The surprising accident in Fukushima turns the spotlight on a new generation of nuclear reactors under development in the US. Are they sufficiently safe?
On the other side of the planet, far from the disaster-stricken Fukushima Daiichi nuclear power plant in Japan, in the heart of the pine forests of the state of Georgia in the USA, hundreds of workers are working these days to prepare the area for an American nuclear renaissance, which will soon materialize, so they still think
Bulldozers rumble across low, flat areas of fresh, well-compacted fill soil covering miles of recently buried piping and drainage systems. If the work progresses as planned, two new nuclear reactors will emerge from the surface of the earth already during 2012 - the first reactors whose construction has been approved in the USA in more than 25 years.
This will be the opening shot for resuming the spread of nuclear energy in the US, which was effectively frozen after the partial melting accident of the reactor core that occurred in 1979 in one of the units at the nuclear power plant on Three Mile Island in Pennsylvania. In the years that have passed since then, under the threat of global warming, nuclear power has transformed from an environmental threat to a potential source of carbon-free energy. Both former US President George W. Bush and President Barack Obama supported this technology, hoping to promote the construction of new nuclear power plants. The United States Nuclear Regulatory Commission (NCR) is currently examining proposals to build 20 new reactors, in addition to the two being built in Georgia, which will be added to the 104 reactors built in the US decades ago.
Credit: Don Foley
More than half of these new reactors, including the two units at the Vogtel nuclear power plant in Waynesboro, Georgia, are designed to be AP1000 models, the first in a new generation of reactors that incorporate "passive" safety features, and are designed to prevent disasters such as the one that happened in Japan. In the event of an accident, an emergency system will be activated in the reactor that utilizes natural forces such as gravity and condensation to help prevent dangerous overheating of the nuclear fuel in it. Such features were lacking at the Fukushima Daiichi nuclear power plant.
A few months ago, it seemed that the NRC was going to grant the final approval for the construction of the two AP1000 model units planned in Georgia this year. However, the Fukushima disaster last March, in which the intense 9.0 magnitude earthquake and the massive tsunami that followed left the hot cores of four reactors without coolant, once again raised the possibility of a nuclear disaster to the top of the public agenda. In the weeks after the disaster, public opinion polls showed a drop in the percentage of Americans who support the construction of new reactors, from 49% before the accident to 41% after it, a drop that reflects distrust in the technology, despite promises that the risks inherent in it are minimal and protections for the reactors are strong. The horrors of Fukushima illustrated in a very real way the limitations of risk assessments.
Despite the early preparation, nuclear energy sources will inevitably be vulnerable to black swan events - events whose probability of occurrence is very low, but which have far-reaching consequences. Rare events, especially events that have never happened, are difficult to predict in advance, expensive to prepare for and easy to ignore for statistical reasons. But the mere fact that a certain event is expected to occur only once in 10,000 years does not mean that such an event will not occur tomorrow. During 40 years, which is the typical lifespan of a power plant, assumptions can also change, as happened on September 11, 2001, in August 2005, when Hurricane Katrina hit, and in March 2011, after the Fukushima disaster.
The list of potential disasters inherent in black swan events is terrifyingly diverse. Nuclear reactors and the pools used to store their spent nuclear fuel could serve as targets for terrorists piloting hijacked aircraft. Nuclear reactors located on the banks of rivers are exposed to the danger of the collapse of dams some distance upstream from them which could cause floods on the scale of a biblical flood. There is a huge danger from mines located near geological replicas (fragments) prone to earthquakes or mines located along coastlines exposed to hurricane surges or tsunami waves. Each of these disasters could create the ultimate danger scenario such as those that occurred on Three Mile Island and Fukushima - a catastrophic failure of the cooling system, overheating and melting of the radioactive fuel rods, and a fatal release of radioactive material. (The reactor core in Chernobyl was ignited following the explosions that occurred there.)
Preparing for such scenarios is not a simple task at all, even without the need to maintain the budgetary framework. Power generation companies are trying to reduce the very high upfront expenses involved in building reactors. Even if all the licensing and construction processes go smoothly, the cost of building a nuclear power plant is almost twice as high per megawatt as the cost of building a coal-fired power plant, and almost five times that of a natural gas-based power plant. These differences can be offset by the lower operating costs - coal is roughly four times more expensive than nuclear fuel, while the cost of gas is ten times higher - but such an offset will only be reflected if the nuclear power plant operates at full capacity for many years. More than once in the 70s and 80s, these operating profits were thwarted due to shutdowns of the power plants for maintenance purposes and handling safety problems. In order to make nuclear power competitive, the service providers are trying to cut the construction costs of the power plants and reduce the scope of their shutdowns by installing simpler and more reliable systems, without reducing their safety margins.
It goes without saying that it is impossible to build a nuclear reactor that is immune to every potential disaster, even if the engineers wrap the reactor in enormous shield walls, bury it deep in the ground in a watertight vault, and hire legions of psychics with supernatural powers to predict the future. There is no doubt that in designing the AP1000 model, the engineers tried to choose the best way considering the multiple constraints involved in the physical and financial aspects of the construction of the reactor and the required preparation in case of a disaster. The planned model is necessarily the product of a compromise. The most troubling question following the Fukushima disaster is: Are nuclear reactors sufficiently safe?
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About the author
Adam Piore is a freelance reporter in New York, and in the past, a reporter for Newsweek. Among other things, he covers patents at Scientific American.
And more on the subject
Nuclear Power in a Warming World. Lisbeth Gronlund et al. Union of Concerned Scientists, December 2007. www.ucsusa.org
The Future of Nuclear Power: An Interdisciplinary MIT Study. Massachusetts Institute of Technology, 2009. http://web.mit.edu/nuclearpower
The website of the Nuclear Energy Institute in the USA: www.nei.org
The website of the US Nuclear Regulatory Commission: www.nrc.gov
World Nuclear Union website: www.world-nuclear.org
9 תגובות
Today there are new technologies in the field of nuclear reactors that have advantages that should be mentioned.
THORIUM reactors that do not produce plutonium and radioactive fission products that are active for such a long time and in addition THORIUM is much cheaper than enriched uranium.
http://en.wikipedia.org/wiki/Thorium_fuel_cycle#Disadvantages_as_nuclear_fuel
Another technology is a reactor that uses nuclear waste from normal reactors.
The view should be towards the best and not towards the mediocre...
Nuclear energy produces radioactive waste that decays only after 100 thousand years...
This is not sustainable.
The perspective should be different. Not whether there can be malfunctions in a nuclear reactor, but whether there are more damages from the electricity generation system from normal mineral fuels (oil, coal, methane), or from the nuclear production system.
The normal electricity generation system includes: coal mines, oil drilling, gas drilling, transport ships, the power plants themselves.
It is necessary to investigate whether the damage to human life to the economy of the accidents in all of the above + the ecological damage that can be measured (oil spills, etc., not including global warming), in relation to their electricity generation per watt-hour, are greater than the damage caused as a result of the nuclear power generation system.
Without knowing the exact data, I often hear about accidents and even deaths in the normal electricity generation system, and only once in many years about a malfunction in a nuclear reactor.
You answered everything is great and really original ideas but like anything that is built and produced to make money and/or improve the standard of living there is a risk versus a cost that a critic of some of your ideas will look as if the price of the reactor will be much higher than its economic value
The countries of the world should very well switch to a reactor that operates on ores as the reactor from our quarries has been operating for years and provides energy to many people
Disasters can be avoided in a very simple and cheap way. I call it protection circles:
First circuit: the reactor is built inside a steel sphere instead of building the reactor inside a sphere of unenriched uranium if the core is molten it will merge into the structure of the reactor and the level of enrichment will drop dramatically and thus the heat and radiation will decrease
Second circle:
You can build a huge pit under the reactor, the pit should be below sea level
In case of a serious failure, the reactor can be dropped into the pit and flooded.
And in the event of an extremely severe earthquake above 9, the reactor will fall by itself into the pit
The pit can be covered with plastic foam or oil that will prevent evaporation.
If you build the reactor out of real preparation for a disaster that will happen someday and with some protective envelopes and no radiation will be emitted even in disasters of total destruction.
United States Nuclear Regulatory Commission = NRC and not NCR
The real question is what is happening with the reactor in Dimona, which is already over 50 years old