Determining Regulatory Contamination Limit

Step 1: Determine the Radionuclide Class 

The CNSC has grouped radionuclide into 3 classes. Use the table below to determine the radioisotope’s class.

Class RADIONUCLIDE
Class A
alpha emitters and their daughter isotopes
Ag-110m Bi-210 Co-56 Co-60 Cs-134
Cs-137 I-124 Lu-177m Mn-52 Na-22
Po-210 Pu-238 Pu-239 Pu-240 Sb-124
Sc-46 Sr-82 U-234 U-235 U-238
V-48 Zn-65      
Class B
long-lived and emit beta or gamma radiation
Au-198 Ba-133 Br-82 Ce-143 Co-58
Cu-67 Fe-59 Hg-194 Hg-203 I-131
Ir-192 La-140 Mo-99 Nb-95 Pa-233
Ra-223 Re-186 Re-188 Ru-103 Sb-122
Sm-153 Sr-90 Xe-127 Y-86 Y-90
Yb-169 Zr-89 Zr-95    
Class C
short-lived and emit beta or gamma radiation
C-11 C-14 Ca-45 Cd-109 Ce-141
Cl-36 Co-57 Cr-51 Cu-60 Cu-61
Cu-64 F-18 Fe-55 Ga-67 Ga-68
Ge-68 H-3 I-123 I-125 In-111
In-113m In-114 K-42 Kr-85 Lu-177
Mn-52m Mn-56 N-13 Na-24 Nb-98
Ni-63 O-15 P-32 P-33 Pd-103
Pr-144 Pu-241 Rh-106 S-35 Sc-44
Sn-113 Sr-89 Tc-94m Tc-99 Tc-99m
Te-127 Tl-201 V-49 W-181 W-188
Xe-133 Zn-63      

Step 2: Determine the regulatory limit

 Each of these has limits assigned in terms of unfixed contamination in either a radioactive use or storage area, or in an area where radioactive material is used.

Non - Fixed Contamination Class A Radionuclide Class B Radionuclide Class C Radionuclide
In all areas, rooms or enclousures where unsealed nuclear substances are used, or stored 3 Bq/cm2 30 Bq/cm2 300 Bq/cm2
In all other areas and packaging prior to disposal 0.3 Bq/cm2 3 Bq/cm2 30 Bq/cm2
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