Comprehensive Second-Order Adjoint Sensitivity Analysis Methodology (2nd-ASAM) Applied to a Subcritical Experimental Reactor Physics Benchmark

The Second-Order Adjoint Sensitivity Analysis Methodology (2nd-ASAM) developed by Cacuci has been applied to compute deterministically the exact values of the 1st-order and 2nd-order sensitivities of the leakage response of a polyethylene-reflected plutonium (PoRP) experimental benchmark to the nuclear data characterizing this benchmark. The imprecisely known parameters underlying the nuclear data used in the neutron transport computational model for this benchmark include 180 group-averaged total microscopic cross sections, 21600 group-averaged scattering microscopic cross sections, 120 parameters describing the fission process, 60 parameters describing the fission spectrum, 10 parameters describing the system’s sources, and 6 isotopic number densities. Thus, this benchmark comprises 21976 first-order sensitivities of the leakage response with respect to the model parameters, and 482,944,576 second-order sensitivities. Computing these sensitivities exactly represents the largest sensitivity analysis endeavor ever attempted in reactor physics, and probably in any field, as well. Due to the symmetry of the 2nd-order sensitivities, only 241,483,276 are distinct from each other, and some of these turned out to be zero.<br><b>Related publications:</b><br> Cacuci, D. G.; Fang, R.; Favorite, J. A. Application of the Second-Order Comprehensive Adjoint Sensitivity Analysis Methodology (2nd-CASAM) to a Subcritical Experimental Benchmark: I. Computation of Response Sensitivities and Uncertainties Stemming from Imprecisely Known Total Cross Sections, Energies, (under review).<br> Fang, R.; Cacuci, D. G. Application of the Second-Order Comprehensive Adjoint Sensitivity Analysis Methodology (2nd-CASAM) to a Subcritical Experimental Benchmark: II. Computation of Response Sensitivities and Uncertainties Stemming from Imprecisely Known Scattering Cross Sections, Energies, (under review).<br> Cacuci, D. G.; Fang, R.; Favorite, J. A.; Badea M.C.; Rocco, F. Di. Application of the Second-Order Comprehensive Adjoint Sensitivity Analysis Methodology (2nd-CASAM) to a Subcritical Experimental Benchmark: III. Computation of Response Sensitivities and Uncertainties Stemming from Imprecisely Known Fission Cross Sections and Average Number of Neutrons per Fission, Energies, (under review). <br> <i>Note: </i> All data files are in EXCEL format. See the file named “description_of_files” for detailed information of the file contents, and their relationship with the above publications.<br>