IR 05000261/2023003

– Integrated Inspection Report 05000261 2023003 and 07200060 2023001

ML23310A315
Person / Time
Site:	Robinson
Issue date:	11/07/2023
From:	David Dumbacher Division Reactor Projects II
To:	Basta L Duke Energy Progress
References
IR 2023001
Download: ML23310A315 (1)

Text

SUBJECT:

H.B. ROBINSON STEAM ELECTRIC PLANT - INTEGRATED INSPECTION REPORT 05000261/2023003 AND 07200060/2023001

Dear Laura Basta:

On September 30, 2023, the U.S. Nuclear Regulatory Commission (NRC) completed an inspection at H.B. Robinson Steam Electric Plant. On October 18, 2023, the NRC inspectors discussed the results of this inspection with you and other members of your staff. The results of this inspection are documented in the enclosed report.

Two findings of very low safety significance (Green) are documented in this report. Two of these findings involved violations of NRC requirements. We are treating these violations as non-cited violations (NCVs) consistent with Section 2.3.2 of the Enforcement Policy.

If you contest the violations or the significance or severity of the violations 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 H.B. Robinson Steam Electric Plant.

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 H.B. Robinson Steam Electric Plant.November 7, 2023 L. Basata 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, David E. Dumbacher, Chief Reactor Projects Branch 3 Division of Reactor Projects Docket No. 05000261 and 07200060 License No. DPR-23

Enclosure:

As stated

Inspection Report

Docket Number: 05000261 and 07200060

License Number: DPR-23

Report Number: 05000261/2023003 and 07200060/2023001

Enterprise Identifier: I-2023-003-0022 and I-2023-001-0109

Licensee: Duke Energy Progress, LLC

Facility: H.B. Robinson Steam Electric Plant

Location: Hartsville, SC

Inspection Dates: July 01, 2023 to September 30, 2023

Inspectors: J. Bell, Senior Health Physicist P. Cooper, Senior Reactor Inspector V. Gaffney, Resident Inspector B. Kellner, Senior Health Physicist J. Zeiler, Senior Resident Inspector

Approved By: David E. Dumbacher, Chief Reactor Projects Branch 3 Division of Reactor Projects

Enclosure

SUMMARY

The U.S. Nuclear Regulatory Commission (NRC) continued monitoring the licensees performance by conducting an integrated inspection at H.B. Robinson Steam Electric 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 Follow Procedures Resulting in an Unanticipated Dose Rate Alarm and Unplanned Exposure to a Crane Operator.

Cornerstone Significance Cross-Cutting Report Aspect Section Occupational Green [H.8] - 71124.01 Radiation Safety NCV 05000261/2023003-01 Procedure Open/Closed Adherence A self-revealed finding of very low safety significance (Green) and associated non-cited (NCV)of Robinson Unit 2 Technical Specification (TS) 5.4.1, Procedures, was identified when the licensee failed to implement procedures leading to a worker receiving an unanticipated dose rate alarm and an unplanned exposure of 39 mrem.

Automatic Reactor Trip Due to Inadequate Maintenance Procedure to Replace Reactor Trip Bypass Breaker Cubicle Cell Switch Cornerstone Significance Cross-Cutting Report Aspect Section Initiating Events Green [H.5] - Work 71152A NCV 05000261/2023003-02 Management Open/Closed A self-revealed Green finding and associated NCV of TS 5.4.1, Procedures, was identified for the licensees failure to provide adequate maintenance work order instructions and conduct adequate post-maintenance testing when replacing the cubicle cell switches for the A and B train reactor trip breakers (RTBs) and reactor trip bypass breakers (BYBs) during the previous November 2022, refueling outage. This resulted in the subsequent malfunction of the cubicle cell switch associated with the B BYB during reactor protection system logic testing on June 22, 2023, causing an unplanned automatic reactor trip on Robinson Unit 2.

Additional Tracking Items

Type Issue Number Title Report Section Status LER 05000261/2023-002-00 LER 2023-002-00 for H.B. 71153 Closed Robinson, Unit 2, Plant Trip During Reactor Protection System Testing

PLANT STATUS

Unit 2 operated at or near rated thermal power (RTP) for the entire 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.

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 from Tropical Storm Idalia on August 30-31, 2023.

71111.04 - Equipment Alignment

Partial Walkdown Sample (IP Section 03.01) (4 Samples)

The inspectors evaluated system configurations during partial walkdowns of the following systems/trains:

(1) 'A' emergency diesel generator (EDG) while 'B' EDG was out of service for surveillance testing on July 12, 2023

(2) 'B' safety injection (SI) pump while 'A' SI pump was out of service for preventive maintenance on July 25, 2023

(3) 'B' motor-driven auxiliary feedwater (MDAFW) pump while 'A' MDAFW pump was out of service for preventive maintenance on August 1, 2023

(4) 'A' containment spray (CS) pump while 'B' CS pump was out of service for preventive maintenance on August 9, 2023

71111.05 - Fire Protection

Fire Area Walkdown and Inspection Sample (IP Section 03.01) (5 Samples)

The inspectors evaluated the implementation of the fire protection program by conducting a walkdown and performing a review to verify program compliance, equipment functionality, material condition, and operational readiness of the following fire areas:

(1) turbine building ground floor elevation 226 (fire zones 25A, 25B, and 25C) on July 21, 2023

(2) boric acid tank room and auxiliary building second floor hallway elevation 246 (fire zones 13 and 15) on July 25, 2023

(3) independent spent fuel storage installation (ISFSI) 24P dry storage area (fire zone ISFSI) on August 3, 2023

(4) dedicated shutdown diesel generator (DSDG) (fire zone 25D) on August 21, 2023

(5) 'A' and 'B' residual heat removal (RHR) pump pit (fire zone 27) on September 7, 2023

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

(1) The inspectors evaluated the onsite fire brigade training and performance during an unannounced fire drill on July 21, 2023.

71111.06 - Flood Protection Measures

Flooding Sample (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated internal flooding mitigation protections in the:

E1/E2 electrical equipment area (FLC200A) and vital battery room (FLC190) on September 26, 2023

71111.07A - Heat Exchanger/Sink Performance

Annual Review (IP Section 03.01) (1 Sample)

The inspectors evaluated readiness and performance of:

(1) 'B' MDAFW pump lube oil heat exchanger on July 11, 2023

71111.11Q - Licensed Operator Requalification Program and Licensed Operator Performance

Licensed Operator Performance in the Actual Plant/Main Control Room (IP Section 03.01) (1 Sample)

(1) The inspectors observed and evaluated licensed operator performance in the control room during a down power to 98.5% RTP during the performance of a MDAFW pump surveillance test on August 1, 2023.

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

(1) The inspectors observed and evaluated a licensed operator requalification simulator evaluation on August 8, 2023.

71111.12 - Maintenance Effectiveness

Maintenance Effectiveness (IP Section 03.01) (1 Sample)

The inspectors evaluated the effectiveness of maintenance to ensure the following structures, systems, and components (SSCs) remain capable of performing their intended function:

(1) failure of 'B' reactor trip bypass breaker cell switch operation during reactor protection surveillance testing on June 22, 2023, [nuclear condition report (NCR 2477070)]

Quality Control (IP Section 03.02) (1 Sample)

The inspectors evaluated the effectiveness of maintenance and quality control activities to ensure the following SSC remains capable of performing its intended function:

(1) 'A' EDG output breaker 52/17B following control power fuse failures on August 3, 2023, (NCR 2481751)

71111.13 - Maintenance Risk Assessments and Emergent Work Control

Risk Assessment and Management Sample (IP Section 03.01) (5 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) elevated risk (Green) during emergent repair of turbine trip system upper bank solenoid valve EV-4458B on July 5, 2023

(2) elevated risk (Green) during planned preventive maintenance on the 'A' SI pump on July 25, 2023

(3) elevated risk (Green) during planned preventive maintenance on 'A' MDAFW discharge valve AFW-V2-20A on August 1, 2023

(4) elevated risk (Green) during planned preventive maintenance on 'B' containment spray pump and motor on August 9, 2023

(5) elevated risk (Green) during planned preventive maintenance on the DSDG on August 21-23, 2023

71111.15 - Operability Determinations and Functionality Assessments

Operability Determination or Functionality Assessment (IP Section 03.01) (5 Samples)

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

(1) NCR 2478175, turbine electrohydraulic solenoid trip valve EV-4458B failure to reset during emergency turbine trip system functional testing in accordance with OST-551-2, review completed July 5, 2023

(2) NCR 2479157, 'B' EDG steady state frequency reading below TS limits during fast start testing, review completed July 12, 2023

(3) NCR 2480195, 'B' train post-accident monitoring system core exit thermocouple and reactor coolant system wide range hot leg temperature instrumentation degradation, review completed July 31, 2023

(4) NCR 2481287, degraded optical isolator NM305 resulting in power range nuclear instrumentation channel deviation indication, review completed on August 3, 2023

(5) NCR 2481751, blown control power fuse for 'A' EDG output breaker 52/17B during engine surveillance testing, review completed on August 7, 2023

71111.24 - Testing and Maintenance of Equipment Important to Risk

The inspectors evaluated the following testing and maintenance activities to verify system operability and/or functionality:

Post-Maintenance Testing (PMT) (IP Section 03.01) (6 Samples)

(1) OST-551-2, Turbine Trip Functional Test, following repair of turbine emergency trip system Quadvoter solenoid valve EV-4458B on July 17,2023

(2) OST-207, Comprehensive Flow Test for MDAFW Pumps, following preventive maintenance on MDAFW header isolation to 'A' steam generator valve, AFW-V2-20A on August 1, 2023

(3) OST-352-2, Containment Spray Component Test - Train B, following pump and motor preventive maintenance on August 9, 2023

(4) OST-948, Auto-Start of the Dedicated Shutdown Diesel Generator, and OP-602, Dedicated Shutdown System, Section 5.1.1, following 24-month preventive maintenance and inspection of the DSDG on August 23, 2023

(5) OST-108-2, Boric Acid Pump 'B' Inservice Test, following preventive maintenance on

'B' boric acid transfer pump discharge valve CVC-341 on September 14, 2023

(6) OP-301A, Chemical and Volume Control System Charging Pump A Operation, Section 6.3 for pump break-in after maintenance, and OST-101-1, CVCS Component Test Charging Pump A, following preventive and corrective maintenance on 'A' charging pump on September 21, 2023

Surveillance Testing (IP Section 03.01) (3 Samples)

(1) OST-409-2, EDG B Fast Speed Start, on July 12, 2023

(2) MST-021, Reactor Protection Logic Train 'B' at Power, on August 2, 2023

(3) OST-251-1, RHR Pump A and Components Test, on September 7, 2023

Inservice Testing (IST) (IP Section 03.01) (1 Sample)

(1) OST-202-1, MDAFW System Component Test, on August 1, 2023

71114.06 - Drill Evaluation

Select Emergency Preparedness Drills and/or Training for Observation (IP Section 03.01) (1 Sample)

(1) The inspectors observed and evaluated an emergency preparedness drill on September 6, 2023. The drill involved a fuel failure event followed by a steam generator tube rupture and subsequent radiological release through a faulted main steam safety valve.

71124.01 - Radiological Hazard Assessment and Exposure Controls

Radiological Hazard Assessment (IP Section 03.01) (1 Sample)

(1) The inspectors evaluated how the licensee identifies the magnitude and extent of radiation levels and the concentrations and quantities of radioactive materials and how the licensee assesses radiological hazards.

Instructions to Workers (IP Section 03.02) (1 Sample)

(1) The inspectors evaluated how the licensee instructs workers on plant-related radiological hazards and the radiation protection requirements intended to protect workers from those hazards.

Contamination and Radioactive Material Control (IP Section 03.03) (2 Samples)

The inspectors observed/evaluated the following licensee processes for monitoring and controlling contamination and radioactive material:

(1) workers exiting the unit 2 radiologically controlled area (RCA)

(2) radiation and contamination survey of the RCA yard

Radiological Hazards Control and Work Coverage (IP Section 03.04) (3 Samples)

The inspectors evaluated the licensee's control of radiological hazards for the following radiological work:

(1) work in the spent fuel pool in preparation for dry storage campaign

(2) core barrel lift during previous outage in December 2022

(3) at power containment vessel entry in April 2023

High Radiation Area and Very High Radiation Area Controls (IP Section 03.05) (5 Samples)

The inspectors evaluated licensee controls of the following high radiation areas and very high radiation areas:

(1) volume control tank [locked high radiation area (LHRA)]

(2) waste holdup tank room (LHRA)

(3) #1 auxiliary sump pump room (LHRA)

(4) containment vessel (LHRA)

(5) LHRA around reactor cavity associated with core barrel lift during 2022 refueling outage

Radiation Worker Performance and Radiation Protection Technician Proficiency (IP Section 03.06) (1 Sample)

(1) The inspectors evaluated radiation worker and radiation protection technician performance as it pertains to radiation protection requirements.

71124.08 - Radioactive Solid Waste Processing & Radioactive Material Handling, Storage, &

Transportation

Radioactive Material Storage (IP Section 03.01)

The inspectors evaluated the licensees performance in controlling, labeling and securing the following radioactive materials:

(1) old steam generator storage building

(2) Sealand storage building

(3) old reactor head building

Radioactive Waste System Walkdown (IP Section 03.02) (2 Samples)

The inspectors walked down the following accessible portions of the solid radioactive waste systems and evaluated system configuration and functionality:

(1) waste water demineralization system

(2) spent resin transfer system (piping and valve gallery)

Waste Characterization and Classification (IP Section 03.03) (3 Samples)

The inspectors evaluated the following characterization and classification of radioactive waste:

(1) dry active waste (class A)

(2) spent media storage tank/spent resin storage tank (SMST/SRST) resin blend - 2022 (class A)

(3) spent resin high integrity container (HIC) for shipment/disposal (class B) container ID:

PO702316-7

Shipping Records (IP Section 03.05) (5 Samples)

The inspectors evaluated the following non-excepted radioactive material shipments through a record review:

(1) radioactive material shipment number 21-066, bead resin in an 8-120 poly HIC for burial, class B waste (LSA-II, CAT 2 Quantity, RQ)

(2) radioactive material shipment number 22-075, RCP diffuser (SCO-II)

(3) radioactive material shipment number 22-081,

(2) 20' Sealand containers of dry active waste (LSA-I)

(4) radioactive material shipment number 23-016,

(2) 20' Sealand containers of dry active waste (LSA-II)

(5) radioactive material shipment number 23-0030, dewatered filters in a 10-160 poly HIC for burial, class C waste (LSA-II, RQ)

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)===

(1) Unit 2 (July 1, 2022 through June 30, 2023)

IE03: Unplanned Power Changes per 7000 Critical Hours Sample (IP Section 02.02) (1 Sample)

(1) Unit 2 (July 1, 2022 through June 30, 2023)

MS08: Heat Removal Systems (IP Section 02.07) (1 Sample)

(1) Unit 2 (July 1, 2022 through June 30, 2023)

OR01: Occupational Exposure Control Effectiveness Sample (IP Section 02.15) (1 Sample)

(1) Unit 2 (December 1, 2022 through July 25, 2023)

PR01: Radiological Effluent Technical Specifications/Offsite Dose Calculation Manual Radiological Effluent Occurrences (RETS/ODCM) Radiological Effluent Occurrences Sample (IP Section 02.16) (1 Sample)

(1) Unit 2 (December 1, 2022 through June 30, 2023)

71152A - Annual Follow-up Problem Identification and Resolution Annual Follow-up of Selected Issues (Section 03.03)

The inspectors reviewed the licensees implementation of its corrective action program related to the following issues:

(1) Robinson unit 2 rapid down power due to electrohydraulic fluid leak on right main steam stop valve MS-314 (NCR 2469550)

(2) Reactor trip during performance of procedure MST-021, Reactor Protection Logic Train 'B' at Power, on June 22, 2023 (NCR 2477070)

71153 - Follow-up of Events and Notices of Enforcement Discretion Event Report (IP section 03.02)

The inspectors evaluated the following licensee event reports (LERs):

(1) LER 05000261/2023-002-00, Plant Trip During Reactor Protection System Testing, (ADAMS Accession No. ML23229A506). The inspection conclusions associated with this LER are documented in this report under Inspection Results Section

===711152A. This LER is closed.

OTHER ACTIVITIES

- TEMPORARY INSTRUCTIONS, INFREQUENT AND ABNORMAL

60855 - Operation of an ISFSI

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) 2690, Inspection Program for Storage of Spent Reactor Fuel and Reactor-Related Greater-than-Class C Waste at Independent Spent Fuel Storage Installations and for 10 CFR Part 71 Transportation Packagings."

Operation of an ISFSI===

(1) From August 14 - 16, 2023, the inspectors performed a review of the licensees ISFSI activities to verify compliance with regulatory requirements. During the on-site inspection, the inspectors observed and reviewed licensee activities in each of the five safety focus areas including occupational exposure, public exposure, fuel damage, confinement, and impact to plant operations.

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. Additionally, the inspectors performed independent walkdowns of the heavy load lifting equipment and the ISFSI haul path. The inspector also performed an independent radiation survey of the ISFSI pad.

INSPECTION RESULTS

Failure to follow procedures resulting in an unanticipated dose rate alarm and unplanned exposure to a crane operator.

Cornerstone Significance Cross-Cutting Report Aspect Section Occupational Green [H.8] - 71124.01 Radiation Safety NCV 05000261/2023003-01 Procedure Open/Closed Adherence A self-revealed finding of very low safety significance (Green) and associated NCV of Robinson Unit 2 TS 5.4.1, Procedures, was identified when the licensee failed to implement procedures leading to a worker receiving an unanticipated dose rate alarm and an unplanned exposure of 39 mrem.

Description:

On December 18, 2022, during refueling outage RO-33, the licensee moved the reactor lower internals (core barrel) from its stand in the refueling cavity back into the reactor vessel. This evolution was controlled by procedure MRP-006-1, Vessel Internals Removal and Installation. MRP-006-1, which states, in part, that the reactor lower internals are only to be moved (by the reactor building polar crane) between the approximate center line between the bridge girder legs and the non-cab end with the control cab located at the south end of reactor building. This requirement is intended to minimize dose through increasing distance of cab from the dose source. Due to inadequate procedural adherence and miscommunication, the polar crane operator in the cab began to lift the lower internals with the cab located at the incorrect end of the reactor building (180 degrees from its expected position). This positioned the operator much closer to the lower internals. When the operator began to lift the internals, remote radiation protection staff monitoring identified that dose rates were much higher than expected in the cab of the crane. It was at this time that the staff identified that the polar crane was mispositioned. The crane operator then completed the lift into the reactor vessel.

The crane operator was exposed to the higher than expected dose rates for approximately two and a half minutes. The operator's self-reading dosimeter (SRD) reported a maximum dose rate of 4760 mrem/hr. The operator was working on a radiation work permit (RWP) with SRD setting of 500 mrem/hr dose rate alarm, and was briefed to a momentary anticipated alarm of 1400 mrem/hr. The RWP and SRD dose alarm setting was 100 mrem. The operator received 139 mrem total dose. Once the lift was completed, radiation protection personnel directed the operator to promptly exit containment and the RCA.

Corrective Actions: An NCR was written, and a prompt incident response team was formed in response to the event. This led to a revision of the procedure used to control the core barrel lift to strengthen controls against polar crane mispositioning.

Corrective Action References: NCR #02453457

Performance Assessment:

Performance Deficiency: The licensee's failure to follow procedure MRP-006-1 was a performance deficiency.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the program & process attribute of the occupational radiation safety cornerstone and adversely affected the cornerstone objective to ensure the adequate protection of the worker health and safety from exposure to radiation from radioactive material during routine civilian nuclear reactor operation. The worker received unplanned dose and was exposed to substantially higher radiation fields than anticipated.

Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix C, Occupational Radiation Safety SDP. The finding was determined to be of very low safety significance (Green) because it was not related to ALARA planning, did not result in an overexposure beyond regulatory limits, there was no substantial potential for overexposure, and the ability to assess dose was not compromised.

Cross-Cutting Aspect: H.8 - Procedure Adherence: Individuals follow processes, procedures, and work instructions. Specifically, the licensee failed to follow MRP-006-1 resulting in unplanned dose and an unanticipated dose rate alarm.

Enforcement:

Violation: TS 5.4.1, Procedures, requires that procedures be established, implemented, and maintained as recommended in Appendix A of Regulatory Guide 1.33, Revision 2. This includes procedures for radiation protection and maintenance activities related to the reactor vessel. MRP-006-1, Vessel Internals Removal and Installation, states, in part, that the reactor lower internals are only to be moved (by the reactor building polar crane) between the approximate center line between the bridge girder legs and the non-cab end with the control cab located at the south end of reactor building. Contrary to this, on December 18, 2022, the reactor lower internals were moved with the reactor building polar crane in the improper orientation.

Enforcement Action: This violation is being treated as an NCV, consistent with Section 2.3.2 of the Enforcement Policy.

Automatic Reactor Trip Due to Inadequate Maintenance Procedure to Replace Reactor Trip Bypass Breaker Cubicle Cell Switch Cornerstone Significance Cross-Cutting Report Aspect Section Initiating Events Green [H.5] - Work 71152A NCV 05000261/2023003-02 Management Open/Closed A self-revealed Green finding and associated NCV of TS 5.4.1, Procedures, was identified for the licensees failure to provide adequate maintenance work order instructions and conduct adequate post-maintenance testing when replacing the cubicle cell switches for the A and B train reactor trip breakers (RTBs) and reactor trip bypass breakers (BYBs) during the previous November 2022, refueling outage. This resulted in the subsequent malfunction of the cubicle cell switch associated with the B BYB during reactor protection system logic testing on June 22, 2023, causing an unplanned automatic reactor trip on Robinson Unit 2.

Description:

On June 22, 2023, Robinson Unit 2 experienced an unplanned automatic turbine trip followed by an automatic reactor trip from 100% RTP. The reactor trip occurred during the performance of semiannual TS surveillance testing of the B reactor protection system logic system which involved the operation of the B RTB and B BYB. The licensee determined the reactor trip was caused by a malfunction of the B BYB cubicle cell switch during this testing.

The Robinson RTBs and BYBs are Westinghouse originally supplied DB-50 breakers that utilize breaker cubicle cell switches designed to externally indicate the breaker position inside the cubicle, i.e., whether the breaker is positioned to the racked in or racked out position. The B RTB and B BYB cell switches are bolted to an angle iron channel support bracket at the bottom rear of the breaker cubicle adjacent to the floor. Each cell switch contains eight electrical contacts that change state, either open or closed, based on the position of the breaker as it moves against the spring-operated push rod of the cell switch. The output of one of these contacts provides logic input to the Turbine Control System (TCS) to initiate a turbine trip signal based on the position of the train related RTB and its associated BYB. On June 22, 2023, per the reactor protection logic test procedure, the B BYB was moved to the racked in position and closed to permit operational testing of the B RTB. This should have caused the cell switch contact for the B BYB to open, which would have allowed opening of the B RTB without generating a TCS turbine trip signal. However, due to unexpected flexing of the channel support bracket that the B BYB cell switch was bolted to, the cell switch push rod failed to move inward far enough to change the state of the cell switch contacts. As a result, when the B RTB was opened per subsequent test steps, an actual turbine trip signal was generated, resulting in an actual turbine trip and reactor trip.

The inspectors reviewed the licensee root cause evaluation in NCR 2477070, the Westinghouse vendor manual for the RTBs, maintenance work orders for replacing the breaker cell switches, and interviewed licensee personnel. The inspectors learned that the licensee had recently replaced the cubicle cell switches for all four of the RTBs during the previous refueling outage between November 25-26, 2022, via work orders 20515532 (A train) and 20515533 (B train). The inspectors noted that the instructions associated with these work orders contained very limited guidance, essentially stating to replace the switch and disconnect and reconnect the switch wiring. However, the vendor manual had included thirteen steps that were critical to ensuring that the cell switches were properly installed and would operate properly. Among these steps included, verifying the cell switch contacts change of state by placing a breaker in the cubicle and moving it to the racked in and racked out positions, and, measuring the amount of cell switch overtravel to ensure the switch contacts would not inadvertently change state later with the breaker racked in. The inspectors concluded that had these actions been implemented, most likely, the licensee would have identified the problem created by the cubicle support flexing and malfunction of the cell switch associated with the B BYB.

Corrective Actions: The licensee implemented an engineering change to install support spacers between the cell switch and floor for the B BYB, as well as the B RTB cubicle, which was also susceptible, to prevent cell switch physical movement when operated. The cell switches in the A RTB and A BYB are mounted in breaker cubicles directly above the B Train floor-mounted breaker cubicles and use a different mounting support structure, thus, were not susceptible to a similar malfunction due to undesirable mounting bracket movement. Until the licensee could implement a planned modification in the next refueling outage to provide the ability to monitor, real time, the change of cell switch contact state when racking in or out the breakers, the online semiannual reactor protection system logic test procedures were revised to temporarily bypass the TCS turbine trip signal during online testing to preclude a cell switch contact state change failure from causing a reactor trip. In addition, the licensee planned to revise work maintenance procedures to include necessary vendor replacement instructions and adequate post-maintenance testing requirements when replacing cell switches in the RTBs or BYBs.

Corrective Action References: NCR 2477070

Performance Assessment:

Performance Deficiency: The licensee's failure to establish and implement adequate maintenance instructions and post maintenance testing when replacing cubicle cell switches associated with the A and B train RTBs and BYBs was a performance deficiency that was within the licensees ability to foresee, prevent, and/or correct. Specifically, as a result of not implementing adequate work instructions that included vendor prescribed replacement and post-maintenance testing instructions, the licensee failed to identify unexpected cubicle cell switch mounting structure interferences, causing malfunction of the B BYB cell switch during subsequent reactor protection system logic testing.

Screening: The inspectors determined the performance deficiency was more than minor because it was associated with the Procedure Quality attribute of the Initiating Events cornerstone and adversely affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown as well as power operations. Specifically, the licensee failed to establish appropriate maintenance work order instructions and post-maintenance testing to replace the cubicle cell switches associated with the RTBs and BYBs which caused a turbine trip/reactor trip.

Significance: The inspectors assessed the significance of the finding using IMC 0609 Appendix A, The Significance Determination Process (SDP) for Findings At-Power. The finding was determined to be of very low safety significance (Green) because, although it caused a turbine trip/reactor trip, it did not cause a loss of mitigating equipment relied upon to transition the plant from the onset of a trip to a stable shutdown condition (e.g., loss of condenser or feedwater).

Cross-Cutting Aspect: H.5 - Work Management: The organization implements a process of planning, controlling, and executing work activities such that nuclear safety is the overriding priority. The work process includes the identification and management of risk commensurate to the work and the need for coordination with different groups or job activities. Specifically, the work order planning and execution for replacing RTB and BYB cell switches failed to include adequate maintenance replacement instructions and test requirements to ensure their proper installation and operation which resulted in a plant trip.

Enforcement:

Violation: Robinson Unit 2 TS 5.4.1, Procedures, requires that written procedures shall be established, implemented, and maintained covering the applicable procedures recommended in Regulatory Guide 1.33, Revision 2, Appendix A, February 1978. Regulatory Guide 1.33, Appendix A, Section 9, Procedures for Performing Maintenance, requires, in part, that maintenance that can affect the performance of safety-related equipment should be properly pre-planned and performed in accordance with written procedures, documented instructions, or drawings appropriate to the circumstances. The A and B train RTBs and BYBs cubicle cell switches were replaced November 25-26, 2022, using instructions developed and implemented in work orders 20515532 and 20515533.

Contrary to the above, from November 25, 2022, through June 22, 2023, the licensee failed to properly pre-plan, create written procedures and documented instructions, appropriate to the circumstances for replacing cubicle cell switches for the A and B train RTBs and BYBs. Specifically, the work instructions failed to include vendor specified instructions for properly replacing the cell switches and providing adequate post-maintenance testing that would have verified the proper operation of cell switch contacts and precluded malfunction of the B BYB cell switch on June 22, 2023.

The disposition of this finding and associated violation closes LER 05000261/2023-002-00, Plant Trip During Reactor Protection System Testing.

Enforcement Action: This violation is being treated as an NCV, consistent with Section 2.3.2 of the Enforcement Policy.

EXIT MEETINGS AND DEBRIEFS

The inspectors confirmed that proprietary information was controlled to protect from public disclosure.

• On July 27, 2023, the inspectors presented the radiation safety inspection results to Laura Basta, Site Vice President (VP), and other members of the licensee staff.

• On August 16, 2023, the inspectors presented the operation of an ISFSI inspection results to Laura Basta, Site VP, and other members of the licensee staff.

• On October 18, 2023, the inspectors presented the integrated inspection results to Laura Basta, Site VP, and other members of the licensee staff.

DOCUMENTS REVIEWED

Inspection Type Designation Description or Title Revision or

Procedure Date

71111.01 Procedures AP-053 Severe Weather Response Rev. 10

OMM-021 Operation During Adverse Weather Conditions Rev. 63

71111.04 Procedures OP-202 Safety Injection and Containment Vessel Spray System Rev. 108

OP-402 Auxiliary Feedwater System Rev. 115

OP-604-1 Diesel Generator A Operations Rev. 7

71111.05 Fire Plans CSD-RNP-PFP-Fuel Handling Building ELEV 226 Pre-Fire Plan Rev. 0

26-001

CSD-RNP-PFP-Auxiliary Building Elevation 246 Pre-Fire Plan Rev. 1

AB2-0246-001

CSD-RNP-PFP-Protected Area Southeast Pre-Fire Plan Rev. 2

PA-003

CSD-RNP-PFP-Protected Area ISFSI Area Pre-Fire Plan Rev. 1

PA-005

CSD-RNP-PFP-Turbine Building ELEV 226 Pre-Fire Plan Rev. 1

TB2-0226-001

Procedures AD-FP-ALL-1520 Transient Combustible Control Rev. 0

AD-OP-ALL-0207 Fire Brigade Administrative Controls Rev. 5

AOP-041 Response to Fire Event Rev. 17

FP-012 Fire Protection Systems Minimum Equipment and Rev. 32

Compensatory Actions

71111.06 Procedures RNP-F/PSA-0104 RNP Internal Flooding PRA Partitioning and Walkdown

71111.07A Miscellaneous NLS-90-005 Response to NRC Generic Letter 89-13, Service Water 01/26/1990

System Problems Affecting Safety-Related Equipment

71111.11Q Procedures AD-OP-ALL-1000 Conduct of Operations Rev. 20

AD-TQ-ALL-0420 Conduct of Simulator Training and Evaluation Rev. 19

OP-105 Maneuvering the Plant When Greater Than 25% Power Rev. 74

71111.12 Procedures AD-EG-ALL-1210 Maintenance Rule Program Rev. 5

71111.13 Procedures AD-WC-ALL-On-Line Work Management Rev. 21

200

AD-WC-ALL-On-Line Risk Management Process Revs. 3 and

240 4

CSD-WC-RNP-RNP ERAT Guidance Rev. 1

Inspection Type Designation Description or Title Revision or

Procedure Date

240-00

OMM-048 Work Coordination and Risk Assessment Rev. 71

71111.15 Procedures AD-OP-ALL-0105 Operability Determinations Rev. 7

71111.24 Procedures PLP-033 Post-Maintenance Testing (PMT) Program Rev. 70

71114.06 Procedures AD-EP-ALL-0101 Emergency Classification Rev. 5

AD-EP-ALL-0105 Activation and Operation of the Technical Support Center Rev. 10

AD-EP-ALL-0109 Offsite Protective Action Recommendations Rev. 9

AD-EP-ALL-0111 Control Room Activation of the ERO Rev. 7

AD-EP-ALL-304 State and County Notifications Rev. 7

CSD-EP-RNP-EAL Wallchart Rev. 2

0101-02

71124.01 ALARA Plans RO-33 Refueling/Reactor Head Rev. 0

Corrective Action AR 02453457 Polar crane operator received SRD dose alarm and 12/18/2022

Documents unanticipated dose rate alarm

Corrective Action NCR 02480944 Minor Violation-2023 NRC RP Baseline Inspection 07/27/2023

Documents NCR 02480963 2023 RP Baseline Inspection Green NCV 07/27/2023

Resulting from

Inspection

Miscellaneous Robinson Nuclear Plant Technical Specifications, Section Amendment

5.7.2, High Radiation Areas #212

Licensing Change Proposal Request for Technical 04/24/2023

Specification 5.7.2

Infrequently Performed Tests or Evolutions Plan for Lower

Internals Removal/Replacement 2R33

Procedures MRP-006-1 Vessel Internals Removal and Installation Rev. 9

Radiation RNP-M-Containment Vessel 3rd Level core barrel movement to 12/5/2022

Surveys 20221205-10 stand

RNP-M-Containment Vessel 3rd Level post core barrel set in vessel12/18/2022

221218-10

Radiation Work 2542 RO-33 Core Barrel Movement Activities Rev. 6

Permits (RWPs)

71124.08 Calculations AD-RP-ALL-Radioactive Waste Classification 10 CFR 61 General Station 10/31/2022

5002, Attachment Review Annual, 2022

Inspection Type Designation Description or Title Revision or

Procedure Date

AD-RP-ALL-Radioactive Waste Classification 10 CFR 61 General Station 04/13/2021

5002, Attachment Review Annual, 2021

AD-RP-ALL-Radioactive Waste Classification 10 CFR 61 General Station 10/14/2020

5002, Attachment Review Annual, 2020

Corrective Action NCRs 02462947, and 02466644 Various

Documents

Corrective Action AR 02480947 NRC Observation - Noted that radioactive waste shipping 07/27/2023

Documents survey are being documented manually (paper copy) rather

Resulting from than using VSDS (electronic survey system)

Inspection AR 02480954 NRC Observation - Noted that there is no visual inspection 07/27/2023

PM for the Spent Resin and Spent Media storage tanks.

Determine if there should be a PM.

Miscellaneous National Source Tracking System (NSTS) 2022 Annual 01/11/2022

Inventory Reconciliation Confirmation

National Source Tracking System (NSTS) 2023 Annual 12/12/2022

Inventory Reconciliation Confirmation

EN0213 DOT General Awareness, Safety and Security Awareness 07/25/2023

Training and Qualification Report for RP Shipping Personnel

EN0315 Duke Power DOT Security Plans Training and Qualification 07/25/2023

Report for RP Shipping Personnel

TTC1722-N Learning Activity Completion Report, Physical Protection of 07/25/2023

Cat 1 - Cat 2 Quantities of Radioactive Material [Current

Security Personnel]

TTC1728-N 10CFR37 Training and Qualification Report for RP 07/25/2023

Personnel

Procedures RST-004 Sealed Source Leak Test Rev. 53

Radiation 556299001 SRST Resin Part 61 sample 10/19/2021

Surveys RNP-M-RCP Diffuser Shipping Box Survey for Shipping [I/S Box] 10/17/2022

221012-1

RST-004 and Semi Annual Sealed Leak Test Radioactive Source 06/21/2022

HPP-018 Inventory

RST-004 and Semi Annual Sealed Leak Test Radioactive Source 12/15/2022

Inspection Type Designation Description or Title Revision or

Procedure Date

HPP-018 Inventory

Self-Assessments 02410927-05 2022 Review of 10 CFR 37 Security Program 09/20/2022

2457422-05 Radiation Protection Program 10 CFR Part 20 Self- 03/29/2023

Assessments

71151 Calculations Regulatory Guide 1.21 Gaseous and Liquid Effluents - 07/25/2023

Summation Of All Releases (Total Effluent activity released

and offsite doses) [1st and Second Quarter 2023]

Regulatory Guide 1.21 Gaseous and Liquid Effluents Report- 07/25/2023

Summation Of All Releases (Total Effluent activity released

and offsite doses) [CY 2022]

RNP-M/MECH-NRC Mitigating System Performance Index (MSPI) Basis Rev. 5

1904 Document

Corrective Action NRC Numbers 02451576, 02453169, 02453456, 02455136, Various

Documents and 02471470

Procedures AD-EG-ALL-1217 Mitigating System Performance Index (MSPI) Rev. 3

AD-PI-ALL-0700 Performance Indicators Rev. 5

18