ML25325A150
| ML25325A150 | |
| Person / Time | |
|---|---|
| Site: | 99902079 |
| Issue date: | 12/09/2025 |
| From: | Vechioli-Feliciano L NRC/NRR/DANU/UAL2 |
| To: | Westinghouse |
| Vechioli-Feliciano L | |
| Shared Package | |
| ML25325A152 | List: |
| References | |
| Download: ML25325A150 (5) | |
Text
Enclosure December 9, 2025 OFFICE OF NUCLEAR REACTOR REGULATION REGULATORY AUDIT REPORT ADVANCED LOGIC SYSTEM V 2 PLATFORM ELIMINATION OF TECHNICAL SPECIFICATION SURVEILLANCE REQUIREMENTS TOPICAL REPORT WESTINGHOUSE ELECTRIC COMPANY, LLC.
DOCKET NO. 99902079
1.0 BACKGROUND
By letter dated December 20, 2023 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23354A139) Westinghouse Electric Company LLC.,
(Westinghouse) submitted Revision 0 of topical report (TR) WCAP-18810-P/NP, Advanced Logic System (ALS) v2 Platform Elimination of Technical Specification Surveillance Requirements, (ML23354A138) to the U.S. Nuclear Regulatory Commission (NRC) staff for review. The TR proposes a methodology to eliminate certain Technical Specification (TS)
Surveillance Requirements (SRs) from the ALS v2 platform. On February 16, 2024, the NRC staff found that the material presented in the TR provides technical information in sufficient detail to enable the NRC staff to conduct their technical review and issued their completeness determination (ML24043A243).
Westinghouse requested the NRC staffs review and approval of this TR for use by future applications referencing Title 10 of the Code of Federal Regulations (10 CFR) Part 50, Domestic Licensing of Production and Utilization Facilities (Reference 4), Section 36, Technical specifications. Specifically relating to the safety system of a nuclear plant is 10 CFR 50.36(c)(ii)(A), which establishes limiting safety system settings for nuclear reactors.
The NRC staff provided its audit plan for the subject TR to Westinghouse via the shared electronic reading room (eRR) and later sent the audit plan via e-mail on February 18, 2025 (ML25101A298). The audit kick-off meeting was held on March 3, 2025, using Westinghouses eRR.
2.0 AUDIT PURPOSE AND ACTIVITIES The purpose of the audit was for the NRC staff to gain a more detailed understanding of the ALS v2 platform, the elimination of its TS surveillance requirements, and the applicable regulations, standards, guidelines, plans, and procedures. The NRC staff also reviewed supporting documentation to identify any information that will require docketing to support the NRC staffs safety evaluation.
The audit followed the guidance in the Office of Nuclear Reactor Regulation, Office Instruction LIC-111, Revision 2, Regulatory Audits (ML24309A281). Audit activities included virtual meetings to discuss questions, the review of files shared via email and the eRR, and code demonstrations via videoconference.
Members of the audit team are listed below:
William Roggenbrodt, Division of Engineering and External Hazards, Instrumentation and Controls Branch Tarico Sweat, Division of Safety Systems, Technical Specifications Branch Lucieann Vechioli, Division of Advanced Reactors and Non-power Production and Utilization Facilities (DANU), Advanced Reactor Licensing Branch 2 (UAL2)
Patrick Boyle, DANU, UAL2 Michelle Vega, DANU, UAL2 Throughout the audit, the NRC staff submitted additional audit questions beyond those included in the audit plan (ML25220A089 and ML25220A152).
During the audit, the NRC staff reviewed supporting documentation to determine if the docketing of additional information was required to develop and support any conclusions for the NRC staffs safety evaluation of the TR. Westinghouse added the following documents in the eRR for the NRC staff to review:
Westinghouse, 6003-00033, Advanced Logic System (ALS) v2 Self-Diagnostic Functionality, Revision 2, December 2023.
Westinghouse, 6003-35212, ALS-352 FPA, FMEA and Reliability Analysis, Revision 0, December 2023.
Westinghouse, 6003-15212, ALS-152 FPA, FMEA and Reliability Analysis, Revision 0, November 2023.
Westinghouse, 6003-36112, ALS-361 FPA, FMEA and Reliability Analysis, Revision 1, November 2023.
Westinghouse, 6003-47112, ALS-471 FPA, FMEA and Reliability Analysis, Revision 0, November 2023.
Westinghouse, 6003-65112, ALS-651 FPA, FMEA and Reliability Analysis, Revision 1, December 2023.
Westinghouse, 6003-45212, ALS-452 FPA, FMEA and Reliability Analysis, Revision 0, November 2023.
Westinghouse, 6003-37112, ALS-371 FPA, FMEA and Reliability Analysis, Revision 0, November 2023.
Westinghouse, 6003-85312, ALS-853 FPA, FMEA and Reliability Analysis, Revision 1, December 2023.
Westinghouse, 6003-85212, ALS-852 FPA, FMEA and Reliability Analysis, Revision 1, December 2023.
Westinghouse, 6003-85012, ALS-850 FPA, FMEA and Reliability Analysis, Revision 0, December 2023.
Westinghouse, Comparative Table Describing Current Phase of System Development for Each Board, Daughter Card, and Any Other System Component.
Vishay, Professional Thin Film MELF Resistors - MMU 0102, MMA0204, MMB 02047.
Vishay Intertechnology, Inc., Drift Calculation for Thin Film Resistors.
KEMET Charged, Ceramic Capacitor Aging: What to Expect.
Vishay Foil Resistors, Ultra High Precision Foil Wraparound Surface Mount Chip Resistor - VSMP Series (0603,0805,1206,1506,2010,2512) Z Foil.
Ultra-High Precision Foil Wraparound Surface Mount Chip Resistor - VSMP Series (0603,0805,1206,1506,2010,2512) (Z Foil).
Vishay, Vishay Material Category Policy, Document No 99912, Revision 22 - March -
2013.
Westinghouse, 6003-00033, Advanced Logic System (ALS) v2 Self-Diagnostics Functionality, Revision 3, July 2025.
As a result of the audit, the NRC staff identified information required to make a safety determination for the TR. Consequently, Westinghouse docketed the following supporting document:
Westinghouse, 6003-00033, Advanced Logic System (ALS) v2 Self-Diagnostics Functionality, Revision 3, July 2025 (ML25206A263).
On November 24, 2025, the NRC staff held an audit exit meeting with Westinghouse. The purpose of the exit meeting was to discuss the audit report which summarized the audit findings, the documents that were reviewed and the closure path of the audit. The meeting also provided an opportunity to clarify any issues related to the audit results.
3.0
SUMMARY
OF OBSERVATIONS As indicated in the NRC staffs audit plan, the audit was focused on clarification of and needed justification for information in the TR that specifically concerns the proposed alternative for certain TS Surveillance Requirements based on automatic self-diagnostic capabilities. The topics during the audit addressed technical, regulatory, and process details about system diagnostics, reliability, verification and validation (V&V), design process, and regulatory compliance. The audit included but was not limited to:
Self-Diagnostics Functionality: both the operational what and how ALS v2 self-diagnostics function.
Test Coverage and Definitions: discussion regarding the discrepancies between the ALS definitions and NUREG-1431, Standard Technical Specifications Westinghouse Plants, standard definitions for surveillance testing (e.g., Channel Operational Test, Actuation Logic Test, Channel Check).
Surveillance Program Applicability: discussion about whether self-diagnostics can be credited in lieu of manual surveillance tests, referencing NRC precedents and regulatory bases.
Safe State Behavior: how the ALS v2 system responds to detected errors and transitions output boards to configurable safe states.
V&V: details about the concurrent design and independent validation of self-diagnostics per NRC-approved processes (WCAP-18780, WNA-PV-00129-GEN).
Failure Detection and Corrective Actions: discussion about diagnostic failures, including use of Corrective Action Programs (CAP) and 10 CFR Part 21, Reporting of Defects and Noncompliance, evaluations.
Diagnostic Implementation Details: clarification on specific board-level and platform-level diagnostic features, including Field-Programmable Gate Array redundancy checks and non-volatile memory (NVM) cyclic redundancy check (CRC) validations.
Reliability Analyses: outlines methods and documentation for hardware reliability (mean time between failure) calculations (e.g., RIAC 217 Plus), noting the absence of the deployed ALS v2 systems and limited operational reliability data.
Regulatory Compliance: discussion about applicable regulations and guidance (e.g.,
Generic Design Criteria 13, Instrumentation and Control; Regulatory Guide 1.152, Criteria for Programmable Digital Devices in Safety-Related Systems of Nuclear Power Plants; Institutes of Electrical and Electronics Engineering Standard 1012-2004, Software Verification and Validation; and Regulatory Issue Summary 2016-05, Embedded Digital Devices in Safety-Related Systems).
In addition, during the audit it was noted that the ALS v2 self-diagnostics have not yet undergone full integration testing or independent verification and validation (V&V) and that the ALS v2 platform has not been deployed in nuclear power plant applications to date. The reliability estimates are based on component analysis, not on operational history.
During the audit exit meeting, the NRC staff informed Westinghouse that the NRC staff intends to impose limitations and conditions in the SE. Any licensee or applicant referring to the TR must address its limitations and conditions.
4.0 REQUESTS FOR ADDITIONAL INFORMATION RESULTING FROM THE AUDIT As a result of the audit, the NRC staff determined that no requests for additional information related to this TR were necessary.
5.0 CLOSURE PATH Westinghouse confirmed that the following TR revisions that were agreed to during the audit will be reflected in the -A version of the TR:
Figure 5-1, ALS Platform Self-Testing revision: Westinghouse will revise figure 5-1 in the TR to accurately depict the starting point of Channel Operational Test at the Actuation Logic Test Input Board.
Update to Regulatory Applicability: Westinghouse will add GDC 13 to the applicable regulation list in the TR.