RADIATION EXCURSIONS AT THE ORNL CRITICAL EXPERIMENTS LABORATORY. I. MAY 26, 1954. II. FEBRUARY 1, 1956

Two prompt critical power excursions have occurred in enriched UO/sub 2/ F/sub 2/ solutions used in criticai experiments at Oak Ridge National Laboratory. The first resulted from a mechanical failure in the equipment, and the second was due to a redistribution of the solution caused by the insertion of a safety device into a near critical volume. Although the safety mechanism operated normally in both instances, the order of 10/sup 17/ fissions occurred, correspondng to an energy release of about 1 kwh. No significant property damage occurred and personnel exposures were limited to a few hundred mr. Experiments were resumed in a few days. On the basis a partial reconstruction of the first event, a semiquantitative analysis was made; a similar treatment of the second was not attempted. (auth)