Application of RELAP5/MOD2 to Loviisa nuclear power plant overcooling transients

Heikki Kantee, Harri Tuomisto, Vesa Yrjölä

Research output: Contribution to journalArticleScientificpeer-review


The RELAP5/MOD2 computer code has been extensively utilized in calculation of thermal-hydraulic sequences concerning the pressurized thermal shock safety issue in the Loviisa 1 nuclear power plant. The cases analyzed feature stuck-open pressurizer safety valve sequences, small hot-leg breaks, steam line breaks, and, in one case, a primary-secondary leakage. The main purpose of these analyses is to validate and compare the results from the full-scale Loviisa training simulator analyses.

The RELAP5 model is made to the detail allowed by the computer. It includes a description of primary and secondary circuits as well as modeling of the emergency core cooling and control systems.

Single-phase thermal stratification and mixing are essential phenomena when pressurized thermal shock sequences are analyzed. The capabilities of the large system analysis code to predict these phenomena in the reactor circuit are discussed
Original languageEnglish
Pages (from-to)308-315
JournalNuclear Technology
Issue number3
Publication statusPublished - 1990
MoE publication typeA1 Journal article-refereed


Dive into the research topics of 'Application of RELAP5/MOD2 to Loviisa nuclear power plant overcooling transients'. Together they form a unique fingerprint.

Cite this