Results of UO₂ Diagnositic Tests for Run Beyond Cladding Breach in EBR-2

Pre-defected uranium dioxide fuel elements were irradiated in EBR-II to determine the response of the fission-product-monitoring systems. In particular, the tests were performed to indicate whether the amount of oxide fuel exposed to the primary sodium could be estimated by monitoring, with the fuel-element-rupture detector (FERD), delayed neutrons (DN's) emitted from bromine and iodine isotopes in the sodium. Elements with defect areas of 0.005 and 0.20 cm sq. were irradiated consecutively in April and June 1977. Post-irradiation examination of the elements showed that an unexpectedly large amount of uranium dioxide/sodium chemical reaction occurred in the element with the 0.20-cm sq. defect.