Phase analysis of simulated nuclear fuel debris synthesized using UO, Zr, and stainless steel and leaching behavior of the fission products and matrix elements

Tonna, Ryutaro*; Sasaki, Takayuki*; Kodama, Yuji*; Kobayashi, Taishi*; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Kumagai, Yuta; Kusaka, Ryoji; Watanabe, Masayuki

Nuclear Engineering and Technology, 55(4), p.1300 - 1309, 2023/04

https://doi.org/10.1016/j.net.2022.12.017

Simulated debris was synthesized using UO, Zr, and stainless steel and a heat treatment method under inert or oxidizing conditions. The primary U solid phase of the debris synthesized at 1473 K under inert conditions was UO, whereas a (U,Zr)O solid solution formed at 1873 K. Under oxidizing conditions, a mixture of UO and (Fe,Cr)UO phases formed at 1473 K whereas a (U,Zr)O solid solution formed at 1873 K. The leaching behavior of the fission products from the simulated debris was evaluated using two methods: the irradiation method, for which fission products were produced via neutron irradiation, and the doping method, for which trace amounts of non-radioactive elements were doped into the debris. The dissolution behavior of U depended on the properties of the debris and aqueous medium the debris was immersed in. Cs, Sr, and Ba leached out regardless of the primary solid phases. The leaching of high-valence Eu and Ru ions was suppressed, possibly owing to their solid-solution reaction with or incorporation into the uranium compounds of the simulated debris.

Study on engineering technologies in the Mizunami Underground Research Laboratory (FY 2015); Development of design and construction planning and countermeasure technologies (Contract research)

Toguri, Satohito*; Kobayashi, Shinji*; Tsuji, Masakuni*; Yahagi, Ryoji*; Yamada, Toshiko*; Matsui, Hiroya; Sato, Toshinori; Mikake, Shinichiro; Aoyagi, Yoshiaki

JAEA-Technology 2017-005, 43 Pages, 2017/03

JAEA-Technology-2017-005.pdf:4.4MB

The study on engineering technology in the Mizunami Underground Research Laboratory (MIU) project roughly consists of (1) development of design and construction planning technologies, (2) development of construction technology, (3) development of countermeasure technology, (4) development of technology for security, and (5) development of technologies regarding restoration and mitigating of the excavation effect. In FY2015, as a part of the important issues on the research program, water-tight grouting method has been developed. Grouting methods utilized in the MIU were evaluated and the post-excavation grouting at the -500m Access/Research Gallery-South was planned based on these evaluation results. Also, technology development from the viewpoint of geological disposal was summarized, and information on the alternative method to the grouting method was collected and organized.

Analysis of excavation cycle time during sinking of the ventilation shaft at the Mizunami Underground Research Laboratory

Sanada, Hiroyuki; Sato, Toshinori; Horiuchi, Yasuharu*; Mikake, Shinichiro; Okihara, Mitsunobu*; Yahagi, Ryoji*; Kobayashi, Shinji*

Proceedings of 8th Asian Rock Mechanics Symposium (ARMS-8) (USB Flash Drive), 7 Pages, 2014/10

The Japan Atomic Energy Agency (JAEA) is implementing the Mizunami Underground Research Laboratory (MIU) Project to establish the scientific and technological basis for the geological disposal of High-level Radioactive Waste (HLW) in crystalline rocks. Excavation cycle times were recorded during the Ventilation Shaft sinking and compared with the planned excavation cycle times for evaluation of the baseline design plan. This included review of the cycle times in the design process and comparison with the actual construction results. The recorded results indicate that actual cycle times were twice as long as the design plan. This paper describes discussions on differences in cycle times between the design and result.

Basic vacuum test of 500-kV photocathode DC gun components at KEK

Yamamoto, Masahiro*; Uchiyama, Takashi*; Miyajima, Tsukasa*; Honda, Yosuke*; Sato, Kotaro*; Matsuba, Shunya*; Saito, Yoshio*; Kobayashi, Masanori*; Kurisu, Hiriki*; Hajima, Ryoichi; et al.

Proceedings of 7th Annual Meeting of Particle Accelerator Society of Japan (DVD-ROM), p.717 - 720, 2010/08

http://www.pasj.jp/web_publish/pasj7/proceedings/P_4PM/P_EH_4PM/WEPS124.pdf

A 500-kV photocathode DC electron gun which can supply the beam of a low emittance and a high average current has been developed in collaboration with KEK, JAEA, Hiroshima Univ., Nagoya Univ. and Yamaguchi Univ. The vacuum of the gun chamber has to be lower Extreme High Vacuum for maintain cathode-life time. A titanium chamber and new material of ceramic were employed to reduce outgassing rate. The result of outgassing rate of the gun chamber is described in this report.

Design of a 500kV electron gun for ERL light source at KEK

Yamamoto, Masahiro*; Honda, Yosuke*; Miyajima, Tsukasa*; Uchiyama, Takashi*; Kobayashi, Masanori*; Muto, Toshiya*; Matsuba, Shunya*; Sakanaka, Shogo*; Sato, Kotaro*; Saito, Yoshio*; et al.

Proceedings of 6th Annual Meeting of Particle Accelerator Society of Japan (CD-ROM), p.860 - 862, 2009/08

A newly 500 kV electron gun (2nd - 500 kV gun) for an ERL light source is designed at KEK. A new concept and state of-the-art technologies of vacuum system, ceramic insulators, high voltage power supply, photocathode and preparation system will be employed. The details are described in this report.

Performance of the undulator for JAERI FEL project

Nagai, Ryoji; Kobayashi, Hideki*; Sasaki, Shigemi; Sawamura, Masaru; Sugimoto, Masayoshi; ; Kikuzawa, Nobuhiro; Okubo, Makio; Minehara, Eisuke; *; et al.

Nuclear Instruments and Methods in Physics Research A, 358, p.403 - 406, 1995/00

https://doi.org/10.1016/0168-9002(94)01294-6

no abstracts in English

Magnetic anisotropy in isovalent spin =7/2 family EuIn (=Ni, Pd, Pt)

Kaneko, Koji; Ikeda, Shugo*; Frontzek, M. D.*; Hanashima, Takayasu*; Nakao, Akiko*; Kiyanagi, Ryoji; Ohara, Takashi; Homma, Yoshiya*; Kobayashi, Hisao*; Yamagami, Hiroshi

no journal, , 

Uranium leaching from simulated fuel debris prepared from UO and stainless steel

Kumagai, Yuta; Kusaka, Ryoji; Nakada, Masami; Watanabe, Masayuki; Kirishima, Akira*; Akiyama, Daisuke*; Sato, Nobuaki*; Sasaki, Takayuki*; Kobayashi, Taishi*

no journal, , 

Fuel debris generated due to nuclear severe accidents is expected to contain a wide variety of uranium compounds. In this project, we have investigated chemical stability of simulated fuel debris containing elements from stainless steel (Fe, Cr, and Ni) against exposure to water. The simulated debris was prepared from the powders of UO and SUS304 by heating the mixed powder at 1200 C for 1 h under continuous gas flow of 2% O in Ar. The produced powder was characterized by XRD, SEM-EDX, Raman micro-spectroscopy, and Mssbauer spectroscopy. The series of characterization revealed that the simulated debris comprised U(Fe,Cr)O, UO, and Fe(III) oxides. Then, the simulated debris was exposed to pure water for 30 days. The same leaching test of UO was performed for comparison. The chemical analysis of leached metals demonstrated that the U elution from the simulated debris was significantly lower than that from UO. In addition, Fe, Cr, and Ni were under quantitation limit as well. The Raman spectra showed that the exposure to water induced insignificant change in the spectra of the simulated debris, while the Raman band structure of UO seemed to become slightly unclear after 30 days immersion.

Leaching behavior of simulated fuel debris in the UO-SUS system prepared by irradiation or tracer doping method

Sasaki, Takayuki*; Tonna, Ryutaro*; Kobayashi, Taishi*; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Kumagai, Yuta; Kusaka, Ryoji; Watanabe, Masayuki

no journal, , 

Research on the stability of fuel debris consisting of oxides and alloys, 10; Leaching behavior of nuclides from simulated fuel debris in the UO-Zr-SS system; Irradiation or addition method

Sasaki, Takayuki*; Tonna, Ryutaro*; Kobayashi, Taishi*; Akiyama, Daisuke*; Kirishima, Akira*; Sato, Nobuaki*; Watanabe, Masayuki; Kumagai, Yuta; Kusaka, Ryoji

no journal, , 

We synthesized simulated fuel debris which containing stainless steel and zirconium. The fission of Uranium by the irradiation of thermal neutron or non-radioactive elements was fed in the simulated fuel debris as fission products (FP), and the sample was immersed in pure water or artificial sea water. In this presentation, we would report the behavior of the solubility of the FP and the interpretation of its results.