Patent Number: 044406738
Section: claims

1. A method of treating radioactive waste water from a nuclear reactor containing dissolved boric acid which comprises the steps of: (a) concentrating radioactive waste water containing dissolved boric acid derived from a nuclear reactor in an evaporator to a boric acid concentration in a concentration below the boric acid saturation level at the temperature of the concentrate but above the saturated level of the concentrate for boric acid at room temperature;  (b) collecting the concentrate following step (a) at a temperature of at least 50.degree. C. in a storage tank and permitting the concentrate in said storage tank to cool to room temperature and adding a radioactive solid waste containing diatomaceous earth to the tank, thereby precipitating boric acid solids from the concentrate in said tank and permitting the precipitate to sediment as a sludge therein;  (c) thereafter decanting clear concentrate from the sedimented boric-acid-containing sludge in said tank and recycling the decanted clear concentrate to the evaporator of step (a);  (d) repeating steps (b) and (c) while accumulating sludge in said tank thereby enabling radiation in the waste water to decay; and  (e) discharging the sludge from said tank upon its accumulation therein to a predetermined level.