ITER Neutronics Analysis for the Design of Diagnostics and Port Plugs Using ATTILA Discrete Ordinates Software

A collaboration is underway between Princeton Plasma Physics Lab and UCLA to develop skill in the use of ATTILA, to benchmark ATTILA against MCNP and to develop Solid Works CAD models for neutronics analysis of the diagnostic ports. MCNP along with the cross section library FENDL 2.1 is the accepted standard tool for neutronics analysis of ITER against which results from ATTILA are being compared. The MCNP community has established a set of benchmark results for a standardized 40 degree CAD model of ITER. These benchmark results create a framework for the acceptance of new applications like A TTILA by the ITER central neutronics, quality assurance and nuclear safety groups. Analysis of the benchmark model with ATTILA also leads to the setting of discrete ordinates solution parameters and model mesh refinement that will help to accelerate the analysis of future diagnostic port design iterations. Flux and heating results in the Divertor, Blanket Shield Modules and Equatorial Port Shielding from the ATTILA benchmarking show good correlation with MCNP results. TF heating results were in error by up to 50% due to poor mesh refinement and boundary condition issues in that area. Detailed models of the Upper and Equatorial ports, port plugs and diagnostics are under development. The detailed port study models will be 40 degree ITER models to preserve the shape of the neutron source loading. These models will include the inner and outer vacuum vessel, inner-wall shielding, blanket shield modules, divertor and cryostat. Models of the OH, TF and PF coils will not be included to save on element count.