Three Mile Island Unit 2 Analysis Exercise: CATHARE Computations of Phases 1 and 2 of the Accident

Within the framework of the Three Mile Island Unit 2 Analysis Exercise, the calculation of phases I and 2 of the accident (0 to 174 min) was performed with the computer code CA THARE 1 and with a preliminary version of CATHARE 1/ICARE. The initial transient (0 to 30 min) is accurately predicted by CATHARE. From the thermal-hydraulic point of view, the remainder of phase 1 has also been very well simulated, even though for the overall problem, this particular part of phase 1 did not prove to be nearly as difficult. The analysis of phase 2 is limited because the computer code does not calculate material relocation. Nevertheless, cladding ballooning and cladding oxidation seem to be correctly predicted.