Application of RELAP5/MOD3.1 to ATWS Analysis of Control Rod Withdrawal From 1% Power Level (NUREG/IA-0180)

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Publication Information

Date Published: June 2000

Prepared by:
H. Kantee
Fortum Engineering Ltd.
P.O. Box 10
00048 Fortum

Prepared as part of:
The Code Application and Maintenance Program (CAMP)

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

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The RELAP5/MOD3.1 computer code has been applied in the analysis of a regulating control rod group withdrawal from 1 % power level. The analysis has been carried out as an Anticipated Transient Without Scram (ATWS) event.

The analysis is related to an extensive inherent boron dilution study which was performed to Loviisa Nuclear Power Plant (NPP) in the mid 1990's. The main goal of the analysis was to study if during the accident so called boiling-condensing mode develops and thereafter a water plug with low boron concentration is formed in the cold leg loop seal.

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