This memorandum discusses the problems associated with the production and use of Uranium 233 for an early test shot.

Three overbore elements, 75Zl2, 75Zl4, and 75Zl5 were discharged from 3062C on April 16, 1962 with longitudinal splits after an exposure of 676. The three elements, two of which had completely split apart, were received on July 5, 1963 to determine the cause of failure. All three elements had failed in the same manner with several full length longitudinal cracks in the uranium extending radially from the canwall to about midway in the core. The failure mechanism was found to be the same as that observed during the examination of worm-tracked overbore elements under RM 456 in which incipient failures had occurred from excessive core temperatures. In two out of the three worm-tracked elements the interior core temperatures had exceeded the beta transformation point as a result of severe cycling conditions. In these three ruptures from 3062C the maximum core temperature had not reached the beta phase; however, the failures were undoubtedly caused by excessive hoop stresses resulting from high internal core temperatures.