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 Berkeley and Oldbury Local Community Liaison Council and covers activities associated with the regulation of safety at Oldbury Nuclear Power Station. These reports are distributed quarterly. Site Inspectors of HM Nuclear Installations Inspectorate (part of the Health and Safety Executive's Nuclear Directorate) attend LCLC meetings and will be happy to respond to any questions raised there by members of the LCLC. Any other person wishing to inquire about matters covered by this report should contact the HSE, Nuclear Directorate Information Centre on 0151 - 951 - 4103. The HMNII Site Inspector for the Oldbury site and other Inspectors visited on the following dates:
The HMNII Site Inspector for the Oldbury site and other Inspectors visited on the following dates:
| 15-18 January 2002 | 22-24 January 2002 | |
| 8 February 2002 | 18-25 February 2002 | |
| 4-5 March 2002 | 11-15 March 2002 | |
| 21 March 2002 |
Throughout the period of this report the NII carried out routine inspections aimed at checking the licensee is complying with the requirements of the nuclear site licence and other statutory provisions. No significant inadequacies were identified. Where these inspections revealed scope for improvements in the site's arrangements the Site Inspector raised these issues with the appropriate Management Team member or the Station Manager, and regularly progresses the station's response.
The compliance inspection focused on a range of topics. These topics included: control and supervision of operations of the Essential Electrical Systems and Burst Can Detection systems; maintenance schedule and planning; the plant modification process; and quality assurance and records of fuel flask handling activities. One particular point of note is as follows.
As reported in the last two NII quarterly reports there continues to be a build up, from historically very low levels, of radioactive caesium in the station pond water. This has arisen from slightly contaminated irradiated fuel skips arriving from Sellafield. The safety significance is low at current levels. However, this continues to result in elevated levels of caesium in site liquid discharges. The station has chosen to mitigate this by installing a system known as IONSIV in the pond. NII, in discussion with the Environment Agency, has agreed to the installation of the IONSIV system up to, but not including, active commissioning. The station has agreed to provide further safety documentation and evidence of a NIREX "letter of comfort" on the concept of packaging the arising wastes. If satisfactory, NII intends to issue a licence instrument agreeing to the use of IONSIV
This quarter has seen three significant events, each recorded as Level 1 on the International Nuclear Event Scale (INES). (The INES scale is from 0 to 7.) Once identified, the station investigated the events thoroughly and NII judged that no formal regulatory action was required. But there are a number of lessons for the station arising from these events and NII will be monitoring closely the station's action plan and signs of any similar events in future.
A Reactor Cooling Water (RCW) system pipe sheared. This led to a loss of RCW to one of the two reactors. The reactor was manually tripped, and full RCW supplies were re-established a few hours later. The RCW does not provide direct cooling to the reactor but is used to cool gas circulator oil systems and provides secondary cooling to the Pressure Vessel Cooling Water (PVCW) system. The possible loss of the RCW system is covered in the station safety case.
The pipe shear was caused by an impact from a nearby dump-steam pipe. (The dump steam system is used to cool steam from the reactor directly in condensers rather than feeding the turbine to generate electricity.) This dump-steam pipe had shaken vigorously as a result of an infrequent operation to dump steam into this line from the other reactor through an interconnector pipe linking the two reactors.
The NII investigated the incident, and Magnox Electric set up its own Panel of Enquiry. NII is satisfied there was no threat to nuclear safety. But a number of issues were identified, including the need to improve some operating practices and the development and use of procedures for infrequent operations. The station is addressing these matters through an action plan and NII is monitoring this to ensure timely completion.
An unrevealed failure of a line of reactor protection was detected during routine maintenance. The internal failure of a reset switch on a reactor neutron flux unit had defeated the trip and control rod withdrawal interlock function of the unit.
This unit was one of three lines of flux equipment claimed as first line of protection for certain potential faults that could occur during start-up of the reactor. Only one of the three was affected. The reactor has further diverse lines of protection, based on fuel temperatures, that were fully operational. Therefore, very significant defence-in-depth remained in the reactor protection systems.
Nevertheless, this was an unrevealed fail-to-danger fault on an important protection device. NII is satisfied that, once the fault was identified, the station took prompt and effective action to investigate the problem and assure itself and NII that there were no other potential unrevealed fail-to-danger faults on the reactor protection systems. The station has put in place modified test procedures and operating instructions to prevent a recurrence and reported the event to other nuclear operators. NII Specialist Inspectors are discussing with the company the lessons learned and programmes for further work to prevent similar problems on other safety-related plant.
Two production technicians were working in the cooling pond area when one dropped his EPD in the pond. Instead of reporting the incident he attempted to remove the EPD by means of a pond debris basket. This was strictly forbidden. As a result the pond gamma alarms and his colleague's EPD alarm activated. On hearing the alarms they immediately stopped the operation. However the alarmed EPD registered a small but not insignificant dose. The station undertook an immediate post-incident investigation.
The reasons for the men's actions are not clear-cut. They have recognised that their actions was against training and instructions. The Site Inspector is satisfied that the station's investigation was thorough. It has raised issues concerning behavioural safety and culture, hazard recognition, and the ease by which the debris basket could be raised. The station is addressing these issues and the Site Inspector will monitor progress.
The Inspectorate has power under the licence to issue Consents, Approvals and Directions. In addition the Inspectorate uses Licence Instruments to issue Specifications and Agreements under the conditions attached to the licence.
The table below summarises the formal Directions, Consents, Approvals and Licence Instruments (LI) issued during the quarter:
| Date | Type | No. | Description |
| 1 February 2002 | LI | 25 | Final Report on Proposals to Modify the Feed Systems to Support the Safety Case |
| 1 February 2002 | LI | 26 | Paper of Principle for replacement of PassPort Work Management |
| 1 March 2002 | LI | 27 | Paper of Principle on Proposal to Remove Caesium from the Ponds using IONSIV units |
Published on the HSE web site 21 August 2002