Stabilization treatment of the sludge items containing nuclear materials at Plutonium Conversion Development Facility

Tanigawa, Masafumi; Nakamura, Daishi; Asakawa, Naoya*; Seya, Kazuhito*; Omori, Fumio*; Koiso, Katsuya*; Horigome, Kazushi; Shimizu, Yasuyuki

JAEA-Technology 2024-001, 37 Pages, 2024/05

JAEA-Technology-2024-001.pdf:2.32MB

At plutonium conversion development facility, the neutralization sedimentation and the coagulation sedimentation (sludge) items are stored in a polyethylene container packed in the plastic bag. The neutralization sedimentation items and the coagulation sedimentation items are stored in the globe box and storage room in the facility, respectively. Some sludge items generate gases, that swelled the plastic bag. We should ensure whether the bag swelling by visual confirmation. When the swelling is confirmed, those containers are transferred to the glove box to exchange the plastic bag for new one. By keeping the above procedure, those items were stored safely in the facility since its founding. The stabilization work for enhance the safe storage was planned to reduce the gas generation of the sludge items caused by the radiolysis of water. Those sludge items have the containing a sodium nitrate that has moisture-absorption characteristic. Therefore, the stabilization method aimed to remove the sodium nitrate from the items. The work was conducted from August 2018 to August 2022. The sodium concentration in items were reduced to 3 wt% or lower. Each stabilized sludge item packed in plastic bag were confirmed its swelling for over one year in the storage place. No gas generation from all item has been observed for more than the one year. And while both the neutralization and the coagulation sedimentation items were stored they were not the increasing of the moisture in the items. As a result, those items were evaluated that will not generate gases any more and confirmed to be stabilized after this treatment. Then, those neutralization sedimentation items were stored in powder cans and transferred to powder storage room as a retained waste. Based on the above results, risks of the gas generation from sludge items were decreased enough. Therefore, the safety of the stored sludge item was improved and confirmed.

Anisotropic electrical conductivity changes in FeTiO structure transition under high pressure

Yamanaka, Takamitsu*; Nakamoto, Yuki*; Sakata, Masafumi*; Shimizu, Katsuya*; Hattori, Takanori

Physics and Chemistry of Minerals, 51(1), p.4_1 - 4_10, 2024/02

https://doi.org/10.1007/s00269-023-01261-6

Neutron and synchrotron X-ray diffraction and electric conductivity measurements of FeTiO ilmenite were performed under pressures. Ilmenite structure is retained up to 28 GPa. Structure analysis revealed that FeO and TiO are compressible and less compressible below 8 GPa, respectively. The resistivity is lowest along the Fe-Ti direction that has shortest interatomic distance among all the metal ion pairs. The resistivity in the direction normal to c-axis monotonically decreases with pressure, whereas that along c-axis shows hallow-shape with pressure. Maximum entropy analysis shows that electron configuration of Fe (3) is more strongly changed than Ti (3) under compression. The anisotropic electrical conductivity and non-uniform structure change of Fe-Ti interatomic distance can be explained by the possible spin transition from high-spin state to intermediate-spin state of Fe cation.

Measurement of the transverse asymmetry of rays in the Sn()Sn reaction

Endo, Shunsuke; Okudaira, Takuya*; Abe, Ryota*; Fujioka, Hiroyuki*; Hirota, Katsuya*; Kimura, Atsushi; Kitaguchi, Masaaki*; Oku, Takayuki; Sakai, Kenji; Shima, Tatsushi*; et al.

Physical Review C, 106(6), p.064601_1 - 064601_7, 2022/12

https://doi.org/10.1103/PhysRevC.106.064601

no abstracts in English

Decommissioning of the Plutonium Research Building No.1 (Plan and Present Status)

Komuro, Michiyasu; Kanazawa, Hiroyuki; Kokusen, Junya; Shimizu, Osamu; Honda, Junichi; Harada, Katsuya; Otobe, Haruyoshi; Nakada, Masami; Inagawa, Jun

JAEA-Technology 2021-042, 197 Pages, 2022/03

JAEA-Technology-2021-042.pdf:16.87MB

Plutonium Research Building No.1 was constructed in 1960 for the purpose of establishing plutonium handling technology and studying its basic physical properties. Radiochemical research, physicochemical research and analytical chemistry regarding solutions and solid plutonium compounds had been doing for the research program in Japan Atomic Energy Agency (JAEA). In 1964, the laboratory building was expanded and started the researching plutonium-uranium mixed fuel and reprocessing of plutonium-based fuel, playing an advanced role in plutonium-related research in Japan. Since then, the research target has been expanded to include transplutonium elements, and it has functioned as a basic research facility for actinides. The laboratory is constructed by concrete structure and it has the second floor, equipped with 15 glove boxes and 4 chemical hoods. Plutonium Research Building No.1 was decided as one of the facilities to be decommissioned by Japan Atomic Energy Agency Reform Plan in September 2014. So far, the contamination survey of the radioactive materials in the controlled area, the decontamination of glove boxes, and the consideration of the equipment dismantling procedure have been performed as planned. The radioisotope and nuclear fuel materials used in the facility have been transfer to the other facilities in JAEA. The decommissioning of the facility is proceeding with the goal of completing by decommissioning the radiation controlled area in 2026. In this report, the details of the decommissioning plan and the past achievements are reported with the several data.

Energy-dependent angular distribution of individual rays in the La()La reaction

Okudaira, Takuya*; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; Niinomi, Yudai*; Sakai, Kenji; et al.

Physical Review C, 104(1), p.014601_1 - 014601_6, 2021/07

https://doi.org/10.1103/PhysRevC.104.014601

Decommissioning of the Uranium Enrichment Laboratory

Kokusen, Junya; Akasaka, Shingo*; Shimizu, Osamu; Kanazawa, Hiroyuki; Honda, Junichi; Harada, Katsuya; Okamoto, Hisato

JAEA-Technology 2020-011, 70 Pages, 2020/10

JAEA-Technology-2020-011.pdf:3.37MB

The Uranium Enrichment Laboratory in the Japan Atomic Energy Agency (JAEA) was constructed in 1972 for the purpose of uranium enrichment research. The smoke emitting accident on 1989 and the fire accident on 1997 had been happened in this facility. The research on uranium enrichment was completed in JFY1998. The decommissioning work was started including the transfer of the nuclear fuel material to the other facility in JFY2012. The decommissioning work was completed in JFY2019 which are consisting of removing the hood, dismantlement of wall and ceiling with contamination caused by fire accident. The releasing the controlled area was performed after the confirmation of any contamination is not remained in the target area. The radioactive waste was generated while decommissioning, burnable and non-flammable are 1.7t and 69.5t respectively. The Laboratory will be used as a general facility for cold experiments.

Transverse asymmetry of rays from neutron-induced compound states of La

Yamamoto, Tomoki*; Okudaira, Takuya; Endo, Shunsuke; Fujioka, Hiroyuki*; Hirota, Katsuya*; Ino, Takashi*; Ishizaki, Kohei*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; et al.

Physical Review C, 101(6), p.064624_1 - 064624_8, 2020/06

https://doi.org/10.1103/PhysRevC.101.064624

Measurement of the angular distribution of -rays after neutron capture by La for a T-violation search

Okudaira, Takuya; Shimizu, Hirohiko*; Kitaguchi, Masaaki*; Hirota, Katsuya*; Haddock, C. C.*; Ito, Ikuya*; Yamamoto, Tomoki*; Endo, Shunsuke*; Ishizaki, Kohei*; Sato, Takumi*; et al.

EPJ Web of Conferences, 219, p.09001_1 - 09001_6, 2019/12

https://doi.org/10.1051/epjconf/201921909001

Parity violating effects enhanced by up to 10 times have been observed in several neutron induced compound nuclei. There is a theoretical prediction that time reversal (T) violating effects can also be enhanced in these nuclei implying that T-violation can be searched for by making very sensitive measurements. However, the enhancement factor has not yet been measured in all nuclei. The angular distribution of the (n,) reaction was measured with La by using a germanium detector assembly at J-PARC, and the enhancement factor was obtained. From the result, the measurement time to achieve the most sensitive T-violation search was estimated as 1.4 days, and a 40% polarized La target and a 70% polarized He spin filter whose thickness is 70 atmcm are needed. Therefore high quality He spin filter is developed in JAEA. The measurement result of the (n,) reaction at J-PARC and the development status of the He spin filter will be presented.

Angular distribution of rays from neutron-induced compound states of La

Okudaira, Takuya*; Takada, Shusuke*; Hirota, Katsuya*; Kimura, Atsushi; Kitaguchi, Masaaki*; Koga, Jun*; Nagamoto, Kosuke*; Nakao, Taro*; Okada, Anju*; Sakai, Kenji; et al.

Physical Review C, 97(3), p.034622_1 - 034622_15, 2018/03

https://doi.org/10.1103/PhysRevC.97.034622

Draft genome sequence of sp. ME121, isolated from soil as a mixed single colony with sp. 32K

Fujinami, Shun*; Takeda, Kiyoko*; Onodera, Takefumi*; Sato, Katsuya; Shimizu, Tetsu*; Wakabayashi, Yu*; Narumi, Issey*; Nakamura, Akira*; Ito, Masahiro*

Genome Announcements (Internet), 3(5), p.e01005-15_1 - e01005-15_2, 2015/09

https://doi.org/10.1128/genomeA.01005-15