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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #05-0254 ([United States Department of Energy] [171.8, 172.202])

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: United States Department of Energy

Individual Name: 171.8, 172.202

Location State: DC Country: US

View the Interpretation Document

Response text:

Jan 17, 2006


Mr. Dennis Ashworth                     Reference No. 05-0254
Office of Transportation
Office of Environmental Management
United States Department of Energy
1000 Independence Ave S.W.
Washington, DC 20585

Dear Mr. Ashworth:

This is in response to your September 23, 2005 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) regarding the applicability of fissile material exceptions. Specifically, you request clarification of the fissile material exception provisions in § 173.453 (f) of the HMR. You cite the existing language of the exception and the wording proposed by the U.S. delegation at the recent International Atomic Energy Agency’s (JAEA) Transport Safety Standards Committee (TRANSSC) meeting for inclusion in the international regulations as follows:

  • 49 CFR 173.453(f): “Packages containing, individually, a total plutonium mass of not more than 1000 grams, of which not more than 20 percent by mass may consist of plutonium-239, plutonium-241, or any combination of these radionuclides.”
  • Proposed IAEA wording: “Packages containing no more than 20% of fissile nuclides by mass up to a maximum of 1 kg of plutonium per consignment”

The intent of § 173.453(f) is to allow shipments of plutonium (not uranium) as fissile excepted, provided the total mass of plutonium is less than 1 kg and no more than 20% of the plutonium nuclides are fissile (i.e., Pu-239 and/or Pu-241). The practical need for such an exception is related to the intrinsic safety of this mixture of plutonium nuclides (in a total mass less than 1 kg) and the large number ofPu-238 sources being shipped.

The new wording was proposed at the recent TRANSSC meeting to clarify that, as long as the total quantity of fissile nuclides (plutonium or uranium) is less than 20% of the total plutonium mass, the shipment can be excepted. Note, however, that this exception is still intended for shipments of plutonium with certain characteristics (limited quantity
of fissile nuclides); this exception is NOT intended to allow shipment of large quantities of uranium with “some” plutonium included.

I hope this information is helpful. Please contact us if you require additional assistance



John A. Gale
Chief, Standards Development
Office of Hazardous Materials Standards

173.457, 173.459

Regulation Sections

Section Subject
173.457 Transportation of fissile material packages-specific requirements
173.459 Mixing of fissile material packages with non-fissile or fissile-excepted material packages