ML20203D571

Insp Repts 50-498/98-15 & 50-499/98-15 on 990614-1123. Violations Noted.Major Areas Inspected:Review of Circumstances Surrounding 980614 Fire in Potential Transformer & Subsequent Deenergization of Switchgear E1B

ML20203D571
Person / Time
Site:	South Texas
Issue date:	02/10/1999
From:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
Shared Package
ML20203D490	List: ML20203D484 ML20203D561 ML20203D571
References
50-498-98-15, 50-499-98-15, NUDOCS 9902160246
Download: ML20203D571 (23)

See also: IR 05000498/1998015

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ENCLOSURE 2

U.S. NUCLEAR REGULATORY COMMISSION

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REGION IV

Docket Nos.:

50-498

50-499

License Nos.:

NPF-76

NPF-80

Report No.:

50-498/98-15

50-499/98-15

Licensee:

STP Nuclear Operating Company

Facility:

South Texas Project Electric Generating Station, Units 1 and 2

Location:

FM 521 - 8 miles west of Wadsworth

Wadsworth, Texas 77483

Dates:

June 14 through November 23,1998

Inspectors:

D. P. Loveless, Senior Resident inspector

C. F. O'Keefe, Senior Resident inspector, STPEGS

G. L. Guerra, Resident inspector, STPEGS

Approved By:

J. l. Tapia, Chief

Project Branch A

Division of Reactor Projects

ATTACHMENT:

SupplementalInformation

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9902160246 990210

PDR

ADOCK 05000498

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PDR

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EXECUTIVE SUMMARY

South Texas Project Electric Generating Station, Units 1 and 2

NRC Inspection Report 50-498/98-15; 50-499/98-15

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This special inspection was conducted to review the circumstances surrounding the June 14 fire

in a potential transformer and the subsequent deenergization of Switchgear E18. The review -

focused on operator performance during the event and circumstances surrounding the retum to

operability of the Gwitchgear E1B vital de subsystem while Battery Bank E1811 was in a

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discharged state. Calculations indicated that the battery was capable of performing its intended

functum throughout the event. However, operator performance during the event was

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considered weak. Licensed operator knowledge and procedure usage were inconsistent and

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resulted in violations of Technical Specifications and plant operating procedures.

Operations

Fire in the Train B switchgear caused operators to deenergize the' train. Vital Battery

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Bank E1811 was discharged for 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />, and was, subsequently, considered to be

operable prior to its being fully recharged. The safety significance of not recognizing

that the battery was not operable was considered to be low because calculations

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demonstrated that the battery was still capable of performing its safety function

throughout the event. Although the battery and the associated train's ability to respond

to a station blackout were degraded, the remaining electrical systems continued to be

- able to respond to a station blackout event and to achieve and maintain a safe

shutdown condition (Section 01.1).

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- A number of the procedures used during the event were unclear or not sufficiently.

specific. This resulted in delayed response actions, misdirection of limited operator

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- resources to unnecessary tasks, and delayed questkening of the operability of Battery

Bank E1B11. Annunciator response procedures did not drive resolution of the problem

and did not provide operators with a list of Technical Speification required equipment

rendered inoperable when engineered safety features buses were deenergized, further

slowing operator response. The inspectors concluded that oparators had low

' expectations for the quality of the operating procedures and did not initially take action

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to improve them following this event (Sections 03.1 and O3.2).

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Licensed operators were unable to reenergize a vital bus undo, ixalized station

- blackout conditions because they did not recognize and override an antipumping

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breaker interlock. This prevented establishing standby diesel generator cooling and

delayed the retum of power to vital equipment for an additional 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 20 minutes. The

inability to establish cooling to the standby diesel generator due to a lack of procedural

- guidance and operator knowledge was considered a significant weakness

(Section 03.1).- ' '

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During the initial response to the deenergization of Switchgear E18, licensed operators

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failed to place the Train B equipment hand switches in the pull-to-lock position. This

' failure to follow the requirements of Procedure OPOPO4-AE-0001 was in violation of.

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Technical Specification 6.8.1. However, this nonrepetitive, licensee-identified and

corrected violation is being treated as a noncited violation, consistent with

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Section Vll.B.1 of the NRC Enforcement Policy (Section O3.2).

Licensed operators failed to understand the physical condition of Battery Bank E1B11

because they were unfamiliar with battery theory and the bases for battery-related

- Technical Specifications and surveillance requirements. As a result, the operability of a

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substantially discharged battery was not questioned until challenged by inspectors.' This

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resulted in a violation of the electrical de system operability Technical Specification. In

addition,'the shift supervisor, unit supervisor, duty operations manager, and duty

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engineer misunderstood the basis for Technical Specification 4.8.2.1.b and improperly

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concluded that the battery was operable. This was the result of inadequate reviews and

relying on the preliminary interpretation of each other (Sections 04.1 and 04.2).

Operators failed to place the pressurizer power-operated relief valve hand switch in the

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closed position while the associated block valve was inoperable. Although Technical

Specifications were not violated, the failure to identify that the block valve position.

indicator was not illuminated during shift tumover was not in compliance with operating

procedures. This nonrepetitive, licensee-identified and corrected violation is being -

treated as a noncited violation, consistent with Section Vll.B.1 of the NRC Enforcement

Policy (Section 04.2)

Although the minimum requirements of Technical Specifications were met, the operators

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were slow to identify that an engineered safety features power availability verification

surveillance test was required (Section O4.2).

Maintenance

During the bench testing and installation of a replacement potential transformer,

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procedures and the work order were prcperly implemented. Communication between

electrical maintenance and operations' personnel was observed to be good. First-line

supervision was in the field and providing appropriate oversight (Section M1.1).

Licensee technicians improperly performed a surveillance test to determine the state of

charge of safety-related Battery Bank E1B11. The surveillance test was conducted

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while recharging was in progress, contrary to a prerequisite in the procedure. An

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unfamiliarity with battery theory and the bases for battery-related Technical

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Specifications was the common cause between this and the failure to meet the

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requirements of the Technical Specifications and the corresponding violation

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(Secton M1.2).

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Enaineerina

Engineering calculations and analyses were well documented with reasonable

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assumptions supported by industry standards and vendor information. These efforts

fully supported the conclusion that the battery was capabic of performing its safety

function throughout the event, and thus the safety significance of the event was low.

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However, the licensee's conclusion that Battery Bank E1B11 had been maintained in a

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condition consistent with the Technical Specification requirements focused too narrowly

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on specific gravity as the sole parameter for battery operability and did not recognize the

inaccuracy of the measurements (Section E1.1).

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The inspectors concluded that the inefficient application of engineering staff resources

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may have exacerbated the problems with evaluating the problems with Switchgear E1B.

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However, licensee management was taking broad corrective actions to ensure better

support staff utilization in the future (Section E4.1).

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.' Report Details -

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Summary of Plant Status

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At 5:08 p.m. on June 14, licensod operators deenergized Vital Switchgear E1B in response to

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indications of an electrical fire. Unit 1 had been operating at 100 percent power. At 7:31 p.m. a

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- plant shutdown was commenced in accordance with Technical Specification 3.8.2.1. At -

approximately 10:45 p.m., the unit shutdown was suspended with reactor power at 12 percent,

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- pending completion of repairs to Vital Switchgear E18. At 1:32 a.m. on June 15, licensed '

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operators commenced power escalation, following retum to service and realignment of Train B

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safety-related equipment. At 9:50 p.m., on June 15, Unit 1 reactor power was stabilized at '

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100 percent.

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Unit 2 operated at essentially 100 percent reactor power throughout this event.

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I, Operations

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01

Conduct of Operations

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01.1

Review of Circurnstances Surroundina a June 14 Fire / Smoke in Switchaear E1B

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Inspection Scope (93702)

A specialinspection was conducted to review the circumstances surrounding the

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. June 14 fire in a potential transformer and the subsequent deenergization of

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Switchgear E18. The review focused on operator performance during the event and

circumstances surrounding the retum to operability of the Switchgear E1B vital dc

subsystem while Battery Bank E1B11 was in a discharged state. On June 14, the

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inspectors responded to the main control room to observe recovery activities.

Corrective maintenance and postmaintenance testing of the switchgear and surveillance

testing of the battery were observed in the field. Following the event, interviews with

licensed cperators and additional personnel involved in the event activities were

conducted. The inspectors reviewed plant computer data and control room logs and

completed procedure data sheets to verify statements of fact developed during the

interviews. The inspectors principally utilized inspection Procedure 93702 to assess the

following areas:

the implications of the event with respect to Technical Specification operability

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and compliance;

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the safety and risk significance of the event; and

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the significance of personnel performance errors while responding to the event.

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Inspection activities documented in this section of the inspection report focus primarily

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on the safety significance of the inoperability of vital Battery Bank E1811. The other

~ areas of the inspection are addressed in subsequent sections of this inspection report.

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System Overview

- The Class 1E 125 vde battery system consists of four independent, physically separated

busses, each energized by one of two available battery chargers and one battery. The

battery chargers are powered through transformers from the three 4.16 kv engineered

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safety features buses. Class 1E electrical distribution equipment is located in the

Seismic Category I classification mechanical-electrical auxiliaries building and arranged

so that each train of the three-train system is located on a different floor elevation. This

provides for independent and redundant power source and distribution equipment such

. that no single failure will prevent a system from performing its safety function.

Solid state protection system Channel lil 125 vdc Battery Bank E1811 consists of 59

lead-calcium cells assembled in shock-absorbing, clear-plastic, sealed containers. The

batteries are kept at a continuous float voltage of 2.20 volts per cell and are maintained

in a nominally fully charged state by the battery chargers. Emergency power required

for plant protection and control is supplied by the batteries. The batteries nre sized to

carry their connected loads for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> without power flow from the +.argers in the

event of loss of ac. The four Class 1E 125 vdc channels have sufficient capacity for a

postulated 4-hour station blackout event, and Channel ll can be ac-independent for an

8-hour duration. Upon loss of power from the ac system to the battery chargers, the

batteries automatically assume the load without switching.

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Event Descriotion

At 5:05 p.m. on June 14,1998, the Unit 1 control room received alarms for load

sequencer trouble and grounds on the Train B 4160 volt bus, Switchgear E1B. The shift

supervisor left the control room to investigate the sequencer, while another operator

. went across the hall from the control room to investigate the bus. The operator

communicated via radio that there was_ smoke in the Train B switchgear room. The unit

supervisor paged the shift supervisor requesting that he return to the control room, and

the two discussed the situation. The unit supervisor urged the shift supervisor to assess

the condition of Switchgear E1B in person before considering deenergizing the bus.

The shift supervisor again left the control room and returned within a minute to order the

bus deenergized. The fire brigade was then activated. Plant Operating

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Procedure OPOPO4-AE-0001, Revision 11, " Loss of Any 13.8 KV or 4.16 KV Bus" was

entered.

. The fire brigade arrived to find that the smoke had dissipated. No fire alarm was

activated in the room, despite the fact that a fire detector was located directly above the

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affected switchboard. Except for a small hole in the top of the potential transformer, no

damage was observed inside the affected switchboard. Initial assessments concluded

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< that the transformer required replacement and that no parts were believed to be

available on site.

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Shift supervision, with the concurrence of the duty operations manager, concluded that

preparations should be made to shut the unit down. Initial power reduction was

scheduled to start after the 7 p.m. shift turnover. The operators spent the remainder of

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the shift determining which equipment lost power and what Technical Specification

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actions were required. The oncoming shift similarly spent a considerable amount of

time evaluating the status of equipment and determining the applicable Technical

Specification actions required. At approximately 8:30 p.m., operators recognized that a

safety function checklist had not been pedormed since the onset of the event. While

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performing this checklist, operators recognized that the pressurizer power-operated

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relief valve hand switch had not been placed in the closed position as required by

Technical Specifications when the associated block valve lost power.

When the ac bus was deenergized, both battery chargers lost their power supplies. The

operators appropriately declared the Train B de system inoperable. The operability of

the associated battery was not questioned. Operators were concemed that Battery

Bank E1B11 was discharging while its associated chargers were deenergized. A

licensed operator was assigned to report battery voltage periodically and to ensure it did

not go below 110 volts. Licensed operators assessed options for providing temporary

power to the chargers. Reenergizing Switchgear E1B with the potential transformer

isolated was determined to be the best alternative.

At 9:38 p.m., licensed operators started Standby Diesel Generator 12 and closed the

supply breaker, energizing Switchgear E18. However, attempts to close the feeder

breakers to Motor Control Centers E181 and E182 were unsuccessful. Engineers later

determined that the problem had resulted from the expected actuation of an

antipumping breaker interlock. Operators were unaware that, by design, loads on the

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sequencer had to be shed before the load center breakers could be shut as a result of

breaker antipumping circuitry. Standby Diesel Generator 12 was placed in the

emergency stop condition because cooling water to the diesel heat exchangers required

ac power from Motor Control Center E1B2.

During a search of the main warehouse, maintenance personnel were able to locate a -

spare potential transformer. A work package was planned and work commenced to

replace the transformer. Power reduction was halted at approximately 12 percent

reactor power when operators were within an hour of taking the main generator off line

and entering Mode 3. Work was then completed shortly before the self-imposed

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deadline for continuing the entry into Mode 3. Power was restored to all affected

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switchgear at approximately 12:08 a.m. on June 15. Operators pedormed a safety

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function checklist to verify that all equipment was operable, then exited all Technical

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Specification actions associated with the event at 12:36 a.m. At 12:45 a.m., inspectors

questioned battery operability because it was observed to be charging at a high rate.

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Although the shift supervisor considered it operable, he consulted with the duty engineer

who recommended performing the battery quarterly surveillance to confirm this

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conclusion. Power ascension was commenced at 1:32 a.m.

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Electrical maintenance personnel commenced performing the quarterly battery

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operability surveillance test at 1:35 a.m. After measuring the specific gravity in eight

random cells, the duty engineer concluded that the battery was not going to meet the

test procedure's acceptance criteria. None of these measurements were recorded.

This was reported to the shift supervisor at 2:15 a.m. along with a recommendation to

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perform stratification measurements. The shift supervisor concurred and, after some

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delay in locating the required test equipment, measurements were resumed at 3 a.m.

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By this time, specific gravity of the battery cells had increased as a result of the chargeng

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current.: Based on the data taken at that time, the duty engineer determined that'

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stratification measurements were no longer required and a routine midcell measurement

of cell-specific gravity was conducted. However, this action was not discussed with the

shift supervisor. The surveillance test was completed at approximately 4:30 a.m. and

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reviewed at 5:13 a.m. by the shift supervisor. Average specific gravity was noted on the

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test record sheet as not meeting the acceptance criteria, but being within Technical '

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Specification allowable values.

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9bservations and Findinas

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The inspectors reviewed the licensee's assessment of the safety significance of the

- event.~ Engineers performed sizing calculations as documented in Section E1.1. The

engineering study showed that the batteries could have supplied the channel's 2-hour

design-basis loads following the observed 7-hour discharge. This study did not include

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a customary assumption for age-related degradation because the batteries had recently

been replaced. ' Based on a review of this engineering study, the inspectors concluded

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that the safety significance, as it related to the original design basis of the battery, was

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low.

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With regard to the station blackout functions of the battery, South Texas Project relies

on any one of the three standby diesel generators as the alternate ac source. Battery

Bank E1811 was required to provide a 4-hour coping duration. The degraded condition

of the battery following the June 14 discharge left the battery unable to respond to a

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station blackout 4-hour profile. The battery could only have provided station blackout

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loads for approximately 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. Consequently, the station blackout design for the

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altemate ac capability was degraded. The additional three batteries would have

provided the required capability and would have supported the recovery of either :

Standby Diesel Generator A or C as the alternate ac source. The licensee concluded

that the Station 1 E batteries retained the capability to respond to a station blackout.

Therefore, although Vital Battery Bank E1811 was degraded following a 7-hour

discharge, this did not eliminate the station's ability to respond to a station blackout

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event and achieve and maintain a safe shutdown condition.

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Conclusions

The safety significance of discharging Vital Battery Bank E1B11 for 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br /> and

declaring it operable prior to fully charging the battery was considered low. The battery

continued to meet its design basis requirements throughout the event. Although the

battery and the associated train's ability to respond to a station blackout were degraded,

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the remaining electrical systems continued to be able to respond to a station blackout

event and achieve and maintain a safe shutdown condition.

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03~ , Operations Procedures and Documentation

03.1 ' Quality of Procedures to Combat the Event

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Inspection Scooe (71707)

The inspectors reviewed the procedures utilized in responding to the' June 14 event.'

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Control room logs were reviewed and licensed operator interviews were conducted to .

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ascertain the scope and usage of procedures. The following procedures were evaluated

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in detail to determine their accuracy and adequacy for responding to the event.

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Licensed operator implementation of the procedures was also assessed:

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OPOP09 AN-03M3, Revision 3, " Annunciator Lampbox 3M03 Response

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instructions"

OPOPO4-ZO-0008, Revision 3," Fire / Explosion"

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OPOPO4-AE-0001, Revision 11. " Loss of Any 13.8 KV or 4.16 KV Bus"

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OPSP03-EA-0002, Revision 3, " Engineered Safety Features (ESF) Power

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Availability"

OPSP03-XC-0002A, Revision 4, " Partial Containment inspection (CWainment

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Integrity Established)"

OPOP03-ZG-0006, Revision 8," Plant Shutdown from 100% to Hot Standby"

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OPOP03-ZG-0005, Revision 19, " Plant Startup to 100%"

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OPSP06-DJ-0002, Revision 3,"125 Volt Class 1E Battery Quarterly Surveillance -

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Test"

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Observations and Findinas

Through interviews with conttol room operators, the inspectors determined that a

number of procedures utilized during this event presented problems to the users.

Examples included:

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The annunciator response procedure for the initial alarms received as a result of

the failed transformer, Procedure OPOP09-AN-03M3, did not direct the operators

to a resolution of the problem. ' When operators realized that the affected bus

needed to be deenergized, the annunciator response procedures for the alarms

generated from deenergizing the bus did not provide sufficient information, such

as which Technical Specification equipment was rendered inoperable.

Operators did not have a list of loads supplied by the buses deenergized in

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response to the failure. Procedure OPOPO4-AE-0001 did not io:lude the

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Technical Specification impact statements and was generic in nature. Rather

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than having a separate section for each bus, the procedure applied to all similar

buses.. This caused the Unit Supervisor to send operators to check unaffected

equipment in order to comply with the procedure. Similarly, this procedure did

not direct performance of the safety function checklist, which would have

resulted in a more timely identification that one of the pressurizer

. power-operated relief valve block valves was inoperable.

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Procedure OPOPO4-ZO-0008 presumed that a fire would be initially discovered

by a fire alarm. In this case, a fire alarm was not received in the affected

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switchgear room. This may have delayed response to the fire because the Shift

Supervisor decided to personally confirm the situation before deenergizing the

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bus and activating the fire brigade after an operator reported heavy smoke.

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Procedure OPOPO4-AE-0001 did not provide adequate procedural guidance to

reenergize the motor control centers following a blackout condition on

Switchgear E18. Once the sequencer stripped the motor control centers and

locked out, attempts to close the breaker were precluded by an antipumping

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breaker interlock. As documented in Section 01.1, when operators attempted to

reenergize Switchgear E1B with Standby Diesel Generator 12, the load center

breakers were prevented from closing and cooling could not be provided to the

diesel generator. Insufficient operator knowledge of the interlocks precluded

restoring the bus. The inability of operators to reenergize a vital bus under

station blackout conditions was considered a significant weakness. This inability

delayed the return of power to vital equipment for an additional 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />

20 minutec.

Procedure OPSP06-DJ-0002 was not explicit in some regards. For instance, the

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procedure listed acceptance criteria; however, if these acceptance criteria were

not met, then stratification measurements were to be taken. Maintenance

personnel interpreted this to mean that, if stratification measurements averaged

to the required specific gravity, the acceptance criteria would be satisfied, even .

though it did not meet the procedural acceptance criteria.1 This misinterpretation

resulted in a continued belief that the battery.was operable when measurements

indicated the contrary.

The Procedure OPSP06-DJ-0002 steps for taking stratification measurements of

electrolyte-specific gravity could not be performed as written. The procedure

required sampling the electrolyte approximately an inch from the top and bottom .

of the cell and in the middle. ' Inspectors observed that the sample tube extended

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from the cell top to approximately 5 inches below the surface, preventing

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technicians from obtaining a representative sample. A top sample would have

required removing the flame arrester, However, this was procedurally prohibited.

The inspectors found through interviews that operators had low expectations for the

quality of procedures. The operators expressed frustrations about some of the

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procedures and had not submitted procedure improvement requests.

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c.

Conclusions

A number of the procedures used during this event were unclear or not sufficiently.

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specific. This resulted in delayed response actions, misdirection of limited operator

resources to unnecessary tasks, and delayed realization that Battery Bank E1811 was

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inoperable.: Annunciator response procedures did not drive resolution of the problem

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. and did not' provide operators with a list of Technical Specification required equipment

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rendered inoperable when engineered safety features buses were deenergized, further '

slowing operator response. The inspectors concluded that operators had low -

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expectations for the quality of the operating procedures and did not initially take action

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to improve them following this event.

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' Licensed operators were unable to reenergize a vital bus under localized station -

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. blackout conditions because of an antipumping breaker interlock. The inability to

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establish cooling to the standby diesel generator due to lack of procedural guidance and

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operator knowledge was considered a significant weakness. This inability delayed the

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retum of power to vital equipment for an additional 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> 20 rninutes.

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03.2 Operations Compliance with Procedur_qg (71707)

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After deenergizing Switchgear E1B, operators performed Plant Operating

Procedure OPOPO4-AE-0001, Revision 11," Loss of Any 13.8 KV or 4.16 KV Bus."

Step 1 in the procedure required operators to verify that all ac engineered safety

features buses were energized.' With Switchgear E1B deenergized, the response was

not obtained. Therefore, the procedure directed operators to place Train B equipment

hand switches in the pull-to-lock position. This action was not performed while

implementing this procedure. Procedure OPOPO4-AE-0001 was completed at 5:36 p.m.

on June 14. However, the Train B equipment hand switches were not placed in the

pull-to-lock position until approximately 9 p.m. The failure to follow the requirements of

Procedure OPOPO4-AE-0001 was in violation of Technical Specification 6.8.1. This is a

nonrepetitive, licensee-identified and corrected violation and is being treated as a

noncited violation, consistent with Section Vll.BM si the NRC Enforcement Policy

(498/98015-01).

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.The; unit supervisor had performed this evolution and stated during an interview that the

failure to place the hand switches in the pull-to-lock position was an oversight. The

event review team documented this occurrence and management took appropriate

action. The inspectors reviewed Condition Report 98-9069. Action 7 described

corrective actions and proposed revisions for the weaknesses in

j

Procedure OPOPO4-AE-0001.

During interviews with the unit supervisor and reviews of procedural controls, the

inspectors noted that Procedure OPOP04-AE-0001 was a generic procedure that

covered a!! safety-related and nonsafety-related switchgear in the plant. The lack of

specific direction caused operators to perform unnecessary verifications clearly

unrelated to the deenergization of Switchgear E1B. A review of this procedure's quality

l'

is covered in Section 03.1 of this inspection report.

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04

Operations Knowledge and Performance

04.1 Operator Knowledae of Batterv Function and Theory -

a.

Inspection Scope (71707)

The inspectors conducted interviews with senior reactor operators, reactor operators,

and reactor plant operators to evaluate the general knowledge of battery theory,

function, and the associated Technical Specification bases. The licensee's event review

team report and the sequence of events were evaluated and were included as part of

~ his assessment.

t

b.

Observations and Findinas

The inspectors observed that the operators involved in this event were not familiar with -

the battery Technical Specifications bases and only had a general knowledge of battery

theory' The inspectors found that this lack of knowledge contributed significantly to the

.

operators' conclusions about batten operability.

During this event, a licensed operator was assigned to monitor battery voltage during

the time it was discharging, as discussed in Section 04.2 of this inspection report. This

was based on a mistaken belief that Technical Specification 4.8.2.1.b implied that the

battery was operable if its output remained above 110 volts. The inspectors determined

that each of the operators involved incorrectly believed that battery voltage was an

indication of the state of charge.

The inspectors reviewed IEEE Standard 450-1980, "lEEE Recommended Practice for

- Maintenance Testing, and Replacement of Large Lead Storage Batteries for

Generating Stations and Substations." This document stated that the state of charge

was determined by measuring specific gravity of the electrolyte. Howaver, the standard

further stated that specific gravity was not accurate during charging. Thus, the state of -

charge of the battery could not be determined after the discharge was begun until it was

fully recharged. This conclusion was supported by Technical Specification

requirements, but was not understood by operators.

Similarly, the quarterly battery surveillance was performed despite not meeting a

prerequisite that the battery be fully charged and at float voltage. Operators and

electricians mistook this to mean that the charger was set for a float charge. As a

result, operators requested the performance of a surveillance intended to trend the

condition of a fully charged battery over its lifetime with the intent of determining the

state of charge of a substantially discharged battery. When the initial results were not

the desired results, stratification measurements were ordered. After a delay during

which charging continued, measurements were obtained that appeared to support the

initial conclusion that the battery was operable. However, the questionable validity of

these measurements was not recognized. Consequently, the state of charge could not

be accurately determined at that time, and the battery was inoperable.

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The inspectors noted that the licensee's response plan for this event conservatively

- assumed that repairs would not be made in time and that the plant would require entry

. into Mode 3. When repairs were successful, licensed operators did not fully evaluate

what actions and equipment conditions would be required to retum to full power.

Operability of the battery was never considered until raised by the inspectors. Since the

de electrical supply system was inoperable while the chargers were deenergized,

operators had not been forced to consider battery operability, only the functional status

of the battery.L Once the charger was reenergized, the associated battery condition

became important for operability of the system, but the inoperable condition was not

recognized.-

c.

Conclusions

Operators were unfamiliar with battery theory and the bases for battery-related

Technical Specifications. As a result, the operability of a substantially discharged

battery was not questioned until challenged by inspectors. An inappropriate surveillance

!?st was performed in an attempt to confirm that the battery was operable without

_

- recognizing that the results would be inaccurate and that a prerequisite could not be '

met. The test results were then accepted as assuring that the battery was operable

without recognizing that the wrong standard was being used to determine operability.

O4.2 Operator Knowladae and Usaae of Technical Soecifications

a.

Insoection Scope (71707)

The inspectors evaluated Technical Specification actions required by the events of

June 14 and 15. The licensee's event review team report and the Technical

Specifications were reviewed. Interviews were conducted with control room senior

reactor operators regarding implementation of applicable requirements. Licensed -

operator knowledge and usage of Technical Specification requirements were evaluated.'

' Compliance with the following specific requirements was assessed:

Technical Specification 3.8.2.1, "D. C. Electrical Sources"

.

~

Technical Specification 3.4.4," Power-Operated Relief Valves"

-.

Technical Specification 3.8.1.1.a. " Demonstration of Operability for Independent

.

Offsite A. C. Circuits"

Technical Specification 4.8.2.1.b, " Operability Verification of 125-volt Battery

.

Bank Following Discharge"

>

b.

Observations and Findinos

On June 14 at 5:08 p.m., licensed operators deenergized Switchgear E1B. This

removed the Channel 111 battery chargers from service and placed 125-volt Battery

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Bank E lB11 in' service. - At this time, battery terminal voltage dropped to 117.7 volts,

which equated to an average output of 2.0 volts / cell for the 59 connected cells.

Technical Specification 3.8.2.1 states that:

As a minimum, the foilowing D. C. electrical sources shAll be

OPERABLE . . . Chanteel lli 125-volt Battery Bank E1811.

Table 4.8-2, " Battery Surveillance Requirements," provides, in part, that the allowable

float voltage value for each connected battery cell for Category B parameters

. be >2.07 volts. Table Notation 3 states: "Any Category 8 parameter not within its

allowable value indicates an inoperable battery."

The allowable value for specific gravity, as stated in Technical Specification Table 4.8-2,

is that the " Average of all connected cells > or equal to 1.195 or battery charging current

is less than 2 amps when on charge." As documented in Section 01.1.c of this

inspection report, performance of Procedure OPSP06-DJ-0002 indicated that average

. cell specific gravity was less than Txhnical Specification defined allowable values at

2:15 a.m. on June 15. Similar testing documented that average cell specific gravity was

. greater than 1.195 at approximately 3:30 a.m. Licensed operators had determined that

the batteries were operable at that time. However, subsequent calculations by the

licensee showed that specific gravity was less than 1.195 at 8:02 p.m. Therefore, it can

be concluded that the battery was inoperable by at least 8:02 p.m.

The inspectors noted that data from the emergency response facility data acquisition

and display system indicated that battery charging current was greater than 2 amps until

approximately 10:37 a.m. This value of 2 amps related to an instrument reading of

'

approximately 6 amps with a normal steady-state system loading of approximately

4 amps. Technical Specification 4.8.2.1, Table 4.8-2, stated that battery charging

current must be less than 2 amps when on charge for operability. Given that IEEE

-

Standard 450-1980 stated that specific gravity measurements were not accurate while

charging, charging rate was the goveming Technica! Specification parameter.

Therefore, the battery had been inoperable for at least 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> 35 minutes Technical Specification 3.8.2.1.c, Action a., states:

With one of the required battery banks inoperable, restore the inoperable

i

battery bank to OPERABLE status within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or be in at least HOT

.. STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the

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following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />,

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The failure of the licensed operators to place the Unit 1 reactor in a hot standby

' condition within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of Battery Bank E1B11 becoming inoperable was in violation of

- Technical Specification 3.8.2.1.c (498/98015-02).

On June 14 at approximately 8 p.m., a reactor operator performed Form 10,." Safety

Function Checklist," of Plant Operating Procedure OPOP01-ZQ-0022, Revision 15,

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" Plant Operations Shift Routines." At approximately 8:30 p.m., licensed operators

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identified that Pressurizer Power-Operated Relief Block Valve 1-RC-MOV-0001B had

been deenergized when Switchgear E1B had been isolated at 5:08 p.m. Technical

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Specification 3.4.4.d states:

)

With one block valve inoperable,'within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> restore the block valve to

operable status or place the associated power-operated relief -

)

valve (PORV) in closed position; restore at least one block valve to

OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />; otherwise, be in at least HOT '

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STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the

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following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />,

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The inspectors determined that, although the operators had not placed the power-

operated relief valve in the closed position, the shutdown requirements of the

specification were being met for other reasons. Therefore, it was considered fortuitous

that a Technical Specification violation had not occurred. However, licensed operators

on the day shift had been relieved at approximately 7:20 p.m. and failed to recognize the

loss of power to the block valve and the subsequent failure to place the power-operated

relief valve in the closed position during the shift tumover process. Procedure OPOP01-

20-0022, Section 3.3, required that, during shift tuihover, watchstanders walkdown the

control boards. Specifically, step 3.3.5 required that:

During the control board walkdown, on-coming Control Room

Watchstanders SHALL scan the panels to ensure normally lit

indications are illuminated.

The failure of the oncoming licensed operators to determine that the Block

- Valve 1-RC-MOV-0001 B position, a normally lit indication, was not illuminated was in

violation of Procedure OPOP01-ZQ-0022 requirements. This failure is not considered

minor because it represents a potential for missing entry into required Technical

Specification action statements. This nonrepetitive, licensee-identified and corrected -

,

violation is being treated as a noncited violation, consistent with Section Vll.B.1 of the

!

NRC Enforcement Polig'I%/98015-03).

As discussed in Section 01.1.c of this inspection report, licensed operators performed

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Plant Surveillance Procedure OPSP03-EA-0002 approximately 50 minutes after

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Switchgear E1 B was deenergized. This action was fully in compliance with the

Technical Specification 3.8.1.1.a requirement to demonstrat6 the operability of the

remaining engineered safety features power sources within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> of identifying an

iinoperable circuit. However, during interviews with the unit supervisor and the reactor

operator performing the procedure, the requirement to perform the verifications was not

identified until 45 minutes after Switchgear E1B was deenergized. Although the

~ minimum requirements were met, the failure to identify the requirement in a timely

manner was of concern. The adequacy of procedures as a tool to assist the operators

in identifying Technical Specification requirements was reviewed as documented in

Section O3.1 of this inspection report.

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During interviews with the shift supervisor, unit supervisor, duty operations manager,

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and on-call system engineer, the inspectors determined that these individuals

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misunderstood the basis for Technical Specification.4.8.2.1.b. This specification

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requires demonstration of battery operability:

i

.

At least once per 92 days and within 7 days after a' battery discharge with

. j

battery terminal voltage below 110 volts, or battery overcharge with

battery terminal voltage above 135 volts, by verifying that . . . The

!

parameters in Table 4.8-2 meet the Category B limits.

)

Licensed operators had informed the inspectors that Battery Bank E1811 had remained

operable during and following the 7-hour discharge because the battery terminal voltage

had not fallen below 110 volts. The basis document for Technical Specification 4.8.2

states that the surveillance requirements for demonstrating operability of the station

batteries are based, in part, on IEEE Standard 450-1980, "lEEE Recommended Practice

for Maintenance, Testing, and Replacement of Large Lead Storage Batteries for

Generating Stations and Substations." Section 4.3.4,"Special Inspections," of

IEEE 450-1980, states:

If the battery has experienced an abnormal condition (such as a

severe discharge or overcharge), an inspection should be made

to assure that the battery has not been damaged.

Therefore, this specification was intended to specify actions to be taken when the

potential for battery damage exists. It does not imply that a battery with a terminal

voltage of 110 volts under load has sufficient charge to perform its design function.-

Licensee management concurred with this interpretation.

The inspectors found that the operator's erroneous interpretation had been presented to

other control room personnel and had not been reviewed further nor challenged. This

interpretation was supported by the duty engineer. Weaknesses in the operators' ~

knowledge of battery theory and function were reviewed and are discussed further in

Section O4.1 of this inspection report.

c. -

Conclusions

Licensed operators failed to understand the physical condition of Battery Bank E1811

and the basis for battery surveillance requirements. This resulted in a violation of the

electrical de system operability Technical Specification. in addition, the shift supervisor,

unit supervisor, duty operations manager, and duty engineer misunderstood the basis

1

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for the 110 volt limit discussed in Technical Specification 4.8.2.1.b. This resulted from

inadequate reviews and reliance on preliminary interpretations of requirements.

While Technical Specifications were not violated when the operators failed to place the

pressurizer power-operated relief valve hand switch in the closed position while the

associated block valve was inoperable, the failure to identify that the block valve position

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indicator was not illuminated during shift tumover was not in compliance with operating

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procedures. Additionally, although the minimum requirements of Technical

Specifications were met, the operators were slow to identify that an engineered safety

- features power availability verification surveillance test was required.

.

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11. Maintenance

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M1'

Conduct of Maintenance -

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~ M1.1 Observation of Field Maintenance Activities (62707)

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a.

Inspection Scope

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The inspectors observed the testing of two spare replacement potential transformers

and the removal and replacement of the degraded potential transformer in the 4.16 kv

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switchgear.

b.

Qhggrvation and Findinos

After searching for spare potential transformers, maintenance personnel identified two in

the main warehouse. The inspectors observed the technicians bench testing the spare

potential transformers in accordance with Plant Maintenance

Procedure OPMP05-ZE-0206, Revision 1, " Potential Transformer Test." This test

verified that the transformer reduction ratio was consistent with nameplate data. The -

potential transformer specification ratio of 35:1 was verified on both spare transformers.

The_ inspectors observed the removal of the failed potential transformer and the

installation of a bench tested potential transformer in the Train B Class 1E switchgear.-

This was performed in accordance with Work Authorization Number 139620,"4160 VAC

Switchgear E1 Train B 4.16 KV Potential Transformer Appears to Have Failed.'" The -

work was performed as outlined in the work package.

During the replacement, two electricians performed the work while the first-line electrical

supervisor observed and assisted when the electricians requested his opinion. The

licensee maintained sufficient support personnel to assist in the potential transformer

'

. replacement. Engineering personnel also observed the maintenance activity.

Operations and electrical maintenance personnel interfaced well, which resulted in a

- change-out before the end of the Technical Specification action statement for the

battery charger required a unit shutdown. The electricians were careful to align the

- potential transformer so that the stabs would make proper contact with the electrical

- contacts. The potential transformer was energized and the associated equipment

clearance order removed.

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c.

Conclusions

The bench testing and installation of a replacement potential transformer were properly

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implemented in accordance with procedures and the work order. Communication was

good between electrical maintenance and operations' personnel. First-line supervision

was in the field and providing appropriate oversight.

M1.2 Batterv Surveillance Testina

,

a.

Inspection Scope (61726)

On June 15, the inspectors observed testing performed in accordance with Plant

Surveillance Procedure OPSP06-DJ-0002, Revision 3. "125 Volt Class 1E Battery

Quarterly Surveillance Test." In addition, documentation of testing related to Battery

Bank E1811 was reviewed.

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b.

Observations and Findinas:

In response to the inspectors' questions regarding the operability of Battery

Bank E1811, the duty engineer recommended performing Surveillance

Procedure OPSP06-DJ-0002 to measure battery parameters as documented in

Sections 01.1 and O3.1 of this inspection report. The duty engineer had previously

been the system engineer for the system and was famiiiar with the test.

Inspectors observed technicians measure cell voltage for each cell, then measure the

specific gravity in a number of cells at different locations. All measurements were below

,

the acceptance criteria for average specific gravity, with values of approximately 1.190.

!

The inspectors observed that this was expected by the technicians because the battery

had been substantially discharged and had not been charging very long. Without

completing the specific gravity measurements or recording the as-found data, the duty

engineer went to the control room and reported that the measurements "were not going

to pass." The duty engineer recommended taking stratification measurements and

stated that he expected this testing to meet the acceptance criteria because charging

was known to cause stratification. The Shift Supervisor confirmed that the procedure

allowed this action and concurred. Some delay occurred while the proper test-

equipment was located.

When specific gravity measurements were resumed approximately 45 m,nutes later, the

midcell measurements had risen sufficiently to meet the surveillance procedure

,

acceptance criteria. Consequently, the duty engineer informed the technicians that only

'

midcell measurements needed to be performed. Stratification measurements were

therefore never taken at the direction of the duty engineer. When the completed

surveillance document was returned to the control room for review, the S5ift Supervisor

failed to note that the stratification data was not taken. Measuring the specific gravities

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at midcell did not satisfy the surveillance procedure acceptance criteria; nevertheless,

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the Shift Supervisor noted on the surveillance cover sheet that thb specific gravities

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were sufficient to satisfy the Technical Specification surveillance criteria. The battery

,

was therefore considered operable based on the surveillance results.

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The inspectors reviewed the completed surveillance document and identified the

following discrepancies:

The work was authorized by the Duty Operations Manager, rather than the Shift

Supervisor, as specified by the procedure.

Prerequisite 4.3 required the battery to be on float charge. This was

misinterpreted by technicians to mean the charger was in the float charge mode,

rather than the intended battery condition of fully charged and at float voltage.

Technicians stopped following the procedure when it was recognized that the

specific gravity was not going to meet the acceptance criteria. Data for the cells

sampled was not recorded. The duty engineer directed the workers to perform a

stratification test from a subsequent part of the procedure without completing the

intervening steps. After a delay while obtaining the required test equipment,

normal midcell measurements resumed when it was recognized that specific

gravity measurements had increased. The stratification test was not performed

despite failure of the midcell measurements to meet the acceptance criteria.

Specific gravity measurements were manually corrected for cell electrolyte level.

e

The surveillance procedure stated that gas bubbles were created as a result of

charging. However, the nonconservative error was not recognized by any

licensee personnel because portions of the surveillance procedure were not

performed.

IEEE Standard 450-1980 stated that, because of the gas bubbles generated by

j

charging, electrolyte level readings should be made only after the battery has been at

i

float voltage for at least 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The inspectors noted that this was not clearly stated

in the surveillance procedure.

Failure to fully comply with all the provisions of Surveillance Procedure OPSP06-DJ-

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0002 contributed to the failure to meet the requirements of Technical Specification 3.8.2.1 and the corresponding violation further described in Section 04.2.

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c.

Conclusions

Licensee technicians did not satisfy a prerequisite and performed a surveillance test to

determine the state of charge of safety-related Battery Bank E1B11. This surveillance

1

test was conducted while recharging was in progress. This resulted in inaccurate

measurements of specific gravity that were then nonconservatively compensated for by

electrolyte level without accounting for gas bubbles created by charging. The inaccurate

results were used as the basis to consider the battery operable. Failure to fully comply

with all the provisions of a surveillance procedure shared a common cause with the

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failure to meet the requirements of Technical Specification 3.8.2.1 and the

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correspondir,g violation.

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111. Enaineerina

-E1

Conduct of Engineering

E1.1

Evaluation of Licensee Batterv Bank E1811 Calculations

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a.

Inspection Scope (37551)

The inspectors reviewed calculations performed by licensee engineers to determine the

capability of Battery Bank E1B11 to meet design basis requirements. The review also

included the applicable Technical Specifications for battery operability to determine if

any Technical Specification limits were exceeded. The following licensee documents

were reviewed:

Study Calculation, " Class 1 E Channel lli Battery Sizing Verification - June 14,

.

1998 Event"

)

Design Change Package 96-3056-35, Calculation EC-5008, Revision 10, "DC

.

' Channel 111 Loading Computation and Battery Size Verification"

Condition Report Engineering Evaluation 98-9069, Supplement 1

. b.

Observation and Findinas

The calculations performed by licensee engineers determined that Battery Bank E1811

was capable of performing its design-basis function throughout the time that the

chargers were not powered. The study calculation showed that the battery had

sufficient margin to carry its design-basis load even after the 7-hour discharge. The

parameters used in the calculation were in agreement with the design-basis calculations

and vendor supplied battery data. The licensee also had its calculations reviewed by the

battery vendor. As discussed in Section 01.1.d of this inspection report, the

calculations supported the licensee's findings that the safety significance of the

discharged battery condition was low.

The calculations were well documented and had been properly reviewed. The

assumptions used were reasonable and supported by industry standards. In addition to

the design-basis analysis, the study calculation used computer logs of battery output in

amperes to determine the estimated specific gravity throughout the event. The

engineers predicted when the specific gravity of Battery Bank E1B11 would have

decreased below the Technical Specification allowable values. The time to recharge the

battery to Technical Specification limits was also calculated.

The inspectors noted that the licensee's battery operability determination and

reportability review for this event relied solely on the calculated specific gravity. While

this approach accounted for instantaneous battery capacity, it did not address the other

parameters required to demonstrate that the battery was operable as specified in

Technical Specifications. These requirements specify that the battery have a terminal

voltage of at least 129 volts, must be supplied by at least one operable battery charger

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(at a higher voltage than the battery is capable of generating), and must have less than

2 amps charging current. To satisfy these requirements, the battery must be essentially

fully charged. Thus, the operability of a battery cannot be determined by calculating the

!

remaining capacity. The inspectors determined that Battery Bank E1B11 was -

inoperable from the time the charger lost power until the battery was essentially fully

>

charged,

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c.

Conclusions

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Engineering calculations and analyses were well documented with reasonable .

!

assumptions supported by industry standards and vendor information. These efforts

,

fully supported the conclusion that the safety significance of the June 14 event was low.

However, the licensee's conclusion that Battery Bank E1811 had been maintained in a

condition consistent with the Technical Specification limiting conditions for operability

l

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focused too narrowly on specific gravity as the sole parameter for battery operability and

did not recognize the inaccuracy of the measurement.

)

E4

Engineering Support of Facilities and Equipment

E4.1

Enoineerina Support to and Utilization by Operations durina the Event (37551)

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The inspectors interviewed the duty engineer. During the event, he was requested to:

Determine how Switchgear E1B could be reenergized with the failed potential

transformer

T Oversee the potential transformer replacement

e

Evaluate the adequacy of the planned postmaintenance testing

e

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Estimate how long Battery Bank E1B11 would continue to provide sufficient

l

voltage to the de circuits .

,

Review the Technical Specifications for battery operability requirements

e

The duty engineer stated that he typically was not given sufficient time to properly

evaluate or support an item before being directed to start the next. For example, he

stated that he did not have sufficient time to evaluate system design and logic before

the first attempt to energize Switchgear E1B was made at approximately 8:45 p.m.

.

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The duty engineer stated that he had next reviewed the Technical Specifications and

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noted the 110 volts identified in Technical Specification 4.8.2.1.b. The applicability of

this Technical Specification to evaluating current battery operability was discussed in

i

Section O4.2 of this inspection report. The engineer stated that he had discussed this

specification with one of the licensed operators and erroneously informed him that

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Battery Bank E1B11 would remain operable if voltage remained above 110 volts.

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The inspectors noted that the event review team had identified a number of additional

engineers on site throughout most of this event. Questions regarding the adequacy of

support staff utilization during the event were assessed. Condition Report 98-9069,

Action 17, was written to develop expectations for an "off-normal event support team" to

be used during priority maintenance activities that affect reactor safety. The inspectors

concluded that the inefficient application of engineering staff resources may have

exacerbated the problems. However, licensee management was taking broad corrective

actions to ensure better support staff utilization in the future.

IV. Manaaement Meetinas

X1

Exit Meeting Summary

The inspector presented initial inspection findings to members of licensee management

'

by telephone at the conclusion of the inspection on November 23,1998. After additional

in-office inspection and review, final results were communicated on February 4,1999.

Management personnel acknowledged the findings presented. The inspector asked

whether any materials examined during the inspection should be considered proprietary.

No proprietary information was identified.

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ATTACHMEN~i

SUPPLEMENTAL INFORMATION

PARTIAL LIST OF PERSONS CONTACTED

Licensee

H. Allgeyer, Operations Shift Supervisor

C. Bowman, Duty Operations Manager

S. Clark, System Engineer

T. Cloninger, Vice President, Nuclear Engineering

W. Cottle, President and Chief Executive Officer

M. Coughlin, Operations Unit Supervisor

G. Danielski, Reactor Operator

E. Dare, Work Control Programs Coordinator

J. Groth, Vice President, Nuclear Generation

G. Janak, Operations Shift Supervisor

G. Parkey, Plant Manager, Unit 1

J. Phelps, Manager, Operations, Unit 1

M. Ruvalcaba, System Engineer

S. Sieben, Operations Unit Supervisor

R. Travino, Reactor Plant Operator

T. Waddell, Manager, Maintenance, Unit 1

INSPECDON PROCEDURES USED

IP 37551: Onsite Engineering

IP 61726: Surveillance Observations

IP 62707: Maintenance Observation

IP 71707: Plant Operations

IP 93702: Prompt Onsite Response to Events

ITEMS OPENED. CLOSED. AND DISCUSSED

CJened

498/98015-01

NCV Failure to place handswitches in pull to lock (Section O3.2).

+

498/98015-02

VIO

Vital Battery E1B11 was inoperable for at least 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br />

'

35 minutes in violation of the Technical Specification 3.8.2.1.c

requirements (Section O4.2)

498/98015-03

NCV improper control board walkdown during turnover (Section 04.2).

Closed

498/98015-01

NCV Failure to place handswitches in pull to lock (Section 03.2).

498/98015-03

NCV improper control board walkdown during turnover (Section O4.2).

<C