4. A device for producing an elecnomotive force

and delivering an elecnic current as the result

of a chemical reaction.

13) Titles.- Nuclear Fuel; Nuclear Power; Nuclear Reaction.

l. A substance which undergoes nuclear fission or

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2. Any reaction which involves a change in the

nucleus of an atom, as distinct born a chemical reaction which only involves the orbital elec- trons. Such reactions occur naturally — on the Earth, in radioactive elements, and in the stars, as thermonuclear reactions. They are also pro- duced in nuclear reactors, and nuclear weapons.

3. Electric or motive power produced from a unit

in which the primary energy source is a nuclear

reactor.

14) Titles. Pressured-Water Reactor (PWR); Boiling-Watur Reactor (BWR).

1. This is a pressure-vessel reactor fuelled with

enriched uranium. The reactor is a thermal one,

moderated and cooled with ordinary (light)

water. The heat in the reactor is extracted by the boiling water as it passes through the core, and the steam is passed directly to the turbine of the energy conversion cycle.

2. The primary reactor vessel of this reactor is op-

erated at considerable overpressure, which sup-

presses boiling of the cooling water.

15) Titles. Nuclear Fusion; Nuclear Fission; Nuclear Charge; Nuclear En-

l. Energy released during a nuclear reaction as the

result of the convemion of mass into energy. Energy of this kind is released in nuclear reac- tors and nuclear weapons.

2. A reaction between light atomic nuclei as a re-

sult of which a heavier nucleus is formed and a

large quantity of nuclear energy is released.

The temperatures necessary for fusion reactions are extremely high. Reactions of this kind are believed to be the source of the energy of the stars (including the Sun).

3. A nuclear reaction in which a heavy atomic nu-

cleus (e.g. uranium) splits into two approxim-

ately equal parts, at the same time emitting neutrons and releasing very large amounts of nuclear energy.

4. The positive elecnic charge on the nucleus of

an atom. Numerically it is equal to the atomic number of the element, to the number of pro-

tons in the nucleus, and to the number of elec- nons surrounding the nucleus in the neutral atom.

Id) Rules: Analog Computer; Computer; Digital Computer; Central Processing Unit.

1. The cennal electronic unit in a computer which

processes input information, and information from the store, and produces the output infor- mation. This unit and the store form the central part of the computer.

2. A computer in which numerical magnitudes arc

represented by physical quantities such as

elecnic current, voltage, or resistance.

^{An electronic device which accents data, ap-}

plies a series of logical processes to it, and sup- plies the results of these processes as infor- mation. The device is used to perform mathe- matical calculations at a very high speed. This makes them useful for various purposes, such as office calculations, comet of industrial processes, and the connol of flight paths.

4. A computer which operates on data in the form

of digits rather than the physical quantities.