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Okumura, Taiga*; Yamaguchi, Noriko*; Dohi, Terumi; Iijima, Kazuki; Kogure, Toshihiro*
Microscopy, 68(3), p.234 - 242, 2019/06
Times Cited Count:10 Percentile:68.41(Microscopy)Radiocesium-bearing microparticles (CsMPs), consisting substantially of silicate glass, were released to the environment during the Fukushima nuclear accident in March 2011. We investigated a total of nine CsMPs using transmission electron microscopy (TEM) and inferred the atmosphere in the reactors during the accident. From elemental mapping using energy-dispersive X-ray spectrometry, Fe and Zn showing radial inhomogeneities were found in the CsMPs, in addition to the Cs that had been previously reported. Four of the CsMPs included submicron crystals, which were identified as chromite, franklinite, acanthite, molybdenite, and hessite. The chromium-containing spinels, chromite and franklinite, indicated the presence of ferrous iron (Fe), suggesting that the inside of the reactors was reductive to some extent. Electron energy-loss spectroscopy also confirmed that the CsMPs did not contain boron, and therefore the atmosphere in which they were formed might be boron-free.
Sugino, Hideharu*; Ito, Hiroto*; Onizawa, Kunio; Suzuki, Masahide
Nihon Genshiryoku Gakkai Wabun Rombunshi, 4(4), p.233 - 241, 2005/12
The purpose of this research is to establish the reliability evaluation method of aged nuclear power components for seismic events from a viewpoint of long-term use of the existing light water reactor nuclear power plants. For this purpose, we developed a piping failure probability evaluation code "PASCAL-SC" based on probabilistic fracture mechanics, and a probabilistic seismic hazard evaluation code "SHEAT-FM" for calculating the seismic occurrence probability of a plant site, paying attention to aging such as fatigue crack progress by the stress corrosion cracking and seismic load in primary coolant piping system. We proposed the reliability evaluation method of aged piping for seismic events by combination of these codes. Using this method, we evaluated the reliability of a weld line in the PLR(Primary Loop Recirculation system) piping of the BWR model plant for seismic events.