Design of a high-level waste repository system for the United States

Abstract

This report presents a conceptual design for a High Level Waste disposal system for fuel discharged by U.S. commercial power reactors, using the Yucca Mountain repository site recently designated by federal legislation. It represents the results of approximately 2000 person-hours of work by students enrolled in the combined undergraduate and graduate design subjects 22.033/22.33 of the M.I.T. Nuclear Engineering Department during Spring Term 1988.

Principal features of the resulting conceptual design include - use of unit trains (including piggyback cars for truck cask transporters where required) for periodic (once every ten years at each reactor) removal of old (cooled > 10 yrs.) spent fuel from at-reactor storage facilities - buffer storage at the repository site using dual purpose transportation/storage casks of the CASTOR V/21 type - repackaging of the spent fuel from the dual purpose transportation/storage casks directly into special-alloy disposal canisters as intact fuel assemblies, without rod consolidation - emplacement into a repository of modular design having a maximum total capacity of 150,000 MT and an annual handling capability of 4000 MT/yr - use of excavation techniques that minimize disturbance, both mechanical and chemical,

to the geologic environment - Incoloy 825 waste canisters arrayed to provide 57 kW/acre thermal loading optimized to the projected inventories - include a unit rail mounted vehicle for both the transportation and emplacement of the canister from the surface facilities to the underground repository - cost-effectiveness of the Yucca Mountain Site Criteria was studied via: a computer model, "WADCOM-II - Waste Disposal Cost Model II"; and an independent cost evaluation by the members of the design team. The total system cost (in constant 1988 dollars) was 1.9 billion dollars by WADCOM-II, and 5.3 billion dollars from the independent cost evaluation, resulting in a levelized disposal cost of 0.2 mills/kW-hr by WADCOM-II and 0.55 mills/kW-hr by the independent cost evaluation.