Heat removal from RBMK reactor core using non-regular means

Abstract

RBMK type reactor is a boiling light-water-reactor with a graphite moderator. Several important design features of RBMK are unique and very complex compared with: the fuel assemblies are located in individual channels rather than a single pressure vessel, these fuel channels are placed in a massive graphite moderator block; the rods of reactor control and protection system are placed in different channels, parallel to the fuel channels in graphite moderator block. Such design provides additional opportunity for heat removal from the reactor in the cases of beyond design-basis accidents. This paper discusses possibility of heat removal from the RBMK-1500 core using weak heat conduction mechanisms: heat removal from outer surface of drum separators and steam – water piping using air ventilation means; heat removal from graphite stack using direct water supply into reactor cavity; heat removal from fuel channels through the core graphite structures by control rods cooling system; heat removal in loss of long term cooling case using de-pressurisation of the reactor coolant system and water supply using complex of non-regular means. The provided analyses discuss advantages and capacities of these different means.