IR 05000352/2022011
| ML22181B069 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 06/30/2022 |
| From: | Glenn Dentel Division of Operating Reactors |
| To: | Rhoades D Constellation Energy Generation, Constellation Nuclear |
| Dentel G | |
| References | |
| IR 2022011 | |
| Download: ML22181B069 (12) | |
Text
June 30, 2022
SUBJECT:
LIMERICK GENERATING STATION, UNITS 1 AND 2 - TRIENNIAL FIRE PROTECTION INSPECTION REPORT 05000352/2022011 AND 05000353/2022011
Dear Mr. Rhoades:
On June 23, 2022, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Limerick Generating Station, Units 1 and 2 and discussed the results of this inspection with Mr. Frank Sturniolo, Site Vice President and other members of your staff. The results of this inspection are documented in the enclosed report.
One finding of very low safety significance (Green) is documented in this report. This finding did not involve a violation of NRC requirements.
If you disagree with 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 I; and the NRC Resident Inspector at Limerick Generating Station, Units 1 and 2. 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, Glenn T. Dentel, Chief Engineering Branch 2 Division of Operating Reactor Safety
Docket Nos. 05000352 and 05000353 License Nos. NPF-39 and NPF-85
Enclosure:
As stated
Inspection Report
Docket Numbers:
05000352 and 05000353
License Numbers:
Report Numbers:
05000352/2022011 and 05000353/2022011
Enterprise Identifier: I-2022-011-0013
Licensee:
Constellation Energy Generation, LLC
Facility:
Limerick Generating Station, Units 1 and 2
Location:
Sanatoga, PA 19464
Inspection Dates:
June 6, 2022 to June 23, 2022
Inspectors:
C. Bickett, Senior Reactor Inspector
E. Miller, Reactor Inspector
A. Patel, Senior Reactor Inspector
Approved By:
Glenn T. Dentel, Chief
Engineering Branch 2
Division of Operating Reactor Safety
SUMMARY
The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a triennial fire protection inspection at Limerick Generating Station,
Units 1 and 2, 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 Validate Time Critical Action per Operator Response Time Program Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems Green FIN 05000352,05000353/2022011-01 Open/Closed None (NPP)71111.21N.
The inspectors identified a Green finding because Constellation did not validate a 20-minute time critical action to manually initiate low pressure coolant injection (LPCI) for a fire in Fire Area 68W in accordance with Section 4.2 of procedure OP-AA-102-106, Operator Time Response Program.
Additional Tracking Items
None.
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.
REACTOR SAFETY
===71111.21N.05 - Fire Protection Team Inspection (FPTI)
Structures, Systems, and Components (SSCs) Credited for Fire Prevention, Detection, Suppression, or Post-Fire Safe Shutdown Review (IP Section 03.01)===
The inspectors verified that components and/or systems would function as required to support the credited functions stated for each sample. Additional inspection considerations were located in the fire hazards analysis (FHA) or safe shutdown analysis (SSA).
- (1) Residual Heat Removal System
- (2) Class 1E DC Power
- (3) Halon Suppression System
- (4) Fire Barriers
Fire Protection Program Administrative Controls (IP Section 03.02) (1 Sample)
The inspectors verified that the selected control or process was implemented in accordance with the licensees current licensing basis. The inspectors ensured that the licensees fire protection program contained adequate procedures to implement the selected administrative control and verified that the selected administrative control met the requirements of all committed industry standards.
- (1) Combustible Control Program
Fire Protection Program Changes/Modifications (IP Section 03.03) (2 Samples)
The inspectors verified the following:
a. Changes to the approved fire protection program did not constitute an adverse effect on the ability to safely shutdown.
b. The adequacy of the design modification, if applicable.
c. Assumptions and performance capability stated in the SSA had not been degraded through changes or modifications.
d. The fire protection program documents, such as the Updated Final Safety Analysis Report, fire protection report, FHA, and SSA were updated consistent with the fire protection program or design change.
e. Post-fire safe shutdown operating procedures, such as abnormal operating procedures, affected by the modification were updated.
- (1) EC 625788, 201 Safeguard 0BX103 Transformer Replacement
- (2) EC 632790, Combustible Free Zone/Transient Combustible Free Zone Reduction
INSPECTION RESULTS
Failure to Validate Time Critical Action per Operator Response Time Program Cornerstone Significance Cross-Cutting Aspect Report Section Mitigating Systems
Green FIN 05000352,05000353/2022011-01 Open/Closed
None (NPP)71111.21N.05 The inspectors identified a Green finding because Constellation did not validate a 20-minute time critical action to manually initiate low pressure coolant injection (LPCI) for a fire in Fire Area 68W in accordance with Section 4.2 of procedure OP-AA-102-106, Operator Time Response Program.
Description:
Constellation procedure OP-AA-102-106, Operator Time Response Program, provides corporate governance regarding identification, control, validation, and documentation requirements for time critical actions (TCAs). TCAs include manual operator actions required to support a credited strategy in the safety analysis. This includes actions in the fire hazards and fire safe shutdown analyses.
This procedure states, in part, that each plant has actions that are to be accomplished in a specified time, and completion of these actions ensures the plant complies with the assumptions made during the analysis of plant events. Per Section 4.2.2, the master list of TCAs shall include the available time in minutes, performance time in minutes, and the ratio of available time to performance time, which determines whether periodic time validation is required. Available time is defined as the time interval from the cue to perform the manual action to the time the analysis credits completion of the manual action and still meet the requirements of the plants design basis or other documented evaluations. Additionally, Section 4.2.7 states that issues that need to be considered include the sequence of TCAs.
Procedure OP-LG-102-106, Operator Time Response Program at Limerick Station, provides the master list of TCAs at Limerick. Included in this list are TCAs 9, 10, and 11, which describe the actions credited to manually initiate LPCI, a mode of the residual heat removal system, in the event of a major fire in Fire Area 68W. Specifically:
- TCA 9 - operator starts the residual heat removal pump from the respective switchgear
- TCA 10 - operator positions residual heat removal valves 2F015B, 2F027B, and 2F048B from panel 20-C601X1 on 217 elevation
- TCA 11 - operator positions residual heat removal valve 2F017B from panel 20-C601X2 on 283 elevation
These TCAs are analogous to Steps 3.2.1, 3.3.1, and 3.3.2 in the associated fire safe shutdown guide, 2FSSG-3068W. Operators use 2FSSG-3068W in conjunction with other operating procedures to safely shutdown the plant following a fire in Fire Area 68W. In this scenario, LPCI is the credited source for reactor vessel inventory control. Per 2FSSG-3068W, Steps 3.3.1 and 3.3.2 (TCA 10 and TCA 11), which encompass the valve lineup, are performed by one operator in sequence, and Step 3.2.1 (TCA 9) is performed by another operator after the valve lineup is complete. Additionally, 2FSSG-3068W and the supporting fire safe shutdown calculation, LF-0016-0068W, state that manual initiation of LPCI is a prompt action that may be required for safe shutdown and is required to be completed within 20 minutes.
To determine whether operators could manually initiate LPCI within 20 minutes, the inspectors reviewed the most recent time validations of TCAs 9, 10, and 11. The inspectors noted that the station time-validated these TCAs independently of each other and assigned each individual TCA an available time of 20 minutes. The inspectors also noted that Constellation exempted TCA 9 from the six-year periodic validation since the ratio of available time (20 minutes) to expected performance time (four minutes) was greater than three (i.e., low risk of failure).
Constellations last time validation of TCA 10, completed in October 2021, demonstrated that operators took an average of 11.75 minutes to complete the action, with the fastest being eight minutes and the slowest being 13 minutes. The last validation of TCA 11, completed in October 2016, demonstrated that most of the operators took less than six minutes to complete the action, with the fastest being just over three minutes and the slowest being over nine minutes. Constellation also noted in both time validations that ratio of the average performance time to available time (20 minutes) was less than 0.8, so no issue reports or margin improvement actions were required.
The inspectors determined that assigning an available time of 20 minutes to each individual action did not meet the OP-AA-102-106 definition of available time since all three actions are required to manually initiate LPCI within a total of 20 minutes for a fire in Fire Area 68W. The inspectors also noted that Constellation did not holistically review individual TCAs completed in a certain sequence to meet a comprehensive objective, like manual initiation of LPCI, to ensure that the periodic validations demonstrated operators could meet the times assumed in station analyses. Additionally, the inspectors determined that calculated margins for the TCAs needed to manually initiate LPCI were incorrect when using an available time of 20 minutes for each separate action. Based on information available in the existing validations, the inspectors concluded it is likely that the time required to manually initiate LPCI per 2FSSG-3068W would exceed a margin threshold and require an issue report and/or margin improvement actions. Based on an inspector field walkdown completed with an operator on June 10, 2022, and consideration of the individual time validations discussed above, the inspectors concluded there was reasonable assurance that the operators could manually initiate LPCI within 20 minutes for a fire in Fire Area 68W. Of note, portions of TCA 9 could be performed concurrently with TCA 10 and 11.
Corrective Actions: Constellation entered this issue into their corrective action program for further evaluation.
Corrective Action References: IR 04507318
Performance Assessment:
Performance Deficiency: The inspectors determined that Constellations failure to validate a 20-minute time critical action to manually initiate LPCI for a fire in Fire Area 68W in accordance with Section 4.2 of procedure OP-AA-102-106, Operator Time Response Program was a performance deficiency that was reasonably within Constellations ability to foresee and correct. Constellation did not ensure that the three TCAs that were credited to manually initiate LPCI could all be performed together within 20 minutes to satisfy the assumptions in the associated fire safe shutdown guide and calculation.
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. Because Constellations time validation structure did not account for the sequence of actions required to manually initiate LPCI, and the individual TCAs were each assigned an available time of 20 minutes, the station could unknowingly exceed the overall 20-minute requirement documented in 2FSSG-3068W and fire safe shutdown calculation LF-0016-0068W. Additionally, the inspectors noted that there were other examples of TCAs in OP-LG-102-106 that were sequenced together to accomplish an overall objective but were not validated as such (e.g., TCAs 2 and 3 for the reactor core isolation cooling system for a fire in Fire Area 7).
Significance: The inspectors assessed the significance of the finding using Appendix F, Fire Protection and Post - Fire Safe Shutdown SDP. Appendix F was applicable in this case because the finding was associated with post-fire safe shutdown. This issue screened as Green in Step 1.4.7-C because the fire finding did not adversely affect the ability to reach and maintain hot shutdown/hot standby using the credited safe shutdown path. Based on field walkdowns and consideration of individual time validations, the inspectors determined there was reasonable assurance that the operators could manually initiate the LPCI system in 20 minutes for a fire in Fire Area 68W.
Cross-Cutting Aspect: Not Present Performance. No cross-cutting aspect was assigned to this finding because the inspectors determined the finding did not reflect present licensee performance.
Enforcement:
Inspectors did not identify a violation of regulatory requirements associated with this finding.
EXIT MEETINGS AND DEBRIEFS
The inspectors verified no proprietary information was retained or documented in this report.
- On June 23, 2022, the inspectors presented the triennial fire protection inspection results to Mr. Frank Sturniolo, Site Vice President and other members of the licensee staff.
DOCUMENTS REVIEWED
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
71111.21N.05 Calculations
LE-130
Class 1E 125/250V DC System Analysis
LEAM-0001
HPCI and RCIC Loads During FSSD
0A
LF-0016-007
Fire Area 007 Fire Safe Shutdown Analysis
LF-0016-068W
Fire Area 068W Fire Safe Shutdown Analysis
LF-0016-068W
Fire Area 068W Fire Safe Shutdown Analysis
1A
LF-0016-068W
Fire Area 068W Fire Safe Shutdown Analysis
1B
LG-PRA-021.11
Limerick Generating Station Fire Probabilistic Risk
Assessment Summary and Quantification Notebook
Corrective Action
Documents
04156586
233701
278009
284972
04312374
04337862
04400188
Corrective Action
Documents
Resulting from
Inspection
04504421
04504447
04504646
04504667
04504704
04504767
04504891
04505317
04505478
04505495
04506733
04506974
04506981
04507012
04507054
04507056
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
04507318
Engineering
Changes
28970
201 Safeguard Transformer Fire System Design
2790
Combustible Fire Zone Evaluation
Engineering
Evaluations
IR 01382361-41
Performance Based Evaluation of Selected Fire Protection
Testing to Extend the Testing Interval
LEAF-0088
Limerick Generating Station Combustible Free Zone
Evaluation
Fire Plans
F-R-500
Limerick Generating Station Pre-Fire Plan
F-R-574
Limerick Generating Station Pre-Fire Plan
Miscellaneous
1P-13.5
Unit 1 Halon Pre-Op Test
04/10/1989
2P-13.5
Halon Pre-Op Test
04/10/1989
LGSOPS2008
LGS Operations Initial Training - Fire Safe Shutdown
Guides (FSSG)
NE-294
Post-Fire Safe Shutdown Program Requirements
Standard for Halon 1301
TCA 11 Operator Response Time Validation Sheet
10/11/2016
TCA 10 Operator Response Time Validation Sheet
10/14/2021
TCP 754
Fire Zone Permit 754
2/23/2022
Procedures
1/2 FSSG-3007
Fire Area 007 Fire Guide
Fire Area 068W Fire Guide
Station Housekeeping/Material Condition Program
MA-AA-716-026-
1001
Additional Guidance for In-Plant/Yard Storage and
Housekeeping at Limerick
Operator Time Response Program
Control of Transient Combustible Material
OP-LG-102-106
Operator Time Response Program at Limerick Station
Unit Common TRM Fire Door Inspection
Work Orders
280402
04643397
Inspection
Procedure
Type
Designation
Description or Title
Revision or
Date
04736727
05044327