ABSTRACTThree in situ heater tests are being performed in dome salt at the Avery Island mine in Louisiana. These tests are simulations of the emplacement of singular canisters of heat generating nuclear waste. Combinations of three power levels and the two emplacement concepts were included in the three heater tests. Each test includes a central heater (simulated waste canister), a protective sleeve, and various sensors to measure rock reponse.
Representative temperatures and displacements measured in the heater tests are presented. For one of the heater tests the measured response is compared with finite element analysis predicted response. A 20% increase in the laboratory measured thermal conductivity is required in the analysis to obtain agreement between the calculated and measured temperatures. The displacements predicted in the analysis are not in total agreement with the measured displacements. The lack of agreement is not severe and is possibly attributable to both the difficulty in representing the room and pillar configuration at Avery Island in a two dimensional analysis and to the suitability of the laboratory determined constitutive creep relation. Further interpretation of the data and additional modeling studies are necessary before the discrepancy will be resolved.
The purpose of the in situ heater tests in the Avery Island salt mine is to acquire thermal and mechanical data that will aid in the identification and understanding of various responses of domal salt to an imposed heat source. This knowledge is germane to investigations related to the ultimate disposal of nuclear waste in a geologic formation. Some nuclear wastes are heat gene rating waste; thus, after this waste is buried, heat will be transferred to the surrounding geologic formation by natural processes. The transfer of heat into the formation results in increased temperatures which induce thermomechanical responses, such as thermal expansion, and possibly thermochemical responses, such as brine migration. Identification and understanding of the various responses of the formation are necessary to design a storage facility capable of providing environmentally and economically acceptable disposal of nuclear waste.
Previous in situ investigations related to nuclear waste disposal have been made in salt formations, most notably Project Salt Vault (Bradshaw and McClain, 1971), which was conducted in bedded salt near Lyons, Kansas. Project Salt Vault made use of both actual radioactive waste and electrical heaters to impose a heat load on the formation. The Avery Island heater tests are extensions of the previous work in salt but differ in that they are being performed in domal salt, rather than in a bedded salt formation. Additionally, no actual nuclear waste or radioactive material is present or allowed in the Avery Island tests.
Three heater tests are being performed. The heater tests employ simulated, electrically heated waste canisters placed in sleeved boreholes in the floor of the mine. Installation of the test equipment was begun in January, 1978; all three tests were in operation by June, 1978. The overall physical makeup of each test is similar.