spaceSpace and Physics

An Idaho University Lost Track Of A Piece Of Weapons-Grade Plutonium

ISU employees searched numerous waste disposal barrels but have still not determined the location of a 1-gram plutonium-239 sample.

Even elite scientists can fall prey to absentmindedness. Case in point: Idaho State University had a major whoopsie moment late last year when they realized they had misplaced a small amount of weapons-grade plutonium.

Making matters even worse, it appears that no one has actually seen it since 2003.


Weighing about 1 gram, or one-thirtieth of an ounce, the sample of plutonium-239 is far too small to make a bomb but still has the potential to wreak havoc if it fell into the wrong hands. Unsurprisingly, the government is not thrilled.

The university first admitted to the US Nuclear Regulatory Commission (NRC) that the quart-sized nuclear material was MIA in October 2017. After reviewing the relevant records, NRC officials docked them for two violations – failing to keep track of the plutonium and failing to provide the full and accurate information about its status. Yet after reviewing the case, the NRC decided to drop the second infraction, “[b]ecause the university took prompt corrective actions after the violations were identified.”

Instead, the officials have decided to simply fine the school $8,500.

According to the Associated Press, researchers from ISU’s nuclear engineering department – who often work closely with the nearby US Department of Energy’s Idaho National Laboratory – obtained the plutonium, alongside 13 other similarly sized samples, soon after the 9/11 attacks in order to develop methods for detecting smuggled radioactive material and determining whether nuclear reactors are leaking.


Believing that the material had been disposed of once the projects concluded, nothing came of the material until last fall, when an employee performing an inventory check discovered that the department only had paperwork documenting the fate of 13 out of 14 plutonium chips.

This set off a wide-ranging search that likely makes the stress of feverishly searching for your car keys before work feel like a day at the spa. The university looked in waste barrels stored on campus and several that had been transferred to other locations, but the piece was not found.

Despite its continued at-large status, Dr Cornelis Van der Schyf, ISU’s vice president for research, reassured the AP that the plutonium was definitely disposed of and that the snafu comes down to a record-keeping issue.

“The radioactive source in question poses no direct health issue or risk to public safety,” he said.


We certainly hope so.

Plutonium-239 is the most commonly used isotope for fission-based nuclear reactors and weapons. And although a critical mass of 11 kilograms (24.2 pounds) is needed to create a nuclear chain reaction, the sample is sufficiently sized to make a “dirty bomb”, according to an NRC spokesman.

On a positive note, exposure to alpha-particle emitting Pu-239 is not acutely dangerous unless its particles enter the air or water, and the piece was last seen in a protective case. Best case scenario, the plutonium is sitting in a sealed bin somewhere, waiting out the 48,200 years until full decay.

A weapons-grade ring of electrorefined plutonium, 99.96 percent purity. The ring shape helps with criticality safety, as the mass is distributed away from itself more than a solid shape would allow. Public domain


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