Re: ULTRASONICS AND DECONTAMINATION

[lakirk@ix.netcom.com]

Scarboro, Michael G. wrote:
> 
> > At the Browns Ferry Nuclear Plant (GE BWR) we have a decontamination
> > dilemma. A TORUS ring header has accumulated crud that is causing elevated
> > dose rates (100 mR/hr contact).  Unfortunately, there is no practical way
> > to access the internals of the header.  So, we would like to decontaminate
> > the header without being intrusive to the header internals.  The header is
> > a ~30 inch diameter pipe with a ~3/4" pipe wall thickness that encircles
> > the TORUS.  The header transmits water from the TORUS to various systems
> > used for reactor cooling (both shutdown and emergency).  The header is
> > completely filled with water at all times.  We can initiate flow through
> > the header, but it is not of sufficient velocity to flush away the crud.
> > An idea I am pursuing is the use of an ultrasonic wave applied on the
> > header pipe exterior surface to try and agitate the crud adhering to the
> > bottom of the pipe.  This when combined with flow might be able to flush
> > the crud from the ring header and back into the TORUS.  The TORUS is
> > normally desludged during each outage.  Incidentally, internal ring header
> > access can be physically achieved during an outage, but due to operability
> > requirements for cooling water supplies it is not practical nor safe.
> >
> > Has anyone out there ever employed such a technique?  Can anyone point me
> > to a reference or source of such ultrasonic devices?
> >
> > Thanks,
> >
> >
> ************************************************************************
> The RADSAFE Frequently Asked Questions list, archives and subscription
> information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html
Michael,
Have you tried Dry Ice Blasting?  CO2 blasting might solve your
problem.  I know of one service company that blasts hazardous materials,
but I don't know if they if they have done rad work.  Good Luck.

Lloyd
************************************************************************
The RADSAFE Frequently Asked Questions list, archives and subscription
information can be accessed at http://www.ehs.uiuc.edu/~rad/radsafe.html