[As a service to our readers, we will be gathering and reprinting notices posted on laboratory doors at the Massachusetts Institute of Technology. The following notice was found affixed to the door of an MIT physics laboratory and was provided to us by Michael Genrich. It appears below unaltered. (Note: if you have notices that you have found posted to doors at MIT, please email them to mcsweeneysmail@yahoo.com with "MIT Doors" in the Subject header.)] - - - - DEPLETED URANIUM - SAFETY AND EMERGENCY PROCEDURES OUR LICENSE: Posession of 2.5 x 10-5 Ci (Curie), i.e. 50g depleted uranium. All comes in or out via the RPO [ Radiation Protection Office ]. Only as a solid (no powders). All containers must be labelled ("radiation hazard" only) and locked away. The authorised labs (6-325 and 6-327(!)) must be locked when radiation authorised personnel are not present. URANIUM: All we handle is depleted uranium that contains pretty stable isotopes. 238U containing 0.45% 235U. Activity is 5 x 10-7 Ci/g. Half life is 4.5 x 109 years. The fission products are low energy gamma emitters. The only two places it is kept are in 6-325; in the glove box and in the two plastic containers in the far fumehood. The powdered metal is pyrophoric in air. TOXICITY: Uranium emits alpha particles of circa 4.2 MeV energy. These are stopped by a latex glove or paper. However, it is very poisonous. IF YOU ARE UNSURE: Radioactivity is very easy to detect. The portable detector is always next to the sink in 6-325. Use it to detect contaminants above background (100-300 cpm) on the highest setting. Pass the gauze end of the tube over surfaces at 5 cm per sec, about 1 cm from the surface. Uranium and its complexes are soluble in conc. nitric acid.
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