ADSR systems and their contribution to our energy needs Roger Barlow DIUS visit Manchester, 16 th September 2008

Roger BarlowUK ADSR ProgrammeSlide 2 Problem Fossil Fuels Cause global warming Politically dangerous Becoming less abundant

Roger BarlowUK ADSR ProgrammeSlide 3 Solution Renewable energy? Restrict consumption?? Nuclear power ???

Roger BarlowUK ADSR ProgrammeSlide 4 Nuclear power Problems (real or perceived) Dangerous Long-term waste disposal Proliferation of nuclear weapons

Roger BarlowUK ADSR ProgrammeSlide 5 Reactors Conventional Run with k=1 Exactly: k<1 stops k>1 explosion Sub Critical Run with k<1 Use accelerator to supply extra neutrons Hence: Accelerator Driven Subcritical Reactor (ADSR) Each fission absorbs 1 neutron and produces ~2.5 Some neutrons lost, leaving k neutrons to produce k fissions

Roger BarlowUK ADSR ProgrammeSlide 6 ADSRs “Manifestly Safe” Switch off accelerator and reaction stops Energy balance is OK: need 5-10% of power to run accelerator Can use Thorium as fuel Accelerator Spallation Target Core

Roger BarlowUK ADSR ProgrammeSlide 7 Thorium Fertile, not fissile 232 Th +n  233 U Much smaller waste problems (no long- lived actinides) Proliferation resistant –No 235 U equivalent –Fissile 233 U contaminated by ‘too hot to handle’ 232 U Abundant. (Like Lead) And spread around

Roger BarlowUK ADSR ProgrammeSlide 8 Energy Amplifier (Rubbia) Idea has been around for years Nobody’s built one yet! Feeling is that the accelerator is the weak point.

Roger BarlowUK ADSR ProgrammeSlide 9 Waste from ADSR Needs storing – but not forever

Roger BarlowUK ADSR ProgrammeSlide 10 Accelerator requirements Proton Energy ~ 1 GeV For 1GW thermal power: Need fissions/sec (200 MeV/fission) spallation neutrons/sec (k=0.98 gives 50 fissions/neutron) protons/sec (20 spallation neutrons each) Current 5 mA. Power = 5 MW Reliable! Spallation target runs hot. If beam stops, target cools and stresses and cracks: no more than 3 trips per year Compare: PSI cyclotron: 590 MeV, 2mA, 1MW ISIS synchrotron: 800 MeV, 0.2mA, 0.1 MW Many trips per day

Roger BarlowUK ADSR ProgrammeSlide 11 Accelerator types Cyclotron Energy too high for classical cyclotron. On the edge for other types FFAG Looks like the answer Similar to proton therapy machine except higher current and no need for variable energy extraction Very similar to neutrino factory proton driver Linac Can do the job. But VERY expensive Synchrotron Current far too high. Complicated (ramping magnets)

Roger BarlowUK ADSR ProgrammeSlide 12 FFAG ACCELERATORS Fixed Field Alternating Gradient Cyclotron Constant Field Orbit radius increases All cyclic accelerators use magnetic fields to contain the particles As the energy increases: Synchrotron Constant Radius Field is ramped up FFAG Radius increases slightly Particles move from low field to high field region

Roger BarlowUK ADSR ProgrammeSlide 13 FFAG

Roger BarlowUK ADSR ProgrammeSlide 14 EMMA:World’s first nsFFAG Design Prototypes Site Production First Beam 2009

Roger BarlowUK ADSR ProgrammeSlide 15 Formation of the Thorium Energy Amplifier Association: Universities and labs and industry A research consortium aimed at Networking (website, workshops) Sharing knowledge, within and outside UK Collaborative response to funding opportunities Design of a Thorium ADSR, aimed at power generation with transmutation as bonus. FFAG is baseline accelerator Inaugurated here last week A way forward

Roger BarlowUK ADSR ProgrammeSlide 16 ThorEA The Thorium Energy Amplifier Association – hereafter known as ThorEA – is an affiliation of academic institutions, research laboratories, industrial companies, and individual scientists, engineers, technologists and policy specialists who share a common interest in developing thorium as a nuclear fuel in accelerator-driven systems such as the energy amplifier. The overriding purpose of ThorEA is to provide a platform for discussion and a focus for action in thorium fuel and energy amplifier technology and related topics including transmutation. If you’re interested, see From the Articles of Association:

Roger BarlowUK ADSR ProgrammeSlide 17 Summary ADSRs provide a possible form of Nuclear Power that avoids the problems of Critical accidents Long-lived waste Proliferation FFAGs may provide the best accelerator technology We (UK, Particle Physicists, Manchester, Cockcroft Institute) are working hard to make it happen