It has featured on stamps, even in a world welly boot throwing record and is one of the most defining sights on Scotland’s north coast.

But it is soon to be going, going, gone for the iconic golf ball dome at Dounreay in Caithness will soon be consigned to history.

Its reactor will be dismantled in 2025, according to the Nuclear Decommissioning Authority’s (NDA) latest business plan, with the distinctive dome expected to disappear the following year.

The business plan includes a 20-year overview, as well as key planned activities for the next three years.

The Herald: Under construction in 1956Under construction in 1956

Dounreay, near Thurso, was the UK site for the development of fast reactor research from 1955 to 1994.

The facility on the north coast is in the process of being closed down, demolished and cleaned up at a cost of £3.2 billion.

The NDA had previously said it wouldn’t be until the year 2333 before the 148-acre site was safe for reuse.

Buildings to be demolished include the dome-shaped Dounreay Fast Reactor (DFR). All reactor breeder and other fuels from the DFR would be taken to Sellafield in Cumbria over the next two years.

The DFR once led the world in fast breeder technology.

The reactor was built in the 1950s at a time when there was a worldwide shortage of uranium for electricity generation. Its core was surrounded by a blanket of natural uranium elements that, when exposed to the effects of the radiation, would “breed” to create a new fuel, plutonium.

After the reactor closed in 1977 most of the core fuel was removed. But work to remove elements from the breeder zone came to a halt when some were found to be swollen and jammed. Almost 1,000 – around two-thirds of the total – were left 
in place.

However, in March last year it was announced that more than half of the last remaining radioactive fuel elements jammed for decades inside the DFR have been removed. 

Decommissioning the 60 plus-year-old reactor is one of the most technically challenging projects in the NDA estate and removing the breeder elements has been a top priority. The sphere itself is expected to be ultimately removed by around 2026.

There were previous plans to retain the dome - including even as a hotel and a nightclub.

Historic Scotland had even considered listing the building so that it would be conserved.

DFR went critical in November 1959 and operated until its shutdown in March 1977. During much of its time it led British research and development of nuclear energy.

Built between 1955 and 1958 to test nuclear energy, it became the first fast reactor in the world to provide electricity to a national grid in 1962.

At the time a sphere was considered to be the best shape of structure to contain gases from the reactor, if there was a breach.

In the 1960s, it featured in a series of special edition stamps promoting Britain’s “white heat of technology”.

Meanwhile, the world record for welly boot throwing was once set during the construction of the dome.

In 2007, site operators DSRL released the results of public consultation on future uses for the dome.

There were previous plans to retain it, including even as a hotel and a nightclub.

Historic Scotland had even considered listing the building so that it would be conserved.

However, because the structure is contaminated with low levels of radioactivity and due to high maintenance costs, it was decided to demolish it.

Two years after the DFR is dismantled it will be the turn of the Prototype Fast Reactor to reach the same stage.

A target date has also been set for the clean-up of a highly contaminated area called the Shaft.

Built in the 1950s, it plunges 65.4 metres (214.5ft) below ground.

Radioactive waste was disposed there from 1959 to 1977, when an explosion ended the practice.

The silo and Shaft should be encapsulated by 2028, according to the NDA report.

The document also sets out that £200 million will be spent on Dounreay in the next financial year.

David Peattie, NDA chief executive, said in the report: “At Dounreay, the fast reactor is scheduled to be defueled by 2022. Completing this work will mark another significant reduction of radiological hazard and is an important step closer to decommissioning the site.

“Our mission to leave the environment a better place for future generations includes the impact we leave as a result of our operations. 

“We will be placing significant emphasis on our roadmap to becoming net carbon zero, having this year established a dedicated programme team to take this work forward. 
“The next few years are critical in the world’s fight against climate change and we must play our part to the fullest.”