RS-15-251, Response to Request for Additional Information Follow-Up Clarification Regarding License Amendment Request for Diesel Generator Load Rejection Surveillance Requirement

Response to Request for Additional Information Follow-Up Clarification Regarding License Amendment Request for Diesel Generator Load Rejection Surveillance Requirement

ML15259A077
Person / Time
Site:	Byron, Braidwood
Issue date:	09/16/2015
From:	Gullott D Exelon Generation Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-15-251
Download: ML15259A077 (7)

Text

AdMMW 4300 Winfield Road Warrenville, IL 60555

• O"w- ExeLon Generation (.,

RS-1 5-25 1 10 CFR 50.90 September 16, 2015 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos. NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457 Byron Station, Units 1 and 2 Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455

Subject:

Response to Request for Additional Information Follow-Up Clarification Regarding License Amendment Request for Diesel Generator Load Rejection Surveillance Requirement

References:

1) Letter from David M. Gulloft (Exelon Generation Company, LLC) to U. S. Nuclear Regulatory Commission "License Amendment Request for Diesel Generator Load Rejection Surveillance Requirement," dated December 18, 2014

2) Letter from David M. Gullott (Exelon Generation Company, LLC) to U. S. Nuclear Regulatory Commission "Response to Request for Additional Information Regarding License Amendment Request for Diesel Generator Load Rejection Surveillance Requirement," dated June 25, 2015 In Reference 1, Exelon Generation Company, LLC, (EGG) requested an amendment to the Technical Specifications (TS) of Facility Operating License Nos. NPF-72 and NPF-77 for Braidwood Station, Units 1 and 2 and Facility Operating License Nos. NPF-37 and NPF-66 for Byron Station, Units 1 and 2. The proposed amendment would modify TS Surveillance Requirement (SR) 3.8.1.10 to increase the voltage limit for the diesel generator (DG) full load rejection test. Increasing the voltage limit for the full load rejection test resolves an existing non-conservative TS for the voltage that is maintained during a DG full load rejection test.

In Reference 2, EGG responded to the U. S. Nuclear Regulatory Commission (NRC) request for additional information regarding the Reference 1 submittal. The NRC later communicated that additional clarification was needed in response to Reference 2. On July 13, 2015, a teleconference took place between the NRC and EGG to clarify responses provided in the

U.S. Nuclear Regulatory Commission September 16, 2015 Page 2 Reference 2 letter. Attachment 1 documents the NRC question discussed during the July 13, 2015 teleconference along with EGO's response. Attachment 2 includes supporting information.

There are no regulatory commitments contained within this letter.

Should you have any questions concerning this letter, please contact Ms. Jessica Krejcie at (630) 657-2816.

Respectfully, David M. Gullott Manager Licensing Exelon Generation Company, LLC : Follow-Up Clarification Regarding License Amendment Request for Diesel Generator Load Rejection Surveillance Requirement : Westinghouse Product Bulletin 44-210 for Type PC-60 Potential Transformer cc: NRC Regional Administrator, Region Ill NRC Senior Resident Inspector, Braidwood Station NRC Senior Resident Inspector, Byron Station NRC Project Manager, NRR Braidwood and Byron Stations Illinois Emergency Management Agency Division of Nuclear Safety

ATTACHMENT Follow-Up Clarification Regarding License Amendment Request for Diesel Generator Load Rejection Surveillance Requirement

Attachment 1: Follow-Up Clarification Regarding License Amendment Request for Diesel Generator Load Rejection Surveillance Requirement Request Provide the upper limit on momentary (- 10 seconds) overvoltage for the Westinghouse Type PC-60 potential transformers (PTs).

Response

Based on discussions with the original manufacturer of the Type PC-60 PTs, Westinghouse Electric Corporation (Westinghouse), there is no published momentary overvoltage rating for these PTs. However, based upon review of the applicable industry standards for high potential testing of PTs, the high potential test voltage bounds the proposed maximum voltage limit for DG full load reject testing (i.e., 5600 Volts); therefore, the PTs would not be damaged by a momentary overvoltage transient during a DG full load reject.

The Type PC-60 PTs used in this application have a primary voltage rating of 4200 Volts and are classified as 5 kV Class PTs per the manufacturer. According to IEEE Standard C57.13-2008, "IEEE Standard Requirements for Instrument Transformers," instrument transformers that are 5 kV Class PTs are capable of withstanding a periodic in-service high potential test voltage of 12 kV for one minute. (Note that the current version of IEEE Standard 057.13 is the 2008 revision.)

This was determined based on review of industry standards. According to Section 8.8.2 of IEEE Standard C57.13-2008, the PTs are capable of withstanding a periodic in-service high potential test at a test voltage equal to 65% of the factory test voltage. Table 2 of IEEE Standard C57.13-2008 states that the factory test voltage is 19 kV for 5.0 kV Class transformers. Therefore, 0.65 x 19 kV = 12 kV for an in-service test. Section 8.8.3 of IEEE Standard C57.13-2008 states that the standard duration for an applied voltage test (i.e., high potential test) is 60 seconds at the maximum test voltage.

The 1968 revision of IEEE Standard C57.13 was also reviewed, since this revision was in effect when Westinghouse Product Bulletin 44-210 was revised and issued in June 1972 (Attachment 2). Based on a review of Table 1 and Sections 6.8.2 and 6.8.3 in IEEE Standard C57.13-19681 it was determined that the voltage and duration criteria for periodic in-service high potential tests of PTs are the same in both the 1968 and the 2008 revisions of IEEE Standard C57.13. The PTs at Byron and Braidwood Stations were purchased in the late 1970s.

Therefore, a comparison of the 1968 and 2008 revisions of IEEE Standard 057.13 bounds the manufacturing dates for the Byron and Braidwood PTs, and the specific revision of IEEE Standard 057.13 that was in effect when the PTs were manufactured is not critical with respect to the capability of the PT to withstand a voltage transient.

Thus, the high potential ac test voltage of 12 kV (12,000 Volts) for one minute bounds the maximum transient voltage of 5600 Volts that could occur during a DG full load reject and also the duration of the DG full load reject voltage transient, which would only last approximately one second. Therefore, the PTs would not be damaged by a peak voltage of 5600 Volts during a DG full load rejection.

ATTACHMENT Westinghouse Product Bulletin 44-210 for Type PC-60 Potential Transformer

Product Bulletin 44.210 Page 1 Calculation: 19-AD-2 Type PC-60 Potential Westinghouse Revision: 001 Transformer 0

Appendix B 2400 Volta Through 4800 Volts, Indoor Page 822 of 826 801W OIL, 60 Hertz Appftcatlon The Type PC-CO is an indoor potential transformer cast In epoxy and designed for metering and relaying applications.

Ratings ANSI metering accuracy (80 Hertz) 0.3 W. X. V and 1.2 Z burdens at 120 volts.

0.3 W, X burdens at 69.3 volts.

Construction Features Primary Terminals Primary leads terminsre with epoxy en-cased M inch deep 16-20 moose holes Connections we secured by means of a cup and bolt warmer. On fused unus. a clamp type terminal designed to accorn-madate No. 14 to No.4 wire is provided on the line and of each (use.

Core and Coil Assembly Features progressive winding with the high voltage coil wound directly over the low voltage coil. A new octagonal WESCORE design permits an overall size reduction to provide the smallest 8 1W Class unit available yet provide the highest thermal capacity 5 KV Class unit available.

Rimovabla Base The base is grounded to the core and coil assembly a nd is easily removed by loosen-ing two 16-20. 16 Inch long Screws.

Secondary Tunnlnsla and Cover Secondary brass terminal insane are 9.

inches deep with a 190-32 tapped hole.

Secondary connections are screw type.

Nameplate The aluminum nameplate incorporates lanced loops and a space lot customer identification is provided.

Selector Guide Type xv Rum I Paunsty Thermal Style Number I Style Number Pnme,vD I Thermal Sine Nunsef Bit. I Voltage Now (Not Fused) (Two Fuses) voltage I Rating (Va) (One Fuse On sn-c SVC Cvtiuiure; PC-11C 60 201 1 2400/4160Y 1000 70C I 2760*15002 2780A15G0t 2760A911001 1 2400141 60GY 1000 70 :710AC7001 361 I 4200/4200Y 1000 100 2780A11002 I 42004200GY 1000 IOC 710A5700 1 401 I 4$O0I40Y flOOD 100 1 2180A95603 2780A15003 I 4100!4900GV I 1000 10.0 2780*97003 (I, Si dwdsicondaivvoua(ieatrsl.o oruDavvoHege ) Fluxed for hn.-t.hns voltear. when connected i s 120 veIls except as sociliea rot IoClnDI.G. line-to-around. nounal saccnoaw voltage is All inarmei ratings at 120 von seconav. 613 volta June. 1972 Stinarseose PS asrec Mar: 19E E. 0. Cf2O$11D

Product Bulletin 44.210 Page 2 Type PC-60 Potential Calculation: 19-AD-2 Transformer Revision: 001 Appendix B 2400 Volts Through 4800 Volta, Indoor 60 ((V BIL 60 Hertz Page B23 of B26 Dimensions In Inches and Weights PC-60 Not Fused PC-60One FuIS PC-60 Two Fuses New Weight 32 lbs. Net Weight 34 lbs. Not Weight 3$ lbs.

'As 018.

'A. Dig. Hole, S%Latt.W Plots t%Lz4aW. t4i Din. Note I%Lx3IsW (2 Told) Slot (2 Total) o(2 Taal) $loI(2 TOW) (2 TOW) - 5101(2 ToW) .

MELM 2if! We Clamp TV" on, Ami

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Performance Curve 1008 Typical ratio correction factors and phase angle values olotied a*Pp for standard burdens, using the Farber Method ("The Analytical 1.004 -

• l0%PP and Graphical Determination of Complete Potential Transformer Characteristics" Settles, Farber, Conner. Al EE Transaction

)COOVA Paper 6).1248. October. 1960). 1.002

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• 30 20 10 0 +10 4.20 +30 Phase Angle In Minutes Fiji. for Type P040 Transformers Type Pus. I Fuse Fuse Rating S DIMBIt$IOlfl (Inches)

Type Styli von, ,nsonun Con Ov.rat Oivancs Saiwemi AInDIJaIt Amperes I Diameter L.ndi Cho Comm --

PC40 CLZ.PT I 077C4$2302 1 7200 50000 II  ; i.eoe 1%

Sea 00 31451. PL 31421 for fuse details.

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