Investigation of the channel disassembly behaviour of Indian 200MWe PHWR - A numerical approach

In absence or non-functioning of a failsafe system, the postulated accident in Pressurised heavy water nuclear reactor may lead to severe degradation of structural integrity of channels. It is utmost important to discover the nature of channel disassembly or sagging behaviour following the loss of channel integrity. An experimental facility is presently being developed at Indian Institute of Technology Roorkee (IIT R), India to study such a severe event. The experiments are grouped under two categories, one being study under inert environment to check channel deformation due to material flow at the higher temperature and other one is the investigation on the effect of an metal oxidation in presence of a steam surrounding. The Latter is the case similar to an actual condition exists in a reactor core under the postulated accident scenario. Initially, experiments will be carried out on a single channel, and later it will be extended up to three channels arranged one below another. This paper discusses various aspects considered towards the facility development. A detailed numerical analysis of a single channel sagging in an inert environment is carried out. It provides information beforehand about the deformation pattern which has helped in designing the experimental facility. The numerical model was simulated using direct coupled fields approach inside finite element domain to get a preliminary insight into structural and thermal coupled response on the channel deformation.