Speaker
Kenzo Ibano
(Graduate School of Engineering)
Description
For the fusion reactor operations, the tritium (T) retention and permeation in the reactor walls are important for points of views of safety and fuel cycle. It is known that T retention in tungsten (W) is less severe compared with carbon (C). However, recent experimental studies revealed that the neutron irradiated damage, surface recrystallization, and fuzz formation by He ion irradiation increases the retention amount. It was also revealed that the T desorption flux strongly depends on the surface temperature because of the difference of potential energy of the T trapping sites. It is expected that desorption occur not only during the plasma operation but also the intervals. Thus, a comprehensive study for the operational scenario should be taken in order to estimate the T retention in a W wall device.
In this study, a T retention model was constructed and integrated into a reactor operation simulation code. In the code, the main plasma was treated in a 0D model and the SOL and divertor plasma was treated in the two-points model or 1D fluid model. For the wall, 1D heat conduction for the depth direction and erosion by sputtering and evaporations were solved for each plasma facing components (PFCs). By taking sequential calculation with the nuclear calculation codes, effects of the nuclear heating and the neutron damage can be included with considerations of the poloidal asymmetry. Based on the experimental data, T retention and desorption amounts are modeled as a function of surface temperature. Using the operation simulation code with the retention model, sensitivities of parameters, plasma operation intervals, design of PFCs, effects of the permeation barrier and neutron damages, for the T retention amount are evaluated.
Co-authors
Heun Tae Lee
(Graduate School of Engineering, Osaka University, Osaka, Japan)
Kenzo Ibano
(Graduate School of Engineering, Osaka University, Osaka, Japan)
Yoshio Ueda
(Graduate School of Engineering, Osaka University, Osaka, Japan)
