1-nuc-stability-decay.pptx

8/18/2019 1-nuc-stability-decay.pptx

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Introduction to Nuclear

Engineering

Mahmoud Dorrah 1


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Lecturer’s CV …

Mahmoud Dorrah

[email protected]

01271330630

1. B.Ch. Medicine & General Surgery 1!!".

#. B.Sc. Nuclear Engineering #$$#.

". %ilo'a o( )ediatrics #$$".

*. M.Sc. Biohysics #$$+.

,. )h.%. Nuclear & -adiation Engineering#$1*.

Mahmoud Dorrah 2

mailto:[email protected]:[email protected]


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Course Contents

• Nuclear Stability & Decay

• Nuclear Reactions

• Radiation & Protection

•

Nuclear Fission• Nuclear Reactor & Production of Nuclear Energy

• Reactor Safety

• Nuclear Fuel Cycle

•

Nuclear astes• Nuclear Fusion

• !""lications of Radiation

• #ealth Physics

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Nuclear %ecay

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• 'he mass of a nucleus asdetermined e("erimentally is

slightly smaller than the sumof masses of its constituentelementary "articles)

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• For e(am"le ,ridium-1.1 nucleus ismade u" of ++ "rotons and 11%neutrons)

• 'herefore/ the combined mass of theelementary "articles is gi0en by

M 3 m" 4 N mn

++ 51)66+2+*%+7 4 11% 51)668**617

1.2)%86..$$ u

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• 'he true mass of 1.1,r nucleus is1.6).18$$.$$ amu/

•

'hat9s it is 1)*2.+* amu : thecombined mass of its elementary"articles 51.2)%86..$$ amu7)

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• 'he reason for this decrease inmass is that on fusion of "rotons

and neutrons to form thenucleus/ a gi0en amount ofenergy is released)

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• !ccording to Einstein;s e


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• 'he released energy is "roducedby con0ersion of some of the

total mass of the nucleus intoenergy 5Mass %e(ect7)

• 'he energy released by

combining neutrons and "rotonsto ma@e a nucleus is called the5Binding Energy3.

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Binding Energy er

Nucleon

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• Ma(imum Binding Energy erNucleon occurs at ,45e)

•

So/ 5usion of nuclei =ith ! : *increases the binding energy "ernucleon)

•

5ission of nuclei =ith ! A *increases the binding energy ernucleon)

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• ,ncrease Binding Energy erNucleon means a more stablenucleus)

• ,t also means the release of someenergy)

•

'his is the basis of generatingnuclear energy by 5usion or5ission)

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Nuclear %ecay

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Nuclear %ecay

• ! nucleus tends to attaingreatest "ossible binding energy

"er nucleon)• 'herefore/ a nucleus tends to

decay by a gi0en mode if the

binding energy "er nucleon ofthe "roducts is greater than itsbinding energy "er nucleon)

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• i)e)/ a nucleus tends to decayby a "articular mode if its

'ass is 6 the su' o( the'asses o( the roductsformed by that decay mode)

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• 'his means that nuclei =ith!AA166 are unstable to=ards

s"ontaneous ssion into t=onuclei of a""ro(imately halfits mass)

• !lso/ nuclei =ith !A1%6 tendto decay by emission)

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• !t 3:26/ the numbers of"rotons and neutrons are

a""ro(imately e


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• 'he Valley o( Sta7ilityre"resents the most

energetically fa0orable nuclides)• i)e)/ it is the combination of

neutrons and "rotons that yields

the highest binding energy "ernucleon)

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• E(cess neutrons at high massnumbers can be e("lained by

that the more "rotons "ac@edtogether in a nucleus/ thehigher the Columbic re"ulsion

5i)e) the lo=er the bindingenergy7)

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• 'herefore more neutrons areneeded to increase the

se"aration distance of the"rotons to decrease Columbicre"ulsion 5,n0erse S


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• For nuclides of lo= !/ greateststability is achie0ed =hen 3

N)• #o=e0er/ as ! increases/ the

stable NG3 ratio increases to 1)/ i)e) a larger number ofneutrons are needed to

maintain stability)Mahmoud Dorrah $%


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• 8hy i( the nu'7er o(neutrons is increased

7eyond N9: / 1., thenucleus ;ill 7e lesssta7le <

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• ,t follo=s that nuclides/ =hichlie a=ay from the H?alley of

StabilityI/ =ill be unsta7le/and tend to decay to=ardsthe HValley o( Sta7ilityI)

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=lha 0>3 %ecay

• !t masses 5!7 A 1%6/ many nuclidesmay decay by al"ha 57 emissiondue to the strong Columbic

re"ulsion bet=een the large numberof "rotons)

• - "articles are made u" of 2

"rotons and 2 neutrons 532/ N27)• i)e) - "article is a %#e nucleus)

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• !tomic Number 537 is decreasedby 2)

•

'he number of neutrons 5N7 isdecreased by 2)

• 'he !tomic Mass 5!7 is

decreased by %)

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).(4242. EnergyQ HeY X A Z Decay A Z ++ → −−α

%$


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α +→

+→

ThU

Or

HeThU

234

90

238

92

4

2

234

90

238

92

%%


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Negati?e Beta 0@A3%ecay

• Nuclei =ith e(cess number ofNeutrons can decay by negati0e

Beta decay 5JK7)• ! Neutron is con0erted into a

Proton =ith the emission of a

negati0e charge 5JK7 "article)• 5JK7 "article is actually an electron)

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• !tomic Number 537 is increasedby 5417)

•

'he number of Neutrons 5N7 isdecreased by 1)

• 'he !tomic Mass 5!7 remains

constant)

n → p + @-

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).(011.

EnergyQY X A

Z

Decay A

Z ++ → −+

−

β β

%.


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)ositi?e Beta 0@3%ecay

• Nuclei =ith e(cess number of Protonscan decay by "ositi0e beta 5J47

decay)• ! Proton is con0erted into a Neutron

=ith the emission of a "ositi0elycharged 5J47 "article)

• 5J47 "article is called a 5)ositron7)

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• !tomic Number 537 is decreasedby 1)

•

'he number of neutrons 5N7 isincreased by 1)

• 'he !tomic Mass 5!7 remains

constant)

→ n + +@Mahmoud Dorrah

).(011.

EnergyQY X A

Z

Decay A

Z ++ → +−

+

β β

$


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Electron Cature 0E.C.3

• Nuclei =ith e(cess number ofProtons can decay by ca"ture

of an orbital electron)• ! Proton is con0erted into a

Neutron)

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• !tomic Number 537 is decreased by 1)

• 'he number of neutrons 5N7 isincreased by 1)

• 'he !tomic Mass 5!7 remains constant)

e → n

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Y e X A Z Capture Electron A

Z 1

.

−

− → +

+


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Sontaneous 5ission

•*Fe has the highest bindingenergy)

•

Nuclides =ith ! A * ha0e lo=erbinding energies "er nucleon

• 'hose =ith ! AA 2 ( * tend to

s"lit into t=o nuclides5S"ontaneous Fission7 =ith therelease of some neutrons and

gamma "hotons)Mahmoud Dorrah .


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).()(

)(.

EnergyQniY Z X

i A A

Z Z

A

Z

FissionSpont A

Z +++ →

+′−

′−

′

′

*6

S i i


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Sontaneous 5ission

*1


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By the ;ay ….. DDD

Induced 5ission

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Neutron Induced 5ission

• ,t is not a 'ode on nucleardecay/ as it is articially induced)

• Some nuclei/ such as 2$>/ 2$8>/ and2$.Pu can be induced to ssion ifthey are bombarded by neutrons)

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• 'he ssion "roducts are not e(actlye


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)hoton Induced 5ission 0)hoto


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)hoton Induced 5ission 0)hoto5ission3

• !gain/ it is not a 'ode on nucleardecay/ as it is articially induced)

• Some nuclei/ such as 2$>/ 2$8>/ and2$.Pu can be induced to ssion if theyare bombarded by an energetic"hoton)

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• 'he ssion "roducts are not e(actlye


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Ga''a 5ission -eaction

*.


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Mahmoud Dorrah

شكر

+6


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1-nuc-stability-decay.pptx

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