SAMS: A sensitivity analysis module for criticality safety analysis using Monte Carlo techniques

The SAMS module has been developed to calculate the relative change in the value ofk_eff due to a change in a constituent component or cross section. The SAMS module works in conjunction with a modified version of the CSAS25 sequence of SCALE that employs an enhanced version of KENO V.a, which is capable of calculating the spherical harmonics components of the flux moments. The SAMS module performs sensitivity calculations using linear perturbation theory as implemented in the FORSS system and requires the calculation of the forward andadjoint flux moments with the enhanced version of KENOV.a. SAMS automatically selects all of the sensitivity parameters that can be calculated for each nuclide in each region of the system based on available cross-section data. Sensitivity parameters for a given nuclide may be generated for a number of parameters, including total, scatter, capture, and fission cross sections, as well as ν and χ. The sensitivities for any nuclide-reaction pair calculated with SAMS can be output on three bases: group-wise region dependent, energy-integrated region dependent, and energy- and region-integrated. The sensitivities generated with SAMS have been verified through comparisons with those generated with the SEN1 and SEN2 sensitivity sequences of SCALE. SAMS is capable of producing accurate sensitivities, provided the KENO V.a regions have been appropriately subdivided to allow for sufficient resolution of the flux moments throughout the problem geometry.