Bob Cywinski International Institute for Accelerator Applications Why thorium? Why Accelerators? PASI 13 January 2012
The Global Energy & Climate Crises
Current nuclear electricity supply Country N o. Reactors GW capacity % Total Electricity United States France Japan United Kingdom Germany Russia So. Korea Canada India Sweden Others Totals: but this represents only 5% of global energy consumption
The Carbon Problem Energy source Grammes of carbon per KWh of electricity Nuclear 4 Wind 8 Hydro electric 8 Energy crops Geothermal Solar Gas Diesel Oil Coal source: Government Energy Support Unit (confirmed by OECD)
The Uranium Fuel Cycle Enriched uranium 97% U-238, 3% U-235 Natural uranium: 99.3% U-238, 0.7% U-235
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
Breeding nuclear fuel Enriched uranium 97% U-238, 3% U-235 Natural uranium: 99.3% U-238, 0.7% U-235
Annual global use of energy resources 5x10 9 tonnes of coal 27x10 9 barrels of oil 2.5x10 12 m 3 natural gas 65x10 3 tonnes of uranium 5x10 3 tonnes of thorium An alternative fuel?
Thorium resources
Breeding fuel from thorium Advantages Does not need processing Generates virtually no plutonium and less higher actinides 233 U has superior fissile properties Disadvantages Requires introduction of fissile seed ( 235 U or Pu) Parasitic 232 U production results in high gamma activity.
Advantages of thorium Thorium fuel cycle thorium reactor
Advantages of thorium: waste 100, ,00010, ,000 1,000,00010,000, ,000 10, ,000 1,000,000 10,000, ,000,000 1,000,000,000
Past experience with thorium “There is little chance that thorium-fuelled nuclear reactors will play a major role in meeting the UK’s future energy requirements No thorium reactor design has been implemented beyond relatively small, experimental systems” Baroness Tina Stowell, Government spokesman on energy and climate change House of Lords November 2011 The UK’s perspective:
Past experience with thorium: the reality
Past experience with thorium
The Indian thorium strategy 500 MW prototype FBR is under construction in Kalpakkam is designed to breed 233 U-from Th The FBR is expected to be operating shortly, fuelled with uranium-plutonium oxide with a blanket of thorium and uranium to breed fissile U-233 and plutonium respectively
Potential deployment of thorium 1. Thorium as fuel in conventional reactors:
Potential deployment of thorium 2. Thorium as fuel in molten salt reactors:
Potential deployment of thorium 3. Thorium as fuel in an energy amplifier: Rubbia et al., CERN/AT/93-47 (ET), CERN/AT/95-44 (ET) Phys Rev C73, (2006) also MSR option: C.D.Bowman, NIM A320, 336 (1992)
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
The Accelerator Driven Subcritical Reactor
Accelerator power The (thermal) power output of an ADSR is given by withN = number of spallation neutrons/sec E f = energy released/fission (~200MeV) ν = mean number of neutrons released per fission (~2) k eff = 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
Accelerator power k eff =0.95, i=33.7mA k eff =0.99 i=6.5mA To meet a constraint of a 10MW proton accelerator we need k eff >0.985
Safety Margins k=0.985
ADSR Shutdown Parks (Cambridge)
Evolution of the criticality value, k eff Coates, Parks (Cambridge)
Evolution of power output Coates, Parks (Cambridge)
The ADSR as an energy amplifier 10MW Accelerator 20 MW electrical 1550MW Thermal Power 600 MW Electrical Power
Why has no ADSR been built?...because accelerators are relatively unreliable
Multiple (FFAG ?) proton injection Multiple injection: - mitigates against proton beam trips and fluctuations - homogenises power distribution across ADSR core
IAEA support I A E A “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…” Alexander Stanculescu Nuclear Power Technology Development Section International Atomic Energy Agency (IAEA) Vienna September 2009
Other ADSR Projects: KURRI Results show prompt and delayed neutrons, the latter from stimulated fission.
Other ADSR Projects: MYRRHA The MYRRHA Project Abderrahim et al., Nuclear Physics News, Vol. 20, No. 1, b€ European project to build an ADSR for transmutation and waste management (2015)
STOP PRESS: 12 January 2012 GUINEVERE World’s first operation of an accelerator driven Pb-cooled fast subcritical reactor (1kW) (CNRS/CEA)
Other ADSR Projects: Aker/Jacobs K eff Accelerator3MW ADSR 600MW
Technology Readiness Levels ADSR Thorium MOX MSR
“The Stone Age didn’t end because we ran out of stone”
Thank You! PASI 13 January