STP has been experiencing a difference between predicted cycle lengths and actual EOC burnup (specifically, over-predictions of cycle length). This effect seems to have begun when we started using 1.5x (B-10 loading) IFBA. Westinghouse uses their APA package for our core design. Has any other utility had a similar experience?
Duane Gore
Supervisor, Reactor Engineering
STPNOC
(361) 972-8909
We don't use Westinghouse fuel anymore. Sorry I can't help much more than that.
J. E. Willett ---------------------------------------------------- Joseph E. Willett, P.E. Principal Reactor Engineer-Fuel Nuclear Operations Division E-mail: jwillett@oppd.com mailto:jwillett@oppd.com%20 Omaha Public Power District Phone: (402) 533-7213 Fort Calhoun Station Pager: (402) 561-3899 9610 Power Lane FAX: (402) 533-6747 Blair, NE 68008 Mail Station: FC-1-1 Plant ---------------------------------------------------- -------- ________________________________
From: Gore, Duane [mailto:degore@STPEGS.COM] Sent: Thursday, July 10, 2008 4:44 PM To: pwrrm@retaqs.com Subject: [Pwrrm] Cycle Length Prediction Error when using Westinghouse 1.5xIBFAs
STP has been experiencing a difference between predicted cycle lengths and actual EOC burnup (specifically, over-predictions of cycle length). This effect seems to have begun when we started using 1.5x (B-10 loading) IFBA. Westinghouse uses their APA package for our core design. Has any other utility had a similar experience?
Duane Gore Supervisor, Reactor Engineering STPNOC
(361) 972-8909
This e-mail contains Omaha Public Power District's confidential and proprietary information and is for use only by the intended recipient. Unless explicitly stated otherwise, this e-mail is not a contract offer, amendment, nor acceptance. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited.
At VC Summer we have been having cycle length prediction errors for many cycles, with at least 4 different IFBA concentrations. Since we do our own core design with APA, we have done a lot of investigations of the problem. W also did a root cause on why so many units are having problems with this. That's part of the reason behind the upgrade to ANC 9.0. Unfortunately, not all of the reactivity errors are going in the same direction, so when they benchmark ANC, they try to hit the average. A major factor in this issue is each utility's method for determining calorimetric reactor power. In other words, each unit may be operating at a different place within the ~2% calorimetric uncertainty, and a 1% change in core power will cause a reactivity change of around 35 ppm at the end of the second fuel cycle (at least in our unit - 3-loop core at 2900 MWth).
We tend to have a reactivity shortfall of about 300-600 pcm at the end of cycle. In the last few cycles we have implemented a bias factor on the eigenvalue, based on the average of the last 3 cycles. This has given us fairly good results, as long as there are no core modeling or fuel design changes.
I have given some presentations at the RxE seminar and the Tech User's Group on this issue. The BEACON User's Group has also discussed it, since the reactivity bias is programmed into the software. I'll be happy to discuss it further if anyone is interested.
Damon Bryson
(803) 345-4814
dbryson@scana.com
From: pwrrm@retaqs.com [mailto:pwrrm@retaqs.com] On Behalf Of Gore, Duane Sent: Thursday, July 10, 2008 5:44 PM To: pwrrm@retaqs.com Subject: [Pwrrm] Cycle Length Prediction Error when using Westinghouse 1.5xIBFAs
STP has been experiencing a difference between predicted cycle lengths and actual EOC burnup (specifically, over-predictions of cycle length). This effect seems to have begun when we started using 1.5x (B-10 loading) IFBA. Westinghouse uses their APA package for our core design. Has any other utility had a similar experience?
Duane Gore
Supervisor, Reactor Engineering
STPNOC
(361) 972-8909
-
BRYSON, DAMON V -
Gore, Duane -
WILLETT, JOSEPH E