An overview of the US work to complete the design of Blanket Shield Modules 7,12 and 13 for the ITER project

Part of the US contribution to the ITER project is Blanket Shield Modules (BSM) number 7, 12 and 13 comprising about 20% of the ITER First Wall. These modules are all in the upper half of the vacuum vessel. Starting from outlines of each style of module, general design rules contained in the ITER Design Description Document (DDD), design memos, and CATIA interface drawings, the US Team has worked to fill in the details of the internal water cooling passages, slits to control eddy currents, and methods for efficient and reliable manufacturing of the BSM. Our analysis begins with nuclear heating assessment of complex 3D structures containing water, copper, and steel carried out by the University of Wisconsin using a version of Monte Carlo N-Particle Transport Code (MCNP) that connects directly to CATIA to get the geometry. Computational Fluid Dynamics (CFD) analysis of the coolant flow distribution and pressure drop in a shield module provides the basis for thermal transfer from the BSM to the coolant. The size and position of coolant passages are adjusted to optimize the heat transfer and eliminate hot spots. ITER specified major disruption (MD) and downward vertical disruption (VDE) events are used to calculate the currents induced in the BSM. In this modeling it is necessary to include the vacuum vessel and other BSM near the modules of interest. In order to benchmark the OPERA Electromagnetic Code against the one used for the DDD analysis, we calculated eddy currents and forces on all 18 BSM in a simplified model that matched analysis by Japan. The eddy current forces are used to determine the torque and net force on the BSM. These forces are compared to the load capacity of the mounts and adjustments made to eddy current control slits as needed. Dynamic analysis of the eddy current induced stresses on the BSM and mounts are performed using the ABAQUS code. Static thermal and pressure stresses are calculated using the temperature distributions from CFD analysis. The primary and secondary stresses are compared to the allowables specified in the ITER Structural Design Criteria to determine the suitability of the design to the ITER needs. Manufacturing processes are being created through a series of mockups and prototypes of sub-scale parts. This paper describes the results of these analyses that have led to a Preliminary Design for the US contribution of BSM. (orig.)