Space, plutonium and risk -Reply

[Joyce Davis <JOYCED@DNFSB.GOV>]

>>> Sandy Perle wrote:The article below was published in the
Christian Science Monitor, and  all in all, it appears to be well
written.... I don't see the  typical scare tactics seen in many other
articles. 

>BOSTON -- Mindful of the risks to using nuclear power sources in 
space, planners for NASA's upcoming Cassini mission say they are
working to keep those risks to a minimum.
....... 
 >The nuclear power sources used, known as radioisotope  
thermoelectric generators (RTGs), use plutonium 238 for heat. Unlike
a nuclear reactor, whose heat comes from chain reactions, an RTG uses
heat from plutonium's natural decay. Solid-state devices turn the
heat into electricity. Smaller amounts in special containers are used
to keep a craft's electronics warm enough to operate....<

 Note the use of the word "natural".  That's one of the "good" words
today.  Notice also that Plutonium-238 is not described as "manmade"
or "artificial" (the opposite of "natural").  "Chain-reactions" are
probably not viewed as "natural".  That's why we need to get out the
word (especially to children -- the public of the future)  about the
natural reactor at Oklo.

>Plutonium-238, while nothing to trifle with, is less radioactive 
than its nuclear-weapons cousin. The danger to humans comes mainly
from inhaling tiny particles of plutonium dust, according to
physicists, as well as NASA's environmental impact statement....< 

Purists will declare this is an error;  Pu-238 with its
eighty-something year half-life is far more radioactive than Pu-239. 
However, if we consider it in the context of uses, the use of Pu-238
results in much less radioactivity than the use of Pu-239 in a weapon
that explodes and releases stupendous amounts of radiation.  In that
sense, the statement is true.  It helps the reader understand the
deeper truth involved.  I would let it stand without quibbling.

 >.....up to 5 billion people could be affected. But the statement
adds that the radiation dose a person might receive would be far
lower than what they get from natural sources. Any adverse health
effects, it estimates, would likely be indistinguishable from other,
more-common occurrences.<

Again the word natural appears in a reassuring context.  Note there
is no quantitative estimate of the effects given; nor, I think, is
one needed to convey the deep truth about the magnitude of potential
impacts.

I can't tell if the reporter alone is responsible for the selection
of the non-inflamatory language used, or if the briefer, or press
release writer was wise in the selection of explanatory material.  I
think we can learn something from such examples.  Thanks to Sandy for
posting it.

Only the opinion of J. P. Davis
joyced@dnfsb.gov