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Nuclear plants squeeze power as critics fret SAN FRANCISCO, California (Reuters) -- Blocked by public opinion from building new nuclear plants, operators have been squeezing more electricity out of existing nuclear plants in an effort to meet demand in California and other parts of the country.
But critics warn that the steps -- which range from running a reactor for longer to building new cooling towers -- are putting stress on the plants and could endanger the public.
Although no new nuclear power plant has been built for 20 years, the nation's nuclear fleet -- which accounts for about a fifth of total power production -- has added about 2,200 megawatts in the last decade, the equivalent of two large new plants or enough electricity for 2 million homes.
The Nuclear Energy Institute, a pro-nuclear trade group, expects at least 2,000 megawatts more in the next few years, an institute spokesman said.
But anti-nuclear groups say that coaxing more power out of the nuclear fleet puts more wear and tear on reactors, turbines, cooling systems and the tens of thousands of other pieces of equipment in a plant.
"The industry is running reactors longer and hotter while shortening refueling and maintenance schedules, and this means it is reducing safety margins," said Paul Gunter, a director with the Nuclear Information and Resource Service.
"Age-related deterioration is inevitable in reactors and other equipment," Gunter said. "Power capacity is going up, but this is increasing the risk to public health and safety."
Safety agency The Nuclear Regulatory Commission (NRC), which oversees the nation's atomic plants, must approve power increases, which are known in the industry as "uprates," and permits can take a year or longer to process.
The NRC has 18 projects pending.
An NRC spokeswoman said the agency closely examines "safety barriers" protecting nuclear fuel, reactor coolant systems and "containment" buildings housing the reactor.
The power uprates come from a variety of methods.
Operators can make turbines spin generators faster by removing heavy moisture from steam passing over a turbine's blades. This can add 5 to 10 megawatts per generating unit, and over the next four years the company expects to add between 70 and 90 megawatts to the units' capability.
Another uprate involves building new cooling towers to improve plant efficiency on hot days. New towers at the Exelon Corp.'s Dresden nuclear plant in Illinois saved almost 300 megawatts.
Yet another improvement uses more precise measuring instruments so control room operators can run units closer to their peak capabilities.
Exelon Nuclear, a unit of Chicago-based Exelon Corp., is the nation's largest nuclear operator, running 17 reactors in the Midwest and Mid-Atlantic states.
Through uprates, Exelon said it expects to add about nine million megawatt hours by 2003, the equivalent of building a new 1,200 megawatt plant at a fraction of the cost.
Exelon's uprates carry a construction cost of $300-$400 per kilowatt, well below the $500 to $700 per kilowatt for a new combined-cycle plant fueled by natural gas, and $1,000 to $1,250 per kilowatt for so-called clean coal technology.
Sunnier nuclear outlook under Bush While the Bush administration has given new life to the nuclear industry -- which was put in cold storage by the near meltdown of the Three Mile Island reactor in Pennsylvania in 1979 -- industry executives caution that it may be years before a new reactor is built.
Bush's new energy policy calls for more nuclear power and suggests many of the existing 65 plant sites, scattered throughout 31 states, have room to accommodate more reactors.
In addition to lingering fears about plant safety and "not-in-my-backyard" opposition to new plants, the problem of where to store highly radioactive nuclear waste remains a big obstacle.
California, for example, in 1976 outlawed construction of any new nuclear plants until there was a "demonstrated and approved" technology for a permanent dump site for used fuel rods.
"The outlook for nuclear power in California is pretty dismal," Robert Glynn, chief executive officer of San Francisco-based PG&E Corp., recently told the company's annual meeting of shareholders. PG&E's Pacific Gas & Electric subsidiary runs the Diablo Canyon nuclear plant on California's central coast, which is among the plants boosting production.
"I'm a huge believer that nuclear power should play a part in our energy needs," Michael Morrell, president and chief operating officer of Allegheny Energy Supply Co., a unit of Allegheny Energy Inc. (AYE.N), of Hagerstown, Maryland, said at a recent conference. "But I don't believe there will be a nuclear plant built in my lifetime," the 53 year old executive added.
-- Martin Thompson (firstname.lastname@example.org), June 13, 2001
Apparently they’re changing from a wet cycle to a superheat cycle. This means increasing the temperature of the steam leaving the steam drum while holding the pressure constant. Increasing the temperature of the piping to the turbine decreases the allowable design stress. About the only way to do this is to decrease the safety factor of the design. Over the years I have noticed that safety factors used in designs have been decreasing. Years ago Section VIII of the ASME code had a safety factor of 5 and now the safety factor is 3.5. This allows a more economical design but also increases the risk. The ASME writes the code for nuclear power plants which I believe is Section III of the ASME code. By lowering the safety factor, the owner of a plant is assuming more risk because of increased confidence of the design. However, these plants are 30 years old and radiation over time has a deleterious effect on steel not to mention that the wasting away of the metal due to corrosion. Normally the corrosion allowance is based on a 30 year life. For example if a corrosion allowance for 30 year service is determined to be .125 in, each year a loss of .125 / 30 inch of steel would be expected. After 30 years, the base metal which is the restraining the pressure is steadily being reduced. Lowering the safety factor at a time when the plants are degrading may not be a wise decision.
-- David Williams (DAVIDWILL@prodigy.net), June 13, 2001.
Isn't the only logical answer to build more nuke plants and reduce the stress on the existing ones? This seems like a logical answer to me. Or, am I being naive?
-- QMan (email@example.com), June 14, 2001.
If we switched all of the incandescent light bulbs to compact fluorescents, we could shut down most of the nukes.
Nuclear reactors would be great if we were a planet of peaceful robots, unaffected by ionizing radiation and without any violence (since all reactors synthesize plutonium that can be used to make bombs).
If you factor in the energy required to mine, mill, enrich, etc. the uranium, and the requirement to monitor the nuclear toilets for eons, nuclear energy is not a net source of power.
see www.ratical.org www.medcom.com www.ki4u.com www.noradiation.org www.nirs.org
-- mark (firstname.lastname@example.org), June 14, 2001.
As an experienced mechanical engineer, with experience in structural and thermal analysis, I can vouch that David Williams knows what he is talking about, including his citations to the A.S.M.E. Boiler Code.
This "pushing the envelope" process for nuclear power plants reminds me of what was being done with the Space Shuttle program in the early and mid 1980s. And we all know what happened: One time, the margin of safety fell below zero, and a major disaster ensued. This impelled an effective temporary shutdown and re-vamping of the entire program. I worked as part of the engineering team in 1986, on the post-disaster Space Shuttle solid rocket motor redesign program. Hence, part of what I learned from this project is that this "pushing the envelope" process is what precipitated the disaster.
I fear that history may be about to repeat itself, on a grand scale. Complaining about an electricity crisis now is like complaining about cold weather in Siberia in late October: "Just wait a little, 'cuz you aint seen nothin' yet!"
-- Robert Riggs (email@example.com), June 14, 2001.
Isn't engineering history full of "pushing the envelope" until (often spectacular) failures occur? The examples that come to mind are medieval cathedrals, and iron bridges during the industrial revolution. Also some of the more daring modern architectural designs have undergone this same cycle. See the wonderful books _Why Buildings Stay Up_ and _Why Buildings Fall Down_ (by Salvadori and Levy).
The trend of "excessive" material/redundancy ultimately leading to over-confidence and failure seems to be repeated, whether there are complex engineering analyses to enumerate and manage (supposedly) the risk -- see nuke pipfittings, spacecraft, large bridges and buildings -- or nothing but seat-of-the-pants experience over many generations -- cathedrals.
Who was it who said "History is just one damn thing after another"?
-- Andre Weltman (firstname.lastname@example.org), June 14, 2001.