138. 



underground storage of the liquid waste in barrels or other containers 

 would present similar problems of heat removal and would probably, 

 in comparison, be more costly than underground storage in bulk. 



13.8 The fixation of the liquid waste in some solid form after cooling 

 and prior to underground disposal would be advantageous as regards 

 both transportation and storage. Various methods of conversion of 

 waste to solid form have been suggested and some of these have been 

 carried through the stage of pilot plant operations. Mixing with cement 

 in the proportion of about 15 lbs. per gallon would result in a solid 

 mixture of about 7 cubic feet, weighing about 80 lbs. per cubic foot.W") 

 On a large scale, at a processing plant, this material could be cast in 

 molds into a form suitable for handling by automatic conveyors and 

 shielded fork-lift trucks with very low hazards from irradiation. Other 

 methods of solidification, such as incorporation in slag or ceramic 

 products, have considerable merit. ( '' 



13.9 On the assumption that a disposal plant could be located in the 

 immediate vicinity of underground storage in mined-out-salt space, 

 the designing of a system of transportation from the plant to the point 

 of disposal would seem to present no serious problems, using belt 

 conveyors for movement and shielded fork-lift trucks for stacking or 

 piling in the underground rooms. The solidified material would produce 

 heat in storage but the problem of boiling would be eliminated and the 

 air temperature could become high without effect on the surrounding 

 salt. The cement blocks could be cast in such form that air could pass 

 through them. A system of air circulation to remove the heat from 

 storage rooms would be more feasible than the cooling of liquid waste 

 in underground reservoirs. 



14. RECOMMENDED STUDIES 



In the light of present knowledge, no insurmountable obstacles to the 

 storage of radioactive waste in solid form in underground cavities in 

 salt appear to exist. Detailed studies should be carried out on the fol- 

 lowing engineering and economic phases of the problems related to salt: 



a. The availability and cost of suitable space in underground salt 

 deposits; 



b. The most effective and economical methods of processing liquid 

 waste in large quantities into solid form; 



