Re: LNT clarification

["ADRossin" <ADRossin@msn.com>]

To: Ted Rockwell



cc: All on John Simpson's distribution: A Preachment



Back when I was working on radiation damage in steel I was trying to find a

way to relate the embrittlement of a pressure vessel after 30 full-power

years of operation to the data we could obtain from steel specimens

irradiated in high flux locations in research reactors.  We were trying to

figure out how to understand temperature, time and "dose rate effects."



I learned that there is a relation between temperature and time together,

and that dose rate is irrelevant because the actual damage phenomenon of

forming dislocations, etc. takes place in billionths of a billionth of a

second.  Temperature changes speed up with higher temperatures, but they

years at a few hundred degrees, down to hours or until it almost melts to

change the embrittlement.



We found that for pure, single crystals of silver, copper, etc. we could

find characteristic temperatures above which embrittlement would "anneal

 out" much faster than below that temperature, and there were several

discrete ranges above room temperature where these "activation" temperatures

showed up.  They could be associated with the energy to move an atom from a

particular place in the lattice.



If you've read this far, you will see a clue to radiation effects in people.

But steel was much more complex than single crystals of copper, living

tissue is obviously much more complex than steel, and mice or people are

much, much more complex than tissue.  But there is a lesson here: living

tissue can recover from cell damage.  If it gets damaged badly enough, it

dies.  If the temperature is too high or too low, it dies.  If it has no

water, it dies.  But if it is surrounded by other healthy, living tissue, it

may just survive with no lingering symptoms.



With metals, the damage would decrease with time, very much like radioactive

decay.  The half-life would depend on the metal and the temperature.  The

actual numbers are hard to determine, but what is clear is that there is

recovery over time.  That means the organism can likely recover from low

doses.  It means that cancer and death rates from huge exposures should

never be extrapolated to very low doses.  And it means that the effects of

background radiation are important to understanding radiation.



I preached the importance of recovery and background for years, practiced

trying to apply it, and published a hundred papers on that stuff.  After I

left that field of research in 1965, these ideas did not get used a lot, and

never have been used in biological studies, where they are desperately

needed.



I think it is because they are too hard.  They are not easy to put into

simple expressions, like half-life and man-rem.  They are hard to explain to

reporters.  Scientists just didn't pursue these simple concepts.



So here we are, Ted, decades later, trying to get people to understand that

low doses of radiation do not add up to numbers of cancers per thousand

man-rem.



I can understand the nuclear power industry living with ALARA.  We've

learned to operate under it, and the critics are not clever enough to come

up with anything better than "All radiation kills," which leaves reporters

yawning.  It is the devil we know.



 - - Dave