A survey of recent EBR-II passive safety testing

During the last two years, the testing program at EBR-II has investigated the capabilities of liquid metal reactors (LMRs) to perform vital safety functions passively. In particular the tests have examined post shutdown decay heat removal by natural circulation and passive shutdown of the reactor after accidents which lead to undercooling. The undercooling accidents have been divided into two categories - the loss of flow without scram (LOFWS) (a family of events involving a loss of forced flow through the reactor), and the loss of heat sink without scram (LOHSWS) (a family of events involving a loss of the ability to transfer reactor heat to down stream components which generate steam and electricity.) The type of ''passive shutdown'' that has been examined is caused by natural processes - principally thermal expansion of the reactor structures, fuel and coolant. As used in this paper the term excludes automatic control of power, operator intervention or negative reactivity generated by special in-core devices. 18 refs., 7 figs., 1 tab.