§ Lord Astor of Heverasked Her Majesty's Government:
In the light of the recent Lancaster University report, how long reactor compartments from Royal Navy nuclear submarines must be stored before the core reaches a safe level of radioactivity. [HL2848]
110WA
§ The Parliamentary Under-Secretary of State, Ministry of Defence (Lord Bach); When a nuclear submarine leaves operational service, its reactor is defuelled at the earliest practicable opportunity and the highly radioactive used fuel in the core is removed for long-term storage at BNFL Sellafield. Certain reusable equipment is also removed and the submarine is stored safely afloat. Within a year of shutdown of the reactor, the majority or the submarine's radioactive fittings either can be classified as low-level waste, or will meet free release standards. The remaining radioactive material, which is mainly irradiated steel in the reactor pressure vessel, and which would be classified as intermediate level waste, is retained in the reactor compartment. The level of radioactivity in the reactor pressure vessel reduces by about a third of its original value over the subsequent 30 years. However, even at the start of the storage period the robust shielding of the submarine's hull ensures that radiation levels on the outside of the submarine are so low that it is barely measurable against normal background radiation: standing beside the hull of one of these defuelled submarines continuously for 20 days results in a similar dose to flying to California once. Moreover, the radiation level inside the reactor compartment is low enough to allow radiation workers entry, under standard control procedures, at any time. Leaving the irradiated steel within submarines is therefore very safe and presents no direct hazard to the workforce, general public or surrounding environment.