Re: Q: "Tandetron" accelerator and regs

[LIPTONW@detroitedison.com]

--Boundary-2065565-0-0

My experience as an accelerator HP is that: 
 
(1)  Some accelerators have low dose rates most of the time, but are subject 
to malfunctions, such as a misaligned beam, that can suddenly increase the 
dose rates. 
 
(2)  Experimenters will want to "push the envelope" to try new things, such as 
increasing the power or current, or using different ions or different targets. 
 These can result in unexpectedly high dose rates.  For example, using the 
same voltages you mentioned with deuterons may produce high neutron fields. 
 
(3)  Accelerators often involve the use of nonradiologically hazardous 
materials.  For example, sulfur hexofluoride is often used as an insulating 
gas, to prevent sparking.  Although nontoxic, this can be an asphyxiant in a 
confined space.   
 
For these reasons, I would recomment that the control console not be in the 
target room, and that a health physics evaluation be required before allowing 
target room occupancy with the beam present; although it may be possible to 
set certain voltage and current parameters where no survey is needed.  
 
Bill Lipton 
The opinions expressed are solely mine. 


--Boundary-2065565-0-0
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Received: 01 May 1996 13:17:20                    Sent: 01 May 1996 12:07:19
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Subject: Q: "Tandetron" accelerator and regs
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A group of researchers here just bought a used 1.7 MV Tandetron tandem 
accelerator which is presently configured to accept either a hydrogen ion 
or helium ion source.  Expected beam performance will be:

5.1 MeV He++, 1 uA at high energy end
3.4 MeV H+, 30 uA at high energy end.

The configuration of the accelerator is such that the operating console 
is movable and is at this time located right next to the target end, but 
can be moved down to the source end as well.

Here's the problem... the regs here (Illinois is an agreement state) say 
that for particle accelerators, all entrances to the accelerator room 
must be equipped with two personnel interlocks.

But hm, the shielding and design of the accelerator is *supposedly* such 
that the accelerator can be safely operated from within the same room.  
This however throws the whole idea of double-interlocked doors into the 
air; what would be the point?

So, I know there should be several of these units around, and I assume 
that other states have regs similar to ours.  How is this being handled 
elsewhere?  Are other regulatory agencies allowing the operation of the 
console in the same room, and are you being held to the double-interlock 
requirement?

Thanks in advance!

--
 Melissa Woo, Health Physicist                       | m-woo@uiuc.edu
 University of Illinois at Urbana-Champaign          | office 1.217.244.7233
 DEHS, MC-225, 101 S. Gregory St., Urbana, IL  61801 | fax    1.217.244.6594
 http://www.uiuc.edu/ph/www/m-woo                    |





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