Expert warns of risk in UK's Cumbria plant

An American nuclear expert has warned that Westinghouse's proposed reactor for Cumbria needs a $100m (£68m) filter to safeguard against a leak that would turn the region into "Chernobyl on steroids".

Arnie Gundersen lifted the lid on safety violations at a nuclear firm in 1990 – he claimed to have found radioactive material in a safe – and was CNN's resident expert during the Fukushima nuclear disaster in Japan in 2011.

Gundersen told The Independent that he is concerned by designs for three reactors proposed for a new civil nuclear plant in Cumbria. A nuclear engineering graduate by background, Gunderson believes that the AP1000, designed by the US-based giant Westinghouse, is susceptible to leaks. The reactor has been selected for the proposed £10bn Moorside plant, a Toshiba-GDF Suez joint venture that will power six million homes. It is going through an approval process with the Office for Nuclear Regulation.

Gundersen, who visited the Sellafield nuclear facility in Cumbria last week, warned that any leak would be like "Chernobyl on steroids", referring to the 1986 nuclear disaster that killed 28 workers within four months. He passed on some of these fears to MPs at an event in Parliament during his visit to the UK.

He said: "Evacuation of Moorside would have to be up to 50 miles. You could put a filter on the top of the AP1000 to trap the gases – that would cost about $100m, which is small potatoes.

"If this leaks it would be a leak worse than the one at Fukushima. Historically, there have been 66 containment leaks around the world."