Near-accident at San Onofre causes concern
Nearly two-and-a-half hours into an Aug. 9 meeting in Oceanside on the decommissioning of San Onofre Nuclear Generating Station (SONGS) came the announcement of a near-accident the week prior. The news was delivered by Occupational Safety and Health Administration inspector David Fritch during the Community Engagement panel.
Fritch told the stunned attendees that when workers using a crane were moving a canister containing spent nuclear fuel, it became lodged at the top of the cavity enclosure container (CEC) it was being deposited into. Although workers thought the canister was being lowered, it was, in fact, not moving at all.
It takes a minute for a canister to be loaded into the storage container and after 30 seconds, when the workers saw that the multi-purpose canister (MPC) was no longer moving, they assumed that it was safely at the bottom of the container. Instead, it was hanging from the guide ring along the top of the CEC, 18 feet in the air.
According to Fritch, the failure to notice that the canister was not moving meant that it could have fallen, an observation that caused considerable concern among citizens and activists who worry about the procedures to safely move and store the irradiated material.
One of those people is Ray Lutz, an engineer and founder of Citizens Oversight, who has demanded that the California Coastal Commission conduct a full investigation into the near-miss incident.
“I have many concerns about what happened here,” Lutz said. “Yes, there’s a thick bottom plate on the canisters but it’s welded to sides that are only five-eighths thick. Computer model testing shows that canisters dropped from a height of 25 feet will not fail. But the models are based on canisters designed for transportation or transfer, which are much thicker.”
The canisters weigh 104,000 pounds, the equivalent of 44 cars, and Lutz asserts that intuitively it makes sense that something that heavy falling 18 feet would suffer substantial damage. “If the sides of the canister had been breached the radioactive fuel would more than likely overheat and there would be no way to cool it down.” He said that the biggest risk wouldn’t be a meltdown in this case, but a critical reaction causing an explosion that would put radioactive particulate matter into the water and air.
According to Lutz, the workers are also in danger when moving the canisters because the process requires one of them to look down into the CEC to make sure that the MPC is moving, which exposes that worker to high levels of radiation. “There has to be another way for them to know if it’s going OK other than someone actually having to look down into the hole,” Lutz said. He suggested that a better way of monitoring the MPC’s movement would be to install a GoPro camera above the CEC.
San Onofre Nuclear Generating Station. Courtesy photo
The fact that a whistle-blower alerted the public to the close call disturbs Lutz. “I’m disappointed but not surprised that Edison didn’t tell us what had happened before the whistle-blower came forward,” he said. “Fritch’s report talks about a bad safety culture at the facility, saying that the staff is undertrained, understaffed and doesn’t communicate lessons learned with new workers. I’m worried that they can’t be trusted.”
David Lochbaum, the director of the Nuclear Safety Project for the Union of Concerned Scientists, disagrees with Lutz. When asked about the possibility of a canister being damaged and releasing radioactive matter into the air Lochbaum replied: “Calculations show that the canister would have remained intact.”
In a slide presentation Lochbaum prepared to explain what had happened during the incident, he asserted that although irradiated fuel inside the MPC might have been damaged had it fallen, the canister itself would have remained intact.
In response to The Coast News asking about the reasonableness of assuming that 44 cars tied together falling 18 feet would cause significant damage to the vehicles, resulting in fuel and oil leakage Lochbaum replied: “I’m an engineer. But I have a degree in and experience in nuclear engineering, not railroad engineering. The evaluations that I reviewed for San Onofre and other nuclear plants examine the forces imparted on the structure of the canister when a dropped canister hits bottom. The material properties of the canister’s walls are known. The evaluations examine whether the forces cause the material to fail. While the evaluations show that the forces might deform or bend the material, the material is thick even and strong enough to prevent a through-wall breach.”
Lochbaum said that even if the canister had fallen 30 feet there would have been no danger of radiation leaking. Lutz disagrees. “He is confusing computer models of transportation or transfer casks, which surround the interior canister, and in those models, the interior canister was considered a rigid cylinder, which could not be damaged.” Lutz went on to say that he challenges Lochbaum to come up with substantiation for his “off-hand” remarks that bare canisters have been modeled and don’t sustain damage when dropped 18 feet.
Southern California Edison suspended spent fuel downloading on Aug. 3, the day of the near-miss. On Aug. 16 Tom Palmisano, vice-president, Decommissioning and Chief Nuclear Officer at SONGS, wrote in a letter to CEP panel members: “SCE is committed to protecting the safety of the public and takes these incidents very seriously as it progresses through the decommissioning process. I will provide your further updates as we complete our actions.”
A total of 73 canisters at the facility must be moved from “wet storage” to the dry storage containers. So far, 29 have been moved.