If you're near Berkeley, take this class or take a look at the slides. I used to be a TA for it. http://socrates.berkeley.edu/~kammen/er100/
ER 100 ENERGY AND SOCIETY - Undergraduate Course (4) (27703) Kammen
Overview: In this course, you will develop an understanding _ and a real working knowledge _ of our energy technologies, policies, and options. This will include analysis of the different opportunities and impacts of energy systems that exist within and between groups defined by national, regional, household, ethnic, gender distinctions. Analysis of the range of current and future energy choices will be stressed, as well as the role of energy in determining local environmental conditions, and the global climate.
Get a Clue: Building and running a nuclear plant requires LESS energy than it takes to build and maintain a solar or wind farm of the same capacity. The energy payback time for building a nuclear plant is less than a month. The energy payback time for building a wind farm is 2 months to 2 years and 2 to 7 years for solar.
Also, what is not frequently mentioned is the difference between baseload and peaking power plants. Nuclear, coal, hydro are baseload power stations that provide constant energy throughout the day. Natural gas and renewables are peaking plants that cover periods of peak demand - though renewables are less reliable even here. Therefore, renewables are not an attractive option for a large fraction of our energy use since they cannot compete for the baseload market.
are hunting a deer. The engineer takes the first shot and misses the deer by one meter to the left. The physicist takes another shot and misses the deer by one meter to the right. The statistician says, "Got 'em!"
Actually, the trend in nuclear education is reversing. While the number of programs have been cut over the last decade, enrollments have been increasing over the last few years and a new department was started recently in the U.S.
Being a recent graduate of a highly ranked nuclear engineering program, I have no concerns about job security in the nuclear field.
There are plenty of jobs at power reactors given that a large fraction of the industry is approaching retirement and given the plans for extended plant lifetimes. For example, the average age at one of the NPPs in California is somewhere near 50. At my old nuclear-related government job, the ratio of those over 50 to under 30 was something like 6:1. And all you see at conferences is gray haired men. During one plenary session, they asked all those under 30 to stand up - about a dozen people stood up in a room with hundreds of people. And if you can't find a job at a power reactor, there are plenty of stable government jobs - especially at the national labs, and in homeland security related organizations.
Though I am not concerned about finding a job somewhere, I am concerned about finding an interesting, innovative job. Working at a reactor is fairly mundane and usually requires you to move out to the middle of bum-f*ck nowhere. Shuffling papers at a government desk job is also kinda lame until you get really high up and are making policy decisions. The really interesting nuclear projects require a friendly administration willing to cough up the millions/billions of dollars to actually build something instead of futzing around with computer codes and flinging reports around all day. As a result, I have lost almost all interest in working in the power industry.
What will continue to provide interesting technical and political challenges in the nuclear field is non-proliferation and safeguards. Even in nuclear power disappears, we will have to continue verifying that no one "cheats."
The Russians should build an Encapsulated Nuclear Heat Source instead http://coe.berkeley.edu/labnotes/1002/reactor.html
But to address, the PBMR issues...
A graphite fire is not a significant risk in a PBMR since helium is used as a coolant. Ever try to burn stuff in helium? Furthermore, air/water ingress scenarios will be very low probability events. Yes, you could dream up such scenarios, but then you have also have to work yourself into a panic about large meteors striking the earth.
There is some debate on the flammability of nuclear-grade graphite used in PBMR fuel. Similar grades of graphite are used on space shuttle tiles and I bet the astronauts would be really pissed if those things burned - they might fall off, but that's a problem with the mechanical connection between the tile and the shuttle.
The PBMR does produce more waste BY VOLUME given the graphite matrix that surrounds the fuel. However, the PBMR is designed for higher burnup fuel so the amount of long-lived radioactive "waste" will be reduced. Furthermore, PBMR fuel may be easier to dispose of given the decomposition resistant graphite layers and the lower density of decay heat (you have to space out spent fuel in a repository to manage the heat loads anyways).
Why would you have to dispose of the helium coolant? It doesn't become radioactive.
If someone has weapons-grade U or Pu and sophisticated enough to build a weapon, what makes us believe that acquiring D or T would be any more difficult? You pointed out yourself that D is easy to acquire. Yes, these materials should be protected to some degree (mostly to prevent exposure to the public), but if fusion works, we can derive enormous benefits while still assuring ourselves that nuclear weapons will still be difficult to acquire.
A dirty bomb is easy to produce given the vast quantities of radioactive materials that can be fairly easily acquired, mostly from weakly defended (if at all) "non-nuclear" facilities. Walking into hospitals, stealing density gauges from construction sites, amassing old fire alarms, swiping stuff from a university,.... You wouln't even need too much radiation to freak the public.
Building a Pu production reactor using a fusion neutron source is unattractive since everyone does it easily using fission reactors. Hmmm...build a multi-billion dollar fusion reactor or build a multi-million dollar fission reactor?
What's the big deal if you have D, T and Li at a fusion power plant? You can't make a fusion bomb out of these materials by themselves. Fusion reactions require high energies to set off. As a result, reactors require magnetic or inertial confinement schemes. An H-bomb still needs a fission bomb (requiring highly enriched Uranium or specific isotopes of Plutonium) to cause fusion. The real concern then is preventing the spread of fissile material in the first place.
It's not longevity that's reduced. Without nuclear power, deep space missions are impossible. RTGs are designed to mitigate the potential impacts due to accidents and/or reentry.
The water flow calculated from the Chlorine data has been accounted for in the models - models that demonstrate with high confidence that the repository will perform for 10K years at well below (as in orders of magnitude below) the unnecessarily strict EPA dose limits. And given the conservatism in the analysis, the repository will likely perform well beyond the 10K year design.
As for the site selection criteria, DOE imposed these unrealistic criteria upon itself. NRC and many experts have maintained from the beginning that a repository would require multiple barriers, both natural and engineered, to be successful. No current respository design relies exclusively on natural barriers and DOE's adoption of these design goals only indicates their alignment with prevailing scientific opinion.
The removal of decay heat is a significant issue and has been addressed in the design of the facility.
Cask corrosion, premature cask failure, and many, many other failure modes have been included in the analytical models (see first paragraph).
1. True 2. I wouldn't call a mere trickle "running" or call the engineered tunnels "caverns" 3. True
Probabilistic analysis includes ALL OF THESE FACTORS and have demonstrated with high confidence that the repository will perform for 10K years at well below (as in orders of magnitude below) the unnecessarily stricts EPA dose limits. And given the conservatism in the analysis, the repository will likely perform well beyond the 10K year design. Perhaps there is a site that is marginally better someplace in the world, but that doesn't change the suitability of Yucca Mountain as a repository for spent nuclear fuel.
How many of you actually have a college degree in Nuclear Engineering? I know I do. Just wondering - some of the things I've read here are just plain wrong.
I'm not entirely sure what you are trying to say this time around, but your previous argument seemed to say that there wasn't enough real world experience to validate fault analysis. The thousands of reactor-years of operating experience is indeed relevant as this experience has provided valuable data on the operation of nuclear power plants and has shown that nuclear power is "safe".
Furthermore, in the U.S., nuclear power is perhaps one of the most open industries around. The Nuclear Regulatory Commission posts all events on their website for everyone to see. However, I am not denying that there were or are problems.
Many claim that the nuclear industry has uniquely enjoyed large government subsidies. However, it is also true that renewables have enjoyed similar (some claim greater) levels of funding - and yet they remain stubbornly uncompetitive and produce very little energy. Meanwhile, nuclear produces 20% of the electricity in the U.S. In terms of returns on investment, the billions of dollars invested in renewables could have been used more effectively by replacing coal plants with cleaner technologies like gas or nuclear. Of course, I am not advocating this - we should be investing in renewables and conservation.
The physical feedback effects that can shut down a reactor are not active systems - they are passive systems that are built-in, requiring no intervention. Active systems would be things like emergency core cooling systems that rely on pumps. Pebble Bed and other Generation IV designs are passively safe, meaning there is little or no need for active systems to shutdown the reactor.
Chernobyl was initially a steam explosion followed by a hydrogen explosion. This accident was caused by the reactor's positive void coefficient, a measure of physical feedback. This resulted in an instability at low power which resulted in voids of steam in the coolant. These voids created an increase in power which then created more voids and so on. Western reactors all have a negative void coefficient, making this type of accident impossible. However, one of the problems is the removal of decay heat in order prevent fuel melting. This is traditionally prevented by active cooling systems. In the case of Pebble Bed, simple conduction takes care of core cooling and the fuel "pebbles" are very resistant to thermal stress. Pebble Bed also uses Helium as a coolant, resulting in higher efficiencies. Therefore, meltdowns, runaway reactions, steam explosions, are impossible.
Personally, I don't see safety as an issue with nuclear power, especially in the case of new reactor designs. However, waste disposal is a political nighmare. But, I believe solutions such as reprocessing and transmutation can minimize the problem of waste disposal with little risk. I also believe that there are credible solutions to geological storage. Nature has shown such storage is possible via the Oklo natural reactor. Unfortunately, credibiliy in this area is lacking since this long term waste storage has yet to be demonstrated. This is why I support plans for retrievable storage, not permanent disposal, in case something should happen and/or better means of dispoal are found.
Solar power is indeed very expensive - perhaps best indicated by how little it is used. It's also not perfectly clean given the toxic substances used the manufacturing process as well as the sheer scale of the required installations. I'm not sure how fear can be included in calculating energy costs. However, you can include external effects by estimating costs due to environmental damage, impact on human health, etc. This is indeed what some have done.
Herbert Inhaber did some lifecycle analysis a while ago that demonstrated that there are significant external costs associated with renewables and that nuclear has one of the lowest impacts. (I'm not sure how well accepted his conclusions were and I'm sure there's plenty of criticism.) Also, the European ExternE project (which seems to have never submitted a final report) also shows that the external costs of renewable generation exist and are comparable, if not greater, than the external costs of nuclear energy. Of course, the actual numbers are not worth very much. Nevertheless, both of these studies demonstrate (at least qualitatively) that renewables do have a substantial impact and that nuclear may not have as much of an impact as some may believe.
As for the German radioactive "leak," all I was able to find was that the containers were contaminated and were more radioactive then they should be - not leaking radioactive materials into the environment. I'd appreciate it if you had more detailed info. - a technical report would be nice. News articles have this irritating tendency to report things inaccurately.
As for wind power, technical limitations, i.e. intermittency, wind location, dilute energy, land use, etc. are the major disadvantages that I see. For example, the Altamont windmill farm in California is one of the largest wind farms in the world. Nameplate capacity is something like 500MW, but factoring in a typical 20% capacity factor, the real capacity is only 100MW. Virtually every time I drive by the farm, very few of the windmills are turning - a serious reliability problem. I tend to disregard people's complaints about noise and visual pollution. However, there are industrial wastes associated with windmill production and this problem is exacerbated by the simple fact that you need A LOT of windmills to produce significant quantities of energy.
Certainly, we can do much more in terms of renewable generation - it is A solution, but not THE solution.
1. Potential catastrophe is not a means to evaluate risk - the very important factor of probability is ignored. Risks for newer designs ARE lower - not might be lower.
2. You don't necessiarily have to use Sodium in a fast breeder reactor. Gas Cooled Fast Reactors, using helium could work. Molten Salt (not Na) could also work. Light water breeder reactors can be fueled with Thorium, which is quite abundant.
I'm also curious by what you mean by "peculiar economic situation of those countries."
It differs from something like a computer system where you can give a uptime estimates on 99.999% for instance. You can test these things to
failure, and form statistics based on actual usage. Clearly you can not do this with a nuclear power plant.
Nuclear power has thousands of reactor-years of experience that provides such real world data. And so far, the safety of nuclear power has been unparalleled.
However, I agree with the your assessment that figures from risk analysis are a bit suspect - uncertainties are a given whenever such analysis is done.
Fortunately, the industry has learned from it's mistakes as numerous safety improvements have been made to existing reactors. Furthermore, advanced designs, especially Generation IV reactors, promise to be inherently safe. For example, the Pebble Bed reactor that has been generating so much interest is essentially incapable of melting down due to a variety of physical feedback effects that are "hard-wired" in the physics of the reactor.
Such a reactor, a high temperature gas reactor, would also be much more thermodynamically efficient which directly translates to less waste per kWh.
I have not heard about this incident. However, spent fuel from power production is safely awaiting storage on reactor sites in either fuel pools or dry cask storage. In the U.S., virtually all nuclear fuel from power production has been succesfully sequestered from the environment. What remains to be seen is if this fuel can be successfully sequestered in a geological repository. However, nature provides evidence that this indeed possible. A natural reactor, Oklo, was in operation in Africa many thousands of years ago. French geologists discovered the deposit of uranium only to find that the composition of the deposit looked just like spent reactor fuel. They also discovered that over thousands of years, despite an abundant source of ground water and no engineered containment, the radioactive elements had transported only several feet. However, this says nothing about the situation in Denver. However, the stuff in Denver is most likely not spent fuel. In fact, nuclear fuel is very strictly regulated.
Nuclear is not the most expensive source of energy. Solar is. Secondly, I don't know where you got the impression that the trains were leaking radioactive waste. The German waste is immobilized in glass and is very resistant to decomposition. Also, "natural" energy is not risk-free - nothing is risk free. It's ridiculous to claim that enormous wind and solar energy systems are perfectly safe. In fact, lifecycle analysis has shown that renewables have a significant impact on human health. Some studies have even shown that nuclear has one of the lowest impacts on the environment and human health! Furthermore, we have studies claiming that several thousand people die every year from air pollution. We could light off a few nuclear plants a year and still not have as great of an impact. Yet, fossil fuels do not engender the same amount of public outcry. I fully support increasing our renewable generation capacity to significant levels. Only then will people realize the true costs of these systems. Soon afterwards, people will realize that their options are limited and they will start rationally evaluating all sources of energy.
As noted in another reply, you cannot have a NUCLEAR explosion in a nuclear reactor. Physically, it is impossible. Furthermore, tests have shown that a U.S. style containment structure could have contained the Chernobyl explosion. Regardless, such an explosion in a U.S. reactor is near impossible due to physical feedback effects that shutdown the reactor in the case of an accident. In the case of Chernobyl, the reactor had a void coefficient that made the reactor unstable. Steam bubbles in the coolant led to increased reactor power which then led to more steam and then more power and so on. Such a reactor would not be licensed in the U.S. New reactor designs, such as the Pebble Bed Modular Reactor, promise to be inherently safe as they are designed such that they would always shut themselves off and not meltdown in the case of an accident. This is not science fiction.
It is true that the once-through fuel cycle employed in the U.S. would only provide ~100 years of energy. However, closing the fuel cycle by recycling used fuel would increase our fuel supply. Furthermore, breeder technology could provide enough energy for thousands of years, a "somewhat" larger extension of supply.
Transmutation, either accelerator or reactor based, of long-lived elements into shorter-lived elements is currently under research and is showing much promise. We can also "burn" elements such as Plutonium in reactors.
Nuclear power is much much better than coal plants in terms of full lifecycle emissions. Furthermore, lifecycle analysis has shown that solar, wind, and even hydro produce significant emissions. For example, it takes a solar panel 2-5 years just to recover the energy used in producing the panel itself.
The amount of radiation released from coal-fired plants is indeed measurable. If I remember correctly, you receive 0.03 millirems per year on average if you live close to a coal plant. A typical nuclear power plant would expose someone to about 0.009 millirems per year. Both of these levels are far lower than anything experienced at Chernobyl. The levels of exposure for Chernobyl "liquidators" are hardly the low levels that are claimed by the report.
Most people seem to forget that renewable energy sources like solar, wind, etc. do produce waste. Solar panels are semiconductors - heavy metals, acids, etc. are waste products. There are also waste products associated with making windmills. The problem is exacerbated by the simple fact that you need huge numbers of solar panels or windmills to produce any meaningful amount of energy. Therfore, the waste problem is magnified by the enormous scale of these installations. In the case of nuclear, the energy is dense both in terms of fuel (and waste) volumes and land use. For example, spent fuel from 40 years of nuclear power generation (representing some ridiculous number of kilowatt-hours) would fill a football field to a depth of 5 yards. In comparison to the wastes generated from industrial processes that we dump on a daily basis or that amount of pollution spewed from fossil fuel combustion, the amount of nuclear waste is miniscule. Therefore, it is much more feasible to sequester nuclear waste from the environment behind multiple engineered and natural barriers. Also, technology exists to recycle spent fuel into new fuel, reducing the quantity that needs to be stored. Trasmutation, accelerator or reactor based, will also be able to transmute long-lived elements into shorter ones.
Slashdot Mirror
If you're near Berkeley, take this class or take a look at the slides. I used to be a TA for it. http://socrates.berkeley.edu/~kammen/er100/
ER 100 ENERGY AND SOCIETY - Undergraduate Course (4) (27703)
Kammen
Overview: In this course, you will develop an understanding _ and a real working knowledge _ of our energy technologies, policies, and options. This will include analysis of the different opportunities and impacts of energy systems that exist within and between groups defined by national, regional, household, ethnic, gender distinctions. Analysis of the range of current and future energy choices will be stressed, as well as the role of energy in determining local environmental conditions, and the global climate.
Get a Clue: Building and running a nuclear plant requires LESS energy than it takes to build and maintain a solar or wind farm of the same capacity. The energy payback time for building a nuclear plant is less than a month. The energy payback time for building a wind farm is 2 months to 2 years and 2 to 7 years for solar.
Also, what is not frequently mentioned is the difference between baseload and peaking power plants. Nuclear, coal, hydro are baseload power stations that provide constant energy throughout the day. Natural gas and renewables are peaking plants that cover periods of peak demand - though renewables are less reliable even here. Therefore, renewables are not an attractive option for a large fraction of our energy use since they cannot compete for the baseload market.
are hunting a deer. The engineer takes the first shot and misses the deer by one meter to the left. The physicist takes another shot and misses the deer by one meter to the right. The statistician says, "Got 'em!"
Actually, the trend in nuclear education is reversing. While the number of programs have been cut over the last decade, enrollments have been increasing over the last few years and a new department was started recently in the U.S.
Being a recent graduate of a highly ranked nuclear engineering program, I have no concerns about job security in the nuclear field.
There are plenty of jobs at power reactors given that a large fraction of the industry is approaching retirement and given the plans for extended plant lifetimes. For example, the average age at one of the NPPs in California is somewhere near 50. At my old nuclear-related government job, the ratio of those over 50 to under 30 was something like 6:1. And all you see at conferences is gray haired men. During one plenary session, they asked all those under 30 to stand up - about a dozen people stood up in a room with hundreds of people. And if you can't find a job at a power reactor, there are plenty of stable government jobs - especially at the national labs, and in homeland security related organizations.
Though I am not concerned about finding a job somewhere, I am concerned about finding an interesting, innovative job. Working at a reactor is fairly mundane and usually requires you to move out to the middle of bum-f*ck nowhere. Shuffling papers at a government desk job is also kinda lame until you get really high up and are making policy decisions. The really interesting nuclear projects require a friendly administration willing to cough up the millions/billions of dollars to actually build something instead of futzing around with computer codes and flinging reports around all day. As a result, I have lost almost all interest in working in the power industry.
What will continue to provide interesting technical and political challenges in the nuclear field is non-proliferation and safeguards. Even in nuclear power disappears, we will have to continue verifying that no one "cheats."
Too bad your silly Canadian reactor has positive reactivity coefficients.
The Russians should build an Encapsulated Nuclear Heat Source instead http://coe.berkeley.edu/labnotes/1002/reactor.html
But to address, the PBMR issues...
A graphite fire is not a significant risk in a PBMR since helium is used as a coolant. Ever try to burn stuff in helium? Furthermore, air/water ingress scenarios will be very low probability events. Yes, you could dream up such scenarios, but then you have also have to work yourself into a panic about large meteors striking the earth.
There is some debate on the flammability of nuclear-grade graphite used in PBMR fuel. Similar grades of graphite are used on space shuttle tiles and I bet the astronauts would be really pissed if those things burned - they might fall off, but that's a problem with the mechanical connection between the tile and the shuttle.
The PBMR does produce more waste BY VOLUME given the graphite matrix that surrounds the fuel. However, the PBMR is designed for higher burnup fuel so the amount of long-lived radioactive "waste" will be reduced. Furthermore, PBMR fuel may be easier to dispose of given the decomposition resistant graphite layers and the lower density of decay heat (you have to space out spent fuel in a repository to manage the heat loads anyways).
Why would you have to dispose of the helium coolant? It doesn't become radioactive.
If someone has weapons-grade U or Pu and sophisticated enough to build a weapon, what makes us believe that acquiring D or T would be any more difficult? You pointed out yourself that D is easy to acquire. Yes, these materials should be protected to some degree (mostly to prevent exposure to the public), but if fusion works, we can derive enormous benefits while still assuring ourselves that nuclear weapons will still be difficult to acquire.
.... You wouln't even need too much radiation to freak the public.
A dirty bomb is easy to produce given the vast quantities of radioactive materials that can be fairly easily acquired, mostly from weakly defended (if at all) "non-nuclear" facilities. Walking into hospitals, stealing density gauges from construction sites, amassing old fire alarms, swiping stuff from a university,
Building a Pu production reactor using a fusion neutron source is unattractive since everyone does it easily using fission reactors. Hmmm...build a multi-billion dollar fusion reactor or build a multi-million dollar fission reactor?
What's the big deal if you have D, T and Li at a fusion power plant? You can't make a fusion bomb out of these materials by themselves. Fusion reactions require high energies to set off. As a result, reactors require magnetic or inertial confinement schemes. An H-bomb still needs a fission bomb (requiring highly enriched Uranium or specific isotopes of Plutonium) to cause fusion. The real concern then is preventing the spread of fissile material in the first place.
It's not longevity that's reduced. Without nuclear power, deep space missions are impossible. RTGs are designed to mitigate the potential impacts due to accidents and/or reentry.
The water flow calculated from the Chlorine data has been accounted for in the models - models that demonstrate with high confidence that the repository will perform for 10K years at well below (as in orders of magnitude below) the unnecessarily strict EPA dose limits. And given the conservatism in the analysis, the repository will likely perform well beyond the 10K year design.
As for the site selection criteria, DOE imposed these unrealistic criteria upon itself. NRC and many experts have maintained from the beginning that a repository would require multiple barriers, both natural and engineered, to be successful. No current respository design relies exclusively on natural barriers and DOE's adoption of these design goals only indicates their alignment with prevailing scientific opinion.
The removal of decay heat is a significant issue and has been addressed in the design of the facility.
Cask corrosion, premature cask failure, and many, many other failure modes have been included in the analytical models (see first paragraph).
1. True
2. I wouldn't call a mere trickle "running" or call the engineered tunnels "caverns"
3. True
Probabilistic analysis includes ALL OF THESE FACTORS and have demonstrated with high confidence that the repository will perform for 10K years at well below (as in orders of magnitude below) the unnecessarily stricts EPA dose limits. And given the conservatism in the analysis, the repository will likely perform well beyond the 10K year design. Perhaps there is a site that is marginally better someplace in the world, but that doesn't change the suitability of Yucca Mountain as a repository for spent nuclear fuel.
How many of you actually have a college degree in Nuclear Engineering? I know I do. Just wondering - some of the things I've read here are just plain wrong.
I'm not entirely sure what you are trying to say this time around, but your previous argument seemed to say that there wasn't enough real world experience to validate fault analysis. The thousands of reactor-years of operating experience is indeed relevant as this experience has provided valuable data on the operation of nuclear power plants and has shown that nuclear power is "safe".
Furthermore, in the U.S., nuclear power is perhaps one of the most open industries around. The Nuclear Regulatory Commission posts all events on their website for everyone to see. However, I am not denying that there were or are problems.
Many claim that the nuclear industry has uniquely enjoyed large government subsidies. However, it is also true that renewables have enjoyed similar (some claim greater) levels of funding - and yet they remain stubbornly uncompetitive and produce very little energy. Meanwhile, nuclear produces 20% of the electricity in the U.S. In terms of returns on investment, the billions of dollars invested in renewables could have been used more effectively by replacing coal plants with cleaner technologies like gas or nuclear. Of course, I am not advocating this - we should be investing in renewables and conservation.
The physical feedback effects that can shut down a reactor are not active systems - they are passive systems that are built-in, requiring no intervention. Active systems would be things like emergency core cooling systems that rely on pumps. Pebble Bed and other Generation IV designs are passively safe, meaning there is little or no need for active systems to shutdown the reactor.
Chernobyl was initially a steam explosion followed by a hydrogen explosion. This accident was caused by the reactor's positive void coefficient, a measure of physical feedback. This resulted in an instability at low power which resulted in voids of steam in the coolant. These voids created an increase in power which then created more voids and so on. Western reactors all have a negative void coefficient, making this type of accident impossible. However, one of the problems is the removal of decay heat in order prevent fuel melting. This is traditionally prevented by active cooling systems. In the case of Pebble Bed, simple conduction takes care of core cooling and the fuel "pebbles" are very resistant to thermal stress. Pebble Bed also uses Helium as a coolant, resulting in higher efficiencies. Therefore, meltdowns, runaway reactions, steam explosions, are impossible.
Personally, I don't see safety as an issue with nuclear power, especially in the case of new reactor designs. However, waste disposal is a political nighmare. But, I believe solutions such as reprocessing and transmutation can minimize the problem of waste disposal with little risk. I also believe that there are credible solutions to geological storage. Nature has shown such storage is possible via the Oklo natural reactor. Unfortunately, credibiliy in this area is lacking since this long term waste storage has yet to be demonstrated. This is why I support plans for retrievable storage, not permanent disposal, in case something should happen and/or better means of dispoal are found.
Solar power is indeed very expensive - perhaps best indicated by how little it is used. It's also not perfectly clean given the toxic substances used the manufacturing process as well as the sheer scale of the required installations. I'm not sure how fear can be included in calculating energy costs. However, you can include external effects by estimating costs due to environmental damage, impact on human health, etc. This is indeed what some have done.
Herbert Inhaber did some lifecycle analysis a while ago that demonstrated that there are significant external costs associated with renewables and that nuclear has one of the lowest impacts. (I'm not sure how well accepted his conclusions were and I'm sure there's plenty of criticism.) Also, the European ExternE project (which seems to have never submitted a final report) also shows that the external costs of renewable generation exist and are comparable, if not greater, than the external costs of nuclear energy. Of course, the actual numbers are not worth very much. Nevertheless, both of these studies demonstrate (at least qualitatively) that renewables do have a substantial impact and that nuclear may not have as much of an impact as some may believe.
As for the German radioactive "leak," all I was able to find was that the containers were contaminated and were more radioactive then they should be - not leaking radioactive materials into the environment. I'd appreciate it if you had more detailed info. - a technical report would be nice. News articles have this irritating tendency to report things inaccurately.
As for wind power, technical limitations, i.e. intermittency, wind location, dilute energy, land use, etc. are the major disadvantages that I see. For example, the Altamont windmill farm in California is one of the largest wind farms in the world. Nameplate capacity is something like 500MW, but factoring in a typical 20% capacity factor, the real capacity is only 100MW. Virtually every time I drive by the farm, very few of the windmills are turning - a serious reliability problem. I tend to disregard people's complaints about noise and visual pollution. However, there are industrial wastes associated with windmill production and this problem is exacerbated by the simple fact that you need A LOT of windmills to produce significant quantities of energy.
Certainly, we can do much more in terms of renewable generation - it is A solution, but not THE solution.
1. Potential catastrophe is not a means to evaluate risk - the very important factor of probability is ignored. Risks for newer designs ARE lower - not might be lower.
2. You don't necessiarily have to use Sodium in a fast breeder reactor. Gas Cooled Fast Reactors, using helium could work. Molten Salt (not Na) could also work. Light water breeder reactors can be fueled with Thorium, which is quite abundant.
I'm also curious by what you mean by "peculiar economic situation of those countries."
It differs from something like a computer system where you can give a uptime estimates on 99.999% for instance. You can test these things to failure, and form statistics based on actual usage. Clearly you can not do this with a nuclear power plant.
Nuclear power has thousands of reactor-years of experience that provides such real world data. And so far, the safety of nuclear power has been unparalleled.
However, I agree with the your assessment that figures from risk analysis are a bit suspect - uncertainties are a given whenever such analysis is done.
Fortunately, the industry has learned from it's mistakes as numerous safety improvements have been made to existing reactors. Furthermore, advanced designs, especially Generation IV reactors, promise to be inherently safe. For example, the Pebble Bed reactor that has been generating so much interest is essentially incapable of melting down due to a variety of physical feedback effects that are "hard-wired" in the physics of the reactor.
Such a reactor, a high temperature gas reactor, would also be much more thermodynamically efficient which directly translates to less waste per kWh.
I have not heard about this incident. However, spent fuel from power production is safely awaiting storage on reactor sites in either fuel pools or dry cask storage. In the U.S., virtually all nuclear fuel from power production has been succesfully sequestered from the environment. What remains to be seen is if this fuel can be successfully sequestered in a geological repository. However, nature provides evidence that this indeed possible. A natural reactor, Oklo, was in operation in Africa many thousands of years ago. French geologists discovered the deposit of uranium only to find that the composition of the deposit looked just like spent reactor fuel. They also discovered that over thousands of years, despite an abundant source of ground water and no engineered containment, the radioactive elements had transported only several feet. However, this says nothing about the situation in Denver. However, the stuff in Denver is most likely not spent fuel. In fact, nuclear fuel is very strictly regulated.
Nuclear is not the most expensive source of energy. Solar is. Secondly, I don't know where you got the impression that the trains were leaking radioactive waste. The German waste is immobilized in glass and is very resistant to decomposition. Also, "natural" energy is not risk-free - nothing is risk free. It's ridiculous to claim that enormous wind and solar energy systems are perfectly safe. In fact, lifecycle analysis has shown that renewables have a significant impact on human health. Some studies have even shown that nuclear has one of the lowest impacts on the environment and human health! Furthermore, we have studies claiming that several thousand people die every year from air pollution. We could light off a few nuclear plants a year and still not have as great of an impact. Yet, fossil fuels do not engender the same amount of public outcry. I fully support increasing our renewable generation capacity to significant levels. Only then will people realize the true costs of these systems. Soon afterwards, people will realize that their options are limited and they will start rationally evaluating all sources of energy.
As noted in another reply, you cannot have a NUCLEAR explosion in a nuclear reactor. Physically, it is impossible. Furthermore, tests have shown that a U.S. style containment structure could have contained the Chernobyl explosion. Regardless, such an explosion in a U.S. reactor is near impossible due to physical feedback effects that shutdown the reactor in the case of an accident. In the case of Chernobyl, the reactor had a void coefficient that made the reactor unstable. Steam bubbles in the coolant led to increased reactor power which then led to more steam and then more power and so on. Such a reactor would not be licensed in the U.S. New reactor designs, such as the Pebble Bed Modular Reactor, promise to be inherently safe as they are designed such that they would always shut themselves off and not meltdown in the case of an accident. This is not science fiction.
It is true that the once-through fuel cycle employed in the U.S. would only provide ~100 years of energy. However, closing the fuel cycle by recycling used fuel would increase our fuel supply. Furthermore, breeder technology could provide enough energy for thousands of years, a "somewhat" larger extension of supply.
Transmutation, either accelerator or reactor based, of long-lived elements into shorter-lived elements is currently under research and is showing much promise. We can also "burn" elements such as Plutonium in reactors.
http://people.diamtech.com/hughesj/masters.html
Nuclear power is much much better than coal plants in terms of full lifecycle emissions. Furthermore, lifecycle analysis has shown that solar, wind, and even hydro produce significant emissions. For example, it takes a solar panel 2-5 years just to recover the energy used in producing the panel itself.
The amount of radiation released from coal-fired plants is indeed measurable. If I remember correctly, you receive 0.03 millirems per year on average if you live close to a coal plant. A typical nuclear power plant would expose someone to about 0.009 millirems per year. Both of these levels are far lower than anything experienced at Chernobyl. The levels of exposure for Chernobyl "liquidators" are hardly the low levels that are claimed by the report.
Most people seem to forget that renewable energy sources like solar, wind, etc. do produce waste. Solar panels are semiconductors - heavy metals, acids, etc. are waste products. There are also waste products associated with making windmills. The problem is exacerbated by the simple fact that you need huge numbers of solar panels or windmills to produce any meaningful amount of energy. Therfore, the waste problem is magnified by the enormous scale of these installations. In the case of nuclear, the energy is dense both in terms of fuel (and waste) volumes and land use. For example, spent fuel from 40 years of nuclear power generation (representing some ridiculous number of kilowatt-hours) would fill a football field to a depth of 5 yards. In comparison to the wastes generated from industrial processes that we dump on a daily basis or that amount of pollution spewed from fossil fuel combustion, the amount of nuclear waste is miniscule. Therefore, it is much more feasible to sequester nuclear waste from the environment behind multiple engineered and natural barriers. Also, technology exists to recycle spent fuel into new fuel, reducing the quantity that needs to be stored. Trasmutation, accelerator or reactor based, will also be able to transmute long-lived elements into shorter ones.