Investigating eutectic behavior and material relocation in BC-stainless steel composites using the improved MPS method

Ahmed, Z.*; Wu, S.*; Sharma, A.*; Kumar, R.*; Yamano, Hidemasa; Pellegrini, M.*; Yokoyama, Ryo*; Okamoto, Koji*

International Journal of Heat and Mass Transfer, 250, p.127343_1 - 127343_17, 2025/11

https://doi.org/10.1016/j.ijheatmasstransfer.2025.127343

Investigation of deposits on filter element of primary gas circulators in HTTR

Hasegawa, Toshinari; Nagasumi, Satoru; Nemoto, Takahiro; Nakajima, Kunihiro; Yokoyama, Keisuke; Fujiwara, Yusuke; Arakawa, Ryoki; Iigaki, Kazuhiko; Inoi, Hiroyuki; Kawamoto, Taiki

Proceedings of 2024 International Congress on Advanced in Nuclear Power Plants (ICAPP 2024) (Internet), 10 Pages, 2024/06

The filter element of the primary gas circulators (PGC) in High Temperature engineering Test Reactor (HTTR) and its deposits were investigated by Scanning Electron Microscope (SEM) observation and Energy Dispersive X-ray spectroscopy (EDX) analysis to find the cause of the increase of the filter differential pressure during the operation in 2021. SEM observation showed that the clumpy deposits and fibrous deposits smaller than the filtration pore size and the rod-shaped deposits larger than the pore size were present on the filter element. EDX analysis showed that the clumpy deposits and fibrous deposits could include silicone oil in the primary helium purification system (PHPS) gas circulators and that the rod-shaped deposits were thermal insulators inside of the co-axial double pipes in the primary cooling system. It is considered that silicone oil leaked from the PHPS gas circulators due to deterioration in the absorption performance of the activated charcoal filter. Next, it could be vaporized and reach PGC's filter element after passing through the reactor core. Since those deposits including silicone oil were present over the entire surface of the filter element, the filter differential pressure could be increased due to a reduction in the pore size and a rise in its flow resistance. The thermal insulator was unrelated to filter clogging because it was present mainly in the lower part of the filter element. Therefore, silicone oil could increase the filter differential pressure, and the graphite powder, which is the cause of the previous issue was unrelated.

Annual report on the environmental radiation monitoring around the Tokai Reprocessing Plant FY2019

Nakano, Masanao; Fujii, Tomoko; Nemoto, Masashi; Tobita, Keiji; Seya, Natsumi; Nishimura, Shusaku; Hosomi, Kenji; Nagaoka, Mika; Yokoyama, Hiroya; Matsubara, Natsumi; et al.

JAEA-Review 2020-069, 163 Pages, 2021/02

JAEA-Review-2020-069.pdf:4.78MB

Environmental radiation monitoring around the Tokai Reprocessing Plant has been performed by the Nuclear Fuel Cycle Engineering Laboratories, based on "Safety Regulations for the Reprocessing Plant of Japan Atomic Energy Agency, Chapter IV - Environmental Monitoring". This annual report presents the results of the environmental monitoring and the dose estimation to the hypothetical inhabitant due to the radioactivity discharged from the plant to the atmosphere and the sea during April 2019 to March 2020. In this report, some data include the influence of the accidental release from the Fukushima Daiichi Nuclear Power Station of Tokyo Electric Power Co., Inc. (the trade name was changed to Tokyo Electric Power Company Holdings, Inc. on April 1, 2016) in March 2011. Appendices present comprehensive information, such as monitoring programs, monitoring methods, monitoring results and their trends, meteorological data and discharged radioactive wastes. In addition, the data which were influenced by the accidental release and exceeded the normal range of fluctuation in the monitoring, were evaluated.

Type II shell evolution in isobars from the island of inversion

Morales, A. I.*; Benzoni, G.*; Watanabe, H.*; Tsunoda, Yusuke*; Otsuka, T.*; Nishimura, Shunji*; Browne, F.*; Daido, R.*; Doornenbal, P.*; Fang, Y.*; et al.

Physics Letters B, 765, p.328 - 333, 2017/02

https://doi.org/10.1016/j.physletb.2016.12.025

Low-lying excitations in Ni

Morales, A. I.*; Benzoni, G.*; Watanabe, H.*; Nishimura, Shunji*; Browne, F.*; Daido, R.*; Doornenbal, P.*; Fang, Y.*; Lorusso, G.*; Patel, Z.*; et al.

Physical Review C, 93(3), p.034328_1 - 034328_14, 2016/03

https://doi.org/10.1103/PhysRevC.93.034328

Production and separation of astatine isotopes in the Li + Pb reaction

Nishinaka, Ichiro; Yokoyama, Akihiko*; Washiyama, Koshin*; Maeda, Eita*; Watanabe, Shigeki; Hashimoto, Kazuyuki; Ishioka, Noriko; Makii, Hiroyuki; Toyoshima, Atsushi; Yamada, Norihiro*; et al.

Journal of Radioanalytical and Nuclear Chemistry, 304(3), p.1077 - 1083, 2015/06

https://doi.org/10.1007/s10967-015-3975-y

Production cross sections of astatine isotopes At in the 29-57 MeV Li induced reaction with Pb target have been measured by - and -ray spectrometry. Excitation functions of production cross sections have been compared with a statistical model calculation to study the reaction mechanism of Li + Pb. Considerably small experimental cross sections of At and At compared with the calculation were clearly observed at incident energies higher than 44 MeV, indicating that the effects of breakup reaction play a role. A chemical separation of astatine from an irradiated lead target has been studied with a dry-distillation method. A complementary way to produce astatine isotopes has been developed.

In-situ stress measurement in the Mizunami Underground Research Laboratory; A New test of strain sensitivity method applying to CCBO

Tanno, Takeo; Sato, Toshinori; Sanada, Hiroyuki; Hikima, Ryoichi*; Yokoyama, Tatsuya*; Shimoyama, Masahiro*

Heisei-25 Nendo (2013 Nen) Shigen, Sozai Gakkai Shuki Taikai Koenshu, p.255 - 256, 2013/09

rock stresses were measured by Compact Conical-ended Borehole Overcoring (CCBO) technique in the 300m depth gallery at the Mizunami Underground Research Laboratory and the measurement results were evaluated using a conventional method and a new test of strain sensitivity method. To compare the rock stress evaluated by both methods, the new test of strain sensitivity method resulted in more accurate evaluation than the conventional method, because of its improved stress deviations.

Production of alpha-emitting radioisotopes using the cyclotron facilities at Osaka University and JAEA Takasaki, and the Tandem accelerator at Tokai, JAEA

Washiyama, Koshin*; Amano, Ryohei*; Maeda, Eita*; Yokoyama, Akihiko*; Nishinaka, Ichiro; Takahashi, Naruto*; Shinohara, Atsushi*; Watanabe, Shigeki; Ishioka, Noriko

no journal, , 

In order to use of an alpha emitter for targeted alpha therapy, we have started the production and the utilization of At using 30 MeV He particle in the Bi(He, 2n)At nuclear reaction at cyclotron facilities of Osaka University and JAEA Takasaki. In addition to that, we have been developing a Rn/At generator to expand the availability of At to wide range of populations far away from cyclotron facilities. The results of studies on the At-chemistry for clinical use and on the development of the Rn/At generator will be presented. And a review of current status of targeted alpha therapy in Japan will be also introduced.

Development of embeded Mach-Zender waveguide using substrate of PDMS

Miura, Kenta*; Kada, Wataru*; Saruya, Ryota*; Hanaizumi, Osamu*; Ishii, Yasuyuki; Koka, Masashi; Yokoyama, Akihito; Sato, Takahiro; Kamiya, Tomihiro

no journal, , 

no abstracts in English

Quantitative tracing of water-rock interactions by IR spectoroscopy; An Example of alkaline alteration of granitic rocks

Nakashima, Satoru*; Kirino, Yusuke*; Nishiyama, Naoki*; Tonoue, Ryota*; Yokoyama, Tadashi*; Nagasawa, Makoto*; Harui, Rika*; Walker, C.; Sasamoto, Hiroshi

no journal, , 

Cementitious grout material will be used to reduce groundwater inflow into the repository of high level radioactive waste. High pH solution derived from cementitious grout material may cause alteration of rock mass by grout-rock interactions. With regard to evaluation of radionuclide migration, it is important to evaluate the long-term behavior of rock mass affected by grout-rock interactions since such altered rock mass potentially affects on migration behavior (e.g., diffusion and sorption) of radionuclide. This study presents the results of identification for trace secondary minerals (alteration products) by (micro)infrared spectroscopy and determination of reaction rate constants of formation for secondary minerals.