USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

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

Interpretation Response #08-0079 ([Washington Closure Hanford] [Mr. G.J. Borden])

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

Interpretation Response Details

Response Publish Date:

Company Name: Washington Closure Hanford

Individual Name: Mr. G.J. Borden

Location State: WA Country: US

View the Interpretation Document

Response text:

July 9, 2008




Mr. G.J. Borden

Washington Closure Hanford

2620 Fermi Avenue

Richland, WA 99354

Ref. No.: 08-0079

Dear Mr. Borden:

This responds to your letter dated February 26, 2008 requesting clarification of the Hazardous Materials Regulations (HMR; Parts 171-180). Specifically, you ask for clarification on describing Class 7 (radioactive) material as Low Specific Activity (LSA) material. Your questions are paraphrased and answered as follows:

Q1. Is it appropriate to mix LSA types and classify the aggregate as the highest class of material?

A1. It is acceptable to mix LSA types and to classify the aggregate at the highest classification of material, provided (emphasis added) that the individual types are properly classified. Each constituent must meet the appropriate LSA material definition and meet the regulatory requirements for that classification. Also, since you are dealing with items with varying dose rates, when commingling these material types, care must be taken to ensure compliance with the requirement in § 173.411 that there be no significant increase in the radiation levels at the external surfaces of the package under routine conditions of transport.

In your second example, it is not clear why you would choose to return items classified as LSA-II material to the soil mixture when they could be shipped separately in an Industrial Package Type 2 (IP-2) and the soil could then be transported in an Industrial Package Type 1 (IP-1).

In your third example, you indicate that the metal items in the soil have high dose rates (several orders of magnitude higher than the soil). In order for these high dose rate items to be shipped as LSA-II material, not only must they meet the LSA-II material definition with an average specific activity of less than 10-4 A2 /g, but also the external radiation level from the unshielded material (the metal items) must not exceed 10 mSv/h (1 rem/h) at 3 meters from the unshielded material (see § 173.427(a)(1)). Compliance with this requirement does not allow a person to take credit for shielding provided by the packaging or the soil. The inherent property of the material must be limited so that even without any shielding, the dose rate would not exceed the limit.

As there may be multiple high dose rate items in some of your packages, you should show that if all the high dose rate items that might be in a single package were aggregated into the worst-case configuration (such that it would result in the highest dose rate at 3 meters), the resulting configuration would not exceed 10 mSv/h (1 rem/h) at 3 meters from the unshielded material, without taking any credit for shielding provided by the soil or packaging.

For those items that do qualify as LSA-II material, they must be properly secured such that the package limits are still met and there is not a significant (20%) increase at any external surface of the package during routine conditions of transport (see § 173.411).

Q2: Is it acceptable to use the criteria in NUREG-1608 Section 4.2.3 to determine if a material has the radioactivity distributed throughout for material that may have significant variations in dose?

A2: The approach given in NUREG-1608 section 4.2.3, while generally appropriate, may not be appropriate when there are significant variations in dose. Since your examples deal with a mixture of soil and activated metal items, section 4.2.4 of NUREG-1608, which addresses mixtures of materials, should be considered. That section notes that materials which the Nuclear Regulatory Commission (NRC) "Branch Technical Position on Concentration Averaging and Encapsulation" recommends should be considered as discrete items for low-level radioactive waste (LLW) classification should also be considered discrete items and be evaluated individually against the LSA definitions, as appropriate. Section 3.3.1 of the Branch Technical Position states that a mixture of activated metal items containing primary gamma-emitters (such as Co-60 that you cited as the primary isotope of concern) should be averaged only if the individual items are within 1.5 of the respective averaged concentration value for each nuclide.

Your first two examples of localized "hot spots" would indicate the need for a closer examination of the situation to determine how the activity is distributed throughout the material. The analysis that shows less than a factor of 10 differences between sections that are no greater than 0.1 m3 should be supplemented with consideration of the activity distribution of the activated metal. As the metal items are known discrete pieces, they should be considered separately from the soil and not averaged over a 0.1m3 volume (which would have the soil composing more than 3 ft3 of the 3.5 ft3). The potential for multiple metal items in close proximity must also be considered.

Your third example relies on the soil to provide shielding around the activated metal items in order to meet the limits of § 173.411. This is only appropriate if the resulting package can be shown to meet all of the applicable requirements. First, as discussed above, the metal items in a package must have an aggregate unshielded dose rate that does not exceed 10 mSv/h (1 rem/h) at 3 meters. Also, as stated in § 173.411(b)(2) for an IP-2 package, there should be no significant increase in the radiation levels when subjected to normal conditions of transport (see § 173.410(f)) or the free drop test of § 173.465(c). It is not clear if the metal items would qualify as LSA-II material or if the package arrangement you describe would meet these requirements.

Q3: If dose rate is a determining factor in "distributed throughout", what is the applicable guidance? Is the factor of 10 in NUREG-1608 for specific activity also applicable to dose rate? Or is meeting the limitations of § 173.441 the only concern regarding dose rates?

A3: Dose rate is not a specific determining factor in "distributed throughout," except that it should be used to inform the analysis of the distribution of specific activity as described above.

In addition to § 173.441 regarding dose rates, as discussed above, § 173.427(a) requires a limit of 10 mSv/h (1 rem/h) at 3 m from unshielded LSA material. Also, as discussed above, for an IP-2 package, § 173.411(b)(2)(ii) requires that there not be a significant increase in the radiation levels during routine conditions of transport.

Q4: Can a determination of "distributed throughout" (assessed through measurements, calculations or process knowledge) as identified in NUREG-1608 Section 4.2.3 be made on a "bounding case" based on a worst case scenario from the same waste stream covering multiple shipments, or does a separate evaluation need to be made for each individual shipment?

A4: It is the shipper"s responsibility to properly class and describe a hazardous material in accordance with the HMR for each shipment. A "bounding case" evaluation may be sufficient, provided the determination is adequately justified as being applicable to the individual shipments. Sufficient information would be needed to assure that the waste stream is uniform enough such that each individual shipment fits the bounding conditions.

In the example you provided, it is not clear what knowledge you would have about the distribution of metal pieces within the soil to be able to bound the number of pieces per package. Nor is it clear how uniformity of the soil or the metal items can be assumed.

Your questions reference the document NUREG-1608. Note that NUREG-1608 (RAMREG-003) was intended as general guidance to assist in applying the regulatory requirements for LSA material and SCOs that were introduced in 1996. However, no single document can address all issues related to the transport of these materials and objects. Furthermore, nothing in that document should be construed as having the force and effect of DOT regulations, or as relieving any shipper from compliance with the requirements of 49 CFR Part 173 or any other applicable regulation.

Also, please note that if any fissile nuclides are present, any shipments of this material must meet at least one of the paragraphs (a) through (f) of § 173.453, as non excepted fissile material is not permitted to be shipped as LSA material.

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

Sincerely,

 

Susan Gorsky

Acting Chief, Standards Development

Office of Hazardous Materials Standards

173.427 173.441

Regulation Sections

Section Subject
173.427 Transport requirements for low specific activity (LSA) Class 7 (radioactive) material and surface contaminated objects (SCO)
173.441 Radiation level limitations and exclusive use provisions