Neutron shielding assessment for the Remote Handling Lower Port rack of ITER

A neutron shielding assessment of an integrated ITER C-lite neutronics baseline model for the Remote Handling Lower Port rack and port interspace components has been performed. The aim of this paper is to decrease the neutron leakage as a mean to eventually reduce the activation relevant for shutdown dose rates. The performance of the neutron shielding assembled in the baseline model of the Remote Handling Lower Port rack has been assessed. As a mitigation strategy, neutronics calculations have been conducted to evaluate the radiation field during operation in the lower port with the Remote Handling Lower Port rack and the interspace components installed. A progressive improvement of the neutron shielding has been carried out with additional shielding elements including a large shielding block. As a result, the neutron streaming has been significantly reduced along the lower port with a neutron fluence rate in the closure flange in the range of 1·10⁹ n/cm²s to 1·10⁸ n/cm²s.