Ponente
Descripción
Neutron energy spectra collimated by the Neutron Beam Tube and Shutter (NBT&S) at the entrance to the Complementary Experiments Room (CER) R160 are presented in this work, with particular investigation of the impact caused to neutron spectra by the materials of the High Flux Test Module (HFTM) and Other Irradiation Modules (OIMs). At KIT we develop two OIMs: BLUME (BLanket fUnctional Materials modulE) and TRTM (Tritium Release Test Module), which could be installed behind HFTM as the Medium Flux Test Modules (MFTMs). The BLUME and TRTM modules are envisaged for testing, validation, and qualification of functional materials for the EU DEMO Helium-Cooled Pebble Bed (HCPB) breeding blanket. This work updates the neutronics analyses presented at the Second DONES Users Workshop [1], now concentrated on the neutronics impact on collimated neutron spectra in CER caused by a series of design parametrizations of BLUME and design updates of the NBT&S system that IPPLM and NCBJ carried out in 2023-2024. One of the important tasks at DONES is to plan the scenario of installation & removal of the Test Modules synchronized with the operation & maintenance of other systems at DONES, such as Target Assembly, Test Cell components, and Accelerator Systems.
This work demonstrates that planning the neutron experiments inside CER depends on the number and design configuration of the Test Modules installed in the DONES Test Cell. The synergy effect for the DONES neutron irradiation campaign is related to the efficient use of neutrons, supplying neutrons to multiple DONES users, and allowing them to work together. That synergy effect was investigated by assessing the collimated neutron spectra inside the CER formed by neutron interactions with the HFTM and MFTM test modules inside the DONES Test Cell (TC). Depending on the configurations of the TC test modules, various neutron spectra are formed in CER, and corresponding neutron experiments could be chosen. As a result, no neutrons will be wasted. The neutron spectra in CER with full-size HCPB OIMs have been reported in [1]. By installation of the full-size OIM MFTM modules, the energy-integrated neutron flux at the entrance to CER was reduced by 100 times due to the presence of TRTM and by 286 times due to BLUME [1]. Such a strong reduction of the neutron loads at the CER entrance motivated us to find the OIM MFTM configurations with minimal radiation attenuation. The minimization was performed by removing the possibly excessive OIM components such as the Neutron Spectral Shifter (NSS), back-side reflector, tungsten armor, First Wall, and blanket cooling manifold. The least possible OIMs impact was found in the TRTM version without NSS and back-side graphite reflector. Installation of the cut version of TRTM caused total neutron flux reduction by 2.6 times from 2.1e10 n/cm^2/s (entrance to CER without MFTM in TC) to 8.0e9 n/cm^2/s (cut version of TRTM). Even in the minimal configuration of BLUME, the total flux is reduced by 175 times from 2.1e10 to 1.2e8 n/cm^2/s. Therefore, the impact of OIMs on collimated neutrons entering CER is still strong and requires further work.
References:
[1] A. Serikov et al., “Impact of installation of the Tritium Release Test Module in the IFMIF-DONES Test Cell on the neutron spectra inside the Complementary Experiments Room collimated by Neutron Beam Tube and Shutter”, Second DONES Users Workshop, October 19-20, 2023, Parque de las Ciencias, Granada, Spain, https://indico.ifmif-dones.es/event/4/contributions/326/
