Chain Reaction
Page 23
‘No, thank God. But Dick’s leg will be in plaster for a while.’ She smiled reminiscently. ‘He gets very cross about it.’
‘Huh. I would, too.’ He put a match to his pipe. ‘What’s he going to do? Is he staying with the Department?’
‘Yes. He’s staying on as Lord Amberton’s P.A.’
The Times went up again, and Sir Horace finished the conversation from behind it. ‘Well, I hope Lord Amberton absorbs all Dick’s nuclear energy until you two have got things settled. They may talk about mutations, but there’s one thing you can’t change.’
Her face caught the firelight as she smiled. ‘Who wants to?’ she said.
A great column of smoke rose from behind The Times and mushroomed out into a cloud.
Sophie went to the telephone and called a Radiocab.
‘Where will you want to go to, please?’ said the girl at the other end.
‘Bart’s Hospital,’ said Sophie.
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GLOSSARY OF TECHNICAL TERMS
ALPHA RAYS. Positively charged panicles emitted from some radioactive matter. They originate from the nuclei of atoms, and each particle consists of two protons and two neutrons (i.e. helium nuclei). Can only penetrate matter to a depth of a few thousandths of an inch.
ANAEMIA. A disorder resulting from an insufficiency of certain blood cells that can be caused by radiation.
ARTIFICIAL NEUTRON SOURCE. An apparatus containing radium and beryllium. It is used for the purpose of emitting free neutrons. In a reactor it is this initial supply of neutrons that start it working.
ATOM. The smallest unit in which matter can exist permanently. Atoms seldom, however, exist in their isolated state, but combine to form molecules.
BACKGROUND COUNT. The count recorded on a geiger counter that originates from cosmic rays and other natural sources. It always exists, and life is adjusted to this small degree of radiation.
BETA RAYS. Negatively charged particles emitted from the nucleus of some radioactive substances. They are, in fact, high speed electrons. Can penetrate a thin sheer of cardboard.
CAESIUM-137. A radioactive isotope of caesium that emits gamma rays and beta particles. When eaten, spreads more or less uniformly throughout the body, and is eventually removed by sweating, etc.
CARBON DIOXIDE. A gas used in many reactors to cool them, and to transfer the resulting heat to the heat-exchangers whereby steam can be made. In this case the gas is known as the coolant.
CELL DIVISION. The process by which living cells multiply. The cells divide in half periodically, and thus rapidly increase their population. (See Genetic Effect.)
CHAIN REACTION A multiple fission process resulting from the fact that when a fissionable substance (such as uranium-235) is bombarded by neutrons, it emits at least two more neutrons which in turn bombard other atoms of the fissionable material.
COBALT-60. An isotope of cobalt with an atomic weight of 60 emitting gamma rays; also emits beta particles.
CONTROL ROD. A rod containing boron which can absorb neutrons and therefore slow down a chain reaction. If sufficient neutrons can be absorbed by a number of controls rods, the reactor will cease to function.
COOLANT. (See Carbon Dioxide.)
CRITICAL MASS. The minimum size of a reactor below which a chain reaction could not take place because there would be insufficient neutrons to go round.
DECAY. All radioactive matter decays at a certain rate and changes its nature thereby. The elements continue to decay until they reach a stable condition. For instance, uranium decays until it becomes lead. (See Half-life.)
DOSE RATE. The rate at which the ‘whole body’ of a human being or animal is irradiated. Expressed in this book in roentgens (per hour). The lethal dose in one single irradiation is anything upwards from 300 roentgens.
ELECTRON. A very small negatively charged particle. Normally electrons rotate round the nucleus of an atom. The electrons are spaced out in a series of one or more rings or ‘shells’. The number of electrons normally equals the number of protons within the nucleus, thus maintaining an electrical balance. If they do not, the atom is said to be ionised. (See Ionisation.)
ELECTROSCOPE. A simple apparatus which indicates an electrostatic charge on an object. Radiation discharges an electroscope.
ENRICHED URANIUM. Uranium containing a greater proportion of the isotope-235 than exists in nature.
FALL-OUT. Radioactive particles, originating from atomic bomb explosions, which descend to the earth from the atmosphere.
FISSION. The process of breaking up complex atoms into two or more lighter substances resulting from bombardment of the nucleus by neutrons.
FISSION PRODUCT The substances that result from the breaking up of a complex atom such as uranium. Fission products (for instance, iodine-131, strontium-90 and caesium-137) are highly radioactive.
FUEL CARTRIDGE. A rod of uranium contained within a magnesium tube. Also known as a slug or fuel rod. The fuel is the basic component of a reactor.
FUEL HOLES. The holes in the graphite block into which the fuel cartridges are inserted.
FUEL RODS. (See Fuel Cartridge.)
GAMMA RAYS. Electro-magnetic waves similar to X-rays, of high penetration, emitted in nature by some radioactive substances.
GEIGER COUNTER. An instrument capable of detecting radiation, may be calibrated in roentgens per hour or one of several other systems.
GENETIC EFFECT. The effect of radiation on future generations shown in the form of mutation.
HALF-LIFE. The length of time taken by a radioactive substance to reduce its level of radioactivity by half. (See Decay.)
HEAT-EXCHANGER. An apparatus wherein hot gases (or in some cases liquids) can be made to heat water without coming into contact with it so as to make steam.
IONISATION. Radiation tends to ionise atoms in its path. (See Electron.) Such ‘ions’ so formed tend to be chemically highly active. If the human body is irradiated, accordingly its chemistry will be changed. (See Radiation Sickness.)
IRRADIATION. The process of being subjected to radiation.
ISOTOPES. Atoms of one element, though identical chemically, may differ in their atomic weight, due to the difference in the number of neutrons contained in the nucleus. Natural uranium, for instance, exists as a mixture of uranium-235 and -238, indicating that there are three additional neutrons in the latter.
LEUKAEMIA. A disease of the blood cells sometimes caused by radiation.
LIFETIME DOSE. The safe dose calculated to be irradiated gradually over the entire working life of a human being.
MEGA-WATT. One million watts. The unit normally used to measure the heat output of a reactor as an expression of the equivalent amount of electric power that can theoretically be generated by it.
MODERATOR. When natural uranium is used in a reactor, it is necessary to bias the flow of neutrons in favour of the uranium-235 content (see Isotopes) as it is the -235 that is fissionable. This can be done by slowing down the neutrons, and the device used is called a moderator. When made of carbon, it is known as the ‘graphite block’.
MOLECULE. Atoms do not normally exist on their own as free atoms, but combine in groups of two or more. These groups are known as molecules.
MUTATION. The process of unnatural change in a life cell which causes disfigurement in the developed embryo. Mutation can only take place if the original cell is affected before division. (See Genetic Effect.)
NEUTRON. An uncharged particle of about the same weight as a proton which is highly penetrating when emitted. (See Chain Reaction.)
NUCLEUS. The core of an atom. The smallest possible nucleus (that of hydrogen) consists of one proton. The addition of further protons decides which element the atom comprises. The addition of neutrons does not change it i
nto another substance, but merely makes it heavier. It is the nucleus of an atom which the flying neutron has to hit in order to cause fission.
PERIODIC TABLE. The table of elements set out in progression relative to the number of protons in the nuclei of their atoms. Thus hydrogen (1 proton) is No. 1 and uranium (92 protons) is No. 92. It is called ‘periodic’ because there is a tendency for elements of similar characteristics to fall at regular intervals throughout the table.
PILE. (See Reactor.)
PROTON. A positively charged particle normally within the nucleus of an atom.
RADIATION. The emitting rays of any or all ionising rays. It is usually taken to include neutrons as well, which indirectly cause ionisation through interaction with other substances in the path of the travelling neutron.
RADIATION SICKNESS. A disorder due to irradiation. It begins with vomiting and other symptoms. An inert period will follow before more dangerous effects become apparent.
REACTOR. An apparatus designed to permit a chain reaction that is capable of being controlled so as to produce continuous energy in the form of heat.
ROENTGEN. A unit used to measure radiation. It is named after the discoverer of X-rays. (See Dose Rate.)
SHIELDING. A thick layer of material (usually of concrete) placed round a reactor in order to prevent the irradiation of persons working near at hand. Sometimes called the biological shield. Water is also an effective shield.
STABLE. The state which matter is said to be in when it is not liable to change into something else.
STRONTIUM-90. A radioactive isotope of strontium that emits beta particles. When eaten, goes mostly to the bone and behaves chemically like calcium.
URANIUM (NATURAL). Natural uranium is used in most reactors and consists of 0.7% U-235 and 99.3% U-238. A chain reaction is made possible, using natural uranium, by slowing down free neutrons by means of a moderator so that more neutrons are absorbed by the U-235 rather than by the U-238.
URANIUM-235. An isotope of uranium which, when bombarded, releases more neutrons than it receives. The figure 235 denotes its atomic weight made up of 92 protons and 143 neutrons.
URANIUM-238. An isotope of uranium that when bombarded by neutrons breeds plutonium.
X-HOLES. The holes in the graphite block (moderator) into which the control rods are inserted.
X-RAYS. Artificially created electro-magnetic rays, identical with gamma rays but usually of longer wavelength.