650 SOFOCATE--A CODE TO DETERMINE THERMAL CONSTANTS ON THE IBM-650

Abstract

650 SOFOCATE is aa IBM 650 code to determine the macroscopic thermal cross sections to be used in reactor diffusion and transport codes. These thermal constants are derived by averaging energy dependent cross sections over either a Wigner-Wilkins or a Maxwellian spectrum. As the name implies, the 650 SOFOCATE code is essentially a recoding of the 704 code, SOFOCATE, programmed by Westinghouse. The procedure of obtaining the spectrum, and the averaging of the cross sections over the spectrum follows exactly the procedure outlined in WAPD- TM-39. Restrictions of the 650 version to the 704 code are that the energy limit of the spectrum is reduced from 2.00 to 1.09 ev, and that no provision is made for an energy dependent moderator cross section and logarithmic energy decrement. In addition to the macroscopic cross sections used in diffusion codes, D, SIGMA / sub A/, and nu SIGMA /sub F/, the 650 SOFOCATE generates cross sections used in transport codes, SIGMA /sub TE/ and SIGMA /sub S/. The 650 version allows the user the option of specifying whether the energy dependent macroscopic cross sections, derived from the specified material composition, are to be averaged over either a Wigner-Wilkins spectrum generated from the same composition, or a Maxwellian spectrum, or a Wigner-Wilkins spectrum generated by a different material composition. The latter is useful in determining homogenized cell constants. A description of the code and the equations and procedures used are presented. A description is also given of a procedure for calculating thermal constants for a thin heavily absorbing region. (auth)