Long-delayed projects designed to protect the Oconee Nuclear Station from catastrophic flood are on schedule, and plans for new “major modifications” will be put forth in the coming months, the station’s owner said Wednesday.
For the first time, Duke Energy publicly shared new proposals to divert rushing waters away from the three reactors in case the 385-foot-high Jocassee Dam were to ever fail upstream.
The fixes — some of which the company said might prove too costly — would be made not to the Jocassee Dam but to the Keowee Dam and areas of the station, Duke officials told Nuclear Regulatory Commission regulators on Wednesday in Atlanta.
The proposals will be formally submitted in December, company officials said.
Meanwhile, other ongoing safety projects — including one designed to provide backup power in case of flood — will meet their newly revised deadlines, the company said.
Earlier this year, the NRC warned Duke that the agency could impose civil fines for the company’s delays in completing safety projects.
The agency ruled against imposing fines so that Duke could complete the backup power system, known as the “protected service water system,” which originally had been scheduled to be completed in 2010.
Over the summer, the NRC extended the deadline to 2016 for the backup power system and alterations to the station’s fire-protection plans.
In its presentation, Oconee site vice president Preston Gillespie assured regulators that they “won’t be before them asking for forgiveness” in 2016 for not completing the projects and that the company has had a new sense of accountability in the first part of this year.
“We will be done by 2016,” Gillespie said.
Eric Leeds, director of the NRC’s Office of Nuclear Reactor Regulation, said the agency hopes the company can follow through comprehensively.
“At this point we are very encouraged by what Duke is doing and very positive about how they’re attacking this issue,” Leeds said. “However, the devil is in the details.”
As the protected service system is completed, Duke will work in conjunction on new safety measures to protect against flood, Oconee licensing manager Dean Hubbard said.
On Wednesday, the company offered several possible fixes, at least one of which they said they might not pursue because of the cost.
The proposals include a discharge diversion wall at the west end of the Keowee Dam and an isolation drain structure in the station’s turbine building to prevent water from infiltrating.
The company also proposed “armoring” the east bank power block and the intake dike to the south of the station. The armoring would involve installing interlocking concrete blocks braced with cable anchors.
Duke ruled out an expensive “hardening” of the bulk of the Keowee Dam, which would involve applying roller compacted concrete.
The final determination on what fixes to implement will come after the company completes its flood hazard analysis required by the federal government in response to the 2011 tsunami-spawned Fukushima nuclear disaster in Japan.
The company had faced a June deadline to submit its final flood hazard evaluation, but the deadline was extended to December so that the company could await an independent analysis of its findings.
“Major modifications will be required” regardless of the findings, Hubbard said.
The modifications are long overdue, nuclear watchdogs say.
In letters last fall, two NRC whistle-blowers said the agency had concealed the threat of dam failure for years.
Internal agency emails and memos, reported by The Greenville News earlier this year, revealed a long history of concern within the agency.
In March, Duke presented to the NRC the findings of a study it conducted to determine how at risk Oconee's 7 1/2-foot flood wall is to a dam failure.
The NRC required Duke to assume a dam failure, which the company did under three scenarios: seismic activity, over-topping because of rainfall and internal flaws in construction, Duke spokeswoman B.J. Gatten said.
The company said that two of three scenarios for dam failure — over-topping and seismic activity — weren't credible threats, Gatten said.
The third scenario, internal flaws in dam construction, is a scenario that Duke is pursuing.
In the presentation Wednesday, Duke officials said that it expected to have the independent analysis completed in November and the findings submitted by December.
The final plan for flood protection is due in March.