Text

Summary of Facility Changes, Tests, and Experiments
	ML25085A252
Person / Time
Site:	North Anna ; (NPF-004, NPF-007)
Issue date:	03/26/2025
From:	Hilbert L; Virginia Electric & Power Co (VEPCO)
To:	; Office of Nuclear Reactor Regulation, Document Control Desk
References
	25-074
	Download: ML25085A252 (1)
	v • d • e

VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA 23261 March 26, 2025 United States Nuclear Regulatory Commission Attention: Document Control Desk Washington, D. C. 20555 Serial No.

25-07 4 NAPS/RAP Docket Nos. 50-338, 339 License Nos. NPF-4, NPF-7 VIRGINIA ELECTRIC AND POWER COMPANY {DOMINION ENERGY VIRGINIA)

NORTH ANNA POWER STATION UNITS 1 AND 2

SUMMARY

OF FACILITY CHANGES, TESTS AND EXPERIMENTS Pursuant to 10 CFR 50.59(d)(2), a report containing a brief description of any changes, tests, and experiments, including a summary of the evaluation of each, must be submitted to the NRC, at intervals not to exceed 24 months. Attachment 1 provides a summary description of Facility Changes, Tests and Experiments identified in 10 CFR 50.59 Evaluations performed at the North Anna Power Station during 2024. Attachment 2 provides a summary description of Commitment Change Evaluations during 2024.

If you have any questions, please contact Marcus A. Hofmann at (540) 894-2100.

Lisa Hilbert Site Vice President Attachments

1. 10 CFR 50.59 Summary Description of Facility Changes, Tests and Experiments

2. Commitment Change Evaluation Summary cc:

Mark Miller - Region II NRC Senior Resident Inspector - North Anna Power Station

ATTACHMENT 1 10 CFR 50.59

SUMMARY

DESCRIPTION OF FACILITY CHANGES, TESTS AND EXPERIMENTS NORTH ANNA POWER STATION UNITS 1 AND 2 VIRGINIA ELECTRIC AND POWER COMPANY (DOMINION ENERGY VIRGINIA)

NORTH ANNA UNITS 1 AND 2 10 CFR 50.59

SUMMARY

DESCRIPTION OF FACILITY CHANGES, TESTS AND EXPERIMENTS 10 CFR 50.59 EVALUATION PARENT DOCUMENT: DC NA-20-00002, Rev. 3 Brief

Description:

The proposed activity, DC NA-2O-00002, replaces the existing non-safety related Hathaway Main Control Room (MCR) Annunciator system, Sequence of Events Recorder (SER), and backboard annunciator panels with a Westinghouse Ovation distributed Input/Output (1/0) system that is integrated into the existing Ovation Plant Computer System (PCS).

Reason for Change: The existing Main Control Room (MCR) Hathaway annunciator system, Sequence of Events Recorder (SER), independent backboard annunciator systems, and associated lightboxes in the MCR have been in service for the life of North Anna Power Station. These systems need to be replaced due to obsolescence and difficulty in adding new plant functionality.

Summary: The proposed activity will replace the existing Hathaway Main Control Room (MCR) Annunciator system, Sequence of Events Recorder (SER), and backboard annunciator panels with a Westinghouse Ovation distributed Input/Output (1/0) system.

The new annunciator system will be integrated into the Ovation Plant Computer System (PCS).

This annunciator system upgrade is being implemented due to equipment obsolescence issues and to support North Anna Power Station Subsequent License Renewal (SLR) activities.

A 50.59 Evaluation was determined to be required because the replacement annunciator system introduces new failure modes that do not exist with the existing annunciator system.

The following SAR-described design basis functions are impacted by the proposed activity:

DF The plant instrumentation and control system, including the MCR, as required by GDCs 13 and 19 DF The onsite power ~ystem as required by GDC-17 No methods of evaluation are impacted by implementation of the proposed change.

The 10 CFR 50.59 Evaluation concluded that the proposed activity:

Will not result in more than a minimal increase in frequency of occurrence of an accident previously evaluated in the SAR.

Will not result in more than a minimal increase in the likelihood of occurrence of a malfunction of an SSC important to safety previously evaluated in the SAR.

Will not result in more than a minimal increase in the consequences of an accident previously evaluated in the SAR.

Will not result in more than a minimal increase in the consequences of a malfunction of an SSC important to safety previously evaluated in the SAR.

Will not create a possibility for an accident of a different type than any previously evaluated in the SAR.

Will not create a possibility for a malfunction of an SSC important to safety with a different result than any previously evaluated in the SAR.

Will not result in a design basis limit for a fission product barrier as described in the SAR being exceeded or altered.

Will not result in departure from a method of evaluation described in the SAR used in establishing the design bases or in the safety analysis.

All evaluation criteria are answered NO.

As a result, this modification may be implemented without prior NRC review and approval.

10 CFR 50.59 EVALUATION PARENT DOCUMENT: DC NA-21-00066, Rev. 2 Brief

Description:

The proposed activity, Design Change (DC) NA-21-00066, replaces the existing North Anna Power Station (NAPS) analog-based 1st and 2nd Point Feedwater Heater (FWH) 1-FW-E-1 A, 1-FW-E-1 B, 1-FW-E-2A, and 1-FW-E-28 control system with an integrated digital control system [i.e., the Westinghouse Electric company (WEC) Ovation Distributed Control System (DCS), hereafter referred to as "Ovation DCS"] and replaces the existing analog valve controllers with Fisher Fieldvue TM DVC6200 Digital Valve Controllers (DVCs ). The Ovation DCS is a real-time plant monitoring and process control system, consisting of various interconnected components that monitor and control plant processes and equipment. These components are connected through a communication network to a Human Machine Interface (HMI) which operators can use to monitor and control plant processes and equipment installed by this DC.

To support this DC, two new WEC Ovation DCS cabinets are utilized. These new cabinets are installed by this DC in the turbine building basement. The two new Ovation DCS cabinets are equipped with the Ovation 1/0 controller modules and associated wiring required to support the changes to the level controls for the 1st and 2nd Point FWHs.

The 1st and 2nd Point FWH operator interface is impacted by this design change.

Although the functionality of the 1st and 2nd Point FWH soft controls is like that of the existing hard control devices, access is through a new HMI liquid crystal display (LCD) monitor, which can be tied to either Ovation DCS A or B. The existing 1st and 2nd Point FWH control system includes automatic and manual control capabilities which were located on platforms near each valve. This capability is maintained with the new system, which is upgraded to control the process automatically as well as manually from the field from the new control panel and HMI at floor level. Manual operation of the 1st and 2nd Point FWH is maintained for the operator to control the process manually via new HMI screens if needed. Existing 1st Point FWH normal and emergency drain, and 2nd Point FWH emergency drain, analog valve controllers are replaced with new remote mount Fisher DVCs which are controlled through the DCS.

The Hi-Lo Alarm Annunciator Tile indication for the 1st Point FWHs will be re-purposed to provide indication of an associated Ovation DCS experiencing trouble and will provide an alarm to the control room on a level transmitter issue (i.e., selection, out of service, FWH HI Level, FWH LO Level, LCV-SD-103A is placed out of service, or either or both LCV-SD-103A or LCV-SD-142A has a position feedback error). If any new subsequent condition occurs, the alarm will re-flash assuring operations personnel are aware of further FWH and/or DCS system issues.

Reason for Change: The existing 1st and 2nd point Feedwater Heaters (FWH) (1-FW-E-1 A/8 and 1-FW-E-2A/B) vessel pneumatic level controls (LC), and associated valve

positioners, are nearing their end of life and require replacement to support plant operation for the Period of Extended Operation (PEO) through the Subsequent License Renewal (SLR) Project.

Summary: Dominion Energy is seeking to extend North Anna Power Station (NAPS) plant operation under a Subsequent License Renewal (SLR). In support of this effort, the station requires a modernized control room and the digital infrastructure necessary to achieve that objective.

This design activity will replace the existing analog 1st and 2nd Point Feed Water Heater (FWH) analog control system with an integrated digital system. The change is considered an improvement to the station by replacing an analog control system with a new, highly reliable digital control system, [i.e., the Westinghouse Electric Company (WEC) Ovation Distributed Control System (DCS)]. The Ovation DCS is a real-time plant monitoring and process control system, consisting of various interconnected components that monitor and control plant processes and equipment. These components are connected through a communication network to Human Machine Interfaces (HMI) which operators can monitor and control plant processes and equipment in the field. The digital network infrastructure and common controls platform equipment needed to accommodate the integration of the Ovation DCS controllers is installed by this activity.

In addition, the proposed activity will replace the existing 1st and 2nd Point FWH analog valve controllers with Fisher DVCs.

Replacement of the 1st and 2nd Point FWH analog control system with a digital control system and migration of the 1st and 2nd Point FWH control onto the Ovation DCS network infrastructure introduces new failure modes within the 1st and 2nd Point FWH control system and plant instrumentation and control system that do not exist with the current systems. The new failure modes introduced result in an adverse impact on the design function of the FWH system and the plant instrumentation and control system.

As a result, aspects of the proposed activity screened in and required further evaluation against the eight 10 CFR 50.59 criteria.

The following SAR-described design functions are impacted by the proposed activity:

DF-1: 1st and 2nd Point Feed Water Heater (FWH)

The function of the 1st and 2nd Point Feedwater Heaters (FWH) is to provide heated water to the steam generators. UFSAR Section 15.2.10 credits the FWHs as an initiator of the Excessive Heat Removal Due to Feedwater System Malfunction event.

Consequently, FWH system, which includes the 1st and 2nd Point Feedwater Heaters, is classified as an accident initiator. Therefore, the function of the FWHs is a design function because it can initiate an accident or transient the plant is required to withstand.

DF-2: Plant Instrumentation and Control Systems and Main Control Room The instrumentation and controls impacted by the proposed activity are used by plant operators to monitor variables and systems over their anticipated ranges and are used to make operational decisions and to control various elements of the plant.

The plant instrumentation and control systems and the main control room have design basis functions because they are required by regulation (10 CFR 50 Appendix A). The instrumentation and controls impacted by the proposed activity support the design basis function of the plant instrumentation and control system and the main control room.

No methods of evaluation are impacted by implementation of the proposed change.