Pulsed activation of structural materials in IFE chambers

First structural wall (FSW) materials in inertial fusion energy (IFE) power reactors will be irradiated under typical repetition rates of 1–10 Hz and operation times as long as the total reactor lifetime. The main objective of the present work is to determine whether or not a continuous-pulsed (CP) approach could be an accurate and practical methodology in modeling the pulsed activation process for operating conditions of FSW materials. To do that, we assess the applicability of the CP model to predict the neutron-induced activation in the FSW material of the HYLIFE-II reactor. It is demonstrated that a CP approach consisting of a continuous irradiation period followed by a series of only a few pulses prior to shutdown can efficiently model the real pulsed operating regime of the FSW material, in terms of both accuracy and CPU time consumption. Pros and cons of the model when compared with an equivalent steady-state (ESS) method are discussed, which is useful to assess how conclusions of earlier activation studies that used the ESS approach might be different when using a more realistic model. Comparison with the exact pulsed (EP) modeling is also performed. Finally, application of the CP model to other inertial confinement fusion operating modes, such as that of the NIF facility, is suggested for future work.