Concept and Development Work
for the LANL Materials Test Station

              Eric Pitcher
     Los Alamos National Labo...
The Materials Test Station will be a fast spectrum
fuel and materials irradiation testing facility

 • MTS will be driven ...
The MTS target consists of two spallation target
 sections separated by a “flux trap”
                                    ...
Spatial distribution of the proton flux shows low
proton contamination in the irradiation regions

                       ...
The neutron flux in the fuels irradiation region
exceeds 1015 n/cm2/s and has low spatial gradient




         ESS Bilbao...
A sharp beam edge is key to maximizing the
neutron flux in the irradiation regions
• Two technologies facilitate




     ...
Beam transport system produces a horizontal
focus at the target front face

                                              ...
The MTS target is tungsten cooled by liquid
lead-bismuth eutectic (LBE)
• Neutron production density is
  proportional to ...
Target is fabricated through multiple diffusion
bonding steps
• Fuel module housing and target                     Channel...
A tungsten target with heat flux up to 600
W/cm2 can be cooled by water
• For single-phase D2O:

   – 10 m/s bulk velocity...
An experiment was conducted to validate the
   target thermal-hydraulic performance
            Copper Test Section
      ...
Thermal-hydraulic experiments using water
coolant confirm heat-transfer correlations




        ESS Bilbao Initiative Wor...
Experimental results match test data using
Handbook heat transfer coefficient




       Thermocouple
         Locations  ...
Heavy water can cool the spallation target, but LBE
provides the required higher temperature operation

• LBE coolant offe...
LBE temperature is controlled with variable-area,
   double-wall, shell and tube heat exchangers

            LBE


      ...
LBE-to-water heat exchanger is sufficiently
novel as to merit a confirmatory experiment
          109 cm




             ...
Target lifetime will be limited by damage to the
target front face
• Experience base:
               ISIS (SS316 front fac...
The MTS would benefit from increased beam
power on target
• At 4 MW, the peak fast neutron flux in MTS would be equal
  th...
Towards higher beam power:
Which is better—more energy or more current?
                                         • Above ~...
Towards higher beam power:
Which is better—more energy or more current?
• If target lifetime and
  coolant volume
  fracti...
Peak neutron flux goes as Pbeam0.8


      ~ Ebeam0.8ibeam0.8
 pk



        Ebeam = 0.8 GeV                              ...
Summary

• Beam rastering and target imaging are key to the
  successful realization of high neutron flux in MTS
• A water...
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Concept and Development Work for the LANL Materials Test Station

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Concept and Development Work
for the LANL Materials Test Station. Eric Pitcher
Los Alamos National Laboratory
Presented to: ESS Bilbao Initiative Workshop

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Concept and Development Work for the LANL Materials Test Station

  1. 1. Concept and Development Work for the LANL Materials Test Station Eric Pitcher Los Alamos National Laboratory Presented to: ESS Bilbao Initiative Workshop 17 March 2009
  2. 2. The Materials Test Station will be a fast spectrum fuel and materials irradiation testing facility • MTS will be driven by a 1-MW proton beam delivered by the LANSCE accelerator • Spallation reactions produce 1017 n/s, equal to a 3-MW reactor fuel module target module beam mask backstop ESS Bilbao Initiative Workshop 16-18 March 2009 2
  3. 3. The MTS target consists of two spallation target sections separated by a “flux trap” materials sample cans spallation target test fuel rodlets • Neutrons generated through spallation reactions in tungsten • 2-cm-wide flux trap that fits 40 rodlets Beam pulse structure: 750 µs 7.6 ms 16.7 mA Delivered to: left right left right target target target target ESS Bilbao Initiative Workshop 16-18 March 2009 3
  4. 4. Spatial distribution of the proton flux shows low proton contamination in the irradiation regions fuels irradiation region materials irradiation regions ESS Bilbao Initiative Workshop 16-18 March 2009 4
  5. 5. The neutron flux in the fuels irradiation region exceeds 1015 n/cm2/s and has low spatial gradient ESS Bilbao Initiative Workshop 16-18 March 2009 5
  6. 6. A sharp beam edge is key to maximizing the neutron flux in the irradiation regions • Two technologies facilitate materials irradiation region a sharp beam edge: fuels irradiation region – Beam rastering – Design and testing by Shafer et al. for APT at LANL 15 mm – Imaging the beam spot on target – VIMOS by Thomsen et al. for SINQ at PSI – Imaging methods for SNS under study by Shea et al. at ORNL • MTS will rely on rastering plus beam spot imaging to produce a 15-mm-wide beam spot only 4 mm from the irradiation regions ESS Bilbao Initiative Workshop 16-18 March 2009 6
  7. 7. Beam transport system produces a horizontal focus at the target front face 25 mm wide target face 15 mm nominal footprint width Beamletis 3 mm horizontal x 8 mm vertical (FWHM) Vertical slew covers 60 mm nominal footprint height in 750 µs macro-pulse ESS Bilbao Initiative Workshop 16-18 March 2009 7
  8. 8. The MTS target is tungsten cooled by liquid lead-bismuth eutectic (LBE) • Neutron production density is proportional to target mass density – W density = 19.3 g/cc LBE density = 10.5 g/cc tungsten diluted by 40 vol% coolant outperforms LBE • MTS maximum coolant volume fraction is 19% • Neutron production density LBE supply plenum with tungsten is 60% greater than for LBE alone ESS Bilbao Initiative Workshop 16-18 March 2009 8
  9. 9. Target is fabricated through multiple diffusion bonding steps • Fuel module housing and target Channels for fuel pins sidewalls are T91 • Ta front face and W target plates have 0.1- to 0.2-mm T91 clad diffusion bonded on each face • Target plates are diffusion bonded to the fuel module and target sidewalls Ta front face • No welds are used near the proton beam ESS Bilbao Initiative Workshop 16-18 March 2009 9
  10. 10. A tungsten target with heat flux up to 600 W/cm2 can be cooled by water • For single-phase D2O: – 10 m/s bulk velocity in 1mm gap (series pressure drop 5.5 bar) – Heat transfer coefficient 5.4 W/cm2-K – 70 µA/cm2 beam current density on 4.4-mm-thick W plate produces 600 W/cm2 at each cooled face – At 600 W/cm2, Tsurf 110 ºC above bulk coolant temp – Tcoolant,inlet = 40 ºC,Tcoolant,exit = 105 ºC,Tsurface.exit = 215 ºC – Static pressure at inlet is 26 bar to suppress boiling ESS Bilbao Initiative Workshop 16-18 March 2009 10
  11. 11. An experiment was conducted to validate the target thermal-hydraulic performance Copper Test Section Surface Heat Flux Peak ~600 W/cm2 1 mm x 18 mm Channel Flow Channel Flow Rate 10 m/s Test Goals: • Determine single-phase HTC Cartridge • Identify plate surface temperature Heaters @ 600 W/cm2 • Measure subcooled flow boiling pressure drop Cartridge heaters in tapered copper • Investigate effect of plate surface block will simulate beam spot heat roughness flux ESS Bilbao Initiative Workshop 16-18 March 2009 11
  12. 12. Thermal-hydraulic experiments using water coolant confirm heat-transfer correlations ESS Bilbao Initiative Workshop 16-18 March 2009 12
  13. 13. Experimental results match test data using Handbook heat transfer coefficient Thermocouple Locations Water flow Temperature (°C) ESS Bilbao Initiative Workshop 16-18 March 2009 13
  14. 14. Heavy water can cool the spallation target, but LBE provides the required higher temperature operation • LBE coolant offers a number of advantages over water: Easy to control and monitor fuel clad temperature at 550 ºC – Can accommodate fuel pin bowing and swelling – Very high heat transfer coefficient parallel flow okay – Liquid to very high temperature low pressure operation – No risk of tungsten-steam reactions releasing radioactive inventory – • Disadvantages of LBE coolant: – Potentially corrosive at elevated operating temperature (>550 ºC) – Not a liquid at room temperature (piping must have race heaters) – Loop components (pumps, valves, etc.) are more expensive than for water loops – Polonium release at elevated temperature ESS Bilbao Initiative Workshop 16-18 March 2009 14
  15. 15. LBE temperature is controlled with variable-area, double-wall, shell and tube heat exchangers LBE 100 Tubes 0.875” OD LBE level in intermediate annulus sets heat transfer water surface area Flowing LBE (primary coolant) reservoir gas/vac Static LBE Inlet water manifold Outlet water manifold ESS Bilbao Initiative Workshop 16-18 March 2009 15
  16. 16. LBE-to-water heat exchanger is sufficiently novel as to merit a confirmatory experiment 109 cm Flowing LBE (primary coolant) Static LBE Inlet water manifold Outlet water manifold ESS Bilbao Initiative Workshop 16-18 March 2009 16
  17. 17. Target lifetime will be limited by damage to the target front face • Experience base: ISIS (SS316 front face): 3.2×1021 p/cm2 = 10 dpa SINQ (Pb-filled SS316 tubes): 6.8×1021 p/cm2 = 22 dpa MEGAPIE (T91 LBE container): 1.9×1021 p/cm2 = 6.8 dpa LANSCE A6 degrader (Inconel 718): 12 dpa • MTS design, annual dose (70µA/cm2 for 4400 hours): (T91-clad tantalum front face): 6.9×1021 p/cm2 = 23 dpa • Fast reactor irradiations at the tungsten operating temperature (700 ºC) yielded 1.5% swelling at 9.5 dpa ESS Bilbao Initiative Workshop 16-18 March 2009 17
  18. 18. The MTS would benefit from increased beam power on target • At 4 MW, the peak fast neutron flux in MTS would be equal that of JOYO • MTS could meet (at 1.8 MW) or exceed (at 3.6 MW) IFMIF peak damage rates for fusion materials studies 1 MW 1.8 MW 3.6 MW ESS Bilbao Initiative Workshop 16-18 March 2009 18
  19. 19. Towards higher beam power: Which is better—more energy or more current? • Above ~800 MeV, target peak power density increases with beam energy • Addressed by: – Higher coolant volume fraction for solid targets – Higher flow rate for liquid metal targets – Bigger beam spot ESS Bilbao Initiative Workshop 16-18 March 2009 19
  20. 20. Towards higher beam power: Which is better—more energy or more current? • If target lifetime and coolant volume fraction is preserved, higher beam current 3.6MW 1.8 MW 1 requires larger beam spot MTS Beam Footprint on Target ESS Bilbao Initiative Workshop 16-18 March 2009 20
  21. 21. Peak neutron flux goes as Pbeam0.8 ~ Ebeam0.8ibeam0.8 pk Ebeam = 0.8 GeV ibeam = 1 mA ~ ibeam0.8 ~ Ebeam0.8 pk pk ESS Bilbao Initiative Workshop 16-18 March 2009 21
  22. 22. Summary • Beam rastering and target imaging are key to the successful realization of high neutron flux in MTS • A water- or metal-cooled stationary solid target is viable beyond 1 MW – Solid targets have higher neutron production density than liquid metal targets – Replacement frequency is determined by target front face radiation damage, and is therefore the same as for a liquid metal target container if the beam current density is the same – A rotating solid target will have much longer lifetime than stationary targets • Target “performance” ~ (beam power)0.8 – Does not depend strongly on whether the power increase comes from higher current or higher energy ESS Bilbao Initiative Workshop 16-18 March 2009 22

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