# Department of Energy — Hazardous Materials Safety Interpretation **Citation:** 06-0100 **Type / status:** guidance / guidance **Agency:** Pipeline and Hazardous Materials Safety Administration **Effective:** Not stated **Published:** 2006-10-13 06-0100 response to Department of Energy concerning 173.453. ## Document text <<>> .S. Departmen f Transportatio Washington, D.C. 20590 400 Seventh Street, S.W. Pipeline and lazardous Materials Safet dministratio OCT 13 2006 Mr. James M. Shuler Ref. No.: 06-0100 Department of Energy Washington, D.C. 20585 Dear Mir. Shuler: ,in This is in response to your April 20, 2006 letter requesting clarification of the Hazardous Specifically, you request clarification of the exception in § 173.453(f) for fissile material. Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to radioactive materials. You request additional clarification of a response we provided to Dennis Ashworth in a letter of interpretation issued on January 17, 2006 (Ref. No. 05-0254) regarding this Q1. How is a shipment of plutonium defined? shipment of a material where plutonium is the primary radionuclide present, with only A1. For the purposes of the exception in § 173.453(f), a "shipment of plutonium" is the trace amounts of other radionuclides. Q2. How much plutonium must be present for the exception to apply? plutonium mass of not more than 1000 grams. The exception does not specify a A2. The exception in § 173.453(f) applies to packages containing, individually, a total minimum amount of plutonium; however, only trace amounts of other radionuclides may be present to qualify for the exception. Q3. How much plutonium must be fissile plutonium for the exception? A3. None of the plutonium "must" be fissile, but not more than 20 percent by mass may consist of plutonium-239, plutonium-241, or any combination of these. Q4. The January 17, 2006 letter of interpretation issued to Dennis Ashworth stated that the exception in § 173.453(f) is not intended to apply to shipments of large quantities of quantities"? uranium with some plutonium present. How much uranium is considered to be "large A4. As you noted in your letter, it is not possible to have fissile plutonium without some fissile uranium present. The scenario you presented of 1E-06 grams of plutonium-238 and 100 kg of uranium-235 as package contents is not the type of shipment that is intended to be covered by the exception. To satisfy the exception in § 173.453(f) only 173.453 (f) 060100 <<>> trace amounts of uranium may be present; we interpret a trace amount of uranium to be less than or equal to 1% of the mass of the fissile plutonium present in the package. Q5. How much fissile uranium may be included in a shipment to qualify for the exception? A5. An acceptable level of uranium is less than or equal to 1% of the mass of the fissile plutonium present in the package. See A4. for the exception? Q6. Could 850 g of plutonium-238 and 100 g of uranium-235 in a single package qualify. A6. The answer is no. The exception is intended to apply to those shipments of plutonium that contain only trace quantities of uranium. See A4 and A5. Note that our January 17" letter referenced a proposal before the International Atomic mass; however, the current exception in § 173.453(f) applies specifically to plutonium. Energy Agency to expand the scope of the exception to permit 20% of fissile nuclides by contact this office. I hope this information is helpful. If you have further questions, please do not hesitate to Sincerely, ? /. Chief, Standards Development Gale Office of Hazardous Materials Standards <<>> Relerford DEPA Department of Energy §173.453f Washington, DC 20585 Fissile Materials APR 2 0 2006 Exceptions 06 - 0100 Mr. Edward T. Mazzullo, Director Office of Hazardous Material Standards, PHH-10 U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 400 7' Street, S.W. Attention: DHM-10 Washington, D.C. 20590-0001 The purpose of this letter is to request an interpretation of the Department of Transportation (DOT) Fissile Material Exception requirements as mentioned in the Title 49, Part 173.453. The relevant portions of 49 Code of Federal Regulations (CFR) 173.453 read as follows: Sec. 173.453 Fissile materials--exceptions. Fissile materials meeting the requirements of at least one of the paragraphs (a) through (f of this section are excepted from the requirements of this subpart for fissile materials... / 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. Because paragraph (f) is silent on the presence of uranium, packages containing shipment of large and potentially unsafe quantities of uranium. As an example, assume a payload contains 1E-06g of 238Pu and 100 kg of 235U. This payload contains a total plutonium mass of not more than 1000 g of which not more than 20 percent by mass is fissile plutonium. In a letter of interpretation signed by John Gale to Dennis Ashworth, dated January 17, 2006 (Reference 05-0254), it indicates "this exception is intended for shipments of plutonium" and "this exception is NOT intended to allow shipments of large quantities of uranium with 'some' plutonium included." <<>> 2 1. How is a "shipment of plutonium" defined? 2. How much plutonium must be present for this exception to apply? 4. How much uranium is considered to be "large quantities"? 3. How much of the plutonium must be fissile plutonium? Because 239 Pu quickly decays to 235U and 24! Pu decays to 233U, it is not physically 5. How much fissile uranium may be included in the shipment? A potent a incuand ency gecurs in that bender ped as fist gulpion apackage shipped fissile excepted. 6. Could 850 g 238 Pu and 100 g of 23U qualify for an exception under paragraph (f)? If you need any additional information, please contact me at (301) 903-5513 or by (e-mail: james.shuler@em.doe.gov). Sincerely, James M. Shuler Manager, Packaging and Certification Program Environmental Cleanup and Acceleration Office of Licensing Office of Environmental Management ## Provenance - Official: Yes - Source: - Source ID: `phmsa` - SHA-256: `dbd0fd506e9a5e6ba42d8dd5ef3229e28781405f97c1f6b5a411ea8810efb4e5` - Retrieved: 2026-08-20T00:59:31.977Z - Exported: 2026-08-22T19:15:09.177Z - Document slug: `phmsa-interpretation-06-0100` ### Source metadata ```json { "materialSubtype": "interpretation", "interpretationArea": "hazardous_materials", "representation": "full_text_from_official_pdf", "companies": [ "Department of Energy" ], "individuals": [ "Mr. James M. 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