Abstract
In this study, the sodium radioactivity of 24Na and 22Na in the primary system measured in the prototype fast breeder reactor Monju was evaluated, and the reliability of the measurements and calculations was examined. The calculated-to-experiment values and their uncertainties for 24Na and 22Na radioactivities were 0.97 to 1.07 and 8.1% to 11.0% and 1.03 to 1.16 and 23.3% to 24.1%, respectively, using the JENDL-4.0 nuclear data library. The 22Na radioactivity calculated with ENDF/B-VIII.0 was larger by 40% than those calculated with JENDL-4.0 and JEFF-3.3 due to the 23Na(n,2n) cross-section discrepancy. The importance of the 22Na neutron capture effect is also confirmed herein for the accurate evaluation of the 22Na radioactivity. The experimental data were judged to be useful for validating the calculation method for improving the reliability of future designs of sodium-cooled fast reactors.
Acknowledgments
The authors would like to express their special thanks to the Radiation and Chemistry Management Section in the Monju for providing the measured data, to A. Takegoshi and H. Katagiri of the NESI, Inc., for their help in the calculation, and to the Reactor Core and Plant System Evaluation Group in the JAEA for editing and providing the 22Na cross-section data.
Disclosure Statement
No potential conflict of interest was reported by the authors.