Radioactive waste water treatment

A method of treating radioactive waste water containing boric acid consisting essentially of:

• adding caustic soda to a boric acid containing waste water until the pH is between 7.0 and 8.0;
• evaporating and concentrating the resultant mixture;
• adding a soluble calcium compound to the concentrated liquid in an amount sufficient to precipitate calcium borate salts;
• aging the mixture until the pH has risen to at least about 12;
• separating the aged mixture into supernatant and precipitate portions;
• solidifying the precipitate portion;
• and returning at least a portion of said supernatant portion to said untreated boric acid containing waste water to raise the pH to said waste water.

A method of volume-reducing solidification treatment of radioactive waste water containing boron, consisting essentially of:

• adjusting the pH of at least a portion of a boron containing waste water to between 7.0 and 8.0 by the addition of caustic soda;
• adding a soluble calcium compound in an amount sufficient to obtain a Ca/B molar ratio of at least 0.2;
• stirring the resulting mixture while maintaining a temperature between 40.degree. and 70.degree. C. to form insoluble calcium salts containing boron;
• aging said mixture for at least one hour at a temperature below that used for forming insoluble salts to obtain a slurry while stirring;
• separating the slurry into supernatant and concentrated solid portions;
• evaporating and concentrating the supernatant;
• and solidifying the concentrated liquid and concentrated solid with cement.