ND-23-0573, ITAAC Closure Notification on Completion of 2.4.02.02a (Index Number 497)

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ITAAC Closure Notification on Completion of 2.4.02.02a (Index Number 497)
ML23197A003
Person / Time
Site: Vogtle Southern Nuclear icon.png
Issue date: 07/16/2023
From: Coleman J
Southern Nuclear Operating Co
To:
Office of Nuclear Reactor Regulation, Document Control Desk
References
ITAAC 2.4.02.02a, ND-23-0573
Download: ML23197A003 (1)


Text

Jamie M. Coleman 7825 River Road Regulatory Affairs Director Waynesboro, GA 30830 Vogtle 3 & 4 706-848-6926 tel July 16, 2023 Docket No.: 52-026 ND-23-0573 10 CFR 52.99(c)(1)

U.S. Nuclear Regulatory Commission Document Control Desk Washington, DC 20555-0001 Southern Nuclear Operating Company Vogtle Electric Generating Plant Unit 4 ITAAC Closure Notification on Completion of 2.4.02.02a [Index Number 497]

Ladies and Gentlemen:

In accordance with 10 CFR 52.99(c)(1), the purpose of this letter is to notify the Nuclear Regulatory Commission (NRC) of the completion of Vogtle Electric Generating Plant (VEGP) Unit 4 Inspections, Tests, Analyses, and Acceptance Criteria (ITAAC) item 2.4.02.02a [Index Number 497]

which verifies the main turbine-generator trips after receiving a signal from the DAS, the main turbine-generator trips from an overspeed trip signal from the emergency and backup overspeed trip signals, and controls in the MCR operate to trip the main turbine-generator. The closure process for this ITAAC is based on the guidance described in NEI 08-01, Industry Guideline for the ITAAC Closure Process under 10 CFR Part 52, which was endorsed by the NRC in Regulatory Guide 1.215.

This letter contains no new NRC regulatory commitments. Southern Nuclear Operating Company (SNC) requests NRC staff confirmation of this determination and publication of the required notice in the Federal Register per 10 CFR 52.99.

If there are any questions, please contact Kelli Roberts at 706-848-6991.

Respectfully submitted, Jamie M. Coleman Regulatory Affairs Director Vogtle 3 & 4

Enclosure:

Vogtle Electric Generating Plant (VEGP) Unit 4 Completion of 2.4.02.02a [Index Number 497]

JMC/TJC/sfr

U.S. Nuclear Regulatory Commission ND-23-0573 Page 2 of 2 cc: Regional Administrator, Region ll Director, Office of Nuclear Reactor Regulation (NRR)

Director, Vogtle Project Office NRR Senior Resident Inspector - Vogtle 3 & 4

U.S. Nuclear Regulatory Commission ND-23-0573 Enclosure Page 1 of 4 Southern Nuclear Operating Company ND-23-0573 Enclosure Vogtle Electric Generating Plant (VEGP) Unit 4 Completion of ITAAC 2.4.02.02a [Index Number 497]

U.S. Nuclear Regulatory Commission ND-23-0573 Enclosure Page 2 of 4 ITAAC Statement Design Commitment 2.a) Controls exist in the MCR to trip the main turbine-generator.

2.c) The main turbine-generator trips after receiving a signal from the DAS.

3) The trip signals from the two turbine electrical overspeed protection trip systems are isolated from, and independent of, each other.

Inspections/Tests/Analyses Testing will be performed on the main turbine-generator using controls in the MCR.

Testing will be performed using real or simulated signals into the DAS.

ii) Testing of the as-built system will be performed using simulated signals from the turbine speed sensors.

Acceptance Criteria Controls in the MCR operate to trip the main turbine-generator.

The main turbine-generator trips after receiving a signal from the DAS.

ii) The main turbine-generator trips after overspeed signals are received from the speed sensors of the 110% emergency electrical overspeed trip system, and the main turbine-generator trips after overspeed signals are received from the speed sensors of the 111% backup electrical overspeed trip system.

ITAAC Determination Basis This ITAAC requires testing to be performed to verify that controls exist in the Main Control Room (MCR) and operate to trip the main turbine-generator and that the main turbine-generator trips after receiving a real or simulated signal from the Diverse Actuation System (DAS). This ITAAC also verifies the turbine electrical overspeed protection trip systems are isolated and independent of each other and that the main turbine-generator trips after receiving simulated trip signals from the emergency electrical overspeed trip system and the backup electrical overspeed trip system.

Controls in the MCR operate to trip the main turbine-generator.

Testing was performed in accordance with Unit 4 preoperational test procedure listed in Reference 1 to verify that controls in the MCR operate to trip the main turbine-generator.

Testing was initiated by resetting the main turbine, verifying the turbine is not tripped, and verifying the main turbine stop and control valves are open. The turbine trip hand switch at the Primary Dedicated Safety Panel (PDSP) was placed in trip, the turbine mode turbine trip display was verified, and the turbine stop and control valves were verified to be closed.

U.S. Nuclear Regulatory Commission ND-23-0573 Enclosure Page 3 of 4 This testing confirmed that for Unit 4, controls in the MCR operate to trip the main turbine-generator.

The main turbine-generator trips after receiving a signal from the DAS.

Testing was performed in accordance with Unit 4 preoperational test procedures listed in Reference 1 to verify the main turbine-generator trips after receiving a signal from the DAS.

Testing in reference 1 performed a trip solenoid valve functional test by verifying that when master trip pilot solenoids (TOS-V174A1/A2, TOS-V174B1/B2) were de-energized, the spool moved to the tripped position and the main turbine and extraction non-return valves were verified to close locally thereby tripping the main turbine. Testing in reference 1 verified the master trip pilot solenoids de-energize due to a DAS manual Reactor and Turbine Trip switch operation resulting in a signal from DAS to the main turbine-generator trip.

Results of the preoperational testing for Unit 4 confirmed that the main turbine-generator trips after receiving a signal from the DAS.

ii) The main turbine-generator trips after overspeed signals are received from the speed sensors of the 110% emergency electrical overspeed trip system, and the main turbine-generator trips after overspeed signals are received from the speed sensors of the 111% backup electrical overspeed trip system.

Testing was performed in accordance with Unit 4 preoperational test procedure listed in Reference 1 to verify the main turbine-generator tripped after overspeed signals were received from the speed sensors of the 110% emergency electrical overspeed trip system, and the main turbine-generator tripped after overspeed signals were received from the speed sensors of the 111% backup electrical overspeed trip system.

Testing in reference 1 performed a trip solenoid valve functional test by verifying when master trip pilot solenoids (TOS-V174A1/A2, TOS-V174B1/B2) were de-energized, the spool moved to the tripped position and the main turbine and extraction non-return valves were verified to close locally thereby tripping the main turbine. The test then simulated an overspeed condition at the speed sensors for the 110% emergency electrical overspeed trip and verified the trip solenoids were tripped. The test then simulated an overspeed condition at the speed sensors for the 111% backup electrical overspeed trip and verified the trip solenoids were tripped.

Results of the preoperational testing for Unit 4 confirmed that the main turbine-generator trips after overspeed signals are received from the speed sensors for the 110% emergency electrical overspeed trip system, and the main turbine-generator trips after overspeed signals are received from the speed sensors for the 111% backup electrical overspeed trip system.

The completed test results (Reference 1), confirm that that DAS controls exist in the MCR and operate to trip the main turbine-generator, that the main turbine-generator trips after receiving a real or simulated signal from the DAS, and that the main turbine-generator trips after receiving trip signals from the emergency electrical overspeed trip system and the backup electrical overspeed trip system.

Reference 1 is available for NRC inspection as part of Unit 4 ITAAC Completion Package (Reference 2).

U.S. Nuclear Regulatory Commission ND-23-0573 Enclosure Page 4 of 4 ITAAC Finding Review In accordance with plant procedures for ITAAC completion, Southern Nuclear Operating Company (SNC) performed a review of all findings pertaining to the subject ITAAC and associated corrective actions. This review found there are no relevant ITAAC findings associated with this ITAAC. The ITAAC completion review is documented in the ITAAC Completion Package for 2.4.02.02a (Reference 2) and is available for NRC review.

ITAAC Completion Statement Based on the above information, SNC hereby notifies the NRC that ITAAC 2.4.02.02a was performed for VEGP Unit 4 and that the prescribed acceptance criteria were met.

Systems, structures, and components verified as part of this ITAAC are being maintained in their as-designed, ITAAC compliant condition in accordance with approved plant programs and procedures.

References (available for NRC inspection)

1. SV4-MTS-ITR-800497, Rev. 0, Unit 4 Main Turbine-Generator MCR, DAS, and Overspeed Trip: ITAAC 2.4.02.02a, NRC Index Number: 497
2. 2.4.02.02a.i-U4-CP-Rev0, ITAAC Completion Package