Text

Westinghouse Electric Company Pre-Submittal of Presentation for Meeting to Discuss Design Certification Extension for AP1000
	ML21060B211
Person / Time
Site:	05200006
Issue date:	02/26/2021
From:	Harper Z; Westinghouse
To:	; Document Control Desk, Office of Nuclear Reactor Regulation
References
	LTR-NRC-21-8 Rev. 0
	Download: ML21060B211 (17)
	v • d • e

Westinghouse Electric Company Nuclear Power Plants 1000 Westinghouse Drive Cranberry Township, Pennsylvania 16066 USA U.S. Nuclear Regulatory Commission Direct tel: 412-374-3382 Document Control Desk e-mail: harperzs@westinghouse.com 11555 Rockville Pike Rockville, MD 20852-2738 Our ref: LTR-NRC-21-8 Rev. 0 February 26, 2021

Subject:

Pre-Submittal of Presentation for Meeting to Discuss Design Certification Extension for AP1000 Please find enclosed the non-proprietary presentation for the March 3rd public meeting related to the AP1000 Design Certification Extension.

Very truly yours, Zachary S. Harper Manager, Licensing Engineering

/Enclosures

1. APP-GW-GLY-187 Revision 1, Pre-Submittal Meeting AP1000 Design Certification Extension cc: Anna Bradford - U.S. NRC Bob Caldwell - U.S. NRC Michael Dudek - U.S. NRC Bruce Bavol - U.S. NRC Michael Corletti - Westinghouse Doug Weaver - Westinghouse

LTR-NRC-21-8 February 26, 2021 Page 1 of 16 ENCLOSURE 1 Pre-Submittal Meeting AP1000 Design Certification Extension

Pre-Submittal Meeting AP1000 Design Certification Extension 1

APP-GW-GLY-187 Rev. 1

Meeting Purpose & Agenda Purpose

Provide an overview of a planned Westinghouse submittal related to the AP1000 design certification extension

Receive and address NRC staff feedback Agenda

Background Information

Summary of the technical issues & resolution

Content & Scope of the submittal 2

APP-GW-GLY-187 Rev. 1

Background Information

By letter dated June 26, 2020 (ML20178A640), Westinghouse requested the NRC extend the duration of the AP1000 design certification (DC).

SECY-20-0082 (ML20252A153) recommended to extend the AP1000 DC an additional 5 years beyond the current expiration date of February 27, 2021 using the direct final rule process.

Staff Requirements Memorandum - SECY-20-0082 (ML20322A047) approved the recommendation.

3 APP-GW-GLY-187 Rev. 1

Background Information

In order to enable the NRC staff to make the necessary safety findings under 10 CFR 52.54, Westinghouse will be submitting information that resolves five previously identified technical issues within the AP1000 design certification.

These technical issues were resolved as part of the Levy, Lee, and Turkey Point AP1000 combined license (COL) applications, as well as the Vogtle 3&4 COL.

The purpose of the submittal is to update the certified design with the same design information that NRC previously approved as part of the COL process.

4 APP-GW-GLY-187 Rev. 1

Summary of the Technical Issues & Resolution

Details of the five previously identified & resolved technical issues can be found in the following Vogtle 3&4 documentation 5

APP-GW-GLY-187 Rev. 1

Summary of the Technical Issues & Resolution Condensate Return

SECY-94-084 recommended that passive reactor safety systems include a residual heat removal system capable of bringing the reactor to a safe shutdown condition of 420°F for non-loss of coolant accident events.

Per the AP1000 DCD, the Passive Core Cooling System (PXS) is capable of removing heat to the safe shutdown condition of 420°F in 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months .

Subsequent to design certification, changes were required to the containment gutter arrangement to support prolonged non-LOCA events to meet the DCD 420°F requirement.

In addition, the Shutdown Temperature Evaluation in Appendix 19E was updated to analyze the PRHR HX performance with the design modifications to confirm it meets its licensing basis performance criterion of cooling the RCS to 420°F within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months and maintaining a safe shutdown condition.

6 APP-GW-GLY-187 Rev. 1

Summary of the Technical Issues & Resolution MCR Heat Up

The emergency habitability system (VES) provides a 72-hour supply of breathable air for the occupants of the main control room (MCR).

The heat loads within the MCR are designed to limit the heat-up when VES is operating.

Subsequent to design certification, calculations found the MCR temperature response exceeded the current licensing basis maximum and equipment qualification conditions.

Therefore, an automatic and manual, Class 1E, electrical load shed of nonessential non-safety related equipment within the main control room was added that brought the design back into alignment with the licensing basis.

7 APP-GW-GLY-187 Rev. 1

Summary of the Technical Issues & Resolution MCR Dose

The AP1000 MCR operator dose requirements are met by the safety related MCR emergency habitability system VES.

Subsequent to design certification, calculations identified several issues associated with the VES that challenged the ability to satisfy GDC 19 control room dose limits.

Therefore, design changes were made to ensure personnel dose does not exceed 5 rem total dose equivalent (TEDE) for the duration of a design basis accident (DBA).

8 APP-GW-GLY-187 Rev. 1

Summary of the Technical Issues & Resolution Hydrogen Venting

The containment hydrogen control system (VLS) is designed promote hydrogen burning in the event of a severe accident. This occurs soon after the lower flammability limit is reached in the containment to provide confidence containment integrity is maintained.

During a beyond design basis event, hydrogen may be vented from the PXS compartments through openings in the floor where each Core Make-up Tank is located.

ITAAC provide a minimum distance between the primary hydrogen vent openings and the containment shell to ensure containment integrity.

Subsequent to design certification, a revised building and equipment layout was identified which led to revised ITAAC minimum distances.

An evaluation was performed to confirm that a diffusion flame hydrogen burn at the venting locations do not challenge containment integrity.

9 APP-GW-GLY-187 Rev. 1

Summary of the Technical Issues & Resolution PMS Logic Changes for Flux Doubling

IEEE 603-1991, imposes requirements on the operating bypasses (i.e., blocks and resets) used for the AP1000 PMS.

Subsequent to design certification, it was identified that the PMS functional logic for blocking the source range (SR) neutron flux doubling signal required revision to fully comply with the IEEE 603 Subclause 6.6 criteria. An operator could block flux doubling logic without an appropriate permissive.

Therefore, a new permissive was added to block the flux doubling signal during reactor startup, P-8.

- Above P-8, operators can control both control rods & boron concentration for reactivity adjustment.

- Below P-8, the safety system overrides isolation valves from the demineralized water system closed, preventing a boron dilution event.

- In addition, a reset of SR neutron flux doubling signal when RCS temperature decreases below the permissive was added.

10 APP-GW-GLY-187 Rev. 1

Content & Scope of the Submittal

The technical resolution of the five issues will align with the Vogtle 3&4 License Amendments

DCD markups and clean DCD pages will be provided for each issue

The submittal will reference the technical discussion provided in the Vogtle LARs

In nearly all cases, the DCD change pages will match the Vogtle LAR change pages verbatim

In limited instances, the DCD change pages will vary slightly from the Vogtle licensing basis change pages due to other Vogtle 3&4 departures impacting the same licensing basis content

- The technical design changes and the NRC bases for approval is not impacted because of these administrative differences

- Examples are provided on the following two slides 11 APP-GW-GLY-187 Rev. 1

Content & Scope of the Submittal Example 1 - Vogtle 3&4 Tech Spec Upgrade

Prior to the submittal of the five Vogtle LARs, a Tech Spec Upgrade LAR was approved and implemented

The Tech Spec Upgrade implemented administrative changes and rearranged many Tech Specs, including the ESFAS Tech Spec

These upgrades do not constitute a significant error in the DCD; therefore, it is not being implemented at this time

Since the Tech Spec Upgrade is not implemented, the DCD Tech Spec change pages associated with some of these five issues will look similar to the Levy, Lee, and Turkey Point Tech Spec change pages 12 APP-GW-GLY-187 Rev. 1

Content & Scope of the Submittal Example 2 - Vogtle 3&4 departures

Prior to the submittal of the five Vogtle LARs, departures were implemented into the Vogtle licensing basis

In order to stay as consistent as possible with the Vogtle LAR change pages, some minor changes from other Vogtle departures will be included in the DCD change pages

These changes will be identified and discussed in the submittal 13 APP-GW-GLY-187 Rev. 1

Content & Scope of the Submittal Topical Reports

The MCR Heat-up change has a small impact on DCD Chapter 7 incorporated by reference Topical Reports

The submittal will contain change pages for DCD Chapter 7A, similar to the Vogtle LAR

An affidavit will be submitted for these Chapter 7A changes 14 APP-GW-GLY-187 Rev. 1

Questions 15 APP-GW-GLY-187 Rev. 1

ML21060B211

Text

Subject:

Navigation menu

Search