Something inexplicable has been going on at the Grand Canyon museum, and the truth is stranger than fiction.

It all started in March of 2018, when the teenage son of a park employee was testing out their Geiger counter in the museum collection room. As the young radiation enthusiast was wandering around the space, they noticed the instrument suddenly spike.

It was here, right next to the taxidermy exhibit, that officials found three buckets filled to the brim with highly radioactive uranium ore. One of the 19-litre (5 gallon) containers was so overloaded, it couldn't even close properly.

Only then was the truth fully realised: for nearly two decades, ever since the buckets were inexplicably brought to the museum, tourists, employees, and children had passed unnervingly close to a dangerous source of radiation.

After eight months of silence from the US National Park Service (NPS), the story is finally reaching the public.

On February 4th, AZ Central reports, a rogue email was set out to all NPS employees detailing the entire debacle and blaming "top management failure".

It was written by none other than the park's own safety, health and wellness manager, Elston "Swede" Stephenson, who found out about the uranium and reported it to park service officials in June 2018, a few months after it was discovered and moved to a different building.

Stephenson, who was concerned primarily by the health consequences, says that he repeatedly emailed officials at the NPS, urging them to inform the public. But after months of fruitless waiting, he took matters into his own hands.

"If you were in the museum collections building between the year 2000 and June 18, 2018, you were 'exposed' to uranium by the [Occupational Safety and Health Administration's] definition," Stephenson wrote in the email, according to AZ Central.

While this exposure will not necessarily cause dangerous health consequences, he urged worried employees to consider receiving a medical screening.

"Of particular concern are 1,000s of children attending 'shows' in very close proximity to the uranium," he reportedly pointed out.

Right next to the three buckets, he explained, children would often stop and listen to museum demonstrations, which means they were sometimes sitting next to a radioactive substance for 30 minutes or more.

Based on radiation readings and standards from the US Nuclear Regulatory Commission, Stephenson figured that within three seconds, these kids could have been exposed to radiation levels well beyond federal safety standards. For adults, it would have taken less than 30 seconds.

In fact, he calculated potential exposures over 1,400 times the NRC's safe level for children, and over 140 times the safe level for adults.

(Elston Stephenson/AZ Central)

But when Stephenson called expert technicians to come get rid of the uranium for good in June 2018, he said they kept the radiation readings from his view.

Allegedly, once the technicians had dumped the ore in a nearby mine, they returned the radioactive buckets back to the museum. In November 2018 they were found and removed by OSHA officials who were following up on Stephenson's report.

Since the email was sent, Stephenson has not heard from the NPS, and he told AZ Central that he thinks officials are "in cover up mode."

Nevertheless, the Park Service has assured the public that the uranium has officially been removed and that background radiation levels at the museum are safely under control. A joint investigation involving OSHA and Arizona's health department is currently underway.