Andrew Buckley, Principal Engineer, ABS Group (UK Office) looks at the impact that Climate Change is having (and is set to increasingly have) on the UK’s nuclear infrastructure, and how the multiple threats associated with increasing extreme weather events may necessitate a reassessment of risks associated with nuclear sites – both today and into the future.
The impact of Climate Change – both today and increasingly into the future – is changing the way the nuclear industry needs to look at safeguarding its infrastructure and its risk levels – especially where the ageing infrastructure of current sites is concerned.
Recent findings of a high-resolution model(1) found that under a high emissions scenario (RCP 8.5), rainfall events in the UK exceeding 20mm/hr could be four times as frequent by 2080 compared to the 1980s.
In a report from the UK Parliament Joint Committee on National Security Strategy published at the end of October 2022, it claimed the UK saw six major storms in the 12 months leading up to the publication of the report, including some of the highest wind speeds recorded in over 30 years.
July 2023 was also the hottest month ever recorded on the planet(2), bringing with it heatwaves and wildfires in some countries, whilst simultaneously deluges and heavy rain episodes in others.
Looking ahead to 2050, the independent Climate Change Committee (CCC) anticipates that the UK will experience warmer and wetter winters, drier and hotter summers, and continued sea level rises; predicting that by 2050, about a third of England’s coast will be under pressure from flood risks.
The impact on nuclear infrastructure security is undoubtedly going to be challenged on an increasing basis by Climate Change.
Under the 2008 Climate Change Act, the UK Government lays an assessment of the risks to the UK from Climate Change before Parliament every five years through its Climate Change Risk Assessment (CCRA). It has highlighted that flooding is set to become more frequent and severe, affecting critical infrastructure including energy, transport, water, waste, and digital communication assets. In its last independent assessment, published in June 2021, it found that the UK is not ready for even the best-case scenario of Climate Change, let alone the current trajectory, and that “the gap between the level of risk we face and the level of adaptation underway has widened” since its last report in 2017.
Climate Change Impact on Nuclear Power Infrastructure
One of the key questions we need to ask of our existing infrastructure is: renew and re-strengthen or replace?
Our advice is that organisations should look with fresh eyes from a risk assessment perspective when it comes to Climate Change impact – in particular, the impact of rain, wind, and rising sea levels. A wait and see approach is not a good option, and operators should take the view that just because an extreme event has not happened does not mean it cannot or will not.
It is also important to look at infrastructure risks from a multi-hazard perspective. Rarely is there just a rain episode; so you could be looking at 100 mph winds accompanied by heavy rainstorms which could in turn lead to building damage, flooding, and wider associated risks.
Taking Steps to Reassess Risk
So how is the growing threat of Climate Change impacting assessments on UK nuclear licensed sites as part of the required operational safety reviews, particularly when looking at sites operating beyond their original lifespan?
Step 1: Review Demand
The biggest impact Climate Change is having on these assessments is when we Review Demand at facilities – especially around changes of use and changes in the hazard.
You should review original design loads against the requirements of both modern standards (Eurocodes), and also the potential impact for increased loads from developing Climate Change hazards and threats, and any revised demand. For example, although the frequency of an event (1 in 1,000 or 1 in 10,000 per year) has not changed, the magnitude of the event may well have changed.
Wind speed increases, rainfall increases, snow, and/or hail loads are typical weather hazards that should be considered and that are changing. Wind speed considerations are also influenced by any changes of the surrounding terrain (new buildings, etc.).
Step 2: Current Condition
Has the condition of the building or equipment deteriorated in the years since the last safety review? Are there signs of aging, damage, or have any modifications been made that could have an impact when looking at Climate Change loads, and the prospect of increased and heavier extreme weather episodes?
Step 3: Current Condition and Future Use Changes
Assessments should consider and review current condition against modern standards, whilst also addressing and assessing any potential future use changes, via analysis and assessment or another route.
Step 4: Safety Case/Operational Safety Review
As part of Operational Safety Review procedures, operators have to demonstrate to the regulator that conditions haven’t deteriorated and risks are not increasing. There is a need to build Climate Change considerations into each Safety Case.
Step 5: Planning for the Worst Credible Scenario
Just because a weather event has not previously happened does not mean it cannot or will not, and you should plan for a worst-credible scenario.
The goal here is to take the potential for an event or series of events – no matter how incredible and unlikely it may seem – and assess its credibility; in turn assessing the potential risks associated with primary, multiple, and consequential secondary risks.
Conclusion
Climate Change effects impacting our critical national infrastructure are already significant and look likely to worsen substantially under all reasonable Climate Change scenarios. The risk of future flooding of major infrastructure sites, high wind damage, landslides, and power outages are significant. They may also happen simultaneously, creating the potential for multiple cascading effects across infrastructure. The scale of the challenge facing Government, operators, and regulators is clear: there is an urgent need to review and, if require, adapt our infrastructure to the potential impacts of Climate Change.