In-vessel melt retention as a severe accident management strategy for the Loviisa Nuclear Power Plant

Conference · Sat Feb 01 04:00:00 EST 1997

OSTI ID:467946

Kymaelaeinen, O; Tuomisto, H ^[1]; Theofanous, T G ^[2]

---

1. IVO International Ltd., Vantaa (Finland)
2. Univ. of California, Santa Barbara, CA (United States)

The concept of lower head coolability and in-vessel retention of corium has been approved as a basic element of the severe accident management strategy for IVO`s Loviisa Plant (VVER-440) in Finland. The selected approach takes advantage of the unique features of the plant such as low power density, reactor pressure vessel without penetrations at the bottom and ice-condenser containment which ensures flooded cavity in all risk significant sequences. The thermal analyses, which are supported by experimental program, demonstrate that in Loviisa the molten corium on the lower head of the reactor vessel is coolable externally with wide margins. This paper summarizes the approach and the plant modifications being implemented. During the approval process some technical concerns were raised, particularly with regard to thermal loadings caused by contact of cool cavity water and hot corium with the reactor vessel. Resolution of these concerns is also discussed.

• Research Organization: Nuclear Regulatory Commission, Washington, DC (United States). Office of Nuclear Regulatory Research; Brookhaven National Lab., Upton, NY (United States)
• OSTI ID: 467946
• Report Number(s): NUREG/CP--0157-VOL.2; CONF-9610202--Vol.2; ON: TI97004274
• Country of Publication: United States
• Language: English

Related Subjects

21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS
22 GENERAL STUDIES OF NUCLEAR REACTORS
COOLING
CORIUM
LOVIISA-1 REACTOR
LOVIISA-2 REACTOR
MELTDOWN
PRESSURE VESSELS
RETENTION
SAFETY ANALYSIS