energy technology

The legacy of a nuclear power plant

While we were on holiday in Wales this summer, we passed Lyn Trawsfynydd and despite the protestations of my wife, we paused to take in the view:


That’s Trawsfynydd nuclear power station, a name I can neither pronounce nor spell. It’s the only nuclear site in Britain that was built inland rather than on the coast. And not just anywhere inland either, but right in the middle of Snowdonia National Park. The logic of this is not entirely clear, but nuclear power was more exciting in the 1950s. And besides, the architect was briefed to design a building that would blend into the landscape.

The man tasked with this mission impossible was Sir Basil Spence, a respected architect whose most famous building is Coventry Cathedral – the new one, the one that looks like a giant air conditioning unit. Spence was of the Brutalist school of architecture, a mid-century movement that produced monolithic structures in unadorned concrete, so that is what North Wales got. ‘Will it blend?’ asked local residents as the controversial construction got underway, and by the early 1960s they had their answer: no, unless you happen to catch it from the right angle in the right light and weather conditions. Preferably a deep fog.


Trawsfynydd (yes, I wrote it once at the beginning and am now copying and pasting it) came online in 1965, its two reactors producing 470 MW between them. They ran for 26 years and were powered down in 1991. The power plant was on standby for two years and then formally shut down in 1993.

The first stage of decommissioning was to remove the fuel and ship it to Sellafield for long term ignoring. After that the process of making the site safe began. At first this was just a matter of monitoring. As certain parts of the building became less radioactive, it was safe enough to send in the robots and start dismantling them. Any part of the site that had been in contact with nuclear fuel has to be carefully taken apart and safely stored. There’s a lot of this ‘intermediate nuclear waste’ to store, including a fair amount of uncatalogued waste that was stashed on site during its operation. Beginning in 1995, this stage of decommissioning was finally completed this year.

2016 is something of a landmark in the story of Trawsfynydd then, as the site is now ‘passively safe’ – as opposed to actively dangerous, I presume. That means they can lift the one-mile emergency area, and there’s little risk of a radiation incident in one of Britain’s most beautiful national parks.

Next comes some more traditional demolition work. Unless the Sir Basil Spence fans get a last-minute campaign together, those big square reactor buildings will be reduced in size. Then the site will sit for a bit longer until radiation levels decay enough to move that stored waste. We haven’t decided where it will go yet, but that’s scheduled to happen in the 2040s.

With the hazardous material off-site, we can clean up the storage facilities and begin to think about finally clearing the site. That is due to begin in 2074, with the site returned to its original state in 2083.

That 90-year decommissioning process is, by the way, the accelerated version and Magnox are quite proud of their innovative work at Trawsfynydd. It was originally going to take 135 years.

There’s something striking about Trawsfynydd. The scale and bulk of it make it almost iconic, a monument to the arrogance and ambition of the nuclear age. If we weren’t insisting on building more of them, leaving those towers to go quietly to ruin would be an appropriate memorial and warning. Instead, they’re just a precursor of what Hinkley C will be in due course – especially if, as I believe, Hinkley will be obsolete before it is ever completed. Hinkley should be easier to clean up, as decommissioning has actually been planned in advance rather than made up afterwards. But it will still be long, expensive, and taxpayer-funded into the distant future.

There is, however, one potential new chapter to Trawsfynydd. The site could be used to test small modular reactors, which many consider to be a better investment than mega-projects like Hinkley. Smaller reactors are possible, as demonstrated by nuclear ships and submarines. Making them modular would, for the first time, allow us to truly capture the learning from nuclear power and create some economies of scale. It would make nuclear power affordable in ways it will never be otherwise.

If it goes ahead as a test site for mini-reactors, then strangely enough it may be the incongruous Trawsfynydd, rather than Hinkley Point, that turns out to be the future of nuclear power in Britain.

1 comment

Leave a Reply

Fill in your details below or click an icon to log in: Logo

You are commenting using your account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: