Bias Determination for DOE Nuclear Fuels

The purpose of this calculation is to establish the relative change in the effective neutron multiplication factor (keff) due to the use of MCNP unique identifiers (ZAIDs) in Nuclear Criticality Calculations for Canister-Based Facilities - DOE SNF (Reference 2.2.1, Attachment 3, MCNP inputs.zip) that are different to the ZAIDs used in the Analysis of Critical Benchmark Experiments and Critical Limit Calculation for DOE SNF (Reference 2.2.5, Table 5-3). This calculation determines the penalty (ΔkEROA), if any, on the applicability of the validation documented in Analysis of Critical Benchmark Experiments and Critical Limit Calculation for DOE SNF (Reference 2.2.5, Section 6.3) to the selected preclosure configurations described in Section 1.1, which have, in some instances, used different ZAIDs.
The MCNP ZAIDs refer to a specific nuclear data library of an element or isotope. The ZAID labels are based on the atomic number (Z), mass number (A), and data library specifier of the element or isotope of interest. Differences between the ZAIDs modeled in Nuclear Criticality Calculations for Canister-Based Facilities - DOE SNF (Reference 2.2.1, Attachment 3, MCNP inputs.zip) and those modeled in the Analysis of Critical Benchmark Experiments and Critical Limit Calculation for DOE SNF (Reference 2.2.5, Table 5-3) exist because of isotopic representation as opposed to elemental representation. Additional differences exist due to the use of different nuclear data libraries.