Towards an uncertainty quantification methodology with CASMO-5

We present the development of an uncertainty quantification (UQ) methodology for the CASMO-5 lattice physics code, used extensively at the Paul Scherrer Institut for standalone neutronics calculations, as well as the generation of nuclear fuel segment libraries for the downstream core simulator, SIMULATE-3. We focus here on propagation of nuclear data uncertainties and describe the framework required for 'black box' UQ--in this case minor modifications of the code are necessary to allow perturbation of the CASMO-5 nuclear data library. We then implement a basic rst-order UQ method, direct perturbation, which directly produces sensitivity coefficients and when folded with the input nuclear data variance-covariance matrix (VCM) yields output uncertainties in the form of an output VCM. We discuss the implementation, including how to map the VCMs of a different group structure to the code library group structure (in our case the ENDF/B-VII-based 586-group library in CASMO-5), present some results for pin cell calculations, and conclude with future work. (author)