IR 05000269/1986001

Insp Repts 50-269/86-01,50-270/86-01 & 50-287/86-01 on 860114-0210.Violation Noted:Failure to Follow Procedure During Channel C Calibr & Functional Test,Resulting in Reactor Trip from 100% Power

ML20210H408
Person / Time
Site:	Oconee
Issue date:	03/20/1986
From:	Brownlee V, Bryant J, Sasser M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
Shared Package
ML20210H360	List: IR 05000269/1986001 ML20210H357 ML20210H374 ML20210H408
References
50-269-86-01, 50-269-86-1, 50-270-86-01, 50-270-86-1, 50-287-86-01, 50-287-86-1, IEIN-85-094, IEIN-85-94, NUDOCS 8604030056
Download: ML20210H408 (10)

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UNITED STATES

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NUCLEAR REGULATORY COMMISSION

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101 MARIETTA STREET, N.W.

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Report Nos.: 50-269/86-01, 50-270/86-01, and 50-287/86-01 Licensee: Duke Power Company.

422 South Church Street Charlotte, N.C.

28242 Facility Name: Oconee Nuclear Station Docket Nos.: 50-269, 50-270, 50-287-License Nos.: DPR-38, DPR-47, and DPR-55 Inspection Conducted: Jgnuary 14 - February 10, 1986 Inspectors: bi L/A d u b J 8 $0

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Approved by:

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['h V. l. Bgowiniee, Section Chief, ( Acting)

Date $1gnbd Division of Reactor Projects SUMMARY Scope:

This routine, announced inspection entailed 270 insoector-hours on site in the areas of operations, surveillance, maintenance, followup of events, cold weather preparations, reactor shutdown margin, and prepr. rations for refueling.

Results:

Of the seven areas inspected, no violations were identified in six areas.

One violation was found in one area (Failure to follow procedure during

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surveillance test, paragraph 11).

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REPORT DETAILS 1.

Licensee Employees Contacted

• M. S. Tuckman, Station Manager J. N. Pope, Superintendent of Operations

• T. B. Owen, Superintendent of Maintenance R. T. Bond, Compliance Engineer

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• T. C. Matthews, Technical Specialist

• D. E. Havice, I&E Engineer B. G. Davenport, Performance Engineer-J. W.~ Collier, Reactor Engineer Other licensee employees contacted included technicians, operators,

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mechanics, security force members, and staff engineers.

• Attended exit interview.

2.

Exit Interview The inspection scope and findings were summarized on Feburary 11, with those persons indicated in paragraph 1 above. The licensee did not identify as proprietary any of the materials provided to or reviewed by the inspectors during this inspection.

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Licensee Action on Previous Enforcement Matters-Not inspected.

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Unresolved Items Unresolved items were not identified on this inspection.

5.

Plant Operations The inspectors reviewed plant operations throughout the reporting period to verify conformance with regulatory requirements, technical speci ficatior.s (TS), and administrative controls.

Control room logs, shift turnover records, and equipment removal and restoration records were reviewed routinely.

Interviews were conducted with plant operations, maintenance,

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' chemistry, health physics and performance personnel.

Activities within the control rooms were monitored on an almost daily basis.

Inspections were conducted on day and on night shifts, during week days and on weekends.

Some inspections were made during shif t change in order to evaluate shif t turnover performance.

Actions observed were conducted as required by Operations Management Procedure 2-1.

The complement of licensed personnel on each shift inspected met or exceeded the requirements of TS.

Operators were responsive to plant annunciator alarms' and were cognizant of plant conditions.

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Plant tours were taken throughout the reporting period on a routine basis.

The areas toured included the following:

Turbine Building-Auxiliary Building Units 1, 2, and 3 Penetration Rooms Units 1,2, and 3. Electrical Equipment Rooms Units 1,2, md 3 Cable Spreading Rooms Station Yard Zele within the Protected Area Standby Shutdown Facility Units 1 and 2 Spent Fuel Pool During the plant tours, ongoing activities, housekeeping,. security, equipment status, and radiation control practices were observed.

Unit 1 operated at essentially full power until 3:48 a.m. on January 31, when the unit 1 output breaker, PCB-20, failed, causing its ceramic insulator to explode.

This caused the breaker to open, resulting in a

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turbine trip and an anticipatory reactor trip.

During and following the reactor trip all systems performed as required to stabilize the reactor at

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hot shutdown conditions.

The main feeawater pumps tripped due to high discharge pressure following the reactor trip, however; the emergency feedwatar pumps supplied feedwater to the steam generator as designed.

There was no ESF actuation.

The fault in the 230 Ky switchyard caused the yellow bus to become isolated, rendering the overhead path from the Keowee emergency power supply inoperable.

However, the underground power path was not affected.

Emergency power was not required during or after the unit trip. As required by TS, the Keowee emergency power path through the underground feeder was operability tested within I hour. The inoperability of the Keowee overhead emergency power path placed all three Oconee units in a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> action statement.

The yellow bus was re-energized at approximated 6:30 p.m., ending the action statement. Unit I was critical at 8:14 p.m. with power operations resuming at 3:23 a.m. on February 1.

The unit remained at full power through the end of the report period.

Unit 2 operated at essentially full power until 11:31 a.m. on January 31, when the unit tripped from 100% power following a load rejection which caused a turbine and anticipatory reactor trip. At the time, electricians were performing maintenance and testing of microwave circuits in the 230 Kv switchyard. Input of signals into an electrical circuit unexpectedly caused

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a breaker fault relay on PCB-23 to actuate.

This relay signal was an indication that a fault had occurrad on the.

breaker, the breaker then opened causing a generator lockout.

All systems performed as required during the reactor trip.

Feedwater

continued to be supplied to the steam generators by the main feedwater

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pumps.

No actuation of engineered safety features (ESF) occurred.

Following reset of the breakers in the switchyard, the reactor was returned critical at 3:00 p.m.

Power operations resumed when the turbine was placed on-line at 12:04 a.m. on February 1.

Full' power operations continued until 3:30 p.m. on February 4 when the unit tripped on reactor power imbalance.

Cause of the trip was the reactor protection system (RPS) channels C and D trip breakers opening during the performance of a surveillance test.

This trip is discussed in greater

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detail in paragraph 11.

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Following evaluation and determination of the reason for the trip, the reactor was taken critical at 8:19 p.m. on February 4.

Power operation was

. resumed and the-unit remained at full power through the end of the report period.

Unit 3 operated at essentially full power until 6:00 a.m. on January 30, when power reduction began in order to repair a turbine reheat stop valve which had closed. Power was reduced to 15% and the turbine taken' off line at 10:53 a.m. The turbine was placed back on line and power ascension began at 3:59 a.m. on January 31.

At 7:08 a.m.

on January 31, the reactor tripped from 57% power on high pressure. The trip was caused when a main feedwater pump flow transmitter failed high, causing a feedwater runback and the subsequent reactor high pressure trip.

Only one feedwater pump was operating at the time. All systems responded normally and there was no ESF actuation. The unit was made critical at 10:49 a.m. on January 31 and returned to power the same day. Unit 3 continued operation at full power through the remainder of the report period.

6.

Surveillance Testing

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The surveillance tests listed below were reviewed and/or witnessed by the inspectors to verify procedural and performance adequacy.

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The completed tests reviewed were examined for necessary test prerequisites, instructions, acceptance criteria, technical content, authorization to begin work, data collection, independent verification where required, handling of deficiencies noted, and review of completed work.

Tha tests witnessed, in whole or in part,. wore inspected to determine that approved procedures were available, test equipment was calibrated, prerequisites were met, tests were conducted according to procedure, test results were acceptable and systems restoration was completed.

Surveillances witnessed in whole or in part are as follows:

CP/1/A/2002/01 Unit 1 Primary Sampling System CP/0/A/2004/6B Determination of Fluorides, Unit 2 RCS and PZR

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CP/0/A/2004/2B Determination of Boron, Unit 2 RCS and PZR CP/0/A/2004/3E Determination of Chlorides, Unit 2 RCS and PZR PT/0/A/290/04 Turbine Stop Valve Movement, Unit 1 PT/0/A/290/03 Turbine Control Valve Movement, Unit 1 PT/1/A/251/02 SF Cooling Pump A Performance Test PT/2/A/1103/15. Reactivity Balance Procedure Surveillance tests reviewed are as follows:

PT/0/A/620/09 Keowee Hydro Operation PT/2/A/600/10 Reactor Coolant Leakage PT/1/A/600/10 Reactor Coolant Leakage PT/2/A/600/01 Periodic Instrument Surveillance PT/1/A/1103/15 Reactivity Balance Procedure, Unit 1 PT/2/A/1103/15 Reactivity Balance Procedure, Unit 2 PT/3/A/1103/15 Reactivity Balance Procedure, Unit 3 No violations or deviations were identified.

7.

Maintenance Activities Maintenance activities were observed and/or reviewed during the reporting period to verify that work was performed by qualified personnel and that approv'ed procedures in use adequately described work that was not within the skill of the trade. Activities, procedures end work requests were examined to verify proper authorization to begin work, provisions for fire, cleanliness, and exposure control, proper return of equipment to service, and that limiting conditions for operation were met.

Maintenance witnessed in whole or in part:

WR 27182B Repair 2 RIA-10 WR 27807B Repair of 28 RBCU Motor Starter WR 53892 Replace 3CA Gattery 8.

Starting of Low Pressure Injection (LPI) Pump With Suction Valve Closed Report No. 269/85-38 discussed the starting of IC LPI pump with the suction valve,

.P-7, closed. The error was detectsd itmediately and the pump was not damaged. The inspectors have reviewed the event in greater detail to determine just how it occured.

PT/1/A/0203/06, Low Pressure Injection Pump Performance Test, has several functions and references different sections on enclosures, depending on _the purpose of using the procedure. As stated in the earlier report, the system was prepared soon after midnight for testing on the following shift. The final part of the preparation performed by the night shift was a section of an enclosure which required, in three steps, opening the suction valve, opening the vent valve, and when venting was complete, closing the vent valve. These steps were performed and verified. The next step would be to return to the body of the procedure and resume the tes.

The nuclear equipment operator (NEO), knowing that no further work was to be done, requested the reactor operator (RO) to close LP-7, which is the tormal action after merely venting the pump and returing it to its normal mode.

Without referencing the procedure, the R0 did as requested. Note that LPI pump C has no automatic ESF function. Twelve hours later the performance group began performing the test. The enclosure, since there was no step to close the valve and sign completion, indicated that LP-7 was open.

The error apparently resulted from the time lag between setting up the system and performing the test, the configuration of the procedure, and the NEO, in effect, adding a step which was not in the procedure. The residents were made aware of the error; the error was noted immediately and corrective action taken which prevented damage to the pump; and the procedure has been modified to add a step req" iring verification that valve LP-7 is open prior to starting the pump.

The licensee is reviewing other

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procedures and the practice of performing valve lineups a considerable period of time before a test is performed. Due to the circumstances and the corrective action taken, this event was not cited as a violation.

.The inspector followup item, IFI 269/85-38-01, is closed.

9.

Determination of Reactor Shutdown Margin (61707)

An inspection of the licensee's. program for. determining shutdown margin (SDM) was performed to verify that SDM calculation is technically correct and in accordance with TS and station procedures.

Technical review of procedures verified that the most recent critical conditions prior to unit shutdown are used in the SDM calculation.

The factors which must be considered are the core reactivity changes due to fuel burnup, power, temperature, boron, xenon, samarium, and control rod position.

On January 31, Oconee taits 1, 2, and 3 each tripped off-line duc to different reasons. The inspectors reviewed the specific SDM calculations performed for those reactor trips.

SDM is calculated using procedure

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PT/A/1103/15, Reactivity Balance Procedure, with curves specific to each unit based on prior core reload data for the unit cycle.

Following a reactor trip the Performance reactor engineer calculates a

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reactor SDM for het shutdown conditions with all control rods inserted for the specific conditions of burnup, boron concentration, xenon, and others as appropriate.

All calculations are independently verified by a second individual on a separate sheet. Subsequent calculations for SDM, shutdown boron concentration, or estimated critical rod position (ECP) are performed

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based on changing conditions as required by the appropriate startup or trip recovery procedure.

The inspectors reviewed all the calculations performed following the unit trips of January 31. One minor discrepancy was noted and discussed with appropriate licensee staff.

Following the trip of unit 3, the ECP was

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calculated in preparation for restart. During the approach to criticality, the reactor did not go critical within the required window on rod position.

As required by the startup procedure, all control rods were inserted for re-evaluation of the ECP.

It was determined that the boron concentration existing at the time of startup was higher than that used for the initial

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ECP calculation because water from the concentrated boric acid storage tank (CBAST) had been used for makeup durino the previous 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period since the last chemistry sample.

'Although a procedural violation did not exist, the inspectors discussed with the licensee the importance of ensuring the use of accurate existing reactor conditions for all calculations in the reactivity balance procedure.

The inspectors will review future reactivity balance calculations to verify that this type of problem does not continue.

No violations or deviations were identified.

10.

Preparation for Refueling (60705)

For the unit 1 outage, scheduled to begin on 2/13 the residents reviewed the licensee's preparations for refueling, including the controls on receipt, inspection, and storage of new fuel. An inspection tour of the units I and 2 spent fuel pool (SFP) was taken to assess cleanliness, the storage area for new fuel, empty space available to off-load the core, and the general condition of the pool area and equipment.

Procedure OP/0/A/1503/04, New Fuel Assembly Inspection and Storage, was

reviewed to ensure that an adequate, approved procedure is available for receipt, inspection, and storage of new fuel.

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The inspectors selected a recent shipment of new fuel from Babcock & Wilcox (B&W), for review of all the completed documentation.

This shipment

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included six containers each containing two fuel assemblies.

The documents reviewed were:

Performance memo to Operations specifying the correct location for

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each new fuel assembly and its components.

Completed procedure OP/0/A/1503/04 for the shipping containers and

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fuel assembly.

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All documents either received from B&W or completed by Operations which trace the new fuel from the supplier to its location in the SFP.

Inc!uded are bill of lading, NRC/D0E Form 741, shipping notice, emergency instructions to driver, and fuel assembly storage notification.

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All the documentation reviewed was found to be in order.

The fuel assemblies were traced from the supplier, B&W, to the receiver and subsequently to specific storage locations in the SFP. The inspectors found

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that adequate procedures exist to control the receipt, inspection, and storage of new fuel.

Following the inspection of new fuel receipt the inspectors reviewed the licensee's program for refueling. The sequence for refueling the reactor is as follows:

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Offload of the entire reactor core into the SFP.

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Component shuffle in the SFP to match up components with correct fuel assemblies.

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Verification of correct assemblies and components in the SFP.

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Reload of the reactor core.

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Core. verification of correct fuel assemblies and core alignment.

The inspectors verified that adequate. procedures exist to control the above activities..The procedures which determine the reload sequence, identifying specific core locations, 'are developed by station and general office engineering personnel and formally transmitted tc t,perations personnel for l

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No violations or deviations were identified.

I 11.

Unit 2 Trip Due To Personnel Error Unit 2 tripped from 100% power at 3:30 p.m. on February 4, apparently due to a' personnel error during performance of a surveillance test.

The unit tripped on power imbalance when safety rods trip breakers were in advertently left opened, driving the rods into the reactor. All safety systems performed as required and there was no engineered safety system actuation. Steam generator levels were maintained at the post trip startup levels.

At the time of the trip, I&E technicians were performing ' procedure IP/2/A/305/3C, RPS Channel

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Calibration and Functional Test, when a personnel error.resulted in breakers CB-3 and CB-4 (associated with Channel D) mistakenly being tripped and left open at the local shunt trip instead of the Channel C breakers, CB-1 and CB-2.

The error was not realized at the time and when subsequent steps in. testing of the Channel C trip logic resulted in opening of CB-1 and CB-2, the rods drove in on 2 out of 4 RPS logic.

Critical steps in the test procedure being followed required independent verification.

All steps in the procedure were. properly signed off, indicating that correct actions were taken and verified to be correct. The mechanics stated that they did not believe an error had been made; however, the events recorder shows the sequence of events leading to the trip.

While the licensee reported the event and all actions taken after the event were correct, this will be cited-as a violation for failing to follow procedure since the critical steps in the procedure had been signed and

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independently verified to be correct.

(Violation failure to follow

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procedure during surveillance test 50-270/86-01-01).

12.

Emergency Drills On January 29 the residents participated in a practice emergency drill on Unit 3.

During the simulated accident, in which a simulated site area emergency was declared, the techincal support center (TSC) and operational support center were actuated.

On February 2 the residents participated, at the TSC and the crisis

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management center, in a practice drill in which general emergency was simulated.

In the early phases of the drills the inspectors' observed the drill from the control rooms to verify that the drills did not impart negatively on routine operation of the reactors. The inspectors determined that all phases of the drill were handled professionally and.in a controlled manner.

13.

Information Notice 85-94 - Minimum Flow Paths IE Notice 85-94: Potential for loss of Minimum Flow Paths Leading to ECCS Pump Damage During a LOCA, alerted licensee's of recent problems discovered at some plants which found that minimum flow requirements might not be met for some emergency core cooling system (ECCS) pumps under some accident conditions.

In summary, the information notice stated that some pumps had inadequate flow paths due to system design or valve problems.

The inspectors reviewed the recirculation flow paths for Oconee safety related pumps, both independently and with licensee personnel.

The high pressure injection (HPI), low pressure injection (LPI), emergency feedwater, and reactor building spray (RBS) systems were reviewed. Results of _ the residents' review, as summarized below, indicated that problems of the kind presented in the IE Notice are not present at Oconee.

For each HPI pump there is a one and one half inch minimum flow recirc line with 35-40 gpm flow directed to the letdown coolers and back to the letdown storage tank.

There are two manual block valves in each recirc line, however these are always open by procedure.

There are no procedures which require these to be closed.

Pumps 'always have minimum recirc while operating.

Each LPI pump-has a one inch recirc line back to the pump suction with no cooling.

The recirc lines have no block valves and cannot be isolated.

Because the recirc line provides no heat sink, the LPI pump (s) can only be run for a short period of time while dead headed.

This is controlled administratively in the emergency operating procedure (EOP) through a note l

that states that LPI cannot operate without flow for more than 30 minutes.

The coerator is directed to establish flow or secure the pump (s).

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For the reactor building spray (RBS) pumps there is no recirc path. Pump suction is always open by procedure. The pump discharge valve op~ ens and the pump starts on the same signal, ESF and containment high pressure. The pump discharge pressure is 250 psig; the only restriction is the containment pressure.

Since containment design pressure is 60 psig there is adequate margin to ensure pump flow.

For the motor driven emergency feedwater pumps (EFW) there is an automatic, self contained, minimum recirc valve incorporated into the discharge check valve. All other valves in the recirc lines are locked open by procedure.

The turbine driven EFW pump has a recirc line which is always open to the upper surge tank. All valves in the line are locked open by procedure.

No violations or deviations were identified.

14.

Licensee Event Reports The inspectors reviewed nonroutine event reports to verify the report details met license requirements, identified the cause of the event, described corrective actions appropriate for the idenfified cause, and adequately addressed the event and any generic implications.

In addition, as appropriate, the inspectors examined operating and maintenance logs, and records and internal investigation reports.

Personnel were interviewed to-verify that the report accurately reflected the circumstances of the event, that the corrective action had been taken or responsibility assigned to assure completion, and that the event was reviewed by the licensee, as stipulated in the Technical Specifications.

The following event reports were reviewed:

(0 pen) LER 270/82-10 Stuck Suction Relief on the "2B" MFWP, After a Reactor Trip. This incident resulted in the upper surge tank level falling below technical specifications limits.

Only one outstanding commitment remains. Station Modification 1584 has been installed, but does not work satisfactorily. Until oparational problems are resolved the LER will remain open.

(Closed) LER's 269/83-17 and 269/83-20 Delayed trip on CRD DC Breaker.

Several modifications have been completed on reactor trip breakers, and changes have been made to preventive maintenance procedures. There have been no recent failures and there are no further modifications in work. These items are closed.

(0 pen) LER 269/83-12 Emerr~.1cy Discharge Valve Opened Without Ccmmand

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Due to Component Malfunct.on.

Corrective action was taken which restored the equipment to operability and heaters were ins *.alled to disipate moisture. A final change to relocate power cables in order to prevent spurious operation is scheduled to be completed by August 1, 1986.

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