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10 CFR 73, Appendix I to Part 73 - Category 1 and 2 Radioactive Materials

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Appendix I to Part 73—Category 1 and 2 Radioactive Materials
Table I-1—Quantities of Concern Threshold Limits
Radionuclides Category 1 Category 2
Terabecquerels(TBq) Curies(Ci) 1 Terabecquerels(TBq) Curies(Ci) 1
1 The regulatory standard values are given in TBq. Curie (Ci) values are provided for practical usefulness only and are rounded after conversion.
Americium-241 6 × 101 1.6 × 103 6 × 10− 1 1.6 × 101
Americium-241/Be 6 × 101 1.6 × 103 6 × 10− 1 1.6 × 101
Californium-252 2 × 101 5.4 × 102 2 × 10− 1 5.4
Curium-244 5 × 101 1.4 × 103 5 × 10− 1 1.4 × 101
Cobalt-60 3 × 101 8.1 × 102 3 × 10− 1 8.1
Cesium-137 1 × 102 2.7 × 103 1 2.7 × 101
Gadolinium-153 1 × 103 2.7 × 104 1 × 101 2.7 × 102
Iridium-192 8 × 101 2.2 × 103 8 × 10− 1 2.2 × 101
Promethium-147 4 × 104 1.1 × 106 4 × 102 1.1 × 104
Plutonium-238 6 × 101 1.6 × 103 6 × 10− 1 1.6 × 101
Plutonium-239/Be 6 × 101 1.6 × 103 6 × 10− 1 1.6 × 101
Radium-226 4 × 101 1.1 × 103 4 × 10− 1 1.1 × 101
Selenium-75 2 × 102 5.4 × 103 2 5.4 × 101
Strontium-90 (Y-90) 1 × 103 2.7 × 104 1 × 101 2.7 × 102
Thulium-170 2 × 104 5.4 × 105 2 × 102 5.4 × 103
Ytterbium-169 3 × 102 8.1 × 103 3 8.1 × 101
Calculations Concerning Multiple Sources or Multiple Radionuclides
The “sum of fractions” methodology for evaluating combinations of multiple sources or multiple radionuclides, is to be used in determining whether a facility or activity meets or exceeds the threshold limits and is thus subject to the physical and/or information security requirements of this part.
I. If multiple sources and/or multiple radionuclides are present in a facility or activity, the sum of the fractions of the activity of each of the radionuclides must be determined to verify the facility or activity is less than the Category 1 or 2 limits of Table 1, as appropriate. Otherwise, if the calculated sum of the fractions ratio, using the following equation, is greater than or equal to 1.0, then the facility or activity meets or exceeds the threshold limits of Table 1 and the applicable physical and/or information 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 from Table 1 or of the individual sources (of the same radionuclides from Table 1) in the numerator of the equation and the corresponding threshold activity limit from Table 1 in the denominator of the equation. Sum of the fraction calculations must be performed in metric values (i.e., TBq) and the numerator and denominator values must be in the same units.
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
[73 FR 63580, Oct. 24, 2008, as amended at 74 FR 62684, Dec. 1, 2009]

Title 10 published on 2012-01-01

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  • 2013-03-19; vol. 78 # 53 - Tuesday, March 19, 2013
    1. 78 FR 16922 - Physical Protection of Byproduct Material
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      NUCLEAR REGULATORY COMMISSION
      Final rule.
      Effective Date: This final rule is effective on May 20, 2013. Compliance Date: Compliance with this final rule is required on March 19, 2014.
      10 CFR Parts 20, 30, 32, 33, 34, 35, 36, 37, 39, 51, 71, and 73

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Title 10 published on 2012-01-01

The following are ALL rules, proposed rules, and notices (chronologically) published in the Federal Register relating to 10 CFR 73 after this date.

  • 2013-04-22; vol. 78 # 77 - Monday, April 22, 2013
    1. 78 FR 23684 - Personnel Access Authorization Requirements for Nuclear Power Plants
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      NUCLEAR REGULATORY COMMISSION
      Petition for rulemaking; notice of receipt and request for comments.
      Submit comments by June 6, 2013. Comments received after this date will be considered if it is practical to do so, but the NRC is able to assure consideration only for comments received on or before this date. Because the NRC has determined that the petition should be expedited due to the aforementioned pending arbitration cases, requests for extension of the comment period will not be granted.
      10 CFR Part 73