The nationally tracked source thresholds are listed in table 1 below with the Terabecquerel (TBq) values as the regulatory standard. The curie (Ci) values specified are obtained by converting from the TBq value. The curie values are provided for practical usefulness only and are rounded after conversion.
Table 1
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
Americium-241/Be
60
1,600
0.6
16
Californium-252
20
540
0.2
5.4
Cobalt-60
30
810
0.3
8.1
Curium-244
50
1,400
0.5
14
Cesium-137
100
2,700
1
27
Gadolinium-153
1,000
27,000
10
270
Iridium-192
80
2,200
0.8
22
Plutonium-238
60
1,600
0.6
16
Plutonium-239/Be
60
1,600
0.6
16
Polonium-210
60
1,600
0.6
16
Promethium-147
40,000
1,100,000
400
11,000
Radium-226
40
1,100
0.4
11
Selenium-75
200
5,400
2
54
Strontium-90
1,000
27,000
10
270
Thorium-228
20
540
0.2
5.4
Thorium-229
20
540
0.2
5.4
Thulium-170
20,000
540,000
200
5,400
Ytterbium-169
300
8,100
3
81
Rulemaking Authority 404.051 FS. Law Implemented 404.022, 404.051, 404.081 FS. History-New 2-28-08, Amended 12-26-13.