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Taniguchi, Naoki; ; Kawasaki, Manabu*; Masugata, Tsuyoshi*
JNC TN8400 2001-001, 56 Pages, 2000/12
JNC-TN8400-2001-001.pdf:2.05MB
It is necessary to clear the effects of corrosion products on the corrosion life time of carbon steel overpack for geological isolation of high-level radioactive waste(HLW). Especially, it is important to understand the effects of magnetite because magnetite as a simulated corrosion product is reported to accelerate the corrosion rate of carbon steel. In this study, corrosion tests to reproduce the acceleration of corrosion due to magnetite was performed and the mechanism of the acceleration was investigated to evaluate the effects of magnetite as a corrosion product. Based on the results of experiments, following conclusions are obtained ; (1)Magnetite powder accelerates the corrosion rate of carbon steel. The main reaction of corrosion under the presence of magnetite is the reduction of Fe(III) in magnetite to Fe(II), but the reaction of hydrogen generation is also accelerated. The contribution of hydrogen generation reaction was estimated to be about 30% in the total corrosion reaction based on the experimental result of immersion test under the presence of magnetite. (2)Actual corrosion products containing magnetite generated by the corrosion of carbon steel protect the metal from the propagation of corrosion. The corrosion depth of carbon steel overpack due to magnetite was estimated to be about 1 mm based on the results of experiments. Even if the effect of magnetite is taken into the assessment of corrosion lifetime of overpack, total corrosion depth in 1000 years is estimated to be 33 mm, which is smaller than the corrosion allowance of 40 mm described in the second progress report on research and development for the geological disposal of HLM/ in Japan. It was concluded that the effect of magnetite on the corrosion life time of carbon steel overpack is negligible.
Shiba, Kiyoyuki; Klueh, R. L.*; Miwa, Yukio; Igawa, Naoki; Robertson, J. P.*
Fusion Materials Semiannual Progress Report (DOE/ER-0313/28), p.131 - 135, 2000/06
no abstracts in English
Fukui, Yasutaka; ; Tanimoto, Kenichi; Terunuma, Seiichi
PNC TN9410 94-033, 86 Pages, 1994/01
It is must deceasse the pool risk for the radio active wastes. So it is necessary to decontaminate the wastes low level 
(
500
Sv/h) during control the secendry wastes. Exfoliation velocity (aria of exfoliated paint per unit time) was measured on various cndition changed parameter brasting pressure, feed rate, stand off distance between nozzle and waste surface, angle of nozzle, therefore most suitable condition for decontamination was decide on high-pressure ice brasting method, results are as follows. (1)Feeding dry-ice pellets of most suitable condition was decided on that brasting pressure is 15Kgf/cm
, feed rate is 30%. Same exfolation ability was gained on condition that brasting pressure is 15Kgf/cm, feed rate is 50%. (2)Brasting dry-ice flow of most suitable condition was dicided on that stand off distance is between 50㎜ and 100㎜ angle of nozzle is 30
with vertical. (3)In case of a pipe form, exfolation ability was gained on condition that angle of nozzle is 60 with vertical after the waste was settled on the turn-table and turning. In case of angle iron form, on condition that angle of nozzle was 0 or 60 with vertical. In case of inner can on condition that angle of nozzle was 45 with axis. When these were such small parts as bolts in the barrel basket which leand 30 with vertical and turned 120rpm, exfolation ability was gained on condition that angle of nozzle was vertical. (4)In decontamination hood designing, negative pressure was maintaind in the cell, and freeze preventing heat capacity of ventilation filter (-78C) was calculated at 73kw.