Nuclear power 101
Water, where to get it and how much, will be a critical issue for any nuclear power plant
By Casey Clark Ney
Argus Observer
Thursday, January 24, 2008 10:29 AM PST
Payette — Nuclear power plants provide 20 percent of America’s power.
If a proposal by MidAmerican Nuclear Energy Co., a subsidiary of MidAmerican Energy Holdings Co., Des Moines, Iowa, gets off the ground in Payette County, that percentage will climb.
Currently the proposed nuclear plant — planned for 3,300 acres south of Paddock Valley Reservoir — is still in the preliminary application phase with the Nuclear Regulatory Commission.
However, in a state predominantly known for hydroelectric power plants, nuclear energy has evolved into a hot topic.
Ralf Bennett of the Idaho National Laboratory (INL) is familiar with both nuclear energy and the Payette plant proposal.
Bennett, who serves as the INL director of international and regional partnerships, is currently working with the Idaho Office of Energy Resources in preparation for MidAmerican’s NRC application process.
Bennett is not in any way affiliated with MidAmerican.
“I’ve been working with them (Idaho Office of Energy Resources) to try to understand what kind of impacts a nuclear plant would have on the state of Idaho,” Bennett said.
Bennett said both the proposed plants in Payette and Owyhee counties are rather large in comparison to the rest of the nation’s nuclear facilities. If approved, the Payette plant would serve as a 1,700-megawatt facility, and the Bruneau plant could potentially generate 1,600 megawatts.
“For the size of plants that are in the United States now, that would be half again as large as the largest. So that’s a big plant,” Bennett said.
Uranium and Fission
According to Bennett, nuclear power plants generate power through a complicated process. In a nutshell, it all begins with fission.
“When fission was discovered back in the ‘30s the idea of splitting the atom was fascinating, but people didn’t have an idea of how to arrange that into a critical reaction,” Bennett said.
Very simply put, fission takes place when the atoms of uranium are split.
“(Fission occurs) if you bring enough uranium fuel together and arrange it in such away that it sustains a neutron reaction,” Bennett said. “When you split uranium atoms, on average, you get about two to three and a half neutrons.”
When done correctly, fission is a continuing process.
“The idea is the little fragments will reabsorb and create even more neutrons,” Bennett said. “Obviously if you wanted to sustain uranium’s fissioning you would want to have one or two of those neutrons absorbed to create the next fission.”
The Core
In a nuclear power plant, fission is moderated through the use of control rods that are pushed into the reactor. The rods are made of boron carbide. They are between 12 and 20 feet long and are slender like a pencil.
“In the large power reactors you have not one, but actually dozens of control rods,” Bennett said. “The operators will grab a group of these rods and move them slowly into the core.”
According to Bennett, a nuclear power plant can have one or more units. Each unit houses one core. The units may be situated next to one another, but they function independently. Each unit produces a considerable amount of heat that then needs cooling water.
Water
In general, a nuclear power plant features one of two kinds of nuclear reactors — a pressurized water reactor or boiling water reactor. Either way, a sizable amount of water is needed for the reactor to work properly. The water is heated by heat from fissioning uranium. This interaction generates steam that in turn propels turbines.
“They are all (nuclear power plants) making steam, putting it into a turbine, that turns a shaft and runs the generator,” Bennett said. Bennett said either reactor works out the same economically in terms of efficiency and water use.
“Water is going to be the No. 1 issue,” Bennett said of Payette County.
Bennett said water is such a key issue because nuclear power plants pull out water from the environment and consume all of it. For example, when a farmer removes 2 acre feet of water from an irrigation ditch he is said to have consumed 1 acre foot. Half of the water is estimated to evaporate, while the other half actually returns to the water table, Bennett said.
“With a nuclear power plant consumption equals withdrawal,” he said. “The guys doing the Payette project need 25,000 acre feet per year. That is a reasonably large amount of water, but it’s not a horrendous amount of water.”
Regardless, the next obvious, and key, question is where will all that water come from?
“You would actually need to buy up the water rights on more than just that property to have enough water,” Bennett said of the project.
In other words, MidAmerican will need to purchase water rights from neighboring residents to secure enough water.
“MidAmerican has not said what exactly they are going to do,” Bennett said. “It’s very important for the plant to say.”
Bennett said details regarding MidAmerican’s plan of attack regarding water will come later in the application process.
Location, Location, Location
Because a nuclear power plant requires a uranium supply to function, the casual observer might presume a facility would need to be situated near such a supply. Bennett said that is not the case.
“The plants are located where you can find a lot of land, where you have enough cooling water to cool the plant and where you can sit next to the population that needs the power or is near transmission lines,” Bennett said.
Payette, Bennett said, has a significant amount of land, and it is near transmission lines.
“The Northwest needs power,” he said.
Why Nuclear Power?
Bennett said the main benefit of nuclear power is it is an efficient power source.
“You have to take the heat out, and if you arrange the cooling correctly, you can get pretty good amounts of electricity,” he said. “It’s an economical base load power supply, and there aren’t many of those. There is coal, nuclear and hydro … It’s hard to supply a city with wind.”
For local residents concerned about the potential hazards the proposed nuclear plant may pose, Bennett said the industry is regulated.
“I guess the thing I like to point out to people is there are many regulations imposed by the NRC.”
Bennett also said the NRC is dedicated to the safe handling of materials and effective practices of nuclear power plant operations.
Casey Clark Ney is a correspondent for the Argus Observer based in Idaho. She holds a B.A. in Communication and has more than six years experience in newspaper writing. She can be contacted at (208) 405-1096.
