Failure Mode Analysis and Residual Life Assessment of Prefabricated Target Neutron Tubes

The failure mechanism as well as the life prediction of neutron tubes have attracted much attention for the wide application of neutron tubes in many domains. In this paper, the failure modes of prefabricated deuterium-tritium neutron tubes were firstly studied. Degradation models considering the time-varying uncertainties, individual differences and measurement uncertainties were used to investigate the random degradation process of neutron tubes. Life tests of neutron tubes were conducted at room temperature and $175^{\circ} \mathrm{C}$ in laboratory. A logarithmic form function was proposed to describe the nonlinear degradation characteristics of neutron tubes. Recursive parameter estimation was performed using the expectation maximization algorithm and the genetic algorithm. Finally, the residual life distribution of each neutron tube was obtained by the proposed models and estimated parameters. The results showed that the nonlinear degradation process modelling and residual life assessment method could be applicable for the stable operation period of prefabricated neutron tubes when the neutron yield decreases continuously.