135. 



operations could be performed by an industrial contractor so that the 

 net cost of the mined-out storage space might be very small. De- 

 tailed consideration should also be given to the suitability and availa- 

 bility of space in existing or abandoned salt mines in this area. 



11.4 The area along the Gulf Coast in which salt domes occur is ac- 

 cessible to water transportation through the Mississippi River and its 

 distributaries and the intercoastal canal. Numerous salt domes are 

 present in the area but in many of them the salt is at uneconomic 

 depths. Some of the salt domes are being mined and worked-out space 

 now exists. The feasibility of utilizing such space for the storage of 

 radioactive waste and at the same time continuing the operation of the 

 salt mines would require detailed investigation. A few salt domes 

 exist in the area in which mines have not been opened and which are 

 favorable as to depth of salt and convenience of transportation. 



12. UTILIZATION OF SALT SPACE FOR WASTE DISPOSAL 



12.1 The storage of radioactive waste in properly located space ob- 

 tained by the mining out of rock salt has many advantages as compared 

 with other methods of disposal. Some of these are the following: 



a. The salt itself has considerable strength so that pillars left in 

 mining may provide sufficient strength to support the roof. In bedded 

 salt deposits the overlying strata such as limestone and dolomite pro- 

 vide truss-like support to the overburden. The possibility of roof 

 collapse causing the release of radioactive materials stored under 

 these conditions appears very small but merits verification. 



b. The salt is impervious to the passage of water because of its 

 plasticity and crystalline structure, so that the mined-out space is 

 very dry. This dryness increases the life of metals by reducing rust 

 and corrosion. 



c. The salt deposits are quite level so that suitable vehicles can be 

 used in transportation underground. 



d. The two principal areas where deposits of rock salt occur in the 

 United States have very low seismicity and the possibility of space in 

 mined-out areas being collapsed by earth movements is extremely 

 small. Geological examination of mined-out areas indicates that 

 faults are not present, confirming a geological history of stability. 



