Verification of Important Cross-Section Data*

1. Verification of ImportantCross-Section Data* E.T. Cheng Solana Beach, California IAEA Technical Meeting on Nuclear Data for IFMIF 4-6 October 2005 FZK, Karlsruhe, Germany *Work Supported by the USDOE, Office of Fusion Energy Sciences

2. Verification of Fusion Nuclear Data • Continuing Efforts in Nuclear Data Development Have Made Fusion Design Less Uncertain • Integral Neutronics Experiments Being Performed for ITER and Power Plant Development • Nuclear Data Measurements Needed to Verify Important Evaluated Cross Sections

3. Verification of Important Cross Sections • Si28(n,n’p)Al27 • V51(n,n’p)Ti50 • Helium Production Data

5. Si28(n,n’p)Al27 • Si28(n,n’p)Al27 Reaction leads to Production of Long-lived Radionuclide Al26(7.17x105 y half-life; gamma-emitter) • Low Level Waste Disposal Rating: Ratio of Activation Level to the Limiting Activity for Low Level Waste • Calculations of Al26 Production in SiC Using the Best Evaluated Nuclear Data Result in a (Class C) Low Level Waste Disposal Rating of 0.5 after Lifetime Irradiation of SiC in a Fusion Power Reactor

6. Measurements of Si28(n,n’p)Al27 • Activation Method • Suggested by Hermann Vonach, Successfully Detected Nb as an Impurity in Vanadium [Nb93(n,2n)Nb92m] • Required High-purity Si Samples • Detecting Na24 Activity [Si28(n,n’p)Al27(n,α)Na24] • Proton Measurements • Thin Si Samples • Measuring Total Si28(n,xp) Cross Sections • Subtracting Si28(n,p) from Si28(n,xp) • Measurements Performed at 14 MeV Energy and Above

7. Measurements of Si28(n,n’p)Al27(Activation Method) • High-purity Si Samples • Al27 Production Concentrations: ~0.05 appb (1 h); ~1.3 appb (1 d); and ~40 appb (30 d) [1011 n/s/cm2] • Irradiate Samples for Several Hours and Detect Na24 [Al27(n,α)] Activity to Determine Al Content • Verify Purity of Si Samples (Al/Si Must be < 1 appb) • For Confirmed Pure Si Samples, Continue Irradiation for Weeks or Months and Measure the Increase of Na24 Activity

8. Source: D. Rockman, et al. NNDC, BNL (2005)

9. V51(n,n’p)Ti50 • Inaccurate V51(n,n’p)Ti50 Cross Section leads to an Overestimate of Hydrogen Production in the Vanadium Alloy, and Transmutation Product Ti • Prediction of Vanadium Alloy Life Time Depends on the Accuracy of the Cross Section • Hydrogen Embrittlement • Degradation in Structural Properties

11. Measurements of V51(n,n’p)Ti50 • Proton Production Cross Sections • Thin V Samples • Measuring Total V51(n,xp) Cross Sections • Subtracting V51(n,p)Ti51 from V51(n,xp) • Measurements Performed at 14 MeV Energy and Above

12. Materials Testing with IFMIF • IFMIF can Produce High Neutron Flux to Reach Needed Helium Concentrations and Atomic Displacements (DPA) for Materials Damage Assessment in a Reasonable Time • Helium to DPA in IFMIF Neutron Spectrum is Estimated to be Similar to that in a D-T Fusion Neutron Spectrum • Helium Production Cross Sections are Fundamental to the Radiation Damage Assessment

13. Helium Production Data for IFMIF Verify Helium Production Data with IFMIF and D-T 14 MeV Neutron Sources • Irradiate Samples at the 14 MeV Neutron Sources and IFMIF-like Facilities • Measure Helium Contents • Derive Helium Production Cross Sections and Compare to Evaluations (or Calculations)