Evaluation of tritium release curve in primary coolant of research reactors

Abstract

Increase of tritium concentration in the primary coolant for the research and testing reactors during reactor
operation had been reported. To clarify the tritium sources, a curve of the tritium release rate into the primary
coolant for the JMTR and the JRR-3M are evaluated. It is also observed that the amount of released tritium is
lower in the case of new beryllium components installation, and increases with the reactor operating cycle.
These results show the beryllium components in core strongly affect to the tritium release into the primary
coolant. As a result, the tritium release rate is related with produced 6Li by (n,α) reaction from 9Be, and
evaluation results of tritium release curve are shown as the dominant source of tritium release into the primary
coolant for the JMTR and the JRR-3M are beryllium components. Scattering of the tritium release rate with
irradiation time were observed, and this phenomena in the JMTR occurred in earlier time than that of the JRR-
3M.