IR 05000413/1990003

Insp Repts 50-413/90-03 & 50-414/90-03 on 891231-900127. Violations Noted.Major Areas Inspected:Routine Resident Insp of Review of Plant Operations,Surveillance & Maint Observation & Review of LERs

ML20012C300
Person / Time
Site:	Catawba
Issue date:	03/02/1990
From:	Hopkins P, Lesser M, William Orders, Shymlock M NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
Shared Package
ML20012C298	List: IR 05000413/1990003
References
50-413-90-03, 50-413-90-3, 50-414-90-03, 50-414-90-3, NUDOCS 9003210007
Download: ML20012C300 (13)

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UNIT E) STATES

NUCLEAR REGULATORY COMMISslON p

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101 MARIETTA STREET. N.W.

• t ATL ANT A, GEORGI A 30323

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Report Nos.:

50-413/90-03 and 50-414/90-03 Licensee: Duke Power Company 422 South Church Street Charlotte, N.C.

28242

Docket Nos.:

50-413 and 50-414 License Nos.:

NPF-35 and NPF-52 Facility Name: Catawba Nuclear Station Units 1 and 2 Inspection Conducted:

December 31, 1989 - January 27, 1990 2PA6/Z d/

Inspectors;W. T. OTd rs, Senior Re ident Inspector

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/ Dat4 Signed

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M. 3. Eesser Resident nspector

Date~ Signed A$//

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1. P. E. Hopkins, Resiidep Inspector

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Opte Signed Approved by: M.

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M.BGhymlock,yettionChief IDate Signed

Projects Branch 3A Division of Reactor Projects

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SUMMARY Scope:

This routine, resident inspection was conducted on site inspecting in the areas of review of plant operations; surveillance observation; maintenance observation; review of licensee event reports; and follow-up of previously identified items.

Results:

In the areas inspected, the licensee's programs were determined to be adequate.

i One strength was identified involving the licensee's identification of a problem with type TM GTE Sylvania contactors for electrical circuit breakers.

Two screws that hold the movable contact carrier in place were found to have worked loose. These breakers are located in both non-safety and safety related applications.

The licensee took prompt and immediate action to correct the problem on a short term and long term basis.

This appears to be a generic problem, as other plants within the Duke system had similar problems.

See paragraph 4c.

9003210007 900302 PDR ADOCK 05000413 Q

PDC

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One weakness was identified concerning Operations review of control room indicators.

For:a period of five_ months, between June and p

November 1989. control. room indication.of Unit 2. Auxiliary Building Filtered Exhaust. flow. reflected a-degraded-' flow rate. This degraded

. condition was not identified during shift - turnovers nor-'during monthly system. testing. even though.the meter indicated in the red or

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" degraded" area.

See paragraph 6.

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One violation was identified involving ' design control-measures.which affected the safety related Auxiliary-Building Ventilation System-(VA).

See paragraph 6.

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REPORT DETAILS 1.

Persons Contacted Licensee Employees l

• T. Owen Station Manager W. Beaver Performance Engineer B. Caldwell. Station Services Superintendent

• R. Casler. Operations Superintendent T. Crawford. Integrated Scheduling Superintendent

• J. Forbes. Technical Services Superintendent

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R. Glover Compliance Engineer T. Harrall. Design Engineering R. Jones. Maintenance Engineering Services Engineer F. Mack. Project Services Engineer W. McCollum, Maintenance Superintendent Other licensee employees contacted included technicians, operators.

mechanics, security force members, and office personnel.

NRC Resident Inspectors

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• W. Orders

• M. Lesser P. Hopkins

• Attended exit interview.

2.

Plant Operations Review (71707 and 71710)

The inspectors reviewed plant operations throughout the reporting a.

period to verify conformance with regulatory requirements. Technical Specifications (TS), and administrative controls. Control Room logs.

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Technical Specification Action Item Log. and the removal and restoration log were routinely reviewed.

Shif t ' turnovers were-observed to verify that they were conducted in accordance with approved procedures.

Daily plant status meetings were routinely

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attended.

The inspectors verified by observation and interviews, that the

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measures taken to assure physical protection of the facility met i

current requirements.

Areas inspected included the security organization, the establishment and maintenance of gates, doors, and isolation zones in the proper conditions, and that access control and badging were proper and procedures followed.

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In addition to the areas discussed above. the areas toured were observed for fire prevention and protection activities and radiolo-gical control practices.

The inspectors reviewed Problem Investi-gation Reports to determine if the licensee was appropriately documenting problems and implementing corrective actions.

b.

Unit 1 Summary Unit I had operated at 100% power for 130 days ur.til the unit was shut down on January 27, 1990, for a scheduled 65 day refueling outage, c.

Unit 2 Summary Unit 2 operated at 97% power until January 4. 1990 when the unit was shut down for an unscheduled outage to repair valve 2BB-19A. a steam generator blowdown inside containment isolation valve.. While performing an auxiliary safeguards test, valve 2BB-19A failed to open due to a short in the motor operated valve.

The motor was reraired, tested, and the unit returned to power on January 6,1990.

The unit maintained power operation throughout the rest of the reporting period.

d.

Pressurizer Safety Valve Reset Points While reviewing the lift setpoints for the Pressurizer Code Safety Valves (PSV) in response to recent industry calibration concerns, the licensee identified a potential problem with the reset point.

The licensee determined that the PSV ring settings, set to obtain stable lift performance to reduce valve chatter, may cause blowdown to be in excess of specified vahes.

Blowdown;. defined as the difference in lift and reseat pressure divided by-lift pressure, has typically been l

expected to be five percent.

However, results of EPRI and Duke l

Power testing showed blowdown up to 12 percent.

The licensee

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applied the higher blowdown value to the feedwater line break (FWLB)

6ccident safety analysis, the worst case scenario for PSV operation, to determine the consequences and identified the potential for the PSVs to remain open longer than originally analyzed.

The analysis determined that under certain conditions the Reactor Coolant System (RCS) would heat up and reach saturation conditions in the hot leg.

The highest saturation pressure is above the PSV blowdown setpoint and, therefore, the PSV would remain open.

Attempts at reducing

. pressure would simply cause flashing in the hot legs.

RCS pressure would not be reduced until RCS temperature was reduced at which time.

the PSVs would resea a l

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The licensee evaluated the consequences of sustained water relief through the PSVs following a FWLB.

The Westinghouse reference analysis does not explicitly model PSV behavior in terms of blowdown, but simply as holding RCS pressure at the PSV relief setpoint. The impact of increased blowdown on the PSV was judged a benefit in that sustained opening of the valve is better for it's integrity than repeated lif ts.

Dose and containment integrity consequences were bounded by the FWLB analysis and the only concern centered around the increased inventory loss.

The licensee concluded that core cooling is not challenged by the RCS inventory loss in that the heat sink.

from three intact steam generators is unaffected by the blowdown.

The licensee is currently reanalyzing the FWLB with less conservative assumptions in order to obtain lower RCS temperatures and is evaluating data from the PSV tests for reportability in accordance with 10 CFR 21.

A conference call between Duke Power Design Engineering. NRC Ril and NRR occurred on January 3.1990, to discuss the issue.

The results of the testing were deemed to be generic, however, the consequences as applied to Catawba and McGuire appeared minimal.

No violations or deviations were identified.

3.

Surveillance Observation (61726)

a.

During the inspection period, the inspector verified plant operations were in compliance with various TS requirements.

Typical of these requirements were confirmation of compliance with the TS for reactor coolant chemistry, refueling water tank, emergency power systems, safety injection, emergency safeguards systems, control room ventilation and direct current electrical power sources.

The inspector verified that surveillance testing was performed in accordance with the approved written procedures, test instrumentation was calibrated, limiting conditions for operation were met, appropriate removal and restoration of the affected equipment was accomplished, test results met acceptance criteria and were reviewed by personnel other than the individual directing the test, und that any deficiencies identified during the testing were properly reviewed and resolved by appropriate management personne,

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b.

The inspectors witnessed or reviewed the following surveillances:

PT/1/A/4200/028 Weekly Main Turbine Valve Movement PT/0/A/4410/01F Sprinkler Alarm System Test PT/1/A/4450/02 VA System Operability PT/1/A/4450/16 VA System Cumulation Purge Test PT/0/A/4450/08A Control Room Area Pressure A Test PT/2/A/4208/08 Post Accident Liquid Sample Test PT/2/A/4700/20B Unit 2 DG C02 Weekly Test PT/2/A/4450/11 VQ System Cumulation Purge Time PT/1/A/4300/028 DG 18 Operability Test PT/2/A/4350/02A DG 2A Operability Test PT/2/A/4600/02A Mode 1 Periodic Surveillance Item PT/1/B/4250/02K Pump Discharge Check Valve Test PT/1/A/4600/02A Mode 1 Periodic Sur"eillance items PT/1/A/4200/01E Upper Containment PAL LRT

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PT/1/A/4450/09C VF Performance Test PT/1/A/4150/23 VUCDT Increase Test PT/1/A/4150/010 NCS Leakage Calculation PT/1/A/4600/02A Mode 1 Periodic Surveillance-Test No violations or deviations were identified.

4.

Maintenance Observations (62703)

a.

Station maintenance activities of selected systems and components were observed / reviewed to ascertain that they were conducted in accordance with the requirements.

The inspector verified licensee conformance to the requirements in the following areas of inspection:

the activities were accomplished using approved -procedures, and

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functional testing and/or calibrations were performed prior to returning components or systems to service; quality control records

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were maintained; activities performed were accomplished by qualified f

personnel; and materials used were properly certified. Work requests j

were reviewed to determine status of outstanding jobs and to assure i

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that priority was assigned to safety-related equipment maintenance which may effect system performance.

I b.

The inspectors witnessed or reviewed the following maintenance activities:

3794 SWR Quarterly Battery Prevention Maintenance j

2 EBC (2)

52321 OPS Identify Ground on Battery 7331 PRF I/R 18861 Failure to Close

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6173 SWR Calibration on 0/G 1B VG System j

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c.

Sylvania Contact Carriers:

On January 4,1990, the licensee while troubleshooting a non-safety related 600V circuit breaker to determine the cause of its failure,

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identified loose mounting screws for the Sylvania manufactured contact carrier assembly.

Review of maintenance history indicated five examples at Catawba where contact carriers had failed due to loose mounting screws.

The contact carrier consists of movable contacts which are magnetically attracted to stationary contacts upon motor start demands.

The licensee was concerned with the potential inoperability of safety related applications in that the loose mounting screws could prevent the proper operation of the contact carrier.

On January 16 the licensee inspected eight of the 35 essential motor control centers (MCC) to determine the extent of the problem.

Each MCC contains 30-40 circuit breakers.

Six breakers were found to have loose screws on the contact carriers.

Some had completely

loosened and fallen out.

The screws do not incorporate any type of i

retaining device or locking feature and it is believed that vibration

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due to breaker operation caused the screws to loosen over time. The

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problem was localized only to Sylvania type TM, size 00, 0,1, and 2 i

contactors.

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The licensee immediately prepared a plan to inspect all remaining safety related circuit breakers at Catawba and the affected breakers at other Duke Power nuclear stations.

The plan included postponement

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of scheduled maintenance to facilitate visual inspection.

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breakers could be visually inspected while energized, however, any repairs had to be done with the equipment inoperable.

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The licensee's inspections identified the following failures: Unit 1 13/331; Unit 2 15/326 for an overall failure rate of 4.3 percent.

The failures typically amounted to one or both screws loose or one j

screw completely backed out.

The licensee has initiated long term corrective action which includes replacing the mounting screws with nylon patched screws for better thread engagement. Unit 1 screws are currently being replaced during the refueling outage.

A monthly inspection has been initiated on Unit 2 to verify operability and trend the failure rate until the

unit enters its next extended outage.

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The licensee is also reporting the defect in accordance with l

10 CFR 21.

The licensee determined that the manufacturer informed one company (non-nuclear industry) of the problem in 1982, however, diagnosed it as a localized problem.

The licensee's response to this issue is considered effective in that the problem was identified, the scope determined, corrective actions were swiftly implemented and the event properly reported.

No violations or deviations were identified.

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5.

Followup on Previous Inspection Findings (97201 and 927202)

(Closed) Inspector Follow Up Item 413/89-21-06:- Hydrogen Skimmer Fan Test Effects on Ice Condenser Bypass Flow.. The licensee completed its investigation with assistance from Westinghouse as to the effect on ice condenser bypass flow during performance of the fan test.

Sensitivity studies referenced in FSAR Table 6.2.1.7 showed that when the bypass area was varied up to an order of magnitude greater than the 5.0 square feet, peak containment pressures following a t.0CA did not significantly change.

The licensee revised the procedure to allow the fan to operate with its dampers open far a maximum of five minutes. Considering these factors and typical allowable outage times for various Technical Specification parameters, the test procedure is considered to be acceptable.

This item is closed.

(Closed) P2189-01:

Brown Boveri Kline K-225 Through K-2000 Circuit Breakers Delivered Prior to 1974 Need Rebound Spring Added to slow Close Pin.

This 10CFR21 Report was evaluated by Duke Power Company and determined to be applicable to the Oconee and McGuire units but not to the-Catawba units.

Based on this the item is closed.

No Violations or deviations were identified.

6.

Auxiliary Building Ventilation Inoperability (93702)

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Summary

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At 5:40 a.m., on November 11, 1989, during a review of Control Room indications. operators observed that the Unit 2 Auxiliary Building Ventilation (VA) filtered exhaust flow was indicating low. Unit 2 was in Mode 1. Power Operation, at 98% power at the time of discovery.

The system was declared inoperable and Technical Specification 3.0.3.

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was entered at 5:40 p.m. that afternoon when the low flow condition

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was confirn'ed.

Air Flow Monitor Device. 2ABFX-AFMD-1. was found to be clogged with lint and cleaned. At 6:25 p.m. Technical Specifica-tion 3.0.3 was exited after all flows and indications were verified

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to be satisfactory.

Subsequent investigation found that the VA l

system had been inoperable for five months.

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Eackground The Auxiliary Building Ventilation System is designed to provide a suitable environment for equipment operation and personnel access during both normal and accident conditions.

The Auxiliary Building

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Filtered Exhaust ( ABFX) System, a subsystem of VA. consists of two trains per unit with associated fans, filters and ducting.

An Air Flow Monitor Device (AFMD) is located in the common duct downstream of each Unit's ABFX subsystem to measure the flow to the respective unit vent. A second AFMD is located upstream of each Unit's filters.

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The AFMDs consist of a flow straightener section located in the duct, instrumented with a static pressure tap and velocity pressure Pitot tubes.

The velocity Pitots in conjunction with the static reference produce an average velocity from which the flow is indicated by flow indicators, 1(2)VAP5280, in the Control Room.

On May 9,1989, with Unit 2 in Mode 5. during a retest of a VA duct section which had been replaced. Filtered Exhaust Train 2A flow ~ was found below the single fan flow rate of 30,000 CFM + 10%. Air flow monitor device 2ABFX-AFMD-7, (upstream of the _ fil~tered exhaust units) was found to be clogged with lint, and was cleaned on May 12.

Train 2A was retested and found acceptable later that same day.

Neither prompt action to determine the cause of the problem nor corrective actions to prevent recurrence were taken by the licensee.

This constitutes a violation of the requirements specified in 10 CFR 50 Appendix B, Criterion XVI, Corrective Actions, and is one of four examples which in the aggregate form Violation 50-414/90-03-01.

System flow was monitored between May 12 and May 25.

When degra-dation became apparent again on May 25, a work request was issued to reinspect and reclean 2ABFX-AFMD-2.

It was determined at that time that the lint was coming from the non-safety related Radiation Protection (RP) clothes dryers. (Unit 1 VA does not receive any input from the clothes dryers.) This is considered to be a design inadequacy in that the interaction of these non-safety related components (clothes dryers) with the safety related portion of the VA ~

system was not adequately considered in the original system design.

This is a violation of the requirements of 10CFR50 Appendix B.

Criterion III Design Control, in that measures established for the suitability and selection of equipment and the identification and control of design interfaces were inadequate to prevent the non-safety related component rendering the safety related system inoperable.

This constitutes the second of four examples constitu-ting Violation 50-414/90-03-01.

Problem Investigation Report (PIR) 2-C89-0211 was written on May 30, 1989 to address the problem described above. The resolution included completion of a clothes dryer filter modification on May 31, 1989 and cleaning of 2ABFX-AFMD-2 on a weekly basis. During the five months following the issuance of the PIR, 2ABFX-AFMD-2 was inspected and cleaned weekly.

Lint was found during each inspection.

The lint found in these subsequent inspections was assumed to be residual lint coming from the VA ductwork.

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Event Description On November 11,1989, at 5:40 a.m. Control Room operators noticed that 2VAP5280, flow indicator for 2ABFX-AFMD-1 (downstream of the filtered exhaust units), was reading approximately 30,000 cfm.

Half of the normal two fan flow.

Unit 2 was in Mode 1, Power Operation, at the time of discovery.

This observation was turned over to the day shift at 7:00 a.m.

The day shift investigated the

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low flow indication by checking the VA system alignment and inspecting the VA discharge duct.

The fans were run in different'

combinations to determine the effect on 2VAP5280, which was found to

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read approximately 18,000 cfm (normal is 30.000 cfm) with either fan off.

At 1:10 p.m. a work request was written to investigate the low

reading on 2VAP5280.

A local reading at 2ABFX-AFMD-1 with a manometer also indicated approximately 30,000 cfm flow with both fans

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running.

The Unit 2 VA system was declared inoperable at 5:40 p.m.

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and Technical Specification 3.0.3 was entered.

Both ABFX fans were

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removed from service and work commenced to inspect Air Flow Monitor Device 2ABFX-AFMD-1.

Approximately one third of the air flow monitor flow straightener openings were found clogged with lint. The.

AFMD was cleaned and the Unit 2 filtered exhaust fans were returned to service.

At 6:25 p.m., Technical Specification 3.0.3 was exited after all flows and indications were verified satisfactory.

The clothes dryer filter modification installed per PIR 2-C89-0211 had not corrected the bypass problem.

The weekly cleanings of 2ABFX-AFMD-2 confirmed that the modification was inadequate. Even with the additional information accumulated by the weekly cleanings, prompt, comprehensive corrective actions were not taken to ensure that the cause of the continued lint accumulation was determined nor were corrective actions taken to preclude recurrence. This constitutes the third of four examples constituting Violation 50-414/90-03-01. This lack of effective corrective actions resulted in the VA system being inoperable for a period of five months as described below, d.

Inoperability Review An extended period passed before the degraded condition of the Unit 2 filtered exhaust system was recognized.

A review of the data taken during the performance of monthly surveillances from May through November, 1989 produced the following two fan flow data:

Date Flow (2VAP5280, cfm)

5/13/89 56,000 6/10/89 57,000 7/7/89 50,000 8/5/89 44,000 9/2/89 41,000 9/30/89 36,000 10/27/89 31,000 11/25/89 58,000 This data indicates that the flow from the Unit 2 filtered exhaust fans fell below the Technical Specification limit 60,000 cfm +/- 10%

sometime between June 10 and July 7,1989.

This in turn indicates that the VA system was inoperable for a period of approximately five

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months.

Technical Specification 3.7.7. Auxiliary Building Filtered Exhaust System requires that two independent trains of the Auxiliary Building Filtered Exhaust System be operable in Modes 1. 2, 3. and 4.

With one train of the Auxiliary Building Filtered Exhaust System inoperable, the inoperable train must be restored to operable status within 7 days or the unit must be in at leat 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-following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

Both trains of the Unit 2 ABFX system were inoperable-for a period of approximately 5 months when the unit operated in Modes 1. 2, 3. or 4.

This constitutes a violation and is the. fourth of four examples identified in this report which in the aggregate form Violation 50-414/90-03-01.

It is significant to note-that the low flow indication was not detected for a five month period neither during operator control board reviews performed at each shift turnover nor during monthly testing. This is identified as a weakness.in the area of operator awareness and knowledge of operating status.

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Safety Analysis During accident conditions the two VA filter trains, operate as two 100 percent capacity subsystems. Upon receipt.of a signal, isolation dampers will close. shutting off air flow from all areas of the Auxiliary Building except for the rooms which contain safety related pumps which are part of the Emergency Core Cooling System (ECCS). While normal flow was degraded from about 30.000 cfm (per fan) to 15.000 cfm (per fan), the emergency flow would have decreesed by about 1%.

Duke calculation CNC-1211.00-00-0089 shows the effect on emergency flow would have been a decrease from 6540 cfm to approximately 6500 cfm.

This flow is adequate to negatively pressurize the ECCS pump rooms and. therefore, filter all air exhausted from these rooms. This indicates that although the VA system was inoperable pursuant to the TS requirements. the system could have performed its intended safety function.

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Corrective Actions It should be noted that once this problem was completely identified, the licensee initiated extensive corrective actions. These included but were not limited to:

A permanent solution to correct the interaction between the Rp clothes dryers exhaust and the Unit 2 VA system will be developed by Design Engineering and Catawba Station personnel.

Standing Work Requests to perform weekly inspections of'

2ABFX-AFMD-1 and 2ABFX-AFMD-2.

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Increased surveillance of 2VAPS280 until the lint problem has

been permanently corrected, j

The incident was covered in the monthly Shift Supervisors

• meeting to reinforce the need to initiate prompt corrective action for abnormal indications.

Dryer filter cleaning frequency was increased.

• The VA duct will be cleaned.

Flow criteria will be added to the appropriate ventilation procedures in order to alert operators of discrepancies in flow.

Procedures will be revised to provide documentation of control

board review for abnormal indications and notification of supervision.

Additional training will be provided to Operators on plant indication awareness.

• Cleaning and/or inspection, as appropriate, of air flow monitors for dust and lint accumulation on other safety related ventilation systems will be conducted annually, g.

Conclusion A design inadequacy allowed a non-safety related component / system to interface with and render VA inoperable, a safety related system.

When it was determined on May 9 and May 25, 1989 that the VA system had become degraded by lint accumulation, prompt comprehensive corrective actions were not taken to identify the cause of the condition or correct the situation to preclude recurrence.

This ultimately led to the Unit 2 VA system being inoperable for a period of five months. Singularly and collectively.these inadequacies violate NRC requirements and in the aggregate constitute Violation 50-414/90-03-01.

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7.

Exit Interview

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The inspection scope and findings were summarized on February 6,1990.

with those persons indicated in paragraph 1.

The inspector described the areas -inspected and discussed in detail. the inspection findings -listed

below.

No dissenting comments-were received from the licensee.

The.

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- licensee did not identify as proprietary any.of the materials provided to -

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or reviewed by the-inspectors during this inspection.

Item Number Description and Reference

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414/90-03-01 Failure to-take prompt and timely corrective action on inoperable 2ABFX~ System

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