Applications of the integral code ASTEC V1 were performed during the first 18 months of SARNET to two different severe accident sequences in French PWR 900 MWe. FRAMATOME-ANP SAS and ENEA compared ASTEC V1.1 results for a scenario of total loss of steam generator feedwater with results of respectively MAAP4 and MELCOR 1.8.5 codes. This is the first time that a MELCOR 1.8.5 input deck is available for a French PWR 900. The complete ASTEC V1.1 calculations coupling all modules ran correctly until their end, i.e. simulating fission product, ex-vessel and containment iodine phenomena. But up to now the comparison of main results has focused on primary circuit thermalhydraulics, core degradation and containment thermalhydraulic behaviour. In parallel, IRSN compared in-vessel results of ASTEC V1.1 with the reference mechanistic IRSN code ICARE/CATHARE V1 on a scenario of a 6” break in cold leg, with only accumulators available. The validation efforts on PWR are illustrated by ENEA work on the two first phases of TMI-2 accident.
After release in July 05 of the latest version ASTEC V1.2, similar comparisons will be performed again with this version. The next stage of work aims to analyse with more details the origin of discrepancies on in-vessel results and to extend the comparison to ex-vessel and fission product behaviour.
(1) : FRAMATOME-ANP SAS
(2) : ENEA
(3) : IRSN