IR 05000454/2023011

Fire Protection Team Inspection Report 05000454/2023011 and 05000455/2023011

ML24079A084
Person / Time
Site:	Byron
Issue date:	03/20/2024
From:	Jasmine Gilliam NRC/RGN-III/DORS/EB2
To:	Rhoades D Constellation Energy Generation, Constellation Nuclear
References
IR 2023011
Download: ML24079A084 (1)

Text

SUBJECT:

BYRON STATION - FIRE PROTECTION TEAM INSPECTION REPORT 05000454/2023011 AND 05000455/2023011

Dear David Rhoades:

On February 16, 2024, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Byron Station and discussed the results of this inspection with Harris Welt 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 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 Byron Station.March 20, 2024 D Rhoades 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, Jasmine A. Gilliam, Chief Engineering Branch 2 Division of Operating Reactor Safety Docket Nos. 05000454 and 05000455 License Nos. NPF-37 and NPF-66

Enclosure:

As stated

Inspection Report

Docket Numbers: 05000454 and 05000455

License Numbers: NPF-37 and NPF-66

Report Numbers: 05000454/2023011 and 05000455/2023011

Licensee: Constellation Energy Generation, LLC

Facility: Byron Station

Location: Byron, IL

Inspection Dates: November 27, 2023 to December 15, 2023

Inspectors: M. Abuhamdan, Reactor Inspector B. Jose, Senior Reactor Inspector A. Shaikh, Senior Reactor Inspector

Approved By: Jasmine A. Gilliam, Chief Engineering Branch 2 Division of Operating Reactor Safety

Enclosure

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting a fire protection team inspection at Byron Station, in accordance with the Reactor Oversight Process. The Reactor Oversight Process is the NRCs program for overseeing the safe operation of commercial nuclear power reactors. Refer to https://www.nrc.gov/reactors/operating/oversight.html for more information.

List of Findings and Violations

Failure to Perform Quality Review for NRC Information Notice 2017-06 Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [H.14] - 71111.21N.

Systems FIN 05000454,05000455/2023011-01 Conservative 05 Open/Closed Bias The inspectors identified a finding (FIN) of very low safety significance (Green) that was not associated with a violation for the licensees failure to perform a quality review for level 3 Operating Experience (OPEX) as specified in Exelon Generation (currently Constellation)

Procedure PI-AA-115-1003, Revision 3 (applicable in 2017 timeframe) Processing of Level 3 OPEX Evaluation. Specifically, the licensee failed to perform a quality review for NRC Information Notice (IN) 2017-06, "Battery and Battery Charger Short-Circuit Current Contributions to a fault on the Direct Current (DC) Distribution System," to ensure the documentation in the OPEX evaluation was a stand-alone document and clear enough to identify that the review was completed satisfactorily.

Additional Tracking Items

Type Issue Number Title Report Section Status URI 05000454,05000455/20 Potential Protective Device 71111.21N.05 Closed 21011-02 Coordination Issues Associated with Battery Charger Short-Circuit Output

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 in the selected fire zones will function as required to support the credited functions stated for each sample. Additional inspection considerations are located in the fire hazards analysis (FHA) or safe shutdown analysis (SSA).

(1)

• Fire Zone 5.5.1, Unit 1 Auxiliary Electrical Equipment Room (AEER)

(2)

• Fire Zone 11.3-1, Unit 1 Containment Pipe Penetration Area

(3)

• Fire Zone 5.6-2, Unit 1 Division 2 Miscellaneous Electrical Equipment Room (MEER)

Fire Protection Program Administrative Controls (IP Section 03.02) (1 Sample)

The inspectors verified that the selected control or process is implemented in accordance with the licensees current licensing basis. If applicable, ensure that the licensees FPP contains adequate procedures to implement the selected administrative control. Verify that the selected administrative control meets the requirements of all committed industry standards.

(1) Transient Combustible Control Program

Fire Protection Program Changes/Modifications (IP Section 03.03) (2 Samples)

The inspectors verified the following:

a. Changes to the approved FPP do 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 have not been degraded through changes or modifications.

d. The FPP documents, such as the Updated Final Safety Analysis Report, fire protection report, FHA, and SSA were updated consistent with the FPP or design change.

e. Post-fire Safe Shutdown operating procedures, such as abnormal operating procedures, affected by the modification were updated.

(1)

• EC-EVAL 395449 GL 86-10 Evaluation of New Steel Support Members in the Diesel Generator 18/28 and Switchgear Room Air Shafts (2)

• EC-EVAL 397405 GL 86-10 Evaluation of Non-Rated Ventilation Damper In TRM Fire Wall In the OB Fire Pump Room

INSPECTION RESULTS

Failure to Perform Quality Review for NRC Information Notice 2017-06 Cornerstone Significance Cross-Cutting Report Aspect Section Mitigating Green [H.14] - 71111.21N.05 Systems FIN 05000454,05000455/2023011-01 Conservative Open/Closed Bias The inspectors identified a finding (FIN) of very low safety significance (Green) that was not associated with a violation for the licensees failure to perform a quality review for level 3 Operating Experience (OPEX) as specified in Exelon Generation (currently Constellation)

Procedure PI-AA-115-1003, Revision 3 (applicable in 2017 timeframe) Processing of Level 3 OPEX Evaluation. Specifically, the licensee failed to perform a quality review for NRC Information Notice (IN) 2017-06, "Battery and Battery Charger Short-Circuit Current Contributions to a fault on the Direct Current (DC) Distribution System," to ensure the documentation in the OPEX evaluation was a stand-alone document and clear enough to identify that the review was completed satisfactorily.

Description:

During the Design Basis Assurance Team Inspection completed on April 15, 2021, NRC inspectors identified an Unresolved Item (URI 05000454,05000455/2021011-02) which could not be resolved without additional information. This issue was associated with the licensees failure to perform an adequate evaluation for NRC IN 2017-06. Specifically, the Byron 125 Vdc and 250 Vdc battery chargers were silicon-controlled rectifier (SCR) type battery chargers, and the testing described in the IN demonstrated SCR-type battery chargers produced significantly higher currents than expected. When the inspectors reviewed the licensees initial operating experience evaluation for NRC IN 2017-06, dated November 8, 2017, they found that the licensee acknowledged the potentially higher short-circuit contribution from a battery charger but justified not performing any additional actions. The licensees justification was based, in part, on their use of conservative short-circuit current data as calculational inputs and the belief that existing calculations contained significant margin to station breaker interrupting ratings.

The licensee did not review interrupting rating of battery charger internal fuses, coordination between battery charger internal fuses, charger output breaker and the downstream interrupting devices.

The inspectors review of calculations BYR97-225, Circuit Breaker Trip Settings for 125 Vdc and 250V dc and BYR97-227, 125 Vdc Fuse Sizing and Coordination found that the licensee credited the 125 Vdc battery charger current limit feature to maintain coordination between the battery charger output breaker and multiple downstream protective devices. Downstream protective devices included individual load breakers and a pair of fuses on the safety-related 125 Vdc bus. The two fuses, which were arranged in series, connected the safety-related bus to the non-safety-related bus and were credited as isolation devices. The inspectors could not find a technical basis supporting the licensees conclusion that their battery chargers would limit current fast enough to maintain protective device coordination.

The inspectors reviewed the time-current characteristics curve for the battery charger output breaker and found that it could open at current levels as low as 3 times the battery charger full load ampere rating (400 Amperes) if the battery charger failed to limit current during the first 100 milliseconds of a fault. The inspectors were concerned that faults on 125 Vdc cables or equipment could cause the loss of a battery charger that was not already considered in the licensees analyses for events such as fire, flood, High Energy Line Break (HELB) or other similar events. The inspectors also identified that a cable 1RD417, (2, 1 /C #2) powered from division 11, 125 Vdc panel in division 11 Miscellaneous Electrical Equipment Room (MEER)passing through division 12 MEER. Because of this, a fire in division 12 MEER could potentially short 1RD417 cable, which could result in tripping the division 11, 125 Vdc battery charger that is credited for safe shutdown for a fire in division 12 MEER. The inspectors decided to keep the URI open pending a review of the licensees updated evaluation of NRC IN 2017-06, which was being tracked by Action Request (AR) 4415085 and a determination of whether any performance deficiencies or violations of NRC requirements had occurred.

During the 2023 Fire Protection Team Inspection, inspectors reviewed the licensees revised response to IN 2017-06 dated December 15, 2021. In this revision, the inspectors noted that the licensee did evaluate the battery charger internal fuses for acceptable interrupting rating and coordination with the battery charger output breaker. The licensee provided an additional white paper to support the revised evaluation. In the supporting white paper, the licensee reviewed the NRC concern related to cable 1RD417 powered from division 11 DC distribution panel passing through division 12 MEER. The licensee determined that 36 feet of this cable is in division 11 and cable fault due to a fire in division 12 MEER can only occur at the earliest at 36 feet length of the cable. The licensee calculated short-circuit current at 36 feet of the cable to be 3,926 amperes using battery internal and external resistances, various connection point contact resistances and the cable resistance for 36 feet. The licensee assumed 20% of 3926 amperes (785 Amperes) to be the contribution from the charger based on the rational that during the BNL testing the actual measured charger contribution to the fault at the battery load side was only 16% of the total fault current. The 600 Ampere battery charger breaker will take over 100 seconds to trip at 785 amperes. The inspectors obtained clarifying guidance from staff in NRR concerning the methodology adopted by the licensee in calculating the fault current contribution. Based on discussions and correspondence with NRR staff, the inspectors concluded that the licensees assumption of 20% battery charger fault current contribution was incorrect, and the actual value would likely be higher based on information presented in IN 2017-06. However, using the available information concerning the particular circuit at Byron Station and industry guidance, the inspectors, under guidance from NRR staff, could not reasonably determine that the battery charger fault current contribution would exceed 1200 amperes (instantaneous trip set point). Therefore, the inspectors could not reasonably conclude that division 11 DC battery charger would trip due to a fire in the 12 MEER room.

Section 4.5, Quality Review, of Exelon Generation (now Constellation) Procedure PI-AA-115-1003, Revision 3,Processing of Level 3 OPEX Evaluation, directed a quality review be performed to ensure the documentation in the OPEX evaluation is a stand-alone document and is clear enough to identify that the review was completed satisfactorily. The inspectors determined the licensee's initial Level 3 OPEX evaluation for IN 2017-06, dated November 8, 2017, did not meet the licensee's standard for a Level 3 OPEX review because the evaluation was not stand-alone and was not clear enough to identify the review was completed satisfactorily. Specifically, the licensee's initial OPEX review did not demonstrate why the site was not vulnerable to the situation described in IN 2017-06 nor did it provide information to demonstrate that the station equipment would be able to withstand the larger short-circuit conditions provided by the chargers as described in the IN. The licensees failure to perform a proper/complete review of the Level 3 OPEX evaluation for IN 2017-006 was contrary to the Exelon Procedure PI-AA-115-1003 and was a performance deficiency. No violations of NRC requirements were identified since this procedure was not safety-related and therefore, not subject to 10 CFR Part 50 Appendix B requirements.

Corrective Actions: The licensee revised the Level 3 OPEX evaluation for IN 2017-06 and performed a site specific fault current circuit analysis. The licensee concluded the now larger short-circuit current contribution from the charger did not exceed the safe interrupting ratings of equipment/isolation devices.

Corrective Action References: AR 4415085 - NRC DBAI - NRC Information Notice 2017-06 Evaluation AR 04750364 - NRC ID-2023 FPT - Error in DC URI Response

Performance Assessment:

Performance Deficiency: The inspectors determined the licensees failure to perform a proper Level 3 OPEX evaluation for IN 2017-06 was contrary to Exelon Generation Procedure PI-AA-115-1003, revision 3, Processing of Level 3 OPEX Evaluation. Specifically, the licensee failed to ensure the documentation in the OPEX evaluation was stand-alone and clear enough to identify the review was completed satisfactorily. Specifically, OPEX evaluation OPXR ATI Assignment #: 04061107-02 failed to demonstrate why the site was not vulnerable to the situation described in the IN nor did it provide information to demonstrate station equipment would be able to withstand the larger short-circuit conditions provided by the chargers as described in the Information Notice.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Design Control 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. The inspectors determined the performance deficiency was more than minor because it was associated with the Design Control 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, regardless of the results of the final/revised evaluation, the failure to perform proper Level 3 OPEX evaluation for NRC IN 2017-06 resulted in a condition where there was a reasonable doubt that equipment/isolation devices were able to withstand the larger short-circuit conditions provided by the chargers as described in the IN.

Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The inspectors assessed the significance of the finding using Manual Chapter 0609, Appendix A, The SDP for Findings At-Power. The finding screened as of very low safety significance (Green) because it did not result in the loss of operability or functionality of Mitigating Systems.

Specifically, the licensee revised the IN 2017-06 evaluation and were able to demonstrate that equipment/isolation devices were capable to withstand the available short-circuit current.

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's initial evaluation for IN 2017-06 failed to evaluate the effect of the larger short-circuit current contribution from the charger on the interrupting rating of the equipment/isolation devices. Instead, the licensee believed that the use of conservative short-circuit current data as calculational inputs and the belief that existing calculations contained significant margin to station breaker interrupting ratings.

Enforcement:

Inspectors did not identify a violation of regulatory requirements associated with this finding.

The disposition of this finding closes URI: 05000454,05000455/2021011-02.

Unresolved Item Potential Protective Device Coordination Issues 71111.21N.

(Closed) Associated with Battery Charger Short-Circuit Output 05 URI 05000454,05000455/2021011-02

Description:

The disposition of finding 2023011-01 closes URI 05000454,05000455/2021011-02. 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 February 16, 2024, the inspectors presented the fire protection team inspection results to Harris Welt and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection Type Designation Description or Title Revision or

Procedure Date

71111.21N.05 Calculations ATD-0026 Calc. for Combustible Fire Loads Attachment A Rev.14

Corrective Action 04474137 NOS ID: Improperly Stored Flammable Materials in the 01/26/2022

Documents RSH

04670706 Unit 1 MSIV Rooms-377 Elevation-Housekeeping Poor. 04/17/2023

04686481 2Q23 SWPPP Walkdown-Poor Housekeeping in SX 06/16/2023

Chem TK Room

04696832 Transient Combustible Control Issue-Hot Shop 08/16/2023

04719586 Area 5 Scaffold Never Removed after B1R23 11/25/2023

Corrective Action 04720409 NRC Identified-Ladder Resting on Piping in Area 5 Pen 11/29/2023

Documents Room

Resulting from 04722970 NRC Identified-Improper Use of Ladder And Scaffolding 12/12/2023

Inspection

Engineering 395449 Evaluation of New Steel Support Members in the Diesel 10/24/2013

Changes Generator 1B/2B and Switchgear Room Air Shafts

397405 Evaluation of Non-Rated Ventilation Damper in TRM Fire Rev.0

Wall in the 0B Fire Pump Room

Procedures 1BOA ELEC-5 Local Emergency Control of Safe Shutdown Equipment Rev.108

Unit 1

BHP 4200-33 Installation of Appendix "R" Emergency Cable Rev.10

BOP FC-7 Startup of the Purification System to Purify or Recirculate Rev.15

The Refueling Water Storage Tank

BOP FC-8 Shutdown of RWST Purification or Recirculation Rev.11

BOP FP-27 Smoke Removal Plan and MCR/AEER Supplemental Rev.9

Cooling Plan

CC-AA-112 Temporary Configuration Changes Rev.32

CC-AA-201 Plant Barrier Control Program Rev.14

MA-AA-716-025 Scaffold Installation, Modification, and Removal Request Rev.20

Process

MA-AA-716-026 Station Housekeeping/ Material Condition Program Rev.21

MA-AA-796-024 Scaffold Installation, Inspection, and Removal Rev.13

MA-BY-716-026-Seismic Housekeeping Rev.2

1001

Inspection Type Designation Description or Title Revision or

Procedure Date

OP-AA-102-106 Attachment 1-Operator Response Time Validation Sheet Rev.4

OP-AA-201-009 Control of Transient Combustible Material Rev.30

SA-AA-0301 Constellation Nuclear Industrial Safety Pocket Guide 2023Rev.20

SA-AA-115 Work at Heights Rev.15

Work Orders 04799836-01 EWP EM PERF Fire Prot SURV Zones 24, 39, 67, 68, 69, 05/14/2020

75, 76, 77, 78

05023563 00141176-01, PMNS, U-1 Fire Hazards Panel 09/26/2021

Instrumentation Surveillance, W:1B OSR XFP-R1

05363303 00170058-01, PMNS, FP Required Gas Powered 08/08/2023

Generator/Fan Run, W:FP Generator

05390364 FP Required Gas Powered Generator/ Fan Run 11/06/2023

9