| Modern risks: nuclear power
Nuclear power: the most natural risk of all
A health warning: I researched these pieces in the mid and late
90s: people quoted may have changed their views since. I haven't.
The evidence, too, may have moved on without my spotting it. This
entire site is a work in progress: its evidence is offered in good
faith and comments are welcome.
The wider picture
Everyone "knows" Sellafield glows. It's the butt of a
hundred jokes - or rather, the same joke re-worked hundreds of times.
Making jokes about people suffering radiation burns or leukaemia
- even if they are imaginary sufferings, or their connection to
Sellafield is imaginary - is of course tasteless as well as alarmist.
The difficulty is that every attempt to explain radiation is open
to charges of being deliberately misleading. At the average doses
allowed by the regulator, there is scant evidence of any damage
at all. They are well below doses which produce what are called
"deterministic" effects, namely, very obvious ones. But
if one stresses this fact, people feel you are opening a door to
the idea that radiation is not bad for us. If one concentrates on
the people who get the greatest dose, their being few is forgotten.
If one concentrates on the many whose dose is miniscule, one may
be thought to be distracting attention from those few who have much
How do you draw attention to this source of radiation, which matters
because it exposes many people to a dose; or to that, which matters
because its effects are long-lasting?
Enter, the idea of the "collective dose". Definitions,
first. A collective dose is the sum total of all the doses to all
the people over all time who are exposed to a radiation source.
It's derived from one assumption: that any radiation dose however
small carries with it a proportional risk however small. This is
called the linear dose relationship. If you use that assumption
then the dose received by a population will be proportional to the
health effect. And for radiation purposes, a "health effect"
is regarded as a death.
This is where the devilry begins. Since it's assumed that radiation
causes cancer (in big doses it obviously does) and since we boldly
assume there will be a cancerous effect even at small doses (which
is open to dispute, but assuming it is so is likely to lead us to
usefully cautious behaviour), then collective dose theory (and it's
only a theory) has it that somewhere in all the crowd of people
who receive their portion of a collective dose, there will be some
This is scary. But it flows out of the business of multiplying
a small individual average dose by a lot of people and multiplying
that number by a lot of years. The result gives you large numbers.
That is, it gives a seemingly large amounts of dose given to a crowd
which is "virtual" in the sense that it is composed of
a changing cast of people, amongst whom are the dead, the living
and the unborn. Somewhere in that crowd, it must be assumed there
must be an individual who gets cancer from this dose. It might well
not be true, of course, because the real doses to real people are
in fact small. Collective dose assessment is certainly a way of
magnifying the sense of risk: it assumes a real and large effect
from exposures which may have none, and then starts multiplying
large numbers all over the place. It is prone, like much statistical
work, to the exaggeration which comes from making heroic assumptions
and then adding noughts.
Actually, this quite fits the way we think about cancer causation.
We do not know as much as we would like about this set of diseases.
We know about a third of people die from them, and that that number
has increased because people grow to become older now than they
used to. We know that various sorts of chemical exposure, and exposure
to radiation, do at differing doses cause some cancers and might
be assumed to increase the likelihood of people getting others -
usually after a long period of time (hence the increase of cancer-death
in an ageing population). It is fair to think of most cancers as
having many causes which accumulate to generate the disease. These
include genetic susceptibility, time, and probably a cocktail of
exposures to chemicals and radiation. In both chemical and nuclear
cases, most exposures come from "natural" and more or
less unavoidable sources whose main effects, especially in the case
of chemicals, may even be benign.
A fair way of looking at this picture is to suggest that cancer-causation
is a little like a shove ha'penny board. Each contributory factor
is a coin which plays its part in the queue of coins which will
eventually push one of their number over the edge. This approach
allows that each coin is only a small contributory factor; but the
role of each in the final outcome cannot be ignored: each was a
necessary part of the downfall of the coin which toppled over the
end of the board. We think we ought to reduce the exposure of the
crowd of us to any additional burden or radiation because in the
case of any one of us, any new factor compounding cancer-causation
ought to be avoided. Just because we can't see why or how an exposure
to radiation of low dose can be a problem does not mean it is sensible
to overthrow the generally precautionary logic.
However, there is a further odd complication. If we know many people
will die from cancer and that this is the case as the result of
a cocktail of effects, then probably the most we can say of any
particular new exposure is that it will bring forward the time when
someone contracts a cancer. In other words, it may not by itself
kill anyone. It may have "only" contributed to a fatal
cancer rather than caused it; it may have induced a cancer a little
earlier than the cancer would have happened anyway; it may have
killed someone at 70 who would otherwise have lived to 75.
Campaigners leap on collective dose data and have argued that it
implies that, for instance, the next decade's-worth of Sellafield's
radiation will cause 2000 deaths over the rest of time. But it is
as true to say that the individual risks of a fatal cancer are very,
very small. It is something like one in 1000 million per year. That
is the risk to anyone, anywhere in the world, for all time of getting
a fatal cancer from the plant. That is many times less than the
annual risk of dying in a car crash. The risk is utterly trivial.
It is harder to gauge how much a risk such as is posed by Sellafield's
routine radiation really rates. How much does it prey on people's
minds? Many of the people who live near the plant have the acceptance
of familiarity, stiffened by knowing people whose livings are had
at the plant. And people who live further away are pleased not to
think too deeply about the place.
The naturalness of nuclear risk
Eighteen hundred million years ago, there was an entirely natural,
spontaneous nuclear power station in the earth's crust. Nuclear
scientists are pleased that creation made several of its own reactors
at Oklo, in Africa's Gabon (and elsewhere), partly because it shows
man did not introduce the splitting of atoms in a chain reaction
to this planet. Besides, the radioactive "wastes" from
that reaction seem to have stayed put, just as the scientists hope
to persuade us that modern nuclear wastes can be made to.
Oklo, a reactor for thousands of years, reminds us of our origins.
We and our planet are wastes from a fusion reactor, the sun. Nuclear
fusion is the collision and combination of lighter elements, as
opposed to fission which is the fragmentation of heavier elements;
both release some of the prodigious energy contained in atoms. The
fusion process produces both stable and unstable elements or isotopes.
These unstable elements from our origins in the sun form the basis
of the present nuclear industry and contribute to the natural background
The radioactivity of the earth's elements is decaying, but at different
rates (expressed in half-lives), with different intensities of energy,
and by a number of different routes, including electron-like fragments
called beta-particles and the heavier alpha-particles; and gamma
rays. Alpha, beta and gamma radiation have ascending powers to penetrate
materials, including human tissue, but all can damage cells.
Plantlife on earth is now dependent, as is our climate, on the
heat of the sun's continuing fusion reaction, and the discussion
of how that heat passes through lifeforms is the very heart of the
fashionable science of ecology. Yet the widely distrusted technology
of nuclear physics is doing something elegant, too. Scientists have
found ways of restoring to its former vigour some of the dying radiation
from the nuclear explosion which formed our world, so that it can
reproduce the Oklo process. As a power-generating technique, it
has the merit over traditional fossil-fuel burning that it adds
very little to atmospheric pollution.
There is good and bad news about the radioactive wastes and emissions
from the nuclear industry. Even during its relatively unsophisticated
infancy, they did not add significantly to the amount of radiation
the average citizen received from the radioactive rocks beneath
his or her feet and from continued bombardment from outer space.
Hospitals and surgeries contributed far more to the average dose.
More recently, the industry's discharges have been reduced, in some
cases tenfold, and in the case of Sellafield's emissions to the
sea, a hundredfold.
In any case, because we know a good deal about man's response to
really large extra doses of radiation, we can be fairly confident
that radiation doses have to be a hundred or hundreds of times average
background levels to cause us measurable harm. This strong guess
is in part derived from the effects of the radiation from atomic
bombs used at the end of the second world war: the bombs' radiation
- about a hundred times background - caused about an eighth more
people to die of cancer than would been expected in an equivalent
non-exposed population . Yet the nuclear industry does not multiply
the dose most people receive by tens or hundreds, but only increases
them by a few thousandths. Even to the 1000 UK nuclear workers most
exposed (with doses about ten times average background), the industry
poses little more exposure to radiation than Concorde's flight crews
experience by spending their working lives high enough in the atmosphere
to be less shielded from cosmic radiation than the rest of us. 
Nuclear workers do not have elevated cancer rates. There is epidemiological
- in effect, circumstantial - evidence that the children of the
most exposed nuclear workers are, like workers in a wide range of
industries, slightly more than usually prone to leukaemia. Some
non-nuclear cause makes more obvious sense than that these cases
overturn our understanding about radiation, about which we are nonetheless
right to be deeply cautious.
Whilst nuclear fission is in principle natural, it creates local
concentrations of radioactivity not seen on earth for billions of
years. The process of turning uranium into fuel does not create
more radiation than man began with, but it does concentrate the
radiation in a much smaller bulk. Then, in using it in a reactor
we produce a little more, and more problematic radioactivity than
was in the original uranium. If this were not so, reactor waste
could, in principle, simply be returned to the mines whence it came,
and the earth's crust would be no more radioactive than before.
We have gone further than creation. Man has developed chemical
techniques for recycling the spent fuel from nuclear reactors into
new fuels: a form of uranium, and plutonium. The latter is useful
for bomb-makers, and its potential value to terrorists means that
it has to be accounted for very carefully (though the plutonium
from dismantled Soviet ballistic missile warheads would make a far
more likely source of mischief). The recovery process at the moment
redistributes most of the radioactivity of spent fuel into bulkier,
though much less potent, radioactive wastes. But it also creates
a very small amount of highly active, "high" level waste
of which it is the only source. New developments promise to recover
waste fuels whilst reducing the radioactivity of by-products. The
recovered materials may one day provide a fuel source for fast breeder
reactors, which have the advantage of generating their own fuel,
though their development is stalled partly because uranium is cheap.
The recovered fuel can be treated so as to be useful in conventional
In Britain, recycling of spent fuel is done at Sellafield, including
a new reprocessing plant, THORP. The industry insist the profit
from the operation more than justifies the marginal increase in
radioactivity emissions it involves.
The vast bulk of nuclear wastes (most of what the industry categorises
as "low" level wastes) are such that a dustbin load would
be no more problem to have around the house than a dustbin of domestic
waste. You would not handle it and then lick your fingers, but you
would not need a shield. A couple of dustbin loads in one's house
wouldn't approach the natural background levels of radiation.
There is a smaller quantity of wastes, called "intermediate"
level, which require a sealed container and a few inches of concrete
shielding to protect us against exposure to gamma radiation and
ingestion of toxic dust. Only about a thousandth of the radioactive
wastes is high level and it is this material which must be treated
as a very toxic substance requiring several feet of concrete to
protect us from the intense gamma radiation.
There is a double-decker load of high level waste in the UK, and
its danger comes from its very active decay processes, which lead
to the relatively short period of its intense radioactivity (in
other words, its short half-life). However, the activity in high
level waste will fall over about 500 years, to a thousandth of its
present level and be equivalent to our intermediate level waste.
High level waste will become as radioactive as low level waste
in 10 million years, or as radioactive as the original uranium from
the earth's crust, in about a million years. However, we can draw
some comfort from the fact that highly penetrating radioactivity
will substantially reduce much quicker: after less than a thousand
years a sheet of paper would stand as sufficient barrier between
us and the emission of the waste's radioactivity, though we would
still have to guard against eating or inhaling it.
The curent intention, for which permission is currently being sought
by the industry, is to bury the intermediate nuclear wastes 650
metres deep in the earth's crust. If this sounds like dumping, one
should remember that the waste will be in containers designed to
delay corrosion, and these will be sealed in caverns backfilled
with material chosen to have a benign chemical effect on the waste.
The whole will then be housed in an area which will have to pass
tough tests as to the likelihood of any radioactivity getting into
water which could reach the biosphere.
Even so, it is proposed to delay the disposal of the high level
wastes. They generate heat, so it is deemed wise to store them above
ground for a generation, until they have cooled and decayed somewhat,
before some sort of deep burial.
Nuclear technology involves dangerous material and processes. So
do the coal and oil technologies, which have killed and diseased
far more employees and customers in accidents, smogs and mines.
Even a very bad nuclear accident, such as extreme folly induced
at Chernobyl did not kill nearly as many people as died in the Piper
Alpha oil field accident, whose death toll was 167. However, there
will be hundreds and perhaps thousands of cancers because of Chernobyl:
radiation doses kill most of their victims after a delay of a couple
of decades. But then, there are health risk associated with burning
the oil which Piper Alpha wsproducing, as well.
Why take the risks associated with even well-managed nuclear power?
Sometime half way through the next century, and barring accident,
there will be 10 billion energy-hungry people in the world. Of these,
many will live on bits of the earth's crust which are rich in coal
and to a much lesser extent oil. Both these are the product of the
arrested and modified decay of plantlife orginally fueled by the
heat of the sun's fusion reactions. Niether will last indefinitely,
and in any case their use is expensive if limiting or adjusting
to their pollution is taken into account. If global warming becomes
a prime factor, we will have an additional motive to shift towards
non-fossil fuels. True, solar power technologies can do a good deal
with the present warmth of the sun, but they are expensive.
We may yet be very glad that we know how to use the radioactivity
which remains from the earth's creation.
 In the Japanese case, 42,000 people were exposed to an average
dose of 300 mSv (average UK exposure 2.5 mSv); by 1986, 3291 of
that population died of cancer, about 400 more than would have been
expected in a non-exposed population. 1991, KSU Analysis Group,
S-611, 82 Nykoping, Sweden.
 In 1987 4 workers receieved in excess of legal limit of 50 mSv.
1000 received doses above 15 mSV. Annual average worker does 2mSv.
Subsonic aircrew are exposed to about 2mSv and supersonic crews
to 2.5 mSv-17 mSv. Coalminers average 1.2 mSv. Radon-exposed miners
recieve about 14 mSv. pp 33-34, Living With Radiation, National
Radiological Protection Board, 1990, London, HMSO.
 p 24 Radiation: Effects and Control, UKAEA, Feb 1993.