IR 05000352/2018003

Integrated Inspection Report 05000352/2018003 and 05000353/2018003

ML18317A116
Person / Time
Site:	Limerick
Issue date:	11/13/2018
From:	Jon Greives Reactor Projects Region 1 Branch 4
To:	Bryan Hanson Exelon Generation Co, Exelon Nuclear
Greives J
References
IR 2018003
Download: ML18317A116 (17)

Text

ber 13, 2018

SUBJECT:

LIMERICK GENERATING STATION - INTEGRATED INSPECTION REPORT 05000352/2018003 AND 05000353/2018003

Dear Mr. Hanson:

On September 30, 2018, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Limerick Generating Station, Units 1 and 2. On October 19, 2018, the NRC inspectors discussed the results of this inspection with Mr. Frank Sturniolo, Plant Manager, and other members of your staff. The results of this inspection are documented in the enclosed report.

NRC inspectors documented two findings of very low safety significance (Green) in this report.

Both of these findings involved violations of NRC requirements. The NRC is treating these violations as non-cited violations (NCVs) consistent with Section 2.3.2.a of the Enforcement Policy.

If you contest the violations or significance of these NCVs, you should provide a response within 30 days of the date of this inspection report, with the basis for your denial, to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC 20555-0001; with copies to the Regional Administrator, Region I; the Director, Office of Enforcement; and the NRC Resident Inspector at Limerick Generating Station. In addition, if you disagree with a cross-cutting aspect assignment, you should provide a response within 30 days of the date of this inspection report, with the basis for your disagreement, to the U. S. Nuclear Regulatory Commission, ATTN: Document Control Desk, Washington, DC, 20555-0001; with copies to the Regional Administrator, Region I, and the NRC Resident Inspector at Limerick Generating Station. This letter, its enclosure, and your response (if any) will be made available for public inspection and copying at http://www.nrc.gov/reading-rm/adams.html and the NRC Public Document Room in accordance with Title 10 of the Code of Federal Regulations (10 CFR), Part 2.390, Public Inspections, Exemptions, Requests for Withholding.

Sincerely,

/RA/

Jonathan E. Greives, Chief Reactor Projects Branch 4 Division of Reactor Projects Docket Numbers: 50-352 and 50-353 License Numbers: NPF-39 and NPF-85

Enclosure:

Inspection Report 05000352/2018003 and 05000353/2018003

Inspection Report

Docket Numbers: 50-352 and 50-353 License Numbers: NPF-39 and NPF-85 Report Numbers: 05000352/2018003 and 05000353/2018003 Enterprise Identifier: I-2018-003-0071 Licensee: Exelon Generation Company, LLC Facility: Limerick Generating Station, Units 1 & 2 Location: Sanatoga, PA 19464 Inspection Dates: July 1, 2018 to September 30, 2018 Inspectors: S. Rutenkroger, PhD, Senior Resident Inspector M. Fannon, Resident Inspector S. Barber, Senior Project Engineer C. Bickett, Senior Reactor Inspector D. Beacon, Project Engineer T. Dunn, Operations Engineer Approved By: Jonathan E. Greives, Chief Reactor Projects Branch 4 Division of Reactor Projects Enclosure

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring Exelons performance at

Limerick Generating Station (LGS), Units 1 and 2 by conducting the baseline inspections described in this report in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information. NRC-identified and self-revealing findings, violations, and additional items are summarized in the table below.

List of Findings and Violations Failure to Assess and Manage Risk Associated with Fuel Oil Storage Tank Maintenance Cornerstone Significance Cross-Cutting Inspection Aspect Results Section Mitigating Green H.8 - Human 71111.13 Systems NCV 05000352/2018003-01 Performance -

Opened/Closed Procedure Adherence An NRC-identified Green non-cited violation (NCV) of Title 10 of the Code of Federal Regulations (10 CFR) 50.65(a)(4) was identified when Exelon failed to assess and manage risk associated with fuel oil storage tank maintenance by not properly evaluating and establishing compensatory actions for maintaining availability of associated emergency diesel generators (EDGs).

Failure to Correct Adverse Environmental Conditions Impacting Low Pressure Coolant Injection Outboard Isolation Valve Cornerstone Severity Cross-Cutting Aspect Inspection Results Section Barrier Green H.13 - Human 71153 Integrity NCV 05000352/2018003-02 Performance - Consistent Opened/Closed Process A self-revealed Green NCV of 10 CFR Part 50, Appendix B, Criterion XVI was identified when Exelon failed to correct adverse environmental conditions affecting the Unit 1 low pressure coolant injection (LPCI) outboard primary containment isolation valve (PCIV) actuator that resulted in long term water intrusion, corrosion, and failure of the valve to stroke closed.

Additional Tracking Items Type Issue Number Title Report Status Section LER 05000352/2018-002-00 Primary Containment 71153 Closed Isolation Valve Failed to Fully Close Resulting in a Condition Prohibited by Technical Specifications

PLANT STATUS

Unit 1 began the inspection period at rated thermal power. On August 29, 2018, the unit was down powered to 32 percent due to an inadvertent runback caused by an equipment issue with the 1A adjustable speed drive. The unit was returned to rated thermal power on August 29, 2018, and remained at or near rated thermal power for the remainder of the inspection period.

Unit 2 operated at or near rated thermal power for the entire inspection period.

INSPECTION SCOPES

Inspections were conducted using the appropriate portions of the inspection procedures (IPs) in effect at the beginning of the inspection unless otherwise noted. Currently approved IPs with their attached revision histories are located on the public website at http://www.nrc.gov/reading-rm/doc-collections/insp-manual/inspection-procedure/index.html. Samples were declared complete when the IP requirements most appropriate to the inspection activity were met consistent with Inspection Manual Chapter (IMC) 2515, Light-Water Reactor Inspection Program - Operations Phase. The inspectors performed plant status activities described in IMC 2515, Appendix D, Plant Status, and conducted routine reviews using IP 71152, Problem Identification and Resolution. The inspectors reviewed selected procedures and records, observed activities, and interviewed personnel to assess Exelons performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.

REACTOR SAFETY

==71111.01 - Adverse Weather Protection

Summer Readiness (1 sample)

==

The inspectors evaluated summer readiness of offsite and alternate alternating current

===power systems.

External Flooding===

The inspectors evaluated readiness to cope with external flooding, with focus on external flood barriers at the station.

==71111.04 - Equipment Alignment

Partial Walkdown (2 samples)

==

The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:

(1) Unit 2 reactor core isolation cooling on July 11, 2018

(2) Unit 1 high pressure coolant injection on August 28, 2018

==71111.05A/Q - Fire Protection Annual/Quarterly

Quarterly Inspection (5 samples)

==

The inspectors evaluated fire protection program implementation in the following selected areas:

(1) Fire area 79, Unit 1 D11 EDG and fuel oil / lube oil tank room, elevation 217, on July 13, 2018

(2) Fire areas 16, 17, 18, and 19, Unit 2 EDG 4 kilovolt switchgear rooms, elevation 239, on July 26, 2018

(3) Fire area 57, Unit 2 high pressure coolant injection pump room, elevation 177, on August 15, 2018

(4) Fire area 33, Unit 1 reactor core isolation cooling pump room, elevation 177, on September 6, 2018

(5) Fire areas 58 and 59, Unit 2 B and D core spray pump rooms, elevation 177 on September 21, 2018

==71111.06 - Flood Protection Measures

Internal Flooding (1 sample)

==

The inspectors evaluated internal flooding mitigation protection in Unit 2 core spray pump

===rooms on September 17, 2018.

Cables===

The inspectors evaluated cable submergence protection in the following locations:

(1) Cable vaults 6, 95, and 109W on August 10 and 28, 2018

==71111.07 - Heat Sink Performance

Heat Sink (1 sample)

==

The inspectors evaluated Exelons monitoring and maintenance of Unit 2 B reactor enclosure cooling water heat exchanger performance.

==71111.11 - Licensed Operator Requalification Program and Licensed Operator Performance

==

Operator Requalification (1 sample)

The inspectors observed and evaluated licensed operator requalification training on

===September 4, 2018.

Operator Performance (1 sample)===

The inspectors observed Unit 1 reactor power escalation from 31 percent to 90 percent on August 29, 2018.

==71111.12 - Maintenance Effectiveness

Routine Maintenance Effectiveness (2 samples)

==

The inspectors evaluated the effectiveness of routine maintenance activities associated with the following equipment and/or safety significant functions:

(1) Unit 1 Class 1E divisions 1 and 2 125/250 volts direct current safeguards batteries

(2) Unit 2 Class 1E divisions 1 and 2 125/250 volts direct current safeguards batteries

==71111.13 - Maintenance Risk Assessments and Emergent Work Control (4 samples)

==

The inspectors evaluated the risk assessments for the following planned and emergent work activities:

(1) Unit 2 high pressure coolant injection maintenance outage on July 10, 2018

(2) Unit 1 D11 EDG fuel oil storage tank cleaning and inspection on August 3, 2018

(3) Unit 1 D12 EDG fuel oil storage tank cleaning and inspection on August 6, 2018

(4) Unit 2 A core spray maintenance outage on August 13, 2018

==71111.15 - Operability Determinations and Functionality Assessments (5 samples)

==

The inspectors evaluated the following operability determinations and functionality assessments:

(1) Unit 2 C standby liquid control pump boron accumulation on July 2, 2018

(2) Unit common A emergency service water leak on July 16, 2018

(3) Unit 1 A residual heat removal pump overcurrent alarm on July 19, 2018

(4) Unit 1 primary containment atmosphere temperature recorder displaying higher drywell temperature on July 20, 2018

(5) Unit common B residual heat removal service water loop flow on August 23, 2018

==71111.18 - Plant Modifications (1 sample)

==

The inspectors evaluated the following temporary or permanent modifications:

(1) Engineering change request 436667 - B main control room chiller panel door

==71111.19 - Post Maintenance Testing (5 samples)

==

The inspectors evaluated post maintenance testing for the following maintenance/repair activities:

(1) Unit 2 high pressure coolant injection electronic governor replacement on July 12, 2018

(2) Unit 1 D14 EDG system overhaul on July 28, 2018

(3) Unit common B control enclosure chiller capacity control module replacement on August 2, 1018

(4) Unit 2 reactor core isolation cooling flow transmitter replacement on September 14, 2018

(5) Unit 1 high pressure coolant injection room cooler leak repair on September 26, 2018

==71111.22 - Surveillance Testing The inspectors evaluated the following surveillance tests:

==

Routine (1 sample)

(1) ST-4-051-307-2, Unit 2 B residual heat removal auto closure contact test on August 22, 2018

In Service (2 samples)

(1) ST-6-055-230-1, Unit 1 high pressure coolant injection pump, valve, and flow test on September 19, 2018

(2) ST-6-051-234-1, Unit 1 D residual heat removal pump, valve, and flow test on September 26, 2018

==71114.06 - Drill Evaluation

Emergency Planning Drill (3 samples)

==

(1) The inspectors evaluated the conduct of a routine LGS emergency planning drill on July 9, 2018

(2) The inspectors evaluated the conduct of a routine LGS emergency planning drill on July 16, 2018

(3) The inspectors evaluated the conduct of a routine LGS emergency planning drill on July 23,

OTHER ACTIVITIES - BASELINE

71151 - Performance Indicator Verification

The inspectors verified Exelons performance indicator submittals listed below for the period July 1, 2017, through June 30, 2018.

(1) Unit 1 and Unit 2 unplanned scrams per 7000 critical hours

(2) Unit 1 and Unit 2 unplanned scrams with complications

(3) Unit 1 and Unit 2 residual heat removal system mitigating system performance index

==71152 - Problem Identification and Resolution

Annual Follow-up of Selected Issues (2 samples)

==

The inspectors reviewed Exelons implementation of its corrective action program related to the following issues:

(1) Failure of rod position indication power supplies on Units 1 and 2 (Issue Reports (IRs)

===03986074, 03988302, 03990303, 04003680, 04011371, and 04076445)

(2) Human performance issues caused the Unit 1 E condensate deep bed to be inadvertently removed from service and the Unit 1 A residual heat removal heat exchanger to be unnecessarily flushed (IRs 04041650 and 04051348)71153 - Follow-up of Events and Notices of Enforcement Discretion Licensee Event Reports ===

The inspectors evaluated the following licensee event report (LER).

(1) LER 05000352/2018002, Primary containment isolation valve failed to fully close resulting in a condition prohibited by technical specifications (ADAMS Accession No. ML18155A193)

The circumstances surrounding this LER are documented in report section Inspection Results.

INSPECTION RESULTS

Failure to Assess and Manage Risk Associated with Fuel Oil Storage Tank Maintenance Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green H.8 - Human 71111.13 Systems NCV 05000352/2018003-01 Performance -

Opened/Closed Procedure Adherence An NRC-identified Green NCV of 10 CFR 50.65(a)(4) was identified when Exelon failed to assess and manage risk associated with fuel oil storage tank maintenance by not properly evaluating and establishing compensatory actions for maintaining availability of associated EDGs.

Description:

The EDG systems are safety-related standby emergency power systems for LGS Units 1 and 2 consisting of four EDG sets per unit. Each EDG has an associated day tank and fuel oil storage tank with fuel for over a few hours and multiple days, respectively.

Exelon removed the D11 fuel oil storage tank from service on July 30, 2018, for a periodic cleaning and inspection, and restored the tank to service on August 3, 2018. Exelon similarly removed the D12 fuel oil storage tank from service on August 6, 2018. During each maintenance window, Exelon established a risk-based contingency plan to align an alternate fuel oil storage tank from one of the other EDGs to the inoperable EDG in case of need. In this manner, the inoperable EDG would be capable of supplying electrical loads beyond the time supplied from the day tank alone. Exelon credited the plan to classify each EDG as available in accordance with procedure WC-AA-101, On-Line Work Control Process, and WC-AA-101-1006, On-Line Risk Management and Assessment.

The inspectors interviewed work management and operations personnel and reviewed the tasks associated with the contingency plan in the field. The inspectors identified a number of issues that represented a challenge to successful performance of the contingency plan: (1)the designated operator assigned to perform the tasks was also assigned to the site fire brigade,

(2) not all required tools were ensured available to the operator and not found at the work location when reviewed in the field,

(3) the majority of the work locations and travel paths were not serviced with emergency lighting and no portable lighting was staged,

(4) the implementing plans procedure called for additional personnel who were not pre-briefed, (5)the tasks required the operator to travel between four different buildings including outside and down into protected fuel vaults multiple times,

(6) the vaults were confined spaces that required verifying oxygen levels prior to entry after unbolting and removing a large protective cover via lift, and

(7) the contingency plan required decision-making to successfully implement and involved a series of tasks that required using tools including a portable oxygen meter and a jumper.

In contrast, the inspectors identified the following in the procedures for maintaining (a)(4)availability. Procedures WC-AA-101 and WC-AA-101-1006 required that collateral duties must be ensured to not interfere with the designated response. WC-AA-101-1006 required the designated operator to be stationed in the same building as the affected component(s).

Finally, WC-AA-101 stated that to credit operator actions outside the control room that operations must have virtual certainty that the action can be completed in the time available, and the evaluation should take into consideration the number of actions required and the environment conditions that are expected. However, Exelon had not explicitly evaluated the level of certainty and time requirements given the travel, actions, environment conditions, and collateral duties.

The inspectors noted that the risk assessment for LGS yielded a change in fire risk color from Green to Blue given the associated EDGs not available. Therefore, the inspectors determined the most applicable scenario according to the risk assessment was a fire causing sufficient damage to require the contingency plan. Therefore, the designated operator having the fire brigade collateral duty, with the uncertainties, hazards, and necessary exertion and stress inherent to performing that duty, was not consistent with the procedures. The inspectors also considered the aggregate impact of all of the identified issues and determined the collateral duties did interfere with the designated response and the level of certainty established by the contingency plan was not virtual certainty and therefore the plan was not in accordance with the applicable procedures.

Corrective Actions: Following identification on August 6, 2018, Exelon initially considered the EDG unavailable yielding Blue fire risk for the site and implemented the required fire risk mitigating actions. Exelon then improved the pre-brief and pre-staging of the contingency plan. Exelon later ensured the designated operator was not a member of the fire brigade, evaluated the required actions following additional improvements, and restored the EDG to (a)(4) available status.

Corrective Action Reference: IR 4162782

Performance Assessment:

Performance Deficiency: The inspectors determined the failure to assess and manage risk associated with fuel oil storage tank maintenance by not properly evaluating and establishing compensatory actions for maintaining availability of associated EDGs was reasonably within Exelons ability to foresee and correct and should have been prevented.

Screening: The inspectors determined the performance deficiency was more than minor because it adversely affected the Protection Against External Factors and Procedure Quality attributes of the Mitigating Systems cornerstone to ensure the availability and reliability of systems that respond to initiating events to prevent undesirable consequences (i.e., core damage). Specifically, the established contingency plan was not adequate in accordance with station procedures to maintain the availability of the associated EDG. Additionally, it was similar to example 7.e of IMC 0612, Appendix E, Examples of Minor Issues, because the failure to adequately assess and manage risk is more than minor if it would have placed overall plant risk in a higher licensee-established risk category. In this case, the overall elevated plant risk associated with the performance deficiency would put the plant into a higher licensee-established risk category (i.e. fire risk Blue).

Significance: Using IMC 0609.04, Initial Characterization of Findings, and IMC 0609, Appendix K, Maintenance Risk Assessment and Risk Management Significance Determination Process, the inspectors determined that the failure to assess and manage risk associated with fuel oil storage tank maintenance required further assessment. A Region I Senior Risk Analyst determined the risk deficit using the following: The total risk was the incremental core damage probability deficit (ICDPD) for the EDG being inoperable due to random failures added to the ICDPD for the increased risk of external events/fire. The exposure periods were five days for D11 EDG and one day for D12 EDG, with the EDG conservatively analyzed to start and then run for only two hours while being supplied from the associated EDG day tank. The contingency plan, although not adequate, provided a degree of capability and awareness in order to be credited as one to two risk management actions in accordance with IMC 0609, Appendix K.

Using SAPHIRE 8 Version 8.1.8 and LGS Unit 1 SPAR model Version 8.50, the assessment set the D11 EDG to fail to continue running for 5 days. This yielded an ICDP of 5.92 E-7/yr.

Since this issue is for an increase in fire risk, the Senior Risk Analyst used the External Initiators Risk-Informed Inspection Notebook for Limerick Generating Station Units 1 and 2, Revision 1, to estimate the risk due to fire. Using Table 3.2, this represented a Fire Group J issue, and the ignition frequency for Fire Group J is 5.46 E-4 fires/reactor-year. Using Table 3.3.10, Significance Determination Process Worksheet for LGS - Fire Group J (Fire resulting in a Dual Unit LOOP (Scenario 20-C), the ICDPD from fire was estimated to be 5 E-7/yr.

Adding the random and external events numbers together the total risk deficit is approximately 1.92 E-6/yr. Therefore, since the risk deficit is greater than 1E-6 but less than 1E-5, and one to two risk management actions were taken, and the ICDP is less than 5E-6, the Senior Risk Analyst determined the finding was of very low safety significance (Green).

Cross-Cutting Aspect: The inspectors determined this finding has a cross-cutting aspect in the area of Human Performance, Procedure Adherence, because Exelon personnel did not recognize all procedural requirements for establishing a designated operator, did not follow the procedure verbatim with respect to establishing virtual certainty, and did not follow the procedure when choosing the individual to be designated operator. [H.8]

Enforcement:

Violation: 10 CFR 50.65(a)(4) states that before performing maintenance activities, the licensee shall assess and manage the increase in risk that may result from the proposed maintenance activities. Contrary to this, on July 30, 2018, to August 3, 2018, and on August 6, 2018, Exelon did not adequately assess and manage the increase in risk from maintenance on the D11 fuel oil storage tank and D12 fuel oil storage tank, respectively.

Disposition: This violation is being treated as an NCV, consistent with Section 2.3.2 of the Enforcement Policy.

Failure to Correct Adverse Environmental Conditions Impacting Low Pressure Coolant Injection Outboard Primary Containment Isolation Valve Cornerstone Significance Cross-Cutting Report Aspect Section Barrier Integrity Green H.13 - Human 71153 NCV 05000352/2018003-02 Performance -

Opened/Closed Consistent Process A self-revealed Green NCV of 10 CFR Part 50, Appendix B, Criterion XVI was identified when Exelon failed to correct adverse environmental conditions affecting the Unit 1 LPCI outboard PCIV actuator that resulted in long term water intrusion, corrosion, and failure of the valve to stroke closed.

Description:

LGS Unit 1 has four LPCI trains for which an outboard injection/isolation valve provides PCIV capability. In addition, for the A and B LPCI trains, closing the outboard injection PCIV allows the operation of drywell spray, suppression pool spray, and/or suppression pool cooling.

On June 13, 2017, Exelon identified a steam leak from the Unit 1 reactor water cleanup suction isolation valve. The function of the valve is to permit maintenance on the reactor water cleanup system. Exelon evaluated the potential impact of the steam leak worsening on the reactor water cleanup system and decided to monitor the condition. On September 8, 2017, Exelon identified a Unit 1 Division 1 safeguard battery ground located in the actuator of the Unit 1 A LPCI outboard PCIV. Exelon determined the steam leak caused water to intrude into the compartment. Exelon cleaned accessible portions of the valve actuator compartment and repaired the steam leak. On March 27, 2018, Exelon opened the A LPCI outboard PCIV for reverse flushes of the shutdown cooling piping, and the valve failed to close due to tripping the torque switch.

Exelon performed a cause evaluation and determined that the torque switch mechanical parts were corroded due to the water that entered the limit switch compartment during the steam leak. Although the compartment was chemically cleaned, not all internal components were fully accessible, including the torque limit switch spring pack which was compressed with the valve in the closed position. Exelon did not disassemble internal components in order to not disturb mechanical or electrical functions. Exelon determined that the risk assessment for the steam leak was narrowly focused on the reactor water cleanup system and did not consider potential impacts to surrounding equipment. The inspectors concluded the steam plume was an adverse environmental condition that was not corrected in a timely fashion.

Corrective Actions: Exelon replaced the Unit 1 A LPCI outboard injection PCIV actuator compartment affected components, including the torque switch and limit switch pack. Exelon conducted additional technical human performance training and communicated a case study and lessons learned to target personnel.

Corrective Action References: IR 2680871, IR 4050248, and IR 4122520

Performance Assessment:

Performance Deficiency: The inspectors determined the failure to correct adverse environmental conditions impacting the Unit 1 A LPCI outboard injection PCIV actuator that resulted in long term water intrusion, corrosion, and failure of the valve to stroke closed was reasonably within Exelons ability to foresee and correct and should have been prevented.

Screening: The inspectors determined the performance deficiency was more than minor because it adversely affected the Structure, System, and Component and Barrier Performance attribute of the Barrier Integrity cornerstone to provide reasonable assurance that physical design barriers (containment) protect the public from radionuclide releases caused by accidents or events.

Significance: The inspectors assessed the significance of the finding using IMC 0609, Appendix H, Containment Integrity Significance Determination Process, Table 6.2, Phase 2 Risk Significance -Type B Findings at Full Power. The inspectors determined the finding was of very low safety significance (Green) because the A LPCI inboard isolation check valve was functional, the suppression pool cooling function was able to be performed via an alternate pathway, and the drywell/suppression pool spray system function was not lost since the B train was not affected.

Cross-Cutting Aspect: The inspectors determined this finding has a cross-cutting aspect in the area of Human Performance, Consistent Process, because Exelon did not utilize or incorporate appropriate risk insights such that the decision-making process was narrowly focused and previous operational decisions were not re-evaluated when conditions worsened.

[H.13]

Enforcement:

Violation: 10 CFR Part 50, Appendix B, Criterion XVI, Corrective Action, requires, in part, that measures shall be established to assure that conditions adverse to quality, such as deficiencies, defective material, and non-conformances are promptly identified and corrected.

Technical Specification (TS) 3.6.3.a.2 requires that with an inoperable PCIV the penetration must be isolated with a de-energized PCIV within four hours or be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in cold shutdown within the next 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. TS 3.6.2.2 requires that with an inoperable suppression pool spray flow path on one of the residual heat removal loops, to return the loop to the operable status within seven days or be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in cold shutdown within the next 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Contrary to the above, from June 13, 2017, to March 27, 2018, Exelon did not correct a condition adverse to quality. Specifically, an adverse environmental condition existed that was not promptly corrected and caused the Unit 1 A LPCI outboard PCIV to fail to close.

This caused the PCIV to be inoperable, and the required actions to isolate the penetration and de-energize the PCIV within four hours or be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in cold shutdown with the next 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> were not taken. This also caused the suppression pool spray flow path to be inoperable, and the required actions to return the loop to the operable status within seven days or be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in cold shutdown within the next 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> were not taken.

Disposition: This violation is being treated as an NCV, consistent with Section 2.3.2 of the Enforcement Policy. The disposition of this violation closes LER 05000352/2018002.

Observations 71152 Annual Follow-up of Selected Issues Human performance issues caused the Unit 1 E condensate deep bed to be inadvertently removed from service and the Unit 1 A residual heat removal heat exchanger to be unnecessarily flushed (IRs 04041650 and 04051348)

Overall, based on the documents reviewed, main control room and field observations, and discussions with operations personnel, the inspectors observed compliance with human performance tools and noted that Exelon personnel identified problems and entered them into the corrective action program at a low threshold.

However, the inspectors identified un-controlled operator aids, meeting the definition of operator aids in procedure OP-AA-115-101, Operator Aid Postings, in both the Unit 1 and Unit 2 portions of the main control room. Specifically, six copies of pages from two controlled documents were located under the Control Room Supervisors desks plexiglass that were no longer the latest revisions available. Procedure OP-LG-103-102-1000, Revision 76, no longer existed, yet page 18 was observed in four locations. Page 39 of OP-AA-101-111-1001, Revision 19, was observed in two locations, yet the latest revision was 20.

The inspectors informed the operations Shift Manager of the un-controlled operator aids, and the operator aid pages were removed from the main control room. This issue is considered minor because the information contained in the operator aid pages was not contrary to updated direction. Thus, the inspectors determined this issue was a deficiency of minor safety significance, and therefore, was not subject to enforcement action in accordance with the NRCs Enforcement Policy. Exelon documented this issue in IR 4168714.

Observations 71152 Annual Follow-up of Selected Issues Failure of rod position indication power supplies on Units 1 and 2 (IRs 03986074, 03988302, 03990303, 04003680, 04011371, and 04076445)

The rod position indication system is a non-safety-related system. Failure of one power supply results in loss of rod position and rod drift indication for 83 of 185 control rods. In 2017, Limerick experienced two failures on Unit 1 and two failures on Unit 2. For each failure, the inspectors noted that Exelon appropriately entered TS 3.1.3.7 which requires operators, in part, to determine the position of the control rod using an alternate method within one hour, or be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. With one exception, discussed below, Exelon appropriately determined the position of the affected control rods using an alternate method, and replaced the power supply in each case.

The inspectors noted that for the power supply failure documented in IRs 03986074 and 03988302, Exelon identified that the operators did not use a valid alternate means to determine rod position for the affected control rods, and therefore did not comply with TS 3.1.3.7 requirements. This TS non-compliance was documented as a licensee-identified violation in NRC Integrated Inspection Report 05000352/2017002 and 05000353/2017002 (ADAMS Accession No. ML17214A658). Corrective actions from this issue included improving station procedures related to determining rod position via alternate methods, developing a new abnormal operating procedure for full or partial loss of the rod position indication system, and updating the associated alarm response card to reference these procedures. The inspectors verified that Exelon used a valid method to determine rod position for the subsequent failures.

The inspectors also noted that this system was scoped into the maintenance rule program, with the performance monitoring criteria of less than or equal to two functional failures in two years per unit. The inspectors verified that Exelon appropriately tracked these power supply failures as system functional failures. Exelon also implemented a corrective action which recently installed a modification on both units that added redundant power supplies to the rod position indication system. As such, when a single power supply fails, the redundant power supply will be available, thus preventing loss of rod position and rod drift indication for the associated control rods. The inspectors determined this action was reasonable and timely, given that it was completed prior to the station exceeding the maintenance rule performance criteria.

EXIT MEETINGS AND DEBRIEFS

On October 19, 2018, the inspectors presented the inspection results to Mr. Frank Sturniolo, Plant Manager, and other members of the Exelon staff.

The inspectors verified no proprietary information was retained or documented in this report.

THIRD PARTY REVIEWS The inspectors reviewed Institute of Nuclear Power Operations reports that were issued during the inspection period.

DOCUMENTS REVIEWED

71111.13

Procedures

OP-LG-108-117-1000, Limerick Protected Equipment Program, Revision 5

S92.6.N, Diesel Oil Storage Tank Lineup to Fill Other than Its Associated Day Tank, Revision 13

WC-AA-101, On-Line Work Control Process, Revision 28

WC-AA-101-1006, On-Line Risk Management and Assessment, Revision 2

Condition Reports

1572759

4162782

71152

Procedures

ARC-MCR-208 E5, RPIS Inoperative, Revision 5

HU-AA-101, Human Performance Tools and Verification Practices, Revision 9

HU-AA-102, Technical Human Performances, Revision 7

ON-127, Loss of RPIS, Revision 1

OP-AA-1, Conduct of Operations, Revision 1

OP-AA-101-111-1001, Operations Standards and Expectations, Revision 20

OP-AA-112-101, Shift Turnover and Relief, Revision 14

OP-AA-115-101, Operator Aid Postings, Revision 2

OP-LG-102-1000, Operations Peer Check Program, Revision 4

OP-LG-103-102-1000, Human Performance Continuing Good Practices

PI-AA-125, Corrective Action Program (CAP) Procedure, Revision 6

ST-6-092-311-1, D11 Diesel Generator Slow Start Operability Test Run, Revision 103

ST-6-107-361-1, Inoperable Rod Position Indication Actions, Revision 2

ST-6-107-590-1, Daily Surveillance Log - OPCONs 1, 2, 3, Revision 181

Condition Reports

3986074 3988302 3990303 3991456 4003680 4011371

4041650 4051348 4076445 4154000 4157086 4168179

4168714*

• Generated in response to this inspection.

Maintenance Orders/Work Orders

R0763463

264663

04640369

Miscellaneous

Limerick Generating Station Updated Final Safety Analysis Report

Maintenance Rule System Basis Document: Limerick Unit 1 Reactor Manual Control System

71153

Condition Reports

2680871 4049572 4050248 4122520