JENDL-5.0 nuclear data sensitivity, uncertainty, and similarity analyses on the criticality of RSG GAS multipurpose research reactor

•JENDL-5 criticality, S/U, and similarity analysis for RSG GAS first criticality.•Sensitivity coefficients generated by the KSEN option of MCNP6.2.•JENDL-5 new covariance matrices generated by AMPX-6 and keff uncertainty evaluated by TSUNAMI-IP.•JENDL-5 keff uncertainty around 620 to 644 ppm.•No criticality experiment with strong correlation (>0.9). The criticality, sensitivity, uncertainty and similarity analysis of the clean, first core of the G. A. Siwabessy Multipurpose Reactor (RSG GAS), using the newly released Japanese Nuclear Data Library version 5 (JENDL-5) was conducted to contribute the validation effort of the JENDL-5, especially for the application on beryllium reflected, light-water moderated, low-enriched uranium (19.75 wt%) fueled material testing reactors. The JENDL-5 sensitivity coefficients and covariance matrices were prepared by MCNP6 and AMPX-6, respectively. The keff uncertainty was then evaluated with TSUNAMI-IP module of SCALE-6. The same module was used for similarity analysis by comparing the sensitivity data of 3,690 criticality experiments. The criticality (keff) analysis results ([C/E-1]) showed maximum overestimation of 801 pcm, 477 pcm and 547 pcm, for JENDL-5, JENDL-4.0 and ENDF/B-VIII.0, respectively. The keff uncertainty originated from the nuclear data was estimated to be 620 pcm, 644 pcm and 637 pcm for JENDL-5 only, JENDL-5 & ENDF/B-VIII.0, and ENDF/B-VIII.0 covariance data, respectively, which are comparable with the keff ([C/E-1]) values. About 125 experiment cases were found to have correlation factors of > 0.8, however, no experiment showed a strong correlation factor (>0.9), therefore, in the future criticality experiments similar to the RSG GAS should be conducted.