Wisconsin Administrative Code › Department of Health Services › DHS 110-199 - Health › Chapter DHS 157 - Radiation Protection › Appendix U

Current through June 24, 2024
Category 1 and Category 2 Quantity of Radioactive
				  Material Thresholds
The sum of fractions' methodology for evaluating combinations
				  of multiple sources, aggregated sources, or multiple radionuclides is to be
				  used in determining whether a location meets or exceeds the threshold and is
				  thus subject to the requirements of subch. XV of ch. DHS 157. Category 1 and
				  category 2 quantities of radioactive material do not include the radioactive
				  material contained in any fuel assembly, subassembly, fuel rod, or fuel pellet.
				  The terabecquerel (TBq) values are 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.
Radioactive material
Category 1 (TBq)
Category 1 (Ci)
Category 2 (TBq)
Category 2 (Ci)
Americium-241
								................................................................................
60
1,620
0.6
16.2
Americium-241/Be
								............................................................................
60
1,620
0.6
16.2
Californium-252
								................................................................................
20
540
0.2
5.40
Cobalt-60
								...........................................................................................
30
810
0.3
8.10
Curium-244
								.......................................................................................
50
1,350
0.5
13.5
Cesium-137
								.......................................................................................
100
2,700
1
27.0
Gadolinium-153
								................................................................................
1,000
27,000
10
270
Iridium-192
								..................................................................................
80
2,160
0.8
21.6
Plutonium-238
								...................................................................................
60
1,620
0.6
16.2
Plutonium-239/Be
								.............................................................................
60
1,620
0.6
16.2
Promethium-147
								................................................................................
40,000
1,080,000
400
10,800
Radium-226
								.......................................................................................
40
1,080
0.4
10.8
Selenium-75
								......................................................................................
200
5,400
2
54.0
Strontium-90
								.....................................................................................
1,000
27,000
10
270
Thulium-170
								......................................................................................
20,000
540,000
200
5,400
Ytterbium-169
								...................................................................................
300
8,100
3
81.0
Note:
Calculations Concerning Multiple
				  Sources or Multiple Radionuclides
I. If multiple sources of the same radionuclide or multiple
				  radionuclides are aggregated at a location, the sum of the ratios of the total
				  activity of each of the radionuclides shall be determined to verify whether the
				  activity at the location is less than the category 1 or category 2 thresholds
				  of Appendix U, as appropriate. If the calculated sum of the ratios, using the
				  equation below, is greater than or equal to 1.0, then the applicable
				  requirements of subch. XV of ch. DHS 157 apply.
II. First determine the total activity for each radionuclide
				  from Appendix U. This is done by adding the activity of each individual source,
				  material in any device, and any loose or bulk material that contains the
				  radionuclide. Then use the equation below to calculate the sum of the ratios by
				  inserting the total activity of the applicable radionuclides from Appendix U in
				  the numerator of the equation and the corresponding threshold activity from
				  Table 1 in the denominator of the equation. Calculations shall be performed in
				  metric values (i.e., TBq) and the numerator and denominator values shall be in
				  the same units.
R1 = total activity for radionuclide 1
R2 = total activity for radionuclide 2
RN = total activity for radionuclide n
AR1 = activity threshold for radionuclide 1
AR2 = activity threshold for radionuclide 2
ARN = activity threshold for radionuclide n
See PDF for
				  diagram