OECD CSNI ISP 22: post-test analysis of the Loss of Feedwater SPES experiment SP-FW-02 performed by RELAP5/MOD2 code at DCMN of University of Pisa, OECD CSNI Workshop on ISP 22, Rome (I), March 22-23, 1990

The document deals with the description of results obtained by the Relap5 code in the post-test open simulation of the Loss of Feedwater (LOFW) transient experiment performed in the Pressurized Water Reactor (PWR) experimental simulator SPES installed at the Piacenza SIET Research Center in Italy. The Relap5 is the well-known computer code developed at Idaho National Laboratory in US: the code is in use at UNIPI since more than a decade. The SPES loop is an Integral Test Facility (ITF) simulating with full height, full pressure, full linear power a US type 3-loop Westinghouse PWR. The concerned test was selected as International Standard Problem 22 (ISP 22) by OECD/NEA/CSNI (Organization for Economic Cooperation and Development / Nuclear Energy Agency / Committee on the Safety of Nuclear Installations). The document describes the results of the post-test calculation submitted (by UNIPI) to SIET/ENEA (Ente Nazionale Energie Alternative) after the execution of the test and after the submission of the pre-test blind analysis. The activity documented in the present report is called open post-test analysis: the comparison of about 60 calculated time trends with measured data allows an evaluation of the capabilities of the computer code and of the code user team in predicting the scenario of an accident. This is relevant for demonstrating the capabilities in evaluating safety margins of existing NPP, with main reference to PWR (in this case).