Participation in the OECD/NEA/NSC TMI-1 PWR MSLB Benchmark - Phase 1: 0-D neutronics, Final Results

A research activity started at the end of 80’s was substantiated within the context of the participation of the TMI-1 (Three Mile –Unit 1) Benchmark. The activity deal with the coupling between one dimensional thermal-hydraulic system code Relap5 and the three-dimensional neutron-physics code (the Parcs code made available from the Purdue University in US was successfully coupled, following attempts in Pisa to couple Relap5 with MODICO code). The TMI-1 is the twin reactor of the TMI-2 which had the core destroyed by the 1979 accident (because of this reactor data, owned by the industry, were made of public domain – to identified research groups including University of Pisa – making possible this activity). The activity is performed in the framework of the Organization for Economic Cooperation and Development / Nuclear Energy Agency / Nuclear Science Committee (OECD/NEA/NSC) and was leaded by Sartori E (OECD), Ivanov K. (PSU, US), Langenbuch L. (GRS, G) and D’Auria (UNIPI, I). The pioneering activity at UNIPI (University of Pisa), in cooperation with University of Zagreb, allowed the achievement of the first coupled results in the world with reference to the TMI-1 Main Steam Line Break (MSLB) transient. The importance of suitable sets of neutron physics ‘cross sections’ made available by PSU (Pennsylvania State University) must be noted. The activity demonstrate the importance of coupled 3D NK-TH (Neutron Kinetics – Thermal-hydraulics) codes for the evaluation of safety and safety margins in existing and new nuclear reactors. The present document deals with Phase 1 of the OECD/NEA/NSC project