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Shimada, Taro; Sasagawa, Tsuyoshi; Miwa, Kazuji; Takai, Shizuka; Takeda, Seiji
Proceedings of International Conference on Environmental Remediation and Radioactive Waste Management (ICEM2023) (Internet), 7 Pages, 2023/10
Nuclear regulatory inspection should be performed on the basis of the risk information during the decommissioning phase of the nuclear power plant. However, it is difficult because the methodology for quantitatively assessing the radiation exposure risk during decommissioning activities has not been established. Therefore, a decommissioning risk assessment code, DecAssess-R, has been developed based on the decommissioning safety assessment code, DecAssess, which creates event trees from initiating events and evaluates the radiation risk resulting from public exposure dose for each accident sequence. The assessment took into account that mobile radioactive inventories that can be easily dispersed in the work area, such as radioactive dust accumulated in HEPA filters attached to a contamination control enclosure, will fluctuate with the progress of the decommissioning work. Initiating events were selected based on the investigation of accidents and malfunctions during dismantling, disassembly, and component replacement activities around the world, and event trees were created from the initiating events to indicate the progress scenario. The frequencies of occurrence were determined with reference to general industry data in addition to the above accidents and malfunctions, and the probabilities of event progression were determined with reference to failure data during the operation phase. The exposure risks during dismantling of components in the reference BWR were evaluated. As a result, the public exposure dose was maximum in case of fire during dismantling of reactor internals and fire spread to combustibles and filters, including radioactivity temporarily stored in the work area. The exposure risk was also maximum because the probability of occurrence of this accident sequence was greater than that of other scenarios.
Nugraha, E. D.*; Hosoda, Masahiro*; Kusdiana*; Untara*; Mellawati, J.*; Nurokhim*; Tamakuma, Yuki*; Ikram, A.*; Syaifudin, M.*; Yamada, Ryohei; et al.
Scientific Reports (Internet), 11(1), p.14578_1 - 14578_16, 2021/07
Times Cited Count：19 Percentile：84.25(Multidisciplinary Sciences)Mamuju is one of the regions in Indonesia which retains natural conditions but has relatively high exposure to natural radiation. The goals of the present study were to characterize exposure of the entire Mamuju region as a high natural background radiation area (HNBRA) and to assess the existing exposure as a means for radiation protection of the public and the environment. A cross-sectional study method was used with cluster sampling areas by measuring all parameters that contribute to external and internal radiation exposures. It was determined that Mamuju was a unique HNBRA with the annual effective dose between 17 and 115 mSv, with an average of 32 mSv. The lifetime cumulative dose calculation suggested that Mamuju residents could receive as much as 2.2 Sv on average which is much higher than the average dose of atomic bomb survivors for which risks of cancer and non-cancer diseases are demonstrated. The study results are new scientific data allowing better understanding of health effects related to chronic low-dose-rate radiation exposure and they can be used as the main input in a future epidemiology study.
Endo, Akira; Yamaguchi, Yasuhiro; Eckerman, K. F.*
JAERI 1347, 114 Pages, 2005/02
no abstracts in English
Endo, Akira; Yamaguchi, Yasuhiro
JAERI-Data/Code 2001-004, 157 Pages, 2001/03
JAERI-Data-Code-2001-004.pdf:11.27MB
New nuclear decay data used for dose calculation have been compiled for 817 radionuclides that are listed in ICRP Publication 38 (Publ.38) and for 6 additional isomers. The decay data were prepared using decay data sets from the Evaluated Nuclear Structure Data File (ENSDF), the latest version in August 1997. Basic nuclear properties in the decay data sets that are important for calculating energies and intensities of emissions were updated by referring to NUBASE. In addition, possible revisions of partial and incomplete decay data sets were done for their format and syntax errors, level schemes, normalization records, and so on. After that, the decay data sets were processed by EDISTR in order to compute the energies and intensities of 
particles, 
particles, 
rays, internal conversion electrons, X rays, and Auger electrons. The compiled data were prepared in two different types of format: Publ.38 and NUCDECAY formats. The decay data will be widely used for dose calculations in radiation protection and will be beneficial to a future revision of ICRP Publ.38.
Endo, Akira; Yamaguchi, Yasuhiro
Proceedings of 10th International Congress of the International Radiation Protection Association (IRPA-10) (CD-ROM), 8 Pages, 2000/05
no abstracts in English
Endo, Akira; *; Yamaguchi, Yasuhiro
JAERI-Data/Code 99-035, 355 Pages, 1999/07
JAERI-Data-Code-99-035.pdf:14.77MB
no abstracts in English
Homma, Toshimitsu; Togawa, Orihiko
JAERI-Data/Code 96-034, 47 Pages, 1996/11
JAERI-Data-Code-96-034.pdf:1.64MB
no abstracts in English
Takahashi, Fumiaki
no journal, ,
JAEA has developed a radiation transport calculation code PHITS and Japanese adult models that enable us to perform computation dosimetry. In recent years, we have analyzed radiation dose assessment data by PHITS for public external exposure from radioactive cesium following the Fukushima Dai-ichi NPP accident. Here, a numerical method was developed to simulate transport of photons in environment and conversion coefficient data were analyzed to estimate effective dose for public including various ages. An integral dose assessment method was developed to predict radiation dose in future by taking account for cesium transfer and indoor dose reduction data were assessed by PHITS. In addition, the relationship between and effective dose and dosimeter reading was clarified for public exposure. These data were useful to make discussions on returning of habitants and to confirm verification of individual monitoring. These results and future plans on computational dosimetry are to be reported in this presentation.
Ulanowski, A.*; Balonov, M.*; Chipiga, L.*; Kinase, Sakae
no journal, ,
