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The UK Health and Safety Executive (HSE) have responded to queries from the Celtic League about problems with cracks in some of the graphite bricks which line the reactor core at nuclear power plants.
They identify Heysham power station has sustaining this difficulty but have not included any substantial information saying that the reports produced are "closed" - although a possible avenue for access via Freedom of Information legislation is indicated.
The League have previously highlighted these safety concerns over Heyshams reactors - see Celtic News Nos:
2027 NUCLEAR POWER PLANTS - ARE THEY CRACKING UP? - Oct 23, 2006 866 NUCLEAR PROBLEMS - Sep 9, 2002 634 HEYSHAM NUCLEAR INCIDENT - Feb 9, 2002
The HSE also say that no problems in relation to cracking of the grapite brick lining of the reactor core has ocurred at Wylfa. However the League unbderstand that a separate problem with weld cracks in the reactor at that station has caused problems.
Finally the HSE set out in some detail why they do not publish details of the many unscheduled reactor shutdowns which occur annually at British nuclear plants.
The correspondence from the HSE is set out below the points a-e are the questions posed by the League:
"Date: 30 November 2006 Reference 1/NUC 120/4/1 pt 56
Dear Sir
With reference your enquiry to Dr Mike Weightman regarding Graphite Cracks at Nuclear Power Stations. Your request has been passed to me to coordinate a response.
In order of your questions raised:-
a) Can we ask when this phenomena was first identified and if at the time a report about these problems was made public?
As with all structural components graphite will change with time. For a gas cooled reactor it was recognised this may result in some grahite cracking during its operational life. Therefore to ensure that plant, equipment and materials continue to meet their safety function the Nuclear Site Licence requires licensees to carry out routine inspection, examination, monitoring and testing of these components.
For graphite NII requires the licensee to have in place on line monitoring arrangements, inspection programmes, and material testing regimes.
The licensees consider information from these activities in their routine reviews of the safety case for continued operation. The safety case for continued operation is then submitted to NII for its consideration. If NII were not satisfied with the safety case it would not allow a reactor to continue to operate. A typical example of reactor shutdown due to a satisfactory case on graphite not being made is Oldbury Reactor I and 2.
To encourage discussion on graphite a conference sponsored by HSE and industry was held in November 2005, on "Ageing Management of Graphite Reactor Cores" at the University of Cardiff where there was opportunity for public debate of these issues. I enclose a copy of the paper presented by HSE at this meeting. (Annex 1)
b) In addition how many nuclear plants are currently experiencing this problem and what are the safety implications for their continued operation?
As indicated in response to a) NII continues to review the licensees safety submissions for continued operation. If NII were not satisfied with the safety case it would not allow a reactor to continue to operate.
c) Could you say when each nuclear power station was originally commissioned and what the original planned operating life for each of plants was?
Please see the table below giving the current lifespan of plants proposed by UK licensees.
(Set out below - Station Name - Start Date - Expected end of life date)
Dungeness "B" Apr-83 2018 Hartlepool Aug-83 2014 Heysham I Jul-83 2014 Heysham2 Jul-88 2023 Hinkley "B" Feb-76 2011 Hunterston "B" Feb-76 2011 Torness May-88 2023 Wyfla May-71 2010 Dungeness"A" 1966 2006 Oldbury 1968 2008 Sizewell"A" 1966 2006 Sizewell "B" 1995 2035
d) In relation to a & b above can you confirm if cracking of graphite bricks in the reactor core has been identified at either Heysham or Wylfa power stations and if so is any report by HSE/NII available publicly
Limited graphite brick cracking has been found at Heysham, but none at Wylfa. NII has reviewed the safety case for Heysham and is satisfied reactor operation should continue. Reports regarding the limited graphite brick cracking at Heysham have been produced but these are closed documents. You may be able to have sight of the report by requesting to HSE under the Freedom of Information Act. Further information regarding Freedom of Information is available at HSE Web page at: www.hse.gov.ukffoi/
e) Can you explain why the quarterly bulletins issued by HSE do not record unplanned shutdowns (reactors trips) at UK nuclear plants?
The basis for inclusion in the Quarterly Statement of incidents are the Ministerial reporting criteria (Goodlad criteria), which are:
a. Dangerous occurrences reportable under the Nuclear Installations (Dangerous Occurrences) Regulations 1965.
b. Confirmed exposure to radiation of individuals which exceed, or which are expected to exceed, the dose limits specified in Schedule 4 to the lonising Radiations Regulations 1999.
c. Examination, inspection, maintenance, test or operation of any part of the plant revealing that the safe operation or condition of the plant may be significantly affected.
d. A confirmed breach of, or discharge expected to breach quantitative limits of a Certificate of Authorisation for the disposal of radioactive waste issued under the Radioactive Substances Act 1993.
e. Abnormal occurrences leading to a confirmed release to atmosphere or spillage of a radioactive substance which exceeds or is expected to exceed, the limits set out in Column 4 of Schedule 8 of the lonising Radiation Regulations, 1999, except where the release is in a manner specified in an Authorisation under Radioactive Substances Act 1993.
f. Abnormal occurrences leading to a release or suspected release or spread of radioactivity, on or off site, which requires special action or special investigation by the Operator.
Unplanned reactor trips generally do not meet the above criteria. I trust that your queries have been satisfactorily addressed.
Yours faithfully,
Mike Jennions On Behalf of Nuclear Installations Inspectorate."
Because of its size the Annex (1) document referred to in the above correspondence is not included with this posting.
J B Moffatt Director of Information Celtic League
09/12/06
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