An accidental burst of radiation occurred at the laboratory on 1 February 1951 during remote control operation of a critical experiment. There was no personnel hazard. Normal operations were resumed within 24 hr, and the active material involved in the burst returned to service within three weeks. An unforeseen brief excursion into the prompt critical region was engendered in the act of scramming the assembly at the end of a series of measurements. This report describes the effects of the burst and analyzes the probable causes in some detail.

A polarographic method for the determination of titanium in the presence of plutonium has been devised. Hydrochloric acid solutions of plutonium and titanium are reduced with zinc, made one molar in tartaric acid, and further reduced in the polarographic cell with liquid zine amalgam. Plutonium is thus reduced to the non-interfering (III) oxidation state and a well defined anodic wave for the oxidation of titanium (III) to titanium (IV) is obtained. The height of this wave is directly proportional to the titanium concentration for plutonium-titanium solutions containing 20 grams plutonium per liter. The precision for the analyses of duplicate samples has been calculated at the 95 percent confidence level to be 2.9 percent for those containing 0.025 to 0.050 gm titanium per liter and 1.1 percent for those containing 0.089 to 0.51 gm titanium per liter.