The US Nuclear Regulatory Commission said on Monday that it is reviewing an incident related to restarting work at the Palisades nuclear reactor in Covert, Michigan.
Viktoria Mitlyng, spokeswoman for the NRC, told The National that there was "no radiological release" and that "no workers or the public have been affected".
The reactor was decommissioned in 2022, but the need for more energy for AI data centres has sparked hopes of a reopening.
Ms Mitlyng said that a "tipped fuel assembly" incident at the plant did not warrant reporting to the NRC, and the watchdog did not need to report it to the public.
The National contacted the NRC after a social media post from long-time nuclear energy critic Edwin Lyman, a physicist and the director of nuclear power safety with the Union of Concerned Scientists.
"An eagle-eyed observer brought to my attention a post on Reddit alleging that Holtec dropped a partially burned nuclear fuel assembly during its fuelling of the Palisades reactor in Michigan more than two weeks ago, yet nothing but silence from either the company or NRC," his post read.
Ms Mitlyng said that the fuel assembly was not dropped, but "tipped".
"Our inspectors will continue monitoring the situation," she said, adding that NRC inspectors at Palisades "have been monitoring restart activities, including all fuel‑handling work, from the beginning".
She also said that Holtec, the owner of the reactor, "has indicated it plans to submit a licence amendment for the retrieval process, which the agency will thoroughly evaluate".
Holtec International, which bought Palisades in 2022, previously indicated that it hopes to restart the plant this year or early in 2027. It has not yet responded to The National's requests for comment.
On a statement posted to Holtec's website shortly after the publication of this article, the company explained the incident that it said occurred on August 30.
"During fuel-loading activities, one fuel assembly tilted from its upright position after it had been placed, and the fuel-handling machine grapple had been disengaged," the statement read.
It said the company contacted the NRC and that the plant personnel evaluated what had happened.
"Fuel loading remains paused while Holtec addresses the affected fuel assembly," the statement continued.
The Holtec Palisades reactor has in recent months cleared several regulatory hurdles. On August 31, Holtec posted pictures showing nuclear fuel bundles were being loaded into the Palisades reactor vessel.
"This photo captures history in the making at Palisades," a caption on the plant's Facebook page read.
"Fuel loading follows more than two years of extensive inspection, maintenance, refurbishment, testing and equipment upgrades across the station, and represents an important step toward returning Palisades to safe and reliable operation."
Last year, the NRC gave Holtec approval to change Palisades's status from decommissioned to eventually operationally licensed.
The nuclear plant first went online in 1971. Over the course of its final 15 years of operations, it was dogged by criticism related to safety.
A 2012 NRC report warned about the work culture at Palisades, where safety concerns were often dismissed. In 2016, security workers at the reactor were placed on leave from the plant, then owned by Entergy, for failing to properly follow fire prevention protocols.
A little more than one year ago, a worker at Palisades fell off a refuelling bridge into a pool of water, although they were not seriously injured.
