Science.gov (United States)

Defense satellites, including the next generation GPS and MILSTAR, continue to require TID well above that of most COTS silicon. ...

Energy Technology Data Exchange (ETDEWEB)

As for Wolsung NPP unit 1, radiation shielding analysis was performed by using neutron diffusion codes, one-dimensional discrete ordinates code ANISN, and analytical methods. But for Wolsung NPP unit 2, 3, and 4, two-dimensional discrete ordinates code DOT substituted for neutron diffusion codes. In other words, the method of analysis and computer codes used for radiation shielding of CANDU 6 type reactor have been improved. Recently Monte Carlo MCNP code has been widely utilized in the field of radiation physics and other radiation related areas because it can describe an object sophisticately by use of three-dimensional modelling and can adopt continuous energy cross-section library. Nowadays Monte Carlo method has been reported to be competitive to discrete ordinate method in the field of radiation shielding and the ...

International Nuclear Information System (INIS)

Remote-controlled handling systems are required for work to be done in the decommissioning and dismantling of nuclear facilities. These systems are equipped with electronic devices suitable for use in working environments affected by ionizing radiation. The publication explains the step-wise progress achieved for improving the radiation resistance of electronic devices with the example of a four-quadrant controlling device for the motors of a manipulator. The radiation resistance of the device could be enhanced to radiation energies of 5.500 Gy. This means that a manipulator vehicle equipped with this controlling device can take up to approx. 15 kGy all in all, taking into account its own shielding properties. (DG).

International Nuclear Information System (INIS)

Optimization of radiation shielding for a medium energy accelerator with 60 MeV alpha ions is carried out using the cost-benefit approach. Cost optimum shield thicknesses are estimated for different operating conditions of the accelerator. (author). 5 refs, 1 tab.

Energy Technology Data Exchange (ETDEWEB)

Shield measurements and four cycles of operating experience have shown the design and construction of radiation shields for the Fast Flux Test Facility (FFTF) reactor and plant to be satisfactory. A number of minor shield deficiencies were found and corrected. Most of these were associated with interfaces between components, each of which was satisfactory by itself. Preliminary evaluation of the shield measurements indicates satisfactory agreement with design calculations. Operator doses to date have been quite small, especially when compared to light water reactor experience.

International Nuclear Information System (INIS)

The first essential before embarking on the radiation-hardening of electrical insulation - mostly magnet coils - in any beam line application is to obtain a reliable estimate of the dose to the components. These are examples ( switchyards at SLAC and LAMPF) where the degree of hardness specified was much higher than was required. Although experience shows that the cost premium for substantial radiation - hardening is of the order of 10%, it has also become clear that well - designed beam line have negligible losses: hardening is required only in the vicinity of targets, collimators or other beam - intercepting devices. Where the beam is deliberately scraped, local shielding will minimize the associated radiation in the surroundings. Electron machines have their own special problems due to synchrotron radiation, so certainly coils and other ...

Energy Technology Data Exchange (ETDEWEB)

The technical complexity of intraoperative radiotherapy (IORT) requires modification of the standard physical and dosimetric methods used in external electron beam therapy. At the National Cancer Institute, a number of technical innovations have been integrated into ongoing clinical studies of IORT. These include: (1) an electron beam applicator system that is significantly different from other IORT systems and includes customized squircle applicators; (2) peripheral dose shields; (3) a modified surgical table replacing the standard radiation treatment couch; and (4) routine use of multiple IORT fields that necessitates field matching. The IORT applicator system and related devices and techniques are dosimetrically characterized in detail both for use in the IORT program and in order to illustrate many useful facets of electron dosimetry.

International Nuclear Information System (INIS)

... alpha particles beta particles gamma radiation lead hot cells bricks shielding

Science.gov (United States)

In massive star formation (gsim 40 M sun) by core accretion, the direct stellar radiation pressure acting on the dust particles exceeds the gravitational force and interferes with mass accretion at the dust sublimation front, the first absorption site. Ram pressure generated by high accretion rates of 10-3 M sun yr-1 is thought to be required to overcome the direct stellar radiation pressure. We investigate the direct stellar irradiation on the dust sublimation front, including the inner accretion disk structure. We show that the ram pressure of the accretion disk is lower than the stellar radiation pressure at the dust sublimation front. Thus, another mechanism must overcome the direct stellar radiation pressure. We suggest that the inner hot dust-free region is optically thick, shielding the dust sublimation front from direct stellar irradiation. Thus, ...

Energy Technology Data Exchange (ETDEWEB)

Thermal-hydraulics analysis can be used to determine location and magnitude of leaks inside a pressurized water reactor (PWR) containment, as required by plant technical specifications. The major advantage of this detection method is that it minimizes radiation exposure of maintenance personnel because most of the leak detection process is performed from the control room outside the containment. In addition, such a program allows for the elimination of pipe whip restraints and jet impingement shields, eliminating costs for maintenance of these supports and shields in older plants and lowering construction costs for new plants. Previously, only simple single-node containment models were used for determining leakage magnitude. This paper presents a more sophisticated multinode approach for determining the magnitude and location. The resulting sensitivities to leak can be programmed into the ...

Energy Technology Data Exchange (ETDEWEB)

The Albedo Theory was applied in order to develop an one-group algorithm for coupled neutron-gamma shielding calculations. The configuration analyzed consists of multilayered plane systems, where a incident neutron current generates gamma radiation through neutron-gamma reactions. The results obtained by Albedo Method and ANISN code have shown excellent agreement. (author)

Energy Technology Data Exchange (ETDEWEB)

The full text follows. A thermal neutron imaging facility (TNIF) capable of real time neutron radiography and computed tomography was developed for the University of Texas TRIGA Mark II (UT-TRIGA) reactor from 1994-1998. The facility was developed with a through reactor beam port capable of producing a 5.2 x 10{sup 6} n/cm{sup 2}/s thermal neutron flux with a gamma dose rate of less than 1 mR/s after collimation. The original TNIF included the UT-TRIGA reactor, neutron collimation array, sample positioning system, neutron image intensifier tube, video camera, computerized image acquisition system, and a radiation shield. A 0.7 mm slit in cadmium was easily detectable using neutron radiography, and 1.4 mm diameter holes bored in an aluminum block were easily resolved using computed neutron tomography. Precise lower limits of the system resolution have hot been determined. The TNIF is currently being revamped to begin work with the ...

Energy Technology Data Exchange (ETDEWEB)

Shielding calculations for neutron-gamma radiation are usually done by using the full Theory of Transport or the Monte Carlo Techniques. After some works based on the Albedo Method, the shielding calculations for neutron-gamma radiation have a reliable tool with great didactical value which shows its clarity and simplicity for the resolution of cases that involve neutrons and photon shielding in nonmultiplying media. The excellent results of these works have motivated the elaboration and the development of this study that will be presented in this dissertation. The balance of a neutronic current entering a shield of two layers considering the coupling neutron-gamma will be determined by the Albedo Method. The shield will be composed of a layer of iron and another one of manganese with 10 cm of thickness each. The arrays of the materials ...

International Nuclear Information System (INIS)

This paper consists the radiation streaming analysis of Horizontal Flux Unit (HFU) penetrations in Calandria Vault of 540 MWe PHWR. There are total 7 HFU penetrations on west wall of calandria vault. As these penetrations are in accessible area, a detailed analysis has been carried out to find the neutron and gamma dose rates around these penetrations when reactor is operating. Analysis has been carried out Using the computer code MCNP and DOT-III. Based on the predictions at HFU penetrations, shielding arrangement was recommended. Neutron and gamma dose rate higher than estimated were observed at TAPS-4. This was because of installed shield not being similar to recommended one due to site conditions. Subsequently semi-empirical calculations using measured data were carried out by MCNP to further augment the existing shield taking into consideration the space limitations at site. (author)

International Nuclear Information System (INIS)

Full text: The principal nuclear design tools available to the shielding designer include diffusion approximation, transport theory, and Monte Carlo techniques. Full transport theory or Monte Carlo methods are routinely used for shielding analyses, where penetration investigations are more sensitive to directional aspects. However, the aim of this paper is to illustrate the coupled neutron-gamma Albedo method particularly as applied to problems of shielding analysis. The multigroup Albedo method is applied to coupled neutron-gamma radiations considering 'n' neutron energy groups and 'g' gamma energy groups to estimate the probabilities of transmission through, absorption in, and reflection from shieldings composed by multiple material layers, 'm' slabs, in which no fission occurs. In this study, these energy groups were selected in order to minimize upscattering effects of the ...

Energy Technology Data Exchange (ETDEWEB)

The Front End Enclosure (FEE) of the Linac Coherent Light Source (LCLS) is a shielding housing located between the electron dump area and the first experimental hutch. The upstream part of the FEE hosts the commissioning diagnostics for the FEL beam. In the downstream part of the FEE, two sets of grazing incidence mirror and several collimators are used to direct the beam to one of the experimental stations and reduce the bremsstrahlung background and the hard component of the spontaneous radiation spectrum. This paper addresses the beam loss assumptions and radiation sources entering the FEE used for the design of the FEE shielding using the Monte-Carlo code FLUKA. The beam containment system prevents abnormal levels of radiations inside the FEE and ensures that the beam remains in its intended path is also described.

Energy Technology Data Exchange (ETDEWEB)

Prompt fission neutron spectrum measurements at the University of Massachusetts Lowell 5.5 MV Van de Graaff accelerator laboratory require that the neutron detector efficiency be well known over a neutron energy range of 100 keV to 20 MeV. The efficiency of the detector, has been determined for energies greater than 5.0 MeV using the Weapons Neutron Research (WNR) white neutron source at the Los Alamos Meson Physics Facility (LAMPF) in a pulsed beam, time-of-flight (TOF) experiment. Carbon matched polyethylene and graphite scatterers were used to obtain a hydrogen spectrum. The detector efficiency was determined using the well known H(n,n) scattering cross section. Results are compared to the detector efficiency calculation program SCINFUL available from the Radiation Shielding Information Center at Oak Ridge National Laboratory.

International Nuclear Information System (INIS)

As a part of the compatibility analysis of DUPIC fuel in CANDU reactors, the radiation physics calculations have been performed for the CANDU primary shielding system, thermal shield, radiation damage, transportation cask and storage. At first, the primary shield system was assessed for the DUPIC fuel core, which has shown that the dose rates and heat deposition rates through the primary shield of the DUPIC fuel core are not much different from those of natural uranium core because the power levels on the core periphery are similar for both cores. Secondly, the radiation effects on the critical components and the themal shields were assessed when the DUPIC fuel is loaded in CANDU reactors. Compared with the displacement per atom (DPA) of the critical component for natural uranium core, that for the DUPIC fuel core was ...

Energy Technology Data Exchange (ETDEWEB)

Two neutron emesis experiments were conducted at the Armed Forces Radiobiology Research Institute (AFRRI). In both experiments (described as Phase I and Phase II) the radiation dose required to cause emesis in 50% of subjects (ED50) was determined for both neutron reactor and gamma reactor source radiation. Emesis onset, offset and duration times post-exposure are reported. Neutrons were maximized from the reactor by passing the beam through a 15.25 cm (6 in.) thick lead wall to filter out gamma photons. Gamma rays were maximized by thermalizing neutrons in 30.5 cm (12 in.) of water, then absorbing the thermal neutrons in a gadolinium-cadmium shield. In Phase I, 28 dogs were exposed to radiation: 12 were exposed to gamma photons at the rate of 0.69 Gy/min and 16 were exposed to neutrons at 1.2 Gy/min. In Phase II, 58 dogs in 3 groups were exposed to radiation: ...

Energy Technology Data Exchange (ETDEWEB)

The principal mathematical tools frequently available for calculations in Nuclear Engineering, including coupled neutron-gamma radiations shielding problems, involve the full Transport Theory or the Monte Carlo techniques. The Multigroup Albedo Method applied to shieldings is characterized by following the radiations through distinct layers of materials, allowing the determination of the neutron and gamma fractions reflected from, transmitted through and absorbed in the irradiated media when a neutronic stream hits the first layer of material, independently of flux calculations. Then, the method is a complementary tool of great didactic value due to its clarity and simplicity in solving neutron and/or gamma shielding problems. The outstanding results achieved in previous works motivated the elaboration and the development of this study that is presented in this dissertation. The ...

International Nuclear Information System (INIS)

This paper addresses the background and the continuously evolving topics of hardening and electronic components. Typical radiation environments from 1960 are described. Examples of a civilian satellite and of future particle physics colliders help illustrate hardening problems. Effects in components, limits of shielding, and three methods of providing components are described. The authors conclude by focusing on both future trends of radiation environments and anticipated progress in electronics. (authors). 10 refs., 9 figs., 4 tabs.

Energy Technology Data Exchange (ETDEWEB)

An apparatus is provided for rapidly restarting the flow of coolant through the cold electromagnetic shield of a superconducting rotor following a thermal transient episode. A vortex diode inhibits coolant flow in the undesirable reverse direction and encourages the reestablishment of a normal thermosyphon cooling loop flow quickly following the termination of a thermal transient such as that caused by transmission line faults. The present invention requires no moving parts and may therefore be permanently sealed in the superconducting rotor without risk of costly repair efforts caused by components failure.

Energy Technology Data Exchange (ETDEWEB)

Background: In an effort to standardise radiological practices in the Republic of Ireland, current legislation states that 'written protocols for every type of standard radiological practice shall be established'. In order to fulfil this requirement the Irish Medical Council recommends the protocols issued by the Commission of European Communitees (CEC) for adoption in the country. Whilst this document does provide good guidance with regard to various radiographic factors, patient shielding instructions are notably ambiguous. The aim of this study was to remove some of this ambiguity by defining the optimal method of positioning patient shielding in antero-posterior (AP) and lateral lumbar spine radiographic examinations. These projections were chosen on the basis of their area of coverage being in close to and in some cases including the reproductive organs. They also represent the highest source of ...

International Nuclear Information System (INIS)

The somatic and genetic radiation exposure of patients undergoing Digital Subtraction Angiography (DSA) and traditional Film Arteriography (FA) of cranial, cervical, thoracic and abdominal vascular territories are compared. The radiation doses absorbed within the critical organs - red bone marrow, lung, thyroid gland and female breast - and in the gonads were measured using an anthropomorphic Alderson phantom. A Somatic Dose Index was calculated in order to estimate the somatic radiation risk. The somatic radiation exposure depends upon the location of the critical organs with respect to the entrance site of the x-ray beam, and can be reduced by an appropriate choice of the angiographic projection. Under this condition, the radiation exposure of the patient during DSA can be lower than during FA. For renal DSA an a.p. projection, the use of an abdominal compression device and ...

International Nuclear Information System (INIS)

Events detected in a shielded plastic scintillation counter occurring in the 26 microsec preceding the arrival of an extensive air shower at ground level with local electron density or = 20 m to the -2 power and the 240 microsec after its arrival have been studied. No significant excess of events (tachyons) arriving in the early time domain have been observed in a sample of 11,585 air shower triggers.

Energy Technology Data Exchange (ETDEWEB)

Numerical errors of PALLAS calculation due to spatial mesh sizes are examined for a typical deep penetration shielding problem of isotropic incident fission neutrons penetrating a 200-cm-thick water slab. The exponential approximation for the source spatial distribution to solve the transport equation based on the direct integration method is verified to be effective for radiation transport in attenuating medium, while the linear approximation employed in the old PALLAS code is found to produce large errors for calculations with large mesh sizes.

Energy Technology Data Exchange (ETDEWEB)

During fluoroscopy the examiner is usually protected by a radiation-reducing body shield, leaving the thyroid unprotected. The fact that the thyroid is located in a region of the neck usually covered by the shirt collar led to the idea of designing a tie with lead core, providing easy and ''decorative'' reduction of the radiation dose. Sonographic examinations were carried out in 20 volunteers (10 men, 10 women) to determine the size of the gland and its coverage by such a tie. The reduction of the surface and organ dose was assessed using film dosimetry with scattered radiation, the body of the examiner being simulated by an Alderson phantom. On average 88% of the thyroid gland surface area was covered. Surface dose was reduced to 1%, and organ dose to 10% of the value without the protection tie. (Author).

International Nuclear Information System (INIS)

Fusion device produces high-level neutrons and #gamma#-rays, which would hazard the safety of the public and workers if the doses would be higher than the regulatory limits because of leakage from the bio-shielding and skyshine. It is essential to monitor the radiation doses in the workshop and the enumerative around fusion devices. A radiation monitoring system (RMS) for full (near and far) areas around a nuclear fusion device has been designed and developed, which can achieve the monitoring and controlling of radiation doses in the workshop area by using the Controller Area Network (CAN), in the institution area by using the Bluetooth Ad hoc network based on a new tree topology formation and routing protocol and in a long range environment by using the General Packet Radio Service (GPRS) network. (authors)

International Nuclear Information System (INIS)

Extra-terrestrial exploration and development missions of the next century will require reliable, low-mass power generation modules of 100 kW_e and more. These modules will be required to support both fixed-base and manned rover/explorer power needs. Low insolation levels at and beyond Mars and long periods of darkness on the moon make solar conversion less desirable for surface missions. For these missions, a closed Brayton cycle energy conversion system coupled with a reactor heat source is a very attractive approach. The authors conducted parametric studies to assess optimized system design trends for nuclear-Brayton systems as a function of operating environment and user requirements. The inherent design flexibility of the closed Brayton cycle energy conversion system permits ready adaptation of the system to future design constraints. This paper describes a dramatic contrast between system designs ...

Energy Technology Data Exchange (ETDEWEB)

To determine if barbiturates would protect brain at high doses of radiation, survival rates in rats that received whole-brain x-irradiation during pentobarbital- or lidocaine-induced anesthesia were compared with those of control animals that received no medication and of animals anesthetized with ketamine. The animals were shielded so that respiratory and digestive tissues would not be damaged by the radiation. Survival rates in rats that received whole-brain irradiation as a single 7500-rad dose under pentobarbital- or lidocaine-induced anesthesia was increased from between from 0% and 20% to between 45% and 69% over the 40 days of observation compared with the other two groups (p less than 0.007). Ketamine anesthesia provided no protection. There were no notable differential effects upon non-neural tissues, suggesting that pentobarbital afforded protection through modulation of ambient neural activity during ...

International Nuclear Information System (INIS)

The Guarantee Outline presents the technical demands of design and contents of assessment for radiation hardening in satellite engineering in China. It includes the basis of design in space environment of polar orbit, the contents of design for general radiation hardening, the requirements and assessments of the single-board computer, the requirements of design for circuits (including hardware and software), the choices and assessments for devices, and the primary stipulations for the requirements of design and assessments against the phenomenon of charge and discharge.

Science.gov (United States)

Photodiode Scintillation Detector for Anticoincidence Shielding An important goal of space research is to understand the physics involved in the activity of ...

Energy Technology Data Exchange (ETDEWEB)

The purpose of this study is to analyze the safeties and the economics for Co-60 production from Wolsung PHWR and to verify the feasibility on the manufacturing of the final Co-60 source for industrial irradiation. The feasibility of reactor conversion was carried out with KEPCO collaboration. Through the site survey on the experience of Gentililly-2 in Canada, a feasibility of plant conversion, changes in design, equipment and tools for Co-60 production was verified. It was estimated that the reactor conversion would not impose adverse impact on plant safety. For the encapsulation of radiation source and storage of the final products, a modification of concrete hot cell at KAERI was primary concerns. The installation and improvement of facilities are needed to avoid cross contamination and extra radiation exposure. Main items for these are pressure gauge, separated HEPA filter the ceiling separation, extra-shielding and ...

International Nuclear Information System (INIS)

Radiation therapy has had a significant and an expanded role in the management of cancer of the pancreas during the last decade. In particular, for locally advanced disease, radiation therapy has improved the median survival of patients to 1 year. Intraoperative electron beam therapy has been applied to unresectable and resectable pancreatic cancer in an attempt to enhance local control of disease and to improve patient survival. This paper presents a survey of the role of radiation therapy in treatment of cancer of the pancreas, provides information on the radiobiological aspects of this treatment modality and details the physical and dosimetric characteristics of intraoperative radiation therapy with electrons. Presented are the design specifics of an applicator system, central axis beam data, applicator parameters, dose distribution data, shielding, treatment planning and means ...

CERN Document Server

Attention is paid to the production mechanisms of light scalars that reveal their nature. We reveal the chiral shielding of the \\sigma(600) meson. We show that the kaon loop mechanism of the \\phi radiative decays, ratified by experiment, points to the four-quark nature of light scalars. We show also that the light scalars are produced in the two photon collisions via four-quark transitions in contrast to the classic P wave tensor q\\bar q mesons that are produced via two-quark transitions $\\gamma\\gamma\\to q\\bar q$. The history of spontaneous breaking of symmetry in quantum physics is discussed in Appendix.

International Nuclear Information System (INIS)

Superconducting generators for high power applications have been of interest for a number of years. Superconducting generators using low temperature superconductors (LTS) have been manufactured to produce up to 20 MW of electrical power and have been configured in either synchronous alternators which have an AC output that may be subsequently rectified to produce DC and homopolar generators which produce low voltage DC. Typically these generators require scrupulous attention to vacuum integrity for cryogenic insulation at 4.2K and tend to be somewhat fragile because of extensive thermal and magnetic shields that are not required in conventional power generators. Recently, high purity aluminum composites have been developed for a high power AC generator that is cooled by cryogenic hydrogen at 21K. This aluminum generator is very compact and lightweight and is much more robust than a generator made with LTS because extensive ...

Energy Technology Data Exchange (ETDEWEB)

The current state and need for radiation protection training in Finland have been surveyed by the Radiation and Nuclear Safety Authority STUK. The survey sought to determine whether the current requirements for radiation protection training had been met, and to promote radiation protection training. Details of the scope and quality of present radiation protection training were requested from all educational institutes and organizations providing radiation protection training. The survey covered both basic and further training, special training of radiation safety officers, and supplementary training. The questionnaire was sent to 77 educational organization units, 66 per cent of which responded. Radiation workers and radiation safety officers were asked about ...

Energy Technology Data Exchange (ETDEWEB)

The ASFIT (Anisotropic Source-Flux Iteration Technique) code was first developed in India about 1970 to solve the radiation transport equation represented in the form of coupled integral equations separating the spatial and energy-angular transmissions. The ASFIT code uses a nodal structure in the wavelength [lambda] domain in Compton units (CU) rather than in the energy domain. The ASFIT-VARI code is the latest version available from the Radiation Shielding Information Center. It incorporates variable dimensioning and has been adapted for use on MS-DOS personal computers using the Ryan-McFarland or Microsoft Version 5.0 FORTRAN compilers. While earlier versions used point cross sections (well suited for gamma-ray transport), the present version also allows multigroup cross sections for neutron and coupled neutron-gamma-ray transport.

Energy Technology Data Exchange (ETDEWEB)

One requirement of a thermophotovoltaic (TPV) radiator is to efficiently emit photons at high temperatures to TPV cells for conversion to electric power. Because many candidate radiator materials with adequate structural properties display low emissivity, coatings or other surface modifications are required for enhancement of emissivity. Six plasma sprayed coatings and one textured surface demonstrated adequate thermal stability and emittance values of 0.8 or greater. Promising attributes of modified surfaces are identified.

Energy Technology Data Exchange (ETDEWEB)

The space environment consists of a varying field of radiation particles including high-energy ions, with spacecraft shielding material providing the only major protection to astronauts from harmful exposure. Unlike low-linear energy transfer (LET) {gamma} or X-rays, the presence of shielding does not always reduce the radiation risks for energetic charged particle exposure, since the dose delivered by the charged particle increases sharply as the particle approaches the end of its range, a position known as the Bragg peak. The Bragg curve does not necessarily represent the biological damage along the particle traversal, and the 'biological Bragg curve' is dependent on the energy and the type of the primary particle, and may vary for different biological endpoints. Here we used a unique irradiation geometry to measure the biological response across the Bragg curve in human fibroblasts ...

Energy Technology Data Exchange (ETDEWEB)

An analyser for detecting explosives has at least one neutron source and a plurality of gamma ray detectors. An article to be analysed is moved adjacent the source and detectors and is subjected to neutrons which generate gamma rays from any nitrogen in the article. The gamma rays are detected and analysed to determine the nitrogen concentration within the article. In order to achieve an area of uniform detection there are a plurality of detectors equidistant both from the or each source and from the article to be analysed. In order to avoid a decrease in sensitivity away from the source(s) and detectors there may be a second opposing array of source(s) and detectors on the opposite side of the article. For greatest uniformity of detection, a source in one array opposes a detector in the other array and vice versa. Transmission of radiation from the analyser is kept at safe levels by enclosing the analyser within shielding which includes ...

International Nuclear Information System (INIS)

Full text: Research reactors have been playing a multi dimensional role in areas of nuclear fuel cycle programme, radio-isotope productions, neutron beam research etc. To ensure an efficient, smooth and safe operation of a nuclear research reactor, many reactor physics evaluations are required on routine basis. As part of reactor core management the important activities are maintaining core reactivity status, core power distribution, xenon estimations, safety evaluation of in-pile irradiation samples and experimental assemblies and assessment of nuclear safety in fuel handling/storage. In-pile irradiation requires a prior estimation of the reactivity load due to the sample, heating rate and the activity developed in it during irradiation. For the safety of the personnel handling irradiated samples the dose rate at the surface of shielded flask housing the irradiated sample should be less than 200 mR/Hr. Therefore, a proper ...

International Nuclear Information System (INIS)

Conformal radiation therapy represents a considerable and attractive challenge in oncology. Its aim is mainly to improve local control by increasing the dose with an acceptable rate of complications. This work overviews the world literature on this subject. The technical and theoretical requirements are highlighted. These requirements include a precise definition of the target volume by digital imaging (essentially CT scan), but also clear view of the target volume and the organs at risk, a specific collimation of the beam, 3-D dose calculations, optimization procedures, and a rigid immobilization of the patient with verification of his position. Moreover, the clinical applications of conformal radiation therapy are reviewed and discussed. (authors). 80 refs., 1 tab.

Energy Technology Data Exchange (ETDEWEB)

The proton beam has a unique advantage over the electron and photon beams in that it can give very high radiation dose to the tumor volume, while effectively sparing the neighboring healthy tissue and organs. For the clinical application of the proton beam, it is very important to confirm the location of the proton beam in the patient, preferentially during the treatment. It has been suggested that the range of the proton beam in the patient can be determined by measuring prompt gammas from the proton beam passage. Recently, a prototype prompt-gamma scanning system has been constructed and tested using experimental and therapeutic proton beams. The measurement results for the proton beams of 70 . 230 MeV showed that a clear correlation exists between the distribution of the prompt gammas and the proton beam range. The scanning method, however, is not suitable for the upcoming 'spot scanning' technique. The 'spot scanning' ...

International Nuclear Information System (INIS)

This monograph provides basic notions and principles in dosimetry and radiation protection in compliance with two fundamental works: IAEA Safety Series No.115 - International Basic Safety Standards for Protection against Ionizing Radiation and for the Safety of Radiation Sources - and Publication no. 60 of International Commission on Radiological Protection. After the review of quantities and units necessary in radiation protection, the book presents the new values of dose limits as well as the values of 'radiation weighting factor', 'tissue weighting factor' and 'conversion factor intake-dose' (committed effective dose per unit intake) by ingestion and inhalation for 30 most important radionuclides. The new values of dose limits, lower than the old values, are a challenge for the radiation protection, especially of the 'public' where the dose limit diminished ...

CERN Document Server

Constraints on target chamber first wall and target designs that will enable NIF debris shields to survive

International Nuclear Information System (INIS)

An attempt was made for early quantitative assessment of the severety of an injury, using the nuclear acids (NA) content as a biochemical indicator. Sexually mature male rats with body mass 160-180 g were irradiated with doses 0.5, 1, 2, 4 and 8 Gy of "1"3"7Cs source. Uneven irradiation was achieved by shielding the abdominal-lumbar area with lead rings, measuring 2,5/50 mm. A 28-30% fall of the dose beneath the shielded zone was thus provided. Dose-dependent quantitative changes in Na content were determined on hours 24 and 72 within the range from 0.5 to 8 Gy and followed up until day 30 after irradiation with nonlethal (2 Gy) and lethal (8 Gy) doses. The total NA content in the leucocytes was determined by the method of Kritski and Aleksandrov. The uneven irradiation of rats within the 0,5-8 Gy range induced early dose-dependent changes in NA content. The nature of their post-irradiation dynamics also depended on the ...

Energy Technology Data Exchange (ETDEWEB)

Recently, the leak-before-break (LBB) concept has been used successfully to eliminate some pipe whip restraints, snubbers and jet impingement shields from the primary reactor cooling system piping of pressurized water reactors. This has resulted in substantial savings in maintenance costs, reductions in radiation exposure of plant service personnel, and has enhanced the overall safety of nuclear power plants. This study provides guidelines to utilities in expanding the application of the LBB concept to additional pipe systems and it couples the concept with hardware optimization. Seven high energy piping systems were investigated for technical feasibility in using the LBB concept. The results indicate that some of these seven lines are good candidates for the leak-before-break application.

Energy Technology Data Exchange (ETDEWEB)

An assay system for the stem cell that colonizes the thymus and differentiates into T cells was developed, and by using this assay system the existence of two subpopulations of stem cells for T cell lineage was clarified. Part-body-shielded and 900-R-irradiated C57BL/6 (H-2b, Thy-1.2) recipient mice, which do not require the transfer of pluripotent stem cells for their survival, were transferred with cells from B10 X Thy-1.1 (H-2b, Thy-1.1) donor mice. The reconstitution of the recipient's thymus lymphocytes was accomplished by stem cells in the donor cells and those spared in the shielded portion of the recipient that competitively colonize the thymus. Thus, the stem cell activity of donor cells can be evaluated by determining the proportion of donor-type (Thy-1.1+) cells in the recipient's thymus. Bone marrow cells were the most potent source of stem cells. By contrast, when the stem cell activity was ...

Energy Technology Data Exchange (ETDEWEB)

The document, based on European guidelines, was jointly developed by radiation oncologists, radiation physicists and radiation technologists. It contains the aims of the guidelines, professional profiles, roles and responsibilities, personnel and equipment requirements, procedures.

International Nuclear Information System (INIS)

The decree refers to conditions of irradiation of food and its components for radappertization and radurization using gamma radiation from cobalt 60 or cesium 137, X radiation or electron beam up to maximum total medium absorbed dose 10 kGy.

British Library Electronic Table of Contents (United Kingdom)

The number of spent fuel storage facilities in the world continues to increase because of "Wait and See" policies and delay of a permanent disposal plan. The temporary spent fuel storage concept is changing to a pre-disposal storage concept. Strengthened safety concepts are required for expanded spent fuel storage facilities and sites. The Korea Hydro and Nuclear Power Company is planning to construct a reinforced concrete MACSTOR-400 facility at Wolsung. In concrete dry spent fuel storage structures, cracks can occur due to radiant heat and environmental chloride. The likelihood of cracking increases over time. Research on changes in shielding performance from one collinear crack in the surface of a concrete facility has been carried out. However there is no research about public radiolog...

International Nuclear Information System (INIS)

We exploit theoretically a class of rectangular cylindrical devices for noise shielding by using acoustic metamaterials. The function of noise shielding is justified by both the far-field and near-field full-wave simulations based on the finite element method. The enlargement of equivalent acoustic scattering cross sections is revealed to be the physical mechanism for this function. This work makes it possible to design a window with both noise shielding and air flow. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

Energy Technology Data Exchange (ETDEWEB)

The purpose of the invention is to improve adaptability of a compression shield to irregularities of a face. This goal is achieved in that a compressible shield is made in the form of a lattice of elastic transverse plates with grooves, elastic vertical elements installed in the grooves, and an elastic plate which is concave toward the face. The plate is located vertically in the middle of the shield. The compressible shield is attached by hinges to a deflector. Telescopic cross pieces are attached by hinges to the covering section of reinforcement, offering the possibility of longitudinal movement at the point of attachment.

International Nuclear Information System (INIS)

Piping systems transporting high-pressure fluid will release a large amount of energy, leading to whipping of the broken pipe as well as impingement of the ejecting fluids on adjacent structures if they fracture unstably. Postulation of such an event in design of piping systems in nuclear power plants often requires various counter measures such as installation of pipe whip restraints or jet impingement shields to prevent such damage. One of the approaches to justify exclusion of unstable fracture from the design conditions is leak-before-break (LBB) analysis. In order to demonstrate LBB behavior, it is necessary to prove that in the presence of a part-through wall flaw in the pipe, this flaw will not grow through the wall under fatigue loading and is stable (level 2 LBB) and that the leak of fluid through the penetration is detected by leak detection systems before unstable fracture occurs (level 3 LBB). If this can be demonstrated in plant ...

International Nuclear Information System (INIS)

The paper discusses some of the assumptions and methods employed for the control of ionizing radiation in the specifications for the civil construction of a planned free electron laser facility based on a 200 MeV, 5 mA superconducting recirculation electron accelerator. Consideration is given firstly to the way in which the underlying building configuration and siting aspects were optimized on the basis of the early assumptions of beam loss and radiation goals. The various design requirements for radiation protection are then considered, and how they were folded into an aesthetically pleasing and functional building. copyright 1997 American Institute of Physics.

International Nuclear Information System (INIS)

This paper consists of shielding analysis of steel balls and water filled end shields of Indian Pressurized Heavy Water Reactors (PHWRs). The material composition inside lattice tube is entirely different neutronically as compared with the composition of end-shield. Due to variation of material composition in radial and axial directions and complex geometry, it is necessary to carry out 3-D analysis for reasonable prediction of neutron flux and gamma dose rates. In the present paper, shielding analysis of end-shield for 540 MWe PHWR has been carried out during reactor operating and shutdown conditions using Monte-Carlo code MCNP. Furthermore materials on the periphery and central portion of end shield are different. Therefore the analysis was carried out separately for annular portion and central portion of end shield. The dominating ...

International Nuclear Information System (INIS)

The invention refers a procedure of radiation dose control in irradiated tissues during electron-beam therapy. It aims at meeting the planned radiation dose for diseased tissues and taking care of the healthy ones. Therefore, the dose distribution required is determined before irradiation in consideration of such factors as energy-dependence of detector sensitivity, self-absorption within the tissue, and relative biological effectiveness. Furthermore, the expected intensity distribution of secondary quantum radiation excited in the irradiated tissue is calculated. A radiation detector for local resolution is used for registration. During irradiation the calculated intensity distribution is compared with the measured one. The invention is applicable in radiation therapy with monoenergetic electron beams.

International Nuclear Information System (INIS)

A car-borne NaI(Tl) spectrometric system was used together with a "1"3"7Cs source to obtain realistic data in the search for unshielded and semi-shielded orphan sources. The potassium-stripped counts (PSC) method was used to estimate the influence by the shielding on the detection ability. A reduction of about 5% in the critical distance was obtained for the semi-shielded source. A curve fitting method was also developed and evaluated. Results from the curve fitting method showed inferior ability to find the source compared to the PSC method. However, it can be a useful complementary tool, for characterisation of the source shielding, and estimation of the distance from the road.

Energy Technology Data Exchange (ETDEWEB)

An experimental investigation of premixed methane-air combustion within the one-dimensional porous ceramic burners for various burner configurations is presented. The burner is nonhomogeneous because of different pore size ceramic block used in different section of the burner. Therefore, the thermophysical and transport properties are nonuniform along the burner core length. The burners are constructed of partially stabilized zirconia. The CO and NO{sub x} emissions, flame speed, and flame stability are examined and compared at lean equivalence ratios for five different burner configurations. The sandwich-structured burner has very favorable flame stabilizing characteristic due to the radiation reflecting region. While the combustion proceeds at faster rate than other burner configurations, the radiation reflecting region and the exit surface have low temperature. Thus the NO{sub x} emission can be kept at the same low level as the other burner ...

International Nuclear Information System (INIS)

In radiation processing of food, the product often has to be prepackaged to prevent microbial recontamination during and after irradiation. The packaging material is exposed to radiation during radiation processing and radiation stability is a key consideration in the selection of packaging materials. The effects of ionizing radiation on many food packaging materials at the dose levels recommended for food precessing can be minimized by selecting appropriate radiation resistant materials. It is important to select materials in which chemicals formed as a result of the radiation treatment do not migrate and interact with the food, affecting its organoleptic and toxicological aspects. It is also important to select materials in which the physical properties are not altered to the extent they cannot resist damage during commercial production, ...

International Nuclear Information System (INIS)

There are many differences between industrial CT and industrial radiography, such as imaging principle, inspection time, radiation dose and the requirements for operators etc. The national standards for radiation protection of industrial detection are not applicable to the requirements of protection and safety for #gamma#-ray industrial CT to some extent now. In order to standardize the production and use for #gamma#-ray industrial CT, protect the safety of operators and the public, and to promote the popularization and application of #gamma#-ray industrial CT, it is significant to establish the national standards for radiation protection of #gamma#-ray industrial CT as soon as possible. The purpose of this paper is to introduce the contents of this standard, and specify some important terms. Then there is a brief discussion on the existing problems during establishing such ...

International Nuclear Information System (INIS)

A design for passive cooling of large containment structures has progressed sufficiently to move forward into the detailed design stage necessary for plant construction. For such application, a safety analysis report has already been submitted to the US Nuclear Regulatory Commission. The design considers an annulus between the inner steel containment vessel and outer, thick-walled concrete shield building with chimney-like natural convection cooling driven only by a density gradient relative to the atmosphere. Air within the annulus is heated as internal containment temperature rises and heat is transferred through the steel containment shell. The resulting air density gradient between the annulus and the environment causes the heated air to rise, producing a natural convection flow through inlets in the shield building, past the steel shell, and out an exit chimney. Several options for enhancing passive heat removal of large containment ...

Energy Technology Data Exchange (ETDEWEB)

The use of deuterium-tritium fuel in the Compact Ignition Tokamak will require applying remote handling technology for ex-vessel maintenance and replacement of machine components. Highly activated and contaminated components of the fusion devices auxiliary systems, such as diagnostics and RF heating, must be replaced using remotely operated maintenance equipment in the test cell. In-vessel remote maintenance included replacement of divertor and first wall hardware, faraday shields, and for an in-vessel inspection system. Provision for remote replacement of a vacuum vessel sector, toroidal field coil or poloidal field ring coil was not included in the project baseline. As a result of recent coil failures experienced at a number of facilities, the CIT project decided to reconsider the question of remote recovery from a coil failure and, in January of 1990, initiated a coil replacement study. This study focused on the technical ...

Energy Technology Data Exchange (ETDEWEB)

The extent to which the size of a modular stellarator reactor may be reduced is investigated by means of an analytic model of the reactor. The various means employed include varying the blanket/shield thickness, the power output and the wall loading. An optimum design is found, the major radius of which tends to be insensitive to changes in these quantities, although a decrease in the power output leads to a rather smaller decrease in reactor dimensions, as would be expected. Varying the plasma beta at fixed (iota/2..pi..)/sup 2/epsilon or, alternatively, increasing the rotational transform per field period, may, however, allow configurations with fewer field periods to be accessed which have a substantially smaller major radius than the 'standard case' adopted. The magnetics of various configurations required by the model are checked by field line following and the performance claimed is shown to be relatively easily ...

Energy Technology Data Exchange (ETDEWEB)

A historical perspective is given of the current paradigm that does not explicitly protect the environment from radiation, but instead, relies on the concept that if dose limits are set to protect humans then the environment is automatically protected as well. We summarize recent international questioning of this paradigm and briefly present three different frameworks for protecting biota that are being considered by the U.S. DOE, the Canadian government and the International Commission on Radiological Protection. We emphasize that an enhanced collaboration is required between what has traditionally been separated disciplines of radiation biology and radiation ecology if we are going to properly address the current environmental radiation problems. We then summarize results generated from an EMSP grant that allowed us to develop a Low Dose Irradiation Facility that specifically ...

Energy Technology Data Exchange (ETDEWEB)

Research on the feasibility of growing cattails as an energy crop is described. The following topics are included: productivity in natural strands, germination requirements for seed, establishing stands by seeding, rhizome dormancy and development, harvesting and stand establishment, and analysis of canopy structure and radiation profiles in a natural community. (MHR)

International Nuclear Information System (INIS)

Reliable values of x-ray and gamma-ray attenuation coefficients of elements and compounds are required in spectrometry as well as in many other scientific, engineering and medical disciplines involving photon radiation

Energy Technology Data Exchange (ETDEWEB)

Historically the Los Alamos Spallation Radiation Effects Facility (LASREF) has used manual methods to control the position of the 800 kW, 800 MeV proton beam on targets. New experiments, however, require more stringent position control more frequently than can be done manually for long periods of time. Data from an existing harp is used to automatically adjust steering magnets to maintain beam position to required tolerances.

International Nuclear Information System (INIS)

The main objective of the present thesis was develop and get operational a real-time neutron radiography system, at the IPEN-CNEN/SP. This system is installed inside the shielding of an old facility, designed in 1988, for film radiography, which is installed at the beam-hole 08 of the 5 MW, IEA-R1 Nuclear Research Reactor. The most important modifications at the such facility were the increase of the #gamma#-radiation filter thickness, increase of the inner area of the shielding, design of a neutron collimator and a light tight box. The main characteristics of the neutron beam at the irradiation position are: flux: 1 x 10"6n/cm"2s, collimation ratio 70, effective energy 7 meV, diameter 20 cm, neutron/#gamma# ratio #approx# 10"6n/cm"2mrem. The real-time images have been obtained by means of an imaging system that consists of a screen scintillator, a light intensifier, a video camera, a digitizing frame grabber and a ...

International Nuclear Information System (INIS)

Personal monitoring and dose assessment of all radiation workers is an essential regulatory requirement as per radiation safety procedures of AERB and operating stations. The occupational workers of TAPS 1 and 2 and TAPS 3 and 4 are monitored for internal contamination due to high energy gamma emitters by whole body counting

Energy Technology Data Exchange (ETDEWEB)

Inactivation of aflatoxin B1 was studied by using gamma radiation and hydrogen peroxide. A 100-krad dose of gamma radiation was sufficient to inactivate 50 micrograms of aflatoxin B1 in the presence of 5% hydrogen peroxide, and 400 krad was required for total degradation of 100 micrograms of aflatoxin in the same system. Degradation of aflatoxin B1 was confirmed by high-pressure liquid chromatographic and thin-layer chromatographic analysis. Ames microsomal mutagenicity test showed loss of aflatoxin activity. This method of detoxification also reduces the toxin levels effectively in artificially contaminated groundnuts.

International Nuclear Information System (INIS)

Long-term aging of organic materials in reactor containment buildings has become a major issue within the nuclear community. In this article, the status of radiation-aging qualification test requirements in several countries is reviewed, and problems with the current aging methodologies are described. These problems include dose-rate and synergistic effects and environmental synergisms, which have been found for many different polymeric materials. A number of approaches to improved accelerated-radiation-aging tests for prediction of long-term aging behavior are discussed together with their limitations.

Energy Technology Data Exchange (ETDEWEB)

The Global Nuclear Energy Partnership (GNEP) is proposing to develop a sodium-cooled fast-spectrum reactor (SFR) to transmute and consume actinides from discharged nuclear fuel. To meet performance objectives, new and advanced fuels and targets need to be developed. The fuels to be irradiated include metal and oxide mixed actinides (U-Np-Pu-Am-Cm); for the target concept, Am-Cm has been considered. A significant part of the development process is the irradiation of the fuel and cladding in a prototypic fast reactor environment to determine the performance under irradiation. Analysis results are presented in this paper for a fast-neutron irradiation facility design based on the large fast neutron flux available in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL) combined with the use of a strongly-absorbing thermal neutron shield. Several designs were assessed; the preferred concept consists of a three-pin design with an europium oxide ...

Science.gov (United States)

... These landing rights were invaluable during Desert Shield/ Desert Storm and may be necessary in securing access to the Arabian Gulf region. ...

Science.gov (United States)

A technical review is presented of experiment activities and state of knowledge on air-borne, radiation source terms resulting from explosive sabotage attacks on spent reactor fuel subassemblies in shielded casks. Current assumptions about the behavior of irradiated fuel are largely based on a limited number of experimental results involving unirradiated, depleted uranium dioxide ''surrogate'' fuel. The behavior of irradiated nuclear fuel subjected to explosive conditions could be different from the behavior of the surrogate fuel, depending on the assumptions made by the evaluator. Available data indicate that these potential differences could result in errors, and possible orders-of-magnitude overestimates of aerosol dispersion and potential health effects from sabotage attacks. Furthermore, it is suggested that the current assumptions used in arriving at existing regulations for the transportation and ...

International Nuclear Information System (INIS)

The Gross Decontamination Experiment was conducted on various levels and surfaces of the TMI-2 Reactor Building during February and March 1982 and was designed to investigate the effectiveness of various surface decontamination techniques. The polar crane, D-rings, missile shields, refueling canal, fueling bridge, major equipment, floors and some walls were flushed with low pressure water. Water lances were directed manually and applied water at temperatures between ambient and 60"0C at a flow rate of about 95 liters per minute. In addition, floor surfaces on the 305-ft elevation and floor surfaces and major equipment on the 347-ft elevation were sprayed with high pressure water (floors in the Reactor Building are designated by their elevations above sea level). The water pressure in this case varied between 13.8 and 41.4 mPa and water temperature was at a maximum 60"0C. Certain surfaces were also decontaminated using either strippable coatings or a mechanical ...

International Nuclear Information System (INIS)

A pilot project was started in 1977 over the Lake Superior basin to measure water storage on the land area using aerial gamma-ray spectrometry to provide hydrologic information for forecasting inflow to the lake. Two airborne surveys were made, respectively in November 1977 and March 1978 which provided estimates of the increase in snow water equivalent between these surveys. The basin is located on the Canadian Shield and consequently, the gamma radiation count rate is quite variable. The airborne results are compared with ground measurements on selected flight lines and show generally good agreement. Two equipment calibrations in the Ottawa area provided inconsistent parameter values which are consequently also reflected in the results over the Lake Superior basin. The project has demonstrated to-date that the technique can be developed into an operational system for measuring snow cover water equivalent of this vast and remote area by using ...

International Nuclear Information System (INIS)

A new dedicated UHV STM for investigations at T#<=#5 K is presented. To achieve such low temperatures and to ensure a high thermal stability, the low-temperature (LT) STM described here has a concentric system of bath cryostats. There are openings for tip and sample exchange at low T, and windows with an infrared radiation shield for optical access, which can both be closed by a door mechanism for LT-STM measurements. Efficient vibration isolation is realized by using spring suspension with eddy current damping. With the 3-d coarse positioning unit any region of interest within 5 mm by 5 mm on the sample is accessible even at 5 K. For short turn-around cycles the sample and tip can both be exchanged at low temperatures. Atomically resolved images of Au(111) at 5 K in UHV demonstrate the excellent performance of this LT STM. As a typical application example the appearance of a charge-density wave on NbSe_2, which occurs below a transition ...

Energy Technology Data Exchange (ETDEWEB)

The proton beam has an advantage of the sharp dose falloff in dose distribution called Bragg peak while conventional radiation therapy modalities such as photons exhibit considerable amount of exit dose. To take advantage of this property it is important to know the exact location of the distal dose falloff. An error can cause overdose to the normal tissue or underdose to the tumor volume. The only way of finding out the dose distribution in-situ in particle therapy is to measure the gammas produced by nuclear reactions with tissue materials. Two kinds of gammas can be used: one is prompt gamma and the other is coincident gamma from the positron-emission isotopes. We chose to detect prompt gammas, and developed a prompt gamma scanning system (PGS). The proton beams of the proton therapy facility at National Cancer Center were used. The gamma distribution was compared to the dose distribution measured by an ionization chamber at three different energies of 100, 150, ...

CERN Document Server

This book examines the applications of Monte Carlo (MC) calculations in therapeutic nuclear medicine, from basic principles to computer implementations of software packages and their applications in radiation dosimetry and treatment planning. It is written for nuclear medicine physicists and physicians as well as radiation oncologists, and can serve as a supplementary text for medical imaging, radiation dosimetry and nuclear engineering graduate courses in science, medical and engineering faculties. With chapters is written by recognised authorities in that particular field, the book covers the entire range of MC applications in therapeutic medical and health physics, from its use in imaging prior to therapy to dose distribution modelling targeted radiotherapy. The contributions discuss the fundamental concepts of radiation dosimetry, radiobiological aspects of targeted radionuclide therapy and the ...

International Nuclear Information System (INIS)

At Tarapur Atomic Power Station 3 and 4, 540 MWe Pressurised Heavy Water Reactors, core being large in size requires a continuous in core monitoring for local flux disturbances. Nearly 200 Self Powered Neutron Detectors (SPNDs) of the Straight Individually Replaceable (SIR) type are distributed in the reactor core. For purpose of reactor regulation and protection, cobalt SPNDs that have a prompt response for changes in power is used for in-core flux mapping, vanadium SPNDs that provide accurate measure of neutron flux, even though having slow response is used In core SPNDs are placed in Vertical Flux Units (VFU) and Horizontal Flux Units (HFUs). These SPNDs were to be replaced at regular intervals to meet the design intent. Cobalt SPNDs have dose rates of the order of 1000 Gy/h and the Mineral Insulated (MI) cables of Vanadium SPNDs have dose rates of the order of 100 Gy/h. So far 3 Cobalt SPNDs were removed from HFUs and are being stored in lead ...

Energy Technology Data Exchange (ETDEWEB)

A low pressure nuclear thermal rocket (LPNTR) is configured to meet the requirements of a nuclear stage for manned Mars exploration. Safety, reliability and performance are given equal consideration in selecting the stage configuration. Preliminary trade studies are conducted to size the engine thrust and determine the thrust chamber pressure. A weight breakdown and mechanical configuration for the selected LPNTR concept are defined. A seven engine stage configuration is selected which gives a two engine out capability and eliminates the need for engine gimbaling. The stage can be ground assembled and launched as a unit including tankage for trans Earth injection and Earth orbital capture. The tankage is configured to eliminate the need for an inert shield. The small engine will be cheaper to develop than a single engine providing full thrust, and will be compatible with stages for Earth orbital, Lunar and deep space missions. Mission analyses ...

International Nuclear Information System (INIS)

The manufacture and use of wood/plastic composite (WPC) as an example of wood matrix and wood sawdust/plastic composites (SDP) as an example of plastic matrix are reviewed. The raw material for WPC are mostly vinyl monomers, particularly methyl methacrylate and styrene. The reaction in WPC polymerization is radical polymerization. Researches on the radiation sources mostly resulted in gamma-ray. Electron beam can be applied only to thin products. The future use of WPC may be for furnitures, sporting goods, decorative parts and the like. Vital study on the reduction of manufacturing costs is required, for example, the improvement of reaction and the adoption of continuous process must be considered. The raw materials for SDP are wood sawdust, vinyl monomer (mostly methyl methacrylate) and resins. Electron beam accelerators are the most preferable radiation source because of its high efficiency and safe operation. SDP shows ...

International Nuclear Information System (INIS)

The integrity of helium circulation loop flanged joints has been attracting recent attention as a design problem, in the development of high-temperature facilities incorporating helium loops (e.g., the VRG-50 pilot nuclear facility). Elevated temperatures and pressures, and the radiation environment, impose additional requirements on sealant materials. This applies first and foremost to rubber seals, which have found widespread favor on account of its excellent elasticity, its ability to spontaneously conform to possible changes in the clearance in the seal assembly, and the low compressive stresses developed in the flange joint assembly.

DEFF Research Database (Denmark)

A simple closed-form equation to calculate the envelope correlation between any two receiver or transmitter antennas in a multi-input multi-output (MIMO) system of an arbitrary number of elements is derived. The equation uses the scattering parameters obtained at the antenna feed point to calculate the envelope correlation coefficient. This approach has the advantage that it does not require knowledge of the antenna radiation pattern. Numerical data that include conductor and permittivity loss are shown to validate the approach. Using the scattering parameters for calculating the envelope correlation is less laborious and relatively cheaper, as compared to the radiation pattern approach.

Energy Technology Data Exchange (ETDEWEB)

The Linac Coherent Light Source (LCLS) will be the world's first x-ray free-electron laser (FEL). To ensure the vitality of FEL lasing, a longitudinal feedback system is required together with other diagnostics. In this paper, we study the possibility of using Coherent Synchrotron Radiation (CSR) from the chicane as a diagnostic tool for bunch length feedback. Studies show that CSR is a good candidate, even for a non-Gaussian, double-horn longitudinal charge distribution as in the LCLS. We further check the possibility for detecting possible microbunching.

Energy Technology Data Exchange (ETDEWEB)

The WAND (Waste Assay for Nonradioactive Disposal) system can scan thought-to-be-clean, low-density waste (mostly paper and plastics) to determine whether the levels of any contaminant radioactivity are low enough to justify their disposal in normal public landfills or similar facilities. Such a screening would allow probably at least half of the large volume of low-density waste now buried at high cost in LANL`s Rad Waste Landfill (Area G at Technical Area 54) to be disposed of elsewhere at a much lower cost. The WAND System consists of a well-shielded bank of six 5-in.-diam. phoswich scintillation detectors; a mechanical conveyor system that carries a 12-in.-wide layer of either shredded material or packets of paper sheets beneath the bank of detectors; the electronics needed to process the outputs of the detectors; and a small computer to control the whole system and to perform the data analysis. WAND system minimum detectable activities (MDAs) for point sources ...

International Nuclear Information System (INIS)

A 450 MeV Synchrotron Radiation Source, Indus-1 is being constructed at Centre for Advanced Technology at Indore in central India. This paper narrates our experience in construction and alignment of synchrotron machines which was first of its kind for most of us. Careful design, planning and execution of the work yielded modest results so that alignment accuracies between 0.1 to 0.3 mm could be achieved (in booster synchrotron) and, which have proved to be adequate up till now. The building of the SRS complex was constructed such that machine rings have their foundations isolated from rest of the building. A number of 100 x 150 mm size steel plates were embedded in the concrete of floor and walls to serve as base for reference surveying marks which were established later. The pre-injector and booster ring are enclosed in a radiation shielding zone with separate ventilation system. Dipoles, quadrupoles and a few sextupoles ...

Science.gov (United States)

Testing was performed to determine the feasibility and processing characteristics of evaporation of actual Defense Waste Processing Facility (DWPF) recycle material. Samples of the Off Gas Condensate Tank (OGCT) and Slurry Mix Evaporator Condensate Tank (SMECT) were transferred from DWPF to the Savannah River National Lab (SRNL) Shielded Cells and blended with De-Ionized (DI) water and a small amount of Slurry Mix Evaporator (SME) product. A total of 3000 mL of this feed was concentrated to approximately 90 mL during a semi-batch evaporation test of approximately 17 hours. One interruption occurred during the run when the feed tube developed a split and was replaced. Samples of the resulting condensate and concentrate were collected and analyzed. The resulting analysis of the condensate was compared to the Waste Acceptance Criteria (WAC) limits for the F/H Effluent Treatment Plant (ETP). Results from the test were compared to previous testing using simulants and ...

Energy Technology Data Exchange (ETDEWEB)

New values of the factors required to convert the reading of a radiation dosemeter calibrated in terms of air kerma (or exposure) into absorbed dose to water for medium-energy x-radiation were given in a code of practice published by the International Atomic Energy Agency in 1987. These are not considered to possess sufficient support from other sources. It is therefore recommended that the F-factors given or codes of practice should continue to be used. Values of backscatter factors for low-energy x-radiation (below 140 kV) in Supplement 17 of the British Journal of Radiology appear to be inaccurate. New values based on Monte Carlo calculations, and supported by new experimental data, are given for use in radiotherapy. (author).

British Library Electronic Table of Contents (United Kingdom)

The initial management of nonfunctioning pituitary macroadenomas (NFAs) is usually surgery; however, a significant proportion of NFAs may require further treatment. Radiotherapy is currently used in patients with residual tumour and achieves excellent long-term control, but there are concerns about potential late toxicity. Stereotactic radiotherapy, both in the form of radiosurgery or fractionated stereotactic radiotherapy, has been developed as a more accurate technique of irradiation with more precise tumour localization and consequently a reduction in the volume of normal tissue, particularly the brain, irradiated to high radiation doses. A review of the literature suggests that new radiation techniques offer safe and effective treatment for recurrent or residual pituitary adenomas; how...

CERN Document Server

An algorithm for creating synthetic telescope images of Smoothed Particle Hydrodynamics (SPH) density fields is presented, which utilises the adaptive nature of the SPH formalism in full. The imaging process uses Monte Carlo Radiative Transfer (MCRT) methods to model the scattering and absorption of photon packets in the density field, which then exit the system and are captured on a pixelated image plane, creating a 2D image (or a 3D datacube, if the photons are also binned by their wavelength). The algorithm is implemented on the density field directly: no gridding of the field is required, allowing the density field to be described to an identical level of accuracy as the simulations that generated it. Some applications of the method to star and planet formation simulations are presented to illustrate the advantages of this new technique, and suggestions as to how this framework could support a Radiative Equilibrium ...

International Nuclear Information System (INIS)

Composite materials of synthetics (based on monomers, oligomers and thermoplastics) and of natural polymers (wood and other fibrous cellulosics) prepared by radiation processing, offer valuable structural materials with enhanced coupling forces between the components. The applied polymer chemistry of such composites shows several common features with that of radiation grafting. E.g. the polymerization rate of oligomer-monomer mixtures in wood remains in most cases proportional to the square-root of the initiating dose-rate, just as in the simultaneous grafting, demonstrating that the chain termination kinetics remain regularly bimolecular in the corresponding dose-rate ranges. In the processing experiences of such composites, low dose requirement, easy process-control, and good technical feasibility have been found for composites of wood with oligomer-monomer mixtures, for coconut fibres with unsaturated polyesters and for ...

Energy Technology Data Exchange (ETDEWEB)

The assessment and control of fetal exposure to radiation in the workplace is an issue that is complicated by both biological and political/social ramifications. As a result of the dramatic increase in the number of women employed as radiation workers during the past 10 years, many facilities using radioactive materials have instituted fetal protection programs with special requirements for female radiation workers. It is necessary, however, to ensure that any fetal protection program be developed in such a way as to be nondiscriminatory. A study has been initiated whose purpose is to balance the political/social and the biological ramifications associated with occupational protection of the developing embryo/fetus. Several considerations are involved in properly balancing these factors. These considerations include appropriate methods of declaring the pregnancy, training workers, controlling the dose ...

International Nuclear Information System (INIS)

The application of robotics for repair, refurbishing or dismantling of nuclear installations implies eventually severe radiation resistance requirements on embarked components and subsystems. This is particularly critical when optical sensing is considered. Optoelectronic components and optical fibers are indeed quite sensitive to radiation, and without special design are rapidly out-of-operation in such an environment. This paper reports the results of a series of #gamma# irradiation experiments on such devices, and identify their behavior under radiation. Test results show that carefully selected optical fibers can keep their radiation induced attenuation lower than 0.3 dB/m even up to a total dose of 10 MGy. Temperature annealing can even lower this attenuation down to 0.1 dB/m. On the other hand, commercially available light emitting diodes and photodiodes present attenuations ...

International Nuclear Information System (INIS)

The textbook is primarily intended for radiologic staff and radiologic safety officers and gives information on the current regulatory provisions of the German X-ray Ordinance, applications of X-rays, quality assurance, organisational aspects of film processing and quality requirements of X-rays. An annex lists the guidelines of the Bundesaerztekammer (German National Chamber of Physicians) relating to quality assurance aspects, and further useful information on commercially available film-screen systems, the various associations of physicians in Germany, and requirements and performance of radiation surveys. (vhe).

Energy Technology Data Exchange (ETDEWEB)

As a part of the program at the Lawrence Livermore National Laboratory (LLNL) in induction-linac free-electron laser (IFEL) research, we are conducting a variety of activities addressing the unique requirements imposed on IFEL wiggler systems. We are actively developing improved dc iron-core electromagnetic wiggler designs to attain higher peak fields, greater tunability, and lower random error levels. We are pursuing specialized control systems, such as magnetic-field and beam-position controllers, which can relax requirements on the wiggler itself. We are also pursuing basic studies to establish the effect of radiation on permanent magnets.

Energy Technology Data Exchange (ETDEWEB)

Epoxy-resin based neutron shielding material, NS-4-FR, is used for spent fuel transport and/or storage cask. In this paper the outline of thermal aging test performed to evaluate the heating effect on this neutron shielding material, NS-4-FR, is introduced. The test is consisted of two kinds of thermal aging test, one is 'Basic Test' and the other is 'Block Heating Test'. The former is cooperatively performed by ten Japanese Electrical Power Companies, and the latter is done by GESC and NOF Corporation. (authors)

Science.gov (United States)

The hydraulic characteristics of flow control multiorifice plate assemblies designed for the FFTF reactor were investigated. The pressure drop flowrate characteristics determined in the test are presented. (JWR)

Science.gov (United States)

... Abstract : Iraqi armored and mechanized divisions crossed the border of ... quick response, the first elements of the 82nd Airborne Division arrived in ...

CERN Document Server

This mechanical version was soon after changed into a hydraulic jack one (the reason being a number of serious constructional defects).

Energy Technology Data Exchange (ETDEWEB)

In the field of reactor and fuel cycle physics, particle transport plays and important role. Neutronic design, operation and evaluation calculations of nuclear system make use of large and powerful computer codes. However, current limitations in terms of computer resources make it necessary to introduce simplifications and approximations in order to keep calculation time and cost within reasonable limits. Two different types of methods are available in these codes. The first one is the deterministic method, which is applicable in most practical cases but requires approximations. The other method is the Monte Carlo method, which does not make these approximations but which generally requires exceedingly long running times. The main motivation of this work is to investigate the possibility of a combined use of the two methods in such a way as to retain their advantages while avoiding their drawbacks. Our work has mainly focused on the speed-up of ...

Energy Technology Data Exchange (ETDEWEB)

A 16 l liquid parahydrogen target has been developed for a measurement of the parity-violating {gamma}-asymmetry in the capture of polarized cold neutrons on protons in the {rvec n} + p {yields} d + {gamma} reaction by the NPDGamma collaboration. The target system was carefully designed to meet the stringent requirements on systematic effects for the experiment and also to satisfy hydrogen safety requirements. The target was designed to preserve the neutron polarization during neutron scattering on liquid hydrogen (LH{sub 2}), optimize the statistical sensitivity to the {rvec n} + p {yields} d + {gamma} reaction, minimize backgrounds coming from neutron interaction with the beam windows of the target cryostat, minimize LH{sub 2} density fluctuations which can introduce extra noise in the gamma asymmetry signal, and control systematic effects. The target incorporates two mechanical refrigerators, two ortho-para convertors, an aluminum cryostat, ...

International Nuclear Information System (INIS)

From the numbers of radiographs of the different examinations and the total amount of radiological diagnostics in the GDR their possible modification by new imaging techniques is discussed under the aspects of costs and radiation burden. Film-screen-systems are of special importance, because they also will be most frequently used image recording system in future. The importance of their various properties and parameters, methods of determining these parameters as well as future developments are analyzed from the standpoint of practical requirements. (author).

International Nuclear Information System (INIS)

Radionuclide (R) sorption from a solution (vapor) by freshly formed crystals with production of substitution solid solutions under different types of self-disordering is studied. Changes of self-defectiveness and macrodefectiveness with time and effect of radiation defects in the presence of P macroquantities are taken into account. An analysis for monodispersed sorbents is performed. It is shown that the achievement of equilibrium within a reasonable time in impurity-solid phase system depends on defectiveness which ensures a required level of the coefficient of impurity diffusion in sorbent crystals.

International Nuclear Information System (INIS)

Radiation exposure control is one of the most important aspects in any nuclear facility . It encompasses continuous monitoring of the various areas of the facility to detect any increase in the radiation level and/or the air activity level beyond preset limits and alarm the O and M personnel working in these areas. Detection and measurement of radiation level and the air activity level is carried out by a number of monitors installed in the areas. These monitors include Area Gamma Monitors, Continuous Air Monitors, Pu-In-Air Monitors, Criticality Monitors etc. Traditionally, these measurements are displayed and recorded on a Central Radiation Protection Console(CRPC), which is located in the central control room of the facility. This methodology suffers from the shortcoming that any worker required to enter a work area will have to inquire about the radiation ...

International Nuclear Information System (INIS)

This thesis reports investigations using gamma-radiation to decontaminate poultry carcasses. The application to foods of doses of ionizing radiation sufficient to reduce the number of viable specific non-sporeforming pathogenic microorganisms so that none is detectable in the treated food by any standard method is termed radicidation. The doses used in this study were at such a level that no undesirable or unfavourable side-effects occurred. The effects of these doses were studied on salmonellae and other microorganisms present in, or associated with poultry carcasses and in liquid and on solid culture media as well. Decimal reduction (D_1_0) values were estimated. These represent the dose (kGy) required to achieve a reduction in initial colony count from N_0 to 0.1 N_0. Together with the estimation of the numbers of Salmonella present per carcass the data were used to predict the effect of an ionizing ...

Energy Technology Data Exchange (ETDEWEB)

The authors investigate the optimisation of solar-heated cavity receivers in which solar energy collected by a paraboloid collector is converted into electrical energy. The focussed solar energy enters the receiver through an aperture to heat the working fluid, which flows inside the receiver tubes and is compressed by the compressor of a gas turbine system, to the highest process temperature. A method of calculating the distribution on the inner receiver surfaces of the solar radiation reflected by the paraboloid collector is presented to begin with. The interchange of radiant energy inside the receiver cavity can be calculated on this basis, including the radiation loads, the temperatures of the inner receiver walls, and the radiative and convective losses. The temperature fields in the tube walls must be known for determining the strength required of receiver tubes; they can be derived from the ...

Energy Technology Data Exchange (ETDEWEB)

The use of hypothesis which assumes a dose / harmful effect relationship without a limit allows the calculation of risks attributable to doses too small to produce detectable, harmful biological effects. The daughter product of this hypothesis is ALARA concept which requires that the dose received is kept as low as reasonably achievable. This concept of prudent avoidance is generally accepted by international radiation protection organisations and universally applied by radiation health professionals. The acceptance of a hypothesis which assumes that a single nuclear event can cause carcinogenesis, has generated levels of anxiety which may have resulted in significant detriment to those possibly exposed to ionising radiation. The anxiety generated may have caused more detriment and a higher death rate than the worst case ` theoretical` value calculated using the Linear or Quadratic Linear Hypothesis. ...

Energy Technology Data Exchange (ETDEWEB)

Safety standards for exposure to radiofrequency radiation must be based upon biologic consequences of exposure to such environments. Behavioral-based measures are considered to be the most-sensitive indices of biological effects. Current safety guidelines are based upon average power density and may not be relevant to the high-peak-power, short pulse width microwave radiation produced by newly developed high peak power microwave sources. The effects of exposure to high-peak-power radiation on reflexive responding and motor function in Fischer 344/N rats were assessed by measuring startle and general activity, and disruption of on-going performance of a rotarod task, respectively. The emitter used was the TEMPO repeat pulse axially extracted vircator. Exposure to single pulses resulted in significant startle responses. Exposure to 1 pps for 10 s produced significant alterations in baseline activity and marked disruption of ...

Energy Technology Data Exchange (ETDEWEB)

Promoting the exchange of information related to implementation of the As Low as Reasonably Achievable (ALARA) philosophy is a continuing objective for the Department of Energy (DOE). This report was prepared by the Brookhaven National Laboratory (BNL) ALARA Center for the DOE Office of Health. It contains the fifth in a series of bibliographies on dose reduction at DOE facilities. The BNL ALARA Center was originally established in 1983 under the sponsorship of the Nuclear Regulatory Commission to monitor dose-reduction research and ALARA activities at nuclear power plants. This effort was expanded in 1988 by the DOE`s Office of Environment, Safety and Health, to include DOE nuclear facilities. This bibliography contains abstracts relating to various aspects of ALARA program implementation and dose-reduction activities, with a specific focus on DOE facilities. Abstracts included in this bibliography were selected from proceedings of technical meetings, journals, research reports, ...

Science.gov (United States)

In 2002 and again in 2003, an investigative journalist unit at ABC News transported a 6.8 kilogram metallic slug of depleted uranium (DU) via shipping container from Istanbul, Turkey to Brooklyn, NY and from Jakarta, Indonesia to Long Beach, CA. Targeted inspection of these shipping containers by Department of Homeland Security (DHS) personnel, included the use of gamma-ray imaging, portal monitors and hand-held radiation detectors, did not uncover the hidden DU. Monte Carlo analysis of the gamma-ray intensity and spectrum of a DU slug and one consisting of highly-enriched uranium (HEU) showed that DU was a proper surrogate for testing the ability of DHS to detect the illicit transport of HEU. Our analysis using MCNP-5 illustrated the ease of fully shielding an HEU sample to avoid detection. The assembly of an Improvised Nuclear Device (IND) -- a crude atomic bomb -- from sub-critical pieces of HEU metal was then examined via Monte Carlo ...

Energy Technology Data Exchange (ETDEWEB)

It is anticipated that early in the next century manned missions into outer space will occur, with a mission to Mars scheduled between 2015 and 2020. However, before such missions can be undertaken, a realistic estimation of the potential risks to the flight crews is required. One of the uncertainties remaining in this risk estimation is that posed by the effects of exposure to the radiation environment of outer space. Although the composition of this environment is fairly well understood, the biological effects arising from exposure to it are not. The reasons for this are three-fold: (1) A small but highly significant component of the radiation spectrum in outer space consists of highly charged, high energy (HZE) particles which are not routinely experienced on earth, and for which there are insufficient data on biological effects; (2) Most studies on the biological effects of radiation to date have ...

International Nuclear Information System (INIS)

... organizations irradiation radiation doses radiation effects RADIATIONS.

International Nuclear Information System (INIS)

... halogenation ionizing radiations kinetics radiations reaction kinetics

British Library Electronic Table of Contents (United Kingdom)

The effects of thermal radiation and viscous dissipation on magneto-hydrodynamic (MHD) unsteady free-convection flow over a semi-infinite vertical porous plate are analysed. The fluid considered is non-gray (absorption coefficient dependent on wave length). The Network Simulation Method is used to solve the boundary-layer equations based on the finite-difference formulation; only discretization of the spatial co-ordinates is necessary, while time remains as a real continuous variable. This method provides a solution for both transient and steady-state problems at the same time, and programming does not require manipulation of the sophisticated mathematical software that is inherent in other numerical methods. The velocity, temperature, local skin-friction and local Nusselt number are studi...

International Nuclear Information System (INIS)

The development and occurrence of new electron accelerators and applications are according to the human society development law, as a whole. The period of economic standstill is generating an intense creative activity in the domain of science and engineering which also resulting in great achievements in the field of electron accelerators. This paper presents the basic principle of the electron beam applications and the accelerators required characteristics for their present and potential applications in the domains: radiation sources, diagnostics, radiation processing, energetics, environment, defense and basic sciences. All these are correlated to the new generation of accelerators which, for the acceleration process, may employ electromagnetic fields generated by standard sources, atomic lasers, free electron lasers, Cerenkov effect, Smith - Purcell effect, electron beams, plasma, excited atoms into a crystal or other ...

Energy Technology Data Exchange (ETDEWEB)

The project is focusing on the formation and growth mechanisms of atmospheric aerosol and cloud droplets. Both aerosol particles and cloud droplets affect strongly on the atmospheric radiation fluxes by scattering and absorption. The droplet formation results from physical and chemical processes occurring simultaneously. The studies concerning the tropospheric cloud droplet formation, laboratory experiments with a cloud chamber and stratospheric cloud formation are summarized. The recent studies summarized in this presentation indicate that both aerosol particles and cloud droplets have a significant role in climatic change and ozone depletion problems. The anthropogenic emissions of gaseous and particulate pollutants change the properties of atmospheric aerosols and cloud droplets. The research in this field will be continued and more quantitative understanding based both experimental and theoretical studies is required

British Library Electronic Table of Contents (United Kingdom)

An evaporative cooling system developed for operation and qualification testing of silicon pixel and microstrip detectors for the inner tracking detector of the CERN ATLAS spectrometer is described. Silicon detector substrates must be continuously operated between 0 and ???7?C in the high radiation environment near the circulating beams at the CERN Large Hadron Collider (LHC). This requirement imposes unusual constraints on the cooling system and has led to the choice of perfluoro-n-propane (C3F8) refrigerant, which combines good chemical stability under ionizing radiation with high dielectric strength and nonflammability. Since the silicon detectors must also be of extremely light construction to minimize undesirable physics background, coolant tubes are of thin (200 ?m) aluminum wall, wh...

Energy Technology Data Exchange (ETDEWEB)

A strategy for the management of the disposal of low-level radioactive wastes into coastal zones and ocean waters has developed over the past three decades. While there has been a substantial increase in the number of international and required agreements there has also been a concomitant improvement in our understanding of the ocean and the processes at work within it. This has allowed more rigorous and reliable assessments to be made of the radiological consequences. With the continued development of basic guidelines of radiological protection by the International Commission on Radiological Protection (ICRP) methodologies have been formulated to derive the fundamental scientific requirement - the relationship between disposal or release rate to the ocean and the resultant radiation dose to exposed human populations.

International Nuclear Information System (INIS)

The suggestion has often been made that an additional radiation exposure imposed on humanity as a result of some important activity such as electricity generation would be acceptable if the exposure was 'small' compared to the natural background. In order to make this concept quantitative and objective, we propose that 'small compared with the natural background' be interpreted as the standard deviation (weighted with the exposed population) of the natural background. We believe that this use of the variation in natural background radiation is less arbitrary and requires fewer unfounded assumptions than some current approaches to standard-setting. The standard deviation is an easily calculated statistic that is small compared with the mean value for natural exposures of populations. It is an objectively determined quantity and its significance is generally understood. Its determination does not omit any of the pertinent ...

International Nuclear Information System (INIS)

The production of radiopharmaceuticals used in positron emission tomography (PET) can require large amounts of activity at the start of synthesis in order to yield sufficient labeled material for clinical studies. Several investigators have developed remote and automated systems for the routine production of PET radiopharmaceuticals in order to reduce radiation exposure to personnel. Such devices, however, suffer from limited flexibility and can be relatively complicated in design. These systems are also limited to the production of a single or a few closely related compounds. Furthermore, changes in chemistry would require considerable modifications in hardware and/or software in order to bring the device back into operation. To circumvent the above limitations associated with the remote production of PET radiopharmaceuticals, the authors have investigated the use of laboratory robotics as a flexible alternative to the ...

Energy Technology Data Exchange (ETDEWEB)

Laser applications have proliferated in recent years and, as to be expected, their presence is no longer confined to the laboratory or places where access to their radiation can be easily controlled. One obvious application where this is so is in military operations where various devices such as laser range finders, target designators, and secure communications equipment elevate the risk of exposure, specifically eye exposure, to unacceptable levels. Although the need for eye protection in the laboratory and other controlled areas has been appreciated since the invention of the laser, the use of lasers in circumstances where safety or the risk of temporary loss of vision, which can not always be ensured by administrative procedures, has made adequate eye protection essential. It is the critical nature of many military operations that has driven the search for eye protection against both nuclear and laser radiation. At the same time, the ...

International Nuclear Information System (INIS)

Initial clinical experience in gastrointestinal radiography using Fuji Computed Radiography(FCR) system was reported. Image quality of conventional film/screen radiography and FCR system on upper GI series and barium enema was compared. Reflecting wide dynamic range of the system, improved image quality was confirmed, particularity in visibility of fine mucosal pattern(area gastricae), folds and overall contour. High sensor sensitivity of the system could reduce radiation dose requirement significantly. Diagnostically acceptable images were obtained with approximately 1/5 of routine dose for conventional radiography except in cases of lateral view of the rectum. (author).

Energy Technology Data Exchange (ETDEWEB)

The role of robotics and remote handling equipment in future nuclear power plant maintenance activities is discussed in the context of artificial intelligence applications. Special requirements manipulators, control systems, and man-machine interfaces for nuclear applications are noted. Tasks might include inspection with cameras, eddy current probes, and leak detectors; the collection of material samples; radiation monitoring; and the disassembly, repair and reassembly of a variety of system components. A robot with vision and force sensing and an intelligent control system that can access a knowledge base is schematically described. Recent advances in image interpretation systems are also discussed.

Energy Technology Data Exchange (ETDEWEB)

A gamma-ray spectrometer (GRS) has been built and delivered to the Mercury MESSENGER spacecraft which launched on August 3, 2004, from Cape Canaveral, Florida. The GRS, a part of seven scientific instruments on board MESSENGER, is based on a coaxial high-purity germanium detector. Gamma-ray detectors based on germanium have the advantage of providing excellent energy resolution, which is critical to achieving the science goals of the mission. However, germanium has the disadvantage that it must operate at cryogenic temperatures (typically {approx}80 K). This requirement is easy to satisfy in the laboratory but difficult near Mercury, which has an extremely hot thermal radiation environment. To cool the detector, a Stirling cycle mechanical cooler is employed. In addition, radiation and conduction techniques a are used to reduce the GRS heat load. Before delivering the flight sensor, a complete thermal prototype was built ...

Energy Technology Data Exchange (ETDEWEB)

A multi-stage, multi-disk type seismic source was developed as a downhole seismic source. The seismic source is an improved version of the downhole seismic source of a system in which an elastic wave is generated by a weight accelerated by restitutive force of a spring striking the upper part of a laminated structure consisted of metal disks and elastic bodies installed in water in a well. Enhancing the vibration exciting efficiency requires impedance radiated from the disks to be increased. The multi-disk structure was adopted because of restrictions on the disk area under the limiting condition of being inside the well. Further limitation has still existed, which led to finally structuring the multi-disk type to a multi-stage construction to increase the radiated impedance. In order to increase average velocity on the radiation surface, mass relationship between the hammer and the anvil was sought so ...

International Nuclear Information System (INIS)

Else of solar energy as substitute for conventional fuels at a competitive cost requires efficient conversion from solar radiation to usable forms of energy. In solar thermal or thermochemical applications, high efficiency usually re- quires high temperature and high concentration of incoming radiation. The main form of energy loss from high temperature solar central receivers is thermal emission ('re radiation'), at an effective temperature close to the maximum receiver temperature. This loss is reduced if the aperture is divided into segments, most of which are maintained at lower temperatures. A two-stage partitioned receiver demonstrating this concept is under construction at the Weizman Solar Tower. The high-temperature stage is the DIAPR (Directly Irradiated Annular Pressurized Receiver). The low-temperature stage is made of tubular cavity receivers of simpler design. Preliminary optical and ...

Energy Technology Data Exchange (ETDEWEB)

No abstract prepared.

International Science & Technology Center (ISTC)

Development of New Resource-Saving Technologies for Ceramic Material Production: High resistant Pigments, Heat Shielding, Plasters, Filters, etc.; by the Method of Controllable Thermosynthesis in Combustion Wave Using Industrial Metal-Containing Wastes

International Nuclear Information System (INIS)

Complete calculations of the accelerator related background in the muon spectrometer of the CMS detector at the Large Hadron Collider are presented. The simulations have been performed with the STRUCT multi-turn tracking code and the MARS and FLUKA cascade codes taking into account latest information of the LHC lattice, vacuum conditions, beam cleaning system and the shielding and layout of the CMS experiment. Beam loss distributions in the interaction regions and their vicinities and their contribution to the background levels in the muon spectrometer of CMS are analyzed. The studies show that hadronic and electromagnetic components of machine background are efficiently suppressed by the proposed CMS shielding. High energy muons penetrate through the shielding, but in positions of significance they do not contribute more than a few percent compared to the background generated by the pp-collisions. It is anticipated that ...

International Nuclear Information System (INIS)

IRAN.LIB is a Coupled Neutron-Gamma library which was developed to be used by the ANISN/PC (ccc-0514/02). The library was developed mainly for shielding calculations and it contains 33 elements mostly used as shielding materials, such as concrete. IRAN.LIB is a set of six libraries, each having the same elements but different number of energy groups. In order to use IRAN.LIB by ANISN/PC, this code must be modified. (author).

CERN Document Server

Increasing the speed and complexity of semiconductor integrated circuits requires advanced processes that put extreme constraints on the level of metal contamination allowed on the surfaces of silicon wafers. Such contamination degrades the performance of the ultrathin SiO sub 2 gate dielectrics that form the heart of the individual transistors. Ultimately, reliability and yield are reduced to levels that must be improved before new processes can be put into production. It should be noted that much of this metal contamination occurs during the wet chemical etching and rinsing steps required for the manufacture of integrated circuits and industry is actively developing new processes that have already brought the metal contamination to levels beyond the measurement capabilities of conventional analytical techniques. The measurement of these extremely low contamination levels has required the use of synchrotron ...

International Nuclear Information System (INIS)

Apoptosis, or programmed cell death (PCD), is a fundamental process that protects organismal integrity. In earlier work, we demonstrated that over-expression of either of two anti-apoptotic members of the BCL-2 family (BCL-2 or BCL-X L could elevate the frequency of radiation-induced mutations at the autosomal TK1 locus in human TK6 lymphoblasts that express wild-type TP53. Ectopic expression of BCL-X L also elevated the frequencies of double-strand break-induced gene conversion. The purpose of this study is to determine if BCL-2 family proteins promote radiation mutagenesis indirectly through their suppression of PCD, or whether the 'pro-mutagenic' function of these proteins can be separated from their anti-apoptotic function. We developed stable transfectants of TK6 cells that express a mutated form of BCL-X L with a single amino acid substitution in the BH1 domain that is known to interfere with the ability to suppress PCD (BCL-X L ...

International Nuclear Information System (INIS)

Full text: Korea Atomic Energy Research Institute (KAERI) has many R and D facilities in operation. including HANARO research reactor, radioactive waste treatment facility (RWTF), post-irradiation examination facility (PIEF) and irradiated material test facility (IMEF). Recently. nation-wide interest is focused on the safety and security of major industrial facilities. Safe operation of nuclear facilities is imperative because of the consequence of public disaster by radiological release/contamination, in case of an accident. Recently, Ministry of Science and Technology (MOST) of the Korean government announced amendments of Atomic Energy laws to enforce requirements of the physical protection and radiological emergency. All provisions on nuclear safety regulation and radiation protection are entrusted to the Atomic Energy Act(AEA). The Act is enacted as the main law concerning the safety regulation of nuclear installations, and is supplemented ...

Energy Technology Data Exchange (ETDEWEB)

Two mechanical design requirements are defined for the SSC Collider beam tube. First, the vacuum requirement (luminosity lifetime = 150 hrs). It requires the design of a pressure boundary within the cold mass vessel to provide a vacuum tunnel for the proton beam and to minimize the synchrotron radiation gas desorbtion with a suitable material. The Collider beam tube design is under an intensive activity to search for a material that will meet the luminosity requirement without a distributed pump or liner. Second is the tube wall's resistivity requirement ([sigma]*t = 2E5 [Omega][sup [minus]1]). For a 4.2 K beam tube the Cu thickness is 100 [mu]m (RRR=30,6.7 T, [sigma]=2E9[Omega][sup [minus]1]m[sup [minus]1]). The copper yield strength is relatively low in comparison to steel and, therefore, the design of the steel layer is governed by the copper layer ...

UK PubMed Central (United Kingdom)

Abstract The authors provide a survey of how images are used in radiation therapy to improve the precision of radiation therapy plans, and delivery of radiation treatment. In contrast...Full Text Available

Environmental Research Database

No further description is available

International Nuclear Information System (INIS)

Full text: Radiotherapy treatment planning (RTP) relies heavily on medical imaging. Until recently, the most important planning tool was the treatment simulator. The kilovoltage radiographic capabilities in a treatment simulator enabled the boundaries of treatment fields to be visualized with respect to bony anatomic landmarks. Perhaps the most important advance in treatment planning in recent years is the ability to visualize the passage of the beams with respect to a more accurate geometrical representation of the tumor and other soft tissue structures. This 'virtual simulation' uses a computer-based representation of a patient to determine the extent of the disease and the location of radiation sensitive normal tissue. Computer tomographic (CT) imaging produces a high-resolution three-dimensional representation of anatomy that can be correlated with other image sets such as magnetic resonance images (MRI) of function. Positron emission tomographic (PET) imaging ...

International Nuclear Information System (INIS)

Purpose: To determine if involved field radiation (IF) is equivalent to standard whole bone radiation (SF) in local tumor control; to establish patterns of failure following treatment; and to determine response, event-free survival (EFS), and overall survival rates from multidisciplinary therapy in Ewing's sarcoma. Methods and Materials: Between 1983 and 1988, 184 children with Ewing's sarcoma were enrolled onto Pediatric Oncology Group 8346 (POG 8346). A total of 178 (97%) met eligibility criteria; 6 had pathology other than Ewing's sarcoma. Induction chemotherapy of cyclophosphamide/doxorubicin (adriamycin )(C/A) x 12 weeks was followed by local treatment either surgery or radiation therapy and C/A, dactinomycin, and vincristine for 50 weeks. Resection was advised for patients with small primary tumors if accomplished without functional loss. Forty patients were randomized to receive SF, whole bone ...

Energy Technology Data Exchange (ETDEWEB)

Investigated here were the effects of microwave (MW) radiation (2450-MHz, continuous-wave, mean specific absorption rate of 103.5 + or - 4.2 W/kg) and convention heating on the nonphosphorylating oxidative metabolism of human peripheral mononuclear leukocytes (96% lymphocytes, 4% monocytes) at 37 C. Metabolic activity, determined by chemiluminescence (CL) of cells challenged with luminol (5-aminO-2, 3-dihydro-1, 4-phthalazinedione) linked to bovine serum albumin, was detected with a brightness photomer. A significant stimulation after after MW exposure (p < 0.005) over total CL of matched 37 C-incubator controls was observed. A similar degree of stimulation, compared to incubator controls, was also detected after sham treatment. No significant difference existed between changes in total CL or stimulation indices of the MW and sham-exposed groups. Exposure to MW radiation, under normothermic (37 + or - 0.03 C) conditions, appears to have no ...

CERN Document Server

Radiation protection and the management of radioactive waste in the oil and gas industry

International Nuclear Information System (INIS)

The case of spontaneous radiation of channeled ultrarelativistic particles is considered when the dipolarity condition is not satisfied. The change of the particle longitudinal velocity affecting the maximum radiation frequency is included. The angular and frequency characteristics of the radiation for superhigh energies are studied for the first time. It is shown that there is an optimum energy at which the radiation density is maximum. The influence of the angle at which electrons enter a crystal and of the beam divergence on the radiation is investigated. The problem of quasichanneled particle radiation and also the radiation in axis-plane transitions are considered. (author).

International Nuclear Information System (INIS)

... odd nuclei organic compounds radiation effects radioisotopes synthesis

International Nuclear Information System (INIS)

... compounds plants radiation effects radioisotopes reaction kinetics trees

Science.gov (United States)

duced and spontaneous radiation. The amount of polarization is ... of the induced and spontaneous radiation patterns. Therefore ...

International Nuclear Information System (INIS)

Despite its great usefulness in the performance of the recording procedures prescribed by the X-Ray Ordinance the dose-area product is much less frequently measured for X-ray exposures than during fluorscopic examinations. The great multitude of measuring units, mainly on account of different scales of the measuring equipments themselves, is a cause of uncertainty in clinical routine and should be eliminated as far as the circumstances would permit. As the determination of the organ dose is relevant only in very few cases and does not necessarily require previous measurements of the dose-area product, these are of limited practical value in the assessment of individual radiation exposures during radiographic examinations. The measurements may, however, be very helpful in determinations of the radiation dose to the total population, if the future retrievability of the values obtained is ensured. In addition to some measuring ...

International Nuclear Information System (INIS)

The fundamental recommendations of the ICRP issued in its publication of 1990 stipulate the general principle of performance of dose measurements at regular intervals in the field of diagnostic radiology, for the purpose of equipment performance checking and optimization of radiological protection. In response to this requirement, the Federal Ministry, in cooperation with experts and the competent supervising authorities, has issued an order to install dose-area-product meters in angiographic examination systems, imaging systems and fluoroscopic screen devices primarily used for examining infants and children up to the age of 12. This is done in response to reported cases of adverse effects of radiation exposure and the high priority given to radiological protection in the examination of infants and children. In 1992, an expert group was convened to discuss and elaborate instructions for including dose-area product measurement in the dosimetry ...

Energy Technology Data Exchange (ETDEWEB)

A new double-null, slotted divertor configuration will be installed for the DIII-D Radiative Divertor Program at General Atomics in late 1996. Four cryocondensation pumps, three new and one existing, will be part of this new divertor. The purpose of the pumps is to provide plasma density control and to limit the impurities entering the plasma core by providing pumping at each divertor strike point. The three new pumps are based on the design of the existing pump, installed in 1992 as part of the Advanced Divertor Program. The pump continues to operate successfully. The new pumps require geometry modifications to the original design. Therefore, extensive modal and dynamic analyses were performed to determine the behavior of these pumps and their helium and nitrogen feed lines during disruption events. Thermal and fluid analyses were also performed to characterize the helium two-phase flow regime in the pumps and their feedlines. A flow testing ...

International Nuclear Information System (INIS)

A new double-null, slotted divertor configuration will be installed for the DIII-D Radiative Divertor Program at General Atomics in late 1996. Four cryocondensation pumps, three new and one existing, will be part of this new divertor. The purpose of the pumps is to provide plasma density control and to limit the impurities entering the plasma core by providing pumping at each divertor strike point. The three new pumps are based on the design of the existing pump, installed in 1992 as part of the Advanced Divertor Program. The pump continues to operate successfully. The new pumps require geometry modifications to the original design. Therefore, extensive modal and dynamic analyses were performed to determine the behavior of these pumps and their helium and nitrogen feed lines during disruption events. Thermal and fluid analyses were also performed to characterize the helium two-phase flow regime in the pumps and their feedlines. A flow testing ...

International Nuclear Information System (INIS)

Core-collapse supernovae are among Nature's most energetic events. They mark the end of massive star evolution and pollute the interstellar medium with the life-enabling ashes of thermonuclear burning. Despite their importance for the evolution of galaxies and life in the universe, the details of the core-collapse supernova explosion mechanism remain in the dark and pose a daunting computational challenge. We outline the multi-dimensional, multi-scale, and multi-physics nature of the core-collapse supernova problem and discuss computational strategies and requirements for its solution. Specifically, we highlight the axisymmetric (2D) radiation-MHD code VULCAN/2D and present results obtained from the first full-2D angle-dependent neutrino radiation-hydrodynamics simulations of the post-core-bounce supernova evolution. We then go on to discuss the new code Zelmani which is based on the open-source HPC Cactus framework and ...

Energy Technology Data Exchange (ETDEWEB)

Systematics of neutron capture radiative width were studied in the target element range from Th to Cm. Reduced radiative widths were analyzed with a simple radiative width formula based on E1 transition. Average radiative width is presented with the standard deviation of 15%. (author)

International Nuclear Information System (INIS)

During the normal operation of a Nuclear Power Plant (NPP), radioactive releases into the atmosphere will be in small quantities. During major accidental situations, though the probability is extremely small, there may be significant release of radioactivity to the environment through the stack or at ground level. To study the external radiation exposure, if any, to the members of public due to releases during the normal operation of a nuclear power plant (NPP) and also to meet the requirement of emergency preparedness for the NPP site, continuous recording and analysis of environmental dose rate data is essential. This paper presents analysis of the gamma dose rates recorded by the Environmental Dose Logging Systems (EDLS) installed around the site during the last six years in the Emergency Planning Zone (EPZ) of Tarapur Atomic Power Station (TAPS). (author)

Energy Technology Data Exchange (ETDEWEB)

This study presents results from Monte Carlo radiation transport calculations aimed at characterizing a novel methodology being developed to detect partial defects in Pressurized Water Reactor (PWR) spent fuel assemblies (SFAs). The methodology uses a combination of measured neutron and gamma fields inside a spent fuel assembly in an in-situ condition where no movement of the fuel assembly is required. Previous studies performed on single isolated assemblies resulted in a unique base signature that would change when some of the fuel in the assembly is replaced with dummy fuel. These studies indicate that this signature is still valid in the in-situ condition enhancing the prospect of building a practical tool, Partial Defect Detector (PDET), which can be used in the field for partial defect detection.

Energy Technology Data Exchange (ETDEWEB)

In a fluoroscopic imaging system, image quality and patient dose are both affected by the optical system linking the image intensifier with the video camera. The effect on patient exposure of increasing the optical iris aperture size over that required for other procedures performed on the same imaging system was investigated for the air-contrast barium enema examination. Using a large-area transmission ionisation chamber to monitor the Roentgen-area-product of entrance exposure, a decrease in fluoroscopic radiation of greater than 50% was clinically documented for a fluoroscopic system utilising kVp and mA variable automatic brightness control. For this iris change, the video image was of acceptable quality for positioning and monitoring the patient, and no deleterious effect was detected in the conduct of the air-contrast exam. The availability of a variable-sized operator-selectable iris diaphragm would permit this dose-reduction approach to ...

Energy Technology Data Exchange (ETDEWEB)

Before disposing of transuranic radioactive wastes in the Waste Isolation Pilot Plant (WIPP), the United States Department of Energy (DOE) must evaluate compliance with applicable long-term regulations of the United States Environmental Protection Agency (EPA). Sandia National Laboratories is conducting iterative performance assessments of the WIPP for the DOE to provide interim guidance while preparing for final compliance evaluations. This volume contains an overview of WIPP performance assessment and a preliminary comparison with the long-term requirements of the Environmental Radiation Protection Standards for Management and Disposal of Spent Nuclear Fuel, High-Level and Transuranic Radioactive Wastes (40 CFR 191, Subpart B).

CERN Document Server

While radiation-pressure cooling is well known, the Brillouin scattering of light from sound is considered an acousto-optical amplification-only process. It was suggested that cooling could be possible in multi-resonance Brillouin systems when phonons experience lower damping than light. However, this regime was not accessible in traditional Brillouin systems since backscattering enforces high acoustical frequencies associated with high mechanical damping. Recently, forward Brillouin scattering in microcavities has allowed access to low-frequency acoustical modes where mechanical dissipation is lower than optical dissipation, in accordance with the requirements for cooling. Here we experimentally demonstrate cooling via such a forward Brillouin process in a microresonator. We show two regimes of operation for the Brillouin process: acoustical amplification as is traditional, but also for the first time, a Brillouin cooling regime. Cooling is ...

Energy Technology Data Exchange (ETDEWEB)

The primary responsibility of the Health, Safety, and Environment (HSE) Division at the Los Alamos National Laboratory is to provide comprehensive occupational health and safety programs, waste processing, and environment protection. These activities are designed to protect the worker, the public, and the environment. Many disciplines are required to meet the responsibilities, including radiation protection, industrial hygiene, safety, occupational medicine, environmental science, epidemiology, and waste management. New and challenging health and safety problems arise occasionally from the diverse research and development work of the Laboratory. Research programs in HSE Division often stem from these applied needs. These programs continue but are also extended, as needed to study specific problems for the Department of Energy and to help develop better occupational health and safety practices.

Energy Technology Data Exchange (ETDEWEB)

Algorithms for the authentication of byte sequences are described. The algorithms are designed to authenticate data in the Storage, Retrieval, Analysis, and Display (SRAD) Test Data Archive of the Radiation Effects and Testing Directorate (9100) at Sandia National Laboratories, and may be used in similar situations where authentication of stored data is required. The algorithms use a well-known error detection method called the Cyclic Redundancy Check (CRC). When a byte sequence is authenticated and stored, CRC bytes are generated and attached to the end of the sequence. When the authenticated data is retrieved, the authentication check consists of processing the entire sequence, including the CRC bytes, and checking for a remainder of zero. The error detection properties of the CRC are extensive and result in a reliable authentication of SRAD data.

Energy Technology Data Exchange (ETDEWEB)

The deliberation by the Nuclear Safety Commission was initiated on the alteration in reactor installation, as was required by the Ministry of International Trade and Industry. The alteration is the additional installation of the reactor No. 2 in the Sendai Nuclear Power Station, Kyushu Electric Power Co., Inc. It is a PWR power plant with thermal output of about 2,660 MW (electric output of 890 MW), to be installed, adjoining to the reactor No. 1 of the same type and capacity under construction. In the examination by MITI, it was confirmed that the technological capabilities for its construction and operation and the radiation protection measures in power generation are both sufficient. The contents of the examination include the siting conditions, the location and construction of reactor facilities, etc.

Energy Technology Data Exchange (ETDEWEB)

The requirements to design nuclear power plants for the effects of an instantaneous double-ended guillotine break (DEGB) of the reactor coolant piping have led to excessive design costs, interference with normal plant operation and maintenance, and unnecessary radiation exposure of plant maintenance personnel. This report describes an aspect of the NRC/Lawrence Livermore National laboratory-sponsored research program aimed at investigating whether the probability of DEGB in Reactor Coolant Loop Piping of nuclear power plants is acceptably small such that the requirements to design for the DEGB effects (e.g., provision of pipe whip restraints) may be removed. This study estimates the probability of indirect DEGB in Reactor Coolant piping as a consequence of seismic-induced structural failures within the containment of the GE supplied boiling water reactor at the Brunswick nuclear power plant. The median probability of ...

Energy Technology Data Exchange (ETDEWEB)

Since 1958, the AlliedSignal Federal Manufacturing and Technologies (FM and T) Metrology Department has developed measurement technology and calibration capability in four major areas of measurement: mechanical; environmental, gas, liquid; electrical (D.C., A.C., RF/microwave); and optical and radiation. The capabilities developed include unique capabilities in many areas of measurement and engineering expertise to develop measurement techniques and resolve measurement problems in these major areas. FM and T Metrology was established in 1958 to provide a measurement base for the Department of energy`s Kansas City Plant. The Metrology Engineering Department provides the expertise to develop measurement capabilities for virtually any type of measurement which falls into the broad areas listed above. The engineering staff currently averages almost 16 years of measurement experience. A strong audit function has been developed to provide a means to evaluate the ...

Energy Technology Data Exchange (ETDEWEB)

The Holifield Radioactive Ion Beam Facility (HRIBF) now under construction at the Oak Ridge National Laboratory will use the 25-MV tandem accelerator for the acceleration of radioactive ion beams to energies appropriate for research in nuclear physics; negative ion beams are, therefore, required for injection into the tandem accelerator. Because charge exchange is an efficient means for converting initially positive ion beams to negative ion beams, both positive and negative ion sources are viable options for use at the facility; the choice of the type of ion source will depend on the overall efficiency for generating the radioactive species of interest. A high-temperature version of the CERN-ISOLDE positive ion source has been selected and a modified version of the source designed and fabricated for initial use at the HRIBF because of its low emittance, relatively high ionization efficiencies and species versatility, and because it has been engineered for remote ...

International Nuclear Information System (INIS)

Displacements per atom (DPA) is a widely used damage unit for displacement damage in nuclear materials. Calculating the DPA for SiC irradiated in a particular facility requires a knowledge of the neutron spectrum as well as specific information about displacement damage in that material. In recent years significant improvements in displacement damage information for SiC have been generated, especially the energy required to displace an atom in an irradiation event and the models used to describe electronic and nuclear stopping. Using this information, numerical solutions for the displacement functions in SiC have been determined from coupled integro-differential equations for displacements in polyatomic materials and applied in calculations of spectral-averaged displacement cross sections for SiC. This procedure has been used to generate spectrally averaged displacement cross sections for SiC in a number of reactors used for ...

Energy Technology Data Exchange (ETDEWEB)

The present work addresses an off-axis Cassegrain optical concentration system. The specific primary collector analyzed, a short focal length parabolic concentrator, is at the University of Florida`s Energy Park. A secondary hyperbolic reflective element was designed to redirect the solar radiation from the primary focal plane to an off-axis target on the polar axis of the primary concentrator. This ground level target will be required for planned experimental work. The analysis was performed using a numerical ray tracing procedure that incorporates both random and systematic errors due to slope and surface irregularities. The optimization process varied secondary element size, curvature, and offset angle, and yielded information required for optimum design. As a single secondary element was found impractical, three elements were designed for use at various time of the year. The numerical analysis predicts that typically 70 ...

International Nuclear Information System (INIS)

Ammonia adsorption on the external surface of C_3_0B_1_5N_1_5 heterofullerene was studied using density functional calculations. Three models of the ammonia-attached C_3_0B_1_5N_1_5 together with the perfect model were optimized at the B3LYP/6-31G"* level. The optimization process reveals that dramatic influences occurred for the geometrical structure of C_3_0B_1_5N_1_5 after ammonia adsorption; the B atom relaxes outwardly and consequently the heterofullerene distorts from the spherical form in the adsorption sites. The chemical shielding (CS) tensors and nuclear quadrupole coupling constants of B and N nuclei were calculated at the B3LYP/6-311G"*"* level. Our calculations reveal that the B atom is chemically bonded to NH_3 molecule. The B atom in the NH_3-attached form has the largest chemical shielding isotropic (CSI) value among the other boron nuclei. The C_Q parameters of B nuclei at the interaction sites are significantly decreased after ...

International Nuclear Information System (INIS)

The mapping of the magnetic flux bundle from the center cell to the Plasma Potential Control plates (PPC) on the end fan of the Tandem Mirror Experiment Upgrade (TMX-U), was improved by the addition of trim coils (12,000 amp-turns) on each side of each end fan next to the pump beam magnetic shields. The coils' axes are oriented perpendicular to the machine centerline. These coils made the necessary corrections to the field-line mapping, while keeping the field in the nearby pump beam magnetic shield below the saturation threshold. This paper briefly describes the problem, discusses the design as it evolved, and presents the results of the field testing. A brief description of the improvement in the machine performance is also included.

International Nuclear Information System (INIS)

One of the major concerns during high speed welding of magnesium alloys is the presence of porosity in the weld metal that can deteriorate mechanical properties. This study seeks to analyze the presence method and quantity of pore during hybrid laser-tungsten inert gas arc (TIG) welding of magnesium alloy AZ31B by radiography, optical microscopy and electron probe microanalysis (EMPA). At the same time, it identifies both the mechanism of pore formation and a remedy for this problem. The experimental results indicate that lacking of shielding gas for laser beam is the dominant cause of macroporosity formation during the hybrid of laser-TIG welding of magnesium Alloys AZ31B plate, and hydrogen is not main cause to form large pores. A favorable weld without porosity can be obtained by appending lateral shielding gas for laser beam.

Science.gov (United States)

A series of experiments is to be made during the acceptance test program of the Fast Flux Test Facility (FFTF) to measure the gamma ray characteristics of the Fast Test Reactor (FTR) and to establish the performance characteristics of the reactor shield. These measurements are a part of the FFTF Reactor Characterization Program (RCP). Detailed plans have been developed for these experiments. During the initial phase of the Characteristics Program, which will be carried out in the In-Reactor Thimble (IRT), both active and passive measurement methods will be employed to obtain as much information concerning the gamma ray environment as is practical. More limited active gamma ray measurements also will be made in the Vibration Open Test Assembly (VOTA).

Energy Technology Data Exchange (ETDEWEB)

A detector head for in situ inspection of irradiated nuclear fuel assemblies submerged in a water-filled nuclear fuel storage pond. The detector head includes two parallel arms which extend from a housing and which are spaced apart so as to be positionable on opposite sides of a submerged fuel assembly. Each arm includes an ionization chamber and two fission chambers. One fission chamber in each arm is enclosed in a cadmium shield and the other fission chamber is unshielded. The ratio of the outputs of the shielded and unshielded fission chambers is used to determine the boron content of the pond water. Correcting for the boron content, the neutron flux and gamma ray intensity are then used to verify the declared exposure, cooling time and fissile material content of the irradiated fuel assembly.

International Nuclear Information System (INIS)

To develop a work in an area with high radiation, it requires of a detailed knowledge of the surroundings work, a communication and effective vision, a near dosimetric control. In a work where the spaces variables and reduced accesses exist, noise that hinders the communication, defendant operative condition, radiation field and taking of decision, it is necessary to have tools that allow a total control of the environment to make opportune and effective decisions, there where the task is developed. Under this elementary concept, it was developed in the Laguna Verde Central a project that it allowed a mechanism, interactive of control in spaces complex; to see, to hear, to speak, to measure. This concept takes to the creation of an equipped system with closed circuit of television, wireless communication systems, tele dosimetry wireless systems, VHS and DVD recording equipment, uninterrupted energy units. The system ...

International Nuclear Information System (INIS)

During Phase 2 of our study of the CIXS conceptual design we have tackled additional important issues that are unique to the ITER environment. These include the thermal control of the crystal and detector enclosures located in an environment with a 100-250 C ambient temperature, tritium containment, and the range of crystal and detector movement based on the need for spectral adjustments and the desire to make measurements of colder plasmas. In addressing these issues we have selected a ''Dewar''-type enclosure for the crystals and detectors. Applying realistic view factors for radiant heat and making allowance for conduction we have made engineering studies of this enclosure and showed that the cooling requirements can be solved and the temperature can be kept sufficiently constant without compromising the specification parameters of the CIXS. We have chosen a minimum 3 mm combined thickness of the six beryllium windows needed in a Dewar-type enclosure and showed ...

International Nuclear Information System (INIS)

Portuguese Sep-Oct 1996 p. 571 Brazil Campos, Patricia Sao Paulo

Science.gov (United States)

The principles of radionuclide excitation of X-ray fluorescence radiation and its application in

International Nuclear Information System (INIS)

This book gives an overview of the entire field of radiation protection with the subject areas radioactivity, X-rays, UV radiation, laser beams and high-frequency electromagnetic fields. It deals graphically with the most important physical notions, the incidence, origin, properties and biological effects of types of radiation, administrative and practical protection measures and the code of rules governing them. Apart from fundamentals of radiation protection the emphasis on the following: natural radiation exposure, radiation exposure to radon, disaster relief plans in the environment of nuclear plant, the precautionary radiation protection system evolved after Chernobyl, radiation exposure through UV radiation devices, radio, RF communication, radar, microwave ovens and high-voltage transmission ...

Energy Technology Data Exchange (ETDEWEB)

The spectral characteristics of the Cherenkov radiation have been evaluated and converted to equivalent retinal irradiance from external sources. On the basis of the conversion, electron fluxes have been estimated for 2-sec recovery times from flashblindness. The electrons are assumed to have energies greater than 6 MeV and to be delivered in one or more bursts of 1 microsecond each over 1 sec. It is important to note that very little data exists on recovery times as short as 2 sec for either photopic and scotopic conditions. This situation is a direct result of the lack of definition of the critical tasks and their sensitivity to an interruption of background adaptation. The Cherenkov radiation produced within the eye by relativistic electrons can be compared to light from external sources by the relationships: 1 rad approx. = 4.6 scotopic td-sec and 1 rad approx. = 0.55 photopic td sec. Based on these conversion factors, the following ...

Energy Technology Data Exchange (ETDEWEB)

Commercial focused ion beam (FIB) systems are commonly used to image integrated circuits (ICS) after device processing, especially in failure analysis applications. FIB systems are also often employed to repair faults in metal lines for otherwise functioning ICS, and are being evaluated for applications in film deposition and nanofabrication. A problem that is often seen in FIB imaging and repair is that ICS can be damaged during the exposure process. This can result in degraded response or out-right circuit failure. Because FIB processes typically require the surface of an IC to be exposed to an intense beam of 30--50 keV Ga{sup +} ions, both charging and secondary radiation damage are potential concerns. In previous studies, both types of effects have been suggested as possible causes of device degradation, depending on the type of device examined and/or the bias conditions. Understanding the causes of this damage is important for ICS that ...

International Nuclear Information System (INIS)

The purpose of the current study was to evaluate the difference in prognostic factors between stage IB and II uterine cervical carcinoma patients treated with postoperative radiation therapy. Between May 1988 and May 1998, a total of 94 patients including 47 patients with stage IB and 47 patients with stage II uterine cervical carcinoma were treated with postoperative radiation therapy at Tokyo Metropolitan Komagome Hospital. All patients were treated with 10 MV X-rays using an anterior-posterior parallel opposed field which covered the whole pelvis. Fractionation was 2 Gy per day, five fractions per week, to a total dose of 50 Gy. The 5-year overall survival rates of stage IB and II were 89.4% and 79.3%, respectively. In multivariate analysis for all patients, lymph node status, histology, and surgical margin status were recognized as prognostic factors. Limited to stage IB patients, lymph node status was the only independent prognostic ...

International Nuclear Information System (INIS)

Little clinical evidence has been provided to show the minimization of radiation resistance of tumors using high linear energy transfer radiation. We therefore investigated the radiobiological and molecular pathological aspects of carbon beam therapy. A total of 27 patients with squamous cell carcinoma (SCC) of the cervix were treated using a carbon beam and 50 control patients with SCC of the cervix using a photon beam. The expression of Ki-67, p53, and p27 proteins before radiotherapy and 5 and 15 days after therapy initiation were investigated using immunohistochemistry. Similar changes were observed in Ki-67 labeling index (LI) and p53 LI during carbon and photon beam therapies. However, for carbon beam therapy, the mean p27 LI significantly decreased from 25.2% before treatment to 18.6% on the 5th day after treatment initiation, followed by a significant increase to 36.1% on the 15th day. In contrast, for photon beam therapy, the p27 LI ...

Energy Technology Data Exchange (ETDEWEB)

Emerging high-power microwave technologies require that bioeffects of exposure to this type of radiation be investigated for health and safety considerations. Disruption of animal behavior is reported to be a sensitive indicator of microwave exposure. Three behavioral tasks were chosen for this initial investigation of exposure to U.S. Air Force high-power microwave emitters. The tasks were: (1) single-trail avoidance, (2) water satiation, and (3) rotarod performance. Exposure to high-power microwave radiation from the USAFSAM peak-power simulator significantly affected the single-trail avoidance task. Neither the single-trail avoidance task nor rotarod performance was affected by the Gypsy emitter. However, animals exposed to 9-kW and 11-kW outputs from the USAFSAM emitter spent significantly less time imbibing water postexposure than sham-exposed animals. The most consistent finding in the animals exposed to the Gypsy ...