University of Leeds Student Sustainability Research Conference 2019 Leeds UK Alexander P G Lockwood BEng Supervisors Dr Timothy Hunter Dr David Harbottle Dr Nicholas Warren Prof Jeffrey ID: 798049
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Slide1
Decommissioning of Spent Nuclear Fuel Ponds
University of Leeds Student Sustainability Research Conference 2019, Leeds, UK.
Alexander P. G. Lockwood, BEng
Supervisors:
Dr Timothy Hunter
, Dr David Harbottle, Dr Nicholas Warren, Prof Jeffrey
Peakall
, Martyn Barnes and Prof Geoff Randall
Slide2Presentation Outline
Introduction to the UK nuclear fuel cycle
Current state of storage ponds and current strategies
Application of Dissolved Air Floatation (DAF)
Research
Conclusions
Future work
Slide3Magnox Reactors
Slide4Magnox Reactors
Gas cooled (CO
2
)
Metallic Uranium fuel
Magnox Fuel cladding
Designed for optimum plutonium production as well as civil use
In service till 2015
26 in the UK
Slide5Reactor
Slide6Cooling fins
Uranium metal fuel pellet
Cladding
Magnox Skip
Reactor
Slide7Cooling fins
Uranium metal fuel pellet
Cladding
Magnox Skip
Reactor
Magnox
Sellafield
Shielded Transport Flask
Slide8Cooling fins
Uranium metal fuel pellet
Cladding
Magnox Skip
Reactor
Magnox
Sellafield
Shielded Transport Flask
Magnox Skip
Storage Pond
Slide9Cooling fins
Uranium metal fuel pellet
Cladding
Magnox Skip
Reactor
Magnox
Sellafield
Shielded Transport Flask
Magnox Skip
Storage Pond
Decanner
Slide10Cooling fins
Uranium metal fuel pellet
Cladding
Magnox Skip
Reactor
Magnox
Sellafield
Shielded Transport Flask
Magnox Skip
Storage Pond
Decanner
Clad Silo
Slide11Cooling fins
Uranium metal fuel pellet
Cladding
Magnox Skip
Reactor
Magnox
Sellafield
Shielded Transport Flask
Magnox Skip
Storage Pond
Decanner
Reprocessing
U & Pu
HAL
Clad Silo
Slide12Cooling fins
Uranium metal fuel pellet
Cladding
Magnox Skip
Reactor
Magnox
Sellafield
Shielded Transport Flask
Magnox Skip
Storage Pond
Decanner
Reprocessing
U & Pu
HAL
Clad Silo
Slide13Slide14Slide15Slide16Slide17Liquid effluent route
Slide18Slide19S
ite
I
on
e
X
change
E
ffluent
P
lant
Slide20pH≈7
pH≈11
CO
2
Pond and Silo feed
IX bed change
BSTs
Sampling
Discharge Tank
Irish Sea
Sand Bed Filter
Carbonation Tower
Ion Exchange Bed
Sampling and Discharge to Sea
Cs
137
& Sr
90
stripped
Slide21pH≈7
pH≈11
CO
2
Pond and Silo feed
IX bed change
BSTs
Sampling
Discharge Tank
Irish Sea
Sand Bed Filter
Carbonation Tower
Ion Exchange Bed
Sampling and Discharge to Sea
Mg solubilised
Mg competition for IX sites
Increase in bed changes and reduction in storage capacity
Cs
137
& Sr
90
stripped
Slide22Solid waste route
Slide23Increase in Waste volume to GDF
Slide24Strategy Requirements
Slide25DAF as an alternative Technology:
Consistent fine bubble generation with no external equipment or spargers.
Intense mixing with small bubbles achieving rapid flotation without mechanical agitation.
High throughput in a small footprint.
Fast response and easy control.
Steady operation and performance irrespective of changes in feed flow.
No moving parts, simple to install and maintain, excellent availability.
Slide26DAF How does it work?
Slide27Initial coverage
Monolayer coverage
Bilayer coverage
Collector Adsorption to Mg(OH)
2
Sodium Dodecyl Sulphate selected as a collector due to its anionic hydrophilic head group
Methyl isobutyl carbinol was selected as a frothing agent
Slide28DAF experimental set-up and investigated properties:
Slide29DAF experimental set-up and investigated properties:
Recovery Percentage (
R
%
)
DAF experimental set-up and investigated properties
:
Recovery Percentage (
R
%
)
Residual Volumetric Concentration (
ξ
%
)
DAF experimental set-up and investigated properties:
Recovery Percentage (
R
%
)
Residual Volumetric Concentration (
ξ
%
)
Volume Reduction Factor (
V
red
)
Recovery percentage:
Slide33Recovery percentage:
General increase with increasing dose of SDSPlateaus at a maximum of 93%
Contrary to adsorption data on the face of it
Slide34Recovery percentage:
General increase with increasing dose of SDSPlateaus at a maximum of 93%
Contrary to adsorption data on the face of it
Optimum should be around 10-100μM but extraction increase continues
Slide35Recovery Factor and Residuals Concentration:
Slide36Entrainment:
Bubble of air
Entrained fluid
Slide37Entrainment (ideal case):
Bubble of air
Entrained fluid
Surface modified Mg(OH)
2
at the air water interface
Slide38Entrainment (real case):
Bubble of air
Entrained fluid
Surface modified Mg(OH)
2
at the air water interface
Surface modified Mg(OH)
2
in the entrained fluid (too small to float)
Slide39Slipstream displacement:
-
As a bubble rises, it displaces fluid and forms a slipstream
-Smaller now hydrophobic particulates get caught in this slipstream unable to interact with the water-air interface
-Floatation sweet spot roughly 20-100
μ
m
Slide40Conclusions:
Given the surface charge properties of the suspended Mg(OH)
2
in Sellafield’s First-Generation Magnox Storage pond, an anionic surfactant such as sodium dodecyl sulphate can be used for rapid extraction.
The technology is successful in extracting Mg(OH)
2
via hydrophobic interaction with SDS
Addresses UK nuclear specific issues (low foot print, no moving parts etc.)
Monolayer development concentration found in this paper to be in the range of 20-100
μM
.
Optimisation of
frother
agent with determined optimum collector concentration for reduction in entrainment carry over work still required
Slide41Ack
nowledgements
Slide42Any questions?
pm2a2l@leeds.ac.uk