Health and Safety
Executive / Commission
Nuclear
LLC reports
This report is issued as part of the Health and Safety Executive's commitment to make information about inspection and regulatory activities relating to the above site available to the public. It is for distribution to members of the Hunterston Site Stakeholder Group (SSG) and covers activities associated with the regulation of safety at Hunterston B Nuclear Power Station. These reports are distributed quarterly and are also available on the HSE’s web site. Site Inspectors of HM Nuclear Installations Inspectorate attend SSG meetings and will respond to questions raised there by members of the SSG. Any other person wishing to inquire about matters covered by this report may contact the HSE’s Nuclear Directorate Information Centre on 0151 951 4103.
http://www.hse.gov.uk/nuclear/llc/index.htm
The site inspections carried out this quarter were primarily in connection with the three-yearly shutdown of Reactor 4 for statutory maintenance and inspection purposes.
The HMNII Site Inspector made the following planned visits during the period:
7 – 8 April
17 – 20 May
1 – 2 June
13 – 17 June
In April the Site Inspector was joined by two other inspectors to witness exercise ‘SOAY’, which was a partial re-demonstration of the annual emergency exercise that had taken place in November 2004.
Inspections are undertaken for the purpose of monitoring compliance with the conditions attached by HSE to the nuclear site licences, and other relevant provisions of the Health and Safety at Work etc Act 1974, including the Ionising Radiations Regulations 1999.
The routine inspections for this quarter, covering a range of aspects of plant operation, maintenance, and management were completed. Reactive inspection has also been carried out, with the more significant items reported below. In areas where opportunities for improvement were identified, remedial work has been agreed with station management, with the intention of achieving improvements to current station arrangements.
Reactor 4/Turbine 8 was shutdown on Friday 24th June 2005th to carry out three yearly statutory maintenance, inspection and testing activities.
It was reported in the NII’s last quarterly report that British Energy wished to complete the integration of the headquarters and technical support functions of the two licensees by having the Scottish sites re-licensed to BEGL.
NII assessed BEGL’s application and consulted with the Scottish Environment Protection Agency. This provided the basis for a decision by HM Chief Inspector of Nuclear Installations on the granting of the new licence.
A new licence for Hunterston B was signed on 27th June 2005 and this came into force on 1st July 2005.
Shift exercise ‘Soay’ on 8 April 2005 was intended to provide a further, partial demonstration to NII of the activities within the Alternative Access Control Point (AACP) following the Hunterston B level 1 emergency exercise ‘Staffa’ which was observed by NII on 4 November 2004
Overall, NII considered that the station adequately demonstrated the use of the AACP during this shift exercise.
For the forthcoming annual demonstration level 1 emergency exercise, scheduled for November 2005, NII’s expectation is that HNB’s emergency arrangements will be based upon the new permanent fixed ACP facility; and that this will be demonstrated formally.
A consolidation of the boiler tube safety case for Hunterston B identified reasonably practicable modifications for enhancing the ability of the gas circulators to withstand moisture, to reduce the risk of gas circulator failure as a direct consequence of boiler tube leaks.
Safety documentation was submitted to NII in support of an application for our agreement to the implementation of modifications.
NII responds to non-routine events that may affect safety. As part of inspection activities at the site, we investigate safety related events that occur and follow-up those which are perceived initially to have the potential to be more significant. In particular, we examine the licensee’s response to such events. From our inspections in this quarter we were satisfied that the response by the station has been in accordance with appropriate arrangements.
Four events rated level 1 on the International Nuclear Event Scale (INES) were followed up during the reporting period, viz.
On 28 April 2005 during the transfer of a redundant UHPU into a storage position, the wire rope sling failed which caused it to fall approximately 4 metres. The UHPU is a component approximately 10 metres long, weighing about one tonne. The direct consequences of this event were confined to minor damage to floor plating – there were no injuries to personnel. As a conservative measure the station decided to undertake a controlled shutdown of Reactor 4
The station’s detailed investigations confirmed that the dropped UHPU had resulted from it becoming snagged on adjacent steelwork owing to poor control of the lifting operations.
A misalignment was discovered on the RACW system of Reactor 3. It was discovered that, following maintenance, the control selector for a valve had been left in the closed position and on local rather than automatic control.
This misalignment meant that the standby system would not have automatically started and fed if duty pump had failed.
A nuclear safety related fire door between the Mulsifyre System Pump Plant Room and the turbine hall was found to be open and unattended. The reason for this was identified as being the routing of a temporary drain tube to allow water from a leaking water pipe to be directed to an installed drain. Action was immediately taken to re-direct the drain tube, close the door and contact the Central Control Room.
Persons responsible for this violation received additional training on the importance of ensuring that nuclear fire safety barriers were not breached.
During routine removal of a Control Rod Actuator (CRA) from Reactor 3 it was noted that no shield plug had been fitted. This CRA was first loaded into the Reactor in 1997. During this period the control rod had performed satisfactorily with no indication of unusual rod-drop characteristics.
In the above four events, the station’s investigations and the corrective actions taken were considered to be appropriate by NII and no regulatory action was judged to be necessary.
Under Health and Safety legislation the Site Inspector, or other HSE Inspectors, may issue formal notices to secure improvements to safety. No such notices were issued during the reporting period.
As part of its regulation under nuclear site licences NII issues regulatory documents, collectively termed Licence Instruments. Three Licence Instruments were issued to Hunterston B during the quarter, viz.
Nuclear Site Licence Sc11 – British Energy Generation (UK) Limited
Nuclear Site Licence Sc13 – British Energy Generation Limited
HM Nuclear Installations Inspectorate July 2005
St Peter’s House
Stanley Precinct
Bootle
Merseyside
L20 3LZ