Interpretation Response #19-0034
Below is the interpretation response detail and a list of regulations sections applicable to this response.
Interpretation Response Details
Response Publish Date:
Company Name:
Individual Name: Mr. W. A. Winters
Location State: NM Country: US
View the Interpretation Document
Response text:
August 12, 2019
Mr. W. A. Winters
379 Aragon Avenue
Los Alamos, NM 87547
Reference No. 19-0034
Dear Mr. Winters:
This letter is in response to your March 21, 2019, letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the transportation of radioactive materials. We have paraphrased and answered your questions as follows:
Q1. In your letter, you describe a scenario in which the dose rate instrument used for beta/gamma is taken with an instrument that has a typical minimum sensitivity of 0.1 millirem/hour (mrem/h) gamma. You also note that there are several neutron reading instruments used with a typical minimum sensitivity of 0.25 mrem/h. You state that "Package A" contains a radionuclide(s) that emit both gamma and neutron radiation, and that the HMR requires both a gamma and neutron dose rate reading to be taken at the surface and one meter from the package. If the dose rate is not detectable above the instruments minimum sensitivity at either location, you ask whether it is acceptable to assign the dose rate as the minimum detectable for gamma and neutron radiation (0.1 mrem/h gamma + 0.25 mrem/h neutron = 0.25) and categorize "Package A" with the Class 7 label (i.e., Yellow II).
A1. The answer is no. It would not be acceptable to assign the dose rate as the minimum detectable of the instrument for gamma and neutron radiation. Furthermore, the instrument should be capable of detecting 0.05 mrem/h to determine whether the transport index should be greater than zero (see A5 below).
Q2. You state that "Package B" contains a gamma emitting nuclide(s) only, and that the HMR requires both a gamma and neutron dose rate reading be taken at the surface and one meter from the package. If the dose rate is not detectable above the instrument's minimum sensitivity at either location, you ask whether it is acceptable to assign the dose rate as the minimum detectable for gamma and neutron radiation (0.1 mrem/h gamma + 0.25 mrem/h neutron = 0.35) and categorize "Package B" with the Class 7 label (i.e., Yellow II).
A2. The answer is no. It would not be acceptable to assign the dose rate as the minimum detectable for gamma and neutron radiation. In this case, since it is known that there is only a gamma emitting nuclide, it would be inappropriate to assign the minimum detectable neutron reading to the dose rate. Furthermore, the instrument should be capable of detecting 0.05 mrem/h to determine whether the transport index should be greater than zero (see A5 below).
Q3. You state that "Package C" contains a beta-emitting nuclide only, and that the HMR requires both a gamma and neutron dose rate reading be taken at the surface and one meter from the package. If the dose rate is not detectable above the instrument's minimum sensitivity at either location, you ask whether it is acceptable to assign the dose rate as the minimum detectable for gamma and neutron radiation (0.1 mrem/h gamma + 0.25 mrem/h neutron = 0.35) and categorize "Package C" with the Class 7 label (i.e., Yellow II).
A3. The answer is no. It would not be acceptable to assign the dose rate as the minimum detectable for gamma and neutron radiation. In this case, since it is known that there is only a beta-emitting nuclide, it would be inappropriate to assign the minimum detectable gamma and neutron readings to the dose rate. Furthermore, the instrument should be capable of detecting 0.05 mrem/h to determine whether the transport index should be greater than zero (see A5 below).
Q4. You ask whether it is acceptable to be conservative and assign a higher category of Class 7 label to a package than that indicated by the dose rate instruments (i.e., Category Yellow II) rather than White I.
A4. The answer is no. Assignment of a higher label category than indicated by dose rate measurements would be inappropriate.
Q5. You ask whether it is required for the Class 7 label category determination that the person determining the dose rates uses a dose rate instrument and measurement times capable of achieving the minimum dose rate stated for Class 7 label categorization, specifically, 0.05 mrem/h (total combined gamma and neutron when neutron emitters are present).
A5. The answer is no. The HMR does not specifically state that an instrument must be used or be capable of achieving a minimum dose rate of 0.005 mrem/hr. However, under § 173.22 of the HMR it is the shipper's responsibility to properly classify a hazardous material. It is recommended that for Class 7 label category determination that the person determining the dose rates for the Class 7 label categorization use a dose rate instrument and measurement times capable of detecting the minimum dose rate stated for Class 7 label categorization (per 49 CFR 172.403), specifically, 0.05 mrem/h.
Q6. You ask whether it is acceptable to use scientific calculations to determine the dose rate at one meter rather than performing actual instrument dose rate measurements.
A6. The answer is yes. However, under § 173.22 of the HMR it is the shipper's responsibility to properly classify a hazardous material. While calculations may give an indication of the expected levels, confirmation from actual readings is recommended to assure that the package is properly loaded, assembled, closed and prepared for transportation.
Q7. You ask whether it will be a violation of the HMR if a corporate policy requires minimum instrument sensitivity be assigned as the dose rate of a package and the Class 7 label category determined from this regardless of the actual dose rates and nuclides present.
A7. The answer is yes. The label category should be determined by actual dose rates.
I hope this information is helpful. Please contact us if we can be of further assistance.
Sincerely,
T. Glenn Foster
Chief, Regulatory Review and Reinvention Branch
Standards and Rulemaking Division
173.22, 172.403