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Journal Articles

Heat conduction analyses on rewetting front propagation during transients beyond anticipated operational occurrences for BWRs

Yonomoto, Taisuke; Shibamoto, Yasuteru; Satou, Akira; Okagaki, Yuria

Journal of Nuclear Science and Technology, 53(9), p.1342 - 1352, 2016/09

AA2015-0497.pdf:1.05MB

https://doi.org/10.1080/00223131.2015.1108882

Times Cited Count：3 Percentile：27.98(Nuclear Science & Technology)

Our previous study investigated the rewetting behavior of dryout fuel surface during transients beyond anticipated operational occurrences (AOOs) for BWRs, which indicated the rewetting velocity was significantly affected by the precursory cooling defined as cooling immediately before rewetting. The present study further investigated the previous experiments by conducting additional experimental and numerical heat conduction analyses to characterize the precursory cooling. For the characterization, the precursory cooling was firstly defined quantitatively based on evaluated heat transfer rates; the rewetting velocity was investigated as a function of the cladding temperature immediately before the onset of the precursory cooling. The results indicated that the propagation velocity appeared to be limited by the maximum heat transfer rate near the rewetting front. This limitation was consistent with results of the heat conduction analysis.

Journal Articles

In-situ monitoring of ion-beam luminescence of Si-O-C(-H) ceramics under proton-beam irradiation

Narisawa, Masaki*; Koka, Masashi; Takeyama, Akinori; Sugimoto, Masaki; Idesaki, Akira; Sato, Takahiro; Hokazono, Hiroki*; Kawai, Taketoshi*; Iwase, Akihiro*

Journal of the Ceramic Society of Japan, 123(9), p.805 - 808, 2015/09

http://doi.org/10.2109/jcersj2.123.805

Journal Articles

Quantitative risk trends deriving from PSA-based event analyses; Analysis of results from U.S.NRC's accident sequence precursor program

Watanabe, Norio

Nihon Genshiryoku Gakkai Wabun Rombunshi, 3(4), p.396 - 406, 2004/12

https://doi.org/10.3327/taesj2002.3.396

The U. S. Nuclear Regulatory Commission has been carrying out the Accident Sequence Precursor (ASP) Program to identify and categorize precursors to potential severe core damage accident sequences using the PSA technique. The ASP Program has identified a lot of risk significant events as precursors that occurred at U. S. nuclear power plants. The results from the ASP Program include valuable information that could be useful for obtaining risk significant insights and for monitoring risk trends in nuclear power industry. The present study examines and discusses quantitative risk trends for the industry level, using two indicators, that is, the occurrence frequency of precursors and the annual core damage probability, deriving from the ASP analysis results. It is shown that the core damage risk at U.S. nuclear power plants has been lowered and the likelihood of risk significant events has been remarkably decreasing. Also, the present study demonstrates that two risk indicators used here can provide quantitative information useful for monitoring risk trends in nuclear power industry.

Journal Articles