BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, MULTI-MW TARGET DEVELOPMENT FOR EURISOL & EUROTRANS Y. Kadi & A. Herrera-Martinez (AB/ATB) European Organization for Nuclear Research, CERN CH-1211 Geneva 23, SWITZERLAND

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Multi-MW Target Challenges High-Power issues –Thermal management Target melting Target vaporization –Radiation Radiation protection Radioactivity inventory Remote handling –Thermal shock Beam-induced pressure waves –Material properties

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Thermal Management: Liquid Target with window The SNS Mercury Target Harold G. Kirk et al. (BNL)

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Thermal Management: Liquid Target with window F. Groeschel et al. (PSI) MEGAPIE Project at PSI 0.59 GeV proton beam 1 MW beam power Goals: Demonstrate feasablility One year service life Irradiation in 2005 Proton Beam

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Thermal Management: Liquid Target with window F. Groeschel et al. (PSI)

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Thermal Management: Liquid Target with free surface High-speed flow (2.5 m/s) permits effective heat removal BEAM DG16.5 Hg Experiments nominal volume flow 10 l/s Close to desired configuration  intermediate lowering of level  some pitting  axial asymmetry

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Thermal Management: Target Pitting Issue ESS team has been pursuing the Bubble injection solution. SNS team has focused on Kolsterizing (nitriding) of the surface solution. SNS team feels that the Kolsterized surface mitigates the pitting to a level to make it marginally acceptable. Further R&D is being pursued. After 100 pulses at 2.5 MW equivalent intensity Before Harold G. Kirk et al. (BNL)

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Worldwide Programs ProjectNeutron SourceCorePurpose MUSE (France) DT (~10 10 n/s) Fast (< 1 kW) Reactor physics of fast subcritical system TRADE (Italy) Proton (140 MeV) + Ta (40 kW) Thermal (200 kW) Demonstration of ADS with thermal feedback TEF-P (Japan) Proton (600 MeV) + Pb-Bi (10W, ~10 12 n/s) Fast (< 1 kW) Coupling of fast subcritical system with spallation source including MA fueled configuration SAD (Russia) Proton (660 MeV) + Pb-Bi (1 kW) Fast (20 kW) Coupling of fast subcritical system with spallation source MYRRHA (Belgium) Proton (350 MeV) + Pb-Bi (1.75 MW) Fast (35 MW) Experimental ADS MEGAPIE (Switzerland) Proton (600 MeV) + Pb-Bi (1MW) -----Demonstration of 1MW target for short period TEF-T (Japan) Proton (600 MeV) + Pb-Bi (200 kW) Dedicated facility for demonstration and accumulation of material data base for long term Reference ADS Proton ( ≈ 1 GeV) + Pb-Bi (≈ 10 MW) Fast (1500 MW) Transmutation of MA and LLFP

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Thermal Management: radiation cooled rotating toroidal target toroid at 2300 K radiates heat to water-cooled surroundings rotating toroid proton beam solenoid magnet toroid magnetically levitated and driven by linear motors R.Bennett, B.King et al. Distribute the energy deposition over a larger volume Similar a rotating anode of a X-ray tube

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Thermal Management: JET J.Lettry et al. (CERN) TT2A

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Radiation Management The SNS Target Station Core Vessel water cooled shielding Core Vessel Multi- channel neutron guide flange Outer Reflector Plug Target Inflatable seal Target Module with jumpers Moderators

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Radiation Management

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Radiation Management The JPARC Kaon Target Concrete shield Concrete shield block Service space: 2m(W)  1m(H) Beam ~10m ~18m T1 container Iron shield2m2m Water pump

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Objectives The objective is to perform the technical preparative work and demonstration of principle for a high power target station for production of beams of fission fragments using the mercury proton to neutron converter-target and cooling technology similar to those under development by the spallation neutron sources, accelerator driven systems and the neutrino factories. This high power target that will make use of innovative concepts of advanced design can only be done in a common effort of several European Laboratories within the three communities and their proposed design studies. In this study emphasis is put on the most EURISOL specific part a compact window or windowless liquid-metal converter-target itself while the high power design of a number of other more conventional aspects are taken from the studies in the other EURISOL tasks or even in other networks like ADVICES, IP-EUROTRANS. EURISOL – Multi-MW Target

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, x100 kW direct irradiation Fissile target surrounding a spallation n-source –>100 kW Solid converters (PSI-SINQ 740 kW on Pb, 570 MeV 1.3 mA / RAL-ISIS 160 kW on Ta, 800 MeV 0.2 mA / LANL-LANSCE 800 kW on SS cladded W, 800 MeV 1.0 mA ) –4 MW Liquid Hg (windowless or jet) EURISOL Target Stations

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, kV > 2000º Grounded < 200º EURISOL Hg-converter and 238 UC 2 target

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, P4 – CERN P18 – PSI Switzerland P19 – IPUL Latvia C5 – ORNL USA ParticipantsContributor EURISOL – Multi-MW Target

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, EURISOL – Multi-MW Target

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Description of work The task will be accomplishment through detailed engineering and theoretical work, off line and on-line testing of the different subsystems as seen from the following 5 subtasks:  Engineering study of the thermal hydraulics, fluid dynamics and construction materials of a liquid-metal converter (window/windowless or jet);  Study of an innovative waste management in the liquid Hg-loop e.g. by means of Hg distillation;  Engineering design and construction of a functional Hg-loop;  Off-line testing and validation of the thermal hydraulics and fluid dynamics;  Engineering design of the entire target station and its handling method. EURISOL – Multi-MW Target

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Main goals for the first months  Provide a first technical design of the liquid Hg proton-to-neutron converter  Provide a status report on optimum method for continuous extraction of radioisotopes  Provide a preliminary engineering design and cost evaluation of the liquid Hg test loop  Initiate technical study on the integration of the entire target station EURISOL – Multi-MW Target

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Engineering Study of the liquid metal converter  Definition of the main parameters (neutron flux angular and energy distributions, radiation damage, heat deposition, spallation product distributions) as a function of energy (1 – 3 GeV) and type of incident particle (p or d)  Establishment of the operation modes (Hg flow rates, cavitation limits, thermo-mechanical behaviour of the structures under normal operating conditions)  Evaluation of the feasibility of a windowless configuration Breakdown of work (per sub-task)

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Projectile Particle: Proton Beam Shape: Gaussian,  ~1.7 mm Energy Range: 1–2–3 GeV Target Material: Hg / PbBi Target Length: 40–60–80–100 cm Target Radius: 10–20–30–40 cm Spatial and energy particle distribution Preliminary Studies

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, GeV Proton range ~46 cm The beam opens up to ~20 degrees, with some primary back-scattering Primaries contained in ~50 cm length and ~30 cm radius 1 GeV Primary Proton Flux

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Maximum energy deposition in the first ~14 cm in the beam axis beyond the interaction point, ~30 kW/cm 3 /MW of beam  dT/dt ~14 K/s (Hg boiling point at 357 ºC) Energy deposition drops one order of magnitude at the proton range (~46 cm) Large radial gradients (dE/dr ~200) in the interaction region Energy Deposition for 1 GeV protons

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Neutron flux centered radially around ~10 cm from the impact point Isotropic flux after ~15 cm from the center, decreasing with r 2 Escaping neutron flux peaking at ~300 keV (evaporation neutrons), with a 100 MeV component in the forward direction (direct knock-out neutrons) Radial End Cap Front Cap Neutron Flux Distribution for 1 GeV Protons

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Very low fission cross-section in 238 U below 2 MeV (~10 -4 barns). Optimum neutron energy: 35 MeV Alternatively, use of natural uranium: fission cross-section in 235 U (0.7% wt.) for 300 keV neutrons: ~2 barns Further gain if neutron flux is moderated Neutron Energy Spectrum vs Fission Cross-Section in Uranium

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Protons Hg Target UCx Target Standard Configuration Protons Hg Target Reflector / UCx Target Alternative Configurations Reflector / UCx Target Low-Z Filter (?) UCx Target Reflector? Alternative Target Configurations Deuterons

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Protons Hg Target Reflector / UCx Target Alternative Configurations Reflector / UCx Target Low-Z Filter (?) UCx Target Increasing HE neutron flux through the End- Cap with decreasing Hg target length Increasing charged-particle and photon escapes with decreasing Hg target length Possible use of a low-Z filter to “tune” the average neutron energy to 35 MeV (maximise fission probability in 238 U) Alternative Target Configurations Deuterons

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Neutron absorbing region ~6 cm behind the interaction region, following the primary particle distribution Neutron producing region extending to the end of the target Small contributions from regions beyond the proton range Neutron producing region not extending beyond r =10–13 cm Neutron absorbing region Neutron producing region Neutral balance boundary Neutron Balance Density for 1 GeV Protons

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, GeV Proton range ~110 cm Forward peaked primary distribution at ~10 degrees No back-scattering and rare radial escapes Few end-cap escapes: 2  escapes/primary with an average energy of 1 GeV for 80 cm 2  escapes/primary with an average energy of 0.7 GeV for 100 cm 2 GeV Primary Proton Flux

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Largest energy deposition in the first ~18 cm beyond the interaction point, ~16 kW/cm 3 /MW of beam  dT/dt ~8 K/s (40% lower compared to the use of 1 GeV primary protons) Identically, smaller radial gradient in the interaction region (dE/dr ~100) Energy Deposition for 2 GeV protons

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Neutron Yield (2 GeV proton) : 57 – 77 n/p Neutron flux centered radially around ~15 cm from the impact point, presenting a forward-peaked component Escaping neutron flux peaking at ~300 keV, with a 100 MeV component in the forward and radial directions and few 1 GeV neutrons escaping through the end-cap Harder neutron energy spectrum and higher flux and in the target compared to the 1 GeV case Neutron Flux Distribution for 2 GeV Protons

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Increase in the relevance of the axial region in the neutron production Neutron producing region still not extending beyond r =10 – 13 cm The neutron capturing region gains relevance (– 6  bal/cm 3 /prim) compared to 1 GeV (– 6  bal/cm 3 /prim) Significant reduction in neutron captures (one order of magnitude) by reducing the radius to 20 cm Neutron absorbing region Neutron producing region Neutral balance boundary Neutron Balance Density for 2 GeV Protons

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, GeV Proton range ~175 cm The beam opens up to ~8 degrees, no back-scattering and few radial escapes (even for 20 cm radius) Some primaries escapes through the end-cap (~ 5  escapes/primary) Average energy of the escaping protons ~750 MeV 3 GeV Primary Proton Flux

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Largest energy deposition in the first ~22 cm beyond the interaction point, ~12 kW/cm 3 /MW of beam  dT/dt ~6 K/s (60% lower compared to the use of 1 GeV primary protons) Smaller radial gradient in the interaction region (dE/dr ~50) compared to the 1 GeV case Energy Deposition for 3 GeV protons

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Neutron Yield (3 GeV proton) : 82 – 113 n/p Neutron flux centered radially around ~20 cm from the impact point, with a larger forward-peaked component Escaping neutron flux peaking at ~300 keV, with a 100 MeV component in the forward and radial directions and some 1.5 GeV neutrons escaping through the end-cap Slightly higher neutron flux in the target compared to the 2 GeV case Neutron Flux Distribution for 3 GeV Protons

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Hg PbBi 1 GeV proton range in Hg: ~46 cm 1 GeV proton range in PbBi: ~60 cm PbBi Alternative – 1 GeV Primary Particles

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Hg PbBi Maximum energy deposition ~30 kW/cm 3 /MW of beam Maximum energy deposition ~21 kW/cm 3 /MW of beam PbBi Alternative – Energy Deposition

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Hg PbBi PbBi Alternative – Neutron Flux

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, PbBi Hg Neutron absorbing region Neutral balance boundary Neutron producing region PbBi Alternative – Neutron Balance

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, PbBi Alternative – Neutron Spectrum

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Optimised for neutron production: Radius: 10 – 15 cm target radius from neutron balance point of view is enough Length: Extend to the proton range to maximise neutron production and avoid charged particles in the UCx Energy Spectrum of the neutrons: Dominated by the intermediate neutron energy range ( 20 keV - 2 MeV) Harden neutron spectrum by reducing the target size (but reduce yield and increase HE charged particle contamination) Use of natural uranium to take advantage of the high fission cross-section of 235 U in the resonance region  Improvement thorough neutron energy moderation Alternatively, axial converter-UCx target configuration for depleted uranium target Very localised energy deposition, 20 cm from the impact point along the beam axis ~30 kW/cm 3 /MW of beam power, reduced with the increasing proton energy Possibility of using PbBi eutectic to improve neutron economy and reduce maximum energy deposition Summary of the Results

BENE Week, CERN, SwitzerlandY.KADIMarch 16-19, Optimise the energy deposition once the size is fixed Study the effect of the shape of the beam (parabolic, annular, variations in the sigma of the Gaussian distribution) Activation of the target (calculate the spallation product distribution) Model the fission target (including moderator/reflector) and optimise the fission yields Analyse alternative target disposition to improve the fission yields Study the use of deuterons as projectile particle Future Work