Discussion of the Behaviour of Different RPV-Steels in Vessel Creep Failure Experiments

Considering the hypothetical core melt down scenario for a light water reactor the failure mode of the reactor pressure vessel (RPV) has to be investigated to deter-mine the loadings on the containment. Experimental and numerical work is performed worldwide to get insights about possible consequences. To validate the developed computational tools numerical simulations of Lower Head Failure experi-ments like OLHF or FOREVER are conducted.
An interesting question to be solved in this frame is the reason for the different shape of the failure site even under comparable loading conditions and for the same material: In some experiments like LHF-7 and EC-FOREVER-3B a rough crack surface was found at the failure site while in others like OLHF-1 a rather ductile behaviour was observed resulting in nearly blade-like edges on both sides of the vessel opening.