Energy Technology Data Exchange (ETDEWEB)

Depth dose distributions for protons in the energy range from 2 to 600 MeV have been calculated by Monte Carlo and analytical methods. The dependence on energy of Maximum Dose Equivalent (MDE), quality factor and isotropic factor recommended for practical use are presented. The problems connected with regulation of maximum permissible proton fluxes are discussed. (author).

International Nuclear Information System (INIS)

Techniques for reducing computation time in 3D photon dose calculations are addressed with specific emphasis given to the convolution/superposition approach. A single polyenergetic superposition model calculating absorbed dose per incident photon fluence (Gy cm"2) was developed in terms of TERMA and a total energy deposition kernel (a total point spread function). A novel approach was devised for reducing calculation time. The method, named the CF method, was based on the use of a conventional, fast model (here a modified power-law method was used) for the generation of 3D dose distributions on a fine dose matrix. Superposition calculations were carried out on a coarse matrix and calculation speed was increased simply by reducing the number of calculations. A ...

International Nuclear Information System (INIS)

The determination of the dose to organs from diagnostic x rays has become important because of reports of radiation injury to patients from fluoroscopically guided interventional procedures. We have modified a convolution/superposition-based treatment planning system to compute the dose distribution for kilovoltage beams. We computed lung doses using this system and compared them to those calculated using the CDI3 organ dose calculation program. We also computed average lung doses from a simulated radiofrequency ablation procedure and compared our results to published doses for a similar procedure. Doses calculated using this system were an average of 20% lower for AP beams and 7% higher for PA beams than those obtained using CDI3. The ratio of the average ...

British Library Electronic Table of Contents (United Kingdom)

We performed experimental studies on the convolution/superposition method reported in the former companion paper (Iwasaki in Radiol Phys Technol 4, 2011) using 10-MV X-ray beams from open-jaw-collimated fields. The method uses primary and scatter dose kernels formed for energy bins of X-ray spectra reconstructed as a function of off-axis distance. We made a comparison of calculations and measurements in water phantoms and thorax-like phantoms with respect to percentage depth dose curves, tissue???phantom ratio curves, and dose profiles. We made the dose calculation by taking into account the beam-hardening effect with depth and the off-axis radiation-softening effect. We found that the method could be used, in general, for performing accurate dose calculations.

International Nuclear Information System (INIS)

The basic relationships of the convolution/superposition dose calculation technique are reviewed, and a modelling technique that can be used for obtaining a satisfactory beam model for a commercially available convolution/superposition-based treatment planning system is described. A fluence energy spectrum for a Co-60 treatment machine obtained from a Monte Carlo simulation was used for modelling the fluence spectrum for a Rokus M machine. In order to achieve this model we measured the depth dose distribution and the dose profiles with a Wellhofer dosimetry system. The primary fluence was iteratively modelled by comparing the computed depth dose curves and beam profiles with the depth dose curves and crossbeam profiles measured in a water phantom. The objective of beam modelling is to build a model of the primary fluence that the patient is ...

Energy Technology Data Exchange (ETDEWEB)

Collective dose equivalent and population dose from occupational exposures in Japan, 1988 were estimated on the basis of a nationwide survey. The survey was conducted on annual collective dose equivalents by sex, age group and type of radiation work for about 0.21 million workers except for the workers in nuclear power stations. The data on the workers in nuclear power stations were obtained from the official report of the Japan Nuclear Safety Commission. The total number of workers including nuclear power stations was estimated to be about 0.26 million. Radiation works were subdivided as follows: medical works including dental; non-atomic energy industry; research and education; atomic energy industry and nuclear power station. For the determination of effective dose equivalent and population dose, organ or tissue doses ...

International Nuclear Information System (INIS)

Convolution/superposition (C/S) is regarded as the standard dose calculation method in most modern radiotherapy treatment planning systems. Different implementations of C/S could result in significantly different dose distributions. This paper addresses two major implementation issues associated with collapsed cone C/S: one is how to utilize the tabulated kernels instead of analytical parametrizations and the other is how to deal with voxel size effects. Three methods that utilize the tabulated kernels are presented in this paper. These methods differ in the effective kernels used: the differential kernel (DK), the cumulative kernel (CK) or the cumulative-cumulative kernel (CCK). They result in slightly different computation times but significantly different voxel size effects. Both simulated and real multi-resolution dose calculations are presented. For simulation tests, we use ...

British Library Electronic Table of Contents (United Kingdom)

A convolution/superposition method is proposed for use with primary and scatter dose kernels formed for energy bins of X-ray spectra reconstructed as a function of off-axis distance. It should be noted that the number of energy bins is usually about ten, and that the reconstructed X-ray spectra can reasonably be applied to media with a wide range of effective Z numbers, ranging from water to lead. The study was carried out for 10-MV X-ray doses in water and thorax-like phantoms with the use of open-jaw-collimated fields. The dose calculations were made separately for primary, scatter, and electron contamination dose components, for which we used two extended radiation sources: one was on the X-ray target and the other on the flattening filter. To calculate the in-air beam intensities at po...

Energy Technology Data Exchange (ETDEWEB)

The US Department of Energy (DOE) sponsors an extensive research program to improve the methods, dosimeters, and instruments available to DOE facilities for measuring neutron dose and assessing its effects on the work force. The Total Dose Meter was recently developed for measuring in real time the adsorbed dose of mixed neutron and gamma radiation and for calculating the dose equivalent. The Field Neutron Spectrometer was developed to provide a portable instrument for determining neutron spectra in the workplace for flux-to-dose equivalent conversion and quality factor calculation. The Combination Thermoluminescence/Track Etch Dosimeter (TLD/TED) was developed to extend the effective neutron energy range of the conventional TLDs to improve detection of fast-energy neutrons. An ...

International Nuclear Information System (INIS)

The Monte Carlo transport codes LAHET and MCNP were used to calculate energy fluence spectra at three neutron therapy facilities. The results compare very favourably with measured data. Kerma spectra and the ratio of ICRU muscle tissue kerma to A-150 kerma, along the carbon to oxygen kerma ratio, were determined. Absorbed dose rate calculations are in reasonable agreement with measured values. Use of these codes to study modifications to existing therapy beams is briefly discussed. (author).

CERN Document Server

Monte Carlo calculations using the codes PENELOPE and GEANT4 have been performed to characterize the dosimetric properties of monoenergetic photon point sources in water. The dose rate in water has been calculated for energies of interest in brachytherapy, ranging between 10 keV and 2 MeV. A comparison of the results obtained using the two codes with the available data calculated with other Monte Carlo codes is carried out. A chi2-like statistical test is proposed for these comparisons. PENELOPE and GEANT4 show a reasonable agreement for all energies analyzed and distances to the source larger than 1 cm. Significant differences are found at distances from the source up to 1 cm. A similar situation occurs between PENELOPE and EGS4.

Energy Technology Data Exchange (ETDEWEB)

In electron beam therapy, tissue overdose due to electrons backscattered from lead has been profusely studied. To quantify this dose enhancement effect, an electron backscatter factor (EBF) wasdefined as the ratio of dose at the tissue-inhomogeneity interface with and without the scatterer present. The dependence of the EBF on energy at the scatterer surface is not well known for energies lower than 3 MeV which is the most frequent clinical situation. In this work, we have done Monte Carlo calculations with the GEANT code to study EBF in lead at this energy range. The applicability of this code and the developed procedure for dose estimation has been experimentally verified. The dependence of the EBF on the beam energy incident on the scatterer has been studied for different nominal beam energies ...

International Nuclear Information System (INIS)

The population doses and risks of stochastic effects from occupational exposures in Japan in 1978 were estimated on the basis of a nation-wide survey. The survey was conducted on annual collective dose equivalents by sex, age group and type of radiation work for about 82,500 workers other than the workers in nuclear power stations. The data on the workers in nuclear power stations were obtained from the offitial publication of the Japan Nuclear Safety Commission. The total number of workers except for nuclear power stations was estimated to be about 170,000 persons. Radiation works were subdivided as follows: medical works including dental; nondestructive inspectional; non-atomic energy industrial; research and educational; atomic energy industrial and nuclear power industrial. The annual collective dose equivalents were estimated to be about 6,000 man rem for medical workers, 450 ...

Science.gov (United States)

Examples are used to demonstrate that a shift in the point of emphasis is necessary with regard to radiation hazard in medicinal X-ray diagnosis. The parameters employed in this study to calculate somatic dose (SD) and somatically significant dose (SSD) m...

CERN Document Server

High energy muon colliders, such as the TeV-scale conceptual designs now being considered, are found to produce enough high energy neutrinos to constitute a potentially serious off-site radiation hazard in the neighbourhood of the accelerator site. A general characterization of this radiation hazard is given, followed by an order-of-magnitude calculation for the off-site annual radiation dose and a discussion of accelerator design and site selection strategies to minimize the radiation hazard.

International Nuclear Information System (INIS)

For the Convolution, Superposition and Monte Carlo methods, energy spectrum data is an essential parameter. Especially, by using Monte Carlo method, if the adequate properties of electrons are set, complex energy spectrum data can be calculated by simple input. However, adjustment of the property of electrons incident on the target of linear accelerator is time-consuming procedure. To cover the difference of many accelerators, it is important how we obtain accurate energy spectrum by simple methods. Especially, the total accuracy of dose calculation depends on the agreement of measured and calculated percentage depth dose (PDD) and off-axis ratio (OAR). Thus, a simple method for the determination of the simulation parameters was considered. To reduce the adjustment procedure, we selected values of important three ...

International Nuclear Information System (INIS)

An ytterbium-169 high dose rate brachytherapy source, distinguished by an intensity-weighted average photon energy of 92.7 keV and a 32.015#+-#0.009 day half-life, is characterized in terms of the updated AAPM Task Group Report No. 43 specifications using the MCNP5 Monte Carlo computer code. In accordance with these specifications, the investigation included Monte Carlo simulations both in water and air with the in-air photon spectrum filtered to remove low-energy photons below 10 keV. TG-43 dosimetric data including S_K, D(r,#theta#), #LAMBDA#, g_L(r), F(r,#theta#), #phi#_a_n(r), and #phi#_a_n were calculated and statistical uncertainties in these parameters were derived and calculated in the appendix.

Energy Technology Data Exchange (ETDEWEB)

This report is the first revision to a series of reports on radionuclides inn the SRS environment. Tritium was chosen as the first radionuclide in the series because the calculations used to assess the dose to the offsite population from SRS releases indicate that the dose due to tritium, through of small consequence, is one of the most important the radionuclides. This was recognized early in the site operation, and extensive measurements of tritium in the atmosphere, surface water, and ground water exist due to the effort of the Environmental Monitoring Section. In addition, research into the transport and fate of tritium in the environment has been supported at the SRS by both the local Department of Energy (DOE) Office and DOE`s Office of Health and Environmental Research.

International Nuclear Information System (INIS)

Purpose: In this paper, we present an alternative to the originally proposed technique for the delivery of spatially fractionated radiation therapy (GRID) using multi-leaf collimator (MLC) shaped fields. We employ the MLC to deliver various pattern GRID treatments to large solid tumors and dosimetrically characterize the GRID fields. Methods and materials: The GRID fields were created with different open to blocked area ratios and with variable separation between the openings using a MLC. GRID designs were introduced into the Pinnacle"3 treatment planning system, and the dose was calculated in a water phantom. Ionization chamber and film measurements using both Kodak EDR2 and Gafchromic EBT film were performed in a SolidWater phantom to determine the relative output of each GRID design as well as its spatial dosimetric characteristics. Results: Agreement within 5.0% was observed between the Pinnacle"3 predicted dose ...

International Nuclear Information System (INIS)

Full text: Verification of the dose delivered to a patient during radiotherapy is an important quality assurance procedure, however this is rarely performed due to the extra time involved. Electronic portal images (EPIs) are currently acquired at many centres during radiotherapy treatment for positioning verification. These could be utilised for dose verification provided 1) an accurate prediction of the dose transmitted through the patient to the EPID can be produced for the patients' radiotherapy beams, and, 2) the EPID image can be converted to an accurate measured dose. Ideally, the radiotherapy planning system (RTPS) would be used to produce the predicted dose as part of the planning procedure. The aim of this project is to investigate whether the convolution-superposition model of the Pinnacle RTPS can accurately calculate dose ...

International Nuclear Information System (INIS)

Current methods to calculate dose distributions with organ motion can be broadly classified as 'dose convolution' and 'fluence convolution' methods. In the former, a static dose distribution is convolved with the probability distribution function (PDF) that characterizes the motion. However, artifacts are produced near the surface and around inhomogeneities because the method assumes shift invariance. Fluence convolution avoids these artifacts by convolving the PDF with the incident fluence instead of the patient dose. In this paper we present an alternative method that improves the accuracy, generality as well as the speed of dose calculation with organ motion. The algorithm starts by sampling an isocenter point from a parametrically defined space curve corresponding to the patient-specific motion trajectory. Then a photon is sampled in the ...

International Nuclear Information System (INIS)

Neutron and gamma ray energy spectra were measured using an NE-213 scintillator at depths of 7.2, 15.2, and 22.2 cm in a tissue-equivalent phantom which was uniformly irradiated on one face by deuterium--tritium (DT) neutrons. Coupled neutron--gamma ray multigroup discrete-ordinates calculations were performed using semi-infinite slab geometry. These calculations were used to supplement the measured spectra below 1 MeV. Similar calculations were performed to study the perturbation in the phantom due to the detector. The measured and calculated spectra were used to determine the kerma distributions for neutrons and gamma rays at each location. The gamma radiation was determined to contribute more than 10% of the total dose at each depth. The calculated kerma also reveals that a knowledge of the gamma ray spectra below 1 MeV is desirable. Key ...

International Nuclear Information System (INIS)

Target materials for inertial fusion energy (IFE) power plant designs might be selected for a wide variety of reasons including wall absorption of driver energy, material opacity, cost and ease of fabrication. While each of these issues are of great importance, target materials should also be selected based upon their safety and environmental (S and E) characteristics. The present work focuses on the recycling, waste management and accident dose characteristics of potential target materials. If target materials are recycled so that the quantity is small, isotopic separation may be economically viable. Therefore, calculations have been completed for all stable isotopes for all elements from lithium to polonium. The results of these calculations are used to identify specific isotopes and elements that are most likely to be offensive as well as those most likely to be acceptable in ...

International Nuclear Information System (INIS)

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).

KoreaScience (Korea)

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UK PubMed Central (United Kingdom)

BackgroundThe aim of this study was to compare and to validate different dose calculation algorithms for the use in radiation therapy of small lung lesions and to optimize the treatment...Full Text Available

International Nuclear Information System (INIS)

The effects of extended source-to-surface distance (SSD) on the electron beam dose profiles were evaluated for various electron beam energies - 6, 9, 12, 15 and 20 MeV - and the accuracy of various output correction methods was analysed on a Mitsubishi linear accelerator using a radiation field analyser (RFA). The dose fall-off region of the central axis depth-dose curves was nearly independent for SSDs up to 120 cm where as in the build-up region, a marginal reduction of surface dose was observed, particularly for lower energies and for smaller field sizes. Effective SSDs and virtual source distances were evaluated for field sizes ranging from 5x5 to 15x15 cm"2 for various energies. Curve fitting was done with the measured outputs with various equations and coefficients were evaluated. The accuracy of the derived output correction factors ...

International Nuclear Information System (INIS)

IMRT optimization requires a fast yet relatively accurate algorithm to calculate the iteration dose with small memory demand. In this paper, we present a dose calculation algorithm that approaches these goals. By decomposing the infinitesimal pencil beam (IPB) kernel into the central axis (CAX) component and lateral spread function (LSF) and taking the beam's eye view (BEV), we established a non-voxel and non-beamlet-based dose calculation formula. Both LSF and CAX are determined by a commissioning procedure using the collapsed-cone convolution/superposition (CCCS) method as the standard dose engine. The proposed dose calculation involves a 2D convolution of a fluence map with LSF followed by ray tracing based on the CAX lookup table with radiological distance and divergence correction, resulting in ...

Energy Technology Data Exchange (ETDEWEB)

Simulations and experiments have been carried out to explore using a plastic scintillator as a dosimetry probe in the vicinity of a pulsed bremsstrahlung source in the range 4 to 20 MeV. Taking advantage of the tissue-equivalent properties of this detector in conjunction with the use of a fast digital signal processor near real-time dosimetry was shown to be possible. The importance of accounting for a broad energy electron beam in bremsstrahlung production, and photon scattering and build-up, in correctly interpreting dosimetry results at long stand-off distances is highlighted by comparing real world experiments with ideal geometry simulations. Close agreement was found between absorbed energy calculations based upon spectroscopic techniques and calculations based upon signal integration, showing a ratio between 10 MeV absorbed dose to 12 MeV absorbed dose of ...

International Nuclear Information System (INIS)

The goal of this work is to present a systematic Monte Carlo validation study on the clinical implementation of the enhanced dynamic wedges (EDWs) into the Pinnacle"3 (Philips Medical Systems, Fitchburg, WI) treatment planning system (TPS) and QA procedures for patient plan verification treated with EDWs. Modeling of EDW beams in the Pinnacle"3 TPS, which employs a collapsed-cone convolution superposition (CCCS) dose model, was based on a combination of measured open-beam data and the 'Golden Segmented Treatment Table' (GSTT) provided by Varian for each photon beam energy. To validate EDW models, dose profiles of 6 and 10 MV photon beams from a Clinac 2100 C/D were measured in virtual water at depths from near-surface to 30 cm for a wide range of field sizes and wedge angles using the Profiler 2 (Sun Nuclear Corporation, Melbourne, FL) diode array system. The EDW output factors (EDWOFs) for square fields from 4 to 20 cm ...

International Nuclear Information System (INIS)

For a given linac design, the dosimetric characteristics of a photon beam are determined uniquely by the energy and radial distributions of the electron beam striking the x-ray target. However, in the usual commissioning of a beam from measured data, a large number of variables can be independently tuned, making it difficult to derive a unique and self-consistent beam model. For example, the measured dosimetric penumbra in water may be attributed in various proportions to the lateral secondary electron range, the focal spot size and the transmission through the tips of a non-divergent collimator; the head-scatter component in the tails of the transverse profiles may not be easy to resolve from phantom scatter and head leakage; and the head-scatter tails corresponding to a certain extra-focal source model may not agree self-consistently with in-air output factors measured on the central axis. To reduce the number of adjustable variables in beam modelling, we replace ...

Energy Technology Data Exchange (ETDEWEB)

The Effective Dose Equivalent Concept defined by the International Commission on Radiological Protection in 1977 considers the risk from irradiation including both hereditary and somatic effects. This paper will deal with the definition of a concept for somatic effects only, the somatically significant dose equivalent. This is defined as the dose equivalent which if received by every member of the population, would be expected to produce the same total somatic injury to the population as does the actual dose equivalent received by various individuals. The somatically effective dose equivalent for a particular radiopharmaceutical is the weighted sum of the average dose equivalent to various organs. The dose equivalent to various organs can be derived from an extended MIRD formalism also considering the rest of body excluding the source ...

International Nuclear Information System (INIS)

While there have been many experimental and calculational investigations on absorbed dose distribution in the patient resulting from conventional X-ray procedures, such data for computerized tomography (CT) are still sparse. As this diagnostic procedure has shown a rapid increase in application during recent years, we have determined absorbed dose to body organs in a human phantom resulting from CT examinations. The exposure model consists of the heterogeneous MIRD-5 phantom and a suitable Monte-Carlo method to calculate absorbed dose to organs of interest. The exposure conditions are specified according to the exposure specifications of a CT-scanner currently in use. The calculations cover the range of body tissues of interest in terms of organ absorbed doses as well as a risk weighted absorbed dose. A detailed example ...

International Nuclear Information System (INIS)

The Monte Carlo method is used to analyse the dose fall-off at the exit surface of a megavoltage photon beam. The convolution/superposition method of dose calculation using Monte-Carlo-generated homogeneous photon kernels is shown to be in error for exit dose calculation. Instead, photon kernels that incorporate modelling of the exit surface were generated, also using Monte Carlo, to analyse the problem, and the calculated dose fall-off using these kernels agrees well with measured data. In addition, the physics underlying the characteristics of the dose fall-off is analysed based on complete Monte Carlo modelling. Practical improvements to the convolution/superposition method are suggested. (Author).

CERN Document Server

The resolution of X-ray diffraction microscopy is limited by the maximum dose that can be delivered prior to sample damage. In the proposed Serial Crystallography method, the damage problem is addressed by distributing the total dose over many identical hydrated macromolecules running continuously in a single-file train across a continuous X-ray beam, and resolution is then limited only by the available molecular and X-ray fluxes and molecular alignment. Orientation of the diffracting molecules is achieved by laser alignment. We evaluate the incident X-ray fluence (energy/area) required to obtain a given resolution from (1) an analytical model, giving the count rate at the maximum scattering angle for a model protein, (2) explicit simulation of diffraction patterns for a GroEL-GroES protein complex, and (3) the frequency cut off of the transfer function following iterative solution of the phase problem, and reconstruction ...

Energy Technology Data Exchange (ETDEWEB)

High dose rate (HDR) brachytherapy for treating a cervix carcinoma has become popular, because it eliminates many of the problems associated with conventional brachytherapy. In order to improve the clinical effectiveness with HDR brachytherapy, a dose calculation algorithm, optimization procedures, and image registrations need to be verified by comparing the dose distributions from a planning computer and those from a humanoid phantom. In this study, the humanoid phantom was fabricated in order to verify the absolute doses and the relative dose distributions. The measured doses from the humanoid phantom were then compared with the treatment planning system for the dose verification. The humanoid phantom needs to be designed such that the dose distributions can be quantitatively evaluated ...

Energy Technology Data Exchange (ETDEWEB)

The risks from radiation exposure during radiological diagnosis has usually been estimated in relation to genetic changes. Relevant information has been expressed as the genetically significant dose. In this paper we attempt to produce an analogous measure for evaluating the somatic risk in the form of a somatically significant dose index for radiological and CT examinations. It is shown that, for both types of examination, the two risk factors may be entirely different.

International Nuclear Information System (INIS)

Previously, an analytical dose calculation algorithm for MLC-based radiotherapy was developed and commissioned, which includes a detailed model of various MLC effects as a unique feature [1]. The algorithm was originally developed as an independent verification of the treatment planning system's dose calculation and it explicitly modeled spatial and depth dependent MLC effects such as interleaf transmission, the tongue-and-groove effect, rounded leaf ends, MLC scatter, beam hardening, and gradual MLC transmission fall-off with increasing off-axis distance. Originally the algorithm was implemented in Mathematica trademark (Wolfram). To speed up the calculation time and to be able to calculate high resolution 2D dose distributions within a reasonable time frame (<2 s) the algorithm needs to be optimized and to be embedded in a user friendly ...

Energy Technology Data Exchange (ETDEWEB)

Potential maximum radiation dose rates were calculated for the former Alba Craft Laboratory site in Oxford, Ohio, which was involved in machining of uranium metal in the 1950s for the U.S. atomic energy program. The site is not currently being used. The residual radioactive material guidelines (RESRAD) computer code, which implements the methodology described in the US Department of Energy`s (DOE`s) manual for establishing residual radioactive material guidelines, was sued in this evaluation. Three potential land use scenarios were considered for the former Alba Craft site; the scenarios vary with regard to the type of site use, time spent at the site by the exposed individual, and sources of food consumed. Scenario A (a possible land use scenario) assumed industrial use of the site; Scenario B (a likely future land use scenario) assumed residential use of the site; and Scenario C (a possible but ...

International Nuclear Information System (INIS)

With accurate calculation algorithms in inverse planning for beamlet-based intensity modulated radiotherapy (IMRT), it takes time to calculate the dose matrix, which represents the dose distribution of each beamlet element to each voxel for unit fluence. To reduce the calculation time, coarse or approximate algorithms are often a choice, but this results in a final dose distribution that cannot reflect the real value. In addition, it is necessary to test if a coarse algorithm is capable of calculating the dose matrix of beamlets. In this work, simulated dynamics optimization algorithm was applied to optimize the segment weight to minish the dose error from the dose matrix calculation. After calculating the dose matrix ...

Energy Technology Data Exchange (ETDEWEB)

Graft copolymerization of sodium styrene sulfonate (SSS) onto electron beam (EB) irradiated poly(vinylidene fluoride) (PVDF) films was investigated to find out a simple preparation process for sulfonic acid proton exchange membranes with respect to monomer concentration, absorbed dose, temperature, film thickness and storage time. The reaction order of the monomer concentration and absorbed dose of grafting was found to be 2.84 and 1.20, respectively. The overall activation energy for graft copolymerization reaction was calculated to be 11.36 kJ/mol. The initial rate of grafting was found to decrease with an increase in the film thickness. The trapped radicals in the irradiated PVDF films remained effective in initiating the reaction without considerable loss in grafting level up to 180 days, when stored under -60 {sup o}C. The presence and distribution of polystyrene sulfonate grafts in the obtained ...

International Nuclear Information System (INIS)

By applying the linear-dose effect relation, the weighting factors for total risks recommended by IRCP can be transformed to weighting factors for somatic effects. Another weighting factor Msub(s) has to be used which takes into account the dependence of the latent period for occurrence of malignant disease and the variation of the incidence with time. On this basis a somatically significant dose equivalent can be defined as 'the dose equivalent which if received by every member of the population, would be expected to produce the same total somatic injury to the population as does the actual dose equivalent received by the various individuals', and an approximation has been derived for this. Tables are presented of the somatic effective dose equivalents calculated for different x-ray examinations for various organs and tissues. The S.E.D. equivalents have also ...

International Nuclear Information System (INIS)

The aim of this research work has been the estimation of the stochastic risk for five barium examinations. The sample was the population attending the Radiological Service of the 'Nuestra Senora de la Victoria' University Hospital, who had been treated with some barium examinations, set in five different groups: oesophagus tract, oesophagus-gastric-duodenal tract, intestinal tract, enteroclysis and double enema. To estimate the stochastic risk, it is necessary to know the organ dose. This can be calculated from the dose-area product which allows us to determine the effective dose using software. The dose-area product is the most suitable quantity to measure in these types of examination. We have evaluated the contribution that each procedure provides to the genetically significant dose, somatically significant dose, collective effective ...

International Nuclear Information System (INIS)

Full text: A semiempirical algorithm for absorbed dose calculation at off-axis points in irregular beams was implemented. It is well known that semiempirical methods are very useful because of their easy implementation and its helpfulness in dose calculation in the clinic. These methods can be used as independent tools for dosimetric calculation in many applications of quality assurance. However, the applicability of such methods has some limitations, even in homogeneous media, specially at off axis points, near beam fringes or outside the beam. Only methods derived from tissue-air-ratio (TAR) or scatter-maximum-ratio (SMR) have been devised for those situations, many years ago. Despite there have been improvements for these manual methods, like the Sc-Sp ones, no attempt has been made to extend their usage at off axis points. In this work, a semiempirical formalism was introduced, ...

International Nuclear Information System (INIS)

The focus of this study is to validate whether the sensitivity of dose distribution following the interface of different media can be used to distinguish between small variations of photon energy spectra in the context of the convolution/superposition algorithm in the polyenergetic implementation (Philips Pinnacle"3, ADAC Laboratories, Milpitas, CA). Calculations were performed in homogeneous water and heterogeneous lung/water phantoms. Spectra were generated, in which the weights of the low-, medium- and high-energy components were adjusted sequentially. The heterogeneity correction factor CF_l_u_n_g, the D_2_0/D_1_0 ratio for homogeneous water and logarithmic derivative in buildup region LD_b_u_i_l_d_u_p were assessed for their relative ability to discriminate between different spectra for various field sizes. In accordance with another study (Charland et al 2004), the superior discrimination ability ...

International Nuclear Information System (INIS)

N-type crystalline Si (100) implanted with 5 keV B ions was subsequently irradiated with MeV Si, O and F ions. The B atom profiles were measured by means of secondary ion mass spectrometer after the treatment of rapid thermal annealing. The results show that the transient enhanced diffusion of B atoms is effectively limited by the post-implantation of high energy ions at high dose. At the same irradiation conditions, it is found that the existence of a SiO_2 layer in the near surface of Si is even more effective in suppressing the transient enhanced diffusion of the doped B atoms. The results are qualitatively discussed in combination with the analyses of RBS/c measurements and calculation of the DICADA code

Energy Technology Data Exchange (ETDEWEB)

In order to calculate the doses received by the organs of 530 children treated by radiation for cancer between 1945 and 1969 at the G. Roussy Institute, we have developed a computer program for organ location calculation. To calculate the location of each child's organs of interest at the time of the treatment, only two parameters are necessary; sex and height or sex and age when the height at the time of the treatment is unknown. The algorithm is based on the metric studies of growth known as auxology. Each organ is located by one point representing its center. The model has been checked on 100 healthy children.

Energy Technology Data Exchange (ETDEWEB)

The in situ assembly states of the glucose transport carrier protein in the plasma membrane and in the intracellular (microsomal) storage pool of rat adipocytes were assessed by studying radiation-induced inactivation of the D-glucose-sensitive cytochalasin B binding activities. High energy radiation inactivated the glucose-sensitive cytochalasin B binding of each of these membrane preparations by reducing the total number of the binding sites without affecting the dissociation constant. The reduction in total number of binding sites was analyzed as a function of radiation dose based on target theory, from which a radiation-sensitive mass (target size) was calculated. When the plasma membranes of insulin-treated adipocytes were used, a target size of approximately 58,000 daltons was obtained. For adipocyte microsomal membranes, we obtained target sizes of approximately 112,000 and 109,000 daltons prior to and after insulin ...

Energy Technology Data Exchange (ETDEWEB)

This report revises estimates of population exposure to external natural background made by D. T. Oakley in 1972. The revisions include more recent estimates of dose equivalents from cosmic rays, use of 1970 U.S. census data, and corrections for building shielding and for self-shielding in the body. The dose equivalents calculated are those from cosmic rays and terrestrial radiation, and do not include doses from natural radioactive materials in the body.

CERN Document Server

Radiation protection of the personnel who will perform interventions in the LHC Beam Cleaning Insertions is mandatory and includes the design of equipment and the establishment of work procedures. Residual dose rates due to activated equipment are expected to reach significant values such that any maintenance has to be planned and optimized in advance. Three-dimensional maps of dose equivalent rates at different cooling times after operation of the LHC have been calculated with FLUKA. The simulations are based on an explicit calculation of induced radioactivity and of the transport of the radiation from the radioactive decay. The paper summarizes the results for the Beam Cleaning Insertions and discusses the estimation of individual and collective doses received by personnel during critical interventions, such as the exchange of a collimator or the installation of Phase 2. The given ...

International Nuclear Information System (INIS)

We present a development of the use of the AAPM TG-43 dose formalism applied to "1"3"7Cs gynecological implant sources. The geometry factor, radial dose function, and anisotropy function of a "1"3"7Cs source modeled after the Nuclear Associates 67-809 series stainless steel jacketed tube source were derived following the AAPM TG-43 formalism. The dose rate distribution through the center of the source using the AAPM TG-43 dose formalism is calculated and compared with the calculations obtained using the Sievert summation and Monte Carlo simulation. The three methods resulted in an agreement within less than 5%, or an isodose rate line agreement within 2 mm. We demonstrate that the AAPM TG-43 formalism can be applied to "1"3"7Cs linear sources and is capable of serving as a "1"3"7Cs dose calculation algorithm that can be ...

International Nuclear Information System (INIS)

The Radiation Technology Center from IPEN-CNEN/SP, Brazil, developed a revolutionary design and national technology, a small-sized continuous run and multipurpose industrial gamma irradiator, to be used as a demonstration facility for manufacturers and contract service companies, which need economical and logistical in-house irradiation system alternatives. Also, to be useful for supporting the local scientific community on development of products and process using gamma radiation, assisting the traditional and potential users on process validation, training and qualification of operators and radioprotection officers. The developed technology for this facility consists of a continuous tote box transport system, comprising a single concrete vault, where the automated transport system of products inside and outside of the irradiator utilizes a rotating door, integrated with the shielding, avoiding the traditional maze configuration. Covering 76 m"2 of floor area, the irradiator design is ...

Energy Technology Data Exchange (ETDEWEB)

Survival curves were constructed from dose-incidence curves for apoptosis in the crypts of mouse small intestine, using the number of apoptotic cells after high doses (N{sub M}) as maximum cell population size. The mean lethal doses (D{sub 0}) for the dose range 0-0.5 Gy were calculated for each time of day. A circadian rhythm in both D{sub 0} and N{sub M} values was detected, indicating that both the number and sensitivity of radiation-induced apoptosis were changing throughout the day. (author).

International Nuclear Information System (INIS)

The authors give a survey of the somatic radiation ris in X-ray diagnostics. A somatic dose index is calculated for different examination methods containing the organ doses to the red bone marrow, the lung, the female breast, and the thyroid gland and evaluating their somatic significance. If this somatic dose index by which the individual radiation risk is described, is multiplied by the examination frequencies per year in the German Federal Republic, one gets the somatically significant dose index, which is a measure of the collective somatic radiation risk. In this sense, mammography has the highest, and dental radiography the lowest collective radiation risk. (orig.).

Energy Technology Data Exchange (ETDEWEB)

Contributions to the population dose due to medical applications of ionising radiation are presented. It appears that contributions due to radiotherapy and X ray diagnosis are of comparable magnitude. To account for the age dependency of the radiation risks, contributions in terms of somatically significant dose equivalent are calculated as 0.3 mSv per caput per annum for X ray diagnosis and as 0.2 mSv per caput per annum for radiotherapy, the latter referring to only doses to organs outside the target volume. (author).

Energy Technology Data Exchange (ETDEWEB)

This study investigated dose to bone tissue in electron beam therapy. Measurements were made using films and thermoluminescent dosimeters in a polystyrene phantom containing bone inhomogeneity for 15-MeV, 12-MeV, and 9-MeV electron beams. An increase in dose of approximately 18%, 12%, and 11%, for the three electron energies respectively, relative to the dose in polystyrene, was found for bone material having an electron density (relative to water) of 1.73. Measurements were also made using films for 15- and 9-Mev electrons in a phantom with a mandibular bone and teeth. A dose enhancement in bone of approximately 10% and 7%, respectively, for the two energies was found in the phantom where the electron density of bone was about 1.60. These results suggest that injury to bone is possible in those clinical situations where high doses of ...

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We have developed a kinetic Monte Carlo (kMC) simulator that links atomic migration and binding energies determined primarily from first principles calculations to macroscopic phenomena and laboratory time scales. Input for the kMC simulation is obtained from a combination of ab initio planewave pseudopotential calculations, molecular dynamics simulations, and experimental data. The simulator is validated against an extensive series of experimental studies of the diffusion of B spikes in self-implanted Si. The implant energy, dose, and dose rate, as well as the detailed thermal history of the sample, are included. Good agreement is obtained with the experimental data for temperatures between 750 and 950 C and times from 15 to 255 s. At 1050o C we predict too little diffusion after 105 s compared to experiment: apparently, some mechanism which is not adequately ...

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According to enactment of reduced dose limit based on ICRP-60, the calculation of Derived Release Limits(DRL) on Wolsung NPPs was carried out. There are two methods of determination on DRL; that is MPC(Maximum Permissible Concentration) method and system analysis method. In order to use the system analysis method, lots of environmental data are necessary and complicated exposure pathway are considered. So we intend to apply MPC method that is sort of simple. In addition the calculated results were compared with derived release limit on Canadian nuclear power plant.

Energy Technology Data Exchange (ETDEWEB)

In 1978 the Marshall Islands Radiological Safety Program was organized to perform radiation measurements and assess radiation doses for the people of the Bikini, Enewetak, Rongelap and Utirik Atolls. One of the major field components of this program is whole- body counting (WBC). WBC is used to monitor the quantity of gamma- emitting radionuclides present in individuals. A primary objective of the program was to establish {sup 137}Cesium body contents among the Enewetak, Rongelap and Utirik populations. {sup 137}Cs was the only gamma-emitting fission radionuclide detected in the 1,967 persons monitored. {sup 137}Cs body burdens tended to increase with age for both sexes, and were higher in males. The average {sup 137}Cs dose Annual Effective Dose for the three populations was as follows: For Enewetak, the dose was 22{+-}4 {mu}Sv. For Utirik, the dose was 33{+-} 3 {mu}Sv. Since 1985 ...

International Nuclear Information System (INIS)

The purpose of this work was to study and quantify the differences in dose distributions computed with some of the newest dose calculation algorithms available in commercial planning systems. The study was done for clinical cases originally calculated with pencil beam convolution (PBC) where large density inhomogeneities were present. Three other dose algorithms were used: a pencil beam like algorithm, the anisotropic analytic algorithm (AAA), a convolution superposition algorithm, collapsed cone convolution (CCC), and a Monte Carlo program, voxel Monte Carlo (VMC++). The dose calculation algorithms were compared under static field irradiations at 6 MV and 15 MV using multileaf collimators and hard wedges where necessary. Five clinical cases were studied: three lung and two breast cases. We found that, in terms of accuracy, the CCC algorithm ...

International Nuclear Information System (INIS)

With the advent of intensity-modulated radiation therapy (IMRT), the inclusion of heterogeneity corrections is further complicated by the conformal delivery of many small beams forming steep dose gradients. Radiation treatment planning has evolved to take into account even small changes in tissue density so that the dose to tumor can be further optimized. However, different treatment planning systems incorporate different heterogeneity correction algorithms, and it is unclear whether any of these algorithms are superior to others in terms of accurately predicting delivered radiation doses relative to measurement in a clinical setting. The purpose of this study was to determine the accuracy of heterogeneity dose calculations from two widely used IMRT treatment planning systems (Pinnacle and Corvus) against measurement. These two systems handle heterogeneity dose ...

International Nuclear Information System (INIS)

Objective: To establish a computer program for rapid calculation of internal committed effective close through inhalation and ingestion pathways under radiological emergency. Methods: Visual Basic 6.0 is used to compile the generic procedures of internal committed effective dose by inhalation and ingestion in IAEA-TECDOC-1162, Generic Procedures for Assessment and Response during a Radiological Emergency. Results: The assessment methodology of internal committed effective dose by inhalation and ingestion under radiological emergency in the report IAEA-TECDOC-1162 can be coded into a computer program. Conclusions: This research provides a rapid method of assessment for internal committed effective dose by inhalation and ingestion under radiological emergency, and it may provide needed dosimetry data for treatment under emergency response. (authors)

British Library Electronic Table of Contents (United Kingdom)

During the last few decades, accuracy in photon and electron radiotherapy has increased substantially. This is partly due to enhanced linear accelerator technology, providing more flexibility in field definition (e.g. the usage of computer-controlled dynamic multileaf collimators), which led to intensity modulated radiotherapy (IMRT). Important improvements have also been made in the treatment planning process, more specifically in the dose calculations. Originally, dose calculations relied heavily on analytic, semi-analytic and empirical algorithms. The more accurate convolution/superposition codes use pre-calculated Monte Carlo dose "kernels" partly accounting for tissue density heterogeneities. It is generally recognized that the Monte Carlo method is able to increase accuracy even furt...

International Nuclear Information System (INIS)

During the last few decades, accuracy in photon and electron radiotherapy has increased substantially. This is partly due to enhanced linear accelerator technology, providing more flexibility in field definition (e.g. the usage of computer-controlled dynamic multileaf collimators), which led to intensity modulated radiotherapy (IMRT). Important improvements have also been made in the treatment planning process, more specifically in the dose calculations. Originally, dose calculations relied heavily on analytic, semi-analytic and empirical algorithms. The more accurate convolution/superposition codes use pre-calculated Monte Carlo dose 'kernels' partly accounting for tissue density heterogeneities. It is generally recognized that the Monte Carlo method is able to increase accuracy even further. Since the second half of the 1990s, several Monte Carlo ...

International Nuclear Information System (INIS)

The equivalent doses of K-feldspar grains in a range of grain sizes from 90 to 250#mu#m diameter were measured using a single-aliquot regenerative-dose protocol for the infrared stimulated luminescence (IRSL) signals for two samples of desert sand. The equivalent doses for each sample were compared with that for the 125-150#mu#m grains of quartz from the same samples. The results suggested that the K-feldspar equivalent doses were underestimated because of anomalous fading. Measurements of the decay of the IRSL signals following laboratory irradiation for these two samples, and an additional one from a previously published isochron study, showed anomalous fading during the period of laboratory storage. The decay rate was about 3% per decade for all samples and was independent of the grain size used. Using plots of equivalent doses for K-feldspars as a function of their ...

International Nuclear Information System (INIS)

In 16 female patients wick colpourethrocystography was performed directly successively with large-size films as well as medium-size films (intensifier fluorography). The area exposure products were measured by a dosemeter closely attached to the diaphragm and separately for radiography and fluorography, resp. Surface doses as well as organ doses were calculated according to Rosenstein. The average radiatin doses of the active bone marrow were 6.03 mGy for examination with large-size films and 1.27 mGy for fluorography; the average gonadal doses were 7.45 mGy and 1.56 mGy, resp. The portion of fluoroscopy in radiation exposure amounted to 14.8% in large-size film examination, but was 74.0% in medium-size examination. Thus the comparative results revealed a significant reduction of the patient's radiation dose by application of intensifier fluorography in ...

International Nuclear Information System (INIS)

The accuracy of dose computation within the lungs depends strongly on the performance of the calculation algorithm in regions of electronic disequilibrium that arise near tissue inhomogeneities with large density variations. There is a lack of data evaluating the performance of highly developed analytical dose calculation algorithms compared to Monte Carlo computations in a clinical setting. We compared full Monte Carlo calculations (performed by our Monte Carlo dose engine MCDE) with two different commercial convolution/superposition (CS) implementations (Pinnacle-CS and Helax-TMS's collapsed cone model Helax-CC) and one pencil beam algorithm (Helax-TMS's pencil beam model Helax-PB) for 10 intensity modulated radiation therapy (IMRT) lung cancer patients. Treatment plans were created for two photon beam qualities (6 and 18 MV). For each ...

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Numerical simulations are used to predict the migration of radionuclides from the disposal units at Material Disposal Area G through the vadose zone and into the main aquifer in support of a radiological performance assessment and composite analysis for the site. The calculations are performed with the finite element code, FEHM. The transport of nuclides through the vadose zone is computed using a three-dimensional model that describes the complex mesa top geology of the site. The model incorporates the positions and inventories of thirty-four disposal pits and four shaft fields located at Area G as well as those of proposed future pits and shafts. Only three nuclides, C-14, Tc-99, and I-129, proved to be of concern for the groundwater pathway over a 10,000-year period. The spatial and temporal flux of these three nuclides from the vadose zone is applied as a source term for the three-dimensional saturated zone model of the main aquifer that underlies the site. The ...

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Health physicists from the Brookhaven National Laboratory (BNL) visited the Savannah River Site (SRS) as one of 12 facilities operated by the Department of Energy (DOE) contractors with annual collective dose equivalents greater than 100 person-rem (100 person-cSv). Their charter was to review, evaluate and summarize as low as reasonably achievable (ALARA) techniques, methods and practices as implemented. This presentation gives an overview of the two selected ALARA practices implemented at the SRS: Administrative Exposure Limits and Goal Setting. These dose control methods are used to assure that individual and collective occupational doses are ALARA and within regulatory limits.

British Library Electronic Table of Contents (United Kingdom)

Purpose Study the radiolysis of solid-state metoclopramide hydrochloride at various absorbed doses. Elucidate the structure of the degradation products to gain information on the radiolysis mechanisms. Methods Solid-state metoclopramide samples were irradiated at several doses with gamma rays and high-energy electrons to evaluate the influence of the dose rate. High-performance liquid chromatography with a diode array detector was used to measure the chemical potency as a function of the absorbed dose and to quantify the degradation products. The characterization of degradation products was performed by liquid chromatography/atmospheric pressure chemical ionization/tandem mass spectrometry. Results The degradation of solid-state metoclopramide after irradiation was negligible. No qualitati...

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(001) CZ silicon wafers were implanted with arsenic (As{sup +}) at energies of 10--50 keV to doses of 2 {times} 10{sup 14} to 5 {times} 10{sup 15}/cm{sup 2}. All implants were amorphizing in nature. The samples were annealed at 700 C for 16 hrs. The resultant defect microstructures were analyzed by XTEM and PTEM and the As profiles were analyzed by SIMS. The As profiles showed significantly enhanced diffusion in all of the annealed specimens. The diffusion enhancement was both energy and dose dependent. The lowest dose implant/annealed samples did not show As clustering which translated to a lack of defects at the projected range. At higher doses, however, projected range defects were clearly observed, presumably due to interstitials generated during As clustering. The extent of enhancement in diffusion and its relation to the defect microstructure is explained ...

International Nuclear Information System (INIS)

To calculate the energy band structures in semiconductors using the relativistic augmented plane wave method, atomic potential and charge density are needed, which are calculated by self-consistent method. Wave function for one electron is determined by solving the Dirac equation with the Hartree-Fock equation based on the slater's exchange potential. The results of calculation for Cu"+"1 are given. (Author).

CERN Document Server

Within the framework of a modified Balitsky-Kovchegov equation, we calculated and provide estimates of non-linear saturation effects expected in the LHC range of energies.

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Surface doses received by patients and operators were measured during 30 interventional radiological procedures (ten percutaneous transhepatic biliary drainages, ten percutaneous nephrostomies, ten percutaneous transluminal angioplasties). In addition, organ doses to the patient were determined using an Alderson-Rando phantom. These served as a basis for calculating the so-called somatic dose indices. It was found that the somatic radiation risk to the patient is relatively small despite prolonged periods of fluoroscopy. However, exposure of the hands and lenses of the operator could easily reach the limits thought acceptable while carrying out these procedures with additional angiography. (orig).

International Nuclear Information System (INIS)

Building on the concepts of MIRD methods described by Webber, Watson and others at this Symposium on the Dosimetry of Administered Radionuclides, we will now consider how to apply these principles to several experimentally based open-quote macroclose quotes and multicellular models. Specifically, methods to calculate absorbed dose using different types of particulate emission (alpha, beta) with a variety of antibody carriers (IgG, F(ab')_2, Fab) for radioimmunotherapy (RIT) will be reviewed. Additionally, a discussion of direct measurement methods at the multicellular level will reveal the problems of tumor absorbed dose heterogeneity when applied to animal and clinical studies.

International Nuclear Information System (INIS)

A dose calculation algorithm for MLC based conformal radiotherapy is described in this paper. The algorithm is formulated by the coordinate of MLC leaves. Verification on the algorithm is made by comparing the dose distributions generated by this algorithm with that generated by a Differential Convolution Superposition algorithm for various regular and irregular fields. The results demonstrate that the present algorithm has suitable accuracy and high computational efficiency, thus it could be useful for the treatment planning process in MLC based conformal radiotherapy, where the workload for interactively or automatically designing the shapes of MLC is heavy. (authors)

CERN Document Server

Monte Carlo calculations of proton irradiation of permanent magnets for the TRADE experiment have been performed. An irradiation dose of about 4´106 Gy/yr/mA has been estimated due to beam losses in normal operating conditions. Existing experimental results indicate that this irradiation level may induce a considerable demagnetization: in fact, a dose of 6´107 Gy induces a remanence loss of 0.3 % on samples of Sm2Co17 magnets, which are the most resistant type. More detailed calculations with the final design of the magnets and of the beam line are suggested, to determine if the irradiation levels allowed a reliable operation of the permanent magnets for the entire duration of the TRADE experiment. Damage and gas production rates have also been calculated; the values obtained are very low, thus confirming that the demagnetization process is in great part reversible.

International Nuclear Information System (INIS)

For comparison of radiation exposure and risk in different diagnostic procedures for adults and children dose measurements and calculations of organs with special risk were carried out. Parameters of image formation influencing image quality as well as of exposure concerning infants and children are recorded and discussed as to radiation exposure and protection. Conclusions are drawn with respect to systems of image formation and to standards of examination and quality assurance.

International Nuclear Information System (INIS)

Concentrations of 226Ra, 232Th, and 40K measured in bauxite waste, local building materials, and soils are presented and used in model equations to estimate the effective gamma dose-equivalent increments over background in the center of a standard-sized room in a prototype house. Calculated and measured values compare reasonably well.

Energy Technology Data Exchange (ETDEWEB)

The dose from heavy ion beams has been calculated using a one-dimensional transport theory and evaluated for 670 MeV/amu /sup 20/Ne beams in water. The result is presented so as to be applicable to arbitrary ions for which the necessary interaction data are known. The present evaluation is based on the Silberberg-Tsao fragmentation parameters augmented with light fragment production from intranuclear cascades, recently calculated nuclear absorption cross sections, and evaluated stopping power data. Comparison with recent experimental data obtained at the Lawrence Berkeley Laboratory reveals the need for more accurate fragmentation data.

International Nuclear Information System (INIS)

The distribution of radiation dose commitments within the body that can result from the lung deposition of a number of transuranic radionuclides ("2"3"7Pu, "2"3"8Pu, "2"3"9Pu, "2"4"0Pu, "2"4"1Pu, "2"4"2Pu, "2"4"3Pu, "2"4"4Pu, "2"4"1Am, "2"4"2Am, "2"4"3Am, "2"4"4Am, "2"4"2Cm, "2"4"3Cm, "2"4"4Cm, and "2"4"6Cm) was calculated. The variables that influence these organ dose commitments include the mobility of the particle or its dissolution products within the body, the radiation characteristics of the inhaled radionuclides and their progeny, and the size of the particles inhaled. In the calculation of organ dose commitments for whole-body, lungs, liver, bone tissues, kidneys, and gastrointestinal tract from the inhalation of transuranium radionuclides, physical characteristics of importance are the dimensions of the particle, its aerodynamic properties, and its density. For particles ...

International Nuclear Information System (INIS)

Monte Carlo (MC) dose calculations can be accurate but are also computationally intensive. In contrast, convolution superposition (CS) offers faster and smoother results but by making approximations. We investigated MC denoising techniques, which use available convolution superposition results and new noise filtering methods to guide and accelerate MC calculations. Two main approaches were developed to combine CS information with MC denoising. In the first approach, the denoising result is iteratively updated by adding the denoised residual difference between the result and the MC image. Multi-scale methods were used (wavelets or contourlets) for denoising the residual. The iterations are initialized by the CS data. In the second approach, we used a frequency splitting technique by quadrature filtering to combine low frequency components derived from MC simulations with high frequency components derived from CS components. ...

International Nuclear Information System (INIS)

It needs accurate estimation of radiation level for verifying machinery and cable in Nuclear Power Plant. Therefore, in this study, we used ESR(Electron Spin Resonance) system for estimate dose of Alanine dosimeter. Alanine/ESR dosimetry, already known as a dosimetric method in medical and industrial field, was applied to estimate dose quantity at cable locations within a nuclear power plant as a part of equipment qualification program. Alanine/ESR dosimetry of absorbed dose range is 1 - 100 KGy. The alanine dosimeter is not significantly affected by temperature and fading is limited to 1% per year. The alanine dosimeters were fixed on the targeted cable or nearest position to measure dose quantity to get accurate value. Alanine dosimeters were scanned by commercially used two different ESR systems, e-scan and EMX series for alanine dosimeters. To estimate more accurate dose, two ...

International Nuclear Information System (INIS)

We calculated the energies of asymmetric nuclear matter at zero and finite temperatures with the cluster variational method. At zero temperature, the expectation value of the two-body Hamiltonian composed of the kinetic energies and the AV18 two-body forces is calculated with the Jastrow wave function in the two-body cluster approximation. The obtained two-body energy is in good agreement with the result with the Fermi Hypernetted Chain (FHNC) calculation by Akmal et al. The energy caused by the UIX three-body forces is treated somewhat phenomenologically so that the total energy reproduces the empirical saturation point. Furthermore, the parameters included in the three-body energy are readjusted so that the Thomas-Fermi (TF) calculations with use of the obtained ...

Energy Technology Data Exchange (ETDEWEB)

Solar ultraviolet radiation is damaging for living organisms due to its high energy pro each photon. The UV radiation is often separated into three regions according to the wavelength: UVC (200-280 nm), UVB (280-320 nm) and UVA (320-400 nm). The most hazardous part, UVC is absorbed completely in the upper atmosphere by molecular oxygen. UVB radiation is absorbed by atmospheric ozone partly, and it is reaching Earth`s surface, as UVA radiation. Besides atmospheric ozone, very important factors in determining the intensity of UVB radiation globally are the solar zenith angle and cloudiness. It may be calculated from global ozone changes that the clear-sky UVB doses may have enhanced by 10-15 % during spring and 5-10 % during summer at the latitudes of Finland, following the decrease of total ozone between 1979-90. The Finnish ozone and UV monitoring activities have become a part of international activities, especially the EU ...

Energy Technology Data Exchange (ETDEWEB)

The real-time dose assessment system under development has been updated and the technology for tracer experiment has been established. The calculation of external gamma dose is the most difficult and time-consuming part of the dose calculations. The characteristics of external gamma exposure have been investigated and the method for reducing the calculation time has been devised. The internal exposure via the ingestion of the contaminated foodstuffs is one of the important pathways to the total radiological exposure. In the emergency, it is necessary to take an action such like food ban to protect the internal exposure. An algorithm for the interface between the real-time system and the food chain model has been provided. The second field tracer experiment over flat terrain has been carried out on a plain in Iksan city in Junrabook-Do. Sequential tracer sampler ...

Energy Technology Data Exchange (ETDEWEB)

This revised edition discusses a large number of renewable energy systems. Future trends are outlined. Economic efficiency calculations are explained and analyzed. Many exemplary calculations and graphical representations illustrate the various technologies and methods of calculation. This standard book addresses university students, scientists and engineers in research and industry. The accompanying DVD is one of the most extensive compilations of demo programs and full versions for simulation of renewable energy systems, all illustrations of the book in electronic format, additional text and a user-friendly navigation aid. (orig.)

Energy Technology Data Exchange (ETDEWEB)

The GASPAR module utilized in MAXIGASP and POPGASP has been verified by hand calculations. The program operates as documented by the NRC [Eckerman et. al. 1980]. Equations used in the code to calculate downwind deposition rates, concentrations in air, on ground surfaces, and in vegetables, meat, and milk are provided in this report.

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 ...

Energy Technology Data Exchange (ETDEWEB)

CT-Expo is a novel MS Excel application for assessing the radiation doses delivered to patients undergoing CT examinations, based on computational methods that were used to analyze the data collected in the German survey on CT practice in 1999. The program enables the calculation of all dose quantities of practical value, such as axial dose free-in-air, weighted CTDI, dose-length product, effective dose and uterine dose. In contrast to existing programs for CT dose assessment, CT-Expo offers a number of unique features, such as gender-specific dose calculation for all age groups (adults, children, newborns), applicability to all existing scanner models including correction of scanner-specific influences, and the possibility of comparison with the results from the German CT survey ...

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Possible accident scenarios for a fusion reactor include breaches in the vacuum or cooling system. Intruding air or steam could react with structural or plasma facing materials, possibly mobilizing radioactive isotopes. Safety assessments must consider the early dose at the site boundary from the release of these activated materials. Previous calculations have indicated that cobalt isotopes dominate dose calculations for designs using stainless steel. Values used in these calculations, however, had been largely determined by the measurement limits of the chemical analysis methodology instead of measured releases. The purpose of the current study was to refine the analytical method to reduce the limit for detecting cobalt, and then test PCA steel in air and steam between 973 and 1473 K. Goals were to obtain more accurate measurements of cobalt mobilization in terms of g/m{sup ...

International Nuclear Information System (INIS)

Pharmacokinetics is studied, radiation doses to patients when using domestic thallium-201 chloride in diagnosis of the heart ischemic disease is estimated; contribution into the total dose of thallium-201 (1.5 %), thallium-201 (0.2 %) and lead-201 + lead-203 (0.05 %) radionuclide impurities is also determined. Internal doses were estimated for a heterogeneous phantom of a standard man; the calculations were carried out using a computer. Scanning of patients which were treated with radiopharmaceuticals to be diagnosed was carried out using a whole body counter and gamma-chamber. Large intestine, kidneys and thyroid are the critical organs when using thallium-201 chloride. The highest contribution into the dose to organs and the whole body from thallium-200 and thallium-202 impurities being contained in thallium-201, doesn't exceed 8.6 %. The contribution into the ...

International Nuclear Information System (INIS)

Electron beams as a source of directed energy are under study at the Lawrence Livermore National Laboratory (LLNL). An intense 10-kA, 50-MeV, 50-ns full-width half-maximum, pulsed electron beam is generated by the prototype Advanced Test Accelerator (ATA) at the Laboratory's Site 300. Whenever the electron beam is stopped in materials, intense radiation is generated. Estimates based on available data in the literature show that for materials such as lead, photon radiation (x ray, gamma, bremsstrahlung) levels can be as large as 10"4 roentgens per pulse at 1 m in the zero-degree direction (i.e., the electron-beam direction). Neutrons, which are emitted isotropically, are produced at a level of 10"1"3 n/m"2 per pulse. Depending upon the number of pulses and the shielding geometry, the accumulated dose is potentially lethal to personnel and potentially damaging to instrumentation that may be used for diagnostics. To provide shielding for ...

International Nuclear Information System (INIS)

A simple method allowing easy calculation of the spatial damage energy distributions for ion-implanted materials is presented. The direct procedure takes account of the variation with depth of the lateral spreading of implanted ions, as well as the effects of energy transport by the recoiling target atoms. The subsequent computer program LUPIN-3D provides three-dimensional damage distributions and allows the construction of damage energy mappings. Various substrates of technological interest are investigated and several fields of application of the calculation are envisaged. The density of cascades can therefore be determined and heterogeneous amorphization models can be implemented. (orig.).

Energy Technology Data Exchange (ETDEWEB)

This report presents a probabilistic safety assessment of radioactive doses as consequences from accident scenarios to complement the deterministic assessment presented in the Waste Isolation Pilot Plant (WIPP) Safety Analysis Report (SAR). The International Council of Radiation Protection (ICRP) recommends both assessments be conducted to ensure that ''an adequate level of safety has been achieved and that no major contributors to risk are overlooked'' (ICRP 1993). To that end, the probabilistic assessment for the WIPP accident scenarios addresses the wide range of assumptions, e.g. the range of values representing the radioactive source of an accident, that could possibly have been overlooked by the SAR. Routine releases of radionuclides from the WIPP repository to the environment during the waste emplacement operations are expected to be essentially zero. In contrast, potential accidental releases from postulated accident ...

International Nuclear Information System (INIS)

Purpose: Various published reports involving intensity-modulated radiotherapy (IMRT) plans developed using automated optimization (inverse planning) have demonstrated highly conformal plans. These reported conformal IMRT plans involve significant target dose inhomogeneity, including both overdosage and underdosage within the target volume. In this study, we demonstrate the development of optimized beamlet IMRT plans that satisfy rigorous dose homogeneity requirements for all target volumes (e.g., #+-#5%), while also sparing the parotids and other normal structures. Methods and Materials: The treatment plans of 15 patients with oropharyngeal cancer who were previously treated with forward-planned multisegmental IMRT were planned again using an automated optimization system developed in-house. The optimization system allows for variable sized beamlets computed using a three-dimensional convolution/superposition dose ...

International Nuclear Information System (INIS)

This work describes an experimental verification of the two-photon dose calculation engines available on the Helax-TMS (version 6.1) commercial radiotherapy treatment planning system. The performance of the pencil beam convolution and the collapsed cone superposition algorithms was examined for 4, 6, 15 MV beams, under a range of clinically relevant irradiation geometries. Comparisons against measurements were carried out in terms of absolute dose, thus assessment of the accuracy of monitor unit (MU) calculations was also carried out. Results show that both algorithms agree with measurement to acceptable tolerance levels in most cases in homogeneous water-equivalent media irradiated under full scatter conditions. The collapsed cone algorithm slightly overestimates the penumbra width and this is mainly due to discretization effects of the fluence matrix. The accuracy of this algorithm strongly depends on ...

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The number of multislice CT (MSCT) scans performed in polytraumatized children has increased rapidly. There is growing concern regarding the radiation dose in MSCT and its long-term consequences, especially in children. To determine the effective dose to polytraumatized children who undergo whole-body MSCT. A total of 51 traumatized children aged 0-16 years underwent a polytrauma protocol CT scan between November 2004 and August 2006 at our institution. The effective dose was calculated retrospectively by a computer program (CT-Expo 1.5, Hannover, Germany). The mean effective dose was 20.8 mSv (range 8.6-48.9 mSv, SD{+-}7.9 mSv). There was no statistically significant difference in the effective dose between male and female patients. Whole-body MSCT is a superior diagnostic tool in polytraumatized children with 20.8 mSv per patient being a justified mean ...

International Nuclear Information System (INIS)

The necessity of the electron beam machine characterization via dose measurement is discussed. It includes a measurement of comprehensive dose distribution (at known X and Z axis) for verification of the machine performance. The acquired data were then used to develop the irradiation parameters such as energy, current, distance, conveyor speed, exposure rate and depth inside product to be irradiated. These parameters will be used as a guide for the routine irradiations. (Author)

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The interaction between a lower hybrid wave and a fusion alpha particle displaces the alpha particle simultaneously in space and energy. This results in coupled diffusion. Diffusion of alphas down the density gradient could lead to their transferring energy to the wave. This could, in turn, put energy into current drive. Here we calculate numerical solutions for the alpha energy transfer and study a range of conditions that are favourable for wave amplification from alpha energy. We find that it is possible for fusion alpha particles to transfer a large fraction of their energy to the lower hybrid wave. The numerical calculation shows that the net energy transfer is not sensitive to the value of the diffusion coefficient over a wide range of practical values. An extension of this idea, the use of a ...

Energy Technology Data Exchange (ETDEWEB)

The interaction between a lower hybrid wave and a fusion alpha particle displaces the alpha particle simultaneously in space and energy. This results in coupled diffusion. Diffusion of alphas down the density gradient could lead to their transferring energy to the wave. This could, in turn, put energy into current drive. An initial analytic study was done by Fisch and Rax. Here the authors calculate numerical solutions for the alpha energy transfer and study a range of conditions that are favorable for wave amplification from alpha energy. They find that it is possible for fusion alpha particles to transfer a large fraction of their energy to the lower hybrid wave. The numerical calculation shows that the net energy transfer is not sensitive to the value of the diffusion coefficient over a wide range ...

British Library Electronic Table of Contents (United Kingdom)

The adhesion strength of polybutylene terephthalate (PBT) on aluminum was investigated using density functional theory-based total energy calculations. Aluminum atom was connected to a PBT monomer at different orientations and total energies were calculated in order to determine the most stable orientation. The energy differences showed that the Al oriented at 180degree with the ester group of the monomer bonded strongly. Using this orientation, the PBT monomer-adhesion on aluminum surface and the aluminum atom adhesion on PBT bulk were also investigated.

International Nuclear Information System (INIS)

Based on the single-particle levels given by Nilsson, the intrinsic and effective (with collective effects) level density parameters as a function of the excitation energy for the "1"8"6Os, "1'8"7Ir, "1"8"9Os and "1"9"3Au deformation nuclei have been calculated in the range of the excitation energy up to 150 MeV. The calculated fission probabilities P_f (U) are consistent satisfactorily with the experimental data when a nonadiabatic estimation of the collective effects was used to calculated the nuclear level density parameters.

International Nuclear Information System (INIS)

1982. p. 4.3-4.6. Israel Eisen, Y. Engler, G. Ovadia, E. Shamai, Y. Israel

International Nuclear Information System (INIS)

Objective: To estimate exposure dose of personnel around patients by Monte Carlo method and integration method. Methods: Exposures were estimated by a Monte Carlo practical program with Visual Basic 6.0 and integration method using 'pen-and-paper'. Results: Exposures for rectangle and ellipse sources were calculated. The difference between different methods for various sources were 0.88% and 0.61%, respectively. Conclusion: The results estimated by Monte Carlo method are close to those of integration method. It is illustrated that doses of other people estimated by Monte Carlo method are significant

International Nuclear Information System (INIS)

The CyberKnife Robotic Radiosurgery System (Accuracy Incorporated, Sunnyvale, CA, USA) is used worldwide to treat tumors and neurological disorders anywhere in the body with sub-millimetre beam delivery accuracy. Accuracy has developed a number of new technologies in recent years to enhance the treatment of cancer patients. Such new technologies include a fast Monte Carlo Dose Calculation algorithm, Sequential Optimization dose planning, the IrisTM Variable Aperture Collimator, an 800 MU/min Linear Accelerator, and Optimized Path Traversal. These technologies enable physicists and physicians to plan treatments quickly and easily and deliver them with unrivalled accuracy and precision

International Nuclear Information System (INIS)

In this work, we investigate the interstitial injection into the silicon lattice due to high-dose, low-energy arsenic implantation. The approach consists in monitoring the diffusion of the arsenic profile as well as of the boron profile in buried #delta#-doped layers, when amounts of the as-implanted arsenic profile are removed by low-temperature wet silicon etching. The experimental results indicate that the contribution of the implantation damage to the transient enhanced diffusion of boron, and thus the interstitial injection, is not the main one. On the contrary, interstitial generation due to arsenic clustering seems to be more important for the present conditions.

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The LAHET code system calculations and experimental results for proton interactions with an energy <50 MeV are compared. For these energies, the theories behind the LAHET models are not applicable. Three quantities compared are (a) the magnitude of the neutron yield generated through proton interactions, (b) the energy and angular distributions of the resultant neutrons, and (c) the residual nuclei produced by proton interactions (spallation products). The comparisons are for protons incident on iron and copper, except in the case of the energy and angular distributions, which are calculated only for iron. The neutron yields predicted by LAHET agree with published measurements to within 50% for both materials. For iron, the predicted energy and angular distributions agree to within a factor of 3. Finally, the predicted spallation product ...

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Nuclear reaction cross-sections for stable strontium and cesium isotopes, which were calculated by different approaches, are compared to available experimental data. Neutron and proton induced reaction cross-sections for the long-lived radionuclides [sup 90]Sr and [sup 137]Cs have been calculated in the energy range from 1 MeV to 10 GeV. Recommendations concerning cross-section calculations for strontium and cesium isotopes at intermediate and high energies are given. (orig.)

International Nuclear Information System (INIS)

The High Flux Isotope Reactor (HFIR) located at Oak Ridge National Laboratory is one of the world's most powerful research reactors. In 1996, one year after the demise of the Advanced Neutron Source Project, the U.S. Department of Energy embarked on an aggressive program to upgrade the neutron scattering facilities at the HFIR. These upgrades, which are now in progress, include the installation of larger beam tubes, a high-performance hydrogen cold source, and additional neutron guides and neutron scattering instruments. An extensive analysis effort was performed over the past 4 yr to support the design of the modified beamlines and new user facilities and to assess the impact of the upgrades on the integrity of the existing reactor system. The results of three of these analyses are summarized here. Specifically, results are presented for analyses related to the design of the new cold neutron source (CNS), the assessment of beam tube changes on the anticipated ...

International Nuclear Information System (INIS)

For the purpose of risk estimates from radiation carcinogenesis including leukemogenesis and radiation genetic effects, the biological significant dose is not the tissue kerma in air but the absorbed dose in organ or tissue with respect to carcinogenic and leukemogenic effects or genetic effects. In order to estimate organ or tissue dose from the tissue kerma in air, a ratio of the organ or tissue dose to the tissue kerma in air for survivors in Hiroshima and Nagasaki was calculated with the aid of the Snyder's mathematical phantoms constructed so as to simulate the body shape of survivors aged 5, 10 years old and adult at the time of atomic bomb detonations. The ratios were corrected for the angular distribution of atomic bomb radiations, assuming an anisotropic angular distribution for the survivors exposed to the atomic bombs in open air and the isotropic distribution for the ...

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To assess the internal dose by {sup 3}H and {sup 14}C in total diet of inhabitants near Wolsung nuclear power plants, TFWT, OBT and {sup 14}C concentration in total diet was analyzed for collection region and time. TFWT, OBT and {sup 14}C concentrations were in the range of 3.19-42.2 Bq/L, 1.00-39.4 Bq/L, and 0.230-0.856 Bq/gC, respectively. The calculated annual effective dose with TFWT, OBT and {sup 14}C is 6.10 x 10{sup -5} mSv/y, 3.71 x 10{sup -5} mSv/y and 7.08 x 10{sup -3} mSv/y, respectively. And then annual internal dose with total diet for inhabitants near Wolsung NPPs is about 7.18 x 10{sup -3} mSv/y, which is about 0.72% of annual effective dose limit 1 mSv/y.

International Nuclear Information System (INIS)

To assess the internal dose by "3H and "1"4C in total diet of inhabitants near Wolsung nuclear power plants, TFWT, OBT and "1"4C concentration in total diet was analyzed for collection region and time. TFWT, OBT and "1"4C concentrations were in the range of 3.19-42.2 Bq/L, 1.00-39.4 Bq/L, and 0.230-0.856 Bq/gC, respectively. The calculated annual effective dose with TFWT, OBT and "1"4C is 6.10 x 10"-"5 mSv/y, 3.71 x 10"-"5 mSv/y and 7.08 x 10"-"3 mSv/y, respectively. And then annual internal dose with total diet for inhabitants near Wolsung NPPs is about 7.18 x 10"-"3 mSv/y, which is about 0.72% of annual effective dose limit 1 mSv/y.

International Nuclear Information System (INIS)

Awaiting new data from RERF, an attempt was made to estimate the somatic risks of low doses of radiation for members of the German public. The new estimate follows closely the approach used in deriving the values published in the NIH Radioepidemiological Tables. The lifetime risk factors thus calculated are significantly larger than the estimates presented in ICRP Report 26 and are consistent with estimates recently made in the ongoing reactor safety study of NUREG. The increase in lifetime risks is mainly due to the introduction of a new time projection model which appears to be more consistent with the epidemiological data for many late effect end points than the constant absolute risk model previously employed. Results from a study in which epidemiological data were stochastically simulated with a computer indicate that the shapes of actual dose effect curves might be significantly more influenced by pure chance than by ...

Science.gov (United States)

The article explains the method of selecting the optimum energy for correcting the energy selectivity of tomographic projection and the optimum length of the crystals corresponding to it when the dual energy method in computerized tomography is used. Results of numerical calculations for actual materials and count results are presented.

Energy Technology Data Exchange (ETDEWEB)

For charged particle irradiations, the response of an imaging plate (IP) changes around the Bragg peak. Therefore, an appropriate compensation is necessary for the evaluation of dose distribution formed by charged particles such as protons. In this paper, the response of IPs to clinical proton beams is investigated. An experimentally-obtained depth-dose distribution (an ordinary Bragg curve) by a silicon semiconductor detector (SSD) is employed to evaluate the compensation factors as a function of proton penetrating depth, i.e. residual range. A typical dose distribution in a water phantom formed by an L-shaped bolus is measured by IPs and corrected by using the information of those compensation factors; the residual proton range is successfully calculated by the pencil beam algorithm at an arbitrary point. The results show a good agreement with the measurements by the SSD within the rms error of 3.0%.

International Nuclear Information System (INIS)

Monte Carlo simulation of beam modifiers such as physical wedges and compensating filters has been performed with a rectilinear voxel geometry module. A modified version of the EGS4/DOSXYZ code has been developed for this purpose. The new implementations have been validated against the BEAM Monte Carlo code using its standard component modules (CMs) in several geometrical conditions. No significant disagreements were found within the statistical errors of 0.5% for photons and 2% for electrons. The clinical applicability and flexibility of the new version of the code has been assessed through an extensive verification versus dosimetric data. Both Varian multi-leaf collimator (MLC) wedges and standard wedges have been simulated and compared against experiments for 6 MV photon beams and different field sizes. Good agreement was found between calculated and measured depth doses and lateral dose profiles along both wedged and ...

International Nuclear Information System (INIS)

The advent of multislice spiral CT (MSCT) technique has led to new aspects of dose reduction, especially for the dedicated use of MSCT in children. Optimizing pediatric MSCT protocols according to the clinical problem allows reduction of radiation exposure to a minimum without loss of diagnostic quality. The different parameters that influence the degree of dose reduction, like tube current-time product (mAs), tube voltage (kV), collimation and pitch, are discussed in context with previously published data and our own experience in nearly 200 pediatric CT examinations. In our department, the effective mAs is calculated for a pediatric chest MSCT by multiplication of the body weight in kilogram with a factor of 1 to 1.5 and for a pediatric abdominal MSCT by multiplication with a factor of 2 to 2.5. To calculate the equivalent effective dose for a contrast media-enhanced 80 kV ...

International Nuclear Information System (INIS)

In this work an analysis of the influence of the choice of the algorithm or planning system, on the calculus of the same treatment plan is introduced. For this purpose specific software has been developed for comparing plans of a series of IMRT cases of prostate and head and neck cancer calculated using the convolution, superposition and fast superposition algorithms implemented in the XiO 4.40 planning system (CMS). It has also been used for the comparison of the same treatment plan for lung pathology calculated in XiO with the mentioned algorithms, and calculated in the Plan 4.1 planning system (Brainlab) using its pencil beam algorithm. Differences in dose among the treatment plans have been quantified using a set of metrics. The recommendation for the dosimetrist of a careful choice of the algorithm has been numerically confirmed. (Author).

International Nuclear Information System (INIS)

Operations at the Savannah River Site (SRS) result in releases of small amounts of radioactive materials to the atmosphere and to the Savannah River. For regulatory compliance purposes, potential offsite radiological doses are estimated annually using computer models that follow U.S. Nuclear Regulatory Commission (NRC) Regulatory Guides. Within the regulatory guides, default values are provided for many of the dose model parameters but the use of site-specific values by the applicant is encouraged. A detailed survey of land and water use parameters was conducted in 1991 and is being updated here. These parameters include local characteristics of meat, milk and vegetable production; river recreational activities; and meat, milk and vegetable consumption rates as well as other human usage parameters required in the SRS dosimetry models. In addition, the preferred elemental bioaccumulation factors and transfer factors to be used in human health ...

Science.gov (United States)

Rapid administration of stable iodine is essential for the saturation and subsequent protection of the thyroid gland against the potential harm caused by radioiodines. This paper proposes the Dutch risk analysis that uses an atmospheric dispersion model to calculate the size of the zones around nuclear power plants where radiological thyroid doses for children might be sufficiently high to warrant iodine administration. Dose calculations for possible releases from the nuclear power plants of Borssele (The Netherlands), Doel (Belgium) and Emsland (Germany) are based on two scenarios in combination with a 1-y set of authentic, high-resolution meteorological data. The dimensions of the circular zones were defined for each nuclear power plant. In these zones, with a radius up to 50 km, distribution of stable iodine tablets is advised. PMID:20332130

British Library Electronic Table of Contents (United Kingdom)

Purpose: In this paper, we present an alternative to the originally proposed technique for the delivery of spatially fractionated radiation therapy (GRID) using multi-leaf collimator (MLC) shaped fields. We employ the MLC to deliver various pattern GRID treatments to large solid tumors and dosimetrically characterize the GRID fields. Methods and materials: The GRID fields were created with different open to blocked area ratios and with variable separation between the openings using a MLC. GRID designs were introduced into the Pinnacle3 treatment planning system, and the dose was calculated in a water phantom. Ionization chamber and film measurements using both Kodak EDR2 and Gafchromic EBT film were performed in a SolidWater phantom to determine the relative output of each GRID design as w...

International Nuclear Information System (INIS)

The paper introduces the disposal procedures of the old reactor pressure vessel head. Reactor pressure vessel (RPV) heads were replaced successfully in Daya Bay Nuclear Power Plant. The on-site treatment and disposal of replaced heads was thereafter implemented. This is the first time in China for large size radioactive article disposal. To guarantee the safety of old head treatment, issues of radiation protection have to be taken into account. Dose rate distribution of the old head surface and radioactivity were initially calculated according to the operation history and the neutron flux rate of the reactor. Shielding calculation and package design was thereafter worked out based on the data obtained from the old head, e.g. neutron flux, sorts of nuclides, radioactivity and dose rates. Shielding package was afterwards manufactured in special factories and transported to Daya Bay NPP site by truck and ...

UK PubMed Central (United Kingdom)

The minimum energy conformations of dApdA have been examined for their suitability as buildings blocks of the single stranded coil form of polynucleotides. Calculations of the characteristic ratio C...Full Text Available

International Nuclear Information System (INIS)

The structural, electronic and optical properties of ZnX and CdX (X = Se, Te and S) are studied using density functional theory by the Wien2k package. The energy band gap, real and imaginary parts of the dielectric function, energy loss function, optical absorption coefficient and reflectivity spectra of these compounds are calculated. The Engel-Vosko approach improves the energy band gaps of ZnX and CdX compounds. The calculated optical parameters are in good agreement with available experimental results, particularly in the Engel-Vosko approach. Furthermore the effect of hydrostatic pressure on the energy band gap, the real and imaginary parts of the dielectric function of these compounds is studied. The first and second order pressure coefficient for the energy band gaps, the static dielectric function and the static reflectivity spectra ...

Energy Technology Data Exchange (ETDEWEB)

In the case of a serious accident and as a precautionary measure, several protection actions can be implemented by the prefect during the emergency phase. In France the levels of intervention are given by a ministerial decree of the 13. october 2003, resuming recommendations of the International Atomic Energy Agency. The selected values are: an efficient dose of 10 mSv for the stake under cover and in the listening: the concerned persons have to put under cover in a building, any openings carefully closed and stay in the listening of the orders of the prefect; an efficient dose of 50 mSv for evacuation; an efficient dose to the thyroid of 100 mSv for the taking of stable iodine tablets. In order to help the authorities to choose between the keeping of populations at their place or immediate evacuation the decision criteria are: if the forecasted efficient dose of the first month is ...

International Nuclear Information System (INIS)

We have studied in detail the gamma radiation induced changes in the electrical properties of the (TeO_2)_0_._9 (In_2O_3)_0 _._1 thin films of different thicknesses, prepared by thermal evaporation in vacuum. The current-voltage characteristics for the as-deposited and exposed thin films were analysed to obtain current versus dose plots at different applied voltages. These plots clearly show that the current increases quite linearly with the radiation dose over a wide range and that the range of doses is higher for the thicker films. Beyond certain dose (a quantity dependent on the film thickness), however, the current has been observed to decrease. In order to understand the dose dependence of the current, we analysed the optical absorption spectra for the as-deposited and exposed thin films to obtain the dose dependences of the optical bandgap and ...

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Equations are derived to calculate the work required for the isentropic compression of a 2-phase fuel-air mixture. Methanol evaporation during compression substantially reduces compression work and improves cycle efficiency and maximum power. Effects of evaporative cooling in the intake manifold are calculated. Energy d. of methanol and gasoline fuel-air charges are compared. The phase equilibrium and evaporation rate are causes of the poor cold-starting performance of methanol.

International Nuclear Information System (INIS)

Li shell-model calculation has been made in the isospin formalism in the complete (0 + n)#Planck constant##omega# model space with the assumption of a closed core "4He. The calculation could probably be improved by use of a better effective interaction and increasing shell model space. With the use of faster computer with large memories, the authors are in hope of calculation in spsd shell-model space

Science.gov (United States)

We describe calculations of the energy loss, range, stopping power, multiple scattering, and other related properties of a high-energy heavy-ion beam at any one of a set of beam line elements. A beam line element (e.g., any beam modification, detection, or control device) is characterized by its thickness, areal density, aperture, and function. The loss of multiply scattered particles to any finite-aperture detector is calculated in the small-angle approximation, and the position of the Bragg peak, as given by particles stopping in the second of two ionization chambers used for Bragg curve measurements, is estimated. A general purpose computer program, PROPAGATE, has been written to allow addition, deletion, and modification of the beam line elements used in the calculation and to provide a convenient means of repeating such calculations for arbitrary beam ...

CERN Document Server

Using the complex Kohn method, we have calculated variational values of phase shifts and the annihilation parameter, Z_{eff}, for the elastic scattering of positrons by molecular hydrogen. Our results are sensitive to small changes in the accuracy of the wave function representing the target hydrogen molecule. We have developed a systematic approach to demonstrate that, at low positron energies, there are particular forms of the Kohn trial wave function for which the results of variational calculations are not reliable, even when the target wave function accounts for as much as 96.8% of the correlation energy of H_{2}. We find that reliable results can be recovered if our calculations are extended to admit more sophisticated target wave functions accounting for 99.7% of the correlation energy. Remaining discrepancies between theory and experiment are briefly ...

International Nuclear Information System (INIS)

Measurements of alpha spectra in the (n, #alpha#) reactions induced on /sup 90,91/Zr at 14.3 and 18.15 MeV incident neutron energy are presented. A microscopic calculation of these spectra has been made using both pick-up and knock-on theories, and in both cases only one overall normalizing factor, which is the same for the two target nuclei and incident energies and all the considered transitions, appears as a free parameter in the calculation. Pick-up calculations provide a very satisfactory reproduction of the data. Knock-on calculations reproduce many qualitative features of the measured spectra, but do not allow a fully satisfactory reproduction of them. While the results obtained do not exclude knock-on contributions to these reactions, their presence is not established.

International Nuclear Information System (INIS)

Purpose: An inverse treatment planning algorithm for tomotherapy is described. Methods and Materials: The algorithm iteratively computes a set of nonnegative beam intensity profiles that minimizes the least-squares residual dose defined in the target and selected normal tissue regions of interest. At each iteration the residual dose distribution is transformed into a set of residual beam profiles using an inversion method derived from filtered backprojection image reconstruction theory. These 'residual' profiles are used to correct the current beam profile estimates resulting in new profile estimates. Adaptive filtering is incorporated into the inversion model so that the gross structure of the dose distribution is optimized during initial iterations of the algorithm, and the fine structure corresponding to edges is obtained at later iterations. A three dimensional, kernel based, convolution/superposition ...

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The strength of adhesion of polybutylene terephthalate (PBT) on aluminium is investigated using density functional theory-based energy calculations. The aluminium atom is connected to a PBT monomer at different orientations, and total energies are calculated and compared to determine the most stable orientation. The binding is strongest when the Al is oriented at 180{sup 0} to the ester group of the monomer. Using this orientation as a basis, PBT adhesion on Ti, Ag, and Au is also investigated.

International Nuclear Information System (INIS)

The electronic structure of octahedral metal atom clusters Me_6 of 3d, 4d, and 5d transition metal atoms (V, Cr; Nb, Mo; Ta, W) has been calculated applying two different quantum-chemical approximation methods (Extended Hueckel (EH) method; SW-Xsub(alpha) method). Equilibrium structures, energy level schemes, Fermi energies and band widths as well as densities of states of clusters are discussed in detail.

International Nuclear Information System (INIS)

From the frequency of diagnostic radiologic examinations and their radiation dose delivered to the population the risk of cancer induction and genetic damage is calculated on the basis of the risk factors given by the ICRP. Thus 0.38 % and 3 % of the total mortality for cancer and leukemia, resp., can be attributed to X-ray diagnostics. Chest examinations alone result in 0.07-0.7 damages per 100,000 persons depending on the imaging technique applied. (author).

International Nuclear Information System (INIS)

Brachytherapy is used for treating certain types of cancer by inserting radioactive sources into tumours. CDTN/CNEN is developing brachytherapy seeds to be used mainly in prostate cancer treatment. Dose calculations play a very significant role in the characterization of the developed seeds. The current state-of-the-art of computation dosimetry relies on Monte Carlo methods using, for instance, MCNP codes. However, deterministic calculations have some advantages, as, for example, short computer time to find solutions. This paper presents a software developed to calculate doses in a two-dimensional space surrounding the seed, using a deterministic algorithm. The analysed seeds consist of capsules similar to IMC6711 (OncoSeed), that are commercially available. The exposure rates and absorbed doses are computed using the Sievert integral and the Meisberger third ...

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Plutonium-containing compounds vary widely in isotopic content, and as a result, the dose as function of isotopic content also varies considerably. Determination of the dose from neutrons, decay and capture gammas from plutonium in the form of compounds thus requires that the spontaneous fission and ({alpha},n) source and spectra from each individual isotope be known. To facilitate dose calculations from plutonium-containing compounds, we have calculated the spontaneous fission and ({alpha},n) sources and spectra for 1 g of each of the plutonium isotopes in the form of either PuF{sub 4} or PuO{sub 2}. As {sup 241}Am is often a component in a mixture of plutonium isotopic compounds, the source and spectra from 1 g of {sup 241}Am mixed with PuF{sub 4} or PuO{sub 2} has also been determined. Using these results, the neutron source and spectra may be determined for any sample ...

International Nuclear Information System (INIS)

The Atomic Energy Control Board (AECB), Canada's nuclear regulatory authority, is preparing new regulations based on ICRP-60. The proposed regulations have some features which are different from ICRP-60, e.g., the limit for pregnant workers was set at a higher level than that proposed in ICRP-60. The AECB, through its consultative process, received many responses from female staff in nuclear medicine. The concern was that it would be very difficult to prove compliance with such low doses, particularly for internal doses. There was an additional concern that hospital administrators would respond to the reduction of the current pregnant worker limit from 10 mSv to the ICRP-60 recommended value of 2 mSv by discriminating against hiring women. A new proposal for the dose limit for pregnant workers has been made which will limit the dose to the mother by means of a combining formula that ...

International Nuclear Information System (INIS)

The neutron capture cross sections of "2"4"1Am and "2"4"3Am to the ground and isomeric states of "2"4"2Am and "2"4"4Am have been calculated using the Hauser-Feshbach statistical theory of nuclear reactions for energies from thermal to 2 MeV. The parameters for the calculations were obtained from recent data on ("2"4"1Am + n) and ("2"4"3Am + n) or, where necessary, from systematics of actinide nuclei. The calculated values are in good agreement with the sparse experimental data.

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This paper describes a functional slide rule that provides a readily usable ?in-hand? method for estimating nuclear criticality accident information from sliding graphs, thereby permitting (1) the rapid estimation of pertinent criticality accident information without laborious or sophisticated calculations in a nuclear criticality emergency situation, (2) the appraisal of potential fission yields and external personnel radiation exposures for facility safety analyses, and (3) a technical basis for emergency preparedness and training programs at nonreactor nuclear facilities. The slide rule permits the estimation of neutron and gamma dose rates and integrated doses based upon estimated fission yields, distance from the fission source, and time-after criticality accidents for five different critical systems. Another sliding graph permits the estimation of critical solution fission yields based upon fissile material ...

International Nuclear Information System (INIS)

The purpose of the study was to optimise the technique employed for AP shoulder and lateral cervical spine examinations following an investigation into image quality, based on clinical assessment, and effective dose, calculated from patient entrance surface dose measurements. A study was therefore conducted in an attempt to determine whether the increased radiation dose to the patient following the introduction of an anti-scatter grid was justified by the level of improvement in image quality. The study, involving 100 patients, was able to demonstrate that the increase in radiation dose to the patient when using an anti-scatter grid for AP shoulder examinations is not justified by the improved image quality. A poor level of inter-rater reliability between the consultants scoring the lateral cervical spine images prevented a firm conclusion from being reached. The fact that all ...

International Nuclear Information System (INIS)

The problems of radioimmunoassay data processing with a fairly big computer are investigated in detail. The logit transformation, introduced by Rodbard et al. in 1968, and the related mathematical operations are presented. From logit-ln plots the confidence limits for the calculation of the antigen concentration can be predicted as well as the minimum detectable dose (i.e. the sensitivity of the assay). The Scatchard plot is used to calculate the equilibrium constant of the antigen-antibody coupling reaction and the binding capacity. A 4-parameter logistic curve fitting method is developed and combined with a method to carry out a multi-component Scatchard analysis. Both a weighted and an unweighted linear regression procedure are evaluated for use in calculating the plasma renin activity from the angiotensin I amounts determined by radioimmunoassay. Improvements for Rodbard's computer programmes are ...

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 by a factor of five ...

Energy Technology Data Exchange (ETDEWEB)

For the purpose of optimizing the process of co-implantation of MeV Si ions to reduce boron transient enhanced diffusion and boron-enhanced diffusion in Si, multiple MeV implantations and annealing at different temperatures have been performed. A slight improvement on the suppression of B diffusion is observed by adding a low temperature annealing step after the MeV implantation. No differences in B diffusion are observed when the Si doses are increased from 1 x 10{sup 15} to 1 x 10{sup 16} cm{sup -2}. This dose independent behavior is speculated to be a quasi-steady state of vacancy cluster evaporation.

Energy Technology Data Exchange (ETDEWEB)

A significant amount of X-rays were detected as a leakage from some of the Crooke`s tubes which were used in the teaching of science at junior and senior high schools in Japan. We measured the leaked dose of X-rays from the Crooke`s tubes with ionizing chambers, film badges and TLDs. The maximum leaked dose at 5cm distance from those tubes was estimated 143mSv/h. The effective energy of leaked X-rays was 19.3keV. The maximum dose of students exposed during the teaching of science were estimated 0.15mSv per experiment, which exceeded the value recommended in the ICRP publication 36. (author)

Energy Technology Data Exchange (ETDEWEB)

Subcutaneous involvement frequently occurs in maxillary sinus carcinoma. Radical resection does not include removal of the skin at risk. In standard postoperative wedge-pair treatment plans, the surface dose is dependent upon beam weighting, beam energy, and patient contour. Thermoluminescent dosimetry (TLD) measurements were performed to evaluate the surface dose of patients undergoing postoperative irradiation of maxillary sinus carcinoma following primary resection. When 60 Gy was delivered to isocenter with a 45 degrees wedge pair and 6 MV photons with 1 cm bolus, the subcutaneous tissues at risk received {approximately} 30 Gy. Based upon presented TLD measurements, supplemental electron beam therapy to the subcutaneous tissues if primarily involved should be considered.

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 former has been known to be superior to the latter for complex geometry problem. However, Monte Carlo method had not been used for radiation ...

Energy Technology Data Exchange (ETDEWEB)

The United States Department of Energy (U.S. DOE) has recently implemented a series of strategic initiatives to address long-term radiological surveillance needs at former U.S. nuclear test sites in the Marshall Islands. The plan is to engage local atoll communities in developing shared responsibilities for implementing radiation protection monitoring programs for resettled and resettling populations in the northern Marshall Islands. Using the pooled resources of the U.S. DOE and local atoll governments, individual radiological surveillance programs have been developed in whole body counting and plutonium urinalysis in order to accurately assess radiation doses resulting from the ingestion and uptake of fallout radionuclides contained in locally grown foods. Permanent whole body counting facilities have been established at three separate locations in the Marshall Islands including Rongelap Atoll (Figure 1). These facilities are operated and ...

Energy Technology Data Exchange (ETDEWEB)

This paper presents a new method for the determination of the energy gap of superconductors. The V/sub max//kT versus ..delta../kT curve was calculated from tunneling theory. The maximum voltage in differential conductance V/sub max/ was measured from the electron tunneling spectrum. From V/sub max//kT and the curve, one can easily calculate the energy gap value ..delta... This method is simple, and the accuracy almost approaches that of the curve-fitting method.

Energy Technology Data Exchange (ETDEWEB)

A new method for determining the energy gap of a superconductor using the maximum in the differential conductance curve of electron tunneling spectrum is given in this paper. The V/sub max//kT versus ..delta../kT curve was calculated from tunneling theory. V/sub max/, the voltage of the conductance maximum, can be measured from electron tunneling spectrum. ..delta../kT can be found from this curve, then the energy gap ..delta.. can be calculated. This method is simple, fast and accurate. The accuracy almost approaches that of the curve fitting method.

International Nuclear Information System (INIS)

The formation of the ions charge and energy distributions of the ions slowed down or randomly changing their charge in the collisions with the medium particles are studied. The effect of the ions dispersion by the charge on the Bragg curve form is investigated. The proposed diffusion approximation for the heavy ions kinetic equation makes it possible to determine simply the parameters of the ions distribution by charge and energy on the whole way of the ions motion. The relation between the ions charge distribution characteristics and the cross sections of the ionization-recombination processes is indicated. The ions distributions, calculated in the proposed analytical model, are compared with the results of the numerical calculations. Good agreement between the analytical, numerical and experimental results is obtained

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The electromagnetic field due to an air explosion is here studied: neutron and the gamma-rays, generated by neutronic reactions, deposit energy which ionizes atmosphere; recoil electrons are also created by gamma collisions. This data set allows to solve the Maxwell equations which manage the electromagnetic field. The TRIPOLI-2 code studies the coupled neutron-gamma transport in 3D- geometries by the Monte Carlo method. The code has been modified to calculate the photon energy deposited in matter and the recoil electron current created by Compton effect. The method is tested wiht a simple case; then neutron and gamma transport is studied in air kerma, deposited photon energy, electron current are calculated as functions of space and time and the contributions of the different neutronic reactions are separately evaluated. The calculations presented here are only ...

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In the convolution/superposition method of photon beam dose calculations, inhomogeneities are usually handled by using some form of scaling involving the relative electron densities of the inhomogeneities. In this paper the accuracy of density scaling as applied to primary electrons generated in photon interactions is examined. Monte Carlo calculations are compared with density scaling calculations for air and cork slab inhomogeneities. For individual primary photon kernels as well as for photon interactions restricted to a thin layer, the results can differ significantly, by up to 50%, between the two calculations. However, for realistic photon beams where interactions occur throughout the whole irradiated volume, the discrepancies are much less severe. The discrepancies for the kernel calculation are attributed to the scattering characteristics of the ...

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The influence of high energy electron (23 MeV) irradiation on the electrical characteristics of p-channel polysilicon thin film transistors (PSTFTs) was studied. The channel 220 nm thick LPCVD (low pressure chemical vapor deposition) deposited polysilicon layer was phosphorus doped by ion implantation. A 45 nm thick, thermally grown, SiO_2 layer served as gate dielectric. A self-alignment technology for boron doping of the source and drain regions was used. 200 nm thick polysilicon film was deposited as a gate electrode. The obtained p-channel PSTFTs were irradiated with different high energy electron doses. Leakage currents through the gate oxide and transfer characteristics of the transistors were measured. A software model describing the field enhancement and the non-uniform current distribution at textured polysilicon/oxide interface was developed. In order to assess the irradiation-stimulated changes of gate oxide ...

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An estimate of the tritium dose to the public in the vicinity of the heavy water research reactor facility at AECL-Chalk River Laboratories, Ontario, Canada, has largely been accomplished from analyses on regularly-collected samples of air, precipitation, drinking water and foodstuffs (pasture, fruit, vegetables and milk) and environmental dose models. To increase the confidence with which public doses are calculated, tritium doses were estimated directly from the ratio of tritiated species in urine samples from members of the general public. Single cumulative 24 h urine samples from a few adults living in the vicinity of the heavy-water research reactor facility at Chalk River Laboratories, Canada were collected and analysed for tritiated water and organically bound tritium. The participants were from Ottawa (200 km east), Deep River (10 km west) and Chalk River Laboratories. ...

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The Anisotropic Analytical Algorithm (AAA) is a new pencil beam convolution/superposition algorithm proposed by Varian for photon dose calculations. The configuration of AAA depends on linear accelerator design and specifications. The purpose of this study was to investigate the accuracy of AAA for an Elekta SL25 linear accelerator for small fields and intensity modulated radiation therapy (IMRT) treatments in inhomogeneous media. The accuracy of AAA was evaluated in two studies. First, AAA was compared both with Monte Carlo (MC) and the measurements in an inhomogeneous phantom simulating lung equivalent tissues and bone ribs. The algorithm was tested under lateral electronic disequilibrium conditions, using small fields (2x2 cm"2). Good agreement was generally achieved for depth dose and profiles, with deviations generally below 3% in lung inhomogeneities and below 5% at interfaces. However, the effects of attenuation and ...

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In this work, thermoluminescent dosimeters have been used to measure entrance surface doses (ESDs) of patients undergoing mammographic screening at the University College Hospital, Ibadan, Oyo state. The mean glandular doses (MGDs) were also calculated using the measured ESDs. The results showed that the ESDs ranged from 0.26 mGy to 21.26 mGy for the mediolateral oblique (MLO) views and 0.08 mGy to 5.36 mGy for the craniocaudal (CC) views. The calculated MGD ranged from 0.07 mGy to 3.57 mGy for the MLO views and 0.02 mGy to 0.98 mGy for the CC views. The possible reasons for the large variations in the individual ESD values and MGD values for both views are discussed using patients' data, equipment specific data and the technical parameters used for the examinations. Comparison showed that the mean ESD values and MGD values reported in this work are below published values. The mean of the ...

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This report documents radionuclide air emissions from the Hanford Site in I998 and the resulting effective dose equivalent to the maximally exposed individual (MEI) member of the public. The report has been prepared in accordance with the Code of Federal Regulations, Title 40, Protection of the Environment, Part 61, National Emission Standards for Hazardous Air Pollutants (40 CFR SI), Subpart H, ''National Emission Standards for Emissions of Radionuclides Other than Radon from Department of Energy Facilities,'' and with the Washington Administrative Code Chapter 246-247, Radiation Protection--Air Emissions. The federal regulations in 40 CFR 61, Subpart H; require the measurement and reporting of radionuclides emitted from Department of Energy facilities and the resulting offsite dose from those emissions. A standard of 10 mrem/yr effective dose ...

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Energy conservation and local energy deposition are investigated in the context of coupled-particle (i.e., neutrons, gamma rays, and charged particles) transport analysis. For charged particles, the concept of group splitting the 1 = 0 transfer matrix to ensure both particle and energy conservation is introduced. Although these procedures are more complex than those found in the usual neutron or coupled-neutron gamma-ray problem, they yield a consistent approach for the calculation of local energy deposition.

International Nuclear Information System (INIS)

A cell calculation code SLAROM-UF was developed to improve calculation accuracy of effective cross sections for various fast reactor types. SLAROM-UF has a capability to calculate effective cross sections in ultra fine groups of about 100,000 below 50keV and in fine groups above the energy (maximum 900 groups). Resonance interaction among the fuel, the coolant, and the structure materials can be treated accurately even in a heterogeneous cell structure. Temperature can be set up freely in a cell by the ultra fine group calculation. Improvement in nuclear characteristics was observed in the analysis of JUPITER critical experiment, as 0.1% for criticality, 4% for sodium void reactivity, several % for radial reaction rate distribution, when SLAROM-UF was used instead of the typical cell calculation code. The effect of the ultra fine group ...

International Nuclear Information System (INIS)

Using high-resolution y-rays spectrometry, the natural radioactivity of 14 samples of natural and o manufactured Egyptian building materials have been investigated. The samples were collected from local market and construction sites. From the measured gamma-ray spectra, specific activities were determined. The radium equivalent activity in each sample was estimated. Radiological evaluations of these materials indicate that all materials meet the external gamma-ray dose limitation. Calculation of concentration indices by assuming a Markkanen room model is constructed from these materials, to find the excess gamma-ray dose taken over that received from the outdoors. The Austrian Standard ONORM S 5200 is used in testing the building 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)

We present results of multiple-time-scale simulations of 5, 10 and 15 keV low temperature ion implantation of arsenic on silicon (100), followed by high temperature anneals. The simulations start with a molecular dynamics (MD) calculation of the primary state of damage after 10ps. The results are then coupled to a kinetic Monte Carlo (MC) simulation of bulk defect diffusion and clustering. Dose accumulation is achieved considering that at low temperatures the damage produced in the lattice is stable. After the desired dose is accumulated, the system is annealed at 800 degrees C for several seconds. The results provide information on the evolution for the damage microstructure over macroscopic length and time scales and affords direct comparison to experimental results. We discuss the database of inputs to the MC model and how it affects the diffusion process.