Characterisation of Fusion Reactor Materials Using Neutron Transmission and Activation Experiments with 14 MeV Neutron Sources – Materials Strand Project

Supervisors: Patrick Stowell (Lead), Russell Goodall, Christopher Race (University of Sheffield) & Carlo Cazziniga (Rutherford Appleton Laboratory).

Understanding the behavior of reactor components under intense neutron irradiation is
critical for the successful development of fusion energy systems. In particular, 14 MeV
neutrons produced by the deuterium–tritium (D–T) fusion reaction present a unique
challenge. Their high energy results in significantly different material activation,
transmutation, and damage profiles compared to the lower-energy neutrons typical of
fission reactors.

A key challenge in developing fusion-relevant material screening data is the accessibility of
appropriate neutron sources. While research reactors provide high fluxes suitable for many
activation and shielding studies, their spectra are dominated by thermal and epithermal
neutrons and do not reproduce the high-energy 14 MeV peak characteristic of D–T fusion.
This mismatch limits the reliability of transmission measurements and benchmarking for
fusion applications.

In contrast, dedicated desktop D–T neutron generators, such as those available in the STFC NILE facility, offer a well-characterised, monoenergetic 14 MeV source ideally suited for transmission experiments and cross-section validation. Although operating at lower overall fluxes than reactors, these facilities have reached a level of standardisation that means they are capable of generating high-quality benchmark data for shielding design and materials activation in the fusion context.

This project will develop the use of DT neutron sources for analytical purposes, focusing in
particular on the characterization of materials of interest for nuclear fusion engineering.
Case studies will certainly include Tungsten alloys that are first choice for plasma-facing
materials, especially in divertors and first wall (Alloy examples: W-Re, W-Ta, ODS-W). Other materials of interest include reduced-activation steels, used in structural components and vacuum vessels, copper alloys, used in heat sinks and magnet structures, and Lithium containing materials used in tritium breeding blankets. The studies will be carried out using the NILE facility at ISIS and the pulsed source of Sheffield University. The two sources are very different and complementary: the first is a high flux neutron generator, that at the moment of writing offers the highest yield of 14 MeV neutrons in the UK; the second has a low neutron yield, but a very sharp pulse structure, ideal for prompt gamma and detector testing.

Training on neutron generator simulation and operation, radiation detector development,
and design of neutron activation experiments will be included as part of the studentship.

During the first six months of the PhD, materials strand students will typically travel to attend taught modules at all six of the Fusion CDT partner universities.

After the taught programme, the student will primarily be based at Sheffield University
working in the Sheffield neutron facility.

As part of the funding the student will be required to spend up to a year working at
Rutherford Appleton Laboratory supporting facility development, with opportunities for
travel to conferences and collaborations with other groups working on radiation sensing
and material screening methods.

This project is offered by University of Sheffield. For further information please contact: Dr Patrick Stowell (p.stowell@sheffield.ac.uk).

This project may be compatible with part time study, please contact the project supervisors if you are interested in exploring this.

For details on how to apply, please visit: Apply