FORT CALHOUN, Neb. — The switch — one that's tripped when Fort Calhoun Nuclear Station needs to safely shut down its reactor — was making an unusual buzzing sound.
Plant engineers looked into it, made some repairs and overall didn't think it was a big deal.
Turns out they didn't understand the problem as well as they thought they did. During a later test, the switch malfunctioned.
The kind of thinking that led to the switch failure at the nuclear power plant 19 miles north of Omaha has now landed the plant in some hot water with federal regulators. More than a mechanical failing, it suggests a culture that's out of step with the assume-nothing, take-no-chances, stay-on-top-of-things approach that's demanded when working with a technology where multiple errors and failures can cascade into very, very bad results.
The switch issue came on the heels of another regulatory write-up Fort Calhoun had received for having inadequate plans for dealing with extremely massive flooding — flooding even greater than the historic high water levels seen at the plant this summer.
Fort Calhoun is one of only two out of the nation's 104 nuclear reactors currently on the U.S. Nuclear Regulatory Commission's list of most-troubled plants, and one of only eight to land on it over the past decade.
It's all caused a great deal of introspection within the plant's owner, the Omaha Public Power District. While the utility's top leaders say the plant remains a safe one, in hindsight they say the staff's safety focus had slipped.
"We had a slow, subtle decline,'' Gary Gates, OPPD's president and CEO, said in an interview during a plant visit last week. "This plant is used to running at a high level of performance. We're embarrassed to be in this situation. This is not how Fort Calhoun runs.''
Gates said he and OPPD are committed to making any changes necessary to restore the NRC's confidence, and he hasn't ruled out management changes. He believes the plant and its 700 workers will emerge in the end stronger and more focused.
Despite the regulatory issues, the plant that typically provides almost one-sixth of the electricity powering lights, TVs and toasters in the Omaha area is preparing to resume operations later this fall after months in a flood-related shutdown mode.
The NRC, OPPD and nuclear power experts all say that the public has nothing to fear from Fort Calhoun's troubles or the restarting of its reactor. They say U.S. nuclear plants are engineered and scrutinized in ways intended to ensure they never reach the point of catastrophe.
Take, for example, that recent switch failure. There are three identical switches that perform the same function at Fort Calhoun, a multiple redundancy built in just in case of such a problem, with two needing to work to shut down the reactor.
And operators also have five different ways they can shut it down manually. They train on each method several times a year in a simulator that is identical to the plant's actual control room, right down to the shade of carpeting.
The NRC and nuclear power experts say it would take a highly unlikely chain of multiple problems, failures and mistakes before the plant could pose a threat to public health.
"That's why, at the end of the day, the citizens of Nebraska were not at safety risk,'' said Dale Klein, a University of Texas professor who formerly was chairman of the NRC's governing board. "The NRC doesn't even want to get close to that.''
In addition to mandated safety equipment and procedures, the regulatory process established by the NRC is set up to trigger federal intervention long before a plant reaches an unsafe condition. The fact the NRC has not ordered Fort Calhoun shut down — something it has the power to do — shows that the agency and its resident inspectors believe OPPD can still operate it without compromising public safety, Klein and others said.
"The system is designed to avoid the kinds of failures that could cause you to have a very bad day,'' said David Lochbaum of the Union of Concerned Scientists, a nuclear power watchdog often consulted by Congress on nuclear safety issues.
The NRC is now set to put Fort Calhoun under an electron microscope. The plant that has two full-time federal inspectors on site soon will be inundated with teams of others who will be scrutinizing all of its operations, going beyond the concerns that landed Fort Calhoun in trouble.
Such a review is likely to cost OPPD ratepayers millions. The publicly owned utility must pay for the inspectors' time, and it also will have to pay for any required improvements in equipment or operations.
The NRC inspectors have been delayed by the summerlong Missouri River surge that until recently had sent a 4-foot tide flowing through the plant's grounds, turning the reactor building and other key structures into islands.
But Gates, who was once the station chief at Fort Calhoun, said OPPD has not been waiting on the NRC.
Since the plant was first shut down in the spring — first for maintenance, then because of the flood — it has gone through its own internal reviews, drawn up an improvement plan and already made changes toward improving Fort Calhoun's safety culture.
Despite all the safety controls in place, Gates said, in nuclear power, nothing should ever be taken for granted.
"The standards are high,'' he said, "and they're high for a reason.''
Indeed, OPPD's recent troubles come in the wake of a nuclear crisis in Japan that has focused worldwide attention on the relative safety of deriving energy by splitting atoms.
A massive earthquake and tsunami crippled the large nuclear plant near Fukushima, causing a partial meltdown of three of its reactors and release of radiation into the environment. While the earthquake and massive wave killed more than 10,000 people, no deaths or injuries have been attributed to the nuclear fallout, which has caused evacuations for several miles around the plant.
The worst U.S. nuclear accident was the 1979 partial meltdown at Three Mile Island in Pennsylvania.
That incident led to huge changes within nuclear power, including a major expansion of staffs at plants, more sharing of information and expertise within the industry and increased scrutiny from federal regulators, who regularly give plants report cards.
The current grading system, adopted by the NRC a decade ago, lists all U.S. nuclear reactors in one of five columns.
In column one are plants that have had no significant recent issues with the NRC. That's where 90 percent of plants typically operate and where Fort Calhoun has resided for most of the decade.
Plants fall into columns two, three or four if the NRC finds problems — which column depends on the number of issues and severity.
In column five, plants are required to shut down. The NRC has never in its history ordered a plant to shut down, though some have halted operations voluntarily in consultation with regulators.
Earlier this month the NRC placed Fort Calhoun into column four of its grading matrix, reserved for the few plants with multiple or repetitive problems that regulators consider significant.
The roots of the downgrade go back to 2009, when an NRC inspector looked over the plant's flood protection plans and found them lacking. Particularly concerning was one part dealing with extremely high waters. It called for stacking sandbags up to 5 feet atop narrow floodgates — something it was not clear the utility had ever even attempted.
The NRC says when inspectors asked for a demonstration, they decided that part of the plan wouldn't hold up.
"Their sandbagging strategy around their buildings wouldn't have worked,'' said Victor Dricks, a spokesman with the NRC's regional office near Dallas.
The NRC also found that Fort Calhoun had missed numerous opportunities to re-examine and update its flood plans, including in 2003 when it received new flood-level projections from the Army Corps of Engineers, the manager of dam flows on the Missouri River.
The NRC determined that under OPPD's old plan, at water levels about 3 feet higher than this summer's high-water mark, Fort Calhoun could have lost both its connection to the outside electrical grid and its backup diesel-powered electrical generators.
Those are the primary sources for keeping power to the pumps that provide vital cooling water to the reactor. Lack of cooling is what creates the potential for overheating that could cause damage to the nuclear core of the plant.
Fort Calhoun still had portable gasoline-powered generators it could have turned to to keep water flowing. And if those would have failed, operators still would have had some time to find other solutions.
The NRC had previously calculated the baseline chances of significant core damage at Fort Calhoun to be 4 in 100,000 in any given year. Regulators found the inadequate flood plan would have increased those odds to 7 in 100,000 — still highly unlikely, but somewhat less unlikely.
"It's not like people were suddenly at much greater risk,'' said Klein, who served as chairman of the NRC in the administration of President George W. Bush. But he said the NRC doesn't like to see any degradation of the operational margin for error. That made it a significant regulatory issue.
In response to the NRC's July 2010 findings, OPPD overhauled its flood plan. While it appears the old plan still would have been adequate to deal with the level of flooding seen this summer, Gates said, there were aspects of the new plan that assisted the utility in its battle against the river.
But before that flood planning problem could be resolved with the NRC, the switch issue arose. What troubled the NRC was not so much the failure of the switch but that its potential to fail was not detected much earlier.
As far back as 2008, engineers noticed in a test that the switch was making a buzzing noise. They opened it up, saw there was a loose coil inside and tightened it.
In April 2010 they noticed it again was making noise and made a similar repair. The switch was scheduled to be replaced during the plant's next maintenance outage, set for April of this year.
But before it could get to that point, the switch failed in a June 2010 test. It later was found that a piece of the coil had broken off and jammed the switch.
Dave Bannister, OPPD's vice president and chief nuclear operator, said plant operators certainly did not ignore the switch problem.
But in evaluating it, they could not come up with a scenario in which a loose coil could cause the switch to fail. If they had dug deeper into the operating experience with similar switches at other nuclear plants, he said, they would have seen the possibility of jamming.
"That was shortsighted on our part,'' he said. And now it's clear the switch should have been replaced immediately.
Given the other available backup switches and the possibility of manual shutdown of the reactor, the failure again only slightly increased the odds of a serious problem at Fort Calhoun.
But it gave Fort Calhoun two strikes, and it was considered particularly significant that both related to systems intended to keep problems at the plant from spinning into much bigger ones. That became Fort Calhoun's ticket to column four.
Aside from those two issues and this summer's flooding, the plant also has faced recent federal scrutiny for a fire in June in a switch gear room that provides power to the plant's pool for spent fuel cooling. The NRC is still investigating the cause and background. Gates said it's unclear whether the fire will lead to another significant safety finding against Fort Calhoun.
NRC officials say they don't yet know whether the issues they've flagged are signs of deeper problems at Fort Calhoun. The upcoming, intensive inspections will look into whether there are more serious root causes.
"Based on what we know, the plant is safe to operate,'' Dricks said. "But they may face a big challenge ahead doing the actions necessary to move them out of column four.''
Lochbaum said equipment failures and procedural problems are typically what land a plant in the NRC's column four. But what both have in common is management. In about half the cases when plants fall to that level, utilities have decided to make management changes, he said.
Ken Dowdy, a union official who works as a maintenance planner at Fort Calhoun, said there are definitely management issues within the plant.
"I can't tell you leadership is wonderful but we're in column four,'' Dowdy said. "That's where the rubber meets the road.''
He declined to specify what he thinks the management issues are but said he has confidence Gates will make necessary changes.
Gates said there already have been some organizational realignments within the plant. He said he can't comment on whether there will be specific changes in personnel. "That merits a very thoughtful process, and that's what we're doing.''
Cooper Nuclear Station, Nebraska's other nuclear power plant, similarly landed in column four within the past decade, degraded in 2002 for lagging emergency preparedness.
The fact that Fort Calhoun and Cooper are two of the eight plants on the list of most troubled plants in that time does raise questions whether the Nebraska utilities are simply too small to operate in the nuclear realm. OPPD and NPPD, the operator of Cooper, are among the smallest utilities in the country with licensed nuclear plants.
In fact, NPPD did not return Cooper to good standing with the NRC in 2004 until it had decided to contract out much day-to-day management of the plant to Entergy, the nation's second-largest nuclear generator.
NPPD officials say overall plant performance, not regulatory matters, was the primary driver for outsourcing Cooper's management. But they say the integration of 10 Entergy employees in key management posts at Cooper, including that of chief nuclear operator, has worked very well.
Gates said no such arrangement is on the table for Fort Calhoun. While OPPD likely will bring in some outside consultants to work through the safety issues, he sees no need for such a drastic overhaul. History has shown OPPD is large enough to safely and economically operate Fort Calhoun, he said.
While operators with more than one nuclear reactor do benefit from sharing operational experience across their entire fleet, OPPD already gets such feedback from a cooperative it formed years ago with other single-reactor utilities.
Klein agreed size should not be an issue. He knows from experience OPPD is capable of properly operating Fort Calhoun.
As NRC chairman he visited Fort Calhoun in 2006, attracted by the ambitious $385 million renovation. He said he was impressed by the attention to detail.
And operators of all sizes can become complacent and slip up, Klein said. The only plant to fall to column four on his watch, Palo Verde in Arizona, is the largest single generating facility in the country, with three big reactors. The other plant currently in column four, Browns Ferry, is operated by the Tennessee Valley Authority, which runs seven reactors at three plants.
In some ways, Gates said, Fort Calhoun benefits from being smaller, making it easier to change the plant's culture. More than anything, that's what he believes Fort Calhoun now needs.
While the plant always has made safety a priority, Gates thinks there has been subtle slippage. He thinks one factor in the switch failure was a conscious falling back on the fact that the plant had redundant systems.
Dowdy, the union representative, agreed.
Changing such mindsets has been central to Fort Calhoun's improvement plans. One change already implemented is making sure there's one person in every meeting at the station whose sole job is to look at any issue discussed through the prism of safety.
"We can't ever assume we're safe as is,'' Gates said. "We need to drive to a deeper answer.''
Dowdy said he thinks everyone at Fort Calhoun is now even more appreciative of the awesome responsibility that goes with producing nuclear power.
"It can be and should be very safe, but you have to respect it,'' he said. "You have to be in awe that we are splitting atoms.''
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