Temperature Distribution and Heat Transfer in a Drained RBMK-1000 Fuel Channel During a Severe LOC Accident

Heat transfer in a drained channel of RBMK-1000 as it heats up during a severe beyond design basis LOC accident with destruction of the core is considered. Radiative heat exchange of a FA with a channel tube, in conjunction with molecular heat exchange in FA and the graphite column enclosing the channel is calculated. This is accomplished by means of precision models of heat transfer, based on ray tracing with adjustable spatial resolution. The calculated temperature behavior is determined by the well-known effect of the heat capacity of a graphite column, in the present case under the conditions of a beyond design basis accident, due to which the core and FA slowly heat up. This has the result that the fuel-rod cladding can heat up while the channel almost completely drained and in the absence of a developed steam-zirconium reaction. The obtained results could be helpful in building simplified approaches to modeling heat transfer in a RBMK-1000 core during a severe accident.