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

ADSR systemsUK activity

Roger BarlowFFAG09

Fermilab 24th September 2009

Saving the planet

2Roger Barlow - UK ADSR programme

Global warming due to CO2 emissions

Global warming due to CO2 emissions

Fossil fuels running outFossil fuels running out

Nuclear Power

Nuclear PowerProliferation

Proliferation

WasteWaste

SafetySafety Thorium fuelled ADSRs

Thorium fuelled ADSRs

ADSRs 101

• Uses Thorium (abundant, widespread) • Spallation Neutrons:

232Th233Th233Pa233Ufission• 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 3

FFAGs for ADSRs

Accelerator requirements:~ 1 GeV - rules out cyclotron~ 10 mA - rules out synchrotronCheap - rules out Linac

FFAG fits the picture. Design like medical accelerators but higher energy and much higher current


Various models

(a) ADSR as standard 1-2 GW power station for advanced energy-consuming society (US,UK…)

(b)ADSR as ~500 MW power station suitable for developing country

(c) ADSR run on same site as cluster of conventional reactors to consume waste products

We currently favour (b) as a first step


ThorEA

The Thorium Energy Amplifier Association


Founded 1 year agoWebsite www.thorea.org3-4 workshops/yearCo-ordinated research bidsOutreach and publicityLinks with European and US co-enthusiasts

From:CockcroftJAIImperial, Glasgow,Cambridge, Brunel, HuddersfieldIndustryNon-UK

From:CockcroftJAIImperial, Glasgow,Cambridge, Brunel, HuddersfieldIndustryNon-UK

Members:78 (loose) or 40 (public)Accelerator ScientistsParticle PhysicistsNuclear PhysicistsNuclear EngineersEconomists…

Members:78 (loose) or 40 (public)Accelerator ScientistsParticle PhysicistsNuclear PhysicistsNuclear EngineersEconomists…

What follows are highlights from recent workshops, plus some thoughts of my own

http://www.thorea.org/

Imperial College CONSORT Research Reactor

(Recent talk by Dave Wark)

100 kW, pool-type enriched U/Al fuel,light water moderatedAlready licensed

Dave knows someone who has a spare reactor we might use…


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.


It’s in the middle of the Thames valleyWe may have a problem if the neighbours find out and object…


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)


Thorium Fuel Thorium Fuel RodsRods

Taken from a talk by:Bob Cywinski

School of Applied SciencesUniversity of Huddersfield

AdvantagesThorium supplies plentiful

Robust fuel and waste form

Generates no Pu and fewer higher actinides

233U has superior fissile properties

Thorium as fuelThorium as fuel

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

DisadvantagesNo fission until 233U is produced


Possibility 1Possibility 1: : Plutonium Plutonium seedingseeding

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, PalEnergy Conversion and Management 47 (2006) 2781


Possibility 1Possibility 1: : Plutonium Plutonium seedingseeding

Seedless thorium cluster

Jagannathan, PalEnergy Conversion and Management 47 (2006) 2781

Seeded fuel cluster

ATBR core


Possibility IIPossibility II: : The ‘pure’ The ‘pure’ Thorium-ADSRThorium-ADSR

Load up with pure Thorium

Switch on accelerator and run for ~6 months before getting any power out

Is this economically possible?


Possibility III: Transitional Possibility III: Transitional technologytechnology

232Th to 233U conversion can be better optimised, with mitigation against detrimental neutron absorption by 233Th and 233PaModifications to existing reactors are not necessaryWider global exploitation of nuclear technology is possibleFuel preparation and burn cycles are decoupled

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+targetWhy?


Possibility III: Possibility III: Transitional technologyTransitional technology

The Challenges

Optimisation of proton beam characteristics; spallation target/fuel rod geometries; moderator and reflector geometriesOptimisation 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 irradiationSelection of optimal fuel form; characterisation of material (physical, chemical and engineering properties under extreme conditions)


Possibility III: Transitional Possibility III: Transitional technologytechnology

Miniature spallation target in central bore of fuel element assembly

High power (MW) proton beam


Fuel types ?Fuel types ?

Thorium MetalDuctile, can be shaped. High conductivity .

Thoria -ThO2

High melting point, most stable oxide known.

Thorium Nitrides and CarbidesCarbides have already been successfully used. The use of nitrides is also possible

CermetFine oxide partilcles embedded in a metallic host.

Cermet fuel element

TRISO fuel (ORNL)

pyC SiC C MOX fuel pellet


Materials PropertiesMaterials 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 !


The next step....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 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).

The programme will support two PDRAs for• GEANT4/MCNPX simulations• Materials studies


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…


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


Reliability

“If the beam stops, the reactor stops”- safety mantra

If the accelerator drops out, the reactor stops1) Stress, thermal shock, target breakdown…2) You are now losing money VERY fast (electricity spot market)Suggestion that at most ~5 trips (of >1 second) / year are

permissibleLong way beyond today’s accelerator systems: (Analysis by R

Seviour of data from SINQ and others)


Achieving Reliability

Many sophisticated machines are reliableAchieving 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

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 26

Going forwards

UK Science minister interestedAsked for a report on possibilitiesNow written – 91 pages – to be

delivered soonHave been liaising with civil servants so

have produced something which should be welcome

Makes case for £300M development 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.)

Stage I: LOKI

The Low-key demonstrator35 MeV H- systemHigh current. (1 mA? 10 mA?)• Commercial source• RF Quadrupole• Standard LinacStudy reliability and build it in from the start. Learn from mistakesLooks like the Front End Test Stand?? Copy? Move?Also measurements of cross sections on Thorium (at

CERN?),simulations, materials studies


Stage 2: FREAFFAG 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


Stage 3: Thor

Add a second ring to give 1 GeVnsFFAG, with RCS and Linac as backup optionsUse with a real target and nuclear core for productionNeed private funding ~ £1Bn


Conclusions

Things are moving• More people• More ideas• Serious possibility of some sort of funding


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

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