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Los Alamos Radiation Monitoring Notebook Los Alamos
Radiation Monitoring
Notebook
LA-UR-00-2584
James T. (Tom) Voss, NRRPT, CHP
June 2000
(Feb. 2001 Update) TABLE OF CONTENTS
Page #
Abbreviations
3
Conversion of Units
4 7
Constants
7 - 8
Rules of Thumb
8 - 16
Units and Terminology
17
Radiation Interactions
18
Public Radiation Dose Rates
19
Radon Facts
20
Biological Effects of Radiation
21
Dosimetry
22 - 24
Equivalent Dose, Effective Dose, and Committed Effective Dose
25
Radiation Weighting Factors
26
Calculating TODE and TEDE
27
Effects of Radiation Exposure
28
Table of the Elements
29 - 30
Radioactive Decay Chart
31 - 32
Reporting Radiological Data
33
Surface Contamination Correction Factors
34 - 35
Detector Efficiency
36
Alpha & Beta Crosstalk
36
Correction Factors for Efficiency
36
Inverse Square Law
37
Shallow Dose Correction Factors
37
Stay-Time Calculations
37
Calculating Exposure Rate in an Air-Filled Ionization Chamber
38
Calculating Percent Resolution of a Gamma Spectroscopy Detector
38
Calculating True Count Rate Based on Resolving Time of a Gas-Filled Detector
38
Calculating Gamma-Ray Constant
39
Calculating Photon Fluence Rate from a Point Source
39
Calculating Exposure Rate from a Point Source
39
Page 1 TABLE OF CONTENTS
Page #
Calculating Dose Rate to air from a Point Beta Source
39
Calculating Exposure Rate from a Line Source
40
Calculating Exposure Rate from a Disk Source
40
Calculating 6CEN
40
Calculating Airborne Radioactivity
41
Respiratory Protection Factors
41
Air Monitoring Calculations
42 - 44
Surface Area Calculations
45
Volume Calculations
46
Gamma & Neutron Half-Value Layers
47
Shielding Calculations
48 - 50
Shielding Materials
51
Calculating Transmission Factor (X-ray)
51
Density of Various Materials
52
Radioactive Decay Graphs
53 - 54
Table 1 of DOE 5400.5
55
Appendix D of 10CFR835
56
Posting
57 - 58
Instrument Use and Selection
59 - 60
DOT 49CFR173
61 - 62
Specific Activity
63 - 64
Characteristic Radiations of Radionuclides
65 - 72
Specific Activity vs. Radiation Levels
73 - 76
Gamma Exposure vs. Particle Size
77 - 78
Ingestion and Inhalation ALIs
79 - 86
Activity vs. Particle Size
87 - 88
Emergency Response
89 - 92
Facility Hazards
93
Thorium-232 and Uranium-238 Decay Chains
94 - 96
Calendar Years 2001 and 2002
97 - 98
Alphabetical Index
99 - 100
Page 2 ABBREVIATIONS
ampere
A, or amp
angstrom unit
D
, or A
atmosphere
atm
atomic weight
at. wt.
cubic foot
ft
3
, or cu. Ft.
cubic feet per minute
ft
3
/min, or cfm
cubic inch
in
3
, or cu. in.
cubic meter
m
3
, or cu. m.
curie
Ci
day
day, or d
degree
deg, or
0
disintegrations per minute
dpm
foot
ft.
gallon
gal.
gallons per minute
gpm
hour
h, or hr
inch
in.
liter
L
meter
m
micron
µ
,
µ
m, or mu
minute
min, or m
pounds per square inch
lb/in
2
, or psi
roentgen
R
second
sec, or s
square centimeter
cm
2
, or sq cm
square foot
ft
2
, sq ft
square meter
m
2
, or sq m
volt
V, or v
watt
W, or w
year
yr, or y
Page 3 CONVERSION OF UNITS
Multiply by To Obtain
To Obtain by Divide
Length
Angstroms
1 E-8
centimeters
Inches
2.54
centimeters
meters
3.2808
feet
kilometers
0.6214
miles
miles
5280
feet
microns (
µ
m)
1 E-6
meters
mils
1 E-3
inches
Area
Acres

43,560
square feet
Barns

1 E-24
square centimeters
Square centimeters
0.1550
square inches
Square meters
10.764
square feet
Square meters
3.861 E-7
square miles
Square miles
640
acres
Volume
Cubic centimeters
3.531 E-5
cubic feet
Cubic centimeters
1 E-6
cubic meters
Cubic feet
28.316
liters
Cubic feet
7.481
gallons
Liters

1.057
quarts
Liters
0.2642
gallons
Cubic meters
35.315
cubic feet
Cubic meters
1,000
liters
Milliliters
1
cubic centimeters
Page 4 CONVERSION OF UNITS
Multiply by To Obtain
To Obtain by Divide
Time
days
1440
minutes
days
86,400
seconds
work week
1.44 E5
seconds
work month
4.33
work weeks
work month
173.3
work hours
years (calendar)
365
days
years

8,760
hours
years
5.256 E5
minutes
years
3.1536 E7
seconds
Density
grams / cm
3
62.428
pounds / cubic foot
grams / cm
3
8.345
pounds / gallon
Pressure
atmospheres
1.0133
bars
atmospheres
1,033
grams / cm
2
atmospheres
14.70
pounds / in.
2
atmospheres
760
mm Hg @ 0
0
C
atmospheres
29.921
inches Hg @ 32
0
F
atmospheres
33.90
feet H
2
O @ 39.2
0
F
bars
1 E6
dynes / cm
2
dynes / cm
2
1.0197 E-3
grams / cm
2
grams / cm
2
0.01422
pounds / square inch
Torr
1
mm Hg @ 0
0
C
Energy
ergs
6.242 E11
electron volts
ergs
2.390 E-8
gram calories
electron volts
1.602 E-12
ergs
Page 5 CONVERSION OF UNITS
Multiply by To Obtain
To Obtain by Divide
Mass
grams
0.03527
ounces
kilograms
2.2046
pounds
pounds
16
ounces
pounds
453.59
grams
Others
amperes
2.998 E9
electrostatic units / sec
amperes
6.242 E18
electronic charges / sec
coulombs
6.242 E18
electronic charges
radians
57.296
degrees
Radiological
rads
100
ergs / gram
rads
6.242 E13
electron volts / gram
roentgens
87.7
ergs / gram of air
roentgens
1.61 E12
ion pairs / gram of air
roentgens
5.47 E13
electron volts / gm of air
sievert
100
rem
curies
3.7 E10
dps
curies
2.22 E12
dpm
µcuries / sq. meter
220
dpm / cm
2
megacuries / sq. mile
0.386
curies / square meter
dpm/m
3
4.5 E-13
microcuries / cm
3
bequerels
2.7027 E-11
curies
bequerels
1
dps
BTU
1.28 E-8
grams
235
U fissioned
BTU
1.53 E-8
grams
235
U destroyed
BTU
3.29 E13

fissions
fission of 1 g
235
U

1
megawatt-days
fissions
8.9058 E-18
kilowatt-hours
fissions
3.204 E-4
ergs
Page 6 CONVERSION OF UNITS
Multiply by To Obtain
To Obtain by Divide
Power
joules/sec
1 E7
ergs / second
watts
1 E7
ergs / second
watts
0.001341
horsepower
watts
3.1 E10
fissions / second
MULTIPLES AND SUBMULTIPLES
10
12
tera
T
10
-1
deci
d
10
9
giga
G

10
-2
centi
c
10
6
mega
M
10
-3
milli
m
10
3
kilo
k
10
-6
micro
µ
10
2
hecto
h
10
-9
nano
n
10
1
deka
da
10
-12
pico
p
10
0
1
1
10
-15
femto
f
10
-18
atto
a
GREEK ALPHABET
Alpha
Nu
Beta
Xi
Gamma
Omicron
Delta
Pi
Epsilon
Rho
Zeta
Sigma
Eta
Tau
Theta
Upsilon
Iota
Phi
Kappa
Chi
Lambda
Psi µ
Mu
Omega
Page 7 CONSTANTS
Avogadro's number (N
0
)
6.02252 E23
electron charge (e)
4.80298 E-10 esu
electron rest mass (m
e
)
9.1091 E-28 g
acceleration gravity (g)
32.1725 ft / sec
2
@ sea level & 45
0
latitude
980.621 cm / sec
2
Planck's constant (h)
6.625 E-27 erg-sec
velocity of light (c)
2.9979 E10 cm / sec
velocity of light (c)
186,280 miles / sec
ideal gas volume (V
0
)
22,414 cm
3
/ mole (STP)
neutron mass
1.67482 E-24 g
proton mass
1.67252 E-24 g
ratio of proton to electron mass
1,836.13
natural base of logarithms (e)
2.71828 3.14159
A gram-molecular weight of any gas contains (Avogadro's number), N
0
(6.02252 E23)
atoms and occupies a volume of 22,414 cm
3
at STP.
Temperature
0
C = (
0
F - 32)(5/9)
0
F = 1.8
0
C + 32
0
K =
0
C + 273.1
0
R =
0
F + 459.58
Conversion Equations
grams/sq. cm
=
density (g/cm
3
) x thickness (cm)
Photon energy (keV) =
12.4/wavelength (A)
Page 8 RULES OF THUMB FOR ALPHA PARTICLES
1.
An alpha particle of at least 7.5 MeV energy is needed to penetrate the nominal
protective layer of the skin (7 mg / cm
2
or 0.07 mm).
2.
The alpha emissions and energies of the predominant particles from 1 µg of several
common materials are:
DPM per µg
Alpha Energy (MeV)
238
Pu
39,000,000
5.50 (72%)
239
Pu
140,000
5.15 (72.5%)
240
Pu
500,000
5.16 (76%)
242
Pu
8,700
4.90 (76%)
a
Natural U
1.5
4.20 (37%), 4.77 (36%)
Oralloy (93%
235
U)
160
4.77 (~ 80%)
b
Natural Th
0.5
4.01 (38%), 5.43 (36%)
D-38 (DU, tuballoy)
1
4.20 (~ 60%)
a
Includes
234
U in equilibrium.
b
Includes
228
Th in equilibrium. Depending upon the time since chemical separation,
228
Th can decrease to give a net disintegration rate lower than 0.5.
c.
With 2 (50%) geometry, the surface of a thick uranium metal (tuballoy) source gives
~ 2400 alpha counts/min per cm
2
. Depleted uranium (D-38) gives ~ 800 alpha cpm/cm
2
.
3.
Alpha particle range in cm of air at 1 atmosphere
R
a
= 0.56 E (E <4 MeV)
R
a
= 1.24 E - 2.62 (E > 4 MeV)
Alpha particles lose about 60KeV of energy per mm of air at 1 atmosphere.
Page 9 RULES OF THUMB FOR ALPHA PARTICLES
4.
Detector window thicknesses cause alpha particles to lose energy at about 1 MeV per
mg/cm
2
of window thickness. Therefore, a detector with a window thickness of 3 mg/cm
2
(such as sealed gas-proportional pancake alpha/beta detectors and pancake