Drift Emplaced Waste Package Thermal Response

by Donald J. Ruffner, Lawrence Livermore Natl Lab, Livermore, United States,
Gary L. Johnson, Lawrence Livermore Natl Lab, Livermore, United States,
Ethan A. Platt, Lawrence Livermore Natl Lab, Livermore, United States,
James A. Blink, Lawrence Livermore Natl Lab, Livermore, United States,
Thomas W. Doering, Lawrence Livermore Natl Lab, Livermore, United States,



Document Type: Proceeding Paper

Part of: High Level Radioactive Waste Management 1993

Abstract: Thermal calculations of the effects of radioactive waste decay heat on the potential repository at Yucca Mountain, Nevada, have been conducted by the Yucca Mountain Site Characterization Project (YMP) at Lawrence Livermore Natl Lab (LLNL) in conjunction with the B&W Fuel Company. For a number of waste package spacings, these 3D transient calculations use the TOPAZ3D code to predict drift wall temperatures to 10,000 years following emplacement. Systematic temperature variation occurs as a function of fuel age at emplacement and Areal Mass Loading (AML) during the first few centuries after emplacement. After about 1000 years, emplacement age is not a strong driver on rock temperature; AML has a larger impact. High AMLS occur when large waste packages are emplaced end-to-end in drifts. Drift emplacement of equivalent packages results in lower rock temperatures than borehole emplacement. For an emplacement scheme with 50% of the drift length occupied by packages, an AML OF 138 MTU/acre is about three times higher than the Site Characterization Plan-Conceptual Design (SCP-CD) value. With this higher AML (requiring only 1/3 of the SCP-CD repository footprint), peak drift wall temperatures do not exceed 160 °C, but rock temperatures exceed the boiling point of water for about 3000 years. These TOPAZ3D results have been compared with reasonable agreement with two other computer codes.

Subject Headings: Radioactive wastes | Temperature effects | Fuels | Rocks | Waste disposal | Decomposition | Waste sites

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