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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 #16-0016 ([U.S. Customs and Border Protection] [Mr. Jason Hart])

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

Interpretation Response Details

Response Publish Date:

Company Name: U.S. Customs and Border Protection

Individual Name: Mr. Jason Hart

Location State: GA Country: US

View the Interpretation Document

Response text:

June 01, 2016

Mr. Jason G. Hart
Health Physicist
Occupational Safety and Health, East Team
Headquarter, Human Resource Management
U.S. Customs and Border Protection
U.S. Department of Homeland Security
510 Sable Trace Way
Acworth, GA 30102

Reference No. 16-0016

Dear Mr. Hart:

This letter is in response to your January 29, 2016 email and March 4, 2016 telephone call with a member of my staff requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180).  Specifically, you ask how to classify and prepare for transportation a number of sealed button Class 7 (radioactive) sources each containing 1 microcurie of Cesium-137 (Cs-137).  We have paraphrased your questions and answered them in the order you provided.  

You state your agency purchased these button sources over a span of approximately 10 years from a variety of vendors for use in devices designed to verify that personal radiation devices (PRDs) are functioning properly but retained neither the documentation that describes the activity nor any certified forms.  You also state when a button source no longer emits sufficient gamma rays to cause a PRD to alarm, it is removed replaced, and stored onsite.

Q1. You state that, based on § 173.421, Cs-137’s activity threshold for Class 7 radioactive material is 0.27 microcuries.  

A1. The definition of “radioactive material,” shown below and found in § 173.403 of the HMR rather than the regulatory text in § 173.421, provides the basis for determining whether a source is considered a radioactive material and when it would be regulated in transport.  

Radioactive material means any material containing radionuclides where both the activity concentration and the total activity in the consignment exceed the values specified in the table in § 173.436 or values derived according to the instructions in § 173.433.

To determine if these sealed button sources are exempt from the HMR when offered for transportation, those persons preparing them for shipment must first determine the consignment activity and activity concentration using the methods prescribed in  § 173.433(a).  Please note, calculation of a radioactive material’s activity concentration should only account for the radioactive material itself and not take into account the mass of the encasing, surrounding, or packaging materials.  Per the information you provided regarding their total activity as being 0.27 microcuries, your sealed button sources would be above the exempt consignment activity limit.  

Q2. You state it is your understanding that the upper range of “limited quantity” for the button source is up to 540,000 microcuries.  

A2. This is incorrect.  It is based on the A1 value found in § 173.435.  If the source is certified as “special form” radioactive material, the correct value would be approximately 54,000 microcuries.  If the source is “normal form” radioactive material, then the A2 value must be used and the correct upper limit would be approximately 16,000 microcuries.  

You provided no information as to whether the source is certified as special form radioactive material, as defined in § 173.403, and meets the test requirements of § 173.469; therefore, this source must be considered to be normal form.  If you determine that the sealed sources are special form, please note that in accordance with § 173.476(a), each offeror of special form Class 7 (radioactive) materials must maintain on file for at least two years after the offeror's latest shipment, and provide to the Associate Administrator on request, a complete safety analysis, including documentation of any tests, demonstrating that the special form material meets the requirements of § 173.469.  An International Atomic Energy Agency Certificate of Competent Authority issued for the special form material may be used to satisfy this requirement.  Lastly, footnote “b” to the Table in § 173.435 states:

The values of A1 and A2 in curies (Ci) are approximate and for information only; the regulatory standard units are Terabecquerels (TBq), (see § 171.10).  

The conventional units provided in the § 173.435 Table have slight rounding errors; therefore, the International System of Units (SI) values in TBq must be used for calculation purposes rather than the conventional Ci units.  

Q3. You state your understanding that when shipping these sealed sources in boxes by themselves, the exterior surface of the box must be tested for surface contamination according to § 173.421(c) and in conformance with, and not to exceed the limits specified in § 173.443(a).  In addition, you ask if such testing is truly required.  

A3. The shipper must either make one or more package wipe measurements in conformance with § 173.443(a)(1)(i) and compare the results against the limits in Table 9, or use the provision in § 173.443(a)(1)(ii) that allows the level of non-fixed contamination to be determined by using other methods of equal or greater efficiency.  Non-fixed (removable) radioactive surface contamination on the external surface of an excepted package of limited quantity Class 7 (radioactive) material must meet the requirements specified in § 173.443(a), which has both a quantitative upper limit and an “as low as reasonably achievable” component (see § 173.421(c)).  Section 173.443(a)(1) requires that the level of non-fixed radioactive contamination may not exceed the limits set forth in Table 9 of § 173.443.  The physical wipe survey technique is an efficient methodology to ensure compliance with the § 173.443(a)(1) requirement.  However, some shippers achieve compliance by instituting alternative requirements allowed under § 173.443(a)(1)(ii).  

Q4. You ask if a shipper of the sealed buttons that uses brand new boxes from a reputable vendor (such as FedEx) would be excepted from having to perform a wipe test.  

A4. New boxes that are received, stored, handled, and prepared for shipment in a manner that assures they have not been exposed to any contamination (e.g., such as ensuring the sources are contamination free, undamaged, and then packaged in a contamination free area) do not require the wipe tests prescribed in § 173.443(a)(1)(i).  As previously stated, in accordance with § 173.443(a)(1)(ii), the level of non-fixed contamination may be determined by using other methods of equal or greater efficiency.  However, such an alternative practice does not relieve the shipper of meeting the contamination limits of § 173.443(a)(1)(i).  If a package were to be discovered to exceed the contamination limits of § 173.443(a)(1)(i), then the shipper would not be compliant with the provisions in § 173.443(a)(1)(ii).  

I hope this information is helpful.  Please contact us if we can be of further assistance.


T. Glenn Foster
Chief, Regulatory Review and Reinvention Branch
Standard and Rulemaking Division

173.421, 173.403, 173.436, 173.433, 173.433(a), 173.469, 173.476(a), 171.10, 173.421(c), 173.443(a)(1) 173.443, 173.443(a)(1)(ii), 173.443(a)(1)(i)

Regulation Sections

Section Subject
171.10 Units of measure
173.403 Definitions
173.421 Excepted packages for limited quantities of Class 7 (radioactive) materials
173.421 Excepted packages for limited quantities of Class 7 (radioactive) materials
173.433 Requirements for determining basic radionuclide values, and for the listing of radionuclides on shipping papers and labels