Developing a Finite Element Based Model for Pellet Relocation in Nuclear Reactor Fuel

About the Project

Primary supervisor - Dr Thomas Anthony Haynes

Pellet-clad interaction (PCI) is a complicated phenomenon, relatively poorly captured in current commercial fuel performance codes. Models have been built in the commercial finite element software ‘Abaqus’ to capture pellet clad interaction in both light water reactors (LWRs) and the UK advanced gas cooled reactor (UK-AGR). Whilst Abaqus offers advantages in terms of materials modelling and contact, COMSOL offers the potential to capture a fuller range of physical behaviours. Chiefly, the ability to capture the inertial behaviour of fuel pellet fragments (Abaqus cannot model inertia in a coupled temperature-displacement model) and the ability to model the migration of multiple chemical species. The motion of pellet fragments will be of paramount importance when predicting the behaviour of fuel during LOCAs.

The project will aim to achieve the following:

• A thorough literature review on the state of the art of fuel performance codes with a particular emphasis on PCI.
• Assessment of how COMSOL might be able to capture each of the physical processes important in nuclear fuel performance.
• Benchmarking the model against other fuel performance codes reported in the literature, with a particular emphasis on the ‘mortar’ method in BISON.
• Validation against experimental data and benchmarking against other codes reported in the recent OECD ‘Pellet-Cladding Mechanical Interaction (PCMI) Benchmark’ exercises.
• Based upon the validation exercise, highlight areas of future code development, including routes to modelling postulated idealised loss-of coolant accidents.

The successful candidate will be expected to work closely with Amentum staff and will be required to obtain Baseline Personnel Security Standard (BPSS) National Security Vetting during their PhD, with no impediment to obtaining Counter Terrorist Check (CTC) and/or Security Check (SC) clearance following their PhD.

Entry requirements

The minimum entry requirement is 2:1 in Engineering, Physics, Materials Science.

Mode of study

Full-time

Start date

1 October 2026

Funding Notes

This 3.5-year PhD studentship is fully funded by Amentum. Funding includes tuition fees at the home-fee rate, an annual tax-free stipend starting at £23,805 in 2026/27, plus a substantial research training support grant (RTSG) to cover a laptop and travel to Amentum sites, and conference attendance.