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Technical Discussions
Jim McGregor
Jim McGregor
11:42 Dec-29-2009
Site use of Cobalt 60 for radiography

I am looking for some history of the site use Cobalt 60 to carry out radiography on field welds and vessels on industrial sites. Can anyone send me information on locations, source size, exposure times, equipment used, type of work carried out etc. Any troubles that were encountered whilst carrying out the inspection and their work around would be appreciated.
Thanks and regards,

Jim McGregor

 
 Reply 
 
John O'Brien
Consultant, -
Chevron ETC , USA, Joined Jan 2000, 280

John O'Brien

Consultant, -
Chevron ETC ,
USA,
Joined Jan 2000
280
14:01 Dec-29-2009
Re: Site use of Cobalt 60 for radiography
In Reply to Jim McGregor at 11:42 Dec-29-2009 (Opening).

Jim

you may need to re-post telling the geographical area where you want to use Co60 as the local regulations will have a big impact on the responses. A lot of places just would not allow its use. where allowed its an extra level of protection as it is a heavily penetrating isotope. As such your risk assessment needs to be more arduous. Planning the location of the exposure is paramount - remmbe rthe container is going to be alot heavier so physically manouvering it into place poses new challenges. the size of your RT crew will likely increase. More needed to lift and place, patrol barriers, exclude personnel etc.
You may need to think more about collimation to control where radiation goes.
Source size will be a function of what you are allowed by jurisdictions and what you want to penetrate within a reasonable exposure time. I have seen 100 Curie sof Co60 in the past but you really want to avoid these values if possible unless you have a very thick section or you have a secure exposure area.

 
 Reply 
 
DJ Kallhof
DJ Kallhof
14:10 Dec-29-2009
Re: Site use of Cobalt 60 for radiography
In Reply to Jim McGregor at 11:42 Dec-29-2009 (Opening).

Many of the variables you are seeking are dependent on the source manufacturer and the items that require to be inspected. The physical source size of cobalt sources I have used in the past has been app. 0.225", give or take. What stands out in my mind as a potential problem is getting the source to the job site. At 500 lbs. plus, they are difficult to maneuver. That and the fact a larger area will need to be roped off were my two biggest complaints.

 
 Reply 
 
Phil
NDT Inspector, Radiation Safety
BINDT, MIAQP, United Kingdom, Joined Mar 2009, 151

Phil

NDT Inspector, Radiation Safety
BINDT, MIAQP,
United Kingdom,
Joined Mar 2009
151
23:55 Dec-30-2009
Re: Site use of Cobalt 60 for radiography
In Reply to Jim McGregor at 11:42 Dec-29-2009 (Opening).

Hi Jim,

As John states depends where you want to use it. I have used it only a couple of times during my career. Once in the UK, and a couple of times on site in Iran in the 70's.

Containers very heavy and difficult to move, in UK we used a crane to lift it into position for the exposure.

Regards,

Phil

 
 Reply 
 

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