IR 05000282/2023003
| ML23311A122 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 11/08/2023 |
| From: | Hironori Peterson NRC/RGN-III/DORS/RPB3 |
| To: | Conboy T Northern States Power Company, Minnesota |
| References | |
| IR 2023003 | |
| Download: ML23311A122 (1) | |
Text
SUBJECT:
PRAIRIE ISLAND NUCLEAR GENERATING PLANT - INTEGRATED INSPECTION REPORT 05000282/2023003 AND 05000306/2023003
Dear Thomas Conboy:
On September 30, 2023, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Prairie Island Nuclear Generating Plant. On October 26, 2023, the NRC 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 report.
Two findings of very low safety significance (Green) are documented in this report. One of these findings involved a violation of NRC requirements. We are treating this violation as a non-cited violation (NCV) consistent with Section 2.3.2 of the Enforcement Policy.
If you contest the violation or the significance or severity of the violation documented in this inspection report, 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 III; the Director, Office of Enforcement; and the NRC Resident Inspector at Prairie Island Nuclear Generating Plant.
If you disagree with a cross-cutting aspect assignment or a finding not associated with a regulatory requirement in this report, 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 III; and the NRC Resident Inspector at Prairie Island Nuclear Generating Plant.
November 8, 2023 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 at the NRC Public Document Room in accordance with Title 10 of the Code of Federal Regulations 2.390, Public Inspections, Exemptions, Requests for Withholding.
Sincerely, Hironori Peterson, Chief Reactor Projects Branch 3 Division of Operating Reactor Safety Docket Nos. 05000282 and 05000306 License Nos. DPR-42 and DPR-60
Enclosure:
As stated
Inspection Report
Docket Numbers:
05000282 and 05000306
License Numbers:
Report Numbers:
05000282/2023003 and 05000306/2023003
Enterprise Identifier:
I-2023-003-0057
Licensee:
Northern States Power Company
Facility:
Prairie Island Nuclear Generating Plant
Location:
Welch, MN
Inspection Dates:
July 01, 2023 to September 30, 2023
Inspectors:
K. Pusateri, Resident Inspector
J. Reed, Health Physicist
D. Tesar, Senior Resident Inspector
Approved By:
Hironori Peterson, Chief
Reactor Projects Branch 3
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Prairie Island Nuclear Generating Plant, 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
Failure to Effectively Implement Plant Processes and Procedures Resulting in an Initiating Event Cornerstone Significance Cross-Cutting Aspect Report Section Initiating Events Green FIN 05000306/2023003-01 Open/Closed
[H.2] - Field Presence 71111.15 A self-revealed Green finding was identified when Xcel Energy failed to perform adequate preventive maintenance on the Prairie Island Nuclear Generating Plant (PINGP) Unit 2 main bank transformer (2GT). Specifically, Xcel Energy failed to implement the programmatic requirements of their H52, Large Oil Filled Power Transformers, procedure resulting in a transformer lightning arrestor failure, a turbine trip, and reactor trip.
Failure to Adequately Evaluate Inability to Meet Acceptance Criteria for Safety-Related Bus Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000282/2023003-02 Open/Closed
[H.6] - Design Margins 71111.15 The inspectors identified a Green finding and associated non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion III, "Design Control," when the licensee failed to adequately assess the failure to meet acceptance criteria for maintenance on the safeguards bus.
Additional Tracking Items
Type Issue Number Title Report Section Status URI 05000282/2022004-01 Bus 15 Failure to Meet Acceptance Criteria 71111.15 Closed LER 05000306/2023-001-00 LER 2023-001-00 for Prairie Island Nuclear Generating Plant Unit 2, 2GT/XFMR Lockout Due to Failure of Lightning Arrester Caused Unit 2 Reactor Trip 71153 Closed
PLANT STATUS
Unit 1 operated at or near full-rated thermal power for the entire inspection period, except for brief power reductions to perform turbine control valve testing, surveillance testing, or flexible power operations.
Unit 2 began the inspection period at full-rated thermal power and remained at or near full-rated thermal power until September 19, 2023, when it entered coast down to the 2R33 refueling outage. Unit 2 was at approximately 91 percent of rated thermal power at the conclusion of the inspection period. Unit 2 was at full-rated thermal power for the remainder of the inspection period except for brief power reductions to perform surveillance testing, or flexible power operations.
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 activities described in IMC 2515, Appendix D, Plant Status, observed risk significant activities, and completed on-site portions of IPs. 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.
REACTOR SAFETY
71111.01 - Adverse Weather Protection
Seasonal Extreme Weather Sample (IP Section 03.01) (1 Sample)
- (1) The inspectors evaluated readiness for seasonal extreme weather conditions prior to the onset of seasonal extreme weather and drought conditions on July 17, 2023.
71111.04 - Equipment Alignment
Partial Walkdown Sample (IP Section 03.01) (2 Samples)
The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:
- (1) Unit 1 and Unit 2 diesel generator walkdowns during Yellow grid conditions on July 24, 2023
- (2) Unit 2 component cooling system on September 12, 2023
71111.05 - Fire Protection
Fire Area Walkdown and Inspection Sample (IP Section 03.01) (5 Samples)
The inspectors evaluated the implementation of the fire protection program by conducting a walkdown and performing a review to verify program compliance, equipment functionality, material condition, and operational readiness of the following fire areas:
- (1) Fire Zone 57, control room, on July 19, 2023
- (2) Fire Zone 87, Unit 1 rod drive room, on July 19, 2023
- (3) Fire Zone 88, Unit 2 rod control room, on July 21, 2023
- (4) Fire Zone 82, D1 diesel room, on August 17, 2023
- (5) Fire Zone 6, D2 diesel generator room, on August 18, 2023
71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance
Licensed Operator Performance in the Actual Plant/Main Control Room (IP Section 03.01) (1 Sample)
- (1) The inspectors observed and evaluated licensed operator performance in the control room during the Unit 1 down power to perform turbine valve testing per SP 1054 on September 21, 2023.
Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)
- (1) The inspectors observed and evaluated licensed operator requalification as-found simulator scenarios on July 17, 2023.
71111.12 - Maintenance Effectiveness
Maintenance Effectiveness (IP Section 03.01) (2 Samples)
The inspectors evaluated the effectiveness of maintenance to ensure the following structures, systems, and components (SSCs) remain capable of performing their intended function:
- (1) D5 diesel generator during electronic governor data collection on July 12, 2023 (2)2GT transformer and CAP 501000075490 following failure was reviewed on July 27, 2023
71111.13 - Maintenance Risk Assessments and Emergent Work Control
Risk Assessment and Management Sample (IP Section 03.01) (4 Samples)
The inspectors evaluated the accuracy and completeness of risk assessments for the following planned and emergent work activities to ensure configuration changes and appropriate work controls were addressed:
(1)intake bypass gates risk management during breaker 511 maintenance on July 7, 2023 (2)risk evaluation of 22 main feed pump lube oil lo-lo pressure trip on July 19, 2023 (3)122 fuel oil storage tank pump failure to start on August 8, 2023
- (4) MCC 1AB2 cable testing and contingency risk informed completion time on September 20, 2023
71111.15 - Operability Determinations and Functionality Assessments
Operability Determination or Functionality Assessment (IP Section 03.01) (3 Samples)
The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:
(1)21 component cooling water heat exchanger cooling water outlet control valve stop bolt replacement on July 5, 2023 (2)12 diesel-driven cooling water pump low-pressure start failure past operability review (POR) on July 18, 2023 (3)bypass of 22 main feedwater pump low-pressure suction trip on August 25, 2023
71111.24 - Testing and Maintenance of Equipment Important to Risk
The inspectors evaluated the following testing and maintenance activities to verify system operability and/or functionality:
Post-Maintenance Testing (PMT) (IP Section 03.01) (6 Samples)
- (3) WO 7000029858, "PMT/RTS of MV-32099"
- (4) SP 1106A, "12 Diesel Cooling Water Pump Monthly Test," and PMT following repair of low press start switch on July 18, 2023
- (5) WO 700127021, "121/122 FOST [Fuel Oil Storage Tank] Transfer Pump Auto Control Switch"
- (6) WO 700100796, "PMT of D1 EDG [emergency diesel generator] Following Starting Air Modification"
Surveillance Testing (IP Section 03.01) (2 Samples)
- (2) WO 700102200, "SP 1306 D2 DG [diesel generator] Relay Functional Test"
Inservice Testing (IST) (IP Section 03.01) (1 Sample)
- (1) WO 700117579, "SP 2088A Train A Safety Injection Quarterly Test"
Containment Isolation Valve (CIV) Testing (IP Section 03.01) (2 Samples)
- (1) SP 1130A, "Train A Containment Vacuum Breaker Quarterly Test," on August 10, 2023
- (2) SP 2130A, "Unit 2 Train A Containment Vacuum Breaker Quarterly Test," on August 16, 2023
71114.06 - Drill Evaluation
Select Emergency Preparedness Drills and/or Training for Observation (IP Section 03.01) (1 Sample)
- (1) Dual Site Demonstration Drill (Monticello Nuclear Generating Station / Prairie Island Nuclear Generating Station) - Common Emergency Operations Facility (EOF)capabilities demonstration drill conducted on August 21, 2023.
- Emergency preparedness drill demonstrated the response capability of the common EOF to a multi-site event. The drill included participation by offsite response organizations and was observed by inspection staff from NRC Region 3 and Federal Emergency Management Agency Region 5.
Drill/Training Evolution Observation (IP Section 03.02) (2 Samples)
The inspectors evaluated:
(1)hospital emergency exercise with contaminated injured individual on August 2, 2023 (2)emergency preparedness drill with drill and exercise performance in TSC on August 8,
RADIATION SAFETY
71124.08 - Radioactive Solid Waste Processing & Radioactive Material Handling, Storage, &
Transportation
Radioactive Material Storage (IP Section 03.01)
The inspectors evaluated the licensees performance in controlling, labeling, and securing the following radioactive materials:
(1)10 CFR 37 material storage locations (2)radioactive materials stored outside the protected area
Radioactive Waste System Walkdown (IP Section 03.02) (2 Samples)
The inspectors walked down the following accessible portions of the solid radioactive waste systems and evaluated system configuration and functionality:
(1)radioactive waste processing area (2)spent resin storage and dewatering system
Waste Characterization and Classification (IP Section 03.03) (2 Samples)
The inspectors evaluated the following characterization and classification of radioactive waste: (1)dry active waste (2)primary system resins
Shipment Preparation (IP Section 03.04) (1 Sample)
- (1) The inspectors observed the preparation of radioactive shipment 23-027.
Shipping Records (IP Section 03.05) (4 Samples)
The inspectors evaluated the following non-excepted radioactive material shipments through a record review:
(1)radioactive shipment 22-016 containing cartridge filters of class A, B, and C waste in a general design package (2)radioactive shipment 21-053 containing activated metal in a type A package (3)radioactive shipment 23-017A containing bead resin of class A waste in a general design package (4)radioactive shipment 22-015 containing cartridge filters of class A, B, and C waste in a general design package
OTHER ACTIVITIES - BASELINE
===71151 - Performance Indicator Verification The inspectors verified licensee performance indicators submittals listed below:
MS05: Safety System Functional Failures (SSFFs) Sample (IP Section 02.04)===
- (1) Unit 1 (July 1, 2022, through June 30, 2023)
- (2) Unit 2 (July 1, 2022, through June 30, 2023)
MS06: Emergency AC Power Systems (IP Section 02.05) (2 Samples)
- (1) Unit 1 (July 1, 2022, through June 30, 2023)
- (2) Unit 2 (July 1, 2022, through June 30, 2023)
MS07: High Pressure Injection Systems (IP Section 02.06) (2 Samples)
- (1) Unit 1 (July 1, 2022, through June 30, 2023)
- (2) Unit 2 (July 1, 2022, through June 30, 2023)
MS08: Heat Removal Systems (IP Section 02.07) (2 Samples)
- (1) Unit 1 (July 1, 2022, through June 30, 2023)
- (2) Unit 2 (July 1, 2022, through June 30, 2023)
MS09: Residual Heat Removal Systems (IP Section 02.08) (2 Samples)
- (1) Unit 1 (July 1, 2022, through June 30, 2023)
- (2) Unit 2 (July 1, 2022, through June 30, 2023)
MS10: Cooling Water Support Systems (IP Section 02.09) (2 Samples)
- (1) Unit 1 (July 1, 2022, through June 30, 2023)
- (2) Unit 2 (July 1, 2022, through June 30, 2023)
BI01: Reactor Coolant System (RCS) Specific Activity Sample (IP Section 02.10) (2 Samples)
- (1) Unit 1 October 1, 2022, through July 31, 2023
- (2) Unit 2 October 1, 2022, through July 31, 2023
OR01: Occupational Exposure Control Effectiveness Sample (IP Section 02.15) (1 Sample)
- (1) October 1, 2022, through July 31, 2023 PR01: Radiological Effluent Technical Specifications/Offsite Dose Calculation Manual Radiological Effluent Occurrences (RETS/ODCM) Radiological Effluent Occurrences Sample (IP Section 02.16) (1 Sample)
- (1) October 1, 2022, through July 31, 2023
71152A - Annual Follow-up Problem Identification and Resolution Annual Follow-up of Selected Issues (Section 03.03)
The inspectors reviewed the licensees implementation of its corrective action program related to the following issues:
(1)follow up of auxiliary building roof standing water/leaks QIM 501000075429 on July 26, 2023
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) Title 10 CFR 50.72 Report for Auto Start of Auxiliary Feedwater Pumps LER 2023-001-00, "2GT/XFMR lockout due to failure of lightning arrester caused Unit 2 Reactor Trip" (Agencywide Documents Access and Management System
[ADAMS] ML23199A216). The inspectors' conclusions associated with this LER are documented in this report under Inspection Results section 71111.15. This LER is closed.
INSPECTION RESULTS
Failure to Effectively Implement Plant Processes and Procedures Resulting in an Initiating Event Cornerstone Significance Cross-Cutting Aspect Report Section Initiating Events Green FIN 05000306/2023003-01 Open/Closed
[H.2] - Field Presence 71111.15 A self-revealed Green finding was identified when Xcel Energy failed to perform adequate preventive maintenance on the Prairie Island Nuclear Generating Plant (PINGP) Unit 2 main bank transformer (2GT). Specifically, Xcel Energy failed to implement the programmatic requirements of their H52, Large Oil Filled Power Transformers, procedure resulting in a transformer lightning arrestor failure, a turbine trip, and reactor trip.
Description:
On May 27, 2023, during steady state operation, a Unit 2 generator transformer (2GT/XFMR) lockout occurred due to a failure of the A-phase lightning arrester, causing a Unit 2 turbine and reactor trip.
Xcel Energy has a program in place for the maintenance strategy of large transformers under program document H52, Large Oil Filled Power Transformers. The licensee implemented this program for 2GT lightning arresters primarily through procedure PE 6033, 2GT Transformer Maintenance, which contains most of the methods of reviewing and maintaining the transformer and subcomponents system health. Per the procedure H52 for large oil filled power transformers, lightning arresters are analyzed based on dielectric loss measured in watts. This power loss testing was completed using the Doble software. Power loss testing with regular cleaning of the arresters are largely the only means of managing the long-term health of the lightning arresters.
The licensee determined that procedure PE 6033 provides vague guidance in several steps which can lead to steps not being completed as intended. Steps 7.2.1.C and 7.2.2.E for when the subcomponents are required to be cleaned rely on statements such as, IF the component is dirty, THEN clean the component. This is not consistent with the common failure mechanism of surface contamination, which would indicate that cleaning should be performed regularly to ensure sustained performance. Additionally, PE 6033 has a section specifying that for any results that are "not normal" to contact the strategic engineer or work supervisor, but since this inspection is for collecting data with no action levels, there is no objective criteria to be used by the performer in identifying any "not normal" conditions. Also, if identified, there is no guidance to enter that condition into the corrective action program.
Additionally, the lack of action levels results in a reliance on third-party software summaries which were found to give misleading information in some cases. This procedure relied upon knowledge of the individuals to properly interpret the results with potential error traps not identified.
The licensee performed a causal evaluation which determined that the primary cause was that the licensee's implementing procedure PE 6033 is not effectively implementing the requirements of program document H52.
Corrective Actions: The operating crew responded to the event and placed the plant in a safe condition. All three phases of lightning arresters for the Unit 2 generator transformer were replaced. Thermography readings were taken on all Unit 1 associated lightning arresters. Actions were created to revise the implementing procedures for H52, Large Oil Filled Transformers."
Corrective Action References: 501000073947
Performance Assessment:
Performance Deficiency: The inspectors determined that the failure to implement the requirements of procedure H52, Large Oil Filled Power Transformers was a performance deficiency as it was within the licensee's ability to foresee and correct. Specifically, the licensee's implementing procedure PE 6033 did not effectively meet the requirements of program document H52, resulting in an initiating event. The automatic start of the auxiliary feedwater system was expected based upon the plant transient, and the inspectors determined that there was no performance deficiency associated with the auto start.
Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Procedure Quality attribute of the Initiating Events cornerstone and adversely affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. The Performance deficiency resulted in an initiating event.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power.
Specifically, the inspectors determined that this finding is of very low safety significance (Green) because: the performance deficiency was not associated with a design or qualification issue; it did not represent a loss of system function; and was not part of an external event mitigating system.
Cross-Cutting Aspect: H.2 - Field Presence: Leaders are commonly seen in the work areas of the plant observing, coaching, and reinforcing standards and expectations. Deviations from standards and expectations are corrected promptly. Senior managers ensure supervisory and management oversight of work activities, including contractors and supplemental personnel.
Supervisors were not in the field setting and reinforcing standards and ensuring that deviations from those standards were promptly corrected.
Enforcement:
Inspectors did not identify a violation of regulatory requirements associated with this finding.
The disposition of this finding closes LER 2023-001-00, 2GT/XFMR Lockout Due to Failure of Lightning Arrester Caused Unit 2 Reactor Trip.
Failure to Adequately Evaluate Inability to Meet Acceptance Criteria for Safety-Related Bus Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000282/2023003-02 Open/Closed
[H.6] - Design Margins 71111.15 The inspectors identified a Green finding and associated non-cited violation (NCV) of 10 CFR Part 50, Appendix B, Criterion III, "Design Control," when the licensee failed to adequately assess the failure to meet acceptance criteria for maintenance on the safeguards bus.
Description:
In October of 2022, during Unit 1 refueling outage (RFO) 1R33, preventive maintenance (PM)was performed on safeguards bus 15 by the transmission & distribution (T&D) group. The PM was performed to assess the condition of the safeguards bus in compliance with NRC commitments from LER 1-01-15. Bus 15 is the safety-related bus which supplies power to the
'A' train of the emergency core cooling system (ECCS) loads. Bus 15 is also the bus that the
'A' train emergency diesel generator (EDG) supplies power through.
During maintenance, per procedure PE 0009, resistance readings were taken from the front of one cubicle to the front of the adjacent cubicle for each phase, checking contact resistance of the bus bar connections. On October 22, 2022, CAP 501000067574 was initiated to document Over-Limit High Cubicle-to-Cubicle Res, indicating that 19 of 42 resistance readings exceeded the acceptance criteria of 110 micro-ohms specified in PE 0009.
T&D continued work on the bus disassembling, cleaning, and reassembling the bus bars.
Following the corrective maintenance performed to improve the resistance readings, the licensee documented on October 27, 2022, some readings did not go down after cleaning and torquing and were approved by engineering group.
Inspectors questioned the efficacy of the work performed on safety-related equipment and the dispositioning of the failure to meet acceptance criteria, even following corrective maintenance. Inspectors reviewed the work package to determine which connections had been broken, how they were cleaned, and what they were torqued to upon reassembly. In reviewing the work documents the inspectors determined that they lacked quantitative and/or qualitative acceptance criteria for determining that the safety-related work activities had been satisfactorily completed.
Step 7.9.3 of the work package documented the following:
Replaced 3 stabs in 15-7 Bus side. Broke connections apart on high resistance cubicles according to decision tree. However, there were no details of which connections were broken, how they were cleaned, or when/how they were reassembled.
Step 7.11 Torque or check torqued all bolted connections in accordance with MSIP 3026, was signed off as complete but did not specify which connections were torqued or what they were torqued to. In addition, there were no torque values specified in MSIP 3026, rather it referred workers to an additional procedure and left it to the technician to determine the correct torque value from a series of tables.
Step 7.21 documented the following:
Used decision tree on High Resistance Cubicles some readings remained high Engineering approved final results.
Inspectors questioned why the resistance readings would remain high (or increase) following completion of actions which were specifically taken to lower the resistance values. Due to the lack of detail, inspectors were unable to determine specifically what work had been performed nor could they assess the quality of the work performed. Inspectors also questioned why the resistance readings would remain essentially stable for approximately 17 years and then experience a step change, in some cases to more than double their previous values. Of note, three cubicles remained at or near their previous values, indicating that the cubicles with higher-than-normal readings were not attributed to changes in methodology and/or test equipment.
In reviewing Engineering Change (EC) 608000000896 which was prepared to disposition the failure to meet the acceptance criteria, inspectors identified that not all cubicles which failed to meet acceptance criteria had been evaluated. Readings from three cubicles failed to meet the 110 micro-ohm acceptance criteria but had not been evaluated for acceptability. In addition, the evaluation focused on the ability of the room coolers to remove the additional heat generated from the higher resistance values. The evaluation did not consider or quantify potential bus failure from material softening or fire from excess heat generated due to localized hot spots caused by higher resistance values. Additionally, the EC only evaluated the amount of heat above baseline and not the total amount of heat generated. The EC did not evaluate the acceptability of as-left resistance readings relative to any design basis or design limitation requirements.
Following discussions with the inspectors, the licensee revised their initial EC to incorporate the additional cubicles for evaluation and added a qualitative assessment for the acceptance of the higher resistance values. Based upon the objective evidence provided, inspectors could not reach the same conclusion that the licensee had come to in determining that the higher resistance values were acceptable for continued operation. Inspectors opened an unresolved item (URI) associated with the bus 15 failure to meet acceptance criteria to understand and disposition the higher resistance readings.
On March 14, 2023, the licensee approved EC 608000000953 Bus 15 Contact Resistance Evaluation. This evaluation used the softening temperature for copper bus bars as the limiting maximum temperature and the anticipated current flow through the components to develop a limiting maximum allowable voltage drop across a given connection. The licensee then determined what the voltage drop across the actual connections would be based upon their as-left resistance readings and compared those to the calculated limit. The evaluation demonstrated that there was margin between the as-left values and the limiting value calculated in the EC.
Based upon the additional evaluation performed, the inspectors were able to conclude their inspection and close out the URI.
Corrective Actions: The licensee entered the failure to meet acceptance criteria into their corrective action program and performed corrective maintenance in an attempt to resolve the issue. When attempts to lower the contact resistances were unsuccessful, the licensee attempted to disposition the higher resistance values via an EC evaluation.
Corrective Action References:
501000054247, "PE 009 Acceptance Criteria Change-Update" 501000068630, "PE 0009 in Need of Update" 501000067574, "Over-Limit High Cubicle-to-Cubicle Res" 501000067578, "Hi Stab Resist: Bus 15 Cub 7 Hi Side" 501000067646, "Relay Testing Failure - Sol. Coil"
Performance Assessment:
Performance Deficiency: Contrary to the requirements of 10 CFR Part 50, Appendix B, Criterion III, the licensee's engineering evaluation for the failure to meet acceptance criteria did not include all cubicles which failed to meet acceptance criteria, nor did it evaluate against any type of design standard as it was qualitative in nature. The inspectors determined that this was within the licensees ability to foresee and correct, and was therefore a performance deficiency.
Screening: The inspectors determined the performance deficiency was more than minor because if left uncorrected, it would have the potential to lead to a more significant safety concern. Inspectors determined the issue to be more than minor based upon the degradation in the resistance readings and the licensee's failure to adequately assess the significance and acceptability of the failure to meet acceptance criteria. The performance deficiency, if left uncorrected, would have the potential to lead to a more significant safety concern.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. This issue screened to Green IAW IMC 0609, Appendix A, "Significance Determination Process for Findings at Power," as ultimately bus 15 remained operable.
Cross-Cutting Aspect: H.6 - Design Margins: The organization operates and maintains equipment within design margins. Margins are carefully guarded and changed only through a systematic and rigorous process. Special attention is placed on maintaining fission product barriers, defense-in-depth, and safety-related equipment.
Enforcement:
Violation: Title 10 CFR Part 50, Appendix B, Criterion III, "Design Control," requires in part that "Measures shall be established to assure that applicable regulatory requirements and the design basis, as defined in § 50.2 and as specified in the license application, for those structures, systems, and components to which this appendix applies are correctly translated into specifications, drawings, procedures, and instructions. These measures shall include provisions to assure that appropriate quality standards are specified and included in design documents and that deviations from such standards are controlled."
Contrary to the above, the licensee failed to ensure that applicable requirements were correctly translated into procedures and that deviations from quality standards were controlled. Specifically, on October 24, 2022, the licensee failed to adequately evaluate the failure to meet acceptance criteria for their safety-related bus 15.
Enforcement Action: This violation is being treated as a non-cited violation, consistent with Section 2.3.2 of the Enforcement Policy.
The disposition of this finding and associated violation closes URI 05000282/2022004-01.
Unresolved Item (Closed)
Bus 15 Failure to Meet Acceptance Criteria URI 05000282/2022004-01 71111.15
Description:
A violation of 10 CFR 50, Appendix B, Criterion III, "Design Control," was identified as discussed above.
Corrective Action References:
501000054247, "PE 009 Acceptance Criteria Change-Update" 501000068630, "PE 0009 In Need of Update" 501000067574, "Over-Limit High Cubicle-to-Cubicle Res" 501000067578, "Hi Stab Resist: Bus 15 Cub 7 Hi Side" 501000067646, "Relay Testing Failure - Sol. Coil" Observation: Aux Building Roof Standing Water/Leaks 71152A The inspectors selected corrective action program (CAP) documents related to auxiliary building roof leaks for annual follow-up due to the potential impact on safety-related and maintenance rule-related equipment. Inspectors selected this sample because a significant amount of water recently entered the auxiliary building after a large rainstorm. After reviewing the CAPs, pictures, and video, the inspectors did not identify any equipment which was negatively impacted by the water, and the licensee performed inspections on electrical equipment to verify no water had entered. The results of these inspections were documented in the CAPs. The corrective actions planned are the ongoing roof replacement and a commercial change to reroute piping from the upper roof to the drain system rather than onto the lower roof. The inspectors did not identify any findings or violations of more than minor significance during the review.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
- On October 26, 2023, the inspectors presented the integrated inspection results to Thomas Conboy, Site Vice President, and other members of the licensee staff.
- On August 18, 2023, the inspectors presented the radiation protection baseline inspection results to Timothy Borgen, Plant Manager, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Procedures
FP-WM-SR-01
Nuclear Department Fleet Procedure, Seasonal Readiness
Program, 602000009915
F5 Appendix A,
Fire Area 11
Fire Detection Zone 87, Fire Area 11
F5 Appendix A,
Fire Area 13
Fire Detection Zone 57, Fire Area 13, Elevation 735'
Fire Plans
F5 Appendix A,
Fire Area 17
Fire Detection Zone 88, Fire Area 17
501000075490
2GT XFMR Arrester Forensic Results
07/26/2023
613000001376
Preventive Maintenance Change Request, SP 1449 Frequency
Change to 6Y
05/09/2019
FP-MA-REW-01
Nuclear Department Fleet Procedure, Rework Program,
2000012949
Corrective Action
Documents
QF0433,
501000073947
Root Cause Evaluation Report, 2GT Lockout/2GT & 2M
Locked Out, CAP ID: 501000073947
2C20.5 AOP3
Abnormal Operating Procedures, Reenergizing 4.16kV
Non-Safeguard Buses Unit 2
FP-PA-HU-05
Nuclear Department Fleet Procedure, Decision Making
H Procedure H28
Control Room Habitability Program
H Procedure H52
Large Oil Filled Power Transformers
PE 6034
20/4.16/4.16kV 2M Transformer Maintenance
Procedures
SP 1449
Tracer Gas Test of Control Room
Work Orders
2M Transformer Refueling Inspection
11/17/2019
Miscellaneous
QF1146, Past
Operability
Review (POR)
CAP 501000075275, Past Operability Review (POR)
07/15/2023
Instrumentation
3.3.2
Definitions 1.1, Shutdown Margin (SDM)
26
Procedures
Instrumentation B
3.3.2
Applicable Safety Analyses, LCO, and Applicability
2
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
SP 2301
Turbine Driven Auxiliary Feedwater Pump Auto Start and
Functional Refueling Outage Test
Miscellaneous
2R33 PRA
Outage Plan
2R33 Prairie Island Refueling Outage October 2023 Shutdown
Safety Plan
08/31/2023
SP 1106A
Diesel Cooling Water Pump Monthly Test
105
SP 1130A
Train A Containment Vacuum Breakers Quarterly Tests
SP 2088A
Train A Safety Injection Quarterly Test
SP 2101
Motor-Driven Auxiliary Feedwater Pump Quarterly Flow and
Valve Test
SP 2130A
Train A Containment Vacuum Breakers Quarterly Tests
Procedures
TP 2296B
D6 Radiator Fans Weekly Run Test & 2ZG System Weekly
Damper Cycling
D6 RM OA MD RPLC POSNR MD-32426
04/22/2022
SP 2101-21 MD AFWP Quarterly Flow Test
07/06/2023
SP 1130A TRN A CTMT VACUUM BKR QTR
08/26/2023
SP 2088A TRN A Safety Injection QTR Test
09/04/2023
SP 2130A TRN A CTMT VACUUM BKR QTR
08/16/2023
Calibrated Tool Usage
07/18/2023
Work Orders
501000075275 Pressure Switch Failed
07/19/2023
501000057032
RAM Shipment w/Higher RAM Levels Found
10/10/2021
501000064647
10CFR37 Mat Accountability Documentation
07/13/2022
501000065700
2R-11 Source Leaking
08/18/2022
501000066460
RAM Sources in Shipment of Equipment
09/16/2022
501000070552
Solid Effluent Stream Uncommon Nuclide
2/08/2023
Corrective Action
Documents
501000073690
Late Receipt of Rad Material
05/17/2023
501000076038
D59 Enhancement
08/16/2023
501000076053
FP-RP-RW-09 Waste Streams
08/16/2023
501000076054
Annual Source Inventory Requirements
08/16/2023
Corrective Action
Documents
Resulting from
Inspection
501000076081
Use of QF1279
08/16/2023
22 Dry Active Waste Part 61 Evaluation
04/03/2023
Engineering
Evaluations
PI22 HLR TB
22 Primary Resin Part 61 Evaluation
10/11/2022
Procedures
FP-RP-RW-001
Additional Security Measures for Transportation of Radioactive
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Material Part 37 Category 1 Quantities
FP-RP-RW-02
Radioactive Shipping Procedure
FP-RP-RW-03
10CFR37 Material Accountability
FP-RP-RW-04
Creating Radioactive Material Packages for Transportation
Offsite
FP-RP-RW-05
Type B Radioactive Shipments
FP-RP-RW-09
Rad Waste Streams and Scaling Factors
RPIP 1301
LSA Box / SEALAND Container Control
2000016617
Assess the Radioactive Shipping Program Utilizing the NRC
Inspection Manual
04/06/2023
Self-Assessments
2000016617
Snapshot Assessment Intended to Serve as a Three-Month
Inspection Focused on the Receipt, Storage, and Shipment of
Radioactive Materials
03/16/2023
21-053
Radioactive Shipment of the Unit 2 Reactor Coupon in a Type
A Package
2/01/2021
2-015
Radioactive Shipment of Bead Resin in a General Design
Package
07/12/2022
2-016
Radioactive Shipment of Cartridge Filters in a General Design
Package
07/19/2022
Shipping Records
23-017A
Radioactive Shipment of Bead Resin in a General Design
Package
06/13/2023
Work Orders
700098016
Ann Radioactive Srce Inventory/Leak Ck
10/26/2022
Operating
Procedure 2C28.2
Unit 2 Feedwater System
71151
Procedures
Operating
Procedure 2C28.3
Unit 2 Condensate System
Corrective Action
Documents
501000075853
Positive Tritium Sample, Lock and Dam #3
08/08/2023
Procedures
Periodic Structures Inspection
Work Orders
PM 3586-10 Periodic Structures Insp
2/13/2021
Miscellaneous
LER 50-306/2023-
001-00
2GT/XFMR Lockout Due to Failure of Lightning Arrester
Caused Unit 2 Reactor Trip
05/27/2023