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Title: As-built mechanical and thermomechanical calculations of a spent-fuel test in Climax Stock granite

Technical Report ·
DOI:https://doi.org/10.2172/5649492· OSTI ID:5649492

A generic test of geological storage of spent-fuel assemblies from an operating nuclear reactor in Climax Stock granite has been underway at the US Department of Energy's Nevada Test Site since spring 1980. The spent-fuel assemblies were emplaced in the floor of the central drift of three parallel drifts. Auxiliary electric heaters were installed in the floors of the side drifts to simulate a large repository. Calculational modeling of the spent-fuel repository was made with the finite element codes, ADINA stress analysis code and the compatible ADINAT heat flow code. The primary purpose for doing the calculations was to provide results with the best estimates of physical and mechanical rock properties and in situ stresses. Field measurements show the effective modulus of Climax Stock granite is a factor of two lower than that obtained in the laboratory on small samples. Comparative calculations using these field measurements and measurements obtained in the laboratory show displacements are approximately inversely proportional to the modulus. They also indicate the importance of knowing the effective in situ modulus. Another comparison, varying the in situ stress loading, shows the importance of knowing the correct value of in situ stress. Calculations using the best-estimate values of rock properties, effective in situ modulus and Poisson's ratio, and in situ stress are not intended to predict the displacement and stress changes from the mining and the imposition of a thermal load. The existing jointing in the Climax Stock granite could have a significant effect on the actual displacements and stress field. Such effects are not accounted for here. However, these calculations do indicate the direction and magnitude of displacements and stresses that would be expected in absence of jointing. Comparison of those results with actual field measurements will, thus, indicate the significance of including a joint model in future calculations.

Research Organization:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
DOE Contract Number:
W-7405-ENG-48
OSTI ID:
5649492
Report Number(s):
UCRL-53198; ON: DE82005856; TRN: 82-006984
Country of Publication:
United States
Language:
English