Analyses of Mark I drywell shell melt-through

Conference · Fri Jan 01 04:00:00 EST 1988

OSTI ID:6815304

Weingardt, J J; Bergeron, K D

A series of parametric calculations of the thermal attack of molten corium on a steel shell have been performed with the TAC2D computer code in order to elucidate uncertainties about the survivability of the BWR Mark I containment boundary in the event of a core-melt accident. Since TAC2D is a two-dimensional, fixed geometry heat transfer code, it is not possible to capture some of the complexities of the debris-concrete interactions which would occur in this accident. However, the two-dimensional transient nature of the thermal attack is modeled better with TAC2D than is possible with existing debris-concrete interaction codes. The calculations consist of two base cases (one with overlying water and one without) and numerous sensitivity variations about each case. The study is not intended as an uncertainty assessment per se. Rather,it is intended that the results can be combined with assessments of the parameter ranges to assist in the estimation of overall uncertainty about the drywell shell melt-through issue. Sensitivities investigated include mixed versus layered debris, heat transfer parameters, initial corium temperature, chemical heating rate, heat transfer conditions in the gap outside the shell, and corium depth. All but two of the cases resulted in ablation and melt-through of the shell in times that ranged from 8.3 minutes to 75.8 minutes. The two cases that did not melt both involved the mixed debris assumption and enhanced boiling heat transfer to an overlying water pool. 13 refs., 14 figs., 3 tabs.

• Research Organization: Sandia National Labs., Albuquerque, NM (USA)
• DOE Contract Number: AC04-76DP00789
• OSTI ID: 6815304
• Report Number(s): SAND-88-2282C; CONF-881169-1; ON: DE88016343
• Country of Publication: United States
• Language: English

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