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 Heysham Local Community Liaison Council and covers activities associated with the regulation of safety at Heysham Power Stations. These reports are distributed quarterly. Site Inspectors of HM Nuclear Installations Inspectorate, which is part of the HSE Nuclear Directorate, attend LCLC meetings and will respond to any questions raised there by members of the LCLC. Any other person wishing to enquire about matters covered by this report should contact the HSE Nuclear Directorate on: 0151-951-3484/3290
This report will be put onto the HSE website at http://www.hse.gov.uk/nuclear/index.htmThe Nuclear Installations Inspectorate (NII) Site Inspectors and other inspectors made inspections at Heysham on the following dates during the quarter:
| Heysham 1 | Heysham 2 | |
|---|---|---|
| 10, 11,12, 24 & 25 | Jan 2007 | 9,10, 11, 23, 24 & 25 |
| 13,14,15, 21 & 22 | Feb 2007 | 7, 8, 20, 21, & 22 |
| 2, 6, 13 & 22 | Mar 2007 | 2, 27, 28 & 29 |
Inspections are undertaken at site as part of the process for monitoring compliance with:
This entails monitoring licensee’s actions on the site in relation to incidents, operations, maintenance, projects, modifications, safety case changes and any other matters which may affect safety. The licensee is required to make and implement adequate arrangements under the conditions attached to the licence in order to ensure legal compliance. Inspections seek to judge both the adequacy of these arrangements and their implementation. In this period routine inspections of site covered:
In general the arrangements made and implemented by the stations in response to safety requirements were deemed to be adequate in the areas inspected. However, where improvements were considered necessary, satisfactory commitments to address the issues were made by or are being sought from the licensee, and the site inspectors will monitor progress during future visits. Where necessary, formal regulatory intervention action may be taken to ensure that appropriate remedial measures are implemented to reasonably practicable timescales.
The NII site inspectors attended the 39th Emergency Planning Consultative Committee on 2 March 2007.
The recent routine refuel outage of reactor 2 provided the opportunity to progress the programme of inspections aimed at establishing and monitoring the condition of BCU components. Previous radiographic examinations had revealed a number of additional wire tails adjacent to tendon wire anchorages. During the outage the station exposed tails at two locations and a visual examination confirmed that they are artifacts of construction. This examination has provided important validation of the capability of the radiographic technique used to establish the condition of key BCU components. The recent radiographic examinations did not reveal any new abnormalities.
Nothing of particular note during this reporting period.
Licensees are required to have arrangements to respond to non-routine matters and events. NII inspectors judge the adequacy of the licensee’s reponse including actions taken to implement any necessary improvements. Matters of particular note considered during the period include the following :-
In preparation for a routine electrical isolation of PVCWS pumps, operatives inadvertently defeated the segregation of electrical supplies required to protect PVCWS function in the event of a cable fire. The error was revealed during restoration of normal supplies later the same day. The station immediately reported the incident to NII in accordance with its arrangements for complying with the conditions of the Site Licence and commissioned a Significant Abnormal Condition Investigation (SACI). The investigation concluded that the incident was caused by human error and proposed several corrective actions which aim to avoid the repetition of this or similar errors. The site inspector met with the Human Performance Leads for both Heysham 1 and Heysham 2 to discuss the incident and is satisfied with the station’s response.
Reactor 2 continues to operate at reduced load due to the higher than expected temperatures indicated by one of several instruments monitoring underdome hot box surface metal temperatures. British Energy has developed a procedure for video examination of the dome surface, which was successfully deployed during the recent routine refuel outage. The station is currently evaluating the video evidence but it shows no significant abnormalities. The station has completed an analysis which justifies a small increase in reactor load while preserving an acceptable margin on dome temperature. The Site Inspector continues to monitor the station’s response to the temperature indications but is satisfied that it is keeping NII informed of any changes in operating conditions.
Following the leak detected on an underground section of pipework which forms part of an auxilliary cooling system during the previous reporting period further inspections have been undertaken on the system pipework. The results of the inspections have revealed some degradation in sections of the pipework. Station has begun a pipe replacement programme using high-density polyethelene (HDPE), which should last the remaining life of the station and be more resistant to seawater and organisms entrained in the seawater. In addition, the installation method means that sections of the pipework will be more readily accessible for inspection in the future. Some of the pipework runs deep underground and the Station is investigating the possibility of lining this pipework should its inspection reveal this to be necessary. NII will continue to monitor progress with this work.
During the stormy weather in January some main electrical grid disturbances led to problems being encountered with the main electrical generator serving reactor 8. This led to the operators taking a prudent decision to manually shutdown the reactor. The safety relief valves on the boilers lifted to relieve stored pressure and some local cabling was damaged in the area of the hot vented steam. During the shutdown no plant operating limits or conditions were exceeded. An investigation into the cause of the event led Station to identify a number of corrective actions, which will be put in place in order to reduce the likelihood of a recurrence. NII is satisfied that station has thoroughly investigated the circumstances surrounding this event and learned the necessary lessons.
During routine maintenance Station detected a small carbon dioxide leak escaping from one of the fuelling machine body bolted joints. Station staff checked the tightness of the bolts and found several at a lower than expected level. A number of bolts were examined by company specialists and these examinations revealed no defects. The procedure for tightening was reviewed and revised and several new bolts were fitted. This overcame the immediate problem of leaktightness. Each of the machine joints has a primary and secondary seal of different design and the secondary seal in one joint has degraded sufficiently that a safety case has been provided by the Station to justify this position. NII has requested the Station to consider a repair methodology for this seal. NII will continue to monitor the progress in respect of the integrity of the fuelling machine joints.
Under Health and Safety legislation NII Site Inspectors, and other HSE Inspectors, may issue formal documents to ensure compliance with regulatory requirements. Under nuclear site licence conditions HSE/NII issues regulatory documents, which either permission an activity or requires some form of action to be taken; these are collectively termed Licence Instruments (LI). In addition inspectors may issue enforcement notices to secure improvements to safety.
One LI was issued to Heysham during the quarter: -
Nuclear Directorate
Health and Safety Executive
Redgrave Court
Merton Road
Bootle
Merseyside
L20 7HS