PWRRM March 2006

pwrrm@retaqs.com

7 participants
6 discussions

IFBA Implementation
by Kinn Gregory S 24 Mar '06

24 Mar '06

IFBA burnout can create some unusual circumstances to be aware of: 1. At BOC, IFBAs deplete faster than the fuel, creating a positive reactivity change with burnup. This make a hump in the letdown curve. At BOC, Operators will need to borate slightly to maintain power, rather than dilute. At Wolf Creek, the switch from boration to dilution occurs at about 4,000 MWD/MTU. Brief Ops early about this operational impact, so they can get used to the idea. Don't schedule any maintenance that takes normal boration OOS at BOC. 2. NI currents initially go down with burnup, then up. IFBA initially flattens the flux profile causing more leakage (higher NI currents). As the IFBA burns out, leakage decreases. When IFBA burnout is nearly complete, normal burnup effects take over and leakage increases through EOC. This hasn't caused any operational problems, but brief Ops that they may be adjusting NI gains up with burnup instead of down for the first part of the cycle. 3. If you start the cycle with any radial tilt, IFBA burnout will cause it to get worse with burnup before getting better. A high-power quadrant burns IFBA faster, making it more reactive before the natural tendency to equilibrate takes over. This is a very gradual effect, but noticeable with long-term trending.

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RE: [Pwrrm] IFBA Implementation
by Cox, Nancy P 24 Mar '06

24 Mar '06

1. Calvert Cliffs has had positive MTC at BOC for about the past fifteen years. We design to get a 0 MTC core at 100% power at BOC. This means that when we reduce power MTC will go back positive, until around a burnup of 7000 or 8000 MWD/MTU. We give the operators placards every 1000 MWD/MTU (about once a month) showing them how many degrees of temperature is worth 1% of reactor power, both at 0% and 100% power. We also put on the placards at what boron concentration the MTC will switch from positive to negative. They get curves of HFP and HZP ITC versus burnup in the curve book too. If we measure an MTC that is too positive at BOC, then we will run with rods inserted enough to drive the MTC down. 2. The current Unit 2 cycle 16 is our first with IFBA. We do not have Hafnium inserts. We check our predicted relative power distributions before we start up, and adjust the Nis based on the predictions. We have been doing that since the early nineties, and it has worked well. - Nancy Cox Reactor Engineer Calvert Cliffs Nuclear Power Plant -----Original Message----- From: pwrrm-bounces(a)retaqs.com [mailto:pwrrm-bounces@retaqs.com] On Behalf Of Michael_Fanguy(a)dom.com Sent: Friday, March 24, 2006 8:43 AM To: pwrrm(a)keffective.com Subject: [Pwrrm] IFBA Implementation Hello to all, I'm looking for some OE on IFBA implementation and have the following questions. 1. Has anyone had experience with a 0 MTC core? How did it affect normal ops at full power or transients? 2. We'll be loading more fresh fuel near the periphery because of IFBA and will be removing Hafnium inserts in front of our NIs, so we're expecting increases in our NI signals. Has anyone had problems with NIs being over-ranged or not being able to adjust NIs to the calorimetric of this type of activity? Thanks for any help you can provide. Michael J. Fanguy Nuclear Analysis & Fuel Lead Reactor Engineer Surry Power Station Email: Michael_Fanguy(a)Dom.com Phone: 757-365-2155 Pager #: 3453 ----------------------------------------- CONFIDENTIALITY NOTICE: This electronic message contains information which may be legally confidential and/or privileged and does not in any case represent a firm ENERGY COMMODITY bid or offer relating thereto which binds the sender without an additional express written confirmation to that effect. The information is intended solely for the individual or entity named above and access by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution, or use of the contents of this information is prohibited and may be unlawful. If you have received this electronic transmission in error, please reply immediately to the sender that you have received the message in error, and delete it. Thank you. _______________________________________________ PWRRM mailing list PWRRM(a)retaqs.com http://www.keffective.com/mailman/listinfo/pwrrm >>> This e-mail and any attachments are confidential, may contain legal, professional or other privileged information, and are intended solely for the addressee. If you are not the intended recipient, do not use the information in this e-mail in any way, delete this e-mail and notify the sender. CEG-IP2

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FW: IFBA implementation
by Tom Tomlinson 24 Mar '06

24 Mar '06

A reply below from Whiting Delk at TVA. Tom Tomlinson President, RETAQS, Inc. (610) 277-8991 ext 201 _____ From: Delk, Whiting S. [mailto:wsdelk@tva.gov] Sent: Friday, March 24, 2006 12:33 PM To: pwrrm-bounces(a)retaqs.com Cc: Michael_Fanguy(a)dom.com Subject: IFBA implementation 1. Has anyone had experience with a 0 MTC core? How did it affect normal ops at full power or transients? TVA'a response for this question: The technical specifications for SQN and WBN have always required that the MTC be negative during operation. TVA did operate early cycles with the MTC near zero at HZP conditions early in the cycle. Since the isothermal temperature coefficient was negative at zero power and the power coefficient was negative throughout the operating range, TVA did not experience the difficulties that could arise from operating with a positive temperature coefficient or power coefficient.

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Re: [Pwrrm] IFBA Implementation
by paul_gurney＠fpl.com 24 Mar '06

24 Mar '06

Mike, For Seabrook, No experience with a 0 MTC at power. We design for 0 MTC at HZP. Regarding your NIS, if you do a good scaling calc pre-strartup, you should be in good shape. The wild card will be the removal of the Hf inserts. In our early days we had currents of 500-600 ua. Now we run 150-200 ua. We rescale NIs pre-startup using our clac data, do a tune-up at 50% (we are looking to move this 30%) and do the final rescale at 100%. We have not had any over-ranging problems but on occasion we need to adjust the coarse gain pot to do the calorimetric adjustment. Paul Gurney Michael_Fanguy@do m.com To: pwrrm(a)keffective.com Sent by: cc: pwrrm-bounces@ret Subject: [Pwrrm] IFBA Implementation aqs.com 03/24/2006 08:42 AM Please respond to "PWR Reactivity Management" Hello to all, I'm looking for some OE on IFBA implementation and have the following questions. 1. Has anyone had experience with a 0 MTC core? How did it affect normal ops at full power or transients? 2. We'll be loading more fresh fuel near the periphery because of IFBA and will be removing Hafnium inserts in front of our NIs, so we're expecting increases in our NI signals. Has anyone had problems with NIs being over-ranged or not being able to adjust NIs to the calorimetric of this type of activity? Thanks for any help you can provide. Michael J. Fanguy Nuclear Analysis & Fuel Lead Reactor Engineer Surry Power Station Email: Michael_Fanguy(a)Dom.com Phone: 757-365-2155 Pager #: 3453 ----------------------------------------- CONFIDENTIALITY NOTICE: This electronic message contains information which may be legally confidential and/or privileged and does not in any case represent a firm ENERGY COMMODITY bid or offer relating thereto which binds the sender without an additional express written confirmation to that effect. The information is intended solely for the individual or entity named above and access by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution, or use of the contents of this information is prohibited and may be unlawful. If you have received this electronic transmission in error, please reply immediately to the sender that you have received the message in error, and delete it. Thank you. _______________________________________________ PWRRM mailing list PWRRM(a)retaqs.com http://www.keffective.com/mailman/listinfo/pwrrm

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Incore thimble tube wear analysis
by Lehmann Elmer E 24 Mar '06

24 Mar '06

Hopefully this email will get to all the Westinghouse pwr Reactor Engineers for them to reply. Wolf Creek is currently putting together the paperwork for an application to the NRC for Plant Life Extension. We currently track and evaluate incore thimble tube fretting wear in our lower internals, fuel assembly bottom nozzle, and lower core plate using a spreadsheet we have developed that has an input from Eddy Current Test results that are obtained every refueling outage. The group set up for gathering information for Plant Life Extension indicates the NRC requires a procedure instead for the analysis and actions taken as a result of the analysis. 1) Do any of you use such a procedure, and if you do, could you supply me a copy to model one after to use at Wolf Creek? 2) If any of you have been approved for Plant Life Extension, did the NRC require such a procedure for your plant in order to be approved. 3) How do you account for wear scars that may extend into the area of repositioned thimble tube,i.e., a repositioning of 2 inches still is in the wear area and the next ECT shows large amount of wear in one cycle of operation. I would appreciate the above information so that if I need to write a procedure for analysis, it is very similar to procedures at other plants so it will not be used to ratchet other plants to revise their procedure or NOT get approved for Plant Life Extension.

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IFBA Implementation
by Michael_Fanguy＠dom.com 24 Mar '06

24 Mar '06

Hello to all, I'm looking for some OE on IFBA implementation and have the following questions. 1. Has anyone had experience with a 0 MTC core? How did it affect normal ops at full power or transients? 2. We'll be loading more fresh fuel near the periphery because of IFBA and will be removing Hafnium inserts in front of our NIs, so we're expecting increases in our NI signals. Has anyone had problems with NIs being over-ranged or not being able to adjust NIs to the calorimetric of this type of activity? Thanks for any help you can provide. Michael J. Fanguy Nuclear Analysis & Fuel Lead Reactor Engineer Surry Power Station Email: Michael_Fanguy(a)Dom.com Phone: 757-365-2155 Pager #: 3453 ----------------------------------------- CONFIDENTIALITY NOTICE: This electronic message contains information which may be legally confidential and/or privileged and does not in any case represent a firm ENERGY COMMODITY bid or offer relating thereto which binds the sender without an additional express written confirmation to that effect. The information is intended solely for the individual or entity named above and access by anyone else is unauthorized. If you are not the intended recipient, any disclosure, copying, distribution, or use of the contents of this information is prohibited and may be unlawful. If you have received this electronic transmission in error, please reply immediately to the sender that you have received the message in error, and delete it. Thank you.

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PWRRM March 2006