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Decommissioning of Spent Nuclear Fuel Ponds Decommissioning of Spent Nuclear Fuel Ponds

Decommissioning of Spent Nuclear Fuel Ponds - PowerPoint Presentation

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Decommissioning of Spent Nuclear Fuel Ponds - PPT Presentation

  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

skip magnox reactor fuel magnox skip fuel reactor storage uranium cladding pond metal cooling recovery pellet bed fins daf

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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

Slide2

Presentation 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

Slide3

Magnox Reactors

Slide4

Magnox 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

Slide5

Reactor

Slide6

Cooling fins

Uranium metal fuel pellet

Cladding

Magnox Skip

Reactor

Slide7

Cooling fins

Uranium metal fuel pellet

Cladding

Magnox Skip

Reactor

Magnox

Sellafield

Shielded Transport Flask

Slide8

Cooling fins

Uranium metal fuel pellet

Cladding

Magnox Skip

Reactor

Magnox

Sellafield

Shielded Transport Flask

Magnox Skip

Storage Pond

Slide9

Cooling fins

Uranium metal fuel pellet

Cladding

Magnox Skip

Reactor

Magnox

Sellafield

Shielded Transport Flask

Magnox Skip

Storage Pond

Decanner

Slide10

Cooling fins

Uranium metal fuel pellet

Cladding

Magnox Skip

Reactor

Magnox

Sellafield

Shielded Transport Flask

Magnox Skip

Storage Pond

Decanner

Clad Silo

Slide11

Cooling 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

Slide12

Cooling 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

Slide13

Slide14

Slide15

Slide16

Slide17

Liquid effluent route

Slide18

Slide19

S

ite

I

on

e

X

change

E

ffluent

P

lant

Slide20

pH≈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

Slide21

pH≈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

Slide22

Solid waste route

Slide23

Increase in Waste volume to GDF

Slide24

Strategy Requirements

Slide25

DAF 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.

Slide26

DAF How does it work?

Slide27

Initial 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

Slide28

DAF experimental set-up and investigated properties:

Slide29

DAF experimental set-up and investigated properties:

Recovery Percentage (

R

%

)

 

Slide30

DAF experimental set-up and investigated properties

:

Recovery Percentage (

R

%

)

 

Residual Volumetric Concentration (

ξ

%

)

 

Slide31

DAF experimental set-up and investigated properties:

Recovery Percentage (

R

%

)

 

Residual Volumetric Concentration (

ξ

%

)

 

Volume Reduction Factor (

V

red

)

 

Slide32

Recovery percentage:

Slide33

Recovery percentage:

General increase with increasing dose of SDSPlateaus at a maximum of 93%

Contrary to adsorption data on the face of it

Slide34

Recovery 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

Slide35

Recovery Factor and Residuals Concentration:

Slide36

Entrainment:

Bubble of air

Entrained fluid

Slide37

Entrainment (ideal case):

Bubble of air

Entrained fluid

Surface modified Mg(OH)

2

at the air water interface

Slide38

Entrainment (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)

Slide39

Slipstream 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

Slide40

Conclusions:

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

Slide41

Ack

nowledgements

Slide42

Any questions?

pm2a2l@leeds.ac.uk