Regulators who detected nonconforming rebar at Vogtle Nuclear Power Plant’s expansion site didn’t have to go far to find a similar problem at the V.C. Summer project in nearby South Carolina.
The two projects – each involving two new reactors – are at different stages of completion, but both Southern Nuclear and SCANA Corp. are building Westinghouse AP1000 reactors designed to be nearly identical from site to site.
Today’s emerging fleet of nuclear plants are touted as islands of consistency – like Walmarts and Waffle Houses – whose uniformity can streamline progress or predict challenges.
“The concept is that AP1000s are all the same, and in theory, that could be an advantage,” said Jim Warren, the director of the North Carolina-based energy and climate watchdog group NC Warn.
The Vogtle project, representing the first new nuclear power reactors to be built in the U.S. in a generation, will be closely watched for its successes and failures, he said, and problems there could very well emerge at other sites.
“But if you start off wrong there, with V.C. Summer close behind, then you eliminate a lot of the ability to make corrections as you go along,” said Warren, a critic of nuclear power.
The nonconforming rebar found by Nuclear Regulatory Commission inspectors at Plant Vogtle prompted a halt to further installation.
Southern Nuclear plans to remove the material and replace it, even though it could impact the $14 billion expansion’s schedule.
SCANA is now working to resolve a similar problem at its $10 billion project, according to the company’s newest U.S. Securities & Exchange Commission filing.
“The NRC recently questioned certain changes made to the specifications for constructing the reinforcement steel – or rebar – cages that will ultimately be placed into the excavation site of the units,” company officials said, adding that rebar construction has ceased while a resolution to the problem is negotiated.
Southern Nuclear has already notified the NRC that there could be as many as 32 separate license amendment requests filed for the Vogtle project during the next three years to address issues ranging from the location of vents to enhancements in electrical control systems and placement of radiation monitors.
Each change requires an amendment if it conflicts with the AP1000 design affirmed by the NRC.
Warren believes those changes, and others yet to be revealed, could affect both the completion schedules and the costs of the projects, some of which are borne by ratepayers.
“That is the multibillion-dollar question: Will Vogtle’s license amendment requests benefit those who come behind them?” Warren said. “It is such complex technology, and such an incredibly complicated construction project schedule, that sometimes it’s hard to see what is really happening.”
The numerous changes to be sought through Vogtle’s license amendment requests do not necessarily mean the Summer project will do the same thing, said SCANA spokeswoman Rhonda O’Banion.
“SCE&G must submit an independent license amendment request for V.C. Summer Units 2 and 3 for any change that we may request,” she said, noting that both Summer and Vogtle hold their own combined operating licenses issued separately by the NRC.
Steve Higginbottom, a spokesman for Southern Nuclear, said amendments made at Vogtle could still benefit subsequent AP1000 projects.
“License amendments for the first plant to file do not automatically become accepted for the next plant,” he said. “Once a standard amendment is filed, the next plant up can file the exact same amendment.”
Although Vogtle and Summer include the first AP1000 units built in the U.S., China is about 24 months ahead with its effort to build four AP1000 units at its Haiyang and Sanmen nuclear stations, where American engineers are watching and learning.
Because of the consistency in design, Southern Nuclear’s representative in China has found that project to be a source of lessons learned that could be applicable to the Burke County site.
One change that has already occurred at Vogtle was the process used to build the containment vessel’s bottom head.
The Chinese built the first one upside down, but challenges associated with flipping the dome-shaped structure over to install it prompted a decision to build other ones right-side up.
The bottom head for Unit 3 is now being assembled in a bowl-like fashion.
Currently, Vogtle’s new units are scheduled to begin operation in 2016 and 2017, with V.C. Summer’s units going online in 2017 and 2018.