§ Mr. Simon HughesTo ask the Secretary of State for Energy (1) what trials, experiments or other modes of operation which would deviate from normal operational96W practice are included in the proposal by Nuclear Electric to restart one of the reactors at Trawsfynydd power station for a period of six months; and what revision to the temperature of operation of each of the reactor core, fuel, coolant gas and reactor presure vessel shell is included in the proposed operations;
(2) if he will make a statement about his current assessment of the frequency probability of failure incidents in the reactor pressure vessels deployed at each of the Magnox nuclear power stations;
(3) what effect delays in the reactor pressure vessel surveying programme at Trawsfynydd and other Magnox nuclear power stations have had on the timing of Nuclear Electric's preparation and submission of a revised safety case to the nuclear installations inspectorate;
(4) on what date Nuclear Electric submitted a revised nuclear safety case for the continued operation of each of the Magnox power stations to the nuclear installations inspectorate; and what materials data, determined from the recent inspections of the reactor pressure vessel at Trawsfynydd and other Magnox nuclear power stations, are included in the revised safety case;
(5) if he will make a statement on the progress of the reactor pressure vessel inspection and surveying programmes currently under way at Trawsfynydd nuclear power station; and if physical obstacles encountered during these inspections have now been overcome.
§ Mr. Heathcoat-AmoryThe details of any operational changes proposed in the revised safety case for a return to power at Trawsfynydd are a matter for Nuclear Electric plc. The assessment of the safety case is a matter for the Health and Safety Executive's nuclear installations inspectorate. The NII will not consent to the restart of the station until it is convinced that it is safe to do so.
In the light of developments at Trawsfynydd, NE has reviewed the position at its four other Magnox stations with steel pressure vessels, and following certain operational changes the NII has agreed to their continued operation up to the end of 1991. Full safety cases to enable the stations to operate beyond the end of the year were submitted to the NII on II September and are currently under consideration. I understand that the NII propose's to make an announcement by the end of this month.
§ Mr. Simon HughesTo ask the Secretary of State for Energy (1) if he will make a statement on details of the temperature excursion that occurred in reactor I at Bradwell nuclear power station on 17 June 1991; what caused the increase in temperature; and whether he has been informed of any disciplinary action by Nuclear Electric as a result of this incident;
(2) if he will place in the Library a copy of the full report of the Nuclear Electric board of inquiry into the temperature excursion incident at Bradwell nuclear power station on 17 June 1991, and the report of the nuclear installations inspectorate; and if he will also place in the Library details of any equipment modifications and revisions to management procedures that have been implemented as a result of the incident.
§ Mr. Heathcoat-AmoryI understand from the Health and Safety Executive's nuclear installations inspectorate that, during the return to service of Bradwell's reactor 1 on 17 June 1991, it was observed that the gas temperature limit in a small area of the reactor core was exceeded by 30 deg C. The temperature deviation was readily brought 97W back within limits by control rod insertion. This incident has been classified at level 2 on the international nuclear event scale—that is, a technical incident or anomaly not directly affecting plant safety.
I am advised by Nuclear Electric plc that incident inquiries are undertaken on a confidential basis in order to encourage the maximum disclosure of information. The details of such investigations are not, therefore, published. The conclusions and actions arising are, however, provided to the regulatory authorities.