Assessment of MICROX-2 Code with New ENDF/B-VII Release 0 Master Libraries

A lattice code, MICROX-2, was assessed for its neutronics calculation performance with new cross-section libraries. First, the new cross-section libraries were generated based on ENDF/B-VII release 0. A total of 386 nuclides were processed, including 10 thermal scattering nuclides. The updated NJOY system and MICROR code were used to process nuclear data and convert them into the MICROX-2 library format. The energy group structure of the new library was optimized for both the thermal and fast neutron spectrum systems based on the Contributon and Pointwise Cross Section Driven (CPXSD) method, resulting in a total of 1173 energy groups. Second, a series of pin-cell–level benchmark calculations was performed against experimental measurements and numerical calculations performed by the deterministic and Monte Carlo codes for multiplication factors and reaction rate ratios. Both the homogeneous and heterogeneous pin-cell calculations were conducted for 15 cases. The results of MICROX-2 calculations show good agreement with the reference values. The arithmetic average errors of k_∞ for the homogeneous and heterogeneous lattices are 0.30% and 0.44%, respectively. For the finite lattices (five cases for water reactor fuels), the average error of k_eff is 0.32%. These errors are due to the combined effect of the solution method and the cross-section library. Especially for the fast reactor cases, the prediction of the physics parameter by MICROX-2 deteriorates when the fuel volume increases, which is mostly due to the simplified resonance self-shielding model.