Sensitivity of R2Smesh shutdown dose rate results on the mesh resolution

Abstract

R2Smesh is a computational interface linking the Monte Carlo code MCNP and inventory code FISPACT for accurate shutdown dose rate (SDDR) analysis in fusion reactor. The superimposed mesh tally in MCNP has been introduced in its development effort for calculation of neutron flux and multi-group spectra. The resulting neutron flux is averaged within each mesh element as its gradient is omitted. The accuracy of final SDDR thus relies heavily on mesh resolution. To evaluate the influence of mesh resolution on SDDR, the sensitivity analysis has been conducted on JET and EU DEMO by using series of mesh with different voxel size. The convergence of SDDR was achieved and the optimum size of mesh voxel for JET and DEMO SDDR calculation were determined after compromising between the precision of result and high computational cost. By employing the optimum mesh resolution, the R2Smesh interface was validated through comparison with JET measurements. Afterwards it was applied on DEMO for global SDDR analysis to provide support for neutron and gamma induced shielding design.