Figure: 30 TAC §336.351(b)

Nationally Tracked Sources Threshold
Radioactive Material Category 1 (TBq) Category 1 (Ci) Category 2 (TBq) Category 2 (Ci)
Actinium-227 20 540 0.2 5.4
Americium-241 60 1,600 0.6 16.0
Americium-241/Be 60 1,600 0.6 16.0
Californium-252 20 540 0.2 5.4
Cobalt-60 30 810 0.3 8.1
Curium-244 50 1,400 0.5 14.0
Cesium-137 100 2,700 1.0 27.0
Gadolinium-153 1,000 27,000 10.0 270.0
Iridium-192 80 2,200 0.8 22.0
Plutonium-238 60 1,600 0.6 16.0
Plutonium-239/Be 60 1,600 0.6 16.0
Polonium-210 60 1,600 0.6 16.0
Promethium-147 40,000 1,100,000 400.0 11,000.0
Radium-226 40 1,100 0.4 11.0
Selenium-75 200 5,400 2.0 54.0
Strontium-90 1,000 27,000 10.0 270.0
Thorium-228 20 540 0.2 5.4
Thorium-229 20 540 0.2 5.4
Thulium-170 20,000 540,000 200.0 5,400.0
Ytterbium-169 300 8,100 3.0 81.0

TBq - Terabecquerel
Ci - Curie