APPLICATION OF RELAP5 MOD3 TO THE EVALUATION OF LOSS OF FEEDWATER IN TEST FACILITIES AND IN NUCLEAR-PLANTS

The present paper deals with the evaluation of the capabilities of the Relap5/Mod3 code (7J version) in simulating the phenomena Occurring f ollowing the application of an accident management procedure in the ca se of a loss of feedwater transient in PWR type nuclear plants; the ac tuation of high pressure injection system is not foreseen in the prima ry side. The proposed procedure is based upon the intervention of auxi liary feedwater after the occurrence of dryout in the core region. Thi s is a consequence of primary inventory loss from the pressurizer reli ef valve. Two experiments performed in Lobi and Spes facilities are th e reference data base for the activity. Post-test analyses were perfor med by using the above code to evaluate the differences with respect t o Relap5/Mod2 code results as well. Nuclear plant performance was pred icted with reference to the same plant scenario.