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How Accelerators can save the planet

In this presentation by Roger Barlow at the Manchester Christmas Meeting on January 5th, 2010, the need to stop burning fossil fuels and the limitations of renewables are discussed. Barlow suggests that nuclear power, specifically using Thorium fuel in an Accelerator Driven Subcritical Reactor (ADSR), could be a solution. The talk includes simulations and scenarios for producing enriched Thorium fuel rods and addresses safety concerns. The alternative plan of separating the accelerator and reactor is also explored.

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How Accelerators can save the planet

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  1. How Accelerators can save the planet Roger Barlow Manchester Christmas Meeting January 5th 2010 Roger Barlow

  2. We have to stop burning fossil fuels Climate change Political dependence They’re running out anyway Roger Barlow

  3. Renewables can’t fill the gap Even major (country-scale) developments will not be enough Improved efficiency and insulation can only be part of the answer Roger Barlow

  4. Nuclear Power Could supply the gap – but public resistance Safety (Chernobyl ) Waste (Yucca Mountain) Proliferation Roger Barlow

  5. Safety : the ADSR Build a sub-critical reactor (k<1) Supply extra neutrons from a spallation target Inherently safe: ‘big red switch’ You need to run the accelerator – lower efficiency but only 5-10% OFF Roger Barlow

  6. Thorium 232Th is fertile 232Th (n,γ)  233Th  233 Pa  233U 233U is fissile Use Thorium as a fuel in an ADSR • Long-lived waste essentially eliminated • Very difficult to make bombs Hence Thorium fuelled ADSRs – Energy Amplifier (Rubbia) – Sam’s talk Roger Barlow

  7. Alternative Plan Separate Accelerator and Reactor • Take conventional fuel rod filled with Thorium (or Thorea: ThO2) • Expose to neutrons from spallation source to form 233U. • Use rod in conventional PWR Roger Barlow

  8. How enriched? Simulation using MCNP program (standard). Typical PWR geometry. 1cm diameter rods in 2cm rectangular grid, water moderator, lead reflector. Plot criticality versus concentration Green is 235U in 238U. Need ~1.2% Blue is 233U in 232Th. Need ~1.8% Roger Barlow

  9. What next for the fuel rod? In the reactor 233Pa hangs around for ~27 days and absorbs neutrons Detailed studies of scenarios needed For 1.7% 233U in 232Th, dependence of k on percentage of 233Pa. Roger Barlow

  10. How to make them? Simulate Thorium rod in D2O moderator surrounded by Lead Spallation-spectrum neutrons generated along z axis Roger Barlow

  11. Simulation well suited to Grid use Roger Barlow

  12. Simulation results Optimum radius ~ 20 cm Units are nuclear conversion probability per neutron X 1026 Roger Barlow

  13. Conclusion • Conversion Probability ~ 10-26 per neutron • For 3 mA proton beam, 25 neutrons per spallation: 4 x 106 seconds=1000 hours • Too expensive: need further optimisation and neutron multiplication Roger Barlow

  14. Other stuff 2009 2010 BaBar LHCb EMMA Grid will work! ThorEA Drift chambers for homland security Merlin+Wakefields Negative weights • BaBar • LHCb • EMMA • ThorEA • Rolling Grant Roger Barlow

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