APPLICATION OF THE SIMPLE FUEL PIN TRANSIENT AND MELTING MODEL TO THERMAL-HYDRAULICS IN LMFBR SUBASSEMBLY

A simple conduction model with phase change has been developed for the transient analysis of a reactor fuel pin based on lumped parameter techniques. The purpose of this analysis is to provide a simple useful tool to obtain the general information about fuel and clad leaning into the cooling transients and melting. Such a simple fuel and clad thermal transient model is particularly useful to multichannel analysis where conventional conduction computer codes require considerable computing time and storage space. At the present, this formulation is being employed for the analysis of sodium thermohydraulics, sodium voiding, and melting of cladding and fuel in a subassembly of a fast reactor core. A detailed analysis of the predicted coolant, fuel and cladding thermal transients leading into sodium voiding and fuel pin melting has been made in comparison with the results of various in-pile experiments and with the predictions from the existing more complicated codes. © 1979.