§ Earl Attleeasked Her Majesty's Government:
Further to the Written Answer by the Lord Bach on 24 May (WA 110) on nuclear submarines, whether the radioactivity in the reactor compartment and the reactor itself is located in the surface of the steel; and, if so, whether it could be removed by heavy shot blasting. [HL3055]
§ Lord BachMost of the radioactivity is contained within the reactor pressure vessel, which is in the submarine's reactor compartment, and consists of irradiated steel as a result of exposure to neutrons during reactor power operations. As this activity occurs throughout the body of the steel it could not be removed by heavy shot blasting. Outside the reactor pressure vessel, but within the reactor compartment, is the primary circuit, which circulates hot water from the reactor pressure vessel to heat exchangers. While this circuit has not been significantly exposed to neutron activity, its internal surface is contaminated with radioactive corrosion products that are deposited in the cooler pipework outside the reactor pressure vessel. As the contamination is internal to the sealed primary circuit, the heavy shot blasting technique could not be used.