The IFMIF-DONES Irradiation Modules consist of a set of systems designed to be tested in the IFMIF-DONES facility and which are thought to produce, in the future, an extensive, qualified and unique set of fusion-like irradiated experimental data associated to the materials and the structures to be used in specific breeding blankets that are currently under consideration for the EU DEMO fusion reactor. The irradiation conditions (neutron fluence and spectra) at the position of the IFMIF-DONES Irradiation Modules inside the Test Cell, will be comparable to that expected as reference in the most exposed zones of the EU DEMO reactor. Nevertheless, medium and low flux regions will be also available. In this work, an introduction to the description of the main IFMIF-DONES Irradiation Modules is given. Particularly, the following 5 modules are described: the (IFMIF-DONES) High Flux Test Module, HFTM, tailored to powerful irradiate structural materials such as small specimens of Eurofer, the (IFMIF-DONES) Start-up Monitoring Module, STUMM, designed to monitor the radiation fields produced just behind the neutron source, under transient and steady state conditions, the (IFMIF-DONES) Blanket Functional Material Module, BLUME, which is a representative section of the Helium Cooled Pebble Bed (HCPB) blanket breeder zone, the (IFMIF-DONES) Liquid Breeder Validation Module, LBVM, for the irradiation of functional materials such as PbLi and anti-corrosion/anti-permeation barriers, and the (IFMIF-DONES) Tritium Release Test Module, TRTM, which is defined for the irradiation of lithium ceramic pebble beds associated to the HCBP Breeding Blanket.

The IFMIF-DONES Test Systems (TS) gather the experimental facilities offered by the plant, as well as the ancillary systems providing supplies and services both to those facilities and the irradiation modules, the latter ones belonging to the TS, although being excluded from the scope of this article. The irradiation modules gather any system that will be irradiated behind the lithium target inside the Test Cell (TC). Therefore, the Test Cell also houses the liquid Li target and the stripping reaction held between the latter and the D+ beam. The Test Cell is described in section 2, addressing as well some detail (section 2.1) about transversal key aspects like safety, RAMI, maintenance and others, although the safety aspects are collected in a dedicated part (section 5). The vacuum vessel is described in sections 2.2.1 and 2.2.3, relevant outputs from seismic, thermo-structural and fluido-dynamics analyses being as well provided. The shielding blocks are described in section 2.2.2, the lining part covering the building cavity filled in section 2.2.4, the floor in section 2.2.5, and the uppermost part in section 2.2.6. Section 3 is fully dedicated to the Test Systems Ancillaries, a summary description being included for each of thesubsystems, as well as an overview of their functional requirements. Section 4 provides a functional description of the different facilities for complementary experiments, apart from the TC. Section 5 is focused on safety issues applicable not only to the TC but to all the test systems included in the present article. Next, the current guidelines are given for the alignment (section 6) of the in-vessel systems and the integrated commissioning inside the TC (section 7). Finally, section 8 collects the main conclusions about the current status of the design of the Test Systems, irradiation modules excluded.

The key system to know the neutron and gamma fields during the commissioning at IFMIF-DONES facility will be the STart-Up Monitoring Module (STUMM), which will include tens of very sophisticated and miniaturised detectors providing crucial information about the radiation fields. In particular, there will be MFCs (micro-fission chambers), ICs (Ionisation Chambers), SPNDs (Self-Powered Neutron Devices) and GTs (Gamma Thermometers). The current state-of-the-art does not provide answers about the performance of the detectors in the very specific working conditions inside the IFMIF-DONES Test Cell, as a very high spatial density of detectors inside the STUMM vessel, an extremely harsh environment with neutron flux up to 5·10¹⁴n/cm²/s and the need of long mineral cables (>30 m) to drive the very weak current signals from the irradiation area to the closest electronics cubicles available in the facility. Except for the extremely high neutron flux provided by IFMIF-DONES, all the other very critical conditions can be replicated by means of a 1:1 scaled prototype of the STUMM (STUMM-PROTO), which will be subjected to comprehensive testing and irradiation campaigns in order to increase the knowledge about the performance of the detectors above mentioned. The present work shows the wide range of capabilities offered by STUMM-PROTO as well as the current status of its construction and some first notions about the experimental campaigns to be implemented.

The IFMIF-DONES (International Fusion Materials Irradiation Facility – DEMO Oriented Neutron Source), under construction in Granada, Spain, will serve as a neutron source to irradiate materials and critical technologies for fusion power plants. It will produce prototypical fusion neutron fluxes capable of generating damage similar to that expected in future fusion reactors. This work presents the evaluation of a current-mode micro-ionization chamber (μIC) tested under the pulsed radiation environment of the Linear IFMIF Prototype Accelerator (LIPAc) in Rokkasho, Japan. The μIC, developed for integration into the STUMM (Start-Up Monitoring Module) of IFMIF-DONES, is designed to measure gamma radiation as part of the STUMM’s overall neutron and gamma field characterization during commissioning. The experiments focused on assessing the performance of the μIC under radiation conditions simulating IFMIF-DONES operational scenarios. Positioned in the LIPAc High Energy Beam Transport (HEBT) line near the Beam Dump, the current-mode μIC demonstrated its capability to detect pulsed gamma irradiation.

Various models of ionization and fission chambers for ionizing radiation detection, designed to operate under harsh conditions such as those found in fusion reactors or particle accelerators, have been experimentally characterized and numerically simulated. These models were calibrated using a photon beam in the X-ray spectrum. Irradiations were performed at the Biomedical Research Center of the University of Granada (CIBM) with a bipolar metal-ceramic X-ray tube operating at a voltage of 150 kV and a dose rate ranging from 0.05 to 2.28 Gy/min. All detectors under study featured identical external structures but varied in detection volume, anode configuration, and filling gas composition. To assess inter- and intra-model response variations, the tested models included 12 micro-ionization chambers (CRGR10/C5B/UG2), 3 micro-fission chambers (CFUR43/C5B-U5/UG2), 8 micro-fission chambers (CFUR43/C5B-U8/UG2), and 3 micro-fission chambers (CFUR44/C5B-U8/UG2), all manufactured by Photonis (Merignac, France). The experimental setup was considered suitable for the tests, as the leakage current was below 20 pA. The optimal operating voltage range was determined to be 130–150 V, and the photon sensitivities for the chambers were measured as 29.8 ± 0.3 pA/(Gy/h), 43.0 ± 0.8 pA/(Gy/h), 39.2 ± 0.3 pA/(Gy/h), and 96.0 ± 0.9 pA/(Gy/h), respectively. Monte Carlo numerical simulations revealed that the U layer in the fission chambers was primarily responsible for their higher sensitivities due to photoelectric photon absorption. Additionally, the simulations explained the observed differences in sensitivity based on the filling gas pressure. The detectors demonstrated linear responses to dose rates and high reproducibility, making them reliable tools for accurate determination of ionizing photon beams across a range of applications.