Nuclear is a safe technology
No way to generate electricity is risk‑free, but risks differ. A handful of people die each year installing solar panels on rooftops. Tracking the dangers in mines for the critical minerals used in windfarms at ‘artisanal’ mines in the developing world is difficult but reports of deaths are frequent.37 Even in developed countries mining is a risky business.38 When the Banqiao Dam, a hydroelectric power station in China burst in 1975 over 25,000 people died in the subsequent flooding.39
When you adjust for deaths per unit of energy produced it becomes clear that some technologies are much safer than others. Burning fossil fuels, by a distance, is the deadliest way to generate power. Coal is more than 1,000 times deadlier than solar. Deaths from natural gas are rarer but still about 100 times more common than from wind or solar.40
Nuclear is an exceptionally safe technology. Our World in Data’s review of scientific studies finds nuclear is roughly as safe as wind or solar power, or put differently, between 100 and 1,000 times safer than burning fossil fuels.
Radiation is all around us. It occurs naturally in rocks and soil, in cosmic rays from the Sun and outer space, and in trace amounts of the food we eat. It is not unique to nuclear power. More than half of the total radiation exposure to the global public from electricity generation is due to coal. Renewables, which depend on rare earth metals like neodymium, expose workers to radiation in mining. For example, the UN Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) found that workers mining rare earth metals for solar were exposed to radiation levels forty times higher than those faced by nuclear workers.41
This is not to say that radiation poses zero risk to the public. There is a well-established scientific link between high levels of radiation exposure and ill health, in particular, cancer. The ‘gold standard’ of radiation health research is the Hiroshima/Nagasaki Life Span Study, which followed Japanese atomic bomb survivors at key lifetime milestones (age 30 and age 70).
People over 1.1km from the centre of the blast were exposed to around 1,000mSv in one go and were 47% more likely to develop a solid-cancer. The risks persisted over decades and could be detected - at a linearly lower rate - at exposures as low as 100mSv.
Put differently, if 100 people were exposed to 100mSv in one go, then on average one additional person would develop cancer as a result.42 To put that into perspective, 42 of the 100 would develop cancer for other reasons. For context, 100mSv is ten times the dose received from a whole spine CT scan and more than 50 times the average Briton’s annual background dose.43
When radiation levels fall well below 100mSv, epidemiology is a limited guide. The core problem researchers face is determining whether any increase in cancer rates is driven by radiation exposure or statistical noise. In one paper Prof Gerry Thomas, who led the Chernobyl Tissue Bank at Imperial College London, pointed out that “a population of one billion individuals would be needed to detect a statistically significant risk of cancer at a dose of 1mSv.”44 (Because the increase we would predict from such a dose is so low.) This study would also need to follow each individual over the full length of their life. In short, it would be the most expensive scientific study ever created.
In response to the clear difficulties in assessing radiation harms at lower doses, the field of radiation protection has adopted a approach known as the Linear No-Threshold (LNT) hypothesis. Put simply, it assumes that if exposing 100 people to 100mSv causes one additional case of cancer then so does exposing 1000 people to 10mSv and 10,000 people to 1mSv (and so on and so forth).
UNSCEAR, the Health Physics Society, and the International Commission on Radiological Protection both state clearly that due to high uncertainty at low doses – it is inappropriate to add up 100,000s of tiny doses (e.g. sub 1mSv) and use them to estimate cancer rates.45 46 47 It would be like assuming that if 4,000 men cut themselves shaving and each lost 1ml of blood then one would die of blood loss.
The radiation doses members of the public are exposed to due to nuclear power are extremely low. Britain runs annual Radioactivity in Food and the Environment (RiFE) surveys each year. The purpose is to estimate the highest annual exposure to radiation someone nearby might receive. Using dosimeter readings and local-food samples, they calculate the dose received by someone living close to the plant, eating over a kilo and a half of fish, crustaceans, and mussels per week, and regularly visiting nearby beaches. At Hinkley Point, this individual would receive an annual additional dose of 0.032mSv each year.48 This is equivalent to eating 320 grams of Brazil Nuts, or spending a weekend in Cornwall.
Given the extremely low radiation exposures near nuclear power stations, it is unsurprising that a recent study, commissioned by UK’s Independent Committee on the Medical Aspects of Radiation in the Environment (COMARE), which covered every single registered cancer case within 25km of every UK nuclear site found no increase in leukaemia, brain tumours or any other cancers, and no other pattern of higher risk in nearby populations.49
People worry not only about normal operation but about accidents such as Three Mile Island, Chernobyl, and Fukushima. The worst — Chernobyl — stemmed from a fatally flawed RBMK design, never used in the West, and a reckless, rulebreaking safety test. Chernobyl also had no containment vessel.
Chernobyl has been studied extensively. In the immediate aftermath, 134 first responders received very high doses; 28 died within months. The most significant impact of Chernobyl was the increase in thyroid cancer rates for people who were exposed to contaminated food and milk as children. About 1% of early‑onset thyroid cancers lead to death within 50 years. Upper‑bound exposure estimates suggest up to 16,000 additional cases—around 160 premature deaths.50
The radiological impact on the wider Ukrainian and Belarussian populations was limited. Around six million people were exposed to an additional 10mSv—the equivalent of one CT scan—spread over 20 years. No one was hurt outside the USSR. UNSCEAR estimates that around 200 people had their lives shortened in total by Chernobyl and none of the other civil nuclear disasters we have experienced can be shown to have led to any early deaths.51
It is important to put the risks of radiation exposure into perspective. The 100-200mSv exposure received by workers involved in the Chernobyl clean-up is estimated to have increased their annual risk of death by 1%. Yet, a worker moving from rural Inverness to London will see their annual risk of death jump by 2.8% as a result of air pollution. The extensive safety features at Hinkley Point C and Sizewell C mean that in the extremely rare event of a core meltdown at Hinkley Point a local will be exposed to just a few mSv worth of radiation – around a third of the dose someone might receive from merely living in Cornwall.52
How Britain regulates radiation risks
Britain regulates the radiological risks from nuclear power under Health and Safety laws. At the heart of Britain’s Health and Safety legislation is a sensible idea: In our day-to-day lives, risk is unavoidable. Eliminating it would not only be impossible, it would be undesirable too. Almost every worthwhile activity from driving to work to taking a vaccine carries some risk. Yet not every risk is worth the reward.
Health and Safety laws divide risks into three broad categories. At one end, there are unacceptable risks where the risk (or severity) of harm is high and the benefits cannot justify exposing people to that avoidable risk. For example, drink-driving might be faster than getting the night bus but it is not worth the risk of causing a fatal accident. At the other end, there are risks that are broadly acceptable, where the risk of harm is low and clearly outweighed by the benefits. For example, crossing the road at a zebra crossing.
There’s a third category in the middle: tolerable, if As Low As Reasonably Practicable (ALARP). These are risks that can be tolerated, if measures have been taken to reduce that risk as low as reasonably practicable. For example, riding a bike to work. Wearing a helmet (along with lights and a maintained bike) is a reasonably practicable control, whereas fitting adult stabilisers or requiring an escort vehicle would be grossly disproportionate to the risk. In other words, reduce risk until the costs of further measures clearly outweigh the benefits, while erring on the side of caution.
In Britain, health‑and‑safety responsibilities fall on dutyholders; for nuclear, that is the site licence holder. Our approach is goal-based, not prescriptive. Dutyholders (i.e. the nuclear plant licensee) are free, in theory, to meet outcomes in whatever way they deem the most suitable. The advantages of goal-based regulation are clear: they allow for innovation, do not lock dutyholders into inappropriate solutions, and they are evidence based. Yet, there are drawbacks too. In some cases, it is unclear what must be reduced to ALARP. In some cases, this can lead dutyholders to add safety measures far beyond what legislation requires.
Whether an activity is unacceptable, tolerable if ALARP, or broadly acceptable is determined by two numbers. The Basic Safety Limit (BSL), which determines the upper limit of what can be considered tolerable. For normal operation, this is 1mSv for off-site exposures. This is far below the region where a link between exposure and cancer is well–established and well within the regional variation in natural background radiation in the UK.53 At the other end, there is the Basic Safety Objective. Reducing radiation doses below the Basic Safety Objective (0.02mSv or the equivalent of flying for five hours) is considered a poor use of the regulator’s time. At this level, risk can be considered broadly acceptable and dutyholders are, in theory, not required to prove they have reduced risk to ALARP beyond this.
ALARP, or more precisely its international cousin ALARA (as low as reasonably achievable) is applied more pragmatically in other countries. In the US, it is an explicit cost benefit analysis using a flat dollar per rem (equivalent dose to 10mSv) figure of $7,200 provided certain dose targets are met.54
ALARP should not, as Health and Safety Executive guidance states: require us to constantly raise standards, require everyone adopt the standards of the employer with the highest standard of risk control, or require us to reduce risk to zero.
How disproportionate safety regulation increases costs
Britain’s approach to regulating the risks from radiation is sound in theory: reduce risks (but not to zero) and, only when it is proportionate, erring on the side of caution. The problem is not with the underlying approach, but with the outcomes it delivers.
ALARP and gross disproportion
The application of ALARP to nuclear power frequently leads to the adoption of expensive safety measures to reduce risks that are already extremely low, in other words grossly disproportionate. To some extent, it is unfair to blame the Office for Nuclear Regulation when grossly disproportionate safety features are adopted – their incentive and legal duty is to only consider safety – the responsibility to challenge recommendations on gross disproportionately rests with the dutyholder. At times, expensive changes are pro-actively brought forward by dutyholders based on a sometimes inaccurate view of what the ONR would actually accept. This is not an issue with the regulator’s behaviour itself, but the incentives created by the regulatory system.
When the ONR commissioned the economic consultancy NERA to assess its economic impact, one of the key findings was that challenge from industry is extremely rare and that there was only one case where cost–benefit analysis was used to oppose an ONR request: a filtered vent to release steam and gas through a particle‑trapping filter in the event of a meltdown. The ONR eventually accepted EDF’s argument that the vent would only reduce radiation exposure by a tiny amount in events that are extremely unlikely and already covered by other safety features.
Industry may be failing in its duty to provide challenge, but the root cause is the structural incentives set by regulation. These include:
- The cost of commissioning safety cases and cost-benefit analyses: To challenge an ONR suggestion will involve preparing extensive analysis of risks and costs. This is expensive – nuclear engineering and radiation safety experts do not come cheap – and there’s still a risk the ONR will not be persuaded by the analysis. There’s an additional cost too: time. Preparing a strong safety case or gross disproportion challenge can take months delaying projects. As a result, some may decide that it simply is not worth the hassle to challenge a decision.
- Indeterminate timescales for challenges to be resolved: Investors want certainty, yet the timescale for resolving a challenge on the grounds of gross disproportion is not clear-cut. Some decisions are made quickly, but it could easily lead to lengthy back-and-forths. When there’s a risk this could drag on for months (or even years) that has major implications for financing.
- The risk that challenge undermines the dutyholders’s good standing: The ONR regulates organisations not designs. Dutyholders will be wary that if they are too oppositional and challenge every recommendation on cost grounds then the ONR would view them as lacking a ‘safety culture’. This could also have impacts on planning – if the public learns that the regulator is regularly in opposition to the site operator they will be more likely to oppose the development.
- Lack of clarity over the definition of gross disproportion: The legal test for gross disproportion is that the sacrifice is clearly out of proportion to the reduction in risk. However, there’s a lack of guidance and clarity over when something is and when something isn’t grossly disproportionate. One issue is that the ratio of costs to benefits needed to prove gross disproportion isn’t fixed. The Sizewell B Inquiry, for example, used a range of ratios – three for worker risk, two for the lowest public risks and ten for the largest high-consequence nuclear risks. The idea of using different ratios for different risks is itself philosophically suspect – after all, the severity of the risk should be captured on the cost-side of the equation.
- The difficulty in comparing quantitative and qualitative claims: Part of the problem is that regulators often are asked to balance qualitative and quantitative information. For example, a dutyholder may warn that implementing certain safety measures would make the reactor £100m more expensive to build. On the other hand, the safety measure may be expected to save a single life. In many areas of public policy, we assign a monetary value of life to allow us to work out these decisions. For example, the National Institute for Clinical Excellence assumes spending up to £30,000 is worth it to save one Quality Adjusted Life Year. The Treasury’s Green Book uses a figure of £2.467m per fatality to guide decisions on whether to make additional investments in speed cameras, flood defences, and low-emission buses. We may be squeamish about assigning a value to a human life, but money protecting people from small radiation risks is money that cannot be spent on road safety. Additionally, only direct costs to the dutyholder are considered - the wider benefits of nuclear power such as decarbonisation are not factored in.
Relevant Good Practice
In order to be considered ALARP, dutyholders must be using Relevant Good Practice (RGP), which can range from following regulatory guidance and industry standards to using practices that have a record of safe operation. The issue is that there is no clear hierarchy or weighting to guide what is and isn’t RGP. When different sources of RGP conflict, it can be difficult for dutyholders to work out what is and is not needed to comply.
In some cases, features that may have been RGP at one time are no longer necessary due to new reactors having additional safety features. Britain last built a new reactor 30 years ago, so relying on domestic precedent is likely to lead to design changes that are inappropriate to reactor types only built overseas.
One key issue is that designs in operation abroad have to be redesigned to be considered RGP in the UK. For example, EDF has raised concerns that in order to comply with British environmental and nuclear safety regulations they were forced to make thousands of design changes to the EPR. Not only did this limit the gains from repeating a standardised design that was safe enough to satisfy French and Finnish regulators, it also led to significantly more steel and concrete being used.
One major change was the requirement to install a separate failsafe hardwired control system. This involved doubling the number of control and instrumentation cabinets and adding hundreds of kilometres of cabling. Another was the requirement to add two additional floors of HVAC in the four safeguard buildings. Neither was required by the French regulator for Flamanville 3.
Many of the components inside the reactor building are provided by the same manufacturers, but require extensive additional safety testing and certification to be used in the UK. All of this raises design complexity and limits the gains from specialisation.
There are four Advanced Boiling Water Reactors (ABWR) in Japan. It is a design with an excellent safety record – notably surviving the Tōhoku earthquake which caused the Fukushima accident. GE Hitachi Nuclear Energy planned to build two in Wales on a site near Wylfa power station in Anglesey/Ynys Môn.
Although the ABWR has an outstanding safety record, GE Hitachi were required to make significant design changes in order to comply with RGP to pass the Generic Design Assessment. The most notable was the installation of bulky HEPA filters on each heating, ventilation and air‑conditioning (HVAC) duct.55 Beyond the filters themselves, this would have added costs to the layout of the building’s ventilation system and increased the amount of waste that needs to be disposed of. The safety benefits were tiny to non-existent. The filters would cut public exposure by 0.0001mSv (about one banana‑equivalent dose) in normal operation. In an emergency they would be redundant because there are already separate containment and filtration systems with HEPA filters.
The ONR insisted on the HEPA filters because they are considered RGP in the UK. The issue is that the UK, unlike the US or Japan, built gas-cooled Magnox and AGR reactors that continuously create particulate-laden gas effluents and lack a sealed containment. The core issue is that the ABWR is a completely different design to Britain’s Magnox and AGR fleet. Installing HEPA filters for this purpose on an ABWR is like installing a catalytic converter on a Tesla.56
Case Study: Westinghouse AP-1000’s Generic Design Assessment
When Westinghouse proposed bringing its AP-1000 reactor to Britain, one of the key things the ONR challenged during the Generic Design Assessment process was the layout of the spent-fuel pool: the water-filled pond where used fuel assemblies sit for several years while they cool and their radioactivity dies down.
In the original US design, the pool is densely packed. Westinghouse splits the racks into two zones: “fresh-out” assemblies go into positions with extra neutron-absorbing material, and older, lower-power assemblies are moved into tighter-packed positions. Making that work safely depends on well-written software and operators rigorously following loading rules so the fuel always stays comfortably sub-critical (i.e. there is no chance of a self-sustaining chain reaction starting in the pond). This approach has been used extensively in the US with a strong safety record.
The ONR however assessed that Relevant Good Practice was only to use ‘administrative controls’ when there was no practical engineered solution. In this case, there were engineered alternatives available. A total of eight different options for the fuel pool were considered at length. One option was to have a larger fuel pool. This was rejected by Westinghouse because a large fuel pool turn would have necessitated a larger nuclear island. In other words, it would have meant radically redesigning the plant layout, losing the benefits of standardisation. The alternative that was eventually accepted was to give every fuel rack the same fixed spacing. This allowed the fuel pool to stay the same size, but meant around one-third less spent fuel could be stored and which would increase operational costs.
Historically, nuclear plants relied on active systems to prevent major accidents, with backup diesel generators often in the highest safety category (Class 1 in the UK, “safety-related” in the US) because they were essential for cooling the reactor and containment.
In the AP-1000, passive systems such as gravity-fed water, natural circulation, and passive heat removal, can cool the core and containment for extended periods without power. The US regulator therefore classifies its diesel generators as non-safety.
In the UK, however, they are Class 2 because they support post-accident recovery, including battery charging, monitoring and ventilation, residual heat and component cooling, spent-fuel pool cooling, and refilling the passive containment cooling tank. The UK’s multi-tier classification system, compared to the US’s two-tier approach, brings stricter quality-assurancerequirements. These can raise costs and limit suppliers, creating supply-chain challenges. No one believes the US approach is unsafe, only that the UK demands additional, often expensive, assurance.
This was not the only case where something was classified as safety-related in the UK but not the US. For example, the AP-1000 has a remote shutdown room in case of an accident. In the US, the remote shutdown room uses digital controls and the equipment was not classed as safety-related due to the plant’s passive features. The UK’s unnecessary extra rules have meant that an additional very expensive class 1 safety panel was required despite the fact it was extremely unlikely it would ever need to be used.57
What needs to change
Change the mindset of Britain’s nuclear regulator
Deploying safe, clean nuclear power is essential to the Government’s Clean Power and Economic Growth missions, yet the Office for Nuclear Regulation has no duty to promote nuclear energy and limited scrutiny from elected officials.
Part of the problem is that the ONR is sponsored by the Department for Work and Pensions, a department where nuclear regulation will never be a top ten priority, and as a result, lacks ministerial scrutiny. This is a legacy of the Nuclear Installations Inspectorate sitting under the Health and Safety Executive.
One potential rationale to maintain the DWP’s sponsorship is to maintain the regulator’s independence from influence by commercial interests. However, this approach is unusual within the UK. For example, the Civil Aviation Authority is responsible for airline safety, but is sponsored by the Department for Transport. Natural England and the Environment Agency are sponsored by Defra.
The ONR’s sponsorship would be suited to a number of different Departments. For example, the Department of Business and Trade hosts the Regulation Directorate, while the Department for Energy Security and Net Zero (DESNZ) has a clear interest in the energy security and climate benefits. In South Korea, where nuclear is deployed cheaply the nuclear regulator (and environmental regulator) report directly to the PM allowing for fast approval processes. As multiple departments have a clear interest in nuclear regulation, a similar approach may be justified. The ONR’s sponsorship should be moved from the Department for Work and Pensions to the DESNZ.58 To enable effective scrutiny, the Cabinet Office should chair a regular committee attended by DESNZ and the Department for Environment, Food and Rural Affairs to co-ordinate work and address cross-cutting issues such as duplicative requirements. This should be modelled on the ‘Star Chamber’ idea put forward in the Ministry of Housing Communities and Local Government Policy Paper Getting Great Britain Building Again.59
There is currently no duty for the ONR to consider energy security, economic growth, or net zero. In theory, it is possible for the ONR to have successfully discharged its mandate in a world where no new nuclear power stations are ever built.60 The US, by contrast, recently passed the bipartisan ADVANCE Act, which updated the Nuclear Regulatory Commission’s mandate to “enabling the safe and secure use and deployment of civilian nuclear energy… through efficient and reliable licensing… for the benefit of society and the environment.” The ONR should be given a new objective to promote the safe and secure deployment of civil nuclear power for the benefit of society, the economy, and decarbonisation.
Challenges to ONR decisions are relatively rare. One reason is that dutyholders may feel deterred from challenging the ONR’s decision-making because it is expensive, time-consuming, and may lead the ONR to look unfavourably at future applications. The Government should require the ONR to create a ‘regulatory red team’ with a mandate to enable and deliver new nuclear energy to scrutinise its decisions and report up to ministerial level. It should have the authority to act as an appeals mechanism for dutyholders and require the ONR to publish cost-benefit analyses.
Restore proportionality to nuclear regulation
The most expensive and unnecessary design changes in the UK have been driven by ONR’s interpretation of Relevant Good Practice (RGP). The lack of a clear hierarchy of RGP creates uncertainty over what is and is not required leading developers to err on the side of caution. Many of the most disproportionate requirements such as the HEPA filters required for the ABWRs privilege UK operational experience over safe operational experience worldwide. In the case of the ABWR and AP-1000, the ONR required changes based on UK operational experience and did not treat US and Japanese safe operational experience as RGP despite the UK experience being based on very different reactor designs (i.e. gas-cooled reactors). With the exception of nuclear design codes and Approved Codes of Practice that have a footing in statute, the strongest weighting should be assigned to safe real-world operation. The ONR should be required to publish a clear hierarchy of RGP and place ‘real‑world safe operation in an International Nuclear Regulators’ Association (INRA) country’ at the top. There should be recognition that RGP should be based on demonstrated safety improvement applicable to that reactor type. The ONR should also review all of the published RGP documents looking at their relevance and the extent to which they overlap or conflict with other sources of RGP in INRA countries, with a special focus on markets with high significance to SMR vendors, such as the US.
Many of the reactor designs Britain wants to build are already licensed and running safely in countries with respected regulators. ONR does not currently treat those overseas approvals and safety analyses as “good practice by default”, so vendors must re-run work that has already been done and accepted elsewhere. This duplication creates long, variable reviews and pushes effort away from Britain-specific issues such as site hazards. The Government should require ONR to accept safety analyses from peer regulators by default and limit extra work to cases where UK-specific factors clearly justify it. This would mirror the unilateral recognition approach adopted post-Brexit for medicines regulation, where drugs approved by top overseas regulators are automatically approved here.
In theory, dutyholders can challenge design changes on the grounds of gross disproportion, but challenges are rare and cost-benefit analyses are almost never used. Part of the issue is that many benefits, such as fatalities prevented or life years saved, are not assigned a value as they would be in other areas such as railway or road safety. A clearer definition of Gross Disproportion and an accepted figure for the value of preventing a fatality would make it much clearer what can and cannot be challenged. The ONR should be required to support dutyholders to challenge ALARP decisions by creating a clear definition of Gross Disproportion (Exceeds a Cost-Benefit Ratio of 2) and using the Treasury Green Book Value of Prevented Fatality figure.
The Basic Safety Objective sets the level below which risks or dose go from being ‘tolerable if ALARP’ to ‘broadly acceptable’. However, it is often treated by regulators and dutyholders as a target rather than a floor to prevent unnecessary gold-plating. The duty to reduce risks or dose to ALARP should be automatically considered discharged when exposures are below the Basic Safety Objective (BSO) level. Such that below this value the regulator has no ability to require the further reduction in risk or dose. In addition:
- For Fault Conditions: The Basic Safety Objectives used for nuclear faults are set far below risks accepted in everyday life. For example, the BSO for off-site persons (i.e. someone living nearby) is equivalent to the risk of driving 200 miles on British roads. The BSO should be raised to be in proportion to other risks we consider broadly acceptable. The ONR should commission a review of the BSOs for faults and assess whether they are in line with other high-hazard industries and the international nuclear community. The review should also set a clear cut-off for individual accident sequences so ultra-rare events that fall outside the plant’s standard design assumptions—but are still checked as rare “what-ifs”—do not end up driving costly changes. For extremely rare external hazards, for example, an earthquake so severe it might occur only once in a million years, limited data has previously encouraged undue pessimism, and the review should examine how regulators handle such cases without excessive costs. For very low frequency events the costs are real: the EPR uses multiple separate emergency core-cooling trains—well beyond the norm in most reactors. This over-design appears to have been recognised as excessive with the ERP2.
- For Normal Operations (Occupational Exposures): between the Basic Safety Objective and the Basic Safety Limit (20mSv per year for workers) where the operator/developer has demonstrated ALARP, and there is a challenge to introduce further design changes by the regulator, the burden of proof on gross disproportion for any design request should be on the regulator to prove and should be time-limited.
- For Normal Operations (Public Exposures): In the case of the exposure to the public under normal operations, regulation of routine discharges of radioactivity to air or water is regulated by the environmental regulator (Environment Agency in England, Natural Resources Wales in Wales and the Scottish Environment Protection Agency in Scotland) through the permitting or authorisation of radioactive substances. Meanwhile routine external radiation dose to the public from the development is regulated by the ONR. The ONR and EA apply a BSO of 0.02mSv which applies to the summation of doses from both discharges and external dose. The value of this BSO is equivalent to a quarter of the radiation someone taking a transatlantic flight would be exposed to, and 100 times less than the average exposure a member of the public receives in the UK from natural sources.661The BSO for normal operation should be raised to a value between 0.15 and 0.3mSv per year mSv. These are the values set by the UK Health Security Agency as an Upper and Lower Dose Constraint, a threshold for optimisation, to ensure an appropriate level of protection. This would place the BSO at roughly 10% of the UK’s annual background dose, and less than what the average member of the UK Public gets from naturally occurring radiation in the food we eat.
In addition to the BSO the environmental regulator refers to a “threshold of no regulatory concern” set at 0.01mSv per year.62 This value defined by the International Atomic Energy Agency is considered sufficiently low that doses arising from sources or practices that meet these criteria may be exempted from regulatory control. Despite the current new nuclear plants in the UK giving doses less than this threshold, the same level of regulatory controls are applied both below and above this threshold. For facilities demonstrating doses below the threshold of no regulatory concerns the developer/operators should be granted a “Light” Radioactive Substances Permit/Authorisation, with requirements reduced simply to monitoring discharges and confirming they are discharging within these limits.
Modernise and streamline regulation for new nuclear technologies
Regulatory Justification requires vendors to show that, for a given reactor design, the benefits outweigh the costs of any public exposure to ionising radiation. This is something they do on multiple occasions through the site licensing, development consent, and GDA process. This creates a significant upfront for startups promoting new designs such as SMRs. The Defra Secretary should make an immediate ruling that all new reactor designs are considered justified provided they acquire a site licence or planning approval.
Requirements (under the Paris and Brussels conventions) to obtain third-party liability insurance of £1.2bn are one-size-fits-all and do not account for the lower-risk profile of SMR/AMRs nor the realities of modular factory manufacture, new fuels such as HALEU/TRISO, and nuclear transport. The Government should create a new SMR/AMR “low-consequence” category under the Nuclear Installations (Prescribed Sites and Transport) Regulations 2018 with a substantially lower liability requirement and review third-party liability arrangements for new nuclear technologies.
Modern designs (and SMR/AMRs) can, and in many cases do, have significantly lower risk profiles, but regulators still require extensive emergency plans based on older designs. Outline Planning Zones (OPZ) Detailed Emergency Planning Zones (DEPZ) should be based on evidence, not historic practice. The Radiation (Emergency Preparedness and Public Information) Regulations 2019 (REPPIR) should be amended so the current 30KM OPZ for reactors is replaced by a design-specific, evidence-based approach. In cases where doses at the site perimeter are below the level that triggers urgent action, the DEPZ should be eliminated.
The Semi-Urban Population Density Constraint greatly restricts the sites available for new nuclear projects. The requirements, based on the risks of old gas-cooled power plants, not modern designs, restrict opportunities for industrial co-location. The EN-7 National Policy Statement and ONR Siting guidance should replace the Semi-Urban Population Density Constraint with a risk-informed approach based on site-specific hazard and consequence assessments.63
To encourage innovation and avoid unnecessarily burdening innovative startups with large fixed costs, the ONR should be required to assess technical design first, then the plant, site, and organisational capability in the Nuclear Site Licence process. This is a more modern approach that shifts focus from excessive documentation to radiological and industrial safety outcomes. This ‘gated’ licensing system mirrors Canada’s system and would allow SMR developers to proceed through the licensing process without the substantial upfront cost of having all organisation capabilities in place.