Metallographic and Numerical Investigation of the EC-FOREVER-4 Test
2004 (English)In: ICAPP'04 2004 international congress on advances in nuclear power plants, American Nuclear Society, 2004, 1082-1089 p.Conference paper (Refereed)
Assuming the hypothetical scenario of a severe accident with subsequent core meltdown and formation of a melt pool in the reactor pressure vessel (RPV) lower plenum of a Light Water Reactor (LWR) leads to the question about the behavior of the RPV. One accident management strategy could be to stabilize the in-vessel debris configuration in the RPV as one major barrier against uncontrolled release of heat and radio nuclides. To get an improved understanding and knowledge of the melt pool convection and the vessel creep and possible failure processes and modes occurring during the late phase of a core melt down accident the FOREVER-experiments (Failure Of Reactor Vessel Retention) have been performed at the Division of Nuclear Power Safety of the Royal Institute of Technology Stockholm. These experiments are simulating the behavior of the lower head of the RPV under the thermal loads of a convecting melt pool with decay heating, and under the pressure loads that the vessel experiences in a depressurization scenario. The geometrical scale of the experiments is 1:10 compared to a common LWR. Accompanying the experiments metallographic and numerical work is performed at the Forschungszentrum Rossendorf. An axisymmetric Finite Element model is developed based on the multi-purpose code ANSYS/Multiphysics. First the temperature field within the melt pool and within the vessel wall is evaluated. The transient structural mechanical calculations are then performed applying a creep model which takes into account large temperature, stress and strain variations. For a failure prediction it is necessary to introduce a damage measure. This is done according to a model proposed by Lemaitre. The microstructural investigation gives an insight to the material state of the vessel wall at different positions. This can be compared with the numerical damage value calculated in the Finite Element Model. This paper deals with the experimental, numerical, and metallographic results of the creep failure experiment EC-FOREVER-4, where the American pressure vessel steel SA533B was applied for the lower head. For comparison the results of the experiment EC-FOREVER-3B, build of the French 16MND5 steel, are discussed, too.
Place, publisher, year, edition, pages
American Nuclear Society, 2004. 1082-1089 p.
IdentifiersURN: urn:nbn:se:kth:diva-53588ISBN: 0-89448-680-2OAI: oai:DiVA.org:kth-53588DiVA: diva2:470385
ICAPP'04: 2004 international congress on advances in nuclear power plants, Pittsburgh, PA (United States), 13-17 Jun 2004
QC 201201092011-12-282011-12-282012-01-09Bibliographically approved