On 30th January, 1607, a massive storm surge swept up the Bristol channel, swamping large parts of Devon, Somerset, Gloucestershire and South Wales. It is estimated that 2,000 people or more drowned, as houses and villages were swept away and around 200 square miles of farmland inundated. In the Church of All Saints at Kingston Seymour, near Weston-super-Mare, a chiselled mark remains showing that the water reached 7.74 metres above sea level.
Some 412 years on from that tragic event, an academic chose to recall it in a talk he was giving. They did so not because it was an interesting slice of British meteorological history, but in order to warn that it could happen again. And the audience they wanted to warn? The people in charge of Britain’s nuclear power stations.
In fact, that warning was just one of several sobering analyses given the same day at a meeting of academics advising the government’s nuclear watchdog, the Office for Nuclear Regulation (ONR), on climate change risks. The little known and catchily named Expert Panel on Natural Hazards – Meteorological and Coastal Flood Hazards Sub-Panel meets to advise the ONR once a year. The minutes and presentation slides of the last meeting, which took place at the ONR head office in Bootle, Merseyside, in May 2019, have been obtained by VICE under the Freedom of Information Act. They make interesting, if not alarming, reading.
For starters, according to the academics – whose names were all redacted – climate change-related heatwaves could lead to a nuclear disaster. Or in their words: “significant heat waves of persistent high temperatures are likely to occur” so that “the ability of Heating Ventilation and Air Conditioning (HVAC) plant to maintain required temperature limits could be challenged, potentially leading to a plant shutdown and the risk of an accident”. This matters because, as the academics point out, the UK is set for more frequent and intense heatwaves and we have eight operational nuclear power stations, with three more in the pipeline – Bradwell B, Hinkley Point C and Sizewell C.
Specific words of caution were given to the builders of Hinkley Point C. Currently under construction at an estimated cost of £22.9 billion, it is the flagship project of the new generation of nuclear power stations from the Nuclear New Build (NNB) Generation Company, a spin-off of EDF Energy. It is due to operate from 2025 until 2085 when it will be retired, or decommissioned. This 60-year lifespan is significant as our planet may change quite a bit during that time. “It is possible,” one academic said, “that by the time HPC is decommissioned the planet will be 4C warmer with many extreme weather events, and therefore with significant design implications for NNB.”
The 1607 flood was not the only historical comparison used to illustrate future risks. Our nuclear power stations must be able to withstand events “worse” than both that devastating flood and the Great Storm of 1703, one speaker said. It’s been argued that the Great Storm, an extratropical cyclone, was the worst Britain has ever experienced. It brought down thousands of trees and chimneys and some estimates put the death toll up to 15,000. It occurred around the birth of journalism; Daniel Defoe penned a whole book about it, The Storm. He wrote: “No pen could describe it, nor tongue express it, nor thought conceive it unless by one in the extremity of it.”
Another presentation at the meeting looked at the possibility of “black swan” storm surges and waves. A black swan was ominously defined as a “high-consequence event that has never been previously observed”. The possibility of a black swan event that causes massive coastal flooding is a big deal to nuclear power stations as they’re all on the coast to use seawater for cooling. The Fukushima disaster stands as an example of what can happen. In 2011, the tsunami in Japan caused three nuclear meltdowns, three hydrogen explosions and a radiation leak which led to residents being evacuated within a 20km radius.
The result of research into black swans – called “Synthesising Unprecedented Coastal Conditions: Extreme Storm Surges” aka SUCCESS – was presented at the meeting. It was important to conduct this research, the academic said, because “the storm surge of 5th December 2013 caused sea levels in many parts of the country that were the highest ever recorded and begs the obvious question – could they have been worse?”
In other words: we’re likely to see storms on a scale never seen before and the only way to get a handle on them is to model their impact using software. One conclusion of modelling these “artificially enhanced events” was that we could see black swan coastal floods which reach close to 6m above sea level.
All in all, the presentations and discussions at the meeting would not have been particularly welcome to the ONR, whose job it is to make sure nuclear power stations are built to standards that guarantee public safety. In a statement to VICE, an ONR spokesperson said “ONR requires that nuclear new build sites are able to withstand extreme natural hazards, by designing against a one in 10,000 year event. Sites must identify these external hazards, which include the impact of climate change, and demonstrate that they are adequately protected against them throughout the lifetime of the facility.”
As one of the experts at the meeting put it, it was “grim news”. But exactly how worried should we be?
On one hand, 1607-scale floods, heatwaves compromising nuclear safety and Black Swan storms doesn’t sound particularly good. On the other, the ONR stipulates that nuclear power stations must be built to withstand “external hazards” so severe they only occur, on average, once every 10,000 years. That seems incredibly robust. However, there a few things to think about here. Firstly, how do you work out what a “once in every 10,000 year event” is? The past isn’t a good guide to future extreme weather in the age of climate change. Modelling may not be especially accurate either. In the words of one academic from the meeting minutes: “Climate and weather models are not good enough.”
The limitations of climate projections are currently being borne out in the real world. Nick Ely national coastal modelling & forecasting manager for the Environment Agency says: “It’s increasingly becoming apparent that defences designed over the last 50 years, using the best evidence at time including climate change, are now no longer providing the standard of protection to the original planned level.”
Another problem is claiming something can withstand a one in 10,000 year event when climate change is constantly moving the goal posts. An infrastructure project with a 60-year lifespan like Hinkley Point C might be able to withstand a one in 10,000 year event when it opens, but climate change means a one in 10,000 year event may become, for example, a one in 8,000 year event by the time its decommissioned. At the same time, a one in 10,000 year event may become something more extreme that the power station hasn’t been designed to withstand.
Even taking on board these considerations though, Kate Crowley, lecturer in climate risk and resilience at Edinburgh University, says Britain’s new nuclear power stations are designed to such a high bar in terms of what they can withstand, that the chance of them being compromised is vanishingly small.
She has an interesting perspective on the expert panel, too. “Often these panels are created to a degree to be controversial,” she says. “They may be there to deliberately put forward the worst case scenario, to push designers to think about new ideas and the black swan concept is exactly that – very much the worst case.”
Crowley does have some words of caution. “You can never completely manage all risk,” she says. “There is going to be residual risk where you might have your very, very extreme events, or where you have unknowns or where we take an emissions pathway that just catapults us into a really awful situation.”
An “awful situation” is how you might describe the 1607 flood. As contemporary William Jones wrote: “Many hundreds of people both men women, and children were then quite devoured, by these outragious waters, such was the furie of the waves, of the Seas… Others some sitting in the tops of Trees might behold their houses overflowne with the waters. Some their houses caryed quite away.”
How much more awful would it be now, as the next generation of nuclear power stations is rolled out, if it wasn’t just houses being overflown?
First published by Vice, 3 June 2020