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 CHAPELCROSS Local Liaison Committee (LLC) and covers activities associated with the regulation of safety at CHAPELCROSS. Site Inspectors of HM Nuclear Installations Inspectorate attend LLC meetings and will be happy to respond to any questions raised there by members of the LLC. Any other person wishing to inquire about matters covered by this report should contact the HSE, Nuclear Directorate Information Centre on 0151-951-4103.
1. The Site Inspector made the following visits during the period:
| 5-6 July 2001 | 17 January 2002 |
| *9-12 July 2001 | 31 January 2002 |
| *13-20 July 2001 | 6-8 February 2002 |
| 2 August 2001 | 14 February 2002 |
| 28-29 August 2001 | 20 February 2002 |
| 11 September 2001 | 28 February 2002 |
| 20 September 2001 | 11-13 March 2002 |
| 26-28 September 2001 | 21 March 2002 |
| 9 October 2001 | 27 March 2002 |
| 18 October 2001 | 10-11 April 2002 |
| 31 October -1 November 2001 | 17-18 April 2002 |
| 15 November 2001 | 24 April 2002 |
| 26-27 November 2001 | 8 May 2002 |
| 4 December 2001 | 22-24 May 2002 |
| 14 December 2001 | 13-14 June 2002 |
| 18 December 2001 | 18 June 2002 |
| 9-10 January 2002 | 25-27 June 2002 |
* A number of NII inspectors went to Chapelcross to investigate the dropped fuel discharge basket incident and to monitor BNFL's handling of that incident.
2 Routine Planned Inspections were carried out during the year. Such inspections enable the Inspectorate to judge whether a Licensee is complying with the conditions attached to a site licence, and any other relevant statutory provisions on a sampling basis. The Site Inspector was satisfied from the sample inspections undertaken that Chapelcross had shown satisfactory compliance.
3. Visit by HM Chief Inspector of Nuclear Installations: Mr L G Williams, HM Chief Inspector of Nuclear Installations, visited Chapelcross on 27-28 September. This was a routine visit carried out as part of a programme of visits to nuclear licensed sites made by the Chief Inspector. A number of issues that were current at Chapelcross including the recent incidents (see below) were discussed with Chapelcross staff and the Chief Inspector inspected the plant. Mr Williams was pleased with the actions being taken by Chapelcross to improve the plant.
4. Ionising Radiations Regulations: A Specialist NII Inspector carried out inspections to examine Chapelcross's compliance with the 1999 revision of the Ionising Radiations Regulations. There were a number of areas where Chapelcross needed to provide a stronger demonstration of compliance with some key aspects of the Regulations, particularly with respect to radiological risk assessments. The shortfall was partly due to a shortage of specialist staff. Chapelcross responded positively to the findings and has made commitments to improve compliance and address the staffing issue.
5. Reactor Pressure Circuit: A specialist inspector observed BNFL's inspection of a gas outlet duct nozzle to reactor pressure vessel weld inspection using an ultrasonic inspection technique delivered by a robot arm. The weld is an important part of the pressure circuit and following the finding of a defect at Calder Hall, BNFL had properly brought this programme of inspections forward. We were satisfied with the inspections, and with BNFL's findings that had shown that there were no defects of significance that would prevent continued operation.
6. Chapelcross's Improvement Programme: The NII expects licensees to continually make improvements in their arrangements for compliance with the site licence to ensure that the arrangements continue to meet modern standards and expectations. Chapelcross has in place an improvement programme to achieve this. The NII has monitored Chapelcross's progress in meeting this programme, and periodically, reviews the whole programme with the licensee at Annual Review Meetings which are attended by the Site Inspector and the Superintending Inspector. We have been satisfied with the progress made to date.
7. Emergency Arrangements: As part of its improvement programme, Chapelcross responded to NII advice and included improvements to some of the equipment and facilities required for it to meet its emergency plan. For example, it has recently installed a new Emergency Plume Gamma Monitoring System which is of a modern standard, to provide immediate forewarning of a release of radioactivity. On the site, it has built the first of two permanent, dedicated Access Control Point facilities. In an incident licensees use Access Control Points to manage the teams on the ground who carry out for example rescues, and as such, the success of the licensee's response is dependent upon the performance of this facility.
Chapelcross installed the new Access Control Point in time for its annual Level 1 demonstration exercise. This is the station's annual emergency exercise which the NII observes. The NII team were impressed with the improved facilities and equipment, and particularly with casualty handling where the new facilities allowed staff to show their skills. Also observed, were the good working relationships between Chapelcross and the local emergency services who make a significant contribution to Chapelcross's emergency response. Overall, the NII concluded that Chapelcross had successfully demonstrated its emergency arrangements to cope with the scenario for the exercise. Valuable learning and improvement points were also identified by Chapelcross, and the NII was satisfied that Chapelcross intended to implement these.
8. Conventional Safety: An inspection of conventional safety was carried out at Chapelcross in June 2002 by a HSE Inspector. The HSE has been running a campaign, Revitalising Health and Safety, which sets targets for improving health and safety performance over the next 10 years (for example, to reduce the number of working days lost from work related injury and ill health by 30% by 2010) The inspection examined a number of these issues at Chapelcross, particularly, working at height and safety from traffic movements on site. Generally, the Inspector was satisfied that Chapelcross was aware of the issues and was taking steps to improve the protection of its employees. Also, the Chapelcross Safety Representatives have a number of initiatives underway seeking to continue to improve health and safety at Chapelcross, and it was welcome that this was being encouraged by Chapelcross management.
9. Essential Electrical Supplies: A Specialist NII Inspector led an inspection of Chapelcross's essential supplies system over three days. The essential supplies system is an important nuclear safety system, and as its name implies, it is to guarantee that there is sufficient electricity for plant and instrumentation needed to maintain a safe shutdown in the event that the grid supply of electricity is lost. The inspection found that although much of the equipment dates to start-of -life at Chapelcross, it was being well maintained and kept in good condition to ensure that it should meet the requirements of the safety case. Also, staff showed a thorough knowledge of the system.
10. Safety Circuits: A Specialist NII Inspector led an inspection of the control and instrumentation aspects of Chapelcross's safety circuits. The safety circuits are a vital component of nuclear safety. They comprise a series of diverse detectors and monitors which trip the reactors automatically should the circumstances arise, and ensure that the reactors operate within the safe operating envelope defined by the safety case. Their operation and maintenance were the focus of this inspection. Overall, the inspection revealed that Chapelcross had a good knowledge of the systems and that they were being well maintained.
11. Dropped Discharge Fuel Basket Incident: A large part of the Inspectorate's work in the last 12 months at Chapelcross has been concerned with the dropping of a basket of discharged irradiated fuel on 5 July 2001. The NII investigated this incident and found that no worker or member of the public incurred any harm from release of radioactive material. The investigation identified the likely cause of the event, and established that there was no deliberate attempt at deception with respect to reporting events or status of plant. The NII investigation produced several recommendations to improve the safety of the defuelling operation, and BNFL made a positive response and implemented a programme to address these. BNFL's progress in meeting the programme is being monitored as part of NII's normal process of regulation. Should progress be inadequate, NII will not hesitate to use its enforcement powers to ensure that safety is maintained.
The investigation, its findings and recommendations were published in February 2002 in a HSE report entitled: "An investigation into a dropped fuel element incident at Chapelcross Nuclear Power Station." Members of the LLC were sent copies of this report and it is available on the HSE web site at www.hse.gov.uk/nuclear/index.htm.
The NII's priority after the incident was to ensure that BNFL safely recovered the 12 elements still in the discharge machine on Reactor 3 in a timely manner. We monitored the development work necessary for this operation, and were satisfied that BNFL had properly reviewed the options for recovery and chosen the best practicable option to ensure safety. This required the building and commissioning or remote handling equipment to put the fuel back into the basket. We issued a licence instrument on 24 October 2001 allowing BNFL to proceed with the recovery operation. Subsequently, BNFL safely recovered the fuel which was dispatched to Sellafield for reprocessing.
Following the incident on 5 July, BNFL took the conservative decision and suspended routine refuelling operations at Calder Hall and Chapelcross. Following a number of meetings, the NII agreed a way forward with the licensee to commence routine refuelling operations. This involved satisfying the requirements set out in NII's Report leading to BNFL recommissioning the fuel route, not only to show that lessons had been learnt, but also to reveal any other safety significant issues. In January, the NII site inspector carried out an inspection to examine Chapelcross's progress in recommissioning to inform its decision on whether to allow recommissioning involving spent fuel elements. Although Chapelcross showed it was ready to begin the next stage of recommissioning, its sister station at Calder Hall had identified a technical problem which needed to be resolved. BNFL resolved this to NII's satisfaction and NII gave its agreement on 19 March 2002 allowing recommissioning of the fuel routes with spent fuel. To date, the NII has been satisfied that the recommissioning has been successful and shown that Chapelcross can discharge fuel safely.
In the longer term, the NII Report requires BNFL to carry out a detailed review of fuel route operations to identify reasonably practicable improvements. The NII will monitor progress and discuss the outcome of this review with BNFL.
12. Depleted Uranium Trioxide Leakage from Building 141
On 19 July, Chapelcross reported to the NII that a leakage of a small amount of Depleted Uranium Trioxide had occurred from Building 141. The material leaked from some corroded mild steel drums. The corrosion was due to rainwater getting into the building, and the rainwater washed a small amount of the spilled material out of the building. Depleted uranium trioxide is a dense, bright and easily seen yellow powder derived from the reprocessing of spent uranium fuel from magnox power stations. It is less radiologically toxic than naturally occurring uranium but chemically toxic in a similar manner to lead. Owing to its density and low solubility, it does not tend to spread far.
The conditions attached to the Nuclear Site Licence require licensees to so far as reasonably practicable to control and contain such material to prevent it coming into contact with either people or the environment. Consequently, a loss of control of nuclear matter is a serious issue, and the NII carried out an investigation of this incident principally to confirm that there was no harm to public or employees, and that the escape had not spread into the environment.
The NII investigation examined BNFL's monitoring to assess the possible spread of depleted uranium oxide and judged that it was sufficient to provide the NII with confidence that there had been no harm to either public or employees. As is normal for such incidents where there could be an environmental impact, there was close liaison between the NII and SEPA.
From its investigation, NII required BNFL to take steps to prevent a recurrence of this incident. In response, BNFL has provided a programme of work to prevent water getting into the building using over-cladding of the building. In the longer term, it intends to empty Building 141 and remove it. The NII will monitor BNFL's progress in achieving this programme. Currently, we are satisfied with the work underway to deliver this programme.
This event reinforced the need for BNFL to take steps to improve the area of Chapelcross known as the North Site. This has been used for many years to store amongst other things, redundant plant and equipment which is contaminated. The NII is satisfied that Chapelcross has included now the North Site in its Improvement Programme, and that it has already made some significant improvements by removing a large number of items into stores it has recently constructed.
13. Incidents: The management and records of events that happened on the Station in the period covered by this report were inspected. Except for those described above, these were relatively minor. The NII Site Inspector has discussed them with Chapelcross staff to ensure that they were being properly dealt with and lessons learnt. The Site Inspector was satisfied that for events identified, corrective actions to address the causes of the incidents had been taken or were being progressed satisfactorily.
14. Charge Pan Movement Relative to the Core: During its routine inspections of the graphite core of Reactor 1 as part of its normal statutory outage in September 2001, BNFL reported to the NII site inspector that the chargepans just above the core were not in the position expected by the safety case. The chargepans are heavy cast iron plates which sit on top of the graphite core to protect the graphite from damage during refuelling operations. BNFL's inspections had found evidence of an increased rate of chargepan movement relative to the reactor core. Graphite shrinkage due to ageing of the core was responsible. Reactor 1 at Chapelcross is more advanced in ageing terms than the other three reactors, as they have sleeved fuel channels, a design change made after Reactor 1 to reduce the rate of ageing of the graphite cores. Calder Hall reactors are of a similar design to Reactor 1, and BNFL shut down the Calder Hall reactors that were still operating to investigate whether they were affected too.
Reactor 1 at Chapelcross has remained shutdown since this finding and before it can return to service, BNFL needs to provide an adequate safety case to justify its safe operation. BNFL carried out inspections to confirm its view that the other Chapelcross reactors are still as expected by the safety case for the reactor cores. The NII was satisfied that BNFL had provided an adequate justification for continued operation of the other reactors until their next outages. However, BNFL need to provide the NII with a safety case to justify operation of these reactors beyond then recognising that ageing will continue.
14. Early Cessation of Generation: As you are aware, BNFL recently announced the early cessation of power generation at Chapelcross by March 2005 for business reasons. This has no effect on the regulation of Chapelcross by NII which regulates nuclear plant while it is licensed under the Nuclear Installations Act from construction, throughout operation and during decommissioning.
8. The Inspectorate has powers under the Licence to issue Consents, Approvals and Directions. In addition the Inspectorate uses Licence Instruments to issue Specifications and Agreements under the conditions of the Licence. The following documents were issued in the period covered by this report:
was granted on 5 February 2002 allowing Reactor 3 to start up following a statutory outage and recovery of the fuel following the dropped fuel discharge basket incident of 5 July 2001.
was issued on 24 October 2001 giving BNFL agreement to the recovery of the 12 elements remaining in discharge machine No.6 on Reactor 3 following the dropped fuel discharge basket incident of 5 July 2001.
was issued on 19 March 2002 giving BNFL agreement to begin recommissioning of the Chapelcross fuel routes.
was issued on 16 April 2002 specifying that BNFL submit Chapelcross's arrangements for complying with Licence Condition 36 for approval. Licence Condition 36 is concerned with the control of organisational change and once approved, BNFL will need to seek NII's permission to change its arrangements for managing organisational changes.
was issued on 30 May 2002 allowing Chapelcross to extend the operating period of Reactor 2 until 3 September 2002 when it will have to begin its outage.
Published on the HSE web site 12 February 2002