Perspectives on the Back-end of the Nuclear Fuel Cycle: Present and Future

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Perspectives on the Back-end of the Nuclear Fuel
Cycle Present and Future

• John Kessler, Program Manager, HLW Spent Fuel
  Management (jkessler_at_epri.com 704-595-2249)
• DOE Fission-Fusion Hybrid Workshop, Gaithersburg
  MDOctober 1, 2009

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Projected US Commercial Spent Nuclear Fuel (CSNF)
Inventory (assumes all existing plants run for 60
years)
Current Yucca Mountain legal CSNF capacity limit
(63,000)
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Dry Interim Storage High Burnup and Extended
Storage
EPRI data and models are the basis for
enabling Dry storage of spent fuel with burnup
gt45 GWd/MTU Dominion, Duke Energy,
Constellation, Dry storage license extended
from 20 to 60 years First license renewal Surry
site Conclusion Long(er)-term storage can give
us time to introduce new technologies
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EPRI Yucca Mountain and Generic Disposal Program

• Yucca Mountain-specific
• Pre- and post-closure
• Transportation
• Generic disposal
• Compare post-closure doses from alternative fuel
  cycle waste forms
• Need for a second repository?

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DOE Yucca Mountain Repository Design
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DOE TSPA Results

• 10,000-year results
• Mean peak dose rate to the RMEI 0.2 mrem/yr
• 0.1 of background
• 1 of dose limit
• Dominated by (relatively) early failure of
  DOE/Defense wastes
• 1,000,000-year results
• Mean peak to RMEI 2 mrem/yr
• 1 of background
• 10 of dose limit
• Dominated by commercial spent nuclear fuel (CSNF)

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EPRI TSPA Results (CSNF only)

• 0.04 mrem/y
• 0.01 of background
• 0.2 of dose limit
• 1/50th of DOE estimate
• Why are EPRI estimates lower?
• Reduction of conservatisms

EPRI, 2006, Report 1013444, Fig. 6-3
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The Peak Dose is NOT Dominated by the Most
Radiotoxic Species

• The geology takes care of the more radiotoxic
  species
• Example relatively low solubility of many
  actinides (including Pu)
• Sorption on geologic media impedes many
  radionuclides from movement
• Conclusion inappropriate to use radiotoxicity
  as a measure for potential technical improvements
• Closing the fuel cycle
• Fission-fusion hybrids,
• Only a handful of radionuclides contribute to
  long-term dose (not usually minor actinides)

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Yucca Mountain Peak Dose Estimates Have Been
Decreasing. Why?

• Additional data
• Removal of initial conservatisms
• Improved (lower) Np solubility estimates
  dramatically decreased importance of Np-237
• EPRI drip shield example (next slide)

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Example of Over-conservatism Drip Shields are
not Necessary
What did DOE do to make it think it needed Drip
Shields?

• Overestimated the amount of net infiltration
• Overestimated the fraction of the repository
  experiencing seepage into the open drifts
• Overestimated seismic energy and rockfall
• Overestimated damage to the TADs due to seismic
  and rockfall events
• Overestimated the rate at which Alloy 22 will
  degrade
• Cladding performance was neglected
• Waste form alteration time was underestimated

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Which is Cheaper, Faster, and Easier to Lower
Dose Estimates for Disposal

• Additional work to remove conservatisms in dose
  estimates?
• Drip shield example even saves money and time!
• Introduce a major technological fix (e.g.,
  fission-fusion hybrids)?

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Several Benefits of Making Yucca Mountain
Capacity Larger than the Current Legal Limit

• Nuclear industry interested in building new
  plants
• Opponents will point out there isnt enough
  disposal space for existing plants
• Delays or even eliminates the need for a second
  repository
• Provides sufficient time buffer for introduction
  of advanced fuel cycles
• RD time to get closed fuel cycles into
  commercial operation 30-50 years

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Yucca Mountain Capacity Options the EPRI Team
Analyzed

• Option 1 Expanded repository footprint
• Option2 Multi-level repository
• Option 3 Grouped, single-level emplacement
  drifts
• Determine the range in expansion factor
  attributable to each option
• Combinations of options

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EPRI-Projected Yucca Mountain Technical Capacity
is Much Higher Than the Legal Limit
EPRIs projected technical capacity
range (260,000-570,000 MTU, 4 to 9 times current
legal limit)
Current legal limit (63,000 MTU)
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Feasibility of Direct Disposal of Dual-Purpose
Canisters (DPCs, licensed for storage and
transportation only)

• Motivation
• Industry currently using DPCs
• Avoids need to repackage
• DPC capacity 1.5x DOEs Transportation, Aging,
  and Disposal canisters (TADs)
• Considerations
• DPC versus TAD diameter it still fits
• Added decay heat effects (hydrothermal,
  thermomechanical) Yucca Mountain can handle it
• Post-closure dose no effect
• Criticality still wont happen

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Need for Advanced Fuel Cycles for Waste Disposal
Minimization? NO!

• Yucca Mountain doses are already very low (lt1 of
  background)
• True for all other repository system estimates
• Yucca Mountain technical capacity is big enough
  for decades to come
• Why trade off near-term, certain increase in dose
  to lower very long-term hypothetical dose?
• Need to compare source terms from the entire fuel
  cycle not just what is headed to disposal
• Which is cheaper and faster, introducing
  fission-fusion hybrids or doing some more work to
  eliminate conservatisms in disposal dose
  estimates?
• Radiotoxicity is an inappropriate measure
• Therefore, introduce advanced fuel cycle for
  reasons other than reducing waste disposal needs
• Economics, resource utilization, energy
  independence,

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Yucca Mountain (and Most Other Repository
Systems) can Help Keep our Options Open for
Decades to Come

• Use them as temporary storage until advanced fuel
  cycle(s) are ready
• Co-locate storage, reprocessing, fuel
  fabrication, and disposal?
• No need to move spent fuel twice if no nuclear
  advancement
• Conclusion Judicious use of repositories will
  support realistically-paced advanced fuel cycle
  development

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TogetherShaping the Future of Electricity