ML20206B814
| ML20206B814 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 11/07/1988 |
| From: | Tucker H DUKE POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| TAC-68468, TAC-68469, TAC-68470, NUDOCS 8811160026 | |
| Download: ML20206B814 (4) | |
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na w f 0 has3]ISA lar PrenJat Dartoor. N C 28212 hadeor treJm t:en t TOILIT3 IDI DUKE POWER Noweber 7,1988 U.S. Nuclear Begulatory (benission Docmient Cbntrol Desk Mashington, DC 20555 Subjects Ooonee Nuclear Station Docket me. 50-269, -270, -287 hmquest flor Additicmal Infhrustion tac me. 68468, 68469, and 68470 Chntlesnen:
Pursuant to your letter of Septaber 20, 1988, find attached the subject information requested.
Should there be any questicna concerning this matter, ccotact S.E. Ielby at (704) 373-6233.
Very truly Sutrs,
/db<4 AL thi B. Tucker SFL/NN/420/mf Attactinent xc Mr. M.L. Ernst Acting Ngicmal Mministrator, Begico II U.S. Relear 41atory Otamission 101 Marietta St., NW, Suite 2900 Atlanta, Georgia 30323 Ms. Helen Pastis office of teclear acactor Ngulatien U.S. thelear mgulatory Chmission Washington, DC 20555 Mr. P.H. Skinner NBC Resident Inspector Oconee Relear Station y
IN ee11160026 esito7 ADOCK 0500 g FDR P
i Docurwnt Control Desk
!knemoor 4,1988 Request for Mditional Infornsticn Page 2 bxc R.J. Brackett (CNS)
K.S. Carksdy R.M. Dulin R.L. Dobnon R.C. I\\itrull E.M. Goddie R.M. Glover (OG)
P.F. Guill M. A. Itsghi G.W. !Lslinsn C.L. listlin S.A. Ibliand T. A. Iedford J.F. Ibrris N.A. Rutherford R.O. Sharpe (!US)
R.J. Quith OS-801.01 (18) l l
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Doctamt (bntrol Desk itwenber 7,1988 ATDateNr Duke Power Cimpany Oconee Nuclear Station Ikply to Request for Additimal Infannation TAC Nos. 68468, 68469, and 68470 me PRC is currently reviewing Licensee Evmt Report No. 269/87-05 dated February 1, 1988 concerning the potential tripping of the liigh Pressurw Injection (HPI) Punp Ntors on overcurre t for pump start-up during a 14CA/Icep scenario, ard had the following questions.
1.
LER 269/87-05 states that the original settings for the lei punp motor overturrent relays were below tM locked-retor themal change curve as appropriate. %e corrective action to prmnt the evet situation fr m occurring includes raising the overcurrent relay settings. Do the new settings now exceed the tMrmi limits of the motors? If not, how l
mch margin remains? Will motors' perfonnance/ life be adversely affected i
by the higher current and longer duration of the new relay setting?
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Answer l
me overcurrent relay settings for tM ITI Ptap Peters have already been raised.
%ese relays are now set at 6.0 seconds at 350% which exceed the locked-rotor thermal damage curve of the motors.
Although the new relay settings are higher than the motor thermi limits, a dynamic analysis perform! by Design Engineering indicates that tM starting currents and tires for the IFI Purps under normal auxiliary pwer system voltage conditima as well as extended started times under auxiliary power systm voltage and loading ecoditionn associated with IICA/IDOP emnt or a three unit ICOP ewnt r
are under the Iocked-rotor tMrnal dange curve of the mtors. 7herefore, the motors perfonnance/ life muld not be adversely affected by the higher sottings of the protectivo relayim.
2.
Since the overutrwnt relay settings for the ITI purp motors have been increased, what offeet does this haw on upstream cceponents (ovnrcurrent relays, breakers, etc.)? Ihve upstream breaker / relay settings been coordinated with the new cwercurrent settings?
Answer A calculation performed by Design thgineerim indicates that increasing the omrcurrmt relay sottings for tM ITI punp motors had no effect on breaker / relay coordination, i.e. tM ITI feeder breaker and upstream breakers (the switchgear main breaker and the CT4 to Stanty Dus breaker) maintain coordination.
3.
IDI 269/87-05 states that tM plant's design engineering staff identified by analysis tM situation concerning the }rtential tripping of these rotors en cverturzent. Provide a discussion of tM analysis for these I
loads and any other loads analyzed including details such as the electrical systm rerpense, bus witage, etc.
Docunent (bntrol Desk Novenber 7, 1988 Roquest for Mditional InforTaatico Page 2 Answer the analysis referenced in tM Int examires bus voltage and electrical systm responso durirn a loss of off-sito power.
It conservatimly assures all three Oconee units transferring to tM Standby Dus sinultaneously, and the standby i
bus being fed fr m reowee underground.
An Auxiliary Systm Design optimization program (ASDCP) was utilized to detemine the statie voltage dip on the motor teminain during motor starting.
mis ntatic analysis indicated that tM voltage level at the noter terminals during notor starting under the conservativ9 assurption described above was belcw 80% of rated voltage.
A dynanic analysis was then performd which takes into account the actual worst care loading characteristic and actual notor capability curwa cbtained frm rotor mnufacturers, mis dynmic analysis indicated tMt under starting voltage icvels resulting frm tM corrervative loading assunpticos described abcrve, notors would successfully accelerate to a running state. W e starting duration; however, wre extended. A caparison Lotuten the extended durations and current levels, and tk protective relayitn setting irdicated that, except for tN HPI purps, no other rotor wuld be tripped due to the voltaje lem1.
'ihereforn, as a remit of this amlysis, tM hPI purp protective relaying rettings wre rained to alicw motor starting under the condition described alove.
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