Room Closure Response to Gas Generation and Mechanical Strength of Different Waste Forms in a Bedded Salt Repository

Abstract

Finite element calculations of the porosity history of a nuclear waste disposal room for transuranic (TRU) waste in a bedded salt formation have been completed. The analyses include a reduced elastic/secondary creep model for the host halite and a nonlinear consolidation model for the crushed salt backfill. Separate gas generation and constitutive models were used for three distinct hypothetical waste forms: 1) unaltered defense-related, contact-handled transuranic (CH-TRU) waste, 2) shredded and cemented CH-TRU waste, and 3) incinerated and vitrified CH-TRU waste. Histories were determined for a 2000 year time period starting from the emplacement of room seals. The resulting final room porosities varied from roughly 55% to less than 10%, according to waste forms.