WorldWideScience

Sample records for accident consequences pwr

  1. Degraded core accidents for the Sizewell PWR A sensitivity analysis of the radiological consequences

    Kelly, G N; Clarke, R H; Ferguson, L; Haywood, S M; Hemming, C R; Jones, J A

    1982-01-01

    The radiological impact of degraded core accidents postulated for the Sizewell PWR was assessed in an earlier study. In this report the sensitivity of the predicted consequences to variation in the values of a number of important parameters is investigated for one of the postulated accidental releases. The parameters subjected to sensitivity analyses are the dose-mortality relationship for bone marrow irradiation, the energy content of the release, the warning time before the release to the environment, and the dry deposition velocity for airborne material. These parameters were identified as among the more important in determining the uncertainty in the results obtained in the initial study. With a few exceptions the predicted consequences were found to be not very sensitive to the parameter values investigated, the range of variation in the consequences for the limiting values of each parameter rarely exceeded a factor of a few and in many cases was considerably less. The conclusions reached are, however, p...

  2. Degraded core accidents for the Sizewell PWR: A sensitivity analysis of the radiological consequences

    The radiological impact of degraded core accidents postulated for the Sizewell PWR was assessed in an earlier study. In this report the sensitivity of the predicted consequences to variation in the values of a number of important parameters is investigated for one of the postulated accidental releases. The parameters subjected to sensitivity analyses are the dose-mortality relationship for bone marrow irradiation, the energy content of the release, the warning time before the release to the environment, and the dry deposition velocity for airborne material. These parameters were identified as among the more important in determining the uncertainty in the results obtained in the initial study. With a few exceptions the predicted consequences were found to be not very sensitive to the parameter values investigated, the range of variation in the consequences for the limiting values of each parameter rarely exceeded a factor of a few and in many cases was considerably less. The conclusions reached are, however, particular to the releases analysed from Sizewell; for different releases from different locations the sensitivity may change significantly. In the earlier study and analysis was undertaken of the impact on the predicted consequences of potential overestimates in the release fractions of radionuclides. Since the results of that study were published some relatively minor numerical errors have been identified. While none of these affects the conclusions reached in that study the opportunity has been taken in this report to present revised values for those results known to be in error. This revised text and results are presented as an appendix to this report and they replace the corresponding material in the earlier study. (author)

  3. The radiological consequences of degraded core accidents for the Sizewell PWR The impact of adopting revised frequencies of occurrence

    Kelly, G N

    1983-01-01

    The radiological consequences of degraded core accidents postulated for the Sizewell PWR were assessed in an earlier study and the results published in NRPB-R137. Further analyses have since been made by the Central Electricity Generating Board (CEGB) of degraded core accidents which have led to a revision of their predicted frequencies of occurrence. The implications of these revised frequencies, in terms of the risk to the public from degraded core accidents, are evaluated in this report. Increases, by factors typically within the range of about 1.5 to 7, are predicted in the consequences, compared with those estimated in the earlier study. However, the predicted risk from degraded core accidents, despite these increases, remains exceedingly small.

  4. An assessment of the radiological consequences of releases to groundwater following a core-melt accident at the Sizewell PWR

    In the extremely unlikely event of a degraded core accident at the proposed Sizewell PWR it is theoretically possible for the core to melt through the containment, after which activity could enter groundwater directly or as a result of subsequent leaching of the core in the ground. The radiological consequences of such an event are analysed and compared with the analysis undertaken by the NRPB for the corresponding releases to atmosphere. It is concluded that the risks associated with the groundwater route are much less important than those associated with the atmospheric route. The much longer transport times in the ground compared with those in the atmosphere enable countermeasures to be taken, if necessary, to restrict doses to members of the public to very low levels in the first few years following the accident. The entry of long-lived radionuclides into the sea over very long timescales results in the largest contribution to population doses, but these are delivered at extremely low dose rates which would be negligible compared with background exposure. (author)

  5. PWR Core 2 Project accident analysis

    The various operations required for receipt, handling, defueling and storage of spent Shippingport PWR Core 2 fuel assemblies have been evaluated to determine the potential accidents and their consequences. These operations will introduce approximately 16,500 kilograms of depleted natural uranium (as UO2), 139 kilograms of plutonium, 2.8 megacuries of mixed fission products, and 14 kilograms of Zircaloy-4 (cladding and hardware) into the 221-T Canyon Building. Event sequences for potential accidents that were considered included (1) leaking fuel assemblies, (2) fire and explosion, (3) loss of coolant or cooling capability, (4) dropped and/or damaged fuel assemblies, and extrinsic occurrences such as loss of services, missile impact, and natural occurrences (e.g., earthquake, tornado). Accident frequencies were determined by formal analysis to be very low. Accident consequences are greatly mitigated by the safety and containment features designed into the fuel modules and shipping cask, the long cooling time since reactor discharge, and the redundant safety features designed into the facilities, equipment, and operating procedures for the PWR Core 2 Project. Possible hazards associated with the handling of these fuels have been considered and adequate safeguards and storage constraints identified. The operations of M-160 cask unloading and module storage will not involve identifiable risks as great or significantly greater than those for comparable licensed nuclear facilities, nor will hazards or risks be significantly different from comparable past 221-T Plant programs. Therefore, it is concluded that the operations required for receipt, handling, and defueling of the M-160 cask and for the storage and surveillance of the PWR Core 2 fuel assemblies at the 221-T Canyon Building can be performed without undue risk to the safety of the involved personnel, the public, the environment or the facility

  6. Analysis of reactivity accidents in PWR'S

    This note describes the French strategy which has consisted, firstly, in examining all the accidents presented in the PWR unit safety reports in order to determine for each parameter the impact on accident consequences of varying the parameter considered, secondly in analyzing the provisions taken into account to restrict variation of this parameter to within an acceptable range and thirdly, in checking that the reliability of these provisions is compatible with the potential consequences of transgression of the authorized limits. Taking into consideration violations of technical operating specifications and/or non-observance of operating procedures, equipment failures, and partial or total unavailability of safety systems, these studies have shown that fuel mechanical strength limits can be reached but that the probability of occurrence of the corresponding events places them in the residual risk field and that it must, in fact, be remembered that there is a wide margin between the design basis accidents and accidents resulting in fuel destruction. However, during the coming year, we still have to analyze scenarios dealing with cumulated events or incidents leading to a reactivity accident. This program will be mainly concerned with the impact of the cases examined relating to dilution incidents under normal operating conditions or accident operating conditions

  7. Reactor safety study. An assessment of accident risks in U. S. commercial nuclear power plants. Appendix VI. Calculation of reactor accident consequences. [PWR and BWR

    1975-10-01

    Information is presented concerning the radioactive releases from the containment following accidents; radioactive inventory of the reactor core; atmospheric dispersion; reactor sites and meteorological data; radioactive decay and deposition from plumes; finite distance of plume travel; dosimetric models; health effects; demographic data; mitigation of radiation exposure; economic model; and calculated results with consequence model.

  8. The Chernobyl accident consequences

    Five teen years later, Tchernobyl remains the symbol of the greater industrial nuclear accident. To take stock on this accident, this paper proposes a chronology of the events and presents the opinion of many international and national organizations. It provides also web sites references concerning the environmental and sanitary consequences of the Tchernobyl accident, the economic actions and propositions for the nuclear safety improvement in the East Europe. (A.L.B.)

  9. Identification and evaluation of PWR in-vessel severe accident management strategies

    This reports documents work performed the NRC/RES Accident Management Guidance Program to evaluate possible strategies for mitigating the consequences of PWR severe accidents. The selection and evaluation of strategies was limited to the in-vessel phase of the severe accident, i.e., after the initiation of core degradation and prior to RPV failure. A parallel project at BNL has been considering strategies applicable to the ex-vessel phase of PWR severe accidents

  10. Accidents, risks and consequences

    Although the accident at Chernobyl can be considered as the worst accident in the world, it could have been worse. Other far worse situations are considered, such as a nuclear weapon hitting a nuclear reactor. Indeed the accident at Chernobyl is compared to a nuclear weapon. The consequences of Chernobyl in terms of radiation levels are discussed. Although it is believed that a similar accident could not occur in the United Kingdom, that possibility is considered. It is suggested that emergency plans should be made for just such an eventuality. Even if Chernobyl could not happen in the UK, the effects of accidents are international. The way in which nuclear reactor accidents happen is explored, taking the 1957 Windscale fire, Three Mile Island and Chernobyl as examples. Reactor designs and accident scenarios are considered. The different reactor designs are listed. As well as the Chernobyl RBMK design it is suggested that the light water reactors also have undesirable features from the point of view of safety. (U.K.)

  11. REWET, PWR LOCA accident experiments

    1 - Description of test facility: The REWET-II facility was designed for the investigation of the reflooding phase of a LOCA. The main design principle is the accurate simulation of the rod bundle geometry and the primary system elevations. This is necessary in order to have the correct flow channels and hydrostatic pressures for the reflooding process. The reactor vessel is simulated by a stainless steel U-tube construction consisting of downcomer, lower plenum, core and upper plenum. The primary loops contain a pipe simulating the broken loop and a connection line between the upper plenum and the downcomer simulating five intact loops. The containment is simulated by a pressure vessel (not in scale). Steam generators and primary pumps are simulated with flow resistances. The ECC-water can be injected to the downcomer and/or to the upper plenum by a pump or from an accumulator. All the elevation in the reactor vessel simulator are scaled to 1:1 (except the reactor upper head). The scale of the volumes and flow areas is 1:2333 referring to the number of the fuel rod simulators in the facility and the fuel rods in the reference reactor. The rod bundle is either in a hexagonal shroud, the inside distance of the opposite walls is 54.3 mm and the wall thickness 2 mm, or in a round shroud, the inner diameter is 66.0 mm and the wall thickness 2 mm. The simulation of the fuel-rod bundle consists of 19 indirectly electrically heated simulator rods. The heating coils are inside stainless steel claddings in magnesium oxide insulation. The heated length, the outer diameter and the lattice pitch of the fuel-rod simulators as well as the number (= 10) and construction of the rod bundle spacers are the same as in the reference reactor. The upper ends of the rods are attached to the upper tie plate. 2 - Description of test: Pressurized water reactors in use in Finland reactors have certain unique features which make them different from most other PWR designs. The 6 horizontal

  12. Accidents, probabilities and consequences

    Following brief discussion of the safety of wind-driven power plants and solar power plants, some aspects of the safety of fast breeder and thermonuclear power plants are presented. It is pointed out that no safety evaluation of breeders comparable to the Rasmussen investigation has been carried out and that discussion of the safety aspects of thermonuclear power is only just begun. Finally, as an illustration of the varying interpretations of risk and safety analyses, four examples are given of predicted probabilities and consequences in Copenhagen of the maximum credible accident at the Barsebaeck plant, under the most unfavourable meterological conditions. These are made by the Environment Commission, Risoe Research Establishment, REO (a pro-nuclear group) and OOA (an anti-nuclear group), and vary by a factor of over 1000. (JIW)

  13. Study on severe accident mitigation measures for the development of PWR SAMG

    2006-01-01

    In the development of the Severe Accident Management Guidelines (SAMG), it is very important to choose the main severe accident sequences and verify their mitigation measures. In this article, Loss-of-Coolant Accident (LOCA), Steam Generator Tube Rupture (SGTR), Station Blackout (SBO), and Anticipated Transients without Scram (ATWS) in PWR with 300 MWe are selected as the main severe accident sequences. The core damage progressions induced by the above-mentioned sequences are analyzed using SCDAP/RELAP5. To arrest the core damage progression and mitigate the consequences of severe accidents, the measures for the severe accident management (SAM) such as feed and bleed, and depressurizations are verified using the calculation. The results suggest that implementing feed and bleed and depressurization could be an effective way to arrest the severe accident sequences in PWR.

  14. Accident consequence assessment code development

    This paper describes the new computer code system, OSCAAR developed for off-site consequence assessment of a potential nuclear accident. OSCAAR consists of several modules which have modeling capabilities in atmospheric transport, foodchain transport, dosimetry, emergency response and radiological health effects. The major modules of the consequence assessment code are described, highlighting the validation and verification of the models. (author)

  15. Consequences of the Chernobyl accident

    The techniques currently used in off-site consequence modelling are applied to the Chernobyl accident. Firstly, the time dependent spread of radioactive material across the European continent is considered, followed by a preliminary assessment of the dosimetric impact (in terms of collective and mean individual doses) on the various countries of Eastern and Western Europe. The consequences of the accident in the USSR are also discussed. Finally, the likely implications of the Chernobyl event on research in the field of environmental consequence assessment are outlined. (author)

  16. Long-Term Station Blackout Accident Analyses of a PWR with RELAP5/MOD3.3

    Andrej Prošek; Leon Cizelj

    2013-01-01

    Stress tests performed in Europe after accident at Fukushima Daiichi also required evaluation of the consequences of loss of safety functions due to station blackout (SBO). Long-term SBO in a pressurized water reactor (PWR) leads to severe accident sequences, assuming that existing plant means (systems, equipment, and procedures) are used for accident mitigation. Therefore the main objective was to study the accident management strategies for SBO scenarios (with different reactor coolant pump...

  17. Scoping Study Investigating PWR Instrumentation during a Severe Accident Scenario

    The accidents at the Three Mile Island Unit 2 (TMI-2) and Fukushima Daiichi Units 1, 2, and 3 nuclear power plants demonstrate the critical importance of accurate, relevant, and timely information on the status of reactor systems during a severe accident. These events also highlight the critical importance of understanding and focusing on the key elements of system status information in an environment where operators may be overwhelmed with superfluous and sometimes conflicting data. While progress in these areas has been made since TMI-2, the events at Fukushima suggests that there may still be a potential need to ensure that critical plant information is available to plant operators. Recognizing the significant technical and economic challenges associated with plant modifications, it is important to focus on instrumentation that can address these information critical needs. As part of a program initiated by the Department of Energy, Office of Nuclear Energy (DOE-NE), a scoping effort was initiated to assess critical information needs identified for severe accident management and mitigation in commercial Light Water Reactors (LWRs), to quantify the environment instruments monitoring this data would have to survive, and to identify gaps where predicted environments exceed instrumentation qualification envelop (QE) limits. Results from the Pressurized Water Reactor (PWR) scoping evaluations are documented in this report. The PWR evaluations were limited in this scoping evaluation to quantifying the environmental conditions for an unmitigated Short-Term Station BlackOut (STSBO) sequence in one unit at the Surry nuclear power station. Results were obtained using the MELCOR models developed for the US Nuclear Regulatory Commission (NRC)-sponsored State of the Art Consequence Assessment (SOARCA) program project. Results from this scoping evaluation indicate that some instrumentation identified to provide critical information would be exposed to conditions that

  18. Scoping Study Investigating PWR Instrumentation during a Severe Accident Scenario

    Rempe, J. L. [Rempe and Associates, LLC, Idaho Falls, ID (United States); Knudson, D. L. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lutz, R. J. [Lutz Nuclear Safety Consultant, LLC, Asheville, NC (United States)

    2015-09-01

    The accidents at the Three Mile Island Unit 2 (TMI-2) and Fukushima Daiichi Units 1, 2, and 3 nuclear power plants demonstrate the critical importance of accurate, relevant, and timely information on the status of reactor systems during a severe accident. These events also highlight the critical importance of understanding and focusing on the key elements of system status information in an environment where operators may be overwhelmed with superfluous and sometimes conflicting data. While progress in these areas has been made since TMI-2, the events at Fukushima suggests that there may still be a potential need to ensure that critical plant information is available to plant operators. Recognizing the significant technical and economic challenges associated with plant modifications, it is important to focus on instrumentation that can address these information critical needs. As part of a program initiated by the Department of Energy, Office of Nuclear Energy (DOE-NE), a scoping effort was initiated to assess critical information needs identified for severe accident management and mitigation in commercial Light Water Reactors (LWRs), to quantify the environment instruments monitoring this data would have to survive, and to identify gaps where predicted environments exceed instrumentation qualification envelop (QE) limits. Results from the Pressurized Water Reactor (PWR) scoping evaluations are documented in this report. The PWR evaluations were limited in this scoping evaluation to quantifying the environmental conditions for an unmitigated Short-Term Station BlackOut (STSBO) sequence in one unit at the Surry nuclear power station. Results were obtained using the MELCOR models developed for the US Nuclear Regulatory Commission (NRC)-sponsored State of the Art Consequence Assessment (SOARCA) program project. Results from this scoping evaluation indicate that some instrumentation identified to provide critical information would be exposed to conditions that

  19. Preliminary safety analysis of the PWR with accident-tolerant fuels during severe accident conditions

    Highlights: • Analysis of severe accident scenarios for a PWR fueled with ATF system is performed. • A large-break LOCA without ECCS is analyzed for the PWR fueled with ATF system. • Extended SBO cases are discussed for the PWR fueled with ATF system. • The accident-tolerance of ATF system for application in PWR is illustrated. - Abstract: Experience gained in decades of nuclear safety research and previous nuclear accidents direct to the investigation of passive safety system design and accident-tolerant fuel (ATF) system which is now becoming a hot research point in the nuclear energy field. The ATF system is aimed at upgrading safety characteristics of the nuclear fuel and cladding in a reactor core where active cooling has been lost, and is preferable or comparable to the current UO2–Zr system when the reactor is in normal operation. By virtue of advanced materials with improved properties, the ATF system will obviously slow down the progression of accidents, allowing wider margin of time for the mitigation measures to work. Specifically, the simulation and analysis of a large break loss of coolant accident (LBLOCA) without ECCS and extended station blackout (SBO) severe accident are performed for a pressurized water reactor (PWR) loaded with ATF candidates, to reflect the accident-tolerance of ATF

  20. PWR auxiliary systems, safety and emergency systems, accident analysis, operation

    The author presents a description of PWR auxiliary systems like volume control, boric acid control, coolant purification, -degassing, -storage and -treatment system and waste processing systems. Residual heat removal systems, emergency systems and containment designs are discussed. As an accident analysis the author gives a survey over malfunctions and disturbances in the field of reactor operations. (TK)

  1. Serious accidents of PWR type reactors for power generation

    This document presents the great lines of current knowledge on serious accidents relative to PWR type reactors. First, is exposed the physics of PWR type reactor core meltdown and the possible failure modes of the containment building in such a case. Then, are presented the dispositions implemented with regards to such accidents in France, particularly the pragmatic approach that prevails for the already built reactors. Then, the document tackles the case of the European pressurized reactor (E.P.R.), for which the dimensioning takes into account explicitly serious accidents: it is a question of objectives conception and their respect must be the object of a strict demonstration, by taking into account uncertainties. (N.C.)

  2. Characteristics of the aerosols released to the environment after a severe PWR accident

    In the event of a postulated severe accident on a pressurized water reactor (PWR) involving fuel degradation, gases and aerosols containing radioactive products could be released, with short, medium and long term consequences for the population and the environment. Under such accident conditions, the ESCADRE code system, developed at IPSN (Institute for Nuclear Safety and Protection) can be used to calculate the properties of the substances released and, especially with the AEROSOLS/B2 code, the main characteristics of the aerosols (concentration, size distribution, composition). For conditions representative of severe PWR accidents, by varying different main parameters (structural material aerosols, steam condensation in the containment, etc...), indications are given on the range of characteristics of the aerosols (containing notably Cs, Te, Sr, Ru, etc...) released to the atmosphere. Information is also given on how more accurate data (especially on the chemical forms) will be obtainable in the framework of current or planned experimental programs (HEVA, PITEAS, PHEBUS PF, etc...)

  3. PWR pressure vessel integrity during overcooling accidents

    Pressurized water reactors are susceptible to certain types of hypothetical accidents that under some circumstances, including operation of the reactor beyond a critical time in its life, could result in failure of the pressure vessel as a result of propagation of crack-like defects in the vessel wall. The accidents of concern are those that result in thermal shock to the vessel while the vessel is subjected to internal pressure. Such accidents, referred to as pressurized thermal shock or overcooling accidents (OCA), include a steamline break, small-break LOCA, turbine trip followed by stuck-open bypass valves, the 1978 Rancho Seco and the TMI accidents and many other postulated and actual accidents. The source of cold water for the thermal shock is either emergency core coolant or the normal primary-system coolant. ORNL performed fracture-mechanics calculations for a steamline break in 1978 and for a turbine-trip case in 1980 and concluded on the basis of the results that many more such calculations would be required. To meet the expected demand in a realistic way a computer code, OCA-I, was developed that accepts primary-system temperature and pressure transients as input and then performs one-dimensional thermal and stress analyses for the wall and a corresponding fracture-mechanics analysis for a long axial flaw. The code is briefly described, and its use in both generic and specific plant analyses is discussed

  4. PWR accident management realated tests: some Bethsy results

    The BETHSY integral test facility which is a scaled down model of a 3 loop FRAMATOME PWR and is currently operated at the Nuclear Center of Grenoble, forms an important part of the French strategy for PWR Accident Management. In this paper the features of both the facility and the experimental program are presented. Two accident transients: a total loss of feedwater and a 2'' cold leg break in case of High Pressure Safety Injection System failure, involving either Event Oriented - or State Oriented-Emergency Operating Procedures (EO-EOP or SO-EOP) are described and the system response analyzed. CATHARE calculation results are also presented which illustrate the ability of this code to adequately predict the key phenomena of these transients. (authors). 13 figs., 11 refs., 2 tabs

  5. Medical consequences of radiation accidents

    Since 1945, more than 1.8 x 1021 Bq of artificial radionuclides have been released into the atmosphere. Approximately 2.04 x 1018B, i.e. approx. 0.11%, are the result of accidents at nuclear industrial facilities. This percentage is causing increased interest among researchers. This is due to the fact that in the wake of accidental release radionuclides become distributed unevenly across the Earth's surface, and the associated exposures, fluctuating from background level to several grays, an induce both stochastic and deterministic effects in the irradiated population. A comparative analysis of the medical consequences of the twentieth century's most serious nuclear events, namely the authorized dumping of high level radioactive waste into the river Techa in 1950, the explosion of a storage tank containing long lived radioactive waste in the Southern Urals in 1957, the fire at Sellafield in 1957 and the accident at the Chernobyl nuclear power plant in 1986, has shown that when timely countermeasures are taken, the worst immediate and delayed medical consequences of an accident can be avoided. The consequences that have since been ascertained are a brief rise in the mortality rate during the first five years, with a dose in excess of 500 mSv; an increase in the incidence of leukaemia, with an absolute risk of up to 1.1. x 10-4 man·years/Gy; and increased mortality among children with external radiation doses of up to 1000 mSv, and internal doses of 99-190 mSv on the bone surfaces of neonates or 170-600 mSv on the bone surfaces of the mother. There is reliable evidence that, with external gamma radiation doses in excess of 520 mSv, the mortality rate for all malignant tumorous increases by 45-58% compared with the control level. There is also a significant increase in thyroid cancer frequency four to ten years after the incorporation of iodine isotopes by children aged up to 7 years, including an accumulation period in the womb. (author). 12 refs, 7 tabs

  6. Application of PCTRAN-3/U to studying accident management during PWR severe accident

    In order to improve the safety of nuclear power plant, operator action should be taken into account during a severe accident. While it takes a long time to simulate the plant transient behavior under a severe accident in comparison with the design based accident, a transient simulator should have both high speed calculation capability and interactive functions to model the operating procedures. PCTRAN has been developing to be a simple simulator by using a personal computer to simulate plant behavior under an accident condition. While currently available means usually take relatively long time to simulate plant behavior, using a current high-powered personal computer (PC), PCTRAN-3/U code is designed to operate at a speed significantly faster than real-time. The author describes some results of PCTRAN application in studying the efficiency of accident management for a pressurized water reactor (PWR) during an severe accident

  7. Analysis of reactivity insertion accidents in PWR reactors

    A calculation model to analyze reactivity insertion accidents in a PWR reactor was developed. To analyze the nuclear power transient, the AIREK-III code was used, which simulates the conventional point-kinetic equations with six groups of delayed neutron precursors. Some modifications were made to generalize and to adapt the program to solve the proposed problems. A transient thermal analysis model was developed which simulates the heat transfer process in a cross section of a UO2 fuel rod with Zircalloy clad, a gap fullfilled with Helium gas and the correspondent coolant channel, using as input the nulcear power transient calculated by AIREK-III. The behavior of ANGRA-i reactor was analized during two types of accidents: - uncontrolled rod withdrawal from subcritical condition; - uncontrolled rod withdrawal at power. The results and conclusions obtained will be used in the license process of the Unit 1 of the Central Nuclear Almirante Alvaro Alberto. (Author)

  8. Level 3 PSA and it's implementation for PWR accident

    Reactor safety assessment of nuclear power plants using probabilistic assessment methodology is most important in addition to the deterministic assessment. The methodology of Level 3 Probabilistic Safety Assessment (PSA) is especially required to estimate severe accident or beyond design basis accidents of nuclear power plants. This method is carried out after the Fukushima accident. In this research, the postulations beyond design basis accidents of PWR AP - 1000 would be taken, and simulated at West Bangka sample site. The series of calculations performed are: calculate the source terms of the core damaged, modeling of meteorological conditions and environmental site, exposure pathway modeling, analysis of radionuclide dispersion and transport phenomena in the environment, radionuclide deposition analysis, analysis of radiation dose, protection & mitigation analysis, and risk analysis. The assessment uses a series of subsystems on PC Cosyma software. The results prove that the safety assessment using Level 3 PSA methodology is very effective and comprehensive estimate the impact, consequences, risks, nuclear emergency preparedness, and the reactor accident management especially for severe accidents or beyond design basis accidents of nuclear power plants. The results of the assessment can be used as a feedback to safety assessment of Level 1 PSA and Level 2 PSA. (author)

  9. Psychiatric consequences of road traffic accidents.

    Mayou, R; Bryant, B.; Duthie, R

    1993-01-01

    OBJECTIVE--To determine the psychiatric consequences of being a road traffic accident victim. DESIGN--Follow up study of road accident victims for up to one year. SETTING--Emergency department of the John Radcliffe Hospital, Oxford. SUBJECTS--188 consecutive road accident victims aged 18-70 with multiple injuries (motorcycle or car) or whiplash neck injury, who had not been unconscious for more than 15 minutes, and who lived in the catchment area. MAIN OUTCOME MEASURES--Present state examinat...

  10. Consequences of the Chernobyl accident

    A collection of three papers about the fallout in Austria from the 1986 Chernobyl reactor accident is given: 1. An overview of the research projects in Austria; 2. On the transfer into and uptake by crops and animal fodder; 3. On the reduction of cesium concentration in food. 18 tabs., 21 figs., 69 refs

  11. Assessing economic consequences of radiation accidents

    This project reviewed the literature on the economic consequences of accidents to determine the availability of assessment methods and data and their applicability to the high-level radioactive waste (HLW) disposal system before closure; determined needs for expansion, revision, or adaptation of methods and data for modeling economic consequences of accidents of the scale projected for the disposal system; and gathered data that might be useful for the needed revisions. 8 refs., 1 tab

  12. Chernobylsk accident (Causes and Consequences)- Part 2

    The causes and consequences of the nuclear accident at Chernobylsk-4 reactor are shortly described. The informations were provided by Russian during the specialist meeting, carried out at seat of IAEA. The Russian nuclear panorama; the site, nuclear power plant characteristics and sequence of events; the immediate measurements after accident; monitoring/radioactive releases; environmental contamination and ecological consequences; measurements of emergency; recommendations to increase the nuclear safety; and recommendations of work groups, are presented. (M.C.K.)

  13. Applications of probabilistic accident consequence evaluation in Cuba

    Are presented the approaches and results of the application of Accident Consequence Evaluation methodologies in on emergency in the Juragua Nuclear Power Plant site and a population evaluation of a planned NPP site in the east of the country Findings on population sector weighing and assessment of effectiveness of primary countermeasures in the event of sever accidents (SST1 and PWR4 source terms) in Juragua NPP site are discussed Results on comparative risk-based evaluation of the population predicted evolution (in 3 temporal horizons: base year, 2005 year and 2050 year) for the planned site are described. Evaluation also included sector risk weighing, risk importance of small towns in the nearby of the effects on risk of population freezing and relocation of these villages

  14. Aerosols behavior inside a PWR during an accident

    During very hypothetical accidents occurring in a pressurized water ractor, radioactive aerosols can be released, during core-melt, inside the reactor containment building. A good knowledge of their behavior in the humid containment atmosphere (mass concentration and size distribution) is essential in order to evaluate their harmfulness in case of environment contamination and to design possible filtration devices. Accordingly the Safety Analysis Department of the Atomic Energy Commission uses several computer models, describing the particle formation (BOIL/MARCH), then behavior in the primary circuits (TRAP-MELT), and in the reactor containment building (AEROSOLS-PARFDISEKO-III B). On the one hand, these models have been improved, in particular the one related to the aerosol formation (nature and mass of released particles) using recent experimental results. On the other hand, sensitivity analyses have been performed with the AEROSOLS code which emphasize the particle coagulation parameters: agglomerate shape factors and collision efficiency. Finally, the different computer models have been applied to the study of aerosol behavior during a 900 MWe PWR accident: loss-of-coolant-accident (small break with failure of all safety systems)

  15. Integral Test Facility PKL: Experimental PWR Accident Investigation

    Klaus Umminger

    2012-01-01

    Full Text Available Investigations of the thermal-hydraulic behavior of pressurized water reactors under accident conditions have been carried out in the PKL test facility at AREVA NP in Erlangen, Germany for many years. The PKL facility models the entire primary side and significant parts of the secondary side of a pressurized water reactor (PWR at a height scale of 1 : 1. Volumes, power ratings and mass flows are scaled with a ratio of 1 : 145. The experimental facility consists of 4 primary loops with circulation pumps and steam generators (SGs arranged symmetrically around the reactor pressure vessel (RPV. The investigations carried out encompass a very broad spectrum from accident scenario simulations with large, medium, and small breaks, over the investigation of shutdown procedures after a wide variety of accidents, to the systematic investigation of complex thermal-hydraulic phenomena. This paper presents a survey of test objectives and programs carried out to date. It also describes the test facility in its present state. Some important results obtained over the years with focus on investigations carried out since the beginning of the international cooperation are exemplarily discussed.

  16. Medical consequences of Chernobyl accident

    Galstyan I.A.

    2015-12-01

    Full Text Available Aim: to study the long-term effects of acute radiation syndrome (ARS, developed at the victims of the Chernobyl accident. Material and Methods. 237 people were exposed during the accident, 134 of them were diagnosed with ARS. Dynamic observation implies a thorough annual examination in a hospital. Results. In the first 1.5-2 years after the ARS mean group indices of peripheral blood have returned to normal. However, many patients had transient expressed moderate cytopenias. Granulocytopenia, thrombocytopenia, lymphopenia and erythropenia were the most frequently observed things during the first 5 years after the accident. After 5 years their occurences lowered. In 11 patients the radiation cataract was detected. A threshold dose for its development is a dose of 3.2 Gy Long-term effects of local radiation lesions (LRL range from mild skin figure smoothing to a distinct fibrous scarring, contractures, persistently recurrent late radiation ulcers. During all years of observation we found 8 solid tumors, including 2 thyroid cancers. 5 hematologic diseases were found. During 29 years 26 ARS survivors died of various causes. Conclusion. The health of ones with long-term ARS effects is determined by the evolution of the LRL effects on skin, radiation cataracts, hema-tological diseases and the accession of of various somatic diseases, not caused by radiation.

  17. Behaviour of organic iodides under pwr accident conditions

    Laboratory experiments were performed to study the behaviour of radioactive methyl iodide under PWR loss-of-coolant conditions. The pressure relief equipment consisted of an autoclave for simulating the primary circuit and of an expansion vessel for simulating the conditions after a rupture in the reactor coolant system. After pressure relief, the composition of the CH3sup(127/131)I-containing steam-air mixture within the expansion vessel was analysed at 80 0C over a period of 42 days. On the basis of the values measured and of data taken from the literature, both qualitative and quantitative assessments have been made as to the behaviour of radioactive methyl iodide in the event of loss-of-coolant accidents. (author)

  18. Simulation of small break loss of coolant accident in pressurized water reactor (PWR)

    A major safety concern in pressurized-water-reactor (PWR) design is the loss-of-coolant accident (LOCA),in which a break in the primary coolant circuit leads to depressurization, boiling of the coolant, consequent reduced cooling of the reactor core, and , unless remedial measures are taken, overheating of the fuel rods. This concern has led to the development of several simulators for safety analysis. This study demonstrates how the passive and active safety systems in conventional and advanced PWR behave during the small break loss of Coolant Accident (SBLOCA). The consequences of SBOLOCA have been simulated using IAEA Generic pressurized Water Reactor Simulator (GPWRS) and personal Computer Transient analyzer (PCTRAN) . The results were presented and discussed. The study has confirmed the major safety advantage of passive plants versus conventional PWRs is that the passive safety systems provide long-term core cooling and decay heat removal without the need for operator actions and without reliance on active safety-related system. (Author)

  19. Examination of offsite radiological emergency measures for nuclear reactor accidents involving core melt. [PWR

    Aldrich, D.C.; McGrath, P.E.; Rasmussen, N.C.

    1978-06-01

    Evacuation, sheltering followed by population relocation, and iodine prophylaxis are evaluated as offsite public protective measures in response to nuclear reactor accidents involving core-melt. Evaluations were conducted using a modified version of the Reactor Safety Study consequence model. Models representing each measure were developed and are discussed. Potential PWR core-melt radioactive material releases are separated into two categories, ''Melt-through'' and ''Atmospheric,'' based upon the mode of containment failure. Protective measures are examined and compared for each category in terms of projected doses to the whole body and thyroid. Measures for ''Atmospheric'' accidents are also examined in terms of their influence on the occurrence of public health effects.

  20. The Chernobyl nuclear accident and its consequences

    An AAEC Task Group was set up shortly after the accident at the Chernobyl Nuclear Power Plant to monitor and evaluate initial reports and to assess the implications for Australia. The Task Group issued a preliminary report on 9 May 1986. On 25-29 August 1986, the USSR released details of the accident and its consequences and further information has become available from the Nuclear Energy Agency of OECD and the World Health Organisation. The Task Group now presents a revised report summarising this information and commenting on the consequences from the Australian viewpoint

  1. Health consequences of nuclear accidents

    The author first outlines that no exposure of mankind to environmental risks has been as exhaustively and continuously studied as that resulting from ionizing radiations. Apart from lethal effects, he describes non lethal cell lesions which are induced in tissues: mutations and modifications of gene expressions, either directly under the effect of radiation, or by water hydrolysis, or indirectly through a biochemical response to these initial events. Then, the author evokes the controversy about Chernobyl: according to scientists, there is no relationship between the health degradation (human morbidity and mortality) and fallouts whereas activist groups state that there is. The author then evokes that the WHO and the IAEA were accused to lie about the issue of victims and health consequences. He outlines that UNSCEAR reports are a reference for radio-biologists, and that the 2011 report confirmed the conclusions of the 2006 report. He comments some published data, notably those on the acute irradiation syndrome (ARS), on carcinogenic effects (essentially thyroid cancers for children, as there is no clear nor admitted relationship for other forms of cancer), on other pathologies. Finally, the author briefly discusses the issue of crisis management, the information about Fukushima, and the issue of Chernobyl fallouts in France

  2. Biological and medical consequences of nuclear accidents

    The study of the medical and biological consequences of the nuclear accidents is a vast program. The Chernobyl accident has caused some thirty deceases: Some of them were rapid and the others occurred after a certain time. The particularity of these deaths was that the irradiation has been associated to burns and traumatisms. The lesson learnt from the Chernobyl accident is to treat the burn and the traumatism before treating the irradiation. Contrary to what the research workers believe, the first wave of deaths has passed between 15 and 35 days and it has not been followed by any others. But the therapeutic lesson drawn from the accident confirm the research workers results; for example: the radioactive doses band that determines where the therapy could be efficacious or not. the medical cares dispensed to the irradiated people in the hospital of Moscow has confirmed that the biochemical equilibrium of proteinic elements of blood has to be maintained, and the transfusion of the purified elements are very important to restore a patient to health, and the sterilization of the medium (room, food, bedding,etc...) of the patient is indispensable. Therefore, it is necessary to establish an international cooperation for providing enough sterilized rooms and specialists in the irradiation treatment. The genetic consequences and cancers from the Chernobyl accident have been discussed. It is impossible to detect these consequences because of their negligible percentages. (author)

  3. Numerical simulation of radioisotope's dependency on containment performance for large dry PWR containment under severe accidents

    Highlights: • Calculation and comparison of activity of BURN-UP code with ORIGEN2 code. • Development of SASTC computer code. • Radioisotopes dependency on containment ESFs. • Mitigation in atmospheric release with ESFs operation. • Variation in radioisotopes source term with spray flow and pH value. -- Abstract: During the core melt accidents large amount of fission products can be released into the containment building. These fission products escape into the environment to contribute in accident source term. The mitigation in environmental release is demanded for such radiological consequences. Thus, countermeasures to source term, mitigations of release of radioactivity have been studied for 1000 MWe PWR reactor. The procedure of study is divided into five steps: (1) calculation and verification of core inventory, evaluated by BURN-UP code, (2) containment modeling based on radioactivity removal factors, (3) selection of potential accidents initiates the severe accident, (4) calculation of release of radioactivity, (5) study the dependency of release of radioactivity on containment engineering safety features (ESFs) inducing mitigation. Loss of coolant accident (LOCA), small break LOCA and flow blockage accidents (FBA) are selected as initiating accidents. The mitigation effect of ESFs on source term has been studied against ESFs performance. Parametric study of release of radioactivity has been carried out by modeling and simulating the containment parameters in MATLAB, which takes BURN-UP outcomes as input along with the probabilistic data. The dependency of iodine and aerosol source term on boric and caustic acid spray has been determined. The variation in source term mitigation with the variation of containment spray flow rate and pH values have been studied. The variation in containment retention factor (CRF) has also been studied with the ESF performance. A rapid decrease in source term is observed with the increase in pH value

  4. Radiological consequences of the Chernobyl reactor accident

    The reactor accident at unit 4 of the Chernobyl nuclear power plant in Ukraine has deeply affected the living conditions of millions of people. Especially the health consequences have been of public concern up to the present and also been the subject of sometimes absurd claims. The current knowledge on the radiological consequences of the accident is reviewed. Though an increased hazard for some risk groups with high radiation exposure, e.g., liquidators, still cannot be totally excluded for the future, the majority of the population shows no statistically significant indication of radiation-induced illnesses. The contribution of the Research Center Juelich to the assessment of the post-accidental situation and psychological relief of the population is reported. The population groups still requiring special attention include, in particular, children growing up in highly contaminated regions and the liquidators of the years 1986 and 1987 deployed immediately after the accident. (author)

  5. Consequences in Sweden of the Chernobyl accident

    It summarizes the consequences in Sweden of the Chernobyl accident, describes the emergency response, the basis for decisions and countermeasures, the measurement strategies, the activity levels and doses and countermeasures and action levels used. Past and remaining problems are discussed and the major investigations and improvements are given. (author)

  6. Consequences in Guatemala of the Chernobyl accident

    Because of the long distance between Guatemala and Chernobyl, the country did not undergo direct consequences of radioactive contamination in the short term. However, the accident repercussions were evident in the medium and long-term, mainly in two sectors, the economic-political and the environmental sectors

  7. Assessment of the efficiency of short term countermeasures following a severe accident on a PWR

    In case of a severe nuclear accident at a PWR plant, countermeasures will be initiated in the short term by authorities to reduce the consequences of the atmospheric radioactive releases on the neighbouring population. Various factors influence the level of protection afforded by countermeasures. For instance, a too late intervention would lead to a Jack of efficiency in terms of dose reduction if the actual evolution of the accident is not considered. Thus, implementation of countermeasures should be optimized. In general, the projected doses (those without countermeasure) are compared with those expected when a particular countermeasure or strategy is implemented. In this paper, an in-depth analysis associates the kinetics of the release with the corresponding evolution of the dosimetric efficiency of countermeasures. This is done at different times in the short term of the accident and for various distances from the plant. Results are presented for different strategies initiated at various times. This work gives useful information for the early management of a major nuclear accident. (authors)

  8. Assessment of severe accident prevention and mitigation features: PWR, large dry containment design

    Plant features and operator actions which have been found to be important in either preventing or mitigating severe accidents in PWRs with large dry containments have been identified. These features and actions were developed from insights derived from reviews of risk assessments performed specifically for the Zion plant and from assessments of other relevant studies. Accident sequences that dominate the core-damage frequency and those accident sequences that are of potentially high consequence were identified. Vulnerabilities of the large dry containment to severe accident containment loads were also identified. In addition, those features of a PWR with a large dry containment, which are important for preventing core damage and are available for mitigating fission-product release to the environment were identified. The report is issued to provide focus to the analyst examining an individual plant. The report calls attention to plant features and operator actions and provides a list of deterministic tributes for assessing those features and actions found to be helpful in reducing the overall risk for Zion and other PWRs with large dry containments. Thus, the guidance is offered as a resource in examining the subject plant to determine if the same, or similar, plant features and operator actions will be of value in reducing overall plant risk. This report is intended to serve solely as guidance

  9. Real and mythical consequences of Chernobyl accident

    This presentation describes the public Unacceptance of Nuclear Power as a consequence of Chernobyl Accident, an accident which was a severest event in the history of the nuclear industry. It was a shock for everybody, who has been involved in nuclear power programs. But nobody could expect that it was also the end romantic page in the nuclear story. The scale of the detriment was a great, and it could be compared with other big technological man-made catastrophes. But immediately after an accident mass media and news agencies started to transmit an information with a great exaggerations of the consequences of the event. In a report on the Seminar The lessons of the Chernobyl - 1' in 1996 examples of such incorrect information, were cited. Particularly, in the mass media it was declared that consequences of the accident could be compared with a results of the second world war, the number of victims were more than hundred thousand people, more than million of children have the serious health detriments. Such and other cases of the misconstruction have been called as myths. The real consequences of Chernobyl disaster have been summed on the International Conference 'One decade after Chernobyl' - 2, in April 1996. A very important result of the Chernobyl accident was a dissemination of stable unacceptance of the everything connected with 'the atom'. A mystic horror from invisible mortal radiation has been inspired in the masses. And from such public attitude the Nuclear Power Programs in many countries have changed dramatically. A new more pragmatic and more careful atomic era started with a slogan: 'Kernkraftwerk ? Nein, danke'. No doubt, a Chernobyl accident was a serious technical catastrophe in atomic industry. The scale of detriment is connected with a number of involved peoples, not with a number of real victims. In comparison with Bhopal case, earthquakes, crashes of the airplanes, floods, traffic accidents and other risky events of our life - the Chernobyl is

  10. Health consequences [of the Chernobyl accident

    The World Health Organisation Conference on the Health Consequences of the Chernobyl and Other Radiological Accidents, held in Geneva last November, is reported. The lack of representation from the civil nuclear industry led often to one-sided debates instigated by the anti-nuclear lobbies present. Thyroid cancer in children as a result of the Chernobyl accident received particular attention. In Belarus, 400 cases have been noted, 220 in Ukraine and 60 in the Russian Federation. All have been treated with a high degree of success. The incidence of this cancer would be expected to follow the fallout path as the main exposure route was ingestion of contaminated foods and milk products. It was noted that the only way to confirm causality was if those children born since the accident failed to show the same increased incidence. Explanations were offered for the particular susceptibility of children to thyroid cancer following exposure to radiation. Another significant cause of concern was the health consequences to clean-up workers in radiological accidents. The main factor is psychological problems from the stress of knowing that they have received high radiation doses. A dramatic increase in psychological disorders has occurred in the Ukraine over the past ten years and this is attributed to stress generated by the Chernobyl accident, compounded by the inadequacy of the public advice offered at the time and the socio-economic uncertainties accompanying the breakup of the former USSR. (UK)

  11. The Chernobyl accident consequences; Consequences de l'accident de Tchernobyl

    NONE

    2001-04-01

    Five teen years later, Tchernobyl remains the symbol of the greater industrial nuclear accident. To take stock on this accident, this paper proposes a chronology of the events and presents the opinion of many international and national organizations. It provides also web sites references concerning the environmental and sanitary consequences of the Tchernobyl accident, the economic actions and propositions for the nuclear safety improvement in the East Europe. (A.L.B.)

  12. Consequences and problems of the Chernobyl accident

    The data on epidemic situation in connection with the Chernobyl accident, based on the personal medical and dosimetric information on all the persons, subjected to radiation effect, and included in the Russian state medicodosimetric register, are presented. The consequences of the Chernobyl accident become the cause for origination of serious radiation injures by 134 persons (with lethal outcome by 37 patients) and also remote radiation stochastic effects by children (thyroid gland cancer) and by liquidators (thyroid gland leucosis and cancer). The permanent stress and other unfavorable factors conditioned aggravation of chronical and increase in somatic diseases and psychoneurotic disorders

  13. Environmental consequences of releases from nuclear accidents

    The primary purpose of this report is to present the results of a four-year Nordic cooperation program in the area of consequence assessment of nuclear accidents with large releases to the environment. This program was completed in 1989. Related information from other research programs has also been described, so that many chapters of the report reflect the current status in the respective areas, in addition to containing the results of the Nordic program. (author) 179 refs

  14. Long-Term Station Blackout Accident Analyses of a PWR with RELAP5/MOD3.3

    Andrej Prošek

    2013-01-01

    Full Text Available Stress tests performed in Europe after accident at Fukushima Daiichi also required evaluation of the consequences of loss of safety functions due to station blackout (SBO. Long-term SBO in a pressurized water reactor (PWR leads to severe accident sequences, assuming that existing plant means (systems, equipment, and procedures are used for accident mitigation. Therefore the main objective was to study the accident management strategies for SBO scenarios (with different reactor coolant pumps (RCPs leaks assumed to delay the time before core uncovers and significantly heats up. The most important strategies assumed were primary side depressurization and additional makeup water to reactor coolant system (RCS. For simulations of long term SBO scenarios, including early stages of severe accident sequences, the best estimate RELAP5/MOD3.3 and the verified input model of Krško two-loop PWR were used. The results suggest that for the expected magnitude of RCPs seal leak, the core uncovery during the first seven days could be prevented by using the turbine-driven auxiliary feedwater pump and manually depressurizing the RCS through the secondary side. For larger RCPs seal leaks, in general this is not the case. Nevertheless, the core uncovery can be significantly delayed by increasing RCS depressurization.

  15. An assessment of the radiological consequences of accidents in research reactors

    This work analyses the radiological consequences of accidents in two types of research reactors: a 5 MWt open pool reactor and a 50 MWt PWR reactor. Two siting cases have been considered: the reactor located near to a large population center and sited in a rural area. The influence of several factors such as source term, meteorological conditions and population distribution have been considered in the present analysis. (author)

  16. Essential severe accident mitigation measures for operating and future PWR's

    Severe Accident mitigation measures are a constituent of the safety concept in Europe not only for operating but also for future light water reactors. While operating reactors mainly have been backfitted with such measure, for future reactors Severe Accident mitigation measures already have to be considered in the design phase. Severe Accident measures are considered as the 4th level of defense for future reactors. This difference has consequences also on the kind of measures proposed to be introduced. While in operating plants Severe Accident mitigation measures are considered for further risk reduction, in future reactors an explicit higher level of safety is required resulting in additional design measures. This higher safety level is expressed in the requirement that there must be no need for evacuation of surrounding populations except in the immediate vicinity of the plant and for long-term restrictions with regard to the consumption of locally grown food. Because of the potential hazard posed by radioactive releases to the environment in the event of an Severe Accident situation depends largely on the airborne material in the containment atmosphere and on the containment integrity, new system features to prevent loss of containment integrity have been introduced in the design of the NPP's. For these tasks it has been necessary to develop and qualify new system technologies and implement them finally into NPP's, e.g. like systems for containment atmosphere H2-control, filtered venting, core retention devices and atmosphere sampling. The following systems are introduced for operating as well as for future plants: · The Hydrogen Control System is based on the Passive Autocatalytic Recombiner (PAR) technology. There is no need for any operator actions because of the self-starting feature of the catalyst if hydrogen is released. · In situ Post Accident Sampling System (In situ-PASS) are introduced for the purpose of obtaining realistic information on airborne

  17. Experiments on natural circulation during PWR severe accidents and their analysis

    Buoyancy-induced natural circulation flows will occur during the early-part of PWR high pressure accident scenarios. These flows affect several key parameters; in particular, the course of such accidents will most probably change due to local failures occurring in the primary coolant system (CS) before substantial core degradation. Natural circulation flow patterns were measured in a one-seventh scale PWR PCS facility at Westinghouse RandD laboratories. The measured flow and temperature distributions are report in this paper. The experiments were analyzed with the COMMIX code and good agreement was obtained between data and calculations. 10 refs., 8 figs., 2 tabs

  18. Radiological consequences of the Chernobyl reactor accident

    Fifty years of peaceful utilization of nuclear power were interrupted by the reactor accident in unit 4 of the Chernobyl nuclear power station in Ukraine in 1986, a disruptive event whose consequences profoundly affected the way of life of millions of people, and which has moved the public to this day. Releases of radioactive materials contaminated large areas of Belarus, the Russian Federation, and Ukraine. Early damage in the form of radiation syndrome was suffered by a group of rescue workers and members of the reactor operating crew, in some cases with fatal consequences, while the population does not, until now, show a statistically significant increase in the rate of late damage due to ionizing radiation expect for thyroid diseases in children. In particular, no increases in the rates of solid tumors, leukaemia, genetic defects, and congenital defects were detected. For some risk groups exposed to high radiation doses (such as liquidators) the hazard may still be greater, but the large majority of the population need not live in fear of serious impacts on health. Nevertheless, the accident shows major negative social and psychological consequences reinforced by the breakdown of the Soviet Union. This may be one reason for the observed higher incidence of other diseases whose association with the effects of radiation as a cause has not so far been proven. The measurement campaign conducted by the federal government in 1991-1993 addressed these very concerns of the public in an effort to provide unbiased information about exposures detected, on the one hand, in order to alleviate the fears of the public and reduce stress and, on the other hand, to contribute to the scientific evaluation of the radiological situation in the regions most highly exposed. The groups of the population requiring special attention in the future include especially children growing up in highly contaminated regions, and the liquidators of 1986 and 1987 employed in the period immediately

  19. Remarks on methods of evaluation of aerosol sources related to PWR core meltdown accidents

    The paper tries to demonstrate the conceptional background of the KfK core melting program, which has been started in 1973, and which is scheduled to be terminated by 1986. The paper also summarizes the main findings of the SASCHA program, with the aid of which the enveloping fission product release from the primary system into the containment during a PWR core melt accident has been investigated. The fractions of release from the fuel determined in the experiment are undoubtedly in the range of 70% to 100% for the radiologically most important elements I, Cs, Te. The reduction in release from the primary circuit due to deposition is 50% at the maximum. A considerable portion resuspended must be deducted from that value. The retention of iodine and aerosol particles in the safety containment amounts to several orders of magnitude (up to 5). Likewise, the decrease in the population dose by spread and dilution in the environment and due to other parameters attains several orders of magnitude (up to 7). Consequently, particle retention by a factor of 2 or 3 in the primary circuit is negligible. - Our present knowledge is completely satisfactory for analyzing the so-called source term in core melt accidents. The wish to develop more detailed codes related to core degradation and to activity release from the primary circuit has many understandable causes. However, there is no single technical reason in favor of spending much money in order to materialize this wish. (orig./HP)

  20. The consequences of the Chernobyl reactor accident

    After the decay of the iodine isotopes the measuring campaigns, in addition to the measuring of soil pollution and pollution of products, concentrated on the way of the cesium isotopes through the food chain, especially in crops, milk, meat and mother's milk. A special programme was developed for the analysis of foreign basic substances for teas, essences and tinctures. In connection with the incorporation measurements in the university hospital Eppendorf the measurement campaigns provided the data material in order to calculate with the aid of the computer program ECOSYS of the GSF the effective dose equivalent which the inhabitants of Hamburg additionally take up due to the accident of Chernobyl. Consequences with regard to measuring methods and social consequences are mentioned. (DG)

  1. Rupther: a simulation approach applied to a PWR vessel failure during a severe accident

    The Rupther program (Rupture Under Thermal Conditions) is a part of the international researches on severe accidents in the PWR type reactors. The aim of the program is the definition of failure simulation validated by experimental data on vessel steel 16MND5 mechanical properties. The paper presents the program and the first results. (A.L.B.)

  2. Cosyma a new programme package for accident consequence assessment

    This report gives details of a new programme package for accident consequence assessment, prepared under the CEC's Maria programme (Methods for assessing the radiological impact of accidents) initiated in 1982 to review and build on the nuclear accident consequence assessment methods in use within the European Community

  3. INTERCOMPARISON OF RESULTS FOR A PWR ROD EJECTION ACCIDENT

    DIAMOND,D.J.; ARONSON,A.; JO,J.; AVVAKUMOV,A.; MALOFEEV,V.; SIDOROV,V.; FERRARESI,P.; GOUIN,C.; ANIEL,S.; ROYER,M.E.

    1999-10-01

    This study is part of an overall program to understand the uncertainty in best-estimate calculations of the local fuel enthalpy during the rod ejection accident. Local fuel enthalpy is used as the acceptance criterion for this design-basis event and can also be used to estimate fuel damage for the purpose of determining radiological consequences. The study used results from neutron kinetics models in PARCS, BARS, and CRONOS2, codes developed in the US, the Russian Federation, and France, respectively. Since BARS uses a heterogeneous representation of the fuel assembly as opposed to the homogeneous representations in PARCS and CRONOS, the effect of the intercomparison was primarily to compare different intra-assembly models. Quantitative comparisons for core power, reactivity, assembly fuel enthalpy and pin power were carried out. In general the agreement between methods was very good providing additional confidence in the codes and providing a starting point for a quantitative assessment of the uncertainty in calculated fuel enthalpy using best-estimate methods.

  4. A general approach to critical infrastructure accident consequences analysis

    Bogalecka, Magda; Kołowrocki, Krzysztof; Soszyńska-Budny, Joanna

    2016-06-01

    The probabilistic general model of critical infrastructure accident consequences including the process of the models of initiating events generated by its accident, the process of environment threats and the process of environment degradation is presented.

  5. Environmental consequences of releases from nuclear accidents

    The report presents the results of a four-year Nordic cooperation project (AKTU-200). The results have impact upon many facets of accident consequence assessment, ranging from new computational tools to recommendations concerning food preparation methods to be utilized in a fallout situation. Some of the subprojects have approached areas where little or no research has been performed previously, like the project on winter conditions, the project on the physico/chemical form of radionuclides in the Chernobyl fallout, and the project on resuspension. The conclusion from the first of these projects is that the impact of an accident or fallout situation occuring during winter may be considerable smaller than in a similar situation during summer conditions. The most important conclusion from the second of these projects is that bioavailability of radiocesium in soil is significantly lower than that of radiocesium in plant material taken up via the roots. In the third project is was found that the resuspension factor is several orders of magnitude lower than the values traditionally cited, and that resuspension is a local phenomenon in a majority of weather conditions. The development of large-scale testing of mitigating actions to prevent uptake of radiocesium in animals in a fallout situation is also one of the projects where new ground has been sucessfully broken. 189 refs., 89 figs., 55 tabs

  6. Development of evaluation method for economic consequences of severe accident at NPP

    A nuclear power plant accident has onsite and/or offsite consequences. A common framework into which many of the consequences of an accident may be translated is their economic cost. Though there are some consequence analysis codes, these are limited only to estimate only offsite consequence. In this study, economic losses are estimated for the case of onsite and offsite consequences for the sample PWR plant at Yong-Gwang site. For the estimation of offsite consequence, economic database unique to Korean economic structure is utilized as many as possible. By grouping of various cost components, each cost groups are compared each other. For the detailed estimation of offsite decontamination cost, offsite surface around the plant is divided into five types of surface. This division of surface types is agricultural field, wooded land, roof surface for representing house, asphalt road and water surface. But on the water surface, it is assumed that no decontamination operation is required. The comparison shows that at the severe accident, offsite consequences are more severe than onsite consequences. And in agricultural growing season, the consequence even becomes more severe. It also turned out that the importance and selection of much appropriate criteria will play a major role, because the economic consequences are widely varying depending on how the criteria was chosen

  7. Simulation of a low-pressure severe accident scenario in a PWR with ATHLET-CD

    Hoffmann, Mathias; Koch, Marco K. [Bochum Univ. (Germany). Reactor Simulation and Safety Group

    2013-07-01

    The plant behavior of a Pressurized Water Reactor (PWR) during a severe accident scenario is analyzed with system code ATHLET-CD Mod. 2.2C in order to assess the code capabilities in terms of the late-phase of the core degradation. For this purpose a severe accident sequence caused by a Station Black-out and a large break in the primary cooling system is simulated both without any accident management measures and with a delayed reflooding of the substantially degraded core. Selected code results are presented in this paper. (orig.)

  8. A knowledge based severe accident handbook for PWR

    During the last decade the level of knowledge about severe accident phenomena has increased dramatically. The improved understanding has been achieved by extensive research but also from feed-back of experience from actual incidents/accidents such as Three Mile Island and Chernobyl. In Sweden, mitigating measures such as filtered venting and external water source were implemented at all nuclear power plants by 1988. In parallel the Emergency Operating Procedures (at Ringhals called Emergency Response Guidelines, ERG, and Beyond ERG, BERG) were developed to include these new features. However, the accident management system has since then been further improved and one important aspect is the long-term accident management. The new information obtained has been one of the basis for a new knowledge based handbook to support the unit leader and the Technical Support Center. The handbook contains information concerning specific issues in the BERG and advice how the organization can manage a long-term severe accident situation

  9. Chernobylsk accident (Causes and Consequences)-Part 1

    Facts, project data, hypothesis, calculations, evaluations, monitoring, standard requirements and several considerations, related to causes, effects and consequences of Chernobylsk-4 accident. (M.C.K.)

  10. International experience with a multidisciplinary table top exercise for response to a PWR accident

    Table Top Exercises are used for the training of emergency response personnel from a wide range of disciplines whose duties range from strategic to tactical, from managerial to operational. The exercise reported in this paper simulates the first two or three hours of an imaginary accident on a generic PWR site (named Seaside or Lakeside depending on its location). It is designed to exercise the early response of staff of the utility, government, local authority and the media and some players represent the public. The relatively few scenarios used for this exercise are based on actual events scaled to give off-site consequences which demand early assessment and therefore stress the communication procedures. The exercise is applicable in different cultures and has been used in over 20 short courses held in the USA, UK, Sweden, Prague, and Hong Kong. There are two styles of support for players: a linear program which ensures that all players follow the desired path through the event and an open program which is triggered by umpires (who play the reactor crew from a script) and by requests from other players. In both cases the exercise ends with a Press Conference. Players have an initial briefing and are assigned to roles; those who must speak at interviews and at the Press Conference arc given separate briefing by an expert in Public Affairs. The exercise runs with up to six groups and the communication rate reaches about 30 to 40 messages per hour for each group. The exercise can be applied to test management and communication systems and to study human response to emergencies because the merits of individual players are highlighted in the relatively stressful conditions of the initial stage of an accident. For some players the exercise is the first time that they have been required to carry out their task in front of other people

  11. Cost per severe accident as an index for severe accident consequence assessment and its applications

    The Fukushima Accident emphasizes the need to integrate the assessments of health effects, economic impacts, social impacts and environmental impacts, in order to perform a comprehensive consequence assessment of severe accidents in nuclear power plants. “Cost per severe accident” is introduced as an index for that purpose. The calculation methodology, including the consequence analysis using level 3 probabilistic risk assessment code OSCAAR and the calculation method of the cost per severe accident, is proposed. This methodology was applied to a virtual 1,100 MWe boiling water reactor. The breakdown of the cost per severe accident was provided. The radiation effect cost, the relocation cost and the decontamination cost were the three largest components. Sensitivity analyses were carried out, and parameters sensitive to cost per severe accident were specified. The cost per severe accident was compared with the amount of source terms, to demonstrate the performance of the cost per severe accident as an index to evaluate severe accident consequences. The ways to use the cost per severe accident for optimization of radiation protection countermeasures and for estimation of the effects of accident management strategies are discussed as its applications. - Highlights: • Cost per severe accident is used for severe accident consequence assessment. • Assessments of health, economic, social and environmental impacts are included. • Radiation effect, relocation and decontamination costs are important cost components. • Cost per severe accident can be used to optimize radiation protection measures. • Effects of accident management can be estimated using the cost per severe accident

  12. Calculation of dose consequences of a hypothetical large accident at a nuclear power reactor

    The fission product release to the atmosphere from a nuclear reactor during a hypothetical large accident is discussed, and the consequences in terms of doses to the population are calculated. The reactor is a light-water reactor located at a site representing an idealized, simplified Danish location. Three release categories are discussed: The first is the release in an accident with a core meltdown and a major rupture of the containment. This release is represented by the BWR-2 release of WASH-1400. The second is the release where the containment integrity is maintained, but there is a failure to isolate the containment. This release is represented by the PWR-4 release. The third is obtained as a Best Estimate from Empirical Data, and it is called the BEED release. The release of the BEED case is deduced from empirical evidence - especially the SL-1 accident - in a seperate study which is described in the appendix. The release fractions for the most significant elements such as iodine and cesium decrease by a decade from BWR-2 to PWR-4, and from PWR-4 to BEED, while the release fractions of the noble gases are assumed to be at an almost constant high level. The dose consequences in terms of a long-term committed effective dose equivalent is found to be practically directly proportional to the release fractions, i.e. decreasing by a decade from BWR-2 to PWR-4, and from PWR-4 to BEED. For the acute bone marrow dose the contribution from the noble gases is significant in all three cases, and as the noble gas release is almost constant the decrease from one case to the next is of the order of only half a decade. For the BEED case the noble gases, which give an external gamma dose from the plume, are the most significant radioactive fission products, both for long-term and acute doses. For the BWR-2 and PWR-4 cases the I-131 in the plume is predominant in the acute dose, while Cs-137 deposited on the ground is the main contributor to the long-term dose. (author)

  13. Consequences of the Fukushima accident: A preliminary assessment and discussion

    Tsunami due to the earthquake in East Japan Sea eventually leaded to a severe nuclear accident in Fukushima Dai-ichi nuclear power plant. This event immediately became the focus of the whole world. The work to roughly evaluate and predict the consequence of this nuclear accident is summarized in this paper and the work actually provides valuable information in predicting the scale and severity of the accident comparing to the published information on the accident thereafter. (authors)

  14. Probabilistic consequence analysis of ATWSs in a PWR plant

    PWR responses (in terms of overpressures, DNBR and other safety-related quantities) to ATWSs are being probabilistically investigated by applying response surface methodology to ALMOD, a computer program for simulation of large amplitude transients. The reactor considered for the analysis is the 1300 MWel reference KWU reactor plant. A comprehensive set of input quantities--including operational, engineering and physical variables--is taken into account. Results are presented for the first phases of station-blackout and loss-of-heat sink ATWSs

  15. Medical consequences of a nuclear plant accident

    The report gives background information concerning radiation and the biological medical effects and damages caused by radiation. The report also discusses nuclear power plant accidents and efforts from the medical service in the case of a nuclear power plant accident. (L.F.)

  16. Reassessment of PWR pressure-vessel integrity during overcooling accidents

    A continuing analysis of the PTS problem associated with PWR postuated OCA's indicates that the previously accepted degree of conservatism in the fracture-mechanics model needs to be more closely evaluated, and if excessive, reducted. One feature that was believed to be conservative was the use of two-dimensional as opposed to finite-length (three-dimensional) flaws. A flaw of particular interest is one that is located in an axial weld of a plate-type vessel. For those vessels that suffer relatively high radiation damage in the welds, the length of the flaw will be no greater than the length of the weld, and recent calculations indicate that a deep flaw of that length (approx. 2 m) is not effectively infinitely long, contrary to previous thinking. The benefit to be derived from consideration of the 2-m flaw and also a semielliptical flaw with a length-to-depth ratio of 6/1 was investigated by analyzing several postulated transients. In doing so the sensitivity of the benefit to a specified maximum crack arrest toughness and to the duration of the transient was investigated. Results of the analysis indicate that for some conditions the benefit in using the 2-m flaw is substantial, but it decreases with increasing pressure, and above a certain pressure there may be no benefit, depending on the duration of the transient and the limit on crack arrest toughness

  17. Accident management following loss-of-coolant accidents during cooldown in a Westinghouse two-loop PWR

    Operation of pressurised water reactors involves shutdown periods for refuelling and maintenance. In preparation for this, the reactor system is cooled down, depressurised and partially drained. Although reactor coolant pressure is lower than during full-power operation, there remains the possibility of a loss-of-coolant accident (LOCA), with a certain but low probability. While the decay heat to be removed is lower than that from a LOCA at full power, the reduced availability of safety systems implies a risk of failing to maintain core cooling, and hence of core damage. This is recognised though probabilistic safety analyses (PSA), which identify low but non-negligible contributions to core damage frequency from accidents during cooldown and shutdown. Analyses are made for a typical two-loop Westinghouse PWR of the consequences of a range of LOCAs during hot and intermediate shutdown, 4 and 5 h after reactor shutdown respectively. The accumulators are isolated, while power to some of the pumped safety injection systems (SIs) is racked out. The study assesses the effectiveness of the nominally assumed SIs in restoring coolant inventory and preventing core damage, and the margin against core damage where their actuation is delayed. The calculations use the engineering-level MELCOR1.8.5 code, supplemented by the SCDAPSIM and SCDAP/RELAP5 codes, which provide a more detailed treatment of coolant system thermal hydraulics and core behaviour. Both treatments show that the core is readily quenched, without damage, by the nominal SI which assumes operation of only one pump. Margins against additional scenario and model uncertainties are assessed by assuming a delay of 900 s (the time needed to actuate the remaining pumps) and a variety of assumptions regarding models and the number of pumps available in conjunction with both MELCOR and versions of SCDAP. Overall, the study provides confidence in the inherent robustness of the plant design with respect to LOCA during

  18. Accident management following loss-of-coolant accidents during cooldown in a Westinghouse two-loop PWR

    Haste, T.J., E-mail: tim.haste@irsn.f [Paul Scherrer Institut (PSI), CH-5232 Villigen (Switzerland); Birchley, J. [Paul Scherrer Institut (PSI), CH-5232 Villigen (Switzerland); Richner, M. [Nordostschweizerische Kraftwerke (NOK) - NPP Beznau, CH-5312 Doettingen (Switzerland)

    2010-06-15

    Operation of pressurised water reactors involves shutdown periods for refuelling and maintenance. In preparation for this, the reactor system is cooled down, depressurised and partially drained. Although reactor coolant pressure is lower than during full-power operation, there remains the possibility of a loss-of-coolant accident (LOCA), with a certain but low probability. While the decay heat to be removed is lower than that from a LOCA at full power, the reduced availability of safety systems implies a risk of failing to maintain core cooling, and hence of core damage. This is recognised though probabilistic safety analyses (PSA), which identify low but non-negligible contributions to core damage frequency from accidents during cooldown and shutdown. Analyses are made for a typical two-loop Westinghouse PWR of the consequences of a range of LOCAs during hot and intermediate shutdown, 4 and 5 h after reactor shutdown respectively. The accumulators are isolated, while power to some of the pumped safety injection systems (SIs) is racked out. The study assesses the effectiveness of the nominally assumed SIs in restoring coolant inventory and preventing core damage, and the margin against core damage where their actuation is delayed. The calculations use the engineering-level MELCOR1.8.5 code, supplemented by the SCDAPSIM and SCDAP/RELAP5 codes, which provide a more detailed treatment of coolant system thermal hydraulics and core behaviour. Both treatments show that the core is readily quenched, without damage, by the nominal SI which assumes operation of only one pump. Margins against additional scenario and model uncertainties are assessed by assuming a delay of 900 s (the time needed to actuate the remaining pumps) and a variety of assumptions regarding models and the number of pumps available in conjunction with both MELCOR and versions of SCDAP. Overall, the study provides confidence in the inherent robustness of the plant design with respect to LOCA during

  19. Fast detections of the accident. Radiological consequences

    This paper shows how the contamination due to the accident of Chernobylsk has been discovered in Sweden. The Swedish national Institute of radio-protection describes in detail the measurements done, and the decisions of radioprotection which have been taken

  20. Basic study on PWR plant behavior under the condition of severe accident

    In this paper, we report on the core cooling effect by natural circulation cooling of the primary cooling system in all core cooling function loss accidents caused by SBO in PWR plant compared with BWR. We also report on the core cooling effect by using air as the final heat sink in place of the seawater by opening the main steam valve of the steam generator. On the other hand, we discuss the behavior of PWR plant in the most serious case that the damage such as LOCA is caused by earthquake and that SBO due to the subsequent tsunami causes the reactor isolation and all function of reactor core cooling system loss. That is the case that LOCA and SBO occur in superimposed manner. We can show the results from the simulation experiments that, in PWR plant, even if it is fell into the reactor core cooling function loss due to SBO, natural circulation cooling can keep the reactor core cool down as long as the feed water is supplied to SG by the turbine-driven auxiliary feed-water pump and also that the cooling effect of even more is expected by ensuring the heat-pass to the atmosphere by opening the main steam valve. We also clarify the plant behaviors under the condition that LOCA and SBO occur in superimposed manner in PWR through the simulation experiments. (author)

  1. Source term and radiological consequences of the Chernobyl accident

    This report presents the results of a study of the source term and radiological consequences of the Chernobyl accident. The results two parts. The first part was performed during the first 2 months following the accident and dealt with the evaluation of the source term and an estimate of individual doses in the European countries outside the Soviet Union. The second part was performed after August 25-29, 1986 when the Soviets presented in a IAEA Conference in Vienna detailed information about the accident, including source term and radiological consequences in the Soviet Union. The second part of the study reconfirms the source term evaluated in the first part and in addition deals with the radiological consequences in the Soviet Union. Source term and individual doses are calculated from measured post-accident data, reported by the Soviet Union and European countries, microcomputer program PEAR (Public Exposure from Accident Releases). 22 refs

  2. The consequences of the Chernobyl nuclear accident in Greece

    In this report the radioactive fallout on Greece from the Chernobyl nuclear accident is described. The flow pattern to Greece of the radioactive materials released, the measurements performed on environmental samples and samples of the food chain, as well as some estimations of the population doses and of the expected consequences of the accident are presented. The analysis has shown that the radiological impact of the accident in Greece can be considered minor. (J.K.)

  3. Assessment and limitation of radioactivity transfers in the event of a postulated severe PWR accident

    This report constitutes the supporting material for a lecture on severe accidents which could occur on PWR type nuclear reactors. It is assumed for present purposes that the reader has at least a rudimentary acquaintance with the basics of general physics if not with the operating processes of these reactors. After defining what is meant by a ''severe accident'' on a reactor, the possible phenomenology of such an accident is qualitatively described: loss of coolant and loss of containment integrity. A certain number of elements are then given for the quantitative assessment of these phenomena involving possible radioactivity transfers within and outside the plant. In conclusion, available means are indicated for the limitation and control of these environmental transfers. (author). 5 refs, figs

  4. Consequences of the Chernobyl accident in Lithuania

    After the Chernobyl accident of 26 April, 1986, population dose assessment favours the view that the radiation risk of population effected by the early fallout would be different from that in regions contaminated later. Taking into account the short half-time of the most important radioactive iodine isotopes, thyroid disorders would be expected mainly to follow the early fallout distribution. At the time of accident at Unite 4 of the Chernobyl NPP, surface winds were from the Southeast. The initial explosions and heat carried volatile radioactive materials to the 1,5 km height, from where they were transported over the Western part of Belarus, Southern and Western part of Lithuania toward Scandinavian countries. Thus the volatile radioiodine and some other radionuclides were detected in Lithuania on the very first days after the accident. The main task of the work - to conduct short Half-time radioiodine and long half-time radiocesium dose assessment of Lithuanian inhabitants a result of the early Chernobyl accident fallout

  5. The Role of Countermeasures in Mitigating the Radiological Consequences of Nuclear Power Plant Accidents

    During the Fukushima accident the mitigation actions played an important role to decrease the consequences of the accident. The countermeasures are the actions that should be taken after the occurrence of a nuclear accident to protect the public against the associated risk. The actions may be represented by sheltering, evacuation, distribution of stable iodine tablets and/or relocation. This study represents a comprehensive probabilistic study to investigate the role of the adoption of the countermeasures in case of a hypothetical accident of type LOCA for a nuclear power plant of PWR (1000 Mw) type. This work was achieved through running of the PC COSYMA(1) code. The effective doses in different organs, short and long term health effects, and the associated risks were calculated with and without countermeasures. In addition, the overall costs of the accident and the costs of countermeasures are estimated which represent our first trials to know how much the postulated accident costs. The source term of a hypothetical accident is determined by knowing the activity of the core inventory. The meteorological conditions around the site in addition to the population distribution were utilized as input parameters. The stability conditions and the height of atmospheric boundary layers ABL of the concerned site were determined by developing a computer program utilizing Pasquill-Gifford atmospheric stability conditions. The results showed that, the area around the site requires early and late countermeasures actions after the accident especially in the downwind sectors. For late countermeasures, the duration of relocation ranged from about two to 10 years. The adoption of the countermeasures increases the costs of emergency planning by 40% but reduces the risk associated with the accident. (author)

  6. Analysis of a control rod ejection accident in a 900 MWe PWR recycling plutonium with a gray control mode

    This research thesis addresses the study of the control rod cluster ejection accident in a 900 MWe PWR recycling plutonium and operating in grey mode, a class-IV accident in the safety report, which results from the failure of the cluster mechanism pressure enclosure, and results in a quick introduction of a reactivity within the core, and then in a violent power transient during which fuel strength can be put into question again. Two aspects are thus notably addressed: plutonium recycling, and grey mode operation. The objective is to qualitatively and quantitatively assess the evolution of physical parameters during the accident in order to determine the most severe scenarios and to be able to assess the severity of consequences. The author first studies all possible scenarios by means of a 2D+1D+0D calculation scheme in order to determine the most penalizing ones. Then, he develops a precise calculation based on 3D steady calculations, neutron kinetics calculations and thermal kinetics calculations in order to study the previously retained scenarios

  7. Method for consequence calculations for severe accidents

    This report was commissioned by the Swedish State Power Board. The report contains a calculation of radiation doses in the surroundings caused by a theoretical core meltdown accident at Ringhals reactor No 3/4. The accident sequence chosen for the calcualtions was a release caused by total power failure. The calculations were made by means of the PLUCON4 code. A decontamination factor of 500 is used to account for the scrubber effect. Meteorological data for two years from the Ringhals meteorological tower were analysed to find representative weather situations. As typical weather, Pasquill D, was chosen with a wind speed of 10 m/s, and as extreme weather, Pasquill E, with a wind speed of 2 m/s. 19 refs. (author)

  8. Medical demographic consequences of the Chernobyl accident

    A demographic study was made of the population evacuated from the 30-km zone around the nuclear power plant and of the population living in areas over which the radioactive cloud passed and over which the plume was formed. For the farmers evacuated from 11,655 homes in the Chernobyl region, 7,000 new houses, built in the Kiev region, had already been provided within 5 months of the accident, and by the summer of 1987 another 5,000 houses were available. A study of the resettlement of the population carried out a year after the accident showed that more than 60% of those evacuated continued to live in the regions from which the evacuation had taken place; about 5% were resettled in other republics, and 20% within their own republic. (author). 7 figs, 2 tabs

  9. Appearing consequences of the Chernobyl accident

    Full text: Chernobyl is the greatest world's tragedy after Chirosima. Global results of this tragedy is already being seen. They are the people who have received radiation dose. the first type of cancer 5 years after Chernobyl accident was the thyroid gland cancer, the reason of it, large quantities of radioactive iodine in the air, food products, milk of cattle and finally their collection in the thyroid gland cancer entering the human body. Period all of a sudden after 10 years completed the next latent type of cancer was leykoz. Giving rise to this type of cancer more sensitive to radiation of the body - a violation of the spinal brain function. After 20 years passing from the accident in the first generation one ill child must be born cause of undergoing to radiation father or mother from each three days in Belarus, Russia and Ukraine

  10. Phenomenology and course of severe accidents in PWR-plants training by teaching and demonstration

    A special one day training course on 'Phenomenology and Course of Severe Accidents in PWR-Plants' was developed at GRS initiated by the interest of German utilities. The work was done in the frame of projects sponsored by the German Ministries for Environment, Nature Conservation and Nuclear Safety (BMW) and for Education, Science, Research and Technology (BMBF). In the paper the intention and the subject of this training course are discussed and selected parts of the training course are presented. Demonstrations are made within this training course with the GRS simulator system ATLAS to achieve a broader understanding of the phenomena discussed and the propagation of severe accidents on a plant specific basis. The GRS simulator system ATLAS is linked in this case to the integral code MELCOR and pre-calculated plant specific severe accident calculations are used for the demonstration together with special graphics showing plant specific details. Several training courses have been held since the first one in November, 1996 especially to operators, shift personal and the management board of a German PWR. In the meantime the training course was updated and suggestions for improvements from the participants were included. In the future this training course will be made available for members of crisis teams, instructors of commercial training centres and researchers of different institutions too. (author)

  11. Phenomenology and Course of Severe Accidents in PWR-Plants - Training by Teaching and Demonstration

    A special one day training course on 'Phenomenology and Course of Severe Accidents in PWR-Plants' was developed at GRS initiated by the interest of German utilities. The work was done in the frame of projects sponsored by the German Ministries for Environment, Nature Conservation and Nuclear Safety (BMU) and for Education, Science, Research and Technology (BMBF). In the paper the intention and the subject of this training course will be discussed and selected parts of the training course will be presented. Demonstrations are made within this training course with the GRS simulator system ATLAS to achieve a broader understanding of the phenomena discussed and the propagation of severe accidents on a plant specific basis. The GRS simulator system ATLAS is linked in this case to the integral code MELCOR and pre-calculated plant specific severe accident calculations are used for the demonstration together with special graphics showing plant specific details. Several training courses have been held since the first one in November, 1996 especially to operators, shift personal and the management board of a German PWR. In the meantime the training course was updated and suggestions for improvements from the participants were included. In the future this type of the training course will be made available for members of crisis teams, instructors of commercial training centres and researchers of different institutions too. (authors)

  12. Estimation of cost per severe accident for improvement of accident protection and consequence mitigation strategies

    To assess the complex situations regarding the severe accidents such as what observed in Fukushima Accident, not only radiation protection aspects but also relevant aspects: health, environmental, economic and societal aspects; must be all included into the consequence assessment. In this study, the authors introduce the “cost per severe accident” as an index to analyze the consequences of severe accidents comprehensively. The cost per severe accident consists of various costs and consequences converted into monetary values. For the purpose of improvement of the accident protection and consequence mitigation strategies, the costs needed to introduce the protective actions, and health and psychological consequences are included in the present study. The evaluations of these costs and consequences were made based on the systematic consequence analysis using level 2 and 3 probabilistic safety assessment (PSA) codes. The accident sequences used in this analysis were taken from the results of level 2 seismic PSA of a virtual 1,100 MWe BWR-5. The doses to the public and the number of people affected were calculated using the level 3 PSA code OSCAAR of Japan Atomic Energy Agency (JAEA). The calculations have been made for 248 meteorological sequences, and the outputs are given as expectation values for various meteorological conditions. Using these outputs, the cost per severe accident is calculated based on the open documents on the Fukushima Accident regarding the cost of protective actions and compensations for psychological harms. Finally, optimized accident protection and consequence mitigation strategies are recommended taking into account the various aspects comprehensively using the cost per severe accident. The authors must emphasize that the aim is not to estimate the accident cost itself but to extend the scope of “risk-informed decision making” for continuous safety improvements of nuclear energy. (author)

  13. Information on economic and social consequences of the Chernobyl accident

    This ''Information on economic and social consequences of the Chernobyl accident'' was presented to the July 1990 session of the Economic and Social Council of the United Nations by the delegations of the Union of Soviet Socialist Republics, the Byelorussian Soviet Socialist Republic and the Ukrainian Soviet Socialist Republic. It presents the radiation situation, the medical aspects of the accident, the evacuation of the inhabitants from areas affected by radioactive contamination and their social welfare, the agro-industrial production and forestry in these areas, the decontamination operations, the scientific back-up for the work dealing with the consequences of the accident and the expenditure and losses resulting from the Chernobyl disaster

  14. Modelling of whole-core release of fission products in PWR core melt accidents: Chapter 13

    The computer code FISREL combines the thermal history of a reactor core with experimentally-based release rate constants to calculate whole-core release histories of fission products in PWR core melt accidents. Predictions of the code for releases of volatile fission products during large-break, small-break and transient initiated sequences are presented, and the sensitivities of results to input data examined. A preliminary assessment of the limitations imposed by mass transport on release of vaporized materials in high pressure sequences is given, and the implications of the results for primary system transport are discussed

  15. Updating and testing of a PWR model for the Modular Accident Analysis Programe MAAP5

    Marcos Delgado, Elisabet

    2013-01-01

    The present Master’s Thesis is part of the Master’s degree in Nuclear Engineering of the Universitat Politècnica de Catalunya and the ENDESA Escuela de Energía, and it was developed during the internship in a Spanish Pressurized Water Reactor (PWR). The objective of the project is to update and test the nuclear plant model used for the Safety Analysis department which belongs to the Licensing Department mainly for Severe Accidents phenomenology studies to prepare for and respond to emergen...

  16. Thyroid consequences of the Chernobyl nuclear accident.

    Pacini, F; Vorontsova, T; Molinaro, E; Shavrova, E; Agate, L; Kuchinskaya, E; Elisei, R; Demidchik, E P; Pinchera, A

    1999-12-01

    It is well recognized that the use of external irradiation of the head and neck to treat patients with various non-thyroid disorders increases their risk of developing papillary thyroid carcinoma years after radiation exposure. An increased risk of thyroid cancer has also been reported in survivors of the atomic bombs in Japan, as well as in Marshall Island residents exposed to radiation during the testing of hydrogen bombs. More recently, exposure to radioactive fallout as a result of the Chernobyl nuclear reactor accident has clearly caused an enormous increase in the incidence of childhood thyroid carcinoma in Belarus, Ukraine, and, to a lesser extent, in the Russian Federation, starting in 1990. When clinical and epidemiological features of thyroid carcinomas diagnosed in Belarus after the Chernobyl accident are compared with those of naturally occurring thyroid carcinomas in patients of the same age group in Italy and France, it becomes apparent that the post-Chernobyl thyroid carcinomas were much less influenced by gender, virtually always papillary (solid and follicular variants), more aggressive at presentation and more frequently associated with thyroid autoimmunity. Gene mutations involving the RET proto-oncogene, and less frequently TRK, have been shown to be causative events specific for papillary cancer. RET activation was found in nearly 70% of the patients who developed papillary thyroid carcinomas following the Chernobyl accident. In addition to thyroid cancer, radiation-induced thyroid diseases include benign thyroid nodules, hypothyroidism and autoimmune thyroiditis, with or without thyroid insufficiency, as observed in populations after environmental exposure to radioisotopes of iodine and in the survivors of atomic bomb explosions. On this basis, the authors evaluated thyroid autoimmune phenomena in normal children exposed to radiation after the Chernobyl accident. The results demonstrated an increased prevalence of circulating thyroid

  17. ALIBABA: a French Expert System for PWR Containment Analysis in case of Severe Accidents

    In the event of an accident occurring in a French pressurized water reactor (PWR), the authorities should be in position to implement the measures required to protect the surrounding population and the environment from radiological consequences of potential releases. The Institute for Nuclear Safety and Protection is part of the national emergency organization established for this purpose. It provides technical support to the French nuclear safety authority. As a technical adviser, IPSN has defined a methodology intended to help assess the plant status and monitor its development as soon as the accident is detected. On the basis of this assessment, the method forecasts the potential behavior of the installation and estimates the related consequences. The state of the installation is evaluated throughout the accident with special reference to the three barriers stretched out between the radioisotopes and the environment (fuel cladding, reactor coolant system and the containment building). It considers successively their physical state, the state of the safety functions guaranteeing their integrity and finally the state of the systems available to monitor these functions. In order to properly diagnose and predict the state of the barriers, evaluations are necessary to quantify parameters such as the break size on the reactor coolant system, the time to core uncovering and the core degradation. As a result, fission products behavior inside the installation and releases outside the plant are assessed. Several flexible, rapid and user-friendly software tools, which are part of the French SESAME system, have been developed to help the experts with their assessment. products cannot be realistically quantified without a complete knowledge of the state of the containment barrier. The expert system ALIBABA is separate from these tools. It provides complementary qualitative information about the third barrier. Indeed, the ongoing or potential releases of fission products

  18. Simulation of fission products behavior in severe accidents for advanced passive PWR

    Highlights: • A fission product analysis model based on thermal hydraulic module is developed. • An assessment method for fission product release and transport is constructed. • Fission products behavior during three modes of containment response is investigated. • Source term results for the three modes of containment response are obtained. - Abstract: Fission product behavior for common Pressurized Water Reactor (PWR) has been studied for many years, and some analytical tools have developed. However, studies specifically on the behavior of fission products related to advanced passive PWR is scarce. In the current study, design characteristics of advanced passive PWR influencing fission product behavior are investigated. An integrated fission products analysis model based on a thermal hydraulic module is developed, and the assessment method for fission products release and transport for advanced passive PWR is constructed. Three modes of containment response are simulated, including intact containment, containment bypass and containment overpressure failure. Fission products release from the core and corium, fission products transport and deposition in the Reactor Coolant System (RCS), fission products transport and deposition in the containment considering fission products retention in the in-containment refueling water storage tank (IRWST) and in the secondary side of steam generators (SGs) are simulated. Source term results of intact containment, containment bypass and containment overpressure failure are obtained, which can be utilized to evaluate the radiological consequences

  19. Radiological attacks and accidents. Medical consequences

    Probability of the occurrence of radiological attacks appears to be elevated after the terrorist attacks against the United States on September 11 in 2001. There are a lot of scenarios of radiological attack: simple radiological device, radiological disperse device (RDD or dirty bomb), attacks against nuclear reactor, improvised nuclear device, and nuclear weapons. Of these, RDD attack is the most probable scenario, because it can be easily made and can generate enormous psychological and economic damages. Radiological incidents are occurring to and fro in the world, including several cases of theft to nuclear facilities and unsuccessful terrorist attacks against them. Recently, a former Russian spy has allegedly been killed using polonium-210. In addition, serious radiological accidents have occurred in Chernobyl, Goiania, and Tokai-mura. Planning, preparation, education, and training exercise appear to be essential factors to cope with radiological attacks and accidents effectively without feeling much anxiety. Triage and psychological first aid are prerequisite to manage and provide effective medial care for mass casualties without inducing panic. (author)

  20. A direct comparison of MELCOR 1.8.3 and MAAP4 results for several PWR ampersand BWR accident sequences

    This paper presents a comparison of calculations of severe accident progression for several postulated accident sequences for representative Pressurized Water Reactors (PWR) and Boiling Water Reactors (BWR) nuclear power plants performed with the MELCOR 1.8.3 and the MAAP4 computer codes. The PWR system examined in this study is a 1100 MWe system similar in design to a Westinghouse 3-loop plant with a large dry containment; the BWR is a 1100 MWe system similar in design to General Electric BWR/4 with a Mark I containment. A total of nine accident sequences were studied with both codes. Results of these calculations are compared to identify major differences in the timing of key events in the calculated accident progression or other important aspects of severe accident behavior, and to identify specific sources of the observed differences

  1. Brief account of the effect of overcooling accidents on the integrity of PWR pressure vessels

    The occurrence in recent years of several (PWR) accident initiating events that could lead to severe thermal shock to the reactor pressure vessel, and the growing awareness that copper and nickel in the vessel material significantly enhance radiation damage in the vessel, have resulted in a reevaluation of pressure-vessel integrity during postulated overcooling accidents. Analyses indicate that the accidents of concern are those involving both thermal shock and pressure loadings, and that an accident similar to that at Rancho Seco in 1978 could, under some circumstances and at a time late in the normal life of the vessel, result in propagation of preexistent flaws in the vessel wall to the extent that they might completely penetrate the wall. More severe accidents have been postulated that would result in even shorter permissible lifetimes. However, the state-of-the-art fracture-mechanics analysis may contain excessive conservatism, and this possibility is being investigated. Furthermore, there are several remedial measures, such as fuel shuffling, to reduce the damage rate, and vessel annealing, to restore favorable material properties, that may be practical and used if necessary. 5 figures

  2. Method for consequence calculations for severe accidents

    This report was commissioned by the Swedish State Power Board. The report contains a calculation of radiation doses in the surroundings caused by a theoretical core meltdown accident at Forsmark reactor No 3. The assumption used for the calculations were a 0.06% release of iodine and cesium corresponding to a 0.1% release through the FILTRA plant at Barsebaeck. The calculations were made by means of the PLUCON4 code. Meteorological data for two years from the Forsmark meteorological tower were analysed to find representative weather situations. As typical weather pasquill D was chosen with wind speed 5 m/s, and as extreme weather, Pasquill F with wind speed 2 m/s. 23 tabs., 36 ills., 21 refs. (author)

  3. Study On Safety Analysis Of PWR Reactor Core In Transient And Severe Accident Conditions

    The cooperation research project on the Study on Safety Analysis of PWR Reactor Core in Transient and Severe Accident Conditions between Institute for Nuclear Science and Technology (INST), VINATOM and Korean Atomic Energy Research Institute (KAERI), Korea has been setup to strengthen the capability of researches in nuclear safety not only in mastering the methods and computer codes, but also in qualifying of young researchers in the field of nuclear safety analysis. Through the studies on the using of thermal hydraulics computer codes like RELAP5, COBRA, FLUENT and CFX the thermal hydraulics research group has made progress in the research including problems for safety analysis of APR1400 nuclear reactor, PIRT methodologies and sub-channel analysis. The study of severe accidents has been started by using MELCOR in collaboration with KAERI experts and the training on the fundamental phenomena occurred in postulated severe accident. For Vietnam side, VVER-1000 nuclear reactor is also intensively studied. The design of core catcher, reactor containment and severe accident management are the main tasks concerning VVER technology. The research results are presented in the 9th National Conference on Mechanics, Ha Noi, December 8-9, 2012, the 10th National Conference on Nuclear Science and Technology, Vung Tau, August 14-15, 2013, as well as published in the journal of Nuclear Science and Technology, Vietnam Nuclear Society and other journals. The skills and experience from using computer codes like RELAP5, MELCOR, ANSYS and COBRA in nuclear safety analysis are improved with the nuclear reactors APR1400, Westinghouse 4 loop PWR and especially the VVER-1000 chosen for the specific studies. During cooperation research project, man power and capability of Nuclear Safety center of INST have been strengthen. Three masters were graduated, 2 researchers are engaging in Ph.D course at Hanoi University of Science and Technology and University of Science and Technology, Korea

  4. Consequence of potential accidents in heavy water plants

    Heavy water plants realize the primary isotopic concentrations of water using H2O-H2S chemical exchange and they are chemical plants. As these plants are handling and spreading large quantities of hydrogen sulphide (high toxic, corrosive, flammable and explosive as) maintained in the process at relative high temperatures and pressures, it is required an assessing of risks associated with the potential accidents. The H2S released in atmosphere as a result of an accident will have negative consequences to property, population and environment. This paper presents a model of consequences quantitative assessment and its outcome for the most dangerous accident in heavy water plants. Several states of the art risk based methods were modified and linked together to form a proper model for this analyse. Five basic steps to identify the risks involved in operating the plants are followed: hazard identification, accident sequence development, H2S emissions calculus, dispersion analyses and consequences determination. A brief description of each step and some information of analysis results are provided. The accident proportions, the atmospheric conditions and the population density in the respective area were accounted for consequences calculus. The specific results of the consequences analysis allow to develop the plant's operating safety requirements so that the risk remain at an acceptable level. (authors)

  5. Offsite Radiological Consequence Analysis for the Bounding Flammable Gas Accident

    Carro, C A

    2003-01-01

    This document quantifies the offsite radiological consequences of the bounding flammable gas accident for comparison with the 25 rem Evaluation Guideline established in DOE-STD-3009, Appendix A. The bounding flammable gas accident is a detonation in a single-shell tank The calculation applies reasonably conservation input parameters in accordance with DOE-STD-3009, Appendix A, guidance. Revision 1 incorporates comments received from Office of River Protection.

  6. MELCOR Accident Consequence Code System (MACCS)

    This report describes the MACCS computer code. The purpose of this code is to simulate the impact of severe accidents at nuclear power plants on the surrounding environment. MACCS has been developed for the US Nuclear Regulatory Commission to replace the previous CRAC2 code, and it incorporates many improvements in modeling flexibility in comparison to CRAC2. The principal phenomena considered in MACCS are atmospheric transport, mitigative actions based on dose projection, dose accumulation by a number of pathways including food and water ingestion, early and latent health effects, and economic costs. The MACCS code can be used for a variety of applications. These include (1) probabilistic risk assessment (PRA) of nuclear power plants and other nuclear facilities, (2) sensitivity studies to gain a better understanding of the parameters important to PRA, and (3) cost-benefit analysis. This report is composed of three volumes. This document, Volume 1, the Users's Guide, describes the input data requirements of the MACCS code and provides directions for its use as illustrated by three sample problems

  7. MELCOR Accident Consequence Code System (MACCS)

    Chanin, D.I. (Technadyne Engineering Consultants, Inc., Albuquerque, NM (USA)); Sprung, J.L.; Ritchie, L.T.; Jow, Hong-Nian (Sandia National Labs., Albuquerque, NM (USA))

    1990-02-01

    This report describes the MACCS computer code. The purpose of this code is to simulate the impact of severe accidents at nuclear power plants on the surrounding environment. MACCS has been developed for the US Nuclear Regulatory Commission to replace the previous CRAC2 code, and it incorporates many improvements in modeling flexibility in comparison to CRAC2. The principal phenomena considered in MACCS are atmospheric transport, mitigative actions based on dose projection, dose accumulation by a number of pathways including food and water ingestion, early and latent health effects, and economic costs. The MACCS code can be used for a variety of applications. These include (1) probabilistic risk assessment (PRA) of nuclear power plants and other nuclear facilities, (2) sensitivity studies to gain a better understanding of the parameters important to PRA, and (3) cost-benefit analysis. This report is composed of three volumes. This document, Volume 1, the Users's Guide, describes the input data requirements of the MACCS code and provides directions for its use as illustrated by three sample problems.

  8. Consequences of the Chernobyl accident in Styria

    We present results which document the contamination of Styria (Southern part of Austria) immediately after and in the years following the Chernobyl accident. The radioactivity and distribution of radionuclides in aerosols, rain water, soil, vegetation, animals and various samples of food are described in great detail. One of the key results is that the highest levels of contamination were found in two districts (Liezen, Deutschlandsberg), and the deposition rates for Cs-137 were determined to be in the range from 3 to about 80 kBq/m2. Of particular interest are studies concerning the migration and distribution of radionuclides in soil, the uptake of radiocesium by the aquatic vegetation and the existence of radionuclides in the natural ecosystem up to this day. Effective dose equivalents due to incorporated radiocesium was estimated to be 252.2 μSv for the adult population of Graz (capital of Styria) over the four years follwing the fallout. (authors) 17 papers are presented and are of INIS scope

  9. MELCOR Accident Consequence Code System (MACCS)

    This report describes the MACCS computer code. The purpose of this code is to simulate the impact of severe accidents at nuclear power plants on the surrounding environment. MACCS has been developed for the US Nuclear Regulatory Commission to replace the previously used CRAC2 code, and it incorporates many improvements in modeling flexibility in comparison to CRAC2. The principal phenomena considered in MACCS are atmospheric transport, mitigative actions based on dose projections, dose accumulation by a number of pathways including food and water ingestion, early and latent health effects, and economic costs. The MACCS code can be used for a variety of applications. These include (1) probabilistic risk assessment (PRA) of nuclear power plants and other nuclear facilities, (2) sensitivity studies to gain a better understanding of the parameters important to PRA, and (3) cost-benefit analysis. This report is composed of three volumes. Volume I, the User's Guide, describes the input data requirements of the MACCS code and provides directions for its use as illustrated by three sample problems. Volume II, the Model Description, describes the underlying models that are implemented in the code, and Volume III, the Programmer's Reference Manual, describes the code's structure and database management

  10. MELCOR Accident Consequence Code System (MACCS)

    This report describes the MACCS computer code. The purpose of this code is to simulate the impact of severe accidents at nuclear power plants on the surrounding environment. MACCS has been developed for the US Nuclear Regulatory Commission to replace the previously used CRAC2 code, and it incorporates many improvements in modeling flexibility in comparison to CRAC2. The principal phenomena considered in MACCS are atmospheric transport, mitigative actions based on dose projection, dose accumulation by a number of pathways including food and water ingestion, early and latent health effects, and economic costs. The MACCS code can be used for a variety of applications. These include (1) probabilistic risk assessment (PRA) of nuclear power plants and other nuclear facilities, (2) sensitivity studies to gain a better understanding of the parameters important to PRA, and (3) cost-benefit analysis. This report is composed of three volumes. Volume I, the User's Guide, describes the input data requirements of the MACCS code and provides directions for its use as illustrated by three sample problems. Volume II, the Model Description, describes the underlying models that are implemented in the code, and Volume III, the Programmer's Reference Manual, describes the code's structure and database management. 59 refs., 14 figs., 15 tabs

  11. MELCOR Accident Consequence Code System (MACCS)

    Jow, H.N.; Sprung, J.L.; Ritchie, L.T. (Sandia National Labs., Albuquerque, NM (USA)); Rollstin, J.A. (GRAM, Inc., Albuquerque, NM (USA)); Chanin, D.I. (Technadyne Engineering Consultants, Inc., Albuquerque, NM (USA))

    1990-02-01

    This report describes the MACCS computer code. The purpose of this code is to simulate the impact of severe accidents at nuclear power plants on the surrounding environment. MACCS has been developed for the US Nuclear Regulatory Commission to replace the previously used CRAC2 code, and it incorporates many improvements in modeling flexibility in comparison to CRAC2. The principal phenomena considered in MACCS are atmospheric transport, mitigative actions based on dose projection, dose accumulation by a number of pathways including food and water ingestion, early and latent health effects, and economic costs. The MACCS code can be used for a variety of applications. These include (1) probabilistic risk assessment (PRA) of nuclear power plants and other nuclear facilities, (2) sensitivity studies to gain a better understanding of the parameters important to PRA, and (3) cost-benefit analysis. This report is composed of three volumes. Volume I, the User's Guide, describes the input data requirements of the MACCS code and provides directions for its use as illustrated by three sample problems. Volume II, the Model Description, describes the underlying models that are implemented in the code, and Volume III, the Programmer's Reference Manual, describes the code's structure and database management. 59 refs., 14 figs., 15 tabs.

  12. Radioecological and dosimetric consequences of Chernobyl accident in France

    After ten years and the taking in account of numerous data, it can be affirmed that the dosimetric consequences of Chernobyl accident will have been limited in France. for the period 1986-2046, the individual middle efficient dose commitment, for the area the most reached by depositing is inferior to 1500 μSv, that represents about 1% of middle natural exposure in the same time. but mountains and forests can have more important surface activities than in plain. Everywhere else, it can be considered that the effects of Chernobyl accident are disappearing. the levels of cesium 137 are now often inferior to what they were before the accident. (N.C.)

  13. The Fukushima accident: radiological consequences and first lessons. Proceedings

    This document brings together the available presentations given at the conference organised by the French society of radiation protection about the Fukushima accident, its radiological consequences and the first lessons learnt. Sixteen presentations (slides) are compiled in this document and deal with: 1 - Accident progress and first actions (Thierry Charles, IRSN); 2 - Conditions and health monitoring of the Japanese intervention teams (Bernard Le Guen, EDF); 3 - The Intra Group action after the Fukushima accident (Michel Chevallier, Groupe Intra; Frederic Mariotte, CEA); 4 - Processing of effluents (Georges Pagis, Areva); 5 - Fukushima accident: impact on the terrestrial environment in Japan (Didier Champion, IRSN); 6 - Consequences of the Fukushima accident on the marine environment (Dominique Boust, IRSN); 7 - Territories decontamination perspectives (Pierre Chagvardieff, CEA); 8 - Actions undertaken by Japanese authorities (Florence Gallay, ASN); 9 - Japanese population monitoring and health stakes (Philippe Pirard, InVS); 10 - Citizen oversight actions implemented in Japan (David Boilley, ACRO); 11 - Implementation of ICRP's (International Commission on Radiological Protection) recommendations by Japanese authorities: first analysis (Jacques Lochard, CIPR); 12 - Control of Japan imported food stuff (David Brouque, DGAL); 13 - Questions asked by populations in France and in Germany (Florence-Nathalie Sentuc, GRS; Pascale Monti, IRSN); 14 - Labour law applicable to French workers working abroad (Thierry Lahaye, DGT); 15 - Protection of French workers working in Japan, Areva's experience (Patrick Devin, Areva); 16 - Fukushima accident experience feedback and post-accident nuclear doctrine (Jean-Luc Godet, ASN)

  14. Development of a parametric containment event tree model of a severe PWR accident

    The study supports the development project of STUK on 'Living' PSA Level 2. The main work objective is to develop review tools for the Level 2 PSA studies underway at the utilities. The SPSA (STUK PSA) code is specifically designed for the purpose. In this work, SPSA is utilized as the Level 2 programming and calculation tool. A containment event tree (CET) model is built for analysis of severe accidents at the Loviisa pressurized water reactor (PWR) units. Parametric models of severe accident progression and fission product behaviour are developed and integrated in order to construct a compact and self-contained Level 2 PSA model. The model can be easily updated to include new research results, and so it facilitates the Living PSA concept on Level 2 as well. The analyses of the study are limited to severe accidents starting from full-power operation and leading to core melting at a low primary system pressure. Severe accident progression from five plant damage states (PDSs) is examined, however the integration with Level 1 is deferred to more definitive, integrated, safety assessments. (34 refs., 5 figs., 9 tabs.)

  15. Regulatory Research of the PWR Severe Accident. Information Needs and Instrumentation for Hydrogen Control and Management

    Park, Gun Chul; Suh, Kune Y.; Lee, Jin Yong; Lee, Seung Dong [Seoul Nat' l Univ., Seoul (Korea, Republic of)

    2001-03-15

    The current research is concerned with generation of basic engineering data needed in the process of developing hydrogen control guidelines as part of accident management strategies for domestic nuclear power plants and formulating pertinent regulatory requirements. Major focus is placed on identification of information needs and instrumentation methods for hydrogen control and management in the primary system and in the containment, development of decision-making trees for hydrogen management and their quantification, the instrument availability under severe accident conditions, critical review of relevant hydrogen generation model and phenomena In relation to hydrogen behavior, we analyzed the severe accident related hydrogen generation in the UCN 3{center_dot}4 PWR with modified hydrogen generation model. On the basis of the hydrogen mixing experiment and related GASFLOW calculation, the necessity of 3-dimensional analysis of the hydrogen mixing was investigated. We examined the hydrogen control models related to the PAR(Passive Autocatalytic Recombiner) and performed MAAP4 calculation in relation to the decision tree to estimate the capability and the role of the PAR during a severe accident.

  16. Regulatory Research of the PWR Severe Accident. Information Needs and Instrumentation for Hydrogen Control and Management

    The current research is concerned with generation of basic engineering data needed in the process of developing hydrogen control guidelines as part of accident management strategies for domestic nuclear power plants and formulating pertinent regulatory requirements. Major focus is placed on identification of information needs and instrumentation methods for hydrogen control and management in the primary system and in the containment, development of decision-making trees for hydrogen management and their quantification, the instrument availability under severe accident conditions, critical review of relevant hydrogen generation model and phenomena In relation to hydrogen behavior, we analyzed the severe accident related hydrogen generation in the UCN 3·4 PWR with modified hydrogen generation model. On the basis of the hydrogen mixing experiment and related GASFLOW calculation, the necessity of 3-dimensional analysis of the hydrogen mixing was investigated. We examined the hydrogen control models related to the PAR(Passive Autocatalytic Recombiner) and performed MAAP4 calculation in relation to the decision tree to estimate the capability and the role of the PAR during a severe accident

  17. First international workshop on severe accidents and their consequences. [Chernobyl Accident

    1989-07-01

    An international workshop on past severe nuclear accidents and their consequences was held in Dagomys region of Sochi, USSR on October 30--November 3, 1989. The plan of this meeting was approved by the USSR Academy of Sciences and by the USSR State Committee of the Utilization of Atomic Energy. The meeting was held under the umbrella of the ANS-SNS agreement of cooperation. Topics covered include analysis of the Chernobyl accident, safety measures for RBMK type reactors and consequences of the Chernobyl accident including analysis of the ecological, genetic and psycho-social factors. Separate reports are processed separately for the data bases. (CBS)

  18. OFFSITE RADIOLOGICAL CONSEQUENCE ANALYSIS FOR THE BOUNDING FLAMMABLE GAS ACCIDENT

    This document quantifies the offsite radiological consequences of the bounding flammable gas accident for comparison with the 25 rem Evaluation Guideline established in DOE-STD-3009, Appendix A. The bounding flammable gas accident is a detonation in a SST. The calculation applies reasonably conservative input parameters in accordance with guidance in DOE-STD-3009, Appendix A. The purpose of this analysis is to calculate the offsite radiological consequence of the bounding flammable gas accident. DOE-STD-3009-94, ''Preparation Guide for US. Department of Energy Nonreactor Nuclear Facility Documented Safety Analyses'', requires the formal quantification of a limited subset of accidents representing a complete set of bounding conditions. The results of these analyses are then evaluated to determine if they challenge the DOE-STD-3009-94, Appendix A, ''Evaluation Guideline,'' of 25 rem total effective dose equivalent in order to identify and evaluate safety-class structures, systems, and components. The bounding flammable gas accident is a detonation in a single-shell tank (SST). A detonation versus a deflagration was selected for analysis because the faster flame speed of a detonation can potentially result in a larger release of respirable material. A detonation in an SST versus a double-shell tank (DST) was selected as the bounding accident because the estimated respirable release masses are the same and because the doses per unit quantity of waste inhaled are greater for SSTs than for DSTs. Appendix A contains a DST analysis for comparison purposes

  19. The Chernobyl reactor accident - provisional results and consequences

    Those involved at present in the analysis and estimation of consequences of the Chernobyl reactor accident are in a dilemma: While a worried and uncertain Western German public is calling for information the Soviet Union was practicing a rigorously restrictive information policy. Both the severity of the reactor accident and the complexity of events do urgently require the acquisition and evaluation of facts which will provide the basis for an objective factual discussion of issues and possible measures. The paper abstracted is trying to assess the alleged causes of the accident and estimate possible consequences. However, all attempts of that kind are based but on incomplete and dubious information as of May 21st, 1986. (orig.)

  20. Cold leg condensation model for analyzing loss-of-coolant accident in PWR

    Liao, Jun, E-mail: liaoj@westinghouse.com; Frepoli, Cesare; Ohkawa, Katsuhiro

    2015-04-15

    Highlights: • Direct contact cold leg condensation model for full spectrum LOCA evaluation model. • The cold leg condensation model addresses both large break LOCA and small break LOCA. • The model is assessed against both large break and small break LOCA experiments. • Scalability of the cold leg condensation model to full scale PWR is discussed. - Abstract: Direct contact condensation in the cold leg of pressurized water reactor is an important phenomenon during a postulated loss-of-coolant accident. The amount of condensation in the cold legs impacts the thermal hydraulic behavior of the reactor coolant system and eventually the integration of reactor nuclear core. A cold leg condensation model was developed for the WCOBRA/TRAC-TF2 safety analysis code. The model correlated the COSI test data and addressed the scaling issues with respect to geometry, pressure, and steam and water flow rates expected during a typical PWR LOCA. The correlation was found to be in good agreement with separate effects and integral effects experimental data and implemented in the WCOBRA/TRAC-TF2 safety analysis code. The cold leg condensation model was assessed against various small break and large break LOCA separate effects tests such as COSI experiments, ROSA experiments and UPTF experiments. Those experiments cover a wide range of cold leg dimensions, system pressures, mass flow rates, and fluid properties. All the predicted condensation results match reasonably well with the experimental data. Scalability discussions on the diameter, flow area, length, superficial velocity, Reynolds number of both cold leg and SI line, and Froude number of SI line in the Westinghouse COSI test facility were provided. The distortion of the SI jet Reynolds number is moderate. The scaling analysis together with the validation matrix covering a wide range of cold leg diameter, SI flow rate and SI Reynolds number support the scalability of the developed cold leg condensation model to the full

  1. Remote medical consequences of Chernobyl NPP accident in Armenia

    In result of global radio-ecological disaster at the Chernobyl NPP in Armenia there has appeared a great 'risk group' of persons, who had participated in liquidation of the accident consequences. The results of medical observation of this cohort carried out in dynamics in Scientific Center of Radiation Medicine and Burns during 25 years are brought in the work

  2. Hanford Waste Tank Bump Accident and Consequence Analysis

    BRATZEL, D.R.

    2000-06-20

    This report provides a new evaluation of the Hanford tank bump accident analysis and consequences for incorporation into the Authorization Basis. The analysis scope is for the safe storage of waste in its current configuration in single-shell and double-shell tanks.

  3. Hanford Waste Tank Bump Accident and Consequence Analysis

    This report provides a new evaluation of the Hanford tank bump accident analysis and consequences for incorporation into the Authorization Basis. The analysis scope is for the safe storage of waste in its current configuration in single-shell and double-shell tanks

  4. Radioecological and dosimetric consequences of the Chernobyl accident in France

    This study has as objective a survey of the radioecological and dosimetric consequences of the Chernobyl accident in France, as well as a prognosis for the years to come. It was requested by the Direction of Nuclear Installation Safety (DSIN) in relation to different organisms which effected measurements after this accident. It is based on the use of combined results of measurements and modelling by means of the code ASTRAL developed at IPSN. Various measurements obtained from five authorities and institutions, were made available, such as: activity of air and water, soil, processed food, agricultural and natural products. However, to achieve the survey still a modelling is needed. ASTRAL is a code for evaluating the ecological consequences of an accident. It allows establishing the correspondence between the soil Remnant Surface Activities (RSA, in Bq.m-2), the activity concentration of the agricultural production and the individual and collective doses resulting from external and internal exposures (due to inhalation and ingestion of contaminated nurture). The results of principal synthesis documents on the Chernobyl accident and its consequences were also used. The report is structured in nine sections, as follows: 1.Introduction; 2.Objective and methodology; 3.Characterization of radioactive depositions; 4;Remnant surface activities; 5.Contamination of agricultural products and foods; 6.Contamination of natural, semi-natural products and of drinking water; 7.Dosimetric evaluations; 8.Proposals for the environmental surveillance; 9.Conclusion. Finally, after ten years, one concludes that at present the dosimetric consequences of the Chernobyl accident in France were rather limited. For the period 1986-2046 the average individual effective dose estimated for the most struck zone is lower than 1500 μSv, which represents almost 1% of the average natural exposure for the same period. At present, the cesium 137 levels are at often inferior to those recorded before

  5. Status on development and verification of reactivity initiated accident analysis code for PWR (NODAL3)

    A coupled neutronics thermal-hydraulics code NODAL3 has been developed based on the nodal few-group neutron diffusion theory in 3-dimensional Cartesian geometry for a typical pressurized water reactor (PWR) static and transient analyses, especially for reactivity initiated accidents (RIA). The spatial variables are treated by using a polynomial nodal method (PNM) while for the neutron dynamic solver the adiabatic and improved quasi-static methods are adopted. A simple single channel thermal-hydraulics module and its steam table is implemented into the code. Verification works on static and transient benchmarks are being conducting to assess the accuracy of the code. For the static benchmark verification, the IAEA-2D, IAEA-3D, BIBLIS and KOEBERG light water reactor (LWR) benchmark problems were selected, while for the transient benchmark verification, the OECD NEACRP 3-D LWR Core Transient Benchmark and NEA-NSC 3-D/1-D PWR Core Transient Benchmark (Uncontrolled Withdrawal of Control Rods at Zero Power). Excellent agreement of the NODAL3 results with the reference solutions and other validated nodal codes was confirmed. (author)

  6. Consequences of Chernobyl accident in Europe

    ,000 'liquidators' ranged between 170 mSv in 1986 and 15 mSv in 1989. Among the >100,000 evacuees the average whole body dose prior to evacuation was 15 mSv. The average lifetime Chernobyl whole body doses in European countries outside the former Soviet Union range from 0.006 mSv in Portugal to 2.4 mSv in Bulgaria. In the Northern Hemisphere the average Chernobyl lifetime dose is 0.14 mSv, i.e. about 0.08% of the natural dose. The average global whole body dose of natural radiation during 70 years is about 170 mSv, and 700 mSv in typically high background areas. Epidemiological studies from Hiroshima and Nagasaki suggest that no increase in cancer mortality should be expected at a single whole body dose (in addition to natural background radiation) of <200 mSv, delivered during a fraction of a second. Doses of about 200 mSv accumulated over tens of years of exposure would be even less effective. Ten years after the Chernobyl catastrophe the total radiation death toll is 31 - 38 persons, among them 3 persons were the members of the public. The total expected number of thyroid cancer deaths is about 500. In Poland, a country closest to Chernobyl outside the former Soviet Union, during two days, starting on the second day after arrival of radioactive cloud, 18.5 million persons were administered a prophylactic dose of stable iodine in form of 'Lugol solution', to block the uptake of radioiodine by the thyroid. This caused a thyroid dose reduction by a factor of up to 5, without any intra-thyroid side effects. Economic loses related to necessary and unnecessary remedial measures are estimated to reach in Belarus between 1986 and 2015 US$ 191.7 billion, of which US$ 86.32 billion are costs of financial and other compensation ('privileges') for peoples living at contaminated regions. It is estimated that in Ukraine in regions where 'Chernobyl radiation dose' is less than 1 mSv/year about 1.73 million persons receives the 'privileges'. Psychosomatic consequences of radiophobia induced by

  7. Radiological consequences of accidents during disposal of spent nuclear fuel in a deep borehole

    Grundfelt, Bertil [Kemakta Konsult AB, Stockholm (Sweden)

    2013-07-15

    In this report, an analysis of the radiological consequences of potential accidents during disposal of spent nuclear fuel in deep boreholes is presented. The results presented should be seen as coarse estimates of possible radiological consequences of a canister being stuck in a borehole during disposal rather than being the results of a full safety analysis. In the concept for deep borehole disposal of spent nuclear fuel developed by Sandia National Laboratories, the fuel is assumed to be encapsulated in mild steel canisters and stacked between 3 and 5 km depth in boreholes that are cased with perforated mild steel casing tubes. The canisters are joined together by couplings to form strings of 40 canisters and lowered into the borehole. When a canister string has been emplaced in the borehole, a bridge plug is installed above the string and a 10 metres long concrete plug is cast on top of the bridge plug creating a floor for the disposal of the next sting. In total 10 canister strings, in all 400 canisters, are assumed to be disposed of at between 3 and 5 kilometres depth in one borehole. An analysis of potential accidents during the disposal operations shows that the potentially worst accident would be that a canister string is stuck above the disposal zone of a borehole and cannot be retrieved. In such a case, the borehole may have to be sealed in the best possible way and abandoned. The consequences of this could be that one or more leaking canisters are stuck in a borehole section with mobile groundwater. In the case of a leaking canister being stuck in a borehole section with mobile groundwater, the potential radiological consequences are likely to be dominated by the release of the so-called Instant Release Fraction (IRF) of the radionuclide inventory, i.e. the fraction of the radionuclides that as a consequence of the in-core conditions are present in the annulus between the fuel pellets and the cladding or on the grain boundaries of the UO{sub 2} matrix

  8. An evaluation of the failure of a PWR lower head during a core meltdown accident

    This paper presents an analysis of the failure of lower vessel head during a core meltdown accident. The analysis is limited to PWR systems with no penetration tubes attached to the lower vessel head. The case considered is characterized by a small quantity of corium and a relatively slow discharge into the lower plenum. The assumption of the breakup of the jet stream results in the solidification of debris particles and the formation of a debris bed thermally attacking the lower head wall. Detailed analyses were performed to determine the debris/water interaction, ablation of the lower head wall, and the time of vessel failure. Parameters which have significant effect on the results were identified. Parametric studies were performed to reflect uncertainties associated with the various phenomenological processes occurring during corium relocation into the lower head

  9. Quantitative uncertainty and sensitivity analysis of a PWR control rod ejection accident

    Pasichnyk, I.; Perin, Y.; Velkov, K. [Gesellschaft flier Anlagen- und Reaktorsicherheit - GRS mbH, Boltzmannstasse 14, 85748 Garching bei Muenchen (Germany)

    2013-07-01

    The paper describes the results of the quantitative Uncertainty and Sensitivity (U/S) Analysis of a Rod Ejection Accident (REA) which is simulated by the coupled system code ATHLET-QUABOX/CUBBOX applying the GRS tool for U/S analysis SUSA/XSUSA. For the present study, a UOX/MOX mixed core loading based on a generic PWR is modeled. A control rod ejection is calculated for two reactor states: Hot Zero Power (HZP) and 30% of nominal power. The worst cases for the rod ejection are determined by steady-state neutronic simulations taking into account the maximum reactivity insertion in the system and the power peaking factor. For the U/S analysis 378 uncertain parameters are identified and quantified (thermal-hydraulic initial and boundary conditions, input parameters and variations of the two-group cross sections). Results for uncertainty and sensitivity analysis are presented for safety important global and local parameters. (authors)

  10. Validation and verification of accident consequence assessment models

    Homma, T.; Togawa, O. [Japan Atomic Energy Research Inst., Tokyo (Japan); Takahashi, T. [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst; Arkhipov, A.N. [Chernobyl Science and Technology Centre for International Research (Ukraine)

    2001-03-01

    An accident consequence assessment code, OSCAAR, primarily designed by Japan Atomic Energy Research Institute (JAERI) for use in probabilistic safety assessment (PSA) of nuclear reactors in Japan, was applied to use for siting, emergency planning, and development of design criteria, and in the comparative risk studies of different energy systems. After verifying the code system through the international code comparison organized by CEC and OECD/NEA, the validation and improvements of the individual models and the verification of the whole OSCAAR code system were made. The cooperative research between Chernobyl Science and Technology Center for International Research (CHESCIR) and JAERI provided a valuable opportunity to test the performance of the accident consequence assessment models by comparing the model predictions with data obtained in the Chernobyl accidents. The predictive capabilities of OSCAAR were demonstrated using the accident source term and meteorological data for estimating the early exposure to the public occurred during and shortly after plume passage. The calculations indicated that ground-shine dose and inhalation dose, particularly from large nonvolatile particulates were the main contributors in the early stage of the accident. (S. Ohno)

  11. The Fukushima accident and its consequences. Facts, explanations and comments

    This document proposes an overview of the present situation in the different reactors of the Fukushima power station and discusses its control by the operator. It also describes what went on, the causes of the accident, and what occurred on the accident day (earthquake, tsunami, flooding). It discusses whether some mistakes regarding the design and the protection of reactors could explain the accident. It presents the various measures which have been immediately implemented to protect the populations and to confine the accident. It proposes an assessment of damages for the ground and marine environment in terms of contamination. It addresses the consequences of the released radioactivity on population health and on personnel intervening within the site. It discusses the restoration perspectives for contaminated areas and the possible return of evacuated population. Then, it describes the different phases for the station dismantling. It evokes the issue of fallouts beyond Japan and in Europe, outlines some lessons learned from the accident and new safety measures to be implemented in France. It discusses how nuclear risk management is organised in France and its efficiency. It addresses the consequences for the development of nuclear energy in the world

  12. Reducing the consequences of reactor accidents with a green belt

    Considerable attention is being paid to reducing the consequences of low-probability accidents in nuclear power plants. A scheme based on the pollution absorption properties of trees is proposed to reduce early and continued mortalities among the general public due to an accident in a nuclear power plant. The consequences of a hypothetical case in which a large, cold, ground-level release of radionuclides into the atmosphere takes place have been analyzed in the absence and in the presence of a green belt (rows of trees). The results show that in the presence of a suitably designed green belt around a nuclear power plant, the consequences in terms of early and continued mortality as well as an interdiction area, involving relocation of population and supply of food stuff from an uncontaminated region, can be reduced by orders of magnitude. This could also help in substantially reducing the magnitude of emergency preparedness in the public domain

  13. Application of the WECHSL code to PWR and BWR specific accident scenarios

    The WECHSL Mod3 version is used to perform an accident analysis for a 1300 MW PWR and a BWR. The analysis starts after the melt has penetrated the reactor pressure vessel and is contained in the dry reactor cavity. The initial melt temperature is estimated to be 2673 K. In the initial phase of the melt/concrete interaction, the dominant energy source in the melt is the energy released in the zirconium oxidation reactions with the concrete decomposition products. Hence the concrete composition will determine the Zr-oxidation and the gas release rates as well as the composition of the released gases. Recent experiments and analyses have shown that the solidus temperature of the oxidic melt decreases much more rapidly with addition of concrete oxide than modelled previously. The solidus temperature of the oxide phase drops rapidly as concrete oxides are incorporated into the melt, approaching the concrete solidus at only about 10 to 20 weight percent of concrete oxides. The calculations are performed using the old estimate and the new solidus temperatures for both reactor types in order to study the influence of that oxide solidus temperature. The condensed Zr/SiO2 chemistry is only relevant for the PWR because of the high content of SiO2 in the siliceous concrete basemat. Compared to former analyses for the PWR the much faster zirconium oxidation leads to a higher temperature of about 100 K in the early phase of melt/concrete interaction and therefore the crust formation process starts later than in the former analyses leading to a longer duration of high gas release rates dominated by H2 because of more effective heat transfer to the concrete in this period of time. The concrete basemat of the BWR consists of pure limestone with a decomposition temperature which is higher than the solidus temperature of the metallic melt. This high concrete decomposition temperature prevents a crust formation at the metal-concrete boundary. Hence a very efficient heat transfer leads

  14. Accident consequence calculations for project W-058 safety analysis

    This document describes the calculations performed to determine the accident consequences for the W-058 safety analysis. Project W-058 is the replacement cross site transfer system (RCSTS), which is designed to transort liquid waste between the 200 W and 200 E areas. Calculations for RCSTS safety analyses used the same methods as the calculations for the Tank Waste Remediation System (TWRS) Basis for Interim Operation (BIO) and its supporting calculation notes. Revised analyses were performed for the spray and pool leak accidents since the RCSTS flows and pressures differ from those assumed in the TWRS BIO. Revision 1 of the document incorporates review comments

  15. Modeling in fast dynamics of accidents in the primary circuit of PWR type reactors

    Two kinds of accidents, liable to occur in the primary circuit of a Pressurized Water Reactor and involving fast dynamic phenomena, are analyzed. The Loss Of Coolant Accident (LOCA) is the accident used to define the current PWR. It consists in a large-size break located in a pipe of the primary circuit. A blowdown wave propagates through the circuit. The pressure differences between the different zones of the reactor induce high stresses in the structures of the lower head and may degrade the reactor core. The primary circuit starts emptying from the break opening. Pressure decreases very quickly, involving a large steaming. Two thermal-hydraulic simulations of the blowdown phase of a LOCA are computed with the Europlexus code. The primary circuit is represented by a pipe-model including the hydraulic peculiarities of the circuit. The main differences between both computations concern the kind of reactor, the break location and model, and the initialization of the accidental operation. Steam explosion is a hypothetical severe accident liable to happen after a core melting. The molten part of the core (called corium) falls in the lower part of the reactor. The interaction between the hot corium and the cold water remaining at the bottom of the vessel induces a massive and violent vaporization of water, similar to an explosive phenomenon. A shock wave propagates in the vessel. what can damage seriously the neighbouring structures or drill the vessel. This work presents a synthesis of in-vessel parametrical studies carried out with the Europlexus code, the linkage of the thermal-hydraulic code Mc3d dedicated to the pre-mixing phase with the Europlexus code dealing with the explosion, and finally a benchmark between the Cigalon and Europlexus codes relative to the Vulcano mock-up. (author)

  16. The Influence of Seasonal Characteristics on the Accident Consequences Analysis

    In order to examine the influence of seasonal characteristics on accident consequences, we defined a limited number of basic spectra based on the relative importance of source term release parameters and meteorological conditions on offsite health effects and economic impacts. We then investigated the variation in numbers and frequency of early health effects and economic impacts resulting from the severe accidents of the YGN 3 and 4 nuclear power plants from spectrum to spectrum by using MACCS code. These investigations were for meteorological conditions defined as typical on an annual basis. Also, we investigated the variation in numbers and frequency of early health effects and economic impacts for the same standard spectra for meteorological conditions defined as typical on a seasonal basis recognizing that there are four seasons with distinct meteorological characteristics. Results show that there are large differences in consequences from spectrum to spectrum, although an equal amount and mix of radioactive material is released to the atmosphere in each case. Therefore, release parameters and meteorological data have to be well characterized in order to estimate accident consequences resulting from an accident accurately. Also, there are large differences in the estimated number of health effects and economic impacts from season to season due to distinct seasonal variations in meteorological conditions in Korea. In fall, the early fatalities and early fatality risk show minimum values due to enhanced dispersion arising from increased atmospheric instability, and the early fatalities show maximum value in summer due to a large rainfall rate. On the contrast, the economic cost shows maximum value in fall and minimum in summer due to different atmospheric dispersion and rainfall rate. Therefore, it is necessary to consider seasonal characteristics in developing emergency response strategies for reducing offsite early health risks in the event of a severe

  17. Consequences and experiences - ten years after the Chernobyl accident

    On 26 April 1986. the most serious accident in the history of the nuclear industry occurred at the Chernobyl nuclear power plant in the former Soviet Union, near the present borders of Ukraine, Belarus and Russia.Material released into the atmosphere dispersed and eventually deposited back on the surface of the earth,were it was measurable over the whole northern hemisphere. Millions of people and all segments of life and economy have been affected by the accident. Radioactive contamination has reached several tens of MBq/m2 in the area of 30 km diameter around the reactor in 1986., and plants and animals have been exposed to short lived radionuclides up to external doses of several tens of Gy. In the early phase after the accident, 237 persons were suspected to have acute radiation syndrome as a consequence of the Chernobyl accident, but diagnoses has been confirmed in 134 cases. In that phase 28 person have died as a consequence of exposure. There are significant non - related health disorders and symptoms, such as anxiety, depression and various psychosomatic disorders attributable to mental stress among the population in the region

  18. Estimated consequences from severe spent nuclear fuel transportation accidents

    The RISKIND software package is used to estimate radiological consequences of severe accident scenarios involving the transportation of spent nuclear fuel. Radiological risks are estimated for both a collective population and a maximally exposed individual based on representative truck and rail cask designs described in the U.S. Nuclear Regulatory Commission (NRC) modal study. The estimate of collective population risk considers all possible environmental pathways, including acute and long-term exposures, and is presented in terms of the 50-y committed effective dose equivalent. Radiological risks to a maximally exposed individual from acute exposure are estimated and presented in terms of the first year and 50-y committed effective dose equivalent. Consequences are estimated for accidents occurring in rural and urban population areas. The modeled pathways include inhalation during initial passing of the radioactive cloud, external exposure from a reduction of the cask shielding, long-term external exposure. from ground deposition, and ingestion from contaminated food (rural only). The major pathways and contributing radionuclides are identified, and the effects of possible mitigative actions are discussed. The cask accident responses and the radionuclide release fractions are modeled as described in the NRC modal study. Estimates of severe accident probabilities are presented for both truck and rail modes of transport. The assumptions made in this study tend to be conservative; however, a set of multiplicative factors are identified that can be applied to estimate more realistic conditions

  19. Nuclear installations abroad the accident risks and their potential consequences

    This paper endeavors to assess the threat to Ireland from severe accidents at civil nuclear installations. Among the various types of nuclear installations worldwide, reactors and reprocessing plants are considered to be the most threatening and so the paper focuses on these. The threat is assumed to be a function of the risk of severe accidents at the above types of installations and the probability of unfavourable weather conditions carrying the radioactive releases to Ireland. Although nuclear installations designed in eastern Europe and Asia are less safe than others, the greatest threat to Ireland arises from nearby installations in the UK. The difficulty of measuring the probabilities and consequences of severe nuclear accidents at nuclear installations in general is explained. In the case of the UK installations, this difficulty is overcome to some degree by using values of 'tolerable' risk adopted by the national nuclear regulator to define the radiotoxic releases from nuclear accidents. These are used as input to atmospheric dispersion models in which unfavourable weather conditions for Ireland are assumed and radiation doses are calculated to members of the Irish public. No countermeasures, such as sheltering, are assumed. In the worst cast scenario no deaths would be expected in Ireland in the immediate aftermath of the accident however, an increase in cancers over a period of 25 years or so would be expected assuming present-day models for the effect of low level radiation are valid

  20. Consequences and effectiveness of relocation after nuclear accidents

    Extensive parameter studies have been performed with the program package COSYMA for probabilistic accident consequence assessments to quantify by means of PRA methods the interdependence of those quantities, which influence the extent, the duration, the efficiency and the monetary costs of relocation. As most important quantities, the amount of radionuclides released, the dose intervention levels for relocation, the (avoided) radiation doses in the population and the associated costs have been identified. Decontamination measures have also been included in the investigations, since they reduce the duration of relocation. The expression of all relevant accident consequences in monetary units allowed to investigate the applicability of cost/benefit analysis for deriving the most favourable intervention levels. It could be shown that weighting with different factors of collective doses calculated from different individual dose bands, and thus incorporating subjective judgements, significantly extends and improves the method. (orig./HP)

  1. Assessment of off-site consequences of nuclear accidents (MARIA)

    A brief report is given of a workshop held in Luxembourg in 1985 on methods for assessing the off-site radiological consequences of nuclear accidents (MARIA). The sessions included topics such as atmospheric dispersion; foodchain transfer; urban contamination; demographic and land use data; dosimetry, health effects, economic and countermeasures models; uncertainty analysis; and application of probabilistic risk assessment results as input to decision aids. (U.K.)

  2. Processing Expert Judgements in Accident Consequence Modelling (invited paper)

    In performing uncertainty analysis a distribution on the code input parameters is required. The construction of the distribution on the code input parameters for the joint CEC/USNRC Accident Consequence Code Uncertainty Analysis using Expert Judgement is discussed. An example from the food chain module is used to illustrate the construction. Different mathematical techniques have been developed to transform the expert judgements into the required format. Finally, the effect of taking account of correlations in performing uncertainty analysis is investigated. (author)

  3. The investigation of Passive Accident Mitigation Scheme for advanced PWR NPP

    Highlights: • We put forward a new PAMS and analyze its operation characteristics under SBO. • We conduct comparative analysis between PAMS and Traditional Secondary Side PHRS. • The PAMS could cope with SBO accident and maintain the plant in safe conditions. • PAMS could decrease heat removal capacity of PHRS. • PAMS has advantage in reducing cooling rate and PCCT temperature rising amplitude. - Abstract: To enhance inherent safety features of nuclear power plant, the advanced pressurized water reactors implement a series of passive safety systems. This paper puts forward and designs a new Passive Accident Mitigation Scheme (PAMS) to remove residual heat, which consists of two parts: the first part is Passive Auxiliary Feedwater System (PAFS), and the other part is Passive Heat Removal System (PHRS). This paper takes the Westinghouse-designed Advanced Passive PWR (AP1000) as research object and analyzes the operation characteristics of PAMS to cope with the Station Blackout Accident (SBO) by using RELAP5 code. Moreover, the comparative analysis is also conducted between PAMS and Traditional Secondary Circuit PHRS to derive the advantages of PAMS. The results show that the designed scheme can remove core residual heat significantly and maintain the plant in safe conditions; the first part of PAMS would stop after 120 min and the second part has to come into use simultaneously; the low pressurizer (PZR) pressure signal would be generated 109 min later caused by coolant volume shrinkage, which would actuate the Passive Safety Injection System (PSIS) to recovery the water level of pressurizer; the flow instability phenomenon would occur and last 21 min after the PHRS start-up; according to the comparative analysis, the coolant average temperature gradient and the Passive Condensate Cooling Tank (PCCT) water temperature rising amplitude of PAMS are lower than those of Traditional Secondary Circuit PHRS

  4. Control room dose analysis for Maanshan PWR plant during design basis loss of coolant accident

    To address the issue identified in USNRC's Generic Letter 2003-1 that the unfiltered air in-leakage rate through plant's control room during design basis accident may exceed that assumed in the licensing analysis and thus threat the control room habitability, the control room radiation dose analysis of Maanshan PWR plant has to be re-performed to determine the allowable unfiltered air in-leakage rate. The allowable unfiltered air in-leakage rate is to be determined in such a way that the calculated whole body dose in the control room during the most limiting design basis accident must meet the criteria set forth in 10 CFR 50 Appendix A General Design Criteria (GDC) 19. The determined allowable air in-leakage rate is then employed as an acceptable limit to be met by the control room in-leakage test. In this study, the Maanshan plant control room dose analysis model during loss of coolant accident (LOCA) has been established based on USNRC's RADTRAD computer code. Different release and transport paths have been incorporated in this model, including containment leakage, engineered safety feature (ESF) leakage, and control room filtered and un-filtered air in-leakage. The RADTRAD calculation results are compared with Final Safety Analysis Report (FSAR) results to assure that overall consistency is reached. Finally, considering the uncertainties and margin to be maintained between RADTRAD calculation results and GDC-19 dose limits, an allowable unfiltered air in-leakage rate for control room habitability application during LOCA has been well defined. (author)

  5. Analyses of conditions in a large, dry PWR containment during an TMLB' accident sequence

    The aim of the paper is to give an assessment of the conditions which would develop in the large, dry containment of a modern Westinghouse-type PWR during a severe accident where all safety systems are unavailable. The analysis is based principally on the results of calculations using the CONTAIN code, with a 4 cell model of the containment, for a station blackout (TMLB') scenario in which the vessel is assumed to fail at high pressure. In particular, the following are noted: (i) If much of the debris is in contact with water, so that decay heat can boil water directly, then the pressure rises steadily to reach the assumed containment failure point after 11/2 to 2 days. If most of the debris becomes isolated from water, for example, because of water is held up on the containment floors and in sumps and drains, the pressure rises too slowly to threaten the containment on this timescale. (ii) If a core-concrete interaction occurs, most of the associated fission product release takes place soon after relocation of molten fuel to the containment. The aerosols which transport these (and other non-gaseous fission products released earlier in the accident) in the containment agglomerate and settle. As a result, 0.1% or less of the aerosols remain airborne a day after the start of the accident. (iii) Hydrogen and carbon monoxide, which would accumulate in the containment are not expected to burn because the atmosphere would be inerted by steam. If, however, enough of the steam is condensed, for example, by recovering the containment sprays, a burn could occur but the resulting pressure spike is unlikely to threaten the containment unless a transition to detonation occurs. 6 refs., 6 tabs., 12 figs

  6. Thermal-hydraulic behavior of a PWR under accident conditions complementary test results from UPTF and PKL

    Two complementary test facilities - the Upper Plenum Test Facility (UPTF) and the Primaerkreislauf test facility (PKL) - were constructed to investigate the thermal-hydraulic response of a pressurized water reactor (PWR) during postulated accidents. The UPTF is a geometrical full-scale simulation of the primary system of a 1300-MW PWR. The upper plenum, the downcomer and the four connected loops as well as the pressurizer are represented on a 1:1 scale. The integral test facility PKL also simulates a 1300-MW PWR, whereby the power and volume is reduced by a factor of 1:145 (elevations 1:1). The PKL test facility models the entire primary system, relevant parts of the secondary side and all important engineered safety and auxiliary systems. Whereas the UPTF was mainly designed to perform separate-effect tests focusing on multidimensional thermal-hydraulic phenomena in full-scale simulated components, the main objective of the PKL tests has been the investigation of the thermal-hydraulic system behavior on the primary and secondary side. So far the program objectives represent a reasonable completion and in summary the experimental results from both test facilities provide an essential contribution for a better understanding of assumed accident sequences in a PWR. Test results which demonstrate the complementary character of the UPTF and the PKL test programs as well as the interaction between the two test facilities are presented in this paper. (author)

  7. Illustration interface of accident progression in PWR by quick inference based on multilevel flow models

    In this paper, a new accident inference method is proposed by using a goal and function oriented modeling method called Multilevel Flow Model focusing on explaining the causal-consequence relations and the objective of automatic action in the accident of nuclear power plant. Users can easily grasp how the various plant parameters will behave and how the various safety facilities will be activated sequentially to cope with the accident until the nuclear power plants are settled into safety state, i.e., shutdown state. The applicability of the developed method was validated by the conduction of internet-based 'view' experiment to the voluntary respondents, and in the future, further elaboration of interface design and the further introduction of instruction contents will be developed to make it become the usable CAI system. (authors)

  8. Assessment of fission product release from the reactor containment building during severe core damage accidents in a PWR

    Fission product releases from the RCB associated with hypothetical core-melt accidents ABβ, S2CDβ and TLBβ in a PWR-900 MWe have been performed using French computer codes (in particular, the JERICHO Code for containment response analysis and AEROSOLS/B1 for aerosol behavior in the containment) related to thermalhydraulics and fission product behavior in the primary system and in the reactor containment building

  9. Health consequences of the Chernobyl accident: a review

    Full text of publication follows: on April 26, 1996, the accident at Chernobyl nuclear power plant led to the release into the atmosphere of considerable quantities of radionuclides. Most contaminated regions were in the southern Belarus, northern Ukraine and Bryansk and Kaluga regions of Russia. Main population groups exposed to the radioactivity released during the accident were the personnel at the Chernobyl plant and the rescue teams present on-site during the first hours, the cleanup workers (numbering about 600000) who participated in the decontamination and cleaning operations in the 30 km zone around the site, the residents of the same zone who were evacuated (numbering about 115000) and the inhabitants of contaminated zones (≥1 Ci/km2). Dose and dose rate levels as well as exposure pathways differ from one population group to another. A review of scientific articles published in the international literature till 1998 has been carried out. Apart the 28 deaths due to acute radiation sickness which occurred in the personnel of the plant and rescue teams within several days or weeks after the accident, two main public health consequences of the Chernobyl accident have been observed. First an unprecedented epidemic of thyroid cancers was detected in children first in 1992 in Belarus then in the Ukraine and to a lesser extent in Bryansk region. The spontaneous incidence of these tumours was multiplied by 100 in most contaminated regions. Although the role of the accident in this epidemic is now recognised, questions are raised regarding the respective role of radioactive agents and other environmental or genetic factors, and its evolution in the future. Regarding other kinds of solid cancers and leukemia, no excess has been clearly demonstrated in the residents of contaminated areas nor in liquidators. Second, results of available epidemiological investigations show an increased risk of psychological distress in residents of highly contaminated areas

  10. Tank Bump Accident Potential and Consequences During Waste Retrieval

    BRATZEL, D.R.

    2000-09-27

    This report provides an evaluation of Hanford tank bump accident potential and consequences during waste retrieval operations. The purpose of this report is to consider the best available new information to support recommendations for safety controls. A new tank bump accident analysis for safe storage (Epstein et al. 2000) is extended for this purpose. A tank bump is a postulated event in which gases, consisting mostly of water vapor, are suddenly emitted from the waste and cause tank headspace pressurization. Tank bump scenarios, physical models, and frequency and consequence methods are fully described in Epstein et al. (2000). The analysis scope is waste retrieval from double-shell tanks (DSTs) including operation of equipment such as mixer pumps and air lift circulators. The analysis considers physical mechanisms for tank bump to formulate criteria for bump potential during retrieval, application of the criteria to the DSTs, evaluation of bump frequency, and consequence analysis of a bump. The result of the consequence analysis is the mass of waste released from tanks; radiological dose is calculated using standard methods (Cowley et al. 2000).

  11. Analysis of the core reflooding of a PWR reactor under a loss-of-coolant postulated accident

    The main purpose of this work is to analyse the termohydraulic behaviour of emergency cooling water, during reflooding of a PWR core submitted to a postulated loss-of-coolant accident, with the scope of giving the boundary conditions needed to verify fuel element and containment integrity. The analytical model presented was applied to the simulation of Angra I core reflooding phase, after a double-ended break between pressure vessel and discharge of one of the main coolant pumps. For this accident, with a discharge coefficient of C sub(D) = 0.4, the highest peak cladding temperature is expected. (author)

  12. Offsite radiological consequence analysis for the bounding flammable gas accident

    The purpose of this analysis is to calculate the offsite radiological consequence of the bounding flammable gas accident. DOE-STD-3009-94, ''Preparation Guide for U.S. Department of Energy Nonreactor Nuclear Facility Documented Safety Analyses'', requires the formal quantification of a limited subset of accidents representing a complete set of bounding conditions. The results of these analyses are then evaluated to determine if they challenge the DOE-STD-3009-94, Appendix A, ''Evaluation Guideline,'' of 25 rem total effective dose equivalent in order to identify and evaluate safety class structures, systems, and components. The bounding flammable gas accident is a detonation in a single-shell tank (SST). A detonation versus a deflagration was selected for analysis because the faster flame speed of a detonation can potentially result in a larger release of respirable material. As will be shown, the consequences of a detonation in either an SST or a double-shell tank (DST) are approximately equal. A detonation in an SST was selected as the bounding condition because the estimated respirable release masses are the same and because the doses per unit quantity of waste inhaled are generally greater for SSTs than for DSTs. Appendix A contains a DST analysis for comparison purposes

  13. Evaluation of nuclear accidents consequences. Risk assessment methodologies, current status and applications

    General description of the structure and process of the probabilistic methods of assessment the external consequences in the event of nuclear accidents is presented. attention is paid in the interface with Probabilistic Safety Analysis level 3 results (source term evaluation) Also are described key issues in accident consequence evaluation as: effects evaluated (early and late health effects and economic effects due to countermeasures), presentation of accident consequences results, computer codes. Briefly are presented some relevant areas for the applications of Accident Consequence Evaluation

  14. A rapid dose assessment and display system applicable to PWR accident

    The necessity of developing a rapid dose assessment system has been emphasized for an effective emergency response of mitigation of off-site radiological consequences. A microcomputer program based on a rapid dose assessment model of the off-site radiological consequences is developed for various accident sinarios for the Nuclear Power Plants in Korea. This model, which is consists of the user answering-question input format as a menu driven method and the output format of table and graphic types, is helpful to decision-making on Emergency Preparedness by being more rapidly able to implement the off-site dose assessment and to interpret the result. (Author)

  15. Reports of the Chernobyl accident consequences in Brazilian newspapers

    The public perception of the risks associated with nuclear power plants was profoundly influenced by the accidents at Three Mile Island and Chernobyl Power Plants which also served to exacerbate in the last decades the growing mistrust on the 'nuclear industry'. Part of the mistrust had its origin in the arrogance of nuclear spokesmen and in the secretiveness of nuclear programs. However, press agencies have an important role in shaping and upsizing the public awareness against nuclear energy. In this paper we present the results of a survey in reports of some Brazilian popular newspapers on Chernobyl consequences, as measured by the total death toll of the accident, to show the up and down dance of large numbers without any serious judgment. (author)

  16. Assessment methods and minimization of radiological consequences of nuclear accidents

    The uncertainty and sensitivity analyses with the program system COSYMA for assessing the radiological consequences of nuclear accidents, performed since 1997 in close co-operation with the University of Delft, NL, and the NRPB, UK, have been terminated and fully documented. Work on the real-time on-line decision support system RODOS for off-site emergency management after nuclear accidents has concentrated on the preparation of the operational version PV 4.0; it will be released by mid 2000. It has been developed and customised to the various regions of Europe in close co-operation with some 40 contract partners in East and West Europe. The operational use of the RODOS system at a central place in Germany and in emergency centres of other West and East European countries is in progress. (orig.)

  17. Chernobyl victims: realistic evaluation of medical consequences of Chernobyl accident

    Objective assessment of early and delayed medical consequence of the Chernobyl accident is presented. Mortality of people due to acute radiation disease, burns and mechanical injuries are attributed to the early effects. Oncological and genetic diseases are considered as the delayed effects. Delayed radiation effects on the residents of contaminated territories were estimated by epidemiologic examination taking into account the dose due to radioactive fallout. Certain regions of Belarus, Russia and Ukraine were mostly exposed to contamination. Contamination density by 137Cs is considered and radiation doses due to natural sources and Chernobyl accident are compared. Disease incidence is analysed for carcinoma and genetic diseases. Health hazard caused by non-radiation accidental factors (psychological stress, victim psychology thrusting, groundless evacuation) is assessed

  18. Radiological consequences of the Three Mile Island accident

    The radiological consequences of the Three Mile Island (TMI) nuclear accident are discussed in detail. The nature, quantity and timing of the radioactive materials released to the atmosphere are established; mainly radioactive noble gases were emitted. A description is given of the radiological monitoring that occurred and the measured levels both inside and outside the plant are given as a function of time from the accident. In particular, the radioiodine release and its subsequent detection in milk analysis is described. The methods of establishing the population dosage are discussed; it is concluded that the collective dose equivalent is in the range 1600-3300 person rems. This implies a projected cancer (fatal and non-fatal) incidence of less than 1.5 in the offsite population within the 50 miles of the TMI site; the expected occurrence in this population is 541,000 cancers. The exposure of workers to radiation levels within the plant is also reported. (U.K.)

  19. Environmental radiological consequences of a loss of coolant accident

    The elaboration of a calculation model to determine safety areas, named Exclusion Zone and Low Population Zone for nuclear power plants, is dealt with. These areas are determined from a radioactive doses calculation for the population living around the NPP after occurence of a postulated ' Maximum Credible Accident' (MCA). The MCA is defined as an accident with complete loss of primary coolant and consequent fusion of a substantial portion of the reactor core. In the calculations carried out, data from NPP Angra I were used and the assumptions made were conservative, to be compatible with licensing requirements. Under the most pessimistic assumption (no filters) the values of 410m and 1000m were obtained for the Exclusion Zone and Low Population Zone radii, respectivily. (Author)

  20. Application of Westinghouse NEXUS/ANC9 cross-section model for PWR accident analyses

    NEXUS/ANC9 is the latest licensed PWR core design code system developed by Westinghouse. This system has demonstrated capabilities of modeling advanced core designs with improved accuracy in core reactivity and power distribution predictions. NEXUS/ANC9 system is being rolled out to replace the current APA system (ALPHA/PHOENIX-P/ANC) for routine core calculations. In addition to the standard core design calculations, investigations are underway to explore the possibility to expand the NEXUS/ANC9 application for safety analysis, especially at accident conditions. The main focus of the investigation is the evaluation of the NEXUS/ANC9 cross-section representation model conditions like high void and significant change of core pressure. Comparisons of the predicted parameters among ANC9, PARAGON lattice code and MCNP calculations are presented. The results show that NEXUS/ANC9 is able to model the cross-section behavior and accurately reproduce lattice code results at all simulated conditions. (author)

  1. The accident consequence model of the German safety study

    The accident consequence model essentially describes a) the diffusion in the atmosphere and deposition on the soil of radioactive material released from the reactor into the atmosphere; b) the irradiation exposure and health consequences of persons affected. It is used to calculate c) the number of persons suffering from acute or late damage, taking into account possible counteractions such as relocation or evacuation, and d) the total risk to the population from the various types of accident. The model, the underlying parameters and assumptions are described. The bone marrow dose distribution is shown for the case of late overpressure containment failure, which is discussed in the paper of Heuser/Kotthoff, combined with four typical weather conditions. The probability distribution functions for acute mortality, late incidence of cancer and genetic damage are evaluated, assuming a characteristic population distribution. The aim of these calculations is first the presentation of some results of the consequence model as an example, in second the identification of problems, which need possibly in a second phase of study to be evaluated in more detail. (orig.)

  2. Thyroid Consequences of the Fukushima Nuclear Reactor Accident

    Nagataki, Shigenobu

    2012-01-01

    Background A special report, ‘The Fukushima Accident’, was delivered at the 35th Annual Meeting of the European Thyroid Association in Krakow on September 11, 2011, and this study is the follow-up of the special report. Objectives To present a preliminary review of potential thyroid consequences of the 2011 Fukushima nuclear reactor accident. Methods Numerous new data have been presented in Japanese, and most of them are available on the website from each research institute and/or from each m...

  3. Primary disability of the Chernobyl Accident consequences liquidators

    The structure of courses of the primary invalidism of the Chernobyl accident consequences liquidators is studies. The main reasons of the loss of a capacity for work are blood circulation diseases (41.9%), neoplasms (19.9%), diseases of the nervous system and sense organs (9.7%), mental disorders (5.9%) and endocrine diseases (5.5%). The invalids distribution in the different regions and in different age groups according to the disease forms is analysed. The average durations of the diseases resulting in the primary invalidism are about 2.8 years. In average the illnesses began in the 3.1 years. 6 refs

  4. PERSPECTIVES ON A DOE CONSEQUENCE INPUTS FOR ACCIDENT ANALYSIS APPLICATIONS

    (NOEMAIL), K; Jonathan Lowrie, J; David Thoman (NOEMAIL), D; Austin Keller (NOEMAIL), A

    2008-07-30

    Department of Energy (DOE) accident analysis for establishing the required control sets for nuclear facility safety applies a series of simplifying, reasonably conservative assumptions regarding inputs and methodologies for quantifying dose consequences. Most of the analytical practices are conservative, have a technical basis, and are based on regulatory precedent. However, others are judgmental and based on older understanding of phenomenology. The latter type of practices can be found in modeling hypothetical releases into the atmosphere and the subsequent exposure. Often the judgments applied are not based on current technical understanding but on work that has been superseded. The objective of this paper is to review the technical basis for the major inputs and assumptions in the quantification of consequence estimates supporting DOE accident analysis, and to identify those that could be reassessed in light of current understanding of atmospheric dispersion and radiological exposure. Inputs and assumptions of interest include: Meteorological data basis; Breathing rate; and Inhalation dose conversion factor. A simple dose calculation is provided to show the relative difference achieved by improving the technical bases.

  5. Health effects models for nuclear power plant accident consequence analysis

    The Nuclear Regulatory Commission (NRC) has sponsored several studies to identify and quantify, through the use of models, the potential health effects of accidental releases of radionuclides from nuclear power plants. The Reactor Safety Study provided the basis for most of the earlier estimates related to these health effects. Subsequent efforts by NRC-supported groups resulted in improved health effects models that were published in the report entitled open-quotes Health Effects Models for Nuclear Power Plant Consequence Analysisclose quotes, NUREG/CR-4214, 1985 and revised further in the 1989 report NUREG/CR-4214, Rev. 1, Part 2. The health effects models presented in the 1989 NUREG/CR-4214 report were developed for exposure to low-linear energy transfer (LET) (beta and gamma) radiation based on the best scientific information available at that time. Since the 1989 report was published, two addenda to that report have been prepared to (1) incorporate other scientific information related to low-LET health effects models and (2) extend the models to consider the possible health consequences of the addition of alpha-emitting radionuclides to the exposure source term. The first addendum report, entitled open-quotes Health Effects Models for Nuclear Power Plant Accident Consequence Analysis, Modifications of Models Resulting from Recent Reports on Health Effects of Ionizing Radiation, Low LET Radiation, Part 2: Scientific Bases for Health Effects Models,close quotes was published in 1991 as NUREG/CR-4214, Rev. 1, Part 2, Addendum 1. This second addendum addresses the possibility that some fraction of the accident source term from an operating nuclear power plant comprises alpha-emitting radionuclides. Consideration of chronic high-LET exposure from alpha radiation as well as acute and chronic exposure to low-LET beta and gamma radiations is a reasonable extension of the health effects model

  6. Impact of improved neutronic methodology on the cladding response during a PWR reactivity initiated accident

    Hursin, Mathieu, E-mail: mathieu.hursin@psi.ch [Department of Nuclear Engineering of University of California at Berkeley, 4101 Etcheverry Hall, Berkeley, CA (United States); Downar, Thomas J., E-mail: downar@umich.edu [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI (United States); Montgomery, Robert, E-mail: Robert.Montgomery@pnnl.gov [Anatech Corp, San Diego, CA (United States)

    2013-09-15

    Highlights: • DeCART provides radial, azimuth, and axial power distribution during RIA analysis. • Coupling to FALCON is developed to evaluate the impact of such information. • Burnup calculation in the “two step” approach causes cladding load discrepancies. • The effect of azimuthal power variation has a 10% impact on the cladding load. -- Abstract: When applied to reactivity initiated accidents (RIAs) analysis, codes such as DeCART can provide a detailed radial, azimuth, and axial power distribution within a fuel rod. The work reported here is aimed at quantifying the sensitivity of the cladding thermo-mechanical response, calculated by the fuel performance code FALCON to the more accurate and detailed neutronic solution provided by DeCART for full PWR core RIA analysis. As a basis of comparison, the neutronics analysis is also performed with the U.S. NRC PARCS code, which is representative of the methodology used by the industry. Based on the DeCART solutions, several fuel rods are chosen for analysis with FALCON according to several relevant criteria. For each of the selected fuel rods, a FALCON study is performed using the boundary conditions provided by the neutronic solvers to predict the cladding response in terms of Strain Energy Density (SED) to the power pulse during the transient. The results of the analysis led to the following conclusions: • The largest impact on the cladding response can be attributed to the differences in the kinetic parameters in PARCS and DeCART. • The modeling of fuel pin exposure in the current industry standard “two step” methodology can result in some significant discrepancies in terms of SED during RIA analysis. • The effect of azimuthal power variation within a given fuel rod has a 10% impact on the SED and should be taken into consideration during RIA analysis, especially for high exposure fuel.

  7. Impact of improved neutronic methodology on the cladding response during a PWR reactivity initiated accident

    Highlights: • DeCART provides radial, azimuth, and axial power distribution during RIA analysis. • Coupling to FALCON is developed to evaluate the impact of such information. • Burnup calculation in the “two step” approach causes cladding load discrepancies. • The effect of azimuthal power variation has a 10% impact on the cladding load. -- Abstract: When applied to reactivity initiated accidents (RIAs) analysis, codes such as DeCART can provide a detailed radial, azimuth, and axial power distribution within a fuel rod. The work reported here is aimed at quantifying the sensitivity of the cladding thermo-mechanical response, calculated by the fuel performance code FALCON to the more accurate and detailed neutronic solution provided by DeCART for full PWR core RIA analysis. As a basis of comparison, the neutronics analysis is also performed with the U.S. NRC PARCS code, which is representative of the methodology used by the industry. Based on the DeCART solutions, several fuel rods are chosen for analysis with FALCON according to several relevant criteria. For each of the selected fuel rods, a FALCON study is performed using the boundary conditions provided by the neutronic solvers to predict the cladding response in terms of Strain Energy Density (SED) to the power pulse during the transient. The results of the analysis led to the following conclusions: • The largest impact on the cladding response can be attributed to the differences in the kinetic parameters in PARCS and DeCART. • The modeling of fuel pin exposure in the current industry standard “two step” methodology can result in some significant discrepancies in terms of SED during RIA analysis. • The effect of azimuthal power variation within a given fuel rod has a 10% impact on the SED and should be taken into consideration during RIA analysis, especially for high exposure fuel

  8. Evaluation of the structural integrity of the CPR1000 PWR containment under steam explosion accidents

    Highlights: • Detailed three dimensional finite element model with a full consideration of the complex structures, the complex materials and the complex loadings. • Damage to the concrete structure was calculated. • Influence of the thermal loading on the concrete barrel was evaluated. - Abstract: Detailed three-dimensional finite element models were set up to study the dynamic response and the possible damage of the CPR1000 PWR containment under steam explosion accidents with a full consideration of the complex geometric structures, the complex mechanical behavior of materials and the complex blast loadings. The structural integrity of the containment and the internal structures was evaluated under five typical steam explosion scenarios. In addition, the influence of the thermal loading was investigated by setting up a thermal-mechanical coupling finite element model. It is found that under steam explosions, only a small portion of energy is transferred to the concrete containment and therefore, the influence of the explosions on the containment is insignificant. Although the internal facilities and the structures are damaged severely by the blast loadings, the damage to the containment is negligible and the structural integrity is ensured. The thermal loading has a noticeable influence on the loading-capability of the containment structure. It is shown even a pure thermal load, i.e., a 150 °C temperature variation across the containment wall, can cause some damage to the concrete containment. The damage is further deepened by a simultaneous blast loading due to a steam explosion. However, the maximum depth of the damage is small compared with the thickness of the wall and the integrity of the concrete containment is still ensured

  9. Analysis of the loss of pool cooling accident in a PWR spent fuel pool with MAAP5

    Highlights: • A PWR spent fuel pool was modeled by using MAAP5. • Loss of pool cooling severe accident scenarios were studied. • Loss of pool cooling accidents with two mitigation measures were analyzed. - Abstract: The Fukushima Daiichi nuclear accident shows that it is necessary to study potential severe accidents and corresponding mitigation measures for the spent fuel pool (SFP) of a nuclear power plant (NPP). This paper presents the analysis of loss of pool cooling accident scenarios and the discussion of mitigation measures for the SFP at a pressurized water reactor (PWR) NPP with the MAAP5 code. Analysis of uncompensated loss of water due to the loss of pool cooling with different initial pool water levels of 12.2 m (designated as a reference case) and 10.7 m have been performed based on a MAAP5 input model. Scenarios of the accident such as overheating of uncovered fuel assemblies, oxidation of claddings and hydrogen generation, loss of intactness of fuel rod claddings, and release of radioactive fission products were predicted with the assumption that mitigation measures were unavailable. The results covered a broad spectrum of severe accident evaluations in the SFP. Furthermore, as important mitigation measures, the effects of recovering the SFP cooling system and makeup water in SFP on the accident progressions have also been investigated respectively based on the events of pool water boiling and spent fuels uncovery. Based upon the reference case, three cases with the recovery of SFP cooling system and three other cases with makeup water in SFP have been studied. The results showed that, severe accident might happen if SFP cooling system was not restored timely before the spent fuels started to become uncovered; spent fuels could be completely submerged and severe accident might be avoided if SFP makeup water system provided water with a mass flow rate larger than the average evaporation rate defined as the division of pool water mass above the

  10. Health effects models for nuclear power plant accident consequence analysis

    This report is a revision of NUREG/CR-4214, Rev. 1, Part 1 (1990), Health Effects Models for Nuclear Power Plant Accident Consequence Analysis. This revision has been made to incorporate changes to the Health Effects Models recommended in two addenda to the NUREG/CR-4214, Rev. 1, Part 11, 1989 report. The first of these addenda provided recommended changes to the health effects models for low-LET radiations based on recent reports from UNSCEAR, ICRP and NAS/NRC (BEIR V). The second addendum presented changes needed to incorporate alpha-emitting radionuclides into the accident exposure source term. As in the earlier version of this report, models are provided for early and continuing effects, cancers and thyroid nodules, and genetic effects. Weibull dose-response functions are recommended for evaluating the risks of early and continuing health effects. Three potentially lethal early effects -- the hematopoietic, pulmonary, and gastrointestinal syndromes are considered. Linear and linear-quadratic models are recommended for estimating the risks of seven types of cancer in adults - leukemia, bone, lung, breast, gastrointestinal, thyroid, and ''other''. For most cancers, both incidence and mortality are addressed. Five classes of genetic diseases -- dominant, x-linked, aneuploidy, unbalanced translocations, and multifactorial diseases are also considered. Data are provided that should enable analysts to consider the timing and severity of each type of health risk

  11. Consequences of the nuclear power plant accident at Chernobyl

    The Chernobyl Nuclear Power Plant accident, in the Ukrainian Soviet Socialist Republic (SSR), on April 26, 1986, was the first major nuclear power plant accident that resulted in a large-scale fire and subsequent explosions, immediate and delayed deaths of plant operators and emergency service workers, and the radioactive contamination of a significant land area. The release of radioactive material, over a 10-day period, resulted in millions of Soviets, and other Europeans, being exposed to measurable levels of radioactive fallout. Because of the effects of wind and rain, the radioactive nuclide fallout distribution patterns are not well defined, though they appear to be focused in three contiguous Soviet Republics: the Ukrainian SSR, the Byelorussian SSR, and the Russian Soviet Federated Socialist Republic. Further, because of the many radioactive nuclides (krypton, xenon, cesium, iodine, strontium, plutonium) released by the prolonged fires at Chernobyl, the long-term medical, psychological, social, and economic effects will require careful and prolonged study. Specifically, studies on the medical (leukemia, cancers, thyroid disease) and psychological (reactive depressions, post-traumatic stress disorders, family disorganization) consequences of continued low dose radiation exposure in the affected villages and towns need to be conducted so that a coherent, comprehensive, community-oriented plan may evolve that will not cause those already affected any additional harm and confusion

  12. Consequences of the nuclear power plant accident at Chernobyl

    Ginzburg, H.M.; Reis, E. (Health Resources and Services Administration, Rockville, MD (USA))

    1991-01-01

    The Chernobyl Nuclear Power Plant accident, in the Ukrainian Soviet Socialist Republic (SSR), on April 26, 1986, was the first major nuclear power plant accident that resulted in a large-scale fire and subsequent explosions, immediate and delayed deaths of plant operators and emergency service workers, and the radioactive contamination of a significant land area. The release of radioactive material, over a 10-day period, resulted in millions of Soviets, and other Europeans, being exposed to measurable levels of radioactive fallout. Because of the effects of wind and rain, the radioactive nuclide fallout distribution patterns are not well defined, though they appear to be focused in three contiguous Soviet Republics: the Ukrainian SSR, the Byelorussian SSR, and the Russian Soviet Federated Socialist Republic. Further, because of the many radioactive nuclides (krypton, xenon, cesium, iodine, strontium, plutonium) released by the prolonged fires at Chernobyl, the long-term medical, psychological, social, and economic effects will require careful and prolonged study. Specifically, studies on the medical (leukemia, cancers, thyroid disease) and psychological (reactive depressions, post-traumatic stress disorders, family disorganization) consequences of continued low dose radiation exposure in the affected villages and towns need to be conducted so that a coherent, comprehensive, community-oriented plan may evolve that will not cause those already affected any additional harm and confusion.

  13. Mitigation of Severe Accident Consequences Using Inherent Safety Principles

    The safety challenges associated with sodium-cooled fast reactors have been recognized since the beginning of nuclear power and include the high power density in the core, the need for a reactor coolant and heat transfer system with high heat removal capability, the variation of power across the core requiring the use of ducted assemblies, and the condition that the fuel is not in the most neutronically reactive configuration during normal operation such that relocation can result in positive reactivity excursions, even possibly exceeding prompt critical conditions and energetic events. The potential for accidents with such severe consequences has been a negative factor with respect to the use of the sodium-cooled fast reactor. With the development of inherent safety principles, including favorable reactivity feedback, natural circulation cooling, and design choices resulting in favorable dispersive characteristics for failed fuel, it is possible to greatly increase the level of safety, to the point where it is highly unlikely, or perhaps even not possible, for accidents to result in releases of hghly radioactive materials to the containment or the surrounding environment. (author)

  14. Accident consequence calculations for project W-058 safety analysis

    Accident consequence analyses have been performed for Project W-058, the Replacement Cross Site Transfer System. using the assumption and analysis techniques developed for the Tank Remediation Waste system Basis for Interim Operation. most potential accident involving the FISTS are bounded by the TWRS BIO analysis. However, the spray leak and pool leak scenarios require revised analyses since the RCSTS design utilizes larger diameter pipe and higher pressures than those analyzed in the TWRS BIO. Also the volume of diversion box and vent station are larger than that assumed for the valve pits in the TWRS BIO, which effects results of sprays or spills into the pits. the revised analysis for the spray leak is presented in Section 2, for the above ground spill in Section 3, for the presented in Section 2, for the above ground spill in Section 3, for the subsurface spill forming a pool in Section 4, and for the subsurface pool remaining subsurface in Section 5. The conclusion from these sections are summarized below

  15. Offsite radiological consequence analysis for the bounding aircraft crash accident

    The purpose of this calculation note is to quantitatively analyze a bounding aircraft crash accident for comparison to the DOE-STD-3009-94, ''Preparation Guide for U.S. Department of Energy Nonreactor Nuclear Facility Documented Safety Analyses'', Appendix A, Evaluation Guideline of 25 rem. The potential of aircraft impacting a facility was evaluated using the approach given in DOE-STD-3014-96, ''Accident Analysis for Aircraft Crash into Hazardous Facilities''. The following aircraft crash FR-equencies were determined for the Tank Farms in RPP-11736, ''Assessment Of Aircraft Crash FR-equency For The Hanford Site 200 Area Tank Farms'': (1) The total aircraft crash FR-equency is ''extremely unlikely.'' (2) The general aviation crash FR-equency is ''extremely unlikely.'' (3) The helicopter crash FR-equency is ''beyond extremely unlikely.'' (4) For the Hanford Site 200 Areas, other aircraft type, commercial or military, each above ground facility, and any other type of underground facility is ''beyond extremely unlikely.'' As the potential of aircraft crash into the 200 Area tank farms is more FR-equent than ''beyond extremely unlikely,'' consequence analysis of the aircraft crash is required

  16. Health effects estimation code development for accident consequence analysis

    As part of a computer code system for nuclear reactor accident consequence analysis, two computer codes have been developed for estimating health effects expected to occur following an accident. Health effects models used in the codes are based on the models of NUREG/CR-4214 and are revised for the Japanese population on the basis of the data from the reassessment of the radiation dosimetry and information derived from epidemiological studies on atomic bomb survivors of Hiroshima and Nagasaki. The health effects models include early and continuing effects, late somatic effects and genetic effects. The values of some model parameters are revised for early mortality. The models are modified for predicting late somatic effects such as leukemia and various kinds of cancers. The models for genetic effects are the same as those of NUREG. In order to test the performance of one of these codes, it is applied to the U.S. and Japanese populations. This paper provides descriptions of health effects models used in the two codes and gives comparisons of the mortality risks from each type of cancer for the two populations. (author)

  17. Towards more realistic assessment of reactor accident consequences

    The purpose of the Nordic project described in the report has been to improve the data base used in accident consequence assessments, and also to improve the assessment models in use in the Nordic countries. The following data related questions have been dealt with: Terrestrial transfer factors, the freshwater pathways, comparison of dynamic and static calculation models for fish, and the shielding effect of buildings. The work on terrestrial transfer factors has resulted in the generation of a Nordic fallout data bank. The following experimental investigations have been performed: Natural decontamination of roofs under summer and winter conditions, deposition in urban areas, and the filter effect of buildings. Various aspects of mitigating actions have also been examined

  18. Accident consequence assessments with different atmospheric dispersion models

    An essential aim of the improvements of the new program system UFOMOD for Accident Consequence Assessments (ACAs) was to substitute the straight-line Gaussian plume model conventionally used in ACA models by more realistic atmospheric dispersion models. To identify improved models which can be applied in ACA codes and to quantify the implications of different dispersion models on the results of an ACA, probabilistic comparative calculations with different atmospheric dispersion models have been performed. The study showed that there are trajectory models available which can be applied in ACAs and that they provide more realistic results of ACAs than straight-line Gaussian models. This led to a completely novel concept of atmospheric dispersion modelling in which two different distance ranges of validity are distinguished: the near range of some ten kilometres distance and the adjacent far range which are assigned to respective trajectory models. (orig.)

  19. The influence of simultaneous or sequential test conditions in the properties of industrial polymers, submitted to PWR accident simulations

    The effect of PWR plant normal and accident operating conditions on polymers forms the basis of nuclear qualification of safety-related containment equipment. This study was carried out on the request of safety organizations. Its purpose was to check whether accident simulations carried out sequentially during equipment qualification tests would lead to the same deterioration as that caused by an accident involving simultaneous irradiation and thermodynamic effects. The IPSN, DAS and the United States NRC have collaborated in preparing this study. The work carried out by ORIS Company as well as the results obtained from measurement of the mechanical properties of 8 industrial polymers are described in this report. The results are given in the conclusion. They tend to show that, overall, the most suitable test cycle for simulating accident operating conditions would be one which included irradiation and consecutive thermodynamic shock. The results of this study and the results obtained in a previous study, which included the same test cycles, except for more severe thermo-ageing, have been compared. This comparison, which was made on three elastomers, shows that ageing after the accident has a different effect on each material

  20. Study of a loss of coolant accident of a PWR reactor through a Full Scope Simulator and computational code RELAP

    The present paper proposes a study of a loss of coolant accident of a PWR reactor through a Full Scope Simulator and computational code RELAP. To this end, it considered a loss of coolant accident with 160 cm2 breaking area in cold leg of 20 circuit of the reactor cooling system of nuclear power plant Angra 2, with the reactor operating in stationary condition, to 100% power. It considered that occurred at the same time the loss of External Power Supply and the availability of emergency cooling system was not full. The results obtained are quite relevant and with the possibility of being used in the planning of future activities, given that the construction of Angra 3 is underway and resembles the Angra 2. (author)

  1. Evaluation of severe accident risks: Quantification of major input parameters: MAACS [MELCOR Accident Consequence Code System] input

    Estimation of offsite accident consequences is the customary final step in a probabilistic assessment of the risks of severe nuclear reactor accidents. Recently, the Nuclear Regulatory Commission reassessed the risks of severe accidents at five US power reactors (NUREG-1150). Offsite accident consequences for NUREG-1150 source terms were estimated using the MELCOR Accident Consequence Code System (MACCS). Before these calculations were performed, most MACCS input parameters were reviewed, and for each parameter reviewed, a best-estimate value was recommended. This report presents the results of these reviews. Specifically, recommended values and the basis for their selection are presented for MACCS atmospheric and biospheric transport, emergency response, food pathway, and economic input parameters. Dose conversion factors and health effect parameters are not reviewed in this report. 134 refs., 15 figs., 110 tabs

  2. Evaluation of severe accident risks: Quantification of major input parameters: MAACS (MELCOR Accident Consequence Code System) input

    Sprung, J.L.; Jow, H-N (Sandia National Labs., Albuquerque, NM (USA)); Rollstin, J.A. (GRAM, Inc., Albuquerque, NM (USA)); Helton, J.C. (Arizona State Univ., Tempe, AZ (USA))

    1990-12-01

    Estimation of offsite accident consequences is the customary final step in a probabilistic assessment of the risks of severe nuclear reactor accidents. Recently, the Nuclear Regulatory Commission reassessed the risks of severe accidents at five US power reactors (NUREG-1150). Offsite accident consequences for NUREG-1150 source terms were estimated using the MELCOR Accident Consequence Code System (MACCS). Before these calculations were performed, most MACCS input parameters were reviewed, and for each parameter reviewed, a best-estimate value was recommended. This report presents the results of these reviews. Specifically, recommended values and the basis for their selection are presented for MACCS atmospheric and biospheric transport, emergency response, food pathway, and economic input parameters. Dose conversion factors and health effect parameters are not reviewed in this report. 134 refs., 15 figs., 110 tabs.

  3. PSYCHIATRIC CONSEQUENCES OF STRESS AFTER A VEHICLE ACCIDENT

    Dickov, Aleksandra; Martinović-Mitrović, Sladjana; Vučković, Nikola; Siladji-Mladenović, Djendji; Mitrović, Dragan; Jovičević, Mirjana; Mišić-Pavkov, Gordana

    2009-01-01

    Background: Vehicle accidents are a common cause of disease and death among people over 30 years of age. Essentially, reaction to stress due to the vehicle accident does not differ from the reaction to other stress factors. There are still no uniform viewpoints about the kind of sequels and their percentage representation after vehicle accidents. Subjects and methods: The research was provided as a prospective study, included 150 subjects who had vehicle accident minimum 2 years prior to t...

  4. Process criticality accident likelihoods, consequences, and emergency planning

    Evaluation of criticality accident risks in the processing of significant quantities of fissile materials is both complex and subjective, largely due to the lack of accident statistics. Thus, complying with standards such as ISO 7753 which mandates that the need for an alarm system be evaluated, is also subjective. A review of guidance found in the literature on potential accident magnitudes is presented for different material forms and arrangements. Reasoned arguments are also presented concerning accident prevention and accident likelihoods for these material forms and arrangements. 13 refs., 1 fig., 1 tab

  5. Numerical simulation of the insulation material transport to a PWR core under loss of coolant accident conditions

    Höhne, Thomas, E-mail: T.Hoehne@hzdr.de [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Fluid Dynamics, P.O. Box 510119, D-01328 Dresden (Germany); Grahn, Alexander; Kliem, Sören; Rohde, Ulrich; Weiss, Frank-Peter [Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Fluid Dynamics, P.O. Box 510119, D-01328 Dresden (Germany)

    2013-05-15

    Highlights: ► Detailed results of a numerical simulation of the insulation material transport to a PWR core are shown. ► The spacer grid is modeled as a strainer which completely retains the insulation material carried by coolant. ► The CFD calculations showed that the fibers at the upper spacer grid plane are not uniformly distributed. ► Furthermore the pressure loss does not exceed a critical limit. ► The PWR core coolablity can be guaranteed all the time during the transient. -- Abstract: In 1992, strainers on the suction side of the ECCS pumps in Barsebäck NPP Unit 2 became partially clogged with mineral wool because after a safety valve opened the steam impinged on thermally insulated equipment and released mineral wool. This event pointed out that strainer clogging is an issue in the course of a loss-of-coolant accident. Modifications of the insulation material, the strainer area and mesh size were carried out in most of the German NPPs. Moreover, back flushing procedures to remove the mineral wool from the strainers and differential pressure measurements were implemented to assure the performance of emergency core cooling during the containment sump recirculation mode. Nevertheless, it cannot be completely ruled out, that a limited amount of small fractions of the insulation material is transported into the RPV. During a postulated cold leg LOCA with hot leg ECC injection, the fibers enter the upper plenum and can accumulate at the fuel element spacer grids, preferably at the uppermost grid level. This effect might affect the ECC flow into the core and could result in degradation of core cooling. It was the aim of the numerical simulations presented to study where and how many mineral wool fibers are deposited at the upper spacer grid. The 3D, time dependent, multi-phase flow problem was modeled applying the CFD code ANSYS CFX. The CFD calculation does not yet include steam production in the core and also does not include re-suspension of the

  6. Numerical simulation of the insulation material transport to a PWR core under loss of coolant accident conditions

    Highlights: ► Detailed results of a numerical simulation of the insulation material transport to a PWR core are shown. ► The spacer grid is modeled as a strainer which completely retains the insulation material carried by coolant. ► The CFD calculations showed that the fibers at the upper spacer grid plane are not uniformly distributed. ► Furthermore the pressure loss does not exceed a critical limit. ► The PWR core coolablity can be guaranteed all the time during the transient. -- Abstract: In 1992, strainers on the suction side of the ECCS pumps in Barsebäck NPP Unit 2 became partially clogged with mineral wool because after a safety valve opened the steam impinged on thermally insulated equipment and released mineral wool. This event pointed out that strainer clogging is an issue in the course of a loss-of-coolant accident. Modifications of the insulation material, the strainer area and mesh size were carried out in most of the German NPPs. Moreover, back flushing procedures to remove the mineral wool from the strainers and differential pressure measurements were implemented to assure the performance of emergency core cooling during the containment sump recirculation mode. Nevertheless, it cannot be completely ruled out, that a limited amount of small fractions of the insulation material is transported into the RPV. During a postulated cold leg LOCA with hot leg ECC injection, the fibers enter the upper plenum and can accumulate at the fuel element spacer grids, preferably at the uppermost grid level. This effect might affect the ECC flow into the core and could result in degradation of core cooling. It was the aim of the numerical simulations presented to study where and how many mineral wool fibers are deposited at the upper spacer grid. The 3D, time dependent, multi-phase flow problem was modeled applying the CFD code ANSYS CFX. The CFD calculation does not yet include steam production in the core and also does not include re-suspension of the

  7. Analysis of severe accident on OPR1000 PWR plant at low power and shutdown states with MAAP5 code

    The objective of this paper is to provide a brief description of severe accident analysis using computer codes in Korean OPR1000 Plant at low power and shutdown states. The results of the analysis are utilized in preparing the shutdown severe accident management guidelines (LPSD SAMG). As part of the efforts to prepare LPSD SAMG, analysis of severe accident is performed at low power and shutdown states with MAAP5 code. The Korean OPR1000 plant, a PWR plant with 2 hot legs and 4 cold legs is considered as a reference plant in the analysis. In this study, the scenarios are selected based on the plant operational states (POS) and dominant initiating events (IE) which cause the core damages. Typical scenarios are the loss of shutdown cooling (LSCS) at various primary coolant levels and stuck-opening of valves which prevent the low temperature over pressurization (LTOP) of primary system. As the analysis results, the core uncovery is expected in 2∼6 hours. The maximum temperature of core exit exceeds 649degC (SAMG entry temperature) in 3∼7 hours. The molten corium starts to relocate into lower head in 5∼13 hours and reactor vessel failure is occurred in 11∼14 hours. The above mentioned timings are utilized to choose the possible actions and the timing to implement those actions LPSD SAMG. Also based on the results, the environmental conditions that instruments may encounter in a severe accident are determined. (author)

  8. Analysis of high burnup fuel behavior under rod ejection accident in the Westinghouse-designed 950 MWe PWR

    As there has arisen a concern that failure of the high burnup fuel under the reactivity-insertion accident (RIA) may occur at the energy lower than the expected, duel behavior under the rod ejection accident in a typical Westinghouse-designed 950 MWe PWR was analyzed by using the three dimensional nodal transient neutronics code, PANBOX2 and the transient fuel rod performance analysis code, FRAP-T6. Fuel failure criteria versus the burnup was conservatively derived taking into account available test data and the possible fuel failure mechanisms. The high burnup and longer cycle length fuel loading scheme of a peak rod burnup of 68 MWD/kgU was selected for the analysis. Except three dimensional core neutronics calculation, the analysis used the same core conditions and assumptions as the conventional zero dimensional analysis. Results of three dimensional analysis showed that the peak fuel enthalpy during the rod ejection accident is less than one third of that calculated by the core is less than 4 percent. Therefore, it can be said that the current design limit of less than 10 percent fuel failure and maintaining the core coolable geometry would be adequately satisfied under the rod ejection accident, even though the conservative fuel failure criteria derived from the test data are applied. (author)

  9. The aftermath of nuclear accidents on mental health; Consequences des accidents radiologiques sur la sante mentale

    Pirard, Ph.; Brenot, J.; Verger, P. [CEA Fontenay-aux-Roses, 92 (France). Inst. de Protection et de Surete Nucleaire

    1998-10-01

    Technological disasters bring about psychological effects in exposed populations of various durability and intensity. This article reviews the epidemiological studies which assess psychological and psychiatric consequences of the Three Mile Island, Goieanna and Chernobyl accidents. It shows, in different accidental and cultural contexts, a statistically significant and durable increase of psychological symptoms in various exposed population groups, which points out an actual psychological distress. Diagnosed psychiatric effects are less constant, but much less studied. Most affected groups are mothers of young children, relocated persons, persons with less social support or in financial trouble. The psychological distress can further psychiatric disorders and give rise to behavioural changes towards health. More research is necessary to delineate the nature and the determinants of the observed symptoms and disorders. It implies to design better tools for the assessment of individual exposure and the diagnosis of mental health effects. (authors)

  10. The primal application research of figure assimilation theory in the nuclear accident consequence forecast

    The deepgoing research of figure assimilation theory promotes many subjects' rapid development. This article outlooks the application of figure assimilation technique in the nuclear accident consequence forecast. The nuclear accident consequence forecast is a complicated system which needs rapidity and precision, so it is quiet difficult. but after the insertion of figure assimilation, it pushes on one step about the question. (authors)

  11. Radiological consequences of the Three Mile Island accident

    The Three Mile Island Accident is described. The pathway and quantity of radioactive materials released, the radiological monitoring results and health effects are discussed. It was concluded that while radiological releases were small in view of the magnitude of fuel damage, the accident indicated that better health physics instrumentation and personnel training is required. (H.K.)

  12. Immediate medical consequences of nuclear accidents: lessons from Chernobyl

    The immediate medical response to the nuclear accident at the Chernobyl nuclear power station involved containment of the radioactivity and evacuation of the nearby population. The next step consisted of assessment of the radiation dose received by individuals, based on biological dosimetry, and treatment of those exposed. Medical care involved treatment of skin burns; measures to support bone marrow failure, gastrointestinal tract injury, and other organ damage (i.e., infection prophylaxis and transfusions) for those with lower radiation dose exposure; and bone marrow transplantation for those exposed to a high dose of radiation. At Chernobyl, two victims died immediately and 29 died of radiation or thermal injuries in the next three months. The remaining victims of the accident are currently well. A nuclear accident anywhere is a nuclear accident everywhere. Prevention and cooperation in response to these accidents are essential goals

  13. A comparison of the consequences of the design basis accident of the Greek Research Reactor with those of a serious realistic accident

    An analysis of the radiological consequences of the design basis and the coolant flow blockage accidents of the Greek Research Reactor is presented. The results indicate that the consequences of the coolant flow blockage accident are practically trivial being 1-2 orders of magnitude lower than the corresponding consequences of the design basis accident. (author)

  14. The consequences from liquid pathways after a reactor meltdown accident

    The potential radiological impact of a core-melt accident on the human population has been investigated. In particular, the radiation dose received from radioactivity which could reach the population via liquid pathways has been considered. Radioactivity could be released directly to the hydrosphere after a core-melt accident as a result of melt-through of the containment basemat followed by any of three processes: (1) leaching of the melt debris; 2 escape of sumpwater through the hole formed by the melt (or from passage out of the containment by an alternate route); and 3) depressurization of the containment atmosphere through the melt hole. The three types of releases would differ primarily in their rates, their magnitudes and their radioactive compositions. Both the containment atmosphere and the sumpwater releases would occur relatively rapidly. However, most of the radionuclides present in these two releases in substantial quantities would be expected to be rather short-lived. Therefore, such releases could have a significant impact at a specific site only if the travel times of the important radionuclides to the human population were small. In contrast, leaching of radionuclides from the melt debris would be expected to occur relatively slowly. Most of the long-lived isotopes would be expected to be found primarily in the melt debris. Consequently, even though this release occurred relatively slowly, the impact could still be significant. In contrast to the situation for releases to the atmosphere, accidents corresponding to the most probable RSS (Reactor Safety Study) meltdown categories would result in the largest releases to the hydrosphere. Furthermore, substantial amounts of radioactivity would generally be expected to be released to the hydrosphere during any meltdown accident involving complete melt-through of the containment basemat. On the basis of subsurface hydrologies alone, sites range from those that essentially preclude any impacts to the human

  15. Prevention of the causes and consequences of a criticality accident - measures adopted in France

    The question of safety in regard to criticality accident risks has two aspects: prevention of the cause and limitation of the consequences. These two aspects are closely connected. The effort devoted to prevention of the causes depends on the seriousness of the possible human psychologic and economic consequences of the accident. The criticality accidents which have occurred in the nuclear industry, though few in number, do reveal the imperfect nature of the techniques adopted to prevent the causes, and also constitute the only available realistic basis for evaluating the consequences and developing measures to limit them. The authors give a analysis of the known causes and consequences of past criticality accidents and on this basis make a number of comments concerning: the validity of traditional safety criteria, the probability of accidents for different types of operations, characteristic accidents which can serve as models, and the extent of possible radiological consequences. The measures adopted in France to limit the consequences of a possible criticality accident under the headings: location, design and lay-out of the installations, accident detection, and dosimetry for the exposed personnel, are briefly described after a short account of the criteria used in deciding on them. (author)

  16. Prevention of "simple accidents at work" with major consequences

    Jørgensen, Kirsten

    2016-01-01

    prevention or safety methodologies and procedures established for major accidents are applicable to simple accidents. The article goes back to basics about accidents causes, to review the nature of successful prevention techniques and to analyze what have been constraints to getting this knowledge used more...... broadly. This review identifies gaps in the prevention of simple accidents, relating to safety barriers for risk control and the management processes that need to be in place to deliver those risk controls in a continuingly effective state. The article introduces the ‘‘INFO cards’’ as a tool for the...... systematic observation of hazard sources in order to ascertain whether safety barriers and management deliveries are present. Safety management and safety culture, together with the INFO cards are important factors in the prevention process. The conclusion is that we must look at safety as a part of being a...

  17. The physical and chemical degradation of PWR fuel rods in severe accident conditions

    An experimental study of the interaction between Zircaloy-4 cladding and UO2 in PWR fuel rods heated to high temperatures with a negligible differential pressure across the cladding wall is described. The fuel rods were of dimensions appropriate to the 17x17 PWR fuel sub-assembly and were heated in a non-oxidising environment (vacuum) up to approx. 1850 deg. C either isothermally or through heating ramps. Observations were made concerning the extent and nature of the reaction zone between Zircaloy-4 and UO2 over the temperature range 1500-1850 deg. C for times ranging from 1 min to 125 min. The location, morphology and the chemical composition of the phases formed are described along with the kinetics of their formation. (author)

  18. Consequences of the nuclear power plant accident at Chernobyl.

    Ginzburg, H M; Reis, E.

    1991-01-01

    The Chernobyl Nuclear Power Plant accident, in the Ukrainian Soviet Socialist Republic (SSR), on April 26, 1986, was the first major nuclear power plant accident that resulted in a large-scale fire and subsequent explosions, immediate and delayed deaths of plant operators and emergency service workers, and the radioactive contamination of a significant land area. The release of radioactive material, over a 10-day period, resulted in millions of Soviets, and other Europeans, being exposed to m...

  19. Radioecological and dosimetric consequences of Chernobyl accident in France; Consequences radioecologiques et dosimetriques de l`accident de Tchernobyl en France

    Renaud, Ph.; Beaugelin, K.; Maubert, H.; Ledenvic, Ph

    1997-12-31

    After ten years and the taking in account of numerous data, it can be affirmed that the dosimetric consequences of Chernobyl accident will have been limited in France. for the period 1986-2046, the individual middle efficient dose commitment, for the area the most reached by depositing is inferior to 1500 {mu}Sv, that represents about 1% of middle natural exposure in the same time. but mountains and forests can have more important surface activities than in plain. Everywhere else, it can be considered that the effects of Chernobyl accident are disappearing. the levels of cesium 137 are now often inferior to what they were before the accident. (N.C.)

  20. Genetic consequences of the Chernobyl accident for Belarus republic

    various uncertainties. Only direct methods, which count the final effect, with all their drawbacks, can provide accurate information on genetic losses. We have estimated possible genetic consequences for the residents of Belarus Republic due to the Chernobyl accident by studying malformations found in legal medical abortuses and by counting congenital anomalies in fetuses and newborns. (J.P.N.)

  1. Accident management following loss of residual heat removal during mid-loop operation in a Westinghouse two-loop PWR

    Birchley, J. [Paul Scherrer Institut, CH-5232 Villigen (Switzerland)], E-mail: jonathan.birchley@psi.ch; Haste, T.J. [Paul Scherrer Institut, CH-5232 Villigen (Switzerland); Richner, M. [Nordostschweizerische Kraftwerke (NOK) - NPP Beznau, CH-5312 Doettingen (Switzerland)

    2008-09-15

    The possibility of an accident or component failure during mid-loop operation has been identified in probabilistic studies as a major contributor to core melt frequency and source term risk during shutdown conditions. The wide range of plant states encountered and the unavailability of certain safety features make it difficult to guarantee that safety systems operation will always be sufficient to terminate the accident evolution. In this context analyses are performed using MELCOR 1.8.5 for loss of residual heat removal (RHR) at various times during mid-loop operation of a Westinghouse two-loop PWR. In the absence of recovery of RHR or other accident management (AM) measures, the sequences necessarily lead to a long term core uncovery, heat-up and degradation, loss of geometry and eventual failure of the reactor pressure vessel (RPV). The results show an extensive time window before uncovery and additionally before core damage, which increase progressively with increasing time after shutdown at which loss of RHR occurs. Significant oxidation of the cladding may result in concentrations of hydrogen sufficient for deflagration. The slow evolution implies an opportunity for the plant operators to initiate AM measures even after core uncovery has started. The analyses indicate a substantial time window during the uncovery within which the injection can recover the core without damage. The upper end of the window is determined by the temperature at which heat from cladding oxidation becomes a dominant factor, marking a critical point for the effectiveness of this recovery mode. The results provide confidence in the inherent robustness of the plant with respect to accident sequences of this type.

  2. The consequences of the Chernobyl nuclear accident in Greece - Report No. 2

    In this report a realistic estimate of the radioactive fallout on Greece from the Chernobyl nuclear accident is described. The measurements performed on environmental samples and samples of the food chain, as well as some realistic estimations for the population doses and the expected consequences of the accident are presented. The analysis has shown that the radiological impact of the accident in Greece can be considered minor. (J.K.)

  3. ICARE/CATHARE V1. Application to a PWR 900 MWe severe accident sequence

    Zabiego, Magali; Fichot, Florian; Guillard, Valia; Barrachin, Marc; Melis, Stephane; Chatelard, Patrick; Camous, Francine [Commissariat a l' Energie Atomique, Institut de Protection et de Surete Nucleaire, DRS/SEMAR/LECTA, Centre d' Etudes de Cadarache, St-Paul-Les-Durance Cedex (France); Lefevre, Bertrand [Communications et Systems, Centre d' Etudes de Cadarache, St-Paul-Lez-Durance (France)

    2000-11-01

    In the first part of this paper, a brief description of the V1 version of the ICARE/CATHARE software is presented. The new models developed by IPSN are described here. An application of this version to a French PWR 900 MWe is then shown. Although a description of the whole circuit is possible with ICARE/CATHARE V1, the present application is restricted to the reactor vessel. The results show the progression of the core degradation and the relocation of an important amount of corium in the reactor lower head. This calculation demonstrates the capacity of the code to provide a physically grounded simulation of the whole scenario. (author)

  4. Quantification of in-containment fission products source term for 1000 MWe PWR under loss of coolant accident

    Highlights: • Kinetic modeling for in-containment fission product activity. • Modeling and simulation of in-containment source term after LOCA. • Quantification of airborne in-containment activity. • BURNUP activity calculation and comparison with literature. • Study the effect of ESFs and coolant retention with mixing rate. - Abstract: The aim of this work is the modeling and simulation of in-containment fission products (FPs) quantification and behavior under loss of coolant accident (LOCA) in terms of NUREG-1465 key aspects. For this purpose, a kinetic model has been developed to determine the quantification and behavior of in-containment source term after loss of coolant accident for typical 1000 MWe PWR. A more realistic approach of continuous release of fission products from damaged core has been implemented with coolant retention. The simulation for in-containment fission product quantification influenced by containment atmosphere and containment system response has been carried out. Dramatic results have been obtained upon comparison study of fission product behaviors with different computational values. Moreover a contradiction in mixing rate (wx) value has been observed with a factor of 10 in comparison with Saeed et al. (2012)

  5. Investigation of the different scenarios occurring in a PWR in case of a TMLB accident

    Severe accidents in light water reactors fall into one of two main categories, depending on whether or not core meltdown is accompanied by a pressure buildup in the primary system. The way in which the accident develops is, in fact, largely conditioned by this pressure aspect: temperature distribution in the core and primary system resulting from natural convection gas streams; fuel clad failure mode, etc... One major effect of pressure buildup on the accident scenario is primary system failure under the combined actions of pressure and temperature. The purpose of the present paper is to present, after a detailed thermalhydraulic study, an analysis of the timing and location of the system failures in case of a TMLB accident on CPY french type reactor

  6. Radiation-biological consequences of the Chernobyl accident

    The paper points out essential aspects of the actual or potential impact of the Chernobyl reactor accident on human health in the areas immediately affected. In particular, radiation-induced diseases in the population are pointed out, which were caused by radioactive iodine. Epidemiological studies try to establish an increased incidence of leukaemia, lymphomas, and thyroid gland tumours. (DG)

  7. Radiological consequence of Chernobyl nuclear power accident in Japan

    Two years have elapsed since the accident in Chernobyl nuclear power station shocked those concerned with nuclear power generation. The effect that this accident exerted on human environment has still continued directly and indirectly, and the reports on the effect have been made in various countries and by international organizations. In Japan, about the exposure dose of Japanese people due to this accident, the Nuclear Safety Commission and Japan Atomic Energy Research Institute issued the reports. In this report, the available data concerning the envrionmental radioactivity level in Japan due to the Chernobyl accident are collected, and the evaluation of exposure dose which seems most appropriate from the present day scientific viewpoint was attempted by the detailed analysis in the National Institute of Radiological Sciences. The enormous number of the data observed in various parts of Japan were different in sampling, locality, time and measuring method, so difficulty arose frequently. The maximum concentration of I-131 in floating dust was 2.5 Bq/m3 observed in Fukui, and the same kinds of radioactive nuclides as those in Europe were detected. (Kako, I.)

  8. The possibility of building nuclear power plant free from severe accident risk: PWR NPP with advanced all passive safety cooling systems (AAP SCS)

    A complete set of advanced all passive safety cooling systems (AAP SCS) for PWR NPP, actuated by natural force has been put forward in the article. Here the natural force mainly means the fore, which created by change of pressure distribution in the first loop of PWR as a result of operational regime conversion from one to another, including occurrence of accident situation. Correspondent safety cooling system will be actuated naturally and then put it into passive operation after occurring some kind of accident, so accidental situation will be mitigated right after it's occurrence and core residual heat will be naturally moved from the active core to the ultimate heat sink. There is no need to rely on automatic control system, any active equipment and human actions in all working process of the AAP SCS, which can reduce the probability of severe accident to zero, so as to exclude the need of evacuation plan around AAP nuclear power plant and eliminate the public's concern and doubt about nuclear power safety. Implementation of the AAP SCS concept is only based on use of evolutionary measures and state-of-the-art technology. So at present time it can be used for design of new-type third generation PWR nuclear power plant without severe accident risk, and for modernization of existing second generation nuclear power plant. (authors)

  9. An Analysis of the Cumulative Uncertainty Associated with a Quantitative Consequence Assessment of a Major Accident

    JIRSA PAVEL

    2005-01-01

    The task of the article is to quantify the uncertainty of the possible results of the accident consequence assessment of the chemical production plant and to provide some description of potentional problems with literature references and examples to help to avoid the erroneous use of available formulas. Based on numbers presented in the article we may conclude, that the main source of uncertainty in the consequence analysis of chemical accident assessment is surprisingly not only the dispers...

  10. The Chernobyl Accident 20 Years On: An Assessment of the Health Consequences and the International Response

    Baverstock, Keith; Williams, Dillwyn

    2006-01-01

    Background The Chernobyl accident in 1986 caused widespread radioactive contamination and enormous concern. Twenty years later, the World Health Organization and the International Atomic Energy Authority issued a generally reassuring statement about the consequences. Accurate assessment of the consequences is important to the current debate on nuclear power. Objectives Our objectives in this study were to evaluate the health impact of the Chernobyl accident, assess the international response ...

  11. The international conference ''one decade after Chernobyl: Summing up the consequences of the accident''

    An International Conference entitled ''One decade after Chernobyl: Summing up the consequences of the accident'' was held at the Austria Center Vienna from 8 to 12 April 1996, the aim being to seek a common and conclusive understanding of the nature and magnitude of the consequences of the Chernobyl accident. The Conference was attended by 845 participants and observers from 71 countries and 20 organizations and covered by 208 journalists from 31 countries and two organizations

  12. Radioecological and dosimetric consequences of the Chernobyl accident in France; Consequences radioecologiques et dosimetriques de l'accident de Tchernobyl en France

    Renaud, Ph.; Beaugelin, K.; Maubert, H.; Ledenvic, Ph. [Inst. de Protection et de Surete Nucleaire, CEA Centre d' Etudes de Fontenay-aux-Roses, 92 (France)

    1997-11-01

    This study has as objective a survey of the radioecological and dosimetric consequences of the Chernobyl accident in France, as well as a prognosis for the years to come. It was requested by the Direction of Nuclear Installation Safety (DSIN) in relation to different organisms which effected measurements after this accident. It is based on the use of combined results of measurements and modelling by means of the code ASTRAL developed at IPSN. Various measurements obtained from five authorities and institutions, were made available, such as: activity of air and water, soil, processed food, agricultural and natural products. However, to achieve the survey still a modelling is needed. ASTRAL is a code for evaluating the ecological consequences of an accident. It allows establishing the correspondence between the soil Remnant Surface Activities (RSA, in Bq.m{sup -2}), the activity concentration of the agricultural production and the individual and collective doses resulting from external and internal exposures (due to inhalation and ingestion of contaminated nurture). The results of principal synthesis documents on the Chernobyl accident and its consequences were also used. The report is structured in nine sections, as follows: 1.Introduction; 2.Objective and methodology; 3.Characterization of radioactive depositions; 4;Remnant surface activities; 5.Contamination of agricultural products and foods; 6.Contamination of natural, semi-natural products and of drinking water; 7.Dosimetric evaluations; 8.Proposals for the environmental surveillance; 9.Conclusion. Finally, after ten years, one concludes that at presentthe dosimetric consequences of the Chernobyl accident in France were rather limited. For the period 1986-2046 the average individual effective dose estimated for the most struck zone is lower than 1500 {mu}Sv, which represents almost 1% of the average natural exposure for the same period. At present, the cesium 137 levels are at often inferior to those recorded

  13. Russian National Chernobyl Register as information and and analytical for Chernobyl accident medical consequences estimation

    The paper is devoted to using of the National Radiation and Epidemiology Register basic part, namely the Russian State Medical-Dosimetric Register of the people affected by the Chernobyl accident, to estimate the medical consequences of the accident. First part of article presents the common description and current state of Register. The estimation of medical consequences of the accident for clean-up workers is given in second part. The prognosis of radiation effects and definition of basic epidemiology factors to propose optimal medicalrehabilitation measures is discussed

  14. TMI-2 - A Case Study for PWR Instrumentation Performance during a Severe Accident

    Joy L. Rempe; Darrell L. Knudson

    2014-05-01

    The accident at the Three Mile Island Unit 2 (TMI-2) reactor provided a unique opportunity to evaluate sensors exposed to severe accident conditions. Conditions associated with the release of coolant and the hydrogen burn that occurred during this accident exposed instrumentation to harsh conditions, including direct radiation, radioactive contamination, and high humidity with elevated temperatures and pressures. As part of a program initiated in 2012 by the Department of Energy Office of Nuclear Energy (DOE-NE), a review was completed to gain insights from prior TMI-2 sensor survivability and data qualification efforts. This new effort focussed upon a set of sensors that provided critical data to TMI-2 operators for assessing the condition of the plant and the effects of mitigating actions taken by these operators. In addition, the effort considered sensors providing data required for subsequent accident simulations. Over 100 references related to instrumentation performance and post-accident evaluations of TMI-2 sensors and measurements were reviewed. Insights gained from this review are summarized within this report. For each sensor, a description is provided with the measured data and conclusions related to the sensor’s survivability, and the basis for conclusions about its survivability. As noted within this document, several techniques were invoked in the TMI-2 post-accident evaluation program to assess sensor status, including comparisons with data from other sensors, analytical calculations, laboratory testing, and comparisons with sensors subjected to similar conditions in large-scale integral tests and with sensors that were similar in design but more easily removed from the TMI-2 plant for evaluations. Conclusions from this review provide important insights related to sensor survivability and enhancement options for improving sensor performance. In addition, this document provides recommendations related to the sensor survivability and data evaluation

  15. TMI-2 - A Case Study for PWR Instrumentation Performance during a Severe Accident

    Joy L. Rempe; Darrell L. Knudson

    2013-03-01

    The accident at the Three Mile Island Unit 2 (TMI-2) reactor provided a unique opportunity to evaluate sensors exposed to severe accident conditions. Conditions associated with the release of coolant and the hydrogen burn that occurred during this accident exposed instrumentation to harsh conditions, including direct radiation, radioactive contamination, and high humidity with elevated temperatures and pressures. As part of a program initiated in 2012 by the Department of Energy Office of Nuclear Energy (DOE-NE), a review was completed to gain insights from prior TMI-2 sensor survivability and data qualification efforts. This new effort focussed upon a set of sensors that provided critical data to TMI-2 operators for assessing the condition of the plant and the effects of mitigating actions taken by these operators. In addition, the effort considered sensors providing data required for subsequent accident simulations. Over 100 references related to instrumentation performance and post-accident evaluations of TMI-2 sensors and measurements were reviewed. Insights gained from this review are summarized within this report. For each sensor, a description is provided with the measured data and conclusions related to the sensor’s survivability, and the basis for conclusions about its survivability. As noted within this document, several techniques were invoked in the TMI-2 post-accident evaluation program to assess sensor status, including comparisons with data from other sensors, analytical calculations, laboratory testing, and comparisons with sensors subjected to similar conditions in large-scale integral tests and with sensors that were similar in design but more easily removed from the TMI-2 plant for evaluations. Conclusions from this review provide important insights related to sensor survivability and enhancement options for improving sensor performance. In addition, this document provides recommendations related to the sensor survivability and data evaluation

  16. Extra-regulatory accident safety evaluation for the PWR S/F transport and storage system

    In the field of high speed crash, high speed impact analyses and test were performed for two systems, the dual purpose metal cask and the concrete cask considering the aircraft crash condition. Through the tests, the procedure and methodology of the assessment were successfully validated. In the field of transient fire, the computer simulation method for transient fire was drawn through the overseas status and methodology analysis. In the field of cumulative damage evaluation for transport accident, the analysis technique for assessment for cumulative damages which occurred from successive accident conditions was developed and proposed. And the sequential tests for the dual purpose cask were performed

  17. One decade after Chernobyl. Summing up the consequences of the accident. Proceedings of an international conference

    The consequences attributed to the disastrous accident that occurred at the Chernobyl nuclear power plant on 26 April 1986 have been subjected to extensive scientific examination; however, they are still viewed with widely differing perspectives. It is fitting then that, ten years after the accident, the European Commission (EC), the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO) should jointly sponsor an international conference to review the consequences of the accident and to seek a common and conclusive understanding of their nature and magnitude. The International Conference on One Decade after Chernobyl: Summing up the Consequences of the Accident was held at the Austria Center, Vienna, on 8-12 April 1996. Refs, figs, tabs

  18. External and internal accidents in PWR power plants. Comparison of current regulations in Belgium, United States, France, Federal Republic of Germany and United Kingdom

    In this report a comparison is made of the rules and practices applied in various countries (Belgium, France, Federal Republic of Germany, United Kingdom and United States of America) in designing PWR plants to resist natural hazards (first part of the report) and hazards associated with human activities (second part). The third part of the report deals with the practices in different countries concerning the protection against accidents of internal origin

  19. Cancer consequences of the Chernobyl accident: 20 years on

    Cardis, Elisabeth [International Agency for Research on Cancer, 150 Cours Albert Thomas, 69372 Lyon CEDEX 08 (France); Howe, Geoffrey [Department of Epidemiology, Mailman School of Public Health, Columbia University, 722 W. 168th Street, Room 1104, New York, NY 10032 (United States); Ron, Elaine [Radiation Epidemiology Branch, Division of Epidemiology and Genetics, National Cancer Institute, Building EPS, MS 7238, Rockville, MD 20852 (United States)] (and others)

    2006-06-15

    26 April 2006 marks the 20th anniversary of the Chernobyl accident. On this occasion, the World Health Organization (WHO), within the UN Chernobyl Forum initiative, convened an Expert Group to evaluate the health impacts of Chernobyl. This paper summarises the findings relating to cancer. A dramatic increase in the incidence of thyroid cancer has been observed among those exposed to radioactive iodines in childhood and adolescence in the most contaminated territories. Iodine deficiency may have increased the risk of developing thyroid cancer following exposure to radioactive iodines, while prolonged stable iodine supplementation in the years after exposure may reduce this risk. Although increases in rates of other cancers have been reported, much of these increases appear to be due to other factors, including improvements in registration, reporting and diagnosis. Studies are few, however, and have methodological limitations. Further, because most radiation-related solid cancers continue to occur decades after exposure and because only 20 years have passed since the accident, it is too early to evaluate the full radiological impact of the accident. Apart from the large increase in thyroid cancer incidence in young people, there are at present no clearly demonstrated radiation-related increases in cancer risk. This should not, however, be interpreted to mean that no increase has in fact occurred: based on the experience of other populations exposed to ionising radiation, a small increase in the relative risk of cancer is expected, even at the low to moderate doses received. Although it is expected that epidemiological studies will have difficulty identifying such a risk, it may nevertheless translate into a substantial number of radiation-related cancer cases in the future, given the very large number of individuals exposed. (rev0009i.

  20. The radioecological consequences of Chernobyl accident for fish

    The estimate of dynamics of radionuclides concentration in muscles of some game-fish from Kiev reservoir and likes in Bryansk region for period after Chernobyl accident was carried out. The concentration of 137Cs in fish has not exceeded the admissible concentration (600 Bq/kg ww) since 1993. The exceptions are the cooling-pond of Chernobyl NPP and Kozlanovskoe Lake where the concentration of 137Cs in fish's muscles exceeded the admissible level more than 5-6 times even in 1995. It was concluded that chronic irradiation of game-fish in water bodies outside 30-km zone would not affect the volume of fishing

  1. Consequences of the Chernobyl accident in France. Thematic sheets; Les consequences de l'accident de Tchernobyl en France. Fiches thematiques

    NONE

    2006-07-01

    This document proposes a set of commented maps, graphs and drawings which illustrate and describe various consequences of the Chernobyl accident in France, such as air contamination (scattering of radioactive particles emitted by the reactor explosion by the wind over thousands of kilometres, evolution of air contamination between April 30 and May 5 1986), ground deposits (influence of rain, heterogeneity of these deposits), contamination of farm products (relationship between the accident date and the deposit characteristics, variable decrease rate of contamination, faster decrease of farm product contamination that caesium radioactive decay since 1987, particular cases of some more sensitive products), health effects (low doses received by the French population, concerns about thyroid cancers)

  2. Accident at the Chernobyl nuclear power plant and its consequences

    In the early morning of April 26, 1986, as the culmination of an almost incredible series of errors that began 24 hours earlier, Unit 4 of the Chernobyl nuclear complex, a so-called RBMK-1000 reactor, suffered the worst accident in the history of commercial nuclear power. There was an uncontrolled nuclear excursion, release of a large amount of energy, possibly comparable to hundreds of pounds of TNT, blowing the top off the reactor. There was no containment, in the traditional American sense, so the roof of the building was blown out, an unprecedented amount of radioactivity was released to the biosphere, and a graphite fire was ignited, which burned for days. The radiation that was released spread through Eastern Europe (the world first learned of it through Swedish observations), bringing with it both official and unofficial protests that the Soviet Union had made no announcement of the radiation release until they were, in effect, caught. In fact, after a few days, the Soviets seemed to recognize that nuclear safety is a matter of international concern, and became quite open in their search for cooperation. They invited officials of the International Atomic Energy Agency (IAEA) to visit the area and to fly over the plant, and agreed, in the end, to make a complete disclosure of the details of the accident at a special meeting of IAEA in Vienna, August 25 to 29, 1986. In preparation for that meeting they distributed a lengthy (400 pages) report on the event. This paper reviews this report

  3. Severe accident approach - final report. Evaluation of design measures for severe accident prevention and consequence mitigation.

    Tentner, A. M.; Parma, E.; Wei, T.; Wigeland, R.; Nuclear Engineering Division; SNL; INL

    2010-03-01

    An important goal of the US DOE reactor development program is to conceptualize advanced safety design features for a demonstration Sodium Fast Reactor (SFR). The treatment of severe accidents is one of the key safety issues in the design approach for advanced SFR systems. It is necessary to develop an in-depth understanding of the risk of severe accidents for the SFR so that appropriate risk management measures can be implemented early in the design process. This report presents the results of a review of the SFR features and phenomena that directly influence the sequence of events during a postulated severe accident. The report identifies the safety features used or proposed for various SFR designs in the US and worldwide for the prevention and/or mitigation of Core Disruptive Accidents (CDA). The report provides an overview of the current SFR safety approaches and the role of severe accidents. Mutual understanding of these design features and safety approaches is necessary for future collaborations between the US and its international partners as part of the GEN IV program. The report also reviews the basis for an integrated safety approach to severe accidents for the SFR that reflects the safety design knowledge gained in the US during the Advanced Liquid Metal Reactor (ALMR) and Integral Fast Reactor (IFR) programs. This approach relies on inherent reactor and plant safety performance characteristics to provide additional safety margins. The goal of this approach is to prevent development of severe accident conditions, even in the event of initiators with safety system failures previously recognized to lead directly to reactor damage.

  4. The Chernobyl accident 20 years on: an assessment of the health consequences and the international response.

    Baverstock, Keith; Williams, Dillwyn

    2007-01-01

    Twenty years after the Chernobyl accident the WHO and the International Atomic Energy Authority issued a reassuring statement about the consequences. Our objectives in this study were to evaluate the health impact of the Chernobyl accident, assess the international response to the accident, and consider how to improve responses to future accidents. So far, radiation to the thyroid from radioisotopes of iodine has caused several thousand cases of thyroid cancer but very few deaths; exposed children were most susceptible. The focus on thyroid cancer has diverted attention from possible nonthyroid effects. The international response to the accident was inadequate and uncoordinated, and has been unjustifiably reassuring. Accurate assessment in future health effects is not currently possible in the light of dose uncertainties, current debates over radiation actions, and the lessons from the late consequences of atomic bomb exposure. Because of the uncertainties from and the consequences of the accident, it is essential that investigations of its effects should be broadened and supported for the long term. The United Nations should initiate an independent review of the actions and assignments of the agencies concerned, with recommendations for dealing with future international-scale accidents. These should involve independent scientists and ensure cooperation rather than rivalry. PMID:17680126

  5. Consequences in Norway after a hypothetical accident at Sellafield - Predicted impacts on the environment.

    Thoerring, H.; Liland, A.

    2010-12-15

    This report deals with the environmental consequences in Norway after a hypothetical accident at Sellafield. The investigation is limited to the terrestrial environment, and focus on animals grazing natural pastures, plus wild berries and fungi. Only 137Cs is considered. The predicted consequences are severe, in particular for mutton and goat milk production. (Author)

  6. Consequences in Norway after a hypothetical accident at Sellafield - Predicted impacts on the environment

    This report deals with the environmental consequences in Norway after a hypothetical accident at Sellafield. The investigation is limited to the terrestrial environment, and focus on animals grazing natural pastures, plus wild berries and fungi. Only 137Cs is considered. The predicted consequences are severe - in particular for mutton and goat milk production. (Author)

  7. Severe Accident Progression and Consequence Assessment Methodology Upgrades in ISAAC for Wolsong CANDU6

    Amongst the applications of integrated severe accident analysis codes like ISAAC, the principal are to a) help develop an understanding of the severe accident progression and its consequences; b) support the design of mitigation measures by providing for them the state of the reactor following an accident; and c) to provide a training platform for accident management actions. After Fukushima accident there is an increased awareness of the need to implement effective and appropriate mitigation measures and empower the operators with training and understanding about severe accident progression and control opportunities. An updated code with reduced uncertainties can better serve these needs of the utility making decisions about mitigation measures and corrective actions. Optimal deployment of systems such as PARS and filtered containment venting require information on reactor transients for a number of critical parameters. Thus there is a greater consensus now for a demonstrated ability to perform accident progression and consequence assessment analyses with reduced uncertainties. Analyses must now provide source term transients that represent the best in available understanding and so meaningfully support mitigation measures. This requires removal of known simplifications and inclusion of all quantifiable and risk significant phenomena. Advances in understanding of CANDU6 severe accident progression reflected in the severe accident integrated code ROSHNI are being incorporated into ISAAC using CANDU specific component and system models developed and verified for Wolsong CANDU 6 reactors. A significant and comprehensive upgrade of core behavior models is being implemented in ISAAC to properly reflect the large variability amongst fuel channels in feeder geometry, fuel thermal powers and burnup. The paper summarizes the models that have been added and provides some results to illustrate code capabilities. ISAAC is being updated to meet the current requirements and

  8. Small chances - great consequences or the consequences of a large-scale accident in a nuclear power plant

    This report is a sequel to the previous Boerderijcahier (no. 7502) which discussed long-term effects of soil contamination in case of a nuclear power plant accident. In this report the short-term health effects are discussed. Models describing the local consequences of a severe accident are developed, taking into account the possible weather conditions (meteorological model), the evacuation possibilities and the inhabitability of certain areas. In each case long-term and short-term effects are discussed. The safety studies by various departments of the Netherlands' government and the Rasmussen report are commented on

  9. Analysis for relocation strategy using the method of probabilistic accident consequence assessment

    Relocation is one of the long-term protective actions in case of nuclear emergency to mitigate the consequences of an accidental release of radionuclides. The strategy of relocation is characterized by its protective benefit, cost and the corresponding residual dose in planning. This paper describes the application of a probabilistic accident consequence assessment model to the calculation of these quantities and the planning of relocation. Calculations of the consequence have been made of a postulated accident with source terms derived from a generic level 2 PSA. The results provided the insights for the development optimum dose criteria for introducing and terminating relocation. (author)

  10. Dose rate calculations inside the containment shell of a PWR in case of an accident

    The aim of the study is the evaluation of γ dose rates. In view to treat the different aspects of partial or total melting of the reactor core, leading to emission of a great quantity of fission radioactive products in the containement shell, implying the loss of integrity of the first two containement barriers, the study comprises: 1) Calculation of the γ dose rate as a function of time, normalized in considering a total release of fission products present in the core at the moment of the accident: it is done by taking into account the fission products in suspension in the containement shell, deposited on the internal surfaces and trapped by the water drain. 2) Transfer hypotheses of fission products (the release kinematics are linked to the accident scenario). The hypotheses of emission and deposit in this work are those of Rasmussen

  11. JERICHO computer code: PWR containment response during severe accidents description and sensitivity analysis

    The JERICHO code has been developed in order to study the thermodynamic behaviour inside the reactor containment building for the complete spectrum of accident sequences likely to occur in such a reactor, including models for the various mass and energy transfer phenomena, for water spray, for hydrogen and carbon monoxide flammability limits and combustion, as well as for containment venting. Sensitivity analyses have been performed on a severe accident sequence, (namely, small LOCA with failure of the emergency core cooling and containment spray systems), involving core melting and subsequent concrete containment basemat erosion. The effect of various models, such as mass and energy transfer to the structures, has been studied. The influence of the concrete composition, of the fission product deposition and of the thermal degradation of the reactor cavity concrete walls on long term thermodynamic behaviour has also been investigated

  12. A Study of Containment Sprays and Charcoal Filters for the Removal of Iodine Following a PWR Loss of Coolant Accident

    This paper summarizes a study of the radioiodine problem associated with the siting of the current generation of nuclear power stations in the United States, and compares the effectiveness of containment spray systems and charcoal filter systems for the removal of the radioiodine following a PWR loss of coolant accident. The study showed that, based on the present reactor siting criteria in the United States, the ultimate iodine removal system must provide an iodine dose reduction factor (DRF) of 13 in the first two hours and then eventually achieve a DRF of 50. This means that about 2% of the iodine need never be removed from the containment atmosphere if the other 98% is removed sufficiently fast. The performance of iodine removal systems is shown as a function of operating time and design capacity. For removal systems operated in a recirculating mode, the system's iodine removal efficiency is relatively unimportant when compared with the effect of the presence of a small quantity of a penetrating component. The slow response time of a charcoal filter system limits the maximum dose reduction factor that can be practically obtained in the first two hours to between 5 and 8. However, the fast response of a containment spray system provides the capability of achieving an iodine dose reduction factor of about 50 within the first two hours after an accident. If a small quantity of a penetrating component is present, the charcoal filter system will eventually catch up to the spray system, and both systems will approach the same dose reduction factor. (author)

  13. The consequences of the Kyshtym accident for Flora and Fauna

    Flora and fauna irradiated in areas radioactively contaminated by the Kyshtym accident accumulated the bulk of their dose more or less in the first year, with the irradiation being at its most intensive in autumn 1957 and the winter of 1957/58, when plants and many animal species were in the physically dormant state. During the ''acute'' phase the maximum doses absorbed (at a contamination level of 4 000 Ci 90 Sr/km2) were as follows (in krad): mouse-type rodents and fish 4, birch bud meristems 20, pine bud meristems 40, pine needles 80, dormant leaf buds and gramineae seeds on the soil surface 160. The main radiobiological effects appeared in the spring of 1958 and were observed for several years after; subsequently, in the presence of chronic irradiation at a low dose rate, predominantly genetic effects were observed, conifers being the most radiosensitive among the plants. Changes in the structure of herbaceous communities occurred at doses over 20 krad (1 500 Ci 90Sr/km2). In subsequent years we observed changes in the structure and numbers of fish and mouse-type rodent populations. The radioactive contamination caused an increase in the rate of mutational processes in plant and animal populations. However, for populations as a whole the increased frequency observed for most mutations (chromosome aberrations, chemical mutations) did not play a major role, since they were speedily eliminated by natural selection. No deformities of a genetic nature were found on the contaminated territory. In the 30 years since the accident the biological characteristics of the contaminated area have not differed (except for coniferous forests) from those of the surrounding regions. Natural ecosystems are very radioresistant, and extremely high doses are needed to damage them seriously and irreversibly. (author)

  14. Experience with psychological consequences of the Chernobyl nuclear plant accident

    The paper describes the image of radiation menance. Basic differences in image parameters are revealed for some population groups. The psychological levels of the image are regarded as psychological phenomena. Some specific psychological consequences of mental regression are outlined in the paper

  15. About some regularities consequences of accidents at NPP

    In the article are considered the principal reasons of differences in observed and calculation frequencies of emergency events in complex technological systems, including NPP. Analyzed simplification inherent in the probabilistic model of work of the reactor. The results of application of power-law probability distribution are presented for the estimation of consequences of catastrophes in complex and dangerous technologies

  16. One decade after Chernobyl: Summing up the consequences of the accident. Poster presentations

    The consequences attributed to the disastrous accident that occurred at the Chernobyl nuclear power plant on 26 April 1986 have been subjected to extensive scientific examination; however, they are still viewed with widely differing perspectives. It is fitting then that, ten years after the accident, the European Commission (EC), the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO) should jointly sponsor an international conference to review the consequences of the accident and to seek a common and conclusive understanding of their nature and magnitude. The International Conference on One Decade after Chernobyl: Summing up the Consequences of the Accident was held at the Austria Center, Vienna, on 8-12 April 1996. To facilitate the discussions of the Conference, background papers were prepared for the Technical Symposium by teams of scientists from around the world, who collaborated over a period of months to ascertain, consolidate and present the current state of knowledge in six key areas: clinically observed effects; thyroid effects; long term health effects; other health related effects; consequences for the environment; and the consequences in perspective: prognosis for the future. A background paper on the social, economic, institutional and political impact of the accident was prepared by Belarus, the Russian Federation and Ukraine. The conclusions of the Forum on Nuclear Safety Aspects served as a background paper on this topic

  17. One decade after Chernobyl: Summing up the consequences of the accident. Poster presentations

    The consequences attributed to the disastrous accident that occurred at the Chernobyl nuclear power plant on 26 April 1986 have been subjected to extensive scientific examination; however, they are still viewed with widely differing perspectives. It is fitting then that, ten years after the accident, the European commission (EC), the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO) should jointly sponsor an international conference to review the consequences of the accident and to seek a common and conclusive understanding of their nature and magnitude. The International Conference on One Decade after Chernobyl: Summing up the Consequences of the Accident was held at the Austria Center, Vienna, on 8-12 April 1996. To facilitate the discussions of the Conference, background papers were prepared for the Technical Symposium by teams of scientists from a round the world, who collaborated over a period of months to ascertain, consolidate and present the current state of knowledge in six key areas: clinically observed effects; thyroid effects; long term health effects; other health related effects; consequences for the environment; and the consequences in perspective: prognosis for the future. A background paper on the social, economic, institutional and political impact of the accident was prepared by Belarus, the Russian Federation and Ukraine. The conclusions of the Forum on Nuclear Safety Aspects served as a background paper on this topic. Refs, figs, tabs

  18. Help guides for post-accident consequence management: farm activities and exiting the emergency phase

    After having recalled the main actions foreseen in the PPIs (plans particuliers d'intervention, intervention specific plans) in case of radionuclide release in the environment after a nuclear accident, i.e. sheltering and ingestion of steady iodine, and also indicated the different phases of consequence management (preparation, emergency and post-accident phases), this report describes and comments the contents of two guides published by the IRSN (the French Radioprotection and Nuclear Safety Institute) and dealing with the management of post-accident consequences. The first one is a guide to aid to decision-making for the management of the agricultural sector in case of nuclear accident, and the second one is a guide for the preparation of the end of the emergency phase in which actions to be performed during the first week after the end of accidental releases are described

  19. A study of core melting phenomena in reactor severe accident of PWR

    Jeun, Gyoo Dong; Park, Shane; Kim, Jong Sun; Kim, Sung Joong [Hanyang Univ., Seoul (Korea, Republic of); Kim, Jin Man [Korea Maritime Univ., Busan (Korea, Republic of)

    2001-03-15

    In the 4th year, SCDAP/RELAP5 best estimate input data obtained from the TMI-2 accident analysis were applied to the analysis of domestic nuclear power plant. Ulchin nuclear power plant unit 3, 4 were selected as reference plant and steam generator tube rupture, station blackout SCDAP/RELAP5 calculation were performed to verify the adequacy of the best estimate input parameters and the adequacy of related models. Also, System 80+ EVSE simulation was executed to study steam explosion phenomena in the reactor cavity and EVSE load test was performed on the simplified reactor cavity geometry using TRACER-II code.

  20. Definition of loss-of-coolant accident radiation source. [PWR; BWR

    1978-02-01

    Meaningful qualification testing of nuclear reactor components requires a knowledge of the radiation fields expected in a loss-of-coolant accident (LOCA). The overall objective of this program is to define the LOCA source terms and compare these with the output of various simulators employed for radiation qualification testing. The basis for comparison will be the energy deposition in a model reactor component. The results of the calculations are presented and some interpretation of the results given. The energy release rates and spectra were validated by comparison with other calculations using different codes since experimental data appropriate to these calculations do not exist.

  1. The influence of seasonal conditions on the radiological consequences of a nuclear accident

    The impact of an accidental release of radioactivity to the environment can be strongly influenced by prevailing environmental conditions. Thus, potential variations in accident consequences caused by variable seasonal, meteorological or climatic conditions are of significance to the development and application of protective measures and emergency response plans. These proceedings present the results of a workshop organized by the NEA to examine such aspects of emergency response to a nuclear accident

  2. OFFSITE RADIOLOGICAL CONSEQUENCE CALCULATION FOR THE BOUNDING MIXING OF INCOMPATIBLE MATERIALS ACCIDENT

    This document quantifies the offsite radiological consequence of the bounding mixing of incompatible materials accident for comparison with the 25 rem Evaluation Guideline established in Appendix A of DOE-STD-3009. The bounding accident is an inadvertent addition of acid to a waste tank. The calculated offsite dose does not challenge the Evaluation Guideline. Revision 4 updates the analysis to consider bulk chemical additions to single shell tanks (SSTs)

  3. Accident on the Chernobyl nuclear power plant. Getting over the consequences and lessons learned

    The book is devoted to the 20 anniversary of the accident on the 4th Power Unit of the Chernobyl NPP. The power plant construction history, accident reasons, its consequences, the measures on its liquidation are represented. The current state of activity on the Chernobyl power unit decommission, the 'Shelter' object conversion into the ecologically safe system is described. The future of the Chernobyl NPP site and disposal zone is discussed

  4. Consequences of tractor accidents in the agriculture in Republic of Macedonia

    Dimitrovski, Zoran

    2008-01-01

    In this paper are the results from the research of the consequences of tractor accidents in the agriculture in Republic of Macedonia. During the research from 1999 till 2003, 610 people have been injured in Republic of Macedonia in agricultural production, and the tractors have been the main reason. 544 people have been injured in tractor traffic accidents and 66 have been injured during tractor operating in agricultural condition. From the total number, 101 people have died during this perio...

  5. Consequences of the Chernobyl accident for reindeer husbandry in Sweden

    Gustaf Åhman

    1990-09-01

    Full Text Available Large parts of the reindeer hearding area in Sweden were contaminated with radioactive caesium from the Chernobyl fallout. During the first year after the accident no food with activity concentrations exceeding 300 Bq/kg was allowed to be sold in Sweden. This meant that about 75% of all reindeer meat produced in Sweden during the autumn and winter 1986/87 were rejected because of too high caesium activités. In May 1987 the maximum level for Cs-137 in reindeer, game and fresh-water fish was raised to 1500 Bq/kg. During the last two year, 1987/88 and 1988/89, about 25% of the slaughtered reindeer has had activities exceeding this limit. The effective long-time halflife or radiocaesium in reindeer after the nuclear weapon tests in the sixties was about 7 years. If this halflife is correct also for the Chernobyl fallout it will take about 35 years before most of the reinder in Sweden are below the current limit 1500 Bq/kg in the winter. However, by feeding the animals uncontaminated food for about two months, many reindeer can be saved for human consumption.

  6. Reactor accident at the Chernobyl nuclear power plant-Block 4. Effects, countermeasures and consequences

    The findings of the Summary Report on the Chernobyl accident issued by IAEA in September 1986 (International Nuclear Safety Advisory Group (INSAG): Summary Report on the Post-Accident Review Meeting on the Chernobyl Accident. Safety Series No. 78-INSAG-1 Vienna, International Atomic Energy Agency (IAEA). Sept. 1986) are updated, reviewing more recent publications providing more complete information on the events both within and outside the plant. The available information on the resulting radioactive pollution of agriculture and the food chain is discussed considering also the consequences for the future in comparison with the other sources of radioactivity in the environment. 21 refs.; 3 figs.; 3 tabs

  7. ASSESSMENT OF THE FUKUSIMA NUCLEAR POWER PLANT ACCIDENT CONSEQUENCES BY THE POPULATION IN THE FAR EAST

    G. V. Arkhangelskaya

    2012-01-01

    Full Text Available The article analyzes the attitude of the population in the five regions of the Far East to the consequences of the accident at the Fukushimai nuclear power plant, as well as the issues of informing about the accident. The analysis of public opinion is based on the data obtained by anonymous questionnaire survey performed in November 2011. In spite of the rather active informing and objective information on the absence of the contamination, most of the population of the Russian Far East believes that radioactive contamination is presented in the areas of their residence, and the main cause of this contamination is the nuclear accident in Japan.

  8. Assessment of radiation consequences of cabins in a nuclear accident of the nuclear ship

    The author discussed about the spread routes of radioactive nuclides from reactor cabin to other cabins and their distributions in these cabins. Methods and formulas to estimate radioactivities of nuclides and doses received by crews in cabins were established. The radiation consequences of cabins in a nuclear accident was quantified and evaluated. The assessments indicates that the consequences of cabins is light and the doses to the staff will not exceed the dose limits prescribed in standards in a design basis accident, and the consequences of cabins is serious and the doses to the staff will exceed the dose limits prescribed in standards in serious accident. Some suggestions on emergency management and radiation protection were given

  9. Estimates of the financial consequences of nuclear-power-reactor accidents

    This report develops preliminary techniques for estimating the financial consequences of potential nuclear power reactor accidents. Offsite cost estimates are based on CRAC2 calculations. Costs are assigned to health effects as well as property damage. Onsite costs are estimated for worker health effects, replacement power, and cleanup costs. Several classes of costs are not included, such as indirect costs, socio-economic costs, and health care costs. Present value discounting is explained and then used to calculate the life cycle cost of the risks of potential reactor accidents. Results of the financial consequence estimates for 156 reactor-site combinations are summarized, and detailed estimates are provided in an appendix. The results indicate that, in general, onsite costs dominate the consequences of potential accidents

  10. RADIOLOGICAL AND MEDICAL CONSEQUENCES OF THE CHERNOBYL ACCIDENT

    V. G. Bebeshko

    2012-01-01

    Full Text Available From the position of a 25-years’ experience to overcome the health effects of Chernobyl the dynamics of the radiation environment, the first summarizing at the international level (1988, the results of completed research and practical monitoring are analyzed. Cohort of acute radiation syndrome (ARS survivors under medical observation at the S.I. "Research Center for Radiation Medicine of the National Academy of Medical Sciences of Ukraine" is the largest. Within the 25 years the functional state of the major organs and body systems, and metabolic homeostasis for this category of persons were studied, a comprehensive assessment of their health, mental and physical performance were given, and risk factors and peculiarities of stochastic and non-stochastic pathology courses were identified, as well as a system of rehabilitation patients after ARS was developed. ARS survivors are suffering from chronic diseases of internal organs and systems (from 5-7 to 10-12 diagnoses at the same time. A correlation between acute radiation effects and specific HLA phenotypes were revealed. The dynamics of the immune system recovery after irradiation was studied. The role and prognostic value of telomere length and programmed cell death of lymphocytes in the formation of the cellular effects of ionizing radiation were determined for the first time. Differences between spontaneous and radiation-induced acute myeloid leukemias were found. Dose-dependent neuropsychiatric, neurophysiological, neuropsychological and neuroimaging deviations were identified after irradiation at doses above 0.3 Sv. It was shown that the lymphocytes of Chernobyl clean-up workers with doses 350 – 690 mGy can induce "the bystander effect" in the non-irradiated cells even after 19 years after exposure. The rates of cancer incidence and mortality of victims, the lessons and key problems to be solved in the third decade after the Chernobyl accident are considered.

  11. Economic consequences of major accidents in the industrial plants: The case of a nuclear power plant

    These last years, newspapers head-lines have reported various accidents (Mexico City, Bhopal, Chernobyl, ...) which have drawn attention to the fact that the major technological risk is now a reality and that, undoubtedly, industrial decision-makers ought to integrate it into their preoccupations. In addition to the sometimes considerable human problems such accidents engender, their economic consequences may be such that they become significant on a national or even international scale. The aim of the present paper is to analyse these economic effects by using the particular context of a nuclear power plant. The author has deliberately limited his subject to the consequences of a major accident, that is to say a sudden event, theoretically unforeseen and beyond man's control. The qualification major means an accident of which the consequences extend far beyond the industrial plant itself. The direct and indirect economic consequences are analysed from the responsibility point of view as well as from the national and international community's point of view. A paragraph explains how the coverage of the costs can rely on the cooperation of a number of parties: responsible company, state, insurers, customers, etc. The study is broadly based on the experience resulting from the two major accidents which happened in the nuclear industry these last years (Three Mile Island in 1979 and Chernobyl in 1986) and makes use of more theoretical considerations, for example in the field of the economic evaluation of human life. (author). 58 refs, 2 figs, 12 tabs

  12. Application of an Expert System on a PWR-Plant Simulator for the Control of an SG-Tube Rupture Accident

    Three mile accident in 1979, and Chernobyl accident in 1986 had a quite an impact for the re-evaluation of the International nuclear programs which caused a delay in those programs especially those for the developing countries. At the same time, developed countries pursued the review and improvement of methods to overcome the causes of such accidents. The basic cause of both accidents was the carelessness and panic of operators because of the divergence nature of information flows during the time course of the accidents. An example of a new technology adopted is the use of expert systems for such cases. In this study, two types of simulators are introduced namely AP-600, and PCTRAN-U2LP PWR simulators. Also an introduction to the concept of expert systems is presented. A steam generator tube rupture accident is simulated to derive some production rules to be incorporated into the expert system shell (EXYS-Shell) so to help the operator to maneuver the plant during the SG-tube rupture accident by introducing to him the appropriate actions for control. (authors)

  13. Thermal-hydraulic analysis best-estimate of an accident in the containment a PWR-W reactor with GOTHIC code using a 3D model detailed; Analisis termo-hidraulico best-estimate de un accidente en contencion de un reactor PWR-W con el codigo GOTHIC mediante un modelo 3D detallado

    Bocanegra, R.; Jimenez, G.

    2013-07-01

    The objective of this project will be a model of containment PWR-W with the GOTHIC code that allows analyzing the behavior detailed after a design basis accident or a severe accident. Unlike the models normally used in codes of this type, the analysis will take place using a three-dimensional model of the containment, being this much more accurate.

  14. The reaction between iodine and organic coatings under severe PWR accident conditions. An experimental parameter study

    Hellmann, S.; Funke, F.; Greger, G.U.; Bleier, A.; Morell, W. [Siemens AG, Power Generation Group, Erlangen (Germany)

    1996-12-01

    An extensive experimental parameter study was performed on the deposition and on the resuspension kinetics in the reaction system iodine/organically coated surfaces. Both reactions in the gas phase and in the liquid phase were investigated and kinetic rate constants suitable for modelling were derived. Previous experimental studies on the reaction of iodine with organic coated surfaces were mostly limited to temperatures below 100{sup o}C. Thus, this parameter study aims at filling a gap and providing kinetic data on heterogeneous reactions with organic surfaces in the accident-relevant temperature range of 100-160{sup o}C. Two types of laboratory experiments carried out at Siemens/KWU using coatings representative for German power plants (epoxy-tape paint), namely gas phase tests and liquid phase tests. (author) 6 figs., 6 tabs., 5 refs.

  15. Application of probabilistic safety analysis (PSA) approach to structuring accident mitigation systems of a PWR

    The safety evaluation technology of PWRs has already been improved substantially because of large-scale safety verification tests and improvement of accuracy in analyses. However, for structuring accident mitigation systems (AMS), the selection of appropriate systems from various AMS candidates mainly depends on engineering judgements by design engineers. So systematic designing process should be established. Reliability of each AMS forms the basis for reliability of safety plant design as a whole. Therefore, explicitly understanding characteristics of each AMS's reliability is very important for safety design. Based on these facts as a background, the limitation of improving reliability by strengthening redundancy of AMS mainly consisting of active components was clarified by applying PSA. At the same time, reliability and other characteristics of AMS mainly consisting of passive components were also clarified with PSA. Through these studies, it is proved that the application of PSA for structuring AMS is effective. (author)

  16. Impact evaluation of the accident with release of a PWR coolant. Case study: Angra 3

    It was postulated in the cooling system, a LOCA where was lost 431 m3 of coolant. The inventory was 1.87 x 1010 Bq/m3 of tritium, 2.22 x 107 Bp/m3 of cobalt and 3.48 x 108 Bq/m3 of cesium and was launched near tue Itaorna beach, Angra dos Reis, RJ, Brazil. By applying the model in the proposed scenery (Angra 1 and 2 functioning and Angra 3 with variation of water taking and discharge with a progressive reduction after the accident), the dilution of specific activity of the radionuclides reached inferior values after 22 hours, to the reference values. After 54 hours, the levels of radionuclides, in the indirect influence are already below the minimum values of activity detected by the laboratory of environmental monitoring of the CNAAA

  17. The reaction between iodine and organic coatings under severe PWR accident conditions. An experimental parameter study

    An extensive experimental parameter study was performed on the deposition and on the resuspension kinetics in the reaction system iodine/organically coated surfaces. Both reactions in the gas phase and in the liquid phase were investigated and kinetic rate constants suitable for modelling were derived. Previous experimental studies on the reaction of iodine with organic coated surfaces were mostly limited to temperatures below 100oC. Thus, this parameter study aims at filling a gap and providing kinetic data on heterogeneous reactions with organic surfaces in the accident-relevant temperature range of 100-160oC. Two types of laboratory experiments carried out at Siemens/KWU using coatings representative for German power plants (epoxy-tape paint), namely gas phase tests and liquid phase tests. (author) 6 figs., 6 tabs., 5 refs

  18. R and D relative to the serious accidents in the PWR type reactors: assessment and perspectives

    This document presents the current state of the research relative to the grave accidents realized in France and abroad. It aims at giving the most exhaustive possible and objective vision of this original field of research. He allows to contribute to the identification and to the hierarchical organization of the needs of R and D, this hierarchical organization in front of, naturally, to be completed by a strong lighting on needs in terms of safety analyses associated with the different risks and the physical phenomena, in particular with the support of probability evaluations of safety level 2, whose the level of sharpness must be sufficient not to hide, by construction, physical phenomena of which the limited knowledge leads to important uncertainties. Let us note that neither the safety analyses, nor the E.P.S. 2 are presented in this document. This report presents the physical phenomena which can arise during a grave accident, in the reactor vessel and in the reactor containment, their chain and the means allowing to ease the effects. The corresponding scenarios are presented to the chapter 2. The chapter 3 is dedicated to the progress of the accident in the reactor vessel; the degradation of the core in reactor vessel (3.1), the behavior of the corium in bottom of reactor vessel (3.2) the break of the reactor vessel (3.3) and the fusion in pressure (3.4) are thus handled there. The chapter 4 concerns the phenomena which can lead to a premature failure of the containment, namely the direct heating of gases of the containment (4.1), the hydrogen risk (4.2) and the vapor explosion (4.3). The phenomenon which can lead to a delayed failure from the containment, namely the interaction corium-concrete, is approached on the chapter 5. The chapter 6 is dedicated to the problems connected to the keeping back and to the corium cooling in reactor vessel and out of reactor vessel, namely the keeping back in reactor vessel by re-flooding of the primary circuit or by re

  19. Effect of water injection on hydrogen generation during severe accident in PWR

    TAO Jun; CAO Xuewu

    2009-01-01

    Effect of water injection on hydrogen generation during severe accident in a 1000 MWe pressurized water reactor was studied.The analyses were carried out with different water injection rates at different core damage stages.The core can be quenched and accident progression can be terminated by water injection at the time before cohesive core debris is formed at lower core region.Hydrogen generation rate decreases with water injection into the core at the peak core temperature of 1700 K,because the core is quenched and reflooded quickly.The water injection at the peak core temperature of 1900 K,the hydrogen generation rate increases at low injection rates of the water,as the core is quenched slowly and the core remains in uncovered condition at high temperatures for a longer time than the situation of high injection rate.At peak core temperature of 2100-2300 K,the Hydrogen generation rate increases by water injection because of the steam serving to the high temperature steam-starved core.Hydrogen generation rate increases significantly after water injection into the core at peak core temperature of 2500 K because of the steam serving to the relocating Zr-U-O mixture.Almost no hydrogen generation can be seen in base case after formation of the molten pool at the lower core region.However,hydrogen is generated if water is injected into the molten pool,because steam serves to the crust supporting the molten pool.Reactor coolant system (RCS) depressurization by opening power operated relief valves has important effect on hydrogen generation.Special attention should be paid to hydrogen generation enhancement caused by RCS depressurization.

  20. Influence of the aquatic environment on release behavior of fission products. Experimental study of aerosol emission during a PWR severe accident

    This experimental study concerns the consequences on the environment of a PWR severe accident. A preliminary bibliographical survey has been undertaken in order to determine the elements to study, and the experimental protocols to use. 4 fission products (Cs, Sr, Ru, Ce) and 3 structure materials (Ag, Fe, In) have been chosen. Tests of cations (Cs+) retention by soils have been done. They showed up the great variability of the results according to experimental procedures (contact time, agitation, solid phase concentration...). The adoption of a standard procedure which would enable the different results comparison is suggested. Then, the dissolution of powders from the 7 elements has been studied in different solutions. Two different phenomena occurs for some elements. We observed a partial dissolution of Ag, In and Ce, according to solution compositions, but fine particles or colloid presence may contribute to the solution total activity. The Cs dissolution is more important but never complete, because of an amalgam formation during calcination with structure materials. Ru doesn't dissolve, and fine particles presence is the reason of solution activity. Soils retention is minimal for the elements that are neutral, like Ru, and maximal for cations, especially Cs+. High contents of organic matter and clay in soils enhance retention. Thanks to the new theoretical source term values, plurielementary aerosols fabrication has debuted. The installation we used (Inducing oven with an aerosol maturation enclosure) allows the obtention of temperatures as high as 2800 - 30000 C and the volatilization of 13 elements between the 16 presents. Suggestions are done that may increase the Ru, Ce and Zr emissions

  1. A study on the pressurized water reactor (PWR) containment response analysis methodologies for postulated severe accident

    The present study contains two major parts: one is the treatment of uncertainties involved in the current APET and the other is the importance analysis of the APET uncertainty inputs. A clear disadvantage of the expert opinion polling process approach for uncertainty analysis of the current probabilistic risk assessment (PRA) is that the sufficient robustness in the final results may not be attained against the ambiguity of the information upon which the experts base their judgement or the judgmental uncertainty arising under various imprecise and incomplete information. For the treatment of such type of uncertainty, a new approach based on fuzzy set theory is proposed. Then its potential use to the uncertainty analysis of the current PRA is proved through an analysis of accident progression event tree (APET). As a product, a formal procedure with computational algorithms suitable for application of the fuzzy set theory to the APET analysis is provided. Comparing with the uncertainty analysis results obtained by the statistical approach currently used in PRA, the present approach has several major advantages: Firstly, it greatly enhances the robustness in the final results of APET uncertainty analysis by modeling the judgmental uncertainty that arises in the probabilistic quantification of APET top events. Secondly, the modeling of APET uncertainty analysis is far more convenient because of the nonprobabilistic features of fuzzy probabilities used for uncertainty quantification of the APET top events. Thirdly, the APET model can easily be operated by means of a well defined formal propagation logic of fuzzy set theory without going through a tedious sampling procedure. Finally, the fuzzy outcomes provide at least as much information as the existing methods based on the statistical approach. Thus, the present approach can be used as a valuable alternative approach to uncertainty analysis used in the current PRA. Two importance measures for the importance analysis of

  2. Formation of decontamination cost calculation model for severe accident consequence assessment

    In previous studies, the authors developed an index “cost per severe accident” to perform a severe accident consequence assessment that can cover various kinds of accident consequences, namely health effects, economic, social and environmental impacts. Though decontamination cost was identified as a major component, it was taken into account using simple and conservative assumptions, which make it difficult to have further discussions. The decontamination cost calculation model was therefore reconsidered. 99 parameters were selected to take into account all decontamination-related issues, and the decontamination cost calculation model was formed. The distributions of all parameters were determined. A sensitivity analysis using the Morris method was performed in order to identify important parameters that have large influence on the cost per severe accident and large extent of interactions with other parameters. We identified 25 important parameters, and fixed most negligible parameters to the median of their distributions to form a simplified decontamination cost calculation model. Calculations of cost per severe accident with the full model (all parameters distributed), and with the simplified model were performed and compared. The differences of the cost per severe accident and its components were not significant, which ensure the validity of the simplified model. The simplified model is used to perform a full scope calculation of the cost per severe accident and compared with the previous study. The decontamination cost increased its importance significantly. (author)

  3. Cohort formation for epidemiological study of medical consequences of the Chernobyl accident

    Belarus State Registry of the Chernobyl-affected population contains information about 276 000 residents of the Republic of Belarus exposed due to the Chernobyl NPP accident. Evidently, the population who lived in the evacuation zone was exposed mostly to radiation and also people participating in the liquidation of the Chernobyl accident consequences (emergency workers) within this zone in early post accident period of the catastrophe. Taking into account this criterion, we singled out the group out of all data files including all people who stayed in the evacuation zone not later than on May 31, 1986. The total number of the group made up 39 548 people including 4251 people who were under 18 at the moment of the accident. By preliminary estimation the number of person-years taking into account the deceased and left out of observation made up at the beginning of 2007- 735 600. During the period since 1986 there was detected 2671 cases of malignant tumors in the cohort and among people who were children and adolescents in 1986 there was registered 106 cases of malignant tumors (82% -thyroid cancer). Among 7483 of the deceased, malignant tumors is the cause of death at 1260 people. At present the real number of alive and remained subjects under observation makes up 25359 people including 2321 people who were under 18 at the moment of the accident. This group will form the base for further prospective research aiming at assessment of medical consequences of the Chernobyl NPP accident. (author)

  4. Investigations related to the chemical behaviour of methyl iodide at severe PWR-accidents

    The decomposition velocity of methyl iodide in aqueous solutions of boric acid has been measured at temperatures up to 423 K and at chemical conditions which are expected to exist in the sumpwater pool during a severe reactor accident. The decomposition was due only to hydrolysis which increased by the expected amount at high temperature. No influence of the cooling water additives was observed. Treatment of the available kinetic data indicated that the influence of polluting material expectedly present in the sump is likely to be negligible too. A possible exception may be the enhancement of the decomposition rate by particulate and dissolved silver. The resistance of methyl iodide to gas phase decomposition by steam and oxygen at 423 K was investigated and only slow decomposition in the order of 10-7/s observed which is explained by reaction with steel surfaces. Neither gas phase oxidation nor hydrolysis occur at this temperature. The resistance to oxidation is of kinetic nature. Gas phase hydrolysis is not possible due to thermodynamics. This was confirmed by the observed gas phase formation of methyl iodide from hydrogen iodide and methanol at 423 K. The kinetics of this reaction are best explained by two parallel reactions, one of second order with a kinetic constant of 1.25 x 10-5/kPa s, and one of third order under action of steam with a constant of 2 x 10-6/kPa2 s. (orig./HP)

  5. Investigation program on PWR-steel-containment behavior under accident conditions

    This report is a first documentation of the KfK/PNS activities and plans to investigate the behaviour of steel containments under accident conditions. The investigations will deal with a free standing spherical containment shell built for the latest type of a German pressurized water reactor. The diameter of the containment shell is 56 m. The minimum wall thickness is 38 mm. The material used is the ferritic steel 15MnNi63. According to the actual planning the program is concerned with four different problems which are beyond the common design and licensing practice: Containment behavior under quasi-static pressure increase up to containment failure. Containment behavior under high transient pressures. Containment oscillations due to earthquake loadings; consideration of shell imperfections. Containment buckling due to earthquake loadings. The investigation program consists of both theoretical and experimental activities including membrane tests allowing for very high plastic strains and oscillation tests with a thin-walled, high-accurate spherical shell. (orig.)

  6. An assessment of the consequences of a research reactor credible accident release

    An analysis of the consequences of a serious credible accident, a coolant flow blockage accident (CFBA) of the Greek research reactor (GRR) is presented. GRR, a 5 MW swimming pool type reactor, is located within Athens the largest population centre of Greece concentrating 32% of its population. To estimate the source term 31 isotopes are taken into consideration and conservative figures of fission product release are adopted. To estimate the CFBA consequences a CRAC2 consequence model version is used. Doses and individual cancer risk from exposure to the passing radioactive cloud are estimated up to a distance of 20km from the reactor site. Collective exposure and latent health effects due to initial exposure and chronic exposure from inhalation of resuspended radionuclides and exposure to groundshine from contaminated ground are estimated for the total Athens area of 3081000 inhabitants. The results of the analysis suggest that the CFBA consequences are not significant. 10 refs., 9 figs., 2 tabs. (Author)

  7. Reactor safety study. An assessment of accident risks in U. S. commercial nuclear power plants. Appendix XI. Analysis of comments on the draft WASH-1400 report. [PWR and BWR

    1975-10-01

    Information is presented concerning comments on reactor safety by governmental agencies and civilian organizations; reactor safety study methodology; consequence model; probability of accident sequences; and various accident conditions.

  8. Critical analysis of accident scenario and consequences modelling applied to light-water reactor power plants for accident categories beyond the design basis accident (DBA)

    A critical analysis and sensitivity study of the modelling of accident scenarios and environmental consequences are presented, for light-water reactor accident categories beyond the standard design-basis-accident category. The first chapter, on ''source term'' deals with the release of fission products from a damaged core inventory and their migration within the primary circuit and the reactor containment. Particular attention is given to the influence of engineering safeguards intervention and of the chemical forms of the released fission products. The second chapter deals with their release to the atmosphere, transport and wet or dry deposition, outlining relevant partial effects and confronting short-duration or prolonged releases. The third chapter presents a variability analysis, for environmental contamination levels, for two extreme hypothetical scenarios, evidencing the importance of plume rise. A numerical plume rise model is outlined

  9. Probabilistic safety assessment (PSA) for serious accident consequences of nuclear power plant

    An analysis method for the PSA of the serious accident consequences of nuclear power plant was introduced and the operation rules, i.e. U5 rules on avoiding the containment failure of the nuclear power plant was put forward by the France. When the nuclear power plant happened core meltdown accident and caused the raising of internal pressure due to the spray failure of the containment, the U5 rules will make the gas inside the containment releasing to the environment through sand-bed filter, then the pressure in the containment will be relieved. The practical calculation was based on the being built nuclear power plant as the chief source. The effect of U5 rules on the serious accident consequences of the nuclear power plant was analysed. In conclusion, some valuable results were given

  10. Accident consequence studies for large fast breeder reactor containments built of concrete or steel

    A numerical analysis of accident consequences in a fast breeder reactor of commercial size after complete loss-of-heat-sink was performed, using the CONTAIN code. Two containment types were studied, which differ in the material used for shielding, support and confinement structures. It was found that the replacement of concrete as principal construction material by steel offers a significant potential for consequence mitigation in terms of thermal and pressure loads and of retention capability

  11. PWR rod ejection accident: uncertainty analysis on a high burn-up core configuration

    Le Pallec, J.C.; Studer, E.; Royer, E. [CEA Saclay, Direction de l' Energie Nucleaire, Service d' Etudes de Reacteurs et de Modelisation Avancee (DEN/SERMA), 91 - Gif sur Yvette (France)

    2003-07-01

    With the increasing of the discharge burn-up assembly, the rod ejection accident (REA) methodology based on the analyse of the hot spot from a decoupling methods of calculation does not allow to ensure the respect of safety criteria. The main reason is that the irradiated fuel certainly less solicited thermally is in the other hand more sensitive to a transient due to a rod ejection. Thus, the hot spot is not necessarily the sensitive point of the core. In the framework of high burn-up configurations, a new methodology tends to replace the former. It characterizes by the use of a best-estimate 3-dimensional modelling: coupling of the thermal hydraulics and neutronics, taking in account fuel properties depending on irradiation. To ensure the conservatism of the modelling response, this new approach has to be followed by an uncertainties analysis. Inputs from the benchmark RIA TMI-1 conducted by IRSN (France), NRC (United State of America) and KI (Russian) are used to perform a first analysis. The response of the modelling is the enthalpy deposited in an assembly. The analysis is based on the Design of Experiments (DoE) that permits to measure the weight of the main parameters and their interactions on the response. These last cannot be disregarded because they represent up to 20% of the penalizing uncertainty. This study shows that the main fuel modifications due to irradiation (radial power distribution, thermal properties degradation) have to be taken into account in a realistic thermal modelling during a strong transient.

  12. Consequences of Chernobyl accident for Poland: Retrospective assessment after 10 years

    The regional contamination in Poland after Chernobyl accident has been presented. On this base the biological and medical consequences have been discussed. The neonatal mortality as well as cancer frequency for selected regional population in Poland have been analysed during the last decade. 10 figs, 20 tabs

  13. Environmental decision support system on base of geoinformational technologies for the analysis of nuclear accident consequences

    The report deals with description of the concept and prototype of environmental decision support system (EDSS) for the analysis of late off-site consequences of severe nuclear accidents and analysis, processing and presentation of spatially distributed radioecological data. General description of the available software, use of modem achievements of geostatistics and stochastic simulations for the analysis of spatial data are presented and discussed

  14. Patterns and consequences of inadequate sleep in college students: substance use and motor vehicle accidents.

    Taylor, Daniel J; Bramoweth, Adam D

    2010-06-01

    We examined college sleep patterns and consequences using a cross-sectional design. We found that students get insufficient sleep and frequently use medication and alcohol as sleep aids, use stimulants as alertness aids, and fall asleep at the wheel, or have motor vehicle accidents due to sleepiness. Future studies should focus on effective interventions for sleep in college students. PMID:20472221

  15. Procedures Guide for Structural Expert Judgement in Accident Consequence Modelling (invited paper)

    A protocol is outlined for using structured expert judgement to generate uncertainty data for uncertainty analyses. The use of performance based weighting as an instrument to enable optimisation of the aggregated experts' assessments is emphasised. Examples are shown from the EC/USNRC joint study on Probabilistic Accident Consequence Uncertainty Analysis. (author)

  16. Application of GIS in prediction and assessment system of off-site accident consequence for NPP

    The assessment and prediction software system of off-site accident consequence for Guangdong Nuclear Power Plant (GNARD2.0) is a GIS-based software system. The spatial analysis of radioactive materials and doses with geographic information is available in this system. The structure and functions of the GNARD system and the method of applying ArcView GIS are presented

  17. The Fukushima Daiichi Accident. Technical Volume 4/5. Radiological Consequences. Annexes

    The Fukushima Daiichi Accident consists of a Report by the IAEA Director General and five technical volumes. It is the result of an extensive international collaborative effort involving five working groups with about 180 experts from 42 Member States with and without nuclear power programmes and several international bodies. It provides a description of the accident and its causes, evolution and consequences, based on the evaluation of data and information from a large number of sources available at the time of writing. The Fukushima Daiichi Accident will be of use to national authorities, international organizations, nuclear regulatory bodies, nuclear power plant operating organizations, designers of nuclear facilities and other experts in matters relating to nuclear power, as well as the wider public. The set contains six printed parts and five supplementary CD-ROMs. Contents: Report by the Director General; Technical Volume 1/5, Description and Context of the Accident; Technical Volume 2/5, Safety Assessment; Technical Volume 3/5, Emergency Preparedness and Response; Technical Volume 4/5, Radiological Consequences; Technical Volume 5/5, Post-accident Recovery; Annexes. The Report by the Director General is available separately in Arabic, Chinese, English, French, Russian, Spanish and Japanese

  18. The accident at the Chernobyl' nuclear power plant and its consequences

    The material is taken from the conclusions of the Government Commission on the causes of the accident at the fourth unit of the Chernobyl' nuclear power plant and was prepared by a team of experts appointed by the USSR State Committee on the Utilization of Atomic Energy. It contains general material describing the accident, its causes, the action taken to contain the accident and to alleviate its consequences, the radioactive contamination and health of the population and some recommendations for improving nuclear power safety. 7 annexes are devoted to the following topics: water-graphite channel reactors and operating experience with RBMK reactors, design of the reactor plant, elimination of the consequences of the accident and decontamination, estimate of the amount, composition and dynamics of the discharge of radioactive substances from the damaged reactor, atmospheric transport and radioactive contamination of the atmosphere and of the ground, expert evaluation and prediction of the radioecological state of the environment in the area of the radiation plume from the Chernobyl' nuclear power station, medical-biological problems. A separate abstract was prepared for each of these annexes. The slides presented at the post-accident review meeting are grouped in two separate volumes

  19. Probabilistic accident consequence uncertainty analysis: Food chain uncertainty assessment. Volume 1: Main report

    This volume is the first of a two-volume document that summarizes a joint project conducted by the US Nuclear Regulatory Commission and the European Commission to assess uncertainties in the MACCS and COSYMA probabilistic accident consequence codes. These codes were developed primarily for estimating the risks presented by nuclear reactors based on postulated frequencies and magnitudes of potential accidents. This document reports on an ongoing project to assess uncertainty in the MACCS and COSYMA calculations for the offsite consequences of radionuclide releases by hypothetical nuclear power plant accidents. A panel of sixteen experts was formed to compile credible and traceable uncertainty distributions for food chain variables that affect calculations of offsite consequences. The expert judgment elicitation procedure and its outcomes are described in these volumes. Other panels were formed to consider uncertainty in other aspects of the codes. Their results are described in companion reports. Volume 1 contains background information and a complete description of the joint consequence uncertainty study. Volume 2 contains appendices that include (1) a summary of the MACCS and COSYMA consequence codes, (2) the elicitation questionnaires and case structures for both panels, (3) the rationales and results for the panels on soil and plant transfer and animal transfer, (4) short biographies of the experts, and (5) the aggregated results of their responses

  20. Probabilistic accident consequence uncertainty analysis: Food chain uncertainty assessment. Volume 1: Main report

    Brown, J. [National Radiological Protection Board (United Kingdom); Goossens, L.H.J.; Kraan, B.C.P. [Delft Univ. of Technology (Netherlands)] [and others

    1997-06-01

    This volume is the first of a two-volume document that summarizes a joint project conducted by the US Nuclear Regulatory Commission and the European Commission to assess uncertainties in the MACCS and COSYMA probabilistic accident consequence codes. These codes were developed primarily for estimating the risks presented by nuclear reactors based on postulated frequencies and magnitudes of potential accidents. This document reports on an ongoing project to assess uncertainty in the MACCS and COSYMA calculations for the offsite consequences of radionuclide releases by hypothetical nuclear power plant accidents. A panel of sixteen experts was formed to compile credible and traceable uncertainty distributions for food chain variables that affect calculations of offsite consequences. The expert judgment elicitation procedure and its outcomes are described in these volumes. Other panels were formed to consider uncertainty in other aspects of the codes. Their results are described in companion reports. Volume 1 contains background information and a complete description of the joint consequence uncertainty study. Volume 2 contains appendices that include (1) a summary of the MACCS and COSYMA consequence codes, (2) the elicitation questionnaires and case structures for both panels, (3) the rationales and results for the panels on soil and plant transfer and animal transfer, (4) short biographies of the experts, and (5) the aggregated results of their responses.

  1. Probabilistic accident consequence uncertainty analysis -- Early health effects uncertainty assessment. Volume 1: Main report

    Haskin, F.E. [Univ. of New Mexico, Albuquerque, NM (United States); Harper, F.T. [Sandia National Labs., Albuquerque, NM (United States); Goossens, L.H.J.; Kraan, B.C.P. [Delft Univ. of Technology (Netherlands); Grupa, J.B. [Netherlands Energy Research Foundation (Netherlands)

    1997-12-01

    The development of two new probabilistic accident consequence codes, MACCS and COSYMA, was completed in 1990. These codes estimate the consequence from the accidental releases of radiological material from hypothesized accidents at nuclear installations. In 1991, the US Nuclear Regulatory Commission and the Commission of the European Communities began cosponsoring a joint uncertainty analysis of the two codes. The ultimate objective of this joint effort was to systematically develop credible and traceable uncertainty distributions for the respective code input variables. A formal expert judgment elicitation and evaluation process was identified as the best technology available for developing a library of uncertainty distributions for these consequence parameters. This report focuses on the results of the study to develop distribution for variables related to the MACCS and COSYMA early health effects models.

  2. Probabilistic accident consequence uncertainty analysis -- Late health effects uncertainty assessment. Volume 1: Main report

    Little, M.P.; Muirhead, C.R. [National Radiological Protection Board (United Kingdom); Goossens, L.H.J.; Kraan, B.C.P.; Cooke, R.M. [Delft Univ. of Technology (Netherlands); Harper, F.T. [Sandia National Labs., Albuquerque, NM (United States); Hora, S.C. [Univ. of Hawaii, Hilo, HI (United States)

    1997-12-01

    The development of two new probabilistic accident consequence codes, MACCS and COSYMA, was completed in 1990. These codes estimate the consequence from the accidental releases of radiological material from hypothesized accidents at nuclear installations. In 1991, the US Nuclear Regulatory Commission and the Commission of the European Communities began cosponsoring a joint uncertainty analysis of the two codes. The ultimate objective of this joint effort was to systematically develop credible and traceable uncertainty distributions for the respective code input variables. A formal expert judgment elicitation and evaluation process was identified as the best technology available for developing a library of uncertainty distributions for these consequence parameters. This report focuses on the results of the study to develop distribution for variables related to the MACCS and COSYMA late health effects models.

  3. Overview of Sandia National Laboratories and Khlopin Radium Institute collaborative radiological accident consequence analysis efforts

    In January, 1995 a collaborative effort to improve radiological consequence analysis methods and tools was initiated between the V.G. Khlopin Institute (KRI) and Sandia National Laboratories (SNL). The purpose of the collaborative effort was to transfer SNL's consequence analysis methods to KRI and identify opportunities for collaborative efforts to solve mutual problems relating to the safety of radiochemical facilities. A second purpose was to improve SNL's consequence analysis methods by incorporating the radiological accident field experience of KRI scientists (e.g. the Chernobyl and Kyshtym accidents). The initial collaborative effort focused on the identification of: safety criteria that radiochemical facilities in Russia must meet; analyses/measures required to demonstrate that safety criteria have been met; and data required to complete the analyses/measures identified to demonstrate the safety basis of a facility

  4. The accident at the Chernobyl' nuclear power plant and its consequences. Pt. 1. General material

    The report contains a presentation of the Chernobyl' nuclear power station and of the RBMK-1000 reactor, including its principal physical characteristics, the safety systems and a description of the site and of the surrounding region. After a chronological account of the events which led to the accident and an analysis of the accident using a mathematical model it is concluded that the prime cause of the accident was an extremely improbable combination of violations of instructions and operating rules committed by the staff of the unit. Technical and organizational measures for improving the safety of nuclear power plants with RBMK reactors have been taken. A detailed description of the actions taken to contain the accident and to alleviate its consequences is given and includes the fire fighting at the nuclear power station, the evaluation of the state of the fuel after the accident, the actions taken to limit the consequences of the accident in the core, the measures taken at units 1, 2 and 3 of the nuclear power station, the monitoring and diagnosis of the state of the damaged unit, the decontamination of the site and of the 30 km zone and the long-term entombment of the damaged unit. The measures taken for environmental radioactive contamination monitoring, starting by the assessment of the quantity, composition and dynamics of fission products release from the damaged reactor are described, including the main characteristics of the radioactive contamination of the atmosphere and of the ground, the possible ecological consequences and data on the exposure of plant and emergency service personnel and of the population in the 30 km zone around the plant. The last part of the report presents some recommendations for improving nuclear power safety, including scientific, technical and organizational aspects and international measures. Finally, an overview of the development of nuclear power in the USSR is given

  5. Proceedings of the first international conference 'The radiological consequences of the Chernobyl accident'

    Five main objectives were assigned to the EC/CIS scientific collaborative programme: improvement of the knowledge of the relationship between doses and radiation-induced health effects; updating of the arrangements for off-site emergency management response (shot- and medium term)in the even of a future nuclear accident; assisting the relevant CIS Ministries alleviate the consequences of the Chernobyl accident, in particular in the field of restoration of contaminated territories; elaboration of a scientific basis to definite the content of Community assistance programmes; updating of the local technical infrastructure, and implementation of a large programme of exchange of scientists between both Communities. The topics addressed during the Conference mainly reflect the content of the joint collaborative programme: environmental transfer and decontamination, risk assessment and management, health related issues including dosimetry. The main aims of the Conference are to present the major achievements of the joint EC/CIS collaborative research programme (1992-1995) of the consequences of the Chernobyl accident, and to promote an objective evaluation of them by the international scientific community. The Conference is taking place close to the 10th anniversary of the accident and we hope it will contribute to more objective communication of the health and environmental consequences of the Chernobyl accident, and how these may be mitigated in future. The Conference is expected to be an important milestone in the series of meetings which will take place internationally around the 10th anniversary of the nuclear accident. It also provides a major opportunity for all participants to become acquainted with software developed within the framework of the collaborative programme, namely: Geographical Information Systems displaying contamination levels and dose-commitments; Decision Support Systems for the management of contaminated territories; Decision Support Systems for

  6. Joint CEC/OECD(NEA) workshop on recent advances in reactor accident consequence assessment

    The workshop on probabilistic accident consequence assessment techniques and their applications aims at a review of the present knowledge of all the work in this field. This includes the atmospheric dispersion and deposition modelling, with comparison of the different approaches, the exposure pathways with emphasis on post-deposition processes, the health effects with emphasis on the consequences of the Hiroshima and Nagasaki data re-evaluation, the countermeasures and their economic consequences, the uncertainty analysis of the models and finally the applications of these models as aids to decision making

  7. Level of health of cleaners taking part in the Chernobyl accident consequences

    During the period of 1986-1988 about 3,000 Moldova citizens took part in Chernobyl NPP accident consequences elimination. In this article the level of morbidity, disability and mortality among Chernobyl accident consequences liquidation participants is analyzed. As a result of analysis of medical documentation and statistical data was revealed that the sickness rate among disaster fighters 2,3 times higher than general sickness rate of the population in Moldova. Disability in this category is at average of 73 per cent as opposed to the overall index for the population of Moldova - 4,4%, this means it is 17 times higher. Mortality among the participants of the accident at Chernobyl NPP is 6 times higher of general data. The participants of the breakdown elimination of Chernobyl accident consequences are equal in their right with the participants and invalids of war and with the disabled workers. Medical and social security of this group is regulated by the legislation of the Republic of Moldova

  8. Radiation health consequences after the accident of Chernobyl Nuclear Power Plant

    The sources of divergences in health consequences assessment after Chernobyl accident have been discussed. The average data about the cancer incidence in Poland have been presented. On that background the frequency of thyroid cancer, being considered as a result of iodine radionuclides exposure after Chernobyl accident in May 1986, have been performed. The great geographic differences in cancer incidence have been underlined. The observed differences between the selected group of people of different age and sex have been also discussed. 14 refs, 11 tabs, 3 figs

  9. Severe accident modeling and offsite dose consequence evaluations for nuclear power plant emergency planning

    We have investigated the roles of Firewater Addition System and Passive Flooder in ABWR severe accidents, such as LOCA and SBO. The results are apparent that Firewater System is vital in the highly unlikely situation where all AC are lost. Also in this paper, we present EPZDose, an effective and faster-than-real time code for offsite dose consequences predictions and evaluations. Illustrations with the release from our severe accident scenario show friendly and informative user's interface for supporting decision makings in nuclear emergency situations. (author)

  10. V.A. Baraboj. Chernobyl: ten years later. Medical consequences of radiation accidents

    Review of the book - Chernobyl: ten years later. Medical consequences of radiation accidents (Kiev, Chernobylinterinform, 1996) by V.A. Baraboj - is presented. The book is based on experimental data obtained by author and available data of other scientists. It is shown that experiments on rats irradiation demonstrate the same combination of symptoms as persons participated in Chernobyl accident response. Attention is paid to the dosimetric, genetic, phenotypic features of exposed persons. Contributions of chemical hazardous pollutants and psychoemotional stress to the general pattern were also accounted. The importance of the book for specialists and public is accentuated

  11. Multi-group SP3 approximation for simulation of a three-dimensional PWR rod ejection accident

    Highlights: • The multi-group SP3 method developed and implemented in PARCS for the MOX analysis. • The verifications were performed in 2D and 3D, 2G and MG, diffusion and transport, with and without feedback. • All results show consistency with the reference results obtained from the ANL PN transport code VARIANT for steady-state and transport calculations. • It was found that the SP3 angular approximation captures sufficient transport effects for both steady-state and transient, and provides essentially the same results as the VARIANT P5 method. • From the transient results of the full-core problem, it was noted that MG is more conservative than 2G, and P1 is more conservative than SP3. - Abstract: Previous researchers have shown that the simplified P3 (SP3) approximation is capable of providing sufficiently high accuracy for both static and transient simulations for reactor core analysis with considerably less computational expense than higher order transport methods such as the discrete ordinate or the full spherical harmonics methods. The objective of this paper is to provide a consistent comparison of two-group (2G) and multi-group (MG) diffusion and SP3 transport for rod ejection accident (REA) in a practical light water reactor (LWR) problem. The analysis is performed on two numerical benchmarks, a 3 × 3 assembly mini-core and a full pressurized water reactor (PWR) core. The calculations were performed using pin homogenized and assembly homogenized cross sections for a series of benchmarks of increasing difficulty, in two-dimensional (2D) and three-dimensional (3D), 2G and MG, diffusion and transport, as well as with and without feedback. All results show consistency with the reference results obtained from higher-order methods. It is demonstrated that the analyzed problems show small group-homogenization effects, but relatively significant transport effects which are satisfactorily addressed by the SP3 transport method. The sensitivity tests

  12. Evaluation of nuclear accident consequences at INR / Nuclear Fuel Plant at Pitesti site

    In the last years, and especially after the Chernobyl accident, considerable efforts have been devoted to develop computer codes for evaluating the radiological impact of nuclear accident and gathering information on alternative counter measures implementing corresponding to different stages of an accident. One of the most important computer codes developed to this aim is COSYMA for radiological and economical consequences evaluations of accidental release of radioactive contaminants in the atmosphere. The paper presents the results obtained with COSYMA computer code for the case of a serious core damage of TRIGA nuclear reactor from INR / Nuclear Fuel Plant at Pitesti site. The specific meteorological conditions at this site, and data on the distribution of population, agricultural production distribution for risk area were taken into account. Short- and long-term doses to the public in the surrounding area, the contribution of different isotopes and exposure pathways, health effects and air and ground concentrations, are also presented. (authors)

  13. RADIATION-HYGIENIC AND MEDICAL CONSEQUENCES OF THE СHERNOBYL ACCIDENT: RESULTS AND PROGNOSIS

    G. G. Onischenko

    2011-01-01

    Full Text Available An article is devoted to the analysis of the radiation situation in the dynamics during the years since the accident at the Chernobyl nuclear power plant in 1986. Data on the scope of activities fulfilled for the assessment of the territories radioactive contamination levels and foodstuffs contamination levels, on the values of the exposure doses for the population living on the contaminated territories, on the medical and socio-psychological consequences of the Chernobyl accident is presented. Basic norms and principles, used during the protective measures development and introduction, are considered, their effectiveness is demonstrated. Mistakes emerged during protective measures implementation are analyzed, the prognosis of the population exposure dose values for the 70-year period since the accident and main directions of activities for the contaminated territories remediation and normal life conditions restoration for the population at these territories are presented.

  14. Development of information resources package for the Chernobyl accident and its consequences by INIS

    The Chernobyl accident was a global catastrophe that captured global attention and as such literature on the Chernobyl accident and its consequences is an important subject covered by the International Nuclear Information System (INIS) Database. The INIS Database contains about 21000 bibliographic records and 9000 full text documents on this subject from 1986 up to August 2006. Based on these extensive resources INIS released a DVD that contained bibliographic references and full text documents as well a bibliometric study of the Chernobyl references on the occasion of the International Conference entitled 'Chernobyl: Looking Back to Go Forwards' held in Vienna on 6 and 7 September 2005. Subsequently, INIS decided to release Revision 1 of the DVD in August 2006 for the twentieth anniversary of the Chernobyl accident with additional value added information sources. This paper briefly discusses the bibliometric parameters of the references, the contents of DVD and the activities undertaken to produce the Chernobyl information resources package

  15. The ASN and the consequences of the Fukushima-Daiichi nuclear accident

    This Power Point document first recalls the sources of exposure to radiations for the French population, the effects of radiation, and some data on the Chernobyl accident. It presents the ASN, its organisation, its means, its missions. It presents the different French nuclear sites, indicates the mean age of nuclear reactors in the World. It describes the licence renewal process, the safety re-examination process. Then, it addresses the Fukushima accident and more particularly the main challenges after the accident: to restore a safe status for the installations, to manage the contamination of the environment. It addresses the consequences for France, i.e mainly safety additional assessment process which has been launched, and the ASN opinion. It indicates the installations located in the Rhone-Alpes region to be assessed in priority, describes the ASN approach for the next months

  16. Quantifying reactor safety margins. Pt. 6; A physically based method of estimating PWR large break loss of coolant accident PCT

    Catton, I. (California Univ., Los Angeles (USA)); Duffey, R.B.; Shaw, R.A. (EG and G Idaho, Inc., Idaho Falls (USA)); Boyack, B.E. (Los Alamos National Lab., NM (USA)); Griffith, P. (Massachusetts Inst. of Tech., Cambridge (USA)); Katsma, K.R.; Wilson, G.E. (Idaho National Engineering Lab., Idaho Falls (USA)); Lellouche, G.S.; Levy, S. (Levy (S.), Inc., Campbell, CA (USA)); Rohatgi, U.S.; Wulff, W. (Brookhaven National Lab., Upton, NY (USA)); Zuber, N. (Nuclear Regulatory Commission, Washington, DC (USA))

    1990-05-01

    The Nuclear Regulatory Commission (NRC) has issued a revised Emergency Core Cooling System (ECCS) rule allowing the use of best estimate computer codes for safety analysis. To support this revised rule the NRC and its consultants and contractors have developed and demonstrated the Code Scaling, Applicability and Uncertainty (CSAU) Evaluation Methodology. This effort lead to increased understanding of the phenomena, and their relative dominance, during Large Break Loss of Coolant Accidents (LBLOCAs) in Pressurized Water Reactors (PWRs). Consequently, it became possible, as is done in this paper, to develop a method for establishing clad temperature history by using physically based arguments and engineering correlations. The results from this method are compared with similar uncertainty estimates based on large computer codes. These comparisons provide a rationale, based on physical arguments, for evaluating the large computer code based estimates of uncertainty. (orig.).

  17. Two decades of radiological accidents direct causes, roots causes and consequences

    Rozental Jose de Julio

    2002-01-01

    Full Text Available Practically all Countries utilize radioisotopes in medicine, industry, agriculture and research. The extent to which ionizing radiation practices are employed varies considerably, depending largely upon social and economic conditions and the level of technical skills available in the country. An overview of the majority of practices and the associated hazards will be found in the Table IV to VII of this document. The practices in normal and abnormal operating conditions should follow the basic principles of radiation protection and the Safety of Radiation Sources, considering the IAEA Radiation Protection and the Safety of Radiation Sources, Safety Series 120 and the IAEA Recommendation of the Basic Safety Standards for Radiation Protection, Safety Series Nº 115. The Standards themselves underline the necessity to be able to predict the radiological consequences of emergency conditions and the investigations that should need to be done. This paper describes the major accidents that had happened in the last two decades, provides a methodology for analyses and gives a collection of lessons learned. This will help the Regulatory Authority to review the reasons of vulnerabilities, and to start a Radiation safety and Security Programme to introduce measurescapable to avoid the recurrence of similar events. Although a number of accidents with fatalities have caught the attention of the public in recent year, a safety record has accompanied the widespread use of radiation sources. However, the fact that accidents are uncommon should not give grounds for complacency. No radiological accident is acceptable. From a radiation safety and security of the sources standpoint, accident investigation is necessary to determine what happened, why, when, where and how it occurred and who was (were involved and responsible. The investigation conclusion is an important process toward alertness and feedback to avoid careless attitudes by improving the comprehension

  18. Two decades of radiological accidents direct causes, roots causes and consequences

    Practically all countries utilize radioisotopes in medicine, industry, agriculture and research. The extent to which ionizing radiation practices are employed varies considerably, depending largely upon social and economic conditions and the level of technical skills available in the country. An overview of the majority of practices and the associated hazards will be found in the Table IV to VII of this document.The practices in normal and abnormal operating conditions should follow the basic principles of radiation protection and the Safety of Radiation Sources, considering the IAEA Radiation Protection and the Safety of Radiation Sources, Safety Series 120 and the IAEA Recommendation of the Basic Safety Standards for Radiation Protection, Safety Series 115. The Standards themselves underline the necessity to be able to predict the radiological consequences of emergency conditions and the investigations that should need to be done. This paper describes the major accidents that had happened in the last two decades, provides a methodology for analyses and gives a collection of lessons learned. This will help the Regulatory Authority to review the reasons of vulnerabilities, and to start a Radiation Safety and Security Programme to introduce measures capable to avoid the recurrence of similar events. Although a number of accidents with fatalities have caught the attention of the public in recent year, a safety record has accompanied the widespread use of radiation sources. However, the fact that accidents are uncommon should not give grounds for complacency. No radiological accident is acceptable. From a radiation safety and security of the sources standpoint, accident investigation is necessary to determine what happened, why, when, where, and how it occurred and who was (were) involved and responsible. The investigation conclusion is an important process toward alertness and feedback to avoid careless attitudes by improving the comprehension of Safety Performance

  19. Concept and validation studies of the real-time reactor-accident consequences assessment model ECOSYS

    The Chernobyl accident has demonstrated the urgent need for computer programs for real-time assessment of potential radiological consequences of major reactor accidents and for timely recommendations of useful and cost-efficient counter measures. During the past decade the dynamic radioecological program ECOSYS has been developed for nuclear accident consequence assessment with high resolution in space, time and exposure pathways. The Chernobyl reactor accident leading to relatively high contamination of Southern Germany provided excellent conditions for realistic validation studies of concept, sub-models and parameters of ECOSYS. To this purpose more than 7000 low level and in-situ gamma spectroscopy measurements were performed to study experimentally the behaviour of radionuclides in foodchains and in the urban environment and to compare the results to theoretical predictions of ECOSYS. The results show good agreement in the contamination levels of important food stuffs and in external exposure dose rates from a given surface contamination. Improvements were necessary in the assumptions regarding the food consumption habits which changed considerably - and in the functions describing the weathering off from urban and plant surfaces. The results of this validation study and the concept of the improved computerised model, which has subsequently been converted into a real-time code, are discussed in detail

  20. Evaluation of radiological and economic consequences associated with an accident in a fusion power plant

    Schneider, T. E-mail: schneider@cepn.asso.fr; Lepicard, S.; Saez, R.M.; Cabal, H.; Lechon, Y.; Ward, D.; Hamacher, T.; Aquilonius, K.; Hallberg, B.; Korhonen, R

    2001-11-01

    The evaluation of the external costs associated with an accident in a fusion power plant points out that the consequences of such an event, as far as health and environmental impacts are concerned, remain rather limited. This paper presents the main components of the evaluation on accident, performed in the framework of the Studies on Socio-Economic Research on Fusion SERF under the EURATOM agreement. This evaluation, limited to the health and environmental impacts, shows that the external costs of the fusion accident is in the range of 10{sup -5}-10{sup -4} mEURO/kW h while the total external costs for fusion are estimated in the range of a few mEURO per kilowatt hour. It should be noted that even with the integration of risk aversion, the external cost associated with the accident scenario for fusion power plant still remains quite limited due to the low radiological impacts that would have to support the populations surrounding the power plant if an accident occurred, especially the absence of evacuation and relocation of the population and the very limited constraints on food products.

  1. Evaluation of radiological and economic consequences associated with an accident in a fusion power plant

    The evaluation of the external costs associated with an accident in a fusion power plant points out that the consequences of such an event, as far as health and environmental impacts are concerned, remain rather limited. This paper presents the main components of the evaluation on accident, performed in the framework of the Studies on Socio-Economic Research on Fusion SERF under the EURATOM agreement. This evaluation, limited to the health and environmental impacts, shows that the external costs of the fusion accident is in the range of 10-5-10-4 mEURO/kW h while the total external costs for fusion are estimated in the range of a few mEURO per kilowatt hour. It should be noted that even with the integration of risk aversion, the external cost associated with the accident scenario for fusion power plant still remains quite limited due to the low radiological impacts that would have to support the populations surrounding the power plant if an accident occurred, especially the absence of evacuation and relocation of the population and the very limited constraints on food products

  2. Adaptation of COSYMA and assessment of accident consequences for Daya Bay nuclear power plant in China

    The program package COSYMA for assessing the radiological and economic consequences of nuclear accidents, developed with the support of the European Commission, was applied to investigate the health effects and risks from accidental releases of radioactive material from the Daya Bay nuclear power plant. Population distribution data in the range of 80 km around the site and hourly meteorological data for the year 1985 representative of accident consequence analysis were used. The results showed that early effects are more important at distances closer to the site, while the number of fatal cancers is closely related to the population density and the late effects are still important at distances larger than 50 km from the site. The mean annual expected values for early mortality and late mortality estimated for the population within a circle of 80 km around the Daya Bay nuclear power plant are 4.5x10-3 and 0.1 yr-1, respectively

  3. Environmental consequences of the Chernobyl accident and their remediation: Twenty years of experience

    The explosion on 26 April 1986 at the Chernobyl Nuclear Power Plant located just 100 km from the city of Kyiv in what was then the Soviet Union and now is Ukraine, and consequent ten days' reactor fire resulted in an unprecedented release of radiation and unpredicted adverse consequences both for the public and the environment. Indeed, the IAEA has characterized the event as the 'foremost nuclear catastrophe in human history' and the largest regional release of radionuclides into the atmosphere. Massive radioactive contamination forced the evacuation of more than 100,000 people from the affected region during 1986, and the relocation, after 1986, of another 200,000 from Belarus, the Russian Federation and Ukraine. Some five million people continue to live in areas contaminated by the accident and have to deal with its environmental, health, social and economic consequences. The national governments of the three affected countries, supported by international organizations, have undertaken costly efforts to remedy contamination, provide medical services and restore the region's social and economic well-being. The accident's consequences were not limited to the territories of Belarus, Russia and Ukraine but resulted in substantial transboundary atmospheric transfer and subsequent contamination of numerous European countries that also encountered problems of radiation protection of their populations, although to less extent than the three more affected countries. Although the accident occurred nearly two decades ago, controversy still surrounds the impact of the nuclear disaster. Therefore the IAEA, in cooperation with FAO, UNDP, UNEP, UNOCHA, UNSCEAR, WHO and The World Bank, as well as the competent authorities of Belarus, the Russian Federation and Ukraine, established the Chernobyl Forum in 2003. The mission of the Forum was - through a series of managerial and expert meetings to generate 'authoritative consensual statements' on the environmental consequences and

  4. Final report of the accident phenomenology and consequence (APAC) methodology evaluation. Spills Working Group

    Brereton, S.; Shinn, J. [Lawrence Livermore National Lab., CA (United States); Hesse, D [Battelle Columbus Labs., OH (United States); Kaninich, D. [Westinghouse Savannah River Co., Aiken, SC (United States); Lazaro, M. [Argonne National Lab., IL (United States); Mubayi, V. [Brookhaven National Lab., Upton, NY (United States)

    1997-08-01

    The Spills Working Group was one of six working groups established under the Accident Phenomenology and Consequence (APAC) methodology evaluation program. The objectives of APAC were to assess methodologies available in the accident phenomenology and consequence analysis area and to evaluate their adequacy for use in preparing DOE facility safety basis documentation, such as Basis for Interim Operation (BIO), Justification for Continued Operation (JCO), Hazard Analysis Documents, and Safety Analysis Reports (SARs). Additional objectives of APAC were to identify development needs and to define standard practices to be followed in the analyses supporting facility safety basis documentation. The Spills Working Group focused on methodologies for estimating four types of spill source terms: liquid chemical spills and evaporation, pressurized liquid/gas releases, solid spills and resuspension/sublimation, and resuspension of particulate matter from liquid spills.

  5. German offsite accident consequence model for nuclear facilities: further development and application

    The German Offsite Accident Consequence Model - first applied in the German Risk Study for nuclear power plants with light water reactors - has been further developed with the improvement of several important submodels in the areas of atmospheric dispersion, shielding effects of houses, and the foodchains. To aid interpretation, the presentation of results has been extended with special emphasis on the presentation of the loss of life expectancy. The accident consequence model has been further developed for application to risk assessments for other nuclear facilities, e.g., the liquid metal fast breeder reactor (SNR-300) and the high temperature gas cooled reactor. Moreover the model have been further developed in the area of optimal countermeasure strategies (sheltering, evacuation, etc.) in the case of the Central European conditions. Preliminary considerations has been performed in connection with safety goals on the basis of doses

  6. Probabilistic Accident Consequence Uncertainty Analysis of the Whole Program Package COSYMA (invited paper)

    The overall uncertainty analysis of the program package COSYMA for assessing the radiological consequences of nuclear accidents builds on the results of a series of individual uncertainty and sensitivity analyses of its submodules. A set of 186 model parameters was identified which contribute most to the uncertainties of endpoints. Probabilistic accident consequence assessments with 144 weather sequences were performed for each of 300 sample sets derived from the uncertainty distributions of these parameters by Latin hypercube sampling. The evaluation of the results provided confidence bounds for the complementary cumulative frequency distributions of endpoints for three different source terms covering a wide range of release fractions. Concluding sensitivity analyses identified the most important model parameters responsible for the uncertainties of endpoints. (author)

  7. The usefulness of time-dependent reactor accident consequence modelling for emergency response planning

    After major releases of radionuclides into the atmosphere fast reaction of authorities will be necessary to inform the public of potential consequences and to consider and optimize mitigating actions. These activities require availability of well designed computer models, adequate and fast measurements and prior training of responsible persons. The quantitative assessment models should be capable of taking into account of actual atmospheric dispersion conditions, actual deposition situation (dry, rain, snow, fog), seasonal status of the agriculture, food processing and distribution pathways, etc. In this paper the usefulness of such models will be discussed, their limitations, the relative importance of exposure pathways and a selection of important methods to decrease the activity in food products after an accident. Real-time reactor accident consequence models should be considered as a condition sine qua non for responsible use of nuclear power for electricity production

  8. Taking into account steam generator tube failure accidents in the design of safety systems for the N4 reactor (PWR 1400)

    Owing to the frequency with which they occur on PWRs, steam generator tube failure accidents have been the subject of a comprehensive review in France. Many modifications have been incorporated into the new PWR 1400 reactors so as to take this kind of accident more fully into account. The aim of these modifications is to control as well as possible the discharge of steam to the atmosphere, on the one hand, by making the atmospheric dump system an engineered safety feature, and on the other hand, by keeping to a minimum the risk of stressing the steam generator blow-off valves. Other modifications have been made to the turbine trip and to the startup of the emergency feedwater system, with a view to limiting the risk of an uncontrolled discharge into the atmosphere. The approach adopted represents an example of the integration of feedback into the design of safety systems and makes it possible to improve the level of safety in relation not only to steam generator tube failure accidents, but to all accidents which would necessitate rapid cooling by the secondary system. (author). 1 fig., 2 tabs

  9. Measures for reduction of severe accident consequences: Comprehensive evaluation of the results sponsored by the BMI

    A number of analytical studies were initial in the past by the Federal Ministry of Interior (BMI) of FRG, to investigate the potential of additional constructive measures for risk reduction. Those measures were proposed especially against uncontrolled overpressurization of the containment due to continuous gas/steam generation, penetration of the foundation of the reactor building by melt-concrete interaction, and failure of the containment due to violent hydrogen combustion. This report gives an overview about those studies and summarizes their results. Concerning uncontrolled overpressurization, only filtered venting may be a reasonable measure, while it seems to make not much sense, to look at measures against penetration of the foundation like 'core-catcher' in further detail. To prevent hydrogen combustion with severe consequences, several potential possibilities exist, but none of them can be considered as a safe measure. Additional analysis concerning hydrogen distribution and combustion in a multi-compartment containment are necessary. All studies mentioned in this report, deal with additional constructive measures to mitigate the consequences of severe accidents. Up to day in FRG, the potential of accident prevention and mitigation of its consequences by still or again operable and already existing systems of a plant have not been investigated in detail. As indicated by first results, the use of those systems in the frame of an appropriate accident management may have a large potential for risk reduction. (orig.)

  10. Severe accident mitigation strategy for the generation II PWRs in France. Some outcomes of the on-going periodic safety review of the French 1300 MWe PWR series

    The 3rd Periodic Safety Review of the French 1300 MWe PWRs series includes some modifications to increase their robustness in case of a severe accident. Their review is based on both deterministic and probabilistic approaches, keeping in mind that severe accidents frequencies and radiological consequences should be as low as reasonably practicable, severe accidents management strategies should be as safe as possible and the robustness of equipment used for severe accident management should be ensured. Consequently, the IRSN level 2 probabilistic safety assessment (L2 PSA) studies for the 1300 MWe reactors have been used to re-assess the results of the utility's L2 PSA and rank them to identify the containment failure modes contributing the most to the global risk. This ranking helped the review of plant modifications. Regarding strategies for accident management, the EDF management of water in the reactor cavity during a severe accident for the 1300 MWe PWRs is presented as well as the IRSN position on this strategy: this is an example where the optimal severe accident management strategy choice is not so easy to define. Regarding the robustness of equipment used for severe accident management, the interest of a diversification or redundancy of the French emergency filtered containment venting opening is one example among many others. (orig.)

  11. The fallout in France of the Chernobyl accident. Radioecological and dosimetric consequences; Les retombees en France de l'accident de Tchernobyl. Consequences radioecologiques et dosimetriques

    Renaud, Ph.; Beaugelin, K.; Maubert, H.; Ledenvic, Ph. [CEA Fontenay-aux-Roses, 92 (France). Inst. de Protection et de Surete Nucleaire

    1999-07-01

    For the first time, the whole of scientific data available has been gathered and exploited thanks to the ASTRAL model, developed at the Institute of protection and nuclear safety, (IPSN). This model has allowed to explain the principal causes of land and food contamination, as well their potential consequences on the human being. This book has elaborated with the help of every organism that has made radioactivity measurements in environment and man and his feeding. The extent of information sources used in this work makes of it a reference work. It allows to estimate the impact, in France of the Chernobyl accident on each of us and to understand the transfer mechanisms of radioactivity in environment. (N.C.)

  12. Evaluation of an accident risk of advanced pwr type reactors. Methods and results of a comprehensive probabilistic safety analysis (PSA)

    Nuclear power plant operators in Germany, and especially the opeator of GKN 2, support the GRS by providing information updates of the probabilistic methods of safety assessment. The report presents the investigations and results of probabilistic safety analyses for PWR power plants according to the current state of the art. The PSA uses methods that can be utilized by a wide range of experienced users and which have been tested by a 12-year continuous PSA for a nuclear power plant with an advanced PWR reactor. (orig.)

  13. Uncertainty and sensitivity analysis of food pathway results with the MACCS Reactor Accident Consequence Model

    Uncertainty and sensitivity analysis techniques based on Latin hypercube sampling, partial correlation analysis and stepwise regression analysis are used in an investigation with the MACCS model of the food pathways associated with a severe accident at a nuclear power station. The primary purpose of this study is to provide guidance on the variables to be considered in future review work to reduce the uncertainty in the important variables used in the calculation of reactor accident consequences. The effects of 87 imprecisely-known input variables on the following reactor accident consequences are studied: crop growing season dose, crop long-term dose, milk growing season dose, total food pathways dose, total ingestion pathways dose, total long-term pathways dose, area dependent cost, crop disposal cost, milk disposal cost, condemnation area, crop disposal area and milk disposal area. When the predicted variables are considered collectively, the following input variables were found to be the dominant contributors to uncertainty: fraction of cesium deposition on grain fields that is retained on plant surfaces and transferred directly to grain, maximum allowable ground concentrations of Cs-137 and Sr-90 for production of crops, ground concentrations of Cs-134, Cs-137 and I-131 at which the disposal of milk will be initiated due to accidents that occur during the growing season, ground concentrations of Cs-134, I-131 and Sr-90 at which the disposal of crops will be initiated due to accidents that occur during the growing season, rate of depletion of Cs-137 and Sr-90 from the root zone, transfer of Sr-90 from soil to legumes, transfer of Cs-137 from soil to pasture, transfer of cesium from animal feed to meat, and the transfer of cesium, iodine and strontium from animal feed to milk

  14. Uncertainty and sensitivity analysis of food pathway results with the MACCS Reactor Accident Consequence Model

    Helton, J.C. [Arizona State Univ., Tempe, AZ (United States); Johnson, J.D.; Rollstin, J.A. [GRAM, Inc., Albuquerque, NM (United States); Shiver, A.W.; Sprung, J.L. [Sandia National Labs., Albuquerque, NM (United States)

    1995-01-01

    Uncertainty and sensitivity analysis techniques based on Latin hypercube sampling, partial correlation analysis and stepwise regression analysis are used in an investigation with the MACCS model of the food pathways associated with a severe accident at a nuclear power station. The primary purpose of this study is to provide guidance on the variables to be considered in future review work to reduce the uncertainty in the important variables used in the calculation of reactor accident consequences. The effects of 87 imprecisely-known input variables on the following reactor accident consequences are studied: crop growing season dose, crop long-term dose, milk growing season dose, total food pathways dose, total ingestion pathways dose, total long-term pathways dose, area dependent cost, crop disposal cost, milk disposal cost, condemnation area, crop disposal area and milk disposal area. When the predicted variables are considered collectively, the following input variables were found to be the dominant contributors to uncertainty: fraction of cesium deposition on grain fields that is retained on plant surfaces and transferred directly to grain, maximum allowable ground concentrations of Cs-137 and Sr-90 for production of crops, ground concentrations of Cs-134, Cs-137 and I-131 at which the disposal of milk will be initiated due to accidents that occur during the growing season, ground concentrations of Cs-134, I-131 and Sr-90 at which the disposal of crops will be initiated due to accidents that occur during the growing season, rate of depletion of Cs-137 and Sr-90 from the root zone, transfer of Sr-90 from soil to legumes, transfer of Cs-137 from soil to pasture, transfer of cesium from animal feed to meat, and the transfer of cesium, iodine and strontium from animal feed to milk.

  15. Probabilistic accident consequence uncertainty analysis -- Late health effects uncertain assessment. Volume 2: Appendices

    Little, M.P.; Muirhead, C.R. [National Radiological Protection Board (United Kingdom); Goossens, L.H.J.; Kraan, B.C.P.; Cooke, R.M. [Delft Univ. of Technology (Netherlands); Harper, F.T. [Sandia National Labs., Albuquerque, NM (United States); Hora, S.C. [Univ. of Hawaii, Hilo, HI (United States)

    1997-12-01

    The development of two new probabilistic accident consequence codes, MACCS and COSYMA, was completed in 1990. These codes estimate the consequence from the accidental releases of radiological material from hypothesized accidents at nuclear installations. In 1991, the US Nuclear Regulatory Commission and the Commission of the European Communities began cosponsoring a joint uncertainty analysis of the two codes. The ultimate objective of this joint effort was to systematically develop credible and traceable uncertainty distributions for the respective code input variables. A formal expert judgment elicitation and evaluation process was identified as the best technology available for developing a library of uncertainty distributions for these consequence parameters. This report focuses on the results of the study to develop distribution for variables related to the MACCS and COSYMA late health effects models. This volume contains appendices that include (1) a summary of the MACCS and COSYMA consequence codes, (2) the elicitation questionnaires and case structures, (3) the rationales and results for the expert panel on late health effects, (4) short biographies of the experts, and (5) the aggregated results of their responses.

  16. Probabilistic accident consequence uncertainty analysis -- Early health effects uncertainty assessment. Volume 2: Appendices

    Haskin, F.E. [Univ. of New Mexico, Albuquerque, NM (United States); Harper, F.T. [Sandia National Labs., Albuquerque, NM (United States); Goossens, L.H.J.; Kraan, B.C.P. [Delft Univ. of Technology (Netherlands)

    1997-12-01

    The development of two new probabilistic accident consequence codes, MACCS and COSYMA, was completed in 1990. These codes estimate the consequence from the accidental releases of radiological material from hypothesized accidents at nuclear installations. In 1991, the US Nuclear Regulatory Commission and the Commission of the European Communities began cosponsoring a joint uncertainty analysis of the two codes. The ultimate objective of this joint effort was to systematically develop credible and traceable uncertainty distributions for the respective code input variables. A formal expert judgment elicitation and evaluation process was identified as the best technology available for developing a library of uncertainty distributions for these consequence parameters. This report focuses on the results of the study to develop distribution for variables related to the MACCS and COSYMA early health effects models. This volume contains appendices that include (1) a summary of the MACCS and COSYMA consequence codes, (2) the elicitation questionnaires and case structures, (3) the rationales and results for the panel on early health effects, (4) short biographies of the experts, and (5) the aggregated results of their responses.

  17. Probabilistic accident consequence uncertainty analysis -- Uncertainty assessment for deposited material and external doses. Volume 2: Appendices

    Goossens, L.H.J.; Kraan, B.C.P.; Cooke, R.M. [Delft Univ. of Technology (Netherlands); Boardman, J. [AEA Technology (United Kingdom); Jones, J.A. [National Radiological Protection Board (United Kingdom); Harper, F.T.; Young, M.L. [Sandia National Labs., Albuquerque, NM (United States); Hora, S.C. [Univ. of Hawaii, Hilo, HI (United States)

    1997-12-01

    The development of two new probabilistic accident consequence codes, MACCS and COSYMA, was completed in 1990. These codes estimate the consequence from the accidental releases of radiological material from hypothesized accidents at nuclear installations. In 1991, the US Nuclear Regulatory Commission and the Commission of the European Communities began cosponsoring a joint uncertainty analysis of the two codes. The ultimate objective of this joint effort was to systematically develop credible and traceable uncertainty distributions for the respective code input variables. A formal expert judgment elicitation and evaluation process was identified as the best technology available for developing a library of uncertainty distributions for these consequence parameters. This report focuses on the results of the study to develop distribution for variables related to the MACCS and COSYMA deposited material and external dose models. This volume contains appendices that include (1) a summary of the MACCS and COSYMA consequence codes, (2) the elicitation questionnaires and case structures, (3) the rationales and results for the panel on deposited material and external doses, (4) short biographies of the experts, and (5) the aggregated results of their responses.

  18. Probabilistic accident consequence uncertainty analysis -- Uncertainty assessment for internal dosimetry. Volume 2: Appendices

    Goossens, L.H.J.; Kraan, B.C.P.; Cooke, R.M. [Delft Univ. of Technology (Netherlands); Harrison, J.D. [National Radiological Protection Board (United Kingdom); Harper, F.T. [Sandia National Labs., Albuquerque, NM (United States); Hora, S.C. [Univ. of Hawaii, Hilo, HI (United States)

    1998-04-01

    The development of two new probabilistic accident consequence codes, MACCS and COSYMA, was completed in 1990. These codes estimate the consequence from the accidental releases of radiological material from hypothesized accidents at nuclear installations. In 1991, the US Nuclear Regulatory Commission and the Commission of the European Communities began cosponsoring a joint uncertainty analysis of the two codes. The ultimate objective of this joint effort was to systematically develop credible and traceable uncertainty distributions for the respective code input variables. A formal expert judgment elicitation and evaluation process was identified as the best technology available for developing a library of uncertainty distributions for these consequence parameters. This report focuses on the results of the study to develop distribution for variables related to the MACCS and COSYMA internal dosimetry models. This volume contains appendices that include (1) a summary of the MACCS and COSYMA consequence codes, (2) the elicitation questionnaires and case structures, (3) the rationales and results for the panel on internal dosimetry, (4) short biographies of the experts, and (5) the aggregated results of their responses.

  19. Methods and codes for assessing the off-site Consequences of nuclear accidents. Volume 2

    The Commission of the European Communities, within the framework of its 1980-84 radiation protection research programme, initiated a two-year project in 1983 entitled methods for assessing the radiological impact of accidents (Maria). This project was continued in a substantially enlarged form within the 1985-89 research programme. The main objectives of the project were, firstly, to develop a new probabilistic accident consequence code that was modular, incorporated the best features of those codes already in use, could be readily modified to take account of new data and model developments and would be broadly applicable within the EC; secondly, to acquire a better understanding of the limitations of current models and to develop more rigorous approaches where necessary; and, thirdly, to quantify the uncertainties associated with the model predictions. This research led to the development of the accident consequence code Cosyma (COde System from MAria), which will be made generally available later in 1990. The numerous and diverse studies that have been undertaken in support of this development are summarized in this paper, together with indications of where further effort might be most profitably directed. Consideration is also given to related research directed towards the development of real-time decision support systems for use in off-site emergency management

  20. Guide for licensing evaluations using CRAC2: A computer program for calculating reactor accident consequences

    A version of the CRAC2 computer code applicable for use in analyses of consequences and risks of reactor accidents in case work for environmental statements has been implemented for use on the Nuclear Regulatory Commission Data General MV/8000 computer system. Input preparation is facilitated through the use of an interactive computer program which operates on an IBM personal computer. The resulting CRAC2 input deck is transmitted to the MV/8000 by using an error-free file transfer mechanism. To facilitate the use of CRAC2 at NRC, relevant background material on input requirements and model descriptions has been extracted from four reports - ''Calculations of Reactor Accident Consequences,'' Version 2, NUREG/CR-2326 (SAND81-1994) and ''CRAC2 Model Descriptions,'' NUREG/CR-2552 (SAND82-0342), ''CRAC Calculations for Accident Sections of Environmental Statements, '' NUREG/CR-2901 (SAND82-1693), and ''Sensitivity and Uncertainty Studies of the CRAC2 Computer Code,'' NUREG/CR-4038 (ORNL-6114). When this background information is combined with instructions on the input processor, this report provides a self-contained guide for preparing CRAC2 input data with a specific orientation toward applications on the MV/8000. 8 refs., 11 figs., 10 tabs

  1. Uncertainty and sensitivity analysis of early exposure results with the MACCS Reactor Accident Consequence Model

    Helton, J.C. [Arizona State Univ., Tempe, AZ (United States); Johnson, J.D. [GRAM, Inc., Albuquerque, NM (United States); McKay, M.D. [Los Alamos National Lab., NM (United States); Shiver, A.W.; Sprung, J.L. [Sandia National Labs., Albuquerque, NM (United States)

    1995-01-01

    Uncertainty and sensitivity analysis techniques based on Latin hypercube sampling, partial correlation analysis and stepwise regression analysis are used in an investigation with the MACCS model of the early health effects associated with a severe accident at a nuclear power station. The primary purpose of this study is to provide guidance on the variables to be considered in future review work to reduce the uncertainty in the important variables used in the calculation of reactor accident consequences. The effects of 34 imprecisely known input variables on the following reactor accident consequences are studied: number of early fatalities, number of cases of prodromal vomiting, population dose within 10 mi of the reactor, population dose within 1000 mi of the reactor, individual early fatality probability within 1 mi of the reactor, and maximum early fatality distance. When the predicted variables are considered collectively, the following input variables were found to be the dominant contributors to uncertainty: scaling factor for horizontal dispersion, dry deposition velocity, inhalation protection factor for nonevacuees, groundshine shielding factor for nonevacuees, early fatality hazard function alpha value for bone marrow exposure, and scaling factor for vertical dispersion.

  2. Uncertainty and sensitivity analysis of early exposure results with the MACCS Reactor Accident Consequence Model

    Uncertainty and sensitivity analysis techniques based on Latin hypercube sampling, partial correlation analysis and stepwise regression analysis are used in an investigation with the MACCS model of the early health effects associated with a severe accident at a nuclear power station. The primary purpose of this study is to provide guidance on the variables to be considered in future review work to reduce the uncertainty in the important variables used in the calculation of reactor accident consequences. The effects of 34 imprecisely known input variables on the following reactor accident consequences are studied: number of early fatalities, number of cases of prodromal vomiting, population dose within 10 mi of the reactor, population dose within 1000 mi of the reactor, individual early fatality probability within 1 mi of the reactor, and maximum early fatality distance. When the predicted variables are considered collectively, the following input variables were found to be the dominant contributors to uncertainty: scaling factor for horizontal dispersion, dry deposition velocity, inhalation protection factor for nonevacuees, groundshine shielding factor for nonevacuees, early fatality hazard function alpha value for bone marrow exposure, and scaling factor for vertical dispersion

  3. Fukushima, one year after. First analyses of the accident and of its consequences

    This report proposes assessments and discussions of knowledge gathered by the IRSN during the first twelve months following the Fukushima accident to understand the status of the installations, to assess the releases, and to analyse and assess the consequences of the accident on workers and the impact on the population and environment. After a description of a boiling water reactor (general description, confinement barriers, safeguard systems), and of the earthquake, the authors describe and comment the consequences for several reactors (Fukushima-Dai-ini, Onagawa, Tokai, Higashidoru and Hamaoka). Then, they more precisely describe the Fukushima-Dai-ichi accident by distinguishing different periods (first two weeks, next three weeks, after the 17 of April). They analyse and comment the environmental impact in Japan (atmospheric dispersion of radioactive releases, ground contamination, impact of radioactive fallouts, contamination of the marine environment, and predictable impact on marine and ground ecosystems). They describe the actions undertaken to protect the population and in terms of post-accidental management, comment assessments of the dosimetric and health impact (workers and population exposure). They finally discuss the long range impact

  4. Družbenoekonomsko vrednotenje posledic prometnih nezgod na cestah v Sloveniji: Socioeconomic evaluation of road accident consequences in Slovenia:

    Bensa, Bruno; Kristl, Marko

    2004-01-01

    The goal of the research was to collect and merge data on traffic accidents and their consequences, collected by different institutions. The information formed the basis for calculations of socio-economic costs for the dead and injured in traffic accidents, as well as for estimates of material costs. In addition, an opinion poll on individual evaluation of costs related to trafficaccidents was conducted, and a traffic-accident information system was modeled with the purpose to enhance integra...

  5. Consequences in Norway after a hypothetical accident at Sellafield - Predicted impacts on the environment

    This report describes the possible environmental consequences for Norway due to a hypothetical accident at the Sellafield complex in the UK. The scenario considered involves an explosion and fire at the B215 facility resulting in a 1 % release of the total HAL (Highly Active liquor) inventory of radioactive waste with a subsequent air transport and deposition in Norway. Air transport modelling is based on real meteorological data from October 2008 with wind direction towards Norway and heavy precipitation. This weather is considered to be quite representative as typical seasonal weather. Based on this weather scenario, the estimated fallout in Norway will be ∼ 17 P Bq of caesium-137 which is 7 times higher than the fallout from the Chernobyl accident. The modelled radioactive contamination is linked with data on transfer to the food chain and statistics on production and hunting to assess the consequences for foodstuffs. The investigation has been limited to the terrestrial environment, focussing on wild berries, fungi, and animals grazing unimproved pastures (i.e. various types of game, reindeer, sheep and goats). The predicted consequences are severe - especially in connection to sheep and goat production. Up to 80 % of the lambs in Norway could be exceeding the food intervention levels for radiocaesium the first years after the fallout, with 30-40 % likely to be above for many years. There will, consequently, be a need for extensive countermeasures in large areas for years or even decades involving several hundred thousand animals each year. Large consequences are also expected for reindeer husbandry - the first year in particular due to the time of fallout which is just prior to winter slaughter. The consequences will be most sever for reindeer herding in middle and southern parts of Norway, but problems may reach as far north as Finnmark where we find the majority of Norwegian reindeer production. The consequences for game will mostly depend on the regional

  6. Accident consequence analysis models applied to licensing process of nuclear installations, radioactive and conventional industries

    The industrial accidents happened in the last years, particularly in the eighty's decade, had contributed in a significant way to call the attention to government authorities, industry and society as a whole, demanding mechanisms for preventing episodes that could affect people's safety and environment quality. Techniques and methods already thoroughly used in the nuclear, aeronautic and war industries were then adapted for performing analysis and evaluation of the risks associated to other industrial activities, especially in the petroleum, chemistry and petrochemical areas. Some models for analyzing the consequences of accidents involving fire and explosion, used in the licensing processes of nuclear and radioactive facilities, are presented in this paper. These models have also application in the licensing of conventional industrial facilities. (author)

  7. Nuclear accidents at the Fukushima Dai-ichi power plant. History, events and consequences

    Written few weeks after the accident, this article first recalls the circumstances (earthquake and tsunami), and then describes the accidental process within the primary vessels of the Fukushima Dai-ichi number 1, 2 and 3 reactors. The author then describes the interventions which aimed at cooling these three reactors, the problem faced for the storage of used fuels, and then the sequence of accidents: loss of cooling means leading to an explosion, problems faced in the different storage pools. He describes the various steps of recovery (primary cooling, electricity supply), discusses the consequences in terms of radioactivity releases in the plant environment with a comparison with Chernobyl, and also in terms of nature and quantity of radioactive elements. He comments radioactivity controls and measurements, evacuation measures, measurements performed by the IAEA, measurements of sea radioactivity, and the establishment of maps of ground radioactivity around the plant. He discusses the perspectives associated with these measurements for the surroundings of the Fukushima site

  8. Consequences of the Chernobyl reactor accident with respect to the feeding of infants

    In view of the persisting and understandable fear of parents with regard to radioactivity in the food of their babies as a consequence of the Chernobyl reactor accident, the Commission on Nutrition of the Deutsche Gesellschaft fuer Kinderheilkunde (German Society of Pediatrics) and the Strahlenschutzkommission have published a statement. According to this statement, the maximum permissible level of radioactivity in commercial baby food has been fixed by the EC to be 370 Bq/kg. The dietetic food industry itself has fixed a maximum for its products which is only a tenth of the radioactivity level permitted by the EC directive. The milk powders for infants tested since the reactor accident contained no measurable radioactivity or only very low amounts of Cs 134 or Cs 137, correspondung to a maximum of 25 Bq/kg in the product. Late damage to health is not to be expected. (orig./ECB)

  9. Expert Judgement for a Probabilistic Accident Consequence Uncertainty Analysis (invited paper)

    The development of two probabilistic accident consequence codes sponsored by the European Commission and the United States Nuclear Regulatory Commission, COSYMA and MACCS respectively, was completed in 1990. These codes estimate the risks and other endpoints associated with accidents from hypothesised nuclear installations. In 1991, both Commissions sponsored a joint project for an uncertainty analysis of these two codes. The main objective of this joint project was systematically to derive credible and traceable probability distributions for the respective code input variables. These input distributions will subsequently be used in two uncertainty analyses for each code separately. A formal expert judgement elicitation and evacuation process was used as the best available technique to accomplish that objective. This paper shows the overall process and reports on experiences of elicitors and experts of the eight expert judgement exercises performed under the joint study. (author)

  10. [Thrombosis and post-thrombotic syndrome as a consequence of an accident].

    Wahl, U; Hirsch, T

    2015-10-01

    Phlebothromboses represent alarming complications in accident victims since they can cause fatal pulmonary embolisms. More than half of those affected also develop post-thrombotic syndrome in the course of the illness. In addition to making clinical assessments, the traumatologist should also have fundamental knowledge about diagnostic methods and be familiar with interpreting internal findings. Colour-coded duplex sonography plays a central role in diagnosing thrombosis and in assessing functional limitations. Further information can be gathered from various phlebological procedures. The expert evaluation of the immediate, as well as the long-term consequences of an accident frequently require leg swelling to be classified. It is not uncommon for post-thrombotic syndrome to be diagnosed for the first time during this process. An additional vascular appraisal is often required. An appreciation of social-medical and insurance-related aspects means a high degree of responsibility is placed on the expert. PMID:26377807

  11. Uncertainty and sensitivity analysis of chronic exposure results with the MACCS reactor accident consequence model

    Uncertainty and sensitivity analysis techniques based on Latin hypercube sampling, partial correlation analysis and stepwise regression analysis are used in an investigation with the MACCS model of the chronic exposure pathways associated with a severe accident at a nuclear power station. The primary purpose of this study is to provide guidance on the variables to be considered in future review work to reduce the uncertainty in the important variables used in the calculation of reactor accident consequences. The effects of 75 imprecisely known input variables on the following reactor accident consequences are studied: crop growing season dose, crop long-term dose, water ingestion dose, milk growing season dose, long-term groundshine dose, long-term inhalation dose, total food pathways dose, total ingestion pathways dose, total long-term pathways dose, total latent cancer fatalities, area-dependent cost, crop disposal cost, milk disposal cost, population-dependent cost, total economic cost, condemnation area, condemnation population, crop disposal area and milk disposal area. When the predicted variables are considered collectively, the following input variables were found to be the dominant contributors to uncertainty: dry deposition velocity, transfer of cesium from animal feed to milk, transfer of cesium from animal feed to meat, ground concentration of Cs-134 at which the disposal of milk products will be initiated, transfer of Sr-90 from soil to legumes, maximum allowable ground concentration of Sr-90 for production of crops, fraction of cesium entering surface water that is consumed in drinking water, groundshine shielding factor, scale factor defining resuspension, dose reduction associated with decontamination, and ground concentration of 1-131 at which disposal of crops will be initiated due to accidents that occur during the growing season

  12. Uncertainty and sensitivity analysis of chronic exposure results with the MACCS reactor accident consequence model

    Uncertainty and sensitivity analysis techniques based on Latin hypercube sampling, partial correlation analysis and stepwise regression analysis are used in an investigation with the MACCS model of the chronic exposure pathways associated with a severe accident at a nuclear power station. The primary purpose of this study is to provide guidance on the variables to be considered in future review work to reduce the uncertainty in the important variables used in the calculation of reactor accident consequences. The effects of 75 imprecisely known input variables on the following reactor accident consequences are studied: crop growing-season dose, crop long-term dose, water ingestion dose, milk growing-season dose, long-term groundshine dose, long-term inhalation dose, total food pathways dose, total ingestion pathways dose, total long-term pathways dose, total latent cancer fatalities, area-dependent cost, crop disposal cost, milk disposal cost, population-dependent cost, total economic cost, condemnation area, condemnation population, crop disposal area and milk disposal area. When the predicted variables are considered collectively, the following input variables were found to be the dominant contributors to uncertainty: dry deposition velocity, transfer of cesium from animal feed to milk, transfer of cesium from animal feed to meet, ground concentration of Cs-134 at which the disposal of milk products will be initiated, transfer of Sr-90 from soil to legumes, maximum allowable ground concentration of Sr-90 for production of crops, fraction of cesium entering surface water that is consumed in drinking water, groundshine shielding factor, scale factor defining resuspension, dose reduction associated with decontamination, and ground concentration of I-131 at which disposal of crops will be initiated due to accidents that occur during the growing season. Reducing the uncertainty in the preceding variables was found to substantially reduce the uncertainty in the

  13. Uncertainty and sensitivity analysis of chronic exposure results with the MACCS reactor accident consequence model

    Helton, J.C. [Arizona State Univ., Tempe, AZ (United States); Johnson, J.D.; Rollstin, J.A. [Gram, Inc., Albuquerque, NM (United States); Shiver, A.W.; Sprung, J.L. [Sandia National Labs., Albuquerque, NM (United States)

    1995-01-01

    Uncertainty and sensitivity analysis techniques based on Latin hypercube sampling, partial correlation analysis and stepwise regression analysis are used in an investigation with the MACCS model of the chronic exposure pathways associated with a severe accident at a nuclear power station. The primary purpose of this study is to provide guidance on the variables to be considered in future review work to reduce the uncertainty in the important variables used in the calculation of reactor accident consequences. The effects of 75 imprecisely known input variables on the following reactor accident consequences are studied: crop growing season dose, crop long-term dose, water ingestion dose, milk growing season dose, long-term groundshine dose, long-term inhalation dose, total food pathways dose, total ingestion pathways dose, total long-term pathways dose, total latent cancer fatalities, area-dependent cost, crop disposal cost, milk disposal cost, population-dependent cost, total economic cost, condemnation area, condemnation population, crop disposal area and milk disposal area. When the predicted variables are considered collectively, the following input variables were found to be the dominant contributors to uncertainty: dry deposition velocity, transfer of cesium from animal feed to milk, transfer of cesium from animal feed to meat, ground concentration of Cs-134 at which the disposal of milk products will be initiated, transfer of Sr-90 from soil to legumes, maximum allowable ground concentration of Sr-90 for production of crops, fraction of cesium entering surface water that is consumed in drinking water, groundshine shielding factor, scale factor defining resuspension, dose reduction associated with decontamination, and ground concentration of 1-131 at which disposal of crops will be initiated due to accidents that occur during the growing season.

  14. Radiological and dosimetric consequences in case of nuclear accident: taking them into account within the security approach and protection challenges

    This report first proposes a presentation of the 'defence in depth' concept which comprises five as much as possible independent levels: preventing operation anomalies and system failures, maintaining the installation within the authorized domain, controlling accidents within design hypotheses, preventing the degradation of accidental conditions and limiting consequences of severe accidents, limiting radiological consequences for population in case of important releases. Then, after a description of a release atmospheric dispersion and of its consequences, this report describes the consequences of two accident scenarios. The first accident is a failure of steam generator tubes, and the second a loss of primary coolant. It notably indicates the main released radionuclides, exposure levels at different distance for a given set of dispersion conditions

  15. Consequence Analysis of Release from KN-18 Cask during a Severe Transportation Accident

    Lim, Heoksoon; Bhang, Giin; Na, Janghwan; Ban, Jaeha; Kim, Myungsu [KAERI, Daejeon (Korea, Republic of)

    2015-05-15

    Korea Hydro and Nuclear Power (KHNP) has launched a project entitled 'Development of APR1400 Physical Protection System Design' and conducting a new conceptual physical protection system(PPS) design. One of mayor contents is consequence analysis for spent nuclear fuel cask. Proper design of physical protection system for facilities and storage and transformation involving nuclear and radioactive material requires the quantification of potential consequence from prescribed sabotage and theft scenarios in order to properly understand the level of PPS needed for specific facilities and materials. An important aspect of the regulation of the nuclear industry is assessing the risk to the public and the environment from a release of radioactive material produced by accidental or intentional scenarios. This paper describes the consequence analysis methodology, structural analysis for KN-18 cask and results of release from the cask during a severe transportation accident. Accident during spent fuel cask transportation was numerically calculated for KN-18, and showed the integrity of the fuel assemblies and cask itself was unharmed on a scenario that is comparable to state of art NRC research. Even assumption of leakage as a size of 1 x 10''2 mm''2 does not exceed for a certain criteria at any distance.

  16. Economic consequences of the Chernobyl accident in Norway in 1986 and 1987

    In the accident consequence assessment (ACA) area there is extensive cooperation between the Nordic countries (Denmark, Finland, Norway, and Sweden), performed within the Nordic Safety Program, and partially funded by the Nordic Council of Ministers, via the Nordic Liaison Committee for Atomic Energy. One of the 17 projects in the ACA-related program area is concerned with the economic consequences of the Chernobyl accident in Finland, Norway, and Sweden. This paper is limited to describing conditions in Norway. There are areas in Norway where the Chernobyl fallout is >100 kBq/m2, and the total amount of radiocesium deposited over Norway is estimated by the National Institute for Radiation Hygiene to be 6% of the radiocesium released from the reactor. The areas where ground concentrations are highest are mostly in sparsely populated mountain areas. These areas are, however, important in connection with several nutritional pathways, notably, sheep, goats, reindeer, and freshwater fish. The purpose of this paper is to summarize information on mitigating actions and economic consequences of the deposited radioactive materials to Norwegian agriculture in the 1986-87 and 1987-88 slaughtering periods

  17. Consequence Analysis of Release from KN-18 Cask during a Severe Transportation Accident

    Korea Hydro and Nuclear Power (KHNP) has launched a project entitled 'Development of APR1400 Physical Protection System Design' and conducting a new conceptual physical protection system(PPS) design. One of mayor contents is consequence analysis for spent nuclear fuel cask. Proper design of physical protection system for facilities and storage and transformation involving nuclear and radioactive material requires the quantification of potential consequence from prescribed sabotage and theft scenarios in order to properly understand the level of PPS needed for specific facilities and materials. An important aspect of the regulation of the nuclear industry is assessing the risk to the public and the environment from a release of radioactive material produced by accidental or intentional scenarios. This paper describes the consequence analysis methodology, structural analysis for KN-18 cask and results of release from the cask during a severe transportation accident. Accident during spent fuel cask transportation was numerically calculated for KN-18, and showed the integrity of the fuel assemblies and cask itself was unharmed on a scenario that is comparable to state of art NRC research. Even assumption of leakage as a size of 1 x 10''2 mm''2 does not exceed for a certain criteria at any distance

  18. Chemical interactions between the metallic silver aerosols and the iodide compounds in the containment building of a PWR reactor during a serious accident

    During an hypothetical severe accident in a PWR, the iodide fission products can be transferred into the liquid phase of the containment with silver particles (or silver colloid) resulting from the fusion and the vaporization of neutronic control rods. The chemical interactions between the iodide ions and the molecular iodine with the silver particles are studied in an aqueous phase separately and without radiation. The interaction between the iodide ions and silver particles requires a preliminary oxidation step of the silver particles the rate of which depends on the pH, the temperature and the liquid oxygen concentration. A kinetic model including two independent stoichiometries allows to represent correctly the whole experimental runs. At pH = 3, the chemical interactions between molecular iodine and silver particles do not require an oxidation step and a second order kinetic model is able to represent the experimental results considering the operating conditions studied. (authors)

  19. Consistent Comparison of Full Core PWR Reactivity Initiated Accident with the Method Of Characteristic Code DeCART and the Coarse Mesh Nodal Code PARCS - 180

    The current state of the art in analysis of a control rod ejection event in a Pressurized Water Reactor (PWR) relies upon the assembly averaged power from a whole core nodal neutronics simulator and some type of pin power reconstruction within the fuel assembly. Recently, there has been interest in taking advantage of the DeCART code to perform a higher fidelity solution which could lead to more accurate pin-power results as well as provide intra-pin power information during the transient. The work described in this paper is the comparison of PARCS and DeCART analysis of two Reactivity Initiated Accidents. The methods used in PARCS and DeCART are briefly described as well as the approach to generate the needed temperature feedbacks. The generation of the macroscopic cross sections and kinetic parameters for PARCS is detailed. The results of both scenarios are shown and the main differences of both approaches are discussed. (authors)

  20. The environmental restoration in the management of radiological accidents with off site consequences

    Radiological accidents are among the potential cases of environmental contamination that could have consequences on the health of the population. These accidents, associated with an increase in the level of radiological exposure surpassing the natural background, have been investigated in greater depth than other conventional accidents. This investigation has included the evaluation of their probability, magnitude and consequences in order to establish safety norms. Nevertheless, the social perception of this type of risk appears to be disproportionately high. The development of a comprehensible and adequate standardized system for the evaluation of the radiological risk and the applicability of corrective actions to reduce this type of risk at local level, will undoubtedly contribute to increase the public confidence in the advised options for the restoration of environments contaminated with the long lived radionuclides. This system should consider the local specificity of each contaminated place, and take into account the associated unwanted consequences for each option. This paper presents the first results of a system to help the decision makers in the quantitative evaluation of the radiological risk produced by long lived radionuclides Cs 137, Cs 134 and Sr 90 spread over urban, agricultural and semi-natural environments and the applicable options to reduce it. The evaluation of these applicable options is made considering the reduction of dose that can be reached, the monetary costs and the significant associated secondary effects if there are any. All these factors are integrated for a time period depending on the half-life of the contaminants and on their strength and distribution on the scenario when intervention is being planned. (authors)

  1. The Fukushima Daiichi Accident. Technical Volume 4/5. Radiological Consequences

    This technical volume describes the consequences associated with radioactivity and radiation from the accident at the Fukushima Daiichi nuclear power plant (NPP) for people and the environment. A number of international organizations have already issued reports on the potential health and environmental consequences of the accident, notably the World Health Organization (WHO) and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR). The intention of the assessments presented in this volume is to build on their work, using more recent data where available. Quantitative information arising from both personal and environmental monitoring has been provided by the Government of Japan. Section 4.1 provides the best estimates of the magnitude and form of radioactive releases during the accident to the atmosphere and directly into the surrounding sea. It also explains the movement of the discharged radionuclides through air and water and the eventual deposition of the atmospheric activity on land in Japan and other countries worldwide, as well as on the open oceans. The goal is to provide a consolidated repository of information on releases to, and levels of radionuclides in, the environment. Some of this information is used in the analyses in subsequent sections of this volume. Section 4.2 gives an overview of exposures to the main groups of emergency workers at the Fukushima Daiichi NPP, to groups of off-site workers and to members of the public. Where sufficient data are available, average effective dose and thyroid equivalent doses derived from personal measurements are compared with the results of previous assessments for specific locations, population groups and time periods. Section 4.3 summarizes relevant aspects of the system of radiation protection in place at the time of the accident. It includes an overview of the legislation and guidance used to implement the radiation protection framework in Japan. This section also provides a

  2. An assessment of the consequences of the Greek Research Reactor's design basis accident: sensitivity to the meteorological record

    The sensitivity of the Greek Research Reactor's design basis accident consequences to the meteorological record, as far as Athens population is concerned, is assessed in this report. Meteorological data of six years of the National Observatory of Athens are analyzed and utilized in the accident consequence calculation model by using weather categories. The results of the present analysis indicate that the meteorological record does not have a significant impact on predicted consequences, which in turn indicates that the utilization of a substitute meteorological record from a nearby meteorological station instead of the reactor's site record could be acceptable for performing consequence analyses. (author)

  3. Modeling the consequences of hypothetical accidents for the Titan II system

    Calculations have been made with the Atmospheric Release Advisory Capability (ARAC) suite of three-dimensional transport and diffusion codes MATHEW/ADPIC to assess the consequences of severe, hypothetical accident scenarios. One set of calculations develops the integrated dose and surface deposition patterns for a non-nuclear, high explosive detonation and dispersal of material. A second set of calculations depicts the time integrated dose and instantaneous concentration patterns for a substantial, continuous leak of the missile fuel oxidizer converted to nitrogen dioxide (NO2). The areas affected and some of the implications for emergency response management are discussed

  4. UFOMOD - program to calculate the radiological consequences of reactor accidents within risk studies

    The FORTRAN-IV computer code UFOMOD calculates the radiological consequences of reactor accidents for risk studies, namely early deaths, latent cancer deaths and genetic significant doses. Different models for the atmospheric transport and deposition, the dose calculation, the countermeasures and the injuries are used to calculate individual and collective injury. Up to 54 radionuclides, 10 release categories, 4 meteorological zones, 10 population distributions per zone with up to 36 sectors and 50 rings, and 115 weather sequences per zone may be used. The deterministic results are combined together with the respective probabilities and frequencies to give complementary cumulative frequency distributions. This report describes the computer code and its input and output. (orig.)

  5. Calculations of reactor-accident consequences, Version 2. CRAC2: computer code user's guide

    The CRAC2 computer code is a revision of the Calculation of Reactor Accident Consequences computer code, CRAC, developed for the Reactor Safety Study. The CRAC2 computer code incorporates significant modeling improvements in the areas of weather sequence sampling and emergency response, and refinements to the plume rise, atmospheric dispersion, and wet deposition models. New output capabilities have also been added. This guide is to facilitate the informed and intelligent use of CRAC2. It includes descriptions of the input data, the output results, the file structures, control information, and five sample problems

  6. A simplified model for calculating early offsite consequences from nuclear reactor accidents

    Madni, I.K.; Cazzoli, E.G.; Khatib-Rahbar, M.

    1988-07-01

    A personal computer-based model, SMART, has been developed that uses an integral approach for calculating early offsite consequences from nuclear reactor accidents. The solution procedure uses simplified meteorology and involves direct analytic integration of air concentration equations over time and position. This is different from the discretization approach currently used in the CRAC2 and MACCS codes. The SMART code is fast-running, thereby providing a valuable tool for sensitivity and uncertainty studies. The code was benchmarked against both MACCS version 1.4 and CRAC2. Results of benchmarking and detailed sensitivity/uncertainty analyses using SMART are presented. 34 refs., 21 figs., 24 tabs.

  7. Medico-demographic criteria in estimating the consequences of the Chernobyl accident

    Correct comparison of population statistics in affected and unaffected areas prior to and after the accident allows to detect any noticeable deviations in basic medico-demographic parameters in contaminated territories from common trends. In view of that when in 1990 in Nuclear Safety Institute a start has been made on construction of an information support system for government and regional executives to overcome the consequences of the Chernobyl disaster a specialized data bank on demography and medical statistics (MDBD) was created. 12 refs, 7 figs, 8 tabs

  8. Functional status of thyroid of Chernobyl accident consequences liquidators after 10 years after disaster

    Analysis of Chernobyl accident consequences liquidators' complaints is carried out and their clinical surveillance is conducted as well. Pronounced disorders of neuro-immune-endocrine system of the liquidators majority and ahill reflex latency half-period prolongation have been observed. By data of ultrasonic study the majority of examined ones have thyroid hyperplasia without features of chronic autoimmune inflammation and formation of adenomatous knots. Thyroid levels of hormone concentration are reduced. There is direct dependence between hormones levels and irradiation dose. The is concluded, that in delayed period after irradiation by low doses the hypo-function status of thyroid is observing

  9. Techniques Applied in the COSYMA Accident Consequence Uncertainty Analysis (invited paper)

    Uncertainty and sensitivity analysis studies for the program package COSYMA for assessing the radiological consequences of nuclear accidents have been performed to obtain a deeper insight into the propagation of parameter uncertainties through different submodules and to quantify their contribution to uncertainty and sensitivity in a final overall uncertainty analysis of the complete program system COSYMA. Some strategies are given for performing uncertainty analysis runs for submodules and/or the complete complex program system COSYMA and guidelines explain how to post-process and to reduce the bulk of uncertainty and sensitivity analysis results. (author)

  10. Development of an accident consequence analysis program based on the object oriented programming technique

    The KAERI accident consequence analysis program KAPAC is being developed on the basis of reusable objects in PPAM (platform for the development of plant analysis and management codes). Development of PPAM is being conducted at the Korea Atomic Energy Research Institute (KAERI) in order to be able to provide portability and reusability of computer codes, and consistent user interface in developing software with the use of object oriented programming (OOP) under a Microsoft Windows environment. By constructing the platform, software development can benefit from a shorter development cycle and an easier validation and verification process. 1 ref., 2 figs

  11. Hypertension and left ventricular hypertrophy in liquidators of consequences of the Chernobyl nuclear accident

    Echocardiography was used for the study of prevalence of left ventricular hypertrophy in 839 liquidators of consequences of the Chernobyl accident. Prevalence of left ventricular hypertrophy (left ventricular myocardial mass 134 g/m2) was 10.3, 13.4 and 22.5 % in liquidators with normal blood pressure, borderline hypertension and hypertension, respectively. Liquidators with normal blood pressure had significantly greater left ventricular myocardial mass than normotensive men from general population while liquidators and non liquidators with hypertension had equal values of this parameter

  12. The accident in Fukushima. Preliminary report on the accident progress in the nuclear power plants as a consequence of the earth quake on 11th March 2011

    The preliminary report on the accident progress in the nuclear power plants as a consequence of the earth quake on 11th March 2011 describes the chronologic sequence of the accident in the different units of the power plant. The measures for mitigation of the accident impact at the site of Fukushima Daiichi and Fukushima Daini included the efforts to reach and maintain stable plant conditions. The issue radiological situation includes an estimation of the air-borne radionuclide release, the contamination of the environment and the sea water, measures for protection of the public. The lessons learned following the NISA and IAEA fact finding missions and the open questions are summarized.

  13. Epidemiological studies in Russia about the consequences of the Chernobyl APS accident

    Ryabzev, I.A. [Institute of Problem of Ecology and Evolution, Russian Academy of Sciences, Moscow (Russian Federation)

    1998-03-01

    The final purpose of all efforts to study and mitigate the consequences of the accident at the 4th reactor of the Chernobyl atomic power station (ChAPS) is protection of health of the people who were more or less exposed to radiation action. This situation has not analogs in terms of scale and character. Certain experience was accumulated earlier through the studies of biological and medical effects of atomic bombing in Hiroshima and Nagasaki, other radiation catastrophes, diagnostic and therapeutic application of radiation, and the control of health state of professionals in atomic industries. However, these experiences can be used just partially in the assessment and the forecast of possible negative after-effects of the Chernobyl accident for the present and future generations. The long-term irradiation of a lage number of population at low doses is to be considered the principal peculiarity of the Chernobyl accident. The medical activities are complicated significantly by the absence of verifiable individual dosimetric information, natural or forced migration of the population, insufficient development of radiation epidemiology, complicated social-economic situation in the country, and other factors which are inevitable at large-scaled catastrophes. Besides, many fundamental questions related to biological effects of action of low doses of ionizing radiation are still being studied. (J.P.N.)

  14. Knowledge resources on the Chernobyl accident and its consequences in the INIS Database

    Literature on the Chernobyl accident and its consequences is an important subject covered by the International Nuclear Information System (INIS) Database. The INIS Database contains 19872 bibliographic records and 8400 full text documents on this subject from 1986 up to 04/2005. A bibliometric study of these records was made to generate statistical summaries that characterise, in general terms, the intellectual content of the records and the nature of the records in terms of its major bibliographic attributes. Environmental aspects and human health constitute the two dominant subjects with a respective contribution of 49% and 38%. The rest is evenly divided among legal aspects, reactor safety and socio-economic impacts of the accident. The three countries that are most affected by the accident, namely Ukraine, Russian Federation and Belarus contributed 44% of the total input. 57% of the literature analysed are conference papers and reports while 25% are journal articles. Most of the documents were written in English (47%) and in Russian (36%). Seven percent of the publications were written in German. (author)

  15. Source term and radiological consequence evaluation for nuclear accidents using a 'hand type' methodology

    In the last decades, hand type calculations have been replaced by computerized solutions, which are much more accurate, but the preparation of an input to run the code can be a time consuming process and can require a laborious work. This is why, a place for hand calculation based on nomograms still exist in some areas. An example is emergency response to an accidental release of radioactive contaminants when the health of persons close to the accident site might be at risk. In this case, results from computerized accident consequences assessment models may be delayed due to the equipment malfunction or the time required developing minimal input files and performing the calculations (typically more than five minutes). A simple nomogram (developed using computerized dispersion model calculations) can provide dispersion and dose estimates within a minute. The paper presents the methodology used for these 'hand type' calculation and the nomograms, figures and tables used to evaluate the dose to an individual close to the release point. In order to illustrate the use of methodology, a hypothetical severe accident scenario involving 14-MW INR-TRIGA research reactor was considered. (authors)

  16. Mitigation of sodium-cooled fast reactor severe accident consequences using inherent safety principles

    Full text: Sodium-cooled fast reactors are designed to have a high level of safety. Events of high probability of occurrence are typically handled without consequence through reliable engineering systems and good design practices. For accidents of lower probability, the initiating events are characterized by larger and more numerous challenges to the reactor system, such as failure of one or more major engineered systems and can also include a failure to scram the reactor in response. As the initiating conditions become more severe, they have the potential for creating serious consequences of potential safety significance, including fuel melting, fuel pin disruption and recriticality. If the progression of such accidents is not mitigated by design features of the reactor, energetic events and dispersal of radioactive materials may result. In the United States, accidents which have the potential for severe consequences usually are of probability less than 1 x 10-4 per reactor year, intended to satisfy the U.S. Nuclear Regulatory Commission (NRC) goal of limiting accidents with any fuel melting to such low probabilities. Such severe accidents include the category of Anticipated Transient Without Scram (ATWS) events mentioned above. Three accidents are usually analyzed to evaluate the reactor response in these cases; the unprotected (unscrammed) loss-of-flow (ULOF), where pumping power is lost and the pumps coast down, reducing coolant flow through the reactor core; the unprotected transient overpower (UTOP), where a control rod is inadvertently withdrawn from the core; and the unprotected loss-of-heat-sink (ULOHS), where the steam generator is isolated from the reactor in response to a turbine trip. For each of these accidents, there are several approaches that can be used to mitigate the consequences of such severe accident initiators, which typically include fuel pin failures and core disruption. One approach is to increase the reliability of the reactor protection

  17. Fukushima, one year later. Initial analyses of the accident and its consequences

    The earthquake of magnitude 9 of March 11, 2011 with an epicenter 80 km east of the Japanese island of Honshu, and the subsequent tsunami, severely affected the region of Tohoku, with major consequences for its population and infrastructure. Devastating the site of the Fukushima Dai-ichi nuclear power plant, these natural events were the cause of the core meltdowns of three nuclear reactors and the loss of cooling of several spent fuel pools. Explosions also occurred in reactor buildings 1 through 4 due to hydrogen produced during fuel degradation. Very significant radioactive releases into the environment took place. The accident was classified level 7 on the International Nuclear Event Scale (INES). This report provides an assessment and perspective on the information gathered by IRSN during the first twelve months following the disaster in an effort to understand the condition of the installations, evaluate the releases and analyze and evaluate the consequences of the accident on workers and the impact on the population and the environment. On the basis of available information, the report provides an initial analysis of the chain of events. It should be noted that a year after the accident, the full sequence of events is still not understood. Operating experience feedback from the 1979 Three Mile Island accident in the United States, in which reactor core damage was not confirmed until 1986, suggests that it may be several years before a detailed scenario can be constructed of the accident that led to radioactive releases. It will require access to the damaged installations. The situation at the site remains dangerous (reactor pressure vessels and containments are not leak-tight, diffuse releases, etc.). If it has significantly improved as a result of the significant resources deployed by the Tokyo Electro Power Company (TEPCO) to regain control of the installations, this effort must continue over the long term to begin evacuation of fuel from pools (in two

  18. Assessment of the consequences of releases

    After a brief recall of severe accidental sequence and of data concerning the containment building, this paper deals with the containment failure mode and source term relationship. The realistic calculation system of the consequences of severe PWR accidents is very shortly presented while giving for each code the phenomena studied

  19. Probabilistic accident consequence uncertainty analysis: Dispersion and deposition uncertainty assessment, appendices A and B

    Harper, F.T.; Young, M.L.; Miller, L.A. [Sandia National Labs., Albuquerque, NM (United States); Hora, S.C. [Univ. of Hawaii, Hilo, HI (United States); Lui, C.H. [Nuclear Regulatory Commission, Washington, DC (United States); Goossens, L.H.J.; Cooke, R.M. [Delft Univ. of Technology (Netherlands); Paesler-Sauer, J. [Research Center, Karlsruhe (Germany); Helton, J.C. [and others

    1995-01-01

    The development of two new probabilistic accident consequence codes, MACCS and COSYMA, completed in 1990, estimate the risks presented by nuclear installations based on postulated frequencies and magnitudes of potential accidents. In 1991, the US Nuclear Regulatory Commission (NRC) and the Commission of the European Communities (CEC) began a joint uncertainty analysis of the two codes. The objective was to develop credible and traceable uncertainty distributions for the input variables of the codes. Expert elicitation, developed independently, was identified as the best technology available for developing a library of uncertainty distributions for the selected consequence parameters. The study was formulated jointly and was limited to the current code models and to physical quantities that could be measured in experiments. To validate the distributions generated for the wet deposition input variables, samples were taken from these distributions and propagated through the wet deposition code model along with the Gaussian plume model (GPM) implemented in the MACCS and COSYMA codes. Resulting distributions closely replicated the aggregated elicited wet deposition distributions. Project teams from the NRC and CEC cooperated successfully to develop and implement a unified process for the elaboration of uncertainty distributions on consequence code input parameters. Formal expert judgment elicitation proved valuable for synthesizing the best available information. Distributions on measurable atmospheric dispersion and deposition parameters were successfully elicited from experts involved in the many phenomenological areas of consequence analysis. This volume is the second of a three-volume document describing the project and contains two appendices describing the rationales for the dispersion and deposition data along with short biographies of the 16 experts who participated in the project.

  20. Probabilistic accident consequence uncertainty analysis: Dispersion and deposition uncertainty assessment, appendices A and B

    The development of two new probabilistic accident consequence codes, MACCS and COSYMA, completed in 1990, estimate the risks presented by nuclear installations based on postulated frequencies and magnitudes of potential accidents. In 1991, the US Nuclear Regulatory Commission (NRC) and the Commission of the European Communities (CEC) began a joint uncertainty analysis of the two codes. The objective was to develop credible and traceable uncertainty distributions for the input variables of the codes. Expert elicitation, developed independently, was identified as the best technology available for developing a library of uncertainty distributions for the selected consequence parameters. The study was formulated jointly and was limited to the current code models and to physical quantities that could be measured in experiments. To validate the distributions generated for the wet deposition input variables, samples were taken from these distributions and propagated through the wet deposition code model along with the Gaussian plume model (GPM) implemented in the MACCS and COSYMA codes. Resulting distributions closely replicated the aggregated elicited wet deposition distributions. Project teams from the NRC and CEC cooperated successfully to develop and implement a unified process for the elaboration of uncertainty distributions on consequence code input parameters. Formal expert judgment elicitation proved valuable for synthesizing the best available information. Distributions on measurable atmospheric dispersion and deposition parameters were successfully elicited from experts involved in the many phenomenological areas of consequence analysis. This volume is the second of a three-volume document describing the project and contains two appendices describing the rationales for the dispersion and deposition data along with short biographies of the 16 experts who participated in the project

  1. Probabilistic accident consequence uncertainty analysis: Dispersion and deposition uncertainty assessment, main report

    Harper, F.T.; Young, M.L.; Miller, L.A. [Sandia National Labs., Albuquerque, NM (United States); Hora, S.C. [Univ. of Hawaii, Hilo, HI (United States); Lui, C.H. [Nuclear Regulatory Commission, Washington, DC (United States); Goossens, L.H.J.; Cooke, R.M. [Delft Univ. of Technology (Netherlands); Paesler-Sauer, J. [Research Center, Karlsruhe (Germany); Helton, J.C. [and others

    1995-01-01

    The development of two new probabilistic accident consequence codes, MACCS and COSYMA, was completed in 1990. These codes estimate the risks presented by nuclear installations based on postulated frequencies and magnitudes of potential accidents. In 1991, the US Nuclear Regulatory Commission (NRC) and the Commission of the European Communities (CEC) began a joint uncertainty analysis of the two codes. The ultimate objective of the joint effort was to develop credible and traceable uncertainty distributions for the input variables of the codes. Expert elicitation was identified as the best technology available for developing a library of uncertainty distributions for the selected consequence parameters. The study was formulated jointly and was limited to the current code models and to physical quantities that could be measured in experiments. Experts developed their distributions independently. To validate the distributions generated for the wet deposition input variables, samples were taken from these distributions and propagated through the wet deposition code model. Resulting distributions closely replicated the aggregated elicited wet deposition distributions. To validate the distributions generated for the dispersion code input variables, samples from the distributions and propagated through the Gaussian plume model (GPM) implemented in the MACCS and COSYMA codes. Project teams from the NRC and CEC cooperated successfully to develop and implement a unified process for the elaboration of uncertainty distributions on consequence code input parameters. Formal expert judgment elicitation proved valuable for synthesizing the best available information. Distributions on measurable atmospheric dispersion and deposition parameters were successfully elicited from experts involved in the many phenomenological areas of consequence analysis. This volume is the first of a three-volume document describing the project.

  2. Probabilistic accident consequence uncertainty analysis: Dispersion and deposition uncertainty assessment, main report

    The development of two new probabilistic accident consequence codes, MACCS and COSYMA, was completed in 1990. These codes estimate the risks presented by nuclear installations based on postulated frequencies and magnitudes of potential accidents. In 1991, the US Nuclear Regulatory Commission (NRC) and the Commission of the European Communities (CEC) began a joint uncertainty analysis of the two codes. The ultimate objective of the joint effort was to develop credible and traceable uncertainty distributions for the input variables of the codes. Expert elicitation was identified as the best technology available for developing a library of uncertainty distributions for the selected consequence parameters. The study was formulated jointly and was limited to the current code models and to physical quantities that could be measured in experiments. Experts developed their distributions independently. To validate the distributions generated for the wet deposition input variables, samples were taken from these distributions and propagated through the wet deposition code model. Resulting distributions closely replicated the aggregated elicited wet deposition distributions. To validate the distributions generated for the dispersion code input variables, samples from the distributions and propagated through the Gaussian plume model (GPM) implemented in the MACCS and COSYMA codes. Project teams from the NRC and CEC cooperated successfully to develop and implement a unified process for the elaboration of uncertainty distributions on consequence code input parameters. Formal expert judgment elicitation proved valuable for synthesizing the best available information. Distributions on measurable atmospheric dispersion and deposition parameters were successfully elicited from experts involved in the many phenomenological areas of consequence analysis. This volume is the first of a three-volume document describing the project

  3. Accident management insights from IPE's

    In response to the U.S. Nuclear Regulatory Commission's Generic Letter 88-20, each utility in the U.S.A. has undertaken a probabilistic severe accident study of each plant. This paper provides a high level summary of the generic PWR accident management insights that have been obtained from the IPE reports. More importantly, the paper details some of the limitations of the IPE studies with respect to accident management. The IPE studies and the methodology used was designed to provide a best estimate of the potential for a severe accident and/or for severe consequences from a core damage accident. The accepted methodology employs a number of assumptions to make the objective attainable with a reasonable expenditure of resources. However, some of the assumptions represent limitations with respect to developing an accident management program based solely on the IPE and its results. (author)

  4. A review of the Melcor Accident Consequence Code System (MACCS): Capabilities and applications

    MACCS was developed at Sandia National Laboratories (SNL) under U.S. Nuclear Regulatory Commission (NRC) sponsorship to estimate the offsite consequences of potential severe accidents at nuclear power plants (NPPs). MACCS was publicly released in 1990. MACCS was developed to support the NRC's probabilistic safety assessment (PSA) efforts. PSA techniques can provide a measure of the risk of reactor operation. PSAs are generally divided into three levels. Level one efforts identify potential plant damage states that lead to core damage and the associated probabilities, level two models damage progression and containment strength for establishing fission-product release categories, and level three efforts evaluate potential off-site consequences of radiological releases and the probabilities associated with the consequences. MACCS was designed as a tool for level three PSA analysis. MACCS performs probabilistic health and economic consequence assessments of hypothetical accidental releases of radioactive material from NPPs. MACCS includes models for atmospheric dispersion and transport, wet and dry deposition, the probabilistic treatment of meteorology, environmental transfer, countermeasure strategies, dosimetry, health effects, and economic impacts. The computer systems MACCS is designed to run on are the 386/486 PC, VAX/VMS, E3M RISC S/6000, Sun SPARC, and Cray UNICOS. This paper provides an overview of MACCS, reviews some of the applications of MACCS, international collaborations which have involved MACCS, current developmental efforts, and future directions

  5. Performance of Core Exit Thermocouple for PWR Accident Management Action in Vessel Top Break LOCA Simulation Experiment at OECD/NEA ROSA Project

    Suzuki, Mitsuhiro; Takeda, Takeshi; Nakamura, Hideo

    Presented are experiment results of the Large Scale Test Facility (LSTF) conducted at the Japan Atomic Energy Agency (JAEA) with a focus on core exit thermocouple (CET) performance to detect core overheat during a vessel top break loss-of-coolant accident (LOCA) simulation experiment. The CET temperatures are used to start accident management (AM) action to quickly depressurize steam generator (SG) secondary side in case of core temperature excursion. Test 6-1 is the first test of the OECD/NEA ROSA Project started in 2005, simulating withdraw of a control rod drive mechanism penetration nozzle at the vessel top head. The break size is equivalent to 1.9% cold leg break. The AM action was initiated when CET temperature rose up to 623K. There was no reflux water fallback onto the CETs during the core heat-up period. The core overheat, however, was detected with a time delay of about 230s. In addition, a large temperature discrepancy was observed between the CETs and the hottest core region. This paper clarifies the reasons of time delay and temperature discrepancy between the CETs and heated core during boil-off including three-dimensional steam flows in the core and core exit. The paper discusses applicability of the LSTF CET performance to pressurized water reactor (PWR) conditions and a possibility of alternative indicators for earlier AM action than in Test 6-1 is studied by using symptom-based plant parameters such as a reactor vessel water level detection.

  6. Analyzing the loss of coolant accident in PWR nuclear reactors with elevation change in cold leg by RELAP5/MOD3.2 system code

    As, the Russian designed VVER-1000 reactor of the Bushehr Nuclear Power Plant by taking into account the change from German technology to that of Russian technology, and with the design of elevation change in the cold legs has been developed; therefore safety assessment of these systems for loss of coolant accident in elevation change in the cold legs and comparison results for non change elevation in the cold legs for a typical reactor (normal design of nuclear reactors) is the main important factor to be considered for the safe operation. In this article, the main objective is the simulation of the loss of coolant accident scenario by the RELAP5/MOD3.2 code in two different cases; first, the elevation change in the cold legs, and the second, non change in it. After comparing and analyzing these two code calculations the results have been generalized for a new design feature of Bushehr reactor. The design and simulation of the elevation change in the cold legs process with RELAP5/MOD3.2 code for PWR reactor is performed for the first time in the country, where it is introducing several important results in this respect

  7. Research activities about the radiological consequences of the Chernobyl NPS accident and social activities to assist the sufferers by the accident

    The 12th anniversary is coming soon of the accident at the Chernobyl nuclear power station in the former USSR on April 26, 1986. Many issues are, however, still unresolved about the radiological impacts on the environment and people due to the Chernobyl accident. This report contains the results of an international collaborative project about the radiological consequences of the Chernobyl accident, carried out from November 1995 to October 1997 under the research grant of the Toyota foundation. Collaborative works were promoted along with the following 5 sub-themes: 1) General description of research activities in Russia, Belarus and Ukraine concerning the radiological consequences of the accident. 2) Investigation of the current situation of epidemiological studies about Chernobyl in each affected country. 3) Investigation of acute radiation syndrome among inhabitants evacuated soon after the accident from the 30 km zone around the Chernobyl NPS. 4) Overview of social activities to assist the sufferers by the accident in each affected country. 5) Preparation of special reports of interesting studies being carried out in each affected country. The 27 papers are indexed individually. (J.P.N.)

  8. Assessment of Radiological and Economic Consequences of a Hypothetical Accident for ETRR-2, Egypt Utilizing COSYMA Code

    A comprehensive probabilistic study of an accident consequence assessment (ACA) for loss of coolant accident (LOCA) has accomplished to the second research reactor ETRR-2, located at Inshas Nuclear Research Center, Cairo, Egypt. PC-COSYMA, developed with the support of European Commission, has adopted to assess the radiological and economic consequences of a proposed accident. The consequences of the accident evaluated in case of early and late effects. The effective doses and doses in different organs carried out with and without countermeasures. The force mentioned calculations were required the following studies: the core inventory due to the hypothetical accident, the physical parameters of the source term, the hourly basis meteorological parameters for one complete year, and the population distribution around the plant. The hourly stability conditions and height of atmospheric boundary layers (ABL) of the concerned site were calculated. The results showed that, the nuclides that have short half-lives (few days) give the highest air and ground concentrations after the accident than the others. The area around the reactor requires the early and late countermeasures action after the accident especially in the downwind sectors. Economically, the costs of emergency plan are effectively high in case of applying countermeasures but countermeasures reduce the risk effects

  9. Techniques and decision making in the assessment of off-site consequences of an accident in a nuclear facility

    This Guide is intended to complement the IAEA's existing technical guidance on emergency planning and preparedness by providing information and practical guidance related to the assessment of off-site consequences of an accident in a nuclear or radioactive materials installation and to the decision making process in implementing protective measures. This Guide contains information on emergency response philosophy, fundamental factors affecting accident consequences, principles of accident assessment, data acquisition and handling, systems, techniques and decision making principles. Many of the accident assessment concepts presented are considerably more advanced than some of those that now pertain in most countries. They could, if properly interpreted, developed and applied, significantly improve emergency response in the early and intermediate phases of an accident. Furthermore, they are considered to be applicable to a broad range of serious nuclear accidents and radiological emergencies. The extent of their application is governed by both the scale of the accident and by the availability of preplanned resources for accident assessment and emergency response. 68 refs, 28 figs, 14 tabs

  10. Regulatory research of the PWR severe accident information needs and instrumentation availability for hydrogen control and management

    Park, Jae-Hong; Park, Gun-Chul; Suh, Kune Y.; Kang, Yun-Moon; Lee, Un-Jang; Oh, Se-Chul; Lee, Jin-Yong [Seoul Nationl Univ., Seoul (Korea, Republic of)

    1998-03-15

    During the current research period, we have set forth the methodology for identification of a severe accident, developed a framework for hydrogen management decision trees, and analyzed the literature on hydrogen management and experimental data for hydrogen bum. Specifically, we have summarized me results for information needs in a severe accident obtained in the U.S. and other countries, and applied the methodology to the reference plant YGN 3 and 4 as part of severe accident management. We have also examined the existing instruments in terms of their availability and survivability during a severe accident, and identified additionally needed information needs and instruments. We have identified dominant accident sequences for me reference plant YGN 3 and 4 to construct decision trees, and extracted available data from the IPE study of the plant. Based upon the data we have performed preliminary study on the decision tree and decision node. Last, we have examined various mechanisms for hydrogen generation and reIevant experimental data to predict me amount of hydrogen generation and governing factors in me process. We have also reviewed the hydrogen generation related models in the severe accident analysis.

  11. Regulatory research of the PWR severe accident information needs and instrumentation availability for hydrogen control and management

    During the current research period, we have set forth the methodology for identification of a severe accident, developed a framework for hydrogen management decision trees, and analyzed the literature on hydrogen management and experimental data for hydrogen bum. Specifically, we have summarized me results for information needs in a severe accident obtained in the U.S. and other countries, and applied the methodology to the reference plant YGN 3 and 4 as part of severe accident management. We have also examined the existing instruments in terms of their availability and survivability during a severe accident, and identified additionally needed information needs and instruments. We have identified dominant accident sequences for me reference plant YGN 3 and 4 to construct decision trees, and extracted available data from the IPE study of the plant. Based upon the data we have performed preliminary study on the decision tree and decision node. Last, we have examined various mechanisms for hydrogen generation and reIevant experimental data to predict me amount of hydrogen generation and governing factors in me process. We have also reviewed the hydrogen generation related models in the severe accident analysis

  12. Development of A Compact Severe Accident Simulator for PWR Nuclear Power Plants%压水堆核电站严重事故紧凑型仿真机开发

    唐钢; 张森如; 江光明; 傅霄华

    2001-01-01

    为了缓解压水堆核电站可能发生的严重事故的后果,也为了满足安全分析工程师和概率风险评价人员的需求,并在与国际原子能机构合作框架协议内,研制开发了紧凑型的严重事故仿真分析机 MELSIM-PC。该仿真系统主要由仿真核心程序、同步通讯程序、人机界面程序等几个部分组成,可以工作在一台普通的微型计算机上,成功地实现 MELCOR程序变量的运行数据库管理、电站动态图形显示、仿真计算控制、再启动和仿真重演等重要功能。%In order to alleviate the consequence of a possible severe accident in PWR Nuclear Power Plants and in response to the demands of safety analysis engineers and Probabilistic Safety Assessment(PSA) specialists,a compact severe accident simulator has been developed under an IAEA TC project.The PC-based simulator consists of the database engine MELCOR code,the man-machine interface modules MANAGER & DISPLAY,the communication module SERVER and the supplementary modules.It can be used successfully to realize some very important functions,such as the variable database management of MELCOR code,the plant mimic screens,simulation computation control,restart and replay,etc.

  13. Reactor safety study. An assessment of accident risks in U.S. commercial nuclear power plants. Appendix VI. Calculation of reactor accident consequences

    Information is presented concerning the radioactive releases from the containment following accidents; radioactive inventory of the reactor core; atmospheric dispersion; reactor sites and meteorological data; radioactive decay and deposition from plumes; finite distance of plume travel; dosimetric models; health effects; demographic data; mitigation of radiation exposure; economic model; and calculated results with consequence model

  14. Analysis of a rod withdrawal in a PWR core with the neutronic- thermalhydraulic coupled code RELAP/PARCS and RELAP/VALKIN

    The Reactor Ejection Accident (REA) belongs to the Reactor Initiated Accidents (RIA) category of accidents and it is part of the licensing basis accident analyses required for pressure water reactors (PWR). The REA at hot zero power (HZP) is characterized by a single rod ejection from a core position with a very low power level. The evolution consists basically of a continuous reactivity insertion. The main feature limiting the consequences of the accident in a PWR is the Doppler Effect. To check the performance of the coupled code RELAP5/PARCS2.5 and RELAP5/VALKIN a REA in Trillo NPP is simulated. These analyses will allow knowing more accurately the PWR real plant phenomenology in the RIA most limiting conditions. (authors)

  15. Radiological consequences of a propagated fire accident in a radiochemical separations facility

    A radiological consequence analysis of a propagated fire accident in a Savannah River Site (SRS) radiochemical separations facility has been performed. This analysis supports the safety documentation for the SRS plutonium reprocessing facility. Included are the evaluation of the doses resulting from the exposure to the radioactive airborne release for co-located facility worker and the off-site individual receptors. Atmospheric dispersion calculations using qualified five-year (1987-1991) meteorological data were performed with the computer code AXAIR89Q, a validated computer code for radiological dose calculations. Radioactive source term estimates and assumptions of material composition and isotope distribution were based on existing permissible storage levels as defined in approved safety documentation. The fire accident scenario assumes that the fire propagates in the entire facility on four structural levels. Approximately 97% of the radioactive materials released occurs from levels three and four of the facility, which are not included in the ventilation pathway to the sand trap filter. Radiological analysis results indicate that the doses to co-located worker and off-site individual receptors are equal to 4.4 rem and 3.3 rem, respectively. Accident mitigators that were identified include provision for filtration capacity from levels three and four of the facility, and relocation of stored radioactive materials. Provision for filtration capacity would reduce the source term from an unfiltered activity of 53.6 Ci to a filtered activity of 2.0 Ci. Relocation of stored radioactive materials would result in a source term reduction from 53.6 Ci to 20 Ci. Limitations exist, however, that may make implementation of the identified mitigators difficult or prohibitive

  16. Modeling in fast dynamics of accidents in the primary circuit of PWR type reactors; Modelisation en dynamique rapide d'accidents dans le circuit primaire des reacteurs a eau pressurisee

    Robbe, M.F

    2003-12-01

    Two kinds of accidents, liable to occur in the primary circuit of a Pressurized Water Reactor and involving fast dynamic phenomena, are analyzed. The Loss Of Coolant Accident (LOCA) is the accident used to define the current PWR. It consists in a large-size break located in a pipe of the primary circuit. A blowdown wave propagates through the circuit. The pressure differences between the different zones of the reactor induce high stresses in the structures of the lower head and may degrade the reactor core. The primary circuit starts emptying from the break opening. Pressure decreases very quickly, involving a large steaming. Two thermal-hydraulic simulations of the blowdown phase of a LOCA are computed with the Europlexus code. The primary circuit is represented by a pipe-model including the hydraulic peculiarities of the circuit. The main differences between both computations concern the kind of reactor, the break location and model, and the initialization of the accidental operation. Steam explosion is a hypothetical severe accident liable to happen after a core melting. The molten part of the core (called corium) falls in the lower part of the reactor. The interaction between the hot corium and the cold water remaining at the bottom of the vessel induces a massive and violent vaporization of water, similar to an explosive phenomenon. A shock wave propagates in the vessel. what can damage seriously the neighbouring structures or drill the vessel. This work presents a synthesis of in-vessel parametrical studies carried out with the Europlexus code, the linkage of the thermal-hydraulic code Mc3d dedicated to the pre-mixing phase with the Europlexus code dealing with the explosion, and finally a benchmark between the Cigalon and Europlexus codes relative to the Vulcano mock-up. (author)

  17. Analysis for mechanical consequences of a core disruptive accident in Prototype Fast Breeder Reactor

    The mechanical consequences of a core disruptive accident (CDA) in a fast breeder reactor are described. The consequences are development of deformations and strains in the vessels, intermediate heat exchangers (IHX) and decay heat exchangers (DHX), impact of sodium slug on the bottom surface of the top shield, sodium release to reactor containment building through top shield penetrations, sodium fire and consequent temperature and pressure rise in reactor containment building (RCB). These are quantified for 500 MWe Prototype Fast Breeder Reactor (PFBR) for a CDA with 100 MJ work potential. The results are validated by conducting a series of experiments on 1/30 and 1/13 scaled down models with increasing complexities. Mechanical energy release due to nuclear excursion is simulated by chemical explosion of specially developed low density explosive charge. Based on these studies, structural integrity of primary containment, IHX and DHX is demonstrated. The sodium release to RCB is 350 kg which causes pressure rise of 12 kPa in RCB. (author)

  18. Analysis of uncertainties caused by the atmospheric dispersion model in accident consequence assessments with UFOMOD

    Various techniques available for uncertainty analysis of large computer models are applied, described and selected as most appropriate for analyzing the uncertainty in the predictions of accident consequence assessments. The investigation refers to the atmospheric dispersion and deposition submodel (straight-line Gaussian plume model) of UFOMOD, whose most important input variables and parameters are linked with probability distributions derived from expert judgement. Uncertainty bands show how much variability exists, sensitivity measures determine what causes this variability in consequences. Results are presented as confidence bounds of complementary cumulative frequency distributions (CCFDs) of activity concentrations, organ doses and health effects, partially as a function of distance from the site. In addition the ranked influence of the uncertain parameters on the different consequence types is shown. For the estimation of confidence bounds it was sufficient to choose a model parameter sample size of n (n=59) equal to 1.5 times the number of uncertain model parameters. Different samples or an increase of sample size did not change the 5%-95% - confidence bands. To get statistically stable results of the sensitivity analysis, larger sample sizes are needed (n=100, 200). Random or Latin-hypercube sampling schemes as tools for uncertainty and sensitivity analyses led to comparable results. (orig.)

  19. The new program system UFOMOD to assess the consequences of nuclear accidents

    The program system UFOMOD is a completely new accident consequence assessment (ACA) code. Its structure and modelling is based on the experience gained from applications of the old UFOMOD code during and after the German Risk Study - Phase A, the results of scientific investigations performed within both the ongoing Phase B and the CEC-Project MARIA, and the requirements resulting from the extended use of ACAs to help in decision making. One of the most important improvements is the introduction of different trajectory models for describing atmospheric dispersion in the near range and at larger distances. Protective actions and countermeasures modelling takes into account recommendations of international commissions. The dosimetric models contain completely new age-, sex- and time-dependent data of dose-conversion factors for external and internal radiation; the ingestion pathway is modelled to consider seasonal dependencies. New dose-risk-relationships for stochastic and non-stochastic health effects are implemented; a special algorithm developed for ACA codes allows individual and collective leukemia and cancer risks to be presented as a function of time after the accident. According to the modular structure of the new UFOMOD program system, an easy access to parameter values and the results of the various submodels exists what facilitates sensitivity and uncertainty analyses

  20. The program system UFOMOD for assessing the consequences of nuclear accidents

    The programm system UFOMOD is a completely new accident consequence assessment (ACA) code. Its structure and modelling is based on the experience gained from applications of the old UFOMOD code during and after the German Risk Study - Phase A, the results of scientific investigations performed within the ongoing Phase B and the CEC-project MARIA, and the requirements resulting from the extended use of ACAs to help in decision-making. One of the most important improvements is the introduction of different trajecotry models for describing atmospheric dispersion in the near range and at larger distances. Emergency actions and countermeasures modelling takes into account recommendations of international commissions. The dosimetric models contain completely new age-, sex- and time-dependent data of dose-conversion factors for external and internal radiation; the ingestion pathway is modelled to consider seasonal dependencies. New dose-risk-relationships for stochastic and non-stochastic health effects are implemented; a special algorithm developed for ACA codes allows individual and collective leukemia and cancer risks to be presented as a function of time after the accident. According to the modular structure of the new program system UFOMOD, an easy access to parameter values and the results of the various submodels exists what facilitates sensitivity and uncertainty analyses. (orig.)

  1. Agroindustrial production sphere - radiological consequences of the Chernobyl accident and the chief protective measures

    As a result of the Chernobyl accident, fallout of radionuclides has occurred on farm lands, and the contaminated production of the agroindustrial complex has become a source of additional irradiation of the population. The contribution of the irradiation associated with the consumption of locally produced food products was quite significant, and led to the implementation of protective measures in the agroindustrial production sphere. It should be noted that irradiation of people owing to the consumption of contaminated agricultural products is more easily regulated than external irradiation. For this reason, the decrease in the total dose load is largely determined by the possibilities of restricting the internal irradiation dose to the population from the consumption of food products. The paper discusses radiological conditions in the agroindustrial production sphere in the region of the accident; intake of radionuclides by agricultural plants through leaves; distribution and form of 137Cs in soils; uptake of radionuclides by plants from the soil, animal husbandry aspects of the migration of radionuclides and their biological action; and organizational measures of the USSR for mitigating the consequences

  2. Chernobyl NPP accident consequences cleaning up participants in Ukraine -health status epidemiologic study main results

    The Epidemiologic Studies System for Chernobyl NPP Accident consequences cleaning up participants (CNPP ACCP) health status was worked out and than improving in Ukraine after the CNPP Accident. The State Register of Ukraine both with several other Registers are the organizational, methodological and informational basis here. The ACCP health status worsening ,-was registered in dynamics through the post-accidental period i.e. the nervous system, digestive system, blood circulation system, respiratory system, bone-muscular system, endocrine and genitourinary systems chronic non-tumoral pathology both with mental disorders amount increase. In cohort study the differences of morbidity formation were fixed among emergency workers with different radiation exposure doses. The dependence of leukemia morbidity on presence in 30-km zone duration was noticed, it's access manifested 5 years after the participance in ACC. The ACCP disablement increase with main reason of general somatic diseases, and annual mortality growth are registered. But that doesn't exceed the mortality rate among population of working age in Ukraine

  3. A dynamic food-chain model and program for predicting the radiological consequences of nuclear accident

    A dynamic food-chain model and program, DYFOM-95, for predicting the radiological consequences of nuclear accident has been developed, which is not only suitable to the West food-chain but also to Chinese food chain. The following processes, caused by accident release which will make an impact on radionuclide concentration in the edible parts of vegetable are considered: dry and wet deposition interception and initial retention, translocation, percolation, root uptake and tillage. Activity intake rate of animals, effects of processing and activity intake of human through ingestion pathway are also considered in calculations. The effects of leaf area index LAI of vegetable are considered in dry deposition model. A method for calculating the contribution of rain with different period and different intensity to total wet deposition is established. The program contains 1 main code and 5 sub-codes to calculate dry and wet deposition on surface of vegetable and soil, translocation of nuclides in vegetable, nuclide concentration in the edible parts of vegetable and in animal products and activity intake of human and so on. (24 refs., 9 figs., 11 tabs.)

  4. Agro-industrial sphere-radiological consequence of Chernobyl accident and major safety measures

    The early spring radionuclide fall as a consequence of Chernobyl accident caused air contamination of aerial part of agriculture crop - winter crops, natural and seeded permanent grasses. For other plants the soil and wind contamination are prevailing. After radionuclide fall most of them are concentrated in the soil upper layer. Radionuclide uptake depends on the ratio of their concentration in soils, that is varied due to the soil type. The soil development results in variation of radionuclide migration in the crop. In cattle production two main trends are the most significant: estimation of food contamination (primarily of milk and meat) and analysis of physiological state of animals near NPP. Organization and land-improvement measures permitting a stable agro-industrial functionaing on the contaminated territory are considered

  5. Introductory remarks by the Chairman. [Session 1: Environmental and health consequences of the Chernobyl accident

    Many scientists as well as representatives from UN organizations and governments of affected regions participated in the work of the Chernobyl Forum. Several meetings of the Forum were necessary to initiate the work and monitor the progress of the expert groups. Two expert groups formulated comprehensive reports - one on environmental issues, organized by the IAEA, and one on health issues, organized by the WHO. Experts from throughout the world were invited to contribute to these evaluations. The representatives of governments and the staff of international organizations then reviewed the results of these groups to be sure that the reviews were complete and the evaluations reasonable, so that they could serve as the basis for consensus agreements and effective recommendations for further dealing with the consequences of the accident

  6. Accidental beam loss in superconducting accelerators: Simulations, consequences of accidents and protective measures

    The consequences of an accidental beam loss in superconducting accelerators and colliders of the next generation range from the mundane to rather dramatic, i.e., from superconducting magnet quench, to overheating of critical components, to a total destruction of some units via explosion. Specific measures are required to minimize and eliminate such events as much as practical. In this paper we study such accidents taking the Superconducting Supercollider complex as an example. Particle tracking, beam loss and energy deposition calculations were done using the realistic machine simulation with the Monte-Carlo codes MARS 12 and STRUCT. Protective measures for minimizing the damaging effects of prefire and misfire of injection and extraction kicker magnets are proposed here

  7. Health effects models for off-site radiological consequence analysis on nuclear reactor accidents (II)

    Homma, Toshimitsu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment; Takahashi, Tomoyuki [Kyoto Univ., Kumatori, Osaka (Japan). Research Reactor Inst; Yonehara, Hidenori [National Inst. of Radiological Sciences, Chiba (Japan)] [eds.

    2000-12-01

    This report is a revision of JAERI-M 91-005, 'Health Effects Models for Off-Site Radiological Consequence Analysis of Nuclear Reactor Accidents'. This revision provides a review of two revisions of NUREG/CR-4214 reports by the U.S. Nuclear Regulatory Commission which is the basis of the JAERI health effects models and other several recent reports that may impact the health effects models by international organizations. The major changes to the first version of the JAERI health effects models and the recommended parameters in this report are for late somatic effects. These changes reflect recent changes in cancer risk factors that have come from longer followup and revised dosimetry in major studies on the Japanese A-bomb survivors. This report also provides suggestions about future revisions of computational aspects on health effects models. (author)

  8. Health effects models for off-site radiological consequence analysis on nuclear reactor accidents (II)

    This report is a revision of JAERI-M 91-005, 'Health Effects Models for Off-Site Radiological Consequence Analysis of Nuclear Reactor Accidents'. This revision provides a review of two revisions of NUREG/CR-4214 reports by the U.S. Nuclear Regulatory Commission which is the basis of the JAERI health effects models and other several recent reports that may impact the health effects models by international organizations. The major changes to the first version of the JAERI health effects models and the recommended parameters in this report are for late somatic effects. These changes reflect recent changes in cancer risk factors that have come from longer followup and revised dosimetry in major studies on the Japanese A-bomb survivors. This report also provides suggestions about future revisions of computational aspects on health effects models. (author)

  9. The radiological consequences in the USSR from the Chernobyl accident: Description of the scheme of implementation

    After October 1989 the Government of the USSR requested the IAEA to organize an international assessment of the 'concept which the USSR has evolved to enable the population to live safely in areas affected by radioactive contamination following the Chernobyl accident, and an evaluation of the effectiveness of the steps taken in these areas to safeguard the health of the population'. The IAEA responded positively to this request for special assistance. The IAEA is carried out an extensive international project involving over 100 experts who assessed the human health and environmental consequences in the affected areas of Byelorussia, the Ukraine, and the Russian Federation, and evaluate measures taken by Soviet authorities to protect the population and the environment

  10. Probabilistic Accident Consequence Uncertainty Analysis of the Dose Calculations Module in the COSYMA Package (invited paper)

    Uncertainty analysis of the dose calculation module of the COSYMA accident consequence assessment code has been undertaken, involving the following steps: (1) Expert judgement techniques were applied to assess uncertainties in measurable parameters determining external and internal doses. (2) The data obtained were used to calculate distributions on the dose quantities required as code input parameters. (3) The effect of uncertainties in dose quantities was analysed for a range of COSYMA end points, including the extent of countermeasures and incidences of early and late health effects, and the most important uncertainties were identified for inclusion in an overall uncertainty analysis of COSYMA. Parameters identified as making the largest contributions to uncertainty included external doses and location factors, residence times of materials on skin, breathing rates, and respiratory tract deposition and retention parameters, for the extent of countermeasures and early health effects, and caesium and iodine retention parameters for late effects. (author)

  11. Uncertainty analysis with a view towards applications in accident consequence assessments

    Since the publication of the US-Reactor Safety Study WASH-1400 there has been an increasing interest to develop and apply methods which allow to quantify the uncertainty inherent in probabilistic risk assessments (PRAs) and accident consequence assessments (ACAs) for installations of the nuclear fuel cycle. Research and development in this area is forced by the fact that PRA and ACA are more and more used for comparative, decisive and fact finding studies initiated by industry and regulatory commissions. This report summarizes and reviews some of the main methods and gives some hints to do sensitivity and uncertainty analyses. Some first investigations aiming at the application of the method mentioned above to a submodel of the ACA-code UFOMOD (KfK) are presented. Sensitivity analyses and some uncertainty studies an important submodel of UFOMOD are carried out to identify the relevant parameters for subsequent uncertainty calculations. (orig./HP)

  12. On the potential limitation of radiological source term releases considering severe core accidents in future PWR plants

    Future nuclear power plants should be so safe that even in case of such a severe accident there will be no need of drastic external disaster control measures such as an evacuation or resettlement of the population from the vicinity of a nuclear power plant. It is shown by the example of a future 1400 MWe pressurized water reactor plant that this goal can be attained in principle by providing a double containment with the annulus vented via an appropriate emergency standby filter. Within the framework of disaster prevention a set of parameters for accident conditions is elaborated under which the lower levels of intervention for evacuation are not attained. (orig./HP)

  13. Probabilistic accident consequence uncertainty analysis: Food chain uncertainty assessment. Volume 2: Appendices

    This volume is the second of a two-volume document that summarizes a joint project by the US Nuclear Regulatory and the Commission of European Communities to assess uncertainties in the MACCS and COSYMA probabilistic accident consequence codes. These codes were developed primarily for estimating the risks presented by nuclear reactors based on postulated frequencies and magnitudes of potential accidents. This two-volume report, which examines mechanisms and uncertainties of transfer through the food chain, is the first in a series of five such reports. A panel of sixteen experts was formed to compile credible and traceable uncertainty distributions for food chain transfer that affect calculations of offsite radiological consequences. Seven of the experts reported on transfer into the food chain through soil and plants, nine reported on transfer via food products from animals, and two reported on both. The expert judgment elicitation procedure and its outcomes are described in these volumes. This volume contains seven appendices. Appendix A presents a brief discussion of the MAACS and COSYMA model codes. Appendix B is the structure document and elicitation questionnaire for the expert panel on soils and plants. Appendix C presents the rationales and responses of each of the members of the soils and plants expert panel. Appendix D is the structure document and elicitation questionnaire for the expert panel on animal transfer. The rationales and responses of each of the experts on animal transfer are given in Appendix E. Brief biographies of the food chain expert panel members are provided in Appendix F. Aggregated results of expert responses are presented in graph format in Appendix G

  14. Probabilistic accident consequence uncertainty analysis: Food chain uncertainty assessment. Volume 2: Appendices

    Brown, J. [National Radiological Protection Board (United Kingdom); Goossens, L.H.J.; Kraan, B.C.P. [Delft Univ. of Technology (Netherlands)] [and others

    1997-06-01

    This volume is the second of a two-volume document that summarizes a joint project by the US Nuclear Regulatory and the Commission of European Communities to assess uncertainties in the MACCS and COSYMA probabilistic accident consequence codes. These codes were developed primarily for estimating the risks presented by nuclear reactors based on postulated frequencies and magnitudes of potential accidents. This two-volume report, which examines mechanisms and uncertainties of transfer through the food chain, is the first in a series of five such reports. A panel of sixteen experts was formed to compile credible and traceable uncertainty distributions for food chain transfer that affect calculations of offsite radiological consequences. Seven of the experts reported on transfer into the food chain through soil and plants, nine reported on transfer via food products from animals, and two reported on both. The expert judgment elicitation procedure and its outcomes are described in these volumes. This volume contains seven appendices. Appendix A presents a brief discussion of the MAACS and COSYMA model codes. Appendix B is the structure document and elicitation questionnaire for the expert panel on soils and plants. Appendix C presents the rationales and responses of each of the members of the soils and plants expert panel. Appendix D is the structure document and elicitation questionnaire for the expert panel on animal transfer. The rationales and responses of each of the experts on animal transfer are given in Appendix E. Brief biographies of the food chain expert panel members are provided in Appendix F. Aggregated results of expert responses are presented in graph format in Appendix G.

  15. Critique of and Limitations on the Use of Expert Judgements in Accident Consequence Uncertainty Analysis (invited paper)

    Accident consequence models are designed primarily to be used in support of siting and licensing decisions. To use these models, the analyst inevitably requires some input from experts. Equally, to understand the implication of the models, the analyst needs to explore their sensitivity to the inputs and uncertainty analysis is a key tool in doing this. In this paper, the interplay between these two aspects of the use of accident consequence models is considered, paying particular attention to issues and limitations that require further research in the coming years. (author)

  16. Development of simplified 1D and 2D models for studying a PWR lower head failure under severe accident conditions

    In the study of severe accidents of nuclear pressurized water reactors, the scenarios that describe the relocation of significant quantities of liquid corium at the bottom of the lower head are investigated from the mechanical point of view. In these scenarios, the risk of a breach and the possibility of a large quantity of corium being released from the lower head exist. This may lead to direct heating of the containment or outer vessel steam explosion. These issues are important due to their early containment failure potential. Since the TMI-2 accident, many theoretical and experimental investigations, relating to lower head mechanical behaviour under severe thermo-mechanical loading in the event of a core meltdown accident have been performed. IRSN participated actively in the one-fifth scale USNRC/SNL LHF and OECD LHF (OLHF) programs. Within the framework of these programs, two simplified models were developed by IRSN: the first is a simplified 1D approach based on the theory of pressurized spherical shells and the second is a simplified 2D model based on the theory of shells of revolution under symmetric loading. The mathematical formulation of both models and the creep constitutive equations used are presented in detail in this paper. The corresponding models were used to interpret some of the OLHF program experiments and the calculation results were quite consistent with the experimental data. The two simplified models have been used to simulate the thermo-mechanical behaviour of a 900 MWe pressurized water reactor lower head under severe accident conditions leading to failure. The average transient heat flux produced by the corium relocated at the bottom of the lower head has been determined using the IRSN HARAR code. Two different methods, both taking into account the ablation of the internal surface, are used to determine the temperature profiles across the lower head wall and their effect on the time to failure is discussed. Using these simplified models

  17. MELCOR 1.8.3 application to NUPEC M-7-1 test (ISP-35) and two hydrogen severe accident scenarios in a typical PWR plant

    Combustion of the hydrogen released to the containment during a severe accident is one of the issues to establish the real threats to the third barrier integrity in nuclear power facilities. Computational efforts on management procedures, such as the containment spray operation, are being addressed at the CTN-UPM to cope with the problem. On top of this, studies about in-containment hydrogen distribution and combustion are currently carried out with the codes MELCOR 1.8.3 and ESTER 1.0-RALOC 2.2. In this study, MELCOR 1.8.3 has been validated against the NUPEC M-7-1 Test, which already showed in 1993 that a good agreement was reached out when the previous MELCOR 1.8.2 calculations were performed regarding to the helium distribution throughout the facility. Nevertheless, some discrepancies were detected when analysing wall and atmosphere temperatures. Generally, well-mixed atmosphere scenarios, in which the role played by the containment water spraying is of the major importance, appear when such a mechanism promotes the onset of convection driven flow patterns that rapidly homogenize the gas properties. The purpose of the new MELCOR 1.8.3 assessment is to take advantage of the newest implemented models to obtain a more realistic thermalhydraulics simulation. A variation case was also performed to highlight the influence of water spray operation. In a second part of the study, insights coming from the previous work were used to apply MELCOR 1.8.3 models to a SBO severe accident scenario management in a commercial 2700 MWt 3-loop W PWR containment

  18. On the performance of an artificial bee colony optimization algorithm applied to the accident diagnosis in a PWR nuclear power plant

    Oliveira, Iona Maghali S. de; Schirru, Roberto; Medeiros, Jose A.C.C., E-mail: maghali@lmp.ufrj.b, E-mail: schirru@lmp.ufrj.b, E-mail: canedo@lmp.ufrj.b [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Coordenacao dos Programas de Pos-Graduacao de Engenharia. Programa de Engenharia Nuclear

    2009-07-01

    The swarm-based algorithm described in this paper is a new search algorithm capable of locating good solutions efficiently and within a reasonable running time. The work presents a population-based search algorithm that mimics the food foraging behavior of honey bee swarms and can be regarded as belonging to the category of intelligent optimization tools. In its basic version, the algorithm performs a kind of random search combined with neighborhood search and can be used for solving multi-dimensional numeric problems. Following a description of the algorithm, this paper presents a new event classification system based exclusively on the ability of the algorithm to find the best centroid positions that correctly identifies an accident in a PWR nuclear power plant, thus maximizing the number of correct classification of transients. The simulation results show that the performance of the proposed algorithm is comparable to other population-based algorithms when applied to the same problem, with the advantage of employing fewer control parameters. (author)

  19. On the performance of an artificial bee colony optimization algorithm applied to the accident diagnosis in a PWR nuclear power plant

    The swarm-based algorithm described in this paper is a new search algorithm capable of locating good solutions efficiently and within a reasonable running time. The work presents a population-based search algorithm that mimics the food foraging behavior of honey bee swarms and can be regarded as belonging to the category of intelligent optimization tools. In its basic version, the algorithm performs a kind of random search combined with neighborhood search and can be used for solving multi-dimensional numeric problems. Following a description of the algorithm, this paper presents a new event classification system based exclusively on the ability of the algorithm to find the best centroid positions that correctly identifies an accident in a PWR nuclear power plant, thus maximizing the number of correct classification of transients. The simulation results show that the performance of the proposed algorithm is comparable to other population-based algorithms when applied to the same problem, with the advantage of employing fewer control parameters. (author)

  20. Analysis of the behaviour of pressure and temperature of the containment of a PWR reactor, submitted to a postulated loss-of-coolant accident

    The main purpose of this work is to analyse the pressure and temperature behaviour of the metalic containment of a PWR building, submitted to a postulated loss-of-coolant accident (LOCA) caused by a double-ended rupture in the main line of the primary circuit. The scope of the study was directed to verify the Final Safety Analysis Report (FSAR) results for the integrity of the metalic containment of the Angra I power plant. The highest containment pressure peak for this unit is expected for a break in the suction line of one of the main pumps of the primary coolant. Using the same input data, our results are very similar to those presented in the FSAR which shows a reasonable equivalence between the two analytical models. Using as input data the results of a previous LOCA study at CNEN, which yields to more conservative boundary conditions than those presented by the FSAR, the pressure and temperature peak values determined by our model are quite larger than those presented by the cited Safety Report. (author)

  1. Modelisation of soluble aerosols behaviour in the atmosphere of a PWR nuclear reactor in case of accident

    After a short description of soluble aerosols accidental production in a PWR, a calculation model is given for physical properties of a gaz and steam mixture in a given atmosphere. Then the equilibrium of a saline drop with steam is studied. From the MASON equation, a calculation model is given for kinetic of volume variation of a saline drop and also a sensitivity study showing the little influence of the boundary layer on the drop surface, of the drop settling and of the thermodynamic conditions of the containment. As a numerical application, this condensation/evaporation model, and a simplified one with faster numerical resolution, is introduced in the AEROSOLS codes of the CEA-DEMT. The AEROSOLS/A2 suppose a log-normal distribution of the suspended particles in the containment. This application shows the very large sensitivity of the condensation depending on the moisture ratio inside the reactor building, and its primary importance on the behaviour of the aerosols. It is also shown that the simplified model gives a very little difference compared with the detailed model, and that the computation time is much more lower

  2. Health and environmental consequences of the Chernobyl nuclear power plant accident

    An assessment of the impact of the Chernobyl accident on the Northern Hemisphere is presented in this report. It relies heavily on the USSR report presented to the International Atomic Energy Agency. There are gaps in present knowledge and, in some areas, uncertainties may never be completely resolved. What is clearly apparent at this time, however, is that on a large regional scale, the estimates of collective dose have a reasonable level of confidence. The associated potential health impacts have also been projected, together with a range of estimates. A brief description of the tragic consequences to the heroic firefighting and rescue personnel is also provided, and valuable insights regarding acute exposures are developed. Much early effort was expended on estimation of the source term, especially for radiocesium and radioiodine. Several independent analyses are presented that are in reasonable agreement. Atmospheric transport of the radioactive material and its subsequent deposition provide a documented ''umbrella'' of the distributions that form the basic integration of this assessment. The estimates of radiological doses to selected Northern Hemisphere populations were employed in developing an integrated risk assessment of potential latent health effects using the most current models, parameters and risk coefficients. The estimates presented include lower- and upper-bound values, as well as the ''best'' or most realistic ranges. While many scientists believe that minuscule increases in risks to large populations are impossible to prove, it is essential that the magnitude of these possible risks be presented, if only to put an upper limit on the situation. It must be emphasized that while these are ''potential'' health effects, the values presented represent our best current assessment of the health and environmental detriment caused by the Chernobyl accident. 72 refs., 37 figs., 91 tabs

  3. Probabilistic Accident Consequence Uncertainty Analysis of the Early Health Effects Module in the COSYMA Package (invited paper)

    The accuracy of models that are used to calculate the risk from early health effects due to exposure to a large dose of radiation from radioactive materials has been investigated. Early health effects are radiation diseases that occur within six weeks after the exposure. The present investigation provides data needed for subsequent analysis of the accuracy of estimates of the risks from nuclear power plant accidents (accident consequence assessments). By means of a formal expert elicitation procedure, for a limited number of exposure cases, a set of data has been obtained that quantifies the accuracy of risk estimates for early health effects. These data have been implemented in the generic models for calculating the risk and the accuracy of the calculated risk. These generic models are currently applied in accident consequence assessments. (author)

  4. Study on the possible consequences of a severe accident in a Swiss nuclear power plant on the drinking water supply

    The study on the possible consequences of a severe accident in a Swiss nuclear power plant on the drinking water supply covers the following issues: estimation of possible source terms and radioactive materials release rates, airborne water contamination, water contamination by direct pollution, consequences for the drinking water supply, emergency measures in case of a drinking water contamination, routine surveillance of surface and ground water and improvement possibilities in nuclear power plants.

  5. Analysis of medico-biological consequences of ChNPP accident for liquidators-participants of the Russian scientific centre

    A base of medico-biological and dosimetric data was created for research workers of Kurchatov Institute, and Institute of nuclear reactors who participated in ChNPP accident mitigation. An attempt is made to analyze possible connection of medico-biological consequences with dose loads

  6. Application of natural adsorbents as decontamination agents for the elimination of the consequences of the Chernobyl reactor accident

    The scientific foundations of using natural adsorbents as ion exchangers,filtering media and adagulants for water purification ase presented. The results showing the efficiency of practical application of natural adsorbents for the decontamination of water, clothes, machinery, construction materials, etc. during the elimination of the consequences of the Chernobyl reactor accident in 1986-1987 are presented

  7. Chernobyl nuclear reactor accident fallout: Measurement and consequences. (Latest citations from the NTIS bibliographic database). Published Search

    The bibliography contains citations concerning the consequences of radioactive fallout from the Chernobyl nuclear reactor accident. Citations discuss radioactive monitoring, health hazards, and radiation dosimetry. Radiation contamination in the air, soil, vegetation, and food is examined. (Contains a minimum of 210 citations and includes a subject term index and title list.)

  8. Chernobyl nuclear reactor accident fallout: Measurement and consequences. (Latest citations from the NTIS Bibliographic database). Published Search

    The bibliography contains citations concerning the consequences of radioactive fallout from the Chernobyl nuclear reactor accident. Citations discuss radioactive monitoring, health hazards, and radiation dosimetry. Radiation contamination in the air, soil, vegetation, and food is examined. (Contains a minimum of 208 citations and includes a subject term index and title list.)

  9. Severe accidents: the primary and secondary bleed and feed procedures to prevent PWR high pressure core melting

    New strategies to cope with severe reactor accidents leading to core degradation and eventually to a release of large quantities of radioactive products into the environment, have been developed in several countries over the last few years. In order to reduce the probability and risk associated with such grave events, appropriate accident management measures have been defined. The most interesting procedures for the prevention of an irreversible deterioration of the plant status and the maintenance of the core in coolable conditions are the secondary and primary side Bleed and Feed measures. In fact, in case of loss of secondary heat sink accidents, these procedures aim either to recover the secondary side heat removal capability by depressurization of the steam generators or to remove the residual heat via the pressurizer valves. In this way the probability of core meltdown with high primary pressure is drastically reduced. Recent investigations on primary and secondary side Bleed and Feed interventions have already shown the high potentiality of this kind of actions in using systems such as feedwater storage tank, accumulators, fire fighting systems or mobile pumps. Since the use of these procedures is strongly dependent on the intervention logic and on the characteristics of the specific plant design, there is the need of carrying out accurate analyses to assess and optimize the intervention actions. This report sets itself a goal in defining a basis for the study of transients which can be handled with Bleed and Feed procedures, allowing in this respect future analyses of the Swiss PWRs. (author) 6 figs., 15 refs

  10. Neural network of Gaussian radial basis functions applied to the problem of identification of nuclear accidents in a PWR nuclear power plant

    Highlights: • It is presented a new method based on Artificial Neural Network (ANN) developed to deal with accident identification in PWR nuclear power plants. • Obtained results have shown the efficiency of the referred technique. • Results obtained with this method are as good as or even better to similar optimization tools available in the literature. - Abstract: The task of monitoring a nuclear power plant consists on determining, continuously and in real time, the state of the plant’s systems in such a way to give indications of abnormalities to the operators and enable them to recognize anomalies in system behavior. The monitoring is based on readings of a large number of meters and alarm indicators which are located in the main control room of the facility. On the occurrence of a transient or of an accident on the nuclear power plant, even the most experienced operators can be confronted with conflicting indications due to the interactions between the various components of the plant systems; since a disturbance of a system can cause disturbances on another plant system, thus the operator may not be able to distinguish what is cause and what is the effect. This cognitive overload, to which operators are submitted, causes a difficulty in understanding clearly the indication of an abnormality in its initial phase of development and in taking the appropriate and immediate corrective actions to face the system failure. With this in mind, computerized monitoring systems based on artificial intelligence that could help the operators to detect and diagnose these failures have been devised and have been the subject of research. Among the techniques that can be used in such development, radial basis functions (RBFs) neural networks play an important role due to the fact that they are able to provide good approximations to functions of a finite number of real variables. This paper aims to present an application of a neural network of Gaussian radial basis

  11. Study on the PWR Steam Generator Behavior with improved steam-driven aux feedwater system under prolonged SBO Accident

    The only available passive decay heat removal system of current PWRs is a turbine-driven auxiliary steam generator (SG) feedwater (TD-AFW) system. If a SG water level becomes too high, however, turbine blades could be damaged due to a large amount of becomes too high, however, turbine blades could be damaged due to a large amount of moisture in steam and the SG cooling capability would not be maintained any longer. Therefore, the SG water level should be controlled to prevent the turbine from being damaged during a Station Black-Out (SBO) accident. In this paper, an improved design feature is proposed to provide electric power for controlling SG water level when both off-site power and the emergency diesel generators are not available. There are additional SG level gauges and valve controllers to control the steam flow into the auxiliary turbine in an improved TD-AFW system. Electric power for this control system is provided by a small additional generator which is connected to the existing auxiliary turbine shaft. Using this new feature, decay heat cooling is available for 29 hours with only 1 condensate storage tank which is the water source of the AFW. Eventually, it is concluded that the improved TD-AFW system with an additional SG level controller and generator can avoid an early SG full level and continue long term cooling during a prolonged SBO accident

  12. A dynamic food-chain model and program for predicting the consequences of nuclear accident

    1998-01-01

    A dynamic food-chain model and program, DYFOM-95, forpredicting the radiological consequences of nuclear accident hasbeen developed, which is not only suitable to the West food-chainbut also to Chinese food chain. The following processes, caused byaccident release which will make an impact on radionuclideconcentration in the edible parts of vegetable are considered: dryand wet deposition interception and initial retention,translocation, percolation, root uptake and tillage. Activityintake rate of animals, effects of processing and activity intakeof human through ingestion pathway are also considered incalculations. The effects of leaf area index LAI of vegetable areconsidered in dry deposition model. A method for calculating thecontribution of rain with different period and different intensityto total wet deposition is established. The program contains 1 maincode and 5 sub-codes to calculate dry and wet deposition on surfaceof vegetable and soil, translocation of nuclides in vegetable,nuclide concentration in the edible parts of vegetable and inanimal products and activity intake of human and so on.

  13. Internal dose coefficients for off-site radiological consequence analysis of nuclear reactor accidents

    The OSCAAR computer code for use in probabilistic accident consequence assessment (Level 3PSA) developed at Japan Atomic Energy Research Institute has calculated dose to the public with internal dose conversion factors based on dosimetric models and biokinetic data provided in International Commission on Radiological Protection (ICRP) Publication 30. Since ICRP issued age-dependent biokinetic models for a limited set of radioisotopes are ICRP Publication 56, a new Human Respiratory Tract model, age-dependent biokinetic model for other radioisotopes and urinary and faecal excretion models were issued. ICRP has published age-dependent internal dose coefficients for a large set of radionuclides in its publications, but they provided only committed effective dose coefficients for inhalation and ingestion. Since OSCAAR estimated acute and late health effects for members of the public, it needs internal dose coefficients for specific tissues and organs in arbitrary integration times. This report describes a preprocessor code DSYS developed for use with OSCAAR for calculating inhalation and ingestion dose coefficients based on these new ICRP models. It also provides the internal dose coefficients for 54 radionuclides used in OSCAAR calculations. (author)

  14. Consequences of the Chernobyl accident for the natural and human environments

    In the ten years since the Chernobyl accident, an enormous amount of work has been done to assess the consequences to the natural and human environment. Although it is difficult to summarize such a large and varied field, some general conclusions can be drawn. This background paper includes the main findings concerning the direct impacts of radiation on the flora and fauna; the general advances of knowledge in the cycling of radionuclides in natural, seminatural and agricultural environments; some evaluation of countermeasures that were used; and a summary of the human radiation doses resulting from the environmental contamination. although open questions still remain, it can be concluded that: (1) at high radiation levels, the natural environment has shown short term impacts but any significant long term impacts remain to be seen; (2) effective countermeasures can be taken to reduce the transfer of contamination from the environment to humans but these are highly site specific and must be evaluated in terms of practicality as well as population does reduction; (3) the majority of the doses have already been received by the human population. If agricultural countermeasures are appropriately taken, the main source of future doses will be the gathering of food and recreational activities in natural and seminatural ecosystems

  15. Consequences of the Chernobyl accident for the natural and human environments

    Dreicer, M. [Lawrence Livermore National Lab., CA (United States); Aarkog, A. [Risoe National Lab., Roskilde (Denmark); Alexakhin, R. [Russian Inst. of Agricultural Radiology and Agroecology (Russian Federation); Anspaugh, L. [Lawrence Livermore National Lab., CA (United States); Arkhipov, N.P. [Scientific and Technical Centre of the RIA `Pripyat` (Ukraine); Johansson, K.-J. [Swedish Univ. of Agricultural Sciences, Uppsala (Sweden)

    1996-07-01

    In the ten years since the Chernobyl accident, an enormous amount of work has been done to assess the consequences to the natural and human environment. Although it is difficult to summarize such a large and varied field, some general conclusions can be drawn. This background paper includes the main findings concerning the direct impacts of radiation on the flora and fauna; the general advances of knowledge in the cycling of radionuclides in natural, seminatural and agricultural environments; some evaluation of countermeasures that were used; and a summary of the human radiation doses resulting from the environmental contamination. although open questions still remain, it can be concluded that: (1) at high radiation levels, the natural environment has shown short term impacts but any significant long term impacts remain to be seen; (2) effective countermeasures can be taken to reduce the transfer of contamination from the environment to humans but these are highly site specific and must be evaluated in terms of practicality as well as population does reduction; (3) the majority of the doses have already been received by the human population. If agricultural countermeasures are appropriately taken, the main source of future doses will be the gathering of food and recreational activities in natural and seminatural ecosystems.

  16. General situation of the radiological consequences of the Chernobyl accident in Ukraine

    Following the Chernobyl Nuclear Accident on April 26, 1986, epidemiological analyses of data point to impressive deterioration of the health of the people affected by radionuclide contamination in the environment. This deterioration of population health embraces a broad spectrum of diseases. Epidemiological prediction of the rate of thyroid cancer in children near Chernobyl seems strikingly compatible with a real increase. But there is a tendency to consider the morbidity augmentation as a result having been associated with the factors of non-radioactive origin (chemical compounds, heavy metals and mainly social-psychological syndrome development). The Chernobyl catastrophe has implied a heavy burden for Ukraine: pollution of air, water, soils and vegetation in all ecosystems, late radiological effects in the health of people, losses of arable land and forest, necessity of mass-evacuation from thousands of settlements in the contaminated regions, severe psychological shock for millions of people, and painful suffering of unexpected life tragedies. Eleven years after, this tragic event with its causes and consequence brings one to very important conclusions concerning moral aspects of human relations within the nuclear society, as well as interactions between the society and the environment. (J.P.N.)

  17. Review of the status of validation of the computer codes used in the severe accident source term reassessment study (BMI-2104). [PWR; BWR

    Kress, T. S. [comp.

    1985-04-01

    The determination of severe accident source terms must, by necessity it seems, rely heavily on the use of complex computer codes. Source term acceptability, therefore, rests on the assessed validity of such codes. Consequently, one element of NRC's recent efforts to reassess LWR severe accident source terms is to provide a review of the status of validation of the computer codes used in the reassessment. The results of this review is the subject of this document. The separate review documents compiled in this report were used as a resource along with the results of the BMI-2104 study by BCL and the QUEST study by SNL to arrive at a more-or-less independent appraisal of the status of source term modeling at this time.

  18. Radiological consequence analyses under severe accident conditions for the Advanced Neutron Source Reactor at the Oak Ridge National Laboratory

    This paper discusses salient aspects of methodology, assumptions, modeling of various features related to radiation exposure, and health consequences from source terms resulting from two conservatively scoped severe accident scenarios. Radiological consequences for a site-suitability scenario based on 10 CFR 100 guidelines also are presented. Consequences arising from severe accidents involving steaming pools and core-concrete interaction (CCI) events combined with several different containment configurations are presented. Results are presented in the form of mean cumulative values for prompt and latent cancer fatality estimates and related cumulative, complementary distribution functions as a function of distance from the reactor site. It is shown that the reactor-site-suitability risk goals are met by a large margin and that overall risk is dominated by early containment failure combined with CCI events

  19. Review of psychological consequences of nuclear accidents and empirical study on peoples reactions to radiation protection activities in an imagined situation

    The report consist of two parts: a review of studies on psychological consequences of nuclear and radiation accidents in population and an empirical study of peoples reactions to protection actions in an event of hypothetical accident. Review is based on research results from two nuclear reactor accidents (Three Mile Island 1979, Chernobyl 1986) and a radiation accident in Goiania, Brazil 1987. (53 refs, 2 figs.,7 tabs.)

  20. Assessment Of Source Term And Radiological Consequences For Design Basis Accident And Beyond Design Basis Accident Of The Dalat Nuclear Research Reactor

    The paper presents results of the assessment of source terms and radiological consequences for the Design Basis Accident (DBA) and Beyond Design Basis Accident (BDBA) of the Dalat Nuclear Research Reactor. The dropping of one fuel assembly during fuel handling operation leading to the failure of fuel cladding and the release of fission products into the environment was selected as a DBA for the analysis. For the BDBA, the introduction of a step positive reactivity due to the falling of a heavy block from the rotating bridge crane in the reactor hall onto a part of the platform where are disposed the control rod drives is postulated. The result of the radiological consequence analyses shows that doses to members of the public are below annual dose limit for both DBA and BDBA events. However, doses from exposure to operating staff and experimenters working inside the reactor hall are predicted to be very high in case of BDBA and therefore the protective actions should be taken when the accident occurs. (author)

  1. Uncertainty and Sensitivity of Neutron Kinetic Parameters in the Dynamic Response of a PWR Rod Ejection Accident Coupled Simulation

    C. Mesado

    2012-01-01

    Full Text Available In nuclear safety analysis, it is very important to be able to simulate the different transients that can occur in a nuclear power plant with a very high accuracy. Although the best estimate codes can simulate the transients and provide realistic system responses, the use of nonexact models, together with assumptions and estimations, is a source of uncertainties which must be properly evaluated. This paper describes a Rod Ejection Accident (REA simulated using the coupled code RELAP5/PARCSv2.7 with a perturbation on the cross-sectional sets in order to determine the uncertainties in the macroscopic neutronic information. The procedure to perform the uncertainty and sensitivity (U&S analysis is a sampling-based method which is easy to implement and allows different procedures for the sensitivity analyses despite its high computational time. DAKOTA-Jaguar software package is the selected toolkit for the U&S analysis presented in this paper. The size of the sampling is determined by applying the Wilks’ formula for double tolerance limits with a 95% of uncertainty and with 95% of statistical confidence for the output variables. Each sample has a corresponding set of perturbations that will modify the cross-sectional sets used by PARCS. Finally, the intervals of tolerance of the output variables will be obtained by the use of nonparametric statistical methods.

  2. Chemical Effects on PWR Sump Strainer Blockage After A Loss-Of-Coolant Accident: Review On U. S. Research Efforts

    Industry- or regulatory-sponsored research activities on the resolution of Generic Safety Issue (GSI)-191 were reviewed, especially on the chemical effects. Potential chemical effects on the head loss across the debris-loaded sump strainer under a post-accident condition were experimentally evidenced by small-scale bench tests, integrated chemical effects test (ICET), and vertical loop head loss tests. Three main chemical precipitates were identified by WCAP-16530-NP: calcium phosphate, aluminum oxyhydroxide, and sodium aluminum silicate. The former two precipitates were also identified as major chemical precipitates by the ICETs. The assumption that all released calcium would form precipitates is reasonable. CalSil insulation needs to be minimized especially in a plant using trisodium phosphate buffer. The assumption that all released aluminum would form precipitates appears highly conservative because ICETs and other studies suggest substantial solubility of aluminum at high temperature and inhibition of aluminum corrosion by silicate or phosphate. The industry-proposed chemical surrogates are quite effective in increasing the head loss across the debris-loaded bed and more effective than the prototypical aluminum hydroxide precipitates generated by in-situ aluminum corrosion. There appears to be some unresolved potential issues related to GSI-191 chemical effects as identified in NUREG/CR-6988. The United States Nuclear Regulatory Commission, however, concluded that the implications of these issues are either not generically significant or are appropriately addressed, although several issues associated with downstream in-vessel effects remain

  3. Effect of check valve on consequences of coolant pump rotor seizure accident for EPR reactor

    Counter current flow phenomenon would appear during reactor coolant pump rotor seizure accident. Present work analyzes the coolant pump rotor seizure accident for European Pressurized Reactor (EPR). The accident safety analysis results of model with check valve and with out check valve are compared. It can be found that the check valve can increase the core inlet flow rate of model about 4%. The increasing of coolant flow rate is beneficial to the reactor core cooling. Check valve can increase the minimum departure from nucleate boiling ratio (DNBR), reduce the departure from nucleate boiling (DNB) fraction and the fuel rod cladding temperature about 14℃ during coolant pump rotor seizure accident. The analyses results show that the model with check valve can maintain the integrity of nuclear fuel rod effectively during reactor coolant pump rotor seizure accident. (authors)

  4. COSYMA, a mainframe and PC program package for assessing the consequences of hypothetical accidents

    COSYMA (Code System from MARIA) is a program package for assessing the off-site consequences of accidental releases of radioactive material to atmosphere, developed as part of the European Commission's MARIA programme (Methods for Assessing the Radiological Impact of Accidents). COSYMA represents a fusion of ideas and modules from the Forschungszetrum Karlsruhe program system UFOMOD, the National Radiological Protection Board program MARC and new model developments together with data libraries from other MARIA contractors. Mainframe and PC versions of COSYMA are distributed to interested users by arrangement with the European Commission. The system was first released in 1990, and has subsequently been updated. The program system uses independent modules for the different parts of the analysis, and so permits a flexible problem-oriented application to different sites, source terms, emergency plans and the needs of users in the various parts of Europe. Users of the mainframe system can choose the most appropriate combination of modules for their particular application. The PC version includes a user interface which selects the required modules for the endpoints specified by the user. This paper describes the structure of the mainframe and PC versions of COSYMA, and summarises the models included in them. The mainframe or PC versions of COSYMA have been distributed to more than 100 organisations both inside and outside the European Union, and have been used in a wide variety of applications. These range from full PRA level 3 analyses of nuclear power and research reactors to investigations on advanced containment concepts and the preplanning of off-site emergency actions. Some of the experiences from these applications are described in the paper. An international COSYMA user group has been established to stimulate communication between the owners, developers and users of the code and to serve as a reference point for questions relating to the code. The group produces

  5. Evaluation of severe accident risks: Methodology for the containment, source term, consequence, and risk integration analyses. Volume 1, Revision 1

    NUREG-1150 examines the risk to the public from five nuclear power plants. The NUREG-1150 plant studies are Level III probabilistic risk assessments (PRAs) and, as such, they consist of four analysis components: accident frequency analysis, accident progression analysis, source term analysis, and consequence analysis. This volume summarizes the methods utilized in performing the last three components and the assembly of these analyses into an overall risk assessment. The NUREG-1150 analysis approach is based on the following ideas: (1) general and relatively fast-running models for the individual analysis components, (2) well-defined interfaces between the individual analysis components, (3) use of Monte Carlo techniques together with an efficient sampling procedure to propagate uncertainties, (4) use of expert panels to develop distributions for important phenomenological issues, and (5) automation of the overall analysis. Many features of the new analysis procedures were adopted to facilitate a comprehensive treatment of uncertainty in the complete risk analysis. Uncertainties in the accident frequency, accident progression and source term analyses were included in the overall uncertainty assessment. The uncertainties in the consequence analysis were not included in this assessment. A large effort was devoted to the development of procedures for obtaining expert opinion and the execution of these procedures to quantify parameters and phenomena for which there is large uncertainty and divergent opinions in the reactor safety community

  6. Evaluation of severe accident risks: Methodology for the containment, source term, consequence, and risk integration analyses; Volume 1, Revision 1

    Gorham, E.D.; Breeding, R.J.; Brown, T.D.; Harper, F.T. [Sandia National Labs., Albuquerque, NM (United States); Helton, J.C. [Arizona State Univ., Tempe, AZ (United States); Murfin, W.B. [Technadyne Engineering Consultants, Inc., Albuquerque, NM (United States); Hora, S.C. [Hawaii Univ., Hilo, HI (United States)

    1993-12-01

    NUREG-1150 examines the risk to the public from five nuclear power plants. The NUREG-1150 plant studies are Level III probabilistic risk assessments (PRAs) and, as such, they consist of four analysis components: accident frequency analysis, accident progression analysis, source term analysis, and consequence analysis. This volume summarizes the methods utilized in performing the last three components and the assembly of these analyses into an overall risk assessment. The NUREG-1150 analysis approach is based on the following ideas: (1) general and relatively fast-running models for the individual analysis components, (2) well-defined interfaces between the individual analysis components, (3) use of Monte Carlo techniques together with an efficient sampling procedure to propagate uncertainties, (4) use of expert panels to develop distributions for important phenomenological issues, and (5) automation of the overall analysis. Many features of the new analysis procedures were adopted to facilitate a comprehensive treatment of uncertainty in the complete risk analysis. Uncertainties in the accident frequency, accident progression and source term analyses were included in the overall uncertainty assessment. The uncertainties in the consequence analysis were not included in this assessment. A large effort was devoted to the development of procedures for obtaining expert opinion and the execution of these procedures to quantify parameters and phenomena for which there is large uncertainty and divergent opinions in the reactor safety community.

  7. PWR degraded core analysis

    A review is presented of the various phenomena involved in degraded core accidents and the ensuing transport of fission products from the fuel to the primary circuit and the containment. The dominant accident sequences found in the PWR risk studies published to date are briefly described. Then chapters deal with the following topics: the condition and behaviour of water reactor fuel during normal operation and at the commencement of degraded core accidents; the generation of hydrogen from the Zircaloy-steam and the steel-steam reactions; the way in which the core deforms and finally melts following loss of coolant; debris relocation analysis; containment integrity; fission product behaviour during a degraded core accident. (U.K.)

  8. Diagnostics and medical treatment of multiple somatic pathology for liquidators of consequences of Chernobyl power plant accident

    States conditioned impacts of radiation, chemical and psychologic stresses and appeared by polyorgan combine somatic pathology are typical for liquidators of consequences of Chernobyl power plant accident and of 30-km zone. Minimizing of medicinal therapy, formation of purpose to active recovery, discharge-dietary therapy, organism satiation of vitamins and microelements, creation and progress of dynamic reserves are main principles therapy correction of these states

  9. Scientometric analysis of the means of scientific communication of the problem of medical consequences of Chernobyl Nuclear accident

    In this paper evaluation of the structure and trends in the development of the Ukrainian scientific communication tools on the medical consequences of the Chernobyl nuclear accident using bibliometric methods has been given. The main developers of methodical documents are allocated, the dynamics of the distribution of methodical references, information letters and innovations is estimated. The importance of scientific communications tools in dissemination and use of new medical knowledge is demonstrated

  10. Human exposure to radiation following the release of radioactivity from a reactor accident: a quantitative assessment of the biological consequences

    The objective of this review is to provide a biological basis upon which to assess the consequences of the exposure of a population to radioactivity released after a reactor accident. Depending upon the radiation dose, both early and late somatic damage could occur in the exposed population and hereditary effects may occur in their descendants. The development of dose-effect relationships has been based upon the limited amount of information available on humans, supplemented by data obtained from experiments on animals. (author)

  11. Elimination of the consequences of radiation accidents at the Mayak production association in the 1950s and 1960s

    The paper describes the consequences of radiation accidents happened at Mayak production association located in Chelyabinsk region, Urals, Russia, and countermeasures applied for reduction of radiation exposure of local population. The assessment of the efficiency of countermeasures based on the averted dose criterion is presented. It is stated that the most efficient measures on prevention of the population exposure were relocation of the population and construction of the Techa Reservoir Cascade. (author)

  12. Reduction of the consequences of accidents whereby the emergency shutdown system in modern reactors fails (ATWS)

    If a nuclear reactor can not be shutdown by pulling out the control rods, an emergency shutdown system must be used. The events, when such a system fails, have been calculated. Also attention is paid to the chance that both systems fail and the possibility of using an extra independent shutdown system, realized in pressurized water reactors (PWR) or boiling water reactors (BWR). Finally a General Electric developed safety method and an alternative method regarding the failure of an emergency shutdown system are described. The results of this investigation, which were also based on a literature study, can be applied in formulating specifications of new nuclear power plants

  13. Evaluation of sanitary consequences of Chernobylsk accident in France. Epidemiological surveillance plan, state of knowledge, risks evaluation and perspectives

    This report jointly written by IPSN and InVS, reviews the sanitary consequences in France of the Chernobyl accident, which occurred in 1986. The first point is dedicated to a short presentation of the knowledge relative to the sanitary consequences of the Chernobyl accident in the high contaminated countries and to the risk factors of the thyroid cancer. Secondly, this report describes the main systems of epidemiological surveillance of health implemented in France in 1986 and in 1999, as well as the data of the incidence and mortality of thyroid cancer observed in France since 1975. In addition, this report presents an analysis of the risk of thyroid cancer related to radioactive contamination in France, for young people of less than 15 years of age who where living in 1986 in the highest contaminated areas of France (Eastern territories). For this purpose, the theoretical number of thyroid cancers in excess is evaluated for this population, on the basis of different available risk model. Finally starting from the results of risk assessment, there is a discussion about the relevance and the feasibility of different epidemiological methods in view of answering the questions related to the sanitary consequences of the Chernobyl accident. In conclusion, this report recommends to reinforce the surveillance of thyroid cancer in France. (author)

  14. Effect of the Duration Time of a Nuclear Accident on Radiological Health Consequences

    Hyojoon Jeong

    2014-03-01

    Full Text Available This study aimed to quantify the effect of duration time of a nuclear accident on the radiation dose of a densely populated area and the resulting acute health effects. In the case of nuclear accidents, the total emissions of radioactive materials can be classified into several categories. Therefore, the release information is very important for the assessment of risk to the public. We confirmed that when the duration time of the emissions are prolonged to 7 hours, the concentrations of radioactive substances in the ambient air are reduced by 50% compared to that when the duration time of emission is one hour. This means that the risk evaluation using only the first wind direction of an accident is very conservative, so it has to be used as a screening level for the risk assessment. Furthermore, it is judged that the proper control of the emission time of a nuclear accident can minimize the health effects on residents.

  15. First International Conference of the European Commission, Belarus, Russian Federation and Ukraine on the radiological consequences of the Chernobyl accident

    The First International Conference of European Commission, Belarus, Russian Federation and Ukraine on the radiological consequences of the Chernobyl accident has been held in Minsk, 18-22 March 1996. During the Conference 84 lectures as well as 74 posters have been presented. The most important problems connected with general topic was: the radiation contaminations and their measurements; environmental aspects and between them; radionuclide migration and remedial actions in contaminated areas; healthy consequences with irradiated people curing and epidemiology; thyroid neoplasms in children; organization rescue actions during future radiation disasters

  16. Effect of the Duration Time of a Nuclear Accident on Radiological Health Consequences

    Hyojoon Jeong; Misun Park; Haesun Jeong; Wontae Hwang; Eunhan Kim; Moonhee Han

    2014-01-01

    This study aimed to quantify the effect of duration time of a nuclear accident on the radiation dose of a densely populated area and the resulting acute health effects. In the case of nuclear accidents, the total emissions of radioactive materials can be classified into several categories. Therefore, the release information is very important for the assessment of risk to the public. We confirmed that when the duration time of the emissions are prolonged to 7 hours, the concentrations of radio...

  17. The radiological accident of Goiania and its consequences for the development of law

    The radiological accident of Goiania and its repercussions caused intense debate in Brazilian society, which extended to the legislative sphere. One of the principal outcomes of this debate was the inclusion in the new Brazilian Constitutional Charter of legal provisions covering the control of nuclear energy and of radiation sources. Internationally, the 1986 Vienna Convention on Early Notification of a Nuclear Accident and the Convention on Assistance in the Case of a Nuclear Accident or Radiological Emergency were invoked following the accident and proved to be effective in facilitating international co-operation and solidarity to deal with the aftermath of the accident. A number of international treaties on assistance in the event of nuclear accidents, the management of radioactive waste and the management of spent fuel are currently in force. The Joint Convention on the Safety of Spent Fuel Management and on the Safety of Radioactive Waste, adopted in 1997, is the most recent treaty promoting the sustainability of nuclear activities. Looking ahead, an international legal framework is needed to build upon and improve the principles of a culture of radiation safety. (author)

  18. Reactor safety study. An assessment of accident risks in U. S. commercial nuclear power plants. Appendices VII, VIII, IX, and X. [PWR and BWR

    1975-10-01

    Information is presented concerning the release of radioactivity in reactor accidents; physical processes in reactor meltdown accidents; safety design rationale for nuclear power plants; and design adequacy.

  19. INFLUENCE OF ANTIHYPERTENSIVE THERAPY ON PSYCHOLOGICAL STATUS OF CHERNOBYL NUCLEAR POWER PLANT ACCIDENT CONSEQUENCES LIQUIDATORS

    E. M. Manoshkina

    2016-01-01

    Full Text Available Aim. To study psychological status and influence of antihypertensive therapy (AHT on it in Chernobyl nuclear power plant (NPP accident consequences liquidators, who suffer arterial hyper-tension (AH, with controlled treatment compared to the standard treatment in out-patient clinic. Material and methods. 81 liquidators with AH (all men were included into open compara-tive randomized study. Study duration was 12 months. Patients were randomized into main group (MG and control group (CG. Patients of MG received strictly regulated stepped AHT based on ACE inhibitor spirapril 6 mg daily (Quadropril®, Pliva-AVD, hypothiazide was added if necessary (12.5-25 mg daily and afterwards – atenolol (12.5-100 mg daily. In CG AHT and its correction was set by physician in polyclinic. Brief multifactor questionnaire for personality analysis was used to study psychological status. Results. 57 patients completed the study, 28 in MG and 29 in CG. In MG target blood pres-sure (BP levels were reached in 22 (78.6% patients, in CG – in 11 (38% patients (p<0.01. The main feature of psychological status of liquidators with AH was hypochondriac, depressive and anxious disorders. Controlled AHT made it possible to reach improvement in psychological status, i.e. growth of optimism and activity of patients, more often, than standard treatment in out-patient clinics. Increase in number of patients with pronounced anxious changes was observed in CG. Effi-ciency of AHT in liquidators with AH is connected with severity of depressive disturbances: in subgroups with inefficient treatment patients had the highest level of depression. In liquidators with AH, possessing neurotic disturbances, spirapril was efficient both as monotherapy, and in combina-tion with diuretic hydrochlorothiazide and beta-blocker atenolol. Conclusion. Controlled AHT in liquidators with AH has advantages over standard treatment in out-patient clinic and results in more frequent target BP level

  20. Transuranics and fission products release from PWR fuels in severe accident conditions. Lessons learnt from VERCORS RT3 and RT4 tests

    Over the last decades, several experimental programs devoted to the source term of fission products (FP) and actinides released from PWR fuel samples in severe accident (SA) conditions have been initiated throughout the world. In France, in this context, the Institute for Radiological Protection and Safety (IRSN) and Electricite de France (EDF) have supported the analytical VERCORS program which was performed by the Commissariat a l'Energie Atomique (CEA). The VERCORS facility at the LAMA-laboratory (CEA-Grenoble, France) was designed to heat up an irradiated fuel sample - taken from EDF's nuclear power reactors - to fuel relocation, and to capture the fission products released from the fuel and deposited downstream on a series of specific filters (impactors, bead-bed filter). On-line gamma detectors aimed at the fuel position, filters and gas capacity monitored the progress of FP release from the fuel, FP deposition on the filters and the fission gases emitted by the fuel (xenon and krypton). Before and after the test, a longitudinal gamma-scan of the fuel was conducted to measure the initial and final FP inventory in order to evaluate the quantitative fractions of FP emitted by the fuel during the test. All the components of the loop were then gamma-scanned to measure and locate the FPs released during the test and to draw up a mass balance of these FP. 25 annealing tests were performed between 1983 and 2002 on irradiated PWR fuels under various conditions of temperature and atmospheres (oxidising or reducing conditions). The influence of the nature of the fuel (UO2 versus MOX, burn up) and the fuel morphology (initially intact or fragmented fuel) have also been investigated. This led to an extended data base allowing on the one hand to study mechanisms which promote FP release in SA conditions, and on the other hand to enhance models implemented in SA codes. Because gamma spectrometry is well suited to FP measurement and not to actinides (except neptunium

  1. Evaluation of sanitary consequences of Chernobyl accident in France: epidemiological monitoring device, state of knowledge, evaluation of risks and perspectives

    The objectives of this document are firstly, to present the situation of knowledge both on the sanitary consequences of the Chernobyl accident and on the risk factors of thyroid cancers, these ones constituting one of the most principal consequences observed in Belarus, in Ukraine and Russia; secondly, the give the principal system contributing to the epidemiological surveillance of effects coming from a exposure to ionizing radiations, in France and to give the knowledge on incidence and mortality of thyroid cancer in France; thirdly, to discuss the pertinence and the feasibility of epidemiological approaches that could be considered to answer questions that the public and authorities ask relatively to the sanitary consequences of Chernobyl accident in France; fourthly to male a calculation of thyroid cancer risk in relation with Chernobyl fallout in France from works and studies made from 1986 on the consequences of this disaster in terms of radioecology and dosimetry at the national level. Besides, the improvement of thyroid cancer surveillance is also tackled. (N.C.)

  2. Assessing the consequences in a nuclear accident scenario at Cernavoda NPP

    Having in view a possible nuclear incident, considerable planning is necessary to reduce at manageable levels the types of decisions leading to effective responses concerning the public protection. One of the most important parts of an emergency response plan is the computerized system which allows to predict the radiological impact of the accident and to provide information in a manageable and effective form for evaluating alternative countermeasure strategies in the various stages of the accident. In this paper the PC-COSYMA results for early containment failure of a CANDU reactor are presented. The deterministic health effects arising in nuclear accident situation are also presented. As source term we have used the core inventory obtained with ORIGEN computer code. The essential input parameters for PC-COSYMA computer code are also done. (authors)

  3. Proceedings of the Seminar on Methods and Codes for Assessing the off-site consequences of nuclear accidents. Volume 1

    The Commission of the European Communities, within the framework of its 1980-84 radiation protection research programme, initiated a two-year project in 1983 entitled 'methods for assessing the radiological impact of accidents' (Maria). This project was continued in a substantially enlarged form within the 1985-89 research programme. The main objectives of the project were, firstly, to develop a new probabilistic accident consequence code that was modular, incorporated the best features of those codes already in use, could be readily modified to take account of new data and model developments and would be broadly applicable within the EC; secondly, to acquire a better understanding of the limitations of current models and to develop more rigorous approaches where necessary; and, thirdly, to quantify the uncertainties associated with the model predictions. This research led to the development of the accident consequence code Cosyma (COde System from MAria), which will be made generally available later in 1990. The numerous and diverse studies that have been undertaken in support of this development are summarized in this paper, together with indications of where further effort might be most profitably directed. Consideration is also given to related research directed towards the development of real-time decision support systems for use in off-site emergency management

  4. The consequences of the Chernobyl accident in the Ukraine and problems with the sarcophagus

    The reactor accident in the Ukraine contaminated part of the territory with iodine 131, caesium 137, strontium 90, and plutonium 239 and 240. The zone surrounding the site of the accident was declared restricted area; more than 90 000 persons were evacuated. The paper reports on current conditions in the restricted area and prospects for this area as well as on the current state of, and problems with, the sarcophagus. The conversion of the sarcophagus into an ecologically safe system and the economic situation of the Ukraine pose great problems. (DG)

  5. Aerosol transport analysis of LWR high-consequence accidents using the HAA-4A code

    Use of the HAA-4A code to calculate removal of aerosol in containment due to inherent behavior mechanisms is described. Results for a PWR TMLB' scenario showed a source reduction of about a factor of 50 in CsI available for release to the environment through a catastrophic containment failure. Respirable CsI entering containment from the primary coolant system and melt-through blowdown was a factor of 25 less than the source. The principal removal mechanisms were particle growth due to Brownian and differential settling agglomeration and subsequent fallout. Sensitivities to important and uncertain parameters are discussed. Increased removal due to turbulent agglomeration and a larger expected source particle size are indicated. A seven control volume analysis took less than 1 minute of CPU time on an IBM 3033

  6. Consequences of Windscale accident (October 1957) and study of the validity of the Sutton's mathematical model of atmospheric diffusion (1960)

    The reactor accident that happens at the number 1 pile of Windscale in 1957 was followed by a discharge of radioactive products into the atmosphere from the 1.X.1957 at 4.30 PM to the 12.X.1957 at 3.10 PM. On october the 11th it was possible to say that there was no more risk either of external irradiation or inhalation. But in adopting a M.A.C. of 0,1 μcurie of iodine 131 per litre of milk, the Authority had to control the milk delivery till november 23rd on a 500 km2 area. On the other hand, this exceptional accident permit to verify that Sutton's atmospheric diffusion model could give an easy means to foresee, with a sufficient approximation, the consequences of a dispersion of radioactive products into the atmosphere. (author)

  7. Comparison of the foodchain transport models of WASH-1400 and MARC using the accident consequence model UFOMOD

    Within the frame of the contract with the European Community 'Methods for Assessing the Radiological Impact of Accidents' (CEC-MARIA) comparative accident consequence assessments were performed with the computer code UFOMOD, replacing the currently implemented foodchain transport model of the WASH-1400 study by the dynamic transport model of the MARC methodology. The calculations were based on the release category FK2 of the German Risk Study with meteorological data representing four different regions of the Federal Republic of Germany. The study of seasonal variations was carried out with the MARC data for four representative times of deposition with an agricultural practice adopted in the UK. In this report the differences are presented which are observed in the potential doses due to ingestion, the areas affected by food-bans and the late health effects when using both models and taking the influence of seasonal effects into account. (orig.)

  8. Consequences of major nuclear accidents on wild fauna and flora: dosimetric assessments remain a weakness to establish robust conclusions

    As about hundred of studies have been undertaken after the major nuclear accidents (Chernobyl and Fukushima) to study the consequences of these accidents on wild flora and fauna, notably on the effects of low doses of ionizing radiations, it appears that some of them reported noticeable effects due to extremely low doses. Such findings put knowledge in radiobiology into question again. This note aims at discussing the importance of the quality of dosimetric assessments for any study performed 'in natura'. It seems that the ambient external dose rate is not systematically a good indicator of the dose or dose rate absorbed by a living organism in radio-contaminated environment. This note outlines the problem related to the spatial heterogeneity of the radioactive contamination, that some statistic methods are not always adapted to data set quality. It briefly indicates other factors which may affect the quality of data set obtained during in situ studies

  9. 10 years after the Chernobyl reactor accident. Thyroid cancer and consequences of public health in the CIS

    Ten years after the accident at the Chernobyl nuclear reactor, governmental and international organisations have identified considerable effects on the health of the various affected groups. A dramatic - over 100-fold - increase in thyroid cancers among children in Belarus has been caused by papillary thyroid carcinomas that are marked by aggressive growth with early metastatic spread. As early as 1995, the number of new cases of thyroid cancer among adults was four times the mean figure in the period before 1986. In Oblast Gomel, the number of children with diabetes mellitus doubled between 1986 and the end of 1995. The number of recorded cases of thyroid cancer, particularly among children, by far exceeds the prognoses made on the basis of established radiation risk estimates, and points to a considerable underestimation of the consequences of the Chernobyl accident. (orig.)

  10. Emergency Responses and Health Consequences after the Fukushima Accident; Evacuation and Relocation.

    Hasegawa, A; Ohira, T; Maeda, M; Yasumura, S; Tanigawa, K

    2016-04-01

    The Fukushima accident was a compounding disaster following the strong earthquake and huge tsunami. The direct health effects of radiation were relatively well controlled considering the severity of the accident, not only among emergency workers but also residents. Other serious health issues include deaths during evacuation, collapse of the radiation emergency medical system, increased mortality among displaced elderly people and public healthcare issues in Fukushima residents. The Fukushima mental health and lifestyle survey disclosed that the Fukushima accident caused severe psychological distress in the residents from evacuation zones. In addition to psychiatric and mental health problems, there are lifestyle-related problems such as an increase proportion of those overweight, an increased prevalence of hypertension, diabetes mellitus and dyslipidaemia and changes in health-related behaviours among evacuees; all of which may lead to an increased cardiovascular disease risk in the future. The effects of a major nuclear accident on societies are diverse and enduring. The countermeasures should include disaster management, long-term general public health services, mental and psychological care, behavioural and societal support, in addition to efforts to mitigate the health effects attributable to radiation. PMID:26876459

  11. Epidemiological survey of the medical consequences of the Chernobyl accident in Ukraine

    The characteristics of the contamination resulting from the Chernobyl accident are defined, as a basis for epidemiological investigations. Due to loss of integrity of the nuclear fuel and thermal buoyancy from fire and nuclear heating, a large quantity of radioisotopes were released over a period of up to 16 days. The areas affected were very large, 37 million hectares in Ukraine alone. About 5 million persons were affected in one way or another, over 2 million of them in Ukraine. Registration and epidemiological follow-up in the former USSR and the three republics afterwards are presented with an emphasis on Ukraine. Considering the long incubation times for some of the expected illnesses and relatively low average doses, the difficulties of confirming significant effects become evident. For example leucosis morbidity among cleanup personnel within a 30 km zone around the accident was 3.4 per 100,000 before the accident and 7 per 100,000 afterwards. The question of the statistical significance of such numbers is discussed by the authors, in the context of confounding factors. For some of the observed effects it has already been established that stress and anxiety caused by the accident and living conditions in the affected areas are the principal cause rather than radiation. According to the authors, more detailed retrospective and prospective epidemiological studies are needed in the future, in order to clarify the causes of observed health effects

  12. Status of safety technology for radiological consequence assessment of postulated accidents in liquid metal fast breeder reactors, Canoga Park, California, 29 July--31 July 1975

    State-of-the-art capabilities are examined for prediction and mitigation of radiological consequences of postulated LMFBR accidents. The following topics are treated: radioactive source terms, sodium reactions, aerosol behavior, radiological dose assessment, and engineered safeguards. (U.S.)

  13. The unique field experiments on the assessment of accident consequences at industrial enterprises of gas-chemical complexes

    Sour natural gas fields are the unique raw material base for setting up such large enterprises as gas chemical complexes. The presence of high toxic H2S in natural gas results in widening a range of dangerous and harmful factors for biosphere. Emission of such gases into atmosphere during accidents at gas wells and gas pipelines is of especial danger for environment and first of all for people. Development of mathematical forecast models for assessment of accidents progression and consequences is one of the main elements of works on safety analysis and risk assessment. The critical step in development of such models is their validation using the experimental material. Full-scale experiments have been conducted by the All-Union Scientific-Research institute of Natural Gases and Gas Technology (VNIIGAZ) for grounding of sizes of hazard zones in case of the severe accidents with the gas pipelines. The source of emergency gas release was the working gas pipelines with 100 mm dia. And 110 km length. This pipeline was used for transportation of natural gas with significant amount of hydrogen sulphide. During these experiments significant quantities of the gas including H2S were released into the atmosphere and then concentrations of gas and H2S were measured in the accident region. The results of these experiments are used for validation of atmospheric dispersion models including the new Lagrangian trace stochastic model that takes into account a wide range of meteorological factors. This model was developed as a part of computer system for decision-making support in case of accident release of toxic gases into atmosphere at the enterprises of Russian gas industry. (authors)

  14. Parameterization of the driving time in the evacuation or fast relocation model of an accident consequence code

    The model of protective measures in the accident consequence code system UFOMOD of the German Risk Study, Phase B, requires the driving times of the population to be evacuated for the evaluation of the dose received during the evacuation. The parameter values are derived from evacuation simulations carried out with the code EVAS for 36 sectors from various sites. The simulations indicated that the driving time strongly depends on the population density, whereas other influences are less important. It was decided to use different driving times in the consequence code for each of four population density classes as well as for each of three or four fractions of the population in a sector. The variability between sectors of a class was estimated from the 36 sectors, in order to derive subjective probability distributions that are to model the uncertainty in the parameter value to be used for any of the fractions in a particular sector for which an EVAS simulation has not yet been performed. To this end also the impact of the uncertainties in the parameters and modelling assumptions of EVAS on the simulated times was quantified using expert judgement. The distributions permit the derivation of a set of driving times to be used as so-called ''best estimate'' or reference values in the accident consequence code. Additionally they are directly applicable in an uncertainty and sensitivity analysis

  15. Radiological consequence analyses of loss of coolant accidents of various break sizes of Pressurized Heavy Water Reactor

    For any advanced technology, it is essential to ensure that the consequences associated with the accident sequences arising, if any, from the operation of the plant are as low as possible and certainly below the guidelines/limits set by the regulatory bodies. Nuclear power is no exception to this. In this paper consequences of the events arising from Loss of Coolant Accident (LOCA) sequences in Pressurized Heavy Water Reactor (PHWR), are analysed. The sequences correspond to different break sizes of LOCA followed by the operation or otherwise of Emergency Core Cooling System (ECCS). Operation or otherwise of the containment safety systems has also been considered. It has been found that there are no releases to the environment when ECCS is available. The releases, when ECCS is not available, arise from the slack and the ground. The radionuclides considered include noble gases, iodine, and cesium. The hourly meteorological parameters (wind speed, wind direction, precipitation and stability category), considered for this study, correspond to those of Kakrapar site. The consequences evaluated are the thyroid dose and the bone marrow dose received by a person located at various distances from the release point. Isodose curves are generated. From these evaluations, it has been found that the doses are very low. The complementary cumulative frequency distributions (CCFD) for thyroid and bone marrow doses have also been presented for the cases analysed. (author)

  16. PWR physics, operation and safety - Management of accidental situations of the reactor system

    This document contains a brief presentation and the table of contents of a book in which the author first presents the main types of accidents which are taken into account in safety demonstration. He presents the risk concerning the three safety barriers, and the various accidents affecting the three safety functions: reactivity control, power evacuation, confinement by the third barrier. Then the author describes approaches to the management of accidents affecting these three safety functions: reactivity insertion accidents due to absorber withdrawal (presentation, absorber cluster extraction transients, primary fluid dilution transient), steam pipe failure accidents or reactivity insertion by primary cooling (presentation, description of a transient of steam-pipe failure, sensitivity study of main parameters), loss-of-coolant accidents (presentation, intermediate breach, the big breach, peculiar case of breaches in stopped status), total loss of support systems such as in Fukushima (loss of electric supplies, of the cold source), loss of steam generator tubes. In the next part, the author addresses the Three Mile Island (TMI) accident and the lessons learned in terms of post-accidental management: presentation of the reactor and description of the accident. The author presents the 'status approach' of the post-accidental management, addresses the core post-fusion situations and their consequences as far as containment is concerned. He finally proposes ways to manage accidental situations for the PWR system. Appendices propose some additional aspects of system thermal-hydraulics, a presentation of safety deterministic and probabilistic approaches, comments on the Chernobyl and Fukushima accidents, comments on human and organizational factors regarding nuclear safety, some specific design aspects of the PWR reactor regarding safety, a presentation of assessment equations and data for the 1300 MWe PWR model

  17. Probabilistic accident consequence uncertainty analysis: Dispersion and deposition uncertainty assessment. Volume 3, Appendices C, D, E, F, and G

    The development of two new probabilistic accident consequence codes, MACCS and COSYMA, completed in 1990, estimate the risks presented by nuclear installations based on postulated frequencies and magnitudes of potential accidents. In 1991, the US Nuclear Regulatory Commission (NRC) and the Commission of the European Communities (CEC) began a joint uncertainty analysis of the two codes. The objective was to develop credible and traceable uncertainty distributions for the input variables of the codes. Expert elicitation, developed independently, was identified as the best technology available for developing a library of uncertainty distributions for the selected consequence parameters. The study was formulated jointly and was limited to the current code models and to physical quantities that could be measured in experiments. To validate the distributions generated for the wet deposition input variables, samples were taken from these distributions and propagated through the wet deposition code model along with the Gaussian plume model (GPM) implemented in the MACCS and COSYMA codes. Resulting distributions closely replicated the aggregated elicited wet deposition distributions. Project teams from the NRC and CEC cooperated successfully to develop and implement a unified process for the elaboration of uncertainty distributions on consequence code input parameters. Formal expert judgment elicitation proved valuable for synthesizing the best available information. Distributions on measurable atmospheric dispersion and deposition parameters were successfully elicited from experts involved in the many phenomenological areas of consequence analysis. This volume is the third of a three-volume document describing the project and contains descriptions of the probability assessment principles; the expert identification and selection process; the weighting methods used; the inverse modeling methods; case structures; and summaries of the consequence codes

  18. Probabilistic accident consequence uncertainty analysis: Dispersion and deposition uncertainty assessment. Volume 3, Appendices C, D, E, F, and G

    Harper, F.T.; Young, M.L.; Miller, L.A. [Sandia National Labs., Albuquerque, NM (United States)] [and others

    1995-01-01

    The development of two new probabilistic accident consequence codes, MACCS and COSYMA, completed in 1990, estimate the risks presented by nuclear installations based on postulated frequencies and magnitudes of potential accidents. In 1991, the US Nuclear Regulatory Commission (NRC) and the Commission of the European Communities (CEC) began a joint uncertainty analysis of the two codes. The objective was to develop credible and traceable uncertainty distributions for the input variables of the codes. Expert elicitation, developed independently, was identified as the best technology available for developing a library of uncertainty distributions for the selected consequence parameters. The study was formulated jointly and was limited to the current code models and to physical quantities that could be measured in experiments. To validate the distributions generated for the wet deposition input variables, samples were taken from these distributions and propagated through the wet deposition code model along with the Gaussian plume model (GPM) implemented in the MACCS and COSYMA codes. Resulting distributions closely replicated the aggregated elicited wet deposition distributions. Project teams from the NRC and CEC cooperated successfully to develop and implement a unified process for the elaboration of uncertainty distributions on consequence code input parameters. Formal expert judgment elicitation proved valuable for synthesizing the best available information. Distributions on measurable atmospheric dispersion and deposition parameters were successfully elicited from experts involved in the many phenomenological areas of consequence analysis. This volume is the third of a three-volume document describing the project and contains descriptions of the probability assessment principles; the expert identification and selection process; the weighting methods used; the inverse modeling methods; case structures; and summaries of the consequence codes.

  19. Bounding Radionuclide Inventory and Accident Consequence Calculation for the 1L Target

    Kelsey, Charles T. IV [Los Alamos National Laboratory

    2011-01-01

    A bounding radionuclide inventory for the tungsten of the Los Alamos Neutron Science Center (LANSCE) IL Target is calculated. Based on the bounding inventory, the dose resulting from the maximum credible incident (MCI) is calculated for the maximally exposed offsite individual (MEOl). The design basis accident involves tungsten target oxidation following a loss of cooling accident. Also calculated for the bounding radionuclide inventory is the ratio to the LANSCE inventory threshold for purposes of inventory control as described in the target inventory control policy. A bounding radionuclide inventory calculation for the lL Target was completed using the MCNPX and CINDER'90 codes. Continuous beam delivery at 200 {micro}A to 2500 mA{center_dot}h was assumed. The total calculated activity following this irradiation period is 205,000 Ci. The dose to the MEOI from the MCI is 213 mrem for the bounding inventory. The LANSCE inventory control threshold ratio is 132.

  20. Assessment of possible consequences of hypothetical reactivity initiated accident connected with Topaz-2 space NPS landing

    The preliminary results of analysis of the hypothetical accident connected with supercritical state initiation in the case of landing of the Topaz-2 space NPP with the thermionic reactor-converter into water are discussed. The results of analysis of the reactivity effects, when the reactor core cavities are filled with water, are considered. The results of numerical simulation of emergency transients are given as well. It is shown that the reactor has the property to compensate the redundant reactivity due to change of the density (phase state) of water filling the core cavities. At that several damping self-quenching power bursts, which transform into stable oscillations around the mean value amounting to several tens kw, may be initiated at the accident initial stage. 8 refs., 2 tabs., 2 figs

  1. What are the consequences of the reactor accident in Fukushima for the evaluation of nuclear risk?

    There are historical breaks in the relation of risk analysis, risk perception and regulation policy. The year 2011 with the reactor accident in the NPP Fukushima was such a break, especially in Germany. The nuclear phase-out was reduced to ten years the energy policy turnaround received a broad societal agreement. Nuclear facilities loose public acceptance, the risk perception has changed. The Japanese evaluation results on faulty and nontransparent behavior and the lack of governance of responsible persons and authorities including a poor accident management have further decreased the public confidence. A new concept of safety culture for all nuclear facilities including the radioactive waste management is required, the communication processes between plant operator, authorities, science and the public have to be intensified.

  2. Character of protective clothes contamination of the personnel participated in the efforts to eliminate the Chernobyl accident consequences

    The results of investigation of radioactive contamination of protective clothes made of cotton and mixed materials for personnel participated in elimination of the Chernobyl accident consequences are described. Radionuclide composition of clothes contamination before and after decontamination, as well as the values of decontamination coefficients, which are much lower than calculated ones, are presented. Clothes contamination is shown to be caused by difficulty soluble particles of irradiated uranium fuel. The contamination radionuclide composition changes a little as a result of decontamination: decrease only the total quantity of radionuclide substances, but contribution of every radionuclide remains unchanced. During decontamination particles of irradiated uranium fuel are removed from material without solution in the decontaminating solution

  3. Accident simulation and consequence analysis in support of MHTGR safety evaluations

    This paper summarizes research performed at Oak Ridge National Laboratory (ORNL) to assist the Nuclear Regulatory Commission (NRC) in preliminary determinations of licensability of the US Department of Energy (DOE) reference design of a standard modular high-temperature gas-cooled reactor (MHTGR). The work described includes independent analyses of core heatup and steam ingress accidents and the reviews and analyses of fuel performance and fission product transport technology

  4. Accident simulation and consequence analysis in support of MHTGR safety evaluations

    This paper summarizes research performed at Oak Ridge National Laboratory (ORNL) to assist the Nuclear Regulatory Commission (NRC) in preliminary determinations of licensability of the US Department of Energy (DOE) reference design of a standard modular high-temperature gas-cooled reactor (MHTGR). The work described includes independent analyses of core heatup and steam ingress accidents, and the reviews and analyses of fuel performance and fission product transport technology

  5. Accident consequences analysis of the HYLIFE-II inertial fusion energy power plant design

    Reyes, S; Gomez del Rio, J; Sanz, J

    2000-02-23

    Previous studies of the safety and environmental (S and E) aspects of the HYLIFE-II inertial fusion energy (IFE) power plant design have used simplistic assumptions in order to estimate radioactivity releases under accident conditions. Conservatisms associated with these traditional analyses can mask the actual behavior of the plant and have revealed the need for more accurate modeling and analysis of accident conditions and radioactivity mobilization mechanisms. In the present work a set of computer codes traditionally used for magnetic fusion safety analyses (CHEMCON, MELCOR) has been applied for simulating accident conditions in a simple model of the HYLIFE-II IFE design. Here the authors consider a severe lost of coolant accident (LOCA) producing simultaneous failures of the beam tubes (providing a pathway for radioactivity release from the vacuum vessel towards the containment) and of the two barriers surrounding the chamber (inner shielding and containment building it self). Even though containment failure would be a very unlikely event it would be needed in order to produce significant off-site doses. CHEMCON code allows calculation of long-term temperature transients in fusion reactor first wall, blanket, and shield structures resulting from decay heating. MELCOR is used to simulate a wide range of physical phenomena including thermal-hydraulics, heat transfer, aerosol physics and fusion product release and transport. The results of these calculations show that the estimated off-site dose is less than 6 mSv (0.6 rem), which is well below the value of 10 mSv (1 rem) given by the DOE Fusion Safety Standards for protection of the public from exposure to radiation during off-normal conditions.

  6. Depressurization as an accident management strategy to minimize the consequences of direct containment heating

    Hanson, D.J.; Golden, D.W.; Chambers, R.; Miller, J.D.; Hallbert, B.P.; Dobbe, C.A. (EG and G Idaho, Inc., Idaho Falls, ID (USA))

    1990-10-01

    Probabilistic Risk Assessments (PRAs) have identified severe accidents for nuclear power plants that have the potential to cause failure of the containment through direct containment heating (DCH). Prevention of DCH or mitigation of its effects may be possible using accident management strategies that intentionally depressurize the reactor coolant system (RCS). The effectiveness of intentional depressurization during a station blackout TMLB' sequence was evaluated considering the phenomenological behavior, hardware performance, and operational performance. Phenomenological behavior was calculated using the SCDAP/RELAP5 severe accident analysis code. Two strategies to mitigate DCH by depressurization of the RCS were considered. One strategy, called early depressurization, assumed that the reactor head vent and pressurizer power-operated relief valves (PORVs) were latched open at steam generator dryout. The second strategy, called late depression, assumed that the head vent and PORVs were latched open at a core exit temperature of {approximately}922 K (1200{degree}F). Depressurization of the RCS to a low value that may mitigate DCH was predicted prior to reactor pressure vessel breach for both early and late depressurization. The strategy of late depressurization is preferred over early depressurization because there are greater opportunities to recover plant functions prior to core damage and because failure uncertainties are lessened. 22 refs., 38 figs., 6 tabs.

  7. Depressurization as an accident management strategy to minimize the consequences of direct containment heating

    Probabilistic Risk Assessments (PRAs) have identified severe accidents for nuclear power plants that have the potential to cause failure of the containment through direct containment heating (DCH). Prevention of DCH or mitigation of its effects may be possible using accident management strategies that intentionally depressurize the reactor coolant system (RCS). The effectiveness of intentional depressurization during a station blackout TMLB' sequence was evaluated considering the phenomenological behavior, hardware performance, and operational performance. Phenomenological behavior was calculated using the SCDAP/RELAP5 severe accident analysis code. Two strategies to mitigate DCH by depressurization of the RCS were considered. One strategy, called early depressurization, assumed that the reactor head vent and pressurizer power-operated relief valves (PORVs) were latched open at steam generator dryout. The second strategy, called late depression, assumed that the head vent and PORVs were latched open at a core exit temperature of ∼922 K (1200 degree F). Depressurization of the RCS to a low value that may mitigate DCH was predicted prior to reactor pressure vessel breach for both early and late depressurization. The strategy of late depressurization is preferred over early depressurization because there are greater opportunities to recover plant functions prior to core damage and because failure uncertainties are lessened. 22 refs., 38 figs., 6 tabs

  8. Consequences of the Chernobyl accident for people and the environment; Les consequences de Tchernobyl pour l'homme et l'environnement

    NONE

    2006-07-01

    This report recalls the accident scenario, discusses the dispersion of the radioactive plume, comments the contamination at the vicinity of the power station, discusses and comments data related to radioactive deposits in Europe and in France, comments available information regarding radioactive fallouts in Belarus, Ukraine and Russia (models have been used to assess radioactive deposits). It addresses the issue of food product contamination in these three countries (impact on farm products, on water streams and on forests), but also in France. It comments the health impacts, more particularly on the people who intervened on the site, but also on people who received medium doses. Thyroid cancer data are discussed for the three mainly concerned countries. Other pathologies and non-cancerous effects are also discussed. The mortality induced by the accident is commented. Effects in France are evoked as well as social and economic consequences in Ukraine, Belarus and Russia. The document provides several links to other documents for further and more detailed information

  9. Reactor safety study. An assessment of accident risks in U. S. commercial nuclear power plants. Executive summary: main report. [PWR and BWR

    1975-10-01

    Information is presented concerning the objectives and organization of the reactor safety study; the basic concepts of risk; the nature of nuclear power plant accidents; risk assessment methodology; reactor accident risk; and comparison of nuclear risks to other societal risks.

  10. An Investigation of Spray Performance to Remove Gaseous Iodine- Approach to mitigate the consequences of severe accident

    New technological approaches need to be in place to address such concern which has significantly deteriorated public confidence in nuclear power. Such technological approach must be capable of systematically mitigate the consequence of severe nuclear accidents involving radioactivity release. An example of such approach is spray technology. In case of an accident involving radioactivity release to the environment, it may possible to deploy spray system to quickly respond to the released radioactivity and to minimize the impact of accidental releases on humans and the environment. During early phase of Fukushima nuclear accident mitigation process, water spray operations were carried out through fire trucks and military helicopters, but the primary concern of such operations was to cool down the reactor and to extinguish the fire and not to minimize the spread of radioactive materials. The aim of this research is to investigate spray technology for effective and efficient capturing of fission products released from leaked/damaged nuclear reactor to the environment. For this purpose, a systematic approach with in depth information about release phenomena and spray features will be required. Based on the information regarding release phenomena including types of materials and their amount and size, release locations, release conditions such as rates, velocities, temperature, etc., requirements for spray application is being developed including spray material types (foam, mist etc.), spray solution additives, flow rates, pressure, drop size, spray coverage area and spray duration, etc. Subsequently the efficiency and effectiveness of spray system to reduce the Dispersion of radioactivity in the environment during the course of severe accident can be characterized. This paper is a summary of our initial investigation for the use of spray technology to reduce the consequence of severe nuclear accident. An experimental investigation of iodine removal efficiency in a spray

  11. The radioecological consequences of the Kyshtym and Chernobyl radiation accidents for forest ecosystems

    Following the Urals and Chernobyl accidents 60 to 90% of the radioactive fallout was retained by the above-ground part of forest stands. In the Urals the period for semi-removal of contamination from crowns ranged from 6 to 8 months, compared to around one month in the Chernobyl region - due to different seasonal conditions during the fallout period. The bulk of the dose burden in woody plants' critical organs built up over one to six months. The minimum lethal dose for pine tree needles in the Urals was around 50 Gy, and 25 Gy for the apical meristem; the corresponding figures for Chernobyl were 100 Gy and 25-30 Gy. At lower doses we observed morphological disturbances, reduced growth and suppressed reproductive capability in pines. The resistance to radioactive contamination of deciduous forest was 10-20 times greater than that of conifers. We studied the irradiation doses of the different groups of organisms living in the various forest storeys, and the effects of irradiation (changes in species composition, prevalence and productivity) in communities of herbaceous plants and soil invertebrates. Specific examples are given to highlight the secondary changes in these communities stemming from radiation damage in species sensitive to radioactive contamination. We studied the dynamics of dispersion and migration of the long-lived radionuclides 90Sr and 137Cs in the various components of the biogeocenoses and in the network of geochemically interconnected forest landscapes, and their content in forestry produce. Some six to ten years after the deposition of radioactive fallout in forest ecosystems the radionuclides were more or less evenly spread throughout the soil-woody plant system. Thus, overall 90Sr content in the arboreal storey amounts to 1-2% in coniferous forests, and 5-10% in deciduous forests (Urals accident), while the corresponding figures for 137Cs (Chernobyl accident) are 2 to 3 times higher. (author)

  12. The French-German initiative for Chernobyl: programme 3: Health consequences of the Chernobyl accident

    - Goals: The main objectives of the health programme are collection and validation of existing data on cancer and non cancer diseases in the most highly contaminated regions of Ukraine, Russia and Belarus, common scientific expertise on main health indicators and reliable dosimetry, and finally communication of the results to the scientific community and to the public. - General Tasks: 1- Comparison between high and low exposed regions, 2- Description of trends over time, 3- Consideration of specific age groups. This methodological approach is applied on Solid cancer incidence and leukaemia incidence in different regions in Ukraine, Belarus and Russia, With a special focus on thyroid cancer in young exposed ages. - Thyroid cancer: Those exposed in very young ages continue to express a relatively high excess of thyroid cancer even though they have now reached the age group 15-29. Those exposed as young adults show a small increase, at least partly due to better screening conditions - Leukemia: Description of leukemia trends for various age groups show no clear difference between exposed and unexposed regions when focusing on those exposed at very young ages. The rates of childhood leukemia before and after the accident show no evidence of any increase (oblasts in Belarus over 1982-1998). - Specific studies: Incidence of congenital malformations in Belarus; Infant mortality and morbidity in the most highly contaminated regions; Potential effects of prenatal irradiation on the brain as a result of the Chernobyl accident; Nutritional status of population living in regions with different levels of contamination; Dosimetry of Chernobyl clean-up workers; Radiological passports in contaminated settlements. - Congenital malformations: As a national register was existing since the 1980's and gives the possibility to compare trends before and after the accident, results of congenital malformations describe large results collected over Belarus, There is no evidence of a

  13. Food monitoring for radioactivity concentrations after the Chernobyl accident: Consequences for the citizen

    Radioactively contaminated food accounts for most of the radiation exposure after the Chernobyl reactor accident. Hence, food low in radiation will allow to kerb exposure. Precautions include a general identification of radioactivity contents in food commodities by industry and trade as well as preferential supply of pregnant women, nursing mothers and young children with low-activity food. Such food would have an acceptable level of 10 Bq Cs 137/kg. Private precautions are needed for as long as the government fails to initiate corresponding measures. (DG)

  14. Environmental consequences of the Chernobyl accident and their remediation: 20 years of experience

    The Chernobyl Forum was organized by the United Nations to examine the health and environmental effects of the accident at the Chernobyl Nuclear Power Station Unit Number 4. This paper is concerned with the environmental effects, including human exposure, as determined by the Expert Group on Environment. The accident on 26 April 1986 resulted in the release of a large amount of radioactive materials over a period of ten days. These materials were deposited throughout Europe (and to a minor extent throughout the remainder of the northern hemisphere) with the three more affected countries being Belarus, the Russian Federation and Ukraine. The more important radionuclides from a human dosimetric standpoint were 131I, 134Cs and 137Cs, with half-lives of 8 d, 2 a and 30 a, respectively. More than five million persons lived on territories in these three countries judged to be contaminated at >37 kBq/m2. Many countermeasures were employed to mitigate the effects of the accident, with the main focus being on urban and agricultural areas. The collective effective dose to the residents of the contaminated territories is estimated to be about 55 000 man Sv; the collective thyroid dose is estimated to be 1.6 x 106 man Gy. Effects on non-human biota were observed that ranged from minor to lethal; a notable effect was the killing of a pine forest near the accident site. The current increase in the number and diversity of species in the most contaminated area is due to the absence of human pressure. The current shelter over the damaged reactor was constructed under time pressure, and it has significant leakage or airborne radionuclides and inflow of rainwater. The immediate waste management practices were chaotic and remediation is needed. It is planned to build an NSC structure over the top of the existing structure and to eventually dismantle the damaged reactor. This will put additional pressure on waste management, including the need for a new site for geologic disposal of

  15. Development of hydrogeological modelling approaches for assessment of consequences of hazardous accidents at nuclear power plants

    This paper introduces some modeling approaches for predicting the influence of hazardous accidents at nuclear reactors on groundwater quality. Possible pathways for radioactive releases from nuclear power plants were considered to conceptualize boundary conditions for solving the subsurface radionuclides transport problems. Some approaches to incorporate physical-and-chemical interactions into transport simulators have been developed. The hydrogeological forecasts were based on numerical and semi-analytical scale-dependent models. They have been applied to assess the possible impact of the nuclear power plants designed in Russia on groundwater reservoirs

  16. Study on consequences of radioactive iodine pollution and iodine prophylaxis after Chernobyl accident in Cracow region

    Program of investigations of effects of radiation and iodine prophylaxis undertaken after Chernobyl accident in Cracow region had to be modified due to goiter endemic in this region.These modifications included: 1) Division of the region into 3 areas (voivodeship Nowy Sacz, urban voivodeship Cracow and area of Kielce and Swietokrzyskie Mountains). 2) Study on iodine uptake in food and urinary secretion. 3) Examination of iodine level in drinking water, and an attempt of calculation of radiation dose absorbed by thyroid. Characterization of selected areas, principles of selection of study groups are presented as well as organisational details and methods of data collection. (author). 11 refs, 2 tabs

  17. Updated action plan for the implementation of measures as a consequence of the Fukushima reactor accident

    The action plan of the German government concerning the measures following the Fukushima reactor accident include the decision on the future of nuclear power in Germany, safety analyses, investigations and measures for nuclear power plants in a national frame, investigations in an international frame, planning for the implementation of CNS (Convention on nuclear safety) topics 1-3, i.e. measures to increase the robustness in German nuclear power plants, and the planning of implementation of further measures (CNS topics 4-6).

  18. Calculation notes that support accident scenario and consequence determination of a waste tank criticality

    The purpose of this calculation note is to provide the basis for criticality consequences for the Tank Farm Safety Analysis Report (FSAR). Criticality scenario is developed and details and description of the analysis methods are provided

  19. Evaluating the consequences of loss of flow accident for a typical VVER-1000 nuclear reactor

    Mirvakili, S.M.; Safaei, S. [Shiraz Univ., Shiraz (Iran, Islamic Republic of). Dept. of Nuclear Engineering, School of Mechanical Engineering; Faghihi, F. [Shiraz Univ., Shiraz (Iran, Islamic Republic of). Safety Research Center

    2010-07-01

    The loss of coolant flow in a nuclear reactor can result from a mechanical or electrical failure of the coolant pump. If the reactor is not tripped promptly, the immediate effect is a rapid increase in coolant temperature, decrease in minimum departure from nucleate boiling ratio (DNBR) and fuel damage. This study evaluated the shaft seizure of a reactor coolant pump in a VVER-1000 nuclear reactor. The locked rotor results in rapid reduction of flow through the affected reactor coolant loop and in turn leads to an increase in the primary coolant temperature and pressure. The analysis was conducted with regard for superimposing loss of power to the power plant at the initial accident moment. The required transient functions of flow, pressure and power were obtained using system transient calculations applied in COBRA-EN computer code in order to calculate the overall core thermal-hydraulic parameters such as temperature, critical heat flux and DNBR. The study showed that the critical period for the locked rotor accident is the first few seconds during which the maximum values of pressure and temperature are reached. 10 refs., 1 tab., 3 figs.

  20. Managing Errors to Reduce Accidents in High Consequence Networked Information Systems

    Ganter, J.H.

    1999-02-01

    Computers have always helped to amplify and propagate errors made by people. The emergence of Networked Information Systems (NISs), which allow people and systems to quickly interact worldwide, has made understanding and minimizing human error more critical. This paper applies concepts from system safety to analyze how hazards (from hackers to power disruptions) penetrate NIS defenses (e.g., firewalls and operating systems) to cause accidents. Such events usually result from both active, easily identified failures and more subtle latent conditions that have resided in the system for long periods. Both active failures and latent conditions result from human errors. We classify these into several types (slips, lapses, mistakes, etc.) and provide NIS examples of how they occur. Next we examine error minimization throughout the NIS lifecycle, from design through operation to reengineering. At each stage, steps can be taken to minimize the occurrence and effects of human errors. These include defensive design philosophies, architectural patterns to guide developers, and collaborative design that incorporates operational experiences and surprises into design efforts. We conclude by looking at three aspects of NISs that will cause continuing challenges in error and accident management: immaturity of the industry, limited risk perception, and resource tradeoffs.

  1. Estimation of health in Chernobyl NPP accident consequences cleaning-up participants

    Over 11 years period of health observation of Chernobyl Accident's victims permits to make some conclusions. Quantitative changes of peripheral blood and bone marrow cells, changes in ultrastructural organization of hemopoietic cells, disturbance of proliferative activity of hemopoietic and stromal progenitor cells in clean-up workers testify to alterations of functional properties of hemopoiesis. There are high level of T- helpers, early appearance regenerated T-cells, which simultaneously express surface antigens of helpers and supressors, synchronization of proliferative cycle of immunocompetentive cells in these patients. Oppressing of antioxidant protection, stable changes of hormonal maintenance of adaptation and reproduction processes, disturbance of feedback mechanism between effector glands and hypophysis, significant rise of polyamines were determined. Cardiovascular diseases are the principal cause of health disruptions at victims. Neural and psychological diseases, suicidal cases, trauma, death in automobile accidents are rank second and third in structure of morbidity. In structure of chronic nonspecific pulmonary diseases dominated chronic obstructive bronchitis. The adrenergic tonus of vegetative nervous system was seen. The peculiarity of rehabilitation measures is complexness and continuity in-patients, out-patients service and providing facilities in health resorts. (author)

  2. Early clinical consequences of victims in JCO criticality accident in Tokaimura

    The JCO criticality accident occurred at 10:35 on September 30, 1999 when two workers (O and S) poured the solution of uranyl nitrate into the precipitation tank and one (Y) worked at desk in the neighboring room. O's symptoms were unconsciousness, rigidity and emesis, and S's, numbness. The three were moved to Mito National Hospital by an ambulance car at 12:07 and then to the Hospital of National Institute of Radiological Sciences by the helicopter and car at 15:25, where contamination of their cloths by Na-24, suggesting the exposure to neutron, was found. O exhibited emesis within 10 min after the accident and diarrhea, unconsciousness and severe pyrexia within 1 hr, suggesting he had undergone the lethal exposure of >8 Gy. S showed emesis, light unconsciousness and numbness within 1 hr, suggesting >6 Gy and Y did not show even emesis, less dose exposure than the two. They underwent firstly the drip of sodium hydrogen carbonate (due to possible internal exposure of uranium), oxygen inhalation and then corticoid injection as well as the drip of antibiotics. At that day, they had the special therapy with pentoxyphylline and L-glutamine+elementary diet. Later, in the Hospital of Tokyo University, O and S had the heamopoietic stem cell transplantation. At present, O passed away, S is still in hospital and Y is discharged. (K.H.)

  3. Medical consequences of the Kyshtym radiation accident of 29 September 1957

    As a result of the accidental release of long-lived radionuclides, the gamma-radiation dose rate in the near zone of the trail reached tens of cGy per hour and, in a number of populated areas in the open countryside, 0.1 c Gy x hour-1. The evacuation of 10 730 people reduced the possible radiation doses by 2-24 times. Examination of people who had received the highest effective dose equivalents prior to evacuation (2.3-52 cSv) revealed, in the first two years, instability in leukocytes and thrombocytes (used as indicators), but this did not exceed normal fluctuations. The structure of morbidity and mortality among the adult and child populations and the incidence of congenital pathology and infant mortality do not differ from the control. The proportion of families with children born of parents aged between 10 and 30 at the time of the accident does not differ from the same indicators for the whole of the USSR, and, in the case of those aged between 0 and 9 years at the time of the accident, this proportion is 5-10% lower than control values, although the number of people who married is considerably higher than in the control group. In addition, the standardized birthrate coefficients in the study group (31.8 x 10-3) are considerably higher than in the control group (18.4 x 10-3). (author)

  4. The ecological consequences of transuranium elements realize on Belarus as a result of Chernobyl NPP accident

    The levels of radioactive contamination with transuranium elements (TUE) on territory of Belarus as a result of nuclear weapon tests and Chernobyl NPP accident have been assessed . The uniform contamination of soil with level of 53±17 Bq/m2 for Pu-239+240 was formed as a result of global precipitation after the nuclear weapon test. This value increased up to 1.1·105 Bq/m2 in South regions of Belarus and gradually decreased to level of global fall out on the North of the republic after Chernobyl NPP accident. The study of the atmosphere contamination with TUE in Republic of Belarus is being held since 1980 to now. The mechanism of radioactive air pollution from April, 1986 is determined by dust transfer from radioactive contaminated regions. The value of this transfer is influenced considerably by agricultural activities on contaminated territory, forest fires and other anthropogenic factors. The transfer coefficients in the soil-plant system have plant species dependence. The behavior of TUE in environment is discussed. (Authors)

  5. Plutonium recycling in PWR

    Two concepts of 100% MOX PWR cores are presented. They are designed such as to minimize the consequences of the introduction of Pu on the core control. The first one has a high moderation ratio and the second one utilizes an enriched uranium support. The important design parameters as well as their capabilities to multi recycle Pu are discussed. We conclude with the potential interest of the two concepts. (author)

  6. Proceedings of the first part of a joint OECD(NEA)/CEC workshop on recent advances in reactor accident consequence assessment

    The first part of the Joint Workshop, organised by the NEA, is focused on the progress achieved in the work of CSNI's GRECA (Group of Experts on Accident Consequences). The program is composed of the following papers. Session 1: characteristics of the Chernobyl release and fallout that affect transport and behaviour of radioactive substances in the environment; Chernobyl accident and hot particles in the fallout; radionuclides associated with colloids and particles in the Chernobyl fallout; source term in the Chernobyl accident; long range transport of radionuclides; parameters in consequence calculations for an urban area. Session 2: review of evaluations concerning radionuclide transfer to foodstuffs via plants in view of the data available after the Chernobyl accident; GRECA review of Chernobyl data on transfer to animal products; Chernobyl accident radiometric data (Cs-137 in fresh water fishes of north Italy lakes); distribution of Cs-137 in water sediment and fish in the Ijsselmeer (Netherlands); uptake in the human body resulting from the Chernobyl accident; radioactivity of people in the nordic countries following the Chernobyl accident; preparations for an international study to evaluate long-range transport models against the Chernobyl accident

  7. 核电厂蒸汽发生器传热管断裂事故运行管理%Operation Research on Steam Generator Tube Rupture Accident in PWR NPPs

    郭城

    2013-01-01

    This paper comprehensively analyzes PWR steam generator heat transfer tube rupture accident (SGTR), and summarizes the accident processing key strategies in the terms of detection means and event nuclear safety analysis. It analyzes the accident processing difficulty and key risk. Taking the America Indian point2 nuclear power plant SGTR as an example, the events de tailed process is described and the corresponding operation experience is given.%全面分析压水堆核电厂蒸汽发生器传热管断裂(SGTR)事故,从探测手段和事件核安全分析方面总结事故处理的关键策略,分析事故处理的难点及关键风险.以美国Indian point 2核电厂的SGTR事故为例,阐述事件的详细处理过程,给出了相应的操作经验教训.

  8. Accidents - Chernobyl accident; Accidents - accident de Tchernobyl

    NONE

    2004-07-01

    This file is devoted to the Chernobyl accident. It is divided in four parts. The first part concerns the accident itself and its technical management. The second part is relative to the radiation doses and the different contaminations. The third part reports the sanitary effects, the determinists ones and the stochastic ones. The fourth and last part relates the consequences for the other European countries with the case of France. Through the different parts a point is tackled with the measures taken after the accident by the other countries to manage an accident, the cooperation between the different countries and the groups of research and studies about the reactors safety, and also with the international medical cooperation, specially for the children, everything in relation with the Chernobyl accident. (N.C.)

  9. Radiocontamination patterns and possible health consequences of the accident at the Chernobyl nuclear power station

    The main hazard in the early phase after Chernobyl was radioiodine. Thyroid doses were esimated separately for (i) zones of strict control, (ii) most contaminated provinces (iii) the whole central European region of the USSR. Distinction was made between children under the age of 7 years at the time of the accident and the rest of the population. In the later phase the main concern is whole-body exposure to radiocaesium. Doses were calculated for the same areas and age groups as radioiodine. The following were considered: thyroid malignancies, leukaemia, other types of cancer, genetic defects and teratogenic anomalies. A stastistically significant excess over the spontaneous level is unlikely to be detectable for these effects, with the possible exception of thyroid disorders. The risk was greatly reduced by preventive measures, in particular lifetime doses have been restricted by establishment of a limit of 0.35 Sv. (author)

  10. Health effects models for off-site radiological consequence analysis of nuclear reactor accidents

    A first version of models has been developed for predicting the number of occurrences of health effects induced by radiation exposure in nuclear reactor accidents. The models are based on the health effects models developed originally by Harvard University (NUREG/CR-4214). These models are revised on the basis of the new information on risk estimates by the reassessment of the radiation dosimetry in Hiroshima and Nagasaki. The models deal with the following effects: (1) early effects models for bone marrow, lungs, gastrointestinal tract, central nervous system, thyroid, skin and reproductive organs, using the Weibull function, (2) late somatic effects models including leukemia and cancers of breast, lungs, thyroid, gastrointestinal tract and so forth, on the basis of the information derived from epidemiological studies on the atomic bomb survivors of Hiroshima and Nagasaki, (3) models for late and developmental effects due to exposure in utero. (author)

  11. Probability and consequences of severe reactor accidents. 60th year atw

    Rasmussen, Norman Carl [Massachusetts Institute of Technology (MIT), Cambridge, MA (United States). Dept. of Nuclear Engineering

    2015-06-15

    The study carried out on behalf of former USAEC (United States Atomic Energy Commission) led by Prof. Rasmussen and published in reworked form as WASH 1400 by the USNRC (United States Nuclear Regulatory Commission) in 1975, assessed in 3,300 pages the risks that can be deducted from severe accidents in nuclear power plants. The results, often quoted and criticised, were so far the most conclusive statements to this question. In his lecture at the reactor meeting in 1976, Prof. Rasmussen tried to trace back the conclusion of the results to the question: Is the use of larger nuclear power plants, in accordance to experiences and calculations so far, acceptable? His risk assessment, related to American power plants and cites, on behalf of the BMI is currently evaluated by the IRS together with the LRA on specific occurrences within the Federal Republic of Germany.

  12. The French-German initiative for Chernobyl: programme 3: Health consequences of the Chernobyl accident

    Tirmarche, M. [Institut de Radioprotection et de Surete Nucleaire (IRSN), Radiological Protection and Human Health Div. (DRPH), Radiobiology and Epidemiology Dept., 92 - Fontenay-aux-Roses (France); Kellerer, A.M. [Munchen Univ., Strahlenbiologisches Institut (Germany); Bazyka, D. [Chornobyl Center (CC), Kiev regoin (Ukraine)

    2006-07-01

    - Goals: The main objectives of the health programme are collection and validation of existing data on cancer and non cancer diseases in the most highly contaminated regions of Ukraine, Russia and Belarus, common scientific expertise on main health indicators and reliable dosimetry, and finally communication of the results to the scientific community and to the public. - General Tasks: 1- Comparison between high and low exposed regions, 2- Description of trends over time, 3- Consideration of specific age groups. This methodological approach is applied on Solid cancer incidence and leukaemia incidence in different regions in Ukraine, Belarus and Russia, With a special focus on thyroid cancer in young exposed ages. - Thyroid cancer: Those exposed in very young ages continue to express a relatively high excess of thyroid cancer even though they have now reached the age group 15-29. Those exposed as young adults show a small increase, at least partly due to better screening conditions - Leukemia: Description of leukemia trends for various age groups show no clear difference between exposed and unexposed regions when focusing on those exposed at very young ages. The rates of childhood leukemia before and after the accident show no evidence of any increase (oblasts in Belarus over 1982-1998). - Specific studies: Incidence of congenital malformations in Belarus; Infant mortality and morbidity in the most highly contaminated regions; Potential effects of prenatal irradiation on the brain as a result of the Chernobyl accident; Nutritional status of population living in regions with different levels of contamination; Dosimetry of Chernobyl clean-up workers; Radiological passports in contaminated settlements. - Congenital malformations: As a national register was existing since the 1980's and gives the possibility to compare trends before and after the accident, results of congenital malformations describe large results collected over Belarus, There is no evidence of a

  13. Parameters of peroxidation and proteolysis in the organism of the liquidators of Chernobyl accident consequences.

    Lykholat, E A; Chernaya, V I

    1999-01-01

    The specificity of lung irradiation caused by ionizing radiation is influence on mucous membranes of respiratory ways, alveolar epithelium and capillaries of a small circle of the blood circulation. Under diseases of bronchus-lung system the lipid peroxidation (LPO) processes activation is observed. The radiating influence strengthening effect. In results in imbalance aggravation in system "LPO-antioxidants", and long expressing of LPO intensification is the important mechanism of the inflammation chronization. The sharp increase of proteolytic activity and inhibitor activity decrease is found out in the patients-liquidators. Noticed imbalance results in the further change of permeability of membranes and correlates with an index of endoscopy inflammation changes and index of irreversible changes in lung tissue. Thus, the direct connection between LPO intensity and imbalance degree of proteinase-inhibitor system of blood at the patients with chronic bronchitic taking part in Chernobyl accident liquidation is revealed. PMID:10609329

  14. Probability and consequences of severe reactor accidents. 60th year atw

    The study carried out on behalf of former USAEC (United States Atomic Energy Commission) led by Prof. Rasmussen and published in reworked form as WASH 1400 by the USNRC (United States Nuclear Regulatory Commission) in 1975, assessed in 3,300 pages the risks that can be deducted from severe accidents in nuclear power plants. The results, often quoted and criticised, were so far the most conclusive statements to this question. In his lecture at the reactor meeting in 1976, Prof. Rasmussen tried to trace back the conclusion of the results to the question: Is the use of larger nuclear power plants, in accordance to experiences and calculations so far, acceptable? His risk assessment, related to American power plants and cites, on behalf of the BMI is currently evaluated by the IRS together with the LRA on specific occurrences within the Federal Republic of Germany.

  15. Study on Severe Accident Consequence Probability Safety Assessment Method of Nuclear Power Plant%核电站严重事故后果概率安全评价方法研究

    王晗丁; 朱姚瑶; 杨英豪; 杨志超

    2015-01-01

    The probability safety assessment (PSA ) method of nuclear power plant (NPP) severe accident consequence is to apply probability theory to analyze radioactive consequences of nuclear power plant and assess quantitatively the public health effects around nuclear power plants . Taking a domestic PWR NPP as a reference site , an appropriate off‐site consequence analysis model was established .The stratified sampling method was used for meteorological sampling within a year meteorological data ,and the radioactive source term and release characteristics data were from level two PSA .Using nuclear power plant accident consequence assessment code to calculate the off‐site severe accident consequences ,the results obtained by probability method were assessed .The off‐site individual dose of each accident and accident spectrum can be expressed as CCDF curve and total frequency‐dose curves by means of calculation , and according to the probability assessment method ,the conditional probability of individual doses exceeding the specified dose can be obtained .Also this method can be used to quantify the most severe accident sequences described in the safety standards for determining the plume emergency planning zone .%核电站严重事故后果概率安全评价(PSA )是采用概率论的方法对核电站放射性后果进行分析,并定量给出放射性物质对核电站周围公众的健康效应影响。以国内某压水堆核电站为参考厂址,建立合适的场外后果分析模型。采用分层抽样方法对参考厂址1a的气象数据进行抽样,源项和释放特征等数据取自二级PSA的研究结果。利用事故后果评价程序对核电站严重事故后果进行计算,并用概率论方法对结果进行评估。通过计算将各事故和事故谱的场外个人剂量表示为CCDF曲线和总频率‐剂量曲线,再用概率论方法得到不同距离处个人剂量超过指定剂量的条件概率;也可用此方法

  16. IRSN press briefing on the issue 'Fukushima, one year after': Situation of Fukushima Dai-ichi nuclear installations; Accident of the Fukushima Dai-ichi: briefing on the situation in February 2012; The Fukushima 1 accident one year after: assessment of environmental consequences in Japan; assessment of consequences of the Fukushima accident on the environment in Japan, one year after; Health consequences of the Fukushima Dai-ichi: situation briefing in February 2012

    This document gathers reports and Power Point presentations (with maps, data tables and graphs) dealing with the Fukushima accident, one year after its occurrence. Different issues are addressed: the status of the nuclear installations, the situation of the installations and of the environment, assessments, measurements and investigations on the effects and consequences of the accident (radioactive releases and fallouts) on the ground and marine environment and on public health

  17. Help guides for post-accident consequence management: farm activities and exiting the emergency phase; Les guides d'aide a la gestion des consequences post-accidentelles: activites agricoles et sortie de la phase d'urgence

    Cessac, B.; Reales, N. [Institut de Radioprotection et de Surete Nucleaire, BP 17 - 92262 Fontenay-aux-Roses (France); Mehl-Auget, I. [Autorite de Surete Nucleaire - 6, place du Colonel Bourgoin - 75012 Paris (France)

    2010-07-01

    After having recalled the main actions foreseen in the PPIs (plans particuliers d'intervention, intervention specific plans) in case of radionuclide release in the environment after a nuclear accident, i.e. sheltering and ingestion of steady iodine, and also indicated the different phases of consequence management (preparation, emergency and post-accident phases), this report describes and comments the contents of two guides published by the IRSN (the French Radioprotection and Nuclear Safety Institute) and dealing with the management of post-accident consequences. The first one is a guide to aid to decision-making for the management of the agricultural sector in case of nuclear accident, and the second one is a guide for the preparation of the end of the emergency phase in which actions to be performed during the first week after the end of accidental releases are described

  18. Frictional Behavior of Fe-based Cladding Candidates for PWR

    After the recent nuclear disaster at Fukushima Daiichi reactors, there is a growing consensus on the development of new fuel systems (i.e., accident-tolerant fuel, ATF) that have high safety margins under design-basis accident (DBA) and beyond design-basis accident (BDBA). A common objective of various developing candidates is to archive the outstanding corrosion-resistance under severe accidents such as DBA and DBDA conditions for decreasing hydrogen production and increasing coping time to respond to severe accidents. ATF could be defined as new fuel/cladding system with enhanced accident tolerant to loss of active cooling in the core for a considerably longer time period under severe accidents while maintaining or improving the fuel performance during normal operations. This means that, in normal operating conditions, new fuel systems should be applicable to current operating PWRs for suppressing various degradation mechanisms of current fuel assembly without excessive design changes. When considering that one of the major degradation mechanisms of PWR fuel assemblies is a grid-to-rod fretting (GTRF), it is necessary to examine the tribological behavior of various ATF candidates at initial development stage. In this study, friction and reciprocating wear behavior of two kinds of Fe-based ATF candidates were examined with a reciprocating wear tests at room temperature (RT) air and water. The objective is to examine the compatibilities of these Fe-based alloys against current Zr-based alloy properties, which is used as major structural materials of PWR fuel assemblies. The reciprocating wear behaviors of Fe-based accident-tolerant fuel cladding candidates against current Zr-based alloy has been studied using a reciprocating sliding wear tester in room temperature air and water. Frictional behavior and wear depth were used for evaluating the applicability and compatibilities of Fe-based candidates without significant design changes of PWR fuel assemblies

  19. Frictional Behavior of Fe-based Cladding Candidates for PWR

    Lee, Young-Ho; Kim, Hyung-Kyu [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Byun, Thak Sang [Oak Ridge National Lab., Oak Ridge (United States)

    2014-10-15

    After the recent nuclear disaster at Fukushima Daiichi reactors, there is a growing consensus on the development of new fuel systems (i.e., accident-tolerant fuel, ATF) that have high safety margins under design-basis accident (DBA) and beyond design-basis accident (BDBA). A common objective of various developing candidates is to archive the outstanding corrosion-resistance under severe accidents such as DBA and DBDA conditions for decreasing hydrogen production and increasing coping time to respond to severe accidents. ATF could be defined as new fuel/cladding system with enhanced accident tolerant to loss of active cooling in the core for a considerably longer time period under severe accidents while maintaining or improving the fuel performance during normal operations. This means that, in normal operating conditions, new fuel systems should be applicable to current operating PWRs for suppressing various degradation mechanisms of current fuel assembly without excessive design changes. When considering that one of the major degradation mechanisms of PWR fuel assemblies is a grid-to-rod fretting (GTRF), it is necessary to examine the tribological behavior of various ATF candidates at initial development stage. In this study, friction and reciprocating wear behavior of two kinds of Fe-based ATF candidates were examined with a reciprocating wear tests at room temperature (RT) air and water. The objective is to examine the compatibilities of these Fe-based alloys against current Zr-based alloy properties, which is used as major structural materials of PWR fuel assemblies. The reciprocating wear behaviors of Fe-based accident-tolerant fuel cladding candidates against current Zr-based alloy has been studied using a reciprocating sliding wear tester in room temperature air and water. Frictional behavior and wear depth were used for evaluating the applicability and compatibilities of Fe-based candidates without significant design changes of PWR fuel assemblies

  20. An overview of current knowledge concerning the health and environmental consequences of the Fukushima Daiichi Nuclear Power Plant (FDNPP) accident.

    Aliyu, Abubakar Sadiq; Evangeliou, Nikolaos; Mousseau, Timothy Alexander; Wu, Junwen; Ramli, Ahmad Termizi

    2015-12-01

    Since 2011, the scientific community has worked to identify the exact transport and deposition patterns of radionuclides released from the accident at the Fukushima Daiichi Nuclear Power Plant (FDNPP) in Japan. Nevertheless, there still remain many unknowns concerning the health and environmental impacts of these radionuclides. The present paper reviews the current understanding of the FDNPP accident with respect to interactions of the released radionuclides with the environment and impacts on human and non-human biota. Here, we scrutinize existing literature and combine and interpret observations and modeling assessments derived after Fukushima. Finally, we discuss the behavior and applications of radionuclides that might be used as tracers of environmental processes. This review focuses on (137)Cs and (131)I releases derived from Fukushima. Published estimates suggest total release amounts of 12-36.7PBq of (137)Cs and 150-160PBq of (131)I. Maximum estimated human mortality due to the Fukushima nuclear accident is 10,000 (due to all causes) and the maximum estimates for lifetime cancer mortality and morbidity are 1500 and 1800, respectively. Studies of plants and animals in the forests of Fukushima have recorded a range of physiological, developmental, morphological, and behavioral consequences of exposure to radioactivity. Some of the effects observed in the exposed populations include the following: hematological aberrations in Fukushima monkeys; genetic, developmental and morphological aberrations in a butterfly; declines in abundances of birds, butterflies and cicadas; aberrant growth forms in trees; and morphological abnormalities in aphids. These findings are discussed from the perspective of conservation biology. PMID:26425805