Monday, May 23, 2011
Radiation Safety Levels - The Moving Target
I have been curious about nuclear power and its potential problems for a long time. In the early days of the atom, it was touted as the new miracle energy that would put everyone on easy street. As with most things so new and wonderful, I have grown to have my doubts, not only about the wonderful promises of life changing improvements, but the doom of life changing disasters.
If a little is good, a lot has to be great, seems to be the cause of most of man kinds problems. Things that are used as directed tend to be fine in most cases, it is when we use too much of a good thing we get in trouble. That seems to be the main problem with nuclear energy.
Nuclear is scary and expensive. Because of that, governments and utilities try to cram too much in small spaces to compromise the fear and cost factors. Then if something goes wrong any is too much. Maybe people will never understand to read directions before use.
Since the situation in Fukushima started, I have spent more time than I should trying to put things in perspective. The nuclear problem is mainly due to trying to get too much out of the Fukushima power plant. At the time the plants were built, they produced huge amounts of energy for the time, with not a great deal of efficiency. The fuel when Fukushima was first built was fairly inexpensive for the time, the safety requirements were the main cost. The game plan to build bigger may have sounded great, but was not all that bright. Then to try to get the plants to produce as long as possible was not too bright either. This is not just a Japanese thing.
Too big is the main problem. While the technology of nuclear power in not difficult to understand in today's world, we still seem to be befuddled by it. More nuclear fuel takes longer to shut down than less. There are pretty simple calculation that you can make to see how much trouble you want to deal with in controlling nuclear power. In the old style reactors, the gross energy is three times the net energy produced. The emergency shut down energy is 7% of the gross and decreases rapidly to 1.5% of the gross over the next 24 hours. To safely shutdown a reactor you have to be able to deal with the 7% quickly and the 1.5% as it decreases for a long time. If you can't deal with it, then there will be a big loss of investment. You have trashed an expensive investment, loss a large portion of you electrical base load, scared the hell out of millions of people and have to pay damages to all the people that have had to change their daily lives to accommodate your screw up. To reduce the impact once the mega plant has been built, you have to use what the design and situation allows to control the damage.
The Japanese dealt with Fukushima as best they could under the conditions. Most people have great hind sight, so it is easy for folks sitting a home to point out all the things that could have been do better. Many say the best solution was to not get into that situation to begin with. I am not particularly better than most at arm chair quarterbacking, but there are a few things I think I have learned from Fukushima.
The first thing I notice is that the older the plant, the more you have to plan for things going wrong. Planning for each and every thing that happened is close to impossible. You can plan for the absolute worst case. That would be that the plant never shutdown and there was no water, no load, no nothing to stop things from going bad.
In a worst case, the worst thing is having to evacuate a sizable population. The area to be evacuated is dependent on the potential amount and spread of radiation. No matter how well the nuclear plant is designed, the potential fallout is has to be considered. Twenty to thirty kilometers is normal for a nuclear power plant of Fukushima's size. That area appears to be based on the size of the individual reactors not the total number of reactors. It takes energy to spread enough radiation and it is the individual reactor energy that would determine the average potential radiation spread. There reactors may spread more radiation, but the distance would be close to the same as the single largest reactor. In terms of human lives and livelihood, the most pressing safety concern, that evacuation area should be minimized.
Time and money can solve most any problem related to a nuclear power plant accident, except for the human element. Smaller individual reactors even with many more installed on a site, reduces the potential impact on lives.
Better understanding of the impact of radiation fallout can also reduce the evacuation area. I have noticed that I am not a part of as small a group as I was ten years ago. Advances in nuclear medicine have educated many more people to the truth of radiation. While it is still dangerous, the human body can tolerate a lot more than previously thought. We have even learned over the past 30 years that every day we are exposed to more naturally than we would have ever imagined. While many radioactive isotopes are no longer common in nature, they have similar isot0pes that are and we are continuously exposed to in varying amounts.
Most of my curiosity about radiation started years ago with the "discovery" of radon levels in homes. I used to test indoor air quality and I avoided jumping on the radon testing bandwagon. The health impact of low levels of radon were nothing compared to common molds. Water in homes where water is not supposed to be, is the primary cause of indoor air pollution followed by out gassing of volatile organic compounds. Knowing this, I have little problem living near a nuclear power plant but would be adamantly opposed to living near a chemical plant. I would have days or weeks to evacuate from a nuclear incident, but could be dead before the alarms sounded if I lived in Bopal, India, for example. Long term exposure to low levels of toxic chemical can have a much more devastating impact than low levels of radiation.
Safe use of nuclear energy demands knowing the potential for harmful levels of fallout in a worse case and understanding what levels are truly harmful. The first is known and can be reduced. The second is the bugger. Japan made a mistake by not establishing more realistic standards of harmful radiation levels. They had to revise maximum levels from their unrealistic standards to more realistic levels while a nuclear situation was in progress. That creates mistrust and that trust may never be regained.
The US Environmental Protection Agency is on the same poor path. They are imposing irresponsible maximum standards that are fractions of the standard guidelines of the US Nuclear Regulatory Commission which are themselves very conservative. For example, the Yucca Mountain National nuclear waste storage facility has EPA limits of 15 Millirem per year above background. 15 millirem per year is 1.7 microrem per hour equivalent to 17 nanosieverts per hour or 0.017 microsieverts per hour. One thousand times that, 1.7 microsieverts per hour, or 14.9 millisieverts per year is about one quarter the radiation exposure limit for people employed in nuclear medicine. With the EPA standard, people living in the area are exposed to more radiation if they have two smoke detectors in their homes (37 kiloBecquerel per detector). Think about that. 37,000 Becquerel per smoke detector. Of course, Becquerel is not directly convertible to Sieverts unless ingested, still it is an illuminating comparison.
Radiation is a part of our lives, isn't it time to start trying to better understand it?
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