Excerpt from 'Deception, Cover-up and Murder in the Nuclear Age'- "Manhattan Project and Army staff, although they were in even greater danger from Trinity's intense radiation at close range, apparently largely escaped harmful exposures. How? They were instructed by their superiors to... follow 'protective measures' such as closing windows, staying indoors, and even breathing through a slice of bread!" more
PREFIXES, CONVERSIONS & EQUIVALENTS
| Multiples/submultiples | Prefix | What we usually call it | Symbol |
| 1015 | peta | million billion times | P |
| 1012 | tera | trillion times | T |
| 109 | giga | billion times | G |
| 106 | mega | million times | M |
| 103 | kilo | thousand times | k |
| 10-2 | centi | hundredth | c |
| 10-3 | milli | thousandth | m |
| 10-6 | micro | millionth | µ |
| 10-9 | nano | billionth | n |
| 10-12 | pico | trillionth | p (or µµ) |
| 10-15 | femto | f | |
| 10-18 | atto | a |
| Curies Symbols | ...is short for... | What we usually call it |
| PCi | petaCurie | million billion Curies |
| TCi | teraCurie | trillion Curies |
| GCi | gigaCurie | billion Curies |
| MCi | megaCurie | million Curies |
| kCi | kiloCurie | thousand Curies |
| Ci | Curie | a curie represents the radioactivity of one gram of pure
Radium-226
a curie is an amount of radioactive material that is decaying at a rate of 3.700 x 1010 disintegrations per second |
| mCi | milliCurie | thousandth of a Curie |
| µCi | microCurie | millionth of a Curie |
| nCi | nanoCurie | billionth of a Curie |
| pCi | picoCurie | trillionth of a Curie = 2.22 disintegrations per minute (dpm) = 0.037 disintegrations per second (dps) |
| fCi | femtoCurie | million billionth of a Curie |
1 picocurie (pCi) = 0.037 Bq
| Becquerels symbols | ...is short for... | What we usually call it |
| PBq | petaBecquerel | mrillion billion Becquerels |
| TBq | teraBecquerel | trillion Becquerels |
| GBq | gigaBecquerel | billion Becquerels |
| MBq | megaBecquerel | million Becquerels |
| kBq | kiloBecquerel | thousand Becquerels |
| Bq | Becquerel |
1 Becquerel (bq) = 1 disintegration per second
= 27.03 pCi |
| mBq | milliBecquerel | thousandth of a Becquerel |
| µBq | microBecquerel | millionth of a Becquerel |
| nBq | nanoBecquerel | billionth of a Becquerel |
| pBq | picoBecquerel | trillionth of a Becquerel |
| fBq | femtoBecquerel | million-billionth of a Becquerel |
1 Becquerel (bq) = 1 disintegration per second = 27.03 pCi
| Rem symbols | ...is short for... | What we usually call it | Converted to Sieverts (Sv) |
| TRem | teraRem | trillion Rems | 0.01 TSv |
| GRem | gigaRem | billion Rems | 0.01 GSv |
| MRem | MegaRem | million Rems | 0.01 MSv |
| kRem | kiloRem | thousand Rems | 0.01 kSv |
| Rem | Rem | 0.01 Sv | |
| mRem | milliRem | thousandth of a Rem | 0.01 mSv |
| µRem | microRem | millionth of a Rem | 0.01 µSv |
| nRem | nanoRem | billionth of a Rem | 0.01 nSv |
1 Rem = 0.01 Sv
| Sieverts Symbols | ...is short for... | What we usually call it | Converted to Rems |
| TSv | teraSievert | trillion Sieverts | 100 TRems |
| GSv | gigaSievert | billion Sieverts | 100 GRems |
| MSv | MegaSievert | million Sieverts | 100 MRems |
| kSv | kiloSievert | thousand Sieverts | 100 kRems |
| Sv | Sievert | 100 Rems | |
| mSv | milliSievert | thousandth of a Sievert | 100 mRems |
| µSv | microSievert | millionth of a Sievert | 100 µRems |
| nSv | nanoSievert | billionth of a Sievert | 100 nRems |
multiply by 100 to convert Sv to Rem
| Symbols often used regarding radiation energies | ...is short for... | What we usually call it |
| TeV | teraelectron volts | trillion electron volts |
| GeV | gigaelectron volts | billion electron volts |
| MeV | megaelectron volts | million electron volts |
| keV | kiloelectron volts | thousand electron volts |
| meV | millielectron volts | thousandth of an electron volt |
| µeV | microelectron volts | millionth of an electron volt |
| neV | nanoelectron volts | billionth of an electron volt |
| peV | picoelectron volts | trillionth of an electron volt |
| feV | femtoelectron volts | million billionth of an electron volt |
Multiple choice question
Which of the following is not an effective way of reducing the external radiation threat to a specific person from a contamination source in the environment?
a) Time - leave area of contamination and return when the radiation source has decayed to safer levels
b) Shielding - cover the radiation source with soil, concrete, cask shielding; and/or cover person - with lead apron, etc...
c) Raise the threshold of harm, so that radiation exposure will be acceptable and nothing else should be done
d) Distance - evacuate person from the contamination or move contamination someone else - via waste transport, incineration, DU weapons use on other continents, etc...
answer (c)
|
Length and Area equivalents |
|
| 1 cm | 0.394 inch |
| 1/2 inch | 12 millimeters |
| 1 inch | 2.5 cm |
| 2.575 sq. km. = 2,575,000 sq. meters | 1 sq. mi |
| 1 sq. km. | 0.388 sq. mi. |
| 1 sq. meter | 3.88E-7 (0.000000388) sq. mi. |
|
Volume and other equivalents |
||
| 1 cup | 8 ounces | |
| 1 pint | 2 cups | |
| 1 quart | 4 cups, 32 ounces | |
| 1 gallon | 4 quarts, 16 cups, 128 ounces | |
| 1 teaspoon | 1/8 ounce (~ 5 milliliters) | |
| 1 tablespoon (3 teaspoons) | 3/8 ounce (~ 15 milliters) | Cooks: If you accidentally put in 1 1/2 teaspoons instead of 1 1/2 tablespoons of vanilla, vinegar, etc.., just add 3 teaspoons to make up the difference. It works! |
| 1 fluid ounce (2 tablespoons) | 30 milliliters | |
| 1 ounce (by weight) | 28 grams | |
| 1 pound | 454 grams | |
| 2.2 pounds | 1 kilogram | |
1 Roentgen (R) = amount of radiation that creates a certain number of ions - created when ionizing radiation hits atoms or molecules - in a cubic centimeter of air
Gray (thanks to J.B. for helping us fix some errors about Grays conversion)
1 Gray (Gy) = 100 Rad; Gray represents 'absorbed dose' (or what Rad is to Rem)
1 Rad = 0.01 Gray (10 milliGray)
1 milliGray (mGy) = 0.1 Rad
Wikipedia notes that the fission yield of 90Sr is 4.5% and 137Cs is 6.3%.
Area of Earth = 200 million square miles
1 nCi/m2=2.59 mCi/mi22 (U.S. Public Health Service conversion)
1 mCi/mi2= 0.386 nCi/m22 (mCi/km2) (ibid)
1 nCi/m22 = 1 mCi/km22
|
|
|
Specific Activity |
|
nuclide |
half-life |
(Ci/gm) (meaning this number is the number of curies in 1 gram of
the nuclide) |
|
239 Pu |
24,400 yrs |
0.06 |
|
137 Cs |
30.28
yrs |
86.1 |
|
90 Sr |
28.1
yrs |
141.0 |
|
131 I |
8
days |
1.24 x 10 5 |
(Additional decimal: 1 gram of Pu239 is 0.067 ci)
1 Curie of 90Sr weighs 7 milligrams (how? If 1 gram of Sr90 is 141.0 curies, then 1 curie is 1/141 or 0.007 grams)
|
nuclide |
half-life
(yrs) |
Specific Activity
(Ci/gm) |
|
233
U |
1.62 x 10 5 |
9.45 x 10 -3 |
|
235
U |
7.1 x 10 8 |
2.1 x 10 -6 |
|
238
U |
4.51 x 10 9 |
3.3 x 10 -7 |
|
239
Pu |
24,400 |
0.0061 |
|
240
Pu |
6,580 |
0.226 |
|
238
Pu |
86 |
17.44 |
|
241
Pu |
13.2 |
112.2 |
RADIOACTIVE-'ACTIVITY'
To determine how radioactive something is:
|
A* = |
0.693 mNA |
|
|
T1/2AFt |
A* = activity of sample (in disintegrations per time)
m = mass of sample
A = atomic weight of radionuclide (easy: it's the number of the nuclide, like 89 for strontium-89)
T1/2 = half-life of radionuclide (in any unit of time)
Ft = conversion from one unit of time to the desired unit of time
NA = constant called Avogadro's number, or 6.022 x 10 23 atoms/mole
Does this formula really work?
Let's try it on radium. We know that 1 curie represents the radioactivity of one gram of pure Radium-226 and we also know that 1 curie pumps out 3.700 x 1010 disintegrations per second.
So, to prove that 1 gram of radium pumps out 37 trillion disintegrations per second, let's assign the variables for radium. Lets assign a mass of 1 (gram). We know radium's half-life is about 1,603 years and its atomic weight is 226.0254 (radium 226). For Ft we want to convert from years to seconds, or 31,536,000 seconds per year.
|
A* = |
(0.693) (1
gram) (6.022 x 10 23 atoms/mole) |
= 3.65E10, or 3.65 x 1010 disintegrations per second |
|
|
(1603 years)(226.0254 grams/mole) (525600 minutes/year)(60 seconds/minute) |
Why did we come up short? Any ideas??
Example. If 1 microgram of strontium-89 (which has a 50.6 day half-life) was deposited today in 1 meter by 1 meter area of a rice patty near Tokyo, what is its present activity?
|
A* = |
(0.693) (0.00001
grams) (6.022 x 10 23 atoms/mole) |
= 6.43 x 1011 disintegrations per minute |
|
|
(50.6 days)(89 grams/mole)
(1440 minutes/day) |
Example. If plutonium-238 depositions from Fukushima caused Namie soils to be 4 becquerels per square meter, what is the activity level?
First 4 becquerels (of pu238) is the same as 108 picocuries (of pu238). Second, one gram of pu238 is 17.44 curies, or (17.44 x 1 trillion) picocuries. So, the 4 becquerels per square meter represents 108/(17.44 x 1 trillion) = 6.3 x 10-12 grams.
|
A* = |
(0.693) (6.3
x 10-12
grams) (6.022 x 10 23 atoms/mole) |
= 238.8 disintegrations per minute |
|
|
(88 years)(238 grams/mole)
(525600 minutes/year) |
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