A new inspection report shows a worker at the Pilgrim Nuclear Power Station was exposed to inhaled radiation in April.
The Aug. 21 report by the U.S. Nuclear Regulatory Commission details an incident first made public by an anonymous letter sent to local activists in May.
A worker performing a survey under the head of the reactor vessel brushed against a contaminated surface, causing radioactive material to become airborne.
Precautions were in order, said commission spokesman Neil Sheehan.
“This really boils down to the fact that they should have had a better work plan in place, where they knew exactly what the worker was getting into,” he said.
According to the report, personnel planning the work evaluated potential levels of airborne contamination, but “the screening relied on non-conservative assumptions about the confinement of the space and potential for resuspension of contamination.”
The screening considered contamination levels on the floor, but not on the underside of the vessel head — where levels were substantially higher. The personnel decided respiratory protection was not necessary, “though using the correct factors would not have supported this conclusion,” the commission said in the report.
The worker received an inhaled dose of 132 millirems of radiation, plus 43 millirems of external exposure.
That’s higher than the 100 millirems the government allows the general public to receive from an operating nuclear plant over an entire year, but far lower than the limit of 5,000 millirems allowed for nuclear workers.
“Nevertheless, we expect the plant to have controls in place to make sure they knew exactly what the dose level would look like when that worker went under the reactor vessel head,” Sheehan said.
Although the legal limit of radiation exposure for workers is 50 times higher than for the public, Sheehan said exposure is generally carefully controlled.
“And part of that is that workers know that they may get a higher dose,” he said. “For members of the public, it's just set at a very much more conservatively adopted level.”
The Pilgrim reactor was shut down in 2019. Holtec Decommissioning International, a subsidiary of Holtec International, is decommissioning the plant. The work includes putting used fuel rods in secure storage, dismantling equipment and making the property safe for reuse.
When the worker’s radiation exposure first came to light in May, Holtec spokesman Patrick O’Brien said the company promptly reported it and implemented corrective action.
“The individual was appropriately monitored at all times for their personal exposure,” O’Brien said in an email. “The dose received by the individual did not approach allowed exposure levels established to ensure worker protection.”
The federal inspection report indicates the exposure was of “low safety significance” and will not result in a formal citation.
