HC Deb 09 January 1990 vol 164 cc567-8W
Mr. Dobson

To ask the Secretary of State for Energy if he will list the nuclear reactors in Britain(a) with and (b) without secondary containment.

Mr. Wakeham

All nuclear reactors in the United Kingdom are provided with defence in depth against the release of radioactivity by means of a series of barriers which differ according to the design characteristics of the particular reactor type. The term "secondary containment" usually refers to an outer, sealed, low-leakage building which houses the reactor core and primary coolant circuits. The need for such containment depends on the operating characteristics of the reactor and the coolant activity levels. The steam-generating heavy water reactor at Winfrith, and the prototype fast reactor at Dounreay have "secondary containment" buildings, and these will also be provided for the pressurised water reactor under construction at Sizewell. The operational characteristics of Magnox, advanced gas-cooled reactors, and small research reactors are such that "secondary containment" buildings are not needed to ensure their safety.