LONDON’S proposed Olympic Park in 2012 had been the site of an experimental nuclear reactor, it was revealed yesterday. London 2012 officials insisted, though, that the area was free from nuclear contamination and senior bid figures told The Times that it came as a surprise to learn that Queen Mary College’s department of nuclear engineering built a reactor at the Lower Lea Valley in 1980.

The college issued a statement declaring that the reactor was closed down in 1982, under supervision by the Nuclear Installations Inspectorate, and that there were “absolutely no ongoing health implications of the decommissioned reactor”.

London 2012 said that it had not disclosed the existence of the reactor to the International Olympic Committee (IOC) because it had not known about it until yesterday and its own environmental advisers had not raised “any nuclear contamination issues”. But the Conservative member of the London Assembly who made details of the reactor public called for a fresh survey of the site. Bob Blackman, the Tory economic development spokesman, said: “If there was an experimental nuclear reactor there . . . they may well have closed it down properly and removed the contamination. But have they surveyed it recently?”

Mike Lee, the bid spokesman, said that environmental advisers had assured the London Development Agency that there was “no nuclear contamination issue”. Lee flatly denied Blackman’s claims that he had confirmed there was a nuclear contamination issue with the site. “We were not aware of this issue when we submitted the candidate file to the IOC,” Lee said. “The only time that the bid became aware was when the matter was raised in the London Assembly today.”

The candidate file, which was submitted to the IOC on November 15, 2004, was examined by the IOC’s evaluation commission, which visited London in February. No mention of the fact that there had been a nuclear reactor on the site of the Olympic Park appears in its official report, which was published on June 6 and read by IOC members before they voted in Singapore on July 6.

London 2012 insiders were furious at the way Blackman raised the issue, dismissing the disclosure as “a storm in a teacup”. Lee has accused Blackman of “scaremongering”.

During the meeting, Blackman asked: “This site was also the site of a nuclear reactor at one stage. Can you assure us that all of that contamination has been removed?” Lee responded: “My understanding is that all the remediation work that is needed, the decontamination that is needed, is being planned and is under way. Everybody who has been engaged in this — and there has been a lot of assessment of the area and the land — knows that it will be fully decontaminated and safe before the building work starts.”

Asked last night to explain why he had apparently known about the issue, despite having said that the bid team became aware of it only yesterday, Lee said: “My comments were of a very general nature, dealing with contamination. They were not to do with any issue about a nuclear reactor.”

In its statement, Queen Mary College said that the now-defunct Department of Nuclear Engineering used to house a small nuclear reactor at Marshgate Lane. It added: “It was used for undergraduate experiments and postgraduate projects, and for training people to work in or on nuclear power stations.

“It was decommissioned in 1982 under supervision by the Nuclear Installations Inspectorate. The reactor was exceptionally small; the core was the size of a bucket and produced virtually no energy. Decommissioning staff were able to stand inside the reactor void with no protective clothing.”

Later, a spokesman for the college said that the core was dismantled and removed but that the concrete shield was found to have some minor contamination. Those radioactive parts were chipped away and sent to a nuclear processing plant. “As far as the college is aware, none of the material from the reactor is buried on the site,” the spokesman added.

Professor Ian Fells, of the University of Newcastle-upon-Tyne, agreed that there was no risk. “I should be very surprised if there is any substantial contamination from the reactor at all,” he said. “Those reactors were feeble in power — that was the reason they were allowed to have one on a university campus in the first place.”

A spokesman for the London Development Agency said: “This seems to be completely spurious. There is no issue here because it was fully decontaminated 23 years ago. It is not relevant what was there years ago if there are no health implications now. There was a full process of checking everything in the area.” No one from the IOC was available to comment.