Isotope Parameters
Significant Radiation Parameters of Commonly Used Isotopes
Nuclide
Principal Radiation
Half-Life
Ingestion Limit, uCi
Shielding
Notes
H-3
Beta
18.6 keV
12.3y
80000
None
--------
C-14
Beta
156 keV
5730y
2000
None
--------
P-32
Beta
1700 keV
14.3 d
600
Acrylic. Plexiglas (1cm)
The Beta s will produce x-rays by Bremsstrahlung if they interact with and high atomic
number material. Lead or other metals should not be used for shielding. Contact RSO
for guidance.
S-35
Beta
167 keV
87 d
1000
None
--------
Ca-45
Beta
257 keV
163 d
2000
See P-32
--------
Cr-51
Gamma
320 keV
28 d
40000
HVL=1.7mm
--------
Co-57
Gamma
122 keV
271 d
4000
HVL=.2mm
--------
I-125
Gamma
27 keV
60 d
40
HVL=.02mm
Volatilization is the most significant hazard. Work with a volatile iodine compound
whose activity exceeds 1 millicuries must be done in a fume hood unless a bioassay
program is established for the user.
I-131
Beta
606 keV
8 d
30
HVL=2.3mm
See I-125
