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.

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