Nuclear plant becomes 1st in US to go digital

Updated: 2011-05-30 11:23


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SENECA, South Carolina - The digital revolution is finally reaching America's nuclear power plants.

Sometime in the next few weeks, technicians will finish installing digital controls for the operating and safety systems of a nuclear plant reactor in western South Carolina, a move being closely watched by other nuclear complexes.

In a nation where a digital blender can be bought for about $30 at Walmart, the Oconee Nuclear Station reactor will be the first of the 104 reactors in the United States not controlled with the same analog technology that brought the world cassette tapes.

While digital control of nuclear plants is widespread in Europe and Asia, the US has been on the sidelines as the digital revolution has brought Americans iPods for their music, movies that stream to their cell phones over the Internet and tiny computers connected to satellites to help them find the store that sells those things.

It has taken US nuclear power plants so long to go digital because regulators wanted assurances the new control systems were as reliable as the old ones and could not be compromised by hackers.

"The systems in the plants right now, they are doing an excellent job. The plants are very safe - they've been doing their jobs for years," said Joe Naser, technical executive with the Electric Power Research Institute.

The goal of going digital is to save money. Most systems in a nuclear power plant are monitors with four sensors. If two of them have out-of-whack readings, engineers often have to "trip" the plant, or shut it down, until the problem is resolved. If a nuclear plant sits idle for a day, it can cost a utility company more than $2 million. That isn't spare change, even for a company like North Carolina-based plant operator Duke Energy, which earned $1.3 billion in 2010.

Unlike a human engineer, who can only take in one measurement at a time from one instrument, the digital system takes in thousands of readings at any moment. The computer can instantly figure out if a sensor is broken and ignore it.

"Those utilities need to keep those plants running. To have unplanned outages as a result of an analog system isn't doing what we need it to do - that's a financial risk," said Jere Jenkins, director of Radiation Labs at Purdue University.

The nuclear plant digital systems will provide operators with much more data about plant operations and a level of precision impossible with an analog system, which often requires the movement of components to get things done.

Other utilities are closely watching. The youngest nuclear plant in the US went online with analog controls in 1996, the same year DVDs were introduced in Japan. More than half of the nation's nuclear power plants are at least 30 years old, and only three have come on since 1990.

"It's to the point where you can't replace that equipment anymore," Jenkins said.

Other nuclear power plants will likely follow Oconee's lead as soon as they can afford it if the conversion goes well, said David Lochbaum, director of the Nuclear Safety Project for the Union of Concerned Scientists.

"There are a lot of eyes on that. If it goes well, you'll probably see many people in the queue making it happen. If it doesn't go well, they are going to wait for Duke Energy to iron out the kinks," Lochbaum said.

The operators at Oconee Nuclear Station will likely encounter a few unexpected glitches as the new system is put in place, but they should all be minor because of extensive testing, Lochbaum said.

Also, Duke Energy said it made sure its engineers can manually take over all digital processes in case there are any problems.

One of the biggest concerns of regulators was worries the software used to run the new controls might be hacked from outside the plant. Documents given to the Nuclear Regulatory Commission show Duke Energy's software provider designed a system with no external network connections. Any communication between the reactor operators and the system is heavily restricted and must be authorized by plant operators.

The new control system at Reactor 1 is part of $2 billion in upgrades that Duke Energy is making to keep its three reactors at the station, which opened in the early 1970s, run safely for the next 30 years. The control panel installation coincides with a planned refueling outage. Reactor 2 will get its new digital panel during next year's refueling, and an upgrade at Reactor 3 is scheduled for 2013. The new panels alone for all three reactors cost $250 million.

Oconee Nuclear Station's reactor operators have spent months training on an exact replica of what the new control panel will look like. And it looks a lot like the old system.

"One of the goals is to make operators' life, I won't say easy, but to make operators more focused on the primary aspects of the job. Just like an airline pilot, you want him to focus on flying the airplane - you don't want him spending all day trying to get the cabin pressure right," said Jeff Hekking, a senior reactor operator who helped test the new system.

During a recent simulation, Hekking and two other operators dealt with a problem with the water that cools the reactor and keeps the nuclear reaction in check. Dinging bells, similar to what someone would use in old movies to summon a hotel bellhop, mark when things first go off kilter. The engineers stay back and let the situation get worse. Dozens of tiny red rectangle lights turn green as the control rods fall back into the reactor core to stop the nuclear reaction. Warning sirens sound, but they are subdued wails, not shrieking claxons.

The engineers then start to control the situation, pushing buttons and pulling levers. Commands are double-checked and repeated to make sure everyone is on the same page.

Reactor operators work on 12-hour shifts. At least three are in the control room of each reactor at all times, even eating their lunches at the gray desks behind flat-screen monitors. Others are doing maintenance, checking components or other tasks, but can be brought into the room if needed.

Hekking, 40, has been a reactor operator for 19 years and is used to working with components manufactured around the time when he was born alongside some of the latest technology, like the control panels being put into place at Oconee.

"Nuclear is a really interesting world," Hekking said. "We have both the oldest and the newest and coolest."


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