§ Mr. Hooleyasked the Secretary of State for Scotland what were the reasons for the recent malfunction of the Hunterston AGR, including design fault or operational inefficiency; what will be the approximate cost of restoring the reactor to normal working and the time scale involved; and if any radiological hazard to either the work force or the general public arose.
§ Mr. MillanOn 13th October 1977 it was found that a quantity of sea water had entered one of the two reactor pressure vessels at Hunterston B through a gas circulator cooling system following the shut down of that reactor for planned routine maintenance. Subsequent inspection showed heavy deposits of salt on the periphery of the floor of the pressure vessel underneath the boilers. The salt water had been prevented by a baffle from passing under the reactor core, and samples taken from other parts of the gas path have not indicated significant salt pollution elsewhere.
The South of Scotland Electricity Board has instituted a board of inquiry into the cause of the incident which has not yet completed its report, but I am advised by SSEB that the indications are that, once the salt has been removed, the reactor can be returned to full load operation. It is not yet clear, however, whether the salt can be removed by water washing or whether it will be necessary to replace part of the insulation, in which case remedial work could take up to 12 months and cost £3 million. The Board is also incurring additional costs while the reactor is out of service in supplying electricity generated more expensively by other stations.
SSEB has assured me that the incident does not reflect on the design, safety or operational characteristics of the AGR 329W system, and that there was no radiological hazard either at the time of the incident or subsequently. The second reactor at Hunterston B continues to operate normally.