The
following are excerpts taken from
NUREG-1608/RAMREG-003, "Categorizing and Transporting Low
Specific Activity Materials and Surface Contaminated Objects",
(Date Published: July 1998), a guidance document jointly developed by DOT
and NRC:
3.1.1 If a
contaminated object is also activated, can it be categorized as an
SCO?
If a contaminated object is also activated to an average
specific activity level less than 70 Bq/g (2 nCi/g), the object itself is not
classified as radioactive material according to
49 CFR 173.403; however, the presence of the contamination on the object
may require that it be classed as a Class 7 (radioactive) material. For such an object, if the SCO
definition is satisfied, the object should then be classified as Class 7, and
shipped as an SCO.
3.1.2 Is there a
contamination level below which an object does not need to be categorized as an
SCO or as radioactive material, n.o.s.?
International
regulations contain a threshold value for contamination, below which a
nonradioactive object [i.e., an object having an average specific activity level
less than 70 Bq/g (2 nCi/g)] can be shipped without regard to the radioactivity
[See clarification of contamination in Section 3.2.1]. The contamination
threshold value was inadvertently omitted from the 1996 DOT domestic regulatory
revisions. Consequently, all objects which are themselves not radioactive,
but are slightly contaminated, could still be construed to qualify as
SCO-I. DOT is currently addressing this issue.
In the interim: an
object with external contamination may be considered to be excepted from
classification as Class 7 (radioactive) material if: (1) contamination when
averaged over each 300 cm2 of all surfaces is less than 0.4 Bq/cm2 for beta and
gamma emitters and low toxicity alpha emitters, and is also less than 0.04
Bq/cm2 for all other alpha emitters; and (2) the object itself has an average
specific activity less than 70 Bq/g (2 nCi/g).
3.2.1 What is contamination?
For the purpose of
complying with the SCO definitions in the domestic transportation regulations
only:
Contamination is the presence of a
radioactive substance on a surface in quantities in excess of 0.4 Bq/cm2 (22
dpm/cm2) for beta and gamma emitters and low toxicity alpha emitters or 0.04
Bq/cm2 (2.2 dpm/cm2) for all other alpha emitters.
This is
consistent with the definition for contamination provided in the international
regulations, although a similar definition is not currently included in the U.S.
domestic regulations. DOT is currently considering addition of the
contamination definition to 49 CFR Part 173.
This
internationally-recognized lower limit for contamination serves a function in
transport regulations comparable to the limit of 70 Bq/g (2 nCi/g) in the
definition of radioactive material; i.e., materials having specific activities
less than this limit are below the scope of the hazardous material
regulations. A definition of contamination is needed in order to properly
utilize the SCO category because the radioactive material definition of 70 Bq/g
(2 nCi/g), which is based on an activity per unit mass, is not readily or
directly applicable to SCOs. For nonactivated objects, dividing the
activity in the contamination by the mass of the nonactivated object (to
determine whether the object as a whole should or should not be defined as
radioactive material) is generally not appropriate because it opens the
possibility for a massive object with significant amounts of contamination on
its surfaces falling below the regulatory threshold definition of radioactive
material [i.e., specific activity would be less
than 70 Bq/g (2 nCi/g)]. This situation is not consistent with the
intent of the regulatory exemption limit and should be
avoided.
To my knowledge, this interpretation for classifying contaminated objects (that have a specific activity below the 49 CFR 173.403 definition of radioactive material) as Class 7 (radioactive) materials is only found in this guidance document. Does anyone know if DOT has formally addressed this issue as indicated in Section 3.1.2 of the guidance above?
Joe Christy
SLAC OHP Department
LLW/MLLW
Coordinator
650-926-2823
jchristy@slac.stanford.edu
-----Original
Message-----
From: Joe Heckman [mailto:jheckman@envirocareutah.com]
Sent:
Wednesday, September 19, 2001 6:56 AM
To:
radsafe@list.vanderbilt.edu
Subject: RE: Contaminated Scaffold Knuckles -
Turkey Point
Rodney,
For the purposes of transportation, materials
with concentrations of less
than 2 nCi/gram are not radioactive materials.
When one determines the
material to be shipped is less than 2 nCi/gram no
other consideration with
respect to RAM is required, therefore the LSA/SCO
requirements do not apply.
The LSA/SCO proper shipping names are used
primarily (when possible) because
exceptions to the packaging requirements
are given for this material.
Joseph Heckman, RRPT
Site Radiation
Safety Officer
Containerized Waste Facility
Envirocare of Utah,
Inc.
(801) 532-1330
jheckman@envirocareutah.com <mailto:jheckman@envirocareutah.com>
"Communications without intelligence is
noise;
Intelligence without communications is irrelevant."
Gen. Alfred. M.
Gray,
USMC
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