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JAEA Reports

Development of database of dose reduction factor for reducing equivalent doses to the thyroid by implementing iodine thyroid blocking (Contract research)

Kimura, Masanori; Munakata, Masahiro; Hato, Shinji*; Kanno, Mitsuhiro*

JAEA-Data/Code 2020-002, 38 Pages, 2020/03

JAEA-Data-Code-2020-002.pdf:3.23MB

To consider the method of implementing urgent protective actions in a nuclear accident appropriately, the authors have been assessing the effects of reducing doses by taking urgent protective actions using a Level 3 Probabilistic Risk Assessment (PRA) code, the OSCAAR, developed by the JAEA. Iodine thyroid blocking is an effective urgent protective action to reduce equivalent doses to the thyroid due to inhalation of radioactive iodine. However, the timing of the administration of stable iodine (SI) is important to maximize the effectiveness for thyroidal blocking. Therefore, the careful consideration should be given to the most effective way of iodine thyroid blocking when preparing off-site emergency plans. In the present study, the authors developed a new metabolic model for thyroid by combining the respiratory tract model (Publ.66) and gastrointestinal tract model (Publ.30) of the ICRP with a metabolic model for thyroid (Johnson's model) in order to calculate the behavior of radioiodine and stable iodine in the body more realistically. The model is useful to evaluate the effect of the administration of SI for reducing equivalent doses to the thyroid depending on the its timing. We also calculated the reduction factor for equivalent doses to the thyroid in order to the thyroid by using the model, and then developed the its database for the OSCAAR. Consequently, the OSCAAR can evaluate the effectiveness for thyroidal blocking realistically and promptly.

Journal Articles

Improvement of a metabolic model for iodine and consideration of a equivalent dose to the thyroid reduction factor for application to the OSCAAR code

Kimura, Masanori; Hato, Shinji*; Matsubara, Takeshi*; Kanno, Mitsuhiro*; Munakata, Masahiro

Proceedings of Asian Symposium on Risk Assessment and Management 2017 (ASRAM 2017) (USB Flash Drive), 9 Pages, 2017/11

The authors developed a new metabolic model for iodine by combining the respiratory tract model (Publ.66), the gastrointestinal tract model (Publ.30) of the ICRP and the metabolic model for iodine (Johnson's model) in order to evaluate the behavior of radioiodine and stable iodine in the body more realistically. The developed metabolic model indicated that a reduction factor (RF) depends on dosage of stable iodine, timing of the administration of stable iodine, different iodine isotopes ($$^{131}$$I - $$^{135}$$I), and age groups. Therefore, the RF was calculated by changing these parameters and then a database of the RF was constructed for the application to the OSCAAR code.

Journal Articles

Evaluation of effective dose coefficient with variation of absorption fraction in gastrointestinal system for ingestion of radiocesium

Pratama, M. A.; Takahara, Shogo; Hato, Shinji*

Hoken Butsuri, 52(3), p.200 - 209, 2017/09

The purpose of this study is to identify the significance of the change in the intestinal absorption rate values the ($$f_{1}$$ value) to the change of dose coefficient as well as to provide a list of dose coefficients which each of the value corresponds to a specific intestinal absorption rate and age groups. In the range of 0-1, 10 different values of $$f_{1}$$ for 1 year, 5 years old, and adult group were chosen and used in a separate calculation by using, a biokinetic compartment model, DCAL. It was found that the lower values of intestinal absorption rate lead to a significant decrease of the committed effective coefficient for adult. Oppositely for children, the decrease of committed effective coefficient was not as significant. This study also suggests that the significance of dose coefficient change due to the variation of $$f_{1}$$ substantially depends on the biological half-life of the radionuclide and the mass of organs and tissues in human body.

Journal Articles

Estimation of radionuclide intakes by singular value decomposition

Hato, Shinji*; Kinase, Sakae

Nihon Genshiryoku Gakkai Wabun Rombunshi, 15(3), p.146 - 150, 2016/09

Journal Articles

Evaluation of averted doses to members of the public by tap water restrictions after the Fukushima Daiichi Nuclear Power Plant Accident

Kinase, Sakae; Kimura, Masanori; Hato, Shinji*

Progress in Nuclear Science and Technology (Internet), 4, p.5 - 8, 2014/04

Journal Articles

Development of internal dosimetry evaluation code for chronic exposure after intake of radionuclides

Kimura, Masanori; Kinase, Sakae; Hato, Shinji*

Progress in Nuclear Science and Technology (Internet), 4, p.60 - 63, 2014/04

Journal Articles

Evaluation of retention and excretion function to members of the public for chronic intake of radionuclides

Hato, Shinji*; Kinase, Sakae; Kimura, Masanori

Progress in Nuclear Science and Technology (Internet), 4, p.36 - 38, 2014/04

JAEA Reports

Development of internal dosimetry evaluation code for chronic exposure

Kimura, Masanori; Kinase, Sakae; Hato, Shinji*

JAEA-Data/Code 2012-027, 27 Pages, 2013/02

JAEA-Data-Code-2012-027.pdf:2.33MB

The Fukushima Daiichi Nuclear Power Plant accident resulted in a wide range of radioactive contamination. As a result, the public concerns the internal doses for chronic exposure due to intake in daily life. To reduce some concerns, it is important to develop the evaluation method of chronic internal dose. The JAEA developed the DSYS code that calculates internal dose to the public with dose coefficients and treats dose assessment of internal exposure due to acute intake based on the ICRP's Publications (Publ.30, 56, 66, 67, 69, 71, 72). Therefore, it cannot apply to the evaluation of whole-body retention values or committed effective/equivalent dose for chronic exposure. In the present study, the authors considered the evaluation method of chronic internal dose and developed the DSYS-Chronic to evaluate chronic internal dose by incorporating into the DSYS code. This report shows the outline of the DSYS-Chronic code and the example of evaluation results.

Journal Articles

Internal dosimetry for continuous chronic intake of caesium-137 in cedar pollen after the Fukushima Daiichi Nuclear Power Plant accident

Kinase, Sakae; Kimura, Masanori; Hato, Shinji*

Proceedings of International Symposium on Environmental monitoring and dose estimation of residents after accident of TEPCO's Fukushima Daiichi Nuclear Power Station, 4 Pages, 2012/12

JAEA Reports

Verification of atmospheric diffusion models using data of long term atmospheric diffusion experiments

Tamura, Junji*; Kido, Hiroko*; Hato, Shinji; Homma, Toshimitsu

JAEA-Research 2008-103, 94 Pages, 2009/03

JAEA-Research-2008-103.pdf:48.02MB

The plume models are used in probabilistic accident consequence assessment (PCA) codes due to cost and time savings. The PCA code, OSCAAR developed by JAERI (Present; JAEA) uses the puff model to calculate atmospheric transport and dispersion. In order to investigate uncertainties involved with the structure of the atmospheric dispersion/deposition model in OSCAAR, we have introduced the more sophisticated computer codes that included regional meteorological model RAMS and atmospheric transport model HYPACT, and comparative analyses between OSCAAR and RAMS/HYPACT have been performed. In this study, model verification of OSCAAR and RAMS/HYPACT was conducted using data of long term atmospheric diffusion experiments, which were carried out in Tokai-mura, Ibaraki-ken. The predictions by models and the results of the atmospheric diffusion experiments indicated relatively good agreements. And it was shown that model performance of OSCAAR was the same degree as it of RAMS/HYPACT.

JAEA Reports

User's manual of DSYS-GUI; The Calculation system of internal dose coefficients

Hato, Shinji; Terakado, Masato*; Tomita, Kenichi*; Homma, Toshimitsu

JAEA-Data/Code 2008-031, 75 Pages, 2009/03

JAEA-Data-Code-2008-031.pdf:3.73MB

This is the user's manual of DSYS-GUI, which calculates the internal dose coefficients by the models of International Commission on Radiological Protection (ICRP). The DSYS-GUI consists of two programs. One is a program for setting calculation conditions and executing. The other is a program for displaying results to figures and tables. The displaying them are used the Microsoft Excel. Anyone can easily calculate the internal dose coefficients and quickly display results as figures and tables with DSYS-GUI.

JAEA Reports

Verification of atmospheric diffusion models with data of atmospheric diffusion experiments

Hato, Shinji; Homma, Toshimitsu

JAEA-Research 2008-094, 95 Pages, 2009/02

JAEA-Research-2008-094.pdf:11.89MB

The atmospheric diffusion experiments were implemented by Japan Atomic Energy Research Institute (JAERI) around Mount Tsukuba in 1989 and 1990, and the tracer gas concentration were monitored. In this study, the Gauss Plume Model and RAMS/HYPACT that are meteorological forecast code and atmospheric diffusion code with detailed physical law are made a comparison between monitored concentration. In conclusion, the Gauss Plume Model is better than RAM/HYPACT even complex topography if the release is around release point and short estimation. This reason is difference of wind between RAMS and observation.

Journal Articles

Description of human alimentary tract model for radiological protection

Kimura, Masanori; Hato, Shinji

Nihon Hoken Butsuri Gakkai Senmon Kenkyukai Hokokusho Shirizu (Internet), 6(2), p.36 - 42, 2008/04

no abstracts in English

Journal Articles

REIDAC; A Software package for retrospective dose assessment in internal contamination of radionuclides

Kurihara, Osamu; Hato, Shinji; Kanai, Katsuta; Takada, Chie; Takasaki, Koji; Ito, Kimio; Ikeda, Hiroshi*; Oeda, Mikihiro*; Kurosawa, Naohiro*; Fukutsu, Kumiko*; et al.

Journal of Nuclear Science and Technology, 44(10), p.1337 - 1346, 2007/10

 Times Cited Count:0 Percentile:0.01(Nuclear Science & Technology)

In the case of internal contamination of radionuclides, it is necessary to perform internal dose assessment for radiation protection. For this purpose, the ICRP has given the dose coefficients and the retention and excretion rates for various radionuclides. However, these dosimetric quantities are calculated only in typical conditions, therefore, are not necessarily covered enough in the case of dose assessment in which specific information on the incident or/and individual biokinetic characteristics should be taken into account retrospectively. This paper describes a developed PC-based package of software REIDAC to meet the needs in retrospective dose assessment. REIDAC was verified by comparisons with dosimetric quantities given on the ICRP publications and several examples of practical use were also shown.

Journal Articles

Development of internal dose coefficients system

Hato, Shinji; Homma, Toshimitsu

RIST News, (41), p.33 - 41, 2006/05

no abstracts in English

JAEA Reports

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

Hato, Shinji*; Homma, Toshimitsu

JAERI-Data/Code 2005-006, 549 Pages, 2005/09

JAERI-Data-Code-2005-006.pdf:33.24MB

The OSCAAR computer code for use in probabilistic accident consequence assessment (Level3PSA) developed at JAERI has calculated dose to the public with internal dose conversion factors based on dosimetric models and biokinetic data provided in ICRP Publication 30. Since ICRP issued age-dependent biokinetic models for a limited set of radioisotopes as ICRP Publication 56, a new Human Respiratory Tract model, age-dependent biokinetic model for other radioisotopes and urinary and faecal excretion models were issued. ICRP has published age-dependent internal dose coefficients for a large set of radionuclides in its publications, but they provided only committed effective dose coefficients for inhalation and ingestion. Since OSCAAR estimated acute and late health effects for public, it needs internal dose coefficients for specific tissues and organs in arbitrary integration times.This report describes a code DSYS developed for calculating dose coefficients based on these new ICRP models. It also provides the internal dose coefficients for 54 radionuclides used in OSCAAR calculations.

Journal Articles

Uncertainty and sensitivity studies with the probabilistic accident consequence assessment code OSCAAR

Homma, Toshimitsu; Tomita, Kenichi*; Hato, Shinji*

Nuclear Engineering and Technology, 37(3), p.245 - 258, 2005/06

This paper addresses two types of uncertainty: stochastic uncertainty and subjective uncertainty in probabilistic accident consequence assessments. The off-site consequence assessment code OSCAAR has been applied to uncertainty and sensitivity analyses on the individual risks of early fatality and latent cancer fatality in the population due to a severe accident. A new stratified meteorological sampling scheme was successfully implemented into the trajectory model for atmospheric dispersion and the statistical variability of the probability distributions of the consequence was examined. A total of 65 uncertain input parameters was considered and 128 runs of OSCAAR were performed in the parameter uncertainty analysis. The study provided the range of uncertainty for the expected values of individual risks of early and latent cancer fatality close to the site. In the sensitivity analyses, the correlation/regression measures were useful for identifying those input parameters whose uncertainty makes an important contribution to the overall uncertainty for the consequence.

Oral presentation

The Comparison of biokinetic model between the human alimentary tract model of ICRP Publ.100 and the gastrointestinal model of Publ.30

Hato, Shinji; Homma, Toshimitsu

no journal, , 

The international commission on radiological protection (ICRP) was published the human alimentary tract model (HATM) on the ICRP publication 100 (2006). The HATM is a new model replaced the gastrointestinal model of ICRP publication 30. The publication 30 was a model applied to workers, though it's model was applied to public by the f1 value of age dependence. And it's model also did not have the oesophagus. As a result, the HATM was developed for the improvement of their problems and findings since publication 30. Our presentation quantitatively show some difference between two models by simulating retention in organ.

Oral presentation

Derivation of uncertainty parameters by probabilistic inversion; Example of internal dose coefficients

Hato, Shinji; Liu, Q.; Homma, Toshimitsu

no journal, , 

The uncertainty and sensitivity analyses for the probabilistic safety assessment have be researched in the Japan Atomic Energy Agency (JAEA). We produces the uncertainty distributions of the OSCAAR's input parameters with the expert judgments which were produced by the probabilistic accident consequences (level 3PSA) implemented joint of EU and USNRC. The expert judgments are consisted of the subjective probability for physical quantities. These quantities questioned to the experts are either the uncertainty of model's input parameters or the uncertainty of model's output related input parameters. The former can apply to the uncertainty analysis, but the latter is need to transform to uncertainty of input parameter by the probabilistic inversion. Our presentation is that produces the uncertainty distribution of input parameters for internal exposure model as an example.

Oral presentation

Uncertainty and sensitivity analysis of risk assessment models, 3; A Comparison of several uncertainty importance measures for ranking influential input parameters of risk assessment models

Liu, Q.; Homma, Toshimitsu; Hato, Shinji

no journal, , 

When the risk information obtained from the PSA study of nuclear power plants is to be used for safety-related decision making, it is necessary to reduce the uncertainty in the risk. Therefore, it is necessary to identify the influential components that contribute to this uncertainty. In this work, we applied several uncertainty importance measures (including the measures proposed by the authors) to a risk assessment model and ranked the importance of each input parameter. It is found that although the ranking orders of the input parameters with regards to these measures are a bit different, the use of several or more importance measures can increase confidence in the ranking of key input parameters.

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