By Shawn Raymundo
A recent independent survey of the dry cask storage system at the San Onofre power plant found no evidence of contamination or radiation leakage coming from the canisters containing spent nuclear fuel.
Based on radiation readings taken at the outlet vents on the 51 storage modules where nuclear waste is being stored at the San Onofre Nuclear Generating Station (SONGS), Southern California Edison concluded that its canisters are not leaking—as purported by some members of the community.
“No contamination was found on any of the 51 outlet vents, which indicates that there has never been any leakage from the canisters, and there is no indication of any airborne radioactivity at any of the modules,” Eric Goldin, a certified radiation protection professional, said at SoCal Edison’s quarterly Community Engagement Panel Meeting on Nov. 19.
According to a summary of the radiological survey, which SoCal Edison released ahead of last month’s CEP meeting, the dose rates measured at the outlet vents ranged from as low as 0.04 millirem per hour to 0.3 millirem per hour. The federal dose limit is 25 millirem per year to the public.
The dose readings, Goldin said, are “so low that a radiation area posting is not required according to federal regulations.” He added, “We’re way, way below federal limits.”
The survey, which SoCal Edison contracted Philotechnics Ltd. to conduct, was meant to serve as a response to concerns by San Clemente resident Donna Gilmore, who runs the website San Onofre Safety and has alleged that the Nuclear Horizontal Modular Storage (NUHOMS) canisters at SONGS are leaking.
“Gilmore has essentially postulated the NUHOMS canisters are ‘leaking,’ and that is why Southern California Edison has not surveyed the outlet vents on the top of the storage modules—only the inlet vents at the bottom of the modules,” Edison said in its summary of the survey.
While Edison touted the survey as an effort in transparency, Gilmore on Tuesday, Dec. 1, said she doesn’t trust the findings, mainly because the utility company didn’t photograph or record a video of a reading or measurement taken by a technician from Philotechnics.
“Edison at the previous meeting, they promised they would video or take pictures of the readings, as they were taking them as a measure of trust, and they didn’t do that,” Gilmore said. “There was not one video or photo of the measurements next to the vents. They showed people, but they did not show that. So, I don’t trust them.”
She also questioned why Edison would hire a third-party company, which—Edison noted—was recommended by the Radiological Branch of the California Department of Public Health.
Acknowledging that she doesn’t know much about the company and can’t state for certain whether she trusts it or not, she said the fact that they were chosen by SoCal Edison was enough reason to give her pause.
“It seems strange to me that they would hire somebody … how can somebody be independent when they hired you” to perform a job, she said.
Asked what evidence she had to support the belief that there’s a leak, Gilmore said she didn’t know for certain that there’s a leak, which is why the survey needed to be done.
But citing a report by the Sandia National Laboratory to the Department of Energy regarding the storage, transportation and disposal of spent nuclear fuel, she noted that corrosion and cracking of canisters due to environmental factors were a top priority issue that needs to be solved in the short term.
Responding to Gilmore’s remarks, Edison spokesperson John Dobken said, “The truth of the matter is we went out and hired a contractor recommended by the California Department of Public Health Radiologic Health Branch to conduct a survey with calibrated instruments. They did the survey, and we posted the results in the interest of openness and transparency.”
SoCal Edison publishes radiological data from monitoring devices on its Independent Spent Fuel Storage Installation to the state’s health department.
The company explained in its summary that there are no regulatory requirement and specifications when it comes to measuring the outlet air vents, “because the canisters in the storage modules are welded closed and airtight.”
Dobken further explained that because they’re welded shut, “there’s no pathway for material to exit the canister and go through the outlet vent.” Welds, he continued, “are far better than the mechanical seals” such as bolted-lid casts, when it comes to keeping materials inside the canisters.
Shawn Raymundo is the city editor for the San Clemente Times. He graduated from Arizona State University with a bachelor’s degree in Global Studies. Before joining Picket Fence Media, he worked as the government accountability reporter for the Pacific Daily News in the U.S. territory of Guam. Follow him on Twitter @ShawnzyTsunami and follow San Clemente Times @SCTimesNews.