United States Nuclear Regulatory Commission - Protecting People and the Environment

10 CFR Part 37—Physical Protection of Category 1 and Category 2 Quantities of Radioactive Material

On March 19, 2013, the NRC published the new 10 CFR Part 37 final rule in the Federal Register (78 FR 16922).  The new regulation establishes security requirements for the use and transport of the most risk-significant quantities of radioactive materials (i.e., International Atomic Energy Agency (IAEA) Category 1 and Category 2 quantities of radioactive materials), as well as for shipments of small amounts of irradiated reactor fuel.  The Category 1 and Category 2 quantities of radioactive materials are thresholds established by the IAEA in its Code of Conduct on the Safety and Security of Radioactive Sources.  The objective of 10 CFR Part 37 is to provide reasonable assurance of preventing the theft or diversion of Category 1 and Category 2 quantities of radioactive materials.  The final rule incorporates lessons learned by NRC and the Agreement States in implementing the post-September 11th security measures, as well as stakeholder input on the proposed rule.  The new 10 CFR Part 37 was effective on May 20, 2013 and NRC licensees must comply with the requirements by March 19, 2014.  Agreement States will have until March 19, 2016, to issue compatible requirements for their licensees.

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Types of Licensees Which Part 37 Could Apply To

  1. Industrial Licensees
  2. Academic and Research Licensees
  3. Medical Licensees
  4. Power Reactor Licensees
  5. Research and Test Reactors
  6. Decommissioning reactors
  7. Fuel Cycle licensees

Part 37 Documents

Rule documents

  • Final Rule
  • *Update: Effective August 15, 2013, the mailing address for Fingerprint
    submissions has changed to:

    Director, Division of Facilities and Security
    U.S. Nuclear Regulatory Commission
    11545 Rockville Pike
    Rockville, MD 20852-2738
    Attn: Criminal History Program, Mail Stop T-03B46M

  • SECY-11-070 – Final rule: Physical protection of byproduct material


  • NUREG-2155 - "Implementation Guidance for 10 CFR Part 37, Physical Protection of Category 1 and Category 2 Quantities of Radioactive Material," dated February 2013
  • NUREG-2166 - "Physical Security Best Practices for the Protection of Risk-Significant Radioactive Material," dated May 2014
  • Part 37 rule/Security order comparison (Enclosure 2 to SECY-11-070)

Questions and answers


  • Enforcement Guidance Memorandum 2014-001: Interim Guidance for Dispositioning 10 CFR Part 37 Violations with respect to Large Components or Robust Structures Containing Category 1 or Category 2 Quantities of Material at Power Reactor Facilities Licensed Under 10 CFR Parts 50 and 52
  • Enforcement Guidance (Note: NRC will use the current NRC enforcement guidance to disposition Part 37 violations.  NRC's current enforcement guidance can be found in the NRC Enforcement Policy, and the NRC Enforcement Manual. Guidance may be revised in the future.)

Contact Us

For any questions or comments related to any 10 CFR Part 37 topic, please send an email to Part37Resource@nrc.gov.

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Page Last Reviewed/Updated Tuesday, April 05, 2016