Interview: How the ONR is regulating new nuclear developments in the UK

A new era of civil nuclear power in the UK is approaching with small modular reactors (SMRs) in the pipeline. A senior executive from the Office for Nuclear Regulation (ONR) has told NCE about how it is overseeing these new developments in the sector.

Great British Nuclear (GBN), the body within the Department for Energy Security and Net Zero (DESNZ), is running the government’s SMR competition, the final result of which is expected in spring 2025.

It is expected that two developers and their respective technologies will be chosen to build a fleet of SMRs, potentially at Wylfa and/or Oldbury, with government backing.

But to get to the construction stage, developers must satisfy the ONR that their organisational structures, reactor designs, and environmental protections are good enough to fulfil the requirements of safety cases and security cases.

Much of this regulatory activity takes place within the context of generic design assessments (GDAs), but these are not the only mechanism through which the ONR assesses SMR proposals.

The in-development large-scale plants – Hinkley Point C and Sizewell C – have already completed the GDA process, so ONR’s time is currently mostly occupied assessing SMR designs.

A critical point to note is that developers bear the regulatory cost – so developers pay the ONR for access to regulatory consideration.

ONR in the broader government context

Often when something newsworthy happens in UK nuclear regulation, other government bodies point to the ONR as the organisation to speak with. But the ONR is not the only body responsible for regulation of nuclear activities.

ONR director of regulation, new nuclear reactors Jane Bowie said: “We’re part of a much broader regulatory system. There’s other requirements for permitting that the Environment Agency lead on.”

Bowie said the ‘regulatory justification decision’ instrument is a Department for Environment, Food and Rural Affairs (Defra) process and “there’s also planning requirements that are delivered by the Planning Inspectorate.

“We’re part of a much bigger ecosystem, and it’s not the case that the ONR leads on all of those. It’s a multitude of requirements.”

ONR licenses organisations, not technologies

Bowie explained that the regulator licenses organisations hoping to deploy nuclear reactor technologies, not the technologies themselves.

“In this country, we don’t license technologies,” she said. “We license organisations to undertake a nuclear activity on a particular site.”

For example, in the GBN-purchased sites at Wylfa and Oldbury, the ONR “would license an organisation to undertake nuclear activities by a particular technology”, Bowie explained.

“You can run licensing parallel to generic design assessment,” she continued. “What we’ve seen historically is that generic design assessment is done first because a site is not known or allocated and then moves into the licensing process.

“But there’s no reason to run that in sequence. They can be done in parallel. If a site and a developer is available.”

However, this is not the case for the GBN technology selection vendors.

“The delivery model via GBN is that they will take forward those developments themselves,” she said.

“They would set up a development company – the intention is through GBN at the moment – but there are different business deployment models. Some just want to be vendor providers.

“But there is still then a requirement to secure a site and then develop an organisation that’s able to be licensed.”

Explaining what the GDA is, Bowie said: “Generic design assessment means you’ve got a generic envelope. It’s not specific to a particular site, but what vendors or developers can choose to do is a site-specific design assessment.

“That’s why generic and site-specific are two different things.”

There are four SMR developers whose technology is currently undergoing the GDA process – which are the same four remaining in the GBN competition: GE-Hitachi, Holtec Britain, Rolls-Royce SMR and Westinghouse Electric Co.

However, Westinghouse has requested a “short delay” to its GDA.

An ONR spokesperson said: “Westinghouse wrote to us in December 2024 requesting to defer the start of GDA for the AP300. At the current time we do not know Westinghouse’s anticipated timescales for commencing the GDA.”

What differences are there between the regulation of gigawatt-scale and SMR developments?

While gigawatt-scale reactors are at the opposite end of the size spectrum compared to SMRs and advanced modular reactors (AMRs), they do have to follow the same procedures.

“There isn’t any difference; the regulatory regime is technology agnostic,” Bowie said.

“All of our regulation is risk-informed, targeted and proportionate, but we also consider novelty and complexity as well.

“It’s based on the concept of safety and security cases, so that’s written in documentation that’s submitted to us, and we assess that on a sampling basis.

“There’s not anything different done for SMRs and gigawatt-scale, per se, there are vendors out there making claims about improved safety for different technologies, but we assess what is put in front of us against the criteria and standards that we have.”

How is the ONR improving regulatory alignment with international sister agencies?

Regulatory alignment with international sister agencies in countries which already have, or hope to have, nuclear power can be a source of frustration for SMR developers because it can add tens of millions of pounds to their costs.

“Our standards are benchmarked against IAEA (International Atomic Energy Agency) standards and the WENRA (Western European Nuclear Regulators’ Association) reference levels, so there’s that element of harmonisation,” Bowie said.

“But each country has its own legislative basis, and that’s really what prevents worldwide, international harmonisation.

“In the UK, you might have heard of this concept as low as it’s reasonably practicable [ALARP]. That’s fairly unique to the UK.”

ALARP is a risk management approach which the Health and Safety Executive (HSE) describes as “weighing a risk against the trouble, time and money needed to control it”.

In the case of nuclear regulation, it means weighing the radiological incident likelihood and other risks against the effort required to mitigate those risks.

“All of our standards are benchmarked, and there is, and has been for many years, work towards harmonisation in technical areas, that’s the standards side of things,” Bowie added.

The UK and Finland recently agreed to work together formally on SMR regulatory alignment.

“In terms of working with overseas regulators, two things that we’re doing there,” Bowie said.

“One is taking much greater credit for what overseas regulators have done in terms of their assessments, where that’s current.

“That’s not necessarily new to the UK, but there is an opportunity at the moment where we have got ourselves, the Canadians and the US NRC [Nuclear Regulatory Commission] looking at the same technologies on similar time scales.

“That does afford us a greater opportunity to work together.

“There’s the taking credit for overseas regulatory assessments, where they’re a bit ahead of us, or where they’ve done assessments before.

“And secondly, this opportunity now to collaborate, where we’re working on the same things at the same time, and both of those things will bring about schedule and cost benefits, and efficiencies for the vendors involved.”

Bowie explained that there could be a situation where the US NRC had already started an assessment of a particular reactor technology, or they could have completed it. Rather than the ONR redoing the whole assessment, it would ask vendors to send all the work submitted for the US NRC, and also ask the NRC for everything it has assessed. This is done via an ONR/NRC memorandum of understanding (MOU).

“That reduces regulatory burden for the vendors, but also reduces the time, effort and resource that we have to apply to undertake our own assessments.

This is also beneficial for vendors as they don’t have to pay multiple times for similar assessments in different countries.

“We are really focused on reducing the delta between jurisdictions,” Bowie said. “What we don’t want is for vendors to undertake safety analysis or regulatory work for one jurisdiction, say the US, and then have to redo it all for the UK.”

She added that the ONR is saying to developers “bring as much over [from engagements with regulators in other countries] as you possibly can, don’t redo – reuse, and we’ll seek to work with you to minimise any delta to meet UK regulatory requirements”.

Developing the GDA process

The fundamental principles of the new nuclear regulatory landscape are largely static because they are defined by legislation from Parliament.

However, Bowie said the ONR conducts minor regulatory reform “all the time”.

“We streamlined the GDA process,” she said. “That was previously four steps; it’s now three.”

Moreover, its “focus is on learning”.

“We first started GDA back in 2006,” Bowie said. “Importing learning from work we’ve done previously is how we develop processes.”

Bowie said the creation of the early engagement process was in response to increased demand as an example of how the ONR has evolved regulation to meet the changing needs of the civil nuclear industry.

“That is seen as advantageous for vendors in terms of risk reduction for their projects, getting regulatory insight as early on as is possible, so they understand what those requirements might mean for their development timelines, costs, etc, in the UK,” she said.

SMRs driving demand for regulatory oversight

The ONR said lots of new developers hoping to deploy their individual SMR and AMR designs had driven a need to increase activity at the regulator.

“The increase in demand does mean that we’ve had to look at how we resource these projects,” Bowie said. “There are a range of ways that we can resource these projects, and it’s not just internal.

“For example, we can make greater use of the supply chain through technical support contractors, and then also the new ways of working [such as] greater collaboration with overseas regulators, taking greater benefit. I use the phrase ‘credit’ or overseas regulatory assessments.

“That all helps us respond to the demand. Our primary motive here is to not be a blocker. We will try and ensure regulatory resource is never a blocker to entry into UK and UK regulation.”

She reported that most of the hold up in the regulatory process comes from the developers.

“We have on our website guidance to requesting parties, which sets out the GDA process and that gives indicative timeframes for each of the steps. And we have been successful in meeting those timeframes,” she said.

“However, our experience is it’s not our readiness, it’s the readiness of the requesting party.”

‘Requesting party’ is the phrase used to describe the technology vendor.

Bowie said the requesting party is “typically the rate determining factor, it’s their readiness to enter UK regulation from a knowledge perspective, from a safety case perspective, and also from a design maturity perspective as well.

“The schedules themselves are agreed [between] ourselves and the requesting party. It’s not ‘You must achieve this in this time’; it is a function of their readiness, what material they’ve got, how advanced their safety analysis and safety case material is, how much advice and guidance they need and the maturity of the reactor technology as well.”

Bowie explained that if there’s a mature technology which exists already and a vendor company wants to deploy it as new nuclear generating capacity, and they already have familiarity with the ONR and wider UK regulatory landscape, they could have an expedited experience with the ONR.

Rolls-Royce SMR is currently the only developer in the GDA process which fits that profile of having an SMR technology proposal which is based on existing technology (reactors for submarines) and has a long history of engagement with UK regulators.