Efficacy of backfilling and other engineered barriers in a radioactive waste repository in salt
In the United States, investigation of potential host geologic formations was expanded in 1975 to include hard rocks. Potential groundwater intrusion is leading to very conservative and expensive waste package designs. Recent studies have concluded that incentives for engineered barriers and 1000-year canisters probably do not exist for reasonable breach scenarios. The assumption that multibarriers will significantly increase the safety margin is also questioned. Use of a bentonite backfill for surrounding a canister of exotic materials was developed in Sweden and is being considered in the US. The expectation that bentonite will remain essentially unchanged for hundreds of years for US repository designs may be unrealistic. In addition, thick bentonite backfills will increase the canister surface temperature and add much more water around the canister. The use of desiccant materials, such as CaO or MgO, for backfilling seems to be a better method of protecting the canister. An argument can also be made for not using backfill material in salt repositories since the 30-cm-thick space will provide for hole closure for many years and will promote heat transfer via natural convection. It is concluded that expensive safety systems are being considered for repository designs that do not necessarily increase the safety margin. It is recommended that the safety systems for waste repositories in different geologic media be addressed individually and that cost-benefit analyses be performed.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- DOE Contract Number:
- W-7405-ENG-26
- OSTI ID:
- 6743521
- Report Number(s):
- ORNL/TM-8372; ON: DE83000380; TRN: 82-024454
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
RADIOACTIVE WASTE STORAGE
BACKFILLING
BENTONITE
CORROSION PROTECTION
DESICCANTS
EVALUATION
PACKAGING
SALT DEPOSITS
SOLID WASTES
CLAYS
GEOLOGIC DEPOSITS
MANAGEMENT
STORAGE
WASTE MANAGEMENT
WASTE STORAGE
WASTES
052002* - Nuclear Fuels- Waste Disposal & Storage