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Sandia’s Salt Design Concept for High Level Waste and Defense Spent Nuclear Fuel
Ed Matteo, Ernie Hardin, and Teklu Hadgu
Sandia National Laboratories
Middelburg, The Netherlands
September 5-7, 2017
Sandia National Laboratories is a multi-mission laboratory managed and operated by
National Technology and Engineering Solutions of Sandia LLC, a wholly owned subsidiary
of Honeywell International Inc. for the U.S. Department of Energy’s National Nuclear
Security Administration under contract DE-NA0003525. SAND2017-9337 C.
Disclaimer
This research was performed as part of the Defense Waste Repository (DWR) project. Based on revised DOE priorities in mid-2017, the development of a DWR has been discontinued; current work unique to the development of a DWR is being closed out and documentation will be completed by the end of fiscal year (FY) 2017. Implementation of any recommendations made in this report for further research regarding a DWR would require resumption of the DWR project at some future time.
Key Acronyms
HLW = High Level Waste
DSNF = Defense Spent Nuclear Fuel (or DOE-Managed Spent Nuclear Fuel)
CSNF = Commercial Spent Nuclear Fuel
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Main Objectives: Operational and post-closure safety
Disposal Concept ≡ waste form + geologic setting + concept of operations
Waste form:
Mostly High Level Waste (HLW) glass, low heat output, Stainless Steel pour canisters
Defense Spent Nuclear Fuel (DSNF) of various types, pre-canistered
Geologic setting: Salt
Concept of operations: ?
Preliminary Disposal Concepts for Salt Repository:Identify Candidate Concepts for Evaluation
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Low-thermal (up to 1 kW per 3- or 5-m canister)
Long-lived radionuclides (~106-year assessment)
Large numbers of canisters (data from Carter et al. 2012)
3,542 DSNF (99.4% < 1 kW in 2030)
23,032 HLW (Savannah River Site(SRS, Hanford & Idaho; all < 1 kW)
Small canisters (mostly 18- and 24-inch diameters)
Neglecting Naval SNF which is most similar to Commercial Spent Nuclear Fuel (CSNF)
(Assume Idaho calcine is package in standardized canisters.)
Canister Handling Weights
DSNF 2267 kg to 4536 kg + overpack ~15 MT
Shielded transport wt. >34 MT
HLW 2500 kg to 4200 kg (no overpack)
Shielded transport weight > 32 MT
Material: stainless steel (welded, no heat treatment)
Preliminary Disposal Concepts for a Salt Repository:Defense Waste Characteristics
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Plastic formation
Creep behavior impacts concept of operations
Excavations will close due to creep
Just-in time drift construction
Self-healing
Geochemical environment Brine pore water
Virtually impermeable media (diffusion dominated)
Repository Access
For bedded salt, shaft access only
For domal salt, shaft or ramp access
Preliminary Disposal Concepts for a Salt Repository:Salt Geologic Setting
Bedded or Domal Salt Constructability
• Opening stability
• Salt backfill
Superior Heat Dissipation
Nominal and Disturbed Performance
• Releases dominated by human intrusion
Natural Barrier
• Insignificant groundwater abundance and mobility (nominal)
• Brine saturation (esp. human intrusion)
Engineered Barriers
• Backfill and seals
• Robust containment during operations
• Emplacement borehole behavior (e.g., backfill reconsolidation)
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Preliminary Disposal Concepts for a Salt Repository:Design Considerations
Preliminary Disposal Concept for a Salt Repository
Direct Disposal of Pour Canisters
• HLW glass stability in operational environment
Robust Overpack for Other Waste Forms
• Carbon steel overpack (e.g., DSNF)
Just-in-Time Drift Construction
• Minimize handling of crushed salt
In-Drift Emplacement (axial or transverse)
• Relatively small, lightweight canisters (e.g., 6 MT HLW)
• Immediate backfilling with crushed salt
Constructability Challenges
• Remote operation in unshielded environments
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The Inventory is ~80% by volume is glass
Projected volumes in the year 2048 ( m3)
Commercial and DOE-Managed
HLW and SNF
DOE-Managed
HLW and SNFDOE-Managed HLW
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data from SNL 2014
Waste Packages
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HLW Glass
Diameter = 61cm (direct disposal)
Length = 3m or 4.57m
Defense Spent Nuclear Fuel
Diameter = 61cm (80cm including Steel overpack)
Length = 3.1m or 4.6m
(not used for Naval SNF)
From DOE 2008 -- Yucca Mountain repository SAR (Figure 1.5.1-8 and Figure 1.5.1-18)
Temperature Histories at Waste Package Surface (10 years surface storage)
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From Matteo et al. 2016
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From Matteo et al. 2016
Temperature Histories at Waste Package Surface (50 years surface storage)
Preliminary Design Parameters Selected on the Basis of Design Criteria Thermal Analysis, 1/2
Waste Package Emplacement Concept is simple and cost effective Just-time- construction
Run-of-mine (ROM) salt from advancing drift used for backfill on adjacent drift post-emplacement
Minimizes ROM handling operation
Provides shielding for DSNF packages
The tranverse emplacement of packages keeps the repository footprint compact
DSNF overpack is robust, direct disposal of HLW reduces handling burden
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Preliminary Design Parameters Selected on the Basis of Design Criteria Thermal Analysis, 2/2
Drift details Drift length = 500m
~50 DSNF packages per drift (~3000 total)
~50-150 HLW packages per drift (~25,000 total)
14m pillars could be increased to 30m, if necessary
Waste Package Spacing
DSNF - ~8m (center to center)
HLW - ~3 to7.7m (center to center)
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From Hardin et al. 2015
An Approximate Illustration of the Preliminary Design in Salt including notable differences
References
DOE (U.S. Department of Energy) 2008. Yucca Mountain Repository License Application Safety Analysis Report. DOE/RW-0573, Revision 1. U.S. Department of Energy, Washington, DC. (http://www.nrc.gov/waste/hlw-disposal/yucca-lic-app/yucca-lic-app-safety-report.html#1 )
Filbert, W., E. Biurrun, W. Bollingerfehr, B. Haverkamp and R. Graf 2010a. “Optimization of Spent Fuel Direct Disposal Technology for a Geological Repository in Rock Salt in Germany– 10504.” Proceedings of Waste Management 2010. March 7-11, Phoenix, AZ.
Hardin, E., L. Price, E. Kalinina, T. Hadgu, A. Ilgen, C. Bryan, J. Scaglione, K. Banerjee, J. Clarity, R. Jubin, V. Sobes, R. Howard, J. Carter, T. Severynse and F. Perry 2015. Summary of Investigations on Technical Feasibility of Direct Disposal of Dual-Purpose Canisters. FCRD- UFD-2015-000129 Rev. 0. U.S. Department of Energy, Office of Used Nuclear Fuel Disposition.
Matteo, E. N., E. L. Hardin, T. Hadgu, H. Park, C. Jové-Cólon, and M. Rigali 2016. Status of Progress Made Toward Preliminary Design Concepts for the Inventory in Select Media for DOE-Managed HLW/SNF. FCRD-UFD-2016-000081, U.S. Department of Energy, Office of Used Nuclear Fuel Disposition.
SNL (Sandia National Laboratories) 2014. Evaluation of Options for Permanent Geologic Disposal of Used Nuclear Fuel and High-Level Radioactive Waste Inventory in Support of a Comprehensive National Nuclear Fuel Cycle Strategy. FCRD-UFD-2013-000371. SAND2014-0187P; SAND2014-0189P. Revision 1. Albuquerque, New Mexico: Sandia National Laboratories.
Wilson, J. 2016. Decay Heat of Selected DOE Defense Waste Materials, FCRD-UFD-2016- 000636, SRNL-RP-2016-00249.
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