30th December 2007

Read Cllr Philip Booth's letter calling for Oldbury's closure now

Photo: Chernobyl fallout applied to Oldbury - see recent talk by John Large about how possible that could be - see here

I write to condemn proposals to delay key maintenance at the ageing Oldbury nuclear power station for twelve months (i).
 
In May Reactor 2 was restarted after two years of inspections and closed almost immediately after a large explosion in the generator/transformer that was heard and seen in Oldbury village. A second attempt to restart failed in July when a turbine began vibrating. The 39 year old reactor was eventually started in August and is due for an inspection shut-down in January. Now the industry wants to delay that until after the reactor's permanent closure at the end of 2008.
 
These are very serious and worrying incidents but of greater concern is the state of the oldest and most corroded reactor core in the country. The Nuclear Installations Inspectorate writing to the Shut Oldbury Campaign state that "a key aspect of the NII decision regarding deferment of the outage is the graphite core safety case." Yet without shutting down the reactor it's impossible to gauge whether cracks have developed in the core.

The regulators said in June they couldn't licence the reactor till the end of 2008 (iii). For Oldbury to now make this request is outrageous and could have unthinkable consequences especially as they still haven't fitted a key extra safety system (ii).

Meanwhile Reactor 1, that is even more damaged, has been out of service since August 2006 awaiting similar test results. Shutting Oldbury finally now is the only safe option.
 
Cllr. Philip Booth, Stroud District Green Party.




Notes:

(i) Paragraph in a letter from Nuclear Installations Inspectorate dated 18th December 2007: Shut Down Dates -
Currently the company is expected to shut down reactor 2 for maintenance at the end of January 2008. However, in the light of the small operating period since the commencement of the last outage, the company has applied to the NII for permission to postpone certain aspects of maintenance to allow the reactopr to continue operation to the end of December 2008. a key aspect of the NII decision regarding deferment of the outage is the graphite core safety case.
 
(ii)  "The only other method for guaging the strength or weakness of the graphite material is to drill out samples and test them. But this is a much more generalised technique from which information is extrapolated. It is not specific enough to pin-point crucial areas of damage."

(iii) Scroll down for Nuclear Installations Inspectorate reference on reactor safety or read the detail in this June press release and Independent on Sunday article.

Shut Oldbury Press Release:

17 June 2007

Cautions overuled in Oldbury report

An internal report (1) 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.

The same safety document reveals that a new safety system should be installed (2) which could take two years to fit and an automatic 'trip' system is periodically suspended (3). 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." (5)

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 (6). 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.(3)

The report predates a fire on 30th May which occurred in one of the transformers linked to the reactor, forcing it to shut down rapidly and possibly indefinitely (4). 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."

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."

"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 overruled. 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.

Jim Duffy, Shut Oldbury Campaign, Stop Hinkley, 07968 974805   



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.


Note 1. "Return to service of reactor 2 following statutory outage", HSE, HM Nuclear Installations Inspectorate, May 2007

Note 2. 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."

JD: 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 potentially spreading to adjacent nuclear fuel channels through cracks in the corroded reactor material. The 'Magnox' magnesium cladding can burn in as little as 900 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."