Richards Barrier LA Reference Design Feature Evaluation
The Richards Barrier is one of the design features of the repository to be considered for the License Application (LA), Richards was a soil scientist who first described the diversion of moisture between two materials with different hydrologic properties. In this report, a Richards Barrier is a special type of backfill with a fine-grained material (such as sand) overlaying a coarse-grained material (such as gravel). Water that enters an emplacement drift will first encounter the fine-grained material and be transported around the coarse-grained material covering the waste package, thus protecting the waste package from contact with most of the groundwater. The objective of this report is to discuss the benefits and liabilities to the repository by the inclusion of a Richards Barrier type backfill in emplacement drifts. The Richards Barrier can act as a barrier to water flow, can reduce the waste package material dissolution rate, limit mobilization of the radionuclides, and can provide structural protection for the waste package. The scope of this report is to: (1) Analyze the behavior of barrier materials following the intrusion of groundwater for influxes of 1 to 300 mm per year. The report will demonstrate diversion of groundwater intrusions into the barrier over an extended time period when seismic activity and consolidation may cause the potential for liquefaction and settlement of the Richards Barrier. (2) Review the thermal effects of the Richards Barrier on material behavior. (3) Analyze the effect of rockfall on the performance of the Richards Barrier and the depth of the barrier required to protect waste packages under the barrier. (4) Review radiological and heating conditions on placement of multiple layers of the barrier. Subsurface Nuclear Safety personnel will perform calculations to determine the radiation reduction-time relationship and shielding capacity of the barrier. (5) Evaluate the effects of ventilation on cooling of emplacement drifts and dusting potential. (6) Evaluate drift conditions and configurations to determine the suitability of Richards Barrier installation methodology. (7) Perform cost assessment of barrier material placement. (8) Evaluate the feature with criteria that will be supplied by the License Application Design Selection (LADS) Team. (9) Comment on the use of depleted uranium as a Richards Barrier material.
- Research Organization:
- Yucca Mountain Project, Las Vegas, Nevada
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC08-91RW00134
- OSTI ID:
- 840669
- Report Number(s):
- B00000000-01717-2200-00215, REV 00, ICN 01; MOL.20000120.0064, DC#20877
- Country of Publication:
- United States
- Language:
- English
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