1. Accelerator Driven Subcritical Reactors with thorium fuel
Doctoral Training Course
University of Huddersfield
11 April 2013
Accelerator Driven Subcritical Reactors
with thorium fuel
Bob Cywinski
School of Applied Sciences
International Institute for Accelerator Applications

2. The Global Energy Crisis

3. The Carbon Problem Energy source Grams of CO2 per KWh of electricity
Nuclear 4
Wind 8
Hydro electric
Energy crops 17
Geothermal 79
Solar
133
Gas
430
Diesel
772
Oil
828
Coal
955
source:
Government Energy Technology Support Unit (confirmed by OECD)

4. Current nuclear supply
Country No. Reactors GW capacity % Total Electricity
France
Sweden
South Korea
Japan
Germany
United States
Russia
United Kingdom
Canada
India
21 Others
Totals:
But this represents only 5% of global energy consumption
To increase this by x5 would reduce carbon emissions by 25%

5. Fission

6. Conventional Reactors

7. Uranium as nuclear fuel
Natural uranium:
99.3% U-238, 0.7% U-235
Enriched uranium
97% U-238, 3% U-235

8. Uranium requirements Scenario 1 No new nuclear build Scenario 2
Maintain current nuclear capability
(implies major increase in plant construction)
Scenario 3
Nuclear renaissance: increase in nuclear power generation to 1500 GW capacity by 2050

9. Breeding nuclear fuel Natural uranium: 99.3% U-238, 0.7% U-235
Enriched uranium
97% U-238, 3% U-235

10. Retaining the nuclear option
the nuclear option should be retained precisely because it is an important carbon-free source of power….
....but there are four unresolved problems:
high relative costs
perceived adverse safety, environmental, and health effects
potential security risks stemming from proliferation
unresolved challenges in long-term management of nuclear wastes.

11. Annual global use of energy resources
5x109
tonnes of coal
5x103 tonnes of thorium
An alternative fuel?
27x109
barrels of oil
2.5x1012 m3 natural gas
65x103
tonnes of uranium

12. Thorium resources

13. Breeding fuel from thorium
Advantages
Does not need processing
Generates virtually no plutonium and less higher actinides
233U has superior fissile properties n
232Th
233Th
233Pa
233U b g
27 days
22 mins
Disadvantages
Requires introduction of fissile seed (235U or Pu)
The decay of parasitic 232U results in high gamma activity from 208Tl.

14. Advantages of thorium: waste
100
1,000
10,000
100,000
1,000,000
10,000,000 10
100,000,000
1,000,000,000
100,000

15. Past experience with thorium:

16. Breeding fuel from thorium
Advantages
Does not need processing
Generates virtually no plutonium and less higher actinides
233U has superior fissile properties n
232Th
233Th
233Pa
233U b g
27 days
22 mins
Disadvantages
Requires introduction of fissile seed (235U or Pu)
The decay of parasitic 232U results in high gamma activity from 208Tl.

17. Spallation
ISIS
200kW
SNS (1 MW)
J-PARC (1MW)

18. Spallation neutrons
The energy spectrum of proton induced spallation neutrons .
The target is a lead cylinder of diameter 20 cm
At 1 Gev, approximately 24 neutrons per proton are produced

19. Spallation neutrons
Number of neutrons per unit energy of incident proton

20. The Accelerator Driven Subcritical Reactor

21. 3. The Accelerator Driven Subcritical Reactor

22. Accelerator power The (thermal) power output of an ADSR is given by
with N = number of spallation neutrons/sec
Ef = energy released/fission (~200MeV)
ν = mean number of neutrons released per fission (~2)
keff= criticality factor (<1 for ADSR)
So, for a thermal power of 1550MW we require
Given that a 1 Gev proton produces 24 neutrons (in lead) this corresponds to a proton current of

23. Accelerator power keff=0.95, i=33.7mA keff=0.99i=6.5mA
To meet a constraint of a 10MW proton accelerator we need keff>0.985

24. Accelerator power So, for a thermal power of 1550MW we require
Given that a 1 Gev proton produces 24 neutrons (in lead) this corresponds to a proton current of

25. Accelerator power

26. A Thorium Fuelled ADSR
1. Initial loss due to build-up of absorbing Pa233 and decrease of U233 enrichment by neutron absorption and fission 1 2
2. Increase due to increasing U233 enrichment from subsequent β-decay of Pa233 3
3. Long term decrease due to build up of neutron absorbing fission products
H.M. Broeders, I. Broeders :
Nuclear Engineering and Design 202 (2000) 209–218

27. Evolution of the criticality value, keff
Parks (Cambridge)

28. Evolution of power output
Coates, Parks (Cambridge)

29. Accelerator power

30. ADSR Shutdown
Parks (Cambridge)

31. The ADSR as an energy amplifier
600 MW
Electrical Power
10MW Accelerator
20 MW
electrical
1550MW Thermal Power

32. “A reactor needs an accelerator like a fish needs a bicycle…”

33. Waste management

34. The ADSR for waste management

35. Applications of Accelerator Driven Systems
Applications of Accelerator Driven Systems Technology
Transmuting selected isotopes present in nuclear waste (e.g., actinides, fission products) to reduce the burden these isotopes place on geologic repositories.
Generating electricity and/or process heat.
Producing fissile materials for subsequent use in critical or sub-critical systems by irradiating fertile elements.
Transmuting selected isotopes present in nuclear waste (e.g., actinides, fission products) to mitigate the need for geologic repositories.
Generating electricity and/or process heat
Producing fissile materials for use in conventional critical or novel sub-critical reactors by irradiating fertile precursors.

36. Waste management
From: Hamid Aït Abderrahim (MYRRHA)

37. ADSR Projects: MYRRHA The MYRRHA Project
1b€ European project to build an ADSR for transmutation and waste management (2015)
Abderrahim et al., Nuclear Physics News, Vol. 20, No. 1, 2010

38. ADSR Projects: Aker/Jacobs
Keff
Accelerator 3MW
ADSR MW

39. ADSR Projects: Aker/Jacobs

40. Towards an ADSR ??

41. Proton drivers? Cyclotron Synchrotron Linac
High Current (<A) Low Energy (600MeV)
Continuous beam
Synchrotron
Low Current (<mA) High Energy (TeV)
Pulsed Beam
Linac
High Current, High Energy
Pulsed or continuous beam
Large and expensive

42. Why has no ADSR been built?
...because accelerators are relatively unreliable

43. Why has no ADSR been built?
...because accelerators are relatively unreliable,
(largely because of ion source and RF issues )
From: Ali Ahmad

44. Technology readiness assessment (US)

45. EMMA – the world’s first ns-FFAG

46. EMMA – the world’s first ns-FFAG

47. Multiple FFAG proton injection
Multiple injection:
- mitigates against proton beam trips and fluctuations
- homogenises power distribution across ADSR core
Patent taken out on multiple injection

48. The way forward?
In 2009 Science Minister, Lord Drayson, asked ThorEA to prepare a report outlining what might be needed to deliver the technology to build the world’s first ADSR power station ThorEA delivered that report in October 2009 .
Interest in thorium is now growing:
eg Weinberg Foundation,
All Party Parliamentary Group on Thorium, Annual International Conference (IThEC)

49. IAEA support
“IAEA warmly welcomes the proposed accelerator driver development programme embodied in the ThorEA project as a positive contribution to the international effort to secure the eventual global deployment of sustainable thorium-fuelled ADSR power generation systems…”
I A E A
Alexander Stanculescu
Nuclear Power Technology Development Section
International Atomic Energy Agency (IAEA)
Vienna

50. Conclusions
Thorium has been used in the past and could now be deployed in conventional, molten salt, ADS and even hybrid MS/ADS reactors providing an alternative, sustainable, safe, low waste and proliferation-resistant technology for nuclear power generation
780kg of thorium = 200 tonnes of uranium (as currently used)
No plutonium is used and very little is produced
After 70 years the radiotoxicity is 20,000 times less than an equivalent conventional nuclear power station
Thorium systems provide means of burning existing legacy waste
Waste can be mixed with thorium and burnt as fuel, reducing radiotoxity by orders of magnitude and turning a liability into an asset
But......
Significant R&D has to be carried out on:
Materials research (particularly for MSR systems)
Improving accelerator reliability (for ADSR and hybrids)
Beam, spallation target and blanket interfaces

51. Thank you !
Thank
You!