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Interpretation Response #10-0174 ([Integrity Inspection Services] [Mr. James Jagemann])

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

Interpretation Response Details

Response Publish Date:

Company Name: Integrity Inspection Services

Individual Name: Mr. James Jagemann

Location State: TX Country: US

View the Interpretation Document

Response text:

September 3, 2010




Mr. James Jagemann

Integrity Inspection Services

21422 Provincial Boulevard

Katy, TX 77450

Ref. No. 10-0174

Dear Mr. Jagemann:

This responds to your August 12, 2010 email regarding the transportation of radioactive material under the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180). Specifically, you request clarification of the method of calculation used to determine the level of contamination on the external surfaces of a package in accordance with § 173.443 of the HMR. Your question is paraphrased and answered as follows:

For instances when the wipe efficiency is assumed to be 0.10, if the instrument used to measure radioactivity provides a reading in counts per minute (cpm), do I need to include a factor to convert cpm to disintegrations per minute (dpm) or does the assumed 0.10 wipe efficiency incorporate a conversion from cpm to dpm?

In addition to the assumed 0.10 wipe efficiency, an instrument efficiency factor is needed to calculate the contamination activity on the wiping material. The wipe efficiency factor does not account for the effectiveness of the instrument in measuring radioactivity. The instrument efficiency factor is a function of the efficiency of the specific instrument in measuring the radioactivity on the wiping material. This instrument efficiency factor may be provided on the instrument, obtained through the manufacturer or supplier of the instrument, or determined by using reference standards of known radioactivity. Therefore, in your case, both a wipe efficiency factor and an instrument efficiency factor are needed to calculate the level of contamination in dpm.

I hope this information is helpful. If you have further questions, please contact this office.


Ben Supko

Acting Chief, Standards Development

Office of Hazardous Materials Standards


Regulation Sections

Section Subject
173.443 Contamination control