Re: Sealed Source Definitions

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

RADSAFERS:  

	I apologize for getting into this thread "late," I've been on travel.

	The ANSI N43.6 definition of a "sealed source" is "radioactive source
sealed in a capsule or having a bonded cover, the capsule or cover being
strong enough to prevent contact with and dispersion of the radioactive
material under the conditions of use and wear for which it was designed."

	Semantically, I think one could quibble a bit about the above general
definition only in the sense that "sealed" is not "bonded" in any
dictionary sense, thus semantically it would be more accurate to say
"sealed/bonded source" is "radioactive source......" 

	As Les Slaback commented, it may be helpful to discern the purpose behind
why certain definitions are worded the way they are.  In the case of ANSI,
my perception is that the above definition was intentionally worded to be
as "general" as possible.  Note that basically it defines a "sealed source"
in terms of how such sources are made, i.e., surrounding radioactive with a
non-radioactive casing or plating radioactive material onto a
non-radioactive substrate.  I would contend that ANSI is quite satisfied
with this basic, very general "sealed source" definition, because from an
ANSI point of view, the intent is to invite as many entities as possible to
use ANSI N43.6 and to certify their products in accordance with (IAW) ANSI
N43.6.  Thus, ANSI's sealed source definition is intentionally general and
serves basically as a general invitation or entreaty that, in effect, says
"all those out there in manufacturing land engaged in the business of
putting radioactive material into non-radioactive cases or bonding it to
non-radioactive backings, please read this standard and consider certifying
your sources according to the proposed testing procedures."

	Note that the ANSI "sealed source" definition is so general as to
intentionally invite manufacturers of nuclear reactor fuel rods to certify
their rods under ANSI N43.6 as "sealed sources."  But as far as I know,
nuclear reactor fuel rod manufacturers do NOT normally certify the rods
they manufacture as "sealed sources" even though the NRC definitions
(discussed below) of a "sealed source" semantically declare such rods to be
"sealed sources."  Perhaps other Radsafers have information to the contrary
about this.

	10 CFR 30.4 and 70.4 contain the official NRC "sealed source" definitions,
the wording of which, if combined, would be "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."  I noted that Kit Weaver mentioned that he liked the NRC Reg
Guide 10.ll definition of a "sealed source," but I don't think the Reg
Guide 10.11 definition that he uses is actually in federal law.  To my
understanding, the existing NRC "sealed source" definitions, specified
above, do NOT include "bonded" sources as being "sealed sources."

	The issue as I view it is that the a general, ANSI-type definition of a
"sealed source" is too general and semantically unqualified to serve
adequately as a "regulatory" definition without additional clarifying
wording being integrated into the regulatory definition, itself.  Further,
from a REGULATORY viewpoint, I am unable to discern any regulatory utility
associated with defining a universe of "sealed sources" that includes items
that are not conveniently wipe testable.  As far as I can discern, if you
cannot readily swipe a sealed source's capsule, storage container, or area
around the bonded foil, what use is there, regulatory wise, to declaring it
to be a "sealed source"?  The basic radiation safety surveillance that you
pull on a "sealed source" is to periodically physically inventory it, wipe
test it, and verify that it is labeled correctly and in a proper storage
area.  Thus the question: what positive, regulatory benefit redounds to the
NRC by defining a "sealed source" to include nuclear reactor fuel rods,
radioisotope thermoelectric generators, fission chambers, etc.?

	The "sealed source" definitions of ANSI and the NRC have different
purposes.  ANSI wishes its definition to be as broad and general as
possible to invite as many entities as possible to certify their sealed
sources IAW ANSI N43.6.  NRC's purpose is narrower, yet the NRC seems to
have lifted the general ANSI definition and used it under the thinking that
it would serve as a perfect regulatory definition.  But the NRC sealed
source definition fails in the sense that it does not clearly delineate the
regulatory universe of sealed sources sufficient to avoid individual
interpretation or local questions.  Thus, many other Radsafers have
legitimately commented and offered up their own interpretation of the NRC
"sealed source" definition(s).  Ask yourself whether or not the NRC's
unclarified definition of a "sealed source" permits you to decide whether
or not the following items are "sealed sources" that ought to be regulated
as "sealed sources":

		Nuclear weapons components; tritiated metallic targets in D-T neutron
generators; yellow cake in closed shipping drums or UF6 in pressurized
cylinders; closed bottles of radioactive material in radiochemistry
laboratories or technetium generators; DU and thorium structures coated
with nonradioactive material used for shielding, ballast, or
counterweights; DU used in aircraft ailerons, landing gear, etc.; DU
contained in military munitions or armor plate; sodium iodide detectors
seeded with Am-241; gas chromatographs and Mossbauer analyzers containing
radioactive material, etc.

	I hope some Radsafer will respond that yellow cake inside a shipping drum
ought not to be a "sealed source" because the drum is merely a shipping
container, nothing more.  I would certainly agree, but also counter with
the statement that NRC's "sealed source" definitions appear to semantically
include yellow cake in a shipping drum as a "sealed source" in that the
NRC's sealed source definitions are little more than general ANSI type
definitions, i.e., radioactive material surrounded by a non-radioactive
casing.

	I agree with Al Tschaeche's lament about "whatever happened to sealed
source definitions that defined a "sealed source" in terms of using the
"emitted radiation.""  

	Based on any further responses to this thread, I will offer a definition
of a "sealed source" that is considerably clarified over the too general
NRC sealed source definitions.  Yes, Al, I remember the N43 "emitted
radiation" definition.  Thanks.

Best regards

David


At 12:42 PM 27-08-97 -0500, you wrote:
>
>Radsafers;
>
>The following are definitions from which you may pick your favorite: SEALED
>SOURCES
>
>ICRP 36-1982
>An amount of radioactive material in fixed form.
>
>NBS 66-1958
>Radioactive material that is incased in, and is to be used in, a container
>in a manner intended to prevent leakage of the radioactive material. Unles
>stated otherwise, the term "sealed source" in this Handbook is understood
>to refer only to sources containing radioactive material that emit beta
>rays (whether or not it also emits alpha, gamma or other radiation, and
>whether or not the beta rays are totally shielded by the container).
>
>NBS73-1960
>Radioactive material that is incased in, and is to be used in a manner
>intended to prevent leakage of the radioactive material.
>
>
>USAS N13.2-1969
>A radioactive source sealed in a container or having a bonded cover, where
>the container or cover has sufficient mechanical strength to prevent
>contact with and dispersion of the radioactive material under the
>conditions of use and wear for which it was designed.
>
>RHH-1970
>A radioactive source sealed in an impervious container which has sufficient
>mechanical strength to prevent contact with and dispersion of the
>radioactive material under the conditions of use and wear for which it was
>designed.
>
>ICRU 18-1970
>A sealed source consists of radioactive and inert material designed to be
>used in such a way that the active material does not enter into immediate
>contact with the source surroundings. It is comprised of one or more units
>such as discs, pellets or rods, or sometimes fine grains, incorporating
>radioactive  and inactive materials, sealed in an envelope or capsule of
>sufficient strength to prevent, under normal conditions of use, any
>dispersion of radioactive substances.
>
>ANSI N1.1-1976
>A radioactive source sealed in a container or having a bonded cover, the
>container or cover being strong enough to prevent contact with and
>dispersion of the radioactive material under the conditions of use and wear
>for which it was designed.
>
>NCRP 48-1976, NCRP 49-1976
>(Same as RHH-1970)
>
>ANSI N432-1980
>Radioactive material packaged in one or more capsules sealed to prevent
>escape of the radioactive material. The capsule or capsules are essentially
>transparent to the desire radiation.
>
>
>Sorry but that's all I could find.
>
>Regards,
>
>Rich Sobilo
>Radiation Safety Officer
>Beckman Instruments, Inc.
>rjsobilo@beckman.com
>
>
>
>
David W. Lee
Los Alamos National Laboratory
Radiation Protection Services Group (ESH-12)
PO Box 1663, MS K483
Los Alamos, NM  87545
PH:   (505) 667-8085
FAX:  (505) 667-9726
lee_david_w@lanl.gov