Research and development for treatment and disposal technologies of TRU waste; JFY 2010 annual report

Kamei, Gento; Honda, Akira; Oda, Chie; Hirano, Fumio; Ichige, Satoru; Kurimoto, Yoshitaka; Hoshino, Seiichi; Akagi, Yosuke; Sato, Nobuyuki; Takahashi, Kuniaki; et al.

JAEA-Research 2012-010, 80 Pages, 2012/06

JAEA-Research-2012-010.pdf:7.45MB

Based on Japanese governmental policy and general scheme, research and development of geological disposal technology for TRU waste has been proceeding to improve reliability of the safety assessment of the co-locational disposal of TRU waste and of HLW, to expand the basement of generic safety assessment, and to develop the alternative technology to cope with the broad geologic environment of Japan. Japan Atomic Energy Agency is dealing with the assignments in the governmental generic scheme. We report here the progress of the studies at the end of H22 (2010) Japanese fiscal year and their products during the last 5 years. These include (1) evaluation of long-term mechanical stability in the near-field including development of a creep mode of rock and analyses of mechanical behavior of TRU waste repository, (2) performance assessment of the disposal system including cementitious material alteration, bentonite and hostrock alteration with alkaline solution and nitrate effect, and (3) alternative technology development including decomposition of nitrate.

Study on hydrogen embrittlement property of titanium for nuclear fuel waste container

Wada, Ryutaro*; Kurimoto, Yoshitaka*; Fujiwara, Kazuo*; ; Tateishi, Tsuyoshi*; Masugata, Tsuyoshi*

JNC TJ8400 2002-002, 111 Pages, 2002/02

JNC-TJ8400-2002-002.pdf:27.24MB

In geologic disposal system of high-level radioactive waste, confinement by waste container must be assured over a thousand years. Titanium is one of the candidate materials, so it is important to clarify hydrogen embrittlement property under geological environment for the container lifetime prediction. The purpose of this study is to investigate hydrogen embrittlement behavior of titanium under reducing condition. Hydrogen was absorbed into titanium test pieces by electrochemical method, and tensile bending and impact tests were performed for mechanical property research. Under 1000ppm concentration of hydrogen, while distinct degradation of mechanical properties by hydrogen embrittlement occurred on dynamic stress, micro cracks induced by hydride were observed in fracture, but distinct degradation of mechanical properties by hydrogen embrittlement did not occur on static stress. Under low oxygen circumstances, corrosion rates of titanium were estimated 10 micrometer/year by hydrogen absorption method, on the contrary to 10 micrometer/year by gas evolution method. These results indicated hydrogen generated by corrosion of titanium under reducing condition, is almost absorbed into material. Carbon steel is regarded as reinforcement of the titanium nuclear fuel waste container. Magnetite, corrosion product of carbon steel, is considered to accelerate corrosion rate. Contribution of hydrogen evolution reaction to its acceleration is estimated to ca.60%.

Development of bio-denitrification model of nitrates under disposal condition

Masuda, Kaoru*; Murakami, Hiroshi*; Kato, Osamu*; Kato, Ko*; Kurimoto, Yoshitaka; Honda, Akira

no journal, , 

A model of nitrate reduction reaction due to microbial activity was developed as a part of an estimation system for the impacts of nitrate on the safety of a geological disposal system for radioactive wastes. Microbial reaction model, which incorporates a relation between nitrate reduction and consumption of organic materials, has been developed on the basis of data available in the literature and experimental results. The model can interpret the experimental results which were acquired using real groundwater.