It has been like the old days recently.

Campaigners accusing the authorities charged with overseeing the nuclear industry of covert plans and official duplicity over Dounreay's nuclear material. We could be back in the 1990s.

But this week Cumbrians Opposed to a Radioactive Environment (Core )  had uncovered covert plans to ship Dounreay nuclear fuel to the US, contrary to the Nuclear Decommissioning Authority's (NDA) publicly stated decision to send it to Sellafield.

Core found that in November 2011 there was an application by NAC International, a leading nuclear fuel cycle consulting and technology company acting on behalf of the US Department of Energy, to America's Nuclear Regulatory Commission (NRC) for authorisation "to package and ship from Dounreay to the Savannah River site in Aiken, South Carolina, five special fuel assemblies in a one-time shipment."

Core understandably thought the NDA was trying to cover up this US connection, as it could find no trace whatsoever of it in anything published by them.

The NDA is the quango created by the Energy Act 2004 to take control of 19 sites and the associated civil nuclear liabilities and assets of the public sector, which were previously under the control of UK Atomic Energy Authority (UKAEA) and  British Nuclear Fuels Ltd (BNFL).

It is responsible for decommissioning and cleaning up the sites and ensuring that all the waste products, both radioactive and non-radioactive, are safely managed.

The NDA responded to Core's allegation by saying: "Paperwork is currently being processed to enable the future return of a quantity of overseas-owned material that is scheduled for treatment in the US. Some material has already been removed from the site and transported to the US."

It stressed that the nuclear fuels and material that had been earmarked for Sellafield were  different to those going to the US, and added: "Following a period of engagement with stakeholders to identify the preferred option, all this material is currently in the process of being transferred to Sellafield."

Although apparently a little coy about the US connection itself, the  NDA provided a link to the  website Dounreay News to show it hadn't been a secret at all. The site has a whole sereies of FAQs, including this one: Does the inventory include the fuel airlifted by the American government from Georgia (1998) for safekeeping at Dounreay?

This was the answer given: "Yes. Some of this material has been removed from the site and transported to the US. Discussions are continuing between the UK and USA about the removal of the remainder."

That was it in the public domain - so no covert plan then, no Dounreay duplicity. Complete transparency in a couple of paragraphs.

Core's spokesman Martin Forwood was understandably frustrated. He said: "The NDA's transparency on the issue leaves a lot to be desired and I question NDA's  motives in not giving the briefest of mention to foreign fuels in its own documents - an upcoming shipment of Highly Enriched Uranium to the US, along the lines of our press release, is certainly contentious and will ruffle more than a few international feathers. Perhaps NDA would hope that no-one had noticed."

It is not the first time there has been confusion about the stewardship of Dounreay's nuclear material; who knew what, when, and whether it was ever true in the first place.

Indeed the Government and Dounreay's operators UKAEA changed their minds three times as to whether 170kg, 86kg, or any Highly Enriched Uranium (HEU) at all was lost in the Caithness plant between 1965 and 1968.

The last twist in the long-running saga emerged in a report on the "material unaccounted for", or MUF, published by the Department of Trade and Industry (DTI) safeguards office in 1999.

But the MUF controversy began on June 2 the previous year, when a report into the contents of the controversial Dounreay waste shaft was published by the UKAEA's  own waste management group. It concluded that 170kg of HEU had been unaccounted for and estimated that at least 22kg would have been put in the shaft.

It predicted: "Unaccountable losses are likely to be spread over various facilities, and are likely to be recovered during their decommissioning." There were also suggestions it had gone to the military nuclear programme.

However, just 24 hours later on June 3, Dr John McKeown, UKAEA's chief executive, insisted it was an accountancy error. He was adamant: "It is not a case of the material having been hidden, it is not a case of the material having been lost, quite simply it is a case of the material never having existed."

It was a line embraced by Tony Blair in an answer to Alex Salmond on the same day which resulted in the then Prime Minister apparently misleading Parliament.

Mr Blair said "The allegations about the supposedly missing highly enriched uranium were based on a misrepresentation of 30-year- old records which are far from complete by any modern standards."

But on July 27, the then President of the Board of Trade Margaret Beckett said the missing material had indeed existed but some had been burnt in the fast reactor and some had been discharged.

And in January 1999  the DTI said the original report had been a worst case scenario and "...the material unaccounted for would have been significantly less than 86 kg of U 235." But it had existed.

There were also several hymn sheets to sing from over whether Dounreay's relationship with UK military programmes - Government ministers and directors of Dounreay, for 40 years, had insisted there had been no connection at all.

It was the position Tony Blair adopted in a withering putdown of Alex Salmond in Parliament. Mr Blair had said at Prime Minister's Questions: "I can confirm that no such material has ever been sent from Dounreay for use for United Kingdom weapons purposes, and I suggest that the Honourable Gentleman reads carefully what has already been said by the chief executive (of UKAEA) and others on the issue. For the Honourable Gentleman to alarm the public in this way is irresponsible in the extreme, but entirely typical of him."

However, it was a cabinet minister who confirmed the established line on Dounreay had been deceitful. And again it was Margaret Beckett. She had been asked about the Dounreay MUF, and in a written answer insisted that material had not gone into weapons programmes, but continued: "As a result of an audit of the records requested by this Government, however, it is clear that there were in the past documented transfers from Dounreay which related to UK military programmes.

"Prior to 1973 when AWRE (the Atomic Weapons Research Establishment) at Aldermaston and Dounreay were both part of the UKAEA, it is probable that some of the material transferred from Dounreay to Aldermaston will have been used in the UK weapons programme."

So it is not just Dounreay's nuclear material that should be handled with the greatest of care and vigilance. Information has radicactive hazard warnings as well.