United States Nuclear Regulatory Commission - Protecting People and the Environment

OLKILUOTO 2 RELAP5/MOD3.2.1.2 Analysis of the Reactor Scram on June 13, 1997 (NUREG/IA-0204)

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Publication Information

Date Published: April 2007

Prepared by:
Heikki Sjövall

Teollisuuden Voima Oy
FIN-27160 OLKILUOTO
FINLAND

Prepared as part of:
The Agreement on Research Participation and Technical Exchange
Under the International Code Assessment and Maintenance Program (CAMP)

Published by:
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

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Abstract

The reactor scram, which occurred at Olkiluoto 2 June 13 in 1997 has been analysed with the RELAP5/MOD3.2.1.2 computer program. The RELAP5 model of the Olkiluoto reactors is based on the model prepared for analysing PSA level 1 success criteria. The purpose of the analysis was to investigate how well RELAP5 is able to calculate the behaviour of process parameters after scram and validate the RELAP5 model of the Olkiluoto reactors.

The main plant features connected with the event are briefly presented. Modelling aspects are discussed regarding the RELAP5 analysis.

The RELAP5 result agrees with the measured reactor water level at the beginning of the transient when the level drops due to the collapse of steam bubbles. Later the level rise due to supply of feed water and the warming up of the reactor water inventory is slower in the RELAP5 analysis than according to the measurements.

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