Sensitivity and uncertainty analysis of the first core of the DNRR using MCNP6 and new nuclear data libraries

Abstract

This paper presents the sensitivity and uncertainty analysis for the Dalat Nuclear Research Reactor (DNRR) using MCNP6.2 and several data libraries such as ENDF/B-VII.1, ENDF/B-VIII.0, JENDL-4.0 and JENDL-5. Calculations have been performed for the first DNRR core with 88 highly enriched uranium fuel bundles. The effect of the new data libraries on the criticality analysis of the DNRR core has been analyzed based on 24 criticality conditions in comparison with the measurement. The largest discrepancies of the effective multiplication factor, keff, obtained with the four data libraries are −271, −297, −258 and −157 pcm, respectively, compared to the experiments. The values obtained with JENDL-5 are greater than that obtained with the other libraries by about 100 pcm in most cases. The nuclides with the major contributions to the positive sensitivities are U-235, H-1, C-12, Be-9, Al-27 and O-16. Whereas, the most negative sensitivity coefficients are found with the capture reactions of H-1, U-235, Al-27, U-238, B-10, Be-9, Fe-56, O-16 and C-12, and the alpha production of B-10. The highest uncertainties are obtained with the capture and elastic scattering of H-1, and the capture and fission of U-235. Subsequently, Al-27, O-16, Be-9, C-12, Fe-56,and U-238 have remarkable contribution to the uncertainty of the keff. The total uncertainties obtained with the four data libraries are 534.9, 466.6, 429.5 and 379.1 pcm, respectively.