Simulation of the fuel rod bundle test QUENCH-03 using the integral code ASTEC V2

Failure of the main and emergency cooling-systems can lead to an accident with severe core degradation even with core meltdown. To prevent total meltdown of the uncovered and overheated core reflooding with water is an unavoidable accident management measure. The fast supply of water and the resulting increased available amount of steam can lead to crack formations and break up of the oxide layer of the fuel rods. The additionally exposed surface could result in an increased release of hydrogen due to a supplementary exothermal zirconium- steam-oxidation reaction. Within the frame of the QUENCH test-program - realised by FZK - loss of coolant accidents in LWR (Light Water Reactor) are analysed using an experimental reactor core to determine the produced amount of hydrogen, the so-called hydrogen source term. Additionally, the behaviour of the bundle with different absorber rod and cladding materials is being analysed. Based on the post-test calculations of the QUENCH tests with the severe accident code system ASTEC the capability of the code can be established and evaluated. In the following the post-test calculations of the QUENCH-03 test with ASTEC V2 are discussed. (orig.)