Safety analysis of depressurization accidents in a medium-sized high-temperature gas reactor

Journal Article · Tue Oct 01 04:00:00 EDT 1991 · Nuclear Technology; (United States)

OSTI ID:5508332

Ron, S ^[1]; Tzoref, J ^[2]

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1. Atomic Energy Commission, P.O. Box 7061, Tel Aviv 61070 (IL)
2. Soreq Nuclear Research Center, Yavne 70600 (IL)

In this paper the potential release of fission products during a beyond-design accident in a medium-sized high-temperature gas reactor (the HTR-500) is investigated. The DSNP modular simulation code is used to simulate a depressurization accident as well as the failure of the forced circulation of the decay heat removal systems to actuate. For such an extreme accident, the calculated maximum localized fuel temperature reaches 3040{degrees} C 43 h after the beginning of the accident. During the heatup, 3.4% of the {sup 137}Cs inventory is found to be released from the fuel elements to the primary circuit, and 4.6 {times} 10{sup {minus}2}% is estimated to be released into the environment. The carbon monoxide and helium releases from the graphite matrix prove to be an important factor in sweeping the fission products from the primary circuit. The comparative consequence analysis indicates a much lower risk than in the analogous light water reactor severe accident. A design-base depressurization accident is also investigated at the beginning of the study and involves the operation of one out of the two redundant decay heat removal systems.

• OSTI ID: 5508332
• Journal Information: Nuclear Technology; (United States), Journal Name: Nuclear Technology; (United States) Vol. 96:1; ISSN NUTYB; ISSN 0029-5450
• Country of Publication: United States
• Language: English

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