Activation Analysis Activation Analysis  Calculations performed for DT pulses with 200 MW of fusion power  Four pulses per day with pulse width of 20 seconds and 3 hours between pulses  Calculations also performed for DD pulses with 1 MW of fusion power  Total fusion energy 5TJ DT and 0.5 TJ DD  Calculations performed for DT pulses with 200 MW of fusion power  Four pulses per day with pulse width of 20 seconds and 3 hours between pulses  Calculations also performed for DD pulses with 1 MW of fusion power  Total fusion energy 5TJ DT and 0.5 TJ DD NUCLEAR CONSIDERATIONS FOR FIRE M.E. Sawan and H.Y. Khater University of Wisconsin-Madison  FIRE design is in pre-conceptual phase with different design options and operation scenarios being considered  DT pulses with widths up to 20 s and fusion powers up to 200 MW produce a total of 5 TJ of fusion energy  DD pulses with different widths and fusion powers up to 1 MW yield total fusion energy of 0.5 TJ  A double walled steel VV with integral shielding adopted  VV thickness varies poloidally from 5 cm in inboard region to 54 cm in outboard region  The PFC include Be coated Cu FW and divertor plates made of tungsten rods mounted on water-cooled Cu heat sink  FIRE design is in pre-conceptual phase with different design options and operation scenarios being considered  DT pulses with widths up to 20 s and fusion powers up to 200 MW produce a total of 5 TJ of fusion energy  DD pulses with different widths and fusion powers up to 1 MW yield total fusion energy of 0.5 TJ  A double walled steel VV with integral shielding adopted  VV thickness varies poloidally from 5 cm in inboard region to 54 cm in outboard region  The PFC include Be coated Cu FW and divertor plates made of tungsten rods mounted on water-cooled Cu heat sink Background Background Peak Nuclear Heating (W/cm 3 ) for 200MW DT Shots Peak Nuclear Heating (W/cm 3 ) for 200MW DT Shots Nuclear Heating in OB FW/Tiles Nuclear Heating in OB FW/Tiles 20 25 30 35 40 45 50 55 60 0 1 2 3 4 5 W/cm 3 of Be W/cm 3 of Cu W/cm 3 of water Power Density (W/cm 3 ) Depth in OB FW/Tiles (cm) 200 MW DT Fusion Power 3.6 MW/m 2 Neutron Wall Loading Water Cooled Vessel Cladding Cu Tiles (80% Cu) Be PFC (90% Be) Gasket (50% Cu) Vessel Cladding (80% Cu, 15% water) Nuclear Heating in VV Drops by an Order of Magnitude in ~18 cm Nuclear Heating in VV Drops by an Order of Magnitude in ~18 cm 10 -2 10 -1 10 0 10 1 0 10 20 30 40 50 60 W/cm 3 of SS W/cm 3 of water Power Density (W/cm 3 ) Depth in OB VV at Midplane (cm) 200 MW DT Fusion Power 3.6 MW/m 2 Neutron Wall Loading Water Cooled Vessel Cladding VV Outer Wall VV Inner Wall VV Shielding Zone 60% SS, 40% Water Relatively High Nuclear Heating in W PFC of Outer Divertor Plate Relatively High Nuclear Heating in W PFC of Outer Divertor Plate 0 10 20 30 40 50 60 0 2 4 6 8 10 12 14 W/cm 3 of SS316 W/cm 3 of Cu W/cm 3 of W Total Power Density Power Density (W/cm 3 ) Depth in Outer Divertor Plate (cm) 200 MW DT Fusion Power 1.8 MW/m 2 Neutron Wall Loading Backing Plate Heat Sink Mechanical Attachment W Total Magnet Nuclear Heating in 16 TF Coils for 200 MW DT Shots Total Magnet Nuclear Heating in 16 TF Coils for 200 MW DT Shots Cumulative Damage in FIRE Components is Very Low Cumulative Damage in FIRE Components is Very Low Cumulative Peak Magnet Insulator Dose ( 5 TJ DT Shots and 0.5 TJ DD Shots) Cumulative Peak Magnet Insulator Dose ( 5 TJ DT Shots and 0.5 TJ DD Shots) 10 8 10 9 10 10 10 11 0 10 20 30 40 50 End-of-life Insulator Dose (Rad) Depth in IB Magnet at Midplane (cm) Total Fusion Energy of 5 TJ DT and 0.5 TJ DD Inboard Magnet at Midplane 2.7 MW/m 2 Neutron Wall Loading Water Cooled Vessel Cladding Insulator Lifetime Issues Insulator Lifetime Issues 10 -20 10 -19 10 -18 10 -17 10 -16 10 -15 10 -14 10 -13 10 -12 10 -11 10 -10 10 -9 10 -8 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 10 1 10 0 10 1 10 2 10 3 10 4 10 5 10 6 10 7 10 8 10 9 10 10 10 11 OB FW (D-T) OB VV (D-T) OB Magnet (D-T) OB FW (D-D) OB VV (D-D) OB Magnet (D-D) Specific Decay Heat (W/cm 3 ) Time Following Shutdown (s) 1 m 1 h 1 mo 1 y 100 y 1 d 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 10 1 10 2 10 3 10 4 10 5 10 6 10 7 10 0 10 1 10 2 10 3 10 4 10 5 10 6 10 7 10 8 Behind OB VV Behind OB Magnet Dose Rate (mrem/h) Time Following Shutdown (s) 1 w 1 h 1 d 1 mo 1 y Limit for Hands-on D-T Shots 10 -9 10 -8 10 -7 10 -6 10 -5 10 -4 10 -3 10 -2 10 -1 10 0 10 1 10 0 10 1 10 2 10 3 10 4 10 5 10 6 10 7 10 8 Behind OB VV Behind OB Magnet Dose Rate (mrem/h) Time Following Shutdown (s) 1 w 1 h 1 d 1 mo 1 y Limit for Hands-on D-D Shots Zone Fetter 10CFR61 IB FW 0.2 ( 108m Ag) 0.022 ( 63 Ni) IB VV 0.092 ( 108m Ag, 94 Nb) 0.035 ( 94 Nb, 63 Ni) IB Mag. 0.0002 ( 108m Ag) 0.0011 ( 63 Ni) OB FW 0.21 ( 108m Ag) 0.024 ( 63 Ni) OB VV 0.011 ( 108m Ag, 94 Nb) 0.0032 ( 94 Nb, 63 Ni) OB Mag. 2.26x10 -6 ( 94 Nb) 2.56x10 -6 ( 94 Nb, 63 Ni) Divertor 0.034 ( 108m Ag) 0.013 ( 94 Nb) Conclusions Conclusions Peak end-of-life cumulative radiation damage values in Cu components are < 0.05 dpa Data on loss of ductility between 80 and 373 K and thermal creep for CuCrZr at temperatures up to 500° C are needed. Peak end-of-life cumulative radiation damage values in Cu components are < 0.05 dpa Data on loss of ductility between 80 and 373 K and thermal creep for CuCrZr at temperatures up to 500° C are needed.  The commonly accepted dose limit for epoxies is 10 9 Rads (ITER)  Polyimides are more radiation resistant  Hybrids of polyimides and epoxies could provide radiation resistant insulators with friendly processing requirements  In FIRE design with wedged coils and added compression ring, the TF inner leg insulation does not have to have significant bond shear strength  Peak shear stresses occur at top and bottom of IB leg behind divertor. End-of-life dose to insulator at this location ~10 9 Rads  Magnet insulation materials with radiation tolerance to 1.5x10 10 Rads under FIRE load conditions need to be developed.  The commonly accepted dose limit for epoxies is 10 9 Rads (ITER)  Polyimides are more radiation resistant  Hybrids of polyimides and epoxies could provide radiation resistant insulators with friendly processing requirements  In FIRE design with wedged coils and added compression ring, the TF inner leg insulation does not have to have significant bond shear strength  Peak shear stresses occur at top and bottom of IB leg behind divertor. End-of-life dose to insulator at this location ~10 9 Rads  Magnet insulation materials with radiation tolerance to 1.5x10 10 Rads under FIRE load conditions need to be developed.  Low decay heat and activity at shutdown due to decay of short-lived radionuclides during the 3 hours between pulses  Activity and decay heat generated following D-D shots are more than three orders of magnitude lower than the D-T shots  Low decay heat and activity at shutdown due to decay of short-lived radionuclides during the 3 hours between pulses  Activity and decay heat generated following D-D shots are more than three orders of magnitude lower than the D-T shots  Modest values of nuclear heating occur in FW, divertor, VV, and magnet  End-of-life He production values imply that VV will be reweldable  Critical issues for copper alloys include low-temperature embrittlement and high-temperature thermal creep  Insulators with radiation tolerance up to ~ 1.5x10 10 Rads under FIRE load conditions should be used  Activity and decay heat values after shutdown are low  Following DT shots hands-on ex-vessel maintenance is possible with the 110 cm shield plug in midplane ports and the 20 cm shield at top of TF coil  All components would qualify for disposal as class C LLW according to both 10CFR61 and Fetter limits  Modest values of nuclear heating occur in FW, divertor, VV, and magnet  End-of-life He production values imply that VV will be reweldable  Critical issues for copper alloys include low-temperature embrittlement and high-temperature thermal creep  Insulators with radiation tolerance up to ~ 1.5x10 10 Rads under FIRE load conditions should be used  Activity and decay heat values after shutdown are low  Following DT shots hands-on ex-vessel maintenance is possible with the 110 cm shield plug in midplane ports and the 20 cm shield at top of TF coil  All components would qualify for disposal as class C LLW according to both 10CFR61 and Fetter limits Peak end-of-life He Production in VV Peak end-of-life He Production in VV FIRE Divertor Cross Section of FIRE BeCu / Cu interface BeCu 17510 OFHC 304 SS case material Insulated strip wound 304 or 316 SS 304 SS case material University of Wisconsin Fusion Technology Institute University of Wisconsin Fusion Technology Institute IB OB Be PFC 33.3 35.6 Cu Tiles 46.9 46.3 Gasket 40.6 40.6 Cooled Cu Vessel Cladding 40.2 40.1 H2O FWCoolant 27.6 30.9 SS Inner VV Wall 33.8 30.9 SS VV Filer 32.9 28.5 H2O VV Coolant 14.9 15.5 SS Outer VV Wall 30.3 0.07 Microtherm Insulation 9.8 0.02 SS Inner Coil Case NA 0.038 Cu Magnet 19.5 0.019 SS Outer Coil Case NA 2.8x10 -5 Dose (Rads) % from DD Shots IB midplane 1.26x10 10 13% OB midplane 1.26x10 7 1.6% Divertor 9.80x10 8 10% He appm IB midplane 0.11 OB midplane 0.15 Divertor 0.016 Magnet Nuclear Heating (MW) IB region 22.9 OB region 0.05 Divertor region 2.1 Total 25.05 Magnet Nuclear Heating (MW) IB region 22.9 OB region 0.05 Divertor region 2.1 Total 25.05 All Components Qualify as Class C LLW  Following DT shots hands-on ex-vessel maintenance is possible with - The 110 cm long steel shield plug in midplane ports - The 20 cm shield at top of TF coil  Following DD shots immediate access for maintenance is possible behind OB VV  Following DT shots hands-on ex-vessel maintenance is possible with - The 110 cm long steel shield plug in midplane ports - The 20 cm shield at top of TF coil  Following DD shots immediate access for maintenance is possible behind OB VV Activity and Decay Heat Values are Tolerable Activity and Decay Heat Values are Tolerable Biological Dose Rates at Midplane Biological Dose Rates at Midplane  He Production in VV < 1 appm Allowing for Rewelding  Contribution from DD shots very small (<0.15%)