Answer to Question #11555 Submitted to "Ask the Experts"

Category: Instrumentation and Measurements — Instrument Calibration (IC)

The following question was answered by an expert in the appropriate field:

Q

Is Pylon 1025 (Pylon Electronics Inc.) considered a sealed source or unsealed source?

A

While the Pylon source that you cite is designed to allow radon-222 (222Rn) gas to escape for use in controlled studies, the radium-226 (226Ra) precursor is in the form of a dry preparation that is contained in an encapsulation intended to prevent the leakage of the radium from the encapsulation. In this sense, the source meets the condition described by the US Nuclear Regulatory Commission (NRC) in 10 CFR 30.4, which states "Sealed source means any byproduct material that is encased in a capsule designed to prevent leakage or escape of the byproduct material." There are instances in which NRC-issued licenses list these specific Pylon sources as sealed sources; here is a link to one such.

As a result of changes to regulations brought about by the Energy Policy Act, sources of 226Ra described as discrete sources (whose activity has been enhanced by concentration techniques to make the material useful in various applications) may be considered byproduct material and thus fall under the regulatory oversight of the US NRC (except in NRC agreement states).

One consideration that should be noted is that if the source contains less than 3.7 × 105 becquerels (Bq) of 226Ra, it is not likely to be subject to leak testing that would otherwise be required (see 10 CFR 35.67f). Similar exclusions would be expected to apply in US NRC agreement states.

George Chabot, PhD, CHP

Ask the Experts is posting answers using only SI (the International System of Units) in accordance with international practice. To convert these to traditional units we have prepared a conversion table. You can also view a diagram to help put the radiation information presented in this question and answer in perspective. Explanations of radiation terms can be found here.
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