Pebble bed reactor emergency shut=down and decay heat removal - by discharge of core into water filled tank esp. after other safety systems fail

摘要

A method for the emergency shutdown and removal of decay heat of a gas-cooled, high-temp reactor (pebble bed reactor), where new spherical fuel elements are fed in at the top and irradiated elements discharged from a pipe at the bottom, is as follows. The reactor core is discharged under gravity through the fuel discharge pipe into a water-filled collecting basin located at a lower level than the reactor core. This core discharge procedure may be triggered by hand, or automatically if more conventional shutdown and heat removal systems, e.g. comprising shutdown rods, have failed. Pref, a single collecting tank, large enough to receive the entire core, is used. Used as a shutdown system of "last resort", if other more conventional systems should fail.