Re: Nuclear Reactor Fuel Rods are Radioactive Sealed Source

[Keith Welch <welch@CEBAF.GOV>]

A couple more thoughts that may or may not be relevant (same caveat as Wes
used also).

I think, as Wes mentioned, UN-irradiated fuel is considered a sealed source.
But I think there is also a caveat somewhere, and I can't remember where at
the moment, that irradiated reactor fuel is a unique animal categorically.
Maybe I'm remembering an old regulation, or an aspect that doesn't relate to
sealed sources.  Does anybody know where this distinction is made - that
spent fuel is singled out as its own specific "type" of "source"?

What about the designation "source material" versus "byproduct or SNM", does
that change anything with regard to being a sealed source?  I don't have the
regs handy to look it up at the moment.



>
>        Hopefully some of the NRC experts on the Radsafe net will respond to
>the questions below.
>
>        The NRC has specified in two parts of federal law (10 CFR 30.4 and
>70.4) its official definitions of a "sealed source."  The wording of these
>definitions, if combined, would be as follows:
>
>                Sealed Source means any byproduct or special nuclear
>material (SNM) that is encased in a capsule designed to prevent leakage or
>escape of the byproduct or special nuclear material.
>
>        The NRC does not provide in either of these federal law parts any
>special NRC definition of a "capsule"; therefore, one must presume the
>generic or 'common' meaning of the word 'capsule' by default.
>
>        Based on the above NRC definition of a sealed source, does any
>Radsafer disagree with the semantic conclusion that nuclear reactor fuel
>rods are "sealed sources" as far as the NRC is concerned?
>
>        Assuming then that the NRC actually intended power reactor fuel rods
>to be construed as "sealed sources," can any Radsafer provide any background
>or elaboration as to why or how the NRC originally felt that it was useful,
>from a regulatory viewpoint, to include reactor fuel rods under a broad
>general 'sealed source' definition?  If it is logical to conclude that the
>NRC views nuclear reactor fuel rods as 'sealed sources,' then how does the
>NRC regulate such rods as 'sealed sources'?
>
>        Most licensed radioactive sealed sources (RSS) are "regulated" in
>the sense that periodic physical inventories are required (make sure you
>still have the sources firmly under your control) and wipe tests of some
>sort at some periodicity are required, generally at a minimum semiannual
>frequency, unless in long-term storage.  Given this reality, what is the
>advantage that redounds to the NRC of semantically defining nuclear reactor
>fuel rods as 'sealed sources' and presumably "regulating" them as RSSs?
>
>        Would this also mean that the NRC semantically regards a 'fission
>chamber' as a 'sealed source' and presumably would regulate it as an RSS?
>How about a Pu-238 radioisotope thermoelectric generator (RTG) whose thermal
>temperature on the exterior of the total RTG module can easily exceed 150
>degrees centigrade (not very amenable to traditional leak test methods).
>Does the NRC regard RTGs also as 'sealed sources' and regulate them as such?
>
>        I have previously asked some of these questions of Radsafer Keith
>Brown of the NRC, but have received no reply; therefore, I am soliciting the
>thoughts/opinions of all those on the Radsafe net.
>
>        Thank-you in advance for your consideration of these questions.
>
>REGARDS
>
>
>
>        
>David W. Lee

Keith Welch
Thomas Jefferson National Accelerator Facility
Newport News VA
welch@cebaf.gov