Aims
Overview of ORION fuel cycle modelling
computer code
With illustration of fast reactor scenarios
in the UK
ORION development started 15 years
ago following BNFL’s need to have a
‘holistic’ view of the fuel cycle
Requirements:
Easy to use
Robust and accurate physics methods
General enough to model virtually any
fuel cycle (steady state or at
equilibrium)
(image: Areva)
A model can contain any number of objects connected in any way:
Buffer
Fabrication plant
Reactor
Active process plant (e.g. reprocessing plant)
Passive process plant (e.g. cooling pond)
External feed
Variable time step (1 month up to 1 year)
Up to 10 feeds can be defined for each object
For fuel with a varying fissile quality, reactivity equivalence coefficients can be used to
estimate the fissile fraction required
Performs decay and transmutation calculations, tracking 2552 nuclides:
Dynamic control of reactor deployment
ORION – the basics
DECC studies
UK Government: 80% CO2 emission cuts by 2050
Recognised potential contribution from nuclear power as well as other low CO2 energy
sources
NNL is in the process of formulating a UK funded nuclear R&D
programme to support national strategic goals:
CO2 reduction
energy security
long term sustainability
Fuel cycle assessments performed to help highlight benefits of a
particular reactor or fuel and to help guide and justify a future R&D
programme:
Legacy plutonium reuse in new build or purpose-procured reactors?
Future reprocessing?
Thorium fuel cycle and MSR use?
Future fast reactors?
Only sodium cooled fast reactor fuel cycles considered in this
presentation
Purpose of these calculations were to:
Gauge how difficult it will be for the UK to transition to a MOX fuelled SFR
closed fuel cycle
The impact fast reactor spent fuel cooling time will have on VHLW waste
volumes
The impact of recycling Am (and Np) will have on a future UK repository
The impact a single or multiple generation of fast reactors would have on
the repository
Scope
Closed fuel cycle
Reprocessing
Throughput
Geological
Disposal (100 yr interim
storage)
MAGNOX+AGR+SxB New build LWR Newer built fast reactor fleet (target)
Different capacities
modelled – 70 Gwy(e)
is an ’ambitious’
maximum
?
MAGNOX
THORP
Future LWR (separating Pu + U)
SFR (separating Pu + U (+ Np and Am)
Pu availability for an SFR fleet
Max SFR fleet 10%-20% lower
than preceding LWR fleet size
Assuming all PWR used fuel reprocessed
5 years cooled (+2 yrs for rep/fab)
No MOX use in LWR fleet
Impact of cooling time on spent fuel handling and reprocessing ..
Inventories will eventually be used to help develop reprocessing flowsheets
2 year
5 year
.. Impact on VHLW volumes and interim storage requirements
SFR Results PWR Results Legacy
2 y
ears
2 y
ears
, N
p+
Am
recycle
5 y
ears
5yr, N
pAm
2.5kW/canister
Impact on repository footprint
Over short time scales, thermicity (decay heat) of the nuclear waste is
limiting
Repository footprint will depend on total decay heat
Thermal limits ensure surrounding bentonite clay remains < 90oC
Decay heat of material entering repository integrated up to 2450 (roughly
200-300 years in repository) – relative sizes of the HLW portion of the
repository can be estimated
Thermicity from a finite fuel cycle
1 generation of PWRs followed by
1 generation of SFRs recycling Pu and Am
1.0
0.56
0.41
Finite vs. equilibrium
Rep. size (HLW) halved
if Pu is recycled through
a fast reactor fuel cycle Significant amount of Am in
fast reactor spent fuel once
the SFR fleet is retired
Np/Am recycle results in a
factor of 6-7 drop in decay
energy deposited in repository,
assuming indefinite operation
Conclusions
Maximum fast reactor fleet size 10-20% smaller than
preceding LWR fleet
Small preceding LWR fleet = small fast reactor fleet
Reducing cooling time from 5 to 2 years results in no drop in SFR fleet
size …
However, VHLW waste volumes increase by a factor of 2-3 and
reprocessing becomes more challenging
Fast reactor closed fuel cycle (single generation) reduces
thermicity of spent fuel by a factor of 2:
Recycling Np+Am reduces thermicity by a further 10%.
Thermicity dominated by final SFR cores
More noticeable if fuel cycle operates indefinitely (6 – 7x improvement)
Current day and future nuclear in the UK
• Sizewell
• Bradwell
• Dungeness Hinkley Point •
Berkeley and Oldbury •
Wylfa •
Trawsfynydd •
Heysham •
Calder Hall/Sellafield •
Chapel Cross •
Hunterston •
• Torness
• Hartlepool
MAGNOX
AGR
PWR (Sizewell B)
NEW BUILD
CURRENT DAY UK NUCLEAR INDUSTRY
MAGNOX stations– all spent fuel reprocessed (11)
AGR stations- some spent fuel reprocessed (6)
PWR station (Sizewell B) (1) – spent fuel stored on site (wet, and soon dry)
FUTURE POSSIBLITIES
UK has a commitment to radically cutting green house gas emissions by 2050
Possible new build sites (7 sites)?
Sizewell (2 x EPR?)
Hinkley Point (2 x EPR - definite)
Oldbury (2 x ABWR?)
Wylfa (2/3 x ABWR?)
Cumbria (Sellafield) (AP1000s?)
Bradwell, Hartlepool, Heysham (?)
Eventually >125tHM separated Pu (Sellafield)
Pu-use in new build/purpose-procured reactors?
RepU-reuse in Sizewell B and new build fleets ?
Future reprocessing of PWR spent fuel in 2050?
Replacement closed fast reactor fleet from 2050?
Separated Pu
These policies requires fuel cycle scenario assessments to estimate their impact – the UK Nuclear Fission Roadmap