The Ministry of Defence says it intends to remove the reactor, which is known as Jason and sits in a building next to the busy main road through the town used by thousands of vehicles every day, and a few yards from people's homes.
But John Large, Britain's leading independent nuclear expert, says that dismantling it will take at least two years' work by highly trained staff, who will need special protection from residual radioactivity caused by its highly enriched uranium fuel.
The reactor, which has been used to train engineer officers from nuclear submarines, has been operational in Greenwich - which proclaims itself a nuclear-free zone - since 1963. Its weapons-grade uranium is 90 per cent enriched - 30 times more radioactive than that used in commercial reactors. "It's incredibly radioactive fuel," says Mr Large, an expert in nuclear systems. "It's not a power reactor, it's more like a neutron radiation facility. It's a very potent piece of radioactivity in the middle of a civilian area. To move it would be quite an undertaking."
No reactor has ever been dismantled and relocated under the present rules governing radiation release in Britain. Mr Large estimates it will take around two years and pounds 2m to dismantle Jason.
Although the reactor is small in comparison with those in atomic power stations, measuring 12 ft high and 300 sq ft in total, it is surrounded by up to 300 tons of steel and concrete cladding, which will have been irradiated by neutrons from the fuel over the years. Moving the reactor will also involve moving this structure, which carries the risk of releasing radioactivity into the environment.
Walter Patterson, another leading nuclear expert, comments: "It may be a small reactor, but they weren't built to be moved around."
Perhaps unsurprisingly, the reactor does not get much mention in the glossy brochure put out by estate agents Knight, Frank & Rutley to promote the sale, the announcement of which last month by Michael Portillo, Secretary of State for Defence, and the Secretary of State for Heritage, Virginia Bottomley, caused outrage.
Jason is housed in the historic King William's Quarter, described in the brochure simply as having "26 training rooms, 42 training-related offices, 25 cabins and extensive kitchens and stores". The only reference in the 18-page brochure is a single sentence saying the MoD will "address the removal" of all specialist plant and equipment, "including a small research and training nuclear reactor".
Knight, Frank & Rutley says it has been conducting two tours a day of the site for interested parties since the announcement in September, but any client's questions about the reactor are referred to the MoD.
Richard Haynes, a partner in the firm, said: "There's no doubt that its removal will be a substantial exercise. Nobody is going to commit themselves to doing anything in a hurry."
Jason's future is uncertain. The MoD says it is conducting a feasibility study into relocating it. A spokesman said: "I cannot imagine a scenario in which it would stay." However, Greenwich Borough Council's environmental health department is under the impression that the reactor is staying put.
Under the plans to lease the 300-year-old Baroque buildings to the private sector, the Government wants to raise at least pounds 400,000 per year from new tenants when the staff colleges occupying the buildings move to the new joint services college in Camberley, Surrey, in 1997.Reuse content