[ RadSafe ] Infinite Thickness of KCl

[Rahim Ghanooni]

Eric:



I used Microshield to calculate the dose rate.  Since I do not have enough
information I made the following assumptions.



I created a disk with 1 cm radius; consist of K-40, at density of 1.98 g/cc,
activity of 0.416 uCi/cc, and thickness of 1 cm, the dose rate was
calculated at distance of 5 cm from front center of the disk.



The calculation started at thickness of one cm, with buildup, and continues
adding to the thickness while the activity distribution kept constant (0.416
uCi/cc).



Rahim Ghanooni, CHMM

Shielding Engineer/ Health Physicist



Thickness of 1 cm exposure rate 3.27E-2 mr/hr

Thickness of 10 cm exposure rate 1.1E-1 mr/hr

Thickness of 15 cm exposure rate 1.18E-1 mr/hr

Thickness of 25 cm exposure rate 1.208E-1 mr/hr

Thickness of 30 cm exposure rate 1.22E-1 mr/hr

Thickness of 35 cm exposure rate 1.23E-1 mr/hr


On Tue, Aug 30, 2011 at 10:49 AM, <Nielsen.Erik at epamail.epa.gov> wrote:

> I am trying to determine the infinite thickness of the 1460 keV gamma
> emission (10.5% abundance) of a planar source of KCl (416 pCi/g) and a
> density of 1.98 g/cc.
>
> In other words, what is the thickness of a KCl planar source where any
> additional thickness does not increase the surface dose rate?
>
> I have scoured my references but have not located the appropriate formula
> for calculating this value.
>
> I would appreciate any references or suggestions for an appropriate
> calculation.
>
> Erik C. Nielsen
> USEPA, National Air and Radiation Environmental Laboratory
> 540 South Morris Ave.
> Montgomery, AL 36115
> Phone 334-270-3475
> Fax 334-270-3454
>
> "Those who do not read are no better off than those who cannot"
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