1. How Accelerators can save the planet Roger Barlow Manchester Christmas Meeting January 5 th 2010 Monday, July 13, 2015Roger Barlow

2. We have to stop burning fossil fuels 7/13/2015Roger Barlow Climate change Political dependence They’re running out anyway

3. Renewables can’t fill the gap 7/13/2015Roger Barlow Even major (country- scale) developments will not be enough Improved efficiency and insulation can only be part of the answer

4. Nuclear Power 7/13/2015Roger Barlow Could supply the gap – but public resistance Safety (Chernobyl ) Waste (Yucca Mountain) Proliferation

5. Safety : the ADSR Build a sub-critical reactor ( k<1 ) Supply extra neutrons from a spallation target Inherently safe: ‘big red switch’ 7/13/2015Roger Barlow OFF You need to run the accelerator – lower efficiency but only 5- 10%

6. Thorium 232 Th is fertile 232 Th (n,γ)  233 Th  233 Pa  233 U 233 U 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 7/13/2015Roger Barlow

7. Alternative Plan Separate Accelerator and Reactor 1.Take conventional fuel rod filled with Thorium (or Thorea: ThO 2 ) 2.Expose to neutrons from spallation source to form 233 U. 3.Use rod in conventional PWR 7/13/2015Roger 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 7/13/2015Roger Barlow Green is 235 U in 238 U. Need ~1.2% Blue is 233 U in 232 Th. Need ~1.8%

9. What next for the fuel rod? In the reactor 233 Pa hangs around for ~27 days and absorbs neutrons Detailed studies of scenarios needed 7/13/2015Roger Barlow For 1.7% 233 U in 232 Th, dependence of k on percentage of 233 Pa.

10. How to make them? Simulate Thorium rod in D 2 O moderator surrounded by Lead Spallation- spectrum neutrons generated along z axis 7/13/2015Roger Barlow

11. Simulation well suited to Grid use 7/13/2015Roger Barlow

12. Simulation results 7/13/2015Roger Barlow Units are nuclear conversion probability per neutron X 10 26 Optimum radius ~ 20 cm

13. Conclusion Conversion Probability ~ 10 -26 per neutron For 3 mA proton beam, 25 neutrons per spallation: 4 x 10 6 seconds=1000 hours Too expensive: need further optimisation and neutron multiplication 7/13/2015Roger Barlow

14. Other stuff 2009 BaBar LHCb EMMA ThorEA Rolling Grant 2010 BaBar LHCb EMMA Grid will work! ThorEA Drift chambers for homland security Merlin+Wakefields Negative weights 7/13/2015Roger Barlow