The Windscale Piles were the first large-scale reactors in the UK. Their crude design and operation must be viewed in the political context of the early Cold War era and the policy of the UK Government to quickly build up an independent nuclear deterrent.  While the first Magnox reactors at Calder Hall and Chapelcross had a dual military and electricity generation function, all other power reactors in the UK have been solely for electricity generation. Because of the design and construction of modern reactors and the sophisticated safety features now built in, a similar accident could not happen. However, the Windscale accident happened because of faulty design and operator error, as in the Chernobyl accident 29 years later, while the 2011 accident at Fukushima Dai-ichi demonstrated the importance of defence in depth.