APPLICATION, SOURCE AND SCOPE OF THE DATA -
ZZ-HILO2k was developed as part of the neutronics R&D effort associated with the design of the Spallation Neutron Source (SNS) currently under construction at ORNL and can be used for other accelerator driven applications. ZZ-HILO2k multigroup cross sections are in the form needed for the CCC-0650/DOORS3.2a (ANISN, DORT and TORT) discrete ordinates codes. In addition to transport cross sections, the new HILO library contains flux-to-dose conversion factors and kermas (nuclear heating response functions) for all energies for all 32 nuclides. It also contains dpa and H-1 and He gas production response functions covering selected energy ranges for some of the nuclides comprising structural materials.
The new library contains transport cross sections for 32 nuclides commonly found in the target, reflector, and shielding materials used at spallation neutron source facilities. The high-energy portion (E>20 MeV) of ZZ-HILO2k is based on neutron elastic and nonelastic interaction and production data generated using the stochastic nuclear collision models in MCNPX Version 2.1.5 (RSICC package CCC-0705). The low-energy portion was derived from ENDF or LENDL data for all nuclides except Hg. The high-energy neutron interaction and production cross sections were also normalized to the nonelastic cross sections for those nuclides treated in the recently evaluated Los Alamos National Laboratory (LANL) 150-MeV library. Dose equivalent obtained from discrete ordinates transport calculations employing HILO2k agreed within approximately a factor of two with that obtained using MCNPX after transport through more than 4000 g/cm2 of typical high-energy shielding materials. Data are provided for: H-1, H-2, He, Be, B-10, B-11, C, N, O, Na, Mg, Al, Si, S, K, Ca, Cr, Mn, Fe, Ni, Cu, Zr, Nb, Cd, Ba, Gd, Ta, W, Hg, Pb, U-235, U-238.
Two versions of the new ZZ-HILO library are distributed. In the standard version, all high energy particle interaction and production data was taken into account to obtain the group total cross section (interaction cross section) and the group-to-group Legendre scattering coefficients (scattering cross sections). In the modified version, neutrons that exited collisions almost straight ahead with more than 95% of the incident neutron energy were treated as uncollided neutrons. Both libraries contain 105 total energy groups (42 high-energy neutron, 41 low-energy neutron, and 22 photon groups). The modified version of the new HILO library contains P-9 Legendre expansions for the scattering cross sections whereas the standard version contains P-10 expansions.