Re: Use of Portable Radiation Monitoring Equipment

["Mark A. Smith" <web25@charweb.org>]

In response to the rather philosohical question regarding how many 
redundant levels are needed in a fixed facility very high radiation area, 
I'd refer all of those that are interested to an IAEA report from 1995 
(maybe early 1996, I can't seem to find my copy right now) called 
"Lessons Learned from Accidents at Industrial Irradiators" (title 
approximately right...I really need to find that copy).

My response to the question - there have been instances in irradiators 
where the operator had confilcting signals from the control console; the 
electronic switch indicated sources down, the radiation monitor said 
sources were up.  Since the former indicator was not known to fail at 
this facility, but the radiation monitor had given erroneous readings 
several times, the operator assumed that the sources were down.  Entering 
the cell without carrying a survey meter, he eventually found that the 
sources were up, resulting in lethal dose.

Of course, the first supposition made in the previous posting about 
"trained operator" being incorrect is at the root of almost all the 
accidents discussed in the IAEA report.  My feeling is that, if the 
training is adequate, all interlocks and control systems are in place and 
operating correctly, the operator should carry the meter with him 
entering a very high radiation area.  The consequences for not doing so 
tend to be severe and the inconvenience associated with lugging the meter 
relatively small.




My personal and professional opinion, but also the standard practice for 
our company.

Mark Smith, CHP
SteriGenics International
web25@charweb.org