Recriticality energetics of a hypothetical water reflood accident in a damaged light water reactor
The Three Mile Island (TMI-2) accident in 1979 resulted in approximately 45% of the fuel collapsing into an irregularly-shaped debris bed near the center of the core, while some of the molten material flowed into the lower dome of the reactor vessel where it solidified. The immediate cause of this severely degraded geometry was loss of coolant and subsequent heatup of the fuel from decay heat. The neutron chain reaction had shut down prior to fuel relocation (below 5 wt% {sup 235}U enrichment, fast-spectrum criticality is impossible). After the system had cooled sufficiently to allow for reintroduction of water, the core was reflooded to remove remaining decay heat; to ensure stable shutdown, the reflood water was heavily berated (in excess of 3000 ppm). One scenario considered was the potential for increased nuclear reactivity of the debris bed with the reintroduction of water. This was guarded against by the operators using heavily berated reflood water. If the reflood water is insufficiently berated, and the system goes recritical during reflood, it is important to estimate the energy release. Is the event minor (reactor containment survives), or is the event major (such as the Chernobyl accident)?
- Sponsoring Organization:
- USDOE Assistant Secretary for Environment, Safety, and Health, Washington, DC (US)
- DOE Contract Number:
- AC06-96RL13200
- OSTI ID:
- 16911
- Report Number(s):
- HNF-SA-3189-FP; ON: DE98059756; BR: EH000000; ON: DE98059756; BR: EH000000; TRN: US0111105
- Resource Relation:
- Other Information: PBD: 24 Apr 1997; Supercedes report DE98059756; PBD: 24 Apr 1997
- Country of Publication:
- United States
- Language:
- English
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