Nuclear Energy II: Waste

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Nuclear Energy II Waste Economics
Prof. William E. Kastenberg Nuclear
Engineering U.C. Berkeley
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Nuclear Fission
200MeV
y
10n
x
2.43
23592U
23994Pu
23892U
10n
23592U
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Fission (continued)
Fission Products
Fission Products
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Actinide Decay Chains
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Nuclear Fuel Cycle Waste Generation
0.2 MT U
27.3 MT
LLW 1,000 drums
26 MT U 0.95 MT FP 0.27 MT Ac
27.5 MT
0.24 MT Pu
0.5 MT U
TRU/LLW
26 MT
165 MT (0.3U-235)
lt 0.26 MT U 0.95 MT FP 0.27 MT Ac
167 MT
100,000 MT ore
1 GWe, LWR, 1 year Reprocessing scheme Thermal
efficiency 0.325 Capacity factor 0.8
0.2 U3O8 181 MT U
1 MT U Ra, Th
Mill tailings U7 Th-230 100, Ra 98
Airborne Rn
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Commercial Spent Nuclear Fuel (Cumulative)
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High-Level Waste
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Transuranic Waste (Retrievably Stored)
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Reprocessing of Spent Nuclear Fuel
Step 1 Decladding and Chopping Step
2 Dissolution into HNO3
Step 3 Extraction of U and Pu by Tri Butyl
Phosphate (TBP) Step 4 Pu Recovery from TBP to
Aqueous phase
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Yucca Mountain
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Engineered Barrier System

• Waste solid
• To limit leaching of radionuclides to groundwater
• Metal canister, overpack
• To prevent waste forms contacting groundwater
• In oxygen-depleted environment, some metal
  canister generates hydrogen by corrosion, and
  keeps the environment reducing.
• By corrosion, metal canister swells, and
  groundwater movement through EBS becomes more
  difficult.
• Buffer material
• To make sure that water movement is negligibly
  slow in this domain.
• To settle and maintain the position of the waste
  form
• To retard radionuclides released from waste forms
• To fill gaps between the waste form and the
  surrounding host rock and to seal cracks in the
  host rock (self-sealing capability)
• To control temperature increases in EBS caused by
  the decay heat of radionuclides
• To maintain a proper pH and redox potential in
  pore water of the buffer material (chemical
  buffering)
• To buffer the stress due to the deformation of
  surrounding host rock as well as the accumulation
  of corrosion products of metal canister (stress
  buffering effects)

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HLW Generation

• For 1 GWeyear
• Spent fuel 30 MT
• FPs Actinides 1 MT
• HLLW 15 30 m3
• Borosilicate glass 3 m3
• 150-liter canister 30
• For 30 40 reactors 1,000 canisters/year
• For 40 years 40,000 canisters/repository

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Radioactivity of HLW

• Fission Products
• Sr-90, Cs-135, I-129, Tc-99, ...
• Actinides U
• Am-243, Am-241, Np-237, Pu-239, Pu-240, Pu-242,
  Cm-245, Cm-244, ...
• Activated materials
• H-3, C-14, Zr-95, Ni-63, Fe-55, Co-60, ...

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HLW Geologic Disposal Concept in Sweden

• water-saturated granite
• LWR spent fuel
• copper canister (lined with titanium)
• bentonite buffer

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HLW Geologic Disposal Concept in Switzerland

• Tunnel type
• water-saturated granite
• Vitrified waste
• carbon-steel overpack
• bentonite buffer

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HLW Geologic Disposal Concept in Japan

• Tunnel type
• water-saturated granite
• Vitrified waste
• carbon-steel overpack
• bentonite buffer

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HLW Geologic Disposal Concept in Germany

• Rock salt (Gorleben)
• Vitrified waste LWR spent fuel

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Potential HLW Geologic Disposal Sites in China
1 SW China (Granite, Shale), 2 Guandong area
(granite), 3 Inner Mongolia (granite) 4 East
China (Granite, tuff), 5 NW China (mudstone,
shale, granite) A Daya Bay NPP, B Linao NPP,
C Qinshan NPP, D Liaoning NPP
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Safety Assessment /Performance Assessment /
Safety Analysis

• Safety Assessment
• A comparison of the results of safety analysis
  with acceptability criteria, its evaluation, and
  the resultant judgements made on the
  acceptability of the system assessed.
• Safety Analysis
• The analysis and calculation of the hazards
  (risks) associated with the implementation of a
  proposed activity.
• Performance Assessment
• Analysis to predict the performance of the system
  or subsystem, followed by comparison of the
  results of such analysis with appropriate
  standards or criteria. When the system under
  consideration is the overall waste disposal
  system and the performance measure is
  radiological impact or some other global measure
  of impact on safety, performance assessment
  becomes the same as safety assessment.

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Rewetting of EBS for the first 1,000 yr

• Heat source at the center
• The buffer is initially dry.
• Water in the surrounding rock will be inbibed by
  capillary suction.
• Air that exists in the buffer pores will be
  driven outward by heat.
• Two-phase mass and heat transfer analysis

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Selections of Radionuclides for Safety Assessment
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Low-Level Waste NRC(I)

• From 10 CFR 61.55, 25mrem/y to general public,
  100mrem/y or 500mrem one time to intruder (WBD)
• Site-generic, scenario-based, intruder risk
  assessment (NRC)
• Site-specific, migration risk assessment (site
  operator)

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Volume of LLRW from California disposed of at
commercial facilities. The 1980-1985 data and
the trendline are from Hayden (1997). Data from
1986-1998 are from the Manifest Information
Management System (MIMS) data base. Data do not
include waste disposed at Envirocare before 1998.
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Volume of solid LLRW processed from nuclear power
reactors per reactor unit (NEI 2000).
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LLRW by Radioactivity
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LLRW by Volume
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LLRW by Waste Class
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Low-Level Waste NRC(II)
Intruder Scenarios Construction, Agriculture
Intruder Dose i radionuclide j pathway
H 50y dose commitment CW nuclide
concentration f factor (time delay, site design
operation, waste form package, or site
selection) that is a function of detailed
indices (dispersability, leachability,
accessibility) PDCF pathway dose conversion
factor Each factor is functionally independent