High Contamination

["Mitchell, Michael T." <mtmitchell@tva.gov>]

Hello All,

We just completed a short mid-cycle outage here on one of our units.  We
had been operating for some time with some known leakers.  Following a
scram which ended a 390 consecutive day run it was decided to
dissassemble and replace the leakers.  Naturally this presented an
opportunity to make an entry into primary containment (drywell for us
BWRs) to find and repair an unidentified leak.  This is where our
problem arises.  The leak was on a reactor water recirculation system
sensing line.  Thanks to our less than stellar fuel performance
contamination levels in the drywell were staggering.  Levels in the
immediate area of the leak were as high as 260 rad/hr beta and 6 rem/hr
gamma.  General smearable levels were from 3 to 25 million dpm/100cm2.
Needless to say, it presented quite a challange in the area of
contamination control and personnel protection.  Now to the problem:  We
have a scheduled outage in Oct 98 on this unit.  Based on the assumption
that we have rectified the fuel problem,looking at the isotopic mix, and
considering half-lives, I still think we will have at least half of the
goodies around in Oct.  We have formed a team to investigate decon
options come Oct.

I would greatly appreciate hearing from any of you who may have had
experience cleaning up such levels, and any successful/suggested
techniques.  Of course, only limited time will be allowed in the
schedule.  Such are the challenges for the nuclear plant HP.  Thanks in
advance. You can respond to me directly. 
Mike Mitchell

=======================================================
Michael. T. Mitchell
Health Physicist

Tennessee Valley Authority
Browns Ferry Nuclear Plant
Phone: (205) 729-2401
Fax: (205) 729-3157
mailto:mtmitchell@tva.gov