Equalisation of Transient Temperature Profile Within the Fuel Pin of a Miniature Neutron Source Reactor (MNSR) During Total Loss of Coolant

Transient temperature distributions in cylindrical fuel element of Ghana Research Reactor-1 (GHARR-1) Miniature Neutron Source Reactor (MNSR) following sudden total loss of cooling have been investigated. The loss of cooling in the reactor core resulting from a blockage of the inner orifice of coolant flow channels was assumed to occur during normal operations and led to sudden shut dow n of the reactor. The objective was to analyse the transient behaviour by solving analytically the heat transfer equation using Bessel functions and also develop from first principle the transient temperature equations for the fuel element. Results obtained during a sudden total lost of cooling showed a high transient temperature distribution at the centre of the fuel element, with the surface of the fuel clad recording the least temperature. The transient temperature distribution decreased from the centre of the fuel element to the surface of the fuel clad and followed a parabolic decay pattern which after increase in tim e follow ed an equalisation pattern. During sudden shut down, since there w as no heat generated and decay heat , the rate at which the fuel elem ent was cooled w as directly proportional to time.