Latest findings from the OECD Rasplav Project
During the late phase of a severe accident in a light water reactor (current and future designs of BWRs, PWRs and VVERs), a significant amount of core material may relocate downward to the lower head of the reactor vessel. If molten core materials were to relocate to the lower head of the reactor pressure vessel (RPV), a molten pool consisting primarily of a mixture of ZrO{sub 2} and UO{sub 2} and some combination of a metal would form on the lower head. A solid crust of material would form around the boundaries of the pool, but internal heat generation resulting from radioactive decay of fission products would assure that most of the pool remains molten. In fact, the molten pool would undergo significant internal natural convection which would reach steady state conditions in about a few hours. Detailed understanding of all aspects of this natural convection process, in conjunction with the thermal boundary conditions imposed on the outer surface, determines the fraction of the total heat dissipation that is transferred through the upper crust to the inside of the reactor vessel by radiative heat exchange and the fraction which must be conducted through the wall of the reactor vessel lower head. This distribution is critical in determining whether and under what conditions the molten material can be cooled and retained in the reactor pressure vessel. The OECD Rasplav Project was established in 1994 as a three year program to study molten pool behavior and its interactions with structural materials in the lower head. This paper reviews the establishment of the project, its initial studies and proposed experimental testing, and the construction, preparation, and actual testing of a chamber of corium heated to well above liquid temperature.
- Research Organization:
- US Nuclear Regulatory Commission (NRC), Washington, DC (United States). Office of Nuclear Regulatory Research; Brookhaven National Lab. (BNL), Upton, NY (United States)
- OSTI ID:
- 468635
- Report Number(s):
- NUREG/CP-0157-Vol.1; CONF-9610202-Vol.1; ON: TI96014720; TRN: 97:008512
- Resource Relation:
- Conference: 24. water reactor safety information meeting, Bethesda, MD (United States), 21-23 Oct 1996; Other Information: PBD: Jan 1997; Related Information: Is Part Of Proceedings of the twenty-fourth water reactor safety information meeting. Volume 1: Plenary session; High burnup fuel; Containment and structural aging; Monteleone, S. [comp.] [Brookhaven National Lab., Upton, NY (United States)]; PB: 372 p.
- Country of Publication:
- United States
- Language:
- English
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