Text

Integrated Inspection Report 05000327/2024003 and 05000328/2024003
	ML24304A883
Person / Time
Site:	Sequoyah
Issue date:	11/06/2024
From:	Louis Mckown; NRC/RGN-II/DORS
To:	Erb D; Tennessee Valley Authority
References
	IR 2024003
	Download: ML24304A883 (1)
	v • d • e

SUBJECT:

SEQUOYAH UNITS 1 AND 2 - INTEGRATED INSPECTION REPORT 05000327/2024003 AND 05000328/2024003

Dear Delson Erb:

On September 30, 2024, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at Sequoyah Units 1 and 2. On October 15, 2024, the NRC inspectors discussed the results of this inspection with Tom Marshall, 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 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 II; the Director, Office of Enforcement; and the NRC Resident Inspector at Sequoyah Units 1 and 2.

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 II; and the NRC Resident Inspector at Sequoyah 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.

November 6, 2024

Sincerely, Louis J. McKown, II, Chief Projects Branch 5 Division of Operating Reactor Safety Docket Nos. 05000327 and 05000328 License Nos. DPR-77 and DPR-79

Enclosure:

As stated

Inspection Report

Docket Numbers:

05000327 and 05000328

License Numbers:

DPR-77 and DPR-79

Report Numbers:

05000327/2024003 and 05000328/2024003

Enterprise Identifier:

I-2024-003-0028

Licensee:

Tennessee Valley Authority

Facility:

Sequoyah Units 1 and 2

Location:

Soddy-Daisy, TN

Inspection Dates:

July 01, 2024 to September 30, 2024

Inspectors:

L. Bryson, Project Engineer

P. Cooper, Senior Reactor Inspector

W. Deschaine, Senior Project Engineer

V. Furr, Reliability and Risk Analyst

P. Meier, Senior Resident Inspector

A. Nielsen, Senior Health Physicist

A. Price, Resident Inspector

D. Restrepo, Health Physicist

J. Rivera, Health Physicist

Approved By:

Louis J. McKown, II, Chief

Projects Branch 5

Division of Operating Reactor Safety

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at Sequoyah 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

RCS leak caused by backfill of a RHR system flow transmitter sensing line Cornerstone Significance Cross-Cutting Aspect Report Section Initiating Events Green NCV 05000327/2024003-01 Open/Closed

[H.12] - Avoid Complacency 71153 A self-revealed Green finding and associated non-cited violation of Technical Specification 5.4.1.a was identified when the licensee failed to implement written procedures covering activities recommended in Regulatory Guide 1.33, Revision, 2, Appendix A. Specifically, the licensee failed to establish and implement a procedure for backfill of residual heat removal (RHR) system flow transmitter sensing lines that was appropriate for plant conditions. This action resulted in lifting the A RHR discharge header relief valve and discharging reactor coolant system (RCS) water to the pressurizer relief tank (PRT).

Additional Tracking Items

None.

PLANT STATUS

Unit 1 began the inspection period at 100 percent rated thermal power (RTP). On August 23, 2024, the unit entered mode three following an automatic trip due to a turbine trip (Event Notification 57285). Mode four was entered on August 26, 2024, to address the cause of the reactor trip. On August 31, 2024, the unit entered mode three and reactor startup (mode two) occurred. Mode one was entered on September 1, 2024, and the main generator was synchronized to the grid on the following day, September 2, 2024. Full RTP was achieved on September 3, 2024, until September 29, 2024, when the unit entered mode three again following an automatic trip due to a turbine trip (Event Notification 57351). The unit entered mode four on September 30, 2024, and remained there through the remainder of the reporting period to address the cause of the reactor trip.

Unit 2 began the inspection period at 100 percent RTP. On July 15, 2024, reactor power was reduced to 45 percent RTP to address main generator issues. Full RTP was restored on July 18, 2024. On July 20, 2024, a controlled rapid load reduction to mode three was performed to address main generator issues. On that same day, Unit 2 entered mode four to perform main generator inspections and repairs. On July 27, 2024, the Unit 2 reactor entered mode three and the reactor was restarted. On July 28, 2024, Unit 2 entered mode one and the main generator was synchronized to the grid on July 29, 2024. After achieving approximately 95 percent RTP on July 30, 2024, Unit 2 entered mode three that same day following an automatic trip due to a turbine trip (Event Notification 57253). Unit 2 proceeded into mode six for a refueling outage (U2R26) while performing inspections and repairs to the main generator and remained in mode six through the remainder of the reporting 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

71111.01 - Adverse Weather Protection

Impending Severe Weather Sample (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated the adequacy of the overall preparations to protect risk-significant systems from impending severe weather involving potential flash flooding and high winds on September 25 and 26, 2024.

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 2 component cooling water system alignment with the 2B component cooling water pump aligned to the "B" train with the "C-S" component cooling water pump unavailable for planned maintenance on July 9, 2024

(2) Unit 2 main steam isolation and safety valves on August 22, 2024

Complete Walkdown Sample (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated system configurations during a complete walkdown of the Unit 1 turbine driven auxiliary feedwater system on September 12, 2024.

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) Unit 2 containment annulus on August 20, 2024

(2) Unit 2 lower containment on August 21, 2024

(3) Auxiliary building compartment 714-01 (corridor 714 foot) on August 21, 2024

(4) Unit 2 upper containment on September 12, 2024.

(5) Control Building elevation 706 on September 17, 2024

Fire Brigade Drill Performance Sample (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated the onsite fire brigade training and performance during an announced fire drill with a simulated fire in the Unit 1 auxiliary building 669 foot elevation on August 27, 2024 (OPDP-3-1).

===71111.08P - Inservice Inspection Activities (PWR) The inspectors verified that the reactor coolant system boundary, reactor vessel internals, risk-significant piping system boundaries, and containment boundary are appropriately monitored for degradation by reviewing the following activities in Unit 2 during the refueling outage from August 26 - 29, 2024.

PWR Inservice Inspection Activities Sample - Nondestructive Examination and Welding Activities (IP Section 03.01)===

Main article: IP 71111.08

The inspectors verified that the following nondestructive examination and welding activities were performed appropriately:

(1) Ultrasonic Examination

Weld #1, flange to vessel weld, MRP-227 exam

202 hot leg nozzle to shell weld, MRP - 227 exam

22 hot leg nozzle to shell weld, MRP-227 exam Eddy Current Examination

Incore Flux Thimble Tubes PWR Inservice Inspection Activities Sample - Vessel Upper Head Penetration Inspection

Activities (IP Section 03.02) (1 Sample)

The inspectors verified that the licensee conducted the following vessel upper head penetration inspections and addressed any identified defects appropriately:

(1) Bare Metal Visual of Penetrations 20, 27, and 35.

PWR Inservice Inspection Activities Sample - Boric Acid Corrosion Control Inspection Activities (IP Section 03.03) (1 Sample)

The inspectors verified the licensee is managing the boric acid corrosion control program through a review of the following evaluations:

(1) SQN-2-FCV-043-0023, RCS Hot Leg HDR Containment Isolation Valve, ASME Class 2

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 2 reactor start-up following a down power to address a turbine bearing issue on July 27, 2024.

Licensed Operator Requalification Training/Examinations (IP Section 03.02) (1 Sample)

(1) The inspectors observed and evaluated a cycle 24-4 pilot crew simulator exam involving a steam generator tube rupture scenario on September 24, 2024 (Segment number OPL273E2441).

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) Unit 1 control rod drive mechanism cooler issues associated with "A" control rod drive mechanism cooler leak and "B' control rod drive fan failure (CR1939435, CR1940005)

(2) Unit 1 and Unit 2 steam dump to condenser failures (CR 1955285, CR 1946817)

71111.13 - Maintenance Risk Assessments and Emergent Work Control

Risk Assessment and Management Sample (IP Section 03.01) (3 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) Unit 1 "B" main feed pump high seal water differential pressure during a conservation operation alert during the week of July 1, 2024 (CR 1940617)

(2) Unit 2 "C-S" component cooling water pump maintenance outage during the week of July 8, 2024

(3) Unit 2 turbine high vibrations and exciter ground troubleshooting and repairs during the week of July 15, 2024 (CR 1943971)

71111.15 - Operability Determinations and Functionality Assessments

Operability Determination or Functionality Assessment (IP Section 03.01) (6 Samples)

The inspectors evaluated the licensee's justifications and actions associated with the following operability determinations and functionality assessments:

(1) Unit 1 control rod deviation (control bank A, rod H-10) alarm identified on June 24, 2024 (CR 1939857)

(2) Unit 1 leading edge flow meter issues associated with the plant computer system impacting the accuracy of indicated rated thermal power identified on July 2, 2024 (CR1941478)

(3) Unit 1 ice condenser 6A air handling unit blower not running identified on July 11, 2024 (CR 1943265)

(4) Unit 2 turbine driven auxiliary feedwater pump slowly spinning with trip and throttle valve shut due to leak-by identified on July 202024 (CR 1945067, CR 1945062)

(5) Unit 2 "A" motor driven auxiliary feedwater pump discharge check valve (2-VLV-003-0820) surveillance failure identified on August 12, 2024 (CR1950020)

(6) Unit 2 emergency core cooling containment sump suction valve to "A" residual heat removal pump (FCV-063-0072-A) failed to open during valve stroke identified on August 27, 2024 (CR 1953959)

71111.20 - Refueling and Other Outage Activities

Refueling/Other Outage Sample (IP Section 03.01) (2 Samples)

(1) The inspectors evaluated a Unit 2 forced outage for turbine vibrations on July 20, 2024 (CR1945095).

(2) The inspectors evaluated a Unit 1 forced outage to address main generator issues from August 23, 2024, through September 1, 2024.

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)

(1)

"C" component cooling water pump maintenance outage during the week of July 8, 2024 (WO 123988231).

(2) Unit 2 transfer canal wafer valve testing following repairs on August 7, 2024 (WO

===123561121)

(3) Unit 1 "A" centrifugal charging pump auxiliary oil pump control switch calibration and testing on August 27, 2024 (WO 123762209)

(4) Unit 2 "A" charging pump motor replacement during the 2024 fall refueling outage,

2R26, in August 2024 (WO 117812692) (5)

Unit 2 loop two and loop four hot leg safety injection check valves (2-VLV-063-0559, 2-VLV-063-0558) replacements during the 2024 fall refueling outage, 2R26, in August 2024 (WO 122699707, WO 122699700)

(6)

"C" component cooling water pump testing following a motor replacement on September 21, 2024 (0-SI-SXP- 070-201.C; WO 117809394)

Surveillance Testing (IP Section 03.01)===

Main article: IP 12356

(1) Unit 2 loss of offsite power with safety injection and emergency diesel generator test on August 9, 2024 (2-SI-OPS-082-026.B)

(2) Unit 1 pressurizer heater capacity test on September 11, 2024 (WO 124001066, 0-SI-OPS-068-297.0)

Containment Isolation Valve (CIV) Testing (IP Section 03.01) (1 Sample)

(1) Unit 2 containment isolation valve local leak rate tests for the incore instrumentation room exhaust and purge isolation penetrations on August 20, 2024 (WO 123728783)

Diverse and Flexible Coping Strategies (FLEX) Testing (IP Section 03.02) (1 Sample)

(1)

"B" three mega-watt FLEX diesel generator full load two-hour surveillance performed on September 25, 2024 (WO124133451)

71114.06 - Drill Evaluation

Additional Drill and/or Training Evolution (1 Sample)

The inspectors evaluated:

(1) A licensed operator training scenario in the simulator associated with a steam generator tube rupture and emergency declaration that contributed to the drill and exercise performance indicator on September 24,

RADIATION SAFETY

71124.06 - Radioactive Gaseous and Liquid Effluent Treatment

Walkdowns and Observations (IP Section 03.01) (5 Samples)

The inspectors evaluated the following radioactive effluent systems during walkdowns:

(1) Auxiliary building exhaust gaseous monitoring system (0-RE-90-101) and associated system configuration and flow path.

(2) Liquid radwaste effluent monitoring system (0-RE-90-122) and associated system configuration and flow path.

(3) Auxiliary Building Gas Treatment System ventilation filtration system and associated system configuration and flow path.

(4) Auxiliary building exhaust routine weekly gaseous sampling.

(5) Cask Decontamination Collector Tank (CDCT) routine pre-release liquid sampling.

Sampling and Analysis (IP Section 03.02) (3 Samples)

Inspectors evaluated the following effluent samples, sampling processes and compensatory samples:

(1) Compensatory sampling for out-of-service (OOS) Essential Raw Cooling Water Liquid Effluent Monitors RM-90-133/140, work order (WO) 123277749.

(2) Compensatory sampling for OOS Liquid Radwaste Effluent Line Monitor RE-90-122, WO 123761595.

(3) Unit 1 upper containment non-routine sampling of noble gas and tritium in response to thermal power change.

Dose Calculations (IP Section 03.03) (3 Samples)

The inspectors evaluated the following dose calculations:

(1) CDCT liquid waste release permit 20241472.008.365.L

(2) Unit 1 containment vent gaseous waste release permit 20241308.027.419.G

(3) Unit 2 containment purge gaseous waste release permit 20241292.029.073.G

Abnormal Discharges (IP Section 03.04) (1 Sample)

The inspectors evaluated the following abnormal discharges:

(1) Unmonitored gaseous release due to damaged and deteriorated ductwork in the auxiliary building exhaust; CR 1931728.

71124.07 - Radiological Environmental Monitoring Program

Environmental Monitoring Equipment and Sampling (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated environmental monitoring equipment and observed collection of environmental samples.

Radiological Environmental Monitoring Program (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated the implementation of the licensees radiological environmental monitoring program.

GPI Implementation (IP Section 03.03) (1 Sample)

(1) The inspectors evaluated the licensees implementation of the Groundwater Protection Initiative (GPI) program to identify incomplete or discontinued program elements.

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)===

Main article: IP 71151

(1) Unit 1 (July 1, 2023 through June 30, 2024)