Classes of Nuclear Substances
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Nuclear substances are divided into 3 classes (A, B and C) based on their radiological characteristics.
The following table lists the classes of the most common nuclear substances and their associated contamination limits.
Notes:
- To find out the class of any nuclear substance that is not in the table, please communicate with your CNSC licence contact.
- All alpha emitters with their progeny (if applicable) not included in the following table are considered Class A nuclear substances.
| Nuclear substance | Nuclear substance abbreviation | Class | Contamination limit in controlled areas in Bq/cm2 | Contamination limit in public areas in Bq/cm2 |
|---|---|---|---|---|
| Silver-110m | Ag-110m | A | 3 | 0.3 |
| Actinium-225 | Ac-225 | A | 3 | 0.3 |
| Americium-241 | Am-241 | A | 3 | 0.3 |
| Astatine-211 | At-211 | A | 3 | 0.3 |
| Bismuth-207 | Bi-207 | A | 3 | 0.3 |
| Bismuth-210 | Bi-210 | A | 3 | 0.3 |
| Bismuth-212 | Bi-212 | A | 3 | 0.3 |
| Bismuth-213 | Bi-213 | A | 3 | 0.3 |
| Cobalt-55 | Co-55 | C | 300 | 30 |
| Cobalt-56 | Co-56 | A | 3 | 0.3 |
| Cobalt-60 | Co-60 | A | 3 | 0.3 |
| Cesium-131 | Cs-131 | C | 300 | 30 |
| Cesium-134 | Cs-134 | A | 3 | 0.3 |
| Cesium-136 | Cs-136 | B | 30 | 3 |
| Cesium-137 | Cs-137 | A | 3 | 0.3 |
| Iodine-124 | I-124 | A | 3 | 0.3 |
| Lutetium-177m | Lu-177m | A | 3 | 0.3 |
| Manganese-52 | Mn-52 | A | 3 | 0.3 |
| Sodium-22 | Na-22 | A | 3 | 0.3 |
| Lead-203 | Pb-203 | C | 300 | 30 |
| Lead-210 | Pb-210 | A | 3 | 0.3 |
| Lead-212 | Pb-212 | A | 3 | 0.3 |
| Antimony-117 | Sb-117 | C | 300 | 30 |
| Antimony-118m | Sb-118m | C | 300 | 30 |
| Antimony-119 | Sb-119 | C | 300 | 30 |
| Antimony-120m | Sb-120m | B | 30 | 3 |
| Antimony-124 | Sb-124 | A | 3 | 0.3 |
| Antimony-125 | Sb-125 | B | 30 | 3 |
| Scandium-46 | Sc-46 | A | 3 | 0.3 |
| Vanadium-48 | V-48 | A | 3 | 0.3 |
| Zinc-65 | Zn-65 | A | 3 | 0.3 |
| Arsenic-73 | As-73 | C | 300 | 30 |
| Arsenic-74 | As-74 | B | 30 | 3 |
| Gold-195 | Au-195 | C | 300 | 30 |
| Gold-198 | Au-198 | B | 30 | 3 |
| Gold-199 | Au-199 | B | 30 | 3 |
| Barium-131 | Ba-131 | B | 30 | 3 |
| Barium-133 | Ba-133 | B | 30 | 3 |
| Barium-135m | Ba-135m | C | 300 | 30 |
| Barium-139 | Ba-139 | C | 300 | 30 |
| Bromine-82 | Br-82 | C | 300 | 30 |
| Calcium-47 | Ca-47 | B | 30 | 3 |
| Cerium-139 | Ce-139 | B | 30 | 3 |
| Cerium-143 | Ce-143 | C | 300 | 30 |
| Cobalt-58 | Co-58 | B | 30 | 3 |
| Copper-67 | Cu-67 | B | 30 | 3 |
| Dysprosium-165 | Dy-165 | C | 300 | 30 |
| Dysprosium-166 | Dy-166 | B | 30 | 3 |
| Iron-59 | Fe-59 | B | 30 | 3 |
| Gallium-72 | Ga-72 | C | 300 | 30 |
| Gadolinium-153 | Gd-153 | B | 30 | 3 |
| Mercury-194 | Hg-194 | A | 3 | 0.3 |
| Mercury-197 | Hg-197 | C | 300 | 30 |
| Mercury-197m | Hg-197m | C | 300 | 30 |
| Mercury-203 | Hg-203 | B | 30 | 3 |
| Iridium-192 | Ir-192 | B | 30 | 3 |
| Iodine-131 | I-131 | B | 30 | 3 |
| Lanthanum-132 | La-132 | C | 300 | 30 |
| Lanthanum-133 | La-133 | C | 300 | 30 |
| Lanthanum-135 | La-135 | C | 300 | 30 |
| Lanthanum-140 | La-140 | B | 30 | 3 |
| Manganese-54 | Mn-54 | A | 3 | 0.3 |
| Molybdenum-99 | Mo-99 | B | 30 | 3 |
| Niobium-94 | Nb-94 | A | 3 | 0.3 |
| Niobium-95 | Nb-95 | B | 30 | 3 |
| Niobium-96 | Nb-96 | C | 300 | 30 |
| Protactinium-233 | Pa-233 | B | 30 | 3 |
| Platinum-195m | Pt-195m | B | 30 | 3 |
| Polonium-210 | Po-210 | A | 3 | 0.3 |
| Polonium-212 | Po-212 | C | 300 | 30 |
| Radium-223 | Ra-223 | A | 3 | 0.3 |
| Radium-224 | Ra-224 | A | 3 | 0.3 |
| Radium-226 | Ra-226 | A | 3 | 0.3 |
| Rubidium-82 | Rb-82 | C | 300 | 30 |
| Rubidium-84 | Rb-84 | B | 30 | 3 |
| Rubidium-86 | Rb-86 | B | 30 | 3 |
| Rhodium-103m | Rh-103m | C | 300 | 30 |
| Rhenium-186 | Re-186 | B | 30 | 3 |
| Rhenium-188 | Re-188 | C | 300 | 30 |
| Ruthenium-103 | Ru-103 | B | 30 | 3 |
| Ruthenium-106 | Ru-106 | B | 30 | 3 |
| Antimony-122 | Sb-122 | B | 30 | 3 |
| Selenium-75 | Se-75 | B | 30 | 3 |
| Samarium-153 | Sm-153 | C | 300 | 30 |
| Strontium-82 | Sr-82 | A | 3 | 0.3 |
| Strontium-85 | Sr-85 | B | 30 | 3 |
| Strontium-90 | Sr-90 | B | 30 | 3 |
| Xenon-127 | Xe-127 | B | 30 | 3 |
| Yttrium-86 | Y-86 | C | 300 | 30 |
| Yttrium-88 | Y-88 | A | 3 | 0.3 |
| Yttrium-90 | Y-90 | B | 30 | 3 |
| Ytterbium-169 | Yb-169 | B | 30 | 3 |
| Ytterbium-175 | Yb-175 | B | 30 | 3 |
| Zirconium-95 | Zr-95 | A | 3 | 0.3 |
| Tungsten-188 | W-188 | B | 30 | 3 |
| Zirconium-89 | Zr-89 | C | 300 | 30 |
| Argon-41 | Ar-41 | C | 300 | 30 |
| Gold-195m | Au-195m | C | 300 | 30 |
| Carbon-11 | C-11 | C | 300 | 30 |
| Carbon-14 | C-14 | C | 300 | 30 |
| Calcium-45 | Ca-45 | C | 300 | 30 |
| Cadmium-109 | Cd-109 | C | 300 | 30 |
| Cerium-141 | Ce-141 | C | 300 | 30 |
| Cerium-144 | Ce-144 | C | 300 | 30 |
| Chlorine-36 | Cl-36 | C | 300 | 30 |
| Cobalt-57 | Co-57 | C | 300 | 30 |
| Chromium-51 | Cr-51 | C | 300 | 30 |
| Copper-60 | Cu-60 | C | 300 | 30 |
| Copper-61 | Cu-61 | C | 300 | 30 |
| Copper-62 | Cu-62 | C | 300 | 30 |
| Copper-64 | Cu-64 | C | 300 | 30 |
| Erbium-169 | Er-169 | C | 300 | 30 |
| Europium-152 | Eu-152 | A | 3 | 0.3 |
| Fluorine-18 | F-18 | C | 300 | 30 |
| Iron-55 | Fe-55 | C | 300 | 30 |
| Gallium-67 | Ga-67 | C | 300 | 30 |
| Gallium-68 | Ga-68 | C | 300 | 30 |
| Germanium-68 | Ge-68 | A | 3 | 0.3 |
| Hydrogen-3 | H-3 | C | 300 | 30 |
| Holmium-166 | Ho-166 | C | 300 | 30 |
| Iodine-123 | I-123 | C | 300 | 30 |
| Iodine-125 | I-125 | C | 300 | 30 |
| Iodine-126 | I-126 | C | 300 | 30 |
| Iodine-129 | I-129 | C | 300 | 30 |
| Indium-111 | In-111 | C | 300 | 30 |
| Indium-113m | In-113m | C | 300 | 30 |
| Indium-114 | In-114 | C | 300 | 30 |
| Indium-114m | In-114m | B | 30 | 3 |
| Potassium-42 | K-42 | C | 300 | 30 |
| Krypton-79 | Kr-79 | C | 300 | 30 |
| Krypton-81 | Kr-81 | C | 300 | 30 |
| Krypton-81m | Kr-81m | C | 300 | 30 |
| Krypton-85 | Kr-85 | C | 300 | 30 |
| Lutetium-177 | Lu-177 | C | 300 | 30 |
| Manganese-52m | Mn-52m | C | 300 | 30 |
| Manganese-56 | Mn-56 | C | 300 | 30 |
| Nitrogen-13 | N-13 | C | 300 | 30 |
| Sodium-24 | Na-24 | C | 300 | 30 |
| Niobium-98 | Nb-98 | C | 300 | 30 |
| Nickel-63 | Ni-63 | C | 300 | 30 |
| Oxygen-15 | O-15 | C | 300 | 30 |
| Phosphorus-32 | P-32 | C | 300 | 30 |
| Phosphorus-33 | P-33 | C | 300 | 30 |
| Palladium-103 | Pd-103 | C | 300 | 30 |
| Promethium-147 | Pm-147 | C | 300 | 30 |
| Praseodymium-144 | Pr-144 | C | 300 | 30 |
| Plutonium-238 | Pu-238 | A | 3 | 0.3 |
| Plutonium-239 | Pu-239 | A | 3 | 0.3 |
| Plutonium-240 | Pu-240 | A | 3 | 0.3 |
| Plutonium-241 | Pu-241 | C | 300 | 30 |
| Rhodium-106 | Rh-106 | C | 300 | 30 |
| Sulfur-35 | S-35 | C | 300 | 30 |
| Scandium-44 | Sc-44 | C | 300 | 30 |
| Scandium-44m | Sc-44m | B | 30 | 3 |
| Tin-113 | Sn-113 | B | 30 | 3 |
| Tin-117m | Sn-117m | B | 30 | 3 |
| Tin-123 | Sn-123 | C | 300 | 30 |
| Strontium-89 | Sr-89 | C | 300 | 30 |
| Tantalum-182 | Ta-182 | A | 3 | 0.3 |
| Terbium-149 | Tb-149 | B | 30 | 3 |
| Terbium-152 | Tb-152 | C | 300 | 30 |
| Terbium-155 | Tb-155 | B | 30 | 3 |
| Terbium-161 | Tb-161 | C | 300 | 30 |
| Technetium-94 | Tc-94 | C | 300 | 30 |
| Technetium-94m | Tc-94m | C | 300 | 30 |
| Technetium-95 | Tc-95 | C | 300 | 30 |
| Technetium-96 | Tc-96 | B | 30 | 3 |
| Technetium-99 | Tc-99 | C | 300 | 30 |
| Technetium-99m | Tc-99m | C | 300 | 30 |
| Tellurium-123m | Te-123m | C | 300 | 30 |
| Tellurium-127 | Te-127 | C | 300 | 30 |
| Titanium-45 | Ti-45 | C | 300 | 30 |
| Thallium-201 | Tl-201 | C | 300 | 30 |
| Thallium-204 | Tl-204 | C | 300 | 30 |
| Thallium-208 | Tl-208 | C | 300 | 30 |
| Thorium-227 | Th-227 | A | 3 | 0.3 |
| Uranium-234 | U-234 | A | 3 | 0.3 |
| Uranium-235 | U-235 | A | 3 | 0.3 |
| Uranium-238 | U-238 | A | 3 | 0.3 |
| Vanadium-49 | V-49 | C | 300 | 30 |
| Tungsten-181 | W-181 | C | 300 | 30 |
| Tungsten-185 | W-185 | C | 300 | 30 |
| Xenon-133 | Xe-133 | C | 300 | 30 |
| Zinc-62 | Zn-62 | C | 300 | 30 |
| Zinc-63 | Zn-63 | C | 300 | 30 |
Revision date: January 2026
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