Federal regulators want to make certain Nebraska's flood-threatened nuclear reactors have adequate safety measures in place if a dam breaks upstream, so they have asked the U.S. Army Corps of Engineers for its latest analyses on the risks of dam failure.
Six dams constituting one of the nation's largest reservoir systems sit above Fort Calhoun and Cooper Nuclear Stations.
The corps is sending record runoff through the dams, and the consequences for Missouri River communities include broken levees, inundated homes and businesses, submerged highways and threatened power plants.
The Fort Calhoun reactor, taken off-line for maintenance in early April, remains idled because of flooding. The plant has water about 2½ feet high around its buildings. Cooper, which was built on higher ground, remains in operation, but also faces tests.
The NRC's division director of reactor safety, Anton Vegel, requested the dam analysis Wednesday from the district commander of the corps, Col. Robert Ruch, according to a copy of the letter The World-Herald obtained Thursday.
Victor Dricks, spokesman for the Nuclear Regulatory Commission, said the public should not construe the request as an indication of particular worry by the NRC or “inside knowledge” about the dams.
“It is part of an ongoing effort to look at all the information that could possibly impact those two plants,” he said. “We want to make sure we're completely up to date. We're constantly asking questions of (Fort Calhoun and Cooper) and of ourselves: Is there new information? Is there additional information we need to be looking at?”
Over the weekend, the chairman of the Nuclear Regulatory Commission, Gregory Jaczko, toured Cooper and Calhoun. Jaczko also met with Ruch, corps personnel and the utilities that operate the reactors. The Omaha Public Power District owns Fort Calhoun, which is about 20 miles north of Omaha; the Nebraska Public Power District owns Cooper, about 70 miles south of town.
The plants were built about 40 years ago.
In 2009 and 2010, the Corps of Engineers updated its breach analyses of the six dams as part of a nationwide response to the devastation of Hurricane Katrina. Prior to that, the last analyses would have dated to the late 1980s and early 1990s, said Monique Farmer, a corps spokeswoman.
OPPD last updated its own look at flood effects from a dam breach in 2000 at Fort Calhoun. NPPD did so in 2001 for Cooper. Both utilities examined the possibility of dam failures on top of an already flooded river. However, NPPD analyzed a much larger dam failure than OPPD, based on utility documents filed with the NRC.
OPPD's 2000 analysis considered the failure of Fort Randall Dam, the system's fourth largest, while NPPD also studied a failure at Oahe Dam, the system's second largest.
Both utilities concluded their protections were adequate.
NPPD and OPPD declined to comment Thursday on the NRC's request.
David Lochbaum, director of nuclear safety for the Union of Concerned Scientists, said the good news is that the corps' analyses are recent, so the NRC will have much more current information to act upon. Lochbaum is among the people Congress turns to with questions about nuclear reactor safety.
Since the terrorist attacks of Sept. 11, 2001, the nation's dam breach analyses are no longer available to the public.
“Prior to 9/11 we probably would have released this, yes,” said John Remus of the corps. “Dam breach scenarios involve extremely high flows — much higher than we're experiencing now. ... We're not in fear of losing our dams, so this is not information that we need to share.”
What is extraordinary about the current situation is not so much the height of the water behind the dams but the amount of water being flushed from the reservoirs, said John Bertino, head of dam safety for the corps' Omaha district.
The dams are being monitored around the clock and remain robust, corps officials say. In addition to standard inspections, teams of engineers from the Omaha district have been helping at the dams for more than a month.
Additionally, the corps has had electronic sensors on the dams for years.
High release rates have caused erosion in some areas downstream or around the spillways at each of the dams, Bertino said.
On Friday, the corps plans to interrupt spillway releases for several hours at Big Bend Dam so it can check there for possible erosion, he said.
“None of the erosion issues are dam safety concerns,” he said. The dams “are performing really well, just like we designed them ... they have performed to these levels several times before.”
World-Herald staff writer David Hendee contributed to this report.
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