IR 05000254/2022090

NRC Inspection Report 05000254/2022090 and 05000265/2022090; Preliminary White Finding

ML22209A232
Person / Time
Site:	Quad Cities
Issue date:	08/08/2022
From:	Julio Lara NRC/RGN-III/DRP/B1
To:	Rhoades D Constellation Energy Generation, Constellation Nuclear
References
EA-22-062 IR 2022090
Download: ML22209A232 (15)

Text

August 8, 2022

SUBJECT:

QUAD CITIES NUCLEAR POWER STATION - NRC INSPECTION REPORT 05000254/2022090 AND 05000265/2022090; PRELIMINARY WHITE FINDING

Dear Mr. Rhoades:

This letter transmits a finding that has preliminarily been determined to be White, a finding of low to moderate safety significance. As described in the enclosed report, on March 21, 2022, one of the four electromagnetic relief valves (ERV) associated with the automatic depressurization subsystem (ADS) failed to actuate during surveillance testing. A subsequent investigation identified that the failure was caused by internal binding of the valve actuator due to the improper rebuild of the actuator prior to being installed on April 7, 2020. As a result, the valve was inoperable from April 7, 2020, until March 21, 2022, resulting in decreased reliability of the ADS. The ADS is a subsystem of the emergency core cooling system and is an alternate to the high-pressure coolant injection subsystem. The ADS functions to depressurize the reactor pressure vessel in the event of a small break loss-of-coolant accident, should the high-pressure coolant injection subsystem fail, to allow the low-pressure coolant injection subsystem or the core spray subsystem to provide adequate core cooling. An extent-of-condition review identified no similar operability concerns with the remaining Unit 2 or Unit 1 ERVs.

This finding was assessed based on the best available information, using the applicable Significance Determination Process (SDP). The basis for the NRCs preliminary significance determination is described in the enclosed report. Important assumptions used in the staffs significance determination include a 2 of 5 success criteria for depressurization and the contribution of common cause failure potential associated with the electromatic relief valves.

The final resolution of this finding will be conveyed in separate correspondence. As described in NRC Inspection Manual Chapter 0612, a finding may or may not be associated with regulatory non-compliance and, therefore, may or may not result in a violation. Based on the review of this issue and in accordance with NRC Inspection Manual Chapter 0612, the NRC determined that the finding is also an apparent violation of NRC requirements and is being considered for escalated enforcement action in accordance with the 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 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 we make 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 the NRC 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 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. 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. If you decide to submit only a written response, such submittal should be sent to the NRC within 40 days of your 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 NRC Inspection Manual Chapter 0609.

If you choose to send a response, it should be clearly marked as a "Response to (An) Apparent Violation(s); (EA-22-62)" and should include for the apparent violation(s): (1) the reason for the apparent violation(s) or, if contested, the basis for disputing the apparent violation(s); (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. Your response should be submitted under oath or affirmation and may reference or include previously docketed correspondence, if the correspondence adequately addresses the required response.

Additionally, your response should be sent to the U.S. Nuclear Regulatory Commission, ATTN: Document Control Center, Washington, DC 20555-0001 with a copy to Robert Ruiz, Chief Reactor Projects Branch 1, U.S. Nuclear Regulatory Commission, Region 3, 2443 Warrenville Road, Suite 201, Lisle, IL 60532, within 40 days of the date of this letter. If an adequate response is not received within the time specified or an extension of time has not been granted by the NRC, the NRC will proceed with its enforcement decision or schedule a Regulatory Conference.

Please contact Robert Ruiz at 630-829-9732 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 these inspection findings at this time. In addition, please be advised that the number and characterization of the apparent violation(s) 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 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, Signed by Lara, Julio on 08/08/22 Julio F. Lara for Jamie Heisserer, Deputy Director Division of Reactor Safety Docket Nos. 05000254 and 05000265 License Nos. DPR-29 and DPR-30

Enclosures:

Inspection Report Nos.

05000254/2022090; 05000265/2022090

Inspection Report

Docket Numbers: 05000254 and 05000265 License Numbers: DPR-29 and DPR-30 Report Numbers: 05000254/2022090 and 05000265/2022090 Enterprise Identifier: I-2022-090-0004 Licensee: Constellation Nuclear Facility: Quad Cities Nuclear Power Station Location: Cordova, IL Inspection Dates: May 23, 2022 to July 14, 2022 Inspectors: Z. Coffman, Resident Inspector C. Hunt, Senior Resident Inspector L. Kozak, Branch Chief C. Mathews, Illinois Emergency Management Agency N. Shah, Senior Project Engineer D. Szwarc, Senior Reactor Analyst Approved By: Robert Ruiz, Chief Branch 1 Division of Reactor Projects Enclosure

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a NRC inspection at Quad Cities Nuclear Power Station, 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.

List of Findings and Violations

02-0203-3B Electromatic Relief Valve Failed to Operate During As-Found Testing During Refueling Outage Q2R26 Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Preliminary White [H.14] - 71153 Systems AV 05000254,05000265/2022090-01 Conservative Open Bias EA-22-062 On March 21, 2022, a self-revealed finding with preliminary White significance and an associated apparent violation of 10 CFR 50, Appendix B, Criterion V, "Instructions,

Procedures, and Drawings," was identified when the 2-0203-3B electromatic relief valve (ERV) failed to actuate during as-found testing during the Q2R26 refueling outage. The licensee transmitted Licensee Event Report (LER) 05000265/2022-001-00, "Electromatic Relief Valve 3B Did Not Actuate Due to Incorrectly Oriented Plunger Well Plastic Guides," on May 20, 2022.

Additional Tracking Items

Type Issue Number Title Report Section Status URI 05000265/2022090-02 Potential Technical 71153 Open Specification Violation Associated With the Failure of the 2-0203-3B ERV LER 05000265/2022-001-00 LER 2022-001-00 for Quad 71153 Closed Cities Nuclear Power Station, Unit 2, Electromatic Relief Valve 3B Did Not Actuate Due to Incorrectly Oriented Plunger Well Plastic Guides

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 reviewed selected procedures and records, observed activities, and interviewed personnel to assess licensee performance and compliance with Commission rules and regulations, license conditions, site procedures, and standards.

OTHER ACTIVITIES - BASELINE

71153 - Follow Up of Events and Notices of Enforcement Discretion Event Report (IP Section 03.02)

The inspectors evaluated the following licensee event reports (LERs):

(1) LER 05000265/2022-001-00, "Electromatic Relief Valve 3B Did Not Actuate Due to Incorrectly Oriented Plunger Well Plastic Guides," (ADAMS Accession No. ML22140A128). The inspection conclusions associated with this LER are documented in this report under Inspection Results Section

INSPECTION RESULTS

02-0203-3B Electromatic Relief Valve Failed to Operate During As-Found Testing During Refueling Outage Q2R26 Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Preliminary White [H.14] - 71153 Systems AV 05000254,05000265/2022090-01 Conservative Open Bias EA-22-062 On March 21, 2022, a self-revealed finding with preliminary White significance and an associated apparent violation of 10 CFR 50, Appendix B, Criterion V, "Instructions, Procedures, and Drawings," was identified when the 2-0203-3B electromatic relief valve (ERV) failed to actuate during as-found testing during the Q2R26 refueling outage. The licensee transmitted Licensee Event Report (LER) 05000265/2022-001-00, "Electromatic Relief Valve 3B Did Not Actuate Due to Incorrectly Oriented Plunger Well Plastic Guides," on May 20, 2022.

Description:

On March 21, 2022, the licensee attempted to cycle the 2-0203-3B ERV for as-found testing at the beginning of refueling outage Q2R26 but the valve did not stroke as expected. Later investigation by the licensee determined that the valves solenoid actuator was binding during operation, preventing the 3B ERV from opening. The licensee documented the condition in the corrective action program (CAP) under Action Request (AR) 4486294.

The automatic depressurization subsystem (ADS) of the emergency core cooling system is an alternate to the high-pressure coolant injection subsystem meant to depressurize the reactor pressure vessel in the event of a small break loss-of-coolant accident to allow the low-pressure coolant injection subsystem or the core spray subsystem to provide adequate core cooling. The ADS contains five valves, four ERVs and one Target Rock valve that functions as an ADS valve and code safety-relief valve.

The licensee performed a failure analysis on the 2-0203-3B solenoid actuator and determined that the cause of the failure was due to two conditions: incorrect installation of the internal plunger well plastic guides, which decreased clearances for the plunger to move within the plunger well, and a warped upper guide bracket that caused increased friction in the plunger well. The licensee performed a corrective action program evaluation (CAPE) and determined:

Both the improper plastic guide installation and the bent upper guide bracket are required for the failure to happen. This is because clearances within the actuator are important for operation and when the clearances are not met and the actuator is required to overcome the friction and force of the tighter tolerances, the actuator becomes damaged and can subsequently fail.

The inspectors reviewed the circumstances surrounding the rebuild of the solenoid actuator for the 2-0203-3B ERV which occurred under Work Order (WO) 4804706 using QCEM 0200-13, Dresser Electromatic Solenoid Actuator Rebuild Instructions, Revision 10.

The inspectors noted that during a normal actuator rebuild, several components on the actuator are allowed to be reused if they pass inspection, per the rebuild procedure. Upon disassembly of the 3B ERV actuator on January 22, 2020, the licensee inspected the upper guide bracket per step 4.2.5 of QCEM 0200-13 and determined that the bracket was straight and flat, which allowed the bracket to be reused. However, in step 4.3.1.1.C of the same procedure, technicians were directed to calculate the amount of material loss on the plunger legs due to wear. If the wear is greater than 5 percent, the procedure directs the technicians to contact engineering for disposition of the rejected part and order a new one for installation.

In this case, the technicians calculated the material loss to be 10 percent, prompting them to obtain a new plunger for installation per procedural direction.

Installation of a new plunger on the upper guide bracket is done per Attachment 2 of QCEM 0200-13. As written in the work order notes, the technicians retrieved two new plungers from stores, but noted that both new plungers were narrower than the plunger that was removed from service. The first attempt at installing a new plunger resulted in the bowing of the upper guide bracket when the plunger and the upper guide bracket were torqued in accordance with Attachment 2. The bow resulted in the plunger binding in the plunger well when the technicians manually actuated the assembly. The technicians returned the first plunger to stores and then attempted to install the second plunger which also caused bowing of the upper guide bracket when torqued per procedure, again resulting in binding during manual actuation. The technicians took a picture of the bow for the work package, but did not document the condition in the CAP.

Following a pause in the rebuild, the electrical maintenance department (EMD) submitted an engineering request to the engineering department to assess the use of shims between the plunger and the upper guide bracket to prevent the torquing of the bracket to a smaller sized plunger from causing a bow in the bracket. Engineering drafted Engineering Change Report (ECR) 445332 to address the condition and concluded, with acceptance from the original equipment manufacturer (General Electric [GE]), that stainless steel shims were acceptable for use:

GE has determined that the use of shims between the upper guide bracket and the plunger are acceptable to reduce warping of the bracket and eliminate binding when the valve is stroked.

The last update for ECR 445332 was documented in the licensee document control database on February 28, 2020. The ECR guidance was eventually rolled into QCEM 0200-13, Revision 11, but the information was never used to address the bowing of the upper guide bracket noted during the rebuild of the 3B ERV in WO 4804706 started in January 2020. On March 20, 2020, technicians manually straightened the upper guide bracket and noted that they achieved smooth movement when manually actuating the plunger on the bench. The solenoid actuator was installed on April 7, 2020, under WO 4812170, prior to startup from the Q2R25 refueling outage, where it was cycled several additional times. The valve failed to cycle during as-found testing 2 years later on March 21, 2022.

In the licensees CAPE, the licensee states:

The upper guide bracket was identified as not being straight as a part of the pre-Q2R25 rebuild WO 4804706-01 but corrected by manually straightening the upper guide bracket per procedural guidance.

The inspectors discussed this statement with the licensee and specifically asked for the procedure, including the step that directed technicians how to perform the manual straightening of the upper guide bracket, an activity affecting quality, and the acceptance criteria used to determine whether the straightening was successfully accomplished. The licensee pointed to step 3.2.7 of QCEM 0200-13 which states:

When making maintenance inspections, it is understood that the maintenance Electrician will resolve any minor inspection discrepancy that does not require disassembly unless replacement of parts are identified in the body of the Procedure. Minor discrepancies are defined (as removal of surface contaminates on components, panels, cable, etc. and/or tightening of loose fittings, covers, connections, terminations, etc.) by performing in-process housekeeping tasks. Minor discrepancies of this type must be resolved by this method PRIOR to initialing and dating the applicable Procedure step. Any in-process actions taken shall be documented in the Remarks section of this Procedure.

The inspectors noted that step 3.2.7 did not contain explicit instructions on how to manually straighten the bracket. When specifically asked how the bracket was straightened to achieve flatness, the licensee could not provide details on how the activity was accomplished.

Additionally, since there were no shims used between the plunger and the upper guide bracket after manually straightening the bracket, the inspectors questioned how the technicians were able to torque the newly straightened upper bracket to the narrower plunger without recreating the bow. The licensee was unable to provide details on how the retorque was accomplished. The inspectors questioned whether the upper guide bracket was rechecked for flatness per step 4.2.5 of QCEM 0200-13 after being straightened given that the bracket was attached to a different plunger than what was originally inspected, and activities affecting its flatness had taken place. The licensee stated that no recheck for flatness on the straightened upper guide bracket was performed because it wasnt directed by procedure after changing out the plunger in accordance with Attachment 2.

The inspectors noted that QCEM 0200-13, Step 4.2.5, explicitly directs the technicians to replace the upper guide bracket per Attachment 2 of QCEM 0200-13 if it does not pass inspection (i.e., the bracket is not able to be verified straight and flat). Therefore, the provisions of step 3.2.7 do not apply. Specifically:

When making maintenance inspections, it is understood that the maintenance Electrician will resolve any minor inspection discrepancy that does not require disassembly unless replacement of parts are identified in the body of the Procedure.

Therefore, the inspectors determined that a provision for manually straightening the bracket was outside of what was allowed by QCEM 0200-13 and not available to the technicians after they introduced a bow in the upper guide bracket.

With respect to acceptance criteria, the licensee stated that the acceptance criteria used to determine that straightening the bracket was successful was included in several procedural steps incorporated in QCEM 0200-13, which have the technicians periodically verify smooth operation of the plunger by manually actuating it:

VERIFY plunger is able to move freely up and down the guideposts without binding. The bushings within the upper guide bracket should float freely with little to no friction along the spring guideposts during full ERV solenoid actuator actuations. Smooth operation is considered to be little to no friction during operation with a visible bounce of the solenoid plunger following actuation.

The inspectors noted that the ERV solenoid actuators are rebuilt in a cooler environment than would be experienced in the drywell during operation of the plant. The inspections and measurements directed by QCEM 0200-13 are performed to account for the clearances required between the plunger and the plunger well at operating conditions when thermal expansion of valve components has taken place. A reduction in these clearances caused by the warping of an upper guide bracket, and the resulting increased friction during operation, may not be discovered during manual actuation of the valve on the bench, or even automatic actuation during testing prior to startup, because thermal expansion has not yet taken place.

Therefore, achieving smooth motion during manual actuation of the actuator on the work bench does not mean that the upper guide bracket was successfully straightened as implied by the licensee in the CAPE. Additionally, the inspectors questioned why manually straightening the upper bracket was performed in lieu of adding shims, as approved by ECR 445332, given that the information in the ECR was available as early as February 28, 2020, and the valve was installed April 7, 2020. The licensee was not able to provide an answer to that question.

In addition, the inspectors noted that during the failure analysis the licensee discovered that the plastic guides located in the plunger well were installed incorrectly. The incorrect orientation of the plastic guides reduced the available clearance between the plunger and the plunger well during valve actuation. General Electric documentation for rebuilding the solenoid actuator is contained in the licensees Vendor Equipment Technical Information Program Manual. Concerning the orientation of the plastic guides, vendor rebuild guidance states in step 3.9:

Locate the plastic plunger guides inside the frame. Note their positioning for later verification of proper installation.

And then in step 3.18:

Verify that the two plastic guides are properly installed in the solenoid frame.

QCEM 0200-13, Revision 10, step 4.8.5, performed under WO 4804709 states:

Install plunger in the solenoid as follows:

1. Verify the 2 plastic guides are installed in solenoid frame.

The inspectors determined that although the vendor guidance did not explicitly provide guidance on the orientation of the plastic guides, there was enough information provided to the licensee to determine that there was a correct way, and conversely, an incorrect way to install the guides. The transference of the vendor guidance into the licensees procedure reduced the two steps in the vendor guidance into one and omitted the details noting the proper position for installation of the plastic guides. Additionally, a future revision of the rebuild procedure, QCEM 0200-13, Revision 11, contained enhancements resulting from a previous failure of an ERV to actuate. Although the cause of that failure was not attributed to the installation of the plastic guides, the enhancement to step 4.8.5 included a picture of the correct orientation of the guides as well as a description of how the guides should be installed. The inspectors noted that, up until QCEM 0200-13, Revision 11, the correct installation of the plastic guides was likely left up to the experience of the technicians performing the rebuild.

Generic Letter 90-03, Relaxation of Staff Position in Generic Letter 83-28, Item 2.2 Part 2, Vendor Interface for Safety-Related Components, states, in part, that the licensees vendor interface program should take into account the requirements of 10 CFR Part 50, Appendix B, which requires the licensee to be responsible for establishing and executing a quality assurance program. Specifically, the licensee may delegate to others the work of establishing and executing the quality assurance program or any part of it, but the licensee shall retain responsibility for the program. As such, the licensee should have a program which assures that procedures and instructions are properly prepared and implemented.

The inspectors determined that the licensee failed to have documented instructions specifying the correct orientation for the installation of the plastic guides, an activity affecting quality, resulting in the guides being installed incorrectly and reducing the available clearance between the plunger and the plunger well.

Corrective Actions: The licensee performed a failure analysis of the 2-0203-3B solenoid actuator and documented the cause of the failure in CAPE 4486294. Additionally, the licensee performed extent-of-condition inspections on the four rebuilt ERV solenoid actuators scheduled to be installed during the Q2R26 refueling outage to verify that similar conditions did not exist with the rebuilt actuators that could lead to the same failure.

Corrective Action References: AR 4486294, "ERV 2-0203-3B Relief Valve Failed to Actuate"

Performance Assessment:

Performance Deficiency: The inspectors determined that the failure to perform an activity affecting quality in accordance with a documented procedure or instruction, containing the appropriate acceptance criteria for determining that activity had been satisfactorily accomplished, was a performance deficiency. Specifically, the licensee failed to have documented instructions specifying the correct orientation of the two plastic guide pieces in the 2-0203-3B ERV plunger well. Additionally, the licensee failed to have a documented procedure or instruction for manually straightening the upper guide bracket, including acceptance criteria for whether the activity was satisfactorily accomplished, after technicians introduced a bow in the bracket during the rebuild of the actuator.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Equipment Performance 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 failure of the 2-0203-3B ERV adversely affects the reliability of the ADS per Technical Specification (TS) basis 3.5.1, H.1.

Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The inspectors screened the finding in accordance with Inspection Manual Chapter (IMC) 0609, Appendix A, Exhibit 2, and determined that the finding required a detailed risk evaluation per step 3. Specifically, the inspectors treated the failure of the 2-0203-3B ERV as the loss of one train of a multi-train TS system for greater than its TS-allowed outage time of 14 days.

The senior reactor analysts (SRAs) evaluated the finding using the Quad Cities Standardized Plant Analysis Risk (SPAR) model version 8.80, Systems Analysis Programs for Hands-on Integrated Reliability Evaluations (SAPHIRE) version 8.2.6.

The SRAs made the following assumptions while performing the risk evaluation:

The ERV actuator was rebuilt in the spring 2020 outage, installed on April 7, 2020, and subsequently failed on March 21, 2022. An exposure time of 1 year was used in accordance with the NRCs Risk Assessment of Operational Events (RASP) manual.

The failure of ERV 3B existed during the entire operating cycle due to the actuator being rebuilt and installed in an inappropriate manner. As a result, basic event ADS-SRV-CC-ERV3B, Electromatic Relief Valve 203-3B Fails to Operate, was used to model the failure and was set to True. All other basic events were left at their nominal failure probabilities.

The ADS success criteria was modified to a 2 out of 5 logic for the depressurization fault tree. This change was made after a review of the licensees success criteria and similar documented risk evaluations at other plants.

Mitigating strategies, equipment, and response procedures (commonly referred to as FLEX) were not credited in this analysis. The SRAs determined early on that loss of offsite power station blackout scenarios were not part of the dominant sequences and therefore crediting FLEX equipment would not have been a significant contributor to risk. The SRAs ran the SPAR model with FLEX credit and verified that the change in risk was not a significant contributor to the overall risk.

The SRAs concluded that no repair or recovery credit should be given as the ERV cannot be manually operated due to the performance deficiency and the ERV actuators cannot be replaced at-power.

The SRAs made the following additional changes to the Quad Cities SPAR model version 8.80 to reflect the best available information:

o The logic representing the safety relief valve overpressure function, important for anticipated transient without scram sequences, was changed to account for the degraded condition. The analysts added ERVs to the logic and changed the overpressure success criteria.

o The basic event calculation representing ADS valve common cause failure (ADS-SRV-CF-EMRVS) was changed from staggered to non-staggered to reflect the ERV maintenance schedule since the actuators for all four ERVs are rebuilt during each outage.

o The logic representing the shutdown makeup pump was changed to allow for operator recovery of room cooling using the fire protection system upon a loss of service water.

The SRAs estimated the risk contribution from internal events for an exposure period of 1 year to be 2.9E-6/year. The dominant core damage sequence for internal events was a small loss-of-coolant accident initiating event with a failure of the power conversion system, main feedwater, high-pressure coolant injection, and a failure to depressurize.

The SPAR models now have the capability to model seismic events in addition to internal flooding, tornadoes, and high winds. These external events were quantified using the SPAR model and the contribution to overall risk from these external events was calculated to be approximately 4.1E-7/year. Most of this external risk was due to seismic and internal flooding.

The SRAs reviewed the licensees fire risk results since the Quad Cities SPAR model does not evaluate fire risk. The licensee calculated the change in core damage frequency (CDF)due to fire to be approximately 6.6E-7/year. The dominant fire cut-sets involve fires in the electro-hydraulic control skids, turbine building transient fires, electrical cabinet fires, and transformer fires. These fires cause a loss of condenser vacuum, high-pressure injection fails, and depressurization fails due to the performance deficiency.

The total contribution to risk from External Events was estimated to be approximately 1.1E-6/year. The SRAs estimated that the total risk from internal and external events was approximately 4.0E-6/year.

The SRAs concluded that the risk should be based on the delta CDF results and that the change in the large early release frequency would not increase the overall significance of the finding.

The licensee performed a risk evaluation with consideration of common cause failure potential of the four regular ERVs and a success criterion of 2 of the 4 ERVs or 1 of the 4 ERVs and the Target Rock valve. This corresponds to the same 2 out of 5 success criteria that was ultimately used by the SRAs in the best estimate case. The licensee calculated delta CDF of 1.4E-6/year for internal events and a delta CDF of 6.6E-7/year for fire for a total delta CDF of 2.0E-6/year (White). The risk evaluation that the licensee provided to the NRC did not consider any additional external events. This evaluation was based on their approved models of record.

Cross-Cutting Aspect: H.14 - Conservative Bias: Individuals use decision making-practices that emphasize prudent choices over those that are simply allowable. A proposed action is determined to be safe in order to proceed, rather than unsafe in order to stop. Specifically, during the 2-0203-3B ERV actuator rebuild, the technicians manually straightened the bowed upper guide bracket, without procedural guidance, to achieve smooth operation of the actuator on the work bench rather than considering the approved technical solution available in ECR 445332, which was to add shims to the plunger, to address the condition.

Enforcement:

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

Contrary to the above, from January 22, 2020, to March 20, 2020, the licensee failed to have documented procedures of a type appropriate to the circumstances for rebuilding the 2-0203-3B ERV solenoid actuator, an activity affecting quality, including the appropriate acceptance criteria for determining that the activity had been satisfactorily accomplished.

Specifically, the licensee failed to provide instructions in the rebuild work package specifying the correct orientation of the two plunger well plastic guides when placing them back into the plunger well. Additionally, during the rebuild, technicians manually straightened the upper guide bracket of the solenoid actuator without the use of a documented procedure or instruction to perform the activity and without acceptance criteria to determine that the activity was accomplished satisfactorily.

Enforcement Action: This violation is being treated as an apparent violation pending a final significance (enforcement) determination.

Unresolved Item Potential Technical Specification Violation Associated With 71153 (Open) the Failure of the 2-0203-3B ERV URI 05000265/2022090-02

Description:

The inspectors have identified an unresolved item (URI) associated with the implementation of TS Limiting Condition for Operation (LCO) 3.5.1, Condition H, when 2-0203-3B was considered inoperable prior to discovery for greater than the allowed LCO completion time.

On March 21, 2022, the licensee attempted to cycle the 2-0203-3B ERV for as-found testing at the beginning of refueling outage Q2R26, but the valve did not stroke as expected. Later investigation by the licensee determined that the valve's solenoid actuator was binding during operation, preventing the 2-0203-3B ERV from opening. As a result of the degraded condition, the 2-0203-3B ERV was considered inoperable prior to discovery and a TS LCO 3.5.1, Condition H, violation may have occurred. This issue is unresolved pending the NRCs additional independent review and evaluation to determine whether a TS LCO violation occurred.

EXIT MEETINGS AND DEBRIEFS

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

On July 14, 2022, the inspectors presented the Preliminary White exit meeting inspection results to Mr. D. Griffiths, Plant Manager, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection Type Designation Description or Title Revision or

Procedure Date

71153 Corrective Action AR 4094488 Defective ERV Rebuild Parts 01/17/2018

Documents

71153 Corrective Action AR 4486294 PSU: ERV 2-0203-3B Relief Valve Did Not Actuate 03/21/2022

Documents

71153 Corrective Action AR 4498778 NRC ID: CAPE 4330737-02 Information Discrepancy 05/10/2022

Documents

Resulting from

Inspection

71153 Engineering EC 631289 Evaluation of Impact of Quad Cities on Safety Analysis due 0

Changes to ERV 2-0203-3D Relief Valve Not Actuating

71153 Engineering ECR 445332 Shims required for ERV Rebuild

Changes

71153 Miscellaneous QDC-76517 Failure Analysis of: 3B Electromatic Relief Valve Solenoid 1

Actuator

71153 Procedures QCEM 0200-13 Dresser Electromatic Solenoid Actuator Rebuild Instructions 10

71153 Procedures QCEM 0200-13 Dresser Electromatic Solenoid Actuator Rebuild Instructions 11

71153 Work Orders WO 4804706-01 00175214-01, EQ, Inspect/Repair Spare ERV Actuators 01/20/2020

Pre-outage (EQ)

11