IR 05000277/1989013

Insp Repts 50-277/89-13 & 50-278/89-13 on 890405-07.No Violations or Deviations Noted.Major Areas Inspected: Licensee Action on Previously Noted Insp Findings in Electrical Area

ML20247K960
Person / Time
Site:	Peach Bottom
Issue date:	05/10/1989
From:	Anderson C, Kosky T, Mathews R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20247K925	List: IR 05000277/1989013 ML20247K919
References
50-277-89-13, 50-278-89-13, NUDOCS 8906020058
Download: ML20247K960 (23)

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'y U.S. NUCLEAR REGULATORY COMMISSION

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REGION I

L50-277/89-13

" - Report Nos. 150-278/89-13

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50-277.:

Docket'No L DPR244~

License ; Nos . - DPR-56

~ Licensee: Philadelphia-Electric Company

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, , ~P.O. Box 752 .. .

Philadelphia, PA 19101

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.: Facility Name: Peach Bottom Atomic Power Station Units 2 and 3 Inspection'At: Corporate' Office in Philadelphia, Pennsylvania

. Inspection' Conducted: LApril-5-7 and-13, 1989-

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. Inspectors:

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.f LThomas .Roshy, Sr. - Reactor Engineer date b 1,tc h W o lo-51 Roy Math ~ew ctor Engineer dat '

Approved'by: -!/ J f

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C. J./ Anderson, Chief, Plant Systems Section _ 3 date

. Inspection Summary: .An inspection was conducted on April 5-7, and'13, 1989 at PECo Corporate Offices to review the licensee's action on previously identified inspection- findings (Unit 2 restart . issues) in the electrical area. . Also included in this report is a summary of the licensee's presentation of Unit 2 restart-issues on April 10, 1989 at the NRC Region I offic Results: No violations or deviations were identified. Six unresolved items were closed. One item on Diesel Generator loading remained unresolved at the

' end of the inspection. The preliminary analyses for voltage adequacy of dc  !'

equipment and capacity margin for batteries, adequately addressed Unit 2

. restart concerns. However, these items and the evaluation and control of i

emergency diesel generator loads remain as restart issues for Unit t

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! o 1.0 Persons Contacted

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1.1 - Philadelphia Electric Company (PECo)

E R. Abavy, Electrical Engineer ri

• I. Baxter, QA, Audits Section

+ ** *W. Boyer, Section Manager, Electrical Services i * **

W. J. Brady, Engineer, Nuclear Engineering Design

T, J. Cabrey, Control. Systems Engineer, Nuclear Engineering Design

• A. R..Diederich, Manager, Projects Division

+ *C. Fletcher, Supervising Engineer

R.'R. Hess, Valve. Application Engineer, Nuclear Engineering Design

+ ** *M. C. Kray, Licensing Engineer

+ ** *R. 'J. Lees,. Manager, Electrical Engineering-

T. S. Neckowicz, Engineer, Nuclear Engineering Design

.1.2' Gilbert Commonwealth

' -+ ** *A. Hartman, Project Electrical Engineer

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'+ ** 'D.. K. Kelly,- Consulting Electrical Engineer

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1.3 -Bechtel Power Corporation P.-Kuhn, Engineering' Specialist U.S. Nuclear Regulatory Commission

• • C..J. Anderson, Chief, Plant Systems Section

• • - J. Lara, Reactor Engineer, Plant Systems Section

• • J. Linville, Chief, Project Section 2A

• • T. Martin, Director, Division of Reactor Safety

• • *E. Wenzinger, Chief, Reactor Project Branch ** H. Williams, Project Engineer, Section 2A

J. Strosnider, Acting Chief, Engineering Branch

• Present at the exit meeting on April 7, 1989.

• • Present at the meeting held in NRC, RI on April 10, 198 +Present at the exit meeting on April 13, 1989.

2.0 Purpose and Scope of the Inspection and Meeting i A special electrical inspectic: was performed at Philadelphia Electric Company's (PECo) Corporate Office in Philadelphia to assess the licensee's corrective actions to resolve restart issues identified in the NRC's

? Special Electrical Team Inspection Report No. 50-277/278-89-07. At the request of NRC management, a meeting was held in the NRC Region I office on April 10, 1989 to discuss the voltage adequacy of de equipment. A summary of .the licensee's presentation is provided as Attachment 1 to this report. A subsequent inspection on April 13, 1989 resolved all the

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restart' issues for Unit No. 2. The status of the unresolved items

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reviewed are discussed in Section 3.0 of this repor '

3 ' Followup 'of Previous Inspection Findings 3.1. -(Closed) Unresolved Item (50-277/89-07-03) (0 pen) (50-278/89-07-03)

Capacity Margin for Batteries

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During NRC Electrical Team. Inspection 89-07, the team raised a question regarding the capacity of batteries 2BD001 and 20D001 to suppcrt the electrical demand during a LOCA (LOCA load profile).

Following the inspection, the licensee developed a new calculation

_(calculation EE-035) to reevaluate the margin between the rated l capacity of the batteries and the design load profile. The new calculation accounts for the additional inrush current required when starting resistors for various dc motor operated valves (M0Vs) are removed. This was to resolve concerns related to NRC Information Notice.88-72 on inadequacies _in the design of de MOVs. The calcula-tion accounts.for load changes due to the new modifications. In addition to the above load changes, the licensee included a 5% load margin in the existing' load profile to account for uncertainty in the magnitude of individual loads presently.not confirmed by field walkdow l The licensee decided to evaluate the batteries for a two hour rather  ;

than a four hour. duty cycle. A survey made by the licensee among the Region I plants shows that a two hour battery design bases is common practic The Peach Bottom Atomic Power Station FSAR Section 8.7. states that the station batteries are adequately sized to provide dc power until ac power is restored. Since the diesels start in approxi-mately 10 seconds and restore power to the battery chargers within 13 seconds, the batteries are normally relied on to provide power for.approximately 16 seconds (allowing three seconds tolerance). Thus, evaluation for a two hour duty cycle satisfies the FSAR commitmen The inspectors noted that the existing technical specifications allow the battery chargers to be out of service for up to three days, thus jeopardizing the availabi m y of full battery capacity. The licensee confirmed that the existing procedures require them to charge the batteries to float voltage using portable battery chargers any time the respective battery charger is out of operatio The inspectors verified the manufacturer's (Exide) average capacity '

of mean size cell curve and the licensee's battery B current versus 1 voltage profile curve (validating manufacturer's curve) using the existing load profile. The ir.spectors concluded from the above curves that the battery has sufficient capacity to provide voltages above the technical specification limit for at least two hours. The licensee's calculations for a two hour battery duty cycle instead of a four hour duty cycle demonstrated an acceptable capacity margin

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for the batterie The present calculation shows the capacity margin on batteries 280001/200001 to be 21% for a two hour duty cycl The battery capacity' is further assured through the licensee's surveil-lance test program consisting of service-tests, performance tests, and quarterly and weekly battery inspections. However, PEco has agreed to confirm the calculations by performing a one minute load test. 'This will improve confidence in the battery capability at the worst duty cycle. The ifcensee documented this commitment in a letter dated April 14, 1989. This test will be a one minute battery service test on the Unit 2 batteries. This test will be conducted at the initial 0-1 minute inrush current value. The battery voltage will be measured to validate an acceptable terminal voltage. These tests.will be performed prior to the end of the next Unit 2 refueling outage or, before, if there is an outage of sufficient duration which commences after July 17, 198 The licensee is preparing new calculations to document the load profile for each class IE battery in Units 2 and 3, based on field walkdown data from individual component The current calculations include a 5% margin in the existing load profile to account for the uncertainty in the magnitude of individual loads not confirmed by field walkdown. The licensee stated that calculations for Units 2

- and 3 will be completed in late 1989 and late 1990, respectivel The inspectors concluded that there is no restart concern for Unit 2 based on the current estimated capacity margi This item is closed for Unit No. .2 (Closed) Unresolved Item (50-277/89-07-01) (0 pen) (50-278/89-07-01)

Voltage Adequacy for dc Equipment During the previous Electrical Team Inspection, the team noted that the licensee had not established the adequacy of de voltage at de equipment such as MOVs, contactors, coils, and relays. In response, the licensee performed calculation No. EE-033 to determine whether the Unit 2 motor operated valves (MOVs) could develop sufficient torque to operate under worst case design basis events. Inadequacies in the design of de MOVs and failure of de MOVs to develop rated torque because of improper cable sizing were the subject of Information Notices 88-72 and 89-1 The licensee assumed in their calculation the technical specification limit of 210V de at the motor control centers (MCC) rather than taking the actual voltage available at the battery terminal. During this evaluation, the licensee identified six MOVs with starting res' tors that could not produce enough torque for timely valve acti; tion. To resolve this potential problem, a modification (Mod No. 5125) was performed removing the starting resistors from the

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motor. circuits.of these valves. The licensee stated that-a similar evaluation and modification is to be performed at Unit 3 before restar The licensee established the. operability of the MOVs by the " required thrust" vs. "as left thrust" verified through MOVAT testing. The

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. licensee's calculation and. subsequent' presentation demonstrated that all of the MOVs needed for LOCA/ LOOP scenerio have a target thrust margin of.approximately 30%. This margin conservatively accounts for the cable voltage drop at the motor terminal.

r The licensee did not perform detailed voltage drop analyses for

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ce quipment other than the MOVs. NRC Information Notice 89-16 entitled

" Excessive Voltage Drop in de System" was issued to_ licensees to address the potential operability problem due to design deficiencies in_de power systems. The. licensee performed a preliminary review for

. equipment which must operate during the 0-16 second period before the b battery charger power is restored. The nature of the analysis and tests 'are discussed. in the attached material presented by the licensee. During this review, the licensee stated that the minimum de voltage required-co energize the de closing. coil for the 4.16 kV switchgear breaker was about 60-67V de based on a test of 19 circuit breakers. 'The licensee's calculation showed that 76 volts was available at the breaker closing coil. The manufacturer's recom-mended minimum voltage is 90V dc. The licensee is planning a program to reestablish the manufacturer recommended design margin on the dc closing coi Subsequent discussions with the licensee revealed that they are in the process of developing a computerized system to study the voltage drop in the de system. The inspectors concluded that the

, test data developed by the licensee provides adequate assurance of breaker operability pending completion of the licensee's progra Based on the inspection, discussions and presentation by the

, licensee, the inspectors concluded that there are no' restart issues for Unit 2 de power system. Preliminary calcu'C ions demonstrated the de system's capability tc respond to a design basis accident with a coincident loss of off-site power. However, the licensee stated that the final voltage adequacy calculations for Unit 2 and 3 will be completed by the end of 1989 and 1990, respectivel PECo has agreed to validate the calculations through testing before the end of the next Unit 2 refueling outage or, during any outage of sufficient dura-tion that commences after July 17, 198 The tests will be performed l'

to validate that the voltagi. drops are consistent with the calculation results. The tests will include a power circuit to a de MOV and a limiting case de control circuit at nominal voltage levels. The test data will then be extrapolated to confirm the voltage drop at reduced ( voltage levels. The inspectors had no further question The Unit No. 2 item is closed, u

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3.3 (Closed)-Unresolved Item (50-277/89-07-07; 50-278/89-07-07) 13kV-Switchgear Interrupting Rating This item pertains to the lack of sufficient interrupting rating margin for the 13kV switchgear which supply the safety related 14.16kV buse The licensee presented a revised short circuit calculation which factored in the impedance of the feeder cables. This increases the interrupting margin to 13.4%. 'The question of the conservatism of

'the calculation was addressed.in the licensee's respunse to the NRC-dated March 17,1989. This was done by factoring in the short-circuit contribution from the reactor recirculation motor generator sets. The inspectors observed that the fault current from the emergency diesel generator was also accounted for in the calculation .

to address the potential fault condition during a test configuratio The licensee confirmed that the plant automatic controls and operat-ing procedures prevent the possibility of. transferring all of the station non IE and IE loads to the only available offsite power source.. All other bus configurations were analyzed in the calcula-

-tion. The inspectors had no further question This item is close .4L (Closed) Unresolved Item (50-277/86-25-03) Administrative Controls on Electrical Load Growth This item addresses lack of an up-to-date engineering calculation to demonstrate acceptability of the Emergency Diesel Generator loads and an on line program to monitor and evaluate the load changes resulting from plant modifications. The inspectors reviewed the interim calcu-lation the licensee developed to. address the emergency diesel generator capacity concern for Unit 2 restar This calculation factored in all the significant loads up to the motor control centers (MCCs).

The inspectors compared the kW nameplate rating of the equipment and the values used for computing the load on the diesel. No discrepancies

.were observe However, certain minor loads on the MCCs were not clearly addressed for the duration of emergency service and the starting time. The licensee is in the process of developing a detailed load list with all of the significant loads up to the distribution panels with emergency duty, power consumption, and operational duration specified. This item is closed as a restart item for Unit No. 2 based on the following reason The licensee utilized the maximum power requirements for all the significant loads in the present calculation and established that for worst accident scenario the diesel has a capacity margin of 92kW in its 200 hour0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br /> rating.

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The previous NRC team inspection did not find any load discrepancies in the ac syste *

The licensee walkdown did not reveal any problems in the 4kV load *'

' Unit 3 emergency loads-are at a minimum demand as the plant'is

. shutdow This item is closed for Unit No. However, it is a Unit No.-3 unresolveditem;(50-278/89-13-01) pending completion of the load calculation and the implementation of an on line load tracking progra .5 -(Closed)1 Unresolved Item (50-277/89-07-13; 50-278/89-07-13) Adequacy of MCC Feeder Cable Protection-This pertains to the long time delay overcurrent protection of the cables that feed the MCCs. There is a possibility of these cables

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becoming overloaded causing premature failur This concern was raised in'the licensee's calculation but there was no record of the corrective actions take The licensee provided the following justifications for the acceptability of the existing installation The. design has precluded the possibility of overloading the MCCs under all design bases events The feeders from MCCs have individual protection The probability of high impedence faults on MCC feeders are l ow.-

-The inspectors reviewed the maximum ampacity of the subject cables as recommended by Insulated Cable Engineers Association (ICEA)

standard P-46-426. The setpoint of the current long tirco element is very close to the maximum ampacity of the cable. The licensee stated

.they plan to review the feasibility and cost benefit of providing an improved design for MCC feeder cable overcurrent protection. This is currently scheduled for the next refuel cycle for Units 2 and This item is close .6 (Closed) Unresolved Item (50-277/86-09-01; 50-278/86-12-01)

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Emergency Load Center Transformers to Operate with a Low Gas Pressure The 480V load center transformers used to supply the 480V emergency buses are the gas filled type. Scheduled routine maintenance using Doble testing, is done every third refueling outage. The inspectors 1-E - - . _ - - - . - - . - - . - - - - - - - - - - - - - - - - - - - _ - - - - - - - - - - -

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interviewed the personnel responsible for this' testing'to. gain an understanding.of the tests._ The testing results are values of insulation power _ factor which.when corrected for. temperature.give an indication of the insulation condition' Results were compared with

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' data collected from like transformers'to assist in the evaluatio Values:of power factor' readings in.the range of 1.5 to 3, when

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corrected to 20 C, aia considered acceptable. Use of Doble testing for gas filled' transformers is an acceptable method. These tests-establish the adequacy of'the present insulation in the transforme The inspectors concluded that test results observed demonstrate

- acceptable insulation values for the four safety related gas filled'

transformers in both Unit 2 and Unit ~.This' item is close <

3.7_ Other Electrical Related Open Items

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'During the. inspection, the licensee stated that_the evaluations'and corrective actions for the following Unit 2 open . items are complet . Under Rated Fuse (50/277 - 89-07-04)

' Undersized de Bus Connection (50-277-89-07-05)- Thermal Overloads' at 480V MCCs-(50-277-89-07-09) Loose. Terminal Blocks in 480V.MCCs (50-277-89-07-11)-

' Fuse Discrepancies'(50-277-89-07-10)

-A walkdown performed by the licensee staff did not reveal any discrepancie The inspectors ~ concluded these corrective actions adequate.for restart of Unit .0 Unresolved Items-Unresolved items are matters for which more information is_ required in order to ascertain whether they are acceptable, violations or deviation Unresolved items are discussed in Section 3.0 of this repor .0 Exit Interview At the conclusion of the inspection on April 7 and 13, 1989, the inspectors met with the licensee representatives, denoted in Section 1.0.

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The-inspector summarized the scope and findings of the inspection at that

tim No written material was provided to the licensee by the inspectors.

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, ' ATTACHMENT ~- 1 g

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PRESENTATION TO-NRC REGION I e

ON x DC: VOLTAGE ADEQUACY AND DEGRADED GRID PROTECTIVE '

RELAY SCHEME FOR PEACH BOTTOM APS

PHILADELPHIA ELECTRIC C APRIL 10,1989

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l Adequacy of DC Voltage to Equipment MOVs IEN- 89-16

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Degraded Grid. Protective Relay Scheme General: Description Status of Response to NRC Questions

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L Ace.quacy of DC VIOV

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Thrust & Torque Vlargin

= IEN. 88-72 REVIEW  !

• Calc EE-033 '

• Design Review

• Mod 5125  :

= mod 2231 MOV PROGRAM y

• Special Project #1253

• Target Thrust Margin Approximately 30%  !

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CONCLUSION

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All DC MOVs have adequate

' thrust & torque margin to  ;

perform design basis safety func' tion

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Conservatism' in Overall DC:MOV Analysis

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-instantaneously. Actually, MOV & cable temperature-rise would . occur graduall . Design torque values used to evaluate motor' torque:

-acceptability are higher than actually require Design stem' factor used to calculate required torque

^is shown to' be conservative by testin (See MO-2-23-24 example.)

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.lE Notice 89-16 o

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Complete ' Unit 2 -

1989 2 Complete Unit 3 -

1990 i

Re Inspection Report Dated 3/24/89 50-277/89-07 & 50-278/89-07 P.E.Co. Letter to NRC Dated 3/17/89

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Design Review Performed Philosophy of Review Methodology Conclusion

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P1ilosoplysof Review o

Restoration of Battery Chargers Within Maximum of 16 Sec. For-Design Basis Accidents Wit Coincident Loop

Chargets Are Q Powered from 4KV Assure Adequate DC Voltage

. for.. Equipment Required L to Operate from T=0-16.Se .

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Methodology System Versus Design Basis Loop w/o LOCA DBA LOCA w/o Loop DBA LOCA &. Coincident Loop Small LOCA & Coincident Loop DC Voltage Drop Review PCIS  !

4KV Breakers y Load Centers Diesel Generators RPS-l ARI

Diesel Generator Controis i HPCI

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DC Calculation (T=0-16' Sec.)

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y Operation of Base DC Loads Assumed.

. Operation of Equipment.for -

Safety. Related Systems included

. Circuit Configurat?;n to End Devices Modeled to Determine i Calculated Voltage-Established Minimum Pickup Voltages for End Devices Catalog Information Field Testing Compared. Calculated Versus Required Voltages WJB8904F I

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DEGRADED GRID b PROTECTIVE RELAY 90 +/- 2 %

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