Nuclear Disasters & the Built Environment. A Report to the Royal Institute of British Architects

135 Pages·1990·8.36 MB·English

by  Philip Steadman and Simon Hodgkinson (Auth.)

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NUCLEAR
DISASTERS
OTHE
BUILT
ENVIRONMENT
A REPORT TO THE
ROYAL INSTITUTE OF
BRITISH ARCHITECTS
PHILIP STEADMAN
MA (Cantab), ScD
SIMON HODGKINSON
BSc, AAGrad. Dip., M Phil
BUTTF.RWORTH ARCHITECTURE
Butterworth Architecture
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First published 1990
© Butterworth & Co. (Publishers) Ltd, 1990
British Library Cataloguing in Publication Data
Steadman, Philip 1942-
Nuclear disasters and the built environment.
1. Structures. Effects of nuclear disasters
I. Title II. Hodgkinson, Simon
III. Royal Institute of British Architects
624. Γ76
ISBN 0-408-50061-1
Library of Congress Cataloging in Publication Data
Applied for.
Composition by Genesis Typesetting, Borough Green, Kent
Printed and bound in Great Britain by Courier International Ltd.,
Tiptree, Essex
Foreword
The purpose of this report is to give the reader, whether a work under the guidance of a working party consisting
member of the public or of the profession, an easily of:
understood assessment of the likely effect on the built
environment of nuclear disasters arising either from a Sir Alex Gordon CBE, Past President RIBA,
nuclear accident or a nuclear attack. Matters related to architect in private practice (Chairman).
nuclear developments, whether for civil or military use,
Miss Nadine Beddington MBE, Former Vice
are inevitably controversial and the necessity of main-
President RIBA, architect in private practice.
taining objectivity in the preparation of the report has
been accepted as being of paramount importance. Professor Ted Happold, Hon. Fellow RIBA, Joint
Head, School of Architecture and Building Engineer-
Although those who have been involved with the study ing, University of Bath, and structural engineer.
obviously have their own views it was no part of their
Miss Kate Macintosh MBE, Former Vice President
terms of reference to consider the desirability or
RIBA, architect with Hampshire County Council.
otherwise of stockpiling nuclear weapons or constructing
nuclear power stations. Both of these already exist and it Mr Charles Thomson, Partner Rock Townsend,
is responsible and prudent for the Institute to summarise architect in private practice.
available evidence as to the implications of nuclear
disasters, and their bearing on the profession's specialist The report was completed in July 1988 and received with
sphere of activity. a view to publication by the RIBA Council in that same
month. Since this is a fast-changing field some minor
In 1983 the British Medical Association published a changes have been made in November 1989 to update
report The Medical Effects of Nuclear War, which examined the text for publication.
the likely effects of nuclear attack upon Britain's
population and the implications for the provision of The available resources made it possible to collate and
medical services. It was soon felt by many in the synthesise the findings of a large number of other studies,
architectural profession that the possibility of a similarly and to provide a review of the existing state of
objective and dispassionate exercise to be carried out by knowledge. A further study of a different nature and
the RIBA, with reference to the effects on the built using considerably more resources would be necessary to
environment, should be investigated. A pilot study group define what initiatives of an architectural character are
was set up and recommended to the Council of the RIBA appropriate in anticipation of and in the event of a
that such a study should be undertaken. It was decided disaster. Nevertheless the Working Party trusts that
to broaden the terms of reference to 'nuclear disasters', readers of this report will find that it provides a
thus encompassing the effects arising from nuclear convenient and readable introduction to a subject which,
accidents in civil installations, such as that at Chernobyl. however depressing, is of the greatest potential import-
ance for the future of our buildings and cities.
After preliminary considerations within the Institute the
Nuclear Working Group was formally established in July We are grateful to Mark Barrett, Michael Flood, John
1986 with the following terms of reference: Large, David Lowry and Hugh Miall for reading and
commenting on the manuscript; and to the staff of the
'To examine available evidence on the effects on the many institutions and libraries which provided informa-
built environment of nuclear disasters and to report.' tion and publications, especially the Open University
Library, the National Radiological Protection Board, the
The study was financed by an allocation of £8000 from Property Services Agency of the Department of Environ-
RIBA funds and a further £5000 in the form of grant ment, and the Home Office Scientific Research and
from the Joseph Rowntree Charitable Trust. Philip Development Branch.
Steadman, MA ScD of the Open University and Simon
Hodgkinson, BSc AA Grad Dip M Phil of Earth
Resources Research were commissioned to undertake the Sir Alex Gordon, Chairman
VI
A driverless bulldozer, controlled remotely by an operator in an armoured vehicle, clears contaminated soil near the
Chernobyl reactor site in June 1986
A military helicopter delivers a polymer spray near Chernobyl, to attach radioactive particles to leaves and grass and
prevent them from being blown or washed further away
CHAPTER 1 3
Introduction
Hiroshima 1945 These descriptions remind us of the devastating impact
Ί climbed Hijiyama hill and looked down. I saw that of nuclear disasters on people and on the places they
Hiroshima had disappeared...I was shocked by the inhabit. They remind us of what a great blow is struck to
sight.. . . What I felt and still feel now I just can't the survivors by the loss of familiar surroundings.
explain with words. Of course I saw many dreadful
scenes after that — but that experience, looking down There have been many books about the medical and
and finding nothing left of Hiroshima — was so shocking social consequences, both of nuclear war and nuclear
that I simply can't express what I felt. I could see Koi (a reactor accidents. There have been studies of the larger
suburb at the opposite end of the city) and a few environmental consequences of nuclear explosions, such
buildings standing. But Hiroshima didn't exist — that as the effects of global fallout and nuclear winter. The
was mainly what I saw — Hiroshima just didn't exist.' damage to buildings and cities as such has been given at
best secondary consideration. In this report we reverse
(DrM. Hachiya cited in Lifton, 1967)
that emphasis, and look at the effect of nuclear disasters
on those man-made places in which our lives are
conducted: our houses and workplaces, our streets and
Chernobyl 1986
fields.
'The First Party Secretary ofKhoiniki Raton Commit-
tee in Byelorussia, D.M. Demichev, also said that "it Of course these buildings and places are not isolated
was difficult for peasants to leave familiar places . . . entities, but together make up a complex urban
there were tears. Some old men hid in cellars . . . ". structure, connected physically by roads, wires and
Some Pripyat residents simply refused to move. Two pipes; connected socially by the ties of work, trade,
elderly women, A.S. Semeniaka and M.I. Karpenok friendship and family; connected mentally by associa-
(aged 85 and 74 respectively), hid during the evacua- tions, images and meanings. Within our villages, towns
tion and were only discovered more than a month after and cities these innumerable relationships between
the accident. Some old men found their way back to the people, buildings and activities slowly develop and
apartments — presumably from their new locations — mature over many years, over generations. Our econo-
"nobody knows how", and were discovered by a patrol. mic, social and cultural growth and creativity depend on
Upon apprehension, they reportedly protested "We will these interrelationships and their stability. While small
not leave — who will feed the geese and the chickens?" ' changes may not greatly affect the whole, the impact of a
disaster, whether man-made or natural, that severs a
(Marples, 1987)
community from its built environment can be very
dramatic, irreversibly breaking this web of connections.
Moreover, buildings are not just receptacles for human
activities. Our built environment represents the com-
bined achievements of many generations and countless
lives. It is a visual representation of our history, and
provides us with a cultural identity and a sense of
belonging to a time and place. We have a responsibility
to past and future generations for this inherited
patrimony, which the built environment represents. It is
from our sense of this responsibility that the present
study stems.
The prime purpose then is to describe the possible
consequences for our built environment of two types of
event: a nuclear accident causing a catastrophic release
of radioactivity to the atmosphere; and a nuclear attack.
We should make it clear that, despite the umbrella title
of 'nuclear disasters', the report falls into two quite
distinct parts. We do not regard the two types of event as
commensurable in the seriousness of their consequences;
and as will become clear, we believe there are several
practical precautions which are or would be useful in
4 INTRODUCTION
emergency planning for reactor accidents, whereas the problems and costs of decontamination? How much land
scope for practical civil defence plans in nuclear war is, and how many buildings might have to be evacuated as a
we believe, extremely limited. result of contamination, and for how long? What would
be the economic and social costs of long-term 'land
There are connections certainly between nuclear denial' of this kind on a large scale? What would be the
weapons and the historical origins of the civil nuclear problems of having to resettle large communities away
power programme in Britain. And there are connections from contaminated zones?
between the spread of civil nuclear technology and the
proliferation of nuclear weapons internationally. These The account of the effects of hypothetical scenarios of
are not matters that we go into here. nuclear attack reports estimates of the extent of damage
to buildings throughout the country. The questions
There are some other points at which the subjects of raised here are: What areas of Britain's cities might be
nuclear power and nuclear war touch which we do cover devastated by blast and fire? What would be the extent of
- for example we look briefly at the implications should a contamination by fallout? What protection could be
nuclear weapon be exploded on a nuclear reactor. The provided against the effects of radioactivity, heat and
principal theme that links the two subjects here, blast, either by ordinary buildings or by special-purpose
however, is the parallel threat that both kinds of disaster shelters?
pose, of radioactive contamination; and the common
problems that they raise, of protecting people from Despite the emphasis on buildings the study is
exposure to radiation. nevertheless directed towards the general public, as well
as to the architectural profession. It is not a professional
The focus is on Britain. The discussion of nuclear manual on shelter design (although this topic is certainly
accidents covers a range of civil and military nuclear treated in some depth). Nor is it a specialised treatment
installations, as well as nuclear transport arrangements, accessible only to those with extensive knowledge of the
where disasters might happen. The principal case taken nuclear power industry or nuclear weapons strategy. It is
for illustration, however, is the possibility of an accident offered as a broad analysis of the architectural dimen-
at the new pressurised water reactor (PWR) being built sions of some very complex subjects, intended to
at Sizewell in Suffolk. Possible future accidents at contribute to wider public awareness in the first place;
Continental reactors, which might affect Britain, and and perhaps beyond that to provide information as a
actual past accidents in the USA and the Soviet Union, basis for policy-making or individual action.
are also described.
Technical language is kept to a minnimum and all
In the case of nuclear attack there are brief descriptions specialised terms are fully explained. No prior knowledge
of the possible consequences of battlefield nuclear war in is assumed of nuclear physics or the nature of
the Germanies, and of intercontinental exchanges radioactivity and its biological effects; and Chapter 2
between the superpowers. The nature and extent of which follows provides a basic summary of these and
damage to buildings at Hiroshima and Nagasaki are other topics necessary to an understanding of later
reported in detail, as are the results of experiments on sections. Some readers may prefer to omit Chapter 2 and
buildings exposed to test explosions. The greater part of go directly to Part II, 'Nuclear Reactor Accidents'.
the discussion, however, is devoted to what might
happen should the Warsaw Pact use nuclear weapons
A note on units of measurement
against Britain, either in 'limited' attacks against
military sites only, or in a massive bombardment of Purists will be shocked to find in the report a
many classes of target. promiscuous mingling of units from the SI and imperial
systems. There are several reasons for this. Some of the
In both cases — reactor accidents and nuclear explosions historical discussion quotes standards that predate
- attention is focused on the consequences for buildings. metrication in Britain. There are references to historical
However, agricultural land and the natural landscape and current standards applying in the USA. Much of the
are also given consideration. literature of nuclear weapons effects is American and
uses imperial units. (The leading textbook even mea-
Thus the description of reactor accidents looks at the sures distances in 'kilofeet'!) And some SI units are still
potential extent of radioactive contamination of settle- relatively unfamiliar outside the engineering and scien-
ments and the surrounding countryside. The siting of tific worlds, and so more popular accounts preserve
nuclear installations is examined with the possibility of imperial units - as for example pressures measured in
accident in mind. A series of questions is raised. To what pounds per square inch (psi) rather than kilopascals
extent could contamination be prevented from entering (kPa). However, wherever possible and appropriate
houses? What protection would buildings offer as shelter metric units have been used, or the metric equivalents of
against radioactivity? What might be the practical imperial units noted.
CHAPTER 2 5
Nuclear Reactions and Radiation
Energy and Mass
Until this century the laws of Newtonian physics seemed
to explain very well the nature of mass and energy and
the relationships between them. These laws presupposed
that mass and energy were separate entities. Energy
provided the means by which matter could be moved,
heated and transformed. The amounts of mass and
energy in the universe were both taken to be forever
constant whatever transformation each might undergo.
However, when scientists this century began to probe
deeper into questions of energy, mass, time and space it Figure 2.1 Atoms (a) A hydrogen atom, atomic mass 2: 1 proton, 1
neutron, 1 electron, (b) An atom of uranium-238, atomic mass 238: 92
became apparent that whilst Newton's laws held with
protons, 146 neutrons, 92 electrons
fair accuracy for most phenomena, they were inadequate
for others. As Albert Einstein discovered, mass and
energy were not separate, but interchangeable entities. called isotopes, and are identified by the sum of their
Contrary to appearances matter was in fact full of an protons and neutrons. The two isotopes of uranium are
energy of unimaginable ferocity - the energy that held hence known as uranium-238 (92 protons plus 146
the nucleus of the atom together - an energy that under neutrons) and uranium-235 (92 protons plus 143
normal conditions was locked in the sub-atomic realm, neutrons). Atoms thus characterised are called nuc-
and which had therefore never been apparent. As lides.
Einstein said, 'It was as though a man who is fabulously
rich, should never spend or give away a cent. No one Nuclear Energy
could tell how rich he was'. In order to appreciate the
true nature and significance of Einstein's discovery it is Some nuclides are stable, and do not change. Others,
necessary to understand the structure of matter and the indeed most, are unstable, and disintegrate at different
types of forces contained in the atom. rates, some slow, some very rapid, depending on the
nuclide. To understand their instability we must look at
the forces that hold the atom together.
The Element, the Atom, and the Isotope
All naturally occurring substances on earth are made There are two main types of force.
from one or more of some 90 elements. These elements
may be gases (like oxygen and hydrogen), non-metals The first of these is electrostatic. Electrons carry a
(like carbon and sulphur), or metals (like iron, zinc or negative charge of electricity, and protons carry a
uranium). The basic unit of an element is the atom — a positive charge, while neutrons carry no charge at all. In
split atom of zinc does not retain the properties of zinc. normal atoms the opposing electrical charges are of
equal magnitude so that the atom as a whole is
One can imagine the atom as made up of a nucleus electrically neutral in relation to its surroundings.
around which orbit electrons. The nucleus is very However, internally to the atom the charges create a
compact and dense, accounting for almost all of the mass magnetic attraction between the electrons and the
of the atom, but for only one hundred thousandth of its protons which keeps the former in their orbit around the
volume. The nucleus contains protons and neutrons. The nucleus, in something of the same way that gravity keeps
number of protons, the so-called atomic number, the planets in their orbits around the sun.
distinguishes which element the atom belongs to; thus
hydrogen is the lightest atom with just one proton, The second force contained in the atom is the nuclear
oxygen has eight, whereas uranium and plutonium are force. Given that like electrical charges repel each other,
the heaviest atoms with 92 and 94 protons respectively one would expect the tightly packed protons in the
(Figure 2.1). nucleus of the atom to fly violently apart. The reason
that they do not generally do this is that within the
Although all atoms of a given element have the same nucleus there exists an immensely strong short-range
number of protons, they may not all have the same force cementing the neutrons and the protons together.
number of neutrons. While over 99% of naturally
occurring uranium atoms have 146 neutrons, a very As the nuclei of the atoms of most elements have the
small proportion, around 0.7%, have 143 neutrons. right balance of protons and neutrons, they are strongly
Different varieties of nuclei of the same element are bonded together and stable. However, in many nuclei,
6 NUCLEAR REACTIONS AND RADIATION
particularly those containing more than 83 protons, the
strong repulsive force between the protons is on the point • · ·
+
of overcoming the nuclear force. Such atoms are liable to
ft
transform themselves spontaneously or decay. In so m+
doing they become changed into atoms of different
e_-^—
elements, and may release electromagnetic radiation and
sub-atomic particles travelling at high speeds. Atoms
that disintegrate in this way are called radioactive, and
their nuclei are termed radionuclides. The atoms of the
new elements produced in these decay processes may
themselves be radioactive, and decay in their turn - or
they may be stable. Figure 2.3 The fission fragments weigh less than the original nucleus
We are concerned here with the three main types of E = mc2
radiation given off by radioactive atoms as they decay,
termed alpha, beta and gamma radiation. Alpha decay or Energy = Mass times the speed of light squared.
occurs only in a few heavy elements such as uranium,
radium and plutonium. The alpha particles which The speed of light is 300 000 kilometres/second, and so
make up the alpha radiation are identical with the nuclei even the conversion of very small amounts of matter can
of helium atoms, and consist each of two protons and two release enormous amounts of energy. In fact weight-for-
neutrons. Alpha radiation travels at around 15 000 weight, nuclear reactions release around 16 million times
kilometres/second, or one-twentieth of the speed of light. more energy than chemical ones. Given the enormously
greater energy potential of nuclear as compared with
The majority of radioactive elements undergo beta
chemical reactions, it is hardly surprising that scientists
decay. Beta particles are electrons moving very fast,
and weapons designers soon set their minds to finding
around nine-tenths of the speed of light. Finally, gamma
ways of releasing this potential for civil and military
radiation is electromagnetic radiation of the same
purposes.
general nature as X-rays or light, and hence travels at
the speed of light. The nature of radioactivity and its
Induced Fission, Critical Mass and the
biological effects are described in more detail below. For
the moment it is necessary to turn to another aspect of Chain Reaction
the decay process - the energy it releases.
Although a small amount of mass can yield a large
amount of energy, the atom of course is very small, and
When, for example, a uranium-238 nucleus, with its 92
so a great many nuclei must split or undergo fission
protons, undergoes alpha decay - an event that is quite
reactions to yield useful quantities of energy. The rate at
unpredictable and may occur after a fraction of a second
which fission reactions occur naturally in radioactive
or after millions of years - it splits into two large
substances is not sufficient for most practical purposes.
fragments plus several isolated neutrons, and ejects a
To generate significant quantities of heat from nuclear
very energetic and fast-moving alpha particle (Figure
fission, scientists thus needed to find a way of generating
2.2). The alpha particle is rapidly slowed down as it hits
enormous numbers of fission reactions very rapidly.
other atoms, and in so doing it converts its kinetic energy
into heat. But how was so much energy imparted to the
It took scientists 33 years from Einstein's discovery in
alpha particle in the first place?
1905 to find a way of doing this. In 1938 two Austrian
physicists, Lise Meitner and Otto Frisch, correctly
stray neutrons. suggested that one could induce a fission reaction in a
t uranium-235 nucleus by hitting it with a neutron. When
this happens typically two-fifths of the atom flies in one
direction to form an atom of strontium-90 (which is itself
radioactive), three-fifths in the opposite direction to form
irSS^ -v(T)^« alpha particle
an atom of xenon gas, with two or three stray neutrons
also being ejected (Figure 2.4).
unstable U-238 nucleus f ^^ ^.
decays into thorium-234 "*" φ
Figure 2.2 Spontaneous decay of uranium-238 stray neutron · strontium-90
If one were to weigh up all the separate fragments and
particles one would find that their total weight was very
slightly less than the weight of the original atom (Figure
2.3). This is because a part of the mass of the original
atom has been converted into energy. Φ ♦ ΟΟτίΠ ·" · stray neutron
neutron enters ^ S £^ ~ s-
The cause öf this conversion of mass to energy is the U-235 nucleus ^ v-.x
basic law of physics, that the conversion of any system in
which the constituents are held together by weaker forces (ΡΟ"ΓΣ> xenon-132
into one in which the forces are stronger is accompanied
by a release of energy and a corresponding decrease in
mass. This equivalence of energy with mass is expressed stray neutron #
in Einstein's famous formula: Figure 2.4 Induced fission
THE NUCLEAR REACTOR 7
It was the stray neutrons emitted as a by-product of such
a reaction that became the key to understanding how to
release useful quantities of nuclear energy. Scientists
realised that if at least one of the stray neutrons from the
original fission reaction was to go on to fission a further
uranium-235 nucleus, and one from the second-
generation fission was to go on to induce a third-
generation fission, and so on, the result would be a
self-sustaining chain-reaction of fissions (Figure 2.5).
time
(microseconds)
Figure 2.6 Critical mass. As the mass of fissile material is increased, fewer
neutrons are lost by escape, until the critical mass is reached, where the
chain-reaction is self-sustaining. Source: Glasstone and Dolan (1977)
escape
neutron-absorbing
generation. Multiplying this by the number of fission
.02- nucleus
generations per second, we can see that very significant
amounts of energy can in this way be released at a
controlled rate. Very crudely speaking this is how a
chain reaction is used in a nuclear reactor to generate
escape heat, which is in turn used to drive turbines and so
.04 -A
generate electricity.
A nuclear reactor (Figure 2.7) is designed to provide
large quantities of energy over a long period. For this
reason many tons of fissile fuel are used. This fuel is
Shielding Control rods
Steam to
l· turbine to
Figure 2.5 A controlled chain reaction. On average each fission produces produce
just enough neutrons to cause one further fission (the critical case). Source: electricity
Open University (1986)
L· < Water
Despite the fact that stray neutrons are for a variety of μ intake
reasons constantly present in our environment (e.g.
cosmic rays from the sun contain stray neutrons) it is
extremely rare for chain reactions to happen spon-
taneously on earth. The reason is that usually fissile Pressure
materials like uranium occur naturally in such low vessel
concentrations that the neutron by-products of a Reactor core Passage
spontaneous fission reaction become absorbed by other Uranium fuel
types of nuclei, and therefore do not have a chance to
Figure 2.7 Schematic diagram of a nuclear power station
cause second-generation fission reactions.
formed into many dozens of fuel rods, clad in metal
If an increasingly large, compact, pure sample of fissile
tubes which support the fuel and confine the fission
material is amassed, however, the proportion of neutrons
products. The rods are inserted in a set pattern into the
that succeed in inducing further fissions increases. A
reactor core. This core contains a moderator, such as
point is reached when the sample is of a sufficient mass
water, which slows down the neutrons - slow neutrons
that on average one neutron from each generation goes
tend to be more effective at inducing fission than fast
on successfully to generate at least one other fission, thus
creating a chain-reaction. This mass is called the critical ones.
mass for that material (Figure 2.6). For a solid sphere of
uranium-235 the critical mass is around 50 kilograms. The core also contains control rods made up of material
like boron, which absorbs neutrons. These control rods
can be used to prevent a chain reaction occurring in a
The Nuclear Reactor
mass of fissile material that would otherwise be critical.
Because the time lapse between fission generations in a To start up the reactor the control rods are slowly
chain reaction is extremely small, of the order of one withdrawn in a careful symmetry. This allows a build-up
fiftieth of a millionth of a second, the build-up of fission of neutrons to occur, until at a certain point the reactor
generations takes very little time. A controlled chain 'goes critical', and a self-sustaining chain reaction is
reaction in a critical mass of fissile material will of course established. At this point the reactor starts producing
involve millions upon millions of reactions per fission large quantities of heat, which is transferred to a coolant