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Re: [MW:11836] Ir92 with 32 Curie-What is the safe distance?

By Materials & Welding
Mr.Jean Staton,

I am looking for calculated safe distance for Ir192 isotope with 32 curie in open space.I don't think that the type of material and shooting have any role in my case as I mentioned clearly in my query that NDT crew shooting the joints without collimator in open space.So, as you know that the radiation coming out from isotopes must be scattered 360 degrees in X,Y&Z direction.The intensity of the Gamma rays will decrease once it penetrates the material wall and the rate of reduction will be based on the density and thickness of the material.In my case NDT crew following DWSI(Double Wall Single Image) and obviously intensity reduction should be only in one direction and not in all direction like what we expect in panoramic(SWSI) shot.

Regards,

Limesh 

On Tue, Jul 19, 2011 at 5:53 PM, Jean Staton <Jean.Staton@metco-ndt.com> wrote:

Your distance depends if you want an actual 2 mR/hr boundary or a calculated one, What are they shooting,etc.

 

From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of limesh M
Sent: Monday, July 18, 2011 10:47 PM
To: Materials & Welding
Subject: [MW:11816] Ir92 with 32 Curie-What is the safe distance?

 

Dear All,

In one fabrication yard,IR192(Iridium192) Isotope being used to take radiography of welded joints to ensure it's integrity after visual inspection.NDT crew usually brings radiation source with a strength of 32 Curie(NDT contractor claiming that they are using 32 curie only but I don't know the exact strength.This is due to client pressure otherwise they are ready to bang with higher curies!!).I would like to know what would be the safe distance when IR92 with 32 curie strength operates without collimator.How can I calculate the safe distance from above parameters?I need this calculation urgently due to non availability of completely covered (except roof) concrete bunker or natural sand wall.For NDT crew protection during RT, two pieces of concrete wall provided to cover their body.Moreover, people like skilled/unskilled workers are staying very close(20Mtr to 35 Mtr range) to radiography area and nobody aware of the seriousness of the activity including the world famous client!!!

It will be highly appreciated if someone could provide an excel spread sheet to calculate the safe distance for different source strength.

Thanks in advance



Regards,


Limesh

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