# 10 CFR Appendix P to Part 110 - Category 1 and 2 Radioactive Material

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Appendix P to Part 110 - Category 1 and 2 Radioactive Material

Table 1 - Import and Export Threshold Limits

Radioactive material Category 1 Category 2
Terabecquerels
(TBq)
Curies
(Ci) 1
Terabecquerels
(TBq)
Curies
(Ci) 1
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
Curium-244 50 1,400 0.5 14
Cobalt-60 30 810 0.3 8.1
Cesium-137 100 2,700 1.0 27
Gadolinium-153 1,000 27,000 10.0 270
Iridium-192 80 2,200 0.8 22
Plutonium-238 2 60 1,600 0.6 16
Plutonium-239/Be 2 60 1,600 0.6 16
Promethium-147 40,000 1,100,000 400 11,000
Radium-226 a 40 1,100 0.4 11
Selenium-75 200 5,400 2.0 54
Strontium-90 (Y-90) 1,000 27,000 10.0 270
Thulium-170 20,000 540,000 200 5,400
Ytterbium-169 300 8,100 3.0 81

1 The values to be used to determine whether a license is required are given in TBq. Curie (Ci) values are provided for practical usefulness only and are rounded after conversion.

2 The limits for Pu-238 and Pu-239/Be in this table apply for imports to the U.S. The limits for exports of Pu-238 and Pu-239/Be can be found in § 110.21.

a Discrete sources of radium-226.

Calculation of Shipments Containing Multiple Sources or Radionuclides

The “sum of fractions” methodology for evaluating combinations of radionuclides being transported, is to be used when import or export shipments contain multiple sources or multiple radionuclides. The threshold limit values used in a sum of the fractions calculation must be the metric values (i.e., TBq).

I. If multiple sources and/or multiple radionuclides are present in an import or export shipment, the sum of the fractions of the activity of each radionuclides must be determined to verify the shipment is less than the Category 1 or 2 limits of Table 1, as appropriate. If the calculated sum of the fractions ratio, using the following equation, is greater than or equal to 1.0, then the import or export shipment exceeds the threshold limits of Table 1 and the applicable security provisions of this part apply.

II. Use the equation below to calculate the sum of the fractions ratio by inserting the actual activity of the applicable radionuclides or of the individual sources (of the same radionuclides) in the numerator of the equation and the corresponding threshold activity limit from the Table 1 in the denominator of the equation. Ensure the numerator and denominator values are in the same units and all calculations must be performed using the TBq (i.e., metric) values of Table 1.

R1 = activity for radionuclides or source number 1
R2 = activity for radionuclides or source number 2
RN = activity for radionuclides or source number n
AR1 = activity limit for radionuclides or source number 1
AR2 = activity limit for radionuclides or source number 2
ARN = activity limit for radionuclides or source number n

$\sum _{1}^{n}\left[\frac{{R}_{1}}{{\mathrm{AR}}_{1}}+\frac{{R}_{2}}{{\mathrm{AR}}_{2}}+\frac{{R}_{n}}{{\mathrm{AR}}_{n}}\right]\ge 1$
[70 FR 37993, July 1, 2005, as amended at 71 FR 20339, Apr. 20, 2006; 82 FR 52826, Nov. 15, 2017]