§ Mrs. Ann CryerTo ask the Secretary of State for Transport, Local Government and the Regions (1) whether the recent discovery of radiolytic corrosion in the graphite moderators of UK Magnox reactors will result in premature closures; [34002]
(2) if he will make a statement on the recent events leading to the closure of the nuclear reactors at (a) Chaplecross and (b) Calder Hall; [34003]
287W(3) what discussions he has had with his colleague the Secretary of State for Health regarding safety actions which the Health and Safety Executive's Nuclear Installations Inspectorate will undertake in relation to graphite depletion in UK Magnox reactors. [34001]
§ Mr. Wilson: BNFLhas announced its strategy for the Magnox stations including maximum operating lifetime limits for each station. Details are set out in the company' s annual report and accounts for 2001. Subject to annual reviews, and provided it remains safe and economic to do so, BNFL intends to operate each of the reactors up to a 50 year lifetime. This means the latest closure date for the four reactors at Calder Hall falls between 2006 and 2008 and for the four at Chapelcross the latest closure dates fall between 2008 and 2010. It is a matter of commercial judgment for BNFL as to whether or not any factors might arise which might make it uneconomical to continue operating any reactor up to its maximum lifetime limit.
The phenomenon of graphite weight loss (referred to in my hon. Friend's questions as radiolytic corrosion and graphite depletion) in Magnox reactors, resulting from the irradiation and heating of the graphite during reactor operation, is well known to both BNFL and HSE's Nuclear Installations Inspectorate (NII). This affects most of the Magnox stations and is monitored closely to ensure that it does not lead to any problems of safety significance. Graphite weight loss is not a significant issue for the reactors at Chapelcross or Calder Hall as these reactors operate at a lower temperature.
At the start of the routine annual outage of Reactor 1 at Chapelcross at the end of August 2001, BNFL discovered that a number of chargepans on top of the reactor had moved out of alignment. This occurrence is related to the well-understood phenomenon of radiation-induced graphite shrinkage which is a separate matter from graphite weight loss. As the four reactors at Calder Hall are of the same design as Reactor 1 at Chapelcross, BNFL decided, in consultation with HSE, to carry out inspections of these reactors too as these reached their next scheduled outrages. All four reactors at Calder Hall are now shut down. They will not be returned to operation until BNFL and the HSE are satisfied that it is safe to do so. This includes the requirement that the issue of misaligned chargepans needs to have been effectively addressed. This is also the case for Reactor 1 at Chapelcross.
Reactors 2, 3 and 4 at Chapelcross have different design features which means that they are less susceptible to graphite shrinkage. They have not been affected by the misaligned chargepans problem. Reactor 3 at Chapelcross was shutdown in July due to the incident that took place during a fuelling outage when a failed grab in the defuelling machine led to a basket of spent fuel being dropped. Having received Consent from the HSE, BNFL has now restarted Reactor 3. Reactor 2 at Chapelcross is operating and Reactor 4 was shut down at the end of January for its planned annual maintenance outrage. Currently, BNFL is awaiting approval from the HSE to resume refuelling operations at Chapelcross.
288WMatters relating to nuclear safety fall to my right hon. Friend the Secretary of State for Trade and Industry. Neither the issue of graphite weight loss nor that of graphite shrinkage has been discussed with my right hon. Friend the Secretary of State for Health.