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Tamaki, Hitoshi; Hamaguchi, Yoshikane; Yoshida, Kazuo; Muramatsu, Ken
Proceedings of International Conference on Nuclear Energy System for Future Generation and Global Sustainability (GLOBAL 2005) (CD-ROM), 6 Pages, 2005/10
A PSA procedure for MOX fuel fabrication facilities is being developed at the JAERI. This procedure consists of four steps, which are hazard analysis, accident scenario analysis, frequency evaluation and consequence evaluation. The proposed procedure is characterized by the hazard analysis step. The Hazard analysis step consists of two sub-steps. In the first sub-step, a variety of functions of equipment composing the facility are analyzed to identify potential abnormal events exhaustively. In the second sub-step, these potential events are screened to select abnormal events by using a risk matrix based on the rough estimation of likelihood and maximum unmitigated release of radioactive material. One of the unique technical issues in this research is the estimation of likelihood of criticality event. A method is also proposed as a part of PSA procedure taking into consideration of failure of a computerized control system for MOX powder handling process. The applicability of the PSA procedure was demonstrated through the trial application of it to a model plant of MOX fuel fabrication facility.
Hidaka, Akihide; Kudo, Tamotsu; Ishikawa, Jun; Fuketa, Toyoshi
Journal of Nuclear Science and Technology, 42(5), p.451 - 461, 2005/05
Times Cited Count：6 Percentile：39.62(Nuclear Science & Technology)The radionuclide release from MOX under severe accident conditions was investigated in VEGA program to contribute to the technical bases for safety evaluation including PSA for LWR using MOX. The MOX specimens irradiated at ATR Fugen were heated up to 3123K in helium at 0.1 and 1.0MPa. The release of volatile FP was slightly enhanced below 2200K compared with that of UO
. The volatile FP release at elevated pressure was decreased as in the case with UO. The total fractional release of Cs reached almost 100% while almost no release of low-volatile FP even after the fuel melting. The release rate of plutonium above 2800K increased rapidly although the amount was small. Since the existing models cannot predict this increase, an empirical model was prepared based on the data. There is no large difference in FP inventories between UO and MOX, and the fractional releases from MOX can be mostly predicted by the model for UO. This suggests that the consequences of LWR using MOX are mostly equal to those using UO from a view point of risks.
Hidaka, Akihide; Kudo, Tamotsu; Fuketa, Toyoshi
Transactions of the American Nuclear Society, 91, p.499 - 500, 2004/12
The radionuclides release from MOX under severe accident conditions was investigated in the VEGA program to prepare the technical bases for safety evaluation including PSA for LWR using MOX. The MOX specimen irradiated at ATR Fugen was heated up to 3123K in He at 0.1MPa. The Cs release started at about 1000K and was enhanced below 2200K compared with that of UO. The possible reason is due to the formation of cracks connected to the high burn-up Pu spots. The total fractional releases were evaluated by alpha-ray, gamma-ray and ICP-AES and compared with the ORNL-Booth model. Although the model was prepared based on the tests with UO, the predictions are in reasonable agreement with the measurements. The VEGA test showed that the total releases from MOX are almost the same as those from UO under extremely severe accident conditions. This indicates that the consequences of LWR using MOX are mostly equal to those using UO. The effect of difference between MOX and UO on the consequences will be systematically investigated using the JAERI's source term code, THALES-2.
Sasajima, Hideo; Fuketa, Toyoshi; Nakamura, Takehiko; Nakamura, Jinichi; Kikuchi, Keiichi*
Journal of Nuclear Science and Technology, 37(5), p.455 - 464, 2000/05
no abstracts in English
Saito, Hioraki*; Iriya, Yoshikazu*
JNC TJ8440 99-003, 156 Pages, 1999/03
no abstracts in English
; Obata, Shinichi; Nogami, Yoshitaka; ; Seki, Masayuki; ;
PNC TN8410 96-198, 235 Pages, 1996/06
None
93JAERI-Tech 94-021, 79 Pages, 1994/09
no abstracts in English
JAERI-M 92-155, 42 Pages, 1992/10
no abstracts in English
PNC TN1420 91-002, 76 Pages, 1990/01
An annual plan of FBR safety research had been made since 1986 by Japanese Nuclear Safety Commission. This plan focuses on the safety philosophy which fully utilizes the intrinsic characteristics of FBRs and which implements the safety technologies of FBRs. Items examined for establishing the safety philosophy includes : * defense-in-depth * safety grade classification * multi-barriers against radioactivity, and * severe accidents. In selecting research items, the following four fields of research were identified in relation to the safety philosophy : 1) research relating to safety design and safety evaluation principles,2) research on accident prevention and mitigation,3) research on (design basis) accidents evaluation, and 4) research on severe accidents. ATR safety research plan has been also revisedz. Its three research fields are 1) research on normal operations and anticipated operational occurrences, 2) research on accident conditions, and 3) research on severe accidents. T
