ND-23-0365, ITAAC Closure Notification on Completion of ITAAC 2.2.03.08b.01 (Index Number 175)

ITAAC Closure Notification on Completion of ITAAC 2.2.03.08b.01 (Index Number 175)

ML23143A330
Person / Time
Site:	Vogtle
Issue date:	05/23/2023
From:	Coleman J Southern Nuclear Operating Co
To:	Office of Nuclear Reactor Regulation, Document Control Desk
References
ND-23-0365
Download: ML23143A330 (1)

Text

Jamie M. Coleman 7825 River Road Regulatory Affairs Director Waynesboro, GA 30830 Vogtle 3 & 4 706-848-6926 tel May 23, 2023 Docket No.: 52-026 ND-23-0365 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 ITAAC 2.2.03.08b.01 [Index Number 175]

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 2.2.03.08b.01 [Index Number 175]. This ITAAC verified that the PRHR Heat Exchanger could remove core decay heat during design basis events. 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 is 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 ITAAC 2.2.03.08b.01 [Index Number 175]

JMC/PCM/sfr

U.S. Nuclear Regulatory Commission ND-23-0365 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-23-0365 Enclosure Page 1 of 3 Southern Nuclear Operating Company ND-23-0365 Enclosure Vogtle Electric Generating Plant (VEGP) Unit 4 Completion of ITAAC 2.2.03.08b.01 [Index Number 175]

U.S. Nuclear Regulatory Commission ND-23-0365 Enclosure Page 2 of 3 ITAAC Statement Design Commitment 8.b) The PXS provides core decay heat removal during design basis events.

Inspections/Tests/Analyses

1. A heat removal performance test and analysis of the PRHR HX will be performed to determine the heat transfer from the HX. For the test, the reactor coolant hot leg temperature will be initially at 350°F with the reactor coolant pumps running. The IRWST water level for the test will be above the top of the HX. The test will continue until the hot leg temperature is 250°F.

Acceptance Criteria

1. A report exists and concludes that the PRHR HX heat transfer rate with the design basis number of PRHR HX tubes plugged is:

8.46 x 107 Btu/hr with 250°F HL Temp and an initial IRWST temperature of 80°F.

The heat transfer rate measured in the test should be adjusted to account for differences in the HL and IRWST temperatures and the number of tubes plugged.

ITAAC Determination Basis Multiple ITAAC are performed to confirm the Passive Core Cooling System provides core decay heat removal during design basis events by testing and analysis of the Passive Residual Heat Removal (PRHR) Heat Exchanger (HX) subsystem to determine the heat transfer from the PRHR HX. The Reactor Coolant System (RCS) hot leg temperature will be initially 350°F with the Reactor Coolant Pumps (RCPs) running. The In-containment Refueling Water Storage Tank (IRWST) water level for the test will be above the top of the PRHR HX, and the test will continue until the hot leg (HL) temperature is 250°F.

The testing was performed in accordance with Unit 4 Work Order and Preoperational test procedure as documented in Reference 1 during Hot Functional Testing with the RCS at 350°F, and the IRWST level was verified to be above the PRHR HX. The RCPs were verified to be running and the test was initiated by opening one of the PRHR HX outlet valves. RCS temperature was monitored, and the PRHR HX outlet valve was closed when temperature decreased to 250°F. PRHR HX inlet temperature, RCS hot leg and cold leg temperatures, IRWST temperature and PRHR HX flow were trended during the test, and this information was provided to engineering to perform the heat transfer rate calculations.

As the actual test conditions differ from the assumptions originally used to develop the ITAAC acceptance criteria of 8.46 x 107 Btu/hr, the heat transfer rate calculated using the UFSAR Chapter 15 LOFTRAN safety analysis code model was adjusted to account for differences in the initial conditions for the test. This adjustment of the acceptance criteria using the LOFTRAN model is necessary to ensure a relevant, conservative comparison of the test results to the heat transfer rates predicted for the test using the LOFTRAN code.

U.S. Nuclear Regulatory Commission ND-23-0365 Enclosure Page 3 of 3 The as-tested performance of the PRHR HX subsystem yielded a heat transfer rate of 9.7632x107 Btu/hr. The equivalent calculation using the conservative LOFTRAN model yielded a heat transfer rate of 8.4622x107 Btu/hr. As stated in Reference 2, this comparison clearly demonstrates that the actual PRHR HX subsystem performance exceeds that predicted in the LOFTRAN model at the as-tested conditions. As the test performed demonstrates that the PRHR HX subsystem meets its design basis, it can be concluded that the PRHR HX subsystem would also meet the heat transfer capability at the safety analysis conditions associated with the 8.46x107 Btu/hr value in the ITAAC acceptance criteria. As such, this ITAAC is determined to be met.

References 1 and 2 are available for NRC inspection as part of the ITAAC 2.2.03.08b.01 Completion Package (Reference 3).

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 ITAAC 2.2.03.08b.01 (Reference 3) and is available for NRC review.

ITAAC Completion Statement Based on the above information, SNC hereby notifies the NRC that ITAAC 2.2.03.08b.01 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-PXS-ITR-800175, Rev. 0, Unit 4 Recorded Results of PRHR Heat Exchanger Heat Transfer Rate Test: ITAAC 2.2.03.08b.01

2. SV4-PXS-T2R-011, Rev. 0, Vogtle Unit 4 PXS Hot Functional Test Results Validation for PRHR Performance Summary Report

3. 2.2.03.08b.01-U4-CP-Rev0, ITAAC Completion Package