“…There have been many transient overpower tests of EBR-II driver fuel elements 41 " 44 to study failure mode and threshold, effect of prior irradiation on failure thresholds, postfailure movement of fuel and coolant, and sodium expulsion and reentry. These tests are not reviewed in the same detail as the ceramic fuel tests, because the metal fuel elements differ so from advanced fuel elements that few behavior similarities can be expected.…”