Measurement of the 23Na(n,2n) cross section in 235U and 252Cf fission neutron spectra

The presented paper aims to compare the calculated and experimental reaction rates of 23 Na(n,2n) 22 Na in a well-defined reactor spectra and in the spontaneous fission spectrum of 252 Cf. The experimentally determined reaction rate, derived using gamma spectroscopy of irradiated NaF sample, is used for average cross section determination.Estimation of this cross-section is important as it is included in International Reactor Dosimetry and Fusion File and is also relevant to the correct estimation of long-term activity of Na coolant in Sodium Fast Reactors. The calculations were performed with the MCNP6 code using ENDF/B-VII.0, JEFF-3.1, JEFF-3.2, JENDL-3.3, JENDL-4, ROSFOND-2010, CENDL-3.1 and IRDFF nuclear data libraries. In the case of reactor spectrum, reasonable agreement was not achieved with any library. However, in the case of 252 Cf spectrum agreement was achieved with IRDFF, JEFF-3.1 and JENDL libraries.