Subsidence Risk Mitigation in LLW Final Covers: A Case History - 18286

Conference · Sun Jul 01 04:00:00 EDT 2018

OSTI ID:22975432

Foye, Kevin; Soon, Te-Yang ^[1]; Gelles, Christine ^[2]

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1. CTI and Associates, Inc. (United States)
2. Longenecker and Associates (United States)

Typical waste packaging and disposal practices at low-level radioactive waste (LLW) disposal facilities, while adequate for safe transportation and facility operations, introduce significant subsidence risk for the facilities' final cover systems. Subsidence is often caused by the collapse of voids in the waste packaging and surrounding cover soils that eventually propagate to the ground surface. This subsidence could result in the loss of final cover system integrity, stormwater ponding, concentrated flow of surface water and/or gas, increased leachate generation, transport of contaminants from the landfill, and potential adverse chemical reactions within the waste mass. For new LLW facilities, steps can be taken to minimize the subsidence potential of newly placed waste. However, there is a significant inventory of existing disposal facilities (trenches, pits, shafts, vaults, etc.), tank farms, and historic, subsurface burial grounds that require final covers - all of which present real subsidence risks. Final covers for these existing LLW disposal sites can be engineered to mitigate these risks. A case history of a 60-acre LLW final cover system design and construction project illustrates an innovative approach to this problem that offers superior risk mitigation compared to typical final cover design practice. This approach combines engineering simulations of the projected final cover mechanical performance, specific probabilistic performance targets, and targeted cover system improvements to manage the subsidence risk in the final design. The result is a successful final cover project that meets the needs of the community, state and federal regulators, and facility owner. (authors)

• Research Organization: WM Symposia, Inc., PO Box 27646, 85285-7646 Tempe, AZ (United States)
• OSTI ID: 22975432
• Report Number(s): INIS-US--20-WM-18286
• Country of Publication: United States
• Language: English

Related Subjects

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
DESIGN
GROUND DISPOSAL
GROUND SUBSIDENCE
LEACHATES
LOW-LEVEL RADIOACTIVE WASTES
MITIGATION
PACKAGING
PERFORMANCE
PROBABILISTIC ESTIMATION
RADIATION HAZARDS
RADIATION PROTECTION
RADIOACTIVE WASTE DISPOSAL
RADIOACTIVE WASTE STORAGE
SANITARY LANDFILLS
SURFACE WATERS
WASTE TRANSPORTATION