9 th session of the AER Working Group “f “ - Spent Fuel Transmutations Simulations of experimental “ADS” Mitja Majerle, Gael de Cargouet Nuclear Physics Institute Řež, Czech Republic Supercomputer Cray I

AER Working Group “f “ - Spent Fuel Transmutations Introduction  Experimental ADS at JINR Dubna High energy protons/deuterons Spallation source (lead) Optionally moderator Measurement of neutron fluxes  MCNPX simulations: Beside standard MCNP :  spallation  high energy neutron transport Differences experiment-simulation

AER Working Group “f “ - Spent Fuel Transmutations MCNP vs. MCNPX

AER Working Group “f “ - Spent Fuel Transmutations Experimental setups  Accelerator (Nuclotron, Phasotron) +  Target with polyethylene – GAMMA-2 (low energy neutrons < 0.1 MeV)  Bare target – PHASOTRON (high energy neutrons >10 MeV)  Target with uranium blanket - EPT  Target in graphite block – GAMMA-MD

AER Working Group “f “ - Spent Fuel Transmutations What we measure…  Radiochemical detectors Monoisotopic foils activated by neutrons Gamma spectrometry  n,xn ( MeV)  n,(<0.1 MeV)  Solid state nuclear track detectors Fissile material (Pb, U) + mica foil Chemical etching Optical microscopy  n,fission (>100 MeV in Pb)  Radioactive samples U, Pu, Np, I, … packed in Al Gamma spectrometry  Mostly n,xn reactions

AER Working Group “f “ - Spent Fuel Transmutations PHASOTRON EXPERIMENT

AER Working Group “f “ - Spent Fuel Transmutations.. and how do we simulate ?  Neutron spectrum is calculated with MCNPX Neutron spectrum from PHASOTRON experiment  Cross-sections calculated with MCNPX/TALYS (n,xn), (n,n,fission)  Convolution: REACTION RATE=NS*XS

AER Working Group “f “ - Spent Fuel Transmutations PHASOTRON Simple, clean setup 660 MeV protons Radiochemical detectors, samples Calculations :  HE - good agreement  LE - many influences

AER Working Group “f “ - Spent Fuel Transmutations ENERGY PLUS TRANSMUTATION Pb target + U blanket 4 proton beams :  0.7, 1, 1.5, 2 GeV 2 deuteron beams:  2.52, 1.26 GeV Detectors :  Radiochemical  SSNTD  Samples

AER Working Group “f “ - Spent Fuel Transmutations Calculations (EPT) Radiochemical:  beam < 1.5 GeV good agreement HE  beam >= 1.5 GeV SSNTD:  1.5 GeV good agreement Neutrons MeV bad - >100 MeV good

AER Working Group “f “ - Spent Fuel Transmutations GAMMA-MD Pb target Graphite block 2.33 GeV deuterons experiment

AER Working Group “f “ - Spent Fuel Transmutations Low energy neutron spectrum Experiments aimed towards HE neutrons Parameters of shileding, concrete walls… are not precisely known LE results can be used for eg. relative comparison between experiments

AER Working Group “f “ - Spent Fuel Transmutations Summary  Below 1 GeV, calculations are reliable within 30%  Above 1.5 GeV, wrong results for neutrons MeV, energies >100 MeV are probably OK (SSNTD)  Possible reasons under investigation (spallation model or XS libraries) ?

AER Working Group “f “ - Spent Fuel Transmutations Parallel computing  Monte-Carlo method can be very well parallelized  MCNPX supports MPI and PVM  Tested on 32bit Xeons (4x) and 64bit Opterons(8x)-speed ca. linearly rises with the number of processors  Plan to try computer farms (grid system)

AER Working Group “f “ - Spent Fuel Transmutations TALYS TALYS: nuclear reaction software by NRG Petten and CEA Bruyères-le-Châtel. Energy range 1 keV MeV. Neutrons, protons, deuterons, tritons, helions, alphas and photons. Many nuclear reaction models implemented. All open nuclear reaction channels covered. Appropriate for basic physics and applications.

AER Working Group “f “ - Spent Fuel Transmutations TALYS A friendly program

AER Working Group “f “ - Spent Fuel Transmutations Data produced by TALYS Total, elastic, Inelastic and reaction cross sections. Exclusive reaction channels, e.g. (n,p), (n,np). Exclusive isomeric production cross sections. Fission cross sections. Fission yields. Total particle production cross sections, e.g. (n,xn).

AER Working Group “f “ - Spent Fuel Transmutations Data produced by TALYS Comparison with experimental data