The Materials Test Station:An Accelerator Driven Neutron Source

for Fusion Materials Testing

Eric Pitcher

Presented at:

Sixth US-PRC Magnetic Fusion Collaboration Workshop

July 10-12, 2012

LA-UR-12-22739

Slide 2Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012

The need for a fusion relevant intense neutron source is well established

• 2007 FESAC (Greenwald) Report – Identified a neutron irradiation facility as one of nine initiatives – Recommended assessing the potential for alternative facilities to reduce or

possibly eliminate the need for the US to participate as a full partner in the International Fusion Materials Irradiation Facility (IFMIF)

• 2009 FES Research Needs Workshop (ReNeW)– Advocated a fusion-relevant neutron source to be an essential mission

requirement

• 2012 FESAC Opportunities for Fusion Materials Science and Technology Research Now and During the ITER Era

– “The lack of an intense fusion relevant neutron source for conducting accelerated experiments is the largest obstacle to achieving a rigorous scientific understanding and developing effective strategies for mitigating neutron-induced material degradation.”

The LANL Materials Test Station is a moderate cost option that can largely satisfy this mission need.The LANL Materials Test Station is a moderate cost option that can largely satisfy this mission need.

Slide 3Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012

Materials Test Station Mission: Irradiate nuclear fuels and materials in a fast neutron spectrum

• The DOE Office of Nuclear Energy (DOE-NE) has funded the conceptual design of the Materials Test Station (MTS) as a fast spectrum nuclear fuels and materials test bed

• Once completed, the MTS will be the only fast neutron spectrum irradiation capability outside of Russia and Asia

• The MTS can provide the US with a fast spectrum test capability in 4 years for about $85M

• The MTS neutron irradiation environment is also suitable for fusion materials testing

Slide 4Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012

MTS will be built at the Los Alamos Neutron Science Center (LANSCE), a multidisciplinary National User Facility

• Lujan Neutron Scattering Center– Materials science– Biology– Nuclear cross sections

• Weapons Neutron Research Facility– Nuclear cross sections– semiconductor testing

• Proton Radiography– dynamic imaging

• Ultra-Cold Neutron Source– nuclear physics

• Isotope Production Facility– medical & research isotopes

• Materials Test Station(under design)

– fuels and materials testing

Slide 5Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012

The MTS will be driven by a 1-MW proton beam delivered by the LANSCE accelerator

• MTS will be built in an existing experimental hall

• Use of existing materials and infrastructure greatly reduces capital costs compared to a green field

Slide 6Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012

MTS neutron flux and energy spectrum is similar to a fast reactor, with an added high-energy tail

MTS flux level will be half of the world’s most intense research fast reactors.

Facility Peak Fast Flux (1015 n/cm2/s)

MTS (USA) 1.3

BOR-60 (Russia) 2.8

CEFR (China) 2.5

NEUTRON ENERGY SPECTRUM SPATIAL DISTRIBUTION OF THE FAST NEUTRON FLUX

Slide 7Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012

Figures of merit for fusion materials testing

• Irradiation temperature– 300˚C to 1000˚C range, controllable to ±10˚C

• He/dpa ratio– “Fusion relevant” range is 10 – 15 appm He/dpa

• Damage rate– Desirable to reach a total dose exceeding 100 dpa in a few years

• Irradiation volume– Sufficient to simultaneously irradiate hundreds of test specimens

• Nuclear recoil spectrum similar to fusion reactor 1st wall

• Similar evolution in elemental composition with dose

With the exception of damage rate, the MTS substantially satisfies these figures of merit.With the exception of damage rate, the MTS substantially satisfies these figures of merit.

Slide 8Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012

MTS produces a broad range of He/dpa ratios

• Peak dpa rate is 32 dpa/fpy or 17 dpa/year (50% LANSCE availability)

• There is an irradiation volume of about 100 cm3 where samples will receive 7 dpa/year or more with fusion-relevant He/dpa ratios

“fusion relevant”He/dpa

ratio from 10 to 15 appm/dpa

fuels irradiation region

materials irradiation region

Slide 9Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012

Different facilities exhibit distinct features in their neutron and nuclear recoil energy spectra

10-6

10-4

10-2

100

102

104

10-5 10-4 10-3 10-2 10-1 100 101

dσ / ( / )dT b MeV

, ( )nuclear recoil energy T MeV

1 fusion reactor st wall

MTS fast reactor

IFMIF

0

1E+14

2E+14

3E+14

4E+14

5E+14

6E+14

7E+14

10-3 10-2 10-1 100 101 102 103

neutron lethargy flux (n.cm

–2.s

–1)

neutron energy (MeV)

fusion reactor 1st wall

MTS

fast reactor

IFMIF

Low-energy portion of the neutron and nuclear recoil spectra are similar for fusion reactor, fast reactor, and MTS.

(DEMO)

Slide 10Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012

The damage production function W(T) of a fusion reactor 1st wall and MTS match in the critical region below 50 keV

0.0

0.2

0.4

0.6

0.8

1.0

10-3 10-2 10-1 100 101

W(T)

nuclear recoil energy, T (MeV)

fusion reactor 1st wall

MTSfast reactor

IFMIF

Isolated defectswith higher rate of survivability

Sub-cascade production

Slide 11Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012

Major elemental composition evolution in MTS is similar to that for a fusion reactor first wall

reflector

bac

ksto

p

materials samples

spallation target

fuel samples

spallation target

materials samples

reflector

proton beam

proton beam

mask

materials region tally volumes

EUROFER97 irradiated to 200 dpa

Slide 12Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012

Summary

• The irradiation environment in MTS is appropriate for fusion materials testing of steel alloys with respect to:

– irradiation temperature– He/dpa ratio– nuclear recoil spectrum– change in elemental composition with dose

• Peak damage rate for iron alloys is 17 dpa/calendar year

• Irradiation volume is sufficient for the simultaneous irradiation of hundreds of miniature test specimens

• Conceptual design completed last year, awaiting DOE approval

• MTS provides the US a cost effective alternative to joining the ITER Broader Approach