Emergency cordon at Folkestone Museum during the removal of a radioactive object

A museum that housed a mysterious radioactive stone was forced to close an entire floor after radiation levels became too high.

The unidentified stone, believed to contain uranium, has been kept away from the public at Folkestone Museum since its opening in 2017.

But radiation protection consultants are now helping Folkestone Town Council (FTC) owners dispose of the potentially hazardous site after it emitted radiation “above permitted levels”.

A council spokesman said staff and the public were not at risk and the item was stored in a secure location at all times and has now been safely removed off site.

The events unfolded when authorities tested radon levels at the town hall where the museum is located over the summer, following health and safety guidelines, as low levels are quite common in the area.

But when radioactive gas readings were found to be “higher than they should be”, the ground floor of the Guildhall Street building was cordoned off to the public and staff from 25 June to 6 August.

A council spokesman told KentOnline: “After monitoring, radon levels were considered higher than they should be on the lower level of the museum.

“There is no information about how the object ended up in the museum’s collection.”

“While further investigations were carried out, as a precautionary measure, the lower level of the museum was closed to the public and staff space was limited.”

When government-vetted radiation protection advisers were brought in to help solve the problem, they were asked to scan the museum’s collection.

“One item was found to be above the permitted level in a mineral collection and not in a public area,” the spokesman said.

“Although it is already safe, this issue has been resolved by moving it to a secure location until appropriate arrangements can be made for safe disposal as recommended by the Radiation Protection Officer.

“There is no record of how the object came to be in the museum’s collection.”

The council has now awarded a three-year contract to a radiation protection firm to provide guidance on the storage and disposal of the site.

Meanwhile, according to official documents, the company plans to train a radiologist to join its ranks.

Always known to be radioactive, the rock is believed to have joined the mineral collection between the 1970s and 1980s to help complete the geological assemblage exclusive to the area.

For decades, Kent County Council has been responsible for these items, including a radioactive rock that was decanted from the old Tontine Street museum in 2016.

“It was immediately isolated in a toxic materials cabinet in a suitable container and entered into the appropriate toxic/radioactive substances register by the previous employee, a university-trained geologist,” the spokesperson explained.

“At that time, appropriate precautions were taken and the risks were known. However, we did not have an accurate reading because the 2017 test was a Geiger method.”

But a later, more accurate scan gave a gamma dose rate of 50 μSv/h, meaning it was most likely a piece of natural uranium, they added.

Radon gas is present throughout the UK.

Levels in the air we breathe outside are very low, but inside buildings they can be higher.

It creates a cloud of invisible radioactive dust that, if inhaled, can cause serious lung damage.

“People cannot see, taste or smell ionizing radiation—most of its effects cannot be observed with the eye,” says the Museum of London.

“Radiation can only be detected using special monitoring equipment.

“With the right equipment, it is usually easy for a trained person to identify radioactive objects.”

The law requires museums to seek advice from radiation protection experts if radioactive material is discovered.