| Popis: |
The ultimate disposal of radioactive wastes into geologic formations has received increasing attention during the past 10 years. Due to the varying heat-generation rates of the different categories of wastes and the allowable costs, no single formation is capable of handling the entire spectrum of wastes produced. Therefore, three different methods of disposal have been investigated to handle the high-, intermediate-, and low-level wastes generated. High-level, small-volume wastes would be converted to solids and stored in a dry impermeable underground formation such as salt; intermediate-level, intermediate-volume wastes would be slurried with cement and additives and injected into slightly permeable formations using the hydrofracturing technique; and low-level, large-volume wastes would be injected into deep porous formations. The engineering-scale demonstration of the hydrofracturing concept has been completed, and a demonstration of the disposal of radioactive solids in a salt mine is underway. A total of seven injections at depths from 800 to 1000 ft have been made at the Oak Ridge National Laboratory using the hydrofracturing technique. These injections have shown that horizontal conformable fractures are possible and have contributed valuable operating experience. In addition, a number of mixes have been developed and tested and are capable of satisfactorily retaining fission product waste. Project SALT VAULT is a demonstration of the disposal of solidified high-level wastes in an out-of-service mine in Lyons, Kansas. In November 1965, fourteen Engineering Test Reactor fuel assemblies, containing 1,000,000 Ci of fission products, were placed in the mine floor. During the course of the 2-year test, four sets of fuel assemblies will be used to achieve a peak dose to the salt of about 8 × 108 rad and to obtain experience with the waste-handling equipment. The operation has proceeded smoothly, and most of the experimental objectives have been already achieved. Laboratory studies on the flow path of radionuclides through a sandstone block have been carried out. However, it appears that a field scale demonstration of the deep well technique is some years away. |
