Nuclear Radiation

Science Summaries

Below, I present a nuclear radiation detection information guide.
I am not a nuclear engineer. Some data may be incorrect.

1. Nuclear Radiation Detection Summary - for general information
          1. Common Radioisotopes (nuclides)
          2. Types of Nuclear Radiation (ionizing radiation)
          3. Radiation Detector Sensitivity Scales Compared
          4. CPM vs. mRem on Radiation Meter Dials - Probe Efficiency
          5. Annual Absorbed Dose - US Person
          6. Disclaimer
2. Geiger Counters Summary - for descriptions and pricing
3. Geiger Counter Data Compared - for sensitivity comparisons
4. Ludlum Radiation Product Summary - detection devices and probes
5. Victoreen CDV-700 6B Detector Summary - True Geiger Counter (antique)
6. Victoreen CDV-715 1A Detector Summary - Ion chamber detector (antique)
7. Victoreen CD V-750 5BDosimeter Charger - Charges CD quartz dosimeters
8. Uranium Ore Summary - common types of radioactive ore

Isotope
(Radio nuclide)

Radiation Emitted

Light Nuclides

Tritium (He3)
Carbon-14
Potassium-40
Cobalt-60*
Strontium-90
Technetium-99*
Iodine-129
Cesium-137
Bismuth-(many)

Beta
Pure beta
Beta, gamma
Beta, gamma
Pure beta
Beta, gamma
Beta, gamma
Beta, gamma
Beta, gamma

. 12 years
. . . . . . . . . . . 6,000 years
. . . . . . . . . . . . . . . 1,300,000,000 years
5 years
. . . 29 years
. . . . . . . . . . . . . . 212,000 years
. . . . . . . . . . . . . . . . .15,700,000 years
. . . 30 years
varies

Heavy Nuclides

Polonium-210
Radium-226
Radon-222
Thorium-230
Uranium-234
Uranium-235
Uranium-238
Plutonium-239*
Americium-241

Pure alpha
Alpha, gamma
Alpha
Alpha, gamma
Alpha
Alpha
Alpha
Alpha
Alpha, gamma

138 days . . . . . . . . . . . . . . . . . . . . .
1,600 years . . . . . . . . . . . . . . . .
3.8 days . . . . . . . . . . . . . . . . . . . . . . . .
75,000 years . . . . . . . . . . . .
244,500 years . . . . . . . . . .
(depleted) . . . . . . . .704 million years . . . . . .
4,500,000,000 years
24,000 years . . . . . . . . . . . . . .
432 years (smoke detectors) . . . . . .

For most people, radon is the biggest threat, due to its accumulation within buildings. Inhaled radon gas causes lung cancer.

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Ionizing Radiation

Shielding/ Detection

Dosage/ Danger

Alpha particles (helium nuclei)
Beta particles (electrons)
Gamma rays (x-rays)
Neutrons

Sheet of paper will shield
Sheet of aluminum will shield
Thick lead and/or concrete
Lead is ineffective

One sievert = 0.05 gray of alpha radiation (Q=20)
One sievert = 1 gray of beta radiation (Q=1)
One sievert = 1 gray of gamma radiation (Q=1)
One sievert = 0.1 gray of neutron radiation (Q=10)

Alpha particles (helium nuclei)
Beta particles (electrons)
Gamma rays (x-rays)
Neutrons

Pancake detector is best
Pancake detector, GM tube
Geiger-Mueller tube
Scintillator detector required

Alpha emitters are dangerous if inhaled or eaten.
Beta emitters are dangerous if inhaled or eaten.
Gamma is the most dangerous source outside the body.
Neutron emission can make nearby objects radioactive.

Helium nuclei consist of 2 protons and 2 neutrons.

Neutrons have no charge, and are not affected by magnetic fields. They sail right through everything, until they collide with a heavy nucleus, producing daughter isotopes, which are ionizing.




Recommended annual human limit = 50mSv = 5,000 mREM
Do not exceed 200 mREM within any 2-week period.
Two weeks = 336 hours
200 mREM / 336 hours = 1.68 mREM/hour

For simplified gamma discussions -
1 RAD = 1 REM = 1 Gray = 1 Sievert

SI = International System of Dosage Units
1 Sievert = 1 Gray, when Q=1
RBE = Relative Biological Effectiveness

Old System (US) Dosage Units
RAD = Radiation Absorbed Dose
REM = Radiation Equivalent Man

Dose Equivalence
1 Sievert (Sv) = 100 Rems
One Gray = 100 Rads


Rate
r/hr = roentgens per hour
CDV-715 Measurement Rate
500 roentgens per hour full scale on x100 scale
50 roentgens per hour full scale on x10 scale
5 roentgens per hour full scale on x1 scale
500 milli-roentgens /hour full scale on x0.1 scale

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Rems/Hour

Sieverts/Hour

Danger Level after 1 Hour

1
2
3
4
5
6
7
8
9

10 µRems
100 µRems
1 mRems
10 mRems
100 mRems
1 Rem
10 Rems
100 Rems
500 Rems

0.1 µSv
1 µSv
10 µSv
100 µSv
1 mSv
10 mSv
100 mSv
1 Sv
5 Sv

Background radiation
Low level radiation
Daily human limit RATE
Do not stay here
Substantial exposure
CDV-715 lowest scale
Extreme danger
50% chance of death
CDV-715 highest scale

For years, we were told that low-level radiation won't hurt us. Most scientists now concede that ANY amount of radiation CAN be harmful (there is no minimum threshold, above which damage "occurs"). Ionizing radiation damage is cumulative. Reduce your total exposure, to optimize your health.

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Geiger
Counter
Model #

CPM
Full Scale

mR/Hour
Full Scale

Sensitivity
CPM/mR/hr

1
2
3
4
5
6
7
8
9
10
11

Ludlum 2401P
CDV-700 #6b
Bicron 50
Ludlum
Ludlum Model 3
Ludlum
Ludlum
Bicron 2000
Ludlum
Eberline 120
Ludlum 44-2

500
300
600
6,600
5,000
4,200
3,500
2,400
3,500
6,000
800

0.15 mR
0.5 mR
0.5 mR
2 mR
2 mR
2 mR
2 mR
2 mR
5 mR
5 mR
5 mR

3,300
600
1,200
3.300
2,500
2,100
1,750
1,200
700
1,200
40

Meter faces will vary by a factor of 80 to 1, in terms of the correspondence between Counts per Minute and milliRems/hour. Some example meter readouts are shown above. Probe sensitivity is the big factor here. A very sensitive probe will require fewer counts to determine mR/hour rates. Put another way, at a given mR/hour rate, more counts will be observed using a very sensitive probe.

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0.01
0.02
0.05
0.1
0.2
0.5
1
2
5
10
20
50
100
200
500
1 REM

6
12
30
60
120
300
600
1,200
3,000
6,000
12,000
30,000
60,000
120,000
300,000
600.000

12
24
60
120
240
600
1,200
2,400
6,000
12,000
24,000
60,000
120,000
240,000
600,000
1,200,000

25
50
125
250
500
1,250
2,500
5,000
12,500
25,000
50,000
125,000
250,000
5,000,000
1,250,000
2,500,000

33
66
132
330
660
1,650
3,300
6,600
16,500
33,000
66,000
165,000
330,000
660,000
1,650,000
3,300,000

Trying to provide a direct "CPM to mR Scale" from the above chart above this one.
0.01 mR/hr equals background radiation levels.

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  Natural:

-

-

Cosmic
Terrestrial
Radon
Internal (K-40, C-14, etc.)

Sun, quasars
Rocks, water
Most of total -> dirt
Food, breathing

-

295 (82%)

  Manmade:

-

-

Diagnostic x-ray
Nuclear Medicine
Consumer Products
Others (fallout, air travel, etc.)

10 = 390 mR
Barium colon?
Salt, smoke detectors
Occupational

-

66 (18%)

Average annual total

360 mRem/year

360 (100%)

Source: University of Rochester, annotated

Suggested Annual Occupational Limit - Individual

5,000 mRem (5R)

360 above = 7%

Suggested Annual Occupational Limit - Pregnant Woman

500 mRem (0.5R)

360 above = 72%

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DISCLAIMER
I know very little about nuclear radiation.
I am building this page on the fly.
Although the author has tried to be as accurate as possible, errors are possible.

I could not find a Radiation Detection summary like the above. So, I made this ionizing radiation detection summary chart, to help myself understand the technology. I hope that it helps you.

I am an electronics engineer by trade, who knows little about nuclear radiation. Please verify all data above. Nuke dudes, please correct me - I'm trainable! This stuff has always intrigued me.

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