Davis–Besse is running again, generating 7.7 billion kilowatt-hours of electricity in 2007, with a new reactor head scavenged from an uncompleted nuclear power plant in Michigan. "The NRC has no concerns," Burnell says.
Davis–Besse and FirstEnergy are not alone. Since 1979, after Three Mile Island partially melted down, U.S. nuclear reactors have had to shut down for a year or more for repairs or other safety improvements 46 times, according to the Union of Concerned Scientists. For example, in February 2000 a steam generator tube abruptly ruptured at the Indian Point nuclear power plant in Buchanan, N.Y.—a potential problem first identified in 1997 that had not been fixed.
All told, only four incidents in the history of the nuclear power industry have been worse than the cavity at Davis–Besse, and two have been roughly equivalent, according to the NRC, such as a radioactive steam pipe burst at PSEG's Salem nuclear generating station in New Jersey.
Even as the U.S. considers building as many as 26 new reactors, 51 of the 104 currently operating have received clearance from the NRC to extend their generating lives by 20 or more years. And the remainder are either under review by the agency or expected to apply. The question: Are they safe?
Inside the bathtub
At issue in the failure at Davis–Besse is the alloy metal used to craft the nozzles—known as Inconel 600 or Alloy 600. The alloy of nickel, chromium and iron is resistant to corrosion generally—but slowly cracks when exposed to boric acid and stress.
But it isn't just reactor heads that are made from the stuff. The steam generators that transfer the heat from the solution of water and boron, which comes into contact with the nuclear reactor, to the water heated into steam that turns the turbines to produce electricity also employ the alloy. "The tubes in the steam generators were susceptible to cracking," says Ken Karwoski, senior level advisor for steam generators and material inspection at the NRC's Office of Nuclear Reactor Regulation. "It's a combination of the temperature and the water chemistry."
In the 1970s and 1980s there were several such tubes that actually ruptured, and nuclear operators have employed patches to keep damaged steam generators in service (although this cuts down on the efficiency in generating power). But many have chosen to completely replace their steam generators since 1989 at a cost of as much as $600 million.
As early as the late 1950s there was some suggestion that this metal would crack under pressure but "the decision was made to go with this material," Karwoski says. "The perspective was that it should last but it didn't." And, as of today, there are still 15 nuclear power plants, including Davis–Besse, employing their old steam generators made from the alloy.
The U.S. fleet of 104 nuclear reactors—most built in the 1960s and 1970s—produced 806.5 billion kilowatt-hours of electricity in 2007, a record, and ran almost 92 percent of the time.
But metal fatigue, embrittled concrete (and even rotting wood in the case of Vermont Yankee) have all plagued the nation's aging fleet. Counterintuitively, though, the bulk of problems with these reactors occurred during their first decade of operation—a fact that bodes ill for the next round of nuclear power plant construction. "There will be deficiencies or defects that occur as you start new plants up, even though new plants are simpler and have fewer components," says Adrian Heymer, senior director for strategic programs at the Nuclear Energy Institute, an industry group. "There's always minor adjustments you have to make to the equipment."
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25 Comments
Add CommentYou should be careful to point out that while the average American receives 350 millirems of radiation per year from natural sources, that number varies from as low as 200 in some places to as high as 600 in others, just because of the local geology and environment. In some parts of the world the background radiation is several thousand millirem per year. So far, attempts to find any link between increased background radiation and cancer risk have found nothing.
Reply | Report Abuse | Link to thisYou say that the radiation in the Chernobyl accident escaped the "containment". I think it is fair to point out that the reactor did not have a containment building. Every plant in the US and I believe the world now has a containment building made of thick steel and reinforced concrete. At best they had a brick building surrounding the entire facility not the reactor. They were using the plant for Plutonium production which can be done more quickly if one has easy access to the fuel rods for replacement.
Reply | Report Abuse | Link to thisThere are always risks in any venture. The consequences of a failure in nuclear reactors are higher than with many other ventures. So, even if the chances of failure are low, that has to be weighed against the potential damage of such a failure. One of the problems of expanding nuclear power is that the overall risk of failure, or serious accident, must necessarily statistically increase, even if new build is inherently safer. This increased risk must be a factor when considering increased generation from nuclear power.
Reply | Report Abuse | Link to thisOver the last 30-40 years we have never had an accident that caused any type of harm to the public. I would say that proves, in America, that we are concerned for the public when it comes to nuclear energy. Furthermore, the records of our plants safety and efficiency is also proof that nuclear should be a viable energy source we should venture into expanding. This would alleviate alot of foreign dependancy and also help gain some of the technological edge and industry we have lost or given up. Just think of the extra industry that would spin off for the need of uranium, heavy castings, steel, etc.
Reply | Report Abuse | Link to thisThis is assuming that we are informed fully of ALL of the nuclear radiative releases - I understand that we are NOT. There are releases on a routine basis that result in unknown fallout and effects on the atmosphere. I would be cautious about claiming any comprehensive knowledge of what is being released into our environment. VERY cautious.
Reply | Report Abuse | Link to thisThree Mile Island did indeed result in deaths and cancers. Read some Ernest Sternglass and Helen Caldicott for some perspective (and they are not the only sources of information). Consider that historic ties with nuclear weapon industry and you have a answer as to the accountability of the nuclear power industry.
Reply | Report Abuse | Link to thisIf you read Sternglass and Caldicott, do so remembering that their zeal for their cause allows them to take a broader view of "truth" than would be taken by someone who was limited to working with reality.
Reply | Report Abuse | Link to thisHave you read and analyzed Sternglass and Caldicott and answered their many charges one by one? If not then opinions such as yours should be ignored... let's see the counter arguments.
Reply | Report Abuse | Link to thisSo how about the Union of Concerned Scientists www.ucsusa.org - not 'dealing with reality'? Care to offer counter-analyses that says they are wrong (and I would say that they are pretty 'conservative' in their assessments).
Reply | Report Abuse | Link to thisOnly matched by the unmitigated zeal of the uninformed and the greedy.
Reply | Report Abuse | Link to thisNuclear power is neither affordable, safe or practical in solving our energy problems. Consider just the following:
Reply | Report Abuse | Link to thisPhysicist Dr. Tom Cochran extrapolated from the nuclear industry calculations for its future and found that by adding 700 gigawatts of nuclear electricity to the world – double today’s capacity – for the fifty years from 2050 to 2100 would entail:
• Adding about 1,200 new nuclear plants (provided they last forty years and have no meltdowns);
• Adding fifteen new uranium enrichment plants;
• Generating 0.97 million tons of high-level nuclear waste containing enough plutonium for hundreds of thousands of nuclear weapons;
• Outfitting fourteen Yucca mountains to store the waste;
• Adding fifty new reprocessing plants to extract plutonium if the Generation IV reactors were to proceed;
• Investing $1 to $2 trillion.
The effect would then be to cut the global average temperature rise by just 0.2%; far from helping to actually reduce global warming.
Read this unbiased assessment:
http://www.ucsusa.org/assets/documents/nuclear_power/nuclear-power-in-a-warming-world.pdf
see this map:
Union of Concerned Scientists map of U.S. nuclear facilities: http://www.ucsusa.org/nuclear_power/reactor-map/embedded-flash-map.html
and read this report:
Craig A. Severance, 2008, Business Risks and Costs of New Nuclear Power and then for a little background: Ernest J. Sternglass, 1981, SECRET FALLOUT, LOW-LEVEL RADIATION FROM HIROSHIMA TO THREE MILE ISLAND.
Then also: Helen Caldicot, PHD (2006, Nuclear Power is Not the Answer)
All energy technologies entail some risk. The Altamont wind farm in California has actually killed a member of the public. Radiation release from burning fossil fuels is unaccounted for, and the fossil industry dumps its wastes into the atmosphere. At least nuclear energy has a serial number level accountability for its nuclear waste, and keeps an eye on it.
Reply | Report Abuse | Link to this"Nuclear power is neither affordable, safe or practical in solving our energy problems"
Reply | Report Abuse | Link to thisConsidering it is supplying 20% of U.S. electrical needs, this statement fails on face value.
The Russian Chernobyl reactor, which ultimately took the lives of 57 people, had a positive coefficient of reactivity because it used graphite as moderator, meaning that increased temperatures can increase neutron multiplication (unless counteracted). Such a design for nuclear power plants is now prohibited in all countries, that is they must have a negative reactivity coefficient. Furthermore the Chernobyl reactor had no containment vessel, as is the law in all Western countries and now worldwide. The assertion that thousands more people could still die from radioactive fallout around Chernobyl is nonsense. Of the 60,000 inhabitants of Pripyat who had been exposed to fallout, at least 9,000 will die at an advanced age of cancer because worldwide at least 15% of all people die from cancer. To ascribe those 9,000 deaths to Chernobyl's fallout is equally ridiculous as claiming that such a death toll is due to drinking coffee because 15% of all people drink coffee. The TMI accident had zero fatalities and no one will ever suffer, contrary to assertions and phantasies by anti-nuclear armchair philosophers. The boric acid corrosion problem has been recognized for more than a adecade. Modern reaction vessels and steam ducts now use improved materials and are designed and tested to prevent such failures. Security precautions and containment measures for today's nuclear power plants reckon with the possibility that terrorists might crash a large airplane or bomb on a reactor. Even if aerial obstructions or underground construction can not prevent penetration of the large dome-shaped containment vessel, the reactor core vessel is designed to stay mostly intact in the event of a core meltdown like at TMI. TMI proved a core meltdown does not cause any earth-penetration as phantasized in "The China Syndrome". Some believe that radioactive materials with long lifetimes are more dangerous than short-lived ones. Just the opposite is true: the longer the decay lifetime, the less the radiation emitted per gram of radio-isotope. Most elements that make up our bodies (hydrogen, carbon, oxygen, nitrogen, etc) have infinitely long decay lifetimes. All humans are "hot" because everyone has radioactive potassium-40 (K-40; 0.012% abundance) in his body, which continuously emits beta particles with a half-life of one billion years! Man successfully evolved in this environment, and there are even indications that low levels of radiation benefit health (called hormesis).
Reply | Report Abuse | Link to thisJeff W. Eerkens
Nuclear Science & Eng'ng Institute
U of Missouri - Columbia
Statistically, there will be some average rate of incidents at each nuclear reactor. If the number of reactors increases, then the likelihood of incidents, overall, goes up. Some of these incidents will be considered serious. Safety regimes will be different in different countries (and may even be different in different regions of some countries). If nuclear power provides an increasing proportion of electricity around the globe, the chances of a serious incident will be greater, perhaps much greater, than it is now. Regardless of how safe someone thinks some design of reactor is, in some given country, overall, the risk increases as reactor numbers increase around the globe. I hope nuclear advocates truly understand this.
Reply | Report Abuse | Link to thisThank you Mr. Eerkens for providing factual and qualified information. While I respect the author on his enthusiasm, I suggest that his articles should be reviewed and commented on by experienced nuclear power industry individuals. Even though there are inconsistencies in this article, as pointed out in the blog comments, the author is writing this article in accordance with his level of experience and Yale education. I support differing views on controversial issues, however, I respect views with experienced factual understandings, not just an overnight educated subject expert. I find it incomprehensible that Scientific American Magazine actually published this tabloid style article. "Balancing the Risks and Rewards of a Power Source" as the tiltle states, is not discussed and balanced with risks proportion to the rewards.
Reply | Report Abuse | Link to thisHas the author any understanding of PSA's that calculate the plant risk? Has the author described any rewards of nuclear power as as source? The economic rewards are, that currently a nuclear plant produces power around $13/MWh to $20/MWh, a coal plant around $45 to $55/MWh, and a gas fired combined cycle plant around $85/MWh or more based on the actual cost of natural gas. And these are the least cost producers. I support renewables, however, wind and solar are much more expensive in production costs. The most politically stated reward of nuclear power, environmentally speaking, is the fact that a nuclear plant produces virtually zero GHG emmissions, to warm this planet. And that we can generate energy independently of foreign fuel sources. The author could have present the risk and rewards with more in depth and educated facts and objectives, that would describe the actual risk to reward, and compare them in light of the current U.S. and world energy needs.
Sofistek, I think your statement is correct but my point would be that dangers of a nuclear accident are way over blown. I am not saying there will not be a major nuclear accident, there will be, but the consequences to the public will be very small if any. We have already seen a worst case scenario nuclear accident at Chernobyl which caused 56 deaths. How many people die every year from air pollution, coal mining accidents or will die from global warming.
Reply | Report Abuse | Link to thisSofistek, I think your statement is correct but my point would be that dangers of a nuclear accident are way over blown. I am not saying there will not be a major nuclear accident, there will be, but the consequences to the public will be very small if any. We have already seen a worst case scenario nuclear accident at Chernobyl which caused 56 deaths. How many people die every year from air pollution, coal mining accidents or will die from global warming.
Reply | Report Abuse | Link to thisSir, I must disagree with your statistical assessment that borderlines on a qualitative and subjective assessment. You say that by simply increasing the number of nuclear reactors in the world you increase the likelihood of core damage frequency. This is simply incorrect. The design of the reactor being constructed dictates the core damage frequency, as is well known in Probabilistic Risk Assessment (PRA) methodologies, as accepted by the Nuclear Regulatory Commission. For the new Gen-IV and Gen-III designs being proposed, that are either inherently safe or have passive safety systems, respectively, the CDF drops significantly by orders of magnitude. This lends to the conclusing that even if nuclear capacity were double from today's reactors, the overall CDF/reactor would actually decrease because the nuclear reactors are less likely to fail.
Reply | Report Abuse | Link to thisNO nuclear power plant design is found to be safe or affordable.. just read the literature: Uassessment:
Reply | Report Abuse | Link to thishttp://www.ucsusa.org/assets/documents/nuclear_power/nuclear-power-in-a-warming-world.pdf
map of nuclear power plants with history of problems:
Union of Concerned Scientists map of U.S. nuclear facilities: http://www.ucsusa.org/nuclear_power/reactor-map/embedded-flash-map.html
the most authoritative industry report:
Craig A. Severance, 2008, Business Risks and Costs of New Nuclear Power
History of radiation risks: Ernest J. Sternglass, 1981, SECRET FALLOUT, LOW-LEVEL RADIATION FROM HIROSHIMA TO THREE MILE ISLAND.
http://www.citizen.org/cmep/energy_enviro_nuclear/nuclear_power_plants/http://www.citizen.org/documents/FatalFlawsSummary.pdf
.
So, no meltdowns yet since - what? - Three Mile Island - means they have a good safety record??). Count me out of that unscientific 'logic.'
The Union of Conerned Scientists analyzed this and found it to be quite wanting (PRA). The NRC is hardly to be trusted, given it's poor safety record thus far.
Reply | Report Abuse | Link to thisSo, Tchernobyl caused from 56 to 4000 deaths? How can we assess nuclear risks when the Ukranian epidemiologists studying the effects of irradiation on the local environment have been imprisonned?
Reply | Report Abuse | Link to thisIn France, nuclear power stations use electro-mechanical technology for their control systems, but young nuclear enginneers only learn electronic systems technology. Reactors are getting to the end of their lifespells...
Companies that made spare-parts have gone out of business.
Steelyards that made reactors have all delocalised.
As reactors based on new technology proliferate, the education levels of control technicians decreases.
As the Nuclear industry has obvious military implications, the openess of access to information is biased.
If Nuclear is a viable proposition in terms of CO2 reductions, the public debate must become fully open and scientific.
I refer to the 1979 TMI radiation release being only about an average of 8 millirems per person within 10 miles, and on that basis the ANS felt that it could reassure the public by comparing the dosage to that of just a chest x-ray. What the public does not know will hurt them. The equivalents are fine but not the results and one is not the other. Radiation from an x-ray passes through the body leaving behind some damage to DNA reproduction that is a minor concern for cancer. But an x-ray does not leave radioactive particles within the human body and a dose from a reactor leak does. The leak is of radioactive gas which, when inhaled, draws the particles into the lungs, lodging there, the radiation repeatedly discharges into the surrounding cells so that the probability of DNA damage is far higher than that of and x-ray where an energy beam blasts through and does not return. I am splitting hairs here, but maybe someone needs to. Of course, cancer is a common malfunction in living cells and no-one can prove that a patient's cancer definitely originated from some specific molecular point. You cannot blame anything or anyone if you cannot clearly identify or name them. Science is statistical rather than exact. Nevertheless, it is not the dose here but the method that is the most deadly. How about other, although faulty, comparisons? A lead bullet on your palm to a lead bullet in your lung; or asbestos powder on your skin to asbestos powder in your lungs. The dose can be the same, but is the effect? In dumbing-down information for public consumption you can misinform, or worse, mislead the public, for what the public doesn't realise, the public cannot complain about; and that should suit any self-preserving authority just fine. I would like to name the ANS.
Reply | Report Abuse | Link to thisIf you increase the number of plants but they are inherently better and safer (due to the evolving technologies employed) then the overall risk of failure should statistically remain unchanged... One set of variable increases the risk, another set reduces it ... the result could be theoretically the same!
Reply | Report Abuse | Link to thisAnd when you consider that to the realistic alternatives of producing electricity the way we do now - electricity is and will be the ultimate real/pure source of end-user "usable" energy - then those risks become really a joke!!! Harnessing atomic energy is as of right now the best real thing we got! Too bad the world economy is in shambles, cuz' the plans are no doubt postponed due to that now, but we already made efforts to recreate the Sun model in our own backyards (an international effort to design and test a real fusion reactor). If you're in the know and not an ignorant, then you surely know about that, so I won't elaborate here! But that again, is way out there... how about the immediate now?! Compared to solar, wind and any other renewable sources (which are great resources to use, don't get me wrong) an atomic reactor is now, more than ever, that real promise of real energy in the size of an apple enough to power the Big Apple for a year! What else in this world gets anywhere close to that?!... Go figure! thanks!
Honestly this stuff only matter if we are working with the old style reactors instead of a design like a pebble bed reactor. There is no way for a design like that to go super critical or release the material into the air.
Reply | Report Abuse | Link to thisDon't have a problem with nuclear if coal is the alternative. I just want a Generation 3 or four reactor design.