DEL MAR — City Council adopted a resolution urging the Nuclear Regulatory Commission to require a public license amendment hearing before SONGS (San Onofre Nuclear Generating Station) is allowed to restart.
The unanimous vote followed presentations from experts on both sides of the issue regarding the troubled generators at San Onofre plant.
Before making the decision at the Sept. 24 meeting, Mayor Carl Hilliard asked Mark Nelson, director of generation, planning and strategy for primary plant owner Southern California Edison, if his company would oppose such a resolution by Del Mar and other cities for a more complete and transparent hearing related to safety issues.
“I certainly don’t think it’s necessary,” Nelson said. “The NRC has laid out a path and we think that that path, along with our regulator, is appropriate.”
Hilliard said any governmental agency should take as much public input as is available to it and embrace the concept of public hearings.
“I’m not sure I understand the reluctance of Edison to endorse that suggestion,” he said.
“I think it’s really an issue of the NRC’s experience and what the regulator sees as reasonable,” Nelson said. “At this point we’ll follow the path of our regulator.”
Unit 2 at SONGS was taken offline Jan. 9 for a scheduled inspection. Unit 3 was shut down Jan. 31 after a small leak was discovered in one of its 19,454 steam generator tubes. The plant has yet to be restarted but Edison may soon submit a request to bring Unit 2 back online.
Daniel Hirsch, a lecturer on nuclear policy at the University of California Santa Cruz, explained that steam generator tubes are important to nuclear power plants because they provide the cooling necessary to avoid a meltdown, which can result in radioactivity being released into the environment.
To transfer heat efficiently, the tubes must be thin. To prevent radioactivity from being released they also need to be strong, Hirsch said.
The original steam generators at SONGS began to fail after about 20 years, he said. Edison bought new ones from Mitsubishi Heavy Industries that had substantial design changes compared to the originals, Hirsch said.
Because of the differences, Edison should have been required to submit a license amendment request to the NRC, Hirsch said. But that would trigger a higher level of review and a possible request from the public for an evidentiary hearing.
So Edison told the NRC this was like a replacement, Hirsch said.
The SONGS tubes have anti-vibration bars and a series of support plates. Each provides a place where there can be rubbing, which can result in thinning, which can cause the tube to burst, Hirsch said.
Hirsch said there are four possible types of rubbing and all occurred at SONGS.
According to an Edison press release read by Hirsch, “The nature of wear is not unusual in new steam generators and is part of equipment settling in.”
Because the NRC didn’t have data to confirm that, Hirsch said he and his students went through every in-service inspection report for every new steam generator in the country that had run for two years, roughly the same period the new SONGS generators were in service.
“The amount of damage is orders of magnitude above the typical reactor,” Hirsch said.
Each has had more tubes plugged, or taken out of service, during this period than the entire country combined, he said. In fact, 14 plants reviewed had no tubes plugged.
The median number of plugged tubes after one cycle of operation nationally is zero. At SONGS there were 510 and 807 in Units 2 and 3, respectively.
He described the number of places where wear had occurred as “staggeringly higher.”
The median number of wear indications after one cycle of operation nationally is four. At SONGS there were 4,721 in Unit 2 and 10,284 in Unit 3.
“So to say that this is standard for similar reactors just isn’t the case,” Hirsch said. “They’re very troubled reactors.”
Once a facility is down for nine months, the Public Utility Commission must initiate an investigation that includes what the costs are, who should pay for them and if the plant is still useful.
“This is a big deal,” Hirsch said. “Eight and a half million people live nearby and we should protect them and we should, at the same time, protect the economy.”
Nelson said Edison compiled a team of international experts from universities and governments, some with 30 or 40 years of experience in the industry, who conducted more than 60,000 inspections “to get to the bottom of what’s going on.”
“There’s a number of places where each tube can be touched so if a tube is vibrating, it’s not unusual for that tube to pick up multiple … indications,” Nelson said. “It’s really just the system saying this tube is hitting in several places.”
He did acknowledge that two of the 19,454 tubes in Unit 2 that were rubbing together in tube-to-tube vibration is unusual.
“Yes, it had a lot of indications and a larger amount of tubes that had been contacted than what’s typically seen in a first in-service inspection,” Nelson said. “But the actual areas that the wear was occurring are areas that are in fact well understood.”
He said the computer modeling underpredicted the steam velocities in some areas where there was tube-to-tube rubbing.
He said the NRC has ruled Edison took appropriate measures to design the steam generators and that it did not need a license amendment.
He said Edison won’t restart the plant until it and the NRC are satisfied it is safe to do so.
“Our next step is to get back to the NRC with a plan for restart (of Unit 2),” he said. “The NRC explicitly is not going to allow us to restart until they’ve approved the plan.”
The NRC has a public meeting schedule for Oct. 9.
Del Mar council members were asked to take a stand on the restart at their June 18 meeting but deferred action until “well-researched” and “very balanced” data could be presented.
As part of the resolution they also support a CUP investigation of the costs and reliability of the plant as well as a comparison of the reliability and costs of SONGS to a future based on alternatives, including efficiency, load management, demand response, renewable energy and energy storage.