I spent way too much time debating the nuclear situation with real scientists the past few days. Mainly the climate sciences guys and their followers. The only reason I am involved in the climate science debate is that I really do not trust a lot of their statistical methodology. The nuclear debate was illuminating.
Probability is an important tool for scientists. Nuclear energy would not be possible without probability and statistics. Significant probabilities are the things lurking in the hypothetical world that need to be discovered. Possibility is meaningless in science. Solid statistical probability is the pooh.
Events with probabilities approaching zero were being contemplated as potential reality by scientists that should know better. Not all by any means, but a few. That is the real world of climate science. A few, unfortunately more vocal, members of the climate science community are lost in the fantastical world of the hypothetical. They honestly believe they have discovered the climatological equivalent of perpetual motion. Trees located so that they magically represent the sweet spot of climate teleconnection. Novel statistical methods to manufacture missing data to incredibly certainty. The mystical insight to prove that the Japanese earthquake was caused by climate change. Amazing feats of the metaphysical!
Some of the players were realists. One, Eli Rabbet, surprised me with a display of common sense and realism that is truly worthy of an engineer. Another, James Annan, living in Japan, was the purest model of pragmatism. Those are two useful isms.
Friday, March 18, 2011
Japanese Nuclear Crisis - Radiation Impact
The effects of radiation exposure is a unpredictable puzzle that is scary and fascinating. What I think are weird contradictions are documented.
In 2008, about 20 years after Three Mile Island, a thyroid cancer study discovered that cases were much lower in the county of the reactor than the counties around the reactor. A study of thyroid cancer following Chernobyl discovered a much greater number of cases. In the Chernobyl area, contaminated milk produced by cows eating contaminated grass was found to be the main source of the radiation causing thyroid cancer. The TMI study did not mention the specifics of the source or reason for the reduction of cases. Heavier isotopes were dispersed at Chernobyl and lighter tritium was the main type of material released at TMI. The difference in the type of radioactive material explains most of the differences, but why tritium seems to act as a vaccination against thyroid cancer is not completely clear to me. It makes some sense, but the amount of radiation dosage was so small at TMI that I am surprised that any significant result was found. Perhaps, that is an endorsement for homeopathy medicine?
The recommended range of exposure limits are much wider than I would expect. NCR recommended maximum public exposure is much lower because of unknown factors. Limits for workers in the nuclear industry are 50 time greater than the public exposure limit. The acute dosage where health impact is not significant is 100 times the public exposure dosage. The acute dose where there is a 50% chance of lethal exposure is 500 times the public dose limit. A relative guideline for the Japanese situation would seem to be the minimum limit with the maximum acute dose as a maximum limit. The range with uncertainty would seem to be more informative for the public than just the low end. The news media rarely reports the range and uncertainty properly in my opinion. If people have better information they can make better personal choices. Children and pregnant women have the highest risk, so they should definitely take greater precautions. The government announcements do not clearly define the risk per age, dose and radiation type to avoid unneeded panic. Honesty in reporting uncertainty would be important for me.
My decision on the value of nuclear energy is based on a comparison of the TMI and Chernobyl accidents. There are huge differences in the two cases, design, isotopes released, fallout distribution and government trust worthiness are some of the main factors I considered. Democratic governments for all their faults are much more trust worthy than any other form of government. That is a very important factor because you can't make good decisions without good data.
The location, prevailing wind and the apparent blend of isotopes would indicate that the Japanese crisis will be similar to TMI. Reactor design is the main reason the impact will be much lower than indicated in the media. There are several things were radioactive release could have been reduced. It is hard at this moment to determine how much design changes would have effected the outcome.
I hope everyone will keep an open mind, take reasonable precautions and not spread too much incorrect information. Human nature means people will exaggerate the situation, so bear that in mind. Considering the magnitude of the events, the design and people involved performed admirably. Then that is just my opinion. Unfortunately, it will take time to know the whole story.
My prayers are with the nation of Japan.
In 2008, about 20 years after Three Mile Island, a thyroid cancer study discovered that cases were much lower in the county of the reactor than the counties around the reactor. A study of thyroid cancer following Chernobyl discovered a much greater number of cases. In the Chernobyl area, contaminated milk produced by cows eating contaminated grass was found to be the main source of the radiation causing thyroid cancer. The TMI study did not mention the specifics of the source or reason for the reduction of cases. Heavier isotopes were dispersed at Chernobyl and lighter tritium was the main type of material released at TMI. The difference in the type of radioactive material explains most of the differences, but why tritium seems to act as a vaccination against thyroid cancer is not completely clear to me. It makes some sense, but the amount of radiation dosage was so small at TMI that I am surprised that any significant result was found. Perhaps, that is an endorsement for homeopathy medicine?
The recommended range of exposure limits are much wider than I would expect. NCR recommended maximum public exposure is much lower because of unknown factors. Limits for workers in the nuclear industry are 50 time greater than the public exposure limit. The acute dosage where health impact is not significant is 100 times the public exposure dosage. The acute dose where there is a 50% chance of lethal exposure is 500 times the public dose limit. A relative guideline for the Japanese situation would seem to be the minimum limit with the maximum acute dose as a maximum limit. The range with uncertainty would seem to be more informative for the public than just the low end. The news media rarely reports the range and uncertainty properly in my opinion. If people have better information they can make better personal choices. Children and pregnant women have the highest risk, so they should definitely take greater precautions. The government announcements do not clearly define the risk per age, dose and radiation type to avoid unneeded panic. Honesty in reporting uncertainty would be important for me.
My decision on the value of nuclear energy is based on a comparison of the TMI and Chernobyl accidents. There are huge differences in the two cases, design, isotopes released, fallout distribution and government trust worthiness are some of the main factors I considered. Democratic governments for all their faults are much more trust worthy than any other form of government. That is a very important factor because you can't make good decisions without good data.
The location, prevailing wind and the apparent blend of isotopes would indicate that the Japanese crisis will be similar to TMI. Reactor design is the main reason the impact will be much lower than indicated in the media. There are several things were radioactive release could have been reduced. It is hard at this moment to determine how much design changes would have effected the outcome.
I hope everyone will keep an open mind, take reasonable precautions and not spread too much incorrect information. Human nature means people will exaggerate the situation, so bear that in mind. Considering the magnitude of the events, the design and people involved performed admirably. Then that is just my opinion. Unfortunately, it will take time to know the whole story.
My prayers are with the nation of Japan.
Thursday, March 17, 2011
The Japanese Nuclear Crisis
While tragic in many ways, the Japanese nuclear crisis is interesting in even more ways. Design of nuclear reactors have to meet criteria often unfathomable. Events with so low a probability that they would be insignificant, have to be considered. Since few things in life have zero probability, the design elements of nuclear reactors and containment of waste are causing considerable panic.
Designers have to include one element that is extremely difficult to predict. The impact of heroic measures. Emergency workers are valiantly risking their lives to control the situation. Well intentioned, but not very prudent actions are the result in this case.
The type of reactors involved have design features to contain and minimize dangers. Once a significant amount of damage is done to the fuel, partial meltdown, the design of the pressure vessel and concrete containment building should handle the maximum amount of molten radiative fuel possible. The possibility of all the fuel melting, then all the molten fuel melting through the metal pressure vessel, then all of that fuel remaining molten as it falls to the concrete floor of the containment building dry well are extremely remote. That is the basis of the design, and extremely remote possibility.
Should the emergency actions cause water to be introduced into the "DRY" well, the possibility of a steam explosion that can spread the heavier, more dangerous, radioactive elements increases. The Japanese military are dumping sea water on the concrete containment buildings which increase the potential of the disaster, not decreases the potential.
The shape, weight and design of the concrete plug at the top of the containment building takes even this remote possibility into consideration. The plug is heavy enough to not move out of position until pressure in the containment building is high enough to produce potential damage to the containment building. If the plug is removed by a major steam explosion, the shape and size of the containment structure to the plug location, is designed to allow pressure from the steam explosion to be relieved without destroying the containment structure. More water than normal, can create a jet of steam from the containment building until either the water evaporates or the fuel is sufficiently cooled. While the jet is evidence of some cooling of the fuel, it is also evidence of more radioactivity being spread. Health impact wise it is best not to dump sea water on the reactor.
The spent fuel cooling pools is another overly complicated situation. There is a remote possibility that the spent fuel can return to criticality. There is a remote possibility that the Zircaloy cladding of the spent fuel rods can "burn" or oxidize. Both of these are "Extremely" remote possibilities. Most people should have the common sense to report the possibilities in terms that the general public can relate to. The criticality probability is equivalent to winning the Irish sweepstakes, being struck by lightning a couple of times and then still being able to spend the money without your ex-wife getting half of it. The probability of the cladding fire is much greater. While I don't have all the information needed to give a more exact estimate, it is more like winning the Irish sweepstakes and not having to give your ex-wife half.
There is also a huge misunderstanding about how much and what kind of radiation is a problem. Too much too fast is without a doubt a problem, but how much is too much too fast? A good guideline is 5000 millirad per year and 10,000 millirads in rapid doses. Below those numbers there is no measurable increase in cancer risk, per the NRC fact sheet on average dosage. There is a large gray area between 10,000 millirads and 50,000 millirads, the point where significant risk is verified. Even the significance of that risk is dependent on the individual.
So while the situation is tragic, it is also a good learning experience.
Designers have to include one element that is extremely difficult to predict. The impact of heroic measures. Emergency workers are valiantly risking their lives to control the situation. Well intentioned, but not very prudent actions are the result in this case.
The type of reactors involved have design features to contain and minimize dangers. Once a significant amount of damage is done to the fuel, partial meltdown, the design of the pressure vessel and concrete containment building should handle the maximum amount of molten radiative fuel possible. The possibility of all the fuel melting, then all the molten fuel melting through the metal pressure vessel, then all of that fuel remaining molten as it falls to the concrete floor of the containment building dry well are extremely remote. That is the basis of the design, and extremely remote possibility.
Should the emergency actions cause water to be introduced into the "DRY" well, the possibility of a steam explosion that can spread the heavier, more dangerous, radioactive elements increases. The Japanese military are dumping sea water on the concrete containment buildings which increase the potential of the disaster, not decreases the potential.
The shape, weight and design of the concrete plug at the top of the containment building takes even this remote possibility into consideration. The plug is heavy enough to not move out of position until pressure in the containment building is high enough to produce potential damage to the containment building. If the plug is removed by a major steam explosion, the shape and size of the containment structure to the plug location, is designed to allow pressure from the steam explosion to be relieved without destroying the containment structure. More water than normal, can create a jet of steam from the containment building until either the water evaporates or the fuel is sufficiently cooled. While the jet is evidence of some cooling of the fuel, it is also evidence of more radioactivity being spread. Health impact wise it is best not to dump sea water on the reactor.
The spent fuel cooling pools is another overly complicated situation. There is a remote possibility that the spent fuel can return to criticality. There is a remote possibility that the Zircaloy cladding of the spent fuel rods can "burn" or oxidize. Both of these are "Extremely" remote possibilities. Most people should have the common sense to report the possibilities in terms that the general public can relate to. The criticality probability is equivalent to winning the Irish sweepstakes, being struck by lightning a couple of times and then still being able to spend the money without your ex-wife getting half of it. The probability of the cladding fire is much greater. While I don't have all the information needed to give a more exact estimate, it is more like winning the Irish sweepstakes and not having to give your ex-wife half.
There is also a huge misunderstanding about how much and what kind of radiation is a problem. Too much too fast is without a doubt a problem, but how much is too much too fast? A good guideline is 5000 millirad per year and 10,000 millirads in rapid doses. Below those numbers there is no measurable increase in cancer risk, per the NRC fact sheet on average dosage. There is a large gray area between 10,000 millirads and 50,000 millirads, the point where significant risk is verified. Even the significance of that risk is dependent on the individual.
So while the situation is tragic, it is also a good learning experience.
Monday, March 14, 2011
How Great an Idea is Natural Gas Powered Vehicles?
Since the main focus of this blog is supposed to be about hydrogen in our energy economy, maybe I should write something about hydrogen. A commenter mentioned that hydrogen is a storage of energy not a source of energy. He is right and I mention that all the time. Now natural gas is an energy source. It is being pushed pretty hard because it produces less carbon than coal, is available in abundance and pretty cheap. Like hydrogen, natgas, has to be compressed or liguefied to to be a protable energy for trucks and stuff. Compressed is easier, but takes up space, just like hydrogen, so bigger vehicles are better suited for compressed natgas.
Some people think that switching to natgas for your truck or bus will cut down on carbon emissions. Carbon is all the rage of course, so how true is that thought? Hmmm?
Here is a link to the Engineering Toolbox I am going to borrow a table from their blog because I am lazy today. I am giving them a link, talking them up, but I really should ask permission. Hopefully, they won't get too hacked off.
Click to enlarge
1) Commonly viewed as a Bio fuel
2) Bio Energy is produced from biomass derived from any renewable organic plant, including
dedicated energy crops and trees
agricultural food and feed crops
agricultural crop wastes and residues
wood wastes
aquatic plants
animal wastes
municipal wastes and other waste materials
I will touch up the table later, but notice Specific emmission of CO2 column (that is the last column on the bizzarro chart). Natural gas is 0.23 and diesel is 0.24. Yep, that is right, natgas produces a whopping 0.01 Kilogram of CO2 less per Kilowatt of energy! So do you think putting a million hydrogen fuel cell vehicles on the road is the same as converting a million semis to natgas. Not even close, hydrogen rules!
The table, now that it isn't so bizarre, has very useful information. I need to double check, but the values seen accurate. The engineering tool site is very informative if you have some questions or want to double check my stuff. There are a few guestimates on previous posts that I should tighten up.
Some people think that switching to natgas for your truck or bus will cut down on carbon emissions. Carbon is all the rage of course, so how true is that thought? Hmmm?
Here is a link to the Engineering Toolbox I am going to borrow a table from their blog because I am lazy today. I am giving them a link, talking them up, but I really should ask permission. Hopefully, they won't get too hacked off.
Click to enlarge
1) Commonly viewed as a Bio fuel
2) Bio Energy is produced from biomass derived from any renewable organic plant, including
dedicated energy crops and trees
agricultural food and feed crops
agricultural crop wastes and residues
wood wastes
aquatic plants
animal wastes
municipal wastes and other waste materials
I will touch up the table later, but notice Specific emmission of CO2 column (that is the last column on the bizzarro chart). Natural gas is 0.23 and diesel is 0.24. Yep, that is right, natgas produces a whopping 0.01 Kilogram of CO2 less per Kilowatt of energy! So do you think putting a million hydrogen fuel cell vehicles on the road is the same as converting a million semis to natgas. Not even close, hydrogen rules!
The table, now that it isn't so bizarre, has very useful information. I need to double check, but the values seen accurate. The engineering tool site is very informative if you have some questions or want to double check my stuff. There are a few guestimates on previous posts that I should tighten up.
What Happened at the Japanese Nuclear Reactors?
UPDATE: Thanks to Eli the Wacky Wabbit, here is a link with more complete information. It has a few minor corrections to what I have here. Some of the very short live isotopes I did not mention are included. He listed cesium and iodine and what a minor worry they are in a neat way. Also the portable generators appeared to arrive in time, they just didn't have the right plug to hook up the power! I need to double check that because it should only take minutes to splice in directly.
The earthquake and tsunami that struck Japan is a tragic combination of natural disasters. I feel deeply for the Japanese people. On top of the huge destruction by natural forces is the nuclear incident.
As far as worst case scenarios go, the Fukushima reactor is about as close as you get. While accounts are still sketchy, it appears that the plant went through its standard "scram" or shutdown for the situation. The control rods were positioned to stop the reaction. While the reaction was stopped, the reactor core is still hot, so cooling water has to be pumped through the reactor core until the temperature drops, ideally to below 100 degrees C, but below the temperature where the core is damaged will do. Since the Tsunami appears to have flooded the back up diesel generators, the plant only had 4 hours of battery operation for emergency cooling. Because of all the other emergencies caused by the combination earthquake and tsunami, portable cooling equipment was not brought to the reactor in time. Without cooling, the reactor core experienced fuel damage which is a partial meltdown.
Engineers are not really sick individuals, but incidents like this are learning experiences. To be a truly walk away, passively safe design, there would have been no damage to the fuel in this case. Terms have different meanings, so passively safe can mean no significant loss of ionizing radiation, meaning no public health disaster. Whether I disagree with the meaning of the term or not is immaterial, the plant designers have to explain their meaning to the buyers which have to explain it to the public. The circumstances of the incident do qualify it as and extremely unlikely event or combination of events. As such, the final chain of safeties, containment, are designed to prevent significant release of radiation.
The pressure vessel containing the reactor core is the first level of containment. Pressure is the first job of the vessel. It is designed to hold pressure much greater than the operating pressure of the system. Three times operating pressure is a good number with an average burst pressure about twice that. This is just my recollection of design criteria, not the actual dsign of the plant. Pressure relief valves have different settings, normally starting a ten percent over operating pressure. So this plant with an operating pressure of 1000 psi would have 1100 psi first relief valve with 3000 psi pressure vessel rating and an average burst rating of 6000 psi. Since there was an apparent steam explosion, that probably happened outside the main containment building. This is often a design feature so that an explosion in a worst case scenario causes the least possible damage, which in this case is major release of radioactive material.
The containment building is the second level of containment. It is the reinforced concrete building that houses the reactor. Three feet or more of reinforce concrete is a nominal design for a containment building. While a containment building may be designed to contain some pressure, its main design is to contain heat and radiation. The floor of the containment building is the thickest construction to contain molten radioactive fuel in the unlikely event that it burns through the pressure vessel.
With this design, the radiation most likely released is tritium, a radioactive form of hydrogen. Tritium forms during operation when water, the moderator of the reaction, captures two neutrons. thanks to fairly complex statistics, the amount of tritium formed in the reactor cooling water is a small percentage of the normal water and heavy water (also formed in operation which is a stable isotope)in the cooling system. So the total amount of harmful tritium that can be released is small. Tritium occurs in nature and we are exposed to it all the time. The concentration of tritium is the factor of concern. maximum levels of allowed tritium release are normally a fraction, roughly a quarter, of tritium that may be in drinking water in some locations. It is naturally occurring so zero exposure is impossible even without a nuclear reactor. The released tritium as a gas, is spread over a wide area. This appears to be a problem but the wide area decreases the tritium concentration to safe levels, often unmeasurable levels, rendering it harmless. It is a popular misconception that wide spread release of radioactivity is a bad thing. It is actually an important natural safety factor.
The absolute worst case scenario is a complete burn through which should not be confused with a melt down. A burn through is when the nuclear material melts down, then burns through the pressure vessel and the containment building. Should this happen, the molten radioactive material can cause a steam explosion with ground water releasing the more toxic heavier ionizing radioactive elements. In order for this to happen, an extremely unlikely sequence of events would have to happen. First, enough of the fuel would have to melt, all of it pretty much, then it would have to burn through the bottom of the pressure vessel. Again, nearly all of the fuel would have to drop through the bottom of the pressure vessel, then melt through the concrete floor of the containment building. The thermal mass of the containment building is figured into the design to cool several times the amount of "possible" molten fuel that may fall out of the pressure vessel. Then enough molten fuel would have to strike enough ground water to cause an explosion of enough force to blow a path out of the containment building to allow the spread of the heavier radioactive materials. Without going through all the math, the probability of this happening is about as likely as being struck by lightning every day for a couple weeks in a row.
Finally, should the nearly impossible happen, the spread of the heavy radioactive elements is greatly limited by their weight. So the vast majority of the radiation does not go very far. That is bad for the area of the site but a good thing for the local population. The area around the reactor has several rings outlining levels of safety (on a site map not painted on the floor). I will try to dig up a drawing showing regions of risk. Chernobyl, BTW, did not have a containment building, so I will try to compare the two designs.
So what should you expect the actual damages to be in terms of human life lost due to the event? Emergency workers in the vicinity of the reactor have a large risk of being caught in a steam explosion. God love them, firefighting is a dangerous job. In an event of this type it is often best to stay away and let the design its job. Hopefully, emergency operations managers will recognize this in the future. If you exclude emergency workers, by which I am in no way implying their lives are less valuable, the loss of live would be very near zero.
The biggest lesson that should be learned from this incident is trust the design and walk away. The overall design provides for more than enough time to actually walk away to a safe distance.
One reason I promote small modular light water reactors is that the smaller amount of fuel in the reactor allows the system to be "truly" walk away. While mega large scale reactors are most common because of various reasons, the scale of the project increases the probability of reactor core damage. Reactor core damage turns the former containment building into a few billion dollar monument to poor choice. Even though that possibility is small it is significant enough to be concern as this case illustrates.
When this situation plays out, try to keep an open mind about the real damages, instead of the sci-fi hype potential catastrophe damages.
The earthquake and tsunami that struck Japan is a tragic combination of natural disasters. I feel deeply for the Japanese people. On top of the huge destruction by natural forces is the nuclear incident.
As far as worst case scenarios go, the Fukushima reactor is about as close as you get. While accounts are still sketchy, it appears that the plant went through its standard "scram" or shutdown for the situation. The control rods were positioned to stop the reaction. While the reaction was stopped, the reactor core is still hot, so cooling water has to be pumped through the reactor core until the temperature drops, ideally to below 100 degrees C, but below the temperature where the core is damaged will do. Since the Tsunami appears to have flooded the back up diesel generators, the plant only had 4 hours of battery operation for emergency cooling. Because of all the other emergencies caused by the combination earthquake and tsunami, portable cooling equipment was not brought to the reactor in time. Without cooling, the reactor core experienced fuel damage which is a partial meltdown.
Engineers are not really sick individuals, but incidents like this are learning experiences. To be a truly walk away, passively safe design, there would have been no damage to the fuel in this case. Terms have different meanings, so passively safe can mean no significant loss of ionizing radiation, meaning no public health disaster. Whether I disagree with the meaning of the term or not is immaterial, the plant designers have to explain their meaning to the buyers which have to explain it to the public. The circumstances of the incident do qualify it as and extremely unlikely event or combination of events. As such, the final chain of safeties, containment, are designed to prevent significant release of radiation.
The pressure vessel containing the reactor core is the first level of containment. Pressure is the first job of the vessel. It is designed to hold pressure much greater than the operating pressure of the system. Three times operating pressure is a good number with an average burst pressure about twice that. This is just my recollection of design criteria, not the actual dsign of the plant. Pressure relief valves have different settings, normally starting a ten percent over operating pressure. So this plant with an operating pressure of 1000 psi would have 1100 psi first relief valve with 3000 psi pressure vessel rating and an average burst rating of 6000 psi. Since there was an apparent steam explosion, that probably happened outside the main containment building. This is often a design feature so that an explosion in a worst case scenario causes the least possible damage, which in this case is major release of radioactive material.
The containment building is the second level of containment. It is the reinforced concrete building that houses the reactor. Three feet or more of reinforce concrete is a nominal design for a containment building. While a containment building may be designed to contain some pressure, its main design is to contain heat and radiation. The floor of the containment building is the thickest construction to contain molten radioactive fuel in the unlikely event that it burns through the pressure vessel.
With this design, the radiation most likely released is tritium, a radioactive form of hydrogen. Tritium forms during operation when water, the moderator of the reaction, captures two neutrons. thanks to fairly complex statistics, the amount of tritium formed in the reactor cooling water is a small percentage of the normal water and heavy water (also formed in operation which is a stable isotope)in the cooling system. So the total amount of harmful tritium that can be released is small. Tritium occurs in nature and we are exposed to it all the time. The concentration of tritium is the factor of concern. maximum levels of allowed tritium release are normally a fraction, roughly a quarter, of tritium that may be in drinking water in some locations. It is naturally occurring so zero exposure is impossible even without a nuclear reactor. The released tritium as a gas, is spread over a wide area. This appears to be a problem but the wide area decreases the tritium concentration to safe levels, often unmeasurable levels, rendering it harmless. It is a popular misconception that wide spread release of radioactivity is a bad thing. It is actually an important natural safety factor.
The absolute worst case scenario is a complete burn through which should not be confused with a melt down. A burn through is when the nuclear material melts down, then burns through the pressure vessel and the containment building. Should this happen, the molten radioactive material can cause a steam explosion with ground water releasing the more toxic heavier ionizing radioactive elements. In order for this to happen, an extremely unlikely sequence of events would have to happen. First, enough of the fuel would have to melt, all of it pretty much, then it would have to burn through the bottom of the pressure vessel. Again, nearly all of the fuel would have to drop through the bottom of the pressure vessel, then melt through the concrete floor of the containment building. The thermal mass of the containment building is figured into the design to cool several times the amount of "possible" molten fuel that may fall out of the pressure vessel. Then enough molten fuel would have to strike enough ground water to cause an explosion of enough force to blow a path out of the containment building to allow the spread of the heavier radioactive materials. Without going through all the math, the probability of this happening is about as likely as being struck by lightning every day for a couple weeks in a row.
Finally, should the nearly impossible happen, the spread of the heavy radioactive elements is greatly limited by their weight. So the vast majority of the radiation does not go very far. That is bad for the area of the site but a good thing for the local population. The area around the reactor has several rings outlining levels of safety (on a site map not painted on the floor). I will try to dig up a drawing showing regions of risk. Chernobyl, BTW, did not have a containment building, so I will try to compare the two designs.
So what should you expect the actual damages to be in terms of human life lost due to the event? Emergency workers in the vicinity of the reactor have a large risk of being caught in a steam explosion. God love them, firefighting is a dangerous job. In an event of this type it is often best to stay away and let the design its job. Hopefully, emergency operations managers will recognize this in the future. If you exclude emergency workers, by which I am in no way implying their lives are less valuable, the loss of live would be very near zero.
The biggest lesson that should be learned from this incident is trust the design and walk away. The overall design provides for more than enough time to actually walk away to a safe distance.
One reason I promote small modular light water reactors is that the smaller amount of fuel in the reactor allows the system to be "truly" walk away. While mega large scale reactors are most common because of various reasons, the scale of the project increases the probability of reactor core damage. Reactor core damage turns the former containment building into a few billion dollar monument to poor choice. Even though that possibility is small it is significant enough to be concern as this case illustrates.
When this situation plays out, try to keep an open mind about the real damages, instead of the sci-fi hype potential catastrophe damages.
Sunday, March 13, 2011
How to Overly Complicate a Simple Problem
In the United States, energy is at the core of a variety of real and perceived problems, both now and projected into the future. Due to an amazingly wide array of political and technological limitations, a clear path to energy related solutions is obscured in noise generated by agenda driven groups. Honest risk assessment is key to resolving this overly complicated issue.
1. Reduced dependence on potentially unstable sources of energy is in the best interest of our nation. It is impossible to make a case were reduction in the supply of foreign sources of energy will not have an adverse impact on America.
2. Every source of energy has risk and rewards. Honest evaluation of the "real" risks related to health, welfare, environmental and financial concerns, is improperly communicated. All of these risks are known. Even the "unknown" events can be quantified in terms of risk. Understanding of the "real" risks is inadequate for the general population to agree on appropriate action.
3. Sustainable energy sources are defined by both availability and cumulative negative impacts. Sustainable should not be interpreted as infinite. Technological advances and scientific evaluation of impact progresses as the "unknowns" are identified. This requires flexibility and diversity of energy choices to limit negative impacts.
Based on the three facts stated above each energy source should be evaluated.
Oil - Oil is primarily used as a transportation fuel. The methods used to convert any form of oil into energy are limited by the efficiency of the process used. Internal combustion engines are approaching a plateau of maximum efficiency. Efficiency limits the reduction of negative impacts possible with mass use of oil. For example; lower efficiency leads to more rapid depletion, increased of waste products and increase probability of "unknown" impacts.
Coal - As with oil, efficiency is a major consideration. Unlike oil, average efficiency as used, is much lower than the maximum limit of current technology and the theoretical limit of efficiency. Current technology limits efficiency to 80% versus a current industry standard efficiency of 40% (See efficiency options). Environmental concerns with coal production and use are real, but have a high degree of variability. Increased efficiency in conversion will reduce many of the risks, but methods of extraction and transport must be evaluated to address to minimization of negative impacts.
Natural Gas - Natural gas can be used for fuel a variety of processes. Efficiency considerations vary with use. A utility scale power plant application is were highest efficiency operation is required (See efficiency options). Environmental concerns of natural gas are fairly well known.
Efficiency options: Theoretical maximum efficiency is 95% for utility scale fossil fuel power plants. While maximum efficiency is desired in most cases there are limits and exceptions. Co-generation efficiencies of 80% are obtainable where waste heat (which can produce chilled water or ice) can be use for heat related processes including building heating and cooling. In applications where waste products are included as a percentage of fuel, lower efficiencies may be desired.
Nuclear - Efficiency of conversion to energy has to be considered differently in the case of nuclear. Lower efficiency in many designs increases safety. Wide spread use of nuclear energy requires lower efficiency reactor designs for greater geographical coverage with centralized high efficiency reactors to process fuel from the lower efficiency reactors in a more secure environment. As technology is proven, a variety of passively safe designs will provide one or more alternatives for current technology. Clearly communicating "real" risks associated with nuclear technology is much more problematic than most energy sources. False perceptions of risk have been instilled in society through generations of science fiction and action entertainment productions that greatly overstate real and create unreal scenarios of mass destruction. Despite real and grotesquely portrayed unreal risks, environmental and financial benefits of responsible use of nuclear energy are much greater than many other alternatives.
Wind - Efficiency of conversion has primarily financial and environmental impacts. Environmental impacts are less likely to be completely understood because of the limited time the impacts have been studied. Some impact bird and bats has been noted. Sound and light pollution (pulsating shadows of the moving blades) impact has been noted. The degree of impact of these issues are not well understood. There are also instances where designs are failing prematurely, blade icing posing problems, grid capacity limitations and requirements for other energy sources to compensate for intermittent availability. Real costs have been artificially deflated with subsidies while long term cost cannot be accurately determined. Wind energy is currently limited to no more than 20% of total production due to the nature of its intermittent source.
Solar - Efficiency plays a huge role in its viability both in terms of conversion of energy and cost of production. While technological advancement is slowing, the proper balance between product efficiency and production efficiency has not been resolved. Reduction in over all cost continues which reduces the wisdom of major expansion faced with a falling market. Environmental impacts appear to be low, but wide scale implementation may produce unanticipated negative impacts related to disposal, manufacturing waste and land use.
Biomass - Efficiency in terms of production, land use and end use, poses a complex blend of real and potential issues. Use of commodities such as corn, soybeans and sugar subject prices to radical fluctuation common to the commodities markets. Diversion of acreage suitable to food production, to fuel production, decreases the real sustainability of biomass as an energy source. Biomass using non-arable acreage shows promise though current production is too low for complete analysis. Environmental impact varies greatly depending on acreage used, methods used, resources used and percentage of total energy produced.
Standard Hydroelectric - Management of water resources and flood control are the major considerations. Environmental impacts are well known and have to be weighed against the water resource and flood control needs. Energy only expansion is unlikely to be significant. Efficiency is not an issue.
Non-Standard Hydroelectric - This is a potentially huge area that has limited current applications installed for proper evaluation. Waves, currents, tides and ocean temperature differentials can be used to produce energy. Transmission distance is a current limiting factor that may be reduced by energy storage. Environmental impact has to be determined by design and method of transmission and/or storage. Efficiency, as it relates to cost, is an issue that can be simplified to comparative cost of usable energy output.
Geo-Thermal - This area also has a wide variety of applications. Currently, environmental impacts and scale of produced usable energy are limiting factors. Smaller scale hybrid geo-thermal applications for heating and cooling are promising. Large scale electrical production is limited by geographical and technological constraints.
Other - Undiscovered energy production potential and hybridization of various technologies to better exploit waste are interesting and often over looked potential energy sources. Normally lumped in with other energy categories, it deserves a place of its own. Everything from landfill mining, sterling engines, super-conductive technology, hydrogen production and methane production from waste can be exciting additions to our energy portfolio.
Energy from trash (waste) combines disposal of certain types of problematic waste, petroleum coke, used tires and combustible, recyclable waste. The quality of the waste as a combustion fuel dictates the type of process used. Liquifecation of waste under heat and pressure allows for easier separation of non-combustible material such as metal tire reenforcement wires, then the liquid waste fuel can be used for a variety of purposes. When waste is used as a fuel mix in coal or natural gas fired plants, the plant design must allow for removal of non-combustibles after firing. Lower thermal efficiency is offset by benefit of waste disposal. Environmental impact of the raw waste and the combustion waste must be compared when evaluating these systems.
I will try to expand the detail and add links to promising new designs in the future.
Health risks - Coal, nuclear and combustible waste have the greater health risks of the energy sources. Each require special considerations to reduce introduction of harmful pollutants that can cause health problems. Ionizing radiation is a harmful by-product of all three. In nuclear applications containment and reactor design are used to minimize release of harmful radiation. With coal and waste fuels, dispersion minimizes health impact. Non-radioactive pollutants are more prevalent. Pre-combustion additives can be used to chemically react with certain elements during the combustion process. Post combustion, neutralizing chemical scrubbers, electrostatic precipitation and filtration can be used in combination to capture harmful pollutants. 100% capture is not economically feasible with current direct combustion technology. The Environmental Protection Agency (EPA) has minimum standards for all known pollutants for coal fired plants. Waste fueled (incinerators) and combined waste fueled power plants have a greater potential for unknown pollutants. Current EPA requirements appear to be more than adequate for public health protection.
CO2 - Carbon dioxide has been recently added to the EPA pollutant list. CO2 is not considered a pollutant in terms of human health. It may lead to harmful climate disruption and ocean PH reduction in sufficiently high concentrations. Fossil fuels, oil, coal and natural gas produce CO2 which are considered positive carbon contributors. The percentage of carbon dioxide per unit energy is a consideration needed for all fossil fuel applications. At equal thermal efficiency, coal produces the most, followed by oil then natural gas. A coal plant that is 60% more efficient than natural gas plant will produce roughly the same CO2 as the natural gas plant. Integrated Gasification Combined Cycle and other experimental combustion cycles can capture carbon dioxide. If the CO2 is used for practical purposes or sequestered, the process can approach carbon neutral. CO2 scrubbing is an experimental process using salt water and lime to react with flue gas to capture CO2. Algae can also be used to scrub CO2 producing bio-mass as a by-product.
Biomass also produces carbon dioxide, but is considered carbon neutral. All biomass is not carbon neutral. Only biomass derived from annual bio-crops is carbon neutral. Peat and mature trees are carbon positive. If the age of the bio-mass is equal to the atmospheric residence time of carbon dioxide it should be considered a fossil fuel. Time to harvest is a major consideration for bio-crops.
NOTE: I HAVE NOT COMPLETELY REVIEWED THIS POST SO THERE MAY BE SOME ERRORS.
1. Reduced dependence on potentially unstable sources of energy is in the best interest of our nation. It is impossible to make a case were reduction in the supply of foreign sources of energy will not have an adverse impact on America.
2. Every source of energy has risk and rewards. Honest evaluation of the "real" risks related to health, welfare, environmental and financial concerns, is improperly communicated. All of these risks are known. Even the "unknown" events can be quantified in terms of risk. Understanding of the "real" risks is inadequate for the general population to agree on appropriate action.
3. Sustainable energy sources are defined by both availability and cumulative negative impacts. Sustainable should not be interpreted as infinite. Technological advances and scientific evaluation of impact progresses as the "unknowns" are identified. This requires flexibility and diversity of energy choices to limit negative impacts.
Based on the three facts stated above each energy source should be evaluated.
Oil - Oil is primarily used as a transportation fuel. The methods used to convert any form of oil into energy are limited by the efficiency of the process used. Internal combustion engines are approaching a plateau of maximum efficiency. Efficiency limits the reduction of negative impacts possible with mass use of oil. For example; lower efficiency leads to more rapid depletion, increased of waste products and increase probability of "unknown" impacts.
Coal - As with oil, efficiency is a major consideration. Unlike oil, average efficiency as used, is much lower than the maximum limit of current technology and the theoretical limit of efficiency. Current technology limits efficiency to 80% versus a current industry standard efficiency of 40% (See efficiency options). Environmental concerns with coal production and use are real, but have a high degree of variability. Increased efficiency in conversion will reduce many of the risks, but methods of extraction and transport must be evaluated to address to minimization of negative impacts.
Natural Gas - Natural gas can be used for fuel a variety of processes. Efficiency considerations vary with use. A utility scale power plant application is were highest efficiency operation is required (See efficiency options). Environmental concerns of natural gas are fairly well known.
Efficiency options: Theoretical maximum efficiency is 95% for utility scale fossil fuel power plants. While maximum efficiency is desired in most cases there are limits and exceptions. Co-generation efficiencies of 80% are obtainable where waste heat (which can produce chilled water or ice) can be use for heat related processes including building heating and cooling. In applications where waste products are included as a percentage of fuel, lower efficiencies may be desired.
Nuclear - Efficiency of conversion to energy has to be considered differently in the case of nuclear. Lower efficiency in many designs increases safety. Wide spread use of nuclear energy requires lower efficiency reactor designs for greater geographical coverage with centralized high efficiency reactors to process fuel from the lower efficiency reactors in a more secure environment. As technology is proven, a variety of passively safe designs will provide one or more alternatives for current technology. Clearly communicating "real" risks associated with nuclear technology is much more problematic than most energy sources. False perceptions of risk have been instilled in society through generations of science fiction and action entertainment productions that greatly overstate real and create unreal scenarios of mass destruction. Despite real and grotesquely portrayed unreal risks, environmental and financial benefits of responsible use of nuclear energy are much greater than many other alternatives.
Wind - Efficiency of conversion has primarily financial and environmental impacts. Environmental impacts are less likely to be completely understood because of the limited time the impacts have been studied. Some impact bird and bats has been noted. Sound and light pollution (pulsating shadows of the moving blades) impact has been noted. The degree of impact of these issues are not well understood. There are also instances where designs are failing prematurely, blade icing posing problems, grid capacity limitations and requirements for other energy sources to compensate for intermittent availability. Real costs have been artificially deflated with subsidies while long term cost cannot be accurately determined. Wind energy is currently limited to no more than 20% of total production due to the nature of its intermittent source.
Solar - Efficiency plays a huge role in its viability both in terms of conversion of energy and cost of production. While technological advancement is slowing, the proper balance between product efficiency and production efficiency has not been resolved. Reduction in over all cost continues which reduces the wisdom of major expansion faced with a falling market. Environmental impacts appear to be low, but wide scale implementation may produce unanticipated negative impacts related to disposal, manufacturing waste and land use.
Biomass - Efficiency in terms of production, land use and end use, poses a complex blend of real and potential issues. Use of commodities such as corn, soybeans and sugar subject prices to radical fluctuation common to the commodities markets. Diversion of acreage suitable to food production, to fuel production, decreases the real sustainability of biomass as an energy source. Biomass using non-arable acreage shows promise though current production is too low for complete analysis. Environmental impact varies greatly depending on acreage used, methods used, resources used and percentage of total energy produced.
Standard Hydroelectric - Management of water resources and flood control are the major considerations. Environmental impacts are well known and have to be weighed against the water resource and flood control needs. Energy only expansion is unlikely to be significant. Efficiency is not an issue.
Non-Standard Hydroelectric - This is a potentially huge area that has limited current applications installed for proper evaluation. Waves, currents, tides and ocean temperature differentials can be used to produce energy. Transmission distance is a current limiting factor that may be reduced by energy storage. Environmental impact has to be determined by design and method of transmission and/or storage. Efficiency, as it relates to cost, is an issue that can be simplified to comparative cost of usable energy output.
Geo-Thermal - This area also has a wide variety of applications. Currently, environmental impacts and scale of produced usable energy are limiting factors. Smaller scale hybrid geo-thermal applications for heating and cooling are promising. Large scale electrical production is limited by geographical and technological constraints.
Other - Undiscovered energy production potential and hybridization of various technologies to better exploit waste are interesting and often over looked potential energy sources. Normally lumped in with other energy categories, it deserves a place of its own. Everything from landfill mining, sterling engines, super-conductive technology, hydrogen production and methane production from waste can be exciting additions to our energy portfolio.
Energy from trash (waste) combines disposal of certain types of problematic waste, petroleum coke, used tires and combustible, recyclable waste. The quality of the waste as a combustion fuel dictates the type of process used. Liquifecation of waste under heat and pressure allows for easier separation of non-combustible material such as metal tire reenforcement wires, then the liquid waste fuel can be used for a variety of purposes. When waste is used as a fuel mix in coal or natural gas fired plants, the plant design must allow for removal of non-combustibles after firing. Lower thermal efficiency is offset by benefit of waste disposal. Environmental impact of the raw waste and the combustion waste must be compared when evaluating these systems.
I will try to expand the detail and add links to promising new designs in the future.
Health risks - Coal, nuclear and combustible waste have the greater health risks of the energy sources. Each require special considerations to reduce introduction of harmful pollutants that can cause health problems. Ionizing radiation is a harmful by-product of all three. In nuclear applications containment and reactor design are used to minimize release of harmful radiation. With coal and waste fuels, dispersion minimizes health impact. Non-radioactive pollutants are more prevalent. Pre-combustion additives can be used to chemically react with certain elements during the combustion process. Post combustion, neutralizing chemical scrubbers, electrostatic precipitation and filtration can be used in combination to capture harmful pollutants. 100% capture is not economically feasible with current direct combustion technology. The Environmental Protection Agency (EPA) has minimum standards for all known pollutants for coal fired plants. Waste fueled (incinerators) and combined waste fueled power plants have a greater potential for unknown pollutants. Current EPA requirements appear to be more than adequate for public health protection.
CO2 - Carbon dioxide has been recently added to the EPA pollutant list. CO2 is not considered a pollutant in terms of human health. It may lead to harmful climate disruption and ocean PH reduction in sufficiently high concentrations. Fossil fuels, oil, coal and natural gas produce CO2 which are considered positive carbon contributors. The percentage of carbon dioxide per unit energy is a consideration needed for all fossil fuel applications. At equal thermal efficiency, coal produces the most, followed by oil then natural gas. A coal plant that is 60% more efficient than natural gas plant will produce roughly the same CO2 as the natural gas plant. Integrated Gasification Combined Cycle and other experimental combustion cycles can capture carbon dioxide. If the CO2 is used for practical purposes or sequestered, the process can approach carbon neutral. CO2 scrubbing is an experimental process using salt water and lime to react with flue gas to capture CO2. Algae can also be used to scrub CO2 producing bio-mass as a by-product.
Biomass also produces carbon dioxide, but is considered carbon neutral. All biomass is not carbon neutral. Only biomass derived from annual bio-crops is carbon neutral. Peat and mature trees are carbon positive. If the age of the bio-mass is equal to the atmospheric residence time of carbon dioxide it should be considered a fossil fuel. Time to harvest is a major consideration for bio-crops.
NOTE: I HAVE NOT COMPLETELY REVIEWED THIS POST SO THERE MAY BE SOME ERRORS.
Friday, March 11, 2011
An Open Mind Doesn't Mean Letting Your Brains Leak Out
The greatest thing about being able to stand back and look objectively at things is you learn a lot! Sticking with a single ideology is really boring. My greatest strength as a manager was actually listening to the people that worked for me. Even though many had much lower educational backgrounds, they all had things to teach. It didn't take long for me to realize that everyone has a little Einstein and a little Dilbert in them. Of course, some had an affinity for their Dilbert, but I directed them to other career paths where I am sure their opportunities to get in touch with their inner Einstein were expanded.
I have even known liberals that were capable of rational thought. The problem is that the Einstein/Dilbert ratio fluctuates in a pseudo-noise encrypted pattern. Since some of you may have forgotten your spread spectrum communications systems primers, Pseudo-noise is a sequence of information intended to appear completely incoherent, like noise. If you know the sequence you can decipher the message concealed in the sequence. Actress Heddi Lamar is credited with the concept and design of spread spectrum communications systems. Her first system was called frequency hopping. A message was divided between a number of different radio frequencies so that if you knew the sequence of frequencies to be used, you could hear the entire message by jumping at the right time to the next frequency.
The reasons I propose that Einstein/Dilbert fluctuates in Psuedo-noise patterns rather than truly random patterns, is that a pattern appears to exist. This is fairly obvious if you discuss any meaningful but controversial subject. Knowing the person's ideological tenancies, you can anticipate, to a point, Einstein/Dilbert responses to elements of the topic. By synchronizing your Einstein/Dilbert with the other person's Einstein/Dilbert, a coherent conversation can take place. As the Einstein/Dilbert ratio approaches infinity the quality of the conversation approaches perfection. An Einstein/Dilbert ratio greater than or equal to 1 is the minimum required for normal understanding.
Improving communication of information on blogs for example requires adjusting the Einstein/Dilbert responses, interjecting or removing Dilberts as required will maintain a reasonable level of conversation. The advantage of removing Dilberts is obvious, eliminate the Dilberts and there are only Einsteins. The advantage of interjecting Dilberts requires the understanding of Pseudo-noise encrypted communications theory in a chaotic communications environment and the law of biased ideological phraseology. As Einsteins are limited to a small percentage of population and Dilberts are unbounded, pure Einsteinian conversation is only theoretical.
In our next installment we will discuss the basics of Ideological Phraseology.
I have even known liberals that were capable of rational thought. The problem is that the Einstein/Dilbert ratio fluctuates in a pseudo-noise encrypted pattern. Since some of you may have forgotten your spread spectrum communications systems primers, Pseudo-noise is a sequence of information intended to appear completely incoherent, like noise. If you know the sequence you can decipher the message concealed in the sequence. Actress Heddi Lamar is credited with the concept and design of spread spectrum communications systems. Her first system was called frequency hopping. A message was divided between a number of different radio frequencies so that if you knew the sequence of frequencies to be used, you could hear the entire message by jumping at the right time to the next frequency.
The reasons I propose that Einstein/Dilbert fluctuates in Psuedo-noise patterns rather than truly random patterns, is that a pattern appears to exist. This is fairly obvious if you discuss any meaningful but controversial subject. Knowing the person's ideological tenancies, you can anticipate, to a point, Einstein/Dilbert responses to elements of the topic. By synchronizing your Einstein/Dilbert with the other person's Einstein/Dilbert, a coherent conversation can take place. As the Einstein/Dilbert ratio approaches infinity the quality of the conversation approaches perfection. An Einstein/Dilbert ratio greater than or equal to 1 is the minimum required for normal understanding.
Improving communication of information on blogs for example requires adjusting the Einstein/Dilbert responses, interjecting or removing Dilberts as required will maintain a reasonable level of conversation. The advantage of removing Dilberts is obvious, eliminate the Dilberts and there are only Einsteins. The advantage of interjecting Dilberts requires the understanding of Pseudo-noise encrypted communications theory in a chaotic communications environment and the law of biased ideological phraseology. As Einsteins are limited to a small percentage of population and Dilberts are unbounded, pure Einsteinian conversation is only theoretical.
In our next installment we will discuss the basics of Ideological Phraseology.
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