IR 05000368/2016011

NRC Inspection Report 05000368/2016011 and Preliminary White Finding

ML17019A288
Person / Time
Site:	Arkansas Nuclear
Issue date:	01/19/2017
From:	Troy Pruett NRC/RGN-IV/DRP
To:	Richard Anderson Entergy Operations
NEIL O'KEEFE
References
EA-16-247 IR 2016011
Download: ML17019A288 (24)

Text

nuary 19, 2017

SUBJECT:

ARKANSAS NUCLEAR ONE - NRC INSPECTION REPORT 05000368/2016011 AND PRELIMINARY WHITE FINDING

Dear Mr. Anderson:

On December 21, 2016, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at your Arkansas Nuclear One facility, Unit 2, and the inspectors discussed the results of this inspection with you and other members of your staff. The results of this inspection are documented in the enclosed inspection report.

The enclosed inspection report discusses a finding that has preliminarily been determined to be a White finding with low to moderate safety significance that may require additional inspections, regulatory actions, and oversight. As described in Section 4OA3.1 of the enclosed report, this finding involved a failure to ensure that an emergency diesel generator bearing was provided with adequate lubrication. As a result, the bearing overheated and caused the emergency diesel generator to fail on September 16, 2016 during a required 24-hour loaded endurance test. The extent of damage from the failure led to the decision to shut the unit down to comply with technical specifications. This finding did not present an immediate safety concern because other normal and emergency sources of power remained available, and your plant walkdowns and our inspections confirmed that this condition did not exist on other safety-related equipment.

This finding was assessed based on the best available information, using the NRCs significance determination process (SDP). The basis for the NRCs preliminary significance determination is described in the enclosed report. The NRC will inform you in writing when the final significance has been determined.

The NRC staff determined that the total increase in core damage frequency for the performance deficiency was preliminarily estimated to be between 3.0E-6 per year and 9.6E-6 per year, or of low to moderate safety significance (White). The most dominant contributor was potential fires in nonvital electrical switchgear, which could result in a transient and loss of offsite power for Unit 2, combined with a postulated non-related failure of emergency diesel generator B. Your staff implemented compensatory measures while repairs were being made to the affected equipment, including delaying work that could impact the reliability of offsite and onsite power sources, increasing the number of fire watches near critical equipment, and delaying the start of the planned refueling outage in Unit 1.

The finding is also an apparent violation of NRC requirements and is being considered for escalated enforcement action in accordance with the NRC Enforcement Policy, which can be found on the NRCs Web site at http://www.nrc.gov/about-nrc/regulatory/enforcement/enforce-pol.html.

In accordance with NRC Inspection Manual Chapter 0609, we intend to complete, using the best available information, and issue our final safety significance determination within 90 days from the date of this letter. The NRCs Significance Determination Process (SDP) is designed to encourage an open dialogue between your staff and the NRC; however, the dialogue should not affect the timeliness of our final determination.

Before the NRC makes a final decision on this matter, we are providing you with an opportunity to (1) attend a Regulatory Conference where you can present to the NRC your perspective on the facts and assumptions used to arrive at the finding and assess its significance, or (2) submit your position on the finding to the NRC in writing. If you request a Regulatory Conference, it should be held within 40 days of your receipt of this letter. We encourage you to submit supporting documentation at least one week prior to the conference in an effort to make the conference more efficient and effective. The focus of the Regulatory Conference is to discuss the significance of the finding and not necessarily the root cause(s) or corrective action(s)

associated with the finding. If a Regulatory Conference is held, it will be open for public observation. The NRC will issue a public meeting notice to announce the conference.

If you decide to submit only a written response, it should be sent to the NRC within 40 days of your receipt of this letter. Written responses should be clearly marked as a Response to an Apparent Violation; EA-16-247 and should include for the apparent violation: (1) the reason for the apparent violation, or if contested, the basis for disputing the apparent violation; (2) the corrective steps that have been taken and the results achieved; (3) the corrective steps that will be taken; and (4) the date when full compliance will be achieved. 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 NRC Inspection Manual Chapter 0609.

Please contact Neil OKeefe at 817-200-1574, and in writing, within 10 days from the issue date of this letter to notify the NRC of your intentions. 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.

Because 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. In addition, please be advised that the number and characterization of the apparent violation may change based on further NRC review. In accordance with 10 CFR 2.390 of the NRC's "Agency Rules of Practice," a copy of this letter and its enclosure will be made available electronically for public inspection in the NRC Public Document Room and in the NRCs Agencywide Documents Access and Management System (ADAMS), accessible from the NRC Web site at http://www.nrc.gov/reading-rm/adams.html.

Sincerely,

/RA/

Troy W. Pruett, Director Division of Reactor Projects Docket No. 50-368 License No. NPF-6 Enclosure:

Inspection Report 05000368/2016011 w/ Attachments:

1. Supplemental Information 2. Detailed Risk Evaluation

ML17019A288 SUNSI Review ADAMS Non-Sensitive Publicly Available Keyword:

By: NFO Yes No Sensitive Non-Publicly Available NRC-002 OFFICE SRI:DRP/E RI:DRP/E PE:DRP/E SRA: BC:DRP/E C:PSB2 TL:ACES NAME BTindell MTobin BCorrell RDeese NOKeefe HGepford MHay SIGNATURE /RA-T/ /RA/ /RA/ /RA-E/ /RA/ /RA/ /RA-John Kramer for/

DATE 1/9/17 1/10/17 1/9/17 1/10/17 1/10/17 1/11/17 1/13/17 OFFICE RC DD:DRS DD:DRP NAME KFuller AVegel TPruett SIGNATURE /RA-E/ /RA/ /RA/

DATE 1/12/17 1/17/17 1/19/17

U.S. NUCLEAR REGULATORY COMMISSION

REGION IV

Docket: 05000368 License: NPF-6 Report: 05000368/2016011 Licensee: Entergy Operations, Inc.

Facility: Arkansas Nuclear One, Unit 2 Location: Junction of Highway 64 West and Highway 333 South Russellville, Arkansas Dates: September 16 through December 21, 2016 Inspectors: B. Tindell, Senior Resident Inspector M. Tobin, Resident Inspector B. Correll, Project Engineer R. Deese, Senior Reactor Analyst Approved N. OKeefe By: Chief, Projects Branch E Division of Reactor Projects Enclosure

SUMMARY

IR 05000368/2016011; 09/16/2016 - 12/21/2016; Arkansas Nuclear One, Unit 2; Inspection

Report; Follow-up of Events and Notices of Enforcement Discretion.

The inspection activities described in this report were performed between September 16 and December 21, 2016, by the resident inspectors at Arkansas Nuclear One and inspectors from the NRCs Region IV office. One finding that was preliminarily determined to have low to moderate safety significance (White) is documented in this report. The significance of inspection findings is indicated by their color (Green, White, Yellow, or Red), which is determined using Inspection Manual Chapter 0609, Significance Determination Process. Their cross-cutting aspects are determined using Inspection Manual Chapter 0310, Aspects within the Cross-Cutting Areas. Violations of NRC requirements are dispositioned in accordance with the NRC Enforcement Policy. The NRCs program for overseeing the safe operation of commercial nuclear power reactors is described in NUREG-1649, Reactor Oversight Process.

Cornerstone: Mitigating Systems

• Apparent Violation. The inspectors reviewed a self-revealing finding that was preliminarily determined to have low to moderate safety significance (White) for the failure to perform maintenance activities in a manner that ensured adequate lubrication to Unit 2 emergency diesel generator A. This finding involved a violation of Technical Specification 6.4.1.a, because the licensee failed to provide adequate work instructions for maintenance on the inboard generator bearing oil sight glass to ensure that the scribe mark indicated the minimum acceptable oil level to ensure adequate lubrication to the bearing. As a result, the licensee reinstalled the sight glass with the oil level scribe mark below the bottom of the bearing rollers. Subsequently, on June 22, 2016, the oil was drained and replaced with oil level close to the sight glass scribe mark, and the bearing failed on September 16, 2016, during a 24-hour surveillance. The licensee entered this issue into the corrective action program as Condition Report CR-ANO-2-2016-03307. The licensee resolved the safety concern by repairing the bearing, successfully testing the diesel, and verifying the condition did not exist in any other safety-related equipment.

The failure to ensure adequate lubrication to the inboard generator bearing so that the Unit 2 emergency diesel generator A would be capable of performing its safety functions for the intended mission time is a performance deficiency. This performance deficiency is more than minor, and therefore is a finding, because it is associated with the procedure quality attribute of the mitigating systems cornerstone, and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences. Specifically, the licensee failed to properly pre-plan and perform work that could affect this safety-related system in accordance with written procedures, documented instructions, or drawings appropriate to the circumstances such that the minimum bearing oil level was correctly marked and maintained. This performance deficiency subsequently affected the availability and reliability of the emergency diesel generator, a mitigating system. The inspectors evaluated the finding with NRC Manual Chapter 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power, dated June 19, 2012, Exhibit 2, Mitigating Systems Screening Questions. The inspectors determined that the finding required a detailed risk evaluation because an actual loss of function of a single train of mitigating equipment occurred for greater than its technical specification allowed outage time.

As determined by a Significance and Enforcement Review Panel (SERP), the total increase in core damage frequency for the performance deficiency was preliminarily estimated to be between 3.0E-6 per year and 9.6E-6 per year, or of low to moderate safety significance.

The inspectors determined this finding has a cross-cutting aspect in the human performance area of Work Management, because the primary cause of the performance deficiency involved the failure to plan, control, and execute work activities such that nuclear safety is the overriding priority [H.5]. (Section 4OA3)

REPORT DETAILS

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

.1 Unit 2 Emergency Diesel Generator A Bearing Failure

a. Inspection Scope

On September 16, 2016, the inboard generator bearing for the Unit 2 emergency diesel generator A overheated and failed. The inspectors reviewed the operators response to the failure, including securing the diesel, consideration of fire response, event classification, technical specification compliance, and risk management actions. During the repair process, the inspectors reviewed the licensees efforts to assess the cause and extent of damage, replace parts, modify the generator shaft, and perform post-maintenance testing. The inspectors reviewed the licensees corrective actions for the failure, including setting the correct scribe mark for the bearing oil. The inspectors independently assessed the extent of condition by conducting plant walkdowns, and reviewed the licensees extent of condition inspection and evaluation.

The inspectors reviewed the licensees corrective actions after a licensee engineer discovered, during reassembly, that the oil level scribe mark on the repaired bearing was again below the vendor recommended level, but above the minimum level for lubricating the bearing (CR-ANO-2-2016-3722). The inspectors reviewed the sleeving modification of the generator shaft and corrective actions for damage that occurred when the new shaft sleeve contacted the repaired bearing housing cover while manually rotating the engine (CR-ANO-2-2016-3435).

b. Findings

Introduction.

The inspectors reviewed a self-revealing finding of preliminary low to moderate safety significance (White) and an associated apparent violation of Unit 2 Technical Specification 6.4.1.a for the failure to provide adequate lubrication to the inboard generator bearing so that the Unit 2 emergency diesel generator A would provide emergency power to safety equipment. Specifically, two separate maintenance activities introduced errors that led to having inadequate oil to lubricate the bearing, and the bearing failed on September 16, 2016, during a 24-hour surveillance.

Description.

On September 16, 2016, 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> into a 24-hour surveillance at full load, the inboard generator bearing for the Unit 2 emergency diesel generator A failed, as evidenced by load swings, overheating, and sparking. Operators secured the diesel, declared it inoperable, documented the failure in Condition Report CR-ANO-2-2016-03307, and complied with Unit 2 Technical Specification 3.8.1.1, A.C.

Sources, Action B. Maintenance personnel discovered significant damage to the bearing indicative of a lack of oil lubrication. On September 28, 2016, the licensee shut Unit 2 down prior to the expiration of the technical specification action statement. The licensee completed repairs and successfully tested the diesel on October 22, 2016, and restarted Unit 2 on October 27, 2016.

During a causal investigation for the lack of lubrication, the licensee identified that the oil level scribe mark on the sight glass was below the minimum level necessary to provide proper oil lubrication to the bearing. The licensee concluded that on November 11,2014, while performing Work Order 356569, maintenance personnel had removed and inadvertently inverted the sight glass, which caused the scribe mark to be below the bottom of the bearing rollers (see diagram below). With the sight glass inverted, the scribe mark was 3/8-inch lower than if it was in the correct orientation. Post-failure measurements identified that the scribe mark was 5/8-inch below the correct position.

The licensee concluded that adequate oil was initially provided following the sight glass reinstallation. Evidence to support this included multiple successful surveillance tests with no increase in vibrations, including a 24-hour surveillance on January 12, 2015, and having an oil sample from the bearing on June 22, 2016, with no indications of abnormal wear.

On June 22, 2016, maintenance personnel changed the oil in the inboard generator bearing after taking an oil sample in accordance with Work Order 52656389.

Maintenance personnel documented leaving the oil level within the procedural limits relative to the scribe mark. Vibrations and system performance were normal during the post-maintenance runs and surveillance tests on June 26, 2016. The licensee determined that the inboard generator bearing had not been leaking oil between the oil change on June 22, 2016, and the September 16, 2016, surveillance failure.

The licensee concluded that the oil in the inboard generator bearing heated up slowly during the 24-hour surveillance. After 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br />, enough oil had vaporized within the bearing casing that the liquid oil level became inadequate to lubricate the bearing, resulting in bearing failure. Therefore, the inspectors concluded that the emergency diesel generator could have failed approximately 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> after the start of a postulated event between June 26, 2016, and September 16, 2016.

The inspectors concluded that multiple causes led to the lack of oil lubrication. The licensee failed to incorporate vendor manual instructions to properly set and verify the correct oil sight glass scribe mark into Work Order 356569 for maintenance performed in 2014. The licensee failed to train maintenance personnel to adequately identify and control critical parameters during maintenance, specifically the effects of sight glass installation and maintenance on bearing lubrication. The inspectors also noted that work instructions in Work Order 52656389 did not specify the correct amount of oil to add when replacing the oil, or else measure the amount of oil removed and ensure that a like amount of new oil was added to the bearing.

On October 11, 2016, following bearing reassembly, a system engineer checked the level of the new sight glass and identified that the scribe mark was too low again. The licensee found that the new oil level had been marked on the bearing housing prior to assembly, but that the oil level was below the vendor-recommended level. In response, the licensee planned and executed a work order to set the oil level in relation to the generator shaft centerline in accordance with the vendor recommendations. The inspectors noted that the licensee had not yet implemented corrective actions to prevent recurrence of the problem in that licensees work plans failed to include verification of the oil level relative to the generator shaft centerline after reassembling the bearing. The licensee subsequently corrected the sight glass position and developed training and improved work instructions to ensure that the bearing oil level would be correctly established.

After the diesel bearing failure, the licensee verified through walk downs that all sight glass marks and bearing oil levels were adequate for other safety-related rotating equipment. The inspectors also independently reviewed bearing oil levels.

Analysis.

The failure to ensure adequate lubrication to the inboard generator bearing so that the Unit 2 emergency diesel generator A would be capable of performing its safety functions for the intended mission time is a performance deficiency. This performance deficiency is more than minor, and therefore is a finding, because it is associated with the procedure quality attribute of the mitigating systems cornerstone, and adversely affected the cornerstone objective to ensure the availability, reliability, and capability of systems that respond to initiating events to prevent undesirable consequences.

Specifically, the licensee failed to properly pre-plan and perform work that could affect this safety-related system in accordance with written procedures, documented instructions, or drawings appropriate to the circumstances such that the minimum bearing oil level was correctly marked and maintained. This performance deficiency subsequently affected the availability and reliability of the emergency diesel generator, a mitigating system.

Using NRC Manual Chapter 0609, Appendix A, The Significance Determination Process (SDP) for Findings At-Power, dated June 19, 2012, Exhibit 2, Mitigating Systems Screening Questions, the inspectors determined that the finding required a detailed risk evaluation because an actual loss of function of a single train of mitigating equipment occurred for greater than its technical specification allowed outage time.

As determined by a Significance and Enforcement Review Panel (SERP), the total increase in core damage frequency for the performance deficiency was preliminarily estimated to be between 3.0E-6/year and 9.6E-6/year, or of low to moderate safety significance (White). See Attachment 2 of this report for the results of the detailed risk evaluation and SERP.

The inspectors determined this finding has a cross-cutting aspect in the human performance area of Work Management [H.5,], because the primary cause of the performance deficiency involved the failure to plan, control, and execute work activities such that nuclear safety is the overriding priority.

Enforcement.

Unit 2 Technical Specification 6.4.1.a requires, in part, that written procedures shall be established, implemented, and maintained covering the applicable procedures recommended in Regulatory Guide 1.33, Quality Assurance Program Requirements, Revision 2, Appendix A, February 1978. Regulatory Guide 1.33, Appendix A, Section 9.a, states, in part, that maintenance that can affect the performance of safety-related equipment should be properly pre-planned and performed in accordance with written procedures, documented instructions, or drawings appropriate to the circumstances.

Contrary to the above, on November 11, 2014, the licensee failed to properly pre-plan and perform maintenance that can affect the performance of safety-related equipment in accordance with written procedures, documented instructions, or drawings appropriate to the circumstances. Specifically, on November 11, 2014, while performing Work Order 356569, and on June 22, 2016, while performing Work Order 52656389, the licensee failed to provide adequate work instructions for maintenance to Unit 2 emergency diesel generator A inboard generator bearing, a safety-related system, such that the minimum bearing oil level was correctly marked and maintained to ensure adequate lubrication to the bearing. As a result, the licensee first reinstalled the sight glass with the oil level scribe mark below the bottom of the bearing rollers, and subsequently replaced the oil with an inadequate volume, causing the bearing to fail on September 16, 2016, during a 24-hour surveillance.

The licensee documented the issue in Condition Report CR-ANO-2-2016-03307. The licensee replaced the damaged parts, machined the shaft and installed a sleeve, and raised the sight glass scribe mark to the correct level for adequate lubrication to the bearing. This violation is being treated as an apparent violation pending a final significance determination. AV 05000368/2016011-01 Failure to Ensure Adequate Lubrication for Emergency Diesel Generator Bearing.

.2 (Closed) LER 05000368/2016-001-00, Failure of One Emergency Diesel Generator and

Subsequent Required Shutdown of Arkansas Nuclear One, Unit 2 On September 16, 2016, the Unit 2 emergency diesel generator A inboard generator bearing failed during a 24-hour surveillance. Operators declared the emergency diesel generator inoperable. When it became apparent that repairs could not be completed within the Technical Specification 3.8.1.1 action statement requirement, operators shut Unit 2 down. The licensee determined that the bearing failed due to inadequate lubrication, and that the diesel had been inoperable since June 22, 2016. The enforcement aspects of this violation are discussed in Section 4OA3.1 of this report.

This licensee event report is closed.

These activities constituted completion of two event follow-up samples, as defined in Inspection Procedure 71153.

4OA6 Meetings, Including Exit

Exit Meeting Summary

On December 21, 2016, the inspectors presented the inspection results to Mr. Rich Anderson, Site Vice President, and other members of the licensee staff. The licensee acknowledged the issues presented. The licensee confirmed that any proprietary information reviewed by the inspectors had been returned or destroyed.

SUPPLEMENTAL INFORMATION

KEY POINTS OF CONTACT

Licensee Personnel

R. Anderson, Site Vice President

P. Butler, Design and Program Engineering Manager

T. Chernivec, Outage Manager

B. Daiber, Recovery Manager

B. Davis, Engineering Director

T. Evans, General Manager of Plant Operations

D. Marvel, Maintenance Manager

D. Perkins, Operations Manager

S. Pyle, Regulatory Assurance Manager

B. Short, Senior Licensing Specialist

M. Skartvedt, Systems and Components Engineering Manager

D. Vest, Senior System Engineer

LIST OF ITEMS OPENED, CLOSED, AND DISCUSSED

05000368/2016011-01 AV Failure to Ensure Adequate Lubication for Emergency Diesel Generator Bearing (Section 4OA3.1)

05000368-2016001-00 LER Failure of One Emergency Diesel Generator and Subsequent Required Shutdown of Arkansas Nuclear One, Unit 2 (Section 4OA3.2)