IR 05000282/2025003
| ML25353A083 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 12/19/2025 |
| From: | Dariusz Szwarc NRC/RGN-III/DORS/RPB3 |
| To: | Paulhardt W Northern States Power Company, Minnesota |
| References | |
| IR 2025003 | |
| Download: ML25353A083 (0) | |
Text
SUBJECT:
PRAIRIE ISLAND NUCLEAR GENERATING PLANT - INTEGRATED INSPECTION REPORT 05000282/2025003 AND 05000306/2025003
Dear Werner K. Paulhardt,
Jr.:
On September 30, 2025, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Prairie Island Nuclear Generating Plant. On December 4, 2025, 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.
Due to the temporary cessation of government operations, which commenced on October 01, 2025, the NRC began operating under its Office of Management and Budget-approved plan for operations during a lapse in appropriations. Consistent with that plan, the NRC operated at reduced staffing levels throughout the duration of the shutdown. However, the NRC continued to perform critical health and safety functions and make progress on other high-priority activities associated with the ADVANCE Act and Executive Order 14300.
On November 13, 2025, following the passage of a continuing resolution, the NRC resumed normal operations. However, due to the 43-day lapse in normal operations, the Office of Nuclear Reactor Regulation granted the Regional Offices an extension on the issuance of the calendar year 2025, 3rd quarter integrated inspection reports normally issued by November 15, 2025, to December 31, 2025. The NRC will resume the routine cycle of issuing inspection reports on a quarterly basis beginning with the calendar year 2025, 4th quarter integrated inspection reports, which will be issued 45 days after the 4th quarter ends on December 31, 2025.
One finding of very low safety significance (Green) is documented in this report.
This finding 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.
December 19, 2025 If you disagree with a cross-cutting aspect assignment 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.
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, Dariusz Szwarc, 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 cc w/ encl: Distribution via LISTSERV Signed by Szwarc, Dariusz on 12/19/25
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 Perform Required Augmented Inspections and Flaw Evaluation per ASME Code Case N-513-5 Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000306/2025003-01 Open/Closed
[H.14] -
Conservative Bias 71111.12 The inspectors identified a Green finding and associated non-cited violation (NCV) of 10 CFR 50.55a(a)(3)(ii), which incorporates by reference American Society of Mechanical Engineers (ASME) Code Case N-513-5, for the licensees failure to complete required augmented inspections. Specifically, the licensee failed to perform required expanded scope augmented inspections required by Code Case N-513-5 upon identification of flaws during initial evaluation for a through-wall leak in the cooling water (CL) supply line to the 22 turbine-driven auxiliary feedwater pump (TDAFWP). The licensee also failed to update the evaluation once the additional flaws were identified.
Additional Tracking Items
None.
PLANT STATUS
Unit 1 began the inspection period at rated thermal power. On July 16, 2025, Unit 1 experienced an unplanned reactor trip during maintenance. Unit 1 started up on July 22, 2025, and returned to full power operation on August 1, 2025. Unit 1 remained at or near full-rated thermal power with the exception of brief power reductions for testing, maintenance, or flexible power operations.
Unit 2 started the inspection period at rated thermal power and remained there for the duration of the 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 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
71111.04 - Equipment Alignment
Partial Walkdown Sample (IP Section 03.01) (1 Sample)
The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:
- (1) Unit 2 charging system after 22 CCP work window on July 16, 2025
71111.05 - Fire Protection
Fire Area Walkdown and Inspection Sample (IP Section 03.01) (4 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 Detection Zone (FDZ) 46, elevation 715', auxiliary building Unit 2 in aftermath of motor control center 2J2 smoke on July 14, 2025
- (2) FDZ 82, D1 diesel room on July 28, 2025
- (3) FZ 2, auxiliary feed pump rooms, elevation 695', with scaffolding installed for MV-32247 work on August 20, 2025
- (4) FDZ 12, Unit 1 and Unit 2 cable spreading room on September 3, 2025
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 Unit 1 reactor startup following trip and relay replacement on July 22, 2025.
Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)
- (1) The inspectors observed and evaluated simulator scenario for licensed operator requalification on August 4, 2025.
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)auxiliary feedwater N-513-5 tee leak evaluation of turbine-driven auxiliary feedwater pump cooling water suction pipe on July 7, 2025 (2)install TMOD power supply in 21BD Unit 2 rod control on August 5, 2025
71111.13 - Maintenance Risk Assessments and Emergent Work Control
Risk Assessment and Management Sample (IP Section 03.01) (1 Sample)
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) D5 protected equipment during D6 work window on August 18, 2025
71111.15 - Operability Determinations and Functionality Assessments
Operability Determination or Functionality Assessment (IP Section 03.01) (4 Samples)
The inspectors evaluated the licensees justifications and actions associated with the following operability determinations and functionality assessments:
(1)755' auxiliary building high energy line break prompt operability determination for motor control center 1MA2 high temps on July 2, 2025 (2)operability of void in 1RH-21 pipe and potential gas intrusion from reactor coolant system in Mode 1 (QIM 501000099808) on June 11, 2025 (3)121 control room chiller past operability evaluation on August 15, 2025 (4)122 control room chiller pipe leak on September 9, 2025
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) (3 Samples)
(1)22 containment spray pump after failed light indication and human performance error on August 27, 2025
- (2) D5 fast start on September 15, 2025
- (3) D6 PMT after voltage regulation circuitry failure on September 26, 2025
71114.02 - Alert and Notification System Testing
Inspection Review (IP Section 02.01-02.04) (1 Sample)
- (1) The inspectors evaluated the following maintenance and testing of the alert and notification system:
- annual siren inspection and maintenance records for the period from April 1, 2024, through December 31, 2024
- monthly alert notification system (siren) tests for the period from April 1, 2024, through December 31, 2024
71114.03 - Emergency Response Organization Staffing and Augmentation System
Inspection Review (IP Section 02.01-02.02) (1 Sample)
- (1) The inspectors evaluated the readiness of the emergency preparedness organization.
71114.05 - Maintenance of Emergency Preparedness
Inspection Review (IP Section 02.01 - 02.11) (1 Sample)
- (1) The inspectors evaluated the maintenance of the emergency preparedness program.
71114.06 - Drill Evaluation
Additional Drill and/or Training Evolution (2 Samples)
The inspectors evaluated:
(1)emergency preparedness drill tabletop exercise on August 19, 2025
- (2) emergency preparedness drill tabletop exercise on August 26, 2025
OTHER ACTIVITIES - BASELINE
71151 - Performance Indicator Verification The inspectors verified licensee performance indicators submittals listed below:
IE01: Unplanned Scrams per 7000 Critical Hours Sample (IP Section 02.01) (2 Samples)
- (1) Unit 1 (July 1, 2024, through June 30, 2025)
- (2) Unit 2 (July 1, 2024, through June 30, 2025)
IE03: Unplanned Power Changes per 7000 Critical Hours Sample (IP Section 02.02) (2 Samples)
- (1) Unit 1 (July 1, 2024, through June 30, 2025)
- (2) Unit 2 (July 1, 2024, through June 30, 2025)
IE04: Unplanned Scrams with Complications (USwC) Sample (IP Section 02.03) (2 Samples)
- (1) Unit 1 (July 1, 2024, through June 30, 2025)
- (2) Unit 2 (July 1, 2024, through June 30, 2025)
MS05: Safety System Functional Failures (SSFFs) Sample (IP Section 02.04) (2 Samples)
- (1) Unit 1 (July 1, 2024, through June 30, 2025)
- (2) Unit 2 (July 1, 2024, through June 30, 2025)
MS06: Emergency AC Power Systems (IP Section 02.05) (2 Samples)
- (1) Unit 1 (July 1, 2024, through June 30, 2025)
- (2) Unit 2 (July 1, 2024, through June 30, 2025)
MS07: High Pressure Injection Systems (IP Section 02.06) (2 Samples)
- (1) Unit 1 (July 1, 2024, through June 30, 2025)
- (2) Unit 2 (July 1, 2024, through June 30, 2025)
MS08: Heat Removal Systems (IP Section 02.07) (2 Samples)
- (1) Unit 1 (July 1, 2024, through June 30, 2025)
- (2) Unit 2 (July 1, 2024, through June 30, 2025)
MS09: Residual Heat Removal Systems (IP Section 02.08) (2 Samples)
- (1) Unit 1 (July 1, 2024, through June 30, 2025)
- (2) Unit 2 (July 1, 2024, through June 30, 2025)
MS10: Cooling Water Support Systems (IP Section 02.09) (2 Samples)
- (1) Unit 1 (July 1, 2024, through June 30, 2025)
- (2) Unit 2 (July 1, 2024, through June 30, 2025)
BI02: RCS Leak Rate Sample (IP Section 02.11) (2 Samples)
- (1) Unit 1 (July 1, 2024, through June 30, 2025)
- (2) Unit 2 (July 1, 2024, through June 30, 2025)
EP01: Drill/Exercise Performance (DEP) Sample (IP Section 02.12) (1 Sample)
- (1) April 1, 2024, through June 30, 2025 EP02: Emergency Response Organization (ERO) Drill Participation (IP Section 02.13) (1 Sample)
- (1) April 1, 2024, through June 30, 2025 EP04: Emergency Response Facility and Equipment Readiness (ERFER) (IP Section 02.14) (1 Sample)
- (1) January 1, 2025, through June 30, 2025 71152A - Annual Follow-up Problem Identification and Resolution
Annual Follow-up of Selected Issues (Section 03.03) (1 Sample)
The inspectors reviewed the licensees implementation of its corrective action program related to the following issues:
(1)reactor trip breaker undervoltage relay failed testing on July 16, 2025
71152S - Semiannual Trend Problem Identification and Resolution Semiannual Trend Review (Section 03.02) (1 Sample)
- (1) The inspectors reviewed the licensees corrective action program (CAP) to identify potential trends in operability determinations that might be indicative of a more significant safety issue, on September 10, 2025.
INSPECTION RESULTS
Failure to Perform Required Augmented Inspections and Flaw Evaluation per ASME Code Case N-513-5 Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green NCV 05000306/2025003-01 Open/Closed
[H.14] -
Conservative Bias 71111.12 The inspectors identified a Green finding and associated non-cited violation (NCV) of 10 CFR 50.55a(a)(3)(ii), which incorporates by reference American Society of Mechanical Engineers (ASME) Code Case N-513-5, for the licensees failure to complete required augmented inspections. Specifically, the licensee failed to perform required expanded scope augmented inspections required by Code Case N-513-5 upon identification of flaws during initial evaluation for a through-wall leak in the cooling water (CL) supply line to the 22 turbine-driven auxiliary feedwater pump (TDAFWP). The licensee also failed to update the evaluation once the additional flaws were identified.
Description:
Title 10 CFR 50.55a(a)(3) states, in part [The use of code cases listed in the NRC regulatory guides]...[is acceptable with the specified conditions in those guides when implementing the editions and addenda of the ASME Boiler Pressure Vessel (BPV) Code and ASME OM Code]. 10 CFR 50.55a(a)(3)(ii) lists NRC Regulatory Guide (RG) 1.147, Revision 21.
The NRC has conditionally approved ASME BPVC Case N-513-5 for use with the following conditions per NRC RG 1.147, Revision 21:
Condition #1 For the purposes of Section 5 of Code Case N-513-5, a flaw is a non-through-wall planar flaw or non-through-wall nonplanar flaw with a wall thickness less than 87.5 percent of the nominal wall thickness of the pipe or the design minimum wall thickness.
Condition #2 For the purposes of Section 5 of Code Case N-513-5, the term significant flaw means any flaw found during augmented examinations performed per Section 5 of N-513-5 that has a depth greater than 75 percent of the pipe wall thickness or that does not satisfy the applicable requirements of the flaw evaluation per Section 3 of N-513-5. If a significant flaw as defined
[in Condition 1] is present, the licensee must perform the additional augmented examination specified in Section 5.
ASME Code Case N-513-5 Section 5(b) and (c), states, When a flaw is detected [during augmented inspections per Code Case N-513-5], an additional sample of the [at least five of the most susceptible and accessible locations, or, if fewer than five, all susceptible and accessible locations] shall be examined, and This process shall be repeated within 15 days for each successive sample, until no significant flaw is detected or until 100 percent of susceptible and accessible locations have been examined.
On December 18, 2024, a pinhole leak was observed on the weld upstream of MV-32030 TDAFWP suction cooling water supply valve. The licensee used ASME Code Case N-513-5 to perform an evaluation for temporary acceptance of flaws in moderate energy Class 2 or 3 piping and gate valves, without performing a repair/replacement activity for a limited time, not exceeding the time to the next scheduled refueling outage. The site measured piping wall thickness to evaluate structural integrity of the pipe, performed daily monitoring for leak rate at the pinhole leak, and performed augmented inspections in accordance with Code Case N-513-5. The augmented inspections revealed that 58/84 areas inspected met the NRC RG 1.1.47 conditional use criteria of Condition #1 definition of a flaw as defined above. However, the licensee failed to perform the required additional inspections required by the code case.
The licensee also failed to perform Code Case N-513-5 Section 2(c), which states, When multiple flaws, including irregular (compound) shape flaws, are detected, the interaction and combined area loss of flaws in a given pipe section shall be accounted for in the flaw evaluation, because the additional flaws identified during augmented inspections were not incorporated into the licensees initial flaw evaluation.
Corrective Actions: The licensee submitted alternative requests 1-RR-5-16, Proposed Alternative to Conditions for Applying Code Case N-513-5, and 2-RR-5-16, Evaluation Criteria for Temporary Acceptance of Flaws in Moderate Energy Class 2 or 3 Piping and Gate ValvesSection XI, Division 1. Those relief requests were granted on September 18, 2025.
The pinhole leak and additional cooling water piping was repaired/replaced as part of the sites 2R34 refueling outage (October 10 to November 16, 2025).
Corrective Action References:
501000093425, TDAFWP CL Suct Pipe Leak 501000093698, MIC Insp: Acceptable Thinning Detected 501000056188, MIC: Acceptable Thinning Detected
Performance Assessment:
Performance Deficiency: Inspectors determined that the licensees failure to perform the required additional augmented inspections and flaw evaluation per ASME Code Case N-513-5 was within the licensees ability to foresee and correct and was a performance deficiency.
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, additional flaws were identified in the performed augmented inspection, necessitating additional expansion of the sample, and this expansion of the sample did not occur, nor did the subsequent evaluation which is required once additional flaws are identified.
Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power.
Inspectors determined that the answer to both
- (2) screening questions of Exhibit 1-Initating Events Screening Questions, Section C, Support System Initiators, were answered No, resulting in the issue screening to Green.
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, the licensee performed less-conservative inspections and flaw evaluations than those required by ASME BPV Code Case N-513-5 to ensure the continued safety and reliability of cooling water system piping until the next outage.
Enforcement:
Violation: 10 CFR 50.55a(a)(3)(ii), which incorporates by reference Code Case N-513-5, requires in Section 5(b) and (c), that When a flaw is detected [during augmented inspections per Code Case N-513-5], an additional sample of the [at least five of the most susceptible and accessible locations, or, if fewer than five, all susceptible and accessible locations] shall be examined, and This process shall be repeated within 15 days for each successive sample, until no significant flaw is detected or until 100 percent of susceptible and accessible locations have been examined.
10 CFR 50.55a(a)(3)(ii), which incorporates by reference Code Case N-513-5, requires in Section 2(c) that when multiple flaws, including irregular (compound) shape flaws, are detected, the interaction and combined area loss of flaws in a given pipe section shall be accounted for in the flaw evaluation.
Contrary to the above, from December 18, 2024 to September 18, 2025, the licensee failed to perform an additional sample of the [at least five of the most susceptible and accessible locations, or, if fewer than five, all susceptible and accessible locations] and repeat that process within 15 days for each successive sample, until no significant flaw is detected or until 100 percent of susceptible and accessible locations had been examined as required by Code Case N-513-5 Sections 5(b) and (c). Additionally, the licensee failed to perform a flaw evaluation when multiple flaws, including irregular (compound) shape flaws, are detected, in a given pipe section as required by Code Case N-513-5 Section 2(c).
Enforcement Action: This violation is being treated as a non-cited violation, consistent with Section 2.3.2 of the Enforcement Policy.
Observation: Follow-Up of CAP 501000090701 Undervoltage Relay Failed Testing 71152A Inspectors selected CAP 501000090701 for follow-up based upon the risk significance of reactor trip breaker undervoltage relays not working as intended. On October 4, 2024, during performance of PE 4810, Westinghouse DB-50 Reactor Trip & Bypass Breaker Maintenance & Calibration Step 7.19 on BKR 1-52/BYB, the Prairie Island maintenance crew identified that the timing test of the undervoltage trip attachment (UVTA) relay exceeded its test parameter three times. The licensee entered the issue into the CAP and performed a maintenance rule evaluation (MRE), placed a mode hold (MDH) on correcting the issue until a new relay was installed and tested per SP 1250, Test of the Reactor Trip Breakers, and performed a past operability determination (POD) as corrective actions in response to the UVTA relay failing its timing test. Inspectors reviewed the corrective action database and noted that corrective actions appeared to be appropriate, consistent with site processes, and effective. No more-than-minor findings or violations were identified during this inspection.
Observation: Semi-Annual Trend Assessment of Operability Determinations 71152S Inspectors performed a semi-annual trend review of Operability determinations due to a cognitive trend from ongoing issues and CAP reviews. Inspectors selected this sample due to risk associated with the process. The licensees operability processes directly implement Technical Specification (TS) requirements. Incorrect operability determinations could potentially impact limiting condition for operation (LCO) ACTION statement entry resulting in a significant increase in risk.
CAP 501000088615, POR [Past Operability Review] 87599 Question of Past Op, is an NRC-identified CAP classified as non-condition adverse to quality (CAQ) initiated on August 6, 2024, documenting in part that While it is clear that there was no loss of safety function during the period of 1R37 inoperability, the NRC Resident Inspector questioned how the POR could come up with the conclusion of operable. Additionally, there were short periods of time where more than one Rad Monitor was OOS [out of service] at the same time during fuel handling. Since other Rad monitors were in service, there was no loss of safety function during these times. However, they need to be evaluated for a missed 3.0.3 entry. Actions taken were to reopen and revise the original POR, which determined there was a missed 3.0.3 entry, and the condition was reportable to the NRC. (A Green NCV was issued for this violation.)
CAP 501000088767, POR [Past Operability Review] 501000087599 Conclusion in Question, is an NRC-identified CAP classified as CAQ initiated on August 13, 2024 documenting that, After a review of the condition and conclusions of POR by ENG, OPS and Reg Affairs, it was determined that the conclusion of the POR was not correct. Actions taken were to revise the POR, which did come to a different conclusion [InOp], and to perform a human performance investigation which resulted in lessons learned. There is no indication of what was done with the lessons learned.
CAP 501000095420, Trend for Past Operability Reviews, is a site-identified CAP classified as non-CAQ initiated by Operations personnel on February 20, 2025, to in part document a potential trend for performance of PORs, which was assigned to Engineering; was closed to trend with no actions taken.
CAP 501000099808, GAMP 1RH-21 Void Identified in MODE 1, is a site-identified CAP classified as CAQ initiated on June 11, 2025. This CAP called into question the operability of reactor coolant system (RCS) pressure isolation valve (PIV) SI-9-5 per TS 3.4.15, Condition A (72-hour shutdown LCO). Engineering completed a POD on June 12, 2025, with a recommendation to Operations of Operable, which Operations accepted. Inspectors questioned the basis for the assumptions and the methodology utilized in the evaluation.
Licensee procedure FP-OP-OL-01, Revision 24, Operability, requires Operability determinations should be documented in sufficient detail to allow an individual knowledgeable in the technical discipline associated with the condition to understand the basis for the determination. In addition, FG-OP-OL-02, Revision 3, Past Operability Reviews (POR) and Prompt Operability Determinations (POD), specifies Provide references to material that is used to support the assumptions. Despite these statements, no references were provided, and the inspectors, although knowledgeable, could not reach the conclusion of Operable.
On July 30, 2025, the licensee provided an official response to NRC question What is the basis for the assumptions in the original SI-9-5 Void POD? CAP 501000099808. The response, in part, indicated The volume of 1RH-21 was inappropriately used to compute a theoretical maximum void volume. This information provided confusion and was invalid. CAP 501000100119 was submitted to revise the POD and acquire additional information to support a more detailed analysis. The response indicated invalid assumptions/methodology were used in the original POD, however, no CAP was written to address that condition. Inspectors determined this was a minor finding associated with licensees failure to follow their procedures listed above. The finding was minor due to the revised POD supporting the determination of Operable. However, it is worth noting that from June 11, 2025, until at least June 26, 2025 (Revision 1 of POD), there was not a valid technical basis for the reasonable assurance of operability concluded in the original POD, and the TS determination of Operable. Revision 2 of the POD was completed on August 7, 2025, and provided a basis for the reasonable assurance of Operability.
Based on the examples provided, as well as additional examples, Inspectors identified a potential adverse trend in quality of Operability determinations performed. Although the Operability determinations themselves were revised, no actions have been taken or are in place in the corrective action program to correct the human performance or programmatic weaknesses allowing those errors to occur. Findings/violations identified were as noted above.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified that no proprietary information was retained or documented in this report.
- On December 4, 2025, the inspectors presented the integrated inspection results to Werner K. Paulhardt, Jr., Site Vice President, and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Engineering
Evaluations
2000030609
Chemical and Volume Control System Charging Letdown
and Seal Water - Unit 2; Number: C12-5
Fire Plans
FDZ 2
Fire Areas 31 and 32; Aux Feedwater Pump Rooms,
El. 695'
Fire Plans
FDZ 46
Fire Area 74; Auxiliary Building Unit 2, El. 715'
Fire Plans
Fire Detection
Zone 12
Fire Area 18; Relay & Cable Spreading Room,
Elevation 715'
Procedures
1C1.2-M1
Unit 1 Startup to Mode 1
Procedures
1C1.2-M2
Unit 1 Startup to Mode 2
Engineering
Evaluations
608000001259
Owner Acceptance of Code Case 513-5 Eval
01/18/2025
Engineering
Evaluations
QF0739;
2000017241
Provide Aging Management Information Regarding the
D6 HT Coolant Piping That Developed a Through-Wall Leak
Due to Vibration-Induced Cracking as Determined in CSE
501000095507.
07/24/2025
Miscellaneous
FP-PE-NDE-425
UT Examination; Work Scope 2R34 MIC; Summary
No. 2-MIC-2147; Report No. 2R34-MIC-001; Area: Aux FW
Pump Room; Drawing No. NO-160394
Miscellaneous
FP-PE-NDE-425
UT Examination; Work Scope 2R34 MIC; Summary
No. 2-MIC-2151; Report No. 2R34-MIC-003; Area:
Aux FW Pump Room
Miscellaneous
LR-AMR-314
AMR Diesel Generators and Support System
Miscellaneous
Technical Report
- EPRI
Non-Class1 Mechanical Implementation Guideline and
Mechanical Tools, Revision 4
January
2006
Miscellaneous
UT Examination
Procedure FP-PE-NDE-425; Work Scope 2R34 MIC;
Summary No. 2-MIC-2147; WO MN 10314737; Area: Aux
FW Pump Room
Engineering
Evaluations
FP-OP-PEQ-01
2000030720, Protected Equipment Program
Calibration
Records
2-9210433-004
S-RELAP5 Gas Void Transport Benchmarks
004
Corrective Action
501000071816
No Purge Time on 121 CR Chiller
03/30/2023
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Documents
Corrective Action
Documents
501000072275
Run Time Data Outside TP 1687 Standard
04/14/2023
Corrective Action
Documents
501000076103
21 CR Chiller Purge Run Time Meter
08/17/2023
Corrective Action
Documents
501000084009
Inability to Detect Level in PRG COMPRES
04/12/2024
Corrective Action
Documents
501000094171
Purge Timer did not Advance
01/17/2025
Corrective Action
Documents
501000095507
Through Wall Coolant Leak
2/24/2025
Corrective Action
Documents
501000096290
D6 Coolant Leak POD did not Address Loop
03/17/2025
Corrective Action
Documents
501000100268
21 CR CHL PRG CMPR not Running in Auto
06/22/2025
Corrective Action
Documents
501000101377
MV-32209 High Running Loads
07/29/2025
Corrective Action
Documents
Review
500000336593/501000100268; 121 Control Room Chiller
Tripped on High Refrigerant Pressure
06/21/2025
Corrective Action
Documents
QF0428
2000021355
Engineering
Evaluations
2000017425
CAP 501000102758, POD 50000033809, Water Slowly
Accumulating on Outside of Insulated ZH Line Above the
Main Control Room and Dripping Down
Engineering
Evaluations
2000017425
Prompt Operability Determination; CAP 501000100300;
POD 501000100300
Engineering
Evaluations
608000001293;
Auxiliary Building
High Temperature
HELB Evaluation
(130F/150F)
Auxiliary Building High Temperature HELB Evaluation
(130F/150F)
06/25/2025
Engineering
Evaluations
QF0739, NRC
Question
Response Form
Request Number 425; Approval 602000017241; 121 Control
Room Chiller Purge Compressor
07/29/2025
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Miscellaneous
2-9222180-000
PINGP GL 2008-01 - RHR Unit 1 Waterhammer Analysis
000
Miscellaneous
13
21 Control Room Chiller Run Time of 30 Days,
04/22/2025 - 06/21/2025
08/15/2025
Miscellaneous
Document DLTC
1605
Diesel Engines Instruction Manual, 2 Operation
August 1990
Miscellaneous
FG-OP-OL-02
Prompt Operability Determinations (POD) and Past
Operability Reviews (POR)
Miscellaneous
FP-PA-HU-01
Human Performance Program, Culpability Evaluation Tool
Miscellaneous
LCO Records,
14
2 Control Room Chiller LCO; 04/23/2025, 05/03/2025,
05/20/2025, 05/22/2025
May 2025
Miscellaneous
LCO Records,
15
2 Control Room Chiller LCO, June 11, 2025
June 2025
Miscellaneous
LCO Records,
16
2 Control Room Chiller LCO, June 11, 2025
June 2025
Miscellaneous
LCO Records,
17
2 Control Room Chiller LCO June 11 and June 21, 2025
June 2025
Miscellaneous
NSPM-1 QATR
Quality Assurance Topical Report
Miscellaneous
QF1146
500000336593/501000100268, 121 Control Room Chiller
Trip
06/21/2025
Miscellaneous
SOMS Logs
SOMS Narrative Log Search, Entry Contains: 1687
01/01/2025 -
06/21/2025
Miscellaneous
SOMS Logs
SOMS Narrative Logs, Entry Contains: 075-011
2/01/2024 -
06/21/2025
Miscellaneous
SOMS Logs
SOMS Narrative Log Search, Entry Contains: ZH
01/01/2023 -
04/01/2023
Miscellaneous
SOMS Logs
SOMS Narrative Log Search, Entry Contains:1687
01/01/2023 -
04/01/2023
Miscellaneous
SOMS Logs
SOMS Narrative Log Search, Entry Contains: 1253
01/01/2023 -
04/01/2023
Miscellaneous
SOMS Logs
SOMS Narrative Log Search, Entry Contains: 075-011
01/01/2023 -
04/01/2023
Miscellaneous
SOMS Logs
SOMS Narrative Log Search, Entry Contains: 3.7.11
01/01/2023 -
04/01/2023
Procedures
FG-G-DEF-01
Definition, Abbreviations and Acronyms
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Procedures
USAR Section -
App L
Prairie Island Updated Safety Analysis Report
Work Orders
700157036
QIM_501000100268_121 CR CHL PRG CMPR
06/22/2025
Work Orders
Work Order Log
Various Work Orders
Various
Dates
Miscellaneous
Shutdown Safety
Plan
2R34 Prairie Island Refueling Outage October 2025
Shutdown Safety Plan
October
25
Engineering
Evaluations
2000027163
D5 Diesel Generator 6 Month Fast Start Test
08/20/2025
Miscellaneous
QF0937
MV-32116, WO 700148375-0010, 22 Containment Spray
Pump Quarterly Test
Procedures
SP 2295
D5 Diesel Generator 6 Month Fast Start Test
Procedures
SP 2307
D6 Diesel Generator 6 Month Fast Start Test
Work Orders
700147456
09/15/2025
Work Orders
D6 Auto Voltage Reg Motor Operated Pot
09/25/2025
71151
Miscellaneous
MSPI Derivation
Report
MSPI Cooling Water System, Performance Limit Exceeded
June 2025
71151
Miscellaneous
MSPI Derivation
Report
MSPI Cooling Water System, Unit 1; MSPI Emergency AC
Power System, Unit 1; MSPI High Pressure Injection
System, Unit 1; MSPI Heat Removal System, Unit 1; MSPI
Residual Heat Removal System, Unit 1; MSPI Cooling Water
System, Unit 2; MSPI Emergency AC Power System, Unit 2;
MSPI High Pressure Injection System, Unit 2; MSPI Heat
Removal System, Unit 2; MSPI Residual Heat Removal
System, Unit 2
June 2025
71151
Miscellaneous
MSPI Deviation
Report
Prairie Island Units 1 and 2; MSPI Cooling Water System
June 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Safety Injection MSPI Monthly Data; Units 1
and 2 Residual Heat Removal MSPI Monthly Data; and LCO
Notes
May 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Units 1 and 2 Aux Feedwater MSPI Monthly Data
May 2025
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Forms
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Aux Feedwater MSPI Monthly Data
June 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Aux Feedwater MSPI Monthly Data
April 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Component Cooling MSPI Monthly Data
April 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Component Cooling MSPI Monthly Data
May 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Component Cooling MSPI Monthly Data
June 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Cooling Water MSPI Monthly Data
April 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Cooling Water MSPI Monthly Data
May 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Cooling Water MSPI Monthly Data
June 2025
71151
Miscellaneous
NRC and MOR
Units 1 and 2 Aux Feedwater MSPI Monthly Data
May 2025
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Data Collection
and Submittal
Forms
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Aux Feedwater MSPI Monthly Data
June 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Aux Feedwater MSPI Monthly Data
April 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Component Cooling MSPI Monthly Data
April 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Component Cooling MSPI Monthly Data, LCO
Logs
May 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Component Cooling MSPI Monthly Data, LCO
Logs
June 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Cooling Water MSPI Monthly Data, LCO Notes
April 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Cooling Water MSPI Monthly Data, LCO Notes
May 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Units 1 and 2 Cooling Water MSPI Monthly Data, LCO Notes
June 2025
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Forms
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Safety Injection MSPI Monthly Data; Units 1
and 2 Residual Heat Removal MSPI Monthly Data; LCO
Notes
June 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Safety Injection MSPI Monthly Data; Units 1
and 2 Residual Heat Removal MSPI Monthly Data; LCO
Notes
June 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 1 Emergency AC MSPI Monthly Data; SOMS Narrative
Logs
April 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 1 Emergency AC MSPI Monthly Data; SOMS Narrative
Logs
June 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 1 Emergency AC MSPI Monthly Data, SOMS Narrative
Logs
May 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 2 Emergency AC MSPI Monthly Data, SOMS Narrative
Logs
April 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 2 Emergency AC MSPI Monthly Data; SOMS Narrative
Logs
June 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 2 Emergency AC MSPI Monthly Data; SOMS Narrative
Logs
May 2025
71151
Miscellaneous
NRC and MOR
Units 1 and 2 Aux Feedwater MSPI Monthly Data
January
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Data Collection
and Submittal
Forms
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Aux Feedwater MSPI Monthly Data
February
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Aux Feedwater MSPI Monthly Data
March 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Safety Injection MSPI Monthly Data
April 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Safety Injection MSPI Monthly Data
May 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Safety Injection MSPI Monthly Data
June 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 Emergency AC MSPI Monthly Data, SOMS Narrative
Log Search
April 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 1 Emergency AC MSPI Monthly Data, SOMS Narrative
Log Search
February
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Units 1 Emergency AC MSPI Monthly Data, SOMS Narrative
Log Search
January
25
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Forms
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 1 Emergency AC MSPI Monthly Data, SOMS Narrative
Log Search
June 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 Emergency AC MSPI Monthly Data, SOMS Narrative
Log Search
March 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 1 Emergency AC MSPI Monthly Data, SOMS Narrative
Log Search
May 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 2 Emergency AC MSPI Monthly Data, SOMS Narrative
Log Search
April 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 2 Emergency AC MSPI Monthly Data, SOMS Narrative
Log Search
February
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 2 Emergency AC MSPI Monthly Data
January
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 2 Emergency AC MSPI Monthly Data, SOMS Narrative
Log Search
June 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 2 Emergency AC MSPI Monthly Data, SOMS Narrative
Log Search
March 2025
71151
Miscellaneous
NRC and MOR
Unit 2 Emergency AC MSPI Monthly Data, SOMS Narrative
May 2025
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Data Collection
and Submittal
Forms
Log Search
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Component Cooling MSPI Monthly Data
January
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Component Cooling MSPI Monthly Data
February
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Component Cooling MSPI Monthly Data
March 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Cooling Water MSPI Monthly Data
January
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Cooling Water MSPI Monthly Data
March 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Cooling Water MSPI Monthly Data
February
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and Safety Injection MSPI Monthly Data, Units 1 and
Residual Heat Removal MSPI Monthly Data, and LCO
Notes
February
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Units 1 and 2 Safety Injection MSPI Monthly Data, Units 1
and 2 Residual Heat Removal MSPI Monthly Data, and LCO
Notes
January
25
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Forms
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Safety Injection MSPI Monthly Data, Units 1
and 2 Residual Heat Removal MSPI Monthly Data, LCO
Notes
March 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 1 Emergency AC MSPI Monthly Data, and SOMS
Narrative Logs
February
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 1 Emergency AC MSPI Monthly Data, and SOMS
Narrative Logs
February
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 2 Emergency AC MSPI Monthly Data, and SOMS
Narrative Logs
March 2025
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Units 1 and 2 Component Cooling MSPI Monthly Data, CC
MSPI Data Collection Logs
January
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 2 Emergency AC MSPI Monthly Data, and SOMS
Narrative Logs
January
25
71151
Miscellaneous
NRC and MOR
Data Collection
and Submittal
Forms
Unit 2 Emergency AC MSPI Monthly Data, and SOMS
Narrative Logs
March 2025
71151
Miscellaneous
Review
501000100268; 121 Control Room Chiller Tripped on High
Refrigerant Pressure
06/21/2025
71151
Miscellaneous
PI Summary
Report
Prairie Island Unit 1, IE01, IE03, IE04, MS05, MS06, MS07,
MS08, MS09, MS10
July 2024 -
June 2025
71151
Miscellaneous
PI Summary
Prairie Island Unit 1; BI01 - Reactor Coolant System Activity;
July 2024 -
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
Report
BI02 - Reactor Coolant System Identified Leak Rate
June 2025
71151
Miscellaneous
PI Summary
Report
Prairie Island Unit 2; BI01 - Reactor Coolant System Activity;
BI02 - Reactor Coolant System Identified Leak Rate
July 2024 -
June 2025
71151
Miscellaneous
PI Summary
Report; Prairie
Island Unit 2
IE01, IE03, IE04, MS05, MS06, MS07, MS08, MS09, MS10,
July 2024 -
June 2025
71151
Miscellaneous
RCS Leakage
Spreadsheet
RCS Leakage Spreadsheet through July 11, 2025
Corrective Action
Documents
501000090701
Timing Test Exceeded the Parameters of the Test 3 Times
10/04/2024
Corrective Action
Documents
501000090701
Timing Test Exceeded the Parameter of the Test 3 Times
10/04/2024
Corrective Action
Documents
QF0754;
2000015288
501000090701; Undervoltage Relay Failed Testing
10/04/2024
Calculations
SPC-EA-008
Determining Normal Trip Setpoints
0B
Drawings
XH-1-239
Logic Diagrams, Primary Coolant System Signals
Engineering
Evaluations
2000036148
A Duty Operator Identified That Their Key Set, Which
Contained a Vital Access Key, Was Not in Their Possession
as Required. EN 57860
08/11/2025
Miscellaneous
LER 50-
2/2025-001-00
Reactor Trip and Auto-Start Actuation of Auxiliary Feedwater
Due to Bus 11 Undervoltage Relay Issues
09/08/2025