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ADS experiments in Dubna. Mitja Majerle for the “ Energy Plus Transmutation ” collaboration. What are Accelerator Driven Systems ?. Accelerator Driven Systems. Subcritical reactor Wider choice for reactor fuel ( 238 U, 232 Th) Transmutation of nuclear waste Increased safety
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ADS experiments in Dubna MitjaMajerle for the “Energy Plus Transmutation” collaboration
Accelerator Driven Systems • Subcritical reactor • Wider choice for reactor fuel (238U, 232Th) • Transmutation of nuclear waste • Increased safety • Accelerator • Protons or light ions of energy around 1 GeV • Very high powers (tens, hundreds of MeW) • Stability of the beam • Spallation reaction
Some projects on this topic • C.Rubbia at CERN (protons on lead block) • MUSE Cadarache (reactor keff=0.95 with (d,t) source) • TRADE Casaccia (reactor coupled with cyclotron) • MEGAPIE at PSI (target research)
Dubna research • Until today: • cross-section measurements on 660 MeV protons • Lead+parafine (GAMMA-2) • Lead target (PHASOTRON) • Energy Plus Transmutation • Lead in graphite block (GAMMA-MD) • Future: • Subcritical Assembly Dubna (SAD)
PHASOTRON experiment • Lead target + 660 MeV protons • Activation detectors (Au, Al, Bi) • 129I samples • Focus – spatial distribution of fast neutrons
ENERGY PLUS TRANSMUTATION • Lead target + natU blanket • Protons (0.7-2 GeV), deuterons (1.6-2.52 GeV) • Activation detectors (Al, Au, Bi, Cu, In, Ta, Y) • Solid state nuclear track detectors (235U, 238U, natPb) • Fastneutrons in uranium
GAMMA-MD • Lead target + graphite moderator • Deuterons 1.6 GeV • Activation detectors (Al, Au, Bi, Cu, In, Ta, Y) • Solid state nuclear track detectors (235U, 238U, natPb) • Fastneutrons in graphite
Activation detectors • Monoisotopic materials (Au, Al, Bi, In, Ta, Y, …) • Activation during the irradiation • (n,xn), (n,g), (n,a) reactions, but also (p,pxn),.. • Activity measurement after the irradiation • Activity a number of produced isotopes n HPGe detector (n,xn), (n,g), … g
Solid state nuclear track detectors • Irradiator material (Pb, 235U, 238U) + plastic, mica … • (n,f) reactions - fission fragments leave tracks in plastic • Chemical etching • Track counting with microscope • Tracks a number of fissions n chemical etching n,fission tracks
Monte-Carlo simulations • MCNPX, FLUKA -> spectral fluence • Spallation • Transport of particles • Spectral fluence folded with cross-sections = number of produced isotopes or fissions -> experimental values • Experiment / calculations inside 30%: • Cross-sections or • Monte-Carlo codes ? by A. Potapenko
Experiment / calculation Phasotron experiment at 660 MeV : measurement/FLUKA calculation. Detectors are placed on top of the target along its length. Energy plus transmutation at 1.5 GeV: Measurement / MCNPX calculation. Detectors are placed in radial direction In the first gap.
Status of cross-sections • (n,xn) reaction in energy range 10-100 MeV • Materials in detectors: Al, Au, Bi, Cu, In, Ta, Y • Other : 127I, 129I • Higher x reactions – n,3n-n,10n – few measurements • (n,f) reactions in energy range 10-1000 MeV • Materials : Pb, 235U, 238U • Other heavy materials : Au, W, Bi, Th • For materials other than U few measurements
Conclusion • Monte-Carlo predictions of XADS within 30% with the experiment –better accuracy needed for real ADS • Mostly (n,xn) and (n,f) cross-sections in energy range 10-1000 MeV are needed • Cross-sections that we need can be used also for monitoring neutron fluxes at other experiments, in reactors ... • Currently we work on some measurements inside EFNUDAT (Ondrej Svoboda talk)