ADSR systems UK activity Roger Barlow FFAG09 Fermilab 24th September 2009

Saving the planet Thorium fuelled ADSRs Nuclear Power Global warming due to CO2 emissions Safety Waste Fossil fuels running out Proliferation Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme ADSRs 101 Uses Thorium (abundant, widespread) Spallation Neutrons: 232Th233Th233Pa233Ufission Accelerator consumes 5-10% of power Does not generate Actinides Consumes Actinides and nastiest fission products (I, Tc) from conventional reactors Very proliferation resistant Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme FFAGs for ADSRs Accelerator requirements: ~ 1 GeV - rules out cyclotron ~ 10 mA - rules out synchrotron Cheap - rules out Linac FFAG fits the picture. Design like medical accelerators but higher energy and much higher current Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme Various models (a) ADSR as standard 1-2 GW power station for advanced energy-consuming society (US,UK…) ADSR as ~500 MW power station suitable for developing country ADSR run on same site as cluster of conventional reactors to consume waste products We currently favour (b) as a first step Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme ThorEA The Thorium Energy Amplifier Association Founded 1 year ago Website www.thorea.org 3-4 workshops/year Co-ordinated research bids Outreach and publicity Links with European and US co-enthusiasts From: Cockcroft JAI Imperial, Glasgow, Cambridge, Brunel, Huddersfield Industry Non-UK Members: 78 (loose) or 40 (public) Accelerator Scientists Particle Physicists Nuclear Physicists Nuclear Engineers Economists … What follows are highlights from recent workshops, plus some thoughts of my own Roger Barlow - UK ADSR programme

Imperial College CONSORT Research Reactor (Recent talk by Dave Wark) Dave knows someone who has a spare reactor we might use… 100 kW, pool-type enriched U/Al fuel, light water moderated Already licensed Roger Barlow - UK ADSR programme

Basic Idea – Modify CONSORT into ADSR. Build/buy small proton accelerator (few - 10 kW total power) for reactor facility. Insert small spallation target either in place of one fuel assembly or above the core. Leave control rods in place to scram reactor and make it sub-critical. Use sample insertion locations/devices (or add more) to place other fuel in/near core. Probably increase instrumentation of the reactor to measure neutron profiles, etc. Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme It’s in the middle of the Thames valley We may have a problem if the neighbours find out and object… Roger Barlow - UK ADSR programme

CONSORT/ADSR – Experiments to be done. Breeding 233U fuel from 232Th in an ADSR. Burning Pu in an ADSR. Burning MA in an ADSR. Burning LLFP in an ADSR. Effects of all of this on the reactivity, neutron profile, and other parameters of the reactor – reactivity feedback in an ADSR has not been measured up to now. Measure all of this as a function of k by changing control rod positions. Use all this to benchmark simulations. Thought of before but not actually done (TRADE/TRIGA) Roger Barlow - UK ADSR programme

Thorium Fuel Rods Taken from a talk by: Bob Cywinski School of Applied Sciences University of Huddersfield

Roger Barlow - UK ADSR programme Thorium as fuel Disadvantages No fission until 233U is produced Advantages Thorium supplies plentiful Robust fuel and waste form Generates no Pu and fewer higher actinides 233U has superior fissile properties n 232Th 233Th 233Pa 233U b g 27 days 22 mins It is generally considered that the neutrons necessary to produce 233U from 232Th must be introduced by seeding the Th fuel with 235U or Pu Roger Barlow - UK ADSR programme

Possibility 1: Plutonium seeding The Indian approach: thermal Thorium Breeder Reactor (ATBR) Calculations suggest PuO2 seeded thoria fuel gives excellent core characteristics, such as: two years cycle length high seed output to input ratio intrinsically safe reactivity coefficients Problems with waste and security Jagannathan, Pal Energy Conversion and Management 47 (2006) 2781 Roger Barlow - UK ADSR programme

Possibility 1: Plutonium seeding Seedless thorium cluster ATBR core Jagannathan, Pal Energy Conversion and Management 47 (2006) 2781 Seeded fuel cluster Roger Barlow - UK ADSR programme

Possibility II: The ‘pure’ Thorium-ADSR Load up with pure Thorium Switch on accelerator and run for ~6 months before getting any power out Is this economically possible? Roger Barlow - UK ADSR programme

Possibility III: Transitional technology Production of ready-engineered Th fuel rods for direct deployment in conventional nuclear reactors, with fertile to fissile conversion achieved through dedicated spallation charging from an accelerator+target Why? 232Th to 233U conversion can be better optimised, with mitigation against detrimental neutron absorption by 233Th and 233Pa Modifications to existing reactors are not necessary Wider global exploitation of nuclear technology is possible Fuel preparation and burn cycles are decoupled Roger Barlow - UK ADSR programme

Possibility III: Transitional technology The Challenges Optimisation of proton beam characteristics; spallation target/fuel rod geometries; moderator and reflector geometries Optimisation of irradiation cycles; consideration of the neutron energy spectrum and related absorption characteristics of 232Th, 233Th, 233Pa Characterisation of the 233U fission during and after irradiation Selection of optimal fuel form; characterisation of material (physical, chemical and engineering properties under extreme conditions) Roger Barlow - UK ADSR programme

Possibility III: Transitional technology Miniature spallation target in central bore of fuel element assembly High power (MW) proton beam Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme Fuel types ? Thorium Metal Ductile, can be shaped. High conductivity . Thoria -ThO2 High melting point, most stable oxide known. pyC SiC C MOX fuel pellet Thorium Nitrides and Carbides Carbides have already been successfully used. The use of nitrides is also possible TRISO fuel (ORNL) Cermet Fine oxide partilcles embedded in a metallic host. Cermet fuel element Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme Materials Properties LWR fuel rod element Crack formation Substantial grain growth in centre (ie in hotter region) Small gap at pellet-cladding interface Effects of irradiation and thermal cycling on thorium fuel assemblies must be studied and characterised These fuel rods may be in the reactor for several years ! Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme The next step.... STFC are funding a two year scoping study of the thorium fuel rod concept through PNPAS scheme (Barlow and Cywinski) The programme will support two PDRAs for GEANT4/MCNPX simulations Materials studies The programme may progress as far as experimental tests , eg at TRIUMF, where FERFICON experiments were carried out in the 70s (these would allow irradiation by protons at up to 20nA at 450MeV). Roger Barlow - UK ADSR programme

Do we need fuel reprocessing? Thorium fuel rods: once-through or recycle? (Current strategy for Uranium is once-through, as extracting Plutonium leads to stockpiles of the stuff.) Thorium fuel rods stay in the reactor for years rather than months – poisonous fission products build up much more slowly Do we then have to process them, or just leave them in a depository somewhere? The latter looked attractive, but… Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme Waste “Thorium Reactors produce no long-term waste” Up to a point. Ignores the 233U which has a half life of 160,000 years. “Thorium is proliferation-resistant as the fissile 233U is inescapably contaminated by 232U which renders it too hot to handle” For a while. 232U has a half life of 72 years. So we need to recycle the 233U. Messy chemistry Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme Reliability “If the beam stops, the reactor stops” - safety mantra If the accelerator drops out, the reactor stops Stress, thermal shock, target breakdown… You are now losing money VERY fast (electricity spot market) Suggestion that at most ~5 trips (of >1 second) / year are permissible Long way beyond today’s accelerator systems: (Analysis by R Seviour of data from SINQ and others) Roger Barlow - UK ADSR programme

Achieving Reliability Many sophisticated machines are reliable Achieving reliability is a science (FMEA*): Parallelism (even >1 accelerator) Under-rating Graceful failure Scheduled preventive maintenance Sticking to the original spec Cost money Need full knowledge of whole system Build in from start of design *Failure Mode and Effects Analysis Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme Considerations DC Magnets are fairly reliable provided they are maintained (e.g. renew coolant pipes) Ion sources are unreliable but can be duplicated RF cavities frequently break down. Need not be catastrophic for Linac and FFAG (consider ILC). But rules out harmonic number jump scheme But first: Define break in provision of service ( 1 sec, 1 min, ....) - How many breaks can we live with ( 1,5,... per year) Allowable capital cost (From R Seviour: ThorEA workshop, Glasgow, 2009) Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme Going forwards UK Science minister interested Asked for a report on possibilities Now written – 91 pages – to be delivered soon Have been liaising with civil servants so have produced something which should be welcome Makes case for £300M development programme Roger Barlow - UK ADSR programme

Straw man scheme: AESIR Accelerator Energy System with Inuilt Reliability Design and build a Thorium ADSR, hopefully with an nsFFAG providing the accelerator (Other accelerator solutions are acceptable.) Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme Stage I: LOKI The Low-key demonstrator 35 MeV H- system High current. (1 mA? 10 mA?) Commercial source RF Quadrupole Standard Linac Study reliability and build it in from the start. Learn from mistakes Looks like the Front End Test Stand?? Copy? Move? Also measurements of cross sections on Thorium (at CERN?),simulations, materials studies Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme Stage 2: FREA FFAG Research for the Energy Amplifier Add a 2nd stage ring: boost energy to 390 MeV Why 390? Pion production. But ~300 would still be interesting Produces spallation. Not as much as 1 GeV, but enough to be interesting. Continue to emphasise reliability. Increase Current to 10 mA Use a proton nsFFAG – with a cyclotron as fallback. Or Linac Gives useful proton machine (c.f. TRIUMF, PSI). 99mTc production? Links to proton therapy Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme Stage 3: Thor Add a second ring to give 1 GeV nsFFAG, with RCS and Linac as backup options Use with a real target and nuclear core for production Need private funding ~ £1Bn Roger Barlow - UK ADSR programme

Roger Barlow - UK ADSR programme Conclusions Things are moving More people More ideas Serious possibility of some sort of funding Roger Barlow - UK ADSR programme