide (DBS) and ethyl 2-hydroxyethyl sulphide (HEES), different adsorbents systems loaded with (1R)-(-)-(camphorylsulphonyl) oxaziridine were prepared. Solution of sulphur mustard and its simulants was prepared in carbon tetrachloride and taken for uniform adsorption on the impregnated systems using incipient volume. Degradation kinetics monitored by GC/FID were found to be first-order. The half-life of degradation reactions for simulants was obtained in less than 30 and for HD in 120 min. From the studied kinetics it was observed that reaction was very rapid with simulants and decreased rate was found for HD. The order of reactivity of MgO/Oxa system for HD and simulants was found to be DBS > HEES > HD. Reaction products of the oxidation reaction of simulants and HD on adsorbents were extracted in dichloromethane and analysed by GC-MS. The products were found to be non-toxic sulphoxide. The objective of the study is to develop a reactive adsorbent for in-situ degradation of sulphur mustard which could be used in nuclear biological and chemical (NBC) filtration systems.

Experimental analysis of upward vertical two-phase flow in four-cusp channels simulating the conditions of a typical nuclear reactor channel, degraded by a loss of coolant accident

International Nuclear Information System (INIS)

Assad, A.C.A.

1984-01-01

The present work deals with an experimental analysis of upward vertical two-phase flow in channels with circular and four-cusp cross-sections. The latter simulates the conditions of a typical nuclear reactor channel, degraded by a loss of coolant accident. Simultaneous flow of air and water has been employed to simulate adiabatic steam-water flow. The installation of air-water separators helped eliminate instabilities during pressure-drop measurements. The gamma ray attenuation was utilized for the void fraction determination. For the four-cusp geommetry, new criteria for two-phase flow regime transitions have been determined, as well as new correlatins for pressure drop and void fraction, as function of the Lockhart-Martinelli factor and vapour mass-fraction, respectively. (Author) [pt

Speeding through cell cycle roadblocks: Nuclear cyclin D1-dependent kinase and neoplastic transformation

Directory of Open Access Journals (Sweden)

Diehl J Alan

2008-09-01

Full Text Available Abstract Mitogenic induction of cyclin D1, the allosteric regulator of CDK4/6, is a key regulatory event contributing to G1 phase progression. Following the G1/S transition, cyclin D1 activation is antagonized by GSK3β-dependent threonine-286 (Thr-286 phosphorylation, triggering nuclear export and subsequent cytoplasmic degradation mediated by the SCFFbx4-αBcrystallin E3 ubiquitin ligase. Although cyclin D1 overexpression occurs in numerous malignancies, overexpression of cyclin D1 alone is insufficient to drive transformation. In contrast, cyclin D1 mutants refractory to phosphorylation-dependent nuclear export and degradation are acutely transforming. This raises the question of whether overexpression of cyclin D1 is a significant contributor to tumorigenesis or an effect of neoplastic transformation. Significantly, recent work strongly supports a model wherein nuclear accumulation of cyclin D1-dependent kinase during S-phase is a critical event with regard to transformation. The identification of mutations within SCFFbx4-αBcrystallin ligase in primary tumors provides mechanistic insight into cyclin D1 accumulation in human cancer. Furthermore, analysis of mouse models expressing cyclin D1 mutants refractory to degradation indicate that nuclear cyclin D1/CDK4 kinase triggers DNA re-replication and genomic instability. Collectively, these new findings provide a mechanism whereby aberrations in post-translational regulation of cyclin D1 establish a cellular environment conducive to mutations that favor neoplastic growth.

Microbial degradation of low-level radioactive waste

International Nuclear Information System (INIS)

Rogers, R.D.; Hamilton, M.A.; Veeh, R.H.; McConnell, J.W. Jr.

1994-04-01

The Nuclear Regulatory Commission stipulates that disposed low-level radioactive waste (LLW) be stabilized. Because of apparent ease of use and normal structural integrity, cement has been widely used as a binder to solidify LLW. However, the resulting waste forms are sometimes susceptible to failure due to the actions of waste constituents, stress, and environment. This report reviews laboratory efforts that are being developed to address the effects of microbiologically influenced chemical attack on cement-solidified LLW. Groups of microorganisms are being employed that are capable of metabolically converting organic and inorganic substrates into organic and mineral acids. Such acids aggressively react with cement and can ultimately lead to structural failure. Results on the application of mechanisms inherent in microbially influenced degradation of cement-based material are the focus of this report. Sufficient data-validated evidence of the potential for microbially influenced deterioration of cement-solidified LLW has been developed during the course of this study. These data support the continued development of appropriate tests necessary to determine the resistance of cement-solidified LLW to microbially induced degradation that could impact the stability of the waste form. They also justify the continued effort of enumeration of the conditions necessary to support the microbiological growth and population expansion

DDB1-Mediated CRY1 Degradation Promotes FOXO1-Driven Gluconeogenesis in Liver.

Science.gov (United States)

Tong, Xin; Zhang, Deqiang; Charney, Nicholas; Jin, Ethan; VanDommelen, Kyle; Stamper, Kenneth; Gupta, Neil; Saldate, Johnny; Yin, Lei

2017-10-01

Targeted protein degradation through ubiquitination is an important step in the regulation of glucose metabolism. Here, we present evidence that the DDB1-CUL4A ubiquitin E3 ligase functions as a novel metabolic regulator that promotes FOXO1-driven hepatic gluconeogenesis. In vivo, hepatocyte-specific Ddb1 deletion leads to impaired hepatic gluconeogenesis in the mouse liver but protects mice from high-fat diet-induced hyperglycemia. Lack of Ddb1 downregulates FOXO1 protein expression and impairs FOXO1-driven gluconeogenic response. Mechanistically, we discovered that DDB1 enhances FOXO1 protein stability via degrading the circadian protein cryptochrome 1 (CRY1), a known target of DDB1 E3 ligase. In the Cry1 depletion condition, insulin fails to reduce the nuclear FOXO1 abundance and suppress gluconeogenic gene expression. Chronic depletion of Cry1 in the mouse liver not only increases FOXO1 protein but also enhances hepatic gluconeogenesis. Thus, we have identified the DDB1-mediated CRY1 degradation as an important target of insulin action on glucose homeostasis. © 2017 by the American Diabetes Association.

Framework for Structural Online Health Monitoring of Aging and Degradation of Secondary Systems due to some Aspects of Erosion

Energy Technology Data Exchange (ETDEWEB)

Gribok, Andrei [Idaho National Lab. (INL), Idaho Falls, ID (United States); Patnaik, Sobhan [Idaho National Lab. (INL), Idaho Falls, ID (United States); Williams, Christian [Idaho National Lab. (INL), Idaho Falls, ID (United States); Pattanaik, Marut [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kanakala, Raghunath [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2016-09-01

This report describes the current state of research related to critical aspects of erosion and selected aspects of degradation of secondary components in nuclear power plants. The report also proposes a framework for online health monitoring of aging and degradation of secondary components. The framework consists of an integrated multi-sensor modality system which can be used to monitor different piping configurations under different degradation conditions. The report analyses the currently known degradation mechanisms and available predictive models. Based on this analysis, the structural health monitoring framework is proposed. The Light Water Reactor Sustainability Program began to evaluate technologies that could be used to perform online monitoring of piping and other secondary system structural components in commercial NPPs. These online monitoring systems have the potential to identify when a more detailed inspection is needed using real-time measurements, rather than at a pre-determined inspection interval. This transition to condition-based, risk informed automated maintenance will contribute to a significant reduction of operations and maintenance costs that account for the majority of nuclear power generation costs. There is unanimous agreement between industry experts and academic researchers that identifying and prioritizing inspection locations in secondary piping systems (for example, in raw water piping or diesel piping) would eliminate many excessive in-service inspections. The proposed structural health monitoring framework takes aim at answering this challenge by combining long-range guided wave technologies with other monitoring techniques, which can significantly increase the inspection length and pinpoint the locations that degraded the most. More widely, the report suggests research efforts aimed at developing, validating, and deploying online corrosion monitoring techniques for complex geometries, which are pervasive in NPPs.

Framework for Structural Online Health Monitoring of Aging and Degradation of Secondary Systems due to some Aspects of Erosion

International Nuclear Information System (INIS)

Gribok, Andrei; Patnaik, Sobhan; Williams, Christian; Pattanaik, Marut; Kanakala, Raghunath

2016-01-01

This report describes the current state of research related to critical aspects of erosion and selected aspects of degradation of secondary components in nuclear power plants. The report also proposes a framework for online health monitoring of aging and degradation of secondary components. The framework consists of an integrated multi-sensor modality system which can be used to monitor different piping configurations under different degradation conditions. The report analyses the currently known degradation mechanisms and available predictive models. Based on this analysis, the structural health monitoring framework is proposed. The Light Water Reactor Sustainability Program began to evaluate technologies that could be used to perform online monitoring of piping and other secondary system structural components in commercial NPPs. These online monitoring systems have the potential to identify when a more detailed inspection is needed using real-time measurements, rather than at a pre-determined inspection interval. This transition to condition-based, risk informed automated maintenance will contribute to a significant reduction of operations and maintenance costs that account for the majority of nuclear power generation costs. There is unanimous agreement between industry experts and academic researchers that identifying and prioritizing inspection locations in secondary piping systems (for example, in raw water piping or diesel piping) would eliminate many excessive in-service inspections. The proposed structural health monitoring framework takes aim at answering this challenge by combining long-range guided wave technologies with other monitoring techniques, which can significantly increase the inspection length and pinpoint the locations that degraded the most. More widely, the report suggests research efforts aimed at developing, validating, and deploying online corrosion monitoring techniques for complex geometries, which are pervasive in NPPs.

Fenofibrate activates Nrf2 through p62-dependent Keap1 degradation

International Nuclear Information System (INIS)

Park, Jeong Su; Kang, Dong Hoon; Lee, Da Hyun; Bae, Soo Han

2015-01-01

Peroxisome proliferator-activated receptor α (PPARα) activates the β-oxidation of fatty acids in the liver. Fenofibrate is a potent agonist of PPARα and is used in the treatment of hyperlipidemia. Fenofibrate treatment often induces the production of intracellular reactive oxygen species (ROS), leading to cell death. The nuclear factor erythroid 2-related factor 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap1) pathway is an essential component of the defense mechanism against oxidative stress. However, the molecular mechanism underlying the regulation of the Nrf2-Keap1 pathway in fenofibrate-induced cell death is not known. In this study, we demonstrated that fenofibrate induces Keap1 degradation and Nrf2 activation. This fenofibrate-mediated Keap1 degradation is partly dependent on autophagy. Furthermore, fenofibrate-induced Keap1 degradation followed by Nrf2 activation is mainly mediated by p62, which functions as an adaptor protein in the autophagic pathway. Consistent with these findings, ablation of p62 increased fenofibrate-mediated apoptotic cell death associated with ROS accumulation. These results strongly suggest that p62 plays a crucial role in preventing fenofibrate-induced cell death. - Highlights: • Fenofibrate induces cell death by increasing ROS production. • The underlying defense mechanism against this effect is unknown. • Fenofibrate induces autophagy-dependent Keap1 degradation and Nrf2 activation. • This process is p62-dependent; lack of p62 enhanced fenofibrate-mediated apoptosis. • p62 plays a crucial role in preventing fenofibrate-induced cell death

Fenofibrate activates Nrf2 through p62-dependent Keap1 degradation

Energy Technology Data Exchange (ETDEWEB)

Park, Jeong Su [Severance Biomedical Science Institute (Korea, Republic of); Yonsei Biomedical Research Institute, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Kang, Dong Hoon [Department of Life Science and Ewha Research Center for Systems Biology (Korea, Republic of); The Research Center for Cell Homeostasis, Ewha Womans University, Seoul 127-750 (Korea, Republic of); Lee, Da Hyun [Severance Biomedical Science Institute (Korea, Republic of); Yonsei Biomedical Research Institute, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of); Bae, Soo Han, E-mail: soohanbae@yuhs.ac [Severance Biomedical Science Institute (Korea, Republic of); Yonsei Biomedical Research Institute, Yonsei University College of Medicine, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-752 (Korea, Republic of)

2015-09-25

Peroxisome proliferator-activated receptor α (PPARα) activates the β-oxidation of fatty acids in the liver. Fenofibrate is a potent agonist of PPARα and is used in the treatment of hyperlipidemia. Fenofibrate treatment often induces the production of intracellular reactive oxygen species (ROS), leading to cell death. The nuclear factor erythroid 2-related factor 2 (Nrf2)-Kelch-like ECH-associated protein 1 (Keap1) pathway is an essential component of the defense mechanism against oxidative stress. However, the molecular mechanism underlying the regulation of the Nrf2-Keap1 pathway in fenofibrate-induced cell death is not known. In this study, we demonstrated that fenofibrate induces Keap1 degradation and Nrf2 activation. This fenofibrate-mediated Keap1 degradation is partly dependent on autophagy. Furthermore, fenofibrate-induced Keap1 degradation followed by Nrf2 activation is mainly mediated by p62, which functions as an adaptor protein in the autophagic pathway. Consistent with these findings, ablation of p62 increased fenofibrate-mediated apoptotic cell death associated with ROS accumulation. These results strongly suggest that p62 plays a crucial role in preventing fenofibrate-induced cell death. - Highlights: • Fenofibrate induces cell death by increasing ROS production. • The underlying defense mechanism against this effect is unknown. • Fenofibrate induces autophagy-dependent Keap1 degradation and Nrf2 activation. • This process is p62-dependent; lack of p62 enhanced fenofibrate-mediated apoptosis. • p62 plays a crucial role in preventing fenofibrate-induced cell death.

Application of condition based maintenance to nuclear power plants

International Nuclear Information System (INIS)

Sonoda, Yukio; Nakano, Tomohito; Shimizu, Shunichi; Iida, Jun; Atomura, Masakazu; Abe, Masahiro

2002-01-01

Device Karte management system which supports application of condition based maintenance to nuclear power plants has been developed. The purpose of this system is to support maintenance personnel in device inspection scheduling based on operating condition monitoring and maintenance histories. There are four functions: field database, degradation estimation, inspection time decision and maintenance planning. The authors have been applying this system to dozens of devices of Onagawa Nuclear Power Station Unit No. 1 for one year. This paper represents the system concept and its application experiences. (author)

First-term Status Report for the Component Operational Experience Degradation and Ageing Programme (CODAP) - 2011-2014

International Nuclear Information System (INIS)

2015-04-01

Structural integrity of piping systems is important for plant safety and operability. In recognition of this, information on degradation and failure of piping components and systems is collected and evaluated by regulatory agencies, international organisations (e.g., OECD/NEA and IAEA) and industry organisations worldwide to provide systematic feedback to reactor regulation and research and development programmes associated with non-destructive examination (NDE) technology, in-service inspection (ISI) programmes, leak-before-break evaluations, risk-informed ISI, and probabilistic safety assessment (PSA) applications involving passive component reliability. Several OECD Member Countries have agreed to establish the OECD/NEA 'Component Operational Experience, Degradation and Ageing Programme' (CODAP) to encourage multilateral co-operation in the collection and analysis of data relating to degradation and failure of metallic piping and non-piping metallic passive components in commercial nuclear power plants. The scope of the data collection includes service-induced wall thinning, part through-wall cracks, through-wall cracks with and without active leakage, and instances of significant degradation of metallic passive components, including piping pressure boundary integrity. The Project is organised under the OECD/NEA Committee on the Safety of Nuclear Installations (CSNI). CODAP is the continuation of the 2002-2011 'OECD/NEA Pipe Failure Data Exchange Project' (OPDE) and the Stress Corrosion Cracking Working Group of the 2006-2010 'OECD/NEA SCC and Cable Ageing project' (SCAP). OPDE was formally launched in May 2002. Upon completion of the 3. Term (May 2011), the OPDE project was officially closed to be succeeded by CODAP. SCAP was enabled by a voluntary contribution from Japan. It was formally launched in June 2006 and officially closed with an international workshop held in Tokyo in May 2010. Majority of the member organizations of the

The human nuclear poly(a-binding protein promotes RNA hyperadenylation and decay.

Directory of Open Access Journals (Sweden)

Stefan M Bresson

Full Text Available Control of nuclear RNA stability is essential for proper gene expression, but the mechanisms governing RNA degradation in mammalian nuclei are poorly defined. In this study, we uncover a mammalian RNA decay pathway that depends on the nuclear poly(A-binding protein (PABPN1, the poly(A polymerases (PAPs, PAPα and PAPγ, and the exosome subunits RRP6 and DIS3. Using a targeted knockdown approach and nuclear RNA reporters, we show that PABPN1 and PAPα, redundantly with PAPγ, generate hyperadenylated decay substrates that are recognized by the exosome and degraded. Poly(A tail extension appears to be necessary for decay, as cordycepin treatment or point mutations in the PAP-stimulating domain of PABPN1 leads to the accumulation of stable transcripts with shorter poly(A tails than controls. Mechanistically, these data suggest that PABPN1-dependent promotion of PAP activity can stimulate nuclear RNA decay. Importantly, efficiently exported RNAs are unaffected by this decay pathway, supporting an mRNA quality control function for this pathway. Finally, analyses of both bulk poly(A tails and specific endogenous transcripts reveals that a subset of nuclear RNAs are hyperadenylated in a PABPN1-dependent fashion, and this hyperadenylation can be either uncoupled or coupled with decay. Our results highlight a complex relationship between PABPN1, PAPα/γ, and nuclear RNA decay, and we suggest that these activities may play broader roles in the regulation of human gene expression.

Nuclear reaction data for IBA applications to cultural heritage diagnostics

Energy Technology Data Exchange (ETDEWEB)

Maino, G.; Menapace, E. [Bologna Univ., ENEA (Italy)

2008-07-01

Main aspects are discussed concerning nuclear reaction cross-sections for PIXE and PIGE (Particle Induced Gamma-ray Emission) analyses, especially referring to cultural heritage diagnostics, within the framework of ion beam analysis (IBA) methods, also reviewing recent results from international Conferences on Nuclear Data for Science and Technology and from NEANSC meetings and IAEA initiatives on the matter.To sum up this work, it is then worth remarking the following items: IBA techniques are powerful tools to derive unique information as for corrosion, degradation and, generally, conservation conditions of materials. Careful analyses of specific systems require accurate evaluations and establishment of complete databases, in particular for stopping powers and relevant cross sections. The physical parameters to be accurately determined are, therefore, nuclear reaction cross sections of importance for NRA analysis of light elements and stopping powers and ranges of light and heavy ions in various matrices. Light elements (H, Li, B, C, N, O, etc.) play an important role as constituents of many important organic as well inorganic materials in historical and artistic objects. To a large extent these materials occur in the near-surface area of a material with altered or degraded composition.

Nuclear reaction data for IBA applications to cultural heritage diagnostics

International Nuclear Information System (INIS)

Maino, G.; Menapace, E.

2008-01-01

Main aspects are discussed concerning nuclear reaction cross-sections for PIXE and PIGE (Particle Induced Gamma-ray Emission) analyses, especially referring to cultural heritage diagnostics, within the framework of ion beam analysis (IBA) methods, also reviewing recent results from international Conferences on Nuclear Data for Science and Technology and from NEANSC meetings and IAEA initiatives on the matter.To sum up this work, it is then worth remarking the following items: IBA techniques are powerful tools to derive unique information as for corrosion, degradation and, generally, conservation conditions of materials. Careful analyses of specific systems require accurate evaluations and establishment of complete databases, in particular for stopping powers and relevant cross sections. The physical parameters to be accurately determined are, therefore, nuclear reaction cross sections of importance for NRA analysis of light elements and stopping powers and ranges of light and heavy ions in various matrices. Light elements (H, Li, B, C, N, O, etc.) play an important role as constituents of many important organic as well inorganic materials in historical and artistic objects. To a large extent these materials occur in the near-surface area of a material with altered or degraded composition

Analysis of possibilities for functional capacity for work rise of reactor fuel elements at nuclear engine regime

International Nuclear Information System (INIS)

Deryavko, I.I.; Perepelkin, I.G.; Pivovarov, O.S.; Storozhenko, A.N.; Tarasov, V.I.

2000-01-01

The principle results of carbide fuel rods testing during series of IVG.1 reactor starts up at regime simulating nuclear engine regime of nuclear moving power unit are given. Considerable degradation of initial fuel elements status increasing from start up to start up and which could resulted fail of separate technological channels is shown. Origin case of extreme degradation of fuel elements status are insufficient thermal strength of fuel elements operation in the field brittle state of sintered carbide material, Possible ways of artificial reinforce of fuel elements of low temperature sections, increasing its thermal strength up to required level

Intelligent SSCs as part of new era in nuclear field and new generation of nuclear facilities

International Nuclear Information System (INIS)

Florescu, Gheorghe; Agapi, Constantin; Panaitescu, V.; Florescu, Ioan-Bogdan

2008-01-01

Nuclear field being in a continuous process of changing and development, offers the opportunity of incorporation of many new designed SSCs and new methods and techniques of study and analysis. Due to the complex items involved in this industrial sector, the nuclear area was always a field of promoting new achievement in hardware science and technique. A major issue in the nuclear facilities is the very large number of not monitored SSCs and also the very large number of undiscovered degraded SSCs. Critical SSCs, referring both to operation and safety, is very important to be monitored. Visual contact and inspections are time and resources consuming and access is not always possible. The evolution of electronics and development of advanced data acquisition devices offers the possibility of use of such equipment to many applications. Methods of investigations of nuclear facilities operation are diverse, deterministic and probabilistic techniques are usually applied. The paper presents the main disadvantages, concerning to the possibility of rapid identification of malfunctions of actual SSCs design. A special section is dedicated to intelligent sensors and SSCs. (authors)

Thermal degradation of the vapours of organic nitrogen compounds in the presence of the air

International Nuclear Information System (INIS)

Brault, A.; Chevalier, G.; Kerfanto, M.; Loyer, H.

1983-04-01

Following a quick survey of the literature on the products originated during the thermal degradation of some organic nitrogen compounds, the experimental results obtained by applying a technique previously used for other organic compounds are presented. The compounds investigated include: methyl and ethylamines at the origin of the bad smells of many gaseous wastes, trilaurylamine and tetraethylenediamine sometimes used in nuclear facilities. Attention is brought on the emission of noxious products during thermal degradation in the presence of the air, at various temperatures, viz. either usual combustion gases such as carbon monoxide, or nitro-derivatives such as hydrogen cyanide present whatever the compound investigated when temperatures are below 850 0 C [fr

EDF specifications on nuclear grade resins

International Nuclear Information System (INIS)

Mascarenhas, Darren; Gressier, Frederic; Taunier, Stephane; Le-Calvar, Marc; Ranchoux, Gilles; Marteau, Herve; Labed, Veronique

2012-09-01

Ion exchange resins are widely used across EDF, especially within the nuclear division for the purification of water. Important applications include primary circuit, secondary circuit and effluent treatment, which require high quality nuclear grade resins to retain the dissolved species, some of which may be radioactive. There is a need for more and more efficient purification in order to decrease worker dose during maintenance but also to decrease volumes of radioactive resin waste. Resin performance is subject to several forms of degradation, including physical, chemical, thermal and radioactive, therefore appropriate resin properties have to be selected to reduce such effects. Work has been done with research institutes, manufacturers and on EDF sites to select these properties, create specifications and to continuously improve on these specifications. An interesting example of research regarding resin performance is the resin degradation under irradiation. Resins used in the CVCS circuit of EDF nuclear power plants are subject to irradiation over their lifetime. A study was carried out on the effects of total integrated doses of 0.1, 1 and 10 MGy on typically used EDF mixed bed resins in a 'mini-CVCS' apparatus to simultaneously test actual primary circuit fluid. The tests confirmed that the resins still perform efficiently after a typical CVCS radiation dose. Certain resins also need additional specifications in order to maintain the integrity of the particular circuits they are used in. Recently, EDF has updated its requirements on these high purity nuclear grade resins, produced generic doctrines for all products and materials used on site which include resins of all grades, and as a result have also updated a guide on recommended resin usage for the French fleet of reactors. An overview of the evolutions will be presented. (authors)

Nuclear facility safeguards systems modeling using discrete event simulation

International Nuclear Information System (INIS)

Engi, D.

1977-01-01

The threat of theft or dispersal of special nuclear material at a nuclear facility is treated by studying the temporal relationships between adversaries having authorized access to the facility (insiders) and safeguards system events by using a GASP IV discrete event simulation. The safeguards system events--detection, assessment, delay, communications, and neutralization--are modeled for the general insider adversary strategy which includes degradation of the safeguards system elements followed by an attempt to steal or disperse special nuclear material. The performance measure used in the analysis is the estimated probability of safeguards system success in countering the adversary based upon a predetermined set of adversary actions. An exemplary problem which includes generated results is presented for a hypothetical nuclear facility. The results illustrate representative information that could be utilized by safeguards decision-makers

Degradation Capability of n-hexadecane Degrading Bacteria from Petroleum Contaminated Soils

Directory of Open Access Journals (Sweden)

PENG Huai-li

2017-05-01

Full Text Available Samplings were performed in the petroleum contaminated soils of Dongying, Shandong Province of China. Degrading bacteria was isolated through enrichment in a Bushnel-Hass medium, with n-hexadecane as the sole source of carbon and energy. Then the isolated strains were identified by amplification of 16S rDNA gene and sequencing. The strain TZSX2 was selected as the powerful bacteria with stronger degradation ability, which was then identified as Rhodococcus hoagii genera based on the constructing results of the phylogenetic tree. The optimum temperature that allowed both high growth and efficient degradation ratio was in the scope of 28~36 ℃, and gas chromatography results showed that approximately more than 30% of n-hexadecane could be degraded in one week of incubation within the temperature range. Moreover, the strain TZSX2 was able to grow in high concentrations of n-hexadecane. The degradation rate reached 79% when the initial n-hexadecane concentration was 2 mL·L-1,while it still achieved 12% with n-hexadecane concentration of 20 mL·L-1. The optimal pH was 9 that allowed the highest growth and the greatest degradation rate of 91%. Above all, the screened strain TZSX2 showed high capabilities of alkali tolerance with excellent degradation efficiency for even high concentration of n-hexadecane, and thus it would be quite suitable for the remediation of petroleum contaminated soils especially in the extreme environment.

Managing aging in nuclear power plants: Insights from NRC's maintenance team inspection reports

International Nuclear Information System (INIS)

Fresco, A.; Subudhi, M.

1994-01-01

Age-related degradation is managed through the maintenance program of a nuclear plant. From 1988 to 1991, the Nuclear Regulatory Commission (NRC) evaluated the maintenance program of every nuclear power plant in the United States. The authors reviewed 44 out of a total of 67 of the reports issued by the NRC on these in-depth team inspections. The reports were reviewed for insights into the strengths and weaknesses of the programs as related to the need to understand and manage the effects of aging on nuclear plant structures, systems, and components. The authors' conclusions are presented. 6 refs

A strategy study on the technology development for key nuclear structural materials

International Nuclear Information System (INIS)

Hong, Jun Hwa; Jeong, Youg Hwan; Kim, Tae Kyu

2012-01-01

In order to realize the advanced long-life PWRs and new Generation-IV nuclear systems, it is pre-requisite to establish or ensure the several key materials technology. In this study, we proposed the several key needs and directions for the key materials issues. Each issue is envisioned and described below. 1) Development of innovative nuclear structural materials with extreme environment-resistance for advanced G-IV systems 2) Improvement/development of key reactor materials for advanced and long -life PWRs. 3) Development of technologies against nuclear materials aging degradation

Degradation of resins in EPICOR-II prefilters from Three Mile Island

International Nuclear Information System (INIS)

McConnell, J.W. Jr.; Johnson, D.A.

1990-01-01

The Low-Level Waste Data Base Development--EPICOR-II Resin/Liner Investigation Program funded by the U.S. Nuclear Regulatory Commission is investigating the chemical and physical conditions of the synthetic ion exchange resins contained in several EPICOR-Il prefilters. Those prefilters were used during cleanup of contaminated water from the Three Mile Island Nuclear Power Station after the March 1979 accident. This paper summarizes results and analyses of the third sampling of resins from prefilters PF-8 and -20. Results are compared with baseline data from tests performed on unirradiated resins supplied by Epicor, Inc. to determine if degradation has occurred due to the high internal radiation dose. Results also are compared with results from tests performed on resins obtained from the first and second samplings of those two prefilters. 17 refs., 4 figs., 4 tabs

Final Report Inspection of Aged/Degraded Containments Program.

Energy Technology Data Exchange (ETDEWEB)

Naus, Dan J [ORNL; Ellingwood, B R [Georgia Institute of Technology; Oland, C Barry [ORNL

2005-09-01

The Inspection of Aged/Degraded Containments Program had primary objectives of (1) understanding the significant factors relating corrosion occurrence, efficacy of inspection, and structural capacity reduction of steel containments and liners of reinforced concrete containments; (2) providing the United States Nuclear Regulatory Commission (USNRC) reviewers a means of establishing current structural capacity margins or estimating future residual structural capacity margins for steel containments, and concrete containments as limited by liner integrity; (3) providing recommendations, as appropriate, on information to be requested of licensees for guidance that could be utilized by USNRC reviewers in assessing the seriousness of reported incidences of containment degradation; and (4) providing technical assistance to the USNRC (as requested) related to concrete technology. Primary program accomplishments have included development of a degradation assessment methodology; reviews of techniques and methods for inspection and repair of containment metallic pressure boundaries; evaluation of high-frequency acoustic imaging, magnetostrictive sensor, electromagnetic acoustic transducer, and multimode guided plate wave technologies for inspection of inaccessible regions of containment metallic pressure boundaries; development of a continuum damage mechanics-based approach for structural deterioration; establishment of a methodology for reliability-based condition assessments of steel containments and liners; and fragility assessments of steel containments with localized corrosion. In addition, data and information assembled under this program has been transferred to the technical community through review meetings and briefings, national and international conference participation, technical committee involvement, and publications of reports and journal articles. Appendix A provides a listing of program reports, papers, and publications; and Appendix B contains a listing of

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

Lehtinen, Pekka

1987-05-01

These general reviews of the operation of the Finnish nuclear power plants concentrate on such events and discoveries related to reactor and radiation safety that the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as noteworthy. The report also includes a summary of the radiation safety of the personnel and the environment, as well as tabulated data on the production and load factors of the plants. In the report period, no event essentially degraded plant safety nor posed a radiation hazard to the perssonnel or the environment. For remedying certain defects found in the administrative procedures concerning plant operation and maintenance, the Loviisa power plant was shut down for several days

Quantitative diagnosis and prognosis framework for concrete degradation due to alkali-silica reaction

Science.gov (United States)

Mahadevan, Sankaran; Neal, Kyle; Nath, Paromita; Bao, Yanqing; Cai, Guowei; Orme, Peter; Adams, Douglas; Agarwal, Vivek

2017-02-01

This research is seeking to develop a probabilistic framework for health diagnosis and prognosis of aging concrete structures in nuclear power plants that are subjected to physical, chemical, environment, and mechanical degradation. The proposed framework consists of four elements: monitoring, data analytics, uncertainty quantification, and prognosis. The current work focuses on degradation caused by ASR (alkali-silica reaction). Controlled concrete specimens with reactive aggregate are prepared to develop accelerated ASR degradation. Different monitoring techniques — infrared thermography, digital image correlation (DIC), mechanical deformation measurements, nonlinear impact resonance acoustic spectroscopy (NIRAS), and vibro-acoustic modulation (VAM) — are studied for ASR diagnosis of the specimens. Both DIC and mechanical measurements record the specimen deformation caused by ASR gel expansion. Thermography is used to compare the thermal response of pristine and damaged concrete specimens and generate a 2-D map of the damage (i.e., ASR gel and cracked area), thus facilitating localization and quantification of damage. NIRAS and VAM are two separate vibration-based techniques that detect nonlinear changes in dynamic properties caused by the damage. The diagnosis results from multiple techniques are then fused using a Bayesian network, which also helps to quantify the uncertainty in the diagnosis. Prognosis of ASR degradation is then performed based on the current state of degradation obtained from diagnosis, by using a coupled thermo-hydro-mechanical-chemical (THMC) model for ASR degradation. This comprehensive approach of monitoring, data analytics, and uncertainty-quantified diagnosis and prognosis will facilitate the development of a quantitative, risk informed framework that will support continuous assessment and risk management of structural health and performance.

EQ6 Calculations for Chemical Degradation Of N Reactor (U-Metal) Spent Nuclear Fuel Waste Packages

International Nuclear Information System (INIS)

P. Bernot

2001-01-01

The Monitored Geologic Repository (MGR) Waste Package Department of the Civilian Radioactive Waste Management System Management and Operating Contractor (CRWMS M and O) performed calculations to provide input for disposal of spent nuclear fuel (SNF) from the N Reactor, a graphite moderated reactor at the Department of Energy's (DOE) Hanford Site (ref. 1). The N Reactor core was fueled with slightly enriched (0.947 wt% and 0.947 to 1.25 wt% 235 U in Mark IV and Mark IA fuels, respectively) U-metal clad in Zircaloy-2 (Ref. 1, Sec. 3). Both types of N Reactor SNF have been considered for disposal at the proposed Yucca Mountain site. For some WPs, the outer shell and inner shell may breach (Ref. 3) allowing the influx of water. Water in the WP will moderate neutrons, increasing the likelihood of a criticality event within the WP; and the water may, in time, gradually leach the fissile components from the WP, further affecting the neutronics of the system. This study presents calculations of the long-term geochemical behavior of WPs containing two multi-canister overpacks (MCO) with either six baskets of Mark IA or five baskets of Mark IV intact N Reactor SNF rods (Ref. 1, Sec. 4) and two high-level waste (HLW) glass pour canisters (GPCs) arranged according to the codisposal concept (Ref. 4). The specific study objectives were to determine: (1) The extent to which fissile uranium will remain in the WP after corrosion/dissolution of the initial WP configuration (2) The extent to which fissile uranium will be carried out of the degraded WP by infiltrating water (such that internal criticality is no longer possible, but the possibility of external criticality may be enhanced); and (3) The nominal chemical composition for the criticality evaluations of the WP design, and to suggest the range of parametric variations for additional evaluations. The scope of this calculation, the chemical compositions (and subsequent criticality evaluations) of the simulations, is limited to

EQ6 Calculations for Chemical Degradation Of N Reactor (U-Metal) Spent Nuclear Fuel Waste Packages

Energy Technology Data Exchange (ETDEWEB)

P. Bernot

2001-02-27

The Monitored Geologic Repository (MGR) Waste Package Department of the Civilian Radioactive Waste Management System Management & Operating Contractor (CRWMS M&O) performed calculations to provide input for disposal of spent nuclear fuel (SNF) from the N Reactor, a graphite moderated reactor at the Department of Energy's (DOE) Hanford Site (ref. 1). The N Reactor core was fueled with slightly enriched (0.947 wt% and 0.947 to 1.25 wt% {sup 235}U in Mark IV and Mark IA fuels, respectively) U-metal clad in Zircaloy-2 (Ref. 1, Sec. 3). Both types of N Reactor SNF have been considered for disposal at the proposed Yucca Mountain site. For some WPs, the outer shell and inner shell may breach (Ref. 3) allowing the influx of water. Water in the WP will moderate neutrons, increasing the likelihood of a criticality event within the WP; and the water may, in time, gradually leach the fissile components from the WP, further affecting the neutronics of the system. This study presents calculations of the long-term geochemical behavior of WPs containing two multi-canister overpacks (MCO) with either six baskets of Mark IA or five baskets of Mark IV intact N Reactor SNF rods (Ref. 1, Sec. 4) and two high-level waste (HLW) glass pour canisters (GPCs) arranged according to the codisposal concept (Ref. 4). The specific study objectives were to determine: (1) The extent to which fissile uranium will remain in the WP after corrosion/dissolution of the initial WP configuration (2) The extent to which fissile uranium will be carried out of the degraded WP by infiltrating water (such that internal criticality is no longer possible, but the possibility of external criticality may be enhanced); and (3) The nominal chemical composition for the criticality evaluations of the WP design, and to suggest the range of parametric variations for additional evaluations. The scope of this calculation, the chemical compositions (and subsequent criticality evaluations) of the simulations, is limited

Differences in crystalline cellulose modification due to degradation by brown and white rot fungi.

Science.gov (United States)

Hastrup, Anne Christine Steenkjær; Howell, Caitlin; Larsen, Flemming Hofmann; Sathitsuksanoh, Noppadon; Goodell, Barry; Jellison, Jody

2012-10-01

Wood-decaying basidiomycetes are some of the most effective bioconverters of lignocellulose in nature, however the way they alter wood crystalline cellulose on a molecular level is still not well understood. To address this, we examined and compared changes in wood undergoing decay by two species of brown rot fungi, Gloeophyllum trabeum and Meruliporia incrassata, and two species of white rot fungi, Irpex lacteus and Pycnoporus sanguineus, using X-ray diffraction (XRD) and (13)C solid-state nuclear magnetic resonance (NMR) spectroscopy. The overall percent crystallinity in wood undergoing decay by M. incrassata, G. trabeum, and I. lacteus appeared to decrease according to the stage of decay, while in wood decayed by P. sanguineus the crystallinity was found to increase during some stages of degradation. This result is suggested to be potentially due to the different decay strategies employed by these fungi. The average spacing between the 200 cellulose crystal planes was significantly decreased in wood degraded by brown rot, whereas changes observed in wood degraded by the two white rot fungi examined varied according to the selectivity for lignin. The conclusions were supported by a quantitative analysis of the structural components in the wood before and during decay confirming the distinct differences observed for brown and white rot fungi. The results from this study were consistent with differences in degradation methods previously reported among fungal species, specifically more non-enzymatic degradation in brown rot versus more enzymatic degradation in white rot. Copyright © 2012 The British Mycological Society. Published by Elsevier Ltd. All rights reserved.

Nondestructive Examination (NDE) Detection and Characterization of Degradation Precursors, Technical Progress Report for FY 2012

Energy Technology Data Exchange (ETDEWEB)

Ramuhalli, P.; Meyer, R.M.; Fricke, J.M.; Prowant, M.S.; Coble, J.B.; Griffin, J.W.; Pitman, S.G.; Dahl, M.E.; Kafentzis, T.A.; Roosendaal, T.J.

2012-09-01

The overall objective of this project was to investigate the effectiveness of nondestructive examination (NDE) technology in detecting material degradation precursors by initiating and growing cracks in selected materials and using NDE methods to measure crack precursors prior to the onset of cracking. Nuclear reactor components are subject to stresses over time that are not precisely known and that make the life expectancy of components difficult to determine. To prevent future issues with the operation of these plants because of unforeseen failure of components, NDE technology is needed that can be used to identify and quantify precursors to macroscopic degradation of materials. Some of the NDE methods being researched as possible solutions to the precursor detection problem are magnetic Barkhausen noise, nonlinear ultrasonics, acoustic emission, eddy current measurements, and guided wave technology. In FY12, the objective was to complete preliminary assessment of advanced NDE techniques for sensitivity to degradation precursors, using prototypical degradation mechanisms in laboratory-scale measurements. This present document reports on the deliverable that meets the following milestone: M3LW-12OR0402143 – Report detailing an initial demonstration on samples from the crack-initiation tests will be provided (demonstrating acceleration of the work).

Nuclear Plant Aging Research (NPAR) program plan

International Nuclear Information System (INIS)

1985-07-01

The nuclear plant aging research described in this plan is intended to resolve issues related to the aging and service wear of equipment and systems at commercial reactor facilities and their possible impact on plant safety. Emphasis has been placed on identification and characterization of the mechansims of material and component degradation during service and evaluation of methods of inspection, surveillance, condition monitoring and maintenance as means of mitigating such effects. Specifically the goals of the program are as follows: (1) to identify and characterize aging and service wear effects which, if unchecked, could cause degradation of structures, components, and systems and thereby impair plant safety; (2) to identify methods of inspection, surveillance and monitoring, or of evaluating residual life of structures, components, and systems, which will assure timely detection of significant aging effects prior to loss of safety function; and (3) to evaluate the effectiveness of storage, maintenance, repair and replacement practices in mitigating the rate and extent of degradation caused by aging and service wear

Aging of nuclear station diesel generators: Evaluation of operating and expert experience: Phase 1, Study

International Nuclear Information System (INIS)

Hoopingarner, K.R.; Vause, J.W.; Dingee, D.A.; Nesbitt, J.F.

1987-08-01

Pacific Northwest Laboratory evaluated operational and expert experience pertaining to the aging degradation of diesel generators in nuclear service. The research, sponsored by the US Nuclear Regulatory Commission (NRC), identified and characterized the contribution of aging to emergency diesel generator failures. This report, Volume I, reviews diesel-generator experience to identify the systems and components most subject to aging degradation and isolates the major causes of failure that may affect future operational readiness. Evaluations show that as plants age, the percent of aging-related failures increases and failure modes change. A compilation is presented of recommended corrective actions for the failures identified. This study also includes a review of current, relevant industry programs, research, and standards. Volume II reports the results of an industry-wide workshop held on May 28 and 29, 1986 to discuss the technical issues associated with aging of nuclear service emergency diesel generators

Cometabolic Degradation of Dibenzofuran and Dibenzothiophene by a Naphthalene-Degrading Comamonas sp. JB.

Science.gov (United States)

Ji, Xiangyu; Xu, Jing; Ning, Shuxiang; Li, Nan; Tan, Liang; Shi, Shengnan

2017-12-01

Comamonas sp. JB was used to investigate the cometabolic degradation of dibenzofuran (DBF) and dibenzothiophene (DBT) with naphthalene as the primary substrate. Dehydrogenase and ATPase activity of the growing system with the presence of DBF and DBT were decreased when compared to only naphthalene in the growing system, indicating that the presence of DBF and DBT inhibited the metabolic activity of strain JB. The pathways and enzymes involved in the cometabolic degradation were tested. Examination of metabolites elucidated that strain JB cometabolically degraded DBF to 1,2-dihydroxydibenzofuran, subsequently to 2-hydroxy-4-(3'-oxo-3'H-benzofuran-2'-yliden)but-2-enoic acid, and finally to catechol. Meanwhile, strain JB cometabolically degraded DBT to 1,2-dihydroxydibenzothiophene and subsequently to the ring cleavage product. A series of naphthalene-degrading enzymes including naphthalene dioxygenase, 1,2-dihydroxynaphthalene dioxygenase, salicylaldehyde dehydrogenase, salicylate hydroxylase, and catechol 2,3-oxygenase have been detected, confirming that naphthalene was the real inducer of expression the degradation enzymes and metabolic pathways were controlled by naphthalene-degrading enzymes.

Planting on the slope of Yangjiang nuclear power plant by spraying combined materials

International Nuclear Information System (INIS)

Li Ning

2010-01-01

During the development and construction of nuclear power projects, in order to prevent ecological degradation and soil erosion of slope hazards, taking practical measures in the works or plant is particularly important. through the main high slope green field application of Yangjiang nuclear power plant, introducing mixed vegetation spraying techniques and characteristics of the construction process, for similar projects it is also a good guide. (author)

Interactions between mRNA export commitment, 3'-end quality control, and nuclear degradation

DEFF Research Database (Denmark)

Libri, Domenico; Dower, Ken; Boulay, Jocelyne

2002-01-01

Several aspects of eukaryotic mRNA processing are linked to transcription. In Saccharomyces cerevisiae, overexpression of the mRNA export factor Sub2p suppresses the growth defect of hpr1 null cells, yet the protein Hpr1p and the associated THO protein complex are implicated in transcriptional el...... results show that several classes of defective RNPs are subject to a quality control step that impedes release from transcription site foci and suggest that suboptimal messenger ribonucleoprotein assembly leads to RNA degradation by Rrp6p....

Task 1. Monitoring real time materials degradation. NRC extended In-situ and real-time Monitoring

Energy Technology Data Exchange (ETDEWEB)

Bakhtiari, Sasan [Argonne National Lab. (ANL), Argonne, IL (United States)

2012-03-01

The overall objective of this project was to perform a scoping study to identify, in concert with the nuclear industry, those sensors and techniques that have the most promising commercial viability and fill a critical inspection or monitoring need. Candidates to be considered include sensors to monitor real-time material degradation, characterize residual stress, monitor and inspect component fabrication, assess radionuclide and associated chemical species concentrations in ground water and soil, characterize fuel properties, and monitor severe accident conditions. Under Task 1—Monitoring Real-Time Materials Degradation—scoping studies were conducted to assess the feasibility of potential inspection and monitoring technologies (i.e., a combination of sensors, advanced signal processing techniques, and data analysis methods) that could be utilized in LWR and/or advanced reactor applications for continuous monitoring of degradation in-situ. The goal was to identify those techniques that appear to be the most promising, i.e., those that are closest to being both technically and commercially viable and that the nuclear industry is most likely to pursue. Current limitations and associated issues that must be overcome before commercial application of certain techniques have also been addressed.

Seismic response of base isolated auxiliary building with age related degradation

International Nuclear Information System (INIS)

Park, Jun Hee; Choun, Young Sun; Choi, In Kil

2012-01-01

The aging of an isolator affects not only the mechanical properties of the isolator but also the dynamic properties of the upper structure, such as the change in stiffness, deformation capacity, load bearing capacity, creep, and damping. Therefore, the seismic response of base isolated structures will change with time. The floor response in the base isolated nuclear power plants (NPPs) can be particularly changed because of the change in stiffness and damping for the isolator. The increased seismic response due to the aging of isolator can cause mechanical problems for many equipment located in the NPPs. Therefore, it is necessary to evaluate the seismic response of base isolated NPPs with age related degradation. In this study, the seismic responses for a base isolated auxiliary building of SHIN KORI 3 and 4 with age related degradation were investigated using a nonlinear time history analysis. Floor response spectrums (FRS) were presented with time for identifying the change in seismic demand under the aging of isolator

HIV-1 accessory proteins VPR and Vif modulate antiviral response by targeting IRF-3 for degradation

International Nuclear Information System (INIS)

Okumura, Atsushi; Alce, Tim; Lubyova, Barbora; Ezelle, Heather; Strebel, Klaus; Pitha, Paula M.

2008-01-01

The activation of IRF-3 during the early stages of viral infection is critical for the initiation of the antiviral response; however the activation of IRF-3 in HIV-1 infected cells has not yet been characterized. We demonstrate that the early steps of HIV-1 infection do not lead to the activation and nuclear translocation of IRF-3; instead, the relative levels of IRF-3 protein are decreased due to the ubiquitin-associated proteosome degradation. Addressing the molecular mechanism of this effect we show that the degradation is independent of HIV-1 replication and that virion-associated accessory proteins Vif and Vpr can independently degrade IRF-3. The null mutation of these two genes reduced the capacity of the HIV-1 virus to down modulate IRF-3 levels. The degradation was associated with Vif- and Vpr-mediated ubiquitination of IRF-3 and was independent of the activation of IRF-3. N-terminal lysine residues were shown to play a critical role in the Vif- and Vpr-mediated degradation of IRF-3. These data implicate Vif and Vpr in the disruption of the initial antiviral response and point to the need of HIV-1 to circumvent the antiviral response during the very early phase of replication

Purification of degraded TBP solvent using macroreticular anion exchange resin

International Nuclear Information System (INIS)

Kartha, P.K.S.; Kutty, P.V.E.; Janaradanan, C.; Ramanujam, A.; Dhumwad, R.K.

1989-01-01

Tri-n-butyl phosphate (TBP) diluted with a suitable diluent is commonly used for solvent extraction in Purex process for the recovery of uranium and plutonium from irradiated nuclear fuels. This solvent gets degraded due to various factors, the main degradation product being dibutyl phosphoric acid (HDBP). A solvent cleanup step is generally incorporated in the process for removing the degradation products from the used solvent. A liquid-liquid cleanup system using sodium carbonate or sodium hydroxide solution is routinely used. Considering certain advantages, like the possibility of loading the resin almost to saturation capacity and the subsequent disposal of the spent resin by incineration and the feasibility of adopting it to the process, a liquid-solid system has been tried as an alternate method, employing various available macroreticular anion exchange resins in OH - form for the sorption of HDBP from TBP. After standardizing the various conditions for the satisfactory removal of HDBP from TBP using synthetic mixtures, resins were tested with process solvent in batch contacts. The parameters studied were (1) capacity of different resins for HDBP sorption (2) influence of acidity, uranium and HDBP on the sorption behaviour of the latter (3) removal of fission products from the solvent by the resin and (4) regeneration and recycling of the resin. (author). 2 figs., 13 tabs., 17 refs

Assessment of Current Inservice Inspection and Leak Monitoring Practices for Detecting Materials Degradation in Light Water Reactors

Energy Technology Data Exchange (ETDEWEB)

Anderson, Michael T. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Simonen, Fredric A. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Muscara, Joseph [US Nuclear Regulatory Commission (NRC), Rockville, MD (United States); Doctor, Steven R. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Kupperman, David S. [Argonne National Lab. (ANL), Argonne, IL (United States)

2016-09-01

An assessment was performed to determine the effectiveness of existing inservice inspection (ISI) and leak monitoring techniques, and recommend improvements, as necessary, to the programs as currently performed for light water reactor (LWR) components. Information from nuclear power plant (NPP) aging studies and from the U. S. Nuclear Regulatory Commission’s Generic Aging Lessons Learned (GALL) report (NUREG-1801) was used to identify components that have already experienced, or are expected to experience, degradation. This report provides a discussion of the key aspects and parameters that constitute an effective ISI program and a discussion of the basis and background against which the effectiveness of the ISI and leak monitoring programs for timely detection of degradation was evaluated. Tables based on the GALL components were used to systematically guide the process, and table columns were included that contained the ISI requirements and effectiveness assessment. The information in the tables was analyzed using histograms to reduce the data and help identify any trends. The analysis shows that the overall effectiveness of the ISI programs is very similar for both boiling water reactors (BWRs) and pressurized water reactors (PWRs). The evaluations conducted as part of this research showed that many ISI programs are not effective at detecting degradation before its extent reached 75% of the component wall thickness. This work should be considered as an assessment of NDE practices at this time; however, industry and regulatory activities are currently underway that will impact future effectiveness assessments. A number of actions have been identified to improve the current ISI programs so that degradation can be more reliably detected.

The effects of aging on electrical and I ampersand C components: Results of US Nuclear Plant Aging Research

International Nuclear Information System (INIS)

Aggarwal, S.K.; Gunther, W.E.

1993-01-01

The US NRC's hardware oriented engineering research program for plant aging and degradation monitoring has achieved results in the area of electrical, control, and instrumentation (ECI) components used in nuclear power plants (NPPs). The principal goals of the program, known as the Nuclear Power Plant Aging Research (NPAR) Program, are to understand the effects of age-related degradation in NPPs and how to manage and mitigate them effectively. This paper describes how these goals have been achieved for key ECI components used in the safety systems of NPPs. The status of relevant on-going and planned research projects is also provided

The effects of aging on electrical and I ampersand C components: Results of US nuclear plant aging research

International Nuclear Information System (INIS)

Aggarwal, S.K.; Gunther, W.E.

1991-01-01

The US NRC's hardware oriented engineering research program for plant aging and degradation monitoring has achieved results in the area of electrical, control, and instrumentation (ECI) components used in nuclear power plants (NPPs). The principal goals of the program, known as the Nuclear Power Plant Aging Research (NPAR) Program, are to understand the effects of age-related degradation in NPPs and how to manage and mitigate them effectively. This paper describes how these goals have been achieved for key ECI components used in the safety systems of NPPs. The status of relevant on-going and planned research projects is also provided

Long-term Performance of PVC and CSPE Cables used in Nuclear Power Plants: the Effect of Degradation and Plasticizer migration

International Nuclear Information System (INIS)

Ekelund, Maria

2009-10-01

Enormous amounts of low voltage cables installed in a Swedish nuclear power plant are reaching their expected lifetimes. Since the cables are crucial to operational safety, it is of great importance that the actual condition of the installed cables is determined. In this study, cables based on poly(vinyl chloride) plasticized with di(2-ethylhexyl)phthalate (DEHP) were examined with respect to the degradation mechanisms responsible for the ageing of the insulation. This was achieved by studying samples that underwent accelerated ageing by different analytical methods, such as indenter modulus measurements, tensile testing, infrared spectroscopy, differential scanning calorimetry and liquid chromatography, to assess the condition of the cables. The results were unambiguous; the main deterioration mechanism differed for the jacket and the core insulation. The immediate increase in stiffness of the jacket insulation suggests that loss of plasticizer was the dominant cause for degradation. The core insulation on the other hand showed much smaller changes in the mechanical properties due to thermal ageing with an activation energy of the change in the indenter modulus matching that of the dehydrochlorination process. The electrical functionality during high-energy line break accident was correlated to the mechanical properties of the cable and this correlation was used to establish a lifetime criterion. The mechanical data showed Arrhenius temperature dependence with activation energies of 80 kJ/mol and 100 kJ/mol for the jacketing and 130 kJ/mol for the core insulation. These activation energies were used to extrapolate the lifetimes to service temperatures (20 deg C to 50 deg C). Plasticizer migration was determined as the lifetime controlling mechanism at the service temperatures. Experimental data, obtained by extraction of DEHP followed by liquid chromatography, were analysed by numerical methods to gain a better understanding of the migration. The analysis showed

Long-term Performance of PVC and CSPE Cables used in Nuclear Power Plants: the Effect of Degradation and Plasticizer migration

Energy Technology Data Exchange (ETDEWEB)

Ekelund, Maria

2009-10-15

Enormous amounts of low voltage cables installed in a Swedish nuclear power plant are reaching their expected lifetimes. Since the cables are crucial to operational safety, it is of great importance that the actual condition of the installed cables is determined. In this study, cables based on poly(vinyl chloride) plasticized with di(2-ethylhexyl)phthalate (DEHP) were examined with respect to the degradation mechanisms responsible for the ageing of the insulation. This was achieved by studying samples that underwent accelerated ageing by different analytical methods, such as indenter modulus measurements, tensile testing, infrared spectroscopy, differential scanning calorimetry and liquid chromatography, to assess the condition of the cables. The results were unambiguous; the main deterioration mechanism differed for the jacket and the core insulation. The immediate increase in stiffness of the jacket insulation suggests that loss of plasticizer was the dominant cause for degradation. The core insulation on the other hand showed much smaller changes in the mechanical properties due to thermal ageing with an activation energy of the change in the indenter modulus matching that of the dehydrochlorination process. The electrical functionality during high-energy line break accident was correlated to the mechanical properties of the cable and this correlation was used to establish a lifetime criterion. The mechanical data showed Arrhenius temperature dependence with activation energies of 80 kJ/mol and 100 kJ/mol for the jacketing and 130 kJ/mol for the core insulation. These activation energies were used to extrapolate the lifetimes to service temperatures (20 deg C to 50 deg C). Plasticizer migration was determined as the lifetime controlling mechanism at the service temperatures. Experimental data, obtained by extraction of DEHP followed by liquid chromatography, were analysed by numerical methods to gain a better understanding of the migration. The analysis showed

Intermittent degradation and schizotypy

Directory of Open Access Journals (Sweden)

Matthew W. Roché

2015-06-01

Full Text Available Intermittent degradation refers to transient detrimental disruptions in task performance. This phenomenon has been repeatedly observed in the performance data of patients with schizophrenia. Whether intermittent degradation is a feature of the liability for schizophrenia (i.e., schizotypy is an open question. Further, the specificity of intermittent degradation to schizotypy has yet to be investigated. To address these questions, 92 undergraduate participants completed a battery of self-report questionnaires assessing schizotypy and psychological state variables (e.g., anxiety, depression, and their reaction times were recorded as they did so. Intermittent degradation was defined as the number of times a subject’s reaction time for questionnaire items met or exceeded three standard deviations from his or her mean reaction time after controlling for each item’s information processing load. Intermittent degradation scores were correlated with questionnaire scores. Our results indicate that intermittent degradation is associated with total scores on measures of positive and disorganized schizotypy, but unrelated to total scores on measures of negative schizotypy and psychological state variables. Intermittent degradation is interpreted as potentially derivative of schizotypy and a candidate endophenotypic marker worthy of continued research.

CRITICALITY CALCULATION FOR THE MOST REACTIVE DEGRADED CONFIGURATIONS OF THE FFTF SNF CODISPOSAL WP CONTAINING AN INTACT IDENT-69 CONTAINER

International Nuclear Information System (INIS)

D.R. Moscalu

2002-01-01

The objective of this calculation is to perform additional degraded mode criticality evaluations of the Department of Energy's (DOE) Fast Flux Test Facility (FFTF) Spent Nuclear Fuel (SNF) codisposed in a 5-Defense High-Level Waste (5-DHLW) Waste Package (WP). The scope of this calculation is limited to the most reactive degraded configurations of the codisposal WP with an almost intact Ident-69 container (breached and flooded but otherwise non-degraded) containing intact FFTF SNF pins. The configurations have been identified in a previous analysis (CRWMS M andO 1999a) and the present evaluations include additional relevant information that was left out of the original calculations. The additional information describes the exact distribution of fissile material in each container (DOE 2002a). The effects of the changes that have been included in the baseline design of the codisposal WP (CRWMS M andO 2000) are also investigated. The calculation determines the effective neutron multiplication factor (k eff ) for selected degraded mode internal configurations of the codisposal waste package. These calculations will support the demonstration of the technical viability of the design solution adopted for disposing of MOX (FFTF) spent nuclear fuel in the potential repository. This calculation is subject to the Quality Assurance Requirements and Description (QARD) (DOE 2002b) per the activity evaluation under work package number P6212310M2 in the technical work plan TWP-MGR-MD-0000101 (BSC 2002)

Comparison of four NDT methods for indication of reactor steel degradation by high fluences of neutron irradiation

Czech Academy of Sciences Publication Activity Database

Tomáš, Ivan; Vértesy, G.; Pirfo Barroso, S.; Kobayashi, S.

2013-01-01

Roč. 265, DEC (2013), s. 201-209 ISSN 0029-5493 Institutional support: RVO:68378271 Keywords : neutron irradiation * steel degradation * nuclear reactor pressure vessel * magnetic NDT * magnetic minor hysteresis loops * Magnetic Barkhausen Emission Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.972, year: 2013 http://www.sciencedirect.com/science/article/pii/S0029549313004664

LWR aging management using a proactive approach to control materials degradation

International Nuclear Information System (INIS)

Bond, L.J.; Doctor, S.R.; Cumblidge, S.E.; Bruemmer, S.M.; Taylor, W.B.; Hull, A.B.; Malik, S.N.

2009-01-01

Material issues can be the limiting factor for the operation of nuclear power plants. There is growing interest in new and improved philosophies and methodologies for plant life management (PLiM), which include the migration from reliance on periodic inservice inspection to include condition-based maintenance. A further step in the development of plant management is the move from proactive responses based on ISI to become proactive, through the investigation of the potential for implementation of a proactive management of materials degradation (PMMD) program and its potential impact on the management of LWRs. (author)

Study for Relation of Pressure and Aging Degradation during LOCA Test

International Nuclear Information System (INIS)

Kim, Jong Seog

2013-01-01

As result of this test, it was found that low pressure effect in aging was not significant compared with that of temperature. If temperature profile in LOCA test can satisfy the plant LOCA profile, no further analysis of pressure profile for aging degradation is necessary. For environmental qualification of electric equipment in containment building of nuclear power plant, LOCA test should be applied. During the LOCA test, temperature and pressure of LOCA chamber shall be controlled to meet a requirement of plant specific LOCA profile. It is general to keep LOCA test temperature and pressure above the plant specific LOCA profile. If the test temperature is lower than required profile in some time zone while it is higher in other time zone, calculation of total cumulated test temperature is required to compare with that of plant profile. Arrhenius equation can be applied for calculation of total temperature accumulation. If there is a deviation of pressure between test profile and plant specific profile, can we still use the same rule of temperature? Since the Arrhenius equation can't be applied to pressure, analysis of pressure effect to aging degradation is not easy. Study for relation of pressure and aging degradation during LOCA condition is described herein. To Study an aging degradation effect of pressure during LOCA test, comparison of IR during high LOCA pressure and low LOCA pressure were implemented. We expected low IR in high pressure because it contained a high concentration of oxygen which induces high aging degradation. Contrary to our expectation, IR of low pressure was lower than that of high pressure. It is assumed that high vibration of temperature profile to maintain the low pressure at high temperature induced supply of high enthalpy steam into LOCA chamber

Characterization and degradation potential of diesel-degrading bacterial strains for application in bioremediation.

Science.gov (United States)

Balseiro-Romero, María; Gkorezis, Panagiotis; Kidd, Petra S; Van Hamme, Jonathan; Weyens, Nele; Monterroso, Carmen; Vangronsveld, Jaco

2017-10-03

Bioremediation of polluted soils is a promising technique with low environmental impact, which uses soil organisms to degrade soil contaminants. In this study, 19 bacterial strains isolated from a diesel-contaminated soil were screened for their diesel-degrading potential, biosurfactant (BS) production, and biofilm formation abilities, all desirable characteristics when selecting strains for re-inoculation into hydrocarbon-contaminated soils. Diesel-degradation rates were determined in vitro in minimal medium with diesel as the sole carbon source. The capacity to degrade diesel range organics (DROs) of strains SPG23 (Arthobacter sp.) and PF1 (Acinetobacter oleivorans) reached 17-26% of total DROs after 10 days, and 90% for strain GK2 (Acinetobacter calcoaceticus). The amount and rate of alkane degradation decreased significantly with increasing carbon number for strains SPG23 and PF1. Strain GK2, which produced BSs and biofilms, exhibited a greater extent, and faster rate of alkane degradation compared to SPG23 and PF1. Based on the outcomes of degradation experiments, in addition to BS production, biofilm formation capacities, and previous genome characterizations, strain GK2 is a promising candidate for microbial-assisted phytoremediation of diesel-contaminated soils. These results are of particular interest to select suitable strains for bioremediation, not only presenting high diesel-degradation rates, but also other characteristics which could improve rhizosphere colonization.

17O NMR investigation of oxidative degradation in polymers under γ-irradiation

International Nuclear Information System (INIS)

ALAM, TODD M.; CELINA, MATHIAS C.; ASSINK, ROGER A.; CLOUGH, ROGER LEE; GILLEN, KENNETH T.

2000-01-01

The γ-irradiated-oxidation of pentacontane (C 50 H 102 ) and the polymer polyisoprene was investigated as a function of oxidation level using 17 O nuclear magnetic resonance (NMR) spectroscopy. It is demonstrated that by using 17 O labeled O 2 gas during the γ-irradiation process, details about the oxidative degradation mechanisms can be directly obtained from the analysis of the 17 O NMR spectra. Production of carboxylic acids is the primary oxygen-containing functionality during the oxidation of pentacontane, while ethers and alcohols are the dominant oxidation product observed for polyisoprene. The formation of ester species during the oxidation process is very minor for both materials, with water also being produced in significant amounts during the radiolytic oxidation of polyisoprene. The ability to focus on the oxidative component of the degradation process using 17 O NMR spectroscopy demonstrates the selectivity of this technique over more conventional approaches

Cobalt-60 gamma radiation effects on degradation of pesticides used in stored rice and beans

International Nuclear Information System (INIS)

Groppo, Gerson A.

1988-02-01

The present work, carried out at CENA, an agriculture nuclear energy center - University of Sao Paulo - Brazil, investigates the Cobalt-60 gamma radiation effects on insecticides applied to stored rice and beans. The radiation dose applied - 200 Gy - to the stored rice and beans treated with insecticides was not sufficient to cause a noticeable chemical degradation through insect mortality. (author). 31 refs., 23 tabs

Management of nuclear power plants lifetime

International Nuclear Information System (INIS)

Hutin, J.P.

2006-01-01

The factors influencing the management of the service life of nuclear power plants can be of various types and the 'heaviest' ones have to be managed through robust and explicit approaches involving all actors. However, the mastery of the service life starts with the mastery of the technical problems, in particular the physical aging of the facilities. This mastery requires to foresee and anticipate the problems and thus a good understanding of the phenomena involved. This article presents: 1 - the general problem of service life management: lifetime concept, situation of French power plants, service life management policy; 2 - aging mechanisms: embrittlement of steel under irradiation, swelling of materials, thermal aging, fatigue, stress corrosion, aqueous corrosion of metals, corrosion-erosion, mechanisms of concrete degradation, mechanisms of elastomers and polymers degradation, wear; 3 - non-replaceable parts: reactor vessel, containment building; 4 - replaceable parts: cables, instrumentation and control system, core internals, primary loop piping, auxiliary primary piping, pressurizer, primary pump, steam generator tubes, other Ni-Cr-Fe alloy parts, secondary loop piping, turbine, alternator; 5 - non-technical aspects: perenniality of the industrial support, evolution of safety requirements, public acceptance, economical aspects, knowledge and information systems; 6 - situation in foreign countries: status of the world nuclear park, lifetime notion in foreign countries, situation in the USA. (J.S.)

Nuclear power plants

International Nuclear Information System (INIS)

Ushijima, Susumu.

1984-01-01

Purpose: To enable to prevent the degradation in the quality of condensated water in a case where sea water leakage should occur in a steam condenser of a BWR type nuclear power plant. Constitution: Increase in the ion concentration in condensated water is detected by an ion concentration detector and the leaking factor of sea water is calculated in a leaking factor calculator. If the sea water leaking factor exceeds a predetermined value, a leak generation signal is sent from a judging device to a reactor power control device to reduce the reactor power. At ehe same tiem, the leak generation signal is also sent to a steam condenser selection and isolation device to interrupt the sea water pump of a specified steam condenser based on the signal from the ion concentration detector, as well as close the inlet and outlet valves while open vent and drain valves to thereby forcively discharge the sea water in the cooling water pipes. This can keep the condensate desalting device from ion breaking and prevent the degradation in the quality of the reactor water. (Horiuchi, T.)

Isoform-specific proteasomal degradation of Rbfox3 during chicken embryonic development

Energy Technology Data Exchange (ETDEWEB)

Kim, Kee K.; Adelstein, Robert S.; Kawamoto, Sachiyo, E-mail: kawamots@mail.nih.gov

2014-08-08

Highlights: • Protein stability of Rbfox3 splice isoforms is differentially regulated. • Rbfox3-d31, an Rbfox3 isoform lacking the RRM, is highly susceptible to degradation. • The protein stability of Rbfox3-d31 is regulated by the ubiquitin–proteasome pathway. • Rbfox3-d31 inhibits the nuclear localization of Rbfox2. • Rbfox3-d31 inhibits the splicing activity of Rbfox2. - Abstract: Rbfox3, a neuron-specific RNA-binding protein, plays an important role in neuronal differentiation during development. An isoform Rbfox3-d31, which excludes the 93-nucleotide cassette exon within the RNA recognition motif of chicken Rbfox3, has been previously identified. However, the cellular functions of Rbfox3-d31 remain largely unknown. Here we find that Rbfox3-d31 mRNA is highly expressed during the early developmental stages of the chicken embryo, while Rbfox3-d31 protein is barely detected during the same stage due to its rapid degradation mediated by the ubiquitin–proteasome pathway. Importantly, this degradation is specific to the Rbfox3-d31 isoform and it does not occur with full-length Rbfox3. Furthermore, suppression of Rbfox3-d31 protein degradation with the proteasome inhibitor MG132 attenuates the splicing activity of another Rbfox family member Rbfox2 by altering the subcellular localization of Rbfox2. These results suggest that Rbfox3-d31 functions as a repressor for the splicing activity of the Rbfox family and its protein level is regulated in an isoform-specific manner in vivo.

Developments in polymer degradation - 7

International Nuclear Information System (INIS)

Grassie, N.

1987-01-01

A selection of topics which are representative of the continually expanding area of polymer degradation is presented. The aspects emphasised include the products of degradation of specific polymers, degradation by high energy radiation and mechanical forces, fire retardant studies and the special role of small radicals in degradation processes. (author)

The biogeochemical fate of nickel during microbial ISA degradation; implications for nuclear waste disposal.

Science.gov (United States)

Kuippers, Gina; Boothman, Christopher; Bagshaw, Heath; Ward, Michael; Beard, Rebecca; Bryan, Nicholas; Lloyd, Jonathan R

2018-06-08

Intermediate level radioactive waste (ILW) generally contains a heterogeneous range of organic and inorganic materials, of which some are encapsulated in cement. Of particular concern are cellulosic waste items, which will chemically degrade under the conditions predicted during waste disposal, forming significant quantities of isosaccharinic acid (ISA), a strongly chelating ligand. ISA therefore has the potential to increase the mobility of a wide range of radionuclides via complex formation, including Ni-63 and Ni-59. Although ISA is known to be metabolized by anaerobic microorganisms, the biodegradation of metal-ISA complexes remains unexplored. This study investigates the fate of a Ni-ISA complex in Fe(III)-reducing enrichment cultures at neutral pH, representative of a microbial community in the subsurface. After initial sorption of Ni onto Fe(III)oxyhydroxides, microbial ISA biodegradation resulted in >90% removal of the remaining Ni from solution when present at 0.1 mM, whereas higher concentrations of Ni proved toxic. The microbial consortium associated with ISA degradation was dominated by close relatives to Clostridia and Geobacter species. Nickel was preferentially immobilized with trace amounts of biogenic amorphous iron sulfides. This study highlights the potential for microbial activity to help remove chelating agents and radionuclides from the groundwater in the subsurface geosphere surrounding a geodisposal facility.

Identification of the chemical inventory of different paint types applied in nuclear facilities

International Nuclear Information System (INIS)

Sabrina Tietze; Foreman, M.R.St.J.; Ekberg, CH.H.; Chalmers University of Technology, Chemical and Biological Engineering, Goeteborg; Dongen van, B.E.

2013-01-01

The floors, concrete walls and many of the metal surfaces in nuclear power plant containments are coated with zinc primers or paint films to preserve the metal surfaces and simplify decontamination in the containment after the occurrence of a severe nuclear incident or accident. A chemical examination of paint films from different nuclear installations out of operation, as well as current operating ones, reveals that different types of paints are used whose composition can vary significantly. Results obtained for one type of paint at a certain nuclear site are in most cases unlikely to be comparable with sites painted with another type of paint. During normal operation and particularly during nuclear accidents, the paints will degrade under the high temperature, steam and irradiation influence. As paint and its degradation products can act as sources and depots for volatile iodine compounds, the type and aging conditions of the paint films will have a significant impact on the source term of the volatile fission product iodine. Thus, great care should be taken when extrapolating any results obtained for the interaction of radioactive iodine with one paint product to a different paint product. The main focus of the study is a comparison of the chemical profile of paint films applied in Swedish nuclear power plants. Teknopox Aqua V A, an epoxy paint recently used at Ringhals 2, and an emulsion paint used in the scrubber buildings of Ringhals 1-4 are compared with a paint film from Barsebaeck nuclear power plant unit 1 that had been aged under real reactor conditions for 20 years. In addition, two paint films, an emulsion and a gloss paint, used in an international nuclear fuel reprocessing facility, are compared with the paints from the Swedish nuclear power plants. (author)

Purex diluent degradation

International Nuclear Information System (INIS)

Tallent, O.K.; Mailen, J.C.; Pannell, K.D.

1984-02-01

The chemical degradation of normal paraffin hydrocarbon (NPH) diluents both in the pure state and mixed with 30% tributyl phosphate (TBP) was investigated in a series of experiments. The results show that degradation of NPH in the TBP-NPH-HNO 3 system is consistent with the active chemical agent being a radical-like nitrogen dioxide (NO 2 ) molecule, not HNO 3 as such. Spectrophotometric, gas chromatographic, mass spectrographic, and titrimetric methods were used to identify the degradation products, which included alkane nitro and nitrate compounds, alcohols, unsaturated alcohols, nitro alcohols, nitro alkenes, ketones, and carboxylic acids. The degradation rate was found to increase with increases in the HNO 3 concentration and the temperature. The rate was decreased by argon sparging to remove NO 2 and by the addition of butanol, which probably acts as a NO 2 scavenger. 13 references, 11 figures

Iodinated contrast media electro-degradation: process performance and degradation pathways.

Science.gov (United States)

Del Moro, Guido; Pastore, Carlo; Di Iaconi, Claudio; Mascolo, Giuseppe

2015-02-15

The electrochemical degradation of six of the most widely used iodinated contrast media was investigated. Batch experiments were performed under constant current conditions using two DSA® electrodes (titanium coated with a proprietary and patented mixed metal oxide solution of precious metals such as iridium, ruthenium, platinum, rhodium and tantalum). The degradation removal never fell below 85% (at a current density of 64 mA/cm(2) with a reaction time of 150 min) when perchlorate was used as the supporting electrolyte; however, when sulphate was used, the degradation performance was above 80% (at a current density of 64 mA/cm(2) with a reaction time of 150 min) for all of the compounds studied. Three main degradation pathways were identified, namely, the reductive de-iodination of the aromatic ring, the reduction of alkyl aromatic amides to simple amides and the de-acylation of N-aromatic amides to produce aromatic amines. However, as amidotrizoate is an aromatic carboxylate, this is added via the decarboxylation reaction. The investigation did not reveal toxicity except for the lower current density used, which has shown a modest toxicity, most likely for some reaction intermediates that are not further degraded. In order to obtain total removal of the contrast media, it was necessary to employ a current intensity between 118 and 182 mA/cm(2) with energy consumption higher than 370 kWh/m(3). Overall, the electrochemical degradation was revealed to be a reliable process for the treatment of iodinated contrast media that can be found in contaminated waters such as hospital wastewater or pharmaceutical waste-contaminated streams. Copyright © 2014 Elsevier B.V. All rights reserved.

Condition monitoring of a check valve for nuclear power plants by means of acoustic emission technique

International Nuclear Information System (INIS)

Lee, Min Rae; Leee, Jun Hyun; Kim, Jung Tack; Kim, Jung Soo; Luk, V. K.

2003-01-01

This work performed in support of the International Nuclear Energy Research Initiative(INERI) program, which was to develop and demonstrate advanced sensor and computational technology for on-line monitoring of the condition of components, structures, and systems in advanced and next-generation nuclear power plants (NPPs). The primary object of this work is to investigate advanced condition monitoring systems based on acoustic emission detection that can provide timely detection of check valve degradation and service aging so that maintenance/replacement could be preformed prior to loss of safety function. The research is focused on the capability of AE technique to provide diagnostic information useful in determining check valve aging and degradation, check valve failures and undesirable operating modes. This work also includes the investigation and adaptation of several advanced sensor technologies such as accelerometer and advanced ultrasonic technique. In addition, this work will develop advanced sophisticated signal processing, noise reduction, and pattern recognition techniques and algorithms from check valve degradation.

Summary. “Materials Challenges in Nuclear Energy,” S.J. Zinkle, 2013

Energy Technology Data Exchange (ETDEWEB)

Pestovich, Kimberly Shay [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-11-05

Nuclear energy continues to grow in abundance and importance. It offers a future electric grid based entirely off of green energy, and it has numerous applications. Nuclear power has capabilities to desalinate water, deliver process heat or steam, affordably crack hydrogen from water, and extract unconventional fossil fuel sources. Current light water reactors demonstrate high reliability under normal operating conditions. Researchers have shown significant interest and investigating how to extend reactor lifespans and into other possible reactor designs. Further understanding of mechanisms responsible for corrosion and stress corrosion cracking, radiation hardening and degradation, and nuclear fuels innovations can lead to safer, more reliable, and cost-effective water-cooled nuclear reactors for electricity production.

Shift scheduling limits for the nuclear industry NRC policy and recommendations

International Nuclear Information System (INIS)

Koontz, J.; Morisseau, D.; Lewis, P.

1985-01-01

A study on shift scheduling and use of overtime and their effects on human performance in nuclear and non-nuclear industries was conducted. An analysis of the literature, current practices, and federal policy on shift scheduling resulted in human factors recommendations for limiting hours of work in the nuclear industry for nuclear power plant personnel conducting safety related functions. Recommended limits on total hours of work were developed by a panel of experts for both 8-hour and 12-hour daily shift schedules for weekly, biweekly, monthly, and annual work periods. The study results are particularly applicable to control room operators but should also be considered for other personnel where performance degradation due to fatigue could directly affect safe plant operations

Development of degradation D/B system for the containment building of NPP

International Nuclear Information System (INIS)

Cho, M. S.; Song, Y. C.; Yim, J. H.; Kim, D. K.; Lee, J. S.

2001-01-01

The Degradation D/B System is developed for digitalizing the history of the Containment building of nuclear power plant. It have 6 D/B which are consist of General, Design drawing, Material, Construction, ISI·SIT·ILRT D/B. For efficient operation of the system, utilities are also developed such as the aging and repair data management program for concrete and steel structures, the data search engine with various options helping users find what they want, and the data exchange program restoring and updating input data

Monitoring Low-Cycle Fatigue Material-Degradation by Ultrasonic Methods

Directory of Open Access Journals (Sweden)

R. Himawan

2010-08-01

Full Text Available Any system consisting of structural material often undergoes fatigue, which is caused by dynamic load cycle. As a structural system, nuclear power plant is very likely to have low-cycle fatigue at many of its components. Taking into account the importance of monitoring low-cycle fatigue on structural components to prevent them from getting failure, the authors have conducted a work to monitor material degradation caused by low-cycle fatigue by using ultrasonic method. An alloy of Cu-40Zn was used as a test specimen. Ultrasonic water immersion procedure was employed in this ultrasonic test. The probe used is a focusing type and has frequency as high as 15 MHz. The specimen area tested is in the middle part divided into 14 points × 23 points. The results, which were frequency spectrums, were analyzed using two parameters: frequency spectrum peak intensity and attenuation function gradient. The analysis indicates that peak intensity increases at the beginning of load cycle and then decreases. Meanwhile, gradient of attenuation function is lower at the beginning of fatigue process, and then consistently gets higher. It concludes that low-fatigue material degradation can be monitored by using ultrasonic method.

Determination of degradation conditions of exchange resins containing technetium

International Nuclear Information System (INIS)

Rivera S, A.; Monroy G, F.; Quintero P, E.

2014-10-01

The quantification of Tc-99 in spent exchange resins, coming from nuclear power plants, is indispensable to define their administration. The Tc-99 is a pure beta emitter of 210000 years of half-life, volatile and of a high mobility in water and soil. For this reason, the objective of this work is to establish a digestion method of ionic exchange resins containing technetium that retains more than 95% of this radioisotope. Mineralization tests were carried out of a resin Amberlite IRN-150 by means of an oxidation heat, in acid medium, varying the resin mass, the medium volume, the media type, the temperature and the digestion time. The digested samples were analyzed by gas chromatography to estimate the grade of their degradation. The 99m Tc was used as tracer to determine the technetium percentage recovered after mineralizing the resin. The digestion process depends on the temperature and the resin mass. At higher temperature better mineralization of samples and to greater resin mass to a constant temperature, less degradation of the resin. The spectra beta of the 99m Tc and 99 Tc are presented. (Author)

Effectiveness of storage practices in mitigating aging degradation during reactor layup

International Nuclear Information System (INIS)

Enderlin, W.I.

1995-09-01

One of the issues identified in the US Nuclear Regulatory Commission's Nuclear Plant Aging Research program plan is the need to understand the state of ''mothballed'' or other out-of-service equipment to ensure subsequent safe operation. Programs for proper storage and preservation of materials and components are required by NRC regulations (10 CFR 50, Appendix B). However, materials and components have been seriously degraded due to improper storage, protection, or layup, at facilities under construction as well as those with operating licenses. Pacific Northwest Laboratory has evaluated management of aging for unstarted or mothballed nuclear power plants. The investigations revealed that no uniform guidance in the industry addresses reactor layup. In each case investigated, layup was not initiated in a timely manner, primarily because of schedule uncertainty. Hence, it is reasonable to assume that this delay resulted in accelerated aging of some safety-significant structures, systems, and components (SSCs). The applicable layup process is site-specific. The reactor type, climatic setting, operational status, and materials of construction are factors that strongly dictate the layup method to be used. The adequacy of current layup practices, and hence their impact on safety-significant SSCS, is not fully understood

Nuclear surveillance of mRNP formation

DEFF Research Database (Denmark)

Jensen, Torben Heick

Proper formation of mRNP requires co-transcriptional loading of proteins onto nascent transcripts. Mutations in several genes involved in mRNA processing, mRNP assembly and nuclear export lead to production of aberrant mRNPs that are retained in transcription site-associated foci. Retention...... and degradation of transcripts depend on the nuclear exosome of 3’-5’ exonucleases.We have studied connections between mRNP assembly and quality control in the yeast S. cerevisiae using mutants of the THO complex. THO is implicated in co-transcriptional mRNP assembly, but its precise role is not known. Genetic...... and biochemical data now show that a defective THO complex negatively impacts mRNA 3’-end processing. We are currently trying to understand the relationship between this phenomenon and mRNP quality control. Retention of mRNP in THO mutants is dependent on the nuclear exosome component Rrp6p. Using the solved...

Operation of Finnish nuclear power plants

International Nuclear Information System (INIS)

Lehtinen, Pekka

1987-07-01

These general reviews of the operation of the Finnish nuclear power plants concentrate on such events and discoveries related to reactor and radiation safety that the regulatory body, the Finnish Centre for Radiation and Nuclear Safety, regards as noteworthy. The report also includes a summary of the radiation safety of the personnel and the environment, as well as tabulated data on the production and load factors of the plants. No event in the report period, or in the whole year of 1986, essentially degraded plant safety nor posed a radiation hazard to the personnel or the environment. For remedying certain defects found in the adminstrative procedures concerning plant operation and maintenance, the Loviisa power plant was shut down for several days in September

Cdc20 mediates D-box-dependent degradation of Sp100

International Nuclear Information System (INIS)

Wang, Ran; Li, Ke-min; Zhou, Cai-hong; Xue, Jing-lun; Ji, Chao-neng; Chen, Jin-zhong

2011-01-01

Highlights: ► Cdc20 is a co-activator of APC/C complex. ► Cdc20 recruits Sp100 and mediates its degradation. ► The D-box of Sp100 is required for Cdc20-mediated degradation. ► Sp100 expresses consistently at both the mRNA and protein levels in cell cycle. -- Abstract: Cdc20 is a co-activator of the anaphase-promoting complex/cyclosome (APC/C complex), which recruits substrates at particular phases of the cell cycle and mediates their degradation. Sp100 is a PML-NB scaffold protein, which localizes to nuclear particles during interphase and disperses from them during mitosis, participates in viral resistance, transcriptional regulation, and apoptosis. However, its metabolism during the cell cycle has not yet been fully characterized. We found a putative D-box in Sp100 using the Eukaryotic Linear Motif (ELM) predictor database. The putative D-box of Sp100 was verified by mutational analysis. Overexpression of Cdc20 resulted in decreased levels of both endogenous Sp100 protein and overexpressed Sp100 mRNA in HEK 293 cells. Only an overexpressed D-box deletion mutant of Sp100 accumulated in HEK293 cells that also overexpressed Cdc20. Cdc20 knockdown by cdc20 specific siRNA resulted in increased Sp100 protein levels in cells. Furthermore, we discovered that the Cdc20 mediated degradation of Sp100 is diminished by the proteasome inhibitor MG132, which suggests that the ubiquitination pathway is involved in this process. However, unlike the other Cdc20 substrates, which display oscillating protein levels, the level of Sp100 protein remains constant throughout the cell cycle. Additionally, both overexpression and knockdown of endogenous Sp100 had no effect on the cell cycle. Our results suggested that sp100 is a novel substrate of Cdc20 and it is degraded by the ubiquitination pathway. The intact D-box of Sp100 was necessary for this process. These findings expand our knowledge of both Sp100 and Cdc20 as well as their role in ubiquitination.

Anthocyanins degradation during storage of Hibiscus sabdariffa extract and evolution of its degradation products.

Science.gov (United States)

Sinela, André; Rawat, Nadirah; Mertz, Christian; Achir, Nawel; Fulcrand, Hélène; Dornier, Manuel

2017-01-01

Degradation parameters of two main anthocyanins from roselle extract (Hibiscus sabdariffa L.) stored at different temperatures (4-37°C) over 60days were determined. Anthocyanins and some of their degradation products were monitored and quantified using HPLC-MS and DAD. Degradation of anthocyanins followed first-order kinetics and reaction rate constants (k values), which were obtained by non-linear regression, showed that the degradation rate of delphinidin 3-O-sambubioside was higher than that of cyanidin 3-O-sambubioside with k values of 9.2·10(-7)s(-1) and 8.4·10(-7)s(-1) at 37°C respectively. The temperature dependence of the rate of anthocyanin degradation was modeled by the Arrhenius equation. Degradation of delphinidin 3-O-sambubioside (Ea=90kJmol(-1)) tended to be significantly more sensitive to an increase in temperature than cyanidin 3-O-sambubioside (Ea=80kJmol(-1)). Degradation of these anthocyanins formed scission products (gallic and protocatechuic acids respectively) and was accompanied by an increase in polymeric color index. Copyright © 2016 Elsevier Ltd. All rights reserved.

Analysis of the distribution of DNA repair patches in the DNA-nuclear matrix complex from human cells

International Nuclear Information System (INIS)

Mullenders, L.H.F.

1983-01-01

The distribution of ultraviolet-induced repair patches along DNA loops attached to the nuclear matrix, was investigated by digestion with DNA-degrading enzymes and neutral sucrose gradient centrifugation. When DNA was gradually removed by DNAase 1, pulse label incorporated by ultraviolet-irradiated cells during 10 min in the presence of hydroxyurea or hydroxyurea/arabinosylcytosine showed similar degradation kinetics as prelabelled DNA. No preferential association of pulse label with the nuclear matrix was observed, neither within 30 min nor 13 h after iiradiation. When the pulse label was incorporated by replicative synthesis under the same conditions, a preferential association of newly-synthesized DNA with the nuclear matrix was observed. Single-strand specific digestion with nuclease S 1 of nuclear lysates from ultraviolet-irradiated cells, pulse labelled in the presence of hydroxyurea/arabinosylcytosine, caused a release of about 70% of the prelabelled DNA and 90% of the pulse-labelled DNA from the rapidly sedimenting material in sucrose gradients. The results suggest no specific involvement of the nuclear matrix in repair synthesis, a random distribution of repair patches along the DNA loops, and simultaneously multiple incision events per DNA loop. (Auth.)

Analysis of the distribution of DNA repair patches in the DNA-nuclear matrix complex from human cells

Energy Technology Data Exchange (ETDEWEB)

Mullenders, L.H.F. (Rijksuniversiteit Leiden (Netherlands). Lab. voor Stralengenetica en Chemische Mutagenese); Zeeland, A.A. van; Natarajan, A.T. (Cohen (J.A.) Inst. voor Radiopathologie en Stralenbescherming, Leiden (Netherlands))

1983-09-09

The distribution of ultraviolet-induced repair patches along DNA loops attached to the nuclear matrix, was investigated by digestion with DNA-degrading enzymes and neutral sucrose gradient centrifugation. When DNA was gradually removed by DNAase 1, pulse label incorporated by ultraviolet-irradiated cells during 10 min in the presence of hydroxyurea or hydroxyurea/arabinosylcytosine showed similar degradation kinetics as prelabelled DNA. No preferential association of pulse label with the nuclear matrix was observed, neither within 30 min nor 13 h after irradiation. When the pulse label was incorporated by replicative synthesis under the same conditions, a preferential association of newly-synthesized DNA with the nuclear matrix was observed. Single-strand specific digestion with nuclease S/sub 1/ of nuclear lysates from ultraviolet-irradiated cells, pulse labelled in the presence of hydroxyurea/arabinosylcytosine, caused a release of about 70% of the prelabelled DNA and 90% of the pulse-labelled DNA from the rapidly sedimenting material in sucrose gradients. The results suggest no specific involvement of the nuclear matrix in repair synthesis, a random distribution of repair patches along the DNA loops, and simultaneously multiple incision events per DNA loop.

Autophagy contributes to regulation of nuclear dynamics during vegetative growth and hyphal fusion in Fusarium oxysporum.

Science.gov (United States)

Corral-Ramos, Cristina; Roca, M Gabriela; Di Pietro, Antonio; Roncero, M Isabel G; Ruiz-Roldán, Carmen

2015-01-01

In the fungal pathogen Fusarium oxysporum, vegetative hyphal fusion triggers nuclear mitotic division in the invading hypha followed by migration of a nucleus into the receptor hypha and degradation of the resident nucleus. Here we examined the role of autophagy in fusion-induced nuclear degradation. A search of the F. oxysporum genome database for autophagy pathway components identified putative orthologs of 16 core autophagy-related (ATG) genes in yeast, including the ubiquitin-like protein Atg8, which is required for the formation of autophagosomal membranes. F. oxysporum Foatg8Δ mutants were generated in a strain harboring H1-cherry fluorescent protein (ChFP)-labeled nuclei to facilitate analysis of nuclear dynamics. The Foatg8Δ mutants did not show MDC-positive staining in contrast to the wild type and the FoATG8-complemented (cFoATG8) strain, suggesting that FoAtg8 is required for autophagy in F. oxysporum. The Foatg8Δ strains displayed reduced rates of hyphal growth, conidiation, and fusion, and were significantly attenuated in virulence on tomato plants and in the nonvertebrate animal host Galleria mellonella. In contrast to wild-type hyphae, which are almost exclusively composed of uninucleated hyphal compartments, the hyphae of the Foatg8Δ mutants contained a significant fraction of hyphal compartments with 2 or more nuclei. The increase in the number of nuclei per hyphal compartment was particularly evident after hyphal fusion events. Time-lapse microscopy analyses revealed abnormal mitotic patterns during vegetative growth in the Foatg8Δ mutants. Our results suggest that autophagy mediates nuclear degradation after hyphal fusion and has a general function in the control of nuclear distribution in F. oxysporum.

Interim Report on Concrete Degradation Mechanisms and Online Monitoring Techniques

Energy Technology Data Exchange (ETDEWEB)

Mahadevan, Sankaran [Idaho National Lab. (INL), Idaho Falls, ID (United States); Agarwal, Vivek [Idaho National Lab. (INL), Idaho Falls, ID (United States); Neal, Kyle [Idaho National Lab. (INL), Idaho Falls, ID (United States); Kosson, David [Idaho National Lab. (INL), Idaho Falls, ID (United States); Adams, Douglas [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2014-09-01

The existing nuclear power plants in the United States have initial operating licenses of 40 years, though most of these plants have applied for and received license extensions. As plant structures, systems, and components age, their useful life—considering both structural integrity and performance—is reduced as a result of deterioration of the materials. The research on online monitoring of concrete structures conducted under the Advanced Instrumentation, Information, and Control Systems Technologies Pathway of the Light Water Reactor Sustainability Program at Idaho National Laboratory will develop and demonstrate concrete structures health monitoring capabilities. Assessment and management of aging concrete structures in nuclear plants require a more systematic approach than simple reliance on existing code margins of safety. Therefore, structural health monitoring is required to produce actionable information regarding structural integrity that supports operational and maintenance decisions. Through this research project, several national laboratories and Vanderbilt University propose to develop a framework of research activities for the health monitoring of nuclear power plant concrete structures that includes the integration of four elements—damage modeling, monitoring, data analytics, and uncertainty quantification. This report briefly discusses available techniques and ongoing challenges in each of the four elements of the proposed framework with emphasis on degradation mechanisms and online monitoring techniques.

Role of non destructive techniques for monitoring structural integrity of primary circuit of pressurized water reactor nuclear power plant

International Nuclear Information System (INIS)

Sharma, P.K.; Sreenivas, P.

2015-01-01

The safety of nuclear installations is ensured by assessing status of primary equipment for performing the intended function reliably and maintaining the integrity of pressure boundaries. The pressure boundary materials undergo material degradation during the plant operation. Pressure boundary materials are subjected to operating stresses and material degradation that results in material properties changes, discontinuities initiation and increase in size of existing discontinuities. Pre-Service Inspection (PSI) is performed to generate reference base line data of initial condition of the pressure boundary. In-Service Inspections (ISI) are performed periodically to confirm integrity of pressure boundaries through comparison with respect to base line data. The non destructive techniques are deployed considering nature of the discontinuities expected to be generated through operating conditions and degradation mechanisms. The paper is prepared considering Pressurized Water Reactor (PWR) Nuclear Power Plant. The paper describes the degradation mechanisms observed in the PWR nuclear power plants and salient aspect of PSI and ISI and considerations in selecting non destructive testing. The paper also emphasises on application of acoustic emission (AE) based condition monitoring systems that can supplement in-service inspections for detecting and locating discontinuities in pressure boundaries. Criticality of flaws can be quantitatively evaluated by determining their size through in-service inspection. Challenges anticipated in deployment of AE based monitoring system and solutions to cater those challenges are also discussed. (author)

A methodology for evaluating ''new'' technologies in nuclear power plants

International Nuclear Information System (INIS)

Korsah, K.; Clark, R.L.; Holcomb, D.E.

1994-01-01

As obsolescence and spare parts issues drive nuclear power plants to upgrade with new technology (such as optical fiber communication systems), the ability of the new technology to withstand stressors present where it is installed needs to be determined. In particular, new standards may be required to address qualification criteria and their application to the nuclear power plants of tomorrow. This paper discusses the failure modes and age-related degradation mechanisms of fiber optic communication systems, and suggests a methodology for identifying when accelerated aging should be performed during qualification testing

A global fouling factor methodology for analyzing steam generator thermal performance degradation

International Nuclear Information System (INIS)

Kreider, M.A.; White, G.A.; Varrin, R.D. Jr.

1998-06-01

Over the past few years, steam generator (SG) thermal performance degradation has led to decreased plant efficiency and power output at numerous PWR nuclear power plants with recirculating-type SGs. The authors have developed and implemented methodologies for quantitatively evaluating the various sources of SG performance degradation, both internal and external to the SG pressure boundary. These methodologies include computation of the global fouling factor history, evaluation of secondary deposit thermal resistance using deposit characterization data, and consideration of pressure loss causes unrelated to the tube bundle, such as hot-leg temperature streaming and SG moisture separator fouling. In order to evaluate the utility of the global fouling factor methodology, the authors performed case studies for a number of PWR SG designs. Key results from two of these studies are presented here. In tandem with the fouling-factor analyses, a study evaluated for each plant the potential causes of pressure loss. The combined results of the global fouling factor calculations and the pressure-loss evaluations demonstrated two key points: (1) that the available thermal margin against fouling, which can vary substantially from plant to plant, has an important bearing on whether a given plant exhibits losses in electrical generating capacity, and (2) that a wide variety of causes can result in SG thermal performance degradation

Ageing of significant to safety structure elements of nuclear power plants

International Nuclear Information System (INIS)

Maksimovas, G.; Ramanauskiene, A.; Ziliukas, A.

1999-01-01

The paper analyzes the ageing problems of structure elements in nuclear power plants. The standard documents and principal parts of the ageing evaluation program are presented. The ageing evaluation model is being worked out and degradation mechanisms of different atomic reactor materials are being compared. (author)

Threaded-fastener experience in nuclear power plants

International Nuclear Information System (INIS)

Koo, W.H.

1983-01-01

This report identifies 44 incidents of threaded-fastener degradation and failure in nuclear power plants from October 1964 to March 1982. It provides an overview of some of the threaded-fastener problems that have occurred since 1964. Safety implications of these incidents are discussed, and short-term regulatory actions and ongoing long-term regulatory actions are described. Information included in this report represents the current NRC staff understanding of each issue

Nuclear Knowledge Management: the IAEA Approach

International Nuclear Information System (INIS)

Sbaffoni, M.; De Grosbois, J.

2015-01-01

Knowledge in an organization is residing in people, processes and technology. Adequate awareness of their knowledge assets and of the risk of losing them is vital for safe and secure operations of nuclear installations. Senior managers understand this important linkage, and in the last years there is an increasing tendency in nuclear organizations to implement knowledge management strategies to ensure that the adequate and necessary knowledge is available at the right time, in the right place. Specific and advanced levels of knowledge are clearly required to achieve and maintain technical expertise, and experience must be developed and be available throughout the nuclear technology lifecycle. If a nuclear organization does not possess or have access to the required technical knowledge, a full understanding of the potential consequences of decisions and actions may not be possible, and safety, security and safeguards might be compromised. Effective decision making during design, licencing, procurement, construction, commissioning, operation, maintenance, refurbishment, and decommissioning of nuclear facilities needs to be risk-informed and knowledge-driven. Nuclear technology is complex and brings with it inherent and unique risks that must be managed to acceptably low levels. Nuclear managers have a responsibility not only to establish adequate technical knowledge and experience in their nuclear organizations but also to maintain it. The consequences of failing to manage the organizations key knowledge assets can result in serious degradations or accidents. The IAEA Nuclear Knowledge Management (NKM) sub-programme was established more than 10 years ago to support Nuclear Organizations, at Member States request, in the implementation and dissemination of the NKM methodology, through the development of guidance and tools, and by providing knowledge management services and assistance. The paper will briefly present IAEA understanding of and approach to knowledge

Drift Degradation Analysis

International Nuclear Information System (INIS)

G.H. Nieder-Westermann

2005-01-01

The outputs from the drift degradation analysis support scientific analyses, models, and design calculations, including the following: (1) Abstraction of Drift Seepage; (2) Seismic Consequence Abstraction; (3) Structural Stability of a Drip Shield Under Quasi-Static Pressure; and (4) Drip Shield Structural Response to Rock Fall. This report has been developed in accordance with ''Technical Work Plan for: Regulatory Integration Modeling of Drift Degradation, Waste Package and Drip Shield Vibratory Motion and Seismic Consequences'' (BSC 2004 [DIRS 171520]). The drift degradation analysis includes the development and validation of rockfall models that approximate phenomenon associated with various components of rock mass behavior anticipated within the repository horizon. Two drift degradation rockfall models have been developed: the rockfall model for nonlithophysal rock and the rockfall model for lithophysal rock. These models reflect the two distinct types of tuffaceous rock at Yucca Mountain. The output of this modeling and analysis activity documents the expected drift deterioration for drifts constructed in accordance with the repository layout configuration (BSC 2004 [DIRS 172801])

Irradiation of quench protection diodes at cryogenic temperatures in a nuclear research reactor

International Nuclear Information System (INIS)

Hagedorn, D.; Schoenbacher, H.; Gerstenberg, H.

1996-01-01

Within the framework of the Large Hadron Collider (LHC) R ampersand D programme, CERN and the Department of Physics E21 of the Technical University Munich have established a collaboration to carry out irradiation experiments at liquid helium and liquid nitrogen temperatures on epitaxial diodes for the superconducting magnet protection. Small diode samples of 10 mm wafer diameter from two different manufacturers were submitted to doses of up 50 kGy and neutron fluences up to 1015 n/cm 2 and the degradation of the electrical characteristics was measured versus dose. During irradiation the diodes were submitted to current pulse annealing and after irradiation to thermal annealing. After exposure some diodes show a degradation in forward voltage drop of up to 600 % which, however, can be reduced to about 15 % - 20 % by thermal annealing. The degradation at liquid helium temperature is very similar to the degradation at liquid nitrogen temperature. These degradations of electrical characteristics during the short term irradiation in a nuclear reactor are compared with degradations during long term irradiation in an accelerator environment at liquid nitrogen temperature

Sensing capabilities of piezoelectric wafer active sensors in extreme nuclear environment

Science.gov (United States)

Faisal Haider, Mohammad; Lin, Bin; Yu, Lingyu; Giurgiutiu, Victor

2017-04-01

There is considerable demand for structural health monitoring (SHM) at locations where there are substantial radiation fields such as nuclear reactor components, dry cask storage canister, irradiated fuel assemblies, etc. Piezoelectric wafer active sensors (PWAS) have been emerged as one of the major SHM sensing technologies. In order to use PWAS to perform SHM in nuclear environment, radiation influence on sensor and sensing capability needs to be investigated to assure the reliability of the PWAS based method. Radiation may cause degradation or even complete failure of sensors. Gamma radiation is one of the major radiation sources near the nuclear source. Therefore, experimental investigation was completed on the gamma radiation endurance of piezoelectric sensors. The irradiation test was done in a Co-60 Gamma Irradiator. Lead Zirconate Titanate (PZT) and Gallium Orthophosphate (GaPO4) PWAS were exposed under gamma radiation at 100 Gy/hr rate for 20 hours. Electro-mechanical (E/M) admittance signatures and electrical capacitance were measured to evaluate the PWAS performance before and after every 4 hours exposure to gamma radiation. PWAS were kept at room temperature for 6 days after each 4 hours radiation exposure to investigate the effect of time on PWAS by gamma radiation. It was found that, PZT-PWAS show variation in resonance frequency for both in plane and thickness mode E/M admittance. Where, the changes in resonance amplitudes are larger for PZT-PWAS. GaPO4-PWAS E/M impedance/admittance spectra don't show any reasonable change after gamma irradiation. A degradation behavior of electrical properties in the PZT-PWAS was observed. Capacitance value of PZT-PWAS decreases from 3.2 nF to 3.07 nF after exposing to gamma radiation for 20 hours at 100Gy/hour. This degradation behavior of electrical properties may be explained by the pinning of domain walls by some radiation induced effect. GaPO4-PWAS doesn't show reasonable degradation in electrical properties

Degradation of Alloy 800 steam generator tubing and its long-term behaviour predictions for plant life management

International Nuclear Information System (INIS)

Lu, Y.C.; Tapping, R.L.; Pandey, M.D.

2009-01-01

Alloy 800 tubing has a good service record in steam generators (SGs) in both German pressurized water reactors and CANDU 6 reactors, however, a recent comprehensive examination of several ex-service SG tubes removed from Darlington Nuclear Generating Station (DNGS) found that these SG tubes (which had experienced shallow pitting in service) were more susceptible to pitting corrosion in laboratory tests than a reference nuclear grade Alloy 800 tubing under SG crevice chemistry conditions. This was an unexpected finding and has raised questions about possible effects of in-service 'aging' on SG tubing. In addition, there has also been recent evidence that a few Alloy 800 tubes have experienced stress corrosion cracking (SCC) in some German pressurized water reactors (PWRs), possibly after many years of degradation-free service, although the inspection history of these tubes is not available to confirm that the reported degradation initiated recently. These findings suggest that Alloy 800 tubing may have some aging degradation susceptibility after many years of service. To provide support for a proactive SG aging management, a survey on the corrosion susceptibility of the archived Alloy 800 tubing from CANDU SGs under plausible crevice chemistry conditions was conducted to assess the potential material degradation issues in CANDU SGs. Experimental work was also performed to investigate the root cause leading to Alloy 800 SG tubing degradation. The results from this study suggested that a combination of negative factors; aggressive chemistry resulting from impurity ingress into the secondary side of the SGs, elevated electrochemical corrosion potential (ECP) during SG transients and surface strain/plastic deformation, might have led to the degradation of the ex-service SG tubing. The studies have shown that each of these conditions in isolation does not cause degradation of Alloy 800 SG tubing; a synergistic combination of factors is required. The OPEX and experimental

Project GRETE: evaluation of non destructive testing techniques for monitoring of material degradation

International Nuclear Information System (INIS)

Coste, J.F.

2001-01-01

The material aging of major critical components of nuclear installations due to in-service conditions may lead to a degradation of their mechanical characteristics. The early detection of material changes and their monitoring using innovative non destructive testing techniques would allow to plan actions in order to prevent the apparition of macroscopic damage (e.g. cracks). One major difficulty in using these particular techniques is to correlate the changes in the measured NDT signals to the microstructural changes in the material due to aging. This problem may be solved through careful microstructural examinations of the material damage. The objective of the project GRETE is to illustrate the potential use of NDT techniques for the monitoring of material degradation through two examples: neutron irradiation of reactor pressure vessel steel and thermal fatigue of piping. The purpose of this paper is to present the project and its programme of work. (author)

An approach regarding aging management program for concrete containment structure at the Gentilly-2 Nuclear Power Plant

Energy Technology Data Exchange (ETDEWEB)

Chenier, J-O.; Komljenovic, D., E-mail: Chenier.jean-olivier@hydro.qc.ca [Nuclear Power Plant Gentilly-2, Becancour, Quebec (Canada); Gocevski, V. [Hydro-Quebec Equipment, Structural Dept., Quebec (Canada); Picard, S.; Chretien, G. [Nuclear Power Plant Gentilly-2, Becancour, Quebec (Canada)

2012-07-01

The current paper presents the approach used by the Gentilly-2 Nuclear Power Plant, Hydro-Quebec, in elaborating a specific Aging Management Program (AMP) for its concrete containment structure. It is developed as a part of preparation activities for the plant refurbishment project. The specificity of the AMP consists in addressing Alkali-Aggregate Reaction (AAR) degradation mechanism which is not well known in the nuclear power industry. HQ developed a numerical model based on finite elements for assessing the concrete containment structure behaviour under the impact of AAR and other relevant degradation mechanisms. Such predictions enable a better targeting of corrective and mitigating actions during the second cycle of the G-2 operation while required. (author)

Degradation of diclofenac by UV-activated persulfate process: Kinetic studies, degradation pathways and toxicity assessments.

Science.gov (United States)

Lu, Xian; Shao, Yisheng; Gao, Naiyun; Chen, Juxiang; Zhang, Yansen; Xiang, Huiming; Guo, Youluo

2017-07-01

Diclofenac (DCF) is the frequently detected non-steroidal pharmaceuticals in the aquatic environment. In this study, the degradation of DCF was evaluated by UV-254nm activated persulfate (UV/PS). The degradation of DCF followed the pseudo first-order kinetics pattern. The degradation rate constant (k obs ) was accelerated by UV/PS compared to UV alone and PS alone. Increasing the initial PS dosage or solution pH significantly enhanced the degradation efficiency. Presence of various natural water constituents had different effects on DCF degradation, with an enhancement or inhibition in the presence of inorganic anions (HCO 3 - or Cl - ) and a significant inhibition in the presence of NOM. In addition, preliminary degradation mechanisms and major products were elucidated using LC-MS/MS. Hydroxylation, decarbonylation, ring-opening and cyclation reaction involving the attack of SO 4 • - or other substances, were the main degradation mechanism. TOC analyzer and Microtox bioassay were employed to evaluate the mineralization and cytotoxicity of solutions treated by UV/PS at different times, respectively. Limited elimination of TOC (32%) was observed during the mineralization of DCF. More toxic degradation products and their related intermediate species were formed, and the UV/PS process was suitable for removing the toxicity. Of note, longer degradation time may be considered for the final toxicity removal. Copyright © 2017. Published by Elsevier Inc.

Evaluation of fatigue damage in nuclear power plants: evolution and new tools of analysis

International Nuclear Information System (INIS)

Cicero, R.; Corchon, F.

2011-01-01

This paper presents new fatigue mechanisms requiring analysis, tools developed for evaluation and the latest trends and studies that are currently working in the nuclear field, and allow proper management referring facilities the said degradation mechanism.

THE HIGH-TEMPERATURE ELECTROLYSIS PROGRAM AT THE IDAHO NATIONAL LABORATORY: OBSERVATIONS ON PERFORMANCE DEGRADATION

Energy Technology Data Exchange (ETDEWEB)

J. E. O' Brien; C. M. Stoots; J. S. Herring; K. G. Condie; G. K. Housley

2009-06-01

This paper presents an overview of the high-temperature electrolysis research and development program at the Idaho National Laboratory, with selected observations of electrolysis cell degradation at the single-cell, small stack and large facility scales. The objective of the INL program is to address the technical and scale-up issues associated with the implementation of solid-oxide electrolysis cell technology for hydrogen production from steam. In the envisioned application, high-temperature electrolysis would be coupled to an advanced nuclear reactor for efficient large-scale non-fossil non-greenhouse-gas hydrogen production. The program supports a broad range of activities including small bench-scale experiments, larger scale technology demonstrations, detailed computational fluid dynamic modeling, and system modeling. A summary of the current status of these activities and future plans will be provided, with a focus on the problem of cell and stack degradation.

Survey of degradation modes of candidate materials for high-level radioactive-waste disposal containers

Energy Technology Data Exchange (ETDEWEB)

Strum, M.J.; Weiss, H.; Farmer, J.C. (Lawrence Livermore National Lab., CA (USA)); Bullen, D.B. (Science and Engineering Associates, Inc., Pleasanton, CA (USA))

1988-06-01

This volume surveys the effects of welding on the degradation modes of three austenitic alloys: Types 304L and 316L stainless steels and Alloy 825. These materials are candidates for the fabrication of containers for the long-term storage of high-level nuclear waste. The metallurgical characteristics of fusion welds are reviewed here and related to potential degradation modes of the containers. Three specific areas are discussed in depth: (1) decreased resistance to corrosion in the forms of preferential corrosion, sensitization, and susceptibility to stress corrosion cracking, (2) hot cracking in the heat-affected zone and the weld zone, and (3) formation of intermetallic phases. The austenitic alloys are ranked as follows in terms of overall weldability: Alloy 825 (best) > Type 316L stainless steel > Type 304L stainless steel (worst). 108 refs., 31 figs., 7 tabs.

Survey of degradation modes of candidate materials for high-level radioactive-waste disposal containers

International Nuclear Information System (INIS)

Strum, M.J.; Weiss, H.; Farmer, J.C.; Bullen, D.B.

1988-06-01

This volume surveys the effects of welding on the degradation modes of three austenitic alloys: Types 304L and 316L stainless steels and Alloy 825. These materials are candidates for the fabrication of containers for the long-term storage of high-level nuclear waste. The metallurgical characteristics of fusion welds are reviewed here and related to potential degradation modes of the containers. Three specific areas are discussed in depth: (1) decreased resistance to corrosion in the forms of preferential corrosion, sensitization, and susceptibility to stress corrosion cracking, (2) hot cracking in the heat-affected zone and the weld zone, and (3) formation of intermetallic phases. The austenitic alloys are ranked as follows in terms of overall weldability: Alloy 825 (best) > Type 316L stainless steel > Type 304L stainless steel (worst). 108 refs., 31 figs., 7 tabs

Photo-fenton degradation of diclofenac: identification of main intermediates and degradation pathway.

Science.gov (United States)

Pérez-Estrada, Leónidas A; Malato, Sixto; Gernjak, Wolfgang; Agüera, Ana; Thurman, E Michael; Ferrer, Imma; Fernández-Alba, Amadeo R

2005-11-01

In recent years, the presence of pharmaceuticals in the aquatic environment has been of growing interest. These new contaminants are important because many of them are not degraded under the typical biological treatments applied in the wastewater treatment plants and represent a continuous input into the environment. Thus, compounds such as diclofenac are present in surface waters in all Europe and a crucial need for more enhanced technologies that can reduce its presence in the environment has become evident. In this sense, advanced oxidation processes (AOPs) represent a good choice for the treatment of hazardous nonbiodegradable pollutants. This work deals with the solar photodegradation of diclofenac, an antiinflammatory drug, in aqueous solutions by photo-Fenton reaction. A pilot-scale facility using a compound parabolic collector (CPC) reactor was used for this study. Results obtained show rapid and complete oxidation of diclofenac after 60 min, and total mineralization (disappearance of dissolved organic carbon, DOC) after 100 min of exposure to sunlight. Although diclofenac precipitates during the process at low pH, its degradation takes place in the homogeneous phase governed by a precipitation-redissolution-degradation process. Establishment of the reaction pathway was made possible by a thorough analysis of the reaction mixture identifying the main intermediate products generated. Gas chromatography-mass spectrometry (GC/ MS) and liquid chromatography coupled with time-of-flight mass spectrometry (LC/TOF-MS) were used to identify 18 intermediates, in two tentative degradation routes. The main one was based on the initial hydroxylation of the phenylacetic acid moiety in the C-4 position and subsequent formation of a quinone imine derivative that was the starting point for further multistep degradation involving hydroxylation, decarboxylation, and oxidation reactions. An alternative route was based on the transient preservation of the biphenyl amino moiety

Characterization of Methane Degradation and Methane-Degrading Microbes in Alaska Coastal Water

Energy Technology Data Exchange (ETDEWEB)

Kirchman, David L. [Univ. of Delaware, Lewes, DE (United States)

2012-03-29

The net flux of methane from methane hydrates and other sources to the atmosphere depends on methane degradation as well as methane production and release from geological sources. The goal of this project was to examine methane-degrading archaea and organic carbon oxidizing bacteria in methane-rich and methane-poor sediments of the Beaufort Sea, Alaska. The Beaufort Sea system was sampled as part of a multi-disciplinary expedition (Methane in the Arctic Shelf or MIDAS) in September 2009. Microbial communities were examined by quantitative PCR analyses of 16S rRNA genes and key methane degradation genes (pmoA and mcrA involved in aerobic and anaerobic methane degradation, respectively), tag pyrosequencing of 16S rRNA genes to determine the taxonomic make up of microbes in these sediments, and sequencing of all microbial genes (metagenomes ). The taxonomic and functional make-up of the microbial communities varied with methane concentrations, with some data suggesting higher abundances of potential methane-oxidizing archaea in methane-rich sediments. Sequence analysis of PCR amplicons revealed that most of the mcrA genes were from the ANME-2 group of methane oxidizers. According to metagenomic data, genes involved in methane degradation and other degradation pathways changed with sediment depth along with sulfate and methane concentrations. Most importantly, sulfate reduction genes decreased with depth while the anaerobic methane degradation gene (mcrA) increased along with methane concentrations. The number of potential methane degradation genes (mcrA) was low and inconsistent with other data indicating the large impact of methane on these sediments. The data can be reconciled if a small number of potential methane-oxidizing archaea mediates a large flux of carbon in these sediments. Our study is the first to report metagenomic data from sediments dominated by ANME-2 archaea and is one of the few to examine the entire microbial assemblage potentially involved in

Nuclear Radiation Degradation Study on HD Camera Based on CMOS Image Sensor at Different Dose Rates.

Science.gov (United States)

Wang, Congzheng; Hu, Song; Gao, Chunming; Feng, Chang

2018-02-08

In this work, we irradiated a high-definition (HD) industrial camera based on a commercial-off-the-shelf (COTS) CMOS image sensor (CIS) with Cobalt-60 gamma-rays. All components of the camera under test were fabricated without radiation hardening, except for the lens. The irradiation experiments of the HD camera under biased conditions were carried out at 1.0, 10.0, 20.0, 50.0 and 100.0 Gy/h. During the experiment, we found that the tested camera showed a remarkable degradation after irradiation and differed in the dose rates. With the increase of dose rate, the same target images become brighter. Under the same dose rate, the radiation effect in bright area is lower than that in dark area. Under different dose rates, the higher the dose rate is, the worse the radiation effect will be in both bright and dark areas. And the standard deviations of bright and dark areas become greater. Furthermore, through the progressive degradation analysis of the captured image, experimental results demonstrate that the attenuation of signal to noise ratio (SNR) versus radiation time is not obvious at the same dose rate, and the degradation is more and more serious with increasing dose rate. Additionally, the decrease rate of SNR at 20.0, 50.0 and 100.0 Gy/h is far greater than that at 1.0 and 10.0 Gy/h. Even so, we confirm that the HD industrial camera is still working at 10.0 Gy/h during the 8 h of measurements, with a moderate decrease of the SNR (5 dB). The work is valuable and can provide suggestion for camera users in the radiation field.

Statistical modeling for degradation data

CERN Document Server

Lio, Yuhlong; Ng, Hon; Tsai, Tzong-Ru

2017-01-01

This book focuses on the statistical aspects of the analysis of degradation data. In recent years, degradation data analysis has come to play an increasingly important role in different disciplines such as reliability, public health sciences, and finance. For example, information on products’ reliability can be obtained by analyzing degradation data. In addition, statistical modeling and inference techniques have been developed on the basis of different degradation measures. The book brings together experts engaged in statistical modeling and inference, presenting and discussing important recent advances in degradation data analysis and related applications. The topics covered are timely and have considerable potential to impact both statistics and reliability engineering.

Understanding and managing corrosion in nuclear power plants

International Nuclear Information System (INIS)

Johnson, A.B. Jr.; Jarrell, D.B.; Sinha, U.P.; Shah, V.N.

1991-03-01

The main theme of this paper is a concept: understanding and managing corrosion in nuclear power plants. The concept is not new--in various forms the concept has been applied throughout the development and maturing of nuclear technology. However, the concept has frequently not been well conceived and applied. Too often, understanding corrosion has been based on reaction rather than on anticipation. Regulatory and utility industry initiatives are creating a climate and framework for more effective application of the concept. This paper characterizes the framework and provides some illustrations of how the concept is being applied, drawing from work conducted under the Nuclear Plant Aging Research (NPAR) Program, sponsored by the Nuclear Regulatory Commission's (NRCs) Office of Research. Nuclear plants are becoming an increasingly important factor in the national electrical grid. Initiatives are currently underway to extend the operating licenses beyond the current 40-year period and to evaluate advanced reactor designs the feature higher safety factors. Corrosion has not caused a major nuclear accident, but numerous corrosion mechanisms, have degraded nuclear systems and components. New corrosion phenomena continue to appear, and occasionally corrosion phenomena cause reactor shutdowns. Effective application of understanding and managing corrosion is important to safe and economic operation of the nuclear plants and also to public perception of a soundly operated technology. 53 refs., 11 figs., 5 tabs

Differential Nuclear and Mitochondrial DNA Preservation in Post-Mortem Teeth with Implications for Forensic and Ancient DNA Studies

Science.gov (United States)

Higgins, Denice; Rohrlach, Adam B.; Kaidonis, John; Townsend, Grant; Austin, Jeremy J.

2015-01-01

Major advances in genetic analysis of skeletal remains have been made over the last decade, primarily due to improvements in post-DNA-extraction techniques. Despite this, a key challenge for DNA analysis of skeletal remains is the limited yield of DNA recovered from these poorly preserved samples. Enhanced DNA recovery by improved sampling and extraction techniques would allow further advancements. However, little is known about the post-mortem kinetics of DNA degradation and whether the rate of degradation varies between nuclear and mitochondrial DNA or across different skeletal tissues. This knowledge, along with information regarding ante-mortem DNA distribution within skeletal elements, would inform sampling protocols facilitating development of improved extraction processes. Here we present a combined genetic and histological examination of DNA content and rates of DNA degradation in the different tooth tissues of 150 human molars over short-medium post-mortem intervals. DNA was extracted from coronal dentine, root dentine, cementum and pulp of 114 teeth via a silica column method and the remaining 36 teeth were examined histologically. Real time quantification assays based on two nuclear DNA fragments (67 bp and 156 bp) and one mitochondrial DNA fragment (77 bp) showed nuclear and mitochondrial DNA degraded exponentially, but at different rates, depending on post-mortem interval and soil temperature. In contrast to previous studies, we identified differential survival of nuclear and mtDNA in different tooth tissues. Futhermore histological examination showed pulp and dentine were rapidly affected by loss of structural integrity, and pulp was completely destroyed in a relatively short time period. Conversely, cementum showed little structural change over the same time period. Finally, we confirm that targeted sampling of cementum from teeth buried for up to 16 months can provide a reliable source of nuclear DNA for STR-based genotyping using standard

Insulin-induced translocation of IR to the nucleus in insulin responsive cells requires a nuclear translocation sequence.

Science.gov (United States)

Kesten, Dov; Horovitz-Fried, Miriam; Brutman-Barazani, Tamar; Sampson, Sanford R

2018-04-01

Insulin binding to its cell surface receptor (IR) activates a cascade of events leading to its biological effects. The Insulin-IR complex is rapidly internalized and then is either recycled back to the plasma membrane or sent to lysosomes for degradation. Although most of the receptor is recycled or degraded, a small amount may escape this pathway and migrate to the nucleus of the cell where it might be important in promulgation of receptor signals. In this study we explored the mechanism by which insulin induces IR translocation to the cell nucleus. Experiments were performed cultured L6 myoblasts, AML liver cells and 3T3-L1 adipocytes. Insulin treatment induced a rapid increase in nuclear IR protein levels within 2 to 5 min. Treatment with WGA, an inhibitor of nuclear import, reduced insulin-induced increases nuclear IR protein; IR was, however, translocated to a perinuclear location. Bioinformatics tools predicted a potential nuclear localization sequence (NLS) on IR. Immunofluorescence staining showed that a point mutation on the predicted NLS blocked insulin-induced IR nuclear translocation. In addition, blockade of nuclear IR activation in isolated nuclei by an IR blocking antibody abrogated insulin-induced increases in IR tyrosine phosphorylation and nuclear PKCδ levels. Furthermore, over expression of mutated IR reduced insulin-induced glucose uptake and PKB phosphorylation. When added to isolated nuclei, insulin induced IR phosphorylation but had no effect on nuclear IR protein levels. These results raise questions regarding the possible role of nuclear IR in IR signaling and insulin resistance. Copyright © 2018 Elsevier B.V. All rights reserved.

Nuclear technology and beekeeping industry: much more than atoms and bees; Tecnologia nuclear y apicultura: mucho mas que atomos y abejas

Energy Technology Data Exchange (ETDEWEB)

Rapisarda, Vicenzo M; Hussein, Ana M [Comision Nacional de Energia Atomica, Ezeiza (Argentina). Dept. de Aplicaciones Tecnologicas y Agropecuarias

2002-06-01

Argentine beekeeping industry is the first honey world exporter and the third honey world producer. At the present work, the authors try to show why nuclear technology is one of the best tools for beekeepers to reach health and quality standards required by national and international organisations. Irradiation from Cobalt 60 aim to fight against American foul brood, European foul brood and Chalk brood, besides it is such a good mechanism to degradate acaricides residuals in wax which were used in order to kill Varroa jacobsoni Oud. During the last 30 years, studies have demonstrated honey bees are wonderful sentinel species which represent an incomparable help to nuclear activity through environmental monitoring. Nuclear energy, health care, commercial affairs and environment meet together at Ezeiza Atomic Center, where many developments have been done and new projects are carried out. (author)

Sono-catalytic degradation of organic compounds

International Nuclear Information System (INIS)

Navarro, N.

2012-01-01

Unlike aqueous effluents from the PUREX process, aqueous effluents from advanced separation processes developed to separate the minor actinides (Am, Cm) contain organic reagents in large amounts. To minimize the impact of these organic compounds on the next steps of the process, and to respect standard discharges, it is necessary to develop new techniques of degradation of organic compounds. Sono-chemistry appears as a very promising solution to eliminate organic species in aqueous nuclear effluents. Indeed, the propagation of an ultrasonic wave in a liquid medium induces the appearance of cavitation bubbles which will quickly grow and implode, causing local conditions and extreme temperatures and pressures. Each cavitation bubble can then be considered as a microreactor at high temperature and high pressure able to destroy organic molecules without the addition of specific reagents. The first studies on the effect of ultrasonic frequency on sono-luminescence and sono-lysis of formic acid have shown that the degradation of formic acid occurs at the bubble/liquid interface. The most striking difference between low-frequency and high-frequency ultrasound is that the sono-lysis of HCOOH at high ultrasonic frequencies initiates secondary reactions not observed at 20 kHz. However, despite a much higher sono-chemical activity at high frequency, highly concentrated carboxylic acids in the aqueous effluents from advanced separation processes cannot be destroyed by ultrasound alone. To increase the efficiency of sono-chemical reactions, the addition of supported platinum catalysts has been studied. In these conditions, an increase of the kinetics of destruction of carboxylic acids such as oxalic acid is observed. (author) [fr

Extensions and applications of degradation modeling

International Nuclear Information System (INIS)

Hsu, F.; Subudhi, M.; Samanta, P.K.; Vesely, W.E.

1991-01-01

Component degradation modeling being developed to understand the aging process can have many applications with potential advantages. Previous work has focused on developing the basic concepts and mathematical development of a simple degradation model. Using this simple model, times of degradations and failures occurrences were analyzed for standby components to detect indications of aging and to infer the effectiveness of maintenance in preventing age-related degradations from transforming to failures. Degradation modeling approaches can have broader applications in aging studies and in this paper, the authors discuss some of the extensions and applications of degradation modeling. The extensions and applications of the degradation modeling approaches discussed are: (a) theoretical developments to study reliability effects of different maintenance strategies and policies, (b) relating aging-failure rate to degradation rate, and (c) application to a continuously operating component

Summary of nuclear plant aging research at Oak Ridge National Laboratory

International Nuclear Information System (INIS)

Eissenberg, D.M.

1991-01-01

Oak Ridge National Laboratory (ORNL) has been a major contributor to the Nuclear Regulatory Commission (NRC) Nuclear Plant Aging Research Program since its inception. The research at ORNL has consisted primarily of the preparation of comprehensive aging assessments and other studies of safety related and other components and systems. The components and systems have been identified and prioritized based on risk considerations, as well as by operating experience. In each case, ORNL has been preparing a Phase 1 assessment which summarizes design features, operating conditions, and stressors which lead to degradation and failure; identified parameters which could be used to detect, trend and differentiate the degradations; and proposed potential inspection, surveillance, and monitoring methods which could be applied to the parameters. Where appropriate, Phase 2 assessments have been prepared, which verify and recommend inspection, surveillance and monitoring methods based on vendor information, laboratory and field tests, and in-situ inspections and tests. Finally, Phase 3 assessments are prepared which provide recommendations regarding implementing the inspection, surveillance and monitoring methods, and provide recommendations regarding criteria to be applied. Other activities include providing assistance to NRC/Nuclear Regulatory Research and regional offices as requested, and participation in ASME and IEEE codes and standards

Development of a simple model for the simultaneous degradation of concrete and clay in contact

International Nuclear Information System (INIS)

Neretnieks, Ivars

2014-01-01

Highlights: • The rate at which concrete and bentonite in contact degrade each other is modelled. • In portlandite and bentonite receding degradation fronts develop and move. • The model results compare well with results from complex models. - Abstract: In nuclear waste repositories concrete and bentonite are used, sometimes in contact with each other. The rate of mutual degradation of concrete and bentonite by alkaline fluids from concrete is explored using a simple model. The model considers dissolution of a soluble compound in the concrete (e.g. portlandite), which is gradually dissolved as the solubilised hydroxide and the cation(s) diffuse towards and into the bentonite in which smectite degrades by interaction with the solutes. Accounting for only the diffusion resistances in concrete and clay, the solubility of the concrete compound and the hydroxide consumption capacity of the smectite, results in a very simple analytical model. The model is tested against several published modelling results that account for reaction kinetics, reactive surface, and equilibrium data for tens to many tens of different secondary minerals. In the models that include several specified minerals often assumptions need to be made on which minerals can form. This introduces subjective assumptions. The degradation rates using the simple model are within the range of results obtained by the complex models. In the studies of the data used in these models it was found that the uncertainties in thermodynamic data are considerable and can give contradictory information on under what conditions smectite degrades. Some smectite models and thermodynamic data suggest that smectite will transform to other minerals spontaneously if there were no kinetic restrictions

An approach to safety problems relating to ageing of nuclear power plant components

International Nuclear Information System (INIS)

Conte, M.; Deletre, G.; Henry, J.Y.; Le Meur, M.

1989-10-01

The safety of nuclear power plants, in France, is discussed. The attention is focused on the ageing phenomena, as a potential cause of the degradation of the systems functional capabilities. The allowance for ageing in design and its importance on safety, are analyzed. The understanding of phenomena relating to ageing and the components surveillance, are considered. As the effective ageing on the components of nuclear power plants is not fully understood, technical improvements and more accurate analysis are required

Radiation effects issues related to US DOE site remediation and nuclear waste storage

International Nuclear Information System (INIS)

Weber, W.J.; Ewing, R.C.

1994-10-01

Site restoration activities at DOE facilities and the permanent disposal of nuclear waste generated at the same DOE facilities involve working with and within various types and levels of radiation fields. Radionuclide decay and the associated radiation fields lead to physical and chemical changes that can degrade or enhance material properties. This paper reviews the impact of radiation fields on site restoration activities and on the release rate of radionuclides to the biosphere from nuclear waste forms

Assessment and management of aging of nuclear power plant safety-related structures

International Nuclear Information System (INIS)

Naus, D.J.; Graves, H.L. III; Ellingwood, B.R.

2003-01-01

Background information and data have been developed for improving existing and developing new methods to assist in quantifying the effects of age-related degradation on the performance of nuclear power plant (NPP) safety-related structures. Factors that can lead to age-related degradation of safety-related structures are identified and their manifestations described. Current regulatory testing and inspection requirements are reviewed and a summary of degradation experience presented. Techniques commonly used to inspect NPP concrete structures to assess and quantify age-related degradation are summarized. An approach for conduct of condition assessments of structures in NPPs is presented. Criteria, based primarily on visual indications, are provided for use in classification and assessment of concrete degradation. Materials and techniques for repair of degraded structures are noted and guidance provided on repair options available for various forms of degradation. A probabilistic methodology for condition assessment and reliability-based life prediction has been developed and applied to structures subject to combinations of structural load processes and to structural systems. The methodology has also been used to investigate optimization of in-service inspection and maintenance strategies to maintain failure probability below a specified target value as well as to minimize costs. Fragility assessments involving analytical solutions and finite-element methods have been utilized to predict the effect of aging degradation on structural component performance. (author)

Microbial degradation of low-level radioactive waste. Volume 2, Annual report for FY 1994

International Nuclear Information System (INIS)

Rogers, R.D.; Hamilton, M.A.; Veeh, R.H.; McConnell, J.W. Jr.

1995-08-01

The Nuclear Regulatory Commission stipulates in 10 CFR 61 that disposed low-level radioactive waste (LLW) be stabilized. To provide guidance to disposal vendors and nuclear station waste generators for implementing those requirements, the NRC developed the Technical Position on Waste Form, Revision 1. That document details a specified set of recommended testing procedures and criteria, including several tests for determining the biodegradation properties of waste forms. Cement has been widely used to solidify LLW; however, the resulting waste forms are sometimes susceptible to failure due to the actions of waste constituents, stress, and environment. The purpose of this research program is to develop modified microbial degradation test procedures that will be more appropriate than the existing procedures for evaluating the effects of microbiologically influenced chemical attack on cement-solidified LLW. Groups of microorganisms indigenous to LLW disposal sites are being employed that can metabolically convert organic and inorganic substrates into organic and mineral acids. Such acids aggressively react with cement and can ultimately lead to structural failure. Results over the past year on the application of mechanisms inherent in microbially influenced degradation of cement-based material are the focus of the annual report. Data-validated evidence of the potential for microbially influenced deterioration of cement-solidified LLW and subsequent release of radionuclides has been developed during this study

Applications and extensions of degradation modeling

International Nuclear Information System (INIS)

Hsu, F.; Subudhi, M.; Samanta, P.K.; Vesely, W.E.

1991-01-01

Component degradation modeling being developed to understand the aging process can have many applications with potential advantages. Previous work has focused on developing the basic concepts and mathematical development of a simple degradation model. Using this simple model, times of degradations and failures occurrences were analyzed for standby components to detect indications of aging and to infer the effectiveness of maintenance in preventing age-related degradations from transforming to failures. Degradation modeling approaches can have broader applications in aging studies and in this paper, we discuss some of the extensions and applications of degradation modeling. The application and extension of degradation modeling approaches, presented in this paper, cover two aspects: (1) application to a continuously operating component, and (2) extension of the approach to analyze degradation-failure rate relationship. The application of the modeling approach to a continuously operating component (namely, air compressors) shows the usefulness of this approach in studying aging effects and the role of maintenance in this type component. In this case, aging effects in air compressors are demonstrated by the increase in both the degradation and failure rate and the faster increase in the failure rate compared to the degradation rate shows the ineffectiveness of the existing maintenance practices. Degradation-failure rate relationship was analyzed using data from residual heat removal system pumps. A simple linear model with a time-lag between these two parameters was studied. The application in this case showed a time-lag of 2 years for degradations to affect failure occurrences. 2 refs

Applications and extensions of degradation modeling

Energy Technology Data Exchange (ETDEWEB)

Hsu, F.; Subudhi, M.; Samanta, P.K. [Brookhaven National Lab., Upton, NY (United States); Vesely, W.E. [Science Applications International Corp., Columbus, OH (United States)

1991-12-31

Component degradation modeling being developed to understand the aging process can have many applications with potential advantages. Previous work has focused on developing the basic concepts and mathematical development of a simple degradation model. Using this simple model, times of degradations and failures occurrences were analyzed for standby components to detect indications of aging and to infer the effectiveness of maintenance in preventing age-related degradations from transforming to failures. Degradation modeling approaches can have broader applications in aging studies and in this paper, we discuss some of the extensions and applications of degradation modeling. The application and extension of degradation modeling approaches, presented in this paper, cover two aspects: (1) application to a continuously operating component, and (2) extension of the approach to analyze degradation-failure rate relationship. The application of the modeling approach to a continuously operating component (namely, air compressors) shows the usefulness of this approach in studying aging effects and the role of maintenance in this type component. In this case, aging effects in air compressors are demonstrated by the increase in both the degradation and failure rate and the faster increase in the failure rate compared to the degradation rate shows the ineffectiveness of the existing maintenance practices. Degradation-failure rate relationship was analyzed using data from residual heat removal system pumps. A simple linear model with a time-lag between these two parameters was studied. The application in this case showed a time-lag of 2 years for degradations to affect failure occurrences. 2 refs.

Applications and extensions of degradation modeling

Energy Technology Data Exchange (ETDEWEB)

Hsu, F.; Subudhi, M.; Samanta, P.K. (Brookhaven National Lab., Upton, NY (United States)); Vesely, W.E. (Science Applications International Corp., Columbus, OH (United States))

1991-01-01

Component degradation modeling being developed to understand the aging process can have many applications with potential advantages. Previous work has focused on developing the basic concepts and mathematical development of a simple degradation model. Using this simple model, times of degradations and failures occurrences were analyzed for standby components to detect indications of aging and to infer the effectiveness of maintenance in preventing age-related degradations from transforming to failures. Degradation modeling approaches can have broader applications in aging studies and in this paper, we discuss some of the extensions and applications of degradation modeling. The application and extension of degradation modeling approaches, presented in this paper, cover two aspects: (1) application to a continuously operating component, and (2) extension of the approach to analyze degradation-failure rate relationship. The application of the modeling approach to a continuously operating component (namely, air compressors) shows the usefulness of this approach in studying aging effects and the role of maintenance in this type component. In this case, aging effects in air compressors are demonstrated by the increase in both the degradation and failure rate and the faster increase in the failure rate compared to the degradation rate shows the ineffectiveness of the existing maintenance practices. Degradation-failure rate relationship was analyzed using data from residual heat removal system pumps. A simple linear model with a time-lag between these two parameters was studied. The application in this case showed a time-lag of 2 years for degradations to affect failure occurrences. 2 refs.

Shutdown and degradation: Space computers for nuclear application, verification of radiation hardness. Final report

International Nuclear Information System (INIS)

Eichhorn, E.; Gerber, V.; Schreyer, P.

1995-01-01

(1) Employment of those radiation hard electronics which are already known in military and space applications. (2) The experience in space-flight shall be used to investigate nuclear technology areas, for example, by using space electronics to prove the range of applications in nuclear radiating environments. (3) Reproduction of a computer developed for telecommunication satellites; proof of radiation hardness by radiation tests. (4) At 328 Krad (Si) first failure of radiation tolerant devices with 100 Krad (Si) hardness guaranteed. (5) Using radiation hard devices of the same type you can expect applications at doses of greater than 1 Mrad (Si). Electronic systems applicable for radiation categories D, C and lower part of B for manipulators, vehicles, underwater robotics. (orig.) [de

Nuclear export signal of PRRSV NSP1α is necessary for type I IFN inhibition

International Nuclear Information System (INIS)

Chen, Zhi; Liu, Shaoning; Sun, Wenbo; Chen, Lei; Yoo, Dongwan; Li, Feng; Ren, Sufang; Guo, Lihui; Cong, Xiaoyan; Li, Jun; Zhou, Shun; Wu, Jiaqiang

2016-01-01

The nonstructural protein 1α (NSP1α) of porcine reproductive and respiratory syndrome virus (PRRSV) is a nucleo-cytoplasmic protein that suppresses the production of type I interferon (IFN). In this study, we investigated the relationship between the subcellular distribution of NSP1α and its inhibition of type I IFN. NSP1α was found to contain the classical nuclear export signal (NES) and NSP1α nuclear export was CRM-1-mediated. NSP1α was shuttling between the nucleus and cytoplasm. We also showed that the nuclear export of NSP1α was necessary for its ability for type I IFN inhibition. NSP1α was also found to interact with CBP, which implies a possible mechanism of CBP degradation by NSP1α. Taken together, our results describe a novel mechanism of PRRSV NSP1α for type I IFN inhibition and suppression of the host innate antiviral response. - Highlights: •NSP1α contains the NES and NSP1α nuclear export was CRM-1-mediated. •NSP1α was shuttling between the nucleus and cytoplasm continuously. •The nuclear export of NSP1α was necessary for its ability for type I IFN inhibition. •NSP1α interacts with CBP, which implies the mechanism of CBP degradation by NSP1α.

Nuclear export signal of PRRSV NSP1α is necessary for type I IFN inhibition

Energy Technology Data Exchange (ETDEWEB)

Chen, Zhi [Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Sangyuan Road No. 8, Jinan 250100 (China); Liu, Shaoning [Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Sangyuan Road No. 8, Jinan 250100 (China); Shandong Institute of Veterinary Drug Quality Inspection, Shandong Key Laboratory for Quality Safety Monitoring and Risk Assessment of Animal Products, Huaicun Street No. 68, Jinan 250722, Shandong Province (China); Sun, Wenbo; Chen, Lei [Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Sangyuan Road No. 8, Jinan 250100 (China); Yoo, Dongwan [Department of Pathobiology, University of Illinois at Urbana-Champaign, 2001 South Lincoln Ave, Urbana, IL 61802 (United States); Li, Feng [Department of Biology and Microbiology, Department of Veterinary and Biomedical Sciences, South Dakota State University, Brookings, SD 57007 (United States); Ren, Sufang; Guo, Lihui; Cong, Xiaoyan; Li, Jun [Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Sangyuan Road No. 8, Jinan 250100 (China); Zhou, Shun [College of marine science and engineering, Qingdao Agricultural University, Changcheng Road No. 700, Qingdao 266109 (China); Wu, Jiaqiang, E-mail: wujiaqiang2000@sina.com [Shandong Key Laboratory of Animal Disease Control and Breeding, Institute of Animal Science and Veterinary Medicine, Shandong Academy of Agricultural Sciences, Sangyuan Road No. 8, Jinan 250100 (China); and others

2016-12-15

The nonstructural protein 1α (NSP1α) of porcine reproductive and respiratory syndrome virus (PRRSV) is a nucleo-cytoplasmic protein that suppresses the production of type I interferon (IFN). In this study, we investigated the relationship between the subcellular distribution of NSP1α and its inhibition of type I IFN. NSP1α was found to contain the classical nuclear export signal (NES) and NSP1α nuclear export was CRM-1-mediated. NSP1α was shuttling between the nucleus and cytoplasm. We also showed that the nuclear export of NSP1α was necessary for its ability for type I IFN inhibition. NSP1α was also found to interact with CBP, which implies a possible mechanism of CBP degradation by NSP1α. Taken together, our results describe a novel mechanism of PRRSV NSP1α for type I IFN inhibition and suppression of the host innate antiviral response. - Highlights: •NSP1α contains the NES and NSP1α nuclear export was CRM-1-mediated. •NSP1α was shuttling between the nucleus and cytoplasm continuously. •The nuclear export of NSP1α was necessary for its ability for type I IFN inhibition. •NSP1α interacts with CBP, which implies the mechanism of CBP degradation by NSP1α.

Quantitative assessment of the degradation of aggregated TDP-43 mediated by the ubiquitin proteasome system and macroautophagy.

Science.gov (United States)

Cascella, Roberta; Fani, Giulia; Capitini, Claudia; Rusmini, Paola; Poletti, Angelo; Cecchi, Cristina; Chiti, Fabrizio

2017-12-01

Amyotrophic lateral sclerosis and frontotemporal lobar degeneration with ubiquitin-positive inclusions are neurodegenerative disorders that share the cytosolic deposition of TDP-43 (TAR DNA-binding protein 43) in the CNS. TDP-43 is well known as being actively degraded by both the proteasome and macroautophagy. The well-documented decrease in the efficiency of these clearance systems in aging and neurodegeneration, as well as the genetic evidence that many of the familial forms of TDP-43 proteinopathies involve genes that are associated with them, suggest that a failure of these protein degradation systems is a major factor that contributes to the onset of TDP-43-associated disorders. Here, we inserted preformed human TDP-43 aggregates in the cytosol of murine NSC34 and N2a cells in diffuse form and observed their degradation under conditions in which exogenous TDP-43 is not expressed and endogenous nuclear TDP-43 is not recruited, thereby allowing a time zero to be established in TDP-43 degradation and to observe its disposal kinetically and analytically. TDP-43 degradation was observed in the absence and presence of selective inhibitors and small interfering RNAs against the proteasome and autophagy. We found that cytosolic diffuse aggregates of TDP-43 can be distinguished in 3 different classes on the basis of their vulnerability to degradation, which contributed to the definition-with previous reports-of a total of 6 distinct classes of misfolded TDP-43 species that range from soluble monomer to undegradable macroaggregates. We also found that the proteasome and macroautophagy-degradable pools of TDP-43 are fully distinguishable, rather than in equilibrium between them on the time scale required for degradation, and that a significant crosstalk exists between the 2 degradation processes.-Cascella, R., Fani, G., Capitini, C., Rusmini, P., Poletti, A., Cecchi, C., Chiti, F. Quantitative assessment of the degradation of aggregated TDP-43 mediated by the ubiquitin

Nuclear Excitations by Antiprotons and Antiprotonic Atoms

CERN Multimedia

2002-01-01

The proposal aims at the investigation of nuclear excitations following the absorption and annihilation of stopped antiprotons in heavier nuclei and at the same time at the study of the properties of antiprotonic atoms. The experimental arrangement will consist of a scintillation counter telescope for the low momentum antiproton beam from LEAR, a beam degrader, a pion multiplicity counter, a monoisotopic target and Ge detectors for radiation and charged particles. The data are stored by an on-line computer.\\\\ \\\\ The Ge detectors register antiprotonic x-rays and nuclear @g-rays which are used to identify the residual nucleus and its excitation and spin state. Coincidences between the two detectors will indicate from which quantum state the antiprotons are absorbed and to which nuclear states the various reactions are leading. The measured pion multiplicity characterizes the annihilation process. Ge&hyphn. and Si-telescopes identify charged particles and determine their energies.\\\\ \\\\ The experiment will gi...

Big data analysis of public acceptance of nuclear power in Korea

Energy Technology Data Exchange (ETDEWEB)

Roh, Seung Kook [Policy Research Division, Korea Atomic Energy Research Institute (KAERI), Daejeon (Korea, Republic of)

2017-06-15

Public acceptance of nuclear power is important for the government, the major stakeholder of the industry, because consensus is required to drive actions. It is therefore no coincidence that the governments of nations operating nuclear reactors are endeavoring to enhance public acceptance of nuclear power, as better acceptance allows stable power generation and peaceful processing of nuclear wastes produced from nuclear reactors. Past research, however, has been limited to epistemological measurements using methods such as the Likert scale. In this research, we propose big data analysis as an attractive alternative and attempt to identify the attitudes of the public on nuclear power. Specifically, we used common big data analyses to analyze consumer opinions via SNS (Social Networking Services), using keyword analysis and opinion analysis. The keyword analysis identified the attitudes of the public toward nuclear power. The public felt positive toward nuclear power when Korea successfully exported nuclear reactors to the United Arab Emirates. With the Fukushima accident in 2011 and certain supplier scandals in 2012, however, the image of nuclear power was degraded and the negative image continues. It is recommended that the government focus on developing useful businesses and use cases of nuclear power in order to improve public acceptance.

Big data analysis of public acceptance of nuclear power in Korea

International Nuclear Information System (INIS)

Roh, Seung Kook

2017-01-01

Public acceptance of nuclear power is important for the government, the major stakeholder of the industry, because consensus is required to drive actions. It is therefore no coincidence that the governments of nations operating nuclear reactors are endeavoring to enhance public acceptance of nuclear power, as better acceptance allows stable power generation and peaceful processing of nuclear wastes produced from nuclear reactors. Past research, however, has been limited to epistemological measurements using methods such as the Likert scale. In this research, we propose big data analysis as an attractive alternative and attempt to identify the attitudes of the public on nuclear power. Specifically, we used common big data analyses to analyze consumer opinions via SNS (Social Networking Services), using keyword analysis and opinion analysis. The keyword analysis identified the attitudes of the public toward nuclear power. The public felt positive toward nuclear power when Korea successfully exported nuclear reactors to the United Arab Emirates. With the Fukushima accident in 2011 and certain supplier scandals in 2012, however, the image of nuclear power was degraded and the negative image continues. It is recommended that the government focus on developing useful businesses and use cases of nuclear power in order to improve public acceptance

Big Data Analysis of Public Acceptance of Nuclear Power in Korea

Directory of Open Access Journals (Sweden)

Seungkook Roh

2017-06-01

Full Text Available Public acceptance of nuclear power is important for the government, the major stakeholder of the industry, because consensus is required to drive actions. It is therefore no coincidence that the governments of nations operating nuclear reactors are endeavoring to enhance public acceptance of nuclear power, as better acceptance allows stable power generation and peaceful processing of nuclear wastes produced from nuclear reactors. Past research, however, has been limited to epistemological measurements using methods such as the Likert scale. In this research, we propose big data analysis as an attractive alternative and attempt to identify the attitudes of the public on nuclear power. Specifically, we used common big data analyses to analyze consumer opinions via SNS (Social Networking Services, using keyword analysis and opinion analysis. The keyword analysis identified the attitudes of the public toward nuclear power. The public felt positive toward nuclear power when Korea successfully exported nuclear reactors to the United Arab Emirates. With the Fukushima accident in 2011 and certain supplier scandals in 2012, however, the image of nuclear power was degraded and the negative image continues. It is recommended that the government focus on developing useful businesses and use cases of nuclear power in order to improve public acceptance.

NRC Information Notice No. 93-25: Electrical penetration assembly degradation

International Nuclear Information System (INIS)

Grimes, B.K.

1993-01-01

In July 1987 and in October 1989, the licensee for the Trojan Nuclear Plant, the Portland and General Electric Company, reported problems with containment air leakage through its Bunker-Ramo electrical penetration assembly seals. In July and August 1991, the NRC inspected the use of containment electrical penetration assembly seals at Trojan and concluded that the licensee had not established an effective program for trending and evaluating electrical penetration assembly seal leakage. On October 28, 1991, while the plant was in a refueling outage, the licensee reported to the NRC that in the originally installed electrical penetration assemblies, the seal (polyurethane) and lubricant (Celvacen or Glycerin) materials were inappropriate for the application. The licensee concluded that these materials may cause seal degradation and that the seals may become degraded if subjected to design basis accident conditions for moisture or temperature. The licensee replaced the electrical penetration assembly seal with an environmentally qualified ethylene propylene rubber seal and added a silicone rubber backup O-ring to the outer face of each electrical penetration assembly module. The licensee subsequently replaced all the Bunker-Ramo electrical penetration assemblies with Conax assemblies

Structural Health Monitoring of Nuclear Spent Fuel Storage Facilities

Energy Technology Data Exchange (ETDEWEB)

Yu, Lingyu

2018-04-10

Interim storage of spent nuclear fuel from reactor sites has gained additional importance and urgency for resolving waste-management-related technical issues. To ensure that nuclear power remains clean energy, monitoring has been identified by DOE as a high priority cross-cutting need, necessary to determine and predict the degradation state of the systems, structures, and components (SSCs) important to safety (ITS). Therefore, nondestructive structural condition monitoring becomes a need to be installed on existing or to be integrated into future storage system to quantify the state of health or to guarantee the safe operation of nuclear power plants (NPPs) during their extended life span. In this project, the lead university and the collaborating national laboratory teamed to develop a nuclear structural health monitoring (n-SHM) system based on in-situ piezoelectric sensing technologies that can monitor structural degradation and aging for nuclear spent fuel DCSS and similar structures. We also aimed to identify and quantify possible influences of nuclear spent fuel environment (temperature and radiation) to the piezoelectric sensor system and come up with adequate solutions and guidelines therefore. We have therefore developed analytical model for piezoelectric based n-SHM methods, with considerations of temperature and irradiation influence on the model of sensing and algorithms in acoustic emission (AE), guided ultrasonic waves (GUW), and electromechanical impedance spectroscopy (EMIS). On the other side, experimentally the temperature and irradiation influence on the piezoelectric sensors and sensing capabilities were investigated. Both short-term and long-term irradiation investigation with our collaborating national laboratory were performed. Moreover, we developed multi-modal sensing, validated in laboratory setup, and conducted the testing on the We performed multi-modal sensing development, verification and validation tests on very complex structures

Managing aging in nuclear power plants: Insights from NRC's Maintenance Team Inspection reports

International Nuclear Information System (INIS)

Fresco, A.; Subudhi, M.

1992-01-01

A plant's maintenance program is the principal vehicle through which age-related degradation is managed. From 1988 to 1991, the NRC evaluated the maintenance program of every nuclear power plant in the United States. Forty-four out of a total of sixty-seven of the reports issued on these in-depth team inspections have been reviewed for insights into the strengths and weaknesses of the programs as related to the need to understand and manage the effects of aging on nuclear plant structures, systems, and components (SSCs). Relevant information has been extracted from these inspection reports sorted into several categories; including Specific Aging Insights, Preventive Maintenance, Predictive Maintenance and Condition Monitoring, Post Maintenance Testing, Failure Trending, Root Cause Analysis and Usage of Probabilistic Risk Assessment in the Maintenance Process. Specific examples of inspection and monitoring techniques successfully used by utilities to detect degradation due to aging have been identified

A survey of repair practices for nuclear power plant containment metallic pressure boundaries

Energy Technology Data Exchange (ETDEWEB)

Oland, C.B.; Naus, D.J. [Oak Ridge National Lab., TN (United States)

1998-05-01

The Nuclear Regulatory Commission has initiated a program at the Oak Ridge National Laboratory to provide assistance in their assessment of the effects of potential degradation on the structural integrity and leaktightness of metal containment vessels and steel liners of concrete containments in nuclear power plants. One of the program objectives is to identify repair practices for restoring metallic containment pressure boundary components that have been damaged or degraded in service. This report presents issues associated with inservice condition assessments and continued service evaluations and identifies the rules and requirements for the repair and replacement of nonconforming containment pressure boundary components by welding or metal removal. Discussion topics include base and welding materials, welding procedure and performance qualifications, inspection techniques, testing methods, acceptance criteria, and documentation requirements necessary for making acceptable repairs and replacements so that the plant can be returned to a safe operating condition.

A survey of repair practices for nuclear power plant containment metallic pressure boundaries

International Nuclear Information System (INIS)

Oland, C.B.; Naus, D.J.

1998-05-01

The Nuclear Regulatory Commission has initiated a program at the Oak Ridge National Laboratory to provide assistance in their assessment of the effects of potential degradation on the structural integrity and leaktightness of metal containment vessels and steel liners of concrete containments in nuclear power plants. One of the program objectives is to identify repair practices for restoring metallic containment pressure boundary components that have been damaged or degraded in service. This report presents issues associated with inservice condition assessments and continued service evaluations and identifies the rules and requirements for the repair and replacement of nonconforming containment pressure boundary components by welding or metal removal. Discussion topics include base and welding materials, welding procedure and performance qualifications, inspection techniques, testing methods, acceptance criteria, and documentation requirements necessary for making acceptable repairs and replacements so that the plant can be returned to a safe operating condition

Characterization of hydrocarbon-degrading and biosurfactant-producing Pseudomonas sp. P-1 strain as a potential tool for bioremediation of petroleum-contaminated soil.

Science.gov (United States)

Pacwa-Płociniczak, Magdalena; Płaza, Grażyna Anna; Poliwoda, Anna; Piotrowska-Seget, Zofia

2014-01-01

The Pseudomonas sp. P-1 strain, isolated from heavily petroleum hydrocarbon-contaminated soil, was investigated for its capability to degrade hydrocarbons and produce a biosurfactant. The strain degraded crude oil, fractions A5 and P3 of crude oil, and hexadecane (27, 39, 27 and 13% of hydrocarbons added to culture medium were degraded, respectively) but had no ability to degrade phenanthrene. Additionally, the presence of gene-encoding enzymes responsible for the degradation of alkanes and naphthalene in the genome of the P-1 strain was reported. Positive results of blood agar and methylene blue agar tests, as well as the presence of gene rhl, involved in the biosynthesis of rhamnolipid, confirmed the ability of P-1 for synthesis of glycolipid biosurfactant. 1H and 13C nuclear magnetic resonance, Fourier transform infrared spectrum and mass spectrum analyses indicated that the extracted biosurfactant was affiliated with rhamnolipid. The results of this study indicate that the P-1 and/or biosurfactant produced by this strain have the potential to be used in bioremediation of hydrocarbon-contaminated soils.

Analysis of the Degradation of MOSFETs in Switching Mode Power Supply by Characterizing Source Oscillator Signals

Directory of Open Access Journals (Sweden)

Xueyan Zheng

2013-01-01

Full Text Available Switching Mode Power Supply (SMPS has been widely applied in aeronautics, nuclear power, high-speed railways, and other areas related to national strategy and security. The degradation of MOSFET occupies a dominant position in the key factors affecting the reliability of SMPS. MOSFETs are used as low-voltage switches to regulate the DC voltage in SMPS. The studies have shown that die-attach degradation leads to an increase in on-state resistance due to its dependence on junction temperature. On-state resistance is the key indicator of the health of MOSFETs. In this paper, an online real-time method is presented for predicting the degradation of MOSFETs. First, the relationship between an oscillator signal of source and on-state resistance is introduced. Because oscillator signals change when they age, a feature is proposed to capture these changes and use them as indicators of the state of health of MOSFETs. A platform for testing characterizations is then established to monitor oscillator signals of source. Changes in oscillator signal measurement were observed with aged on-state resistance as a result of die-attach degradation. The experimental results demonstrate that the method is efficient. This study will enable a method to predict the failure of MOSFETs to be developed.

Bacteria-mediated bisphenol A degradation.

Science.gov (United States)

Zhang, Weiwei; Yin, Kun; Chen, Lingxin

2013-07-01

Bisphenol A (BPA) is an important monomer in the manufacture of polycarbonate plastics, food cans, and other daily used chemicals. Daily and worldwide usage of BPA and BPA-contained products led to its ubiquitous distribution in water, sediment/soil, and atmosphere. Moreover, BPA has been identified as an environmental endocrine disruptor for its estrogenic and genotoxic activity. Thus, BPA contamination in the environment is an increasingly worldwide concern, and methods to efficiently remove BPA from the environment are urgently recommended. Although many factors affect the fate of BPA in the environment, BPA degradation is mainly depended on the metabolism of bacteria. Many BPA-degrading bacteria have been identified from water, sediment/soil, and wastewater treatment plants. Metabolic pathways of BPA degradation in specific bacterial strains were proposed, based on the metabolic intermediates detected during the degradation process. In this review, the BPA-degrading bacteria were summarized, and the (proposed) BPA degradation pathway mediated by bacteria were referred.

An approach to nuclear-power-plant life management

International Nuclear Information System (INIS)

Vojvodic Tuma, J.; Celin, R.; Udovc, M.; Bundara, B.; Zabric, I.

2007-01-01

The plant life of a nuclear power plant (NPP) depends on degradation processes and ageing. Degradation is a deterioration phenomenon that can lead to component failure or limit the life of a component or the NPP itself. Ageing describes a continuous time or operational degradation of materials due to operational conditions, which include both normal and operating conditions. As a result of ageing degradation the state of the NPP or component can vary throughout the operating life. The degradation mechanisms for metallic components are general and local corrosion, erosion/corrosion, fatigue, corrosion fatigue, material changes due to irradiation and temperature, creep and wear. All the components of an NPP are subject to ageing, which may lead to the degradation of the physical barriers and redundant components, resulting in an increased probability of common-cause failures. The aims of NPP ageing management are to ensure that the necessary safety margins, adequate reliability and unforeseen and uncontrolled ageing of critical components do not shorten the NPP's lifetime. For the reasons stated above, plans are necessary to maintain the NPP in a state of high reliability. These are plans for an assessment of the life of the components that cannot be readily replaced, plans for operating life assessment or the planned replacement of major components where economic considerations will largely condition whether replacement or decommissioning should be pursued and plans for maintenance and replacements so that outages and delays can be minimised. In this paper some aspects of the process of NPP life management will be presented. (author)

Proceedings of the second international conference on advances in nuclear materials: abstract booklet and souvenir

International Nuclear Information System (INIS)

2011-01-01

Nuclear materials form special class of materials which either act as fuel for the nuclear reactors or form the structure of the reactors and the allied systems. The topics covered in this conference are: materials challenges for thermal and fast reactors, technological advances in nuclear fuels and components, materials for future reactors, fuel cycles and materials challenges, materials degradation and life management, advanced materials development, modelling and simulation, advanced materials- II, advanced materials for future reactors, development of advanced fuel and structural materials, zirconium alloy developments, irradiation effects and PIE, advanced nuclear fuels, corrosion and materials characterization. Papers relevant to INIS are indexed separately

IR Laser Ablative Degradation of Poly(phenylene ether sulfone): Deposition of Films Containing Sulfone, Sulfoxide and Sulfide Groups

Czech Academy of Sciences Publication Activity Database

Blazevska-Gilev, J.; Bastl, Zdeněk; Šubrt, Jan; Stopka, Pavel; Pola, Josef

2009-01-01

Roč. 94, č. 2 (2009), s. 196-200 ISSN 0141-3910 R&D Projects: GA AV ČR IAA400720619 Institutional research plan: CEZ:AV0Z40720504; CEZ:AV0Z40400503; CEZ:AV0Z40320502 Keywords : laser ablation * laser-induced degradation * poly(1,4-phenylene ether-sulfone) Subject RIV: CH - Nuclear ; Quantum Chemistry Impact factor: 2.154, year: 2009

Study of PP/montmorillonite composite degradation

International Nuclear Information System (INIS)

Baer, Marcia; Granado, Carlos J.F.

2009-01-01

The objective of this work was to produce composites of PP/sodium bentonite and PP/ organophilic bentonite through melt intercalation and analyze the degradation produced by ultraviolet irradiation. The XRD results showed that the samples of nature bentonite had better interaction with de polymer and produced intercalated nanocomposite. The effect of UV irradiation on degradation was observed after 24 hours of exposition. The samples showed the same photoproducts and at the same proportion until 240 hours of UV exposition; with 480 hours the organophilize bentonite composite showed higher degradation than other ones. The superficial cracks increased with degradation time. The degradation occurs due chromophores impurities presented in the samples, thus samples with sodium clay show higher degradation, and organophilic clay contains ammonium salt that contribute to increase the degradation. (author)

Nuclear Radiation Degradation Study on HD Camera Based on CMOS Image Sensor at Different Dose Rates

Directory of Open Access Journals (Sweden)

Congzheng Wang

2018-02-01

Full Text Available In this work, we irradiated a high-definition (HD industrial camera based on a commercial-off-the-shelf (COTS CMOS image sensor (CIS with Cobalt-60 gamma-rays. All components of the camera under test were fabricated without radiation hardening, except for the lens. The irradiation experiments of the HD camera under biased conditions were carried out at 1.0, 10.0, 20.0, 50.0 and 100.0 Gy/h. During the experiment, we found that the tested camera showed a remarkable degradation after irradiation and differed in the dose rates. With the increase of dose rate, the same target images become brighter. Under the same dose rate, the radiation effect in bright area is lower than that in dark area. Under different dose rates, the higher the dose rate is, the worse the radiation effect will be in both bright and dark areas. And the standard deviations of bright and dark areas become greater. Furthermore, through the progressive degradation analysis of the captured image, experimental results demonstrate that the attenuation of signal to noise ratio (SNR versus radiation time is not obvious at the same dose rate, and the degradation is more and more serious with increasing dose rate. Additionally, the decrease rate of SNR at 20.0, 50.0 and 100.0 Gy/h is far greater than that at 1.0 and 10.0 Gy/h. Even so, we confirm that the HD industrial camera is still working at 10.0 Gy/h during the 8 h of measurements, with a moderate decrease of the SNR (5 dB. The work is valuable and can provide suggestion for camera users in the radiation field.

Potential uses of lead in nuclear waste disposal

International Nuclear Information System (INIS)

Goodwin, F.E.; Pool, K.H.; Westerman, R.E.; Pitman, S.G.; Telander, M.R.

1991-01-01

In order for lead to be considered as a nuclear waste packaging material, it must be shown that it has adequate corrosion resistance, and that it does not degrade the properties of other important structural or barrier elements in the waste package. The present work focused on determining (a) the corrosion resistance of commercial purity (CP) lead and a Pb-1.5% Sb alloy in irradiated, elevated-temperature tuff ground water environments; (b) the resistance of alloy 825, a candidate container alloy, to embrittlement by molten lead; and (c) the resistance of lead and the Pb-Sb alloy to localized (pitting, crevice) corrosion. The test results support the feasibility of using lead in nuclear waste containers

Ordered bulk degradation via autophagy

DEFF Research Database (Denmark)

Dengjel, Jörn; Kristensen, Anders Riis; Andersen, Jens S

2008-01-01

During amino acid starvation, cells undergo macroautophagy which is regarded as an unspecific bulk degradation process. Lately, more and more organelle-specific autophagy subtypes such as reticulophagy, mitophagy and ribophagy have been described and it could be shown, depending on the experimental...... at proteasomal and lysosomal degradation ample cross-talk between the two degradation pathways became evident. Degradation via autophagy appeared to be ordered and regulated at the protein complex/organelle level. This raises several important questions such as: can macroautophagy itself be specific and what...

In vitro degradation of ribosomes.

Science.gov (United States)

Mora, G; Rivas, A

1976-12-01

The cytoplasmic ribosomes from Euglena gracilis var. bacillaris are found to be of two types taking into consideration their stability "in vitro". In the group of unstable ribosomes the large subunit is degraded. The other group apparently does not suffer any degradation under the conditions described. However the RNAs extracted from both types of ribosomes are degraded during sucrose density gradients. The degradation of the largest RNA species has been reported previously, but no comment has been made about the stability of the ribosome itself.

Nuclear magnetic resonance in contemporary art: the case of ''Moon Surface'' by Turcato

Energy Technology Data Exchange (ETDEWEB)

Proietti, Noemi; Di Tullio, Valeria; Capitani, Donatella [CNR, Area della Ricerca di Roma, Magnetic Resonance Laboratory ' ' Annalaura Segre' ' , Istituto di Metodologie Chimiche, Monterotondo (Rome) (Italy); Tomassini, Roberta; Guiso, Marcella [Sapienza Universita di Roma, Dipartimento di Chimica, Rome (Italy)

2013-12-15

Nuclear Magnetic Resonance (NMR) methodologies were applied to characterize the constitutive materials and the state of degradation of a contemporary painting. The investigation was mandatory to plan a suitable restoration. Noninvasive, portable NMR allowed the detection of degraded regions of the painting based on the measurement of longitudinal relaxation time. A few samples were investigated by high resolution solid state NMR and NMR in solution, which allowed us to identify the polyurethane constituting the artefact, to investigate the microstructure in detail, and to assess that the degradation process mostly affected the ethylene units used to cap the polypropylene oxide polymeric chain. As a matter of fact, a shortening of longitudinal relaxation time was accompanied by a degradation of ethylene units. The degradation of the inorganic loading was investigated by {sup 27}Al MAS, which evidenced the absence of penta-coordinated aluminum in degraded samples. (orig.)

Lysosomal degradation of membrane lipids.

Science.gov (United States)

Kolter, Thomas; Sandhoff, Konrad

2010-05-03

The constitutive degradation of membrane components takes place in the acidic compartments of a cell, the endosomes and lysosomes. Sites of lipid degradation are intralysosomal membranes that are formed in endosomes, where the lipid composition is adjusted for degradation. Cholesterol is sorted out of the inner membranes, their content in bis(monoacylglycero)phosphate increases, and, most likely, sphingomyelin is degraded to ceramide. Together with endosomal and lysosomal lipid-binding proteins, the Niemann-Pick disease, type C2-protein, the GM2-activator, and the saposins sap-A, -B, -C, and -D, a suitable membrane lipid composition is required for degradation of complex lipids by hydrolytic enzymes. Copyright 2009 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Study of distillation and degradation of perfluoro polyether

International Nuclear Information System (INIS)

Lopergolo, Lilian Cristine

1997-01-01

Perfluoro-polyethers, PFPE, were first synthesised by Sianesi and collaborators giving rise to a new lubricant oils and greases classes with several applications. Perfluoro polyethers have excellent properties, for instance: high chemical stability and thermal stability, high density, high radiation resistance and excellent lubricating properties. FOMBLIN-Y oil is one of the perfluoro polyethers used as a lubricant in vacuum systems applied in the UF 6 enrichment installations. Due to its excellent properties and for its applications in the nuclear field, IPEN-CNEN/S P had the interest to dominate its production technology with the aim to substitute the commercial FOMBLIN-Y oil used in the national consumption. The FOMBLIN-Y oil synthesis method, adopted in IPEN-CNEN/S P, made by the photooxidation of the hexa fluoro propylene. In this work we study the fraction separation of the national available production with restricted an increased molecular weights which was obtained by fraction distillation in a vacuum according to the ASTM D-1160 norm. We also study the catalytic effect of metals on the thermal stability of perfluoro polyethers. The inertness of perfluoro polyethers at temperatures higher than 300 deg C is strongly affected by presence of some metals. Al and Ti alloys cause fluid degradation at 250 deg C. This degradation is very important because it has a yield increase of the perfluoro polyethers production. (author)

Adaptive Kalman filtering for diagnosis of multiple component degradations

International Nuclear Information System (INIS)

Aumeier, S. E.; Alpay, B.; Lee, J. C.

2005-01-01

We have developed an adaptive Kalman filtering algorithm for the diagnosis of faults or degradations of multiple components in nuclear power plants. We propose to detect the presence and magnitude of the fault(s) through noisy system observations when the measurements indicate significant deviations from predictions. Our diagnostic algorithm uses the measurement residuals, i.e., the difference between the measurements and predictions, to generate a noise input to the uncertain component state in an adaptive Kalman filtering algorithm so that various postulated component transitions or degradations may be statistically represented. The diagnostic algorithm has been tested with a balance of plant (BOP) model of a boiling water reactor (BWR). We have presented a set of algorithms for the detection and diagnosis of component faults of arbitrary magnitude and type within a multi-component system. By analyzing a number of transients including the one example illustrated in the paper, we find that these algorithms are not only capable of determining the correct component fault and magnitude for single components but also they can be used to determine binary faults satisfactorily. Additional study is under way to evaluate the performance of the proposed algorithm including the sensitivity of the diagnostic time to adaptive noise matrix introduced (see equations 7 and 8 illustrated in the paper)

Identification and Assessment of Material Models for Age-Related Degradation of Structures and Passive Components in Nuclear Power Plants

International Nuclear Information System (INIS)

Choi, In Kil; Kim, Min Kyu; Hofmayer, Charles; Braverman, Joseph; Nie, Jinsuo

2009-03-01

This report describes the research effort performed by BNL for the Year 2 scope of work. This research focused on methods that could be used to represent the long-term behavior of materials used at NPPs. To achieve this BNL reviewed time-dependent models which can approximate the degradation effects of the key materials used in the construction of structures and passive components determined to be of interest in the Year 1 effort. The intent was to review the degradation models that would cover the most common time-dependent changes in material properties for concrete and steel components

The Change of the Seebeck Coefficient Due to Neutron Irradiation and Thermal Fatigue of Nuclear Reactor Pressure Vessel Steel and its Application to the Monitoring of Material Degradation

International Nuclear Information System (INIS)

Niffenegger, M.; Reichlin, K.; Kalkhof, D.

2002-05-01

The monitoring of material degradation, that might be caused by neutron irradiation and thermal fatigue, is an important topic in lifetime extension of nuclear power plants. We therefore investigated the application of the Seebeck effect for determining material degradation of common reactor pressure vessel steel. The Seebeck coefficient (SC) of several irradiated Charpy specimens made from Japanese JRQ-steel were measured. The specimens suffered a fluence from 0 up to 4.5 x 10 19 neutrons per cm 2 with energies higher than 1 MeV. The measured changes of the SC within this range were about 500 nV, increasing continuously in the range under investigation. Some indications of saturation appeared at fluencies larger than 4.55 x 10 19 neutrons per cm 2 . We obtained a linear dependency between the SC and the temperature shift ΔT 41 of the Charpy-Energy- Temperature curve which is widely used to characterize material embrittlement. Similar measurements were performed on specimens made from the widely used austenitic steel X6CrNiTi18-10 (according to DIN 1.4541) that were fatigued by applying a cyclic strain amplitude of 0.28%. For this kind of fatigue the observed change of SC was somewhat smaller than for the irradiated specimens. Further investigations were made to quantify the size of the gage volume in which the thermoelectric power is generated. It appeared that the information gathered from a Thermo Electric Power (TEP) measurement is very local. To overcome this problem we propose a novel TEP-method using a Thermoelectric Scanning Microscope (TSM). We finally conclude that the change of the SC has a potential for monitoring of material degradation due to neutron irradiation and thermal fatigue, but it has to be taken into account that several influencing parameters could contribute to the TEP in either an additional or extinguishing manner. A disadvantage of the method is the requirement of a clean surface without any oxide layer. A part of this disadvantage can

Role of recent research in improving check valve reliability at nuclear power plants

International Nuclear Information System (INIS)

Kalsi, M.S.; Horst, C.L.; Wang, J.K.; Sharma, V.

1990-01-01

Check valve failures at nuclear power plants in recent years have led to serious safety concerns, and caused extensive damage to other plant components which had a significant impact on plant availability. In order to understand the failure mechanism and improve the reliability of check valves, a systematic research effort was proposed by Kalsi Engineering, Inc. to U.S. Nuclear Regulatory Commission (NRC). The overall goal of the research was to develop models for predicting the performance and degradation of swing check valves in nuclear power plant systems so that appropriate preventive maintenance or design modifications can be performed to improve the reliability of check valves. Under Phase I of this research, a large matrix of tests was run with instrumented swing check valves to determine the stability of the disc under a variety of upstream flow disturbances, covering a wide range of disc stop positions and flow velocities in two different valve sizes. The goals of Phase II research were to develop predictive models which quantify the anticipated degradation of swing check valves that have flow disturbances closely upstream of the valve and are operating under flow velocities that do not result in full disc opening. This research allows the inspection/maintenance activities to be focussed on those check valves that are more likely to suffer premature degradation. The quantitative wear and fatigue prediction methodology can be used to develop a sound preventive maintenance program. The results of the research also show the improvements in check valve performance/reliability that can be achieved by certain modifications in the valve design

Status of degraded core issues. Synthesis paper prepared by G. Bandini in collaboration with the NEA task group on degraded core cooling

International Nuclear Information System (INIS)

2001-02-01

The in-vessel evolution of a severe accident in a nuclear reactor is characterised, generally, by core uncover and heat-up, core material oxidation and melting, molten material relocation and debris behaviour in the lower plenum up to vessel failure. The in-vessel core melt progression involves a large number of physical and chemical phenomena that may depend on the severe accident sequence and the reactor type under consideration. Core melt progression has been studied in the last twenty years through many experimental works. Since then, computer codes are being developed and validated to analyse different reactor accident sequences. The experience gained from the TMI-2 accident also constitutes an important source of data. The understanding of core degradation process is necessary to evaluate initial conditions for subsequent phases of the accident (ex-vessel and within the containment), and define accident management strategies and mitigative actions for operating and advanced reactors. This synthesis paper, prepared within the Task Group on Degraded Core Cooling (TG-DCC) of PWG2, contains a brief summary of current views on the status of degraded core issues regarding light water reactors. The in-vessel fission product release and transport issue is not addressed in this paper. The areas with remaining uncertainties and the needs for further experimental investigation and model development have been identified. The early phase of core melt progression is reasonably well understood. Remaining uncertainties may be addressed on the basis of ongoing experimental activities, e.g. on core quenching, and research programs foreseen in the near future. The late phase of core melt progression is less understood. Ongoing research programs are providing additional valuable information on corium molten pool behaviour. Confirmatory research is still required. The pool crust behaviour and material relocation into the lower plenum are the areas where additional research should

Marine sponge skeleton photosensitized by copper phthalocyanine: A catalyst for Rhodamine B degradation

Directory of Open Access Journals (Sweden)

Norman Małgorzata

2016-01-01

Full Text Available We present a combined approach to photo-assisted degradation processes, in which a catalyst, H2O2 and UV irradiation are used together to enhance the oxidation of Rhodamine B (RB. The heterogeneous photocatalyst was made by the process of adsorption of copper phthalocyanine tetrasulfonic acid (CuPC onto purified spongin-based Hippospongia communis marine sponge skeleton (HcS. The product obtained, CuPC-HcS, was investigated by a variety of spectroscopic (carbon-13 nuclear magnetic resonance 13C NMR, Fourier transform infrared spectroscopy FTIR, energy-dispersive X-ray spectroscopy EDS and microscopic techniques (scanning electron microscopy SEM, fluorescent and optical microscopy, as well as thermal analysis. The study confirms the stable combination of the adsorbent and adsorbate. For a 10 mg/L RB solution, the percentage degradation reached 95% using CuPC-HcS as a heterocatalyst. The mechanism of RB removal involves adsorption and photodegradation simultaneously.

Nuclear techniques in food production

International Nuclear Information System (INIS)

Merlin, J.P.C.

1975-01-01

This study is divided into three parts. The first, devoted to the use of radiations in food production, deals especially with artificial mutagenesis, selectors taking advantage of altered hereditary features in plants from irradiated seed; sterilization of animals to eliminate harmful insects (male sterilization technique); the lethal power of radiations used for the production of animal vaccins, attenuated by irradiation, against organisms which infest or degrade food products. Part two shows that radioactive atoms used as tracers to reveal migrations and chemical transformations of products such as fertilizers and pesticides can speed up all kinds of agronomical research. Their possibilities in research on animal feeding and to detect poisonous substances in foodstuffs are also mentioned. The last part is devoted to the use of nuclear techniques in irrigation and more precisely in the study of underground water flows soil moisture and lastly the future of nuclear desalination [fr

How do polymers degrade?

Science.gov (United States)

Lyu, Suping

2011-03-01

Materials derived from agricultural products such as cellulose, starch, polylactide, etc. are more sustainable and environmentally benign than those derived from petroleum. However, applications of these polymers are limited by their processing properties, chemical and thermal stabilities. For example, polyethylene terephthalate fabrics last for many years under normal use conditions, but polylactide fabrics cannot due to chemical degradation. There are two primary mechanisms through which these polymers degrade: via hydrolysis and via oxidation. Both of these two mechanisms are related to combined factors such as monomer chemistry, chain configuration, chain mobility, crystallinity, and permeation to water and oxygen, and product geometry. In this talk, we will discuss how these materials degrade and how the degradation depends on these factors under application conditions. Both experimental studies and mathematical modeling will be presented.