BEMUSE PHASE II Report: Reanalysis of ISP 13 Exercise, Post Test Analysis of the LOFT L2-5 calculation

The LOFT (Loss of Fluid Test) facility was available in the 70’s and the 80’s at the Idaho National Engineering Laboratory (INL, or INEEL or INEL) for performing pioneering experiments relevant to nuclear reactor safety. Actually LOFT is a 50 MW nuclear reactor originally designed as the ground prototype for a submarine reactor and later on used for experiments relevant to PWR (Pressurized Water Reactors). Namely, the L2-5 test, Large Break Loss of Coolant experiment (LBLOCA), was already used by Organization for Economic Cooperation and Development / Nuclear Energy Agency / Committee on the Safety of Nuclear Installation (OECD/NEA/CSNI) for an International Standard Problem (ISP) with the nuclear core in the early 80’s, i.e. ISP 13. Following the development of an improved set of specifications, the present document deals with the post-test analysis performed by all BEMUSE Phase II participants of the L2-5 experiment and with application of uncertainty methods available by the participants for the determination of uncertainty bands of the individual calculations.