Sandia’s Salt Design Concept for High Level Waste and Defense Spent Nuclear Fuel

1. 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.

2. 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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3. 3
 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

4. 4
 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

5. 5
 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

6.  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

7. 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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8. 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 SNF
DOE-Managed HLW
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data from SNL 2014

9. Waste Packages
9
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)

10. 10
Distribution of Thermal Output per Canister
(by # of canisters)
From Matteo et al. 2016

11. 11
Distribution of Thermal Output per
Canister (by % of each waste type)
From Matteo et al. 2016

12. Decay Heat for Different Waste Types
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From Wilson 2016

13. Temperature Histories at Waste Package
Surface (10 years surface storage)
13
From Matteo et al. 2016

14. 14
From Matteo et al. 2016
Temperature Histories at Waste Package
Surface (50 years surface storage)

15. Salt Preliminary Design Concept
by the Numbers
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16. 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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17. 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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18. 18
From Hardin et al. 2015
An Approximate Illustration of the
Preliminary Design in Salt including
notable differences

19. 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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