The Spent Fuel Test-Climax (SFT-C) is a test of dry geologic storage of spent nuclear reactor fuel. The SFT-C is located at a depth of 420 m in the Climax granitic stock at the Nevada Test Site of the U.S. Department of Energy. Eleven canisters of spent commercial PWR fuel assemblies are to be stored for 3 to 5 years. Additional heat is supplied by electrical heaters, and more than 800 channels of technical information are being recorded. The measurements include rock temperature, rock displacement and stress, joint motion, and monitoring of the ventilation air volume, temperature, and dewpoint.
The Lawrence Livermore National Laboratory (LLNL) as a participant in the Nevada Nuclear Waste Storage Investigations (NNWSI) program is responsible for the technical direction of a test of geologic storage of spent reactor fuel. This test (generally referred to as the Spent Fuel Test-Climax or SFT-C) is at a depth of 420 m in the Climax granite at the Nevada Test Site. The NNWSI is part of the commercial waste management activities of the National Waste Terminal Storage (NWTS) program of the U.S. Department of Energy (DOE). At the time the SFT-C was authorized in June 1978, there was no high level nuclear waste in deep geologic storage, even at a demonstration or pilot scale. Furthermore, the only previous such test, Project Salt Vault (Bradshaw and McClain, 1971), was in bedded salt, and no actual experience with deep geologic storage in other rock types existed. At the Nevada Test Site (NTS) of the DOE, there existed facilities both for encapsulating spent fuel assemblies in canisters suitable for underground storage and for a test layout near previously mined workings at a depth of 420 m.
Therefore, a test was planned which would have both educational and demonstration value as well as address technical issues of rock response to the waste. The technical concept for the SFT-C (Ramspott and others 1979) provides a simulation of the thermal field of a large repository within a 15-m × 15-m repository model cell. The heat sources are 11 canisters of spent commercial PWR fuel assemblies and 6 electrical fuel-simulators in a central canister storage drift. These are supplemented by 10 electrical heaters in each of 2 adjacent heater drifts (Fig. 1). By comparison of the electrical simulators with the spent fuel, it is possible to evaluate the effects of heat alone with heat plus ionizing radiation. Work performed under the auspices of the U.S. Department of Energy by the Lawrence Livermore National Laboratory under contract No. W-7405-ENG-48. Spent fuel emplacement was completed by May 28, 1980, at which time the decay heat from each fuel assembly was about 1550 W. Following encapsulation at a facility about 75 km from the storage site, the canistered fuel was transported and emplaced with a system designed specifically for this test. No hot cell was built at the site, and although sufficiently shielded for personnel access at all times, operations at the Climax site were remotely controlled.
