ML20198N365
| ML20198N365 | |
| Person / Time | |
|---|---|
| Site: | Byron  |
| Issue date: | 10/24/1997 |
| From: | Graesser K COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BYRON-97-0239, BYRON-97-239, NUDOCS 9711040071 | |
| Download: ML20198N365 (3) | |
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Isl H14144 S ill October 24,1997 LTR; BYRON 97-0239 FILE: 2.01.0301 U.S. Nuclear Regulatory Commission A'1 Tit Document Control Desk Washington, DC 20555-0001
SUBJECT:
Supplement to Application for Amendment to Appendix A, Tecimical Specifications, for Facility Operating Licenses Byron Nuclear Power Station Units I and 2 Facil:ty Operating Licenses NPF-37 and NPF-66 NRC Dockst Nos. 50-454 and 50-455
" Electrical Power Systems, D. C. Sources"
REFERENCES:
- 1. Letter from K. L. Gracsser (Comed) to NRC Document Control Desk transmitting Technical Specification Amendment Request for 125 volt de batteries, dated April 7,1997 (BYRON 97-0079) 2 Letter from G. F. Dick, Jr. (NRC) to 1. M. Johnson (Comed) transmitting a Request for Additional infomution regarding the proposed replacement of Gould batteries with C&D Charter Power Systems batteries, dated June 20,1997
- 3. Letter from K. L. Graesser (Comed) to NRC Document Control Desk transmitting a Response to a Request for Additional Information regarding the proposed replacement of Gould batteries with C&D Charter Power Systems batteries, dated August 7.1997 (BYRON
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97-0180)
In Reference 1, Commomvealth Edison Company I. Comed) submitted an application for amendment to Appendix A, Technical Specifications, for the 125-volt de batteries at Bvrm Nuclear Power Station. The NRC issued a Request for Additional Information (RAI) m Reference 2. Reference 3 provided the requested information.
In Reference 3, the response to question 4 stated that the design margin used to size the C&D batteries is 10% Subsequent testing of the battery cells at the factory has resulted in a change to our response to question 4. He design margin used to size the C&D batteries is now 5%
A detailed discussion of the design margin is provided in the attachment.
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_ October 24,1997 Page 2 if you have any questions concerning this correspondence, please contact Marcia Lesniak at (630) 663-6484.
Sincerely, K. L. Grac se Site Vice President Byron Nuclear Power Station Attachment cc:
A B. Beach, Regional Administrator - Region til G. F. Di:k, Jr., B) Ton Project Manager - NRR Senior Resident inspector-Byron Oflice of Nuclear Safety-IDNS p197byltr\\970239. doc l
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Attachment for 125 volt de Battery Design Margin his attachment replaces Commonwealth Edison's response to Question 4 in the letter from K. L. Graesser (Comed) to NRC Document Control Desk transmitting a Response to e Request for Additional Information regarding the proposed replacement of Gould batteries with C&D Charter Power Systems battcries, dated August 7,1997 (BYRON 97-0180).
NBC_Qmitioni in sizing the C&D batteries, what aging factor is used? He licensee's submittal refers to a design margin of 10-15% Please provide the specific value used for the design margin.
H3IprLmponse, R
De aging factor used ic the si-ing calculations is 1.25, which corresponds to sizing the battery to meet the design function when the battery has 80% of the manufac*urer's rating.
The design margin used to size the C&D batteries is 5%, based on recent testing of the battery cells at the factory. IEEE Std. 485 1983 and the newly issued 1997 revision both recommend a design intgin of 10-15% and are normally used for new installations. Per section 6.2.2 of the standard, the 10 15% margin is for unforeseen load growth and Icss than optimum operating conditions.
11cwever, this replacement battery is for an existing station that has been in operation for about ten years. The expected load growth is small and is tracked and approved by calculation before any additions can be imple. ented Therefore, the use of a 5% design margin is considered acceptable.
The reason for the change is described below.
Calculation BYR97-204/BRW97-0384-E originally used a design margin of 10% This calculation used a vendor-supplied battery curve that is certified for construction. This characteristic cu.ve for the LCUN-33 battery cells was prepared based on similar ceils previous!y tested for other clients to end voltages different from the Byron requiremem. Dorough test data for the LCUN type cells (withoat copper inserts) was not available. Byron has a specific end soltage (1.86 volts per cell) requirement. Due to this specific end voltage requirement, the curve for 1.86 volts per cell was extrapolated from the different end voltage curves. The purchase specification required C&D to test the batteries at the one-minute rate and Gie two and one-half hour rate per the curn uid demonstrate a 100% eapacity battery. The two and one-half hour test corresponded to the curve. However, the cells did not meet the one-minute rate, which was needed to support our calculation results using a design margin of 10% (1.10 multiplier). The factc.,
testing at the one-minute rate appears to support a Byron design margin of between 5% and 10%
The characteristic curve has been revised by C&D per the factory test data on the Byron cells.
Based on this revised batter 3 curve, calculation BYR97-422, revision 0, uses a 1.05 design margin value in the sizing sheet for the battery with the worst-case load duty cycle and profile, which corresponds to a 5% design margin.
This revised curve is Comed-specific, and C&D feels that this curve represents worst-case performa: ice. Eight cells will be shipped to the manufacturer's test facility for further testing. Per discussions with C&D, the results of the additional testing will then be evaluated and the curve may be adjusted up. Calculation BYR97-204/BRW-0384-E will be revised upon receipt of a certified and approved for use curve from C&D, and will document any upward adjustment. C&D indicates that if there are changes to the wrve, other users of LCUN-type cells will be notified, as appropriate.
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