Assessment of Cathare 2 V2.5 code against boron transport experiments

The document deals with the description of results obtained by the Cathare code in the post-test’ of experiment E2.2 performed in the Pressurized Water Reactor (PWR) experimental simulator PKL installed at the Erlangen AREVA Research Center in Germany. The Cathare is the well-known computer code developed by CEA (Commissariat a l’Energie Atomique) in France in a cooperation with AREVA and EDF: the code is in use at UNIPI since about two decades. The PKL loop is an Integral Test Facility (ITF) simulating with full height, reduced pressure, full linear power a German 4-loop KWU-Siemens PWR. The PKL has four loops. The concerned test is part of a series of a dozen experiments performed in the framework of an Organization for Economic Cooperation and Development / Nuclear Energy Agency / Committee on the Safety of Nuclear Installations (OECD/NEA/CSNI) project where University of Pisa is special member. The concerned experiment deals with boron dilution (diluted boron plugs can be formed in the loop seal of primary system, later on reaching the core and causing the potential of neutron flux excursions and large power peaks - challenging core integrity) and complex Accident Management (AM) situations relevant to improve the AMP (Accident Management Procedures) of existing NPP (Nuclear Power Plants)