High-Performance Flow Measurement for Fusion Reactor Auxiliary Systems: Physics-Based Optimisation of Differential Pressure Sensors in Extreme Environments

About the Project

Fusion power plants require extensive instrumentation networks to monitor and control safety-critical auxiliary systems, particularly tritium extraction systems (TES), coolant purification systems (CPS), and breeder blanket cooling circuits. These systems operate under extreme conditions—temperatures of 600-873 K, high radiation environments, and corrosive tritium-containing atmospheres—where reliable flow measurement is paramount for operational safety, process control, and tritium accountancy. Multiport averaging pitot-type differential pressure sensors are the preferred technology for these applications due to their simplicity, radiation tolerance, and compatibility with harsh fluids. However, generating sufficient differential pressure signals in challenging flow regimes (low velocities, high temperatures, varying fluid properties) remains a critical design challenge. Current sensor designs often produce inadequate signals in fusion-relevant operating envelopes, forcing either oversized installations or reliance on less robust measurement principles.

The fundamental challenge lies in optimising sensor geometry to maximise differential pressure generation whilst maintaining measurement accuracy and long-term reliability in extreme multi-physics environments. Fusion auxiliary systems present unique measurement demands:

1. helium flows at 773-873 K in tritium extraction circuits where gas density variations affect signal strength,
2. liquid metal (PbLi) coolant systems where high operating temperatures (600-700°C) and magnetohydrodynamic effects complicate conventional flow measurement approaches, and
3. constrained geometries with limited access for maintenance due to radiation activation, necessitating highly reliable 'fit-and-forget' instrumentation.

Inadequate differential pressure generation translates directly to measurement uncertainty, compromising process control and tritium accountancy—both safety-critical functions. Furthermore, the ASME MFC-12M standard governing multiport averaging pitot tubes in closed conduits provides design guidelines optimised for conventional industrial conditions but offers limited guidance for fusion-relevant extreme environments.

Recent advances in high-fidelity CFD, adjoint optimisation methods, and machine learning-based surrogate modelling enable systematic exploration of sensor geometry design spaces to maximise differential pressure output. However, translating computational predictions into validated designs requires careful experimental validation in realistic pipe flow conditions. The University of Liverpool's Very-Large-Scale Pipe Flow (VLSPF) facility provides unique capability for validating probe performance in fully developed turbulent flow (L/D = 233, ReD up to 300,000) that replicates industrial installations. The 100 mm diameter matches typical auxiliary system pipework, whilst the transparent borosilicate glass construction enables simultaneous pressure measurements and optical flow diagnostics. When coupled with high-temperature flow testing capabilities and collaboration with WIKA—a leading instrumentation manufacturer with nuclear sector expertise—this project can deliver sensor designs optimised for fusion auxiliary systems whilst establishing validated design methodologies compliant with ASME MFC-12M principles extended to extreme operating conditions.

In carrying out the work, you will also be part of the UKAEA Fusion Engineering CDT, and, along with your cohort of other doctoral students from universities across the UK, will receive training on cutting edge topics in fusion energy from academic and industry experts in fusion energy. The 3-month CDT fusion engineering training programme is delievered at 4 leading Russell Group research universities - the University of Manchester, Liverpool, Sheffield and Birmingham, and hence you will be funded to travel to these univiersities to recieve training across the fusion energy topic. The CDT trainnig programme is detailed at the CDT website https://www.fusion-engineering-cdt.ac.uk/training-fusioneers/programme/

The project is sponsored by WIKA, and you will also have the opportunity to spend time at their facilities where this is beneficial for the project.

Apply for this project at The University of Liverpool here. Add 'UKAEA EngD in Fusion Engineering 2026/27' in your title.

For further information about the project please contact the supervisor at Sebastiano.Fichera@liverpool.ac.uk

References

1. ASME MFC-12M-2006 (R2014). Measurement of Fluid Flow in Closed Conduits Using Multiport Averaging Pitot Primary Elements. American Society of Mechanical Engineers.
2. Day, C. and Murdoch, D.K. (2011). HCLL and HCPB coolant purification system: preliminary measurement and instrumentation plan. Fusion Science and Technology, 60(4), pp.584-589.
3. Baker, R.C. (2016). Flow Measurement Handbook: Industrial Designs, Operating Principles, Performance, and Applications. 2nd ed. Cambridge University Press.
4. Shank, K.E. and Easterly, C.E. (1976). Tritium instrumentation for a fusion reactor power plant. Oak Ridge National Laboratory Report ORNL-TM-5581.

Funding Notes

Students will receive a 4-year studentship including home tuition fees, UKRI stipend (indicated as £21,805 in 26-27) and a £25k RTSG budget for the project. All costs associated with attending CDT training will be met by the RTSG budget.

Please note that this advert will be withdrawn when a suitable candidate is identified, we recommend that you apply early.