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Title: Analyses of backfilled transuranic wastes disposal rooms

Technical Report ·
OSTI ID:5295881
;  [1]
  1. RE/SPEC, Inc., Rapid City, SD (United States)

The Waste Isolation Pilot Plant (WIPP) is a US Department of Energy (DOE) research and development facility established to demonstrate the safe geologic disposal of transuranic (TRU) wastes generated from defense-related activities. Crushed salt and crushed-salt treatments are the candidate materials to be used as backfill around waste and waste packages in the underground disposal rooms. In response to room closure, the backfill is anticipated to compact sufficiently such that an effective seal is formed reducing brine inflow and radionuclide transport. In this report, different backfill and backfill/TRU waste combinations are investigated based on finite element simulations for a 200-year period conducted to examine and compare the sealing efficacy of different backfill scenarios. Specifically, disposal room content scenarios investigated include crushed salt, a crushed salt/bentonite mixture, crushed salt covering TRU waste, crushed salt/bentonite covering TRU waste, crushed salt covering a mixture of crushed salt and shredded metallic waste and crushed salt covering vitrified waste. The simulations were conducted with the thermomechanical finite element program SPECTROM-32. The report includes a description of constitutive relations used to simulate the backfill and host rock formation including viscoplastic (creep), nonlinear elastic, creep consolidation, and nonlinear elastic and consolidation mixture models. The simulation results show that the backfill attains average void fractions less than 5 percent in all cases except for the case with crushed salt/bentonite covering TRU waste, which is only slightly greater than 5 percent. The time required to attain these void fractions varies considerably between cases. 27 refs., 22 figs., 11 tabs.

Research Organization:
Sandia National Labs., Albuquerque, NM (United States); RE/SPEC, Inc., Rapid City, SD (United States)
Sponsoring Organization:
USDOE; USDOE, Washington, DC (United States)
DOE Contract Number:
AC04-76DP00789
OSTI ID:
5295881
Report Number(s):
SAND-91-7052; ON: DE91018888
Country of Publication:
United States
Language:
English