The Record 2006 - Keble College - University of Oxford

The Life of the College
perceived level of threat from nuclear radiation is a serious issue for
a world, threatened by global warming and pressed to consider the
nuclear power option.
Safety must be quantified. An engineer designing a bridge calculates
the load of the wind and then applies a safety factor of perhaps two or
three, depending on how well the loads can be predicted. No bridge is
affordable if designed on a basis of absolute safety.
Consider the effect of heating parts of the human body. If the body
gets hot for whatever reason, cooling mechanisms quickly cut in to
re-establish the proper temperature. During exercise or a light fever the
body may become heated by 1ºC or 2ºC, and it is well established that
this does no harm. Actually, it is quite difficult to measure very small
temperature increases for tissue localized within the body. On the other
hand, if the temperature is raised by 50ºC or more, the tissue is cooked
or melted and damage is permanent. Such heating is used in new forms
of cancer therapy with focussed ultrasound. However because of the
corrective effect of cooling it makes no sense to suppose that as much
damage is done by raising the temperature of 100 people by 1ºC, as by
raising the temperature of one person by 100ºC. This kind of ill-found
argument is used all too commonly in radiation safety.
Exactly why are we frightened of nuclear radiation?
Nuclear radiation is easy to measure but strikes fear because it is
powerful and cannot be felt. Its power was impressed on the public
when Hiroshima and Nagasaki were destroyed in 1945. In the Cold
War fear of this power combined with early uncertainty of the long
term effects of radiation was used as a political instrument. Since those
days our understanding of long term recovery and the risks to life
from a dose of radiation have been transformed, not least because of
the large body of data available on the survivors of Hiroshima and
Nagaski, measured over 60 years. However the public has not yet
accepted that a complete re-assessment might be in order, although
it quietly accepts benefits in medical therapy. Terrorist threats and
the irresponsible behaviour of rogue states are ever present but the
currency of their nuclear blackmail is inflated by the continuation of
public nuclear phobia.
Mankind with all animals and plants has evolved in an environment
which is bathed in a low level of radiation that comes from outer
space and radioactive materials around us including our own bodies.
Consequently biological cells have developed the capacity to repair
damage caused by low radiation doses. This takes a certain time
– typically the time for cells to reproduce. This varies around days or
weeks. So the significant question is how much radiation can cells or
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