Flying nuclear material from Scotland to US 'an option'
The Nuclear Decommissioning Authority (NDA) has said radioactive material could potentially be flown to and from Scotland and the US.
Last month, the UK and US governments agreed that material could be exchanged, with the UK receiving a type of uranium used to diagnose cancer.
The NDA is funding improvement work to enhance the runway at Wick John O'Groats Airport.
The airport is about 30 miles (48km) from the Dounreay nuclear site.
Under the UK-US deal, it has been proposed that highly enriched uranium (HEU) stored at Dounreay be sent to the US.
The NDA said flying the material was among options being considered, but also said no decisions have been taken.
A spokeswoman for the NDA said: "The protection of the public and personnel is of paramount importance at all times. For those reason we are unable to disclose information about the transport arrangement that's could jeopardise the security of this material.
"It has been proposed that a quantity of HEU may be exchanged with the US in return for material to be used in the production of medical isotopes for Europe.
"The upgrades to the airport in Wick will be done to ensure that this is one possible option to allow the transport to take place."
A spokesman for Wick John O'Groats Airport, which is operated by Highlands and Islands Airport Limited, said: "Work will get under way later this month on a project to refurbish the runway at Wick John O'Groats Airport in order to enhance its operational capability and, in particular, its ability to accommodate larger aircraft.
"This work will be carried out on behalf of the Nuclear Decommissioning Authority. The majority of work will be carried out overnight and the project is expected to be completed in August."
Radioactive material from the civil nuclear industry has been transported by plane in the past, the NDA said.
A spokesman for the authority added that funding improvements to the airport near Wick secured "the option of moving material by air on a range of aircraft".
The Dounreay nuclear power complex is being decommissioned and the site cleaned up.
Most of the radioactive materials, such as fuel, held there is being moved to other locations, including Sellafield in Cumbria where it will be reprocessed or stored.
These shipments are being made by rail.
Over a period of four years, 150 tonnes of waste held at Dounreay were transported in 21 shipments to Belgium by sea.
In October 2014, a fire broke out on a ship involved in this work and it began drifting in the Outer Moray Firth.
The MV Parida was transporting a cargo of cemented radioactive waste when a fire broke out in a funnel.
The blaze was extinguished, but 52 workers were taken from the nearby Beatrice oil platform by helicopter as a precaution.
The cargo ship was towed to Invergordon for repairs before completing its journey to Antwerp.
The NDA said at the time that the ship and its cargo had been categorised at the lowest level of safety concern.