Nukes 101: Up close and personal with nuclear power
CNET's Martin LaMonica goes inside the Seabrook Station nuclear power plant, one of the U.S.'s fleet of nuclear power plants which generate one-fifth of the country's electricity.
SEABROOK, N.H.--After a period of stagnation, the U.S. nuclear power industry is pushing for another chance--both to build new power plants and to reshape popular opinion.
Earlier this week, I took a tour of the Seabrook Station nuclear power plant on the New Hampshire coast, just north of the Massachusetts border. I got to see some impressive engineering, relearn the physics of nuclear fission, and ponder the future of nuclear power.
In a way, the Seabrook Station reflects the crossroads that nuclear power in the U.S. finds itself at. Construction of the plant, located on a granite peninsula surrounded by a two-mile-long salt marsh, began in the late 1970s but wasn't commissioned until 1990 because of changes in ownership and court challenges from opponents.
Its owners are now seeking to extend its original 40-year license from the U.S. Nuclear Regulatory Commission for another 20 years. In 2000, the NRC extended the license of a nuclear power plant for the first time, which was a turning point. As of last year, it has renewed licenses for more than half of the U.S. fleet of 104 reactors, which generate about 20 percent of the electricity in the U.S.
As the U.S. and the rest of the world try to reduce pollution from power generation, particularly coal plants, nuclear is very much part of the discussion. Although opinion is clearly mixed, even some high-profile environmentalists who had opposed nuclear power in the past have changed their views on nuclear power, which produces no greenhouse emissions during operation.
In the U.S., more than 20 companies have announced plans to submit applications for new nuclear power plants, although only one is now under construction. Meanwhile, another 59 nuclear plants are under construction around the world, with 23 in China alone, according to the Nuclear Energy Institute.
The host for my visit was well trained in demystifying nuclear power, citing safety statistics and procedures (more than 100 people employed for security) and wowing the group of engineers I was with with technical details (water temperature in the reactor is 550 degrees at a pressure of 2,200 pounds per inch). Tours start at the nature and science center, nestled between hiking trails with picnic tables.
We learned in great detail how nuclear fuel is handled when the power plant is shut down every 18 months for refueling, a process that takes about three weeks. During that time, which is scheduled for the lower-demand periods of the spring and fall, other power generators in the New England grid need to step up and fill the gap of 1,200 megawatts that Seabrook Station generates, enough for 1.4 million homes.
Main event
After the briefing, nicknamed Nukes 101 by employees there, we started the five-minute walk toward the "protected area," where the reactor and other buildings are, and eventually made it through security. (We had to submit personal information before coming, but some of the visitors in my group had names that appeared slightly differently on their passports, which caused a slow-down in the computer look-up process.)
During the walk over, we had a physical reminder of the spent fuel storage problem. The Seabrook plant was designed to store 20 years' worth of spent nuclear fuel, and the NRC was supposed to deal with long-term storage of this radioactive material. Well, it hasn't quite worked out that way.
Nuclear waste is now often stored where it was used--at power plants. Seabrook had to build a facility to store the spent fuel assemblies in "dry casks," which are sealed metal cylinders placed in above-ground concrete storage containers. The Department of Energy is now developing an alternative long-term storage plan to Yucca Mountain.
Photos were strictly forbidden in some parts of the facility, notably anything that had to do with security. Since September 11, 2001, stricter physical security measures have been put in place, including more barriers to stop a would-be attacker, either on foot or in a vehicle. Armed guards, including people stationed in watchtowers, can be seen once inside the protected area.
The tour didn't allow us to go into the actual control room or other sensitive areas. (An interesting side note is that since the plant was designed in the 1970s, all of the controls in the control room are analog except for a few digital displays.) But there was plenty to see.
The 180-foot-high dome that houses the reactor was fun to see up close, especially since I just learned that much of the reactor itself is about 40 feet below ground and connected to an adjacent waste disposal building with underground pipes. But another iconic image from nuclear plants--cooling towers--was absent.
Seabrook, like many power plants of all kinds, is located close to the ocean to tap into the cold water supply. At Seabrook, seawater is funneled through three-mile-long underground pipes to the plant, where three giant pumps send the water at half a million gallons a minute to the generating station.
The seawater cools the steam, which runs the turbine and power generator, to turn it back into water. The seawater, which doesn't mix with the reactor water, is then sent back out through the salt-resistant pipes, which are about 22 feet across, to the ocean beyond the nearby beaches. The heat from the plant has created an "island" about one mile offshore where the water is about five degrees hotter than the surrounding area.
Serious juice
Most impressive is the turbine building where the electricity is generated. This is the same system that you would see in any power plant, only this one was bigger than most.
Inside a room that seems as large as an airplane hangar are giant tubes twisting around and connecting to a half-domed machine that stretches from one end of the room to the other. The tubes transport high-pressure steam created by the heat from the nuclear reactor and blast it into the blades of a turbine. There are actually four turbines in a row (three of which are low-pressure turbines) within that half-domed assembly. All of them are connected by a single rotating shaft to a General Electric generator, which is about 20 feet at its highest point.
Right up next to the generator, it was loud, pushing 100 degrees, and the floor was rumbling. After the calm and quiet we experienced walking up to main buildings, this was the moment when you started to comprehend the magnitude of what this plant was doing. From that generator run torrents of electricity carried at 375,000 volts to three separate points on the New England grid.
Below the turbines and generators are two more stories full of machinery that do many other things, including condense the steam back into water, treat the water from one of the three water loops, and circulate hydrogen gas through the generator for cooling.
To finish off, we saw how plant employees are required to track their exposure to radiation. They measure the amount of radioactivity by carrying a device, called a radiation dosimeter, and logging into a computer system that tallies how much a person is exposed to over time in the "radiologically controlled area."
On the way home, it was hard not to be impressed that one location, which is comparable in size to a city block or two, generates enough electricity for well over a million homes. The operation had a serious, business-like atmosphere, which is what you would expect--and hope to see.
With all the talk of modernizing the electric grid and getting consumers to more actively manage energy downstream from power plants, getting a glimpse of the science and engineering upstream at a power plant was a treat.
It was also a reminder of how central nuclear power is to today's grid and how few options there are for utility-scale power generation. According to the Energy Information Association, coal represented almost half of the power generation in the U.S. in 2008, followed by natural gas at 21 percent, nuclear at 20 percent, and hydro with about 6 percent. Biomass and wind are about 1 percent, and solar and geothermal are less than 1 percent.
Seabrook Station's request to extend its permit has brought back opponents in public hearings and it will be interesting to see how the debate has changed since 20 or 30 years ago. A decision on whether to renew its license is expected in 2012.
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