§ Mr. Benn
Oxidation of certain minor steel components at a greater rate than anticipated has occurred at six of the Central Electricity Generating Board's seven operational Magnox type nuclear stations; Bradwell, Hinckley "A", Trawsfynydd, Dungeness "A", Sizewell and Oldbury. The rate of oxidation is influenced by the temperature of the coolant gas inside the reactor which has therefore been reduced slightly to slow down the rate of oxidation.
Production from these stations will be reduced by about 400 MW, approximately 1 per cent. of the C.E.G.B.'s maximum output capacity. With present plant margins the C.E.G.B. foresee no threat to supplies this winter. All the stations affected remain in continuous operation and are, I understand, still exceeding their design load factors of 75 per cent. I am satisfied that they can continue to operate safely at the reduced temperatures.
I have satisfied myself that with help from the U.K.A.E.A. and the nuclear consortia the Generating Board are investigating the full consequences of the problem and ways in which to restore the lost output. I have the Board's assurance that A.G.R. stations will not be affected as they operate in a much higher temperature range for which special steel components are being provided.