RE: Maze doors for HDR?

["Garner, William" <whgarn2@email.uky.edu>]

I am not sure if my situation would apply as my experience is with Ir-192, 10 - 100+ Ci, radiography sources.  I have used a maze type vault and we seemed to be fine as long as we didn't direct the exposure at the primary barrier shielding the door.  We control the direction of the exposure away from the primary barrier by using a tungsten collimator that allows us to "aim" the exposure where it is needed.  If the situation came up where we had to position the collimator closer to the barrier we would add more shielding using lead bricks or shot bags between the  collimator and the barrier.  Keeping the exposure direction in mind and taking meter readings at the entrance during exposures to verify levels always ensured that we were safe. 

 

William Garner

University Of Kentucky

Radiation Safety Office

Lexington, KY.  40506

Office: (859) 323-5795

FAX:   (859) 323-4752

Web: http://ehs.uky.edu/radiation/welcome.html



-----Original Message-----

From: owner-radsafe@list.Vanderbilt.Edu [mailto:owner-radsafe@list.Vanderbilt.Edu]On Behalf Of Dr. Sergio Faermann

Sent: Wednesday, May 12, 2004 07:13

To: radsafe@list.Vanderbilt.Edu

Subject: Maze doors for HDR?





Dear colleagues

 

We are in process of receiving a new HDR unit ( Gammamed),which is to be installed in an existing accelerator room

 ( Clinac 18)-10 MV X-rays).

The room was designed at the time with a maze and without the need of a shielded door.

My question is what is the methodology to calculate the dose at the door( scattered radiation) for  a 10 Ci Ir-192 HDR source? I didn't find in NCRP 51 references to the reflection coefficient for Ir-192.

 

Thanking you in advance

 

Sergio Faermann