Re: minigenerators

[Michael Thomason <thomason@spot.Colorado.EDU>]

Jack Couch reports the Oxford Cs-137/Ba-137m minigenerator releases "a
lot" of 30-year half-life Cs-137 as well as the 1.3-minute half-life
Ba-137m.  I too have found this to be true.  Oxford, however, claims no
Cs-137 is released if the correct EDTA solution is used.

Have others observed this?  Many colleges and high schools are using this
generator intended for student use without taking any precautions for
long-lived radioactive waste.

Jack, can you quantify the Cs-137 activity in your samples from the Oxford
minigenerator?

Michael Thomason, Director of Physics Learning Laboratories
University of Colorado, Dept of Physics, Box 390, Boulder CO 80309-0390
MWF 303 -492-7117   TTh 303 492-8313   thomason@aeinstein.colorado.edu
http://www.colorado.edu/physics/2000/

On Thu, 27 Feb 1997, Jack Couch wrote:

> John, 
> You may get a flurry of replies on this. It was a thread topic a few months
> back. The old style generator that we all liked so well is no longer
> manufactured. I don't know the history, but it must have been
> profit-related. Oxford Instruments and a number of school science equipment
> companies market a new version.
> 
> Oxford Instruments, Inc.
> P.O. Box 2560, 
> 601 Oak Ridge Turnpike
> Oak Ridge, TN 37831-2560
> 1-800-7-Oxford
> 
> A 1995 price sheet lists it at $150
> Its called the Model M-2 Isogenerator, the activity of the parent Cs-137 is
> 9 microCi, and they recommend 0.1m EDTA solution rather than acid. I think
> we have ruined a couple of ours using acid. 
> 
> Our experience is that a lot of the Cs-137 leaches through, so if you are
> going to use it for half-life measurements of 2.6 min Ba-137m, count for a
> half hour, draw a horizontal base line back to zero time and subtract that
> as "background" instead of ambient lab background. We get pretty good
> results doing it that way. Two irksome problems: (1) Because of the new
> design, you are bound to drip solution on your fingers (wear protective
> gloves, of course), and (2) you have to deal with the Cs-contaminated fluid
> when you finish. Good luck.
> 
> Jack Couch
> Bloomsburg University
> 
>