Site manager Don Seaborg says radiation would still exist near a burial pit, and tests have shown no elevated readings.
By Joe Walker email@example.com
"It wasn't a criticality," he said. "We've looked at that with enough people with the right qualifications to say that. If it was a criticality, you'd be able to see it even now with elevated (radiation) readings."
The glow was the subject of an internal memo written Oct. 11 by plant health physicist Ray Carroll. The Sun obtained a copy of the memo Wednesday.
Seaborg said Carroll appropriately wrote the memo, expressing concern about nuclear safety, after talking with employees who recalled seeing the glow. Carroll wrote that if nuclear fission caused the glow, workers in the area of the pit might get a lethal dose of radiation. He recommended barring workers from within 1,000 feet of the pit and installing signs, continuous monitors and flashing red alarms.
The burial yard, which is fenced and locked within the outer plant security fence, is maintained by DOE. Carroll is employed by plant operator USEC Inc., which leases production areas of the plant not controlled by DOE.
USEC Public Affairs Manager Georgann Lookofsky said Carroll's suggestions were not used because radiation surveys of the pit have not shown evidence of a criticality, a term for an uncontrolled nuclear reaction.
Reports of a blue glow or "blue flame" — first seen in the early 1980s over a corner of the burial yard in the northwest part of the plant — also were raised several months ago as DOE investigated the plant's handling of atomic weapons parts during the Cold War, Seaborg said.
Seaborg agreed with Lookofsky that tests have not shown elevated radiation indicative of a criticality. The radiation still would be present even with a reaction in 1996, he said.
The Carroll memo said the glow, reported by some employees as resembling "blue fire," was seen solely after heavy rain with mist just above the ground. "During the first reported sighting, it is my understanding that personnel involved were told to stay out of the area and stay upwind," he wrote.
Carroll wrote that the incidents could have been a rain-induced fission phenomenon called "Cerenkov radiation," in which water looks blue. The glow reportedly was seen several times after the first sighting, until the area was covered with five to nine feet of dirt. There was one report of the glow in 1996, well after the dirt was spread, the memo said.
Seaborg said another reason he discounts a criticality is that the reaction should have caused an upheaval of the dirt, which is undisturbed.
Carroll recommended taking core samples in the burial yard to see if fission products are present, which would mean far more extensive cleanup of the site. But based on the tests already done, Seaborg said he does not favor taking core samples now. The landfill is scheduled to be investigated and cleaned up later, he said.
"I don't see anything that causes the need to change the priorities at this point," Seaborg said. "I'm certainly open to information that says we need to change that."
On Wednesday, the Sun was unable to reach John Volpe, manager of the Radiation Control and Toxic Agents Branch of the Kentucky Cabinet for Health Services. An office spokesman said Volpe was traveling and in meetings.
Volpe, the state's chief radiation expert, told the Louisville Courier-Journal — which reported the memo Wednesday — that he did not have enough information to even speculate about the sightings. But the issue shows why DOE should disclose the landfill's secret contents to the state, he said.
"I have no problems with doing that if they (state officials) have the appropriate clearance," said Seaborg, who has been site manager for the Paducah plant less than a year. "I assume they have been told that previously, because this is a classified burial ground."
Last spring, a DOE investigative team found sections of 17 aluminum nuclear bomb casings, apparently from the early 1960s, standing in an unclassified scrap yard at the plant. Several other half-round parts of bomb sections were stacked in the yard.
Seaborg said the blue color could have come from burning aluminum parts, thought to be buried in the classified landfill. The burning would have come from a reaction with water and other elements in the soil.
"I mention that possibility because aluminum will indeed burn in some forms and has a blue flame," he said. "But that doesn't necessarily mean conditions exist below grade to cause that."
There could be other explanations for the glow, Kimberlee J. Kearfott, a professor of nuclear engineering at the University of Michigan, told the Courier-Journal.
For the glow to be from a fission reaction, there would have to be ‘‘extremely large sources’’ and a vast amount of energy being expended to cause the Cerenkov effect, she said. She said the only places she has seen the blue glow are in a university research reactor under water or in spent fuel rods immersed in water.
She said a more likely scenario is either a chemical fluorescence or phosphorescence or a glow from tritium — a radioactive material that reports say was buried in unknown quantities in the plant’s landfills.
Seaborg told the Sun that Kearfott's observations are astute and could explain the sightings.
DOE weapons-recovery operations took place secretly for decades and ended in the mid-1980s. The department has acknowledged that plant contamination from tritium may have come from some of the weapons work in which tritium was used.
Some nuclear weapons parts were built in the plant’s machine shop and shipped to customers. An earlier DOE memo obtained by the Sun said that while the general practice was to break down and smelt weapons materials, whole weapons, "minus the nuclear package," were buried at the plant.