The UK’s civil nuclear energy sector is entering a transformative phase, driven by energy security, decarbonisation, and net-zero emission targets. The UK Government has an ambition of 24 GW of nuclear capacity by 2050 and is investing across advanced reactors, small modular reactors (SMRs) and fusion technologies, as well as in safe and cost-effective decommissioning of legacy nuclear sites.
Achieving these goals requires accurate and reproducible measurements using the latest generation techniques. These can reduce the complexity of technical risks, accelerate licensing and construction of new reactors, and reduce the cost of decommissioning.
Offering confidence in measurement across the nuclear industry
As the UK’s National Metrology Institute, the National Physical Laboratory (NPL) is in a unique position to provide confidence in measurement across the nuclear sector. Metrology, the science of measurement, provides the standards and methods to ensure measurements are accurate, repeatable, and traceable, underpinning innovation, trade, and regulation. It plays a vital role in every stage of the nuclear energy lifecycle. From reactor design and construction to operation, fusion development and decommissioning, accurate measurements are essential for ensuring safety, efficiency, compliance, and investor confidence. Furthermore, understanding new measurement challenges is important for the strategic development of metrology to support the nuclear sector to address cost issues, technical barriers, regulatory bottlenecks, and waste concerns.
A recent report from NPL highlights how advances in metrology can help address many of these challenges facing the modern nuclear sector.
The UK’s nuclear sector is undergoing significant transformation. Existing reactors are approaching the end of their operational lifetimes, while new technologies are being developed to provide reliable low-carbon energy for decades to come. Advanced reactors and SMRs promise improved efficiency and flexibility, while fusion aims to unlock an entirely new source of energy.
However, these technologies also introduce new engineering and scientific challenges. They operate under more extreme conditions, use novel materials, and require greater levels of precision than previous generations of nuclear infrastructure. Successfully commercialising these technologies depends on reducing technical risk, demonstrating safety, and providing robust evidence to regulators and investors.
This is where metrology plays a fundamental role.
Why is metrology so important in nuclear?
Reliable measurements provide objective data that enables better decision-making throughout the lifecycle of a nuclear asset. Whether measuring neutron flux inside a reactor core, validating the performance of advanced materials or monitoring the integrity of a waste package over several decades, confidence in measurement is essential. Without trusted measurement standards and traceability, uncertainty increases, costs rise, and innovation slows.
Advanced reactors and SMRs
Among the most promising developments in nuclear energy are advanced reactor technologies and SMRs. These systems are designed to be safer, more efficient, and faster to deploy than conventional large-scale nuclear plants. However, achieving these benefits requires unprecedented levels of measurement accuracy.
Precise dimensional metrology is needed throughout manufacturing and construction to ensure critical components align correctly and perform as intended. Even small deviations can affect operational efficiency, maintenance requirements, and safety performance.
© shutterstock/Simon Kadula
At the same time, advanced reactors rely on accurate, real-time monitoring of parameters such as temperature, pressure, neutron flux, radioactivity levels, and structural condition. Operating environments are often characterised by high temperatures, radiation exposure, and other demanding conditions that can challenge conventional instrumentation.
NPL is helping address these challenges through the development of measurement standards, calibration methods, and advanced sensing technologies. Improved measurement capability enables developers to validate designs more effectively, reduce modelling uncertainty, and provide stronger evidence during licensing and regulatory assessment processes.
The result is a clearer pathway towards commercial deployment, helping developers bring new technologies to market more quickly and cost-effectively.
Metrology in fusion
Fusion energy presents perhaps the ultimate measurement challenge.
Unlike conventional nuclear fission, fusion systems involve plasmas operating at temperatures hotter than the centre of the Sun, while exposing surrounding materials to intense neutron bombardment and complex mechanical stresses. Understanding and controlling these environments requires highly sophisticated measurement systems.
To support fusion development, NPL is focused on several key metrology priorities. These include standards for high-energy neutron measurements, improved methods for measuring tritium, validated plasma diagnostics, and enhanced material testing capabilities.
Accurate measurement is particularly important because fusion technology remains at the demonstration stage. Every experiment generates data that informs design decisions, performance predictions, and future investment. The quality of that data directly influences the pace of technological progress.
© shutterstock/Sergey Nivens
Measurement traceability is therefore essential. Researchers, developers, regulators, and international partners must all be confident that results obtained in different facilities and countries can be compared consistently and reliably.
NPL’s multidisciplinary expertise is also helping to address some of fusion’s most complex challenges. For example, researchers are exploring advanced spectroscopic techniques to improve the detection and measurement of hydrogen isotopes, which are critical to future fusion fuel cycles.
Decommissioning
While considerable attention focuses on new nuclear technologies, decommissioning remains one of the sector’s most significant and costly responsibilities.
The UK is managing a substantial legacy of nuclear facilities that require long-term monitoring, waste management, and environmental protection. Decommissioning projects often span decades and involve complex technical, regulatory, and financial challenges.
Measurement science can play a major role in reducing these costs while maintaining safety standards.
Accurate monitoring of waste packages and storage environments helps ensure materials remain stable throughout their lifetime. Key parameters include temperature, humidity, corrosion rates, and radiation levels, all of which require reliable and traceable measurement systems.
Advanced imaging and remote sensing technologies are becoming increasingly important in this context. They enable operators to characterise waste safely, inspect difficult-to-access environments, and minimise worker exposure to hazardous conditions.
Improved measurement capability supports more informed decision-making, optimised maintenance schedules, and stronger evidence for regulatory compliance. Over the long term, these benefits can translate into substantial cost savings across the decommissioning programme.
Measurement challenges
One of the key findings from NPL’s recent report is that many measurement challenges are shared across different parts of the nuclear industry.
For example, traceable gas standards developed for one application may support fuel integrity monitoring in another. Detection of ratios between radioactive gases can provide early indicators of potential fuel failure, helping operators identify issues before they escalate. Similarly, remote techniques used to monitor corrosion and temperature in operating reactors can also support the management of spent fuel and waste storage environments.
These shared challenges create opportunities for knowledge transfer and collaboration across the sector.
Beyond individual technical challenges, metrology provides the infrastructure that enables innovation to flourish.
Standards, calibration services, validated measurement methods, and uncertainty analysis may not be visible components of a reactor or fusion facility, but they form the foundation upon which technological progress depends.
Through collaboration with original equipment manufacturers (OEMs), supply chains, government, academia, regulators and site owners/operators NPL is helping deliver practical outputs that strengthen the UK nuclear ecosystem. These include new measurement services, national and international standards, good-practice guidance, training programmes, and research publications.
Addressing skills shortages is another important element of this work. As the nuclear sector grows, so too does demand for scientists, engineers, and technicians with expertise in measurement science. Developing this capability is essential to maintaining the UK’s competitiveness and supporting future deployment of nuclear technologies.
Balancing nuclear energy and metrology to boost the UK’s energy system
Nuclear energy has a significant role to play in the UK’s future energy system, but its success will depend on the sector’s ability to demonstrate safety, performance, and environmental stewardship over many decades.
Many of the challenges facing the sector, from advanced reactors and new fuels to waste management and decommissioning, have important measurement dimensions. Ensuring that these challenges are understood and addressed will help provide the evidence base needed for innovation, regulation, and informed decision-making.
While often operating behind the scenes, advances in measurement science will continue to support the UK civil nuclear area, as the sector evolves.
Please note, this article will also appear in the 27th edition of our quarterly publication.