Dr Tim Johnson presents at the Nuclear Decommissioning and Waste Management Congress in London.

1. Plasma Vitrification of ILW
Date: 14th
September 2016
Dr Tim Johnson
Tetronics International
Swindon, UK

2. 2
OVERVIEW OF CONCEPT DESIGN
COMMERCIAL IN CONFIDENCE

3. 3
Waste Streams
Legacy sludges
Selected for continuity of
development
~3500m3
Decommissioning wastes
Selected for new challenge to technology
~10,000m3
Shielding and remote operation
Transport
Containment
Heterogeneity

4. 4
Description
Material allowed to solidify and cool in-situ within crucible, so no requirement for pouring
or tapping equipment

5. 5
Basis of Operations and Maintenance
Operations
Processing to recipes
Control on inputs
Remote operation
Focus on primary containment
Maintenance
Remote dismantling of process equipment
Limited access to process cells to maintain other items

6. 6
Basis of Safety
System is always a net-consumer of energy
Process prevents accumulation of explosive gases
Standard nuclear ventilation and shielding dealing with radiological
hazard
Criticality hazard managed by geometry

7. 7
Scale
Test rig designed to ensure product could fit through lid of 3m3
ILW box
Can be implemented for any realistic size container
At test rig scale: 0.5m3
feed per day per furnace
Furnaces can run in parallel

8. 8
DESIGN OF DEMONSTRATION FACILITY
COMMERCIAL IN CONFIDENCE

9. 9
Demonstration Plant
COMMERCIAL IN CONFIDENCE
Feeding of sludges
and fluxes
Twin electrodes
Plant cell (cage)
Plasma furnace
Water-cooled ‘clam
shell’ and base
Remote loading and
unloading of crucible
Simulated final waste
container roof

10. 10
Design of Demonstration Plant
Based on concept design and corresponding safety case
Engineering schedule developed for demonstration plant
Design of furnace cell based around key design features including:
Remote loading of crucible into cooling jacket
Remote vertical and horizontal movement of crucible
Monitoring of furnace seal integrity
Furnace clamp mechanisms
Replaceable roof refractory
COMMERCIAL IN CONFIDENCE

11. 11
Crucible
COMMERCIAL IN CONFIDENCE

12. 12
Objectives of Trials
Demonstrate flexibility of plasma system to treat multiple waste streams:
SIXEP sludge
Magnox sludge
Future decommissioning waste
Demonstrate maximum passivation and stabilisation of vitrified product
Maximise volume reduction
Demonstrate maximum retention of caesium in the vitrified product
Confirm that critical components deliver their process and safety
functions, as per HAZOP study
Investigate factors affecting plasma vitrification process performance:
Volume reduction, process stability, homogeneity, throughput, off
gas treatment demand, etc.
COMMERCIAL IN CONFIDENCE

13. 13
Composition of Surrogate Wastes
Species SIXEP wt% MAGNOX wt%
Water 37.00 49.00
Caustic soda 7.98 1.27
Magnesium hydroxide 4.37 37.39
Silica sand 6.99 -
Dry Clinoptilolite 43.67 -
Cellulose - 2.16
Magnesium carbonate - 6.36
Aluminium oxide - 3.81
Total raw feed (wt %) 100.00 100.00
Inactive Cs (ppm) 1432 2521
COMMERCIAL IN CONFIDENCE
Species Future Decommissioning Waste wt%
Stainless steel 15.82
Mild steel 2.92
Plastic (non-chlorinated i.e. PE) 6.00
Rubber (PS) 2.00
Cellulose 1.40
Glass 4.70
Concrete and Brickwork 67.15
Total raw feed 100.00%
Inactive Cs (ppm) >2185

14. 14
Slag Composition Control
Species SIXEP Magnox FD waste
Raw waste simulants 100 % 59% 92%
Silica sand, flux - 30% -
Aluminium oxide, flux - 11% -
Calcium Carbonate, flux - - 8%
Total 100 % 100 % 100 %
COMMERCIAL IN CONFIDENCE
Fluxes are added to ensure low
melting point and good fluidity
Allowing the material to solidify in-
situ reduces accuracy of composition
control required
Ternary diagram (right) shows
example of target composition after
fluxing

15. 15
OVERVIEW OF RESULTS
COMMERCIAL IN CONFIDENCE

16. 16
KEY RESULTS
SIXEP ILW SIMULANT
COMMERCIAL IN CONFIDENCE

17. 17
Mass Balance - SIXEP
COMMERCIAL IN CONFIDENCE
Inputs: Mass, kg % of Input
Solid in waste simulant 553.51 63.0%
Water in waste simulant 325.08 37.0%
Flux in blended waste simulant 0.00 0.00%
Total mass input 878.59 100.0%
Outputs:
Vitrified slag 446 50.8%
Furnace exit duct dust 1.51 0.2%
Combustion chamber dust 0.12 0.0%
Filter bag-house dust 9.14 1.0%
Total solid mass output 456.77 52.0%

18. 18
Plasma characteristics
COMMERCIAL IN CONFIDENCE
Continuous Feeding Mode

19. 19
Cs Retention – SIXEP (MCerts Gas Analysis)
Sample 1 Sample 2
Waste type SIXEP SIXEP
Trial No SIXEP005 SIXEP005
Feed rate kg/h 30 30
Caesium Nitrate (CsNO3) mg/kg feed material 2272 2272
Caesium (convert to Cs ) mg/kg feed material 1550 1550
Duration minutes 30 30
Corrected Sampled Gas Vol. Nm3@STP 0.103 0.139
Caesium Concentration @ STP (mg/m3) 194 108
Caesium (Cs ) in off gas mg 20.0 15.0
Caesium (Cs ) in feeding during 30 mins mg 774.8 774.8
Cs loss in off gas % wt 2.58 1.94
COMMERCIAL IN CONFIDENCE
Caesium detected in off gas analysis indicates c.98% retention of the caesium is possible with recycling
of the solid off gas products, based on the trials facility off gas abatement system.

20. 20
Caesium Retention - SIXEP
COMMERCIAL IN CONFIDENCE
• Results presented above are for single pass operation.
• Total retention of c.98% retention of the caesium is possible with recycling of
the solid off gas products, based on the trials facility off gas abatement
system.
kg % of Output
Outputs:
Cs in vitrified slag, kg 0.978 93.5%
Cs in off gas duct dust, kg 0.057 5.4%
Cs in combustion chamber dust, kg 0.000 0.0%
Cs in filter unit dust, kg 0.012 1.1%
Cs in solid output, kg 1.066 100.0%

21. 21
Volume Reduction
COMMERCIAL IN CONFIDENCE
Sludge fed during trial, m3
0.112
Vitrified slag volume, m3
0.043
Volume reduction (without crucible) 61%
Maximum vitrified slag volume, m3
0.108
Sludge volume required, m3
0.280
Maximum final wasteform volume, m3
0.278
Volume reduction (with crucible) 1%

22. 22
KEY RESULTS
FD WASTE SIMULANT
COMMERCIAL IN CONFIDENCE

23. 23
Mass Balance – FD Waste
COMMERCIAL IN CONFIDENCE
Inputs: Mass, kg % of Input
Solid waste simulant - Batch 1 65.7 55.2%
Solid waste simulant - Batch 2 43.8 36.8%
Solid oxidant in blended feedstock (total) 9.5 8.0%
Total mass input 119.02 100.0%
Outputs:
Slag 88 73.9%
Furnace exit duct dust 1.416 1.2%
Combustion chamber dust 0 0.0%
Filter bag-house dust 0 0.0%
Total solid mass output 89.416 75.1%

24. 24
Plasma characteristics
COMMERCIAL IN CONFIDENCE
Plasma off;
inspect melt;
FD batch 1
FD batch 2
Plasma off;
Slag cooling;
Electrode reset;
Load batch 2 to
crucible

25. 25
Caesium Retention – FD Waste
COMMERCIAL IN CONFIDENCE
Mass, kg % of Output
Outputs:
Cs in vitrified slag, kg 0.514 95.5%
Cs in off gas duct dust, kg 0.024 4.5%
Cs in combustion chamber dust, kg - 0.0%
Cs in filter unit dust, kg - 0.0%
Mass of Cs in output, kg 0.538 100.0%
• Results presented above are for single pass operation.
• Partitioning of caesium is consistent with SIXEP, suggesting possible total
retention of c.98% with recycling of the solid off gas products.

26. 26
Volume Reduction
COMMERCIAL IN CONFIDENCE
Pre-loaded FD waste (Batch 1) Processed FD waste (Batch 1)
4 hours
FD waste trials Trial No Batch 1 &2
Total blended FD waste fed, m3
0.125
Vitrified slag volume, m3
0.046
Volume reduction (without crucible) 63%
Maximum vitrified slag volume, m3
0.108
FD waste volume required, m3
0.295
Maximum final wasteform volume, m3
0.278
Volume reduction (with crucible) 6%

27. 27
KEY RESULTS
COMMERCIAL IN CONFIDENCE

28. 28
Retention of Caesium
COMMERCIAL IN CONFIDENCE
Demonstrated flexibility of technology to treat and stabilise a wide range
of waste streams
Circa 98% retention of Cs in glassy matrix by recycling off-gas dusts
Clear potential to increase storage efficiency by using thinner refractory
and increasing crucible depth
Technology demonstrated to full-scale pilot plant scale with surrogates
Proof-of-concept studies conducted on a wide range of ILW and LLW
surrogates in conjunction with UK Nuclear Industry partners
Long track record of vitrification applications outside the nuclear industry
Recent Industry Day presentation attended by NDA, NNL, AWE, Sellafield
Ltd, MoD, EDF and others has led to significant interest

29. Marston Gate
South Marston Park
Stirling Road
Swindon, SN3 4DE
Tel : +44 (0)1793 238500
Thank you
Contact:
Dr Tim Johnson – Technical Director, Tetronics: tim.johnson@tetronics.com
Mr Stephen Gill – Sales Director, Tetronics: stephen.gill@tetronics.com
Dr Bryony Livesey – Head of Research & Technology, Costain: bryony.livesey@costain.com