Activation analysis for the plasma facing component of ITER divertor

A three-dimensional activation analysis for the divertor of the International Thermonuclear Experimental Reactor (ITER) design has been performed. Results of the activation analysis are needed for the environmental and safety assessment of ITER. The activation characteristics are dependent on the materials used as well as the operational scenarios assumed for the machine. To examine the effect of pulsing sequences on the decay heat generation, the calculations were performed for two different operational scenarios that were suggested by the ITER Joint Central Team (JCT). The first scenario corresponds to a total fluence of 0.3 MW.a/m² with a long term availability of 25% and a final month availability of 50%. A pulse length of 1 hour is used for this scenario. The second scenario corresponds to a total fluence of 0.12 MW.a/m² with a long term availability of only 4% and a last month availability of 50%. A 1000 second burn pulse length is used for this scenario. Results of the activation analysis showed that the activity and decay heat generated are dominated by ¹⁸⁷ W during the first day after shutdown, the activity and decay heat generated are dominated by impurities present in tungsten. Accurate calculation of the ¹⁸⁷W inventory mandate taking account of the resonance shielding effects by using effective self-shielded cross sections