Fourth DONES Users Workshop

Enlarging the Perspectives of IFMIF-DONES by Neutronics Qualification of Functional Materials for the Breeding Blankets and Fusion Reactors

14 oct 2026, 14:55

25m

Main Auditorium (CIEMAT)

Studies of functional materials and other fusion technologies

Ponente

Dr. Arkady Serikov (Karlsruhe Institute of Technology (KIT))

Descripción

Responding to the growing interest from the DONES users community, this work provides a comparative neutronics assessment of key diagnostic and control components to address the critical needs of future facilities. While structural materials often dominate radiation damage discussions, functional components face unique operational limits under intense neutron fields. This paper addresses the specific challenge of evaluating these neutronics responses in a power-plant environment and maps those requirements directly to the experimental volumes and irradiation conditions provided by the IFMIF-DONES facility.

To provide a comprehensive neutronics evaluation, this study defines and analyzes key categories of functional materials:

• Tritium breeding and Neutron multiplication materials, analyzing
  advanced ceramic breeder (ACB) pebbles (lithium orthosilicate with 35
  mol% lithium metatitanate) and Li8PbO6​ octalithium plumbate,
  alongside neutron multipliers, including TiBe12​ in the Helium-Cooled
  Pebble Bed (HCPB) and the stagnant liquid lead of the Water-Cooled
  Lead-Lithium Ceramic Breeder (WLCB) blanket concepts;
• Electrical Insulators, specifically investigating MgO and Al2​O3​;
• LTS and HTS superconducting coil materials: Nb3Sn, REBCO, stabilizer matrix;
• Optical Elements, incorporating irradiation studies of chemical vapor deposition (CVD) diamond windows and fiber optic cables.

Comprehensive radiation transport and activation calculations were performed for both MgO and Al2​O3​ to evaluate their suitability in intense neutron fields. The simulations characterize the specific spatial distribution of neutron flux and fluence, nuclear heating, and neutron damage (dpa), directly comparing the irradiation conditions within the DONES High Flux Test Module (HFTM) and Medium Flux Test Module (MFTM) against the expected exposure at the DEMO First Wall (FW). Furthermore, the long-term activation behavior, decay heat profiles, and specific transmutation pathways—such as the generation of sodium (Na) isotopes—were systematically analyzed.

Neutrons degrade superconductors through lattice displacement (reducing critical temperature and critical field​) and resistivity spikes in the copper stabilizer matrix due to transmutations. We analyzed the Low-Temperature Superconductor (LTS) Niobium-Tin material (Nb3​Sn) defined in ITER, DEMO/VNS, and the High-Temperature Superconductor (HTS) Rare-Earth Barium Copper Oxide (REBCO) materials used in SPARC, ARC, Proxima Fusion (Stellaris concept), and Gauss-Fusion (GIGA plant). To quantify and predict resistivity spikes in the stabilizer matrix made of highly pure copper surrounding the superconductor, we calculated neutron fluence, neutron damage, and nuclear transmutation. We applied the MCNP6.2 and McDeLicious-17 radiation transport and FISPACT-II inventory codes and the actual MCNP neutronics models of DONES. The materials are irradiated by the neutron spectra of HFTM and the MFTM versions, such as the In-Situ Ceramic Breeder Irradiation Module (ICBIM) and BLanket fUnctional Materials modulE (BLUME).

Special emphasis is placed on identifying how closely the high-energy deuteron-lithium neutron spectrum can emulate the specific degradation mechanisms—such as Radiation-Induced Conductivity (RIC) in ceramic insulators and transmission loss in optical diagnostics — expected in a commercial fusion environment. Ultimately, this work quantifies the capabilities of IFMIF-DONES to accelerate the qualification of essential functional technologies, providing the fusion community with the predictive data necessary for robust engineering design finalization of breeding blankets and auxiliary systems.