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[imgcontainer] [img:cooper-from-above530.jpg] [source]Utilities Service Alliance[/source] The Cooper Power Station, on the Missouri River in Brownville, Nebraska. [/imgcontainer]
On a ridge outside the northwest Missouri town of Rock Port, population 1395, four wind turbines generate enough electricity to power the town. If you perched on top of one of those tall towers, you’d be able to see across the Missouri River, and to spot Brownville, Nebraska (pop. 185), home of the Cooper Nuclear Station. The Cooper power plant could light up many, many towns the size of Rock Port: its gross generating capacity is 800 megawatts of electricity. Per hour.
Nuclear plants emit no greenhouse gasses. They take up a less space than fossil-fuel burning power plants require and a teeny, tiny fraction of the space needed for a wind farm producing comparable amounts of electricity. The first commercial nuclear power plant in the U.S., the Shippingsport Reactor in Pennsylvania, began operations over fifty years ago. Today there are 103 nuclear plants in the U.S., most of them east of the Mississippi. Nuclear power has been championed as an efficient and inexpensive source of energy and condemned as a peril to the human health and the environment.
But as the debate over green energy continues to heat up, there’s renewed interest in nuclear power. Could it possibly be “greener” than sprawling wind farms, or coal-fired plant belching CO2?
I decided to look inside one of these mysterious powerhouses, and sought permission to visit Nebraska’s Cooper plant. It’s managed by Entergy for the Nebraska Public Power District (NPPD), and representatives from the company and NPPD offered me a tour.
[imgcontainer] [img:cooper-couch-530.jpg] [source]Glenn Troester[/source] Author Julianne Couch and one of her guides, Mark Becker of Nebraska Public Power District, inside the Cooper Nuclear Station. [/imgcontainer]
Mark Becker of NPPD came down from his office in Columbus to meet me in Auburn, about 15 miles west of Brownville. Auburn is where one can find motels, restaurants, and many of the plant’s 750 employees. Over sandwiches at the Wheeler Inn, Becker explained that Cooper is a “base load plant,” meaning it runs at full capacity all the time, unlike the wind farm across the river, for example, which provides power only when the wind blows.
Construction on the Cooper plant started in 1968, and commercial operation began in 1974. Its operating license will expire in 2014. The plant is in the process of renewing its license with the Nuclear Regulatory Commission. The application includes 1,176 pages of documentation about safety and 649 pages for the environmental review. If approved, Cooper could operate for twenty more years.
[imgcontainer right] [img:cooper-boiling-water-plant3.jpg] [source]Energy Information Administration[/source] A typical boiling-water nuclear reactor: the fission reaction heats water, creating steam that turns the turbine, producing electricity. [/imgcontainer]
At the Cooper plant, boiling water makes steam to turn turbines to create electricity, much like other types of plants. But rather than burning coal or some other fossil fuel, Cooper uses enriched uranium fuel to create heat. The elephant in the room, of course, is what one does with the highly radioactive used fuel once its heat-generating capacity is spent.
I arrived at Cooper punctually at 0800, driving past the small state park where Lewis and Clark once camped. I had submitted my Social Security number to Glenn Troester, the plant’s communications coordinator, a few weeks earlier so that I could be cleared to visit. I’d also been given a list of rules before entering the plant and took care to follow them all: no synthetic fibers (they attract radon particles); no shoes with metal shanks (they set off metal detectors); no lip balm (on lips ok, in pocket not ok); photo ID, yes; “knives, ammunition, firearms, fireworks, or anything else that goes pop, zip, buzz, hummm, whirr, zing, hiss or even pffft” – definitely no.
Glenn, Mark and I met in the plant’s Learning Center, where Troester explained how uranium is mined, then enriched for fuel in places such as Paducah, Kentucky. The fuel comes in the form of ceramic pellets. Troester handed me an information card with a plastic bubble window. Inside was a half-inch long simulated fuel pellet. At present, a bundle of uranium costs $645,000. If that pellet had been real uranium, it could create the energy equal to 149 gallons of oil, one ton of coal, or 17,000 cubic feet of natural gas.
[imgcontainer left] [img:cooper-HANDLING-FUEL-320.jpg] [source]Glenn Troesler[/source] A fuel handler at the Cooper plant guides rods containing uranium to the inspection stand. [/imgcontainer]
The real uranium pellets are encased in zirconium tubes, or fuel rods. Around 33,000 of those rods, assembled into 548 fuel bundles, are contained in the reactor. That’s where the U-235 isotope, which fissions readily, joins with the U-238 isotope (basically the “designated driver” in this process). Inside the reactor, these materials bounce and jostle against one another, creating a fission chain-reaction tempered and regulated with water.
Becker and most other observers of nuclear energy believe that the plan to create a central depository for used fuel at Yucca Mountain, Nevada, won’t come to pass. That leaves each plant, for now, pretty much up to its own devices for figuring out how and where to store used fuel.
The first stop on our tour was the Learning Center window, to see the Used Fuel Dry Cask storage area, Cooper’s solution to the storage problem, for now. This man-made reverse mountain of concrete and steel is connected not just to the ground but to the bedrock below. The used fuel in this dry cask must be cooled for at least a year in the used fuel pool. That’s basically a 38-foot deep swimming pool for the extremely hot and highly radioactive fuel rods that have been removed at the end of their lifespan.
Before we could see the pool or other places in the Radioactive Control Area (RCA), we had to pass through security. As you’d hope and expect, security at a nuclear plant is anything but casual. It starts with the approach to the plant and the view of imposing gates topped with razor wire. Guards on watchtowers are armed with military-grade assault rifles. They can pretty much shoot anyone whose actions will threaten the plant or the people in it. More armed guards are stationed on the ground outside and around the control room at the heart of the plant. They aren’t in the RCA area though. (No one should tarry in a radiation area.)
Before entering the Radioactive Control Area, we all signed release forms saying we knew what we were doing; we then went through an airport-style metal detector with our small belongings sliding through an X-Ray machine. Then we headed for what amounted to a reception area at the RCA to pick up our “trip ticket” cards and a direct reading dosimeter, a machine that monitors radiation levels along the tour route. Visitors are required to know what normal radiation levels would be along the tour route, so we filled out the trip tickets affirming that we knew this information before starting the tour.
Signage reminded us of all to be aware of As Low As Reasonably Possible exposure, when it comes to radioactive material. Troester’s goal for his tour charges was an expected gamma ray dose of less than 0.3 millirem (mrem) for the entire tour. Reassuringly, our Expected Contamination Level was 0.
[imgcontainer] [img:cooperFUEL-INSPECTIONS530.jpg] [source]Glenn Troesler[/source] Reactor engineers and fuel inspectors at Cooper check every fuel bundle for defects that could cause the fuel to fail. [/imgcontainer]
Although Troester had been in the RCA many times over his nine years at Cooper, he estimated that his total accumulated dose has been less than 40 mrem. The dosimeters the three of us wore were programmed to beep loudly if we entered an area where, were we to stay for an hour, we would be exposed to 10 mrem. If a visitor milled around in the RCA long enough to be exposed to 50 mrem of radiation, the alarm would also “holler,” Troester explained. (He said that if someone on a typical tour received even two mrem, the tour leader would have a lot of explaining to do.)
So we entered the Radiation Control Area, inserting plastic cards like hotel room keys in and out of door locks, being pulled into sensitive areas by Troester, and pushed out of them when it was time to leave. We passed down long halls with exposed pipes – blue for water circulation, red for fire protection.
We moved to the Reactor Building until we reached two heavy steel doors separated by a small room called an airlock. Troester said that the reactor building is kept pressurized at a slight vacuum, the airlock ensuring that air from inside the reactor building does not escape into the hallway outside. We had to make sure one door was completely closed before opening the other door.
When we exited the airlock and entered the reactor building, the first thing we encountered was a magenta and yellow “High Radiation Area” sign on a massive door. The door is the gateway to the “drywell” housing the nuclear reactor itself.
There were magenta and yellow ropes in several areas, with “Contaminated Area” signs on them. (I wasn’t sure how I could be safe on one side of the rope but not two inches on the other side of it, though I didn’t question this.)
[imgcontainer] [img:CooperHydraulicControl530.jpg] [source]Glenn Troester[/source] The hydraulic control units, where control rods are driven into the reactor to shut it down. [/imgcontainer]
Troester showed us the hydraulic control units that drive control rods into the reactor to shut it down. The units are pressurized, he said, and can automatically stop the reactor in seconds without any human intervention if needed, without requiring any electricity or other external power. Troester explained that this is one of many defense-in-depth, redundant systems that keep the plant safe.
Probably it was just psychological, but when we found ourselves standing right above the dry well, which contains the reactor, I felt like the fillings in my teeth were coming to life. True, there was at least 30 feet –18 of it, concrete and steel — between the bottoms of our feet and the top of the dry well, with the reactor itself well below that, but it still was an eerie feeling.
[imgcontainer] [img:cooper-UsedFuel530.jpg] [source]Glenn Troester[/source] Spent uranium fuel bundles are stored in a pool to cool. [/imgcontainer]
Troester showed us the Used Fuel Pool, in which almost all the fuel bundles the station has consumed since 1974 have floated, keeping innocuously cool. Eventually, those bundles will enter the longer term, temporary Dry Cask fuel area we’d viewed from the window of the Learning Center.
We made a few more stops in the radioactive area of the plant, with me feeling guilty each time I asked Troester to photograph something for me. He occasionally stopped to read our electronic alarms for radiation dosage levels to make sure we didn’t breach As Low As Reasonably Possible exposure. He pointed out the Standby Liquid Control area, which would coat the reactor with boron if the reactor needed to be shut down and the hydraulic control units couldn’t insert the control rods into the reactor. This, he said, is another redundant safety system.
All nuclear plants of Cooper’s vintage undergo “aging management”: an effort to repair or replace pipes, wires and other mechanical systems before any age-related failures. (Troester and Becker joked that “aging management” could refer to them and some other members of the Cooper team, too.) My tour guides said that this protocol, along with redundant safety measures, makes American nuclear power plants some of the safest industrial facilities in the world, (they also stressed that constant replacement of parts adds to the expense of operating a nuclear power plant).
Next we moved to the control room, outside of which another man with a rifle stood unobtrusively. We did not enter the control room itself but stood in a glass-enclosed corridor while Troester described the functions of various panels of knobs, levers, dials and computer screens.
One of the panels, illuminated with red lights, displayed a representation of the reactor. Troester said that when a control rod is withdrawn from the reactor, so that the nuclear reaction can occur, the light turns red; when the control rods are inserted, and the reactor is shut down, all the lights are green. Red means on, and green means off. When the reactor is operating, Troester said, the operators – licensed by the federal government – need to be highly vigilant at all times. The red lights on the control room panels signal this need for vigilance and caution. When the reactor is shut down, green lights mean the plant is in safe condition.
But even when it’s safely shut down, the system still produces heat. To cool the plant, Cooper uses feed water. And they have plenty of it – the Missouri River is right outside the door. Workers here designate locations around the plant by feet above sea level. The “ground floor” of the Cooper station is 903 feet above sea level; the used-fuel pool is at 1001-feet elevation. We made one of our last stops on the tour at 932 feet, the turbine operation deck, which is Cooper’s reason for being – where electricity is created. The plant employs two low-pressure turbines and one-high pressure turbine, driven by steam from the reactor. The steam carries radioactive materials with it, so the turbine generator system at a boiling-water nuclear plant is inside the radioactive-controlled area.
Also, boiling water reactors produce radioactive gasses. They’re released from a 100-meter stack outside at the Cooper plant. Troester said that the release of radioactive gases is strictly limited by federal and state permits and is closely and continuously monitored.
[imgcontainer right] [img:cooper-Locked320.jpg] [source]Glenn Troesler[/source] Locked High Radiation Area, at the Cooper Nuclear Station. [/imgcontainer]
After about 45 minutes in the radiation area of the station, it was time to head to a safer area of the plant. Repeating the complicated sequence of door openings and closings and electronic pass-card readings, we entered the RCA access point, where we stepped into personnel contamination monitors that scanned our clothes and exposed skin for traces of contamination. Even common radon gas found in most homes in America would send a signal to the monitors, and prevent someone from leaving the radioactive control area.
Once we’d been checked by the contamination sensors, we turned in our dosimeters and learned that our radioactive dose for the tour was 0.035 mrem, just a fraction higher than Troester’s .03 mrem goal, (far below the 6 mrem of a chest x-ray, or even the 1 mrem of one “bite-wing” dental x-ray).
Back outdoors in the high-security “protected area,” we saw a maze of fences designed to impede anyone seeking to enter the station by force, slowing them down enough so that security officers could detect their presence and open fire to stop them. (Knowing this system was in place made me feel at once safe and afraid I’d be possessed by involuntary attention-attracting spasms.) We also saw huge blue tanks outside that hold water used to replace what’s lost in the boiling process. Troester pointed out an extensive array of high tech resins used, he said, to filter and “polish” the reactor-system water to remove radiation and impurities.
Water from the Missouri River is used to condense steam back into water, and to keep the many safety systems cool. River water and the pristine-pure reactor system water are never allowed to mingle in any way, Troester said; each water type is in its own isolated and self-contained system of pipes, valves and pumps. After the river water absorbs heat from the plant, it’s filtered; this process, according to Troester, removes any trace of radiation or contamination before the water is discharged back into the river. He said that the discharged water must meet strict federal and state temperature limits to protect fish and other aquatic life.
We visited the intake building (where another heavily armed security officer was posted) and saw how water from the Missouri is drawn into the plant through a system of screens designed for keeping out fish, logs and detritus. A fish diverter enables live fish and turtles to escape. But dead wildlife ends up in a large, very smelly bin.
[imgcontainer] [img:cooper-exterior530.jpg] [source]Julianne Couch[/source] The Cooper Nuclear Station is a major employer in Auburn, Nebraska. [/imgcontainer]
Making our way back to the security area, we turned in our green visitor hard hats, safety glasses, visitor badges and gizmos, and talked about what life would be like at the plant over the next few months.
Glenn Troester will be receiving visitors from the Nuclear Regulatory Commission as part of the plant’s license renewal. In October the plant will undergo a refueling outage, which happens once every 18 months. At that time approximately 700 additional workers will flood the area, rotating out used fuel and replacing it with new, as well as performing other inspections and maintenance tasks. For about 35 days, the Nebraska Public Power District will have to replace the power from Cooper with other electricity generated in Nebraska or neighboring states. Outages are planned for times of the year when electricity demand from air-conditioning and irrigation are lowest.
According to Mark Becker, the whole town of Auburn gets excited about the hubbub of the refueling outage. “We are very grateful to have the plant here,” said Auburn’s mayor Bob Engels, “not just for the economic
value but for the commitment those people have to our area. They are
great partners.” he said.Who wouldn’t get excited, with all that money flowing into the area for most likely another 20 years if the plant’s license renewal is successful?
Gazing back over the river into Rock Port, one can see the wind turbines, useful on the small scale but inefficient as a solo form of power. Some place between the ancient technology of wind and the atomic-era technology of nuclear may lie the recipe for our country’s energy needs.
For more of Julianne Couch’s adventures in energy production, see her weblog, PowerTourist.