Performance of breached LMFBR fuel pins during continued operation

Four EBR-II tests were used to scope the behavior of breached mixed-oxide pins. After release of stored fission gas, delayed-neutron signals were large and easily detected, although not readily correlated with exposed fuel area. No problems were met during reactor operation or fuel handling. Fuel-sodium reaction caused only narrow breaches which released minute amounts of fuel and fission products; the reaction product appeared dense and non-friable. These initial results indicated LMFBR oxide pins could have considerable potential for operating in the breached mode.