Some of our nuclear fears are all wrong

The debate over storing nuclear waste in Nevada's Yucca Mountain has raged for years, and even last week's Senate vote to go forward won't quell opposition to the plan. In recent months, opponents have been focusing on the potential dangers of transporting waste across the United States. They have put forward visions of radiological catastrophes resulting from ordinary truck and train accidents or, worse yet, extraordinary terrorist attacks. Environmental groups have sponsored a Web site - www.MapScience.org -- that allows citizens to calculate how close a nuclear-waste transportation route might be to their home.

"No airplane, regardless of size, can fly through such a wall. This has been calculated in detail and tested in 1988 by flying an unmanned plane at 480 mph into a test wall." - Anthony M. Gaglierd

I find this statement interesting because it sounds like we've had drones for quite awhile and not as recent as it's been stated. Maybe I've just not been paying attention :)

"The plane, including its fuel tanks, collapsed against the outside of the wall, penetrating less than an inch. The engines are a better penetrator, but still dug in only 2 inches." - Anthony M. Gaglierd

However, I did pay attention to the details of the plane that slammed into the Pentagon. If the walls there are 5 feet thick, why didn't we find most of the plane lying outside on the ground?

My theory is they flew a model airplane into the reinforced, steel-lined five-foot-thick concrete walls surrounding the nuclear reactor.

For a while now I've been persuaded to generally agree with the information put forth in this article.
But this posting does prompt memory:

Ten years after the Chernobyl incident---which did result in
some very "hot" localized contamination, according to one article that I remember reading, those scientists monitoring the site found field rats living in the grasses
nearby the remains of the plant. The rats' thriving presence, and apparant health were suprising.
It was assumed that mammals of any kind would not be able to live close to the site for generations to come...

It had been calculated that the zone was hot enough to attack and break-down the DNA of living animals if they were to remain within the zone for very long. You know, the
"mutation" due to nuclear contamination syndrome...
Reported in the findings---the rats were in fact suffering
"dna breakages"---BUT---what was more interesting was a correlated finding, which in turn lead them to look more deeply into the question, which lead them to the most interesting finding; firstly, these "affected" rats were not "mutating" at all. Investigating further, evidence was found that as rapidly as the dna was being broken, as would be expected in this case--- but also that the dna
strands were somehow splicing themselves back together!
Which was a total suprise.
Without a hitch, apparently...

They found evidence of gene damage---AND 'repair', and somehow the repaired genes were in proper sequence, not mutated, or changed. Individual rats' dna showed signs of numerous breaks, and corresponding repairs. If memory serves correct, it was more like the dna was in some way re-splicing itself past the breaks, as in perhaps not immedietly right "at" the point of damage, but near-by, then re-attatched past the damage, and so on...
Somehow the DNA strands were able to "jump" past the breakages, about as fast as they occurred.

If the walls there are 5 feet thick, why didn't we find most of the plane lying outside on the ground?
My theory is they flew a model airplane into the reinforced, steel-lined five-foot-thick concrete walls surrounding the nuclear reactor.

My theory is that you've stated an incorrect premise.

The Pentagon doesn't have reinforced, steel-lined five-foot-thick concrete walls. It is merely and office building. It IS the largest office building in the world, but just an office building nonetheless. And office buildings don't have five-foot-thick, steel-lined, reinforced concrete walls. They have windows.

somehow the repaired genes were in proper sequence, not mutated, or changed.

This is because deoxyribonucleic acid (DNA, the building block of genes and chromosomes) has two strands, much like a zipper. The "broken genes" in this situation were in a single strand of the DNA, like breaking one tooth of the zipper.

Natural cosmic radiation and chemical processes in the body cause these types of breaks all the time. You have trillions of such breaks in your body right now. However, living organisms have repair enzymes that constantly repair this kind of break, with essentially 100% accuracy, using the opposite strand of DNA as a template to fix the damaged strand.

Problems only arise when there is a break of both strands of DNA, at the same level or nearby. You can imagine that it would be much easier to repair a single tooth of a zipper than to sew it back together after both sides are torn through.

Double-strand breaks can occasionally happen when a very high-energy particle strikes the DNA directly and tears it apart. However, this is rare even with high exposures.

Most of the damage from radiation occurs because radiation particles interact with water molecules, producing hydrogen peroxide and other 'free radicals.' These chemically interact with the DNA and produce multiple single strand breaks.

Then, the race is on between the body's repair enzymes and the damaging free radicals. If single-strand breaks accumulate faster than they can be repaired, eventually two will occur at the same level or near each other, producing a double-strand DNA break. The fact that some families have a lot of cancer and others have practically none probably relates to genetic variability in the amount and effectiveness of the DNA repair enzymes.

If the ends are not widely separated, sometimes this type of break gets repaired correctly, but quite frequently it is put back together incorrectly or not at all. When this happens, the effect is variable depending on where it is in the gene. It may do nothing at all, or it may induce cell death, or it may cause cancer, or if it happens in a sperm or egg cell, it may cause a hereditary mutation.

The particularly interesting thing is that the repair enzymes are activated by increasing levels of single strand breaks, so low levels of radiation actually rev up the repair mechanism. This has been shown not only in the rat studies you mentioned, but in studies of Hiroshima survivors, Chernobyl residents, and nuclear plant workers. The rates of cancer in some of these populations that have been exposed to significant doses of radiation are two-thirds or less of normal. This effect is called 'radiation hormesis'.

It may be premature to say that human health would be improved by building more nuclear power plants, but it certainly seems that much of our fear of radiation is not only overblown but dead wrong.

For more info: Low-level Radiation & Health

-ccm

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