In this study, we analyzed the passive safety features of a small simplified pebble bed
reactor with an accumulative fuel loading scheme for decay heat removal after reactor
shutdown without a forced cooling system. The accumulative fuel loading scheme has
unique characteristics that make it different from Multipass or Once Through Then Out
(OTTO) fuel loading schemes. In this fueling scheme, significant changes of power
distributions occur in a limited area at the top of the reactor core, where new fuel pebbles are …