Presentation on theme: "Accelerator Driven Subcritical Reactors with thorium fuel"— Presentation transcript:
1 Accelerator Driven Subcritical Reactors with thorium fuel Doctoral Training CourseUniversity of Huddersfield11 April 2013Accelerator Driven Subcritical Reactorswith thorium fuelBob CywinskiSchool of Applied SciencesInternational Institute for Accelerator Applications
3 The Carbon Problem Energy source Grams of CO2 per KWh of electricity Nuclear4Wind8Hydro electricEnergy crops17Geothermal79Solar133Gas430Diesel772Oil828Coal955source:Government Energy Technology Support Unit (confirmed by OECD)
4 Current nuclear supply Country No. Reactors GW capacity % Total ElectricityFranceSwedenSouth KoreaJapanGermanyUnited StatesRussiaUnited KingdomCanadaIndia21 OthersTotals:But this represents only 5% of global energy consumptionTo increase this by x5 would reduce carbon emissions by 25%
8 Uranium requirements Scenario 1 No new nuclear build Scenario 2 Maintain current nuclear capability(implies major increase in plant construction)Scenario 3Nuclear renaissance: increase in nuclear power generation to 1500 GW capacity by 2050
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 costsperceived adverse safety, environmental, and health effectspotential security risks stemming from proliferationunresolved challenges in long-term management of nuclear wastes.
11 Annual global use of energy resources 5x109tonnes of coal5x103 tonnes of thoriumAn alternative fuel?27x109barrels of oil2.5x1012 m3 natural gas65x103tonnes of uranium
13 Breeding fuel from thorium AdvantagesDoes not need processingGenerates virtually no plutonium and less higher actinides233U has superior fissile propertiesn232Th233Th233Pa233Ubg27 days22 minsDisadvantagesRequires introduction of fissile seed (235U or Pu)The decay of parasitic 232U results in high gamma activity from 208Tl.
14 Advantages of thorium: waste 1001,00010,000100,0001,000,00010,000,00010100,000,0001,000,000,000100,000
16 Breeding fuel from thorium AdvantagesDoes not need processingGenerates virtually no plutonium and less higher actinides233U has superior fissile propertiesn232Th233Th233Pa233Ubg27 days22 minsDisadvantagesRequires introduction of fissile seed (235U or Pu)The decay of parasitic 232U results in high gamma activity from 208Tl.
22 Accelerator power The (thermal) power output of an ADSR is given by with N = number of spallation neutrons/secEf = 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 requireGiven 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
26 A Thorium Fuelled ADSR1. Initial loss due to build-up of absorbing Pa233 and decrease of U233 enrichment by neutron absorption and fission122. Increase due to increasing U233 enrichment from subsequent β-decay of Pa23333. Long term decrease due to build up of neutron absorbing fission productsH.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)
35 Applications of Accelerator Driven Systems Applications of Accelerator Driven Systems TechnologyTransmuting 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 heatProducing fissile materials for use in conventional critical or novel sub-critical reactors by irradiating fertile precursors.
41 Proton drivers? Cyclotron Synchrotron Linac High Current (<A) Low Energy (600MeV)Continuous beamSynchrotronLow Current (<mA) High Energy (TeV)Pulsed BeamLinacHigh Current, High EnergyPulsed or continuous beamLarge 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
47 Multiple FFAG proton injection Multiple injection:- mitigates against proton beam trips and fluctuations- homogenises power distribution across ADSR corePatent 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 AAlexander StanculescuNuclear Power Technology Development SectionInternational Atomic Energy Agency (IAEA)Vienna
50 ConclusionsThorium 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 generation780kg of thorium = 200 tonnes of uranium (as currently used)No plutonium is used and very little is producedAfter 70 years the radiotoxicity is 20,000 times less than an equivalent conventional nuclear power stationThorium systems provide means of burning existing legacy wasteWaste can be mixed with thorium and burnt as fuel, reducing radiotoxity by orders of magnitude and turning a liability into an assetBut......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