ML19308C130

Nuclear Terms-Glossary

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Issue date:	12/31/1967
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FOREWORD Terms defined ir. this glossary are among those com-monly used in nuclsar science and its applications. Some also are in common usage or apply in other specialized areas of science and technology. When this is the case, the definitions givers are those which have special meaning in nuclear fields. urless otherwtse indicated.

This glossary is intended for persons who are not spe-cialists in the FJbject matter of atomic energy. Some defi-nations may for that reason fall short of technical precision or completeners. A reference list on page 66 includes other glossaries anr*, detailed sources of information.

For cross references, italic type is used. Defimtions that employ or r efer the reader to synonymous, parallel, simi-lar, or related terms defined elsewhere in this glossary show such terms in stalres. Enmple:

dry, critical ty Reactor criticality a hieved without a coolant. (Compare wet crsticality; see ersticalsty.)

Definitions expressed wholly or largely in terms denned elsewhere in this glossary also are set irricalics. Example:

A-bomb An atomic 'bom6.

In defimtions that mention related generalorcollec%vesub.

ject areas. defined in this glossary, which are aot neces-sarily synonymous to or parallel with the term betag de-fined, but which may contribute understanding, these broad subject areas are printed in CAPITAL ITAllCS. Example:

scintillation A flash of light produced byaphosphor ta an 10NIZING EVENT.

The Appendix beginning on page 67 includes prefixes, units of measurement. constants, abbreviations, a Periodic Table and List of the Elements, tables of isotopes of some of the elements. principal fission products, and the four radioactive decay series.

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9 HOW THIS GLOSSARY WAS WRITTEN This edition of " Nuclear Terms: A Brief Glossary" is an outgrowth of an earlier edition compiled by James D. Lyman of the Atomic Energy Commission Division of Public Information, who also served as its co-editor. Mr. Lyman years earlier had started a card nie of definitions of nuclear terms to assist him in his work of answering inquiries from news.

men. The Die grew to impressive proportions and proved so useful that others asked for copies.

The card file, somewhat enlarged, carefully edited, revised and reviewed by authorities both within and outside the Atomic Energy Commission, appeared in April 1964, as the Brat edition of this booklet. It proved to be one of the most popular of the "Under-standing the Atom" series. More than 118,000 copies were distributed.

Numerous suggestions were made that the list of terms be enlarged. This has now been done. Mr. Ly-man's original list contained 385 terms. The present volume contains 640. Moreover, the complete list has been reviewed anew by those who contributed to the Brat edition as well as by additional specialists.

Principal reviewers and contributors from outside the AEC were William R. Corliss, nuclear engineer, consultant and writer; Dr. John F. Hogetton, nuclear consultant and author of The Atomic Energy Desh-book: Dr. Samuel Glasstone, author of Sourcebook on Atomac Enerb/ and many other technical volumes; and Dr. Charles W. $ hilling, editor and principaleon-tributor to The Atomic Energy Encyclopedia sn the Life Sciences.

Many members of the AEC staff also contributed extensively to this edition, particularly Dr. Walter D.

Claus, formerly with the Division of Biology and Medicine, and Dr. Benjamin S. Loeb, Diviston of Technical Information. Dr. John H. Pomeroy for-merly with the AEC Division of Research was the technical editor. Harold F. Osborne formerly with the Division of Technical Information was editorial supervisor.

The complete list of terms in the first edition was edited and revised as necessary. In addition, by in-creased cross. referencing (see Foreword), simitse and related terms were linked to provide greater utility and increase understanding.

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NUCLEAR TERMS A GLOSSARY Second Edition O

A symbol for mass number.

A bomb An atomac bomb.

absorbed dose Whenl0N! ZING RADIATION passes through MATTER, some of its energy is imparted to the matter. The amount absorbed per unit mass of irradiated mate.

rial is called the absorbed dose, and is measured in rems and rads. (See threshold dose.),

absorber Any matertal that absorbs or <timtat=hes the intensity of ionizing RADIATION. Neutron absorbers, like bo-ron. hafnium, and cadmium, are used in control rods for reactors. Concrete and steel absorb gamma rays and neutrons in reactor shields. A thin sheet of paper or metal will absorb or attenuate alpha particles and all except the most energetic beta particles. (Com-pare moderator; see posson )

absorption The process by which the number of particles or photons entering a body of MATTER is reduced by interaction of the particles or radiation with the matter; similarly, the reduction of the energy of a particle while traversing a body of matter. This term is sometimes erroneously used for capture. (Com-pare capture; ree stoppsng power.)

accelerator A device for increasing the velocity and energy of charged El.EMENTARY PARTICLES, for example, electrons or protons, through application of elec-

. trical and/or magnetic forces. Accelerators have made particles move at velocities approaching the speed of light. Types of accelerators include beta-trans. Cockcroft-Walton accelerators, cyclotrons, linear accelerators, synchrocyclotrons, synchrotrons, and Van de Graaff generators.

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actinide series The series of elements h==4aaia-with actinium, Ele-ment No. 89, and continuing through lawrendum, Ele-ment No.103, winch together occupy one positior.in the Periodic Table. The series includes uranium, Element No. 92, and au the man-made transuranic elements. The group is also referred to as the "Ac-tinides". (Compare latkneide series, trasuranic elements.) (See Appendiz.)

actinium series The series of nucudos resulting from the radioactive (sequence) decay of uranium-235. Many man-made nuendes de-i cay into this sequence. The end product of this so-quence in nature is lead-207. (See decay, radioactive, l

radioactive series.) (See Appendix.)

I activation The process of mairing a material radioactive by l

I bombardment with neutrons, protons, or other cu-

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clear particles. Also caued radsoactivation. (See ac-tivation analysis. induced radioactivity.)

l activation analysis A method for identifying and measuring chemicalele-monts in si sample of material. The sample is first j

tr.ade radioactive tt ombardment with neutrons, charged particles, or gam rays. Tha newly formed radioactive atoms in the sample then give off charac-e teristic nuclear radiations (such as gamma rays) that

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teu what kinds of atoms are present and how many.

Activation analysis is usually more sensitive than i

i chemical analysis. It is used in research, industry, archeology, and criminology.

I activity radioactisity. (See spectfic activity.)

AEC The U. S. Atomic Energy Commission.

aftercooling The cooling of a reactor after it has been stant down.

afterheat The heat produced by the continuing decay of radio-active atoms in a reactor after fission has stopped.

Most of the afterheat is due to the radioactive decay of fission products.

air sampling The conection and analysis of samples of air to mea-sure its radioactivity or to detect the presence of ra-dioactive substances. (See fallout.)

allobar A form of an element differinginisotopic compost-tion, having a different average atomic weight from the usual:y occurring form. (See isotope.)

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alpha particle [Symbola (alpha)} A posiuvely chargedparticiaemit-ted by certain radioactive materials. It is made up of two r.eutrons and two protons beand together, bence is identical with the nucleus of a helium atom. It is the least penetrating of the three common types of radiation (alpha, beta, gamma) emitted by radioactive material being stopped by a sheet of paper. It is not dangerous to plants, acimals or man unless the alpha-emitting substance has entered the body. (See decay, radioactive.)

alpha ray A stream of alpha particles. Leonely, a synonym fcr alpha particle.

angstrom [Symbot 1 or C A unit of lengt.5. sed in measuring electromagnetic radiation, M! tr 10*8 centimetei.

Named for A. J. Angstrom, Swedisa epectroscopist.

(See Appendix.)

annihilation (see antimatter.)

antimatter Matter in which the ordinary nuclear particles (neu-iantiparticles) trons, protons, electrons, etc.) are conceived of as being replaced by their corresponding antiparticles (antineutrons, antiprotons, positrons, etc.). An anti-hydrogen atom, for example, would consist of a nega-tively charged antiproton with an orbital positron.

Normal matter and antimatter would mumally annihi-late each other upon contact, being converted totally into energy. (Compare matter.)

atom A particle of matter indivisible by chemical means.

It is the MMmental but. ding block of the chemical elements. The elements, such as iron, lead, and sul-fur, differ from each other because they contain dif-

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forent k1Ma of atoms. There are about six sextillion 22 (6 followed by 21 zeros, or 6 x 10 ) atoms in an ordinat7 drop of water. According topresent-day the-ory, an atom contains a dense innercore (the nucleus) and a much less dense outer domain consisting of electrons in motion around the nucleus. Atoms are electrically neutral. (Compare element, ion, mole-cute; see matter.)

atom smasher An accelerator.

atomic battery A radioisotopic generator, atomic bomb A bomb whose energy comes from the/issionoi heavy elements, such as uranium or plutonmm. (Compare hydrogen bomb.)

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atomic clock A device that uses the estremely fast vibrances of molecules or atomic nuclei to measure time. These vibrations remain constant with time, consequently short intervals can be measured with much higher precision than by mechanical or electrical clocks.

(Compare radsoactssie dating.)

atomic cloud The cloud of hot gases, smoke, dust, andother matter that is carried aloft after the esplosion of a nuclear weapon in the air or near the surface. The cloud fre.

quently has a mushroom shape. (See fareball, rodso.

actsre cloud.)

atomic energy nuclear energy.

Atomic Energy [Abbrettation AEC] The adopendent emlian agency Commiss6on of the federal government with statutory responsaull-ity for atomic energy matters. Also the body of five persons, appointed by the President, to direct the

agency, atomic mass (See atomse weight, mass.)

atomic mass unit [ Symbol amu] One. twelfth the mass of a neutral atom of the most aNadant isotope of carbon, t:C. (See ato>nse wesght. mass number.)

atomic number [3ymbol Z] The number of protons in the nucleus of an atom, and also its positive charge. Each chemical element has its characteristic atomic number, and the atomic numbers of the known elements form a complete series from 1 (hydrogen) to 103 (lawren.

clum). (Compare atomse wasght, mass numbert see element, isotope, Pernodse Table.)

atomic reactor A nuclear reactor.

atomic weapon An explosive weapon in which the energy is pro.

duced by auclearftssson orfusson. (Compare dettre, nuclear.)

atomic Weight The mass of an atom relat49e to other atoms. The present. day basis of the scale of atomic weights is carbon; the enmmanest isotope of this element has arbitrarily been assigned an atomic weight of 12. The unit of the a: ale is '/: the weight of the carbon.12 atom, or roughly the mass of one proton or one neu.

tron. The atomic weight of any element is approx 1 mately equal to the total number of protons and neu.

trons La its nucleus. (Compare atomsc numbert see atomse mass weit, Pernodse Table >

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autoradiograph A photographic record af radiation trem radioactive material in an object, made by placing the object very close to a photcgraptLic film or emulsion. The process is called autoradiography. It is used, for insunce, to locate radioactive atoms or tracers in metallic or biologic al samples. (Compare ra-diography.)

O background backenund radiation.

background The radiation in man's natural environment, including radiation cosmic rays and radiation from the naturally radio-active elements, both outside and inside the bodies of men and animals. It is also called natural radiation.

The term may also mean radiation thatis unrelated to a specific experiment. (See cosmic rays.)

backscatter when radiation of any kind strikes matter (gas, liquid or solid), some of it may be reflected or scattered back in the general direction of the source. An un-derstandir.g or exact measurement of the amcunt of backscatter is important when beta particles are be-ing counted in an ionization chamber, in medical treatment with radiation, or in use of industrial ra-dioisotopic thickness gauges. (See gauging.)

barn [Symbot b] A unit area used in exprusing the cross sections of atoms, nuclei, electrons, and other par-ticles. One barn is equal to 10* square centimeter.

Jee cross section.) (See Appendix.)

barricade shield A type of movable shleid for protection from radia.

tion. (See shield.)

barrier shield A wall of enclosure shielding the operator from an area where radioactive material is being used or processed-l'y remote control equipment. (See shield.)

baryon one of a class of heavy elementary particles that includes hyperons, neutrons and protons. (Compare lepton, meson.)

beam A stream of particles or electromagnetic radiation, going in a single direction.

beam hole An opening through a reactor shield and. generally, through the reactor reflector, which permits a beam of radioactive particles or radiation to be used for experiments outside the reactor, b

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beta particle [ symbol 3 (beta)] An elementary particleemittedfrces a smcleus during radioactive decay, with a sigle 8

electrical charge and a mass equal to /ger that of a protos. A 'egatively charged beta particle is iden-t1 cal to an electros. A positively charged beta par-ticle is c Hed a postfrom. Beta radiation may cause skin burns, and beta-emitters are harmful if they enter the body. Beta particles are easily stopped by a thin sheet of metal, however. (See decay, radio-active.)

betatron A doughnut-shaped accelerator in which electrons,.

traveling in an ortit of constant r&dius, are acceler=

ated by a changing magnetic field. Energies as high as 340 Mev have been attained. (See accelerstor.)

i Bev symbol for billion (or 109 electron volts. Alsowritten as BeV. (See electrom volt.) (See Appendiz.)

binding energy 'The binding energy of a nucleus is the minimum en-ergy required to dissociate it into its component neu-trans and protons. Neutron or proton Nving energies are those required to remove a neutron og a proton, respectively, from a nucleus. Electron Nadina en-orgy is that required to remove an electron from an atom or a molecule. (Compare fission. iostration.)

biological dose The radiation dose absorted in biological matsrial.

Measured in rems. (See absorbed dose.)

biological half. life The time required for a biological system, such as a man or an animal, to eliminate, by naturalprocesses, half the amount of a substance (such as a radioactive material) that has entered it. (Compare half-lifet see half-life, effectsve.)

biological shield A mass of absorbing material placsd around a reac-tor or radioactive source.to reduce the radiation to a level that is safe for human beings. (See absorber, shield, thermal shield.)

blanket A layer of fertile material, such as uranium 238 or thorium-232, placed around the fissionable material in a reactor. (See fertile material, seed core.)

blast wave A pulse of air, propagatsJ from an explosion, in which the pressure increases sharply at the front of a moving air mass, accosepanied by strong, transient winds. (See shock wave.)

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bocy burden The amount of radioactive matertal present in the body of a man or an anamal. (See bachroundredsa.

Ison, whole body counter.)

boiling water A reactor in which water, used as both coolant and r t3Ctor moderator, is allowed to boil in the core. The re.

sulting steam can be used directly to drive a turbine.

(Compare water boster.)

bcr'e Seteu er A radioisotope that tends to accumulate in the bones when it is introduced into the body. An example is strontium-90. which behaves chemically likecalcium.

brachytheraoy Radiattoo treatment ustas a solid or enclosed radio-1sotopte source on the surface of the body or at a short distance from the area to be treated. (Com-pare snterstitial implants. teletherapy; see rodsation therapy.)

breeder reactor A reactor that produces fissionable fuel as well as consvaning it, especially one that creates more than it consumes. The new fissionable materialis created by capture in fertile materials of neutrons from fis-ston. The process by which this occurs is known as breeding. (Compare cont erter reactor; see fertste material.)

breeding (See breeder reactor.)

brseding gain (See breedrag rotto.)

breecing ratio The ratto of the number of fissionable atoms pro.

duced in a breeder reactor to the number of fission.

able atoms consumed in the reactor. Breeding gaan is the breeding ratto minus cne. (Compare conter-sion ratto.)

bremsstrahlung Electromagnetsc radiation emttted (as photons) when a fast-moving charged particle thsually an electron) loses energy upon being accelerated and deflected by the electric field surrounding a positively charged atomic nucleus. X rays produced in ordinary X ray machines are bremsstrahlung. (In German, the term means " braking radiation".) (See X ray.)

bubble chamber A device used for detection and study of elementary particles and nuclear reactions. Charged particles from an accelerator are introduced into a super.

heated liquid, each forming a traA1 of bubbles along its path. The trails are photographed, and by sudy-ing the photograph scientists can identify the par.

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originate. (Compare cloud chamber, sport chamber.)

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burnable poison A neutron absorber (or potson), such as boron,which, when purposely incorporated in the fuel or fuel clad-ding of a nuclear reactor, gradually ** burns up" (is changed into nonabsorbing material) under ne'utron irradiation. This process compensates for the loss of reactivity that occurs as fuel is consumed and fission-product poisons accumulate, and keeps the overall characteristics of the reactor nearly con-stant during its use. (See poison, reactitity.)

burner reactor A cosverter reactor.

burnup A measure of reactorfuel consumption. It can be ex-pressed as (a) the percentage of fuel atoms that have undergone fission, or (b) the amount of energy pro-duced per unit weight of fuelin the reactor.

by procuct material Any radioactive material (except source material or fLasionable material) obtained during the production or use of source material or fissionable material. It includesfissson products and many other radioiso-topes produced in nuclear reactors. (Compare fis-sionable material, source matenal.)

O Capacity factor plant factor, capture A process in which an atomic or nuclear system ac-quires an additional particle; for nummple, the cap-ture of electrons by positive ions, or capture of electrons or neutrons by nuclei. (See absorption. K-capture, radiative capture.)

Carrier A stable isotope. or a normal element, to which ra.

dioactive atoms of the same element can be added to obtain a quantity of radioactive mixture sufttcient for hwitng, or to produce a radioactive mixture that will undergo the same chemical or biological reac-tion as the stable isotope. A substance in weighable amount which, when associated with a trace of rn-other substance, will carry the trace through schem-ical, physical or biological process. (See radioactive tracer; tracer, isotopic. )

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Cascade A connected arrangement of units of equipment for separation of isotopes. A single device or process usually can produce only a small amount of isotopic separation, but if a number of these are connected together the effect can be multiplied and a signincant amount of separation achieved. An example is a cas.

cade of barriers for the gaseous diffusion process.

(See gaseous diffusson. tsotope separation.1 Cathode rays A stream of efectrons emitted by the cathode,or neg.

ative electrode, of a gas-discharge tube or by a hot nlament in a vacuum tube, such as a television tube.

Cave A hot cell.

6erenkov radiation 1.ight emitted when charged particles pass through a transparent material at a velocity greater than that of light in that material. It can be seen, for example, as a blue glow in the water around the fuel elements of pool reactors. P. A. derenkov was the Russian scientist who nrat explained the origin of this light.

(See radiation.)

Chain reaction A reaction that stimulates its own repetition. In a fission chain reaction a nastonable nucleus absorbs a neutron and fissions, releasing additional neutrons.

These in turn can be absorbed by other Bastonable nuclet, releasing still more neutrons. A fission chain reaction is self-sustatning when the number of neu.

trons released in a given time equals or exceeds the ratmber of neutrons lost by absorption in non.nssion.

ing material or by escape from the system. (See enticalsty, fissson. )

Charged particle Anion! an elementary particlethat carries a positive or negative electric charge. (See plasma.)

chemical dosimeter A detector for indirect measurement of radiation by indicating the extent to which the radiation causes a definite chemical change to take place. (Compare film badge, ionstalwn chamber;see dossmeter.)

l Chemical shim Chemicals, such as borte acid, which are placed in a reactor coolant to control the reactor by absorbing l

neutrons. (Compare bunsable posson, shsm rod; see absorber.)

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chopper A rotating shutter for interrupting an otherwise con-tinuous stream of particles. Choppers can release short bursts of neutrons with known energies, used to measure enaclear cross sections. (See beam. cross section.)

cladding The outer Jacket of nuclearfuel elements. It pre-vents corrosion of the fuel and the release of fission products into the coolant. Aluminum or its alloys, stainless steel and zirconium alloys are common cladding materials.

l clean bomb A nuclu bomb that produces relatively little radio-active fallout. Afusion bomb. (Compare dirty bomb.)

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closed cycle A reactor design in which the primary heat of fission reactor system is transferred outside the reactor core to do useful I work by means of a coolant circulating in a com-plately closed system that includes a heat exchanger.

(Compare & rect-cycle reactor system. ind rect-cycle reactor system, open-cycle reactor system.)

cloud chamber A device in which the tracks of charged atomic par-ticles, such as cosmic rays or accelerator beams, are aisplayed. It consists of a glass-walled chamber filled with a supersaturated vapor, suca as wet air.

When charged particles pass through the chamber, they trigger a process of condensation, and so pro-duce a track of tiny liquid droplets, much like the vapor trail of a jet plane. This track permits sci-entists to study theparticles' motions and interactions.

(Compare bubble chamber, spark chamber.1 cobalt bomb If a nuclear weapon were encased in cobalt, large amounts of radioactive cobalt-00 could be produced when it was detonated. Such a weapon (only theoreti-cal today) could add to the explosive force of the bomb the danger of the highly penetrsting and long-lasting gamma radiation emitted by ec'Jalt-60 Cockcroft Walton A device for accelerating charged particles by the accelerator action of a high direct-current voltage on a stream of gas ions in a straight insulated tube; the voltage is generated by a voltage multiplier system consisting essentially of a number of condenser pairs connected through switching devices (vacuum tubes). The par-ticles (which are nuclei of an ionized gas, such as protons from hydrogen) gain energies of up to several million electron volts from the single accelersdon so produced. Named for the British physicists, J. D.

I Cockcroft and E. T. S. Walton, who developed this machine in the 1930s. (See accelerator.)

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Coffin A heavily shielded shipping cask for spent (used) fuel elements. Some coffins weigh as much as '!5 tons.

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coincidence A method for detecting or identifytag rs. active ma-Counting terials and for calibrating their disintegration rates by counting two or more characteristic radiation events (such as gamma ray emisotons) which occur together or in a specific time relationship to each other. This method is important in activation anal-ysts, medical scanning, cosmic ray studies and low-level measurements. (See counter, lose-letal countsng.)

collimator A device for focusing or confining a beam of par-ticles or radiation, such as X rays.

collision A close approach of two or more particles, photons, atoms or nuclei, during which such quantities as en-orgy, momentum and charge may be exchanged. (See compton effect, escsted state, pasr />roductson, scat-tersag.)

Compton of'ect Elastic scattering of photo is (x raye or gamma rays) by electrons. In each such process the electron gains energy and recoils, and the photon toese energy.

This is one of three waye photons lose energy upon interacting with matter, and is the usual method with photons of intermediate energy and materials of low atomic number. It is named for A. If. Compton, American physicist, who discovered it in 1923. (See collision, past production, scattersng.)

containment The provision of a gastight shell or other enclosure around a reactor to confine fission products that otherwise might be released to the atmosphere in the event of an accident.

containment vessel A gas tight shell or other enclosure around& reactor.

(Compare pressure vessel:see containment.)

contamination (see radioactive contams.ation.)

control rod A rod, plate, or tube coanining a material that readily absorbe neutrons (hafnium, boron, etc.), used to control the power of a nuclear reactor. By absorts-ing neutrons, a control rod prevents the neutrons from causing further fission. (See absorber, regulat-ing rod, safety rod, and shim rod, which are types of control rods.)

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l Controlled fusion (See controlled thermonuclear reactson.)

experiment controlled thermo-Controlled fusion, that is, fusion produced under re-nuclear reaction search conditions, or for production of useful power.

(See Sherwood.)

conversion (See converter reactor.)

conversion ratio The ratio of the number of atoms of newfissionable maternal produced in a converter reactor to the orig.

inal number of atoms of fissionable fuel consumed.

(Compare breeding ratio.)

Converter reactor A reactor that produces some fissionable material, but less than it consumes. In some usages, a reactor that produces a fissionable material different from the fuel burned, regardless of the ratio. In both usages the process is known as conversion. (Com-pare breeder reactor,)

Coolant A substance circulated through a suelear reactor to remove or transfer heat. Common coolaats are wa.

ter, air, carbon dioxide, liquid sodium and sodium.

potassium alloy (NaK).

Core The contral portion of a nuclear reactor can'uning the fuel elements and usually the moderator, but not the reflector.

Cosmic rays Radiation of many sorts but mostly atomic nuclei (protons) with very high energies, originating outside the earth's atmosphere. Cosmic radiation is part of the natural bachground radiation. Some cosmic rays are more energetic than any man-made forms of radiation. (See neutrina)

Counter A general designation applied to radiation detection instruments or survey meters that detect and mea.

sure radiation in terms of individual lanisations, dis-playing them either as the accumulated total or their rate of occurrence. (See Ceiger-MEller counter, scaler,)

Critical Capable of sustaining a chain reaction. (See criti.

cality) critical 3SSembly An assembly of sufScient fissionable material and moderator to sustain a fission chain reaction at a very low power level. This permits study of the be.

havior of the components of the assembly for various fissionable materials in different geometrical ar-rangements. (Compare nuclear reactor.)

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1 Critical experiment An experiment to verify or supplement calculationsof the critical size and other physical data affecting a reactor design. The power is kept so low that a sys-tem for removing heat is not required.

Critical facility A facility where entical experiments are conducted.

Critical mass The smallest mass of fissionable maternal that will support a self-sustaining chain reaction under stated conditions.

Criticality The state of a nuclear reactor when it is sustaining a chain reaction. (See dry crtticality, multiplication factor, prompt criticality, reactivity, wet criticalit)L)

Cross Section (Symbol a (sigmalj A measure of the probability that-a NUCLEAR REACTION will occur.Usually measured in barns, it is the apparent (or effective) area pre-sented by a target nucleus (or particle) to an on-coming particle or other nuclear radiation, such as a photon of gamma radiation.

Curie (Symbol c) The basic unit to describe the intensity of j

radioactitsty in a sami e of material. The curie is l

i equal to 37 billion disintegrations per second, which is approximately the rate of decay of 1 gram of ra-dium. A curie is also a quantity of any nuclide having 1 curie of radioactivity. Named for Marie and Pierre Curie, who discovered radium in 1898. (Compare rem, roentgen.) (See Appendiz.)

Cutie pie A common radiation survey meter used to determine exposure levels or to locate possible radiation haz-ards. (See monstor.)

Cyclotron A particle accelerator in which charged particles re-ceive repeated synchronized accelerations by elec-trical fields as the particles spiral outward from their source. The particles are kept in the spiral by a powerful magnetic field. (Compare synchro-cyclotron.)

O daughter A nuclide formed by the radioactive decay of another nucLde, which in this context is called the parent.

(Ste radioactive series.) (See Appendix.)

decay Chain A radioactire series.

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I decay heat The heat produced by the decay of radioactive nu-clides. (See afterheat decay. radscactivet SNAP 1 decay radioactive The spontaneous transformation of one nuclide into a different nuclide or into a different energy state of the same Inaclide. The process results in a decrease, with time, of the number of the original radioactive atoms in a sample. It involves the emission from the nucleus of alp %n partseles, beta particles (or elec-trons), or Ear, ma rays.* or the nuclear capture or ejection of ort'tal electrons; or fission. Also called radioactis;e dissutegwson. (See half-life, nuclear re-actson, radioactste serses.) (See Appendix.)

decontamination The removal of radioactive cont =wnts from sur-faces or equipment, as by cleaning and washing with chemicals. (See radioactive contamsnation.)

delayed neutrons Neutrons emitted by radioactivefission products in a reactor over a period of seconds or minutes after a fission takes place. Fewer than 1% of the neutrons are delayed, the majority being prompt neutrons.

Delayed neutrons are important considerations in reactor design and control. (See dollar.)

depleted fuel (see depleted uranium spentfuel.)

depleted uranium Uranium having a smaller percentage of uranium-235 than the 0.'G found in natural uramum. It is obtained from the spent (used) fuel elements or as by-product tasis, or residues, of uranium isotope separation.

(Compnre natural uramum, spentfuel.)

detector Material or a devtee that is sensitive to radia son and can produce a response signal suitable for measure-ment or analysis. A radiation detectson snstrument.

deuterium 8

[ Symbol H or D] An tsotope of.W.en whose nu-cleus contains one neutron and one proton and is therefore about twice as heavy as % nucleus of normal hydrogen, which is only a single proton. Deu-terium is often referred to as heasy hydrogen: it occurs in nature as 1 atom to 6500 atoms of normal hydrogen. It is nonradioactive. (See heavy water, hydrogen.)

deuteron The nucleus of deutersum. It contains one proton and one neutron.

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i device, nuclear A nuclear explosive usea wr peaceful purposes, tests or experiments. The term is used to distinguishthese explosives from nuclear weapons, which are packaged units ready for transportation or use by military forces. (Compare nuclear weapons.)

diffusion plant (See faseous diffusion.)

direct cycle reactor A nuclear power plant system in wtsten the coolant or system heat transfer Guid circulates first through the reac-tor and then directly to a turbine. (Compare :ndirect-cycle reactor system.)

dirty bomb A fission bomb or any other weapon which would dis-tribute relatively large amounts of radioactivity upon explosion, as distinguished from a fusion weapon.

(Compare clean bomb.)

discriminator An electronic circuit which selects signal pulses ac-cording to their pulse hetght or voltage. It is used to delete extraneous radiation counts or background ra=

diation, or as the basis for energy spectrumanalysis.

disintegration. Equivalent to radioactive decay.

--- radioactive distribution factor A term used to express the modification of the effect of radiation in a biological system attributable to the norumtfar'n distribution of an internally deposited isotope, such as radium's being concentrated in bones. (See absorbed dose, dose equsvalent, q uality factor, relative bsologtcal effectiveness.)

dollar A unit of reactivity. One dollar is the maximum amount of reactivity in a reactor due to delayed neu-frons alone. (See reactivity.) (See Appendiz.)

Doppler effect The shift with temperature of the interaction rate be-tween neutrons and reactor materials, such as fuel rods, structural materials, and fertile materials.The shift can appreciably affect tie neutron density and j

hence the reactivsty of reactore.iSee neutron denssty.)

dose (See absorbed dose, bsologscal dose, maxnmum per-l misssble dose, threshold dose.)

f dose equivalent A term used to express the amount of effective ra-distian when modifying factors have been considered.

j The product of absorbed dose multiplied by a quality factor multiplied by a distnbutionfactor. It is ex-pressed numerically in rems.

15 l

6

e dose rate The radiation dose delivered per unit time and mea-sured, for instance, in rems per hour. Gee absorbed dose, rem.)

dosimeter A device that measures radiation dose, such as afilm badge or somsation chamber. We radsation dosime-try.)

dosimetry (See radiatson dossmetry.)

doubling time The time required for a breeder reactor to produce as much fissionable material as the amountusually contained in its core plus the amount tied up in its fuel cycle (fabrication, reprocessing, etc.). It is es-timated as 10 to 20 years in typical reactors. (See breeder reactor, fuel cycle.)

dry criticality Reactor criticality achieved without a coolant. (Com-pare wet crsticality; see crsticality.)

dual-cycle A reactor-turbine system in which part of the steam reactor system fed to the turbine is generated directly in the reactor and part in a separate heat exchanger. A combination of dsrect-cycle and sndirect-cycle reactor systems.

dual-purpose A reactor designed to achieve two purposes, for ex-reactor ample, to produce both electricity and new fissice-able material.

O effective half life (See half-life, effective.)

effective (see multiplicationfactor.)

multiplication factor ion constant)

Einstein eouation (See mass-energy eguation.)

l elastic scattering (see compon effect, scattersng.)

1 electromagnetic Radiation consisting of associated and interacting radiation electric and magnetic waves that travel at the speed of light. Examples: light, radio waves, gamma rays, l

X rays. All can be transmitted through a vacuum.

I (Compare ionissng radiation; see quantum.)

16 i

I

electron (Symbol e-] An eleneentary particle with a unit pega-tive electrical charge and a mase /sst that of the 8

i proton. Electrons surround the positively charged NUCLEUS and determine the chemical properties of the atom. Positive electrons, or positrons. also exist.

(Compare antimattert see paar production, shell.)

electron capture ( Abbreviation EC) A mode of radioactive decay of a nuclide in which an orbital electron is captured by and merges with the nucleus, thus forming a new nuclide with the mass number unchanged but the atomic number decreased by 1. (See K-capture.)

electron volt (Abbreviation et or eV) The amount of kinetic energy gained by an electron when it is accelerated through an electric potential difference of 1 volt. It is equiva-lent to 1.003 x 10-'8 erg. It is a unit of energy, or wort, not of voltage. (See Bev, Mev.) (See Appendiz.)

element One of the 103 known chemical substances that can-not be divided into simpler substances by chemical means. A substance whose em all have the same atomic number. Examples: hydrogen, lead, uranium.

(Not to be confused with fuel element.) (See atom, matter, nuclide.) (See Appendix.)

elementary particles The simplest particles of matter and radiation. Most are short-lived and do not exist under normal con-ditions (exceptions are electrons, neutrons, protons and neuhenos). Originally this term was applied to any particle that could not be subdivided, or to con-stituents of atoms; now it is applied to nucleons (protons and neutrons), electrons, mesons, muons, baryons, strange particles, and the anti-particles of each of these, and to photons, but not to alpha pan ticses or deuteronse Also called fundamentalparticles.

end product (See radioactive series.)

)

energy The capability of doing work. (See kinetic energy, nu.

I clear energy.)

j l

enriched material Material in s ich the percentage of a givenisotope

)

1 present in a n terial has been artificially increased, i

so that it is higw.' than the percentage of that isotope l

naturally found in the material. Enriched uranium contains more of the fissionable isotope uranium-235 than the naturally occurring percentage (0.7%). (See isotopic curschment.)

17 99*

m o-s sas

C *'.dCnm e n*

isotopic enrichment.

eXnerma; neutron An antarmcJiate neutros.

tDitt'Orrnal rea;tCr An tntermedsatt reactor.

00uF.'ascr.! ton (See TNT equ :.'alant.)

exerts reactivity More reactivity than that neededtoachievecrtticanty Excess reactivity is built into a reactor by using ex-tra fuel) in order to compensate for fuel burwup and the accumulation of fission-product poisons during operation. (See criticality, reactitity.)

erc.1ed state The state of a molecule, atom, electron or nucleus when it possesses more than its normal energy. Ex-cosa nuclear energy is often released as a gamma ray. Excess molecular energy may appear as !!uo-rescence or beat. (Compare ground statt.)

eXC!US!On area An area immediately surrounding a nuclear reactor where human habitation is prohibited to assure safety in the event of accident. (See low population sont.)

excursion A audden, very rapid rise in the power level of a re-actor caused by superctificality. Excursions are usually quickly suppressed by the negative tempera-ture coefficient of the reactor and/or by automatic control rods. (See sqfaty rod. scram, temperature coefficient of reactssity.)

experimental A reactor to test the design of new reactors. (Com-reactC-pare research reactor. test reactor.)

O tahout Air-borne particles edaining radioactive material which fall to the gre tnd following a nuclearexplosion.

"Incal fallout" #<om nuclear detonations falls to the earth's surface within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the detonation.

"Troposphe.se fallout" constats of materialinjected into the 'toposphere but not into the higher altitudes of the stratosphere. It does not fall out locally, but usually is deposited in relatively narrowbands around the earth at about the latitude of injection. "Strato-spherte fallout" or " worldwide fallout"is that which' is injected into the stratosphere and which then falls out relatively slowly over much of the earth's surface.

(Compare background radsation.)

'&st Teccer A reactor that operates with fast neutrons and pro-rea;;y duces more fasssonable material than it consumes.

(See breeder reactor, fast neutron, fast reactor.1 18 l

e a

fast neutron A neutron with energy greater than approximately 100,000 electron volta. (Compare antermediate sene.

Iron. Prompt neutron, thermal neutron.)

fast reactor A reactor in which the naston chain reaction is sus-tained primarily by fast neutrons rather than byther-mal or intermediate neutrons. Fast reactors contain little or no moderator to slow down the neutrons from the speeds at which they are ejected from fis-stordng nuclei. (Compare intermediate reactor, ther-mal reactor.)

feed matertais Renned uranium or thorium metal or their pure com-pounds in a fctm suitable for use in nuclear reactor fuel elements or as feed for uranium enrichmentpro-cosees. (See ennched materta;.)

fert:le material A material, not itself nastonable by thermaineutrons, which can be co verted into a fissile material by tr-radiation in a reactor. There are two basic fertile materials, uranium-238 and thortum-232. When these fertile materials capture neutrons, they are partially converted into fissile plutonium 239 and uranium-233, respectively. (Compare /issile matenal.)

film badge A light-tscht package of photographic nlm worn like a badge by workers in nuclear industry or research, used to measure possible esposure tolONIELVC RA-DIATION, The absorbed dose can be calculated by the degree of film darkening caused by the irradiation.

(Compare son:tation chambert see dosimeter.)

fireball The luminous ball of hot gases that forms a few mil.

11onths of a second after a nuclear orplosion. (See atomsc cloud.)

fissile material While sometimes used as a synonym for fissionable material, this term has also acquired a more re-strteted meaning, namely, any material fissionable by neutrons of all energies, including (and especially) thermal (slow) neutrons as well as fast neutrons; for example, uranium-235 and plutonium-239. (See fis-stonable matenal.)

fission The splitting of a heavy nucleus into two approat.

mately equal parts (which are nuclei of 11ghter ele-monts), accompanied by the release of a relatively large amount of energy and generally one or more neutrons. F1 seton can waarspontaneously,butusually is caused by nuclear absorption of gamma rays, neu-trans or other particles, (Compare fusion; see chain reaction, nuclear reaction.)

l 19 l

fission fragments The two nuclei which are formed by the fission of a nucleus. Also referredtoasprimaryfission products.

They are of medium atomic weight, and are radio-active. (see fission products.)

fission product The absorption or capture of neutronsbynasionprod.

poisoning ucts in a reactor, decreasing its reactivity. (See poison.)

fission products The nuclot (fission fragments) formed by the nasion of heavy elements, plus the nuclides formed by the Assion fragments' radioactive decay, (Compare fis-sson fragments; see decay, radioactive.) (See Ap-pendiz.)

fission weapon An atomic bomb.

fission yield The amount of eneacy released by assion in a ther-monuclear (fusion) explosion as distinct from that released by fusion. Also the amount (percentage)of a given nuclide produced by fission. (Compare yield; see thermonuclear reactson, TNT equivalent.)

fissionable material Commany used as a synonym for assile material.

The meaning of this term also has been extended to include material that can be fissioned Dyfast neutrons only, such as uranium-238. Used in reactor opera-tions to meanfuel. (Comparef X waterial, fissile matersal.)

flash burn A skin burn due to a nash of thermal radiation. n can be distinguished from a flame burn by the fact it oc-curs on unshielded parts of the body that are in a direct line with the origin of the thermal radiation.

(See ionising radiation, thermal burn.)

fluid fuel reactor A type of reactor (for example, afused-salf reactor) whose feelis in fluid form.

fluidized bed A reactor design in which the fuer ranses in size from reactor small particles to pellets. Although the fuel particles are solid, their entire mass behaves like a fluid be-cause a stream of liquid or gas coolant keeps them moving.

fluorescence Many substances can ausorb energy (as from X rays, ultraviolet light, or radioactive particles), and im-mediately emit this energy as an electromagnetic j

photon, often of visible light. This emission is fluo-rescence. The emitting substances are said to be fluorescent. (Compare lus.sescence, scintillation; see excited state.)

20 f

i i

i

d fluoroscope An instrument with a fluorescent screen suitably mounted with respect to an X-ray tube, used for im-mediate iMirect viewing of internal organs of the body, internal structures in apparatus or masses of metals, by means of I rays. A fluorescent image, really a kind of X-ray shadow picture, is produced.

(See X ray.)

flux ineutron) A measure of the intensity of neutron radiation. It is the number of neutrons passing through 1 square centimeter of a given target in 1 second. Expressed as av where n = the number of neutrons per cubic centimeter and y = their velocity in centimeters per second. (See sntegrated neutron finr, intenssty, neu-tron denssty.)

food chain The pathways by which any material (such as radio-active material from fallout) passes from the first absorbing organiam through plants and 2ntmata to man.

fuel 14ssionable material used or usable to produce energy in a reactor. Also applied to a mixture, such as not-ural uramuns. in which only part of the atoms are readily fissionable, if the misc!re can be made to sustain a chain reaction. (See fissionable material.)

fuel cycle The series of steps involved in supplying fuel for nu-clear power reactors. It includes mining, refining, the original fabrication of fuel elements, their use in a reactor, chemical processing to recover tne fis-sionable material remain;;g in the spent fuel, re-enrichment of the fuel material, andrefabricationinto new fuel elements.

fuel element A rod, tube, plate, or other mechanical shape or form into which nuclear fuelis fabricated for use in a re-actor. (Not to be confused with element.) (See nuclear reactor.)

f fuel reprocessing The processing of reactor fuel to recover the unused fissinnmMa material. (See reeveling, spentfuel.)

l i

l fundamental elementary particles.

particles fused salt reactor A type of reactor that uses molten salts of uranium for both fuel and coolat.

21

e fusion The formation of a heavier aucleus from two lighter ones (such as hydrogen isotopes), with the attendant release of energy (as in a hydrogen bomb). (Compare fission; see nuclear reaction. Sherwood, thermonu-clear reaction.)

e fusion We8Dof' An atomic weapon using the energy of nuclearAsson, such as a hydrogen bomb.

O gagmg gaugung.

gamma rays [ Symbol y (gamma)) High-energy, short-wavelength electromagnetic radiatson. hmma radiation fre-quently accompanies alpha and beta emissions and always accompanies fission. Gamm2 rays are very penetrating and are best stopped or shielded against by dense materials, such as lead ordepleteduranium.

Gamm a rays are essentially similar to X rays, but are usually more energetic, and are nuclearin origin.

(Compare X ray;see decay radioective, excited state.

photon.)

gas centrifuge A method of isotopic separation in stich heavy gas.

process eous atoms or molecules are separated from light ones by centrifugal force. (See isotope separation.)

gas: cooled reactor A nuclear reactor in which a gas is the coolant.

gaseous A method of isotopic separation based on the fact that diffusion plant-gas atoms or molecules with different masses will diffuse through a porous barrier (or membrane) at different rates. The method is used by the AEC to separate uranium-233 from uranium-238;it requires large gaseous-diffusion plants and enormous amounts of electrte power. (See cascade. isotope separation, uranium hexafluoride.)

gaugmg The measurement of the thickness, density or quan-t2ty of material by the amount of radiation it absorbs.

This is the most common use of radioactive isotopes in industry. Also spelled gaging.

22

l l

j 1

Geiger Muller A radiation detection and measuring Lastrumett. It Counter consists of a gas-filled (Geiger-Muller) tube contain-(Geiger. Muller tube) ing electrodes, between wtuch there is an electrical voltage but no current flowing. When ionising radiation passes through the tube, a short, intense pulse of current passes from the negative electrode to the positive electrode and is measured or counted. The number of pulses per secon$ measures the intensity of radiation. It is also often known as Geiger counter; it was named for Hans Getter and W. MG11er who invented it in the 1920s. (See counter.)

generatl0n time The mean time for the neutrons produced by one fis-ston to produce fissions again in a chain reaction.

(See chasn reaction.)

genetic effects Radiation effects that can be transferred from parent of radiatl0n to offspring. Any radiation-caused changes in the genetic material of sex cells. (Compare radsomuta-tion. somatic effects of radtatson.)

geometry The spatial conaguration, pattern or relationship of components in an experiment or apparatus. In reac-tot technology, the term refers to the shape and size of fuel elements, moderator and reflector and their location with respect to each other. In nuclear phys-ics, it refers to the arrangement of source and de-tacting equipment. In counting and scanning, the term commonly indicates the percentage of the ra.

diation leaving a sample which reaches the sensitive volume of a counter. (See lattice.)

glory hole A beam hole.

Elove BOX A sealed box in which workers, using gloves attached to and passing through openings in the box,can handle radioactive materials safelyfrom the outside.

graphite A*very pure form of carbon used as a moderator in nuclear reactors, green salt uranium tetrafinortda.

I ground state The state of a nucleus, atom or molecute at its lowest (normal) energy level. (Compare excited state.)

l ground Zero The point on the surface of land or water vertically

(

below or above the center of a burst of a nuclear explosion. For a burst over or under water, the term surface zerois preferable.

23 l

o O

H bomb. A hydrogen bomb.

half life The ume in which half the atoms of a particular ra-dioactive substance disintegiste to another nuclear form. Measured half-lives vary from millionths of a second to billions of years. (See decay, radioactive.)

(See Appendiz.)

half life. biological (See biological half-life.)

half life, effective The time required for a radionuclide contained in a biological system such as a man or an animal, to reduce its activity by half as a combined result of radioactive decay and biological ehmMtion. (Com.

• pare bsologscal half-lifet see half-life.)

half thickness The thickness of any given absorber that will reduce the intensity of a beam of radiation to one-half its initial value.

hatf time (see residence tsme.)

half value layer The thicknese of any particular material necessary to reduce the dose rate of an X-ray beam to one-half its original value.

hand and foot A monitoring device arranged to'stre a rapid radia-counter tion survey of hands and feet of persons working with radioactive materials, ta detect radioactive contam-ination. (See counter, monitor, personnelmonitorsng, radioactive contamination.)

health physics The science concerned with recognition, evaluation, and control of health hazards from ionssing radiation, heat exchanger Any dettee that transfers heat from one fluid (liquid or gas) to another or to the environment.

I l

heat sink Anything that absorbs heat; usually part of the en-

)

vironment, such as the air, a river, or outer space.

heavy hydrogen deuterium.

24 1

I 1

i

~

j

e (Symbol D o] water containing signincantly more heavy water i

than the natural proportion (one in 6500) of heavy by-drogen (deuterium) atoms toordinary hydrogen atoms.

Heavy water is used as a moderator in some reac-tors because it slowe down neutrons effectively and also has a low cross section for absorption of neutrons.

heavy water-A reactor that uses heaty water as its moderator.

moderated reactor Heavy water is an excellent moderator and thus per-mits the use of inexpensive natural (unenriched) ura.

nium as a fuel.

heterogeneous A reactor in which the fuel is separate from the reactor moderator and is arranged in discrete bodies, such as fuel elements. Most reactors are heterogeneous.

(Compare homogeneous reactor.)

homogeneous A reactor in which the fuel is mixed with or 'is-d reactor solved in the moderator or coolant. Example: a fused-salt reactor. (Compare heterogeneous reactor.)

hood A protective device, usually providingspecialventila.

tion to carry away gases, in which dangerous chemi.

cal, biological, or radioactive materials can besafely handled.

hot Highly radioactive.

hot cell A heartly shielded enclosure in wtuch radioactive ma-terials can be handled by persons using remote ma-napulators and viewing the materials through shielded windowe or periscopes. (See shield.)

hot laboratory A laboratory designed for the safe h=mng of ra-dioactive materials, and usually containing one or more hot cells.

hot spot A surface area of higher-than-average radioactinty.

j Also a part of a fuel element surface that has become overbeated.

i hydrogen (Symbol H) The lightest element, No.1 in the atomic series. It has two natural isotopes of atomic weights 1 and 2. The nrst is ordinary hydrogen, or light by.

drogen; the second '

suterium, or heavy hydrogen.

A third isotope, tritius, atomic weight 3. is a radio-active form produced in reactors by bombarding 11thium-6 with neutrons. (See Appendix.)

25 o

hydrogen bomb A nuclear weapon that derives its energylargelyfrom fusion. (see thermonuclear reaction.)

hyp;,ron one of e class of short-lived elementary particles with a mass greater than that of a proton and lesa than that of a deuteron. All hyperons are unstable and yield a nucleon as a decay product. (See baryon.)

O

~

implosion weapon A weapon in which a quantity of fissionable material, less than a critical mass at ordinary pressure, has its volume suddenly reduced by compression (a step

. accomplished by usutg chemical explosives) so that it becomes supercritical, producing a nuclear explo-ston. (See supercritical mass.)

indirect cycle A reactor system in wtuch a heat exchanger trans.

reactor system fers heat from the reactor coolant to a second fluid which then drives a turbine. (Compare closed-cycle reactor systr., direct-cycle reactor system.)

induced radioactivity Radioactivity that is created when substances are bombarded with neutrons, as from a nuclear explo-sion or 1.1 a reactor, or with charged particles pro-inuced by accelerators. (See activation.)

inelastic scattering (See scattenng.)

initial nuclear Radiation emitted from the fireball of a nuclear ex-radiation plosive during the first minute (an arbitrary time interval) after detonation. (Compare ressdual nuclear radiation.)

in-pile A term used to designate experiments or equipment inside a reactor. (Seepile.)

in pile loop (See loop.)

integrated riux multiplied by time, usually expressed as ni;t, neutron flux when n e the number of neutrons per cubic centimeter, u = their velocity in centimeters per second, and t =

time in seconds. (See f7ux.)

intensity The energy or the number of photons or particles of l

any radiation incident upon a unit area or flowing through a unit of solid material per unit of time. In connection with radioactivity, the number of atoms I

disintegrating per unit of time. (Seeflux.)

26 e

e

intermediate A neutron having energy greater than the.t of a ther.

(epithermal) neutron mal neutron but less than that of a fast neutron. The range is generally considered to be between about 0.5 and 100,000 electron volts. (Compare fast neutron, thermal neutrem.)

intermediate A reactor in which the chain reaction is sustained (epithermal) reactor mainly by intermediate neutrons. (Comparefast re-actor, thermal reactor.)

interstitial implants Solid or encapsulated radiation sources, made in the form of seeds, wires or other shapes to be inserted directly into tissue that is to be irradiated. (See brachytherapy.)

ion An atom or molecule that has lost or gained one or more electrons. By this nomsation it becomes elec-trically charged. Ersrnples: an alpha particle, which is a helium atom minus two electrons;aproton, which is a hydrogen atom minus its electron. (Compare atom, elementary particles, molecule.)

ion engine An engine which provides thrust by expelling accel-ersted or high velocity ions. Ion engines using en-

..ergy provided by nuclear reactors are pioposed for space vehicles.

ion exchange A chemical process involving the reversible inter-change of various tons between a solution and a solid material, usually a plastic or a resin. It is used to separate and purify chemicals, such asfission prod-ucts, rare earths, etc., in solutions.

lon pair A closely associated positive ion and negative ion (usually an electron) having charges of the same magnitude and fonned from a neutral atom or mole-cule by radiation. (Compare pair production.)

ionization The process of adding one or mor'e electrons to, or removing one or more electrons from, atoms or molecules, thereby creating ions. High temperatures, electrical discharges, or nuclear radiations can cause ionisation.

ionization chamber An instrument that detects and measures lanmng ra-diation by measuring the electrical current that flows when radiation ionizes gas in a chamber, m2Wf the gas a conductor of the electricity. (Compare chemical dassmeter. film badge.)

s 27 ew L

e Ae-

+aw.g

._m.

ionizing event Any occurrence in which an ton or group cf ions is produced; for example, by passage of a charged par-tsele through matter, ionizing radiation Any radiation displacing electrons from atoms or molecules, thereby producing sons. Examples: alpha, beta, gamma radiation, short-wave ultraviolet light.

Iontaing radiation may produce severe skin or tissue damage. (See radiatxon, radiation burn, radnation ill=

ness.)

irradiation Exposure to radiation, as in a nuclear reactor. (See spent fuel.)

isobar One of two or more nuclides having about the same l

atomic mass but different atomic numbers, hencedif-ferent chemical properties. Example: 'jC,8lN,and )O 8

are isobars. (Compare isotope.)

isodose curves Curves or lines drawn to connect points where iden-tical amounts of radiant energy reach a certain depth in tissue, isointensity Imaginary lines on the surface of the groundor water, contours or lines drawn on a map, jotning points in a radiation field which have the same radiation intensity at a given time.

isomer One of two or more nuclides with the same numbers of neutre,M and protons in their nuclei, but with dif-ferent one. vies; a nuclide in the czeited state and a stmtlar nuclide in the Eround state are isomers.

(Compare isotope.)

isotone One of several nuclides having the same number of neutrons but a different number of protons in their nuclei. Example: potassiutn-39 (j)C,) and calcium-40 (Mage) are isotones. (Compare isotope.)

isotope One of two or more atoms with the same atomic num-ber (the same chemical element) but with different atomre accights. An equivalent statement is that the nuclei of isotopes have the same number of protons but different numbers of neutrons. Thus, *jC, 'jC, and 8lC are isotopes of the element carbon, the sub-l scripts denoting their c xnmon ).omic numbers, the superscripts denoting ths differing mass numbers, or apprnrimate atomic weights. Isotopes usually have

'very nearly the same chemical properties, but some-(

what different physical properties. (Compare isobar, l

isotone, nuclide;see radioisotope.) (See Appendix.)

{

28 i

isotope farm A car n-14 growth chamber, or greenhouse, ar-ranged as a closed system in which plants can be grown in a carbon-14 dioxide ("COs) atmosphere and thus become labeled with "C. Isotope farms also can be used with other labeled materials, such as heavy water (D 0), phosphorus-35 (8'P), etc., to produce bio-chemically labeled compounds. (See tracer. isotopic.)

isotope separation The process of separating isotopes from one another.

or changing their relative abundances, as by gaseous diffusson or electromagnetic separation. All systems are based on the mass differences of the isotopes.

' Isotope separation is a step in the isotopic enrich-ment process. (See mass spectrometer.)

isotopic enrichment A process by which the relative abimannees of the isotopes of a given element are altered, thus pro-I ducing a form of the element which has bben enriched in one particular isotope. Example: enriching natural uranium in the uranium-235 isotope. (See ennched matersal. gaseous dsffusson.)

0 K capture The capture by an atomic nucleus of an orbital etec-tron from the first (innermost) orbit or shell.or K.

shell, surrmnding the nucleus. (See atom. capture, electron capture.)

K meson (Ses haon.)

kaon A'n elementan particle (contraction of K-meson). A heavy meson with a mass abcut 970 times that of an electron. (See meson.)

kilo A prefix that multiplies a basic umt by 1000. (See

~

Appendix.)

l

• kiloton energy The energy of a nuclear explosion which is equivalent to that of an explosion of 1000 tons of TNT. (See TNT equsvalent, yseld.)

kinetic energy Energy due to motion.

O label (See tracer. isotopic.)

29

lanthanide series The series of elements beginning with lanth*===,

Element No. 57, and conHmdnt through lutettum, Element No. 71, which together occupy one position in the Pmodic Table of the elements. These are the

" rare earths", which an have chemical properties similar to tanth*== They also are called the "lan-thanides". (Compare octansde setiest see' rare eartha)

(See Appendix.)

lattice An orderly array or pattern of nuclearfuel elements and moderator in a reactor or critical assembly.

Also, the arrangement of atoms in a crystal. (See geometry.)

leakage In nuclear engineering, the escape of neutrons from a reactor core. Leakage lowers a reactor's reactiv-ity. (See neutron economy.)

lepton One of a class of light elementary particles (having small mass). Specifically, an electron, a positron, a neutrino, an antineutrino, a muon or an antimuon.

(Compare baryon. meson.)

lethal dose A dose of ionising radiation suffic'ient to cause death.

Median lethal dose (MLD or LD-50) is the does re-quired to kill within a specified period of time (usu.

ally 30 days) half of the individuals in a large group of organisms similarly exposed. The ID-50/30 for man is about 400 -450 roentgens. (See biologicaldose, roentgen, surs.kal curve, threshold dose.)

licensed material source matmal, special nuclear matersal, or by-product material received, possessed, used or trans.

ferred under a general or special license issued by the Atomic Energy Commission or a state.

light hydrogen Ordinary hydrogen.

light water Ordinary water (H 0), as distinguished from heavy water (D 0).

2 linac Short for linear accelerator.

linear accelerator A long straight tube (or series of tubes) in wtiich charged particles (ordinarily electrons or protons) gain in energy by the action of oscillating electro-m*F"* tic fields. (Compare cycictront see accel-l erator.)

l M

l P

d linear energy transfer (Acronym LET) A measure of the ability of biological material to absorb ions: ag radiationt the radiation energy lost per unit length of path through a biological material. In general, the higher the LET value, the greater is the r41stive biological. effectiveness of the radiation in that material. (See biological dose 'rele-tive bsologtcal effectiveness.)

load factor The ratio of average load carried by an electric power plant or system during a spect!!c period to its peak load during that period. (Compare plant factor.)

e loop A closed circuit of pipe in which materials and com-ponents may be placed to test them under different conditions of temperature, irradiation, etc. If part of the loop and contents are placed in a reactor, it is called an in.psie loop.

low-level analysis A procedure to measure the radioactive content of (low level Counting) materials with very low levels of activity, using son-sitive detecting instruments and with good shielding to eliminate the effects of backsvotosd radiation and cosmic rays. (See cosacidence counting, counter.)

low population zone An area of low population density sometimes required around a nuclear installation. The number and den-sity of residents is of concern in providict, with reasonable probability, that effective protection mes-sures can be taken if a serious accidentsbould occur.

(See exclusson area.)

luminescence Emission of light produced by the action of biological or chemical proceans or by radiation, or any other cause except high temperature (which produces in-candescence). (Compare fluorescence, scintillation; see excsted state, radiolumsnescence.)

l l

magnetic bottle A magnetic field used to confine or contain a plasma

)-

in controlled fusion (thermonuclear) experiments.

(See controlled thermonuclear reaction plasma.)

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l magnetlC mirror A magnetic field used in contrglied fusion expert-ments to reflect charged particles back into the con-l tral region of a magnetic bottle.(Compare psneh of.

fact:see controlled thermonuclear reaction.)

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' Manhattan Project The war Department program during world war a that prodaced the first atomic bombs. The term originated in the code-name, " Manhattan Engineer District", which was used to conceal tk nature of the secret work underway. The Atomic Energy Com-reission, a civilian agency, succeeded the military unit Jan.1,1947.

manipulators Mechanical devices used for safe herwtury W radio-active materials. Frequently they are remotely op-ersted from behind a protective shield. (See hot cell.)

mass The quantity of matter in a body. Often used as a I

synonym for weight, which, strictly speaking,is the force exerted by a body under theinfluence of gravity.

(See atomic mass snett, atomic weight.)

mass defect The difference between the atomic massand the mass number of a nuclide. (See packingfraction.)

l mase energy The statement developed by Albert Einstein, German-nuation born American physicist, that "the mass of a Indy is (m.ss.ene,,y a..asur. of tis on.rgy content, as an e=t.rsion of equivalence) his 1M5 Sped % of ReWty. The statement (mass eng was subsequently veriSed experimentally by mes-surements of mass and energy in nuclear reactions.

relation)

The equation, usually given as: E = me, shows that n

when the energy of a body changes by an amount, E, (no ms.tter what form the energy takes) the mass, m, of the body will change by an amount equal to E/c.

8 8

(The factor c, the square of the speed oflightin a vacuum, may be regarded as tte conversion factor relating units of mass and energy.) This equationpre-j dicted the possitality of releasing enormous amounts of energy (in the atomic bomb) by the conversion of mass te energy. It is alsocalledthe Einstein eguatior mass number [ Symbol A) The sum of the neutrons and protons in a NUCLECS. It is the nearest whole number to an atom's atomic weight. For instance, the mass number of uranium-235 is 235. (Compare atomic number.)

l mass spectrogrtph. Two related devices for detecting and analysingiso-mass spectrometer topes. They separate nucleithathavedifferentcharge-to-mass ratios by passing the nuclei through elec-trical and magnetic fields. (See isotope separation.)

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a matter The substance of which a physical object is com-posed. All materials in the universe have the same inner nature, that is, they are composed of atoms, arranged in different (and often complex) ways; the specific atoms and the specific arrangements iden-tify the various taaterials. (See atom, element.)

maximum credible The most serious ctor accident thatcan reasonably accident be imagined fron. ay adverse combination of equip-ment ms%Mian, operating errors, and other

• ore-seeable causes. The term is used to analyze the safety characteristics cd a reactor. Reactors are designed to be safe even if a mnvimum a:redible acci-dent should cccur.

maximum permissible The amount of radioactive materialin air, water, or concentration (MPC) food which might be expected to result in a maximum permissible dose to persons consuming them at a standard rate of intake. An obsolescent term. Wee radiation protection guide, radioactivity cor. centra-tion guide.)

maximum permissible That dose of ionizing radiation established by cor-dose (MPD) potent authorities as an amount below which there (maximum permissible is no rmmable expectatim of risk to human health, and which at the same time is somewhat below the exposure) lowest level at which a de*Lnite hazard is believed to exist. An obsolescent term. (See radiation protection guide.)

mean free path The average distance traveled by a particle, atom, or molecule between collisions or intertctions. (See collision.)

mee I life The average time during which an atom, an excited nucleus, a radionuclide or a particle exists in a par-ticular form. (See scattering.)

1 median lethal dose (See lethal dose.)

1 mega A prefLx that multiplies a basic unit by one million.

(See Appendtz.)

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megaton energy The energy of a nuclear explosion which is equivalent l

to that of an explosion of one million tons (or 1000 kilotons) of TNT. (See TNT equivalent. yield.)

megawatt day A unit used for expressing the burnup of fuelin a per ton reactor, specifically, the number of megawatt-days of heat output per metric ton of fuelin the reactor.

(See bunup.)

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e meson One of a class of medium-mass, short-lived elemen-tary particles with a mass between thatof the electron and that of the proton. Framples: pi-mesons (psons)'

and K-mesons (kaons). (Compare baryon, lepton.)

Mov One million (or 10 ) electron volts. (Also written as 8

MeV.) Gee electron soft.) (See Appendix.)

micro A prefix that divides a basic unit by one million. Gee Appendix.)

micromicro (See pico.)

milli A prefix that divides a basic unit by one thousand.

(See Appendix.)

moderator A material, such as ordinary water, howy water or graphite, used in a reactor to slow down high-velocity neutrons, thus increasing the likelihood of further fission. (Compare reflector; see absorber, thermal neutrons.)

molecule A group of atoms held together by chemicalforces.

The atoms in the molecule may be identical, as in Hz, S, and S, or different, as in H:0 and COz. A mole-3 cule is the smallest unit of matter which can exist by itself and retain all its chemical proper:1es. (Com-pare atom. ion.)

molten salt reactor A fused-salt reactor.

mt nitor An instrument that measures the level of ionizing ra-diation in aa ntes. (See radiation detection instrument, radiation monitonng.)

multiplication fIctor (Symbol k] The ratio of the number of neutrons pres-for comtant) ent in a reactor in any one neutron generatho to that in the immediately preceding generation. Criticality is achieved when this ratio is equal to one.The

" infinite" multiplication factor is the ratio in a the-otetical system from which there is no leakage, that is, a reactor of infinite size; for an actual reactor 1

(from which leakage does occur), the term effective multiplicationfactor, which is the ratio based tx2neu-trons available after leakage, is commonly used. (See

)

generatnon time, leakage, neutron, reactivity.)

mu meson (See muon.)

34

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muon (Contraction of mu-meson.) An elementary particle.

classed as a lepton (not as a meson), with 2(n times the mass of an electron. It may have asingle positive or negative charge. (See lepton meson.)

mushroom cloud (see atomse cloud.)

mutation A permanent transmissible change in the character.

istics of an offspring from those ofits parents. (Com-pare radiomutation.)

O nano A prefLx that divides a basic unit by one bt111on (109.

l (See Appendix.)

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natural circulation A reactor in which the coolant (usuallywater)ts made reactor to circulate without pumping, that is, by natural con.

vection resulting from the different denstties of its cold and reactor-heated portions.

natural radiation. 6ackground radiation.

natural radioactivity 838 natural uranium Uranium as found in nature, conhining 0.7% of U,

99.3% of assU, and a trace of "U. It is also called normal uransum. (See uransum.)

negative temperature (see temperature coefficient of reactisnty.)

coefficient neptunium seri~es The series of nuclides resulting from the radioactive l

1 sequence) decay of the man-made nuclide, neptunium-237. Many other man-made nuclides decay into this sequence.

The end-product of the series is stable bismuth-209, which is the only nuclide in the series that occurs in nature. (See decay, radioactive; radsoactive senes.)

(See Appendiz.)

neutrino (Symbol y (nu)] An electrically neutral elementary particle with a negligible mass. It interacts very weakly with matter and hence is difficult to detect. It is produced in many nuclear reactions, for example, in beta decay, and has high penetrating power; neu.

l trinos from the sun usually pass right through the earth. (See cosmsc rays. neutron, nuclear reackson.)

35

neutron (Symbol n) An uncharged elementary particle with a mass slightly greater than that of the proton, and found in the nucleus of every atom heavier than by-drogen. A free neutron is unstable and decays with a half-life of about 13 minutes into an electron, pro-ton, and neutrino. Nsutrons sustain the nasion chain reaction in a nuclear reactor. (See fast neutron, in-termediate neutron, and thermal neutron.)

neutron activation, Activation analysis in which neutrons are the acti-analysis vating agent.

neutron capture The process in which an atomie nucleus absorbs or captures a neutron. The probability that a given ma-terial will capture neutrods is measured by its neu-tron capture cross section, which depends on the en-ergy of the neutrons and on thenatureof the material.

(See capture, nuclear reaction, radiative capture.)

neutron density The number of neutrons per cubic centimeter in the core of a reactor. (See flux.)

neutron economy The degree to which neutrons in a reactor are used for desired ends instead of being lost by leakage or nonproductive absorption. The ends may include propagation of the chain reaction, converting fertile to nasionable material, producing isotopes, or re-search. (See leakage, reactianty.)

neutron flux (See 17ax.)

nondestructive Testing to detect internal and concealed defects in testing materials using techniques that do not damage or destroy the items being tested. X rays, isotopic ra-diation and ultrasonics are frequently used.

normal uranium natural uranium.

nuclear battery A radioisotoptc generator.

nuclear energy The energy liberated by a nuclear. reaction (fission i

or fusion) or by radioactive decay iSee decay, radio-actne; fission;]usion; nuclear explosive; nuclear re-actor.)

i nuclear explosive An explosive based on fission orfusion of atomic nuclei. (See dernce, nuclear; nuclear weapons.)

nuclear fission (see fission.)

1 nuclear fusion (See fusion.)

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nuclear power plant Any device, machine, or assembly that converts nu.

clear energy into some form of useful power, such as mechanical or electrhl i,ower. In a nuclear elec-tric power plant, heat produced by a reactor is gen-erally used to make steam to drive a turbine that in turn drives an electric generator.

nuclear reaction A reaction involving a change in an atomic nucleus, such as fission,fusson, neutron capture, or radioac.

Sve decay, as distinct from a chemical reaction, which is limited to changes in the electron structure surrounding the nucleus. (Compare thermonuclear reaction.)

nuclear reactor A device in which a fission chain reaction can be initiated, maintained, and controlled. Its essential component is a core with fissionablefuel. It usually haa a moderator, a reflector, shseldsng, coolant, and control mechanisms. Sometimes called an atomic

" furnace", it is the basic machine of nuclear energy.

(See fission.)

nuclear rocket A rocket powered by an engine that obtains energy for heating a propellant fluid (such as hydrogen) from a nuclear reactor, rather than from chemical'com-bustion. (See Rover.)

nuclear Superheating the steam produced in a reactorby using superheating additional heat from a reactor. Two methods are commonly employed: recirculating the steam through the same core in which it is first produced (integral superheating) or passing the steam through a second and separate reactor. (See superheating.)

nuclear weapons A collective term for atomic bombs and hydrogen bombs. Any weapons based on a nuclear explosive.

(Compare device, nuclear.)

nuclei Plural of nucleus, nucleon A constituent of an atomic aucleus, that is, a proton or a neutron.

~

nucleonics The science and technology of nuclear energy and its applications, nucitus The small, positively charged core of an atom. It is only about '/,,,,, the diameter of the atom but con.

tains nearly all the atom's mass. All nuclei contain both protons and neutrons, except the nucleus of or-dinary hydrogen, which consists of a single proton.

37

nuclide A general term applicable to all atomic forms of the elements. The term is often erroneously used as a synonym for " isotope", which properly has a more limited definition. Whereas isotopes are the various forms of a single element (hence are a family of nu-clides) and all have the same atomic r. umber and number of protons, nuclides comprise all the isotopic forms of all the elements. Nuc*,1 des are distinguished by their atomic number, atomac mass, and energy state. (Compare element, isotope.) (See Appendiz.)

A reactor system in wh'ch the coolant passes through open-cycle reactor i

system the reactor core only once and is then discarded.

(Compare closed-cycle reactor system.)

orange oxide uramum trsoxsde.

Orbit The region occupied by an electrim as it moves about the nucleus of an atom. (See shell.)

organic-cooled A reactor that uses organic chemicals, such as mix-reactor tures of polyphenyls (diphenyls and terphenyls), as coolant.

overpressure The transient pressure over and above atmospheric pressure caused by a shock wave from a nuclear ex.

plosion. (See shoch wave.)

O package power A small nuclear power plant designed to be crated in reactor packages small enough to be conveniently transported to remote locations.

packing fraction The difference between the actual mass of a nuclide and the nearest whole mimher, divided by the mass number, At or (M-AVA. An equivalent statement is that it is the mass defect divided by themass num.

ber. It is positive for most nuclides with mass num-ber less than 12 and more than 180, which therefore tend to be less stable, and negative for most other nucIldes, which tend to be more stable.

pair production The transformation of the kinetic energy of a high-energy photon or particle into mass, producing apar-ticle and its artsparticle, such as an electron and posstron. (Compare son pasr; see mass-energy equsv-alence.)

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parasitic capture Any absorption (as in a reactor) cf neutrons in re.ac-tions which do not cause further fission or the pro-duction of new fissionable material. In a reactor the procesa is undesirable. (See absorption, capture, nen-tron economy.)

parent A radionuclide that upon radioactive decay or dis-integration yields a specific nuclide (the daughter),

either directly or as a later member of a radicac-tive series. (See daughter, radioactive series.) (See Appe'ndix.)

j particle A minute constituent of matter, generany one with a j

measurable mass. The primary particles invotred in radioactivity are alpha particles, beta particles, neu-a trons, and prctons. (Compare antiparticle. photon;see charged partsele, elementary particles, son radia-tion.)

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particle accelerator An accelerator.

i pebble bed reactor A reactor'in which the fissionable fuel (and some-l times also the moderator) is in the form of packed j

or randomly placed pellets, which are cooled by gas or liquid.

Penetrometer A simple device for measuring the penetrating power of a beam of X rays or other penetratingRADIADON by comparing transmission through various absorb-era. (See absorber.)

j period The time required for one cycle of a regularly re-l peated series of events. In a nuclear reactor,it is the l

time required for the power level to change by the factor 2.718, which is known as e (the base of natural i

logarithms). (See Periodic Table.)

Periodic Table A table or chart usting all the elements, arranged in j

y (Periodic Chart) order of tacreasing atomic numbers and grouped by similar physical and chemical characteristics into

" periods". The table is based on the chemical law that the physical or chetnical properties of the ele-ments are periodic (regularly repeated) functions of their atomic weights, first proposed by the Russian chemist, Dmitri 1. Mendeleev, in 1869. (See Appendix.)

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permissible dose (See maximum permsssible dose, radiation pro: ectiOn gusde.)

39

personnel monitoring Determination by either physical or biological mes-

{

surement of the amount of ionizing radiation to which an individual hat been exposed, such as by measuring I

the darkening of a film badgeor performing a radon breath analysis. (Compare radiation monitorxng; see hand andfoot counter.)

i phantom A volume of material approximating as closely as j

possible the density and effective atomic number of living tissue, used in biological esperiments involv-ing radiation.

phosphor A luminescent substance; a material capable of emit-ting light when stimulated by radiation. (See scantil-lation.)

photon The carrier of a quantum of electromagnetic energy.

j Photons have an efective momentum but no mass or electrical charge. (See radiation, quantum.)

pico A prefix that divides a basic unit by one trillion 38 (10 ). Same as micromicro. (See Appendiz.)

pig A heavily shielded cantainer (usually lead) used to ship or store radioactive materials.

pile old term for nuclear reactor. This name was useo because the first reactor was built bypilingup graph-ite blocks and natural uranium.

pi meson (See pion.)

pinch effect In controlled fusion experiments, the effect obtained when an electric current, flowing through a cohmm of plasma, produces a magnetic field that confines and compresses the plasma. (Compare magnetic bot-tie; see controlled thermonuclear reaction, plasma, Shenoood.)

pion An elementary particle (contraction of pi-meson).

The mass of a charged (positive or negative) pion is about 273 times that of an electron; that of an elec-trically neutral pics is 264 times that of an electron.

(See meson.)

plant factor The ratio of the average power load of an electric power plant to its rated capacity. Sometimes called capacsty factor. (Compare loadfactor.)

40

plasma An electrically neutral gaseous mixture of positive and negative ions. Sometimes called the " fourth state of mafter", since it behaves differently from solids, liquids and ' gases. High-temperature plasmas are used in controlledfusion experiments. (See charged particle.)

P!0wshare De Atomic Enec Commission prog 'un of re-search and development on peacert uses of nuclear explosives. The possible uses ir.

fe large-scale excavation, such as for enasta and. Arbors,, ushing ore bodies, and producing heavy transuranic iso-topes. The term is based on a Biblical reference:

Isaiah 2: 4.

T l

plutonium [ Symbol Pu] A heavy, radioactive, man-made, metal-j lic element with atomic num,ber 94. Its most impor-tant isotope is fissionable plutonium-239, producedby neutron irradiatirm of uranium-238. It is used Mr reactor fuel and in weapons. (See Appendix.)

poisoft Any material of high absorption cross sectios that absorbs neutrons unprortuctively and hence removes l

them from the fission chain reaction in areactor, de-creasing its reactittty. (Compare buntable poi.on.)

pool reactor A reactor in widch the fuel elements are suspecded in a pool of water that serves as the reflector, mod-erator, and coolant. Popularly called aswimmingpool reactor, it is usually used for research and training.

(Compare tank reactor.)

port An opealag in a research reactor through which ob.

~

jects are inserted for irradiationor from wtuchbeams of remstina emerge for experimental use.

posttive tsimperature (See temperature coefficient of reactivity.)

coefficient p0Sitron (Symbol $+ (beta-plus)] An elementary particle with the mass of an electron but charged positively. It is the "antietectron". It is emitted in some radioactive j

disintegrations and is formed in pair production by the interaction of high-energy gamma rays with matter. (See antimatter, electron, pasr production.)

I power density The rate of heat generated per unit volume of a reac-tor core. (See specific power.)

41

power reactor A reactor designed to prosce useful nuclear power, as distinguished from reactors used primarily for research or for producing radiation or fissionable materials. (Compare production reactor, research reactor.)

pressure suppression (See vapor suppression.)

pressure tube A reactor in which the fuel elements are located in-reactor side tubes -"M coolant circulating at highpres-sure. "me tube assembly is surrounded by stank con-taining the moderator at low pressure.

pressure vessel A strong-walled container housing the core of most types of power reactors; it usually also contains mod-erator, reflector, thermal shield, and control rods.

(Compare containment vessel.)

pressurized water A power reactor in which heat is transferred from reactor the core to a heat exchanger by water kept under high pressure to achieve high temperature without boiling in the primary system. Steam is generated in a sec-ondary circuit. Many reactors producing electric power are pressurized water reactors.

primary fission fission fragments.

procucts probability (See cross section.)

process heat A reactor that produces heat for se in manufacturing reactor processes.

production reactor A reactor designed primarily for large-scaleproduc-tion of plutontum-239 by neutron irradiation of ura-nium-238. Also a reactor used primarily for the production of radioactive isotopes. (Compare power reactor, research reactor.)

prompt criticality The state of a reactor when the fission chain reaction is sustained solely by prompt neutrons, that is, with-out the help of delayed neutrons. (See criticality.)

prompt neutrons Neutrons that are emitted immediately following nu.

clear fassion, as distinct from delayed neutrons, which are emitted for some time after fission has occurred. Prompt neutrons comprise more than 99%

of fission neutrons. (Compare delayed neutrons.)

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1 prompt radiation Fadhhna produced by the primary fiselon or fusion process, as distinguished from the radiation from fission products, their decay chains and other later reactinna protection Provisicos to reduce exposure of persons to radia-tion. For mmple, protective barriers to reduce external radiation or measures to prevent inh =1stina of radioactive materials. (See radiation protection.)

protective action The absor6ed dose of ionizing radiation to individuals guide (PAG) in the general population which would warrant pro-tective action following a con'-'a**4M event,suchas a nuclear explosion. (See radiation protection guide.)

protective clothing special clothing worn by a radiation worker to prevent enntaminaHno of his body or his personal clothing.

protective survey An evaluation of the radiation hazards incidental to the production, use, or existence of radioactive ma-terials or other sources of rsifistion under a specific set of conditions.

proton An elementary particle with a single positive elec-trical charge and a mass approximately 1837 times

+

that of the electron. The nucleus of an ordinary or light hydrogen atom. Protons are constituents of all nuclei. The atomic number (Z) of an atom is equal to the numher of protons in its nucleus.

proton synchrotron A type of particle accelerator for profucing beams of very high energy protons (in the Bev range).

pulse An electrical signal arising from a single event of

[

l ionissng radiation.

pulse amplifier An amplifier designed specifically to amplify the in-termittent signals of a radiation detection instru.

ment, incorporating appropriate pulse-shaping char-acteristics.

l pulse height The measure of the strength or signal amplitude of a pulse delivered by a detector; measured in volts.

pulse height An electronic circuit which scrts and records pulses analyzer according to height or voltage.

pulse height (see discrimsnator.)

discriminator 43 i

pulse height A circuit designed to select and pass voltage pulses selector in a certain range of amphtudes.

pulsed reactor A type of research reactor with which repeatedshort, intense surges of power and radiation can be pro.

duced. The neutron f7mx during each surge is much higher than could be tolerated during a steady. state operation.

O Q A tmit used to express very large energy figures.

One Q equals 10 (1 billion billion) BTU (British thermal units),

quality factor The factor by which absorbed dose is to be rnultiplied to obtain a quantity that expresses on a common scale, for all ionizing radiations, the irradiation in-curred by exposed persons. (See dose tyvwalent.

distrtbutsonfactor, relatser beologscal effectiveness.)

quantum Unit quantity of energy according to the quantum the.

ory. It is equal to the product of the frequency of radiation of the energy and 6.6256 x 10# org.sec.

The photon carries a quantum of electromagnetic (See electromagnetic radiatsor., radiation )

energy.

(See Planck's constant in Appendia.)

quantum theory The statement according to Max Planck, German physicist, that energy is not emitted or absorbed continuously but in units or quanta. A corollary of this theory is that the energy of radiation is directly proportional to its frequency. (See quantum.)

quench To hmit or stop the electrical discharge inan tonha.

tion detector.

O rabbit A device to move a sample rapidly from one place (such as inside a research reactor) to another place (such as a radiochemistry laboratory). " Rabbits" of'.en consist of small cylinders of aluminum or plas.

I tie, moved by air pressure through a long pipe.

i rad (Acronym for radiation absorbed dose.) The baste l

unit of absorbed does of iontaing radiation. A dose of one rad means the absorption of 100 ergs of radiation energy per gram of absorbing material. (Cornpare rem. vornigen; see absorbed dose.)

44 e

6

O radiation The emission and propagation of energy through matter or. space by means of electromagnetic dis-turbances which display both wave-like and particle-like behavior; in this contest the " particles" are known as photons. Also, the energy so propagated.

Ttte term has been extended to include streams of fastamoving Mticles (alpha and beta particles, free neutrons, cosmic radiation, etc.). Nuclear radiation is that emitted from atomic nuclei in various nuclear reactsons, includag alpha, beta and gamma radia-tion and neutrons. (See electromagnetic radiation, ionizing radiation, qwntum.)

I radiation accidents Accidents resulting in the spread of radioactive ma-terial or in the exposure of individuals to radiation.

i radiation area Any accessible area in which the level of radiation is such that a major portion of an individual's body could receive in any one hour a dose in excess of 5 mt11trem, or in any 5 consecutive days a dose in excess of 150 mt11trem. (See absorbed dose, rem.)

I i

radiation biology (See radiobiology).

radiation burn Radiation damage to the skin. Beta burns result from skin contact with or exposure to emitters of beta particles. Flash burns result from sudden thermal r1At snnn. (See beta particles, flash burn, ionizsng radiation, thermal burn.)

radiation chemistry The branch of chemistry that is concerned with the chemical effects, including decomposition, of ener-getic radiatias or particles on matter. (Compare radiochemistry.)

i radiation damage A general term for the harmful effects of radiation on matter.

radiation detection Devices that detect and record the characteristics of instruments ioming radiatson. (See counter, dassmeter, monster.)

radiation dosimetry The measurement of the amount of radiation de-117ered to a specific place or the amount of radiation that was absorbed there. (See dosameter.)

radiation illness An acute organic disorder that follows exposure to relatively severe doses of inntzing redisHon. It is characterized by nausea, vomiting, diarrhea, blood cell changes, and in later stages by hemorrhage and loss of hair. (See ionszing radiation.)

45 w

radiation monitorlng continuous or periodic determination of the amount of radiation present in a given area. (See monstor.)

radiation protection Legislation and reguistina= to protect the public and laboratory or industrial workers against radiation.

Also measures to reduce exposure to radiation. (Com-pare protectiont see radiatson standards.)

radiation protection The officiallydetermined radiation doses whichshould guide not be exceeded without careful consideration of the reasons for doing so. These standards, established by the Federal Radiation. Council, are equivalent to what was formerly called the maxsmum permssssb.e dose or maxsmum permisssble exposure. (See radso-activsty concentration gusde.)

radiation shielding Reduction of radiation by interposing a shield of ab-sorbing material between any radioactive source and a person, laboratory area, or redtstian. sensitive de-stce. (See absort er, shseld.)

radiation source Usually a man-made, sealed source of radsoactsvity used in teletherapy, radiography, as a power source for batteries, or in various types ofindustria1 gauges.

Machines such as accelerators, and radioisotopic generators and natural radionuclides may also be considered as sources.

radiation standards Exposure standa rds, permissible concentrations, rules for safe bandling, regulations for transporta-tion, regulations for industrial control of radiation, and control of radiation exposure by legislative means. (See radiaison protectson, radiation protectson gusde.)

radiation sterilization Use of radiation to cause a plant or animalto be-come sterile, that is, incapable of reprod. action. Also the use of radiation to kill all forms of life (espe-cially bacteria) in food, surgical sutures, etc. (Com-pare radiatson sliness, radsomutation.)

radiation therapy Treatment of disease with any type of radiation.Orten called radiotherapy.(See brachytherapy. teletherapy.)

radiation warning

'M An officially prescribed symbol (a magenta symbol 4&

trefoil on a yeuow background) which a

should always be displayed when a radia-massus ass tion hasard exists.

I radiations Specific units or types of radiation.

46

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4 radiative Capture A nuclear capture process whose prompt result is emission of electromagnetic rutstian only, as when a NUCLEUS captures a neutron and emits gamma l

rays. (See capture.)

i e'3dio-A prefix denoting radioactivity or a relationship to it, or a relatitunhtp to radiation.

radioactivation activation..

radioactive hhthiting radioactivity or per'sining to radioactivity.

radioactive chain A radioactive series.

radioactive cloud A mass of air and vapor in the atmosphere carrying radioactive debris from a nuclear emplosion. (see atomic cloud.)

radioactive Deposition of radioactive materialin any place where contamination it may harm persons, spoil experiments, or make I

products or equipment unsuitable or unsafe for some specific use. The presence of unwanted radioactive

~~

matter. Also rsdinactive material found on the walls l

of vessels in used-fuel processing plants, or radio-l active material that has leaked into a reactor coolant.

l Gten referred to only as contamination. (Compare i

background radiation; see decontammation.)

radioactive dating A technique for measuring the age of an object or, sample of material by determining the ratios of vart-ous rodsoisotopes or products of radioactive decay it contains. For example, the ratio of carbon-14 to carbon-12 reveals the approximate age of bones, i

pieces of wood, or other archeological specimens that I

contain carbon estracted from tho' air at the time of their origin. (Compare atomic clock; see decay, ra-dioactive.)

radioactive decay (see decay, radioactive.)

' disintegration)

I radioactive fallout (see fallout.)

radioactive halflife (see half-life.)

radioactive isotope A radioisotope.

47 4

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radioactive series A succession of nuclides, each of which transforms by radioactive dismiegration into the next until a stable nuclide results. The first member is called the parent, the intermediate members are called daughters, and the final stable member is called the end product. (See decay, radioactive.)(See Appendix.)

radioactive source A radiation source.

radioactive standard A sample ci radioactive material, usually with a long half-lite, in which the number and type of radioactive atoms at a definite reference time is known. These are used in calibrating radiation measuring equip-ment or for comparing measurements in di!!arent laboratories. (Compare radiation source.)

radioactive tracer A small quantity of radioactive isotope (either with carrier or carrier-free) used to follow biological, chemical or other processes, by detection, deter-mination or localization of the radioactivity. (See carrter; tracer, isotopic.)

radioactive waste (see waste, radioactive.)

radioactivity The spontaneous decay or disintegration of an un-stable atomic nucleus, usually accompanied by the emission of ionizing radiation. (Often shortened to

" activity".) (See decay, radioactive.) (See Appendix.)

radioactivity The concentration of radioactive material in an en-concentration guide vironment which would result in doses equal, over a period of time, to those in the Radiation Protection Guide. This Federal Radiation Council term replaces the former maximum permissible concentration.

radiobiology The boby of knowledge and th study of the principles, mechanisms, and effects of ionizing radiation on living matter.

radiochemistry The body of knowledge and the study of the chemical properties and reactions of radioactive materials.

(Compare radiation chemistry.)

l radioecology ne body of knowledge and the study of the effects of l

radiation on species of plants and animale in natural communities, radioelement An element cnntaining one or more radioactive iso-topes;a radioacttre element.

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radiogenic of radioactive origin; produced by radioactive trans.

formation. (See decay, radioactive; transmutation.)

radiography The use of ionizing radiation for the production of i

shadow images on a photographic emulsion. Some of l

the rays (gamma rays or X rays) pass through the subject, while others are partially or completely absorbed by the more opaque parts of the subject and thus cast a shadow on the photographic film. (Com-pare autorediograph.)

radioisotope A radioactive isotope. An unstable isotope of an ele-ment that decays or disintegrates spontaneously, emitting rnAtation. More than 1300 natural and arti-

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ficial radiaMpaes have been identified. (See decay.

radioactive; isotope.) (See Appendiz.)

radioisotopic A small power generator that converts the heat re-t generator leased during radioactive decay directly into elec-i tricity. These generators generally produce only a I

few watts of electricity and use thermoelectric or thermionic converters. Some also function as electro-static converters to produce a small voltage. Some-times called an " atomic battery". (See decay, radio-active: SNAP.)

radiology The science which deals with the use of all forms of ionizing radiation in the diagnosis and the treatment of disease. (Compare radioactive tracer, radiog-raphy.)

radioluminescenc' visible light caused by radiations from radioactive substances; an example is the glow from luminous paint con *=ining radium and crystals of r.ine sulfide, which give off light when struck by altna particles from the radium. (See luminescence.)

radiolysis The dissociation (or decomposition) of molecules by radidian. Frample: A small proportion of water in a reactor core dissociates into hydrogen and oxygen during operation of the reactor, radiomifnetic Chemical substances which cause biological effects Substances similar to those caused by tonizing redhtinn radiomutation A permanent, transmissible change in form, quality, or other characteristic of a cell or offspringfrom the characterietes of its parent, due to radiation ex-posure. (See genetic effects of radiation, mutation.)

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a radionuclide A radioactwe nuclide.

radioresistance A relative resistance of cells, tissues, organs, or organisms to the injurtous action of radiation. (Com-pare radiosensitteity.)

radiosensitivity A relative susceptibility of cells, tissues, organs or organisms to the injurious action of radiation. (Com-pare radioresistance.)

radiotherapy rodsation therapy.

radium [ Symbol Raj A radioactive metallic element with atomic number 88. As found in nature, the most com-mon isotope has an atomic weight of 226. It occurs in-minute quantities associated with uranium in pitch.

blende, carnotite and other minerals; the uranium decays to radium in a series of alpha and beta emis-sions. By virtue of being an alpha-and gamma-emitter, radiurn is used as a source of luminescence and as a radiation source in medicine and radiog-raphy. (See Appendix.)

redon [ Symbol Rn] A radioactive element, one of the heavi-est gases known. Its atomic number is 86, and its atomic weight is 222. It is a daughter of radium in the uranium radioactis/t series. (See Appendiz.)

radon breath Examination of exhaled air for the presence of radon analysis to determine the presence and quantity of radsurn in the human body. (See personnel momtorsng.)

rare earths A group of 15 chemically similar metallic elements, including Elements 57 through 71 on the Periodic Table of the Elements, also known as the Lanthanide Series. (See lanthanide series.) (See Appendix.)

reactivity A measure of the departure of a nuclear reactor from criticality. It is about equal to the effective multiplication factor minus one and is thus precisely zero at criticality. If there is excess reactivity (post-tive reactivity), the reactor is supercritical and its power will rise. Negative reactivity (suberiticality) will result in a decreasing power level. (See erstical-ity, dollav, excess reactwity, multiplication factor, suberstical assembly, supercritical reactor.)

reactor (See nuclear reactor.)

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l recycling The reuse of fissionable material, after it has been recovered by chemical processmg from spent or de-pleted reactor fuel, reenriched, and then refabricated into new fuel elements. (See fuel cycle, fuel repro-i cessing, spentfuel.)

reflector A layer of materialimmediately surrounding a reac-tor core which scatters back or reflects into the core many neutrons that would otherwise escape. The re-turned neutrons can then cause more fissions and improve the neutron economy of the reactor. Common reflector materials are graphite, beryllium and nat-1 ural uramum. (Compare moderator.)

regulating rod A reactor control rod used for making frequent fine adjustments in reactivity. (Compare sham rod.)

relative biological A factor used to compare the biological effectiveness

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effectiveness <R8E) of different types of ionizing radiation. It is the in-verse ratio of the amount of absorbed radiation, re-quired to produce a given effect, to a standard (or reference) radiation required to produce the same ettect. (See absorbed dose, distribution factor, quality l

factor, rad, rem.)

rem (Acronym for roentgen equivalent man.) The unit of dose of any Lontaing radiation which produces the same biological effect as a unit of absorbed dose of ordinary X rays. The R3E dose (in rems) = RBE x l

absorbed dose (in rads). (Compare curre, roentgen.)

I rep (Acronym for roentgen equivalent physical,) An obso-lete unit of absorbed dose of any ionizing radiation, wtth a matmitude of 93 ergs per gram. It has been superseded by the rad.

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reprocessing fuel reprocessing.

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research reactor A reactor primarily designed to supply neutrons or other ionizing radiation for experimental purposes.

f It may also be use1 for training, materials testing, and production of radioisotopes. (Compare experi-mental reactor, power reactor, production reactor, test reactor.)

1 residence time The time during wnich radioactive material remains l

l in the atmosphere following the detonation of a nu.

I clear explosive. It is usually expressed as a half-time, since the time for all material to leave the f

atmosphere is not well known. (Compare half-life; see fallout.)

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residual nuclear Lingering radiation, or radiation emitted by radio-radiation active material remain +ng after a nuclear explosion.

Residual radiation is arbitrarily designated as that emitted more than one minute after the explosion.

(Compare fallout, initial nuclear radiation.)

resonance The phenomenon whereby particles such as neutrons exhibit a very high interaction probability with nu-j clei at specific kinetic energies of the particles.

Cross sections for neutron capture and scattering, for example, exhibit peaks at these so-called reso-nance energies and have relatively low values be-tween the peaks. (This term is also applied to sev-eral other phenomena in physics.) (See capture, cross section, nuclear reaction, scattenng.)

rod A relatively long, slender body of material used in or in conjunction with a nuclear reactor. It may con-tain fuel, abscrber, or material in which activation or transmutation is desired. (See control rod.)

roentgen [ Abbreviation r] A unit of exposure toionizing radia-tion. It is that amount of gamma or X rays required to produce ions carrying 1 electrostatic unit of elec-trical charge (either positive or negative) in I cubic centimeter of dry air under stamined conditions.

Named after Wilhelm Roer.tgen, German scientist who discovered I rays in 1895. (Compare cune, rad, rem.)

roentgen equivalent. (See rem.)

man roentgen rays X rays.

roentgen therapy Radiation therapy with X rays.

roentgenography Radiography by means of X rays.

Rover A joint program of the Atomic Energy Commission and the National Aeronautics and Space Administra-tion to develop a nuclear rocket for space flight. (See nuclear rocket.)

O Safety rod A standby control rod used to shut down a nuclear reactor rapidly in emergencies. (See scram.)

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4 Scaler An electronic instrument for rapid counting of rsdistion-induced pulses from Geiger counters or other radiation detectors. It permits rapid counting by reducing (by a definite scaling factor) the number of pulses entering the counter. (See counter. Gerger.

Muller counter.)

Scanner (See scannsng, radioisotope.)

Scanning, A method of deterwning the location and amount of radioactive isctopes within the body by measure-radioisotope ments taken with instruments outside the body; usu.

ally the instrument, called a scanner, moves in a regular pattern over the tres to be studied, or over the whole body, and makes a visual record. (Compare wholebody counter; see connesdence countsng.)

Scattefing A process that changes a particle's trajectory. Scat-tering is caused by particle collisions with atoms, nuclei, and other particles or by interactions with fields of magnetic force. If the scattered particle's internal energy (as contrasted with its kinetic energy) i l

is unchanged by the collision, elastic scattering pre-

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vails; if there is a change in the internal energy, the process is called inelastic scattering. (See colliston, Compton effect.)

scavenging in chemistry, the use of a nonspecific precipitate to remove one or more undesirable rad!onuclides from 3

solution by absorption or coprecipitation. In atmo-spheric physics, the removal of radionuchdes from the atmosphere by the action of rain, snow or dew.

(See fallout.)

[

A flash of light produced in a phosphor by an !ONI2-Scintillation ING EVENT. (Comparefluorescence,lumsnescence.)

Scintillation Counter An instrument that detects and measures ionizing radiation by counting the light flashes (scintillations) caused by radiation impinging on certain materials (phosphors).

The sudden shutdown of a nuclear reactor, usually by Scram rapid insertion of the safety rods. Emergencies or deviations from normal reactor operation cause the reactor operator or automatic control equipment to scram the reactor.

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f Seebeck effect The phenomenon involved in the operation of a ther-mocouple. It is named for the German scientist Thomas Seebeck, who first observed the phenome-non in 1822. (See thermocouple.)

seed (See seed core.)

seed tand blanket) A reactor core which includes a relatively small core volume of highly enriched uranium (the seed) sur-rounded by a much larger volume of natural uranium or thorium (the blanket). As a result of fissionsin the seed, neutrons are supplied to the blanketwhere more fission takes place. In this way, the blanket is made j

to turnish a substantial fraction of the total power of the reactor. Also called aspiked core, shell one of a series of concentric spheres, oror6sts, at various distances from the nucleus, in which, accord-l ing to atomic theory, electrons move around the nu.

claus of an atom. The shells are designated, in the order of increasing distance from the nucleus..as the k, l. m, n, o. p, and g shells. The number of elec-trans which each shell can contain is limited. Elec-I trons in each shell have the same energy level and are further grouped into subshells. (See electron cap-ture, K-capture.) (See Appendiz.)

Sherwood The Atomic Energy Commission program for re-search in controlled thermonuclear reactsons.

shield tshieldingi A body of material used to reduce the passage of radiatton. (See barricade shield, barrser shseld, bio-logscal shield, rodsatson shieldsng, thermal shield.)

shim rod A reactor control rod used in =* int infreque 4 coarse adjustments in reactivity, as in startup or shutdown. (Compnre regulatsng rod; see control rod, reactiuly.)

shock wave A pressure pulse in air, water or earth, propagated from an explosion, which has two phases: in the first, or positive phase, the pressure rises sharply to a peak, then subsides to the normal pressure of the surrounding medium; in the second,ornegativephase, the pressure falls below that of the medium, then returns. A shock wave in air usually le called a blast ware.

single-cycle reactor A direct-cycle reactor system.

system 54

Slow neutron A thermal neutron.

)

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Slug A short, usually cylindrical fuel element.

i SNAP (Acronym for Systems for.Welear Andiary Pbwer.)

An Atomic Energy Commission program to develop small anr111sry nuclear power sources for spect21tred space, land, and sea uses. Two approaches are em-ployed: the first uses heat from radioisotope decay to produce electricity directly by thermoelectric or thermionic methods; the second uses heat from small l

reactors to produce electricity by thermoelectric or thermionic methods or by turning a small turbine and electrte generator. (See radioisotopic generator, thermionic conversion, thermoelectric conversion.)

sodium-graphite A reactor that uses liquid sodium as coolant and reactor graphite as moderator.

4 somatic effects Effects of radiation limited to the exposed individual, of radiation as distinguished from genetic effects (which also affect subsequent, unexposed generations). Large radiation doses can be fatal. Smaller doses may make i

j the individual noticeably ill, may merely produce 1

temporary abanges in blood-cell levels detectable h

only in the laboratory, or may produce no detectable effects whatever. Also called physiological effects of l

ta^intton. (Compare genetic effects of radiation; see radiation illness.)

source (See radiation source.)

I source material In atomic energy law any material, except special

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nuclear material, which contains 0.05% or more of uranium, thorium, or any combination of the two.

I (See licensed material, specsal nuclear maternal.)

spark Chamber An instrument for detecting and measuring the paths of ELEMENTARYPARTICLES. It is analogous to the Aloud chamber and bubble chamber. It consists of numerous electrically charged metal plates mounted in a parallel array, the spaces between the plates being filled with an inert gas. Any ioniz ng event causes sparks to jump between the plates along the i

radiation path through the chamber. (Compare bubble chamber, cloud chamber.)

55

Special nuclear In atomic energy law, this term refers to plutonium-material 239, uranium-233, uranium cordatmng more than the natural abundance of uranium-235, or any material artificially enriched in any of these substances. (Com-pare source matersalt see entsched matenal, licensed

• maternal.)

Special ior A theory developed by Amer? Einstein in.1905 that is Restricted; Theory of great importance in atomic and nuclear physics. It of Relativity is especially usefulin studies of objects moving with speeds approaching the speed of light. Two of the results of the theory with specific application in nu-clear physics are statements (a) that the mass of an object increases with its velocity and (b) that mass

• and energy are equivalent. (See mass-energy equa.

tion.)

Species A particular kind of atomic nucleus, atom, molecule or lon; a nuclide.

Specific activity The radioactivity of a radioisotope of an element per unit weight of the eleinent in a sample. The activity per unit mass of a pure radionuclide. The activity per unit weight of any sample of radioactive material.

(See radioactitity.)

specific ionization The number of ion pairs formed per unit of distance along the track of an ton passing through matter. (See ionization, sonissng radiation.)

specific power The power generated in a nuclear reactor per unit mass of fuel. It is expressed in kilowatts of heat per kilogram of fuel. (See power density.)

l spectral shift A reactor design in which a mixture of light water reactor and heatiy water is used as the moderator and cool-ant. The ratio of light to heavy water is varied to change (shift) the speed distribution (spectrum) of the neutrons in the reactor core. Since the probability of neutron capture varies with neutron velocity, a mea-sure of reactor controlis thus obtained.

Spectrum A visual display, a photographic record, or a plot of the distribution of the intensity of a given type of ra-diaison as a function of its wave length, energy, fre-quency, momentum, mass, or any related quantity.

spent (depleted) Nuclear reactor fuel that has been irradiated (used) fuel to the extent that it can no longer effectively sustain a chain reaction. (Compare depleted uraniumt see bunsup.)

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spiked core A seed core.

spill The accidental release of radioactive material, j

spontaneous fission Fission that occurs without an externalstimulus.Sev-eral heavy isotopes decay nainly in this manner; ex-amples: califormum-252 and californium-254. The process occurs occasionally in allfissionable mate-rials, including uranium-235.

Stable Incapable of spontaneous change. Not radioactive.

stable isotope An isotope that does not undergo radioactive decay.

(Compare radioisotope.)

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stopping power A measure of the effect of a substance upon the ki-notic energy of a charged particle passing through it.

(Compare cross section: see absorption.)

strange particles A class of very short-lived elementary particles that decay more slowly than they are formed, indicating that the productionprocess and decay process result from different fundmasental reactions. They include K-mesons and hyperons, i

stress corrosion Chemical corrosion, such as of reactorpressureves-sels, that is accelerated by stress concentrations, either built into or resulting from a load.

subatomic particle Any of the constituent particles of an atom: an elec-tron, neutron, proton, etc.

subcritical A reactor consisting of a mass of fissionable mate-rial and moderator whose ffective multiplicationfac-a assembly tor is less than one and that hence emannt sustain a

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chain reaction. Used primarily for edue*Hans1 pur-l l

pones. (See cvsticality, multiplication factor. reac.

l tienty.)

subcritical mass An amount of fissionable materialinsufficientinquan-tity or of improper geometry to sustain a fission chain reaction. (See entical mass. crsticality.)

l subcritical reactor A subentical assembly.

l supercritical mass A mass of fuel whose effective multiplication factor is greater than one.tSee critical mass, multiplication

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l fac. tor.)

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SUDer0-!*.10a! reactor A reactor in which the effective multiplication factor is greater than one; consequently a reactor that is increasing its power level. If uncontrolled, a super-critical reactor would undergo an excursion. (See ersticality, excursion, multiplicationfactor.)

superneating The heating of a vapor, particularly saturated (wet) steam, to a temperature much higher than the boiling point at the existing pressure. This is done in power plants to improve efficiency and to reduce condensa-t$on in the turbines. (See nuclear superheating )

surface The deposition and attachment of radioacti'.e mate-Contamination rials to a surface. (See radioactive contamination.)

surf a:e :ero (See ground zero.)

survey meter Any portable radiation detection instrument espe-cially adapted for surveying or inspecting an area to establish the existence and amount of radioactive ma-terial present. (Compare counter, monitor.)

sdrviva! Ct:rve Curve obtained by plotting the number or percentage of organisms surviving at a given time against the dose of radiation, or the number surviving at differ-ent intervals after a particular dose of radiation.

(See lethal dose.)

Ewtmming Ocol A pool reactor.

reactor synchrocy:Ictren A cyclotron in which the frequency of the accelerating voltage is decreased with time so as to match exactly the slowmg revolutions of the accelerated particles.

The decrease in rate of acceleration of the particles results from the increase of mass with energy as pre-dicted by the Special Theory of Relatirity. (Compare synchrotron; see cyclotron.)

Syr:Chrct*on An accelerator in which particles are accelerated around a c'ircular patt by radio-frequency electric fields. The magnetic guiding and focusing fields are increased synchronously to match the energy gained by the particles so that the orbit radius remains con-stant. (Compare cyclotron, synchrocyclotron.)

O tag (See tracer. isotopic.)

taiti (See depleted uranium.)

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tank reactor A reactor in which the core is s'tspended in a closed tank, as distinct frord an open poolteactor.These are e

commonly used as research and test reactors. (Com-1 l

pare pool reactor.)

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target Material subjected to particle bombardment (as in as accelerator) or irradiation (as in a research re-

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actor) in order to induce a nuclear reaction; also a nuclide that has been b9.nbarded or irradiated. (See cross section, X ray.)

teaching reactor A research reactor or subcritical assembly.

i teletherapy Radiation treatment administered by using a source that is at a distance from the body, usually employing gamma-ray beams from radioisotope sources. (Com-i pare brcchytherapy; see radiation therapy.)

1 5

temperature The change in reactor reactivity (per degree of tem-coefficient perature) occurring when the operating temperature of reactivity changes. The coefficient is said to be positive when an increase in temperature increases the reactivity, f'

negative when an increase in temperature decreases reactivity. Negative temperature coefficients are de-

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sirable because they help to prevent power excur-sions. (See excursion. reactitsty.)

test reactor A reactor specially designed to test the behavior of 1

materials and components under the neutron and

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gamma fluxes and temperabre conditions of an op.

I erating reactor. (Compare experimental reactor re-search reactor.)

thermal breeder A breeder reactor in which the fission chain reaction i

reactor is sustained by thermal neutrons.

I thermal burn A burn of the skin or other organic materialdue to radiant heat, such as that produced by the detonation of a nuclear explosive. (See flash bem. radiation bum radiation illness.)

thermal column A channel built into some research reactors to supply j

thermal neutrons for experimontal purposes. It con-i sists of a large body of moderator located adjacent to the core or reflector. Neutrons escaping from the reactor enter the thermal colu.nn where they are slowed dawn to thermal energies with velocities of

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about 2200 meters per second. (See thermal neu-tron.)

59 4

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thermat efficiency The ratio of the electne power produced by a power plant to the amount of heat produced by the fuel; a measure of the efficiency with which the plant con-verts thermal to electrical energy.

thermal islow-A neutron in thermal equilibrium with its surrounding neutron mediusa. 'Diermal neutrons are those that have been slowed down by a moderator to an average speed of abopt 2200 meters per second (at room temperature) from the much higher initial speeds they had when expelled by fission. This velocity is similar to that of gas molecules at ordinary temperatures. (Compare fast neutron. sntermediate neutron: see fissson.)

thermal radiation Electromagnetic radiation emitted from the fireball produced by a nuclear explosion. Thirty-five percent of the total energy of a nuclear explosion is emitted in the form of thermal radiation, as light, ultraviolet and inirared radiation.

tnerma' reactor A reactor in which the fission chain react 1or. is sus-tained primarily by thermal neutrons. Most reactors are thermal reactors. (Comparefast reactor, inter-mediate reactor; see thermal neutron.)

tnermal Snield A layer or layers of high density material located within a reactor pressure vessel or between the ves.

sel and the biological shield to reduce radiation heat-ing in the vessel and the biological shield. (See bio-logscal shield. shield.)

thermionic The conversion of heat into electricity by evaporating conversion electrons from a hot metal surface and condensing them on a cooler surface. No moving parts are re-quired. (Compare thermoelectric conversson.)

thermocouple A device consisting essentially of two conductors made of different metals, joined at both ends, pro-ducing a loop in which an electric current willflow when there is a difference in temperature between the two junctions. (See Seebeck effect. thermoelectree conversion.)

thermoeiectric The conversion of heat into electricity by the use of conversion thermocouples. (Compare thermionic copaarsion; see thermocouple.)

tnermonuclear A hydrogen bomb (device).

bomD.Cevicet 60

thermom. clear A reaction in which *ery high temperatures bring reaction about the fusion of two hght nuclel to form the j

nucleus of a heavier atom, releasing a large amount i

l of odergy. In a hydrogen bomb, the high temperstare to initiate the thermonuclear reaction is produced j

by a preliminary fission reaction. (Seefusion, Sher-a wood.)

thorium [ symbol Thi A naturally radioactive element with atomic number 90 and, as found in nature, an atomic weight of approximately 232. The fertile thorium-232 1sotope is shinntant and can be transmuted to fission-able uranium-233 by neutron irtsdiation. (See fertile matenal, transmutation.) (See Appendiz.)

thorium series The series of nuclides resulting from the radioactive (sequence) decay of thortum-232. Many man-made nuclides de-cay into this sequence. The end product of this so-quence in nature is lead-208. (See decay, redso-activet radioactive series.) (3ee Appendix.)

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3 threshold dose The minimum dose of radiation that will produce a detectable biological e#ect. (See absor6ed dose, bio-logical dose.)

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i time of fligtit A dertce for separating and sorting neutrons (or Spectrometer other particles) into categories of similar energy,

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measured by the time it takes the particles to travel a known distance. (Compare mass spectrometer.)

TNT equivalent A measure of the energy released in the detonation of a nuclear explosive expressed in terms of the weight of TNT (the chemical emplostwe, trinitrotoluene)which 4

would release the same amount of energy when ex-l ploded. It is usually expressed in kilotons or mega-tons. He TNT equivalence relationship is based on the fact that 1 ton of TNT releases one Milian (10')

f calortes of energy. (See kiloton energy, megaton es-ergy, yield.)

i toit enrichment A proposed arrangement whereby privately owned i

uranium could be enriched in uranium-235 content in government facilities upon payment of a service Charge by the owners. (See isotopic enrichment.ura-

.I nium.)

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tracer, isotopic An isotope of an element, a small amount of which may be incorporated into a sample of material (the carrier) in order to follow (trace) the course of that element through a chemical, biological or physical process, and thus also follow the larger sample. The tracer may be radioactive, in which case observations are made by measuring the radioactivity. If the tracer is stable, mass spectrometers, densitymeasurement, or neutron activation analysis may be employed to determine isotopic composition. Tracers also are called labels or tags, and materials are said to be labeled or tagged when radioactive tracers are in-corporated in them. (See carner, radioactis/e tracer.)

transforthation. transmutation.

nuclear transmutatior The transformation of one element into another by a nuclear reaction or series of reactions. Enmple: the transmutation of uramum-238 into plutonium-239 by abscrption of a neutron.

transplutonium An element above plutomum in the PERIODIC TABLE element that is, one with an atomic number greater than 94.

(See transuranic element.)

transuranic element An element above uranium in the PERIODIC TABLE, (isotope; that is, with an atomic number greater than92. All 11 transuranic elements are produced artificially and are radioactive. They are neptunium, plutomum, americium, curium, berkelium, californium, einstel-nium, fermium, mendelevium, nobellum, and law.

rencium. (See Appendiz.)

a transuranium. A transurante element.

element triage The process of determinine which casualties (from a large number of persons exposed to heavy radiation) need urgent treatment, which ones are well enough to go untreated, and which ones are beyond hope of benefit from treatment. Used in medical aspects of civil defense.

trit!Um A radioactive isotope of hydrogen with two neutrons and one proton in the nucleus. It is man-made and is heavier than deuterium (heavy hydrogen). Tritium is used in industrial thickness gauges, and as a labelin experiments in chemistry and biology. Its nucleusisa triton. (Compare deutersum; see hydrogen.)

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triton The nucleus of a tritium (810 atom. (See hydrogen, trattum. )

O U 235 Uranium-235 (See uranium.) (See Appendix.)

unstable isotope A radioisotope. (Compare stable isotope.)

uranium [ Symbol Uj A radioactive element with the atomic number 92 and, as found in natural ores, an average atomic weight of approximately 238. The two prin.

cipal natural isotopes areuranium 235 (0.7% of naf.

ural uranium). which is fissionable, and uranium-238 (99.3% of natural urantum) which is fertile. Natural uranium also includes a minute amount of uranium.

234. Uranium is the basic raw material of nuclear energy. (See fertile matertal, fisssonable material, natural uranium.)(See Appendiz.)

uranium enrichment (See isotopic enrichment.)

uranium (Symbol UFe] A volatile compound of uranium and hexafluoride 11uorine. UFs gas is the process fluid in the gaseous diffuston process. (See isotope separation.)

uranium series The series of nucilies resulting from the radioactive (sequence) decay of uranium-238, also known as the uranium-radium series. The end product of the series is lead.

206. Many man-made nuclides decay into this so-quence. (See decay, radioactive: radioactste s trtes.)

(See Appendiz.)

uranium [ Symbol UFa] A solid green compound called green tetrafluoride salt. An intermediate product in the production of uranium hexafluoride. (See uranium hexa /7uoride.)

uranium trioxide (Symbol UO ] An intermediate product in the refining 3

of uranium, also called orange oxide.

use Charge An annual rental charge assessed by the Atomic En-ergy Commission for inventories of enriched fission-able material.

63

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V3n de Gr3aff An electrostatic machine inwhich electric 211ycharged generator particles are sprayed on a moving belt andcarried by it to build up a high potentia 1on an insulated terminal 4 accelerator:

Charged particles are then accelerated along a dis-charge path through a vacuum tube by the potential difference between the insulated terminal and the op-posite end of the machine. A Van de Graaff accelera-tor is often used to inject particles into larger ac-celerators. Named after R. S. Van de Graaff, who invented the ddvice in 1931^. (See accelerator.)

vapor suppression A safety system that can be incorporatedin the design of structures housing water reactors. In the system, the space surrounding the reactor is vented intopools of water open to the outside air. If surges of hot vapors should be released from the reactor in an accident, their energy (pressure) would be dissipated in the pools of water. Gases not condensed would be scrubbed clean of radioactive particles by the bub-bling. Another system uses a suppression pool in a separate pressure vessel that can be vented through a stack. Also called pressure suppression. (Compare pressure vessel.)

void coefficient A rate of change in the react:rity of a water reactor system resulting from a formation of steam bubbles as the power level and temperature increase.

O waste radioactive Equipment and materials (from nuclear operations) which are radioactive and for which there is no fur-ther use. Wastes are generally classified as high-level f,baving radioactivity concentrations of hundreds to thousands of curies per gallon or cubic foot), low-level (in the range of 1 microcurie per gallon or cubic foot), or intermediate (between these extrerr.es).

(Compare fissiors products.)

water boi;er A research reactor whose core consists of a small metal tank filled with uranium fuelin an aqueous so-lution. Heat is removed by a cooling coilin the core.

Not to be ce tused with boiling water reactor.

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I Reactor criticality achieved Mth the coolant present.

wet criticahty (Compare dry enticality.)

A device used to identify and measure the radiation whole body counter in the body (body burden) of human beings and ani.

mals; it uses heavy shielding to keep out background radiation and ultrasensitive sciott11ationdetectors and (Compare scanner; see body electronic equiprnent.

burden.)

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form of electromagnetic radiation A penetrating X ray emitted either when the inner orbital electrons of an excited atom return to their normal state (these are characteristic X rays), or when a metal target is speed electrons (these ara bombarded with high bremsstrahlung). X rays are always nonnuclear in origin. (Compare bremsstrahlung, gamma rays; see excsted state.)

O The total energy released in a nuclear explosion. It yield is usually expressed in equivalent tons of TNT (the quantity of TNT required to produce a corresponding amount of energy).14w yield is generally considered to be less than 20 kilotons; low intermediate yield from 20 to 200 kilotons; intermediate yield from 200 kilotons to 1 megaton. There is no standardized term to cover ytelds from 1 megaton upward. (Compare ftsston yseld; see TNT equsvalent.)

O Z The symbol for atomic number.

An experimental reactor operated at such low power Zero power reactor levels that a coolant is not needed and little radioac-tivity is produced. (Compare subcntical assembly.)

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OTHER GLOSSARIES Popular-level glossaries available include the following:

101 Atomic Terms and What They blean. Esso Research and Engineer.

ing Company, P. O. Box 172, Linden, NewJersey 07036,1964, 20 pp.,

free.

Glossary of Atomrc Terms. Technical Writers' Section, Public Rela.

tions Branch. Unsted Kingdom Atomic Energy Authority, London, 1966, 62 pp., 3 shillings 6 pence (30.42).

More detailed and more technical definitions and definitions of a more comprehensive list of terms may be found in other bocks, such as the following:

Atomsc Energy Deshbook, John F. Hogerton, Retnhold Publishing Cor.

poration, New York 10022,1963, 673 pp., $11.00.

Atomtc Energy Encyciopedia sn the Lsfe Sciences, Charles Wesley Sch111mg, editor and major contributor, W. B. Saunders Company, Philadelphia, Pennsylvania 19105,1964. 474 pp., $10.50 Conesse Dictionary of Atomses. Alfred Del Vecchio (Ed.), Philosophical Library, Inc., New York 10016,1964, 262 pp., 56.00. (Out of print but avallable through ILbraries.)

Newnes Concise Encyclopedna of Nuclear Energy. D. E. Barnes et al.,

advisory editors, John Wiley and Sons. Inc., New York 10016, 1962, 88", pp., $25.00.

Sourceboch on Atomic Energy (third edition), Samuel Giasstone, D. Van Nostrand Company, Inc., Prmceton, New Jersey 08540,1967,883 pp.,

39.25.

Glossary of Term s Frequently Used in Nuclear Physses. compiled by Dr. Robert L. Stearns, American Institute of Physics, New York 10017,1961, 37 pp., 31.00.

Glossary of Terms Frequently Used t., Hugh Energy Physses compiled by Dr. Allen M. Sachs and Dr. Melvm Schwartz, American institute of Physics, New York 10017,1961, 20 pp., 31.00.

66 G

. ~. _

i APPENDIX RECOMMENDED UNIT PREFIXES The following urut prefixes are the ones adopted by the International Committee on Weights and Measures.

Muluples and submultiples.

Prefixes Symbols Pronunciation 1 028 ters T

ter's 19 pp*

G fp(&

los mess M

me los kilo k

kn'6 108 hecto h

h4k't3 10 deka da dek'i 10*1 deet d

des'!

10*8 conti c

sen't!

10*8 milli m

mI1*ll micro g (mu) m!'kr8 10d 10*8 nano a

rin'$

10" 8 picot p

p4'k8 10-15 femto f

fem't8 10-e atto a

It't8

• Also beva (symbol B pronounced bFrai.

fAlso micromicro (symbol ms.

67 l

APPENDIX A NOTE ABOUT NUMERICAL ABBREVIATIONS Numerical abbreviations used in nuclear science are likely to be composed of two elements; first, an abbreviation of a numerical pre-fix expressing some multiple or fraction of unity, and second, an ab-breviation of a unit which measures some basic property. Examples of both elements are:

PRET!XES Prefts Meaning pico divide by 1 trillion (10-13; nano divide by 1 bulion (10*8) micro divide by 1 multon (10")

milli divide by 1 thousand (10*8) s kilo muluply by 1 thousand (lo )

8 msga multiply by 1 million (10 )

gtga muluply by I bullon (10')

UNITS (See proceding pages for definiuons)

Unit Abbreviation Measured Property angstrom 1

length of radlauon barn b

crosa section curte e

radioactivity electron volt ev energy gram g

mass meter m

length rad rad radiacon absorbed dose roentgen r

radlauon dose rem rem radlauon dose second see time toe t

nuclear weapon energy in TNT equivalent watt w

power Knowing the two ingredients, it is easy to understand or to employ numerical abbreviations. Fnmples:

Abbrevlauon Full Term Meaning i

mb millabern One thousandth of a barn uc mierecurie One millionth of a curte kt kiloton One thousand tons of TNT equiv-alent l

OS l

r

i APPENDIX CONSTANTS The following values are supplied as useful reference values for stu-dents, as recommended by the National Academy of Sciences-National Research Council, and adopted by the National Bureau of Standards:

Values Constant symbol Deftastion 2.997925 x 10'8 Speed of light c

contimeters/ sec.

88 Avogadro number N

Number of molecules 6.02232 x 10 in vacuum in one gramemolec-ular weight of a sub.

etance.

9.64870 x to' Faraday constant F

Quantley of electrtetty to free chemical coulombe equhalent weight of a substance (in electrolyste).

Energy of quantum of 6.62536 = 10-If Planck constant h

radiauon in relation erg-sec.

to frequency of source.

4.80298 w 10*H Elementar; charge e*F/N Electric charge on one e.s.u. (electro-electron.

stauc unitss.

Electron rest mass m.

9.1091 x 10*H gram Proton rest mass m,

1.67252 x 10-88 gram 69 1

~

APPENDIX NUCUDE DESIGNATION (SUBSCRIPTS AND SUPERSCRIPTS)

In accordance with recommendations of the International Union of Pure and Applied Chemistry, the following designations are used for nuchdes:

The AIASS NUMBER of a nuclide is placed as a supersenpt to the left of the symbol for the chemical element of the nuclide, rather than to its right, as formerly; for example, "N, rather than N" for nitrogen-14.

The ATOACC N03fBER is placed as a left subsenpt; for example, 8N for carbon-14, or 5U for uranium-235.

8 The state ot 10N!ZAT10Nis shown as s nght supersenpt; for exam-ple, Ca** or sos.

The number of NEUTRONS in the nucleus is shown as a rs'gM sub-senpt; for example, NCase for the isotope of calcium-40 containing 20 protons (its atomic number) (left subscript), and 20 neutrons (right subscript) in its nucleus.

Excited states are shown either as part of theleft superscript, or sometimes the nght supersenpt; for example: "'"Ag or "'Ag" indi-cates an excited state of a silver-110 nucleus; He* indicates an excited state of a helium atom.

Mass tenustum numtier 40

++

Cs 20 - 20 Atermc pawntier of number neutrons

-Symbol for chormcal element i

I l

i l

l 70 i

2--

e PERIODIC TABLE OF THE ELEMENTS T

g I

He 5m H

5 6

7 8

9 10 2

3 4

B C

N O

F h

O 13 14 15 17 18 X

U h

11 12 N

S P

S O

k Na Mg 19 20 21 22 23 24 25l26 27 28 29 30 31 32 33 34 35 36 K

Ca Sc Ti V

Cr Mn. Fe Co Ni Cu Zn Ga Ge As Se er Kr 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 Rb Sr Y

Zr Nb Mo Tc Ru m

Pd Ag Cd in Sn Sb To I

Xe I

12 13 74 75 76 il 78 79 80 81 82 83 84 85 86 5Ij.I 55 56 Hf Ta W

Re Os Ir Pt Au Hg Tl Pb h

Po At Rn g

Cs 84 Sergg5 89-103 87 88 Fr Ra Series

' lanthanide 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 Series La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu 1 Actinide 89 90 91 92 93.

94

' 95 l 4r '9T

'.48 1 !99-100 101 log

!!0M Series Ac Th Pa U

Ng N

61 Cag

'Ob

~Cf R

Fm' led No Lr-14e actinide senses of elements as a gnoop occupees a ssngle Transuranssue elements are shouw sn shaded squares.

l the larger s hael.

square en the nease Iqure. the tanthansde series of elements also occupees a sing e square se U

4 e

e APPENDIX ALPHABETICAL LIST OF ELEMENTS AND SYMBOLS Agente Asense Asemas Atomne Elemem Symmel summer wenght*

Element symbol number *elght*

Astaasusa Aa 89 227 Molytmeaman Me 42 95.95 Alemanum Al 13 28.90 Needymaam Ed 60 164.24 Amernesem Aan 95 243 Neoa Ne 16 20.182 Aatamony St

$1 121.75 Newmaaum bp 93 237 Argos Ar 18 39 942 Nickel N6 20 88.71 Areenae As 33 74.91 Niettum Assasaae At SS 110 aCoiumatum)

Nt 41 92 91 Berham

== Ba 64 137.35 Nitroges N

7 14.0C7 Bernetaum Ba 97 24e Nomeaum No 102 254 Beryllsusa Be 4

9.013 Osmaum Os 76 190.2 Bismuth 31 83 204.99 Oavsee O

8 15.999 Boroa B

b 10.82 Palladame Pd 44 106.4 Bromune Br 35 79.913 Phoopmerus P

15 30.973 Cadstum Cd to 112.40 Platsaiam Pt 76 195 00 Caletusa Ca to 40.00 Plutonsum Pu 94 242 Caltforams:

Cf 80 251 Pelossum Po 64 210 Carmen C

6 12.610 Potaaema K

19 39.090 Carma Ce 58 140.12 Praaeodemum Pr 59 140.91 Ceeiam Ce SS 132.90 Promeenum Pm 41 147 Chiertae C1 17 35.455 Protaeumsum Pa 91 231 Chromsma Cr 24 52.01 Radium Da st 226 Comaat Ca 27 58.94 Rados Ra 66 222 Copper ce 29 63.54 Rheasum Re 75 194.21 Curium Ca 96 247 Rhodium Rh 45 102.90 Dyspressur Dy se 162.50 Rubwhum 39 37 65.44 Esastanasua Ee 99 254 Ruthensum Ru 44 101.1 Er1>tums Er le 167.26 Samarnum 5m 62 150.34 Eurostam Eu 43 152.0 Scaadsum Se 21 44.94 Fermium Fm 100 253 Seienmm Se 34 78 to Fluertae F

9 19.00 Salicom 5:

le 29 09 Fraaema Fr 87 223 Silver Ag 47 107.075 Gadokaasum Gd 44 157.25 Sodium ha 11 22.990 GaJhua Ga 31 49.72 Strontium '

5r 38 07.63 Germatma Ge 32 72.40 Sunfur 5

le 32.064 Gold Ais 79 197.0 Tantalum Ta 73 100.94 Mafatum Kf 72 179.49 Technetaan te 43 99 Mels.st Me 2

4.003 Tellurium Te 52 127.40 Heimium Ho 47 164.93 Terhum Tb 65 155.92 Hydroges

• N 1

1.0079 Thallium Tl 81 204.38 ladaum la 49 114.31 Thortum Tn to 232.04 lodine 1

53 126.90 Thultum Tm 148.93 tridium Ir 77 192.2 Tia la 50 119.89 Iron Fe 26 53.a5 Titanium Tl 22 4*.90 Krypton Kr 34 83.se Tungsten Laatassum La 57 130.91 1%eifraal W

74 193.89 Lawressme Lt 103 257 Ursamm U

92 230.06 Lead Pt 32 207.20 Wadium V

23 50.95 Litkaum Le 3

4.940 Xenon Xe 54 131.29 Lutenum Lu 73 174.9s Ytterteum Tb 70 173.03 14agesenum Mg 12 24.32, Yttrium Y

39 89.92 Massaaeee Ma 75 54.94 Zone Za 30 65.39 Messeleviens Md 101 254 Zareenum Zr 40 91.22 Mercury Ng 60 209.60

• Atenas seigns of the most asundant er best asowa isotope, or na the case of radioneuve lectopeel the Asotope wat the icagest half-life, resatave to stemte wetgtt of Cartoa*13 e 12.

72 6p 9

g A6b a-

e APPENDIX THE TRANSURANIUM ELEMENTS Atomic Atomic Atomic Atomic nenber Dement Symbol weight

• number Dement Symbol wetsht*

93 Neptuntum Np 237 99 Einsteinium Ee 254 94 Plutonium Pu 242 100 Fermium Fm 253 96 Americtum Am 243 101 Mendelevium Md 256 96 Curium Cm 248 102 Nobellum No 254 97 Berketh a Bk 249 103 f.awreactum Lr 257 98 Califoratum Cf 249

• Mase number of longest-lived or more available isotope.

O e

T 73 l

t

APPENDlX ISOTOPES OF SOME OF THE ELEMENTS

• Element isotopes Ofass Numbers)

Hydrogen

1. 2 J Helium

4. 3, 6 Llthium 7, 6, 8, 9 Carbon 12,13. Ie,11,10,15 Nitrogen 14, 15,13, 16, 17, 12 Oxygen 16, 18, 17, 15, 14, 19 Fluorine 19,18,17,20,21 Sossum 23, R. 24,25,21,20 hagnesium 24, 26, 25, 28, 27, 23 Aluminum 27, 26, 29, 3. 25, 24 Sulfur 32, 34, 33, 36 J5, 37, 31 Chlorine 35, 37, J6, 39, 38, JJ, J4, J2 Potassium 39,41 ee,4J,42,44,38,J7 Calcium 40, 44, 42, 48, 43. 46, 41,45,47, 49, 39 Iron 56, 54, 57, 58, 55, 5 9, 52, SJ Cobalt 59.60,57,56,54,55,61,62,34 Nickel 58, 60, 62, 61, 64, 59, 6J, 66, 57, 65, 56 Copper 63, 65, 67,64,61, 60, 62, 58,66, 68 Zinc 64, 66. 6 8, 67, 70, 65, 72, 62, 71, 6 9, 6J Bromine 79, 81, 77, 82, 76, SJ, 75, 74, 84, 80, 78, 85, 87, 88 SL1ser 101,109,105,106, lit,123,112,10J,104,115, 100, 114, 110 Tin 120, 118, 116, 119, 117, 124, 122, 112, 114, 115, 13, 113, 125, 121, 106, 127, 1M, 111, 109.

lodnne 127, 129, 125, 1M, 131, 124, 1J3, 123, 1J0, 1J5, 132,121,134,128,122,137,118,1J9 16artum 138, 137, 136. 135, 134, 130, 132, 133, 140, 1J1, 128,129,126,141,142,14J Platinum 195, 194, 196, 190, 192 I90, 188, 191, 197, 189, 187,199 Gold 197. 195.196.199,1N,1N,19J,192,191, 200, 189,201,187,20J Mercury 202, 200.199. 201,198, 204,196, 20J,197,195 192,193.191,159,205 Lead 208, 206, 207,204, 202, 210, 203, 200, 212, 201, 209,199. 211,3ie,190 Bismuth 209. 3 Io, 207, 205. 206, 204, 20J, 201, 202, 2 8 3, 21J 200,199,3Ie,tI5,190,3II Radon 3 3 2. 211, 210, 209, 221, 212, 208, t to 2 69. 218, 217, 216, 215 Radium 3 E s 3 3 4,225, 3 3 3, 2 x e. 227, 213, 222, 221, 220, 219 Thoriumt 2 3 2, 223, 2N, 225, 2J6, 3 27, a t 8, 229, 2 30, t a l, 23J,234 Uranium 2 3 4, 2 a s. 2 s e, 236, 233, 22', 230, 2J7, 2J1, No, l

229,239,228, M7 5eptunnum 2J7, 2J6, 2J5, 2J4, 239, 2J8, 240, 231, 2JJ, 241, 232 74 I

I i

Isotopes (Mase Numbers)

Element 244,242,2J9. J40,28. 4J. 2Jd. 2Jf. 23. 243.

Plutonium 234. 243, 232. 233 243. 241. 242, 240, 239, 238. 245, 237. 244* 244 Amettatunt

23. 243. 246,243. 244,242. 24f. 241. 240* 238 J4 f, 249,243, 246, 248. 244, 24J. 250 Curtumt Berkeliumt 251, 249, 250, 232, 240, 234. 253. 246. 247. 243*

CalLforakunt 244 202.200.

264. 293. 245,246,240,249. 250. 231e ELantekniumt 257,23J,232.255,244,249 M JJ. 254. 23d 2M Tormtumt JJd. 23J Mendelovtum Nobellumi 254.JJJ.256 JJ7 Lawreactum es

• Stable isotopes La ordinary type. Naturally radioactive isotop inboldface. Other radioisotopes la statics. Naturalisotopes given j

h in order of abundance. All other isotopes given ta ottier of lengt of half-life.

tNot Listed la order of length of half-life.

f f

I l

75 i

i 4

e APPENDIX RAD 10ACTNE DECAY The Actinium Series Radiation Element Symbol emitted Half life s

Uranium mU a

7.13 m lo years Thornum tatTh 28.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> Protactinium WPa a

3.43 x 10' years f#

8 Wc 21.8 years A

Actinium

• g Thorium mTh a

18.4 days Franctum mFr A

21 minutes Radium mRa a

11.7 days Radon 8"Rn a

3.92 seconds

,10 1.83 x 10-s second Polonium.

mpo

,g 14ad IliPb A

36.1 minates Astatine 818At a

~10" second Bismuta' 81881

• 3 2.16 minutes 33 Polonium 811Po o

0.52 second Thallium mT1 4.78 mimites 14ad NPb Stable

' Undergoes both alpha and beta decay, la definite proportice to decay events, as shown.

The Thorium Series Radiation Element Symbol eautted Half life Thorium 288Th a

1.39 w 10H years Radium mRa A

6.7 years Actinium usAc d

613 hours0.00709 days <br />0.17 hours <br />0.00101 weeks <br />2.332465e-4 months <br /> Thorium usTh a

1.91 years Radium

• Ra a

3.64 days Wn a

52 seconds R

Radon Polonium 218 Po a

3.16 second Lead MPb 3

10.6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> f466.3 Bismuth

• mB1 60.5 minutes g

3 Polonium tispo a

3 x god second Thallium 2"Tl A

3.1 minutes Lead 2#Pb Stable

• Undergoes both alpha and beta decay. in definite proportion to the decay events, as shown.

76 i

I

a The Neptunium Series Radiation Element Symbol emitted Half life Plutonium 84iPu A

13.2 years Americium 881Am a

442 years 8

Neptuntum 88'Np a

2,20 w 10 years Protactinium n Pa 27.4 days 8

Uranium 888 U a

1.62 x 10 years 7.34 m 10s years Thortum D*Th a

Radium D8Ra J

14.6 days Actinium.

usAc a

10.0 days Franctum u Fr a

4.8 minutes 1.8 w 10-8 second tttAt a

Astatine f#

47 minutes Bismuth

• 8DBi 33 d second Polonium itsPo a

4.2 w 10 Thanium 8*T1 3

2.2 minutes Lead 8*Pb J

3.32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br /> Bismuth 8*B1 Stable

• Undergoes both alpha and beta decay La definite proportion to decay events. as shown.

The Uranium Series Radiation Element Symbol emitted Half life '

8 Uranium 888U e

4.51 = 10 years Thorium 83*Th 3

24.1 days Protactinium

• 88'Pa 1.18 minutes s

Uranium

1. 8U a

2.48 w lo years 8.0 =108 years Thortum 88'Th a

Radium z2 era a

1.62 = 10 years 2:2Rn a

3.82 days Rados 3' 08 "'8"*

Poloalumt tispa 0.0M)

!.and 31*Pb A

26.8 minutes 2 seconds Astarin.

itsAt a

f0 19.7 minutes Bt'smuth?

818B1 g

1,6 w 10-* second Polonium 81*Po a

Thallium st*T1 3

1.32 minutes 818Pb A

19.4 years Lead 5.0 days Bismutht 81'Bt

, gg)

Polonium 81'Po a

139.4 days Thallium 8*T1 A

4.20 minutes Lead 888Pb Stable

• Protacttatum also undergoes a process of isomeric transition ts 0.12% of its decay events. The resulting tsomer of 888Pa has a lower energy state. It then undergoes beta decay. with a half-life of 6.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />, to formasag, tUndergoes both alpha and beta decay. ta definite proportion to the decay events, as sh 17

\\

O

=

APPENDIX ELECTRONIC ARRANGEMENT OF THE ELEMENTS She!As K

L M

N O

P Q

Sub 1Avels la 2s 27 34 2p 3d 4a op 4d V ' Sa Sp Sd 5/ 6s 6p Gd 6f Ta 1 Hyerages 1

2 Holtam 2

3 Linhaum 2 1 4 Berytime 2 2 8 Borce 2 2 1 0 Cartes 2 2 2 7 Nitrogen 2 2 3 4 Osyges 2 2 4 9 Fluerase 2 2 &

10 Neon 2 2 6 11 So6mm 2 2 4 1 12 Magnesium 2 2 6 2 13 Alumamsa 2 2 6 2 1 14 5 incee 2 2 6 2 2 ES Phospeorus 2 2 6 2 3 le Sulfur 2 2 6 2 4 17 Chlorine 2 2 4 2 3 16 Argoa 1 2 6 2 6 19 Potasenum 2 2 4 2 6 1

20 Calesum 2 2 6 2 6 2

21 Scandamm 2 2 6 2 6 1 2 22 Titaamm 2 2 6 2 6 2 2 23 Vanad=m 2 2 6 3 6 3 2 24 Chromium 2 2 4 2 6 5 1 23 Manganese 2 2 6 2 4 8 2 26 Iroe 2 2 4 2 6 6 2 27 Cobalt 2 2 6 2 4 7 2 24 Machel 2 3 4 3 4 4 2 29 Copper 2 2 6 2 6 10 1 30 Zane 2 2 6 2 6 le 2 31 Galbum 2 2 4 2 6 10 2 1 22 Germannuan 2 2 6 2 6 10 2 2 33 Areesse 2 3 4 2 6 10 2 3 34 Setessen 2

2 6 2 6 10 2 4 35 Brosaame 2 2 6 2 6 10 2 8 34 Krypten 2 2 6 2 4 10 2 6 27 hbadtuas 2 2 6 2 6 10 2 e 1

36 Straatum 1

2 6 2 6 10 2 4 2

39 Yttrium 2 3 4 2 6 10 2 6 1

2 40 Zircomum 2 2 6 2 6 to 2 6 2

2 41 Nacetum 2 2 6 2

6, 10 2 6 4

1 42 Molybdenum 2 2 4 2 6 le 2 6 5

1 43 Tectaettum 1 2 4 2 6 to 2 6 4

1 44 Rutheanum 2 2 6 2 6 10 2 6 7

1 45 Rha6 sum 2 2 6 2 6 10 2 4 6

1 46 Palladam 2 2 6 2 6 10 2 6 10 47 56tver 2 2 6 1

.6 to 2 6 10 1

i 46 Caensum 2 2 6 2 6 10 2 6 10 2

l 49 Indam 2 2 6 2 6 10 2 6 10 1 2

$0 Tia 2 2 4 2 6 10 2 4 to 2 2

[

31 Antamony 2 2 6 2 6 to 2 6 to 2 3 l

52 Tehtaam 2 2 4 2 6 10 2 6 10 2 4 78 l

l

\\

l i-l

D Stella K

L M

N O

P Q

Sue.I4vete is 2s 2p 3s 3p w as op 4d y is 5p k y es 47 ed V is

$2 ledase 2 3 4 2 4 10 2 4 10 2 3 34 Xenes 2 2 4 2 e 10 2 6 to 2 e SS Conson 2 3 4 2 6 to 2 6 to 2 4 1

Se Barmen 2 3 e 2 e to 2 6 to 2 e 2

37 tasataman 3 2 6 2 e to 2 4 10 2 e 1 2

Se Certum 3 3 4 3 e to 2 4 to 2 2 e 2

30 Pressesymamm 2 2 4 2 e le 2 e le 2 2 4 2

64 Needymium 2 3 4 2 6 to 2 6 10 4 2 6 2

61 PromeJuum 2 2 6 2 6 10 2 6 10 3 2 4 2

42 Samartum 2 2 8 2 4 to 2 4 10 8 2 4 2

63 Europmm 2 3 4 2 6 to 2 6 10 7 2 4 2

64 Cadenansum 2 2 0 2 4 to 2 4 to 7 2 6 1 2

45 Teresum 2 2 8 2 4 to 2 4 10 9 2 6 2

64 Dysprostum 2 3 e 2 6 to 2 6 to 10 2 4 2

47 Heimaum 2 2 0 2 4 10 2 6 10 11 2 4 5

Se Etteum 2 2 6 2 6 10 2 e 10 12 2 6 2

69 Tbullum 1 2 6 2 6 to 2 4 to 13 2 6 3

70 Yttertium 3 2 6 2 4 to 2 4 to 14 2 e 2

71 1stenen 2 2 6 2 4 10 2 e le 14 3 e 1 2

12 Mainaam 2 2 6 2 6 10 2 6 to to 2 6 3 2

73 Tantalum 2 2 6 2 6 10 2 4 to 14 2 4 3 2

14 haagesse 2 3 4 2 6 10 2 4 10 14 2 4 4

2 73 Itbensum 2 2 4 2 e to 2 6 to 14 2 6 3 2

76 Comaum 2 3 4 2 4 to 2 6 10 14 3 4 6 3

77 trieum 2 2 8 2 6 to 2 6 to 14 2 6 1 2

70 Ptaumsm 1 2 8 2 6 to 2 6 to 14 2 4 6 2

79 Gote 2 2 8 2 8 10 2 4 to 14 2 4 10 1

90 Mereury 2 2 6 2 6 10 2 6 10 14 2 6 le 2

91 Thallium 1 2 6 2 4 10 2 4 10 14 2 4 to 2 1 82 Lead 3 2 6 2 4 10 2 4 10 14 2 6 10 2 2 03 Bismum 2 3 4 2 4 to 2 e to 14 2 6 to 1 3 54 Polonnem 2 2 6 2 4 10 2 6 to 14 2 6 to 3 4 la Astatine 2 2 4 2 4 10 2 4 10 14 2 0 10 2 S 84 Reden 2 3 4 2 e to 2 4 to 14 2 4 to 2 4 97 Franema 2 2 6 2 4 10 2 8 10 to 2 4 10 2 6 1

ta Raeum 2 2 e 2 6 to 2 6 10 14 2 4 10 2 6 2

$9 Aetmaum 3 2 6 3 e to 2 6 to 14 2 e to 2 6 1 2

90 Thortuam 2 2 6 2 4 10 J 4 10 14 2 4 10 2 4 3 2

91 Protectissum 2 2 6 2 4 to 2 e to 14 2 6 to 2 2 6 1 2

92 LTreanum 2 2 6 2 6 to 2 6 le le 2 6 10 3 2 4 1 2

93 Nepeustus 2 2 6 2 6 10 2 6 10 14 2 6 10 3 2 e 2

94 Pluteatum 2 2 6 2 4 to 3 6 10 14 2 6 10 4 2 4 2

95 Amernetum 2 2 6 2 e 10 2 4 to 14 2 6 to e 2 6 1 2

to Osrium 2 2 6 2 4 10 3 e 10 14 2 6 to ? 2 6 1 2

97 Bernetaum 3 2 4 2 4 10 2 6 10 14 3 4 10 9 2 6 2

to Callierstum 2 2 4 2 4 10 2 6 10 14 2 6 10 10 2 4 2

99 Elastetanuat 2 2 8 2 6 10 2 4 10 14 2 6 10 11 2 6 2

100 Fermaum 2

2 6 2 6 10 2 6 10 14 2 6 10 12 2 6 2

101 Mendelevium 1 2 8 2 6 10 2 4 to 14 2 6 to 12 2 4 2

102 Nonetsam 2 2 4 3 4 10 2 4 10 14 2 6 10 14 2 6 2

103 1.aerencium 2 2 6 2 6 10 2 8 to 14 2 6 10 to 2 4 1 2

9 79 JTMA (dij\\W.utun 6

e

r

's -

-w APPENDIX PRINCIPAL PRIMARY FISSION PRODUCTS laotope Symbol Half LJe Strontium "Sr 53 days Strontium "Sr 25 years Yttraum "Y

64.2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> Yttrium

Y 57 days Zircoruum "Zr 65 days Niobium "Nb 35 days Molybdenum "Mo 6s.3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> Ruthensum mRu 39.6 days Ruthensum

• Ru 1 year Rhodium N'Rh 57 minutes Rhodium I"Rh 30 seconds Tellurium mTe 77.7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> todane ml 8.1 days lodine ml 2.4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> Xenon mXe 5.27 days Cesaum mCs 30 years Barium mBa 2.6 minutes Barnum 1"Ba 12.6 days Lantaanum 1"La 40 hours4.62963e-4 days <br />0.0111 hours <br />6.613757e-5 weeks <br />1.522e-5 months <br /> Cerium toCe 32.5 days Certum 1"Ce 290 days Praseodymaum mPr 13.7 days Praseodymaum

'"Pr 17.5 minutes Neodymium WNd 11 days Promethaum wpm 2.6 years Promethium Pm 54 hours6.25e-4 days <br />0.015 hours <br />8.928571e-5 weeks <br />2.0547e-5 months <br /> l

l l

80 9 v.s. eovannuaw? pasutims omer, inva-var.ssa/e "Dlilli>ddl D

D

~

U' fi l

wth IIlju

'A L

.