ML20080H567

Forwards Response to NRC 831121 Request for Info Re Use of Voltage Regulators.Tech Spec Change Request 88 Re Second Level (Degraded Grid) Undervoltage Relays Clarified

ML20080H567
Person / Time
Site:	Oyster Creek
Issue date:	02/09/1984
From:	Fiedler P GENERAL PUBLIC UTILITIES CORP.
To:	Crutchfield D Office of Nuclear Reactor Regulation
References
NUDOCS 8402140244
Download: ML20080H567 (9)

Text

s. .

GPU Nuclear Corporation

. U sp y,t ev Je sey07054 201 263-6500 TELEX 136-482 Writer's Direct Dial Number:

February 9,1984 Mr. Dennis !!. Crutchfield, Chief Operating Reactors Branch #5 Division of Licensing U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Oyster Creek Nuclear Generating Station Docket No. 50-219 Technical Specification Change Request No. 88 Response to NRC Request for Information This letter transmits the information requested by members of your staff during a November 21, 1983 conference call regarding the use of volt-age regulators at Oyster Creek and the clarification of the Technical 0pecifications. This information presents a more detailed explanation of our position which was stated previously in our October 18, 1982 letter on the same subject.

The enclosed f9 format;on will facilitate your review and final approval of Technical Specification Change Request No. 88 with respect to t1e second level (degraded grid) undervoltage relays. The portion of the artviously submitted change request pertaining to the batteries had already

)een approved as Amendinent No. 55 dated August 13, 1981.

If you have any questions regarding the enclosure, please call Mr. James Knubel at (201) 299-2264.

Very truly yours, 1 )

. . edler Vice President / Director Oyster Creek PFW: dis:0107e Enclosures cc: Administrator Region I U.S. Nuclear Regulatory Ccamission 631 Park Avenue King of Prussia, PA 19406 8402140244 840209 PDR ADOCK 05000219 NRC Resident Inspector P PDR Oyster Creek Nuclear Generating Station Forked River, NJ 08731 GPU Nuclear Corporation is a subsidiary of the General Pubhc Utilities Corporation I

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RESPONSE TO NRC REQUEST FOR INFORMATION i l

I. Conservatism of Analysis A. Crld Voltage Predictions The grid voltage of 214.8 KV was predicted by an analysis which included the following assumptions:

1. Oyster Creek generator outage.

2. Southern NJ generation of 553 HW out of a possible 805 MW which has been analyzed and the probability of this level of generation is 0.26. This is independent of the other as-sumptions.

3. The highly improbable loss of a major 230 KV tie line to the west referred to as the Windsor-Lawrence 230 KV Ifne.

The grid voltage level of 214.8 KV does not include nor take credit for the following improvements:

1. Installed voltage regulators (Automatic + 10% capability).

2. Increasing Southern Area generation levels.

3. Operation of Load Tap Changer controls on the 230 KV-34.5 KV transformers at Oyster Creek which improves the 34.5 KV voltage profile. This operation is performed by personnel in the Oyster Creek control room.

4 Availability of the 34.5 KV capacitors to improve voltsge levels. This action is also performed by control room operators.

5. Ability to decrease Southern Area loads on the distribution system.

B. Burns and Roe Voltage Analysis The voltage analysis performed by Burns and Roe assumed a grid voltage level of 214.8 KV as the minimum voltage on the 230 KV system. The analysis did not take any credit for the voltage regulators, capacitors, or load tap changes on the 230. KV -

34.5 KV transformers. In addition, there were two other fairly i

conservative assumptions utilized in their analysis.

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e e r

1. Bus loading was conservatively assumed to include all safety loads and normal plant loads including all Reactor Feed Pumps running. It is highly unlikely that all of these loads would be running at the same time.

2 Actual setting of the new second level (degraded grid) voltage relays is 3671 volts but the analysis included the 1% tolerance of the device and used 3635 volts as the minimum allowable 4160 volt bus voltage which will insure that all safety related motor starters will have enough voltage to pick up at the 460 volt level.

C. Outcome of Analysis Utilizing conservative assumptions and an improbable grid voltage level, the only questionable plant equipment loads were the fuel pool filter pmrps and the CRD feed pumps. All other plant safety loads were found to have acceptable voltage levels.

The fuel pool filter pumps are rated at 460 volts. At (-)10% , a minimum of 414 volts would be required to safely run these pumps. The analysis computed a minimum voltage of 398 volts at the setpoint of the second level voltage relays. This voltage difference would be compensated for by automatic operation of the voltage regulators or by manual operation of capacitors and/or load tap changers on the 230 KV-34.5 KV transformers.

It was also stated in previous submittals that the fuel Pool Filter pumps are not considered to be important to Reactor shutdown or cooldown and are not required to be running con-tinuously. Therefore, these pumps could be off for extended periods of time and running only when voltage conditions permit.

Burns and Roe recommended that the overload heaters be replaced for the Fuel Fool Filter pumps in order to comply with the NEC requirements for overcurrent protection. This replacement was accomplished in 1981 and the new overload heaters protect the pumps f rom thermal damage by providing overcurrent protection as well as some measure of undervoltage protection.

The CRD feed pumps are rated at 480 volts. At (-)l0% , the mini-mum required voltage is 432 volts. The analysis computed a voltage level of 402 volts at the setpoint of the undervoltage (second level) relays. This voltage difference would be com-pensated by the automatic operation of the voltage regulators or the manual operation of the LTC's on the 230 KV-34.5 KV trans-formers and/or the 34.5 KV capacitors.

Burns and Roe recommended that the motors or motor windings for the CRD feed pumps be replaced with those rated at 440 volts.

This recommendation was not followed and the motors remain rated at '80 volts.

The CRD feed pumps are Important for plant operation but are not needed during an accident and have not been taken credit for in any accident analysis. Voltage conditions during plant opera-tion have been analyzed and no adverse effects on the CRD feed pumps were found (refer to our submittal of April 30, 1981).

The Burns and Roe analysis computed a voltage level of 402 volts at the terminals of the CRD feed pumps during an accident condition without any credit for voltage regulators, capacitors, or LTC's. But, as stated previously, the CRD feed pumps are not needed during the accident scenario assumed in their analysis.

D. Conclusion Based on the above informattan, it is our position that the voltage regulators provide a useful service but do not perform a safety function and are not safety grade equipment. They are merely an added feature which improves voltage levels in much the same manner as the capacitors and the LIC's. They should not, in our view, have to be included in the Technical Speci-fications as an L.C.O.

II. Overvoltage Conditions Under minimum load conditions and with the maximum predicted grid voltage the computed maximum MCC voltage is 498 volts. Thus, even I taking credit for some voltage drop in the feeder cables, does not f guarantee that the 440 volt motors' maximum voltage limit of 484 volts is not exceeded.

l 1

The difference in the computed maximum voltage level and the allowable maximum rating is compensated for automatically by the operation of the voltage regulators. There are, however, other actions that can be taken to ensure that this maximum limit is not exceeded. First, operators could maintain sufficient load on the Startup transformers to prevent this limit f rom being exceeded. And second, operators could change the taps on the 230 KV-34.5 KV trans-formers by utilizing the LTC controls.

The control room operators are kept aware of any overvoltage condi-tions by means of overvoltage relays which alarm in the control room but do not perform any tripping function. These relays were in-stalled at the same time as the new second level (degraded grid) undervoltage relays and they alert the operators to the overvoltage condition so that the above actions can be taken to bring the voltage down to acceptable levels.

_-m_._.- . _ . _

III. 460 Volt Motor Starter Ratings As stated in previous submittals the following MCC starter voltage criteria apply:

Normal Voltage 460 VAC )

Drop out Voltage 60% of Normal (276 V)

Pickup Voltage 85% of Normal (391 V)

The naximun voltage drop in control wiring for any safety related starter circuit is 3 volts. Since the motor starters' control transformers have a 4:1 ratio,12 volts on the primary of these transformers in required to account for this control wiring voltage drop. Thus the minimum voltage on the primary side of the control transformers which will guarantee all starters pick up is 403 volts (391 volts + 12 volts).

Therefore, the Burns and Roe Analysis demonstrates that at the undervoltage relay trip set;nint (including device tolerance) at least 403 volts is available at the substation /MCC levels to gusrantee all starters pick up.

IV. LOO For Safety Bus Tie Breakers Reference Technical Specification Change Request No. 88 which was submitted August 11, 1980, on page 3.7-1 para. 3.7.A.5 Bus tie breaker ED and EC is in the open position. Copy of this page is attached. For some reason, this change was not included in Amendment No. 55 dated August 13, 1981. Also, attached to this submittal is a simplified one line diagram of the OCNGS electrical distribution system which shows breakers EC and ED. This diagram is actually Figure 1 from the August 1981, EG&G report on the Adequacy of Station Electric Distribution System Voltages Oyster Creek Nuclear Power Station.

V. . Technical Spreifications Clarifications Copies of the following revised Technical Specifications are provided to clarify the requested changes in light of other changes which have been incorporated during this review cycle.

Page 4.1-6a (reference Amendment 63 October 15, 1982)

Page 4.7-1 (reference Amendments 55 Aug. 13, 1981 and 60 Feb. 3,1982)

Page 4.7-la with March 19, 1981 cover memo Page 3.7-3 (reference Amendment 60 February 3,1982)

Page 4.7-2 (typo and Amendment 60 Feb. 3,1982)

3.7-1

, 3.7 . AUXILIARY ELECT ICAL POWER Aop l icab i l i ty: Applies to the operating status. of the auxilary electrical power supply.

Ob jtetive: To assure tne operability of the auxiliary eiectrical power supply.

S neci f ication: A. Tne reactor shal l not be made criticut unless all of the following requirements are satisfied:

. 1. Tne following buses or panel s energized.

a. 4160 volt buses IC and ID in the turbine building switchgear room.

b. 460 voit buses IA2, 182, IA21, 1821 vital MCC 1A2 and 182 in the reactor building switchgear room: l A3 and 183 at the intake structure; 1 A21 A , IB21 A , l A218, and 1821B and v ital MCC 1 A32 on 23 '6" elevation in 1he reactor building; 1A24 and 1824 at the stack.

c. 208/120 volt panels 3, 4, 4A, 48, 4C and VACP-1 in ,the reactor building switchgear room,

o. 120 voit protection panel 1 and 2 in the cable room.

e.125 volt DC distribution centers C and B, and panel 0, Panel DC-F, isolation valve motor control center DC-1 and 125V DC motor control center DC-2.-

f . 24 volt D.C. power panel s A and B in the cable room.

2. One 230 KV line is fully operational and

, switch gear 'and botn startup tran,stormers are energized to carry power to the station

, 4160 voit AC buses and carry power to or away fecm the plant.

3. An additional source of power consisting of one of the following is in service connected to f eed the appropriate plant 416Q V bus or buses:

a. A second 230 KV line fully operational,

b. One 34.5 KV line fully operational .

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4. Tne statica batteries B and C are available f or normal service and a battery charger is in service for each battery.

5. Eas tie breakes ED and EC are in the - --

open positico.

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n- - - -  ;- ga Figure 1. Oyster Creek Nuclear Power Station electrical distribution . 3 system single-line diagr'am. , .

                                                                                                                                        '3                -

                       ~Inntrument Chrnn21          -Chrck ' Calibrate       Test         Remarks (Applies to fest.& Calibretien)

19. Manual Scram. Buttons - - NA NA' 1/3 mo. .

L20. :High Temperature Main NA Each Refuel- Each refuel- Using heat source box Steamline Tunnel ing outage ing cutage

              '21. ISRM'                        '*        *

• Using built-in calibration equipment

    ,- ,      - 22.: Isolation Condenser High        NA      1/3'mo.         1/3 mo.      By application of test pressure Flow /kP (Steam and Water)
              - 23. - Turbine Trip ' Scram           NA                      Every-3 months

24. Generator Load Rejection ' NA Every Every Scram 3 months 3 months

25. Recirculation Lo'op Flow .NA. Each Refuel- NA By application of test pressuce ing Outage

              '26.    ' Low Reactor Pressure        NA       Eve ry          Every        By application of test pressure Core Sp ray - Valve '                 3 months        3 months Permissive;
             ' 2 7.  . Scram Discharge Volume

.(Rod Block) a) . Water ^1evel:high NA Each Refuel- Every 3 By varying level in switch column ing Outage months Lb)', Scram trip bypass'

                                                   -NA      NA               Each refuel-Ing outage

28. : Loss of. Power

a) : 4.16 KV Emergency -Daily 1/18 mos. 1/mo.

Bus Undervoltage

                            .(Loss of' voltage)-

b).. 4.16 KV Emergency Daily 1/18 mos. 1/mo. , Bus Undervoltage r (Degraded Voltage)- & u

• Calibrate prior to startup and normal shutdown and thereaf ter check 1/s and test 1/wk until no longer required.

Amendment No. 63

l 4.7-1 4.7 Auxti tary F.loctrical P >wer . Appitcability: Applies to surveL11ance requirements of the auxiliary electrical supply. Objective: To verify the availability of the a'uxiliary electrical supply. Specification: A. Diesel Generator

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1. Each d Lesel generator shall be started and loaded to not less than 20% rated power every two weeks.

2. Each diesel generator shall be automatically activated (by simulating a loss of offsite power in conjunction with a safety injection actuation test signal) . and functionally tested during. each refueling outage by:

a. Verifying de-energization of the emergency busses and load shedding from the emergency busses,

b. Verifying the diesel starts from ambient conditions on the auto start signal, energizes the emergency busses with per-manently connected loads, energizes the

                                              -auto-connected . emergency loads through the load sequence timers listed in fable 3.1.1 and operates for 2: 5 minutes while its generator is loaded with the emer-gency loads.

c. Ver!fying. that on diesel generator trip,

                                             - the loads are shed from the emergency husses and the diesel restarts on the auto-start. signal, the emergency . busses are energized with permanently connected loads, the auto-connected emergency loads are energized through the load sequences and the diesel cperates for 2" 5 minutes while its generator is loaded with the emergency ' loads.

3. Each diesel generator shall be given a thorough. Inspection at least once per 18 months during. shutdown.

4. The diesel generators' fuel supply shall be checked following the above tests.

5. The diesel generators' starting batteries shall be tested'and monitored the same as the station _ batteries, Specification 4.7.B.

A'mendment No. 60

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