S.P. Simakov

Status of the McDeLicious Approach for the D-Li Neutron Source Term Modeling in IFMIF Neutronics Calculations

Abstract McDeLicious is an extension to the MCNP Monte Carlo code with the ability to simulate the generation of source neutrons based on D-Li interaction processes. This paper presents an overview of the McDeLicious approach for the D-Li neutron source term modeling including latest code extensions, improvements, validation efforts, and applications to IFMIF neutronics analyses. The current McDeLicious capabilities include the generation of source neutrons and photons based on evaluated d + 6,7Li cross-section data and the sampling of the impinging deuteron beam intensity distribution using fitting functions or probability tables. The McDeLicious software has been updated to comply with the standard of the state-of-the-art version 5 of the MCNP code. A message passing interface program version enables one to run McDeLicious in parallel mode on large computer clusters. McDeLicious is in routine use for IFMIF neutronics calculations employing different nuclear data including a test version of the recent FENDL-3 nuclear data.

''Proton Activation Data File'' to Study Activation and Transmutation of Materials Irradiated with Protons at Energies up to 150 MeV

To satisfy growing needs in nuclear data at intermediate energies, the Proton Activation Data File (PADF) has been prepared. It contains 418,575 excitation functions of nuclear reactions for 2,355 target nuclei from Mg to Ra at proton energies up to 150 MeV. The data are available in the PADF for stable and unstable target nuclei including isomeric targets with the half-life more than one second. Cross-sections included in the PADF were obtained by using the TALYS code, the modified ALICE code, and the available experimental data.

Spectral Flux of the p- 7 Li(C) Q-M Neutron Source Measured by Proton Recoil Telescope

The cyclotron-based fast neutron source at NPI produces mono-energetic neutron fields up to 35 MeV neutron energy using the p + 7Li(carbon backing) reactions. To be applied for activation cross-section measurements, not only the intensity of neutron peak, but also the contribution of low-energy continuum in the spectra must be well determined. Simulations of the spectral flux from present source at a position of irradiated samples were performed using CYRIC TOF-data validated in the present work against LA150h by calculations with the transport Monte Carlo code MCNPX.Simulated spectra were tested by absolute measurements using a proton-recoil telescope technique. The recoil-proton spectrometer consisted of a shielded scattering chamber with polyethylene and carbon radiators and the ΔE1-ΔE2-E telescope of silicon-surface detectors located to the neutron beam axis at 45° in the laboratory system. Si-detectors were handled by usual data acquisition system. Dead-time – and pulse-overlap losses of events were determined from the count rate of pulse generator registered during duty cycle of accelerator operation. The proton beam charge and data were taken in the list mode for later replay and analysis.The calculations for 7 Li(p,n) and 12 C(p,n) reactions reasonably reproduce CYRIC TOF neutron source spectra. The influence of neutron source set-up (proton beam dimensions, 7 Li-foil, carbon stopper, cooling medium, target support/chamber and the geometry-arrangement of irradiated sample) on the spectral flux is discussed in details.

Assessment of the tritium production in the HFTM specimen cells of IFMIF

The high-flux test module (HFTM) of the International Fusion Materials Irradiation Facility IFMIF will be exposed to an intense flux of neutrons with energies of up to approximately 55 MeV. The threshold of tritium-producing reactions in HFTM and the specimen materials is typically between 10 and 20 MeV, therefore the assessment of the tritium inventory becomes important for the handling of the specimen cells and specimens after the irradiation cycle. In this work, we calculate the tritium production in the specimen cells by neutrons with the McDeLicious code and activation nuclear data from the libraries EAF-2007 and IEAF-2007. The results differ by roughly a factor of two. We discuss ambiguities in the relevant activation data and conclude that better experimental verification of cross sections of isotopes most important for the tritium production in the test cells is desirable.

Validation of differential cross sections by means of 252 Cf spectral averaged cross sections

The results of systematic evaluations of the spectrum-averaged cross section measurements performed in the spontaneous fission 252Cf neutron field are presented. The Following threshold reactions were investigated: 23Na(n,2n)22Na, 54Fe(n,p)54Mn, 54Fe(n,α) 51Cr, 27Al(n,p)27Mg, 27Al(n,α)24Na, 19F(n,2n)18F, 90Zr(n,2n)89Zr and 89Y(n,2n)88Y. The spectrum-averaged cross sections for 23Na(n,2n)22Na, 54Fe(n,α)51Cr and 89Y(n,2n)88Y reactions were measured for the first time. This quantity is compared with calculations carried with the IRDFF-v1.05 library. There is a notable disagreement exceeding uncertainties only for 54Fe(n,p)54Mn and 54Fe(n,α) 51Cr reactions. The spectrum-averaged cross sections were inferred from experimentally determined reaction rates. The experimental reaction rates were derived for irradiated samples from the Net Peak Areas measured using the semiconductor high purity germanium spectroscopy. The presented experimental data can be used to validate nuclear data libraries and reactions used in the practical reactor dosimetry and to specify high energy tail of the 252Cf neutron spectrum.