ZZ BARC-27GRP, 27-Group Infinitely Dilute and Bondarenko Cross-Section Library from ENDF/B

1 - Description of problem or function: - BARC-27GRP: Format: 1-DX; Number of groups: 27; Nuclides: U-235, U-238, Pu-239, Pu-240, Pu-241, C, O, H, Al, Si, Na, Mg, Cr, Fe, Ni, Mo; Origin: ENDF/B-IV; Weighting spectrum: flux weighting proportional to 1/ΣT(u); fission weighting plus 1/E spectrum. - BARC-35-A: Format: SPHINX, Fx2-TH; Number of groups: 35; Nuclides: Al, He, Si, H, Fe, O, C, Na, Li, B, Be, N, Ca, Mn, V, Mo, Pb, Pu, Gd, K, Sm, Dy, Lu, Nb, U, Cr, Ni, Th, Np, Am, Zr, Cd, Eu, Mg, Ta, Cm, F, Ti, W. Origin: ENDF/B-IV; Weighting spectrum: fission - 1/E - thermal Maxwellian. - IAEA0856/01: 27-group resonance self-shielding factors and infinite diluted Cross sections for U-235, U-238, Pu-239, Pu-240, Pu-241, C, O, H, Al, Si, Na, Mg, Cr, Fe, Ni, Mo, generated by using the basic cross section and resonance parameter data from the ENDF/B-4 library. 2 - Method of solution: The 27-group constants were obtained by integrating the microscopic data over group intervals using a flux weighting proportional to 1/ΣT(u) and a fission plus 1/E spectrum. The standard ABBN group structure is used. The self-shielding factors were calculated for the following temperatures: 300, 900, 2100 (degrees Kelvin) and for potential scattering Cross sections of 10000, 100, 10, 1 barns. A thermal group is also included. For the 35-group library, resonance self-shielding factors are given at 300, 900, and 2100 K for a variety of dilution constants. Group Cross sections cover the energy range from 15 MeV to 0.005 eV and have been derived using Bondarenko flux approximation with a fission-1/E-thermal Maxwellian spectrum. The scattering Cross sections have been represented by a P3 Legendre expansion