Nuclear Reactor Fuel Rods are Radioactive Sealed Sources, n'est pas?

[David W Lee <lee_david_w@lanl.gov>]

Dear Radsafers:

        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
Radiation Protection Policy
& Programs Analysis Group (ESH-12)
Los Alamos National Laboratory
PO Box 1663, MS K483
Los Alamos, NM  87545
Ph:  (505) 667-8085
FAX: (505) 667-9726