Analysis of in-core processes during a loss-of-coolant accident in the absence of ECCS

A loss-of-coolant accident in the absence of the emergency core cooling system is analyzed using computer programmes. Programme BOIL is capable of analyzing 3 types of accidents. Results are reported obtained using the programme for a large PWR reactor for the temperature course of fuel sections in the central part of the core and for the effect of the model of core melting on the amount of molten fuel. Programme CHEMLOC-II debugged and modified by the Power Research Institute in Prague is compared to programmes NURLOC 1.0 and BOIL. Using programme CHEMLOC-II, model problems were calculated for various selectable parameters of the WWER type reactors (fuel temperature and cladding temperature) submitted in a graphical representation. The programme was found to be an adequate tool for the analysis of bare core heating; it contains the mathematical models of all significant processes and is not demanding on machine time. (Oy)