IR 05000255/2011013

IR 05000255-11-013; 09/26/2011 - 10/05/2011; Palisades Nuclear Plant; Other Activities

ML11301A025
Person / Time
Site:	Palisades
Issue date:	10/28/2011
From:	Stephanie West Division Reactor Projects III
To:	Vitale A Entergy Nuclear Operations
References
EA-11-227 IR-11-013
Download: ML11301A025 (17)

Text

ctober 28, 2011

SUBJECT:

PALISADES NUCLEAR PLANT, NRC INSPECTION REPORT 05000255/2011013 PRELIMINARY WHITE FINDING

Dear Mr. Vitale:

On October 5, 2011, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at your Palisades Nuclear Plant. The enclosed report documents the results of this inspection, which were discussed on October 5, 2011, with you and other members of your staff.

The inspection examined activities conducted under your license as they relate to safety and compliance with the Commissions rules and regulations and with the conditions of your license.

The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel.

This report documents a finding that has preliminarily been determined to be White or a finding of low-to-moderate increased safety significance. As documented in Section 4OA3 of this report, the turbine driven auxiliary feedwater pump failed during testing on May 10, 2011.

Based on our assessment of the information, the pump was susceptible to failure for a period longer than allowed by Technical Specifications. This finding was assessed based on the best available information, including influential assumptions, using the applicable Significance Determination Process.

Upon identification of this issue, you declared the pump inoperable. Troubleshooting by your staff identified that improper greasing of a knife edge contributed to the pumps failure.

Your staff removed the grease and tested the pump satisfactorily. Because of the actions taken to restore the pump to operable status, no current safety concern exists.

This finding is also an apparent violation of NRC requirements and is being considered for escalated enforcement action in accordance with the NRC Enforcement Policy.

The current Enforcement Policy can be found at the NRCs Web site at http://www.nrc.gov/reading-rm/doc-collections/enforcement.

In accordance with Inspection Manual Chapter (IMC) 0609, we intend to complete our evaluation using the best available information and issue our final determination of safety significance within 90 days of the date of this letter. The Significance Determination Process encourages an open dialogue between the NRC staff and the licensee; however, the dialogue should not impact the timeliness of the staffs final determination.

Before the NRC makes its enforcement decision, we are providing you an opportunity to either:

(1) present to the NRC your perspectives on the facts and assumptions used by the NRC to arrive at the finding and its significance at a Regulatory Conference, or (2) submit your position on the finding to the NRC in writing. If you request a Regulatory Conference, it should be held within 30 days of the receipt of this letter and we encourage you to submit supporting documentation at least 1 week prior to the conference in an effort to make the conference more efficient and effective. If a conference is held, it will be open for public observation. The NRC will also issue a press release to announce the conference. If you decide to submit only a written response, such submittal should be sent to the NRC within 30 days of the receipt of this letter. If you decline to request a Regulatory Conference or to submit a written response, you relinquish your right to appeal the final SDP determination; in that, by not doing either you fail to meet the appeal requirements stated in the Prerequisite and Limitation Sections of Attachment 2 of IMC 0609.

Please contact John Giessner at (630) 829-9619 in writing within 10 days of the date of this letter to notify the NRC of your intended response. If we have not heard from you within 10 days, we will continue with our significance determination and enforcement decision.

The final resolution of this matter will be conveyed in separate correspondence.

Since the NRC has not made a final determination in this matter, no Notice of Violation is being issued for this inspection finding at this time. Please be advised that the number and characterization of the apparent violation described in the enclosed inspection report may change as a result of further NRC review. In accordance with 10 CFR 2.390 of the NRC's "Rules of Practice," a copy of this letter, its enclosure, and your response (if any) will be available electronically for public inspection in the NRC Public Document Room or from the Publicly Available Records System (PARS)

component of NRC's document system (ADAMS). ADAMS is accessible from the NRC Website at http://www.nrc.gov/reading-rm/adams.html (the Public Electronic Reading Room).

Sincerely,

/RA/

Steven West, Director Division of Reactor Projects Docket No. 50-255 License No. DPR-20

Enclosure:

Inspection Report 05000255/2011013 w/Attachment: Supplemental Information

REGION III==

Docket No: 50-255 License No: DPR-20 Report No: 05000282/2011013 Licensee: Entergy Nuclear Operations, Inc.

Facility: Palisades Nuclear Plant Location: Covert, MI Dates: September 26 through October 5, 2011 Inspectors: J. Ellegood, Senior Resident Inspector T. Taylor, Resident Inspector L. Kozak, Senior Reactor Analyst Approved by: John B. Giessner, Chief Branch 4 Division of Reactor Projects Enclosure

SUMMARY OF FINDINGS

IR 05000255/2011013; 09/26/2011 - 10/05/2011; Palisades Nuclear Plant; Other Activities.

This report covers the review of a failure of a turbine driven auxiliary feedwater (TDAFW) pump.

The inspectors identified one apparent violation with a preliminary significance of

White.

The significance of most findings is indicated by their color (Green, White, Yellow, Red) using Inspection Manual Chapter (IMC) 0609, Significance Determination Process (SDP).

Findings for which the SDP does not apply may be Green or be assigned a severity level after NRC management review. The NRCs program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, Reactor Oversight Process,

Revision 4, dated December 2006.

NRC-Identified

and Self-Revealed Findings

Cornerstone: Mitigating Systems

• Preliminary

White.

A self-revealed finding of low to moderate safety significance and associated Apparent Violation (AV) of 10 CFR Part 50 Appendix B, Criterion V,

Instructions, Procedures and Drawings, occurred for the licensees failure to follow procedures for lubrication of linkages on the TDAFW pump overspeed trip device.

Specifically, during a maintenance window the licensee greased a knife edge on the trip mechanism. The greasing of the knife edge contributed to a trip of the pump on May 10, 2011, as well as rendering the pump inoperable for a period of time in excess of what is allowed by Technical Specifications (TSs). After identification of the grease, the licensee removed the grease, restored the pump to an operable status, and initiated condition report (CR) PLP-2011-02350.

The inspectors concluded that the finding was more than minor because it was associated with the equipment reliability and performance attributes of the Mitigating Systems Cornerstone. In addition, this performance deficiency impacted the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the TDAFW pump could not reliably perform its mitigating function. The inspectors performed a Phase 1 SDP evaluation and determined that a Phase 2 evaluation was required because this finding represented an actual loss of safety function of a single train of equipment for greater than the TS allowed outage time. The inspectors performed a Phase 2 evaluation using the pre-solved SDP worksheets for Palisades and determined that this finding screened as

Yellow.

In order to realistically assess the significance, IMC 0609 required a Phase 3 SDP evaluation. Based on the Probabilistic Risk Analysis conducted by the Senior Reactor Analyst (SRA), a Significance and Enforcement Review Panel reached a preliminary determination the finding was of low to moderate (White) safety significance. The finding occurred, in part, due to a worker making a change to a work instruction without following the process for procedure revisions. Therefore, the inspectors assigned a cross cutting aspect of H.1(a),

risk-significant decisions using a systematic process. (Section 4OA3)

Licensee-Identified Violations

No violations of significance were identified.

REPORT DETAILS

4OA3 Follow-Up of Events and Notices of Enforcement Discretion

a. Inspection Scope

On May 10, 2011, the turbine driven auxiliary feedwater (TDAFW) pump, P-8B, tripped during routine pump testing. Examination of the pump following the trip revealed the presence of grease on the knife edge that supports the reset lever (figure 1). The inspectors reviewed the licensees Licensee Event Report (LER) for accuracy and violations of requirements. The inspectors also reviewed the licensees associated condition report for corrective actions and the apparent cause evaluation. The knife edge is part of the overspeed trip mechanism. If the resetting lever is not supported by the knife edge on the manual trip lever, the trip assembly valve will close and isolate steam to the TDAFW pump. The presence of the grease reduced the force available to maintain the resetting lever on the knife edge which allowed the resetting lever to slip off the knife edge during the pump test. In the LER 2011-004-00, the licensee stated that additional evaluation would occur to determine a cause. However, the licensee has a site approved apparent cause evaluation that concluded that the greasing of the knife edge caused the TDAFW pump to trip.

Based on this information provided by the licensee and the inspectors examination of the trip mechanism following the trip, the inspectors concluded that the lubrication played a significant role in the TDAFW pump trip. Although a technical evaluation by the site did not support the lubrication as a direct contributor, the evaluation noted the lubrication reduced the force, needed to move the lever arm, significantly. The licensees assessment noted that normal vibration would not be expected to cause this force, albeit reduced. The inspectors noted several other factors which were not considered in the technical evaluation. For example, the evaluation only assessed motion in the one direction. Motion in another direction could allow the reset lever to slip off the side of the knife edge and close the steam valve. The inspectors noted the reset lever would move easily in this direction when grease was present. In addition, the inspectors noted full treatment of the lever arm and forces acting on the lower part of the arm near the overspeed trip device were not considered. The past operability review conducted by the licensee concluded that the TDAFW pump was inoperable from October 29 through May 11, 2011. Therefore, the inspectors concluded that the lubrication of the knife edge significantly contributed to the pump trip. The inspectors identified one finding related to a failure to follow procedures. This LER will remain open pending review of the LER supplement.

This LER review constituted one sample as defined in Inspection Procedure 71153.

Figure 1

b. Findings

Introduction:

A self-revealed finding of low to moderate safety significance and associated Apparent Violation of 10 CFR Part 50 Appendix B, Criterion V, Instructions, Procedures and Drawings, occurred for the licensees failure to follow procedures for lubrication of linkages on the TDAFW pump overspeed trip. Specifically, during a maintenance window the licensee greased a knife edge on the trip mechanism. The greasing of the knife edge contributed to a trip of the pump on May 10, 2011.

Discussion: During a refueling outage, the licensee took the TDAFW pump (P-8B)out-of-service for maintenance. The maintenance included greasing of linkages associated with the overspeed and manual trip mechanism. The mechanism is designed with a narrow ledge (knife edge) upon which rests a lever. When the knife edge no longer supports the lever, the lever will be pulled down under spring tension to close the steam valve to the TDAFW pump. This location should not be lubricated.

Lubrication of the knife edge significantly decreases the friction force on the trip mechanism which reduces the force needed to move the trip lever. However, the worker performing the lubrication of the linkages erroneously lubricated the knife edge.

Although the procedure provided correct instructions regarding which points to lubricate by referencing a specific drawing, the procedure contained multiple drawings of the linkages, and the drawings were not consistent in labeling of each point. If a person was not careful in aligning the lubrication step to the correct attachment (which contained the drawing), it could lead to confusion. The worker changed the procedure from the correct verbiage, Pin

(12) to knife edge and lubricated the knife edge. The change was not initialed by a cognizant supervisor for a possible procedure change, which is contrary to Palisades Procedure Admin 10.41 Site Procedure and Policy Processes.

On May 10, 2011 the licensee attempted to perform surveillance procedure RO-97, Auxiliary Feedwater System Initiation Test. Shortly after the pump started, the pumps mechanical overspeed trip actuated and shut down the pump. The licensee reviewed plant data and concluded that no overspeed condition existed. In addition, the licensee discussed the trip with operators in the room. Based on the discussions, the licensee concluded that the trip was not due to improper equipment operation or inadvertent contact with the trip mechanism. The licensee ruled out inadvertent operation of the lever by workers in the vicinity based on the workers statements. During troubleshooting, the licensee noted grease on the knife edge. The presence of the grease significantly reduced the friction on the surface, allowing the reset lever to move easily over the knife edge thereby increasing the potential for a pump trip. After removal of the grease, the licensee validated that in the grease free condition, higher forces were needed to move the resetting lever along the knife edge. In addition, the licensee tested the pump satisfactorily in accordance with surveillance procedures.

Analysis:

In accordance with Inspection Manual Chapter (IMC) 0612, Power Reactor Inspection Reports, Appendix B, the inspectors concluded that the finding was more than minor because it was associated with the equipment reliability and performance attributes of the Mitigating Systems Cornerstone. In addition, this performance deficiency impacted the cornerstone objective of ensuring the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the TDAFW pump could not reliably perform its mitigating function. The inspectors performed a Phase 1 Significant Determination Process (SDP)evaluation in accordance with IMC 0609, Attachment 4, Phase 1- Initial Screening and Characterization of Findings and concluded a Phase 2 evaluation was required because this finding represented an actual loss of safety function of a single train of equipment for greater than the Technical Specification (TS) allowed outage time. The inspectors performed a Phase 2 evaluation using the pre-solved SDP worksheets for Palisades and determined that this finding screened as Yellow. In order to realistically assess the significance, IMC 0609 required a Phase 3 SDP evaluation. A Probabilistic Risk Analysis was conducted by the Senior Reactor Analyst (SRA).

The SRAs performed a SDP phase 3 evaluation of the finding using the Palisades Standardized Plant Analysis Risk (SPAR) model for internal events and the licensees Individual Plant Examination of External Events (IPEEE) for fire risk. The SPAR model was modified to include the supplemental diesel generator that can be manually operated to provide power to a safety bus.

The exposure period used in the evaluation was 87 days, which represents the time from the last successful surveillance test of the pump until it was returned to service after the troubleshooting and removal of the grease. For both internal events and fire scenarios the TDAFW pump was assumed to be failed but recoverable.

For the internal events risk contribution, the SRAs set the basic event representing the TD AFW pump failure to run to True to obtain the sequences contributing to the delta Core Damage Frequency (CDF). Recovery credit was applied to these sequences by multiplying the estimated Human-error Probability (HEP) for the failure to recover the pump to the delta CDF obtained from the SPAR model.

Using the IPEEE submittal, the SRAs reviewed the four dominant fire areas that would contribute to the risk of the finding. The four areas reviewed were the cable spreading room, control room, 1D switchgear room, and the 1C switchgear room. An unsuppressed exposure fire in these areas was assumed to require the use of the TDAFW pump either locally or from the hot shutdown panel. Since the pump is failed due to the performance deficiency, the frequency of the unsuppressed fires represents the delta CDF if the pump is not recovered. Ignition frequencies for these areas and non-suppression probabilities from the IPEEE were used in the calculation.

The contribution to the risk significance of the finding from other external events was qualitatively evaluated and determined to be much less than the contribution from internal events and fire. IMC 0609, Appendix H, Containment Integrity Significance Determination Process was used to determine the potential risk contribution due to large early release frequency (LERF). Palisades has a large dry containment.

Sequences important to LERF include steam generator tube rupture events and inter-system loss of coolant events. These were not the dominant core damage sequences for this finding and so the risk significance due to LERF was evaluated to be low.

To evaluate the human reliability of actions to recover the pump, the SRAs used the SPAR - Human Reliability method. The procedure steps for resetting the turbine are included in Emergency Operating Procedures Supplement 19, Alternate Auxiliary Feedwater Methods. Operators are directed to this procedure from several Emergency Operating Procedures, Functional Restoration Procedures, and from the Appendix R Safe Shutdown procedures, including ONP 25.2 Alternate Safe Shutdown Procedure.

For the diagnosis portion of the HEP, the SRAs assumed stress and complexity were the driving performance shaping factors. Stress was assumed to be high because operators would be responding to multiple alarms and the consequences of their actions represent a threat to plant safety. Complexity was assumed to be moderate since the sequences of interest involve multiple equipment failures in response to initiating events and operators will be transitioning through multiple procedures and coordinating with ex-Control Room activities.

For the action portion of the HEP, in addition to stress and complexity, the SRAs assumed procedures were a driving performance shaping factor. The procedures for reset of the turbine were considered to be incomplete. The procedure instructs the operator to check the turbine is latched and if not to reset the overspeed trip lever. The procedure does not address causes of an overspeed trip, in this case slippage due to grease, or provide instructions for multiple resets, or alternate actions in the event the turbine does not remain latched.

Using these assumptions, the SRAs estimated an HEP for failing to recover the TDAFW pump to be 0.11. The delta CDF for internal events was 3.4E-7/yr and for fire scenarios was 3.1E-6/yr, for a total delta CDF of 3.4E-6/yr. The dominant sequence for internal events was a station blackout, failure to recover onsite and offsite power, failure of the TDAFW pump, and failure to recover the pump. The dominant sequence for the fire risk contribution was an unsuppressed fire in the cable spreading room followed by the failure of the TDAFW pump, and failure to recover the pump. The SDP phase 3 result is a preliminary finding of low to moderate risk significance (White).

The licensee performed an evaluation and provided several calculations. The licensee first assumed that the failure was a random failure not associated with a performance deficiency. For this case, the licensee performed a Bayesian update of the pump failure to run frequency. No recovery was credited in this calculation. The change in CDF was estimated to be 4E-8/yr. The NRC has concluded a performance deficiency existed.

The licensee also performed several calculations assuming that the failure did represent a performance deficiency. If no recovery is credited, the licensee estimated a delta CDF of 4.37E-5/yr. If recovery is applied, the licensee estimated a delta CDF of 4.81E-7/yr.

In both the NRC and the licensee evaluations, the fire contribution dominates the risk.

The licensees unrecovered fire contribution is similar but slightly higher than the NRCs due to including more scenarios. The dominant scenarios are the same.

The major difference in the numerical result is credit for recovering the turbine-driven AFW pump. The licensees evaluation treats reset as recovery of the pump and does not consider the possibility that reset alone may not restore function and operator actions outside of procedures may be required.

The finding occurred, in part, due to a worker making a change to a work instruction without following the process for procedure revisions. When faced with uncertainty regarding the proper lubrication point, the worker changed the procedure without consulting supervision. Therefore, the inspectors assigned a cross cutting aspect of H.1(a), risk-significant decisions using a systematic process.

Enforcement:

10 CFR Part 50 Appendix B, Criterion V, Instructions, Procedures and Drawings, states, in part, that activities affecting quality shall be prescribed by documented instructions, procedures or drawings of a type appropriate to the circumstances and shall be accomplished in accordance with these instructions, procedures or drawings.

Technical Specification 3.7.5 requires, in part, that two auxiliary feedwater trains be operable during plant operation in Modes 1, 2, and 3 with the steam driven pump required to be operable prior to making the reactor critical.

Technical Specification Actions 3.7.5.A and B require, in part, that if one auxiliary feedwater train is inoperable in Modes 1, 2, and 3, the affected train shall be restored to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or the plant placed in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in Mode 4 within 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.

An Apparent Violation (AV) of 10 CFR Part 50, Appendix B, Criterion V, Instructions, Procedures and Drawings, has been identified as it appears that the licensee failed to accomplish maintenance on the TDAFW pump, an activity affecting quality, in accordance with the documented procedure. Specifically, a worker performing procedure FWS-M-6, Auxiliary Feedwater Turbine Maintenance failed to follow step 5.40.3 of the procedure which required lubricating a pin and instead greased the knife edge of the mechanical overspeed/manual trip mechanism. As a result, the TDAFW was inoperable from October 29, 2010, when the plant achieved criticality, to May 11, 2011, a period greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. Because the licensee was not aware of the inoperability, the required actions in Actions 3.7.5.A and B were not followed.

(AV 05000255/2011013-01, Improper Lubrication of Turbine Driven Auxiliary Feedwater Pump Linkages)

4OA6 Management Meetings

.1 Exit Meeting Summary

On October 5, 2011, the inspectors presented the inspection results to Mr. A. Vitale and other members of the licensee staff. The licensee acknowledged the issues presented.

The inspectors confirmed that none of the potential report input discussed was considered proprietary.

ATTACHMENT:

SUPPLEMENTAL INFORMATION

KEY POINTS OF CONTACT

Licensee

O. Gustafson, Licensing Manager

J. Haumerson, Systems Engineering Manager

D. Hamilton, General Manager

T. Fouty, Engineering Supervisor

Nuclear Regulatory Commission

J. Giessner, Chief, Reactor Projects Branch 4

LIST OF ITEMS

Opened

2011013-01 AV Improper Lubrication of Turbine Driven Auxiliary Feedwater Pump Linkages

Closed

NONE

Discussed

2011-004-00 LER Turbine Driven Auxiliary Feedwater Pump Inoperable in Excess of Technical Specification Requirements Due to Unexpected Trip Attachment