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JAEA Reports

Study on the evaluation method to determine the radioactivity concentration in radioactive waste on Oarai Research and Development Institute (FY2019)

Asakura, Kazuki; Shimomura, Yusuke; Donomae, Yasushi; Abe, Kazuyuki; Kitamura, Ryoichi

JAEA-Review 2020-015, 66 Pages, 2020/09

JAEA-Review-2020-015.pdf:4.27MB

The disposal of radioactive waste from the research facility need to calculated from the radioactivity concentration that based on variously nuclear fuels and materials. In Japan Atomic Energy Oarai Research and Development Institute, the study on considering disposal is being advanced among the facilities which generate radioactive waste as well as the facilities which process radioactive waste. This report summarizes a study result in FY2019 about the evaluation method to determine the radioactivity concentration in radioactive waste on Oarai Research and Development Institute.

Journal Articles

Optimization of light water reactor high level waste disposal scenario in the situation of delayed reprocessing with existing and demonstrated technology

Fukaya, Yuji

Annals of Nuclear Energy, 144, p.107503_1 - 107503_7, 2020/09

 Times Cited Count:0 Percentile:100(Nuclear Science & Technology)

Disposal scenario of High Level Waste (HLW) of Light Water Reactor (LWR) have been optimized to reduce waste volume and repository footprint in geological disposal. The optimization was performed with existing and demonstrated technology in the situation where the reprocessing will be delayed. In general, the scenario with Partitioning and Transmutation (P&T) is optimized to minimize waste package number generated in the situation where the spent fuel will be reprocessed immediately with the minimum cooling time. With considering the delay of reprocessing, it is found that the more simplified and effective optimization with the high-waste-loading glass and cold crucible induction melter technologies and without partitioning. The optimized case can achieve significant reduction of number of waste package generation and the repository footprint to half of those of non-P&T case with 100 years cooling.

Journal Articles

A Coupled modeling simulator for near-field processes in cement engineered barrier systems for radioactive waste disposal

Benbow, S. J.*; Kawama, Daisuke*; Takase, Hiroyasu*; Shimizu, Hiroyuki*; Oda, Chie; Hirano, Fumio; Takayama, Yusuke; Mihara, Morihiro; Honda, Akira

Crystals (Internet), 10(9), p.767_1 - 767_33, 2020/09

Details are presented of the development of a coupled modeling simulator for assessing the evolution in the near-field of a geological repository for radioactive waste disposal where concrete is used as a backfill. The simulator uses OpenMI, a standard for exchanging data between simulation software programs at run-time, to form a coupled chemical-mechanical-hydrogeological model of the system. The approach combines a tunnel scale stress analysis finite element model, a discrete element model for accurately modeling the patterns of emerging cracks in the concrete, and a finite element and finite volume model of the chemical processes and alteration in the porous matrix and cracks in the concrete, to produce a fully coupled model of the system. Combining existing detailed simulation software in this way with OpenMI has the benefit of not relying on simplifications that might be necessary to combine all of the modeled processes in a single piece of software.

Journal Articles

Research on activation assessment of a reactor structural materials for decommissioning, 2

Seki, Misaki; Ishikawa, Koji*; Sano, Tadafumi*; Nagata, Hiroshi; Otsuka, Kaoru; Omori, Takazumi; Hanakawa, Hiroki; Ide, Hiroshi; Tsuchiya, Kunihiko; Fujihara, Yasuyuki*; et al.

KURNS Progress Report 2019, P. 279, 2020/08

no abstracts in English

Journal Articles

Comparison of field data and numerical simulation of nitrate evolution in groundwater using the model of nitrate evolution

Abe, Toru*; Hirano, Fumio; Mihara, Morihiro; Honda, Akira

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 27(1), p.3 - 11, 2020/06

Degradation of TRU waste in a geological disposal facility may cause the formation of a nitrate plume. A Nitrate Evolution model due to mineral reactions, microbial activity, and metal corrosiON (NEON) has therefore been developed to evaluate the safety case for geological disposal of TRU waste. Small scale laboratory experiments can be reproduced satisfactorily, however, it is necessary to demonstrate the applicability of the NEON model on scales relevant to the geological disposal of TRU waste. In the current study, an industrial analogue of a nitrate plume from the pollution of groundwater from nitrate fertilizers used on Ikuchi Island, Japan was selected to test the applicability of the NEON model. Concentration profiles of nitrate ions in the groundwater were successfully reproduced over the hundreds of meters scale demonstrating the applicability of the NEON model in evaluating the chemical behavior of a nitrate plume derived from the geological disposal of TRU waste.

Journal Articles

Evaluation of oxidation efficiency of hydrophobic palladium catalyst for $$^{3}$$H monitoring in radioactive gaseous waste

Furutani, Misa; Kometani, Tatsunari; Nakagawa, Masahiro; Ueno, Yumi; Sato, Junya; Iwai, Yasunori*

Hoken Butsuri (Internet), 55(2), p.97 - 101, 2020/06

Herein, an oxidation catalyst was introduced after heating it to 600$$^{circ}$$C to oxidize tritium gas (HT) existing in exhaust into tritiated water vapor (HTO). This study aims to establish a safer $$^{3}$$H monitoring system by lowering the heating temperature required for the catalyst. In these experiments, which were conducted in the Nuclear Science Research Institute, Japan Atomic Energy Agency, cupric oxide, hydrophobic palladium/silicon dioxide (Pd/SiO$$_{2}$$), and platinum/aluminum oxide (Pt/Al$$_{2}$$O$$_{3}$$) catalysts were ventilated using standard hydrogen gas. After comparing the oxidation efficiency of each catalyst at different temperatures, we found that the hydrophobic Pd/SiO$$_{2}$$ and Pt/Al$$_{2}$$O$$_{3}$$ catalysts could oxidize HT into HTO at 25$$^{circ}$$C.

Journal Articles

Development of ODS tempered martensitic steel for high burn up fuel cladding tube of SFR

Otsuka, Satoshi; Tanno, Takashi; Oka, Hiroshi; Yano, Yasuhide; Tachi, Yoshiaki; Kaito, Takeji; Hashidate, Ryuta; Kato, Shoichi; Furukawa, Tomohiro; Ito, Chikara; et al.

2018 GIF Symposium Proceedings (Internet), p.305 - 314, 2020/05

Oxide Dispersion Strengthened (ODS) steel has been developed worldwide as a high-strength and radiation-tolerant steel used for advanced nuclear system. Japan Atomic Energy Agency (JAEA) has been developing ODS steel as the primary candidate material of Sodium cooled Fast Reactor (SFR) high burn-up fuel cladding tube. Application of high burn-up fuel to SFR core can contribute to improvement of economical performance of SFR in conjunction with volume and hazardousness reduction of radioactive waste. This paper described the current status and future prospects of ODS tempered martensitic steel development in JAEA for SFR fuel application.

JAEA Reports

Analysis of the radioactivity concentrations in low-level radioactive waste generated from JRR-2, JRR-3 and hot laboratory facilities

Tobita, Minoru*; Haraga, Tomoko; Sasaki, Takayuki*; Seki, Kotaro*; Omori, Hiroyuki*; Kochiyama, Mami; Shimomura, Yusuke; Ishimori, Kenichiro; Kameo, Yutaka

JAEA-Data/Code 2019-016, 72 Pages, 2020/02

JAEA-Data-Code-2019-016.pdf:2.67MB

In the future, radioactive wastes which generated from research and testing reactors in Japan Atomic Energy Agency are planning to be buried for the near surface disposal. Therefore, it is required to establish the method to evaluate the radioactivity concentrations of radioactive wastes by the time it starts disposal. In order to contribute to this work, we collected and analyzed the samples generated from JRR-2, JRR-3 and Hot laboratory facilities. In this report, we summarized the radioactivity concentrations of 25 radionuclides ($$^{3}$$H, $$^{14}$$C, $$^{36}$$Cl, $$^{60}$$Co, $$^{63}$$Ni, $$^{90}$$Sr, $$^{94}$$Nb, $$^{93}$$Mo, $$^{99}$$Tc, $$^{108m}$$Ag, $$^{126}$$Sn, $$^{129}$$I, $$^{137}$$Cs, $$^{152}$$Eu, $$^{154}$$Eu, $$^{233}$$U, $$^{234}$$U, $$^{238}$$U, $$^{238}$$Pu, $$^{239}$$Pu, $$^{240}$$Pu, $$^{241}$$Pu, $$^{241}$$Am, $$^{243}$$Am, $$^{244}$$Cm) which were obtained from radiochemical analysis of those samples.

JAEA Reports

Evaluation report of research and development on "Geological Disposal of High-level Radioactive Waste" (Interim report)

Geological Disposal Research and Development Department

JAEA-Evaluation 2019-010, 69 Pages, 2020/01

JAEA-Evaluation-2019-010.pdf:2.54MB
JAEA-Evaluation-2019-010-appendix(CD-ROM).zip:13.88MB

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.

Journal Articles

Current status of low level radioactive wastes generated from research, industrial and medical

Sakamoto, Yoshiaki

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 26(2), p.127 - 132, 2019/12

JAEA has promoted near surface disposal project for low-level radioactive wastes generated from research, industrial and medical facilities after receiving project approval from the government in 2009. This kind of low level radioactive wastes which were arising from the 1940s are still keeping in each storage buildings. For immediate treatment and disposal of the wastes, technical issue and commercialization of the disposal project are studied by JAEA. The outline of current status of the disposal project of JAEA and some approach to push forward rational treatment and disposal system are presented.

Journal Articles

The Current status on analysis of radioactive waste at Fukushima Daiichi Nuclear Power Station

Koma, Yoshikazu

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 26(2), p.133 - 136, 2019/12

At Fukushima Daiichi Nuclear Power Station, radioactive waste has been generated due to progress of decommissioning. This review outlines analysis of the waste at the site for R&D concerning waste management technologies.

Journal Articles

Effort for management of radioactive waste with unknown quality and amount

Koma, Yoshikazu; Niibori, Yuichi*

Nippon Kikai Gakkai-Shi, 122(1211), p.21 - 23, 2019/10

International Topical Workshop on Fukushima Decommissioning Research was held in March 2019 by the Japan Society of Mechanical Engineers and the Atomic Energy Society of Japan. Result of track for waste management technologies among 5 tracks is outlined.

Journal Articles

Research on activation assessment of a reactor structural materials for decommissioning

Seki, Misaki; Ishikawa, Koji*; Nagata, Hiroshi; Otsuka, Kaoru; Omori, Takazumi; Hanakawa, Hiroki; Ide, Hiroshi; Tsuchiya, Kunihiko; Sano, Tadafumi*; Fujihara, Yasuyuki*; et al.

KURNS Progress Report 2018, P. 257, 2019/08

no abstracts in English

JAEA Reports

Study on the evaluation method to determine the radioactivity concentration in radioactive waste generated from the dismantling of research reactors

Murakami, Masashi; Hoshino, Yuzuru; Nakatani, Takayoshi; Sugaya, Toshikatsu; Fukumura, Nobuo*; Sanda, Toshio*; Sakai, Akihiro

JAEA-Technology 2019-003, 50 Pages, 2019/06

JAEA-Technology-2019-003.pdf:4.42MB

Toward the establishment of a common approach to determine the radioactivity concentrations in dismantling wastes arising from research reactors, radionuclide concentrations in the reactor structure materials of aluminum, carbon steel, shield concrete, and graphite of TRIGA Mark II reactor at Rikkyo University, Japan, were evaluated with both radiochemical analysis and theoretical calculation. The measured nuclides by the radiochemical analysis were $$^{3}$$H, $$^{60}$$Co, and $$^{63}$$Ni in aluminum, $$^{3}$$H, $$^{60}$$Co, $$^{63}$$Ni, and $$^{152}$$Eu in carbon steel, $$^{3}$$H, $$^{60}$$Co, and $$^{152}$$Eu in shield concrete, and $$^{3}$$H, $$^{14}$$C, $$^{60}$$Co, $$^{63}$$Ni, and $$^{152}$$Eu in graphite. Neutron-flux distributions and neutron-induced activities were computed with DORT and ORIGEN-ARP codes, respectively. Using the results of material composition analysis, radioactivity concentrations were conservatively predicted with good accuracy except for graphite material.

Journal Articles

Risk communication at Horonobe Underground Research Center, using the Public Information House and Underground Research Laboratory

Osawa, Hideaki; Nogami, Toshinobu; Hoshino, Masato; Tokunaga, Hiroaki*; Horikoshi, Hidehiko*

Genshiryoku Bakkuendo Kenkyu (CD-ROM), 26(1), p.45 - 55, 2019/06

Japan Atomic Energy Agency has performed risk communication at Horonobe Underground Research Center, using the Public Information House and Underground Research Laboratory (URL), to promote understanding R&D of geological disposal technology and waste disposal against public. In this paper, we conducted the analysis of questionnaire investigation performing after visiting those facilities from FY2013 to FY2017. The results show that long-term safety would gain prominent attention as agita factor by growing understanding. The results also shows that visiting to those facility would become valuable experience to understand geological disposal because, for example, respondents with visiting to URL positively evaluated necessity, appropriates and safety of geological disposal, compared with those without visiting URL.

Journal Articles

Effects of trust and procedural fairness on public acceptance of siting a repository for high-level radioactive waste

Osawa, Hideaki; Otomo, Shoji*; Hirose, Yukio*; Onuma, Susumu*

Ningen Kankyogaku Kenkyu, 17(1), p.59 - 64, 2019/06

This study examined the determinants of public acceptance of siting a repository for High-level radioactive waste (HLW), focusing on procedural fairness and trust. To examine the presumption, the study implemented a hypothetical scenario experiment that manipulated two factors: an opportunity of voice as an antecedent of procedural fairness and similarity value to the authority as a component of trust. Results indicated that affective reaction, procedural fairness, and trust determined public acceptance. A process analysis indicated that the effect of procedural fairness was strengthened when the trust on similarity was negative.

Journal Articles

Importance of root uptake of $$^{14}$$CO$$_{2}$$ on $$^{14}$$C transfer to plants impacted by below-ground $$^{14}$$CH$$_{4}$$ release

Ota, Masakazu; Tanaka, Taku*

Journal of Environmental Radioactivity, 201, p.5 - 18, 2019/05

 Times Cited Count:2 Percentile:55.77(Environmental Sciences)

$$^{14}$$CH$$_{4}$$ released from deep underground radioactive waste disposal facilities can be a belowground source of $$^{14}$$CO$$_{2}$$ owing to microbial oxidation of $$^{14}$$CH$$_{4}$$ to $$^{14}$$CO$$_{2}$$ in soils. Environmental $$^{14}$$C models assume that the transfer of $$^{14}$$CO$$_{2}$$ from soil to plant occurs via foliar uptake of $$^{14}$$CO$$_{2}$$. Nevertheless, the importance of $$^{14}$$CO$$_{2}$$ root uptake is not well understood. In the present study, belowground transport and oxidation of $$^{14}$$CH$$_{4}$$ were modeled and incorporated into an existing land surface $$^{14}$$CO$$_{2}$$ model (SOLVEG-II) to assess the importance of root uptake on $$^{14}$$CO$$_{2}$$ transfer to plants. Performance of the model in calculating the belowground dynamics of $$^{14}$$CH$$_{4}$$ was validated by simulating a field experiment of $$^{13}$$CH$$_{4}$$ injection into subsoil. The model was then applied to $$^{14}$$C transfer in a hypothetical ecosystem impacted by continuous $$^{14}$$CH$$_{4}$$ input from the water table (bottom of one-meter thick soil). In a shallowly rooted ecosystem with rooting depth of 11 cm, foliar uptake of $$^{14}$$CO$$_{2}$$ was significant, accounting for 80% of the $$^{14}$$C accumulation in the leaves. In a deeply rooted ecosystem (rooting depth of 97 cm), where the root penetrated to depths close to the water-table, more than half (63%) the $$^{14}$$C accumulated in the leaves was transferred by the root uptake. We found that $$^{14}$$CO$$_{2}$$ root uptake in this ecosystem depended on the distribution of methane oxidation in the soil; all $$^{14}$$C accumulated in the leaves was transferred by the root uptake when methane oxidation occurred at considerable depths (e-folding depths of 20 cm, or 80 cm). These results indicate that $$^{14}$$CO$$_{2}$$ root uptake contributes significantly to $$^{14}$$CO$$_{2}$$ transfer to plants if $$^{14}$$CH$$_{4}$$ oxidation occurs at great depths and roots penetrate deeply into the soil.

Journal Articles

Study on decontamination of steel surface contaminated with uranium hexafluoride by acidic electrolytic water

Nakayama, Takuya; Nomura, Mitsuo; Mita, Yutaka; Yonekawa, Hitoshi*; Bunbai, Misako*; Yaita, Yumi*; Murata, Eiichi*; Hosaka, Katsumi*; Sugitsue, Noritake

Proceedings of 2019 International Congress on Advances in Nuclear Power Plants (ICAPP 2019) (Internet), 8 Pages, 2019/05

Clearance of contaminated metal is important for recycling and volume reduction of radioactive waste. Among applicable decontamination technologies, immersion method with ultrasonic cleaning is considered to be effective for metal materials having various shapes. in this study is to demonstrate decontamination of carbon steel contaminated by uranium hexafluoride to the target level for clearance (less than 0.04 Bq/cm$$^{2}$$), and minimize secondary waste. In this test, acidic electrolytic water, dilute hydrochloric acid, dilute sulfuric acid and ozone water with various pH and redox potential were used as decontamination solutions to be tested. We found that acidic electrolytic water is effective solution for decontamination of carbon steel contaminated by uranium hexafluoride. It could be decontaminate less than target level for clearance, and reduced secondary waste relatively.

Journal Articles

Environmental research on uranium at the Ningyo-Toge Environmental Engineering Center, JAEA

Sato, Kazuhiko; Yagi, Naoto; Nakagiri, Toshio

Proceedings of 27th International Conference on Nuclear Engineering (ICONE-27) (Internet), 6 Pages, 2019/05

no abstracts in English

JAEA Reports

Study on the basic system of the common non-destructive radioactivity measuring equipment for disposal of radioactive wastes generated from research, industrial and medical facilities

Izumo, Sari; Hayashi, Hirokazu; Nakata, Hisakazu; Amazawa, Hiroya; Motoyama, Mitsushi*; Sakai, Akihiro

JAEA-Technology 2018-018, 39 Pages, 2019/03

JAEA-Technology-2018-018.pdf:2.8MB

JAEA has planed the near surface disposal of LLW generated from research, industrial, and medical facilities. Maximum radioactivity concentration of each waste and total radioactivity of disposed wastes are needed to be less than the permitted values in the license of disposal facility. Thus, it is important not to evaluate the radioactivity of each waste in unduly conservative ways so as to dispose of the total amount of the waste that is originally planned. Accordingly, the detection limit is required to be as low as the clearance level for the very low level radioactive waste planned to be disposed of trench-type. In this report, the feasibility of the non-destructive assay method is studied by model calculations for gamma emitters. It is confirmed that the detection limit less than the clearance level can be achieved as regards the box type metal container that is difficult to measure. This report summarizes the requirements for the non-destructive measuring equipment.

1879 (Records 1-20 displayed on this page)