exclusive, 25 May 2011
British nuclear plants could be vulnerable to terrorist attacks, power failures, severe natural disasters and hydrogen explosions, according to evidence from industry experts submitted to the government’s review of nuclear safety after the Fukushima accident in Japan.
Submissions to the review, being conducted by the head of the newly-formed Office for Nuclear Regulation, Dr Mike Weightman, were published online last week but have since been withdrawn. They highlight a series of previously unpublicised concerns from nuclear insiders.
In one submission, Robert Quayle, who says that he was for 15 years a member of the emergency response team at the Sellafield nuclear complex in Cumbria, warns of the dangers of terrorists causing a power blackout. They could do this, he says, by disabling back-up power systems and downing pylons without breaching the site security fence.
That would mean that emergency diesel generators would have to be brought in from Manchester or Newcastle to keep vital safety systems going, which could take hours. According to Quayle, who is now a consultant to the engineering company, Babcock, this scenario was apparently discussed by engineering teams at Sellafield “some years ago”.
He concludes: “It was considered that there is the potential for severe damage that could readily and easily be caused, without gaining access to the secure areas, and the impact would not only be to the site but also the surrounding areas.”
Other expert submissions to the Weightman review warn of the dangers that floods or other severe events could trigger power failures. According to a 30-page report from the management consultants, Serco, who help run Britain’s nuclear bomb factory at Aldermaston in Berkshire, vital emergency cooling systems could fail.
“An event (or combination of events, which might be linked) sufficiently severe to disable both offsite and onsite power could well be severe enough to disable a complex engineered solution,” says the Serco report.
“It could also affect storage locations for equipment. Thus the normal UK approach, of having an engineered solution, might not be effective.”
Sean Moules, an engineer from the government's Nuclear Decommissioning Authority (NDA) writing in a personal capacity, is worried that the power lines at nuclear sites would be damaged by a major flood. “I have seen a number of elevated external cable runs on various sites, that are functional under normal circumstances but would not survive contact with very large debris,” he says.
“Some sites are clearly more prone to flooding than others, and for non-generating sites the risks from loss of power could be quite manageable, but perhaps this area should be considered for more exposed sites where inundation leading to potential power loss could create more hazardous outcomes.”
A submission from Babcock, which runs the nuclear submarine base at Faslane on the Firth of Clyde and many other military sites, highlights the risks of extending the lifetimes of Britain’s older reactors. There are two old Magnox stations still running at Oldbury in South Gloucestershire and Wylfa in north Wales, plus seven advanced gas-cooled reactor (AGR) stations (Torness in East Lothian, Hunterston in North Ayrshire, Heysham 1 and 2 in Lancashire, Hartlepool on Teeside, Hinkley Point in Somerset and Dungeness in Kent).
“These facilities have not been designed to modern seismic safety standards and planned emergency responses to events may not have considered a sequence of severe events, which is what has happened at Fukushima,” says Babcock.
“The events in Japan have highlighted a sequence of events where recovery of power was not possible for an extended length of time; even compared to the time periods for severe accidents to progress in AGRs.”
Another NDA manager, Michael Slater, expresses concern in a letter to Weightman about the dangers of explosions from the build-up of hydrogen in light water reactors (LWRs) like the one at Sizewell in Suffolk.
“If this gas build up was due to the operator venting the system to relieve excess pressure then this raises a serious question about how the secondary containment of a LWR is designed to deal with such an event,” he says.
“Its main purpose is to prevent release to atmosphere, but how is a hydrogen build up within it prevented? Ideally there would be an engineered vent, but this would also compromise the containment function.”
The Office for Nuclear Regulation (ONR) posted 74 submissions to the Weightman review on its website when its interim report on Fukushima was published on 18 May. But two days later all the submissions were pulled after complaints were made about some of the personal information they contained.
According to the ONR, the plan had always been to publish all the submissions online. “This happened, in full, shortly after publication of the interim report on 18th May,” said an ONR spokesman.
“We then noticed that some contained information, such as ONR staff email addresses and signatures, which we had not intended to publish. We decided to take the submissions offline to remove these and expect to have them back on the website within days.”
The submissions made to the Weightman review referred to in this article can be downloaded here: Quayle (33KB pdf); Serco (3.2MB pdf); Moules (12KB pdf); Babcock (29KB pdf); and Slater (12KB pdf).
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