Estimation Of Head Loss Due To Debris Deposition During Loss Of Coolant Accident(LOCA)

During a loss of coolant accident(LOCA)or a main steam line break accident(MSLB)debris of different sorts like particulate,latent fiber or chemical nature might be generated due to jet impingement or ensuing,hot,pressurized steam leaking from the site of damage.This debris gets transported to the emergency core cooling system(ECCS)or the containment recirculation system(CRS)and might get deposited on the sump screens and causes a head loss.Some of these debris particles escape the sump screens and get access to the primary system through the bypass and thereafter challenge the core flow path and cause the head-loss across the fuel assemblies.The deposition of these debris particles in the fuel assemblies generates the possibility of hindering the long term core cooling(LTCC)of the nuclear power plant.The US Nuclear Regulation Commission(NRC)regulates the possibility of a commercial nuclear power plant to be able to maintain long term core cooling in case of a LOCA based event.In light of the aforementioned reasons the study of the debris particles inside the fuel assembly under different conditions becomes necessary to investigate the deposition of these debris particles in the assembly and to point out the critical value of the head loss to avoid a possible core melt down scenario.An experimental test loop has been developed here at the North China Electric Power University by the School of Nuclear Science and Engineering for pressurized water reactor(PWR)and AP1000 fuel assemblies(full scale assemblies)to analyze the head loss generated by the debris particulates,fibrous particles and chemical precipitates added to the loop in different quantities.The purpose of this thesis report is to record the data obtained from the experiments performed on this test loop,organize it and to generate a CFD model to study the critical amounts of debris deposition in the fuel assembly so that the LTCC becomes ineffective.