Annals of the ICRP, 49(2), p.7 - 9, 2020/10
no abstracts in English
Sugita, Tsuyoshi; Kobayashi, Kentaro*; Yamazaki, Taiki*; Isaka, Mayu*; Itabashi, Hideyuki*; Mori, Masanobu*
Journal of Photochemistry and Photobiology A; Chemistry, 400, p.112662_1 - 112662_8, 2020/09
In this study, we developed an in-line photocatalytic performance evaluation system in which a flow reactor was connected to the ion chromatography to accurately evaluate the performance of the photocatalyst. This system was used to evaluate the photocatalyst supported by the two-layer support method on the substrate, such as glass beads. The performance of the photocatalyst was evaluated using dimethyl sulfoxide (DMSO), and it was possible to monitor the decomposition of DMSO by UV and the formation of by-products, such as methane sulfonate (MSO) and sulfate (SA). This system can be expected to be useful not only for evaluating the decomposition performance of an object using a photocatalyst but also for evaluating the byproducts.
Tanaka, Masaaki; Nakada, Kotaro*; Kudo, Yoshiro*
Nippon Kikai Gakkai-Shi, 123(1222), p.26 - 29, 2020/09
In the nuclear engineering, simulations are used in radiation, thermal hydraulic, chemical reaction, and structural fields, and the integrated fields thereof, to be applied to the design, construction and operation of nuclear facilities. This article describes brief history of discussion in the AESJ to the publication and introductory explanation of the procedures in the five major elements described in the "Guideline for Credibility Assessment of Nuclear Simulations (AESJ-SC-A008: 2015)". And also, a practical experience of the V&V activity according to the fundamental concept indicated in the Guideline is introduced.
Sakamoto, Naoki; Fujishima, Tadatsune; Mizukoshi, Yasutaka
Hozengaku, 19(2), p.125 - 126, 2020/07
The five post-irradiation examination facilities in JAEA's Oarai research and development institute have been operated for over 40 years in order to investigate the irradiation performance of fast reactor fuel materials. The equipment associated with these facilities has been managed to maintain secure from the problems occurred in the process of aging. Therefore, we established a safety assessment method for aging facilities in 2002, and we have been conducting maintenance management of facilities since then. In this study, improvement plans of the safety assessment method are considered in order to solve the issues detected as a result of analysis of past maintenance information.
Sawaguchi, Takuma; Takai, Shizuka; Takeda, Seiji
JAEA-Research 2020-005, 47 Pages, 2020/06
After the Fukushima Daiichi Nuclear Power Station accident, large quantities of radiocesium-contaminated soil were generated from decontamination activities in the Fukushima prefecture. The removed soil has been stored in the prefecture until its final disposal. To complete the final disposal outside Fukushima prefecture, reducing the disposal volume through recycling can prove effective. The Ministry of the Environment, Japan (MOE) has presented a policy to recycle low-radioactive removed soil as recycled materials under the management of public authority. The recycling is limited to civil engineering structures in public projects. In this study, to contribute to guideline development for removed soil recycling by MOE, dose estimation in recycling of removed soil as embankment materials of seaside protection forest was conducted. First, additional doses to workers and the public in construction and service scenarios were evaluated. From the result, the radioactive cesium concentration level of recycled materials, where all additional doses meet the radiation criterion of 1 mSv/y, was derived to be 5,000 Bq/kg. Then, construction conditions were reviewed to reduce additional doses to the public in a service scenario. With the derived radioactivity level of 5,000 Bq/kg, the covered soil thickness of 39 cm or more limited the doses to less than 10 Sv/y. Finally, additional doses in a disaster scenario were evaluated. The doses were confirmed to be below 1 mSv/y when the removed soil of 5,000 Bq/kg was used.
Sato, Hiroyuki; Ohashi, Hirofumi
Mechanical Engineering Journal (Internet), 7(3), p.19-00332_1 - 19-00332_11, 2020/06
An uncertainty analysis method for control room habitability under toxic gas leakage accidents in cogeneration HTGR is proposed to support risk-informed design of the plant. The method is applied to representative toxic gas leakage accidents in a IS process hydrogen production plant coupled to the HTTR gas turbine test plant. Epistemic and aleatory uncertainties for each variable parameter are identified and are propagated using Latin hypercube sampling. The analyses show that the suggested method can successfully characterize and quantify uncertainties in the toxic gas concentration in control room. The results lead us to the conclusion that toxic gas dispersion behavior analysis should combine two evaluation methods: dense gas dispersion model and computational fluid dynamics simulation.
Maruyama, Yu; Kita, Toshinobu*; Kuramoto, Takahiro*
Nippon Genshiryoku Gakkai-Shi, 62(6), p.328 - 333, 2020/06
no abstracts in English
Manabe, Kentaro; Koyama, Shuji*
Radiation Protection Dosimetry, 189(4), p.489 - 496, 2020/05
It is important for radiation protection in diagnostic nuclear medicine to estimate organ absorbed doses in consideration of person-specific parameters. This study proposes a straightforward method for estimating organ doses which reflect an individual organ masses by scaling the reference doses based on the reference human models using the inverse ratio of the individual masses to the reference organ masses. The method was tested for the administration cases of Tc-labelled colloids and I-labelled sodium iodine to confirm the effectiveness of the method. The discrepancies of the doses estimated by the method were sufficiently small in terms of solid organs.
Yamaguchi, Yoshihito; Katsuyama, Jinya; Li, Y.; Onizawa, Kunio
Journal of Pressure Vessel Technology, 142(2), p.021906_1 - 021906_11, 2020/04
Yoshitomi, Hiroshi; Kowatari, Munehiko
Radiation Protection Dosimetry, 188(2), p.191 - 198, 2020/02
Geological Disposal Research and Development Department
JAEA-Evaluation 2019-010, 69 Pages, 2020/01
Japan Atomic Energy Agency (JAEA) consulted the advisory committee, "Evaluation Committee on Research and Development (R&D) Activities for Geological Disposal of High-Level Radioactive Waste", for an interim review of R&D activities on high-level radioactive waste disposal in accordance with "General Guideline for the Evaluation of Government Research and Development (R&D) Activities" by the Cabinet Office, Government of Japan, "Guideline for Evaluation of R&D in Ministry of Education, Culture, Sports, Science and Technology" and JAEA's "Regulation on Conduct for Evaluation of R&D Activities". In response to JAEA's request, the Committee reviewed mainly the progress of the R&D project on geological disposal, the relevance of the project outcome during the period of FY2015-2018. This report summarizes the results of the assessment by the Committee with the Committee report attached.
Takai, Shizuka; Shimada, Asako; Sawaguchi, Takuma; Takeda, Seiji; Kimura, Hideo
Radiation Protection Dosimetry, 188(1), p.1 - 7, 2020/01
After the Fukushima Nuclear Power Plant accident, most of radiocesium-contaminated soil generated from decontamination activities outside Fukushima prefecture has been stored at decontamination sites such as schools, parks and residential lands (storage at sites) according to the Decontamination Guidelines. However, additional exposure due to the present storage has not been evaluated. Moreover, entering storage sites, which is not restricted for storage at sites, was not considered in safety assessment conducted in the guidelines. To continue the storage and confirm the effectiveness, understanding of present possible exposures is important. In this study, we evaluated exposure doses for residents and users of storage sites based on the present situation. As a result, annual doses due to residence were 10 to 10 mSv y and doses due to annual entries were of the order of 10 mSv y. Hence, we confirmed that the exposure due to present storage outside Fukushima is significantly less than 1 mSv y.
Hayafune, Hiroki; Maeda, Seiichiro; Ohshima, Hiroyuki
Nippon Genshiryoku Gakkai-Shi, 61(11), p.798 - 803, 2019/11
In the "Strategic Roadmap" of Fast Reactor Development decided at the Inter-Ministerial Council for Nuclear Power in December 2018, the development works for the around next 10 years were identified, and the role of JAEA was presented. In response, JAEA has prepared a framework for R&D plans for about 5 years on the fast reactor technology and the fuel cycle technology (reprocessing, fuel manufacturing, fuel and material development). In the future, JAEA will promote independent R&D works based on these plans, and provide the obtained R&D results together with various testing functions of JAEA to the activities of the private sector, etc. Through these actions, JAEA will actively contribute to the future fast reactor development. This article outlines JAEA's policy and the R&D items (development of ARKADIA; Advanced Reactor Knowledge- and AI-Aided Design Integration Approach through the whole Plant Life Cycle, development of standards and standards system, development of safety improvement technology, research in the fuel cycle technology), the policy of international cooperation, the human resource development, and the future perspective were explained.
Baron, P.*; Cornet, S. M.*; Collins, E. D.*; DeAngelis, G.*; Del Cul, G.*; Fedorov, Y.*; Glatz, J. P.*; Ignatiev, V.*; Inoue, Tadashi*; Khaperskaya, A.*; et al.
Progress in Nuclear Energy, 117, p.103091_1 - 103091_24, 2019/11
The results of an international review of separation processes for spent nuclear fuel (SNF) recycling in future closed fuel cycles with the evaluation of Technology Readiness Level are reported. This study was made by the Expert Group on Fuel Recycling Chemistry (EGFRC) organised by the Nuclear Energy Agency (NEA) of the Organisation for Economic Co-operation and Development (OECD). A unique feature of this study was that processes were classified according to a hierarchy of separations aimed at different elements within spent fuel (uranium; uranium-plutonium co-recovery; minor actinides; high heat generating radionuclides) and also the Head-end processes, used to prepare the SNF for chemical separation, were included. Separation processes covered both wet (hydrometallurgical) and dry (pyro-chemical) processes.
Tomita, Jumpei; Takeuchi, Erina
Applied Radiation and Isotopes, 150, p.103 - 109, 2019/08
A rapid analytical method for determining Sr in urine samples (1-2 L) was developed to assess the internal exposure of workers in a radiological emergency. Strontium in a urine sample was rapidly separated by phosphate co-precipitation, followed by extraction chromatography with a tandem column of Pre-filter, TRU and Sr resin, and the Sr activity was determined by ICP-MS/MS. Measurement in the MS/MS mode with an O reaction gas flow rate 1 mL min showed no tailing of Sr at m/z = 90 up to 50 mg-Sr L. The interferences of Ge, Se and Zr at m/z = 90 were successfully removed by chemical separation. This analytical method was validated by the results of the analyses of synthetic urine samples (1.2-1.6 L) containing a known amount of Sr along with 1 mg of each of Ge, Se, Sr and Zr. The turnaround time for analysis was about 10 h, and the detection limit of Sr was approximately 1 Bq per urine sample.
Yoshitomi, Hiroshi; Kowatari, Munehiko; Hagiwara, Masayuki*; Nagaguro, Seiji*; Nakamura, Hajime*
Radiation Protection Dosimetry, 184(2), p.179 - 188, 2019/08
Kaku Nenryo, (54-2), P. 3, 2019/07
no abstracts in English
Sector of Fast Reactor and Advanced Reactor Research and Development
JAEA-Evaluation 2019-004, 47 Pages, 2019/06
Japan Atomic Energy Agency (hereafter referred to as "JAEA") consulted with the "Evaluation Committee of Research and Development Activities for Fast Reactor Cycle" (hereinafter referred to as "Committee"), which consists of specialists in the fields of the evaluation subjects of fast reactor cycle technologies, for interim assessment of R&D activities of fast reactor cycle in the 3rd Mid- and Long-Term Plan (from April 2015 to March 2022) in accordance with "General Guideline for the Evaluation of Government Research and Development (R&D) Activities" by Cabinet Office, Government of Japan, "Guideline for Evaluation of R&D in Ministry of Education, Culture, Sports, Science and Technology" and Regulation on Conduct for Evaluation of R&D Activities" by JAEA. In response to the JAEA's request, the Committee assessed the R&D program of fast reactor cycle technologies during the period of four years from April 2015 to March 2018. The Committee evaluated the management and R&D activities based on the explanatory documents and oral presentations by JAEA. The results of the evaluation were compiled in assessment report that was organized including the reasons for evaluation and the opinions and recommendations. This report is issued for the purpose of actively disseminate evaluation information to the people of Japan (based on General Guideline), which lists the members of the Committee and outlines the assessment items and the review process for procedure of the assessment. The assessment report which was issued by the Committee is attached.
Onoe, Hironori; Kosaka, Hiroshi*; Matsuoka, Toshiyuki; Komatsu, Tetsuya; Takeuchi, Ryuji; Iwatsuki, Teruki; Yasue, Kenichi
Genshiryoku Bakkuendo Kenkyu (CD-ROM), 26(1), p.3 - 14, 2019/06
In this study, it is focused on topographic changes due to uplift and denudation, also climate perturbations, a method which is able to assess the long-term variability of groundwater flow conditions using the coefficient variation based on some steady-state groundwater flow simulation results was developed. Spatial distribution of long residence time area which is not much influenced due to long-term topographic change and recharge rate change during the past one million years was able to estimate through the case study of the Tono area, Central Japan. By applying this evaluation method, it is possible to identify the local area that has low variability of groundwater flow conditions due to topographic changes and climate perturbations from the regional area quantitatively and spatially.
Yamamoto, Tomohiko; Matsubara, Shinichiro*; Harada, Hidenori*; Saunier, P.*; Martin, L.*; Gentet, D.*; Dirat, J.-F.*; Collignon, C.*
Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 8 Pages, 2019/05
Japan-France collaboration on ASTRID (Advanced Sodium Technological Reactor for Industrial Demonstration) project is launched in 2014. In this project, Japan-France evaluates core assemblies with interferences on seismic event. The object of this study is to verify the seismic evaluation method on core assemblies between Japan and France by comparing the results. The analysis of this benchmark calculation shows a satisfactory agreement between the Japanese and French tools and the figures show a good behavior of the core in horizontal direction under French seismic condition.