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

How Accelerators can save the planet

Roger Barlow

Manchester Christmas MeetingJanuary 5th 2010

Wednesday, April 19, 2023 Roger Barlow

We have to stop burning fossil fuels

04/19/23 Roger Barlow

Climate change

Political dependence

They’re running out anyway

Renewables can’t fill the gap

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Even major (country-scale) developments will not be enough

Improved efficiency and insulation can only be part of the answer

Nuclear Power

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Could supply the gap – but public resistance

Safety (Chernobyl )Waste (Yucca Mountain)Proliferation

Safety : the ADSR

Build a sub-critical reactor (k<1)Supply extra neutrons from a spallation target Inherently safe: ‘big red switch’

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OFFYou need to run the accelerator – lower efficiency but only 5-10%

Thorium232Th is fertile232Th (n,γ) 233Th 233 Pa 233U

233U is fissileUse Thorium as a fuel in an ADSR• Long-lived waste essentially eliminated• Very difficult to make bombsHence Thorium fuelled ADSRs – Energy Amplifier

(Rubbia) – Sam’s talk 04/19/23 Roger Barlow

Alternative Plan

Separate Accelerator and Reactor

1.Take conventional fuel rod filled with Thorium (or Thorea: ThO2)

2.Expose to neutrons from spallation source to form 233U.

3.Use rod in conventional PWR

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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

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Green is 235U in 238U. Need ~1.2% Blue is 233U in 232Th. Need ~1.8%

What next for the fuel rod?

In the reactor 233Pa hangs around for ~27 days and absorbs neutrons

Detailed studies of scenarios needed

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For 1.7% 233U in 232Th, dependence of k on percentage of 233Pa.

How to make them?

Simulate Thorium rod in D2O moderator surrounded by Lead

Spallation-spectrum neutrons generated along z axis

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Simulation well suited to Grid use

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Simulation results

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Units are nuclear conversion probability per neutronX 1026

Optimum radius ~ 20 cm

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

04/19/23 Roger Barlow

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

04/19/23 Roger Barlow