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Journal Articles

Development of dose evaluation method considering radionuclides migration on the surface of the site for confirmation of completion of decommissioning

Miwa, Kazuji; Namekawa, Masakazu*; Shimada, Taro; Takeda, Seiji

MRS Advances (Internet), 7(7-8), p.165 - 169, 2022/03

https://doi.org/10.1557/s43580-022-00212-7

We have developed evaluation method of radiocesium (RCs) migration by surface runoff and soil erosion in considering vertical distribution of RCs in initial contaminated soil and concentration of RCs in different particle size. RCs migration on ground surface during single year has been evaluated in virtual site contaminated uniformly by Cs-137. As a result, RCs has concentrated in the impoundment, and 0.18% of total inventory in the site migrated into the sea. These results suggest that surface migration of RCs effects increasing of external exposure at impoundment and internal exposure from ingestion of marine product.

Journal Articles

Localized-impact damage caused by proton bombarding in mercury target

Futakawa, Masatoshi; Kogawa, Hiroyuki; Ishikura, Shuichi*; Kudo, Hisaaki*; Soyama, Hitoshi*

Journal de Physique, IV, 110, p.583 - 588, 2003/09

A liquid-mercury target system for the MW-scale target is being developed in the world. The moment the proton beams bombard the target, pressure waves will be generated in the mercury by the thermally shocked heat deposition. Provided that the negative pressure generates through its propagation in the mercury target and causes cavitation in the mercury, there is the possibility for the cavitation bubbles collapse to form pits on the interface between the mercury and the target vessel wall. In order to estimate the cavitation erosion damage, Split Hopkinson Pressure Bar (SHPB) tests impact tests were performed to impose the impact pressure to the interface between mercury and solid metals. In particular, the surface hardening treated samples: Kolsterising, some coatings are investigated. As results, it is confirmed that the pitting damage is suppressed by surface hardening treatments and relative hardness appeared to be a good correlating parameter on impact erosion resistance.

Journal Articles

Impact behavior of mercury droplet

Date, Hidefumi*; Futakawa, Masatoshi; Ishikura, Shuichi*

Jikken Rikigaku, 2(2), p.103 - 108, 2002/06

https://doi.org/10.11395/jjsem2001.2.103

In order to examine the impact behavior of mercury, which is one of important key-issues in a facility for high intensity neutron sources, the falling and colliding profiles of mercury droplets were recorded by high-speed video recorder. The impact force was also measured using the strain gage glued on an elastic bar. The falling mercury droplet oscillated between a prolate spheroid and an oblate one, repeatedly. The regathering and jumping of mercury at the collision point on the impact face of the target were observed after impact because of the strong surface tension of mercury. The impact force of mercury droplet was in proportion to the impact velocities and the square root of the potential energy. Scince the non-dimensional duration time K that obtained experimentally is independent of the impact velocity and the size of the droplet, the mean applied stress due to the mercury droplet against the target is easily predictable by the equatiion using K value and the impact velocity is known.

Journal Articles