19/04/23 radiation safety - level 5 1

Radiation safetyRadiation safetylevel 5level 5

Frits Pleiter

19/04/23 radiation safety - level 5 2

ContentsContents

atomic and nuclear physics (1) interaction with matter (3)

o sources and x-ray equipment (2)o shielding (3)o detection (4)o radiobiology (6)

• objective risk of radiation (6)• subjective risk acceptation (6)

quantities and units (5) regulations (7)

o practical health physics (8 - 10)o waste (11)

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Atomic and nuclear physicsAtomic and nuclear physicsatomic structureatomic structure

AZsymbol

Z electronsZ protonsN neutronsN ZA = Z + N 2Z

proton mass 2000 electron massatomic mass nuclear mass

electron

proton

neutron

42He

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Atomic and nuclear physicsAtomic and nuclear physicsatomic structureatomic structure

electrons are grouped in shellsenergy transfer excitation and ionization vacancies in shell

unit of energy:joule (J)electron volt (eV)1 eV = 1.610-19 J electron

proton

neutron

73Li

excitation

ionization

K

L

M

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Atomic and nuclear physicsAtomic and nuclear physicsatomic structureatomic structure

vacancy is filledx-ray photon

EK = BK – BL

Auger electronEKLL = BK – BL – BL

low Z Auger emission prevailshigh Z x-ray emission prevailsthese are competing processes

K

L

X-ray

L

K

Auger electron

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Atomic and nuclear physicsAtomic and nuclear physicsperiodic system according to Mendelejevperiodic system according to Mendelejev

H He

Li Be B C N O F Ne

Na Mg Al Si P S Cl Ar

K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr

Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe

Cs Ba * Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn

Fr Ra ** Rf Db Sg Bh Hs Mt Ds Rg 112 114

* La Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu

** Ac Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

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Atomic and nuclear physicsAtomic and nuclear physicsnuclide chartnuclide chart

isotopes equal Zisobars equal Aisomers equal A and Z

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Atomic and nuclear physicsAtomic and nuclear physicsmathematical intermezzomathematical intermezzo

addition8 = 5 + 3 additioninverse function

8 = ? + 3 ? = 8 - 3 subtraction8 = 5 + ? ? = 8 - 5 subtraction

multiplication15 = 5 3 multiplicationinverse function

15 = ? 3 ? = 15 / 3 division15 = 5 ? ? = 15 / 5 division

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Atomic and nuclear physicsAtomic and nuclear physicsmathematical intermezzomathematical intermezzo

exponentiation9 = 32 exponentiationthere are two inverse functions

9 = ? 2 ? = 29 root9 = 3 ? ? = 3log(9) logarithm

we call 3 the base of the logarithmthe "natural" logarithm has base e = 2.71828182847...we write the natural logarithm as ln(x)

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Atomic and nuclear physicsAtomic and nuclear physicsmathematical intermezzomathematical intermezzo

logarithm23 25 = 28

3 = 2log(23)5 = 2log(25)8 = 2log(28) 3 + 5 = 8

2log(23) + 2log(25) = 2log(28) = 2log(23 25)

in general: xlog(a) + xlog(b) = xlog(a b)

the logarithm makes it possible to multiply with the aid of a ruler

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Atomic and nuclear physicsAtomic and nuclear physicssingle logarithmic graph papersingle logarithmic graph paper

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Atomic and nuclear physicsAtomic and nuclear physicsdouble logarithmic graph paperdouble logarithmic graph paper

equal distancescorrespond toequal factors

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Atomic and nuclear physicsAtomic and nuclear physicsradioactive decayradioactive decay

unit of activitybecquerel (Bq)curie (Ci)

1 Bq = 1 decay per second1 Ci = activity of 1 gram radium

= 3.71010 Bq

the half-life T½ is the timeduring which the activititydecreases by a factor of two

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Atomic and nuclear physicsAtomic and nuclear physicsprefixesprefixes

milli (m) 10-3

micro (µ) 10-6

nano (n) 10-9

pico (p) 10-12

kilo (k) 103

mega (M) 106

giga (G) 109

tera (T) 1012

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Atomic and nuclear physicsAtomic and nuclear physics---decay-decay

Z = +1A = 0

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Atomic and nuclear physicsAtomic and nuclear physics---decay-decay

average -energy <E> E,max / 3

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Atomic and nuclear physicsAtomic and nuclear physics++-decay-decay

Z = -1A = 0

+ + e- 2 annihilationE = mec2 = 511 keV

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Atomic and nuclear physicsAtomic and nuclear physicselectron captureelectron capture

Z = -1A = 0

vacancy in electron shell is filled x-ray photon

Auger electron

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Atomic and nuclear physicsAtomic and nuclear physics-decay-decay

Z = -2A = -4

-particle = 4He nucleushigh riskstrongly regulated

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Atomic and nuclear physicsAtomic and nuclear physics-decay and internal conversion-decay and internal conversion

Z = 0A = 0

excess nuclear energy is released -photon

conversion electron

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Atomic and nuclear physicsAtomic and nuclear physics-decay and internal conversion-decay and internal conversion

these are competing processes

conversion electronEK = E - BK

K = NK / N

x-rayAuger electron

K

-rayE

K

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Atomic and nuclear physicsAtomic and nuclear physicsnuclear fissionnuclear fission

A A1 + A2 + neutrons + energy

A1 95A2 140energy 200 MeV

examples: 23892U 98

37Rb + 13755Cs + 3n

23592U + n 90

36Kr + 14456Ba + 2n

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Atomic and nuclear physicsAtomic and nuclear physicsdecay schemedecay scheme