ML20154E841
| ML20154E841 | |
| Person / Time | |
|---|---|
| Site: | Mcguire, Catawba, McGuire, 05000000 |
| Issue date: | 09/09/1988 |
| From: | Tucker H DUKE POWER CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NUDOCS 8809190153 | |
| Download: ML20154E841 (7) | |
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Duko Ibuer Compny llu H h w PO Box 33199 hce Pn sibnt Charlotte, N C 28242 M' kat haducto (704)1?]lill DUKEPOWER September 9, 1988 U.S. Nuclear Regulatory Commission Attention: Document Control Deuk Washington, DC 20555
Subject:
Catawba Nuclear Station Donat Nos. 50-413 and 50-414 McGuire Nuclear Station Docket Nos. 50-369 and 50-370 Centlement By letter dated June 1, 1988. Duke Power identified to NRC two issues relative the ATWS/AMSAC design modification for McGuire and Catawba.
These issues 6,,
were discussse Juring a conference call on July 13, 1988.
In follevup to these licensing activities, attached please find a response from Westinghouse.
Please note that reference 4 in the Westinghouse letter contains the same information as Duke letter to the NRC dated June 1, 1988.
With this letter. Duke continues en conclude that the McGuire/Catauba ATVS/AMSAC design is acceptable.
Very truly yours, 4
Hal B. Tucker RLC/400/maf Attachment act w/ attachment Nr. Darl Hood Office of Nuclear Reactor Regulations U.S. Nuclear Regulatory Commission Washington, DC 20555 Mr. U.T. Orders NRC Resident Inspector McGuire Nuclear Station Od[h Dr. J. Nelson Grace, Regional Administrator
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U.S. Nuclear Regulatory Commission I
t Region II 101 Marietta Street, NV, Suite 2900
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Atlanta, Georgia 30323 8809190153 800909 PDR ADOCK 05000369
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Electric Corporation Bcd55 Pascure Frwer a 15230 0355 Mr. T. C. McNeekin, Chief Engineer DAP 88-620 Electrical Division August 25, 1988 Duke Power Company P0 Sox 33189 Ref: MS-SAT TA-II 88-316 Charlotte, NC 28242 DAP 88 614 CH 15028 Attention: Mr. W. E. O'Neal Duke Power Company McG'Jire and Catawba Nuclear Station ATWS Mitica*. ion System Actuation Circuitry (AMSAC)
ResDonse Dear Mr. Wyket i
The referenced letter provided responses to Duke Power Company AMSAC questions and were marked Proprietary Class 2.
After receiving the responses, Mr. 6. T. Duke of Duke Power requested that non proprietary responses be provided.
After reviewing the information in the referenced letter, the response to Question 3 was slightly revised and the proprietary classification removed. Attached to this letter are the non proprietary responses, if you have any questions please contact R. L. Haessler at 412 374 4714.
Sincerely.
WESTINGHOUSE ELECTRIC CORPORATION f$N$b
- 5. 5. Kilborn, Manager Duke Power Project cc W. E. O'Neal IL 1A T. B. Duke IL 1A J. M. Roth IL 1A T. R. Puryear IL 1A
- 5. E. Lawson IL 0534e
ATIACHMDTI 'Io NS-SAT-CA-II-88-316 ouestion 1:
'Ibe first issue cenaarns the mmber c4 auxiliary feedwater (AFW) putrps required once an AINS event is detected. Duka Power Ccepany's specific AMSAC design for the Catawba and itOuire Nuclear Stations currently requires that two notor driven auxiliary feedwater (AFW) parps start.
'Ihis Duka specific AMSAC design requizment is based upon normal plant reaperine to loss of both main feedwater pumps. During previous talephone
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j oonversations with Gary Ament of Westingbouse's Nuclear Safety Department, it was stata$ that while the bcundary of the calculation is bassi on a I
flow almost double Daka Power's motor driven capacity, the sensitivity to lower flow ratas is very low. Based on the low sensitivity of an AINS event to lower levels of AW flow rates, Duka Power ccrpany concluded that j
the present AMSAC design is acceptable and that additional A W capaci @
l was not required for Dike Power Ctrpany's specific APEAC design. Tb j
I support this conclusion, Duke Power o:rpany requests a vdtten response I
i frcra Westinghouse evaluatirg this conclusion.
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Pasponse 1:
'Ihe Westinghouse generic AINS analyses (Paference 1) conservatively m:x$el a Westirghause 4 loop plant with Madel 51 staa:n generators.
In these analyses the initiation of full AN capability at 60 seconds is modeled.
'Iha AW ficw rata used in the AINS analyses is 1760 gpn which con +4s to 2 retor driven AW purps plus the turbina driven AW purp.
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ATIActOfr 'IO }G-SAT-TA-II-88-316 For the most limitirg AIHS events, e.g., Irss of Load / 'Iurbine Trip ard Ioss of Ptormal ree &atar, sensitivities to various AIW relstad parameters are provided in Reference 1.
Included in these sensitivities are; 1) one-half A!W flow (e.g., 880 gp, epivalent to having mly 2 motor driven AfW purps or the turbine driven A7W purp), 2) i lot AFW f)ow rate, and 3)
AIW initiation delay (fzm 60 socords to 120 sacands into the transient).
For thase limiting AIWS events, the largest sensitivity to havirg cne-half f
AfW flow is a peak reactor coolant systan pressure increase of 64 psi.
Relative to the 3200 psig allowable peak reactor coolant systan for AIWS events, this increase is very sw.11. With the inclusien of this additicnal pressure increase to the peak RCS pressures given in the generic analysis results presented in Reference 1, the allow 3hle peak RCS pressure limit of 3200 psig is still met.
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'Ibe final AINS rule for Westinghcuse plants requires the installation of REAC. The generic MEAC designs devaleped for the Westirghause Cuners Group (WoG) and presented in the Reference 2 stata "A turbine trip ard start-up of all auxiliary feedwater prps will occur upon reonipt of an NEAC signal". No explicit definition of AFW flow rate is pttvidsd in Refertros 2 since AIV flow 13tas vary among Westinghouse plants.
4 Westirghause has ticognized the need for flexibility in plant specific NEAC design requizwents for AIV flow. Consequently, Westinghouse han considered the impact of diffarent (reduced) AIV flow capability in the joint WoG/ Westinghouse ADE Rule Administration prugram (Reference 3) currut.ly in prtqtiss. In the AINS Rule Administration p m defined in Referunos 3, the capability of a-aing ard, if nanannary, accounting for less than full AfW flow is presented. Upon final issuarce of the ADS Rule Aininstraticn program report, Westirghause rik u+e-ds that tuka Powr W arploy this process to detamine the impact of their specific M EAC design requirenants relata3 to ATW flow.
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ATDate2fr 70 NS-SAT-G-II-88-316 ouestion 2:
After the original MEAC design was ccepleted and apprwed, plant cperating prewes at McGuire were slightly modified to allow operation above 50 panent power with the Feedwatar contzel-Bypass Valves (N) fully cpen. The new cymrating prews was analyzed and fcund to have flowpath arra%-.ats which are very similar to those associated with the feedwater arrarw J.s of the D5 model steam generators. The cerclusion was reached that because of this similarity flowpath blockage can only occur if both the Feedwater Centrol Valve (ftV) and N aru closed or the Feedwater isolation Valve (FIV) is closed. Westinghouse is asked to evaluate this design change.
I Response 2:
Westirghouse has rwiewed the logic diagrams and description of the NEAC design prwided in Reference 4.
The conclusion of the rwiew is that the logic modification shom for the Mntire units will provide at laut the level of AINS protection as the WCG pimp ard valve status Icgic in WCAP-10858P-A, Pav.1, "NGAC Generic Design Package" (Peterance 2).
It is apprtpriate to monitor the valve position of the PCBVs and the FtVs with an "And" logic gata ard couple that with the FIV position in an "or" gata for the N EAC actuation on valve position. This conclusion is based cm the assunption that the flow through the FCBV2 will be sufficient should the FtVs fail close (as stated in Befarance 4).
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ATDONDE 10 NS-SAT-TA-II-88-316 ouestion 3:
In the July 18, 1988 conference call with B. T. h, it was also requested that Wer;tirghouse ocurent on the turbine power interlock logic for the Pt:ouire units, partio11arly the 120 second time delay.
Response 3 he Moouizu AMSAC logic as presented in Reference 4 will maintain the turbine power pemissive for 120 seconds after turbine power is below 40%.
The time delay in the feedvatar valve status porticn of the circuit is 30 seconds. Warufore, the 120 secords is a sufficient length of time to maintain the turbine power permissive. Note that the nnge for the prp i
and valve logic turbine power pemissive delay, in Rev. O of WCAP-l I
I 10858P-A, was 90 to 180 socorsis (refer to WCAP Fig. 3-4). The rarge was 1
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l increased to 180 to 420 seconds in Pav.1 of WCAP-10858P-A (Ref. 2) l because of the tuvised time delay ad$ed to the design. Because tuke has l
not incorporated the revised time delay into the Nouire AMSAC design, the turbine pw pemissive delay does not need to be increased as it was Ref. 2.
1 The tutbine power pemissive for the Catawba units does not include the 120 second delay. Rus, the valve position NEAC actuation will be ammi below 40% power until the cperater takes action to renove the turbine power pemissive. After reviewing the logic diagrans, Westinghouse concludes that the Rouire turbine power pemissive logic oculd be a@ lied to the Catawba units.
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ATDO85Nr 70 NS-SAT 'IA-II-8C-316 Rafarences
- 1) Isttar NS 'IMA-2182, Anderscm, T. M., (Westi:sh:use Elm.tric Corporation) to Hanauer, S. H. (USNPC), "AM Sulaittal", hr 30, 1979.
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- 2) Adler, M. R., "MEAC Genaric Desigr.) Package," WCAP-10858P-A. Rev.1, July, 1987.
- 3) Westinghouse Preliminary Report, "AM Rule Administraticn Process",
ESSD/WOG-88-106, June 14,1988.
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Duka Power otrpany letter of May 23, 1988, fran J. E. Thcuss to i
a S. S. FJ.lbom.
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