Update on TCA Problem with SNF Ox Tubes

Jim McVittie mcvittie at cis.Stanford.EDU
Thu Aug 29 19:18:32 PDT 2002


Tylan Furnace Users,

Our understanding of what was happening with the Tylan oxidation furnaces
has changed a bit since the note that I sent out yesterday.  In
particular, we found out that they had been an undocumented hardware
change to the TCA system some years ago, that none of the current staff
knew about. This change had allowed the TCA to flow with the way the
TCACLEAN program had been written, however this hardware change had also
allowed the corrosion problem to occurs. So the TCA cleans had been
running correctly but they were introducing Fe into the tubes.  Where we
stand is that all the corroded stainless steel tubing and fittings have
been replaced. Tonight instead of TCA cleans, we are running simple steam
cleans on all the tubes.

Before we start running TCA cleans again, we are accessing several
possible hardware changes to make sure that the corrosion problem does not
occur again.  We suspect that the Fe (Iron) level is higher than we would
like but it is not probably no higher than it has been for the past
several years. It will take us a few days to fully determine which of the
proposed hardware changes is best. I will keep you posted.

Thanks for your patience.  

			Jim 	
--------------------------------------------------------------
James P. McVittie	                Senior Research Scientist
Allen Center for Integrated Systems     jmcvittie at stanford.edu
Stanford University             	Tel: (650) 725-3640	
Rm. 336, 330 Serra Mall			Fax: (650) 723-4659
Stanford, CA 94305-4075	




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