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Radiation Safety Training Module
Refresher Training
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Radionuclide Data

Definitions:

Annual Limit on Intake (ALI) - The quantity of a radionuclide which, if taken into the body, produces an effective dose equivalent of 5 rem.  Because of differences in physiological transport mechanisms, the ALIs vary depending on the route of intake.  For purposes of contamination control and bioassay procedures, the most limiting ALI as appropriate for either ingestion or inhalation is used.

Reference Quantity (RQ) - A quantity of a radionuclide (expressed in microcuries) related to its relative hazard potential and used to prescribe requirements for handling, monitoring, labeling and disposal.  Reference quantities are obtained from 10CFR20, Appendix C.

Removable Contamination Limits (RCL) - A basic limit for removable surface contamination, specified in "Contamination Limits and Action Levels" (RPR 10B, based on NRC Reg Guide 8.23).

Dose Equivalent Rates (mrem/hour) as given:
Penetrating - the dose rate from photons at 1 meter from a point source of 1 millicurie, assumed to be proportional to the inverse of the square of the distance between the point source and the receptor.

Skin dose - dose rate to the basal epidermal cells from contamination on the skin, expressed in microcuries per unit area of skin (microCi/cm2) over an area of at least 1 cm2.

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Low-energy beta or electron emitters with negligible external exposure potential. 
Nuclide
Half Life
Reference
Quantity (microCi)
Ingestion ALI (mCi)
H-3
12 years
1,000
80
C-14
5,730 years
100
2
S-35
87 days
100
6
Cl-36
3x105 years
10
2





High-energy beta emitters with negligible gamma emission but capable of significant bremsstrahlung* production if not properly shielded.  Emphasis is on control of doses to extremities and prevention of intake.  
Nuclide
Half Life
Reference
Quantity (microCi)
Ingestion ALI (mCi)
P-32
14.3 days
10
0.6
Sr-Y-90
29.12 years
0.1
0.03
* Bremsstrahlung radiation is electromagnetic radiation emmitted by swiftly moving charged particles as they de-accelerate.



Radioiodines are treated as a separate category for exposure evaluation.  Emphasis is on prevention of intake by ingestion or inhalation.
 
Nuclide
Half Life
Reference
Quantity (microCi)
Ingestion ALI (mCi)
I-125
60 days
1
0.04
I-129
1.57x107 years
1
0.005
I-131
8 days
1
0.03




Noble gases present minimal exposure potential or waste disposal problems.
 
Nuclide
Half Life
Reference
Quantity (microCi)
Ingestion ALI (mCi)
Kr-85
10.7 years 
1,000
NA
Xe-133
5.2 days 
1,000
NA




Naturally occurring radionuclides are primarily alpha emitters. Emphasis is on prevention of intake by ingestion or inhalation.
 
Nuclide
Half Life
Reference
Quantity (microCi)
Ingestion ALI (mCi)
Th-232
1.4x1010 years 
100
0.0007
U-238
 4.5x109 years
100
0.02




Radionuclides which emit gamma rays of substantial energy and with ALI greater than or equal to 1 millicurie; emphasis is on external exposure control and monitoring.
 
Nuclide
Half Life
Reference
Quantity (microCi)
Ingestion ALI (mCi)
Na-24
15 hours 
100
4
Mn-54
312 days
100
2
Mo-99
2.8 days
100
1
Tc-99m
6 hours
1,000
80
Au-198
 2.7 days
100
1




ALL OTHER RADIONUCLIDES not included in one of the above groups are assumed to have potentials for both external and internal exposures and must be evaluated individually.
 
Nuclide
Half Life
Reference
Quantity (microCi)
Ingestion ALI (mCi)
Na-22
2.6 years
10
0.4
Co-60
5.27 years
1
0.2
Zn-65
244 days
10
0.4
Ir-192
74 days
1
0.9
Hg-203
47 days
100
0.5





 


Key Words:  “radioiodines”, gases, RQ, ALI, RCL.
 
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