Download Pitcher - MTS

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
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.
Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012
Slide 2
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
Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012
Slide 3
MTS will be built at the Los Alamos Neutron Science
Center (LANSCE), a multidisciplinary National User Facility
•
Lujan Neutron Scattering Center
–
–
–
•
Weapons Neutron Research Facility
–
–
•
nuclear physics
Isotope Production Facility
–
•
dynamic imaging
Ultra-Cold Neutron Source
–
•
Nuclear cross sections
semiconductor testing
Proton Radiography
–
•
Materials science
Biology
Nuclear cross sections
medical & research isotopes
Materials Test Station
(under design)
–
fuels and materials testing
Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012
Slide 4
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
Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012
Slide 5
MTS neutron flux and energy spectrum is similar
to a fast reactor, with an added high-energy tail
NEUTRON ENERGY SPECTRUM
SPATIAL DISTRIBUTION OF THE FAST NEUTRON FLUX
Peak Fast Flux (1015 n/cm2/s)
Facility
MTS (USA)
1.3
BOR-60 (Russia)
2.8
CEFR (China)
2.5
MTS flux level will be
half of the world’s
most intense research
fast reactors.
Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012
Slide 6
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.
Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012
Slide 7
MTS produces a broad range of He/dpa ratios
fuels irradiation region
materials
irradiation
region
“fusion
relevant”
He/dpa
ratio from
10 to 15
appm/dpa
•
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
Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012
Slide 8
Different facilities exhibit distinct features in
their neutron and nuclear recoil energy spectra
104
7E+14
fusion reactor 1st wall
(DEMO)
6E+14
IFMIF
5E+14
fast reactor
d / dT (b/MeV)
neutron lethargy flux (n.cm
–2
.s–1)
102
4E+14
3E+14
100
2E+14
fusion reactor 1st wall
IFMIF
1E+14
0
10-3
MTS
fast reactor
10-2
10-4
MTS
-2
10
-1
10
0
10
1
10
neutron energy (MeV)
2
10
3
10
10-6
10-5
10-4
10-3
10-2
10-1
100
nuclear recoil energy, T (MeV)
Low-energy portion of the neutron and nuclear recoil spectra
are similar for fusion reactor, fast reactor, and MTS.
Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012
Slide 9
101
The damage production function W(T) of a fusion reactor
1st wall and MTS match in the critical region below 50 keV
1.0
0.8
Isolated defects
with higher rate
of survivability
MTS
fast reactor
W(T)
0.6
fusion reactor 1st wall
0.4
IFMIF
0.2
Sub-cascade production
0.0
10-3
10-2
10-1
nuclear recoil energy, T (MeV)
100
Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012
101
Slide 10
Major elemental composition evolution in MTS
is similar to that for a fusion reactor first wall
reflector
proton beam
mask
proton beam
spallation target
fuel samples
backstop
materials samples
spallation target
materials samples
materials region tally volumes
reflector
EUROFER97 irradiated to 200 dpa
Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012
Slide 11
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
Sixth US-PRC Magnetic Fusion Collaboration Workshop, San Diego, July 10-12, 2012
Slide 12