Relative shielding properties of ammonium metatungstate for neutrons and gamma rays from 252Cf

The hydrogen and tungsten content and the high solubility of ammonium metatungstate suggest that a saturated aqueous solution of this salt may make a good neutron–gamma shield for 252Cf. Comparative attenuation experiments with a saturated aqueous solution and pure water show that the ammonium metatungstate solution is a significantly better shielding material for gamma rays and slow neutrons, and is also better than water for fast neutrons. For 252Cf sources of less than 500 μg, a shield consisting of a thick paste of ammonium metatungstate is recommended as a useful shielding material in place of a saturated solution to reduce the hazard in case of container leakage. A saturated solution of ammonium metatungstate is relatively clear and may be used as an absorber in windows of hot cells.