Activation of structural materials is an important design consideration for an experimental power reactor such as ITER. Several activation calculations have been performed based on one and two-dimensional models [1,2]. Two-dimensional model analysis is generally a better approach than the 1-d model because (1) the results are accurately normalized to the fusion power, and (2) the poloidal variation is more accurately represented by the 2-d model. The 2-d model reported in Ref. 2 has a double-null divertor configuration and is much simplified. In this paper we report the analysis of the ITER shielding blanket design based on a single-null divertor configuration and more detailed blanket, vacuum vessel, and toroidal field magnet components and geometry.

The 2-d model covers a cylindrical geometry with dimensions of 14 m radially (r-axis) and 16 m axially (z axis). The mid-plane of the plasma is at 9 m above the bottom of the z-axis. All meshes employ uniform squares of 5 cm in both r and z axes. Neutron fluxes were calculated with the 2-d particle transport code system DANT, in P3-S8 approximations. Activation calculations were performed using the activation calculation code REAC*3. The nuclear data libraries employed for both neutron flux and activation calculations are those derived from the Fusion Evaluated Nuclear Data Library (FENDL). The results were normalized to 1500 MW fusion power. The activation calculations were calculated primarily based on the operational scenario of the base performance phase of ITER. The neutronics calculation shows that a total of 1720 MW nuclear heating is deposited in the major components, giving a blanket energy multiplication of 1.43. Of which, about 288 MW is deposited in the first wall (1 cm Be + 2 cm Cu-alloy and SS316 structure), 1345 MW in the blanket, 2.12 MW in the vacuum vessel, 85 MW in the divertor, and 9 kW in the TF magnet. Detailed results of nuclear heating in the segmented blanket modules are also available.

More detailed neutronics and activation analyses will be discussed. Essential results, namely decay heat and induced radioactivity, for the safety analysis and waste management assessment will be presented.

*Work supported by the USDOE/OFES, under Grant No.: DE-FG03-92ER54137.

References:
[1] E.T. Cheng, G. Saji, "Activation Analysis for ITER Safety and Environmental Assessment," ANS Topical Meeting on the Technology of Fusion Energy, June 1996, Reno, Nevada, USA.
[2] E.T. Cheng, et al., "Neutronics and Activation Analysis of a SS316 based Experimental D-T Fusion Power Reactor," Symposium on Fusion Engineering, September 1995, Illinois, USA.