ML17276B493

Responds to NRC Concerns Re Load Shedding Feature Raised During 820512-13 Site Visit.One Oversize Drawing Encl. Aperture Card Is Available in PDR

ML17276B493
Person / Time
Site:	Columbia
Issue date:	06/04/1982
From:	Bouchey G WASHINGTON PUBLIC POWER SUPPLY SYSTEM
To:	Schwencer A Office of Nuclear Reactor Regulation
Shared Package
ML17276B495	List: ML17276B493 ML17276B496
References
GO2-82-506, NUDOCS 8206140258
Download: ML17276B493 (6)

Text

REGULA' INFORMATION DISTRIBUTIO ~ SYSTFM (RIDS)

AOCESSION NBR:8206100258 DOC,DATE: 82/06/04 NOTARIZED: NO DOCKET FAOIL:50-397 NPPSS Nuclear Pr ojectg Unit 2~ Hashington!Public Powe 05000397

'AUTH'AME AUTHOR AFFILIATION BOUCHEY<G,D, Washington Public Power Supply System 1RFJCIP,NAME RECIPIENT AFFILIATION 9CHhENCERgA ~ Licensing Branch 2

SUBJECT:

Responds to NRC concerns re load shedding feature raised during 820512 13 ssite visit. One oversize .dr awing encl.

Aperture cand is available in PDR, DISTRIBUTION CODE: 800IS COPIES 'RECEIVED:L'TR, ENCL SIZE:

PSAB/FSAR AMDTS and "Related ~Correspondence 2k'ITLE:

@~A RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LT!TR ENCL A/D LICENSNG 0 LIC BR 02 BC 1 0 LIC BR 02 LA 1 0 AULUCKiR~ 01 1 1 INT>ERKAL: ELD/HOS2 1 0 IE FILE 1 1 IE/DEP EPOS 35 1 1 IE/DEP/EPLB 36 3 3 MPA 1 0 NRR/DE/CEB 11 1 1 NRR/DE/EQB 13 '3 '3 NRR/DE/GB 28 2 2 NRR/DE/HGEB 30 2 2 NRR/DE/MEB 18 1 1 NRR/DE/MTEB 17 1 1 NRR/DE/QAB 21 1 1 NRR/DE/SAB 2O 1 1 NRR/DE/SEB 25 1 1 NRR/DHFS/HFEBQO 1 1 NRR/DHFS/LQB 32 1 1 NRR/DHFS/OL'B 30 1 1, NRR/DHFS/PTRB20 1 1 NRR/DS I/AEB 26 1 NRR/DS I/ASB 27 1 1 NRR/DS I/CPB 10 1 1 NRR/DSI/CS8 09 1 1 NRR/DS I/ET'SB 12 1 1 NRR/DS I/ICSB 16 1 1 NRR/DS I/PSB 19 1 1 NRR/DSI/RAB 22 1 1 NRR SB 23 1 1 NRR/DST/LGB 33 1 1 REG FIL 04 1 RGN5 2 2 EXTERNAL': ACRS 41 16 16 BNL(AMDTS ONLY-)

FEMA-REP DIV '39 1 1 LPDR 03 NRC .PDR 02 1 1 NSIC 05 NTIS 1 1 TOTAL NUMBER OF COPIES REQUIRED: LTTR 63 ENCL .58

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820b140258 820604 PDR ADOCK '05000397 A PDR Washington Public Power Supply System P.O. Box 968 30006eorge Washington Way Richland, Washington 99352 (509) 372-5000 June 4, 1982 G02-82-506 Docket No. 50-397 Mr. A. Schwencer, Chief Licensing Branch No. 2 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

NUCLEAR PROJECT NO. 2 RESPONSE TO CONCERNS: SANG RHOW SITE VISIT This letter addresses concerns expressed on questions which were raised as a result of a site visit by Sang Rhow, PSB Electrical Reviewer, May 12-13, 1982. , AE Drawing E517, Sheet 3, shows the WNP-2 load shedding feature.

Contacts 27-7, 1 and 2, located at E7 and E8 on the drawing are those controlled by the primary undervoltage relays set at 69K of nominal bus voltage. When a 5M-7 bus undervoltage condition exists these contacts will close. This energizes relays 27X-7 and 6Z-7.

Contacts from relay 27X-7 start diesel generator 1A and disable/enable the se-quencing circuit for the LPCS and RHR pumps. Note that the disable/enable con-tacts from 27X-7 will open during bus undervoltage and close when voltage is reestablished.

Contacts from 6Z-7, after a two second time delay, close to energize relays 62X-7, 62X1-7, 62-1-7 and 62-2-7. Relays 62X-7 and 62X1-7 are responsible for shedding the loads on SM-7. The relay contacts and their functions (loads shed) are identified below the circuit diagram on E517, Sheet 3.

This relay load shedding scheme is duplicated in the redundant division II.

This information confirms previously supplied information in a letter to the NRC from the Supply System, dated March 18, 1982, as well as the FSAR write-up on load shedding. Load shedding is initiated whenever the critical buses SM-7 or SM-8 experience an undervoltage condition of 69K or less of nominal bus voltage.

Load sequencing is initiated by two contacts. The first closes on a LOCA signal. The second is the power available on the bus enable contact previously described off 27X-7.

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A. Schwencer Page Two June 4, 1982 G02-82-506 A question arose concerning the K21 contact in the trip circuit of DG1-7 and DG2-8. These contacts are controlled by a standard auxiliary relay energized by either of two pushbuttons. One is located in the Control Room and one is located locally. These pushbuttons are used to shutdown the diesels during normal shutdown as well as an emergency situation.

If either of these pushbuttons are inadvertently pushed during diesel operation under a loss of offsite power or LOCA condition, the diesel will immediately restart due to enabling circuitry in the start circuit of the diesel.

guestions were raised about the locations of some CT's and fault levels asso-ciated with certain buses.

The instantaneous overcurrent relays (50) in the trip circuits of breakers 7-DG1 and 8-DG2 have their CT's electrically located between breakers 7-DGl and DG1-7, 8-DG2 and DG2-8, respectively. These CT's are physically located in switchgears SH-7 and SH-8. Fault current on the primary side is calculated at 9494 amps.

The time overcurrent relays (51) in the trip circuit of breakers 7-1 and 8-3 have their CT's electrically located immediately upstream of breakers 7-1 and 8-3, respectively. These relays are physically located in switchgears SM-7 and SH-8. The fault current on SM-7 has been calculated at 65,900 amperes.

Paragraph 2 on page 8.3-lb has been modified as requested. The new paragraph is as follows:

During test mode operation, an expanded set of disabling conditions are permit-ted to prevent unit start or initiate unit trip as indicated in 8.3.1.1.8.1.8.

However, in the event of receipt of emergency start signals while the units are in the test mode, those signals not permitted to disable the unit in the standby mode are eliminated from the trip circuitry. The diesel generator then remains in parallel with the offsite source until shutdown by operator action.

Very truly yours, G. D. Bouchey Deputy Director, Safety and Security TLH/jca Attachment cc: R Auluck NRC WS Chin BPA R Feil NRC Site S Rhow NRC

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