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EURISOL DS PROJECT Task#2: MULTI-MW TARGET DESIGN

EURISOL DS PROJECT Task#2: MULTI-MW TARGET DESIGN. Adonai Herrera-Martínez & Yacine Kadi on behalf of T2 European Organization for Nuclear Research, CERN CH-1211 Geneva 23, SWITZERLAND Adonai.herrera.martinez@cern.ch. Overview. Baseline Parameters

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EURISOL DS PROJECT Task#2: MULTI-MW TARGET DESIGN

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  1. EURISOL DS PROJECTTask#2: MULTI-MW TARGET DESIGN Adonai Herrera-Martínez & Yacine Kadi on behalf of T2 European Organization for Nuclear Research, CERN CH-1211 Geneva 23, SWITZERLAND Adonai.herrera.martinez@cern.ch

  2. Overview • Baseline Parameters • Baseline Design (BLD) vs. Hg Jet (Hg-J) → Intermediate Solution (IS) • Comparison of the FLUKA Simulation Results • Primary Particle Flux → Proton Escapes • Neutron Flux and Energy Spectra • Fission Densities → Isotopic Yields • Energy Deposition → Temperature Increase • Conclusions

  3. Sensitivity Study http://eurisol-hg-target.web.cern.ch/eurisol-hg-target/

  4. Baseline Parameters of the MMW Hg Target

  5. Reflector Reflector UCx/BeO Target Reflector UCx/BeO Target Protons 16 cm Hg Target UCx/BeO Target Protons Target container Protons 4 cm Hg Jet 30 cm Hg Target 68 cm UCx/BeO Target Reflector Target container 73 cm Reflector Reflector 40 cm MMW Hg Target Configuration • BLD: Shape of Hg target optimised for neutron production (neutron balance) • 15 mm sigma proton beam, fully contained in the Hg target • Possibility of further reduction in Hg target dimensions → Intermediate solution (IS) • Hg-J: designed for high-energy neutron fluxes in the UnatC3 (3 g/cm3) fission target • 4 mm sigma proton beam, mostly contained in the 4 cm diameter Hg Jet • Use of reflector to improve neutron economy and to shield HE particles

  6. Primary Proton Flux Distribution • 1GeV proton range ~ 46 cm • BLD: Beam fully contained inside • Hg-J: Important HE primary escapes (~1013 prim/cm2/s/MW of beam), mostly at small polar angles (up to 25% losses)→ Beam dump • IS: Some primary escapes through the endcap, mostly contained by the reflector • BLD and IS: Beam window suffering ~100 μA/cm2/MW (radiation damage limit) Primary flux (prim/cm2/s/MW of beam)

  7. Neutron Flux Distribution Neutron flux (n/cm2/s/MW of beam) • Neutron fluxes in the fission target ~1014 n/cm2/s/MW of beam • BDL and IS: Partial containment by the reflector of the escaping neutron flux • Hg-J: Higher neutron flux in the fission target (~2×1014n/cm2/s/MW of beam)

  8. Neutron Energy Spectrum vs Fission Cross-Section in Uranium • Significantly harder spectrum for the Hg-J, with a peak neutron energy between 1 − 2 MeV, compared to 300 keV for BLD and 700 keV for IS • Very low fission cross-section in 238U below 2 MeV (~10-4 barns). Optimum energy: 35 MeV • Use of natural uranium: sf in 235U (0.7% wt.): at least 2 barns • Further gain if neutron flux is reflected (e.g. BeO)

  9. Fission Density Distribution in UnatC3 Fission density (fissions/cm3/s/MW of beam) • High-energy fissions in Hg → Radioactive isotopes in Hg • BLD: 1011 fiss/cm3/s/MW, homogenously distributed • Hg-J: High and anisotropic fission density (~4×1011 fiss/cm3/s/MW) • IS: 2×1011 fiss/cm3/s/MW, homogenously distributed → ~1015 fissions/s for 4 MW of beam and a 1 litre UnatC3 (3 g/cm3) fission target

  10. HE Fission Density Distribution in UnatC3 HE fission density (fissions[>20 MeV]/cm3/s/MW of beam) • Non-homogenous HE fissions in all cases • BLD: ~10% of the fissions are HE (>20 MeV), compared to ~20% in IS and ~40% in Hg-J

  11. LE Fission Density Distribution in UnatC3 LE fission density (fissions[<20 MeV]/cm3/s/MW of beam) • BLD: LE fissions account for 90% of the radial fissions • BDL and IS: Important effect of the reflector ← More LE fissions in the outside surface of the fission target • Hg-J: Stronger anisotropy in the LE fissions and lack of containment for LE neutrons

  12. Power Densities (1) Power density (W/cm3/MW of beam) • Maximum energy deposition in the first 10 cm beyond the interaction point, in Hg • BLD and IS, maximum power density in Hg: ~2 kW/cm3/MW of beam • Hg-J, maximum power density in Hg: ~22 kW/cm3/MW of beam! • Power density in the UnatC3 target: ~3 W/cm3/MW of beam in the BLD and ~5 W/cm3/MW the IS, homogenously distributed in both • ~20 W/cm3/MW of beamUnatC3 target for the Hg-J, following the fission density distribution → Strongly anisotropic

  13. Power Densities (2) Hg • More than one order of magnitude difference between the free surface Hg-J (~22 kW/cm3/MW) and the confined Hg targets (BLD, ~2 kW/cm3/MW) • BDL and IS: Beam window suffering important power densities (~1 kW/cm3/MW → extra cooling plus radiation resistant material needed) Beam Window

  14. Power Densities (3) • Increasing sbeam from 15 to 25 mm or taking parabolic beam of at least 45 mm radius → reduce DT in Hg by a factor 2 - 2.5 • Doubling the flow rate (~2 m/s) will reduce DT by factor 2 • →DT ~ 130 - 150 ºC

  15. Radioisotope Yields in UnatC3 Target (1) Harder neutron spectrum for the Hg Jet → more high-energy neutron induced fissions → large increase in the symmetrical fission products Small differences in terms of asymmetrical (low energy) fission fragments

  16. Radioisotope Yields in the UnatC3 (1) Ni isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD Ga isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD

  17. Radioisotope Yields in the UnatC3 (2) Ga isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD Kr isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD

  18. Radioisotope Yields in the UnatC3 (3) Kr isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD Sn isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD

  19. Radioisotope Yields in the UnatC3 (4) Sn isotopic yields (Ions/cm3/s/MW of beam) and ratio over BLD

  20. Conceptual Design of the MMW Hg Target • Conclusions • The Intermediate Solution brings us closer to the ideal performance of a Hg Jet in terms of fission density and relevant isotopic yields, additionally reducing the particle escapes and power densities in Hg • The Hg Jet presents important technical issues regarding Hg cooling, radiation damage to the nearby structures and radiation shielding • Need to clearly establish the beam requirements (i.e. CW vs. pulsed, beam frequency and beam shape) and fission target configuration

  21. The End (... or The Beginning)

  22. Fission Density Distribution: UnatC vs 238UC UnatC • 3 times more fissions with UnatC compared to UnatC3 (proportional to density) • With 238UC less isotropic distribution and fission yield reduced by factor 3 238UC

  23. Residual Nuclei Distributions in Hg •  At high masses it is characterized by the presence of three peaks corresponding to(i) the initial target nuclei, (ii) those obtained after evaporation below and (iii) those obtained after acivation above (A+1) •  Three very narrow peaks corresponding to the evaporation of light nuclei such as (deuterons, tritons, 3He and a) • An intermediate zone corresponding to nuclei produced by high-energy fissions (symmetric distr.) • At higher proton energy nuclei from evaporation and multi-fragmentation (ligth nuclei) are more abundant

  24. Radioisotope yields in UCx targets •  At high masses it is characterized by the presence of acivation products (Pu239 !!) ==> dominates over fission !! •  Three very narrow peaks corresponding to the evaporation of light nuclei such as (deuterons, tritons, 3He and a) ==> very few • An intermediate zone represented double humped distribution corresponding to nuclei produced by low-energy fissions • twice as much fission in radial position

  25. Radioisotope yields in UCx targets (2)  5 times less fissions with U238 overall but…  equal amount of high-energy neutron induced fissions (sym. distribution)

  26. Radioisotope yields in UCx targets (3)  harder neutron spectrum along the beam axis with 2 GeV protons ==> more high-energy neutron induced fissions and few evaporations  no differences radially

  27. Radioisotope yields in BeO target  aim for 2x10136Heat/s

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