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Fukushima Project Team, Oarai Research and Development Center; Fukushima Fuels and Materials Department, Oarai Research and Development Center
JAEA-Technology 2014-020, 52 Pages, 2014/07
JAEA-Technology-2014-020.pdf:21.21MB
In this study, a screening study on corrosion phenomena and a preliminary investigation for an evaluation method on long-term integrity of FAs experienced unusual corrosive environment were carried out in views of fundamental features of corrosion. The screening study have led to the following two features of FAs from the viewpoint of the integrity as important phenomena to be further investigated; "fission product confinement of cladding tube" and "structural integrity of FA". In terms of "fission product confinement of cladding tube", it was shown experimentally that influence of the exposure to an unusual corrosive environment was low. On the other hand, in terms of "structural integrity of FA", a concept of experimental methodology for predicting long-term corrosion behavior was preliminary studied for preferentially selected FA local parts composed of different metals.
Fukushima Project Team, Oarai Research and Development Center; Fukushima Fuels and Materials Department, Oarai Research and Development Center; Oarai Research and Development Center, Technology Development Department
JAEA-Technology 2014-014, 60 Pages, 2014/07
JAEA-Technology-2014-014.pdf:57.06MB
We have launched a new research program since 2011 for the evaluation of fission product and actinide release behaviour under the severe accident. Chemical forms of fission products were focused on for more accurate evaluation of source term issues. This report describes the progresses and achievements of the research program in 2013. In order to clarify the Cs and I chemistry in the BWR system during the severe accident which include moderator material B
C, the three research items were configurated: the fission product release kinetics evaluation, the fission product chemical form evaluation and fundamental data acquisition. Basic knowledge on the chemistry of BC and CsI have been obtained by using non-radioactive samples.
Fukushima Project Team, Oarai Research and Development Center
JAEA-Testing 2014-002, 16 Pages, 2014/06
JAEA-Testing-2014-002.pdf:10.27MB
The passive gamma-ray spectrometry of the fuel debris is under development as one of the candidate technologies for nuclear material accountancy in 1F Nuclear Power Plants. Based on the results of TMI accident, 
Eu and 
Ce were selected as the candidates of monitored gamma-ray emitters which were accompanied with nuclear material. The accompanying behavior of Ce with nuclear material under the severe accident was investigated by the high temperature heating test and the chemical equilibrium calculation. The high temperature heating test was carried out under the simulated condition of severe accident that the irradiated fuel was liquidized by the high temperature reaction with molten zircaloy. Ce was found to exist in high concentration at the boundary of reaction between fuel and molten zircaloy.
Fukushima Project Team, Oarai Research and Development Center; Fukushima Fuels and Materials Department, Oarai Research and Development Center
JAEA-Research 2014-007, 32 Pages, 2014/06
JAEA-Research-2014-007.pdf:9.33MB
Primary containment vessel (PCV), reactor pressure vessel and pedestal in Fukushima Daiichi Nuclear Power Station units 1 through 3 have been exposed to severe thermal, chemical and mechanical conditions due to core meltdown events and seawater injections for emergent core cooling. These components will be immersed in diluted seawater with dissolved fission products under irradiation until the end of debris removal. Fresh water injected into the cores contacts with debris to cool, dissolutes or erodes their constituents, mixed with retained water, and becomes "accumulated water" with radioactive nuclides. We have focused the leaching of fission products into the accumulated water under lower temperature (323 K). FUGEN spent oxide fuel segments were immersed to determine the leaching factor of fission product and actinide elements. Since PCV made from carbon steel is one of the most important boundaries to prevent from fission products release, corrosion behavior has been paid attention to evaluate their integrity. Carbon steel specimens were immersion- and electrochemical-tested in diluted seawater with simulants of the accumulated water at 323 K. in order to evaluate the effect of fission products in particular cesium and radiation.