Presented by: Nigel Donaldson

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Presented by Nigel Donaldson
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Composition of Irradiated - PWR Fuel
(30,000MWD/te)
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Some Nuclear Fuel Cycle Alternatives

• Direct Disposal (Once through)
• Thermal Recycle
• Fast Breeder/Recycle
• Minor Actinide Burning (Fast Neutron)

Using Reprocessing
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Current Fuel Storage Available (Pond, Casks,
Vaults.)
Current Global Stocks 340,000 Tonnes Heavy
Metal By 2010 (IAEA - May 2002) Disposal demonstra
tion, no commercial operations
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Thermal Recycle Model
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• Purex Technology
• Cap La Hague (France)
• Two Plants
• Sellafield (UK)
• Two Plants
• Rokkashomura (Japan)
• One Plant
• Recycled commercially
• .uranium as uranium oxide fuel
• .plutonium as mixed oxide (MOx) fuel

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Fast Breeder Recycle Model
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Demonstration reactors in a number of states no
commercial operations
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Potential of UK stocks

• To realise the full potential of uranium and the
  Pu bred from it, requires fast-neutron reactors
• Current UK stockpile of depleted uranium, if used
  in fast reactor, would provide the energy
  equivalent of 35 x 109t oil
• Fast reactor unlikely to be deployed until well
  into the 21st century

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Wider Fuel Cycle Concepts
CURRENT
TRANSITIONAL
ADVANCED
ThO2?
UO2, (MOx)
Metal?
Fuel
Nitride?, Carbide?
ReducedPurex
Process
Purex
Thorex?
Novelaqueous partitioning
Molten Salt
Partition/Transmute
Packing
Vibro
Casting
Pellet
Reactor
Thermal Fast
Accellr
Thermal
Waste
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Commercial Reprocessing Technology- Aqueous
Partitioning - Purex Process
Receipt Storage
Head End
Chemical Plants
UraniumProduct to Fuel
PlutoniumProduct to Fuel
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Solvent extraction contactor technologies

• Mixer settlers
• Pulsed columns
• Thorp uses pulsed columns
• ..and mixer settlers .
• Centrifugal contactors have previouslybeen used
  but are not currently favoured

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Solvent Extraction - aka - Aqueous Partitioning
UP Cycle
Acid
Acid
Reducing Agent
HA Cycle
Reducing Agent
HA Feed
Acid
U
U Product
Pu
Reducing Agent
PP Cycle
Aqueous stream Solvent stream
Pu Product
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Products and Solid Wastes
Products
Uranium (of Residual Enrichment) as uranium
trioxide Plutonium as plutonium dioxide
Solid Wastes (Thorp average m3/tU oxide fuel
reprocessed)
High Level Wastes (HLW)
(Temperature may rise significantly)
0.07 Intermediate level Wastes (ILW)
(gtLLW but doesnt require heat
0.7
to be taken into account) Low
Level Wastes (LLW)
(Very low radioactive content)
1.8
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Volumes of Waste Produced from 1GW-year of
Electricity
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Aerial Liquid Discharge Impacts
For typical 100t fuel reprocessed

• Measured in terms of the number of Becquerels of
  radionuclide species discharged
• Converted into maximum dose to individuals in
  the community
• i.e. potentially most exposed to the discharge
  through
• work/diet/habits.
• Total Aerial (via stack) 1.0 microSv
• Total Liquid .0.27 microSv
• Total and species limits set by Environment
  Agency
• e.g. 3.3 x104 MBq for 129 I aerial discharges
  for 800t fuel throughput

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Radiation Impacts - Risks
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Typical annual doses to those exposed to radiation

• 20 mSv Regulatory dose limit for workers
• 2.5 mSv Average dose to us all from exposure to
  natural background radiation (8mSv in Cornwall)
• 2 mSv Average additional dose to airline crews
  through exposure to cosmic rays
• 1.3 mSv Average dose to a Sellafield radiation
  worker from occupational exposure (Thorp average
  about half 0.6mSv)
• 1 mSv Dose limit for members of the public from
  practices.
• 0.2 mSv Highest (critical group) dose to public
  from Sellafield
• i.e. those believed to be most at risk due to
  extreme behaviours/exposure patterns

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Other exposure sources

• 0.02 mSv Dose received from return flight from
  UK to Spain
• 0.0001 mSv Dose received by consuming one Brazil
  nut.
• Some bottled mineral waters drinking 1litre/d
  100microSv/y (0.1mSv)
• Total Aerial (via stack) 1.0 microSv
• Total Liquid .0.27 microSv

Potential dose to the most exposed members of
population
100t Fuel Reprocessing
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Plant Design Considerations

• Routine operations, fault conditions and external
  events- including discharges/environmental
  impacts
• Environmental assessments within Safety Cases aim
  to demonstrate BPM and BAT
• Restriction of radiation exposure and dose
  limitation legal requirement given in Ionising
  Radiation Regulations 99

• Doses should be ALARPHierarchy of protection
  measures

• design and engineering
• safety features and warning devices
• systems of work
• personal protective equipment

• Nuclear plant features
• Biological shielding
• Containment and ventilation
• Geometry

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Plant Design Accident Risks

• Translated into frequency targets dependant on
  the predicted consequences
• Separately considered for workforce and public

What sort of hazards are considered in safety
cases? radiological e.g. loss of
containment criticality e.g failure to control
amounts of fissile material shielding e.g.
routine dose uptake environmental discharges fire
and explosion e.g. safety of public and
workforce, environmental impacts conventional
e.g. control of moving machinery,
noise chemotoxic e.g. Control of Substances
Hazardous to Health (COSHH) external hazards
e.g. extreme weather, impacts
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Plant Design Safety Cases

• HAZOP/HAZAN approaches used to develop Safety
  Case
• considers all aspects of risk of plant operation,
  credible faults and environmental impacts
• balances the various sources of risk and
  demonstrates that the overall risk is ALARP (As
  Low As Reasonably Practical)
• Safety Case shows
• Designated equipment and procedures needed to
  ensure compliance with safety criteria
• Demonstration that plant achieves acceptable risk

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Plant Design Security and Safeguards

• Responsibility for physical protection system for
  nuclear materials and facilities within a State
  rests entirely with the Government of that State.
  
• Euratom and IAEA safeguards are applied to
  nuclear material in the UK.
• Generally use
• Containment and surveillance e.g. fuel/storage
  inventories
• Materials accountancy for in-process inventory
  (Near Real Time Materials Accountancy possible
  ..once an input measurement is available)
• Plant inventory taking and verification
• Three categories of material based on potential
  risk of materials use for a nuclear device
• The intensity of Euratom and IAEA safeguards
  measures (e.g. the frequency of inspection and
  the degree to which nuclear material is measured)
  is a function of the type and form of the nuclear
  material concerned

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Economics
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Reprocessing versus Direct Disposal Economics

• OECD/NEA study, published in 1994, assessed the
  total fuel cycle costs, typically

Disposal
min
Reprocess
max
0
1
2
3
4
5
6
7
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Fuel Cycle Costs at 5 discount rate
(Mils/kWh) (1Mil 10-3 US Dollars) 14
difference (Undiscounted Difference lt5)
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The OECD/NEA study concluded
In light of the underlying cost uncertainties,
the small cost difference between reprocessing
and the direct disposal options is considered to
be insignificant and in any event represents a
negligible difference in overall cost terms.
It is likely that considerations of national
energy strategy including reactor type,
environmental impact, balance of payments and
public acceptability will play a more important
role in deciding a fuel cycle policy than the
small economic difference identified.
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Comparison of Fuel Cycle Impacts on Pu Stocks
Once through
t Pu
400
Repository
200
Pu Store
Spent Fuel
Reactor
0
1990
2000
2010
2020
2030
2040
2050
2060
2070
Total Plutonium Inventory
Fast Recycle
t Pu
200
Spent fuel
Reactor
Pu Store
Fuel Fab.
0
1990
2000
2010
2020
2030
2040
2050
2060
2070
Total Plutonium Inventory
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Estimated World Primary Energy Resources
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Plant Design and Standards Dose Limits

• Whole body dose (effective dose) to Radiation
  worker
• Legal limit is 20mSv/y (IRR99)
• BNGSL individual limit is 15mSv/y
• BNGSL target is average to workforce not greater
  than 5mSv/y
• (Operationally Thorp achieves - max 2-4 and ave
  0.6..mSv/y)
• Whole body dose (effective dose) to member of
  public - 1 mSv/y
• Eye and extremity dose limits subject to separate
  limits

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PWR HLW - Groundwater Pathway (Sv/y)
1 microSV