CHAPTER15 Leaming from Accidents While no company want.docx

CHAPTER15
Leaming from Accidents
While no company wants to have accidents, once they occur, it
is
important to learn from these accidents. One of the worst
mistakes to make
for a company is to repeat an accident. Accidents are
opportunities to fix the
safety program, correct hazardous situations, train employees on
the correct
behavior, and ensure systemic problems are corrected. While an
accident is
dreadful, we must learn from them.
The key concept of a safety program and the accident
investigation program
15 ro prevent accidents and/ or prevent recurrence of an
accident. No one
wants to get hurt, but actions/inactions and conditions will
dictate an accident.
All 'd aca ents are caused, and there are many consequences of
accidents. The
heallh and safety of personnel is the utmost priority, but other
issues include
funcuonal c bili' f · fin · al 11 bein apa ty a ter los s, public
image and reputation, anc1 we -
g 0oss of sales), and also civil or criminal legal action.
Lessons Learned

"If it ca 0 happen h ' 1 " Thi · the co at t 1s ocation then it can
happen anywhere. s 1s
ncept of 1 ' essons learned. One of the most important elements
of
159
Parl IV: Pmornting Arddmls
160
accident in vcs t.igat.ion that ha s been discussed is to fi
an . . gure Out Wh
happened and how to prevent It. One of the bigge st mistakes of
an . at
. k d kin y acc1de is not learning from your rrusta ·e s an ma · g
the same mist k . nt
. h aeagainAu companies need to not 1us1 fix t e problem areas
and prev ·
' ent recurren
b)' correcting the problems, but actually develop a system to lea
f ce
. rn rorn th
accidents. A lesso ns learned program will ensure that accidents
a e
, . . re corrected
not just at o ne locat1on, but at all locations. Also a lessons lea
d f
. . rne rorn a

smaller accident can hdp avoid a larger accident from
happening. "If ~-e
were really good at learrung from o ur mistakes, two similar
accidents would
never occur" Qanson 2009) .
One of the biggest failures of companies is not communicating
the
problems, causes , issues, rrustakes, and / or failures of an
accident to the other
divisions of the company. If a company has multiple locations,
then these
issues could cause an accident anywhere. Communication is the
key. Luckily,
communication is much easier now, and accident information
can be e-mailed
immediately to other off-s ite locations.
There are many different ways to disseminate lessons learned
information,
and many companies e-mail out each cause and corrective
actions to all.
Others put together a weekly or monthly newsletter to
disseminate the
accident information. Communication is the key component.
Review Board
Another important aspect is to have an accident review board to
review
the accide nt report to check for quality, consistency, and
ensure the faccs ,
causal factors, and corrective actio n s are correct. There are
many types
of re view board s. The be st review boards are made up of all
levels of

employees, from floor level (hourly workers), supervisors, to
management.
Th ere are othe r forms of review boards such as union review
boa rd s
d ' h principle an management review board s. These all work on
t e same .
to review the report , validate the depth of analysis and inve
sugauon '.
h k h . · ns will fix c ec · t e cau sal factor s, and ensu re that
the correcuve acuo . .
h . . . . . . n effecu,e t e problem. Exhibit 15.1 gives a quick
checklist for building a
acc id ent review board.
Chapter 15: Ltami11gfro111 Arcidents
Jl,<liibi t 15.l
EFFECTIVE ACCIDENT REVIEW BOARD ~------
Building an effective accident review board
l) Choose the right accident review _board members, and the
members should be knowledgeable in the analyacal techniques
and causal factors analysis.
Z) Develop a consistent review process that yields consistency.
3) Root out system risk and look for systemic problems /
causes.
4) Ensure that action items are completed.
Adapted from Hughes 2011.

Opportunities to Improve the
Safety Program
While accidents are a negative path in a sequence of events and/
or an unplanned
event, once an accident happens, the sequence is over. Now it
becomes an
opportunity to improve the safety program. An accident utilizes
the concept
of basic safety principles of identify, analyze, and control the
hazards. The
accident identified the hazard, and hopefully the accident
investigation will
ana lyze and control the hazards so there is no recurrence of the
accident.
Thus, it provide s an opportunity to improve the safety program.
While many
safety professionals are dedicated to using proactive safety
techniques, once a
near miss or accident occurs, it becomes an opportunity. It has
either already
caused an accident or almost did.
Prevent" S . mg ysterruc Problems
One of h f find is the systemic t e most in1portant and difficult
causal actors to
cause Th . . fu th culture of the company · e systemic cause is
the cause that in ses e . f
and if r more accidents. l a not found and corrected will lead to
man)
161
Part I V: Pm <t11h·11g Amdm ts

162
structured causal factors analysis is n ot performed, then syste _
facro rs wi ll no t be fou nd. If causes are always based O rnic
causil_ .d . . . Id b . . n superficial then the acc1 enr m ves uga
uo n cou e m1 ss 1.ng a ma· fl _ calscs Jor aw 10 th •
manageme nt system. For example, it was initially presumed e
safety
was having all types of h a nd injuries because of em 1
th
at a tornpan}'
p oyees beh .
wearing the wro ng personal protective equipment. An a "d _
avtor in
determined that the real iss ue was tha t the workers w cci en~
investigation
. . ere tramt d to
wrong perso nal p rotecuve equ1pment . The accidents would h .
u~e the
until the training was changed. 1 f the investigatio n had not 1
;ve _conllnuc-d,
factors then th e sys temic cause would not have been di
00
ed lrlto causal
scovered.
Spreading the Information
The lme~ne t has its ~roble m s , b~t it also ~as a wealth of
information on it

Co rn~arues c.a n u se It to. get the. tnformauon out much
faster, especiallpt
off-s ite locauons. E- m a1_l, webs tt ~s, sh arepoints, and even
newsletters can
b e a ~ool to s~read the m fo rmauo n about accidents and
lessons leamro._
Th~ mformauon can al so be u sed for trending accidents, using
many
vanables to h elp spread the accident information. Graphs and
charts an
be d eveloped to m ake it eas ie r for the information to be
understood by all
employees. For OSHA record able accidents, the information is
required
to be posted, but other acc ident information and trending resul
ts can
be posted around the compa n y so e mployees are aware of the
number
of accidents, near misses, and prope rty damage that occurs
within the
company. Other information o n cau ses and corrective actions
can also be
posted or communicated.
Using Accident Theories and Analytical
Techniques to Prevent Accidents
Xlb y should you wait until the re is a n accident at your
workplace before you
perform safety m e asures? Vh y sh ould yo u wait until there is
an accidcnl to
use th e accide nt theo rie s? Acc ident theo rie s have been used
for accident
Ch([pttr f 5: /J ammgfrom /lmdm ts

inn~srigation and caus~l analysis for many years. lt is time t ~
start u sin~ these
H.•chniques in a proacovc approach. One can use these acc1dem
theones and
::in:ilytical techniques as proactive safety techniques to
identify, analyze, a nd
pre'ent hazard s from b ecoming accident s.
As discus sed in previous chapters, the one question sa fety e
ngi nee rs
ha,·e po ndere d for decade s is, " How do we prevent
accidents?" By fir st
taking a look at how accidents occur. Accidents d o no r ju st
happen- th ey
are caused, and the key is to find the causes and control them b
efore there
is an accid ent.
Analytical Approach to Accidents
The analytical approach to investigating accident s is u sed to
find out vhat
happened and how tO prevent future accidems. This is :t very
intuith·e and
iterative process to u se techniques that develop scenario s and
d e te rmines
wha t happe ned. The purpose is to use techniques and
methodologie s that
help to determine th e accident sequence and then prevent that
sequence b y
corrective actions o r controls. The purpose of the anal ytical
approach is to
use the techniques and methodo logies to analyze th e
knowledge :ind fact s
to develop results or recommendations and corrective actio n s
to preve nt
accident s. A n analytical approach w ill establish consiste ncy

and validity to
the proactive process.
Systems Safety Approach
The key to a systems safe ty o r task safety approac h is to
analytically a nd
methodically ide ntify, analyze, and control h azards before an
accident occurs.
The concept of conducting analyses is to b reak down the sys
tem Yersu s the
job or task. Analyze the systems such as the piece of equipme nt
and look fo r
hazards. Then break down the tas ks: '(!hat th e process is fo r
obtai ning raw
malcrial, loading it into the m achine, and so on. O btai n all of
the hazards for
this task also. The n ext step is to discover the ha zards versus
failures . Man y
of the systems safety techniques find failures ; h owever, to
prevent accidents
you mu st look for hazards .
163
Part JV· Prrrrnti11g A uidmts
164
Proactive Safery Techniques Using Accid e nt The o ries
k O all acciden ts is to uncover a nd analyze the accident The ey
t , . . sequ ence
d •ne the causal factors , and fi nd corr cc UY e acuon s that
vill , etermt . . prevent

furure accidents. After th e h azar~s arc tdenu? ed and analyzed,
causal factors
are de·eloped. Using the se a.ccident theon es . the cau sal
factor s or wha t
would have prevented th e acct.dent are u sed to devel~p the
proper controls
or corrective actions. The theones sh~uld be u sed to ~alidate
and find systemic
problems :a :ill levels. Management issu es, worker iss ues,
engineering issues
(design), as well as po licy is~ues n~ed to b e analyzed. All
levels need to be
looked at to provide corrective acaons and accountability to
prevent future
accidents. Telling a worker to work safer ,vill o nly prevent that
worker from
haYing a future acciden L If the control is a policy issu e or a
design issue, then
the corrective action needs to be addressed a t that level to fix
future accidents.
Pro1ctin sa fety is a chance to look at the failures in the sa fety
program and
Ii....: them. (It is not the time to p lace blame or look at h uman
error. lbis is
the rime to look at what caused the human e rror.)
The next step to prevent accid ents is to implement the
corrective actions.
All correctiw actions need to b e tracked and a strict timetable
established. If
corrective actions arc assigned to a d epartment or someone is
accountable
fo r the corrective action, th e n usually they will be fixed in a
more timd)'
manner. All corrective action s or recomme ndations must be
communicated

clearly and objectively. The las t ste p is to conduct a follow-up
and m:ike sure
the corrective actio ns are in place o r wo rking correctly to
prevent accidents.
Complian ce/Regula lio n s
One o f the best ways to use the tl1eo ri es o f accidents is to
use the standards/
regulations to find hazardou s situ a ti o n s . X' hile sta ndards
are the minimil
compliance, it is a great starting point. W h e n performing a
walkaround, look
for potential accidem sequences or u se the OSHA categories of
accidents as
listed in Exhibit 15.2. Th es e are the ca tegories that would be
marked for:in
OS HA recordable, so if you alleviate th ese from occurring,
then you stopped
lhe domino or seque nce of evenrs of an accident.
Chapter 15: Lrami11gfro111 Amdmts
Exhibit 15.2
C OSHA CATEGORIES OF ACCDENTS
Stru ck By
Slru ck Ag:un st
Ca uglu Betwee n
Co nta ct '1/ ith
Co nt ac t By
Co ntact On

Job Sa fety Anal ysis
Ca ught In
Fall, Sa me Le ·cl
Fall 10 Below
Ovcrcxe ni o n
E..,o;:posurc
E·eryone has probab ly perform ed the basic job sa fety anal
ysis of listing th e
steps t0 a job, documen ting the hazards, and developing
controls. A jo b sa fety
analysis is an excellent p roactive safety approach. Vhen
conducting a jo b
safety analysis, look at the po te n tial dominos and sequence of
event s for an
accident. Look fo r negative paths and use the OSHA categories
to structure
yo ur hazard s. Also u se the unsafe acts/ unsafe conditions to
detem1ine where
lack -of-comrol situations can occur.
X' hilc identifying the hazards is the h ardes t step o f the job
5afety analysis,
the mos t impo rta nt step is developing solutions to preven t the
accident. The
hazard co ntro l precedence was developed to try to prevent the
accident in
the bes t possib le way to ensure that the co ntrol is fixed . l11e
first step is to
try to design out or get rid of the hazard; if tl1 at ca nno t be
accom p li shed,

then try to substitute for less hazardous tas ks or equipment. Th
e next step
is to try to use guard s and safety de vices to reduce the hazard.
TI1e ne.xt step
is to use administrative controls and pro cedures to co ntrol the
hazard. The
last step is to use personal p rotective equipme nt to guard the
perso n from
the hazard . This is extremely important in that vo u want to try
to control the
hazard at the highe st level. ·
166
Pan / 1/.· Prrt YnhngAmdmts
Bam ·er A.nalysis
T his is a simple an al y~is_ dia~ is ,·.ery good a t locating
hazards and contro .
_1 r barrier an alysis 1s fairly simple co perfonn- keep the h,, ..
d lling
u1en1. _ _ ''-"ar frornth
target. Thi s type of barrier :rnalys1s con s1~ers potential
hazards, the pocen . '
'
• =e rs and assesses th e ad equacy of b:uners o r other
safeguards th ttal
•-b • • . . at shoUJd
pre,·cnr ~r nUtig:i te an acade_m (Spear 2002) . Ths a nalysis is
extremely US(fuj
because Jt prod~ces a graplucal chart. T h e ~utcome ca n

graphically explain
the :iccid ents failure~ and also find the barner~ that n:ed to be
corrected or
:idded ro prevent accidents. ~e approach to this technique is
very siJ:n le
is lisled in E:hibit 15.3. T here IS a hazard and a target. The
barriers try ~o k'MIIJ.
the hazard from reaching the target. The first step is to identify
the hazard CCp
the rn.rge t. Th : ne~ t step is to ide nti~, or brainstorm all of
t~e barriers to:
a comprehensn·e list and docume nt It on a form, as shown m
Exhibit IS.4.
Exhib it 15.3
THE STEPS NEEDED TO PERFORM A BARRIER ANALYSIQ
Perfo rming a Barrier Analys is
1. Identify the hazard and the target
2. Id entify (b rain storm) barriers and controls
3. Ev aluate the intended function of th e
barrier
Th e barri er analys is summ a ry chart can be an excellent
graphical chw
tha t di splays th e fail u res of barri e r s for the accident in an
easy to read
graphjcal fo rm at. Thi s cha rt can b e ge nerated easi ly from
the workshtel
and be very h e lp ful in d eve lo ping c o rrectiv e actions to p
reve nt furo re
acci dents. A n ex ampl e o f a barrier ana lys is summary chart
is illu5uated

in Exhi bit 15.5. This exa mp le di spla ys the hazard of an
electrical shoe~
from m ainte n a nc e o f a ma c hine . / hen thinking
proactively, }'OU
I d . . I h k canelec<rtt cone u e tha t th e barn e r s to preve nt
an e lectr1ca s oc ar . . d
safety p rocedure , a loc ko u t tagout program, electrical safety
uainmg, an
personal protectfre e q uipme nt.
Exhibi t 15.4
Barrier
Exhibit 15.5
HAZARD
BARRIERS
TARGET
Chap ter 15: Uamll,gjrom A a idmts
Purpose o f B arrier
Electrical Shock
Electrical Safety
Procedure
LOTO Program
Safety Training

PPE
Worker
Prut I I/: 1'1Pve11ti11g Arddents
168
1 t is important to understand how and why accidents occur by
looking at the
many accident theories. Proactive safety techniques are
extremely useful in
identifying, analyzing, and controlling accidents. Simple
techniques can be
used to prevent these accidents. It is important to understand
the aspect of
and impact of proactive safety and the true reasons these tools
and techniques
are applied, which is to prevent accidents.
Summary
Accidents can be very simple or extremely complex; however,
the important
aspect of an accident investigation is to learn from them and not
repeat them.
Lessons learned from accidents need to be communicated to the
company to
prevent similar accidents. No accident should be repeated.
Other aspects of an accident investigation is to develop an
accident review
board that acts to check the accident report for quality,
consistency, and

ensure the facts, causal factors, and corrective actions are
correct. The focus
of the accident investigation is to prevent problems and improve
the safety
program.
REVIEW QUESTIONS
1. Why is it important to learn from accidents?
2. What is the purpose of an accident review board?
3. Who is on a review board?
4. What is the problem if systemic causes are not analyzed?
5. What are some ways to communicate lessons learned?
6. What are some ways to use accident theories and analytical
techniques to
prevent accidents?
CHAPTER 16
Radioactive Materials
--
01/07--03/07 :· .
-~ . ..
J ._· 1
~-
Covrte-sy of Lilnd;, u , r, Inc.. Glen wood, /J/l no1s.

airborne radioactivity area, p . 703
alpha particle, p . 689
alpha decay, p . 689
alpha radiation , p . 690
atmospheric fallout. p. 706
background radiatio n, p . 698
becquerel (Bq), p . 697
beta decay, p . 690
beta radiation, p. 691
breeder reactor, p . 710
chain reaction, p . 707
Comprehensive Nuclear-Test-Ban Treaty ccren, p . 113
critical mass, p . 707
criticality, p . 707
criticality safety Index (CSI), p . 715
curie (Ci), p . 697
depleted uranium (DUF6), p . 71Z
deute rium, p . 686
deuteron. p. 686
dirty bomb, p. 729
dry cask, p. 716
684
electromagnetic radiation, p . 692
electron volt (eV), p. 689
enriched uranium, p. 712
excepted package, p . 721
exclusive use, p . 721
fissile nuclei, p . 706
fission product. p. 704
fuel rod, p . 712
gamma decay, p . 693
gamma radiation, p. 692
gamma ray (photon), p . 691
gray (Gy), p . 698

green salt, p. 711
half-life, p. 687
high-radiation area, p . 703
~~i~~;,YP~o;
2
t;-controlled quantity
inverse square law of radiation, p . 726
ionizing radiation, p. 689
irradiation, p. 694
Isomeric transition (IT), p . 693
low specific activity material
(LSA),p. 720
mas s number, p . 686
meltdown, p . 710
metastable state (isomeric state),p. 693
mixed oxide fuel (MOX}, p . 711
negatron, p . 690
normal form class 7 material
(non-special-form class 7 materi,1ij,
p , 724
nuclear fission, p . 704
nuclear reactor, p . 704
orange oxide, p . 711
positron, p. 691
protlum, p . 686
radiation absorbed dose (rad), p. 698
radiation area, p . 703
radiation level, p . 699
radiation sickness, p . 698
radioactive material, p. 685
radioactive materials area, p. 702
radioactivity, p. 686
radioisotope (radionuclide), p. 687

radiological dispersal device, p. 729
radlolysls, p . 703
reportable quantity (RQ), p. 718
resldential radon , p . 727
roentgen, p . 698
roentgen equivalent man (rem), p. 69B
-
staled source, p. 693
sievert (Sv), p . 698
surface contaminated object
(SCO),p. 720
type B package, p . 722
special form class 7 materlal, p . 723
eciflc activity, p . 697
:~rateglc Reduction Arms Treaty
(START), p . 713
transport Index, p. 719
tritium, p . 686
uranium enrichment process, P- 71 1
very high radiation area, P- 703
yellowcake, p . 711
triton, p . 686
type A package, p. 722
1 Describe the phenomenon of radioactivity and the concept of a
half-life for a give n

radioisotope.
1 Describe the na ture of each mode by whic h a radioisotope
ma y decay.
1 Describe the differentiating features of alpha, beta, and
gamma radiation.
1 Describe the nature of a sea led radiatio n sou rc e and the
features of the ionizing
radiation symbol used to identify its presence.
1 Identify rhe units used for the measurement of activity and
radiation dose.
1 Identify the ge ne ral aspects of OSHA regulations req uiring
employers to limit
radiation exposure in the workplace, including the posting of
signs in areas where
radioactive materials a re stored or used.
Describe the phenomenon of nuclear fission, incl ud ing sponta
neous fission.
Iden tify the primary health concern posed by the presence of
rad o n within residen-
tial dwellings.
Identify the label s, markings, and placards that DOT requi res
on packaging of
radioactive mat erials and the transport 'e hicles used for their s
hipment.
Identify the response actions to be executed when radioactive
materials a re released
from their packaging into the environment.
Describe the response action to be executed whe n a
radiological dirty bomb ha s
been activated a nd discharged into the environment.
W hen we hear the te rm radioactive, two fearsome incidents
generally come t o mind: the accidenta l release of material fro

m a nuclear power plant and the deployment of nuclear
weapons. 1 We discover in this chapter that both events
are associated with the occ urrence of o ne o r more nuclear
processes. The forms of matter
that display chem are called radioactive materials.
We a lso lea rn in this c hap ter that serious health ri sks are
linked wit h exposure t o
radioactive materials. To eliminate or minimize rhe impact of
these risks, the U.S. Con-
gre ss delegated the following responsibilities to the reg ulat
ory bodies listed:
• The U.S. Nuclea r Regulatory Commission (N RC ) re gulates
the civilian nuclear cnerg)'
industry by licensing th e construction and operation of the
nation's nuclear power
plants.
• The U.S. Department of Energy (DOE) oversees the research
and d evelo pment of new
a nd creat ive means for reducing the burgeoning supply of
nuclear was te . In add ition,
it oversees the construction a nd operation of nuclear waste
disposal sites and responds
to re lea ses of radioactive material from any source. DOE a lso
certifies the integrity of
the unique packages in which radioactive material is
transported, provided t he y a re
fo r the purpose of national security.
1
Nuclear wea pon s. o r nucl ear bombs, in iti.ill y were called
aro mic bo mb5. Th e renn 1111 c fr a r is pre fe ra ble to
atom rc, bec au se the phe nom enon res pon sible fo r th ei r

detonation is a nucl ea r one.
ra d io a ctive m a t e ria l
A material containing
an Isotope that sponta -
n e o usly emits ionizin g
ra d iatio n; for DOT pu r-
po ses, a materlal whose
speci fic activity and
t otal activity In a con-
sig nment exceed valu es
pu bl is hed for liste d
ra dioisoto pes at 49
C.F.R. §173 .436
Chapter 16 Radioactive Materials 685
mass number • The
tota l nu mber of pro-
tons and neutrons in
a given nu cl eus
protiu m • The hydro-
ge n isotope com posed
of one proton and no
neutrons
deuteriu m• The hy dro-
gen isotope co mposed
of one proton and one
neutron
EPA es{abl ishes r.idi.ation-exposure limir_s to p~o rect publi c
he_alt.h. These limi ts appJ

to ra dia tion arisi ng m the env1ron_menc, mcludmg natural
r~d1at1on and the radiatio~
from spent radioactive m:iten ~ds m storage. EPA :ilso momtors
the levels of rad
rivi ry in ai r, preci pitatio n, drinking waler, and milk al 164
monitoring stations s;::~
throughout rh e 50 srates.
OS HA estab lishes radi:iri on-expos ure limit s that protect
employees who use rad '
tfre mat erials wirhin those wo rkplaces that are not regulated
by NRC or DOE. ioac-
DOT ensu res th ~tr shi.Ppers and c~ rr iers ~dop~ proced~res
to eliminate or minimize
the ris ks associated wuh rransportmg rad1oact1ve materials.
In combination, these age ncies serve to prov_ide a_degree o ~
protectio n against the hazards
associated with inad ve rtent exposure to rad1oam ve materials.
16. 1 FEATURES OF ATO M IC NUCLEI
In Senion 4.4, we noted chat the atomic nucleus ha s two
primary constituents: protons
and neutrons. Although the nuclei of all atoms of the same
element have the same number
of protons, they m:i y have different numbers of neutrons.
These nuclei are called
isoropes.
The number of protons found in rhe nucleu s of an atom is its
atomic number. The
number of protons equals the number of electrons in a neutral
atom. Because the atomic
nwnbers of the elements are compiled in the periodic table, we
may use a periodic table to
re:idily identify the number of protons in a gi ven nucleus. The
tora l number of protons

and neutrons in a particular isotope is called its mass number.
Hydrogen has an atomic number of 1; rhis means that every
hydrogen atom has one
proton. Each hydrogen atom has one electron, but when a
hydrogen atom is ionized, it is
stripped of its electron , and only its nucleus remains.
Hydrogen atoms exist in an y of three isotopic forms having the
following unique
names and compositions:
Protiu m is the simplest of the hydrogen isotopes and, in fact,
the simplest of all nuclei.
Protium ha s a single proton as irs nucleus. When a protium
atom is ionized, only a
proton remains.
Deuterium is the second hydrogen isotope. Deuterium has a
nucleus consisting of a
proron and a neutron. When a deuterium atom is ionized , the
remaining nudeu5 is
composed of one proton and on e neutron and is called a
deuteron.
Tritium is the third hydrogen isotope. Tritium has a nucleus
consisting of a proton
and rwo neutrons. The nucleus of an ionized tritium atom is
called a triton. deuteron • The nucl eus
of the deute ri um atom Each isotope is designated by the
symbol 2X, where z and t are the atomic num be r
tri ti um • The hydrogen and ma ss number, respecti vel y; X is
the element's chemical symbol. Using chis format, rh e
isotope composed of three hydrogen isotopes are designated by
the symbols !H, fH, and {H, rcspectivdr: For
one proton and two each , the symbol Z equals l, the number of
proton s. The number of neutrons is the differ-

neutrons ence between the superscript and the subscript: for
prorium, the number is O; for deu ie-
trito n • The nuc leus of rium, the number is l; and for tritium,
the number is 2. Deuterium and tritium are al so
the tr itium atom represe nted as D and T, respectively.
radioactivity , The prop- Only the isotopes of hydrogen have
unique names. The isotopes of other elements are
erty associ ated with the n:imed by identifying the name or
symbol of rh e element and the mass number of th e
:i;;~~~;ta~:~~on of isot~pe at iss ue. Thu s, nuclei designated as
l£C, ~l1 U and iSK are named carbon-12,
gamma rad iation from uramum-235., and pota ssium-40, or ~ -
12, U-235, and K-40, respectively. . , cain
rad ioisotopes, their cap- . All nucle~ ~an have three or more
1so1opes, many of which are stable; that 1s, the) re clei
ture of extran uclear their c~mposmons and do nor undergo
spontaneous changes. Howe'er, many ot~.er n~dis-
eleetrons, or their spon- are subJ ect to spontaneo us tran
sformati ons. They are sa id to "transform" "decay, or .
taneous fi ss ion integrate.,.. The phenomenon is called
radioactivity, and the intrinsically' unstable nuclei are
68 6 Chapter 16 Rad ioactive Materials
•Jid ro be radioactive. ~hey ~re ~ailed radioisotopes, or
radionuclides. Protium and deute-
;iulll are srab_k _, nonradioac_uve isotopes of hydrogen, but
tritium is a radioisotope.
Rad1oacu v1t}' generally IS not affected by any physical or
chemical change in a substance.
Hence, when radioacti•e mat~~ls are ~ubjecred to changes in
pressure, temperature, or chemi-
cil n:twre, the sr:o~1aneous d1smregrat10n of the ~levanr
radioisowpe usually is not altered . .
When a rad101sotope undergoes a change, it usuall y emits a

particle; less commonly, 1t
absorbs an electron. Both processes fr~quend y are accompanied
by the simultaneous emi s-
. of energy. When the transformauon occurs, the radioisotope is
converted inro a new
~
1
~~eus, which is either stable or radioactive itself. Radioisotopes
often undergo several
nsformations before 1hey are convened into stable nuclei.
ira Each radioactive transformation is associated with a specific
period of time. The time
during which an arbitrary number of nuclei are reduced to half
the number is called the
half-life of that radioisotope. For instance, suppose a volume of
tritium gas containing
S00.000 molecules is set aside for 12.32 years. Because the
tritium molecule is diatomic,
there are I million atoms of tritium in this volume. After a
12.32-year lapse, only 500,000
iritium :iroms remain; and after another 12.32 -year lapse, on ly
250,000 tritium atoms
remain. Hence, 12.32 years is the half-life of tritium.
A half-life is typically symbolized as t½ and is one of the
characteristic properties of a
r.1dioisotope. Its value may range from nanoseconds to billions
of years. Each element has
at least one radioisotope. The hundred or so elements
collectively have nearly 3100
kno wn radioisotopes. Table 16.1 shows that few radioisotopes
are present in nature. If
they were present when Earth was initiall y formed, most
disappeared long ago, because
the planet is 3.6 billion years old.

Some commercially available radioisotopes are listed in Tab le
16.2. Although rher
have man y potentia l purposes , most commercia l
radioisotopes are used to image the
lfr1!iiii
AADIOISOTOPE
Tri tium
Ca rbon-14
Potassium-40
Rubidium -87
lridium-115
lanth an um -138
Neody mi um -144
Sa mari um-147
~ 87
Platinum- 190
Rad ium -226
Thor ium -232
Some Naturally Occurring Radioisotopes"
HALF-LIFE (y)
I RELATIVE ISOTOPIC
ABUNDANCE(%) I MODE OF DECAYb
12 .32 0.00013 ~-
5700 ~-
1.248 X 109 I 0.012 p-, EC,~•
4.81 X ,olO 27.8 ~-
4.41 X 10 14 958 p-

1.02 X 10 11 0.089 p,-, EC
2.29 x 10 15 23.9
1.06x10 11 15.1
3.76 X 10 10 2.60 p-
4.33 X 10 10 62.9 ~-
6.5 X 10 12 I 0.012
1600
1.40 X 1010 100
0.72 7.04 x 108
4.468 X 109 99.28
Uran ium-235 --_ i..,'.:'.:::..:..:.:...,,-----t~ ;;--
Uran ium -238
:Chan of Nu cl ldes, National Nu clear Data Center, srookhaven
Nation al l abor atory, Long Isl an d, New York {l012).
S~ctlon 16.2.
radioisotope
{radion ucl ide)• An
atom ic nucleus that
undergoes a spontane·
ous change by emitting
a particle, absorb ing an
extranuclear electron,
or undergoing sponta-
neous fission
half- li fe • The time

period during which an
arbitrary amount of a
rad ioisotope is trans-
formed into half that
amount
MilhiiN Some Commercially Available Radioisotopes
RADIOISOTOPE ---
Amer icium -241
Cesium-137
Chrom,um -51
Co ba lt-57
Cobalt-60
Fluorine-18
Gado lin ium- 153
Ga ll iu m-67
Ind ium-t i t
lodin e-123
tod ine-- 125
lodine-131

lrid ium-192
lron-59
Pa ll ad iu m-103
Phosphorus-32
Pluto ni u m-238
Pot a ssium-40
Rad ium -223
Rad ium -226
Rhen ium- 187
Se le ni um-75
Sod ium -24
Stro nt iu m-90
Techne ti um -99m
HALF-LIFE• APPLICATION OR USE ---
Smoke dete cto rs 432 .6y
3008y
27.7025 d
271.74d
~ diat io n so urce for treatment of cance r; sealed rad iat ion

sou~
food s
Ra~ e fo rdete ~ ofred ~l1 volumea~ b~
----1-R,- d-ia-t ion source fo r in_stru~ent ca li brat ion and
determ ina~
t he body 's uptake of vi tamin Biz
5.27 y
109.77 min
240.4d
3 .2617 d
2.8047 d
13.2235 hr
59.407 d
8.0252 d
73 .829d
44.495 d
16.991 d
14.262 d
87.7y
1.248 X 109 y

11.43 d
1600 y
4JJ X 10 10 y
I 119.79d
1S.997 hr
28.90 y
6.0067h r
Sea ted source for industr ial radiograp hy; sealed source for
treatment of cancer
irrad iat ion of foods, and induc ing cross-l ink ing w ith in
polyethylene and rubbe~
macromo lecu les; determ inat ion of the effectiveness of the
body's uptake of vitam ins;
ste rili zat ion o f medical de vi ces
Bra in- and bone-i mag ing drug ; rad iat ion source for tumor
imaging using pos itron
em iss ion tomography
Rad iat ion source for determ in ing bone density and the enent
of bone mineral ization
Diagnost ic drug for tumor detection
Diagnost ic drug tor tumor detection; rad iation source for
imaging the gastr ic and
cardiac systems

Rad iation source for imag ing the bra in, thyroid, and renal
systems
Cancer therapeut ic drug ; brain , blood, and metabolic-function
diagnostic drug;
surg ically implanted as a component of • seeds" for the internal
treatment of prostate
Bra in, pulmonary, and thyro id diagnostic drug ; thyro id -
cancer chemotherapeutic drug
Sealed source for industrial radiography ; surgically implanted
as brachytherapy
needles into organ for internal cancer treatment
Radiat ion source for measuring the rate of format ion and
lifetime of red blood cells
Rad iation source for detect ion of skin cancer
Power source for the thermoe lectric generators used in
equipment for planetary
stud ies, incl ud ing the Mart ian rover, Curiosity
Dat ing geolog ical format ions
Rad io immunotherapeut ic drug
Rad iat ion source for treatment of cancer
Dat ing meteor ites
I Pancrea ti c cancer d iagnostic drug
I Radiat ion source for detect ion of obstruct io ns with in the
circulatory system
Industrial gauges; thermoelectr ic generators

I Ra d iat ion source for imag ing the brain, thyro id, live r,
kidney, lung, and card iova~u lar systems ___
Th a lliu m-201 3.042 1 d
Trit ium,orH-3 12.32 y
~ + :::--::~ ----11---
,ea::_:,d:..:i•:...'d:...i•:.,9:..."o:.:st:...i<:..:d:::'":.,9
_____________ __
Rad iation source for determ ination of total body water
Yttrium 90 64.053 hr Rad 10 1mmunotherapeut1c drug
•Ch art of NuclidM, Nationa l Nucl ea r Data c,n1er,
Brookhaven Nationa l La borat ory, Long isla nd. New Yo rk
(2012).
688 Chapter 16 Radioactive Materials
org:i ns in pa~ie~1ts having diseases in the heart , bones, and
elsewhere. Generally, to pro-
diic e a graphic ~m age of the st ructure or m~tabolic activity of
an organ , radiologists inject
l rJdi oisorope into the bloodstream and film the activity of the
radioisotope as it move s
,oncentrates.
or Some radioi sot0pe~ are u.scd to treat cancer patients. The
radiation source delivers a
hii;h dose fo~ <:7onsecu~1 ve da_1ly tre_atments to a specific
location in the body. Less com-
nly. a rad101sotope 1s surgically implanted to deliberately
radiate an organ over a long
mo e period. During the treatment of prostate cancer, for
example, a surgeon may implant
tin~in c- 125 or palladium-103 encased in tiny pellets or " seeds

" within the proscate. The
10
dioisotope kills cells in the nearby region, including those that
are malignant. Once
::e:itment is completed, the seeds are surgically removed.
fi·itiH&HiMlll-11
r:-e,ium• 137 1s a rad101sotope often used a'> a sealed source
(Section 16 3) of gamma rad•atJon for the tfeatm e nt
of cance r 11 a cl inic pu rchas es a sour ce conta,n ,ng 7 60 x
1015 atoms of cesium-137 today, hOIN ma ny atoms w,11
rema1n ,n 121 yea rs '
Solutlon: The ha ll -hie of ces,um-137 ts listed 1n Table 16 2 as
30 08 yea r, The number of half-lives in 12 1 yea rs
1s then detei min ed by d1v1s 1on:
Number of half- lives~ 121 y/ 3008y = 4 0
This me-ans that afte r the passage of 12 1 ye ars . cesi um-137
will have disintegrated through four hali-hves, hence,
one-skXteent h of th e ato ms will re main
½ X ½ x Yi X ½ = (1/1)• ,., 1/1 6
~•u•t1 olym g 7 60 x 101s by 1/1 6 gives 4 75 x 10 14 atoms
7 60 x 101~ atoms x 1/ 16 = 4.75 x 101' atoms
Thus, after the passage of 12 1 yea rs, 4 75 x 1014 atoms of
cesium -137 rem ai n ,n the sealed sourc e
16.2 MODES OF RADIOISOTOPIC DECAY
Nuclear transformations of radioisotopes principally occur by
means of one or more of
the modes illustrated in figure 16.1: alpha decay, beta decay

(nega.tr~n emission, positron
emission, and electron capture), gamma decay, and spontaneous
hss1on .. tl.pha: b~ta, ~md
ga mma decay gives rise to a specific cype of radiation: B:c~usc
th ~ r~d1at1on 1omzes the
matter through which it passes, each is an example of 1onizmg
rad1at1on. We shall exam-
ine them in Sections 16.2-A, 16.2-B, and 16.2-C.
The unit used to express the energy associated ,~ith alpha , beta
, and gamma. dee:?
typical}' is the electron volt or eV. One electron volt 1s the
amount of ene~gy ac~mred b)
an electron when it is accel~rated by an electric potential of one
~·oh. It 1s equ_1vale_nt_ to
1.602 X 10~19 J. The energy typically emitted by r~diois~topes
IS express;~ l~/r11l1on
electron volts. One million electron volts, or l MeV, 1s
cqlllvalent to 1.602 10 J.
16,2-A A LPHA D ECAY
.fany radi - - 11 , those ha ving atomic numbers grea1er than 83
, disi.nt ~grate b msotopes, especia ) . d of two proto ns and two
neutrons. rhese
Y spontaneously emitting particles compose - lied alpha decay
Alpha particles
Panicles are called alpha particles, a~d the process/ ca
symbolized as either ~He or the
are the nuclei of doubly ionized hehum atoms an are
ioniz ing radiation
Types of rad iation
that ionize matter
upon impact

e le ctron volt (e V) The
amou nt of energy
acquired by an electron
when It is accelerated
by an e lectric potential
of one volt
alpha A par-
ticle emitted from cer•
tain radio isotopes and
having the properties
of a doubly ion ized
hel ium atom
a lpha d t!ca y A mode
of radioisotopic decay
associated with the
em ission of an alpha
part icle by a nucleus
r
alpha radiation • The
coll ect ive com bination
of th e alpha particles
em in ed from certa in
rad ioisotopes
beta dKay A mode of
radioisotopic decay
associ ated w ith the

spontaneous emiss ion
of a negatron or posi•
tron from a nucleus or
th e capture of an
orbital electron by the
nucl eus
negatro n • A particle
hav in g the pr ima ry
propert ies of an
el ectron
FI GURE 16.1 The modes by wh ,ch rad•OISO·
tooes decay, wherein the open circles represent
protons, and thesol, o red circ les rep resent
neutrons Th e most common modes of decay
are those associa ted with the production of
beta and gamma rad1at1on Tht> ra rest mode of
decay 1ssocntaneous fiss ion
-y-decay
Gree k letter o:. When man y nucle i decay b y alpha emiss io n,
the combination of alpb.i
particl es is called alpha radiation.
Alp ha radiation is associated wit h a ~elatively large a_mo_unt
of ~nergy tha t rangts
from 4 to 8 MeV; but because a lpha parnc_les a re dou~l y
ionized, th1 ~ en~rgy is readily
di ss ipated by its passage thro ugh a few centimeters of atr or
by absorption ma thin piece
of matter. For instance, alpha rad iation is absorbed b y the
thickness of this page.
When alpha decay occu rs, th e at0mic numb er a nd mass

number of th e as sociated
n uclei decrease by 2 and 4 , re spec tiv el y. An example of a
radioisotope that disintegrates
by a lpha decay is uranium-238. This phenomenon is repr ese
nted by either of the follow.
ing equations:
! J~U --+ !:MiTh + 1He
1 J~U --+ .!Jt Th + u
Both equations represent the chan ge that th e uranium-238
nucleus undergoes by
emitti ng a n alpha particl e. The sy mbol o f the particle is
written to the right of the arrow
ro designate th a t th e a lpha particle ha s been emitted from
the uranium -238 nucleus.
Equations d enot in g nuclear phenomena a re n o t balanced in
the chemical se nse.
Inst ead, a nucl ea r equation is balanced when each of th e
following is fulfilled: The sums
of th e aromic numbers and th e s um s of th e ma ss numbers
are the sa me on each side of the
a rrow.
16 .2-8 BETA DECAY
The seco nd m ode of radioactive disintegration is ca ll ed beta
decay. This process occurs
w hen a radi oisot0pe eit her emi t s a ncga tron or positron or
combines with an ex1ranude3r
electron. These individu al ty pes of beta decay may occ ur
individually or in combination.
Neg a tron Emission
The first rype of beta d ecay is equiva lent in res ult 10 th e
emission o f an electron from the

nucleus. W hen electrons a re di scussed in nucl ea r phenom
ena , the)' ordinaril)' a~e ~all:~
negatrons a nd are de signa ted as fr, o r -1e. W hen beta deca y
occurs by ch e en11ssion .
negatrons, the mass numbers o f th e associa ted radioisotopes
remain unchanged, bu! rhe,r
ato mic numbers increase by I. 2
. ~n example of a radi oisotop e th a t disintegrates by nega1ron
emissio_n !s thorium·,!!;:
Thi s 1s th e nucleu s p roduced w hen uranium•238 di si nte
grates . On emntmg a nega
2
T he types of lxrJ •decay a re al~o J~~o,1Jtcd with th e produc
tion of neu trJI subJtom ic p JCficle~ calkd ,witfl/l(i,$
an d a11tmei <1m105. Th,:-sc part icl,:-s Mt' of no lnter es r
he1t.
690 Chapter 16 Rad ioactive Mate ri als
honu m-234 becon~es protoactinium-234. This phenomenon is
represe nted by either of
:he fo llowing equation s:
!~6Th - 1 J~ Pa + - ~"
.!ttTh - 1{~ Pa + p-
The emi ssio n of a nega tron from a nucleus rai ses a basic que
stion: How ca n it be
emi tt ed fro m the nucl e~s when the elect~on is not a
component of the nucle~ s? ~he pro·
. • a ppa rentl y more involved th an a smgl e equation
represents. N ucl ea r sc1e nt1 sts ha ve

~:~: ~~lin ed that during n egatro n emission, eac h neutron wi
thin th e un stabl e nucleus
forms into a proron and an elec1ron. The proton then becomes
part of the new
~~~:us, a nd the electron is si ~ulra_neously emitted. This
conversion of the neutron (6 11 )
in to a prow n a nd an electron 1s designated as follows:
611- 1-! + _1('
N . uon s possess a range of energi es, but these energi es
generally arc n o greater th a n~
The y us uall y are absorbed by a 1--cent imet er-thick sheet o f
aluminum. The combt-
~a:i~ n of multiple negatron-deca)' processes rep rese nts one
type of beta radiation.
Positro n Emi ssio n . .
The second rype of beta decay invol'es the emission of a
positron from a nu~lcus. A p~s1tron
is 3 particle like an electron in most features, but it is positively
charged. It ts sy ~1boltzed a~ .1e, or 13" . When a radioi sotope
emits positrons, the ma ss numbers of the assoc.1a1ed nuclei
remain unchanged, but their atomic numbers decrease by 1.
Each nucl ea r event involves th e
con'ersion of a proton into a neutron and posi tron, expressed
as follows:
H - ~11 + .1e
Sodium-22 is a n exa mple of a radi oisotope that deca)'S b y
emining positrons. This
nucleu s spo ntaneousl y tran sfo rms into neon-22. The event is
denot ed by either of the fol-
lowi ng equations:

HN :-. - fijNe + .1e
11 ~.1 ---4- 1ij Ne + ~ .
Like neg:nrons, positrons possess :1 range of energies, but gc
nerall_y the y ar~ no greater
than 3 McY. Like negatrons, the y usuall y are absorbed by a t -
ce_numcter-th1ck sh:er of
aluminum. The combination of multiple positron-decay
processes 1s also represe ntauvc o f
beta radiation.
Electro n Ca p ture .
The phenomenon associated with th e third type of beta decay
involves the caprure of a n
unstable nucleus a nd an orbital electron. A radioi sotope that
undergoes clec1ron ca pture
dec reases in atomic numb er by I but its mass numb er remain ~
unchanged. Eac h _electron
ca ptu red by ihe nucleus re ac t s with a proto n, 1here by
fornung a neutron, w hi ch then
becomes pa rt of th e s trucrnre of the new nucleus. T his nucl
ear event is represented b y the
fo llowi ng cq ua 1ion :
H ,.. ~c--+ ~n
[email protected] a rad iatio n The
collective comb ination
of the negatrons or
positrons emitted from
certa in radio isotopes
The
counterpart of an
electron, having an

electric charge of +1
Argon-37 is an exa mple of a radioisotope th a t under goes
electron ca pture . The
ph eno menon is rep re se nted as follows:
;;Ar + -1e FCI
In 1h · · h b I f he electron is written to the lcfl of th e arrow to
d esignate 1s msra nce, c e sy m o o t
1 that the el ect ron h as combined with th e argon-3 7 nuc eu s.
Chapter 16 Rad ioactive Materials 6 91
Ii
SOLVED EXERCISE 16.2
electromagnetic
ra diation The ent ire
ra nge of e ne rgy t ha t
trave ls as waves
through space
gamma The
co llect ive com bination
o f ga mm a rays emitt ed
from a nucl eus
ga mma ray (photo n)
• A massl ess pack et of
e lectromagnet ic energy
e mitted by certa in
rad io isotopes

u:~i ~~;ae~~ct1~1:s0t ;u;:ial d1ag nost1c dr ug an d fo r gas tru:
an o ca rd,ac irnag!og
f•l How many protons and neutrons a re pres ent 1n the in d,um-
111 nu cl e us ?
(b) •dent·fy tne product of ,ts rad, oactive trans format ion
(<} What percen tage of ,n d,um -11 1 1ema ns 1n the
bloodstream 8 4 days after adm ,n, str,mon of the drug ,
Solution
: Referring to either Figur e 4 3 or Appe ndix Ba t the bac k of
this text , we see that the ch em,
:~~:•c_number of in d-um are determined to be In an d 49, re
spectively Thu s, the sy mbol for the ,;;,iu~~
f•l ~:,:~;1~~u~:,; ::5~u;,~I~ ;;~t~~.s ;~:;~:aan~t the ,nd,um-l J l
nucleus Is 111 The number of neu trons ,n 1·••n is 111 - 49 or
62 neutrons 1n ths
lb) 'ndium-11 t captures an orb,tal e1ectron, a pr0<ess
represen~ed as fo ll ows
The product of this tramform at1on 1s cad m1um- 111
(c) r:;i°r~~:1~:1~::r;:;~:~~a:
1,:e1~a~f~:~ves Aft er that time , the percenta ge olthf

Final perce nta ge = 100 % x Vi x Yl x ½ = 12 5%
16.2 -C GAMMA DECAY
Alpha an d beta decay f~ equ e~d ~ a re accompanied by che
simultaneous emission of the
fo rm ':'f electr_o"_"agnet1c rad1at~o~ called gamma radiation.
Like X-ray, infrared, and
ulrrav1o ler rad1 ~t1on, ga mma rad ia ti o n has neither ma ss
nor charge.
ln che P? rti o n o f th e elec tro mag neti c spectrum shown in
Figure 16.2, the various
fo ri:n s of ra dia nt en_ergy a re cha racteriz ed by their wa
velength s. Ultra violet, infrared, and
rad~ o _waves are sa id to ha ve " lo ng" wa vele ngths, whereas
gamma radiation and X-ray
rad1 ano n have " sho rt " wave length s. Vi sible li ght is th e
bala nce point between long and
sho rr wave len~h s, and rh e ~nl y fo rm rh a t is detected by
our eyes. The components of the
~le~tromag net1 c spectrum with short wa velengths are ve ry
energetic, so much so that they
1omz_e the matter thr~ugh which rh 7y pass, bu t th e co
mponents with Jong wa velengths,m
rela n vely nonenerge nc a nd do nor io ni ze ma n er.

~ch indi vi dual compo nent o f g:rnmrn rad ia ti o n is ca lled a
gamma ray , or photon,
~nd 1s re prese nr ed by rh e sym bol -y . Beca use it does not
possess a c harge, a gamma r3y
;f ~:~~~m el y penetrating a nd abso rbed o nl y by dense fo rms
o f ma rter such as thick blocks
Rad ar
X rays c, 3:
Gamm a L __J 2i l (Nea r) (Fa r)/ §
5
• ray , J Uiii'a~,ofc l Jt Infrar ed :.E
j FM ra di o
AM ra dio
3 ,,:, 10 18 3 :,, 10 13 3 :,, ,o 10 3000 300 3 0
1~:ef:~~~ontnhts of
the e'emomag net1 c spectrum as a funct ,on of radiation
frequency Gamma

fr ea~e nc1es Beca use gam O t e s~e mu m, are fo rms of
energy as soc iated with short wavelength s and high
ionizing rad rauon ma rays ave sufficient ene rg ies 10 1ono ze
matte r, gam ma radiation 1s a fo rm 01
692 Chapter 16 Rad ioactive Materials
The process in.v~ lvi ng rh e emission of gamma rays from a
nucleus 1s ca ll ed gamma
decaY. When a radio isotope un~ergoes ga _m'!la decay, no
change in ei1her its atomi c num -
~er or ma ss ~um_ber occ urs. With the em1 ss1on of each
gamma ra y, some frac tion of the
energ)' of exc1t:H10~ ~hat ca uses rh e ~ucleus to be unstable is
removed.
Im agi ne a ra d 101sotope chat exms in o nl y two energy
stares. The mo re en ergetic
fo rm- ih e excited st~te-ma y emit one or more ga mma ra ys
from the nucleu s. The
pheno meno n ma y b~ illu srra ted by the foll owing equation,
wh ere the exci ted state is rep-
rescnc ed by a n as teri sk:
(Q X)• ---,. ) X - -y

In thi s process, the radioi sotope gi ves up a fraction of its
excitati o n energy to become a
mo re sta ble form of the same radio isotope.
Excited stat es that deca y by emitting gamma ra ys generally ha
ve especially shon half-lives
i<< I0-8 s), but some excited states have half-liv es in th e
range o f -10-8 second to several
}ears. In the latter case, the long- li ved excited state is referred
to as a metastable state, or
isomeric state, of the radioi so tope. The metastable state is
designated by adding an m foJlow -
ing the iso tope's mass number. For example, tcchnetium-99m is
an excited state of techne-
uu m-99 that has a half-life of 6.0067 hours. h deca ys by
gamma-ra y emission as follows:
994"JT C ---,. ~';'re + -y
The deca y of a metastable stal e of a radioisoto pe like
technetium-99m is called an
isomeric transition, o r IT. Table 16.2 notes that , the gamma ra
ys emitted from techne -
tium -99m ca n be specifically used br radiologists to image the
organs of the body.

The phenomenon of gamma-ray emi ssion is not alwa ys
represented by means o f a n
equation . It also is represe nted by 1he follo wing genera l
diagra m, where eac h hor izontal
]me designates a discrete energy state of the atomic nucleus :
16.3 SEALED RADIATI ON SOURCES
Se 'Cr:il radioisotopes listed in Table 16.2 a re encou ntered as
sealed sources. Typica ll y, a
man ufa cturer sea ls high level s of th ese radio isotopes wi
thin do uble-skmned Steel rubes,
whic h then are ho used wi thin a medi cal or other devi ce . The
radioisoto pes rema in sea led
wi th in rh ese rubes througho ut the period of th ei r use.
Co ba. lt-60 is an example of a ra dioi so tope th at is used as a
sea led source. As it decays,
negntro ns and gamma ra ys a. re emined to the environment. Fi
rst, each nucle us emits a ncga -
tron and transform s into an excited state of nickcl-60, which
then emits two ga mma ra ys
ha ving energies o f l. t 73 MeV and I.3 32 MeV. We represe nt
this phe nomeno n as foll ows:

527 -y WCo
µ
~---lr1 = 1.173 MeV
I ln 1 332 MeV
gam ma d eca y • A
spontaneous mode o f
rad lo isotop lc decay
assoc iated w ith the
emiss ion of gamma rays
from a nu cl eus, often
accompany ing alpha
and beta decay
me ta sta b le st at e
(i some ric sta te)• An
exc ited state of a
radioisotope that has
a half-life ln the range
of <10 - 8 second to
several years
iso me ric tra n siti on

The decay of a
rad ioisotope by the
emiss ion of a photon
from an excited state
t o a less energetic state
seal ed so urce • An
encapsulate d
ra d io isoto pe u sed in
irrad iati on e q u ipment
an d elsewh e re
Chapter 16 Ra d lo a ct ive M ater ia ls 693
zrrad i.l t i on • The
mtent1ona l exposure
When co b.ilc -60. ,s used for a sp~c!fic purpose, 1he sca le~ so
urce is posit ioned s
of matter to 1on1zmg
rad iat ion, usually X rc1y~

or gamm a r ays, for
med ical treatment.
ste nl,za t1 on or preser -
vation of foods. and
other purposes
r~ e garnm.1 ray s emmed br che rad101soco~e pass th ro ugh
us steel co ntai ner a nd O tha1
non,tlly penerratt.' :l m.1terial. This process 1s referre d to ~s
i~radiation. Ga mm a r lntcn.
used to irrndiate polyethrlene or rubber IO mduce cross- lmk mg
with in their ars are
cu les. They :ire :il~o used w irradiau: spices :1.11d o th er
harvested f~o ds a nd~:c:;~le.
medical devices. Smee 2008, w hen ant hrax- ta inted l_cu er~
we re ma il ed 10 U.S. 5 enhie (Secuon 10.2 1-E), the
government has rero ute d a nd 1rrad 1a1ed ma il to th e Wh·
ena tors
Congression.11 offices, and oc her federal government offices
in ce rt ain zi p it~ Houst,
befo re its deliver y. co e areas
'fhen gamma rays or ot her for ms of io mzl ng radia tio n are
used to irrad·
the y disrupt the fast-growing ce ll s of insects, mo lds, an d mic

ro bes o n peris h
1
~ ~ food~
poultry, ~nd produ ce. Irra d iati o n also d~stro~·s th e mic ro
~rga ni sms t hat cause lll e~t,
age. burn does not rende r th e food rad1 oacuve o r ca use n to
lose its nu t riti ve I SpotJ.
. p!i mary advantage assoc iated_ wi th irradia tmg foods is irs
success :n kill ing :~t·
ri a wuh m raw mea t an d prod uce. It 1s th e only kn own met
ho d o f eliminating th e b~ctt-
dea dl y bacte ri a Escherichia co l, , Salm o nella, an d
Campylobact er fro m ra w fru iJ'°t~ntla.l]y
rab!cs. _Typi~a ll y, fruits and vege tabl es t~lcra te an irra diat
io n o f 1.0 kGy (Sccriona~6 ·~ c-whic h macava rcs 99.999%
of the baccen a. .S B),
Al th oug h ga mm a-ray irradi atio n elimi nac es pes ts in fresh
foods and ex tends h •
Li fe, irradia ti o n also creates free ra dica ls, th e presence of
w hic h could ncgari vcl t ~u- shdf
inhe rem quality o f foods by produci ng small a mo unts o f und

esi rabl e substa nce: ~ f the
the re !s no tec hnical basis for concludin.g th a_r c~ ese irra
dia ted _foods a re un safe t~ co~:~
the wi desp rea d use o f ga mma rays fo ~ 1rrad1 atm g foo ds
rema ms a co ntroversial b' '
. FDA's appro va l is rcq~ired to sell irradiat ed foo~s i~
America n stores. As a c~::~m
of us arpr<:'va l, FDA reqmrcs m.:muf~c tur~rs an d d1
smburors to affix th e Radura symbol
show n m Fig ure 16.3 on packages of 1rrad1 a tcd foods . FDA
also requ ires food di scr·b
to ma rk packa ges of irra dia ted foo ds wi th ei th er of th e
foll o wing statements:
1
utors
TREATED WITH RADI ATION
TREATED BY IRRADIATION
. Sca led ra d iatio n sour ces a re highly dange ro us if th ey
beco me un sea led. Ac kn owledg-
ing th e need to wa rn people of th e prese nce of ra di oisoto
pes in sea led sources the Uni ted

~atio ns' lnrcrn ati~ na l. Atomic Ener~y Age ncy, o r IAEA,
and th e Intern a ti o n; I Organiia-
n_o n fo r Srand a rd1zat1o n, or ISO, int ro du ced the io nizing
rad ia ti o n sy mb ol shown in
F,g u~e 16.4. The symbol shows waves ra di ati ng fro m a thr
ee- bla d ed propell er ca lled a
trefo il, a skull-a nd-crossbones sym bol, a nd a ru nni ng pe rso
n .
. l ~EA an~ ISO reco mmend a ffi xi ng this sy mbo l to d ev
ices th a r ho use a hig h-ltvd
radw1soto pe ma sealed so urce, ex posure to w h ic h co ul d ca
use d ea th or se rio us injury.
The sea led so urce us uall y is a sea led caps ul e rh a1 co nt ai
ns th e ra di o isoto pe. ft is funhcr
sealed be t ween laye rs of non rad ioactive ma teria l o r firm!
)' fi xed ro a no nr adioactive sur-
face by electropla ting o r o cher mea ns to preve nt lea kage o r
esca pe of th e radioisotope.
FI GU RE 16. 3 At 2 1 C FR §179 26(c.). FDA req uires th is
international
Radura symbo l to be poste d on 1rrad1ated pack.aged foods,
bulk con-
t.Mers of unpackaged foods, on placards at the point of pu rcha

se for
fresh produce , and on ,nvo rces for 1rrad 1ated 1ngred ren 1s
and prod ucts
so ld to food processors The logo 1s da1k green and displayed o
n a
w hrt e back.ground (Cou nesy of FDA-food and Dn.ig
Admm,srra1,on l
694 Chapter 16 Rad ioactive Ma terials
FIGU RE 16 .4 The lAEA/ISO 1o n,z,n g rad,at1on symbol
u~ed to warn 1nd,v1 dua ls that a dangerous le~ el of ,on -
1w19 rao ,a1,on 1n a sealedra01oact,vesource 1s nearby
The tnangular sym bol ,s red w ith a black border and has
black.andwh1tewavesr ad•at,ngfromat1 efo 1l, ask ull-
and<rossbones symbol, and a runn ,ng person
l'o rnia ll y th e radio iso 1o pe is vis ibl e o nl y when attempts
ar c ma d e to di sa sse mble th e
~q uipment in wh ic h ir is maintai ned. The intent of th e io ni
zi ng ra d ia ti o n symbo l is to
wa rn people 10 di sta nce themselves from the radi ation so
urce. Because it is no t a ffixe d to
bui ld ing• access d oors, co nt a iners, o r tran spo rt ve hicles,
th is sy mbol suppl e me nts rhe

warni ng trefoil requir ed by NRC, O SH A and DOT o n signs,
labels, a nd placa rd s.
16.4 DETECTION OF RADIOACTIVITY
Seve ral ra di a tion detec tio n instruments arc commercia ll y
ava il able. The ty pe sho w n in
figure 16. 5 o ft en is used by emergency res po nders for detec
ting th e prese nce o f a ra d ia·
cion source . T he o perator may specificall y dc1erminc w heth
er a r.i di ;1 cio n so urce is nea rb y,
how close it is, its ident ity, and it s intensity.
The to tal ra diat io n to whi ch an indi vidual has been exp
osed, includin g the o ccupa-
tiona l rad ia tio n d ose, is determ ined thro ugh th e use o f
perso na l-mo nitor ing equ ipment
like t he o pti ca ll y stimula ted luminesce nt do si meters sho
w n in Figur e 16. 6(a ) and th e
pocket o r pe n d osimeters illustrated in Fi gure 16.6 (b ).
FIGURE 16. 5 A portable handheld rad iat ion
detector 1s commonly used by first-on -the-sce ne
responders to measure the 1ntens1ty of alpha , beta ,
gamma. and X-ray rad iat ion Th,s model is know n
as the inspector Its d1g1tal d is play provides 1ead1ngs

,n m1ll1roentgens pe r hour (mR/h), counts per
m,nute (c/m1nl, or m,cros1eve rts pe r hour (µSv/h)
(Cour-resyof S f ln tema r<OOJI, Inc . Sommeno-.-m,
Tennessee )
r
I
I
FI GU RE 16 .6 (a ) Ootr•
c,f'y!itlmu lat ed lum,nes•
centdosme:e rs and (b)
pocl.e t or pen dos1me1e-s
The use of these dos m-
eters prc ces a measure-
ment of the total amount
of raoiauon to wh 1Ch an
1nc v o'u.:1J hasbeen
~ !COJt?PSy of

Ldl'lddl.lt'C/r>c,G~~
IUtnois.MT.JS. E ltltf'ma11MtJI,
O:..~n. _ ,
lb!
,,,
696 Chapter 16 Radioactive Materials
16,5 UNITS OF RADIATION AND RADIATION DOSE
fhe 1ntensi ry ~f rafois~ IO~c is called its activity, and the
ac1iviry per unit mass is called
its specific ~ct•v•ty : 5 sc ie n_ns~s developed radi atio n
detection instruments, they simulta-
n(OII SI}' defmed l~~ns of.r~dia uon meas~ remcnt to serve as
a means of accounting for the
JCllvit y of a specific rad101 sotopc. We cite them in the
following sect ions.
16.s -A UNITS O F ACTIVITY
Each type of ra~iation ?:rector provides the intensity of a
radioisotop e by counting the
nu mber of n~clei t~ a t dlSl~teg_~te duri~g a time period. The
intensity of the radioisotope

niaY be prov1~ed directl_y m d1smtegrat1ons per second, or it
ma y be converted into mul -
tiples or fracnon s of units called the curie and becquerel.
The curie (Ci) is a meas ure of the number of radioactive dis
integrations occur-
r11lg each seco nd in a sample. One curie is the amount of
radiation equal to 3.7 X 10 10
disintegrations per seco nd. Because the curie is an extremely
large unit, th e intensity of
a sam ple of a radioactiv e mat erial usually is measured in
millicuries (mCi), microcuries
(µCi ), and picocuries (pCi ).
lmCi = 3.7 x 107 disimegrations/s
1µ.Ci = 3.7 x 104 disimegrarions/s
lpCi = 3.7 X 10 - 2 disintegration s/s
T he becquerel (Bq) is the SI unit used to measure radioactive
disintegrations per
secon d. One Bq is equivalent to one nuclear disintegration per
second, which can be writ-
ten as follows:

!Ci= 3.7 X JO"Bq
Intensity
of a radiation source
i peclfic act iv ity • The
activity of a rad ioi so -
tope per unit mass
curi e (Ci) • The amount
of a rad io isotope that
decays at the rate of
3 .7 x 1010 disintegra -
tions per second
be cqu erel ( Bq) • The SI
unit of radioactivity
equivalent to 1 disinte-
gration per second
The becquerel is a small amount of :ictivity; hence, it generally
is used with a prefix lik e
tera-. EPA, DOE, and NRC regulations usually list the activities
of radioisotopes in tera-
becquerels (TBq) and curies. One TBq equals a trillion

becquerels or a trillion disintegra·
tions per seco nd.
ITBq = 10 12 Bq
SOLVED EXERCISE 16.3
Te< hneti um -99m 1s used dunng diagnostic Imaging of th!!
body's internal or gans When a rad,olog1cal technlaan
,n,em a patient intr avenously with 24 .5 mCI of t echnetium-
99m , how many be<querels of the rad101sotope were
rece ,vedbythe patient ?

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