Any idea what revision of FBM03's you are using? There is a fix in modules
(Rev J & above I think) that corrects for thermal drift.
Phil
-----Original Message-----
From: Hicks, Gaylon F. [mailto:[EMAIL PROTECTED]]
Sent: 22 May 2001 17:03
To: 'Foxboro DCS Mail List'
Subject: FBM03 Drift Characteristics
I'm conducting an informal survey in lieu of talking to TAC. I would
appreciate and pertinent information anyone can share.
First, a little background. Browns Ferry uses Feedwater line temperatures
as an input to our core thermal power calculation during normal operation
(it's basically an enthalpy balance calc), and we operate based on our
licensed thermal power limits, so we get whatever electrical MWs output
based on this amount of steam, river temperature, etc.. If this number is
inaccurate, we can lose electrical output, and we appear to be missing about
9 MW electric at the moment. Our Feedwater line temperature is measured by
two four-wire precision 100 ohm platinum RTDs on each of two Feedwater lines
with a EXTBLK connection to a CHARC block. We use lab data RTD specific
curves for each AIN block (we really, really want this to be accurate), and
have these four inputs split between two FBM03s on the same CP. We normally
operate with a FW temperature of about 380 degrees F.
Over the last year all four RTD measurements have trended downward about 1
degree F, which would account for about 2 MW electrical. I have been tasked
with contacting the vendor (Foxboro) to ask if there is any known failure
mode or mechanism that would cause these four RTDs on two separate FBM03s to
trend downward. I though I would try the list first to solicit opinions.
No derogatory comments please. I have already expressed my opinion on this
subject, but I don't want to bias anyone.
Again, your patience and any input is appreciated.
Thanks,
==================================================
Gaylon Hicks
Tennessee Valley Authority, Browns Ferry Nuclear Plant
Mail Stop PEC-2C
PO Box 2000
Decatur, AL 35609
Phone: (256) 729-7804 Fax: (256) 729-2047
email: [EMAIL PROTECTED]
FedEx Address: Shaw Road, Athens, AL 35611
==================================================
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