RBG-45095, Responds to NRC Re Violations Noted in Insp Rept 50-458/99-07.Corrective Actions:Fuel Pump Coupling Was Reworked Using Loctite & Division I DG Was Returned to Operable Status

Responds to NRC Re Violations Noted in Insp Rept 50-458/99-07.Corrective Actions:Fuel Pump Coupling Was Reworked Using Loctite & Division I DG Was Returned to Operable Status

ML20216E490
Person / Time
Site:	River Bend
Issue date:	09/07/1999
From:	King R ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
50-458-99-07, EA-99-158, RBF1-99-0257, RBG-45095, NUDOCS 9909140163
Download: ML20216E490 (14)

Text

,

EntIrgy Operations, Inc.

N River Bend Station

' ({/' 5485 U.S. Highway 61

', i* D* P. O. Box 220 ,

St. Francsville. LA 70775 I Tuf 225 336 6225 Fax 225 6'15 5068 f j

Rick J. King )

September 7,1999 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001

Subject:

Response to Apparent Violations in IR 50-458/99-07 EA 99-158 River Bend Station License No. NPF-47 Docket No. 50-458 File Nos.: G9.5, G15.4.1 RBG-45095 RBF1-99-0257 Ladies and Gentlemen:

Entergy Operations, Inc. (EOl) appreciates this opportunity to respond to the apparent violations described in NRC Inspection Report (IR) 99-07 as requested in NRC's letter dated August 23,1999. This letter gave EOl the choice of either  !

responding in writing to the apparent violations, or attending a pre-decisional  !

enforcement conference. EOl b61ieves that this method of addressing issues is l appropriate for situations in which the facts of the issue are well understood by both EOl and NRC.

A response to the apparent violations as requested in your letter is provided in 1 Attachment A. The apparent violations were a result of a period in which the l Division I emergency diesel generator was inoperable for a time in excess of that allowed by the River Bend Station (RBS) Technical Specifications (TS). The first apparent violation deals with inadequate work instructions related to maintenance performed on the diesel generator. This was determined by our root cause analysis to be one of the causes of the second violation, a violation of the Technical Specification for the effected equipment. Because of the close relationship between the two violations, one response is being provided to address both violations. Commitments contained in this letter are summarized in Enclosure 1.

-gj 9909140163 990907 PDR

/> j G ADOCK 05000458 /

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r y _ R:sponse to Apparent Violations in IR 50-458/99-07

, y River Bend Station

' License No. NPF-47 Docket No. 50-458 1 Page2 of 3

' RBS management understands the significance of the issues described in the IR.

Attachment B provides our evaluation of the safety significance of the event.

While the condition resulted in a reduction in the defense-in-depth of safety systems provided in the design of RBS, our risk analysis found the condition to be non-risk significant.

We believe, based on the facts surrounding the event and our review of the Enforcement Policy (NUREG-1600), that no civil penalty is warranted. EOl should be given credit for identification of the issue and for prompt and thorough corrective actions following discovery of the problem. Our regulatory perspective addressing enforcement factors described in NUREG-1600 is provided in

~ Attachment C. This perspective addresses safety significance, credit for identification, and credit for corrective actions. However, in this case, we are concerned that the docketed NRC correspondence on the subject does not clearly describe, in detail, the causes determined or corrective actions taken by EOI. Therefore, we request that NRC consider holding a pre-decisional enforcement conference if there is a disagreement with the facts or conclusions presented in thir, letter, which show that no civil penalty is warranted.

RBS management recognizes the importance'of diesel generator performance to the safe operation of the station, and are taking aggressive actions to address issues which impact the performance of this equipment. A multi-discipline team i led by Engineering has been formed to directly oversee and correct problems identified in our assessment. This effort is focused on improving the reliability of the diesel generators. We request a separate meeting this fall to discuss our focused efforts and results of the diesel generator improvements.  !

l Should you have any questions regarding the attached information, please I contact Mr. David Lorfing of my staff at (225) 381-4157. I Sincerely, RJK/dhw Affirmation '

Enclosure 1 Attachments - i h

R:sponse to App r nt Violations in IR 50-458/99-07 Rivsr B3nd St: tion License No. NPF-47 Docket No. 50-458 Page.3 of 3 cc: U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 )

Arlington, TX 76011 NRC Sr. Resident inspector P. O. Box 1050 St. Francisville, LA 70775 NRR Project Manager, Robert Fretz U.S. Nuclear Regulatory Commission M/S OWFN 04DO3 i Washington, D.C. 20555 i i

- Director, Office of Enf arcement U. S. Nuclear Regulatory Commission Washington, D. C. 20555-0001 0'

9,

BEFORE THE s

. UNITED STATES NUCLEAR REGULATORY COMMISSION LICENSE NO. NPF-47 DOCKET NO. 50-458 IN THE MATTER OF ENTERGY GULF STATES, INC. AND ENTERGY OPERATIONS, INC.

AFFIRMATION 1, Rick J. King, state that I am Director - Nuclear Safety Assurance of Entergy Operations, Inc., at River Bend Station; that on behalf of Entergy Operations, Inc., I am authorized by Entergy Operations, Inc., to sign and file with the Nuclear Regulatory Commission, this response to Apparent Violations 50-458/99-07-01 and 02; that I signed this letter as Director - Nuclear Safety Assurance at River Bend Station of Entergy Operations, Inc.; and that the statements made and the matters set forth therein are true and correct to the best of my knowledge, information, and belief.

ls .

/ Rick J g'

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STATE OF LOUISIANA PARISH OF WEST FELICIANA SUBSCRIBED AND SWORN TO before me, a Notary Public, commissioned in and for the Parish and State above named, thbs 1A day of kahh ,

1999.

(SEAL)

OJLcuutio J. /4uto t

- Claudia F. Hurst Notary Public My commission expires with life

^

. . 1

. Encigsure 1 Commitment identification Form

Subject:

Response to Apparent Vioations 50-458/99-07-01 and 02 RBF1-99-0257 RBG-45095 Date: September 7,1999  ;

l 3 COMMITMENT ' ONE-TIME CONTINUING ACTION COMPLIANCE An evaluation of past work on the Division I and ll x DGs will be conducted to assess compliance with SiMs. This review is scheduled to be completed by September 30,1999. '

An evaluation of Division lli DG will be performed to x confirm the adequacy of vendor documentation.

A sampling of vendor documents on other systems x and equipment has been initiated to determine whether this type of condition exists elsewhere.

Training on taper pin staking techniques will be x incorporated into continuing maintenance na.ning.

An effectiveness review of the corrective actions x taken to address the conditica of the Division I and 11 DGs, as we!! as training related to this event, will be performed.

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Attachment A

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i l Respanse to Apparent Violations in IR No. 50-408/99-07 APPARENT VIOLATIONS

1. An apparent violation of 10 CFR Part 50, App. B, Criterion V, was identified regarding failure to provide adequate work instructions for maintenance of the Division I emergency diesel generator.

2. An apparent violation of Technical Specifications 3.8.1.1b and c was identified regarding Divisions I and 11 emergency diesel generator inoperability. As a result of improper maintenance on the Division I emergency diesel generator j fuel oil pump coupling, the Division i emergency diesel generator was inoperable for approximately 30 days and 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. During this period, the Division ll emergency diesel generator was removed from service for approximately 26 hours3.009259e-4 days <br />0.00722 hours <br />4.298942e-5 weeks <br />9.893e-6 months <br />. l River Bend admits to the apparent violations.

REASON FOR VIOLATIONS i

On February 24,1999, during a scheduled maintenance outage of the Division I diesel generator (DG), repairs were performed to replace a leaking mechanical seal on the overspeed drive shaft. The scope of this task required removal and reinstallation of the fuel pump drive coupling.

The work was completed without apparent incident. The next day, the DG was operated per the applicable surveillance test procedure to satisfy post-maintenance retest requirements, and to restore the DG to an operable status. The surveillance was completed successfully.

On March 23,1999, the DG was operated for a scheduled surveillance test. Fifty-five minutes into the one-hour run, the operator tripped the DG when a " Generator Output High" alarm was received in the Main Control Room, and the electrical load on the generator became erratic.

Subsequent investigation revealed that a taper pin had come out of the fuel pump drive coupling, allowing the coupling to become loose and move on its shaft. This resulted in decreased fuel pump output. When interviewed, the mechanic that installed the pin stated that he did not countersink the taper pin any noticeable amount, but thought that sufficient metal was disturbed by the staking to hold it in place.

4 Further investigation showed that the DG vendor manual states that the fuel pump coupling should be assembled using Loctite 680 compound, in addition to the staking. The Loctite was not used during assembly on February 24. On March 25,1999, the fuel pump coupling was reworked

.'using Loctite in accordance with the vendor recommendations The DG .

- was then successfully operated using the applicable surveillance test procedure.

'The DG_ vendor, Cooper Energy Services (CES), was contacted during the investigation, and provided the follow lng pertinent information:

. . .The purpose of using Loctite in the assembly of the accessory

' drive, overspeed, and fuel booster pump drive couplings to their respective shafts is to fill any clearance that may exist between the shaft and bores. If the hubs assemble to the shafts with an interference fit, then the Loctite provides a small measure of increased protection against loosening. Use of the Loctite on the taper pin in addition to the staking is a " belt and suspenders" measure for added assembly security.

. Service information Memo (SIM) 363 was issued, including the Loctite application on the fuel booster pump drive coupling and staking the pin in two places, on January 23,1984.

b e The vender was not aware of any similar applications in which the taper pin had come loose.

.. The maintenance planner was unaware that the Loctite was recommended on this coupling when the work instructions were prepared.

- The use of Loctite is specified in SIM-363, located in the vendor manual. j There were no indicators or cross-references in the vendor parts  !

' list / drawings used to prepare work instructions that referred to the SIM or  ;

the need to use Loctite. Consequently, maintenance was performed on l this component without the use of Loctite. The same written work  ;

- instructions have been used by CES and by River Bend personnel to l assemble this component on multiple occasions. When the maintenance l was performed on two occasions by CES, Loctite was used during j assembly and documented in the work documentation sheets. When it was rerformed by River Bend personnel, Loctite was not used.

The taper pin staking is the primary means of retaining the pin in place. If the staking fails, the security of the pin is lost without Loctite.

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l Two causes of this event were identified: l

. The staking of the coupling taper pin was inadequately l performed. The taper pin was not sufficiently countersunk prior l to staking the surrounding metal.

. The maintenance work instructions did not specify the use of Loctite.

The primary document used for planning the work (i.e., the parts list /

drawings) did not specify the use of Loctite, or refer to the applicable SIM.

A contributing factor in this event is the lack of specific training in taper pin staking techniques in the maintenance training program.

1 CORRECTIVE ACTIONS TAKEN AND RESULTS ACHIEVED l The following corrective actions I ave been completed:

. The fuel pump coupling was reworked using Loctite and the division l l diesel generator was returned to an operable status. l

. The Division 11 DG was evaluated for possible common mode failure due to inadequate taper pin staking. The fuel pump coupling was examined, and the taper pin was found to be adequately staked and operable without the Loctite.

. The Division 111 Electro-Motive Division DG was evaluated and, based on the use of a different type of coupling by a different manufacturer, it is not susceptible to this type of failure.

. A safety significance / risk assessment of the DG was performed. This assessment is documented in the RBS corrective action program. l Attachment B of this letter provides a summary of that assessment. )

. A standard job plan has been developed for this task to include the use 1 of Loctite. j

. Maintenance planners and mechanics have been briefed on the root cause analysis of this event.

. ECl has updated the DG vendor technical information to improve the  :

correlation with the SIMs. l

. A maintenance training module has been developed to specifically address staking techniques on taper pins.

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CORRECTIVE ACTIONS TO PREVENT RECURRENCE I The following actions will be completed:

. An evaluation of past work on the Division I and ll DGs is being conducted to assess compliance with SIMs. This review is scheduled to be completed by September 30,1999.

. An evaluation of Division lli DG will be performed to confirm the adequacy of vendor documentation.

. A sampling of vendor document types on other systems and l equipment has been initiated to determine whether this type of condition exists elsewhere.

. Training on taper pin staking techniques will be incorporated into )

continuing maintenance training.

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. An effectiveness review of the corrective actions taken to address the condition of the Division I and 11 DGs, as well as training related to this event, will be performed. j DATE WHEN FULL COMPLIANCE WILL BE ACHIEVED

~ Compliance was achieved on March 25,1999, when the Division i diesel generator was restored to an operable condition.

Attachment B Safety Significance in order to assess the safety significance of this event, a review of concurrent equipment outages in redundant safety systems was perfonned for the period February 24 to March 24,1999. Four equipment outages in this period, in addition to the Division I DG, were evaluated. The components that were out of service at some time during the period in question were:

. Division ll diesel generator (25 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> 54 minutes total over two outages),

e Reactor core isolation cooling system (11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> 21 minutes) and,

. Service water pump P2C, supplying Division 3 diesel generator, (6 days 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br />).

At no time did these four outages coincide with each other.

A common mode failure analysis for the Division ll DG was performed immediately following the event. The recent maintenance history of the fuel pump was reviewed, and the fuel pump drive coupling was closely examined. The coupling had last been assembled on July 2,1996, and the maintenance work instructions did not specify the use of Loctite. Upon examination, however, the taper pin was found to be adequately restrained, such that it was not susceptible to becoming loose.

Additionally, the Division lll DG has a different type of drive coupling on its main fuel pump. It is not susceptible to the failure experienced on the Division I DG.

While the Division I DG was inoperable, it was capable of operation with an alternate fuel supply. The DG is equipped with an electrically driven fuel booster pump powered from the station's non-safety 125 volt DC system. Based on actual test data, the pump will start on an emergency start signal, and can run to support diesel operation as long as DC power is available. The non-safety station batteries are designed for a two-hour capacity following isolation of the battery charger from the DC bus by a loss of coolant accident signal.

The significance of this condition was the reduction of defense-in-depth of systems used to mitigate accidents analyzed in the River Bend USAR. One specific example is that the River Bend ECCS analysis assumes that two of three emergency Diesel Generators operate in response to plant transients, but there was a limited period of time (i.e., less than 26 hours3.009259e-4 days <br />0.00722 hours <br />4.298942e-5 weeks <br />9.893e-6 months <br />) in which only Division lli DG was operable. To further evaluate this significance, a probabilistic safety assessment for the condition was performed.

V I-c ,

The instantaneous risk associated with each of these instances of concurrent

,' equipment outage was calculated and determined to be acceptable, based on a l . quantitative evaluation of the Equipment Out-of-Service Monitor. Also, the

!- incremental risk was evaluated using the methodology for temporary changes in the EPRI Probabilistic Safety Assessment Applications Guide (EPRI TR-105396).

The calculated incremental risk values were found to be non-risk significant.

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Attachment C Regulatory Perspective in response to the inspection report, we have reviewed the identified issues against the criteria provided in NUREG-1600, " General Statement of Policy and Procedures for NRC Enforcement Actions." The apparent violations as described in IR 99-07 involved a failure to comply with the action statement for a Technical Specification Limiting Condition for Operation. NUREG-1600 includes this as an '

example of a severity level 111 violation. In this specific case, the Division I DG was inoperable for a period of time that exceeded the action statement time period. However, the NRC should consider risk as a basis to deviate from the j NUREG-1600 examples. In this case, the results of our risk significance {

evaluation, as discussed in Attachment B, indicates that a severity level IV I violation is warranted based on the condition being non-risk significant. )

l If NRC decides that a severity level ill violation is warranted, we conclude that no !

civil penalty should be assessed. This is based on 1) credit for identification,2) l immediate and comprehensive corrective actions, 3) minimal actual safety significance, and 4) absence of willfulness.

Credit for Identification Following the re-assembly of the fuel pump drive coupling on February 24, the appropriate post-maintenance test procedure was successfully performed to demonstrate the operability of the diesel generator. This test included a one hour surveillance run of the DG. As the pump coupling is not an item visually inspected by an operator during routine on-shift equipment monitoring, the next regularly scheduled surveillance test was the earliest possible opportunity to discover the discrepancy. The time of failure on March 23,1999, was the first opportunity to discover the condition after completion of the original maintenance work on the equipment.

Our review of NUREG-1600 indicates that this issue should be treated as

" revealed through an event." Credit for identification should be given as the condition was discovered through a "!icensee self-monitoring effort" which is intended to discover conditions such as this. In this case, the condition was discovered by a planned surveillance test. NUREG-1600 identifies a surveillance test as an example of a licensee self-monitoring effort. It further states that identification credit should normally be given when the condition occurred as a result of conducting a surveillance. In addition, based on review of the circumstances, there were no reasonable previous opportunities to discover the condition. A post-maintenance test is specified to reveal any performance

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deficiencies following a maintenance activity, and no problems were identified.

. The first reasonable opportunity to discover this condition was during the March 23,1999, scheduled surveillance test on the Division 1 DG. The vendor SIM 363 document was issued more than two years ago, and does not represent a current reasonable opportunity to identify this condition.

Immediate and Comprehensive Corrective Actions immediately upon discovery of the condition, actions were taken to restore operability of the Division l DG. The coupling was reworked and the availability of the DG was restored. A common mode failure analysis for the Division ll DG was performed. This analysis found the Division ll DG to be operable in the as-found condition. An extensive root cause analysis was performed and reviewed by plant management as part of the River Bend Station (RBS) corrective action program. This analysis not only identified concerns with adequacy of staking, but also discovered contributing factors related to adequacy of vendor technical information. Details concerning the root cause analysis and corrective action plan are documented in the RBS corrective action program and described in Attachment A to this letter.

Our review of NUREG-1600 indicates that credit for prompt and comprehensive corrective action should be given for the subject condition. The problem with the Division I DG was immediately corrected. Additional actions are being implemented to prevent recurrence of similar conditions with not only the DGs.

Also, a sampling of vendor document types on other systems and components has been initiated. We believe these actions address the underlying root cause, and are sufficient to prevent recurrence of similar violations.

Actual Safety Significance The significance of this condition was the reduction of defense-in-depth of systems used to mitigate accidents analyzed in the River Bend USAR.

An evaluation of other equipment outages during the period that the Division I DG was inoperable was performed to assess the safety significance of this event.

The instantaneous risk associated with each instance of concurrent equipment outage were calculated and determined to be acceptable, per the RBS Equipment Out-of-Service Monitor. Also, the incremental risk was evaluated  !

using the methodology for temporary changes in the EPRI Probabilistic Safety Assessment Applications Guide (EPRI TR-105396). The calculated incremental risk values were found to be non-risk significant.  ;

Absence of Willfulness The root cause analysis found no instance of intentional noncompliance with or disregard of station procedures. The mechanic made a legitimate effort to ]

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.,.g+< q perform the task of installing the pump coupling taper pin per the work  ;

instructions. The maintenance planners made a good-faith effort to provide  ;

appropriate work instructions for the task. '

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