IR 05000333/1993022

Insp Rept 50-333/93-22 on 930920-24.Weakness Identified. Major Areas Inspected:Eds Deficiencies During NRC Edsfi

ML20058C726
Person / Time
Site:	FitzPatrick
Issue date:	11/09/1993
From:	Ruland W, Scholl L NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20058C722	List: IR 05000333/1993022 ML20058C719
References
50-333-93-22, NUDOCS 9312020552
Download: ML20058C726 (9)

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U.S. NUCLEAR REGULATORY COMMISSION REGION 1 REPORT / DOCKET.NOS.: 50-333/93-22 LICENSE NO.:

DPR-59 LICENSEE:

New York Power Authority (NYPA)

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P.O. Box 41 l

Lycoming, New York 13093

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FACILITY:

James A. FitzPatrick Nuclear Power Plant

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i LOCATION:

Scriba, New York l

l INSPECTION DATES; September 20-24,1993

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INSPECTOR:

y L. Sclioll, keactor Engineer Date

Electrical Section, EB, DRS

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APPROVED BY:

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William H. Ruland, Chief

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Electrical Section, EB, DRS e

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i 9312O20552 931115 PDR ADDCK 05000333 G

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Areas Insnected: Electrical distribution system deficiencies identified during NRC electrical distribution system functional inspections (EDSFIs) at various facilities.

Results Generally, the issues inspected were found to have been aduluately reviewed and addressed by NYPA. Two items, regarding the ability of the emergency diesel generator l

building ventilation system to withstand the effects of a tornado (Section 2.4), and the

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adequacy of the emergency diesel generator logic testing (Section 2.6), are unresolved.

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DETAILS

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1.0 BACKGROUND in 1989, the NRC performed a safety system functional inspection on the electrical

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distribution system at FitzPatrick. Since that inspection the NRC has performed mole than

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50 electrical distribution system functional inspections (EDSFIs) at licensed reactor facilities throughout the country. Information regarding significant deficiencies identified during these

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inspections has been provided to all reactor plant licensees through the issuance of hTC

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Information Notices. The inspector reviewed several of these deficiencies for applicatility to

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the FitzPatrick plant and to determine if NYPA had take the appropriate actions in response

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to the information.

2.0 INSPECTION DETAILS j

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The inspector held discussions with various members of the licensee's staff and reviewed drawings, calculations and procedures associated with the areas inspected. The issues that were reviewed are discussed in the following NRC Information Notices:

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91-13 Inadequate Testing of Emergency Diesel Generators (EDGs)

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91-29 and Deficiencies Identified During Electrical Distribution Supplement 1 System Functional Inspections

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91-51 Inadequate Fuse Control Program

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92-40 Inadequate Testing of Emergency Bus Undervoltage Logic Circuitry i

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92-53 Potential Failure of Emergency Diesel Generators Due To j

Excessive Rate ofImading

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2.1 Inadequate Voltage (IN 91-29)

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At three plants the NRC found that, under certain conditions, the voltage available at the

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safety buses would be inadequate to operate safety-related loads and equipment. These

conditions could occur when the plant electrical distribution systems were being supplied from an offsite grid that had become degraded.

NYPA is in the process of reviewing and updating electrical system calculations as part of a

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comprehensive electrical distribution system review program. A consultant has been retained to perform portions of this work, and to develop a computer model of the system down to i

the 600 Vac level. The initial work is complete, has been reviewed by NYPA and the

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consultant is in the process of resolving the NYPA comments. NYPA has completed a

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review and update of the 125 Vdc system calculations. No significant problems were i

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identified by NYPA during these reviews. A similar task remains to be performed for the 120 Vac system. The inspector concluded that NYPA was taking appropriate actions to confirm the adequacy of the electrical system design bases, including a verification that bus voltages are adequate.

2.2 Molded-Case Circuit Breaker Testing (IN 91-29)

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The NRC has identified deficiencies in licensee programs to test circuit breakers. These

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deficiencies included inadequate procedures, inadequate test acceptance criteria, inadequate j

i test equipment and inadequate control of testing.

NYPA has established maintenance procedures for circuit breakers that are specific to voltage rating and type of current. The procedures are MP-056.01, "AC Motor Control Center

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Maintenance and Subcomponent Replacement," and MP-200.16, " Maintenance and j

t Subcomponent Replacement of GE 7700 Series DC Motor Control Centers." In 1991, NYPA performed a detailed review of all of the circuit breaker failures that have occurred since the initial plant startup and used the results of this study to determine the testing

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frequency for the breakers. Both safety-related and nonsafety-related breakers are tested on a frequency of four to eight years. The inspector concluded that the scope of the program for the maintenance and testing of circuit breakers is good.

2.3 Interrupting Capacity and Coordination of Fault Protection Devices (IN 91-29)

NRC inspections have identified conditions in which the interrupting capacities of fault protection devices were not adequate for the application and other cases in which a lack of coordination could have resulted in a branch circuit fault causing the trip of a feeder circuit breaker or fuse.

Several problems were identified in the area of fuse and breaker coordination during the SSFI inspection performed in 1989. These problems were subsequently corrected and reinspected. The inspector noted that NYPA's ongoing efforts to review and update electrical system calculations and to generate a computer model of the electrical distribution system includes a review of the adequacy of the fault protection device interrupting capacities and coordination. These reviews are essentially complete down to the 600 Vac level and for the 125 Vdc system. The 120 Vac system remains to be performed.

2.4 Emergency Diesel Generator Mechanical Interfaces (IN 91-29 Supplement 1)

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I The NRC found deficiencies invohring EDG mechanical systems interfaces such as air-start systems, fuel oil storage and heating, ventilation and cooling systems.

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To verify the adequacy of the EDG air start system NYPA performed temporary surveillance test TST-1, "EDG Air Starting Reservoir Capacity Test." The inspector reviewed the results_

of this test that demonstrated that the diesel would start seven times from nominal air

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I receiver pressure, including 5 starts from air pressures that were below the air receiver low pressure alarm point.

i To ensure adequate fuel oil storage to support seven days of EDG operation, NYPA performed temporary surveillance test TST-7, " Fuel Oil Consumption Test." This test measured the fuel oil consumption for each EDG while it was opemting at its continuous rating of 2600 KW. The inspector reviewed the test results and calculations and concluded i

that the test demonstrated adequate fuel oil storage capability for seven days of continuous j

operation. The inspector also noted that since the maximum expected loading during an

accident is approximately 77% of the continuous EDG rating, there is considerable margin available.

l The inspector reviewed NYPA's assessment of the EDG room ventilation system adequacy.

l Based on an EDG room ventilation capacity test performed in August 1989, NYPA

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concluded that the EDG room temperature would reach a maximum of 114 degrees l

fahrenheit with the EDG operating at full load with an outside temperature of 93 degrees.

This temperature would not impact the operation of the EDGs.

t At the D. C. Cook site it was discovered that the ability of the EDG ventilation system and

engine air intake ducting to withstand the differential pressure effects of a tornado may not

have been considered during the initial design of these components. NYPA also has been j

unable to locate documentation or calculations which address these concerns for the

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FitzPatrick plant. The lack of design documentation is being tracked by NYPA in their

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design document open item tracking system as item DDOI-JAF-EDG-093-001 and is

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expected to be resolved by December 31,1993. The resolution of this issue was assigned a l

low priority by NYPA, based on the assumption that it was simply a case of missing i

documentation. During the effort to locate design documentation, it became evident that the

effects of a tornado on the EDG structures ventilation may never have been a design

consideration. The inspector questioned whether any operability evaluation had been

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performed based on this information. NYPA could not produce any such evaluation and agreed to review this issue further. This is an apparent weakness in the application of l

guidance on performing operability evaluations which is discussed in NRC Generic 12tter

91-18, "Information to Licensees Regarding Two NRC Inspection Manual Sections on Resolution of Degraded and Nonconforming Conditions and on Operability." This issue is i

unresolved pending NRC review of the NYPA's design evaluation (50-333/93-22-01).

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2.5 Fuse Control Program (IN 91-51)

Numerous problems associated with the control of fuses in the plant electrical systems have been identified during NRC inspections and by licensees as reported in Licensee Event Reports. Fuse control deficiencies include:

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inadequate root cause evaluation of blown fuses

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inadequate verification of design information for installed and replacement fuses

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inadequate identification and labeling of fuses

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improper coordination of fuses and circuit breakers

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personnel errors NYPA currently controls fuses with plant Procedure PSO-56, " Replacement of Electrical Fuses." This procedure provides guidance for fuse installation during plant modifications and for the replacement of blown fuses. Exhibit 9.1 to the procedure lists specific fuse sizes and types to be used in the 4.16 kV switchgear control circuits and the 600 Vac load center and motor control center control circuits. NYPA is taking measures to strengthen the fuse control program including the development of a comprehensive fuse list that is to be completed following plant panel walkdowns planned for the next refueling outage. This fuse list will list all plant fuses and suitable replacements that will ensure the plant design considerations, such as fuse and breaker coordination, are not affected. During the next procedure revision, steps will be included to direct the investigation of the cause of blown fuses prior to replacement. This change is being tracked in the licensee commitment tracking program. The inspector concluded that when the planned program improvements are completed by NYPA a good fuse control program will be in place.

7.6 Emergency Bus Undervoltage Logic Circuitry Testing (IN 92-40)

During the EDSFI inspection at the LaSalle County Nuclear Station, the NRC found that the surveillance test used for the loss of offsite power test was not testing the capability of the undervoltage logic circuitry to de-energize the emergency bus. The loss of offsite power was simulated by tripping the emergency bus feeder breakers. One function of the undervoltage logic circuitry is to open the feeder automatically during an undervoltage condition to ensure that the emergency diesel generator is not connected to a degraded offsite power source.

Manually tripping the feeder breaker to initiate the test did not permit the testing of this functio !

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i FitzPatrick offsite power is supplied to the 4160 volt buses through two series circuit

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breakers one safety grade and one non-safety grade. To initiate the test of the undervoltage circuitry, the non-safety breaker is tripped to de-energize the bus. The undervoltage circuitry then initiates a trip of the safety-related tie breaker, the start of the emergency diesel l

generators, the energization of the emergency bus by the EDGs, and the starting of the

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emergency core cooling pumps.

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During the review of NRC Information Notice 91-13, NYPA determined that there was not j

sufficient overlap between the instrumentation and controls tests (relay tests) and the j

functional tests to ensure all of the emergency diesel generator logic was tested. NYPA

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subsequently performed a detailed review of the EDG logic testing and generated two additional tests to ensure all of the circuitry was tested as required by the plant technical specifications. Licensee Event Report 92-50 was submitted to the NRC by NYPA as a result

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of their failure to comply with the technical specification testing requirements and documents

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the corrective actions taken.

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Subsequent to this inspection, NYPA performed additional reviews of the EDG logic testing

and determined that an auxiliary contact on the non-safety feeder breaker also initiates a trip t

of the safety-related feeder breaker. Therefore, although the test methodology verifies the

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trip of the feeder breaker, it is not possible to determine that the undervoltage logic is functioning properly since the two trip signals are present simultaneously. NYPA is

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currently reviewing this issue. The adequacy of the EDG logic testing is unresolved pending l

the NRC review of NYPA's corrective actions (50-333/93-22-02).

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2.7 Emergency Diesel Generator Rate of Loading (IN 92-53)

The NRC found at the Calvert Cliffs Nuclear Power Plant that, under certain conditions, I

loads could be sequenced onto the emergency bus more rapidly than the design capability of the emergency diesel generator.

At FitzPatrick each emergency bus is supplied by two EDGs with a combined rating of 5200 kW. The EDG load review, Calculation Number E77-01, determined that the worst-case loading on an emergency bus would be 3,992 kW or approximately 76.8 % of the EDG

rating. The EDG loads are sequenced on the emergency bus by the use of time delay relays.

l Initially the emergency bus loads are stripped with the exception of the feed to the 600 Vac i

load centers. When the bus recnergizes following a loss of offsite power coincident with a loss of coolant accident the 600 Vac loads are immediately energized. The emergency core

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cooling system pumps are then sequenced on by time delay relays. The first pump starts at 1-1.5 seconds, the second pump at 5.5-6.5 seconds and the third pump at 10.4-11.6 seconds.

This sequencing is tested by ST-9C, " Emergency AC Power Load Sequencing Test and 4 kV

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Emergency Power System Voltage Relays Instrument Functional Test." During this test, the

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emergency bus voltage is monitored by a strip chart recorder. The inspector reviewed the

data taken during the last performance of the test and found that the EDG was able to

generate full voltage on the bus in less than 0.2 seconds after the circuit breaker closure.

j During the pump starts, bus voltage dropped slightly below nominal and was restored to full i

voltage in approximately one second.

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Based on the rapid recovery time of the bus voltage, during initial energization and during

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pump starts and the durations between pump starts, the inspector. concluded that excessive

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EDG loading due to coincident sequenced pump starts was not a concern.

l The inspector also reviewed the emergency bus loads to determine if there were loads that

could cycle onto an emergency bus coincident with a sequenced load start and, thereby,

challenge the ability of the EDG to maintain adequate bus voltage and frequency.

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Considering the excess EDG capacity available, and the relatively small size of the cyclic loads, no problems were identified.

3.0 CONCLUSION

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The inspector concluded that, in general, NYPA had adequately evaluated and implemented j

corrective actions based on industry findings related to the electrical distribution system.

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4.0 EXIT MEETING i

At the conclusion of the inspection on September 24,1993, the inspector met with licensee representatives listed in Attachment 1. The inspector summarized the scope and results of the inspection at that time. The licensee acknowledged the inspection findings as detailed in this report and had no additional comments regarding the inspection results.

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ATTACIIMENT 1

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PERSONS CONTACTED i

i New York Power Authority

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• R. Barrett

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R. Converse

M. Colomb

J. Heddy l

N. Hoy l

• T. Klein

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D. Lindsey l

D. Ruddy

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T. Savory l

D. Simpson

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G. Tasick i

F. Weinert

A. Zaremba j

l U. S. Nuclear Regulatory Comm_ijsion

l J. Tappert

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Indicates those who attended the exit meeting on September 24,1993,

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