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Transcript
Radiation Safety
Capt. David Ayre CAP, SWR-TX-176
RADIATION
The definition of
radiation is the
emission (sending out)
of waves and/or
particles thru space.
TYPES OF RADIATION
TYPES OF
RADIATION
IONIZING OR
NON IONIZING
•
•
•
•
•
•
•
•
•
•
heat
light
radio waves
x-rays
nuclear
non -ionizing
non - ionizing
non - ionizing
ionizing
ionizing
Nuclear Radiation
One source of radiation is the nuclei of an unstable
atom. These radioactive atoms become more stable
when the nuclei ejects or emits subatomic particles
and/or high-energy photons (gamma rays).
This Is the Way the Atom Probably
Looks
Atomic Structure
Electron
Nucleus
Proton
Neutron
Atomic Number
Atomic number (Z number)
is the number of PROTONS in
the nucleus of an atom.
Atomic Mass
Atomic Mass
(A number),
is the number of
PROTONS plus
the number of
NEUTRONS in
the nucleus of an
atom.
Mass and Charges of
Basic Atomic Particles
Mass
Charge
1 amu
+1
Neutron
1 amu
0 or
neutral
Electron
1/2000
amu
-1
Proton
ISOTOPE
Atoms with the same atomic number,
.
but different atomic mass
Carbon-12
(6P + 6N)
Atomic Mass = 12
Carbon-13
(6P + 7N)
Atomic Mass = 13
Carbon-14
(6P + 8N)
Atomic Mass = 14
6 Protons
6 Protons
6 Protons
6 Neutrons
7 Neutrons
8 Neutrons
IODINE ISOTOPE EXAMPLE
Isotope
Atomic Mass
Atomic
Number
Number of
Neutrons
I 123
123
53
70
I 125
125
53
72
I 131
131
53
78
Discovery of Radiation
Henri Becquerel
1896
Ernest
Rutherford
Wilhelm
Roentgen 1895
Marie Curie-To describe the behavior of
uranium and thorium she invented the word
“radioactivity” --based on the Latin word for ray.
RUTHERFORD’S
EXPERIMENT
Photographic
Plate
TYPES OF RADIATION
Types of
Radiation
Mass
Charge
Stopped By
Alpha
4
+2
Thin Sheet of
Paper
Gamma
Ray
No Mass
No Charge
Several Inches
of Lead or Steel
X Ray
No Mass
No Charge
Several Inches
of Lead or Steel
Beta
1/2000
-1
Thin Aluminum
0
High Hydrogen
Content
Neutron
1
Electromagnetic Spectrum
INDUSTRIAL USES OF
RADIOACTIVE MATERIALS
Power Plants
Medical
Farming
Ranching
Textile
Auto
Soda Can
CASES OF HIGH OCCUPATIONAL
EXPOSURE TO RADIATION
Early Scientists
Watch Dial Painters
Nuclear Weapons Research
Military Personnel
Emergency/Medical Personnel
COMMON PREFIXES
Giga (G) = 1 billion
Mega (M) = 1 million
kilo (k) = 1 thousand
milli (m) = 1 thousandth
micro (u) = 1 millionth
UNITS OF MEASUREMENT
Curie
A UNIT used to
measure
the activity of a
radioactive source and
equals
37,000,000,000
disintegration's per
second.
The SI UNIT is the
_____Becquerel____
which is one nuclear
transformation or
one disintegration
per second.
UNITS OF MEASUREMENT
Roentgen
A measure of the
ionization effect
Gamma
and
X radiation
have in AIR.
UNITS OF
MEASUREMENT
REM
A measure of the
biological effect
radiation has on man.
REM
stands for
Roentgen Equivalent Man
Half-Life
The time required for the amount of
radioactive material to decrease by one
half.
Original
Material
Material after
one Half-Life
Material after
two Half-Lives
HALF-LIVES OF VARIOUS
ISOTOPES
HalfIsotope
Life
Am 241
454 Years
Cs 137
30 Years
Ra 226
1602 Years
I 131
8 Days
Co 60
5.2 Years
Detecting Radiation and the
PHOTOGRAPHIC PROCESS
FILM BADGES
Radiation will
expose film just as
light will.
The greater the dose
of radiation the
darker the film
will become.
THERMOLUMINESCENT
DOSIMETER
TLD’s use three
chips that when
exposed to radiation
store the energy.
When the chip is
heated it gives off
light proportional to
the radiation
absorbed.
LANDAUER
John Doe
JAN 01, 1997 Z1
N
030000 T29
07469
0561420
T
OPTICALLY STIMULATED LUMINESCENCE (OSL)
DOSIMETER
OSL’s use two thin Al2O3 strips which when
exposed to radiation record Photons (X & d
Rays) in the 5 keV / 40 MeV range & Beta
Particles in the 150 keV / 10 MeV range.
During analysis, the Al2O3 is stimulated with
selected frequencies of laser light, which cause it
to become luminescent in proportion to the
amount of radiation exposure received.
A third component, for the measurement of
Neutrons, is also enclosed. This is a Neutrak 144
Allyl Diglycol carbonate solid state track
detector. In this case measurement is made by
chemical etching followed by track counting.
Energies measured are between 100 keV / 30
MeV.
JOHN
DOE
TRAINING
luxel
LANDAUER
FRONT
®
OPTICALLY STIMULATED
LUMINESCENCE (OSL)
DOSIMETER
Dose Measurement Range
Photon
Beta Particle
Neutron
1 mREM to 1000 REM
10 mREM to 1000 REM
20 mREM to 25 REM
01 - 01 - 99
0030000 T29 04839
Whole Body (chest)
Accuracy
0554677A2
Shallow Dose = ±15% at the 95% confidence
interval for photons above 20 keV and beta
particles above 200 keV
3073719
Deep Dose = ±15% at the 95% confidence
interval for photons above 20 keV
BACK
OPTICALLY STIMULATED
LUMINESCENCE (OSL) DOSIMETER
The OSL is the principle device
used to measure radiation
exposure personnel.
John
Doe
The OSL will only measure what
your body will receive and does not
TRAINING
“protect” from
luxel
LANDAUER
®
radiation.
A OSL will simply measure what
you have been exposed to and will
allow us to determine if you have
received to much radiation.
RADIATION
MONITORING
Radiation Quality is an indication
of the type of radiation received
Radiation Quality
Type of Radiation Received
P
Gamma Only
CPN
Combination Gamma and Neutron
NF
Fast Neutron
M
Minimal (Less than 1.0 mR)
MAXIMUM PERMISSIBLE
EXPOSURES
5 REM per Year
Lifetime Dose – ( Age - 18 ) * 5 REM
Recommended exposure while pregnant
500 mREM
Average exposure for Wireline
Logging & Perforating Personnel
150 - 250 mREM per Quarter
Detecting Radiation and the
ENCLOSED GAS VOLUME PROCESS
Voltage Source
+
-
Incident Ionizing Radiation
Anode +
Inert Gas
Electrical
Current
Measuring
Device
Cathode -
Geiger-Mueller Counters
An enclosed tube has an anode and a cathode and usually an
inert gas inside the tube. The radiation enters the tube
ionizing the gas thus creating a current flow. The amount of
radiation is proportional to the current flow.
Detecting Radiation and the
SCINTILLATION CRYSTAL PROCESS
Gamma Ray

Preamp
e-
P
e-
High
Voltage
ee-
e-
e-
Dynodes
Photo-Cathode
Optical
Coupling
Grease
Scintillating
Crystal
Glass
Vacuum Tube
Photo-Multiplier
Tube
e- Electrons
P Photons
Detecting Radiation and the
Direct-Read Pocket Dosimeter
A
+
+
DIRECT - READING POCKET DOSIMETER
A. Charging Rod
B. Metal Support for Fibers
C. Movable Fine Metal Coated
Quartz Fiber
D. Transparent Scale
+
-
B +
C
-
LENS
D
Milliroentgens
0 50 100 150 200
LENS
EYE
PIECE
VICTOREEN MODEL 493
Scale reads from
0 to 0.5
Switch positions are:
• Off
mR/h
0.2
• bat.
• x100
• x10
• x1
0.1
0.3
B AT .
0.4
c/m
0
PHONE
VICTOREEN
0.5
493
VICTOREEN
Ludlum Model 2
LUDLUM MODEL 2
SURVEY METER
Scale Reads from:
0 to 5
0
Switch Position Are:
• OFF
• BAT
• X 10
•X 1
• X 0.1
1
2
3
mR/h
ON
F
OFF
S
A
U
D
O
F
F
4
5
BAT
X 10
X1
HV
X 0.1
LUDLUM
MEASUREMENTS, INC.
SWEETWATER,TEXAS
MODEL 2
SURVEY METER
EXPOSURE RATE
VICTOREEN 493
mR/h
0.2
0.3
0.1
0.4
0
0.5
LUDLUM MODEL 2
2
1
0
3
4
5
What exposure rate is this
meter reading?
X 1 _______mREM/hour
X 10 _______mREM/hour
X 100_______mREM/hour
What exposure rate is this
meter reading?
X 0.1 ______mREM/hour
X 1.0 ______mREM/hour
X 10 ______mREM/hour
OCCUPATIONAL DOSE RATES
_____ mREM/hour
100 mREM/year
(General Public)
500 mREM/year
(If Attended Awareness Training)
5 REM/year
BACKGROUND RADIATION DOSE
Source
Radiation Received
Radon Gas
200 mREM/year
Daughter Products
28 mREM/year
Food & Water
40 mREM/year
Cosmic Rays
28 mREM/year
Medical Radiation
53 mREM/year
T.V. Consumer Products
7 mREM/year
TOTAL 356 mREM/year
RADIATION DOSES FROM OTHER
SOURCES
SOURCE EXPOSURE
•
•
•
•
•
•
One Hour of Jet Flight at 37,000 Feet
Chest X-Ray or Dental Exam
Dose to Unborn Child Due to Background
Pelvic Exam
Lower GI Series
Areas of High Background
2 mREM/hour
10 mREM/hour
200 mREM/hour
600 mREM/hour
700 mREM/hour
Up to 5000 mREM/year
Biological Effects Due to Exposure
Can Be Divided Into Two Groups
EARLY EFFECTS
(ACUTE)
Blood Count Changes
Damage
Vomiting
Cancer Risk
Nausea
Life Span
Death
LATE EFFECTS
(DELAYED)
Genetic
Increased
Shortened
Some Acute Effects of High Exposure
Over a Short Period Are
DOSE (1 week)
EFFECT (30 days)
•
30-150 REM
Detectable changes in blood counts
•
150-250 REM
Nausea and vomiting within 24 hours
•
250-350 REM
Death may occur
•
350 REM
50% will Die within 30 days
•
350-600 REM
Death will probably occur
•
over 600 REM
100% will die
within 30 days
Estimated Loss of Life Expectancy
From Health Risks
HEALTH
RISK
ESTIMATES OF DAYS OF
LIFE EXPECTANCY
LOST, AVERAGE
Smoking 20
Cigarettes/Day
2370 (6.5 years)
OVERWEIGHT
(by 20 %)
435 (1.2 years)
RISK CHART
CONTINUED
AUTO ACCIDENTS
200 DAYS
ALCOHOL
CONSUMPTION
130 DAYS
RISK CHART
CONTINUED
HOME
ACCIDENTS
95 DAYS
DROWNINGS’
41 DAYS
RISK CHART
CONTINUED
SAFEST JOBS
(SUCH AS ………………..)
30 DAYS
NATURAL
BACKGROUND
RADIATION (Calculated)
8 DAYS
RISK CHART
CONTINUED
1 REM Occupational Radiation Dose
Calculated (Industry Average Is 0.34 REM/year)
1 DAY
1 REM/year for 30 Years, Calculated
30 DAYS
5 REM/year for 30 years, Calculated
150 DAYS
Everyday Items Containing
Radioactive Materials
Scale Found on Oil Field
Pipe
Brazil Nuts
Smoke Detectors
Lantern Mantles
Some Ceramics
Salt Substitutes
ALARA PRINCIPLE
ALARA
stands for
AS LOW AS REASONABLY ACHIEVABLE
REDUCING YOUR
EXPOSURE
The three most important safety
rules to remember while
working with radiation are
Time
Distance
Shielding
The Effect of Time on Radiation
Exposure
EXPOSURE = DOSE RATE X TIME
For Example: 495 mREM per hour
1 HOUR = 495 mREM
2 HOURS = 990 mREM
3 HOURS = 1485 mREM
The Effect of Distance on Radiation
Exposure
The Equation for Calculating
Radiation Exposure as a
Function of Distance:
I 1 x ( D1 ) 2 = I 2 x ( D 2 ) 2
OR
I 2 = I 1x ( D 1 ) 2
(D2)2
SHIELDING
GAMMA RAYS
DEFINITION
OF
SHIELDING
Using some
material as a
shield to reduce
the radiation
exposure.
SHIELD
SHIELDING MATERIALS
ALPHA
PAPER
GAMMA
BETA
LEAD
TIN
NEUTRONS
WATER
SKIN
STEEL
THIN
ALUMINUM
WAX
SEVERAL
INCHES OF
AIR
GOLD
DEPLETED
URANIUM
PARAFFIN