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Re: transportation event
This arrangement is generally known as "scab shielding," i.e. shielding which is not an integral part of the packaging. I
generally avoid it, for two primary reasons: (1) It often compromises package integrity. 2. The shielding may fail within the
package, resulting in a dose rate increase. With many radionuclides, the dose rate, not the quantity is the limiting condition
for an RQ shipment.
I remember a training class where a class exercise involved determining the maximum quantity of solid Co-60 that could be shipped
LQ. The activity limit is 10.8 mCi. With all of my usual diplomatic skills, I challenged the instructor to find a "strong tight"
package for that quantity of Co-60 which would meet the 0.5 mR/hr dose rate limit. (The unshielded dose rate from a Co-60 point
source of 10.8 mCi is ~150 mR/hr at 1 foot.)
In a situation such as this, there's a great temptation to add shielding to the package to achieve dose rate compliance. I would
generally avoid this. Possible solutions: use a bigger package, with the material securely centered in the package; use a
shielded package; or ship as NOS, rather than RQ. I suspect that an ammo box is not an adequate package for material in a lead
pig, especially if it were dropped on a top corner.
The opinions expressed are strictly mine.
It's not about dose, it's about trust.
Curies forever.
Bill Lipton
liptonw@dteenergy.com
John Jacobus wrote:
> The ammo can or box is not shielded, but the loaded
> syringes and vials are in lead pigs. The box has foam
> inserts into which the lead pigs are placed so they do
> not shift around. The ammo cans are usually shipped
> as a Radioactive White I or Radioactive Yellow II
> label.
>
> One issue we see is the package was obviously not
> secured in the truck.
>
> --- Doug Aitken <daitken@sugar-land.oilfield.slb.com>
> wrote:
> > At 01:13 PM 11/12/2003 -0800, John Jacobus wrote:
> > >Every ammo can that I have every seen used
> > indicates
> > >it is a Type A package.
> >
> > As the requirements of a Type 7A package are
> > adequate shielding and
> > security, both of which characteristics should not
> > be significantly lost
> > (e.g shielding efficiency maintained to 80%, no loss
> > of material) in the
> > event of transport damage (assessed by the drop
> > test, water spray test,
> > stacking test and penetration test), I don't see
> > that an "ammo case" would
> > be considered a Type 7A package without some
> > shielding added. And (IMHO) a
> > lose lead pig rattling around inside an ammo case
> > would not meet the
> > criteria for a type 7A package.
> >
> > Anyway, as Luke says, if we are talking exempt
> > quantities, no need for type
> > A packages.....
> >
> > . . .
>
> =====
> +++++++++++++++++++
> "Eternal vigilance by the people is the price of liberty and . . . you must pay the price if you wish to secure the blessing."
> Andrew Jackson
>
> -- John
> John Jacobus, MS
> Certified Health Physicist
> e-mail: crispy_bird@yahoo.com
>
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