17th June 2007

The Independent on Sunday today reveal shocking risks taken at Oldbury (pictured) - click 'Read More' to see Green party comment

An internal report (i) revealed under the Freedom of Information Act shows that a nuclear reactor at Oldbury is unsafe to operate through to its planned closure date of December next year but despite cautions concerning a nuclear fire is allowed to operate for six months. (Please note the following background information is from Jim  Duffy from the Shut Oldbury Campaign and  Stop Hinkley)

See here for most last weeks press release re fears about new management at Oldbury and here re the fire at the plant last month

The same safety document reveals that a new safety system should be installed (ii) which could take two years to fit and an automatic 'trip' system is periodically suspended (iii). But despite these concerns reactor 2, which has already been closed for two years for nuclear safety reasons, was still recently allowed to restart on a temporary basis till November this year when a new safety case must be made.

The graphite reactor core is at the centre of concerns by the regulator who states: "Due to uncertainties relating to: measurement of [graphite] density; prediction of weight loss; and predictions of structural integrity I am currently unable to recommend operation to the planned end-of-generation." (v)

The statement goes on to allow a short term restart till this November on the judgement that the risk of a nuclear fuel fire or 'clad-melt' for the period is one chance in a thousand (vi). Clad-melt risk for nuclear power stations is expected to be one chance in ten thousand or higher. Nuclear Consultant John Large describes the risk as 'unacceptably high'.

Another part of the report reveals that periodic tests are being conducted at the reactor with the suspension of an automatic trip system, leaving a 'time window' during which a fuel fire could escalate to multiple fuel channels (iii).

The report predates a fire on 30th May which occured in one of the transformers linked to the reactor, forcing it to shut down rapidly and possibly indefinitely (iv). The 'trip' shut down may have caused extra damage through stress to the already heavily corroded reactor core making a future accident more likely. The explosion was heard in the village of Oldbury where a plume was seen rising from the reactor.

Nuclear consultant John Large said: "I'm disturbed by this report. If the reactor is said to be unsafe to operate for its last eighteen months then it's highly unlikely to be safe for six months."

Green party comment

Cllr Philip Booth, a local District councillor and spokesperson for Stroud District Green party said: "Greens welcome this story is now getting national coverage (vii). It is quite shocking that despite the Nuclear Installation Inspectorate (NII) casting doubts on the nuclear company's ability to cope with exceptional circumstances they still allowed the reactor to start up last month. Documents released under the Freedom of Information Act show that there was a one-in-1,000 risk of a fire in the highly radioactive nuclear fuel yet the plant has been restarted. This is wholly unacceptable. We must immediately and permanently close this 39 year old dinosaur that is the oldest and most corroded reactor in the country."

Jim Duffy spokesman for the Shut Oldbury campaign said: "The documents reveal on one hand that Oldbury is essentially finished, as required safety work is impossible, but on the other hand that the regulators have astonishingly relaxed their stance to let it splutter on for a few more months' worth of electricity. There is a serious question here as to whether the regulators have allowed an economic argument to slip into what should be a pure safety case."

Jim Duffy continued: "The oldest and most corroded reactor in the country should not be subject to this level of relaxation of standards. Despite being heavily censored, the safety report was dotted with examples of cautions being overuled. The recent generator explosion, heard in the village of Oldbury, was a warning that the unexpected can happen and we can now only guard against that by the reactor's permanent closure.

Notes:

(i) "Return to serice of reactor 2 following statutory outage", HSE, HM Nuclear Installations Inspectorate, May 2007

(ii) HSE Nuclear Safety Directorate Assessment Report: a Revised Safety Case for the integrity of the Graphite Cores to the Planned End of Generation: Proposal for Return to Service of Reactor 2 (NP/SC 4927):  Recommendations: 37."[NII] should continue to press for the installation of the Failed Fuel Trip System as a potential ALARP option to improve safety at the station."

Jim Duffy from Shut Oldbury comments: "The Failed Fuel Trip System differs from the Burst Clad Detection System and has the advantage it could trip the reactor automatically much earlier in the event of a fuel fire in just one fuel channel. A fuel fire could take hold in as little as thirty seconds spreading rapidly to adjacent nuclear fuel channels through cracks in the corroded reactor material. The 'Magnox' magnesium cladding can burn in as little as 700 degrees C even in the carbon dioxide cooling gas."

A nuclear expert suggests this safety system could take two years to fit.) HSE Nuclear Safety Directorate Assessment Report: a Revised Safety Case for the integrity of the Graphite Cores to the Planned End of Generation: Proposal for Return to Service of Reactor 2 (NP/SC 4927): Recommendations: 37."[NII] should continue to press for the installation of the Failed Fuel Trip System as a potential ALARP option to improve safety at the station."

Jim Duffy from Shut Oldbury comments: "The Failed Fuel Trip System differs from the Burst Clad Detection System and has the advantage it could trip the reactor automatically much earlier in the event of a fuel fire in just one fuel channel. A fuel fire could take hold in as little as thirty seconds spreading rapidly to adjacent nuclear fuel channels through cracks in the corroded reactor material. The 'Magnox' magnesium cladding can burn in as little as 700 degrees C even in the carbon dioxide cooling gas."

A nuclear expert suggests this safety system could take two years to fit.

(iii) "Oldbury Power Station Graphite Brick Cracking, Role of the Operator" HSE Nuclear Directorate 60/07   3. Conclusions and Recommendations: "For the 'majority' case the claimed human reliability has been demonstrated. For the 'exception' cases I cannot support a reliabilty claim of the operators. Therefore the station may wish to consider: ...the suspension of the automatic trip rule...[which] may have a consequential effect on the time for operator actions; the 'cliff edge' associated with the time for fault escalation to multiple channels."

Jim Duffy from Shut Oldbury comments: "It appears that suspending the automatic trip function relating to the Burst Clad Detection System is permitted by the regulator. The BCD System would normally trigger an automatic shut-down of the reactor in the event of a nuclear fuel fire, detected by loose fission particles in a general area of the reactor, although with a potentially devastating one to 12 minute delay. This is periodically suspended during alarm tests. The regulator doubts the safety of this process."

(iv) BBC News report: 2nd June 2007

(v) HSE Nuclear  Directorate Assessment Report: Review of the Safety Case for the Integrity of  the Reactor 2 Graphite Core, Conclusions 5.

(vi) Ditto, Conclusions  6.  

(vii) The Independent on Sunday article:

Revealed: faulty nuclear reactor was allowed to operate without safety alarm

By Geoffrey Lean, Environment Editor

Independent on Sunday  17 June 2007


Britain's nuclear watchdog last month allowed a faulty nuclear reactor to start up even though it had not been fitted with an important safety system, startling internal documents seen by The Independent on Sunday reveal.

The documents also show that the Nuclear Installation Inspectorate (NII) judged that the reactor, at Oldbury nuclear power station in Gloucestershire, was not safe enough to operate for the next 18 months, but allowed it to go onstream until November anyway.

The revelations - described as "deeply alarming" by top nuclear expert John Large yesterday - are bound to fuel concern at a time when ministers are encouraging the building of a new generation of reactors.

The heavily censored documents - released under the provisions of the Freedom of Information Act to the Stop Oldbury campaign - come from an investigation into the safety of reactor 2 at the power station. They reveal a one-in-1,000 risk of a fire in the highly radioactive nuclear fuel, a figure that Dr Large regards as "unacceptably high".

They show that the NII pressed for the installation of a safety system, called "a failed fuel trip system", which would automatically shut down the reactor if such a fire broke out. But it accepted the response of the power station's operator, the British Nuclear Group, that "it would be disproportionate to further delay the return to service of the reactor" while it was fitted.

The NII also cast doubt on the company's ability to cope with exceptional circumstances. But the watchdog still allowed the reactor to start up last month and operate until November. In the event, within two weeks an unrelated fire broke out in a non-nuclear part of the plant, and the power station had to be shut down indefinitely.