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Science Summaries
Ionizing Radiation

Nuclear Radiation Detection
Summary

by Vaughn Aubuchon

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

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100

60

30

80

80

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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
6.
Victoreen CDV-715 1A Detector Summary - Ion chamber detector
7. Victoreen CD V-750 5BDosimeter Charger - Charges CD dosimeters
8. Uranium Ore Summary - common types of radioactive ore


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1. A Few Common Radioactive Isotopes

Related
Cancer

AN

Isotope
(Radio nuclide)

Energy
Mev

Radiation Emitted

Half-Life

Light Nuclides

Days

Less than
10,000 Years

Greater than
10,000 Years

lung
-
-
liver, kidney
bone
-
-
thyroid
thyroid
all types
-

1
6
19
27
38
40
43
53
53
55
83

Tritium **
Carbon-14
Potassium-40
Cobalt-60**
Strontium-90**
Zirconium-95**

Technetium-99**
Iodine-129
Iodine-131**
Cesium-137**
Bismuth-(many)

0.019
0.155
1.460
0.318
0.546
-
0.292
0.150
-
0.514
-

Beta only
Beta only
Beta
, gamma
Lo Beta, hi gamma
Pure beta
Beta
, gamma
Beta
, gamma
Beta
, gamma
Beta, gamma
Beta
, gamma
Beta, gamma






64 days


8 Days

(varies)

12 years
6,000 years

5 years
29 years




30 years
(varies)



1.3 Billion Y.



212,000 Y.
15.7 million Y.

Heavy Nuclides

Days

Less than
10,000 years

Greater than
10,000 Years

lung
bone
lung
-
all types
all types
all types
lung
lung
lung
all organs
all organs

84
86
88
90
92
92
92
94
94
94
95
95

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

Americium-241**
Americium-243**

5.30
4.78
5.49
4.68
4.77
4.39
4.20
-
5.15

5.49
-

Hi alpha, lo gamma
Alpha, gamma
Alpha
Alpha, gamma
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha
Alpha, gamma
Alpha, gamma

138 days

3.8 days






1,600 years





88 years

14 years
432 years
7,370 years




75,000 Y.
244,500 Y.
704 million Y.
4.5 Billion Y.

24,000 Y.

AN = Atomic Number
* = Isotopes used by nuclear reactors in fuel rods
** = A few of the isotopes created in nuclear reactors

For most people, radon is the biggest threat, due to its accumulation within buildings (see
Dose below).
This radon gas is generated by decaying isotopes in the soil under the structure.
Inhaled radon gas causes lung cancer.
Radon Gas in California

100

40

130-830

50

170

80

120

130


.
# of Half-lives Required
for Isotope to Be Reduced to 1%
of its Original Value
# of
Half-Lives
Per Cent of Isotope
(Radioactivity)
Remaining

Example Isotope
Americium-241

0
100 %

Right Now

1
50 %

432 years

2
25 %

864 years

3
12.5 %

1,296 years

4
6.25 %

1,728 years

5
3.125 %

2,160 years

6
1.5625 %

2,592 years

7
0.78125 %

3,024 years

It takes about 7 half-lives to reduce an isotope's radioactivity to less than 1% of the original radioactivity. The radioactive decay of one isotope produces other isotopes, some of which have half-lives longer than the original.

Although there are only about 118 elements, there are hundreds of different isotopes, each with their own characteristics, and daughter isotopes.

Over time, we will cover the planet with nasty isotopes that are extremely long-lived, forcing us to evolve into mutants, if we are to survive long-term.

What Radiation Does to the Human Body (very graphic)

80

150-400

140



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2. Types of Nuclear Radiation

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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200

340 - 768



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3. Nuclear Radiation Detection Rate -
Detector Sensitivity Scales
Scale

Rems/Hour

Sieverts/Hour

Danger Level after 1 Hour

Reported
Fukushima
Radiation
Levels

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
Strong exposure
Extreme danger
50% chance of death
CDV-715 highest scale



10µSv
400µSv

10 mSv
400 mSv

Human Radiation Damage - "Linear No Threshold"
For years, we were told that low-level radiation won't hurt us. Exposure Limits were set at what were believed to be "safe levels", AKA "acceptable levels".

In reality, there are no "safe levels". 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, and is proportional to exposure.
Reduce your total exposure, to protect your health.
A very small exposure is worse than no exposure.

Is it inevitable that these Fukushima radioisotopes will rise into the atmosphere, and be carried by the jet stream to the west coast of Canada and the United States? Yes.
Will this radiation result in thousands of new cancers in California? No.
Will the overall cancer rate in California rise slightly due to increased background radiation? Yes.
Can anyone say by how much? No.

The GE Mark 1 Reactor Design
Who was the person who decided to store the used fuel rods, now containing plutonium, in a cast cement tank, ON TOP of the reactor?
These rods should have been stored ANY PLACE ELSE.

Who APPROVED this design?
Pure insanity.

INFORMATION FLOW - We Still Don't Know
Things are worse than we are allowed know -
Tokyo Electric Power ---> censored info ---> Japanese Government ---> more censorship ---> available information to outside world
Wouldn't we do the same thing? Reduce panic. Prolong ignorance.

Sanjay Gupta Is Ill-informed
Most people are getting their Japan radiation information from CNN. EVERY time that Sanjay has opened his mouth since March 11, he has demonstrated his utter lack of knowledge about radiation. I just wish I had written everything down. On ONE DAY, in ONE interview, he made FIVE absurd pronouncements.

At one point, he tried to explain the difference between a dosimeter and a Geiger counter - he failed miserably.
On Tuesday March 22, he said something to the effect - "These short half-life isotopes will decay quickly, but NOT if they are buried underground, where it will take decades". WHAT? They will decay underground JUST AS QUICKLY as above ground. The half-life of an isotope DOES NOT VARY, no matter where you put it. Hence, the atomic clock - the most accurate on earth, based upon isotope decay. There are 6th graders who can correct this know-it-all dummkopf.

Somebody needs to gag this guy, because he is making all his listeners dumber than dirt. And they wanted to make him Surgeon General? AHH-HA-HA-HA. I don't think so..
Practicing neurosurgeon? That is just plain scary. I guess he cuts into people's brains, in between spewing disinformation to the masses.

Sometimes, PHD simply means Piled Higher and Deeper. It doesn't mean he is smart - it simply means he put up with a ton of academic hoop-jumping.

Saturday March 26 - More disinformation from CNN -
"ALARA = As Low As Is Reasonably Acceptable" - WRONG!
ALARA = As Low As Is Reasonably ACHIEVABLE - BIG difference
NO RADIATION is reasonably acceptable - it is all about what can be ACHIEVED!
Therefore, what is acceptable, is determined by what is achievable. If lower rates were achievable, then THAT would be what is acceptable.
CNN is truly staffed by scientific dolts.

Below -
Fukushima Reactor Status ... from the New York Times, March 26, 2011

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100

100

240-590

100


Fukushima Fuel Rod Assemblies

Each BWR "Fuel Assembly" contains 208 kg of Uranium Oxide.
208 times 2.2046 equals 458 pounds.
458 times 7,354 = 3,368,132 pounds of Uranium.
7,354 Assemblies times 63 rods = 463,302 fuel rods (~7.3 lbs./rod).

There is also a 7th "common pool" which contains 6,291 Fuel Assemblies.
This is the only storage pool not located above a reactor.



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4. CPM vs. mR/hr - Probe Sensitivity
Meter

Geiger
Counter
Probe Model #

CPM
Full Scale

mR/Hour
Full Scale

Sensitivity
CPM/mR/hr

1
2
3
4
5
6

Ludlum 44-2
CDV-700 #6b
Bicron 50 EWGM

Bicron 2000
Ludlum 44-6, 38
Eberline 120 Pan

200
300
600
2,400
2,400
6,000

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

40
600
1,200

1,200
1,200
1,200

7
8
9

Ludlum 44-7 End
Ludlum Model 3
Ludlum 44-9 Pan

4,200
5,000
6,600

2 mR
2 mR
2 mR

2,100
2,500
3,300

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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4.5. CPM vs. mR/hr for a given CPM/mR/hr
True
mR/hr
From Least Sensitive -----------> over 5 Times More Sensitive
(CDV-700)
CPM @
mR/hr = 600
(Bicron 50)
(Bicron 2000)
CPM @
mR/hr = 1,200
(Ludlum)
CPM @
mR/hr = 2,500

 

(Ludlum)
CPM @
mR/hr = 3,300

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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5. US Citizen Annual Radiation DOSE
Radiation Source 
Average Annual Whole Body Dose  (millirem/year)

  Natural:

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

27 mR
28 mR
200 mR
40 mR

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.)

39 mR
14 mR
11 mR
  2 mR

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%

 



DISCLAIMER
I know very little about nuclear radiation.
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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Vaughn Aubuchon
Vaughn's Summaries
©2006, 2011 Vaughn Aubuchon
www.vaughns-1-pagers.com
All Rights Reserved
This Vaughns Nuclear Radiation Detection Information summary
was last updated on 2014-08-08.