ML25344A042

Final Safety Evaluation by the Office of Nuclear Reactor Regulation for Mitsubishi Electric Corporations Topical Report, Revision 3 Mitsubishi Electric Total Advanced Controller Platform - Meltac (EPID L-2023-TOP-0036) - Non-Proprietary

ML25344A042
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Issue date:	01/21/2026
From:	James Smith Licensing Processes Branch
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EPID L-2023-TOP-0036
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OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION FINAL SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION FOR MITSUBISHI ELECTRIC CORPORATIONS TOPICAL REPORT, REVISION 3 MITSUBISHI ELECTRIC TOTAL ADVANCED CONTROLLER PLATFORM - MELTAC PHASE 1 DOCKET NO. 99902039 EPID L-2023-TOP-0036

1.

INTRODUCTION By \

letter dated June 16, 2023, (Ref. 1), as supplemented by letters dated March 15, 2024 (Ref. 2), April 25, 2024 (Ref. 3), and May 16, 2024 (Ref. 4), the Mitsubishi Electric Corporation (MELCO) submitted to the U.S. Nuclear Regulatory Commission (NRC), topical report (TR)

JEXU-1041-1008-P/NP, Revision 3 (Rev. 3), titled the Mitsubishi Electric Total Advanced Controller (MELTAC) Platform Safety System Digital Platform - MELTAC - Topical Report (Ref. 5), hereafter referred to as Rev. 3 of the TR, for NRC staff review and approval.

Additionally, by letters dated March 15, 2024 (Ref. 7), July 31, 2024 (Ref. 8), August 23, 2024 (Ref. 9), and November 12, 2024 (Ref. 11), MELCO submitted supplemental information in its responses to NRC staffs requests for additional information (RAIs) dated January 19, 2024 (Ref. 6), July 31, 2024 (Ref. 8), and October 23, 2024 (Ref. 10). On December 23, 2024 (Ref. 12), the NRC staff sent a revised schedule to MELCO agreeing to accept the supplemental information as part of the NRC staffs ongoing review of Rev. 3 of the TR.

The purpose of Rev. 3 of the TR is to describe updates to MELCOs MELTAC platform and provide the digital platforms applicability to meet NRC regulations. This safety evaluation (SE) provides a summary of the NRC staffs review and its evaluation of the MELTAC Platform in Rev. 3 of the TR. The NRC staff performed its review based on, in part, a comparison of the MELTAC Platform in Rev. 3 of the TR to the previously approved version in Rev. 2 of the TR (Ref. 13).

2.

BACKGROUND AND SCOPE OF THE REVIEW The NRC staffs review of Rev. 3 of the TR evaluates the MELCO MELTAC platform for its general applicability in nuclear power plant safety systems in accordance with NRC regulations.

The MELTAC platform is a computer-based programmable-logic controller (PLC) system which comprises a predefined set of hardware and software components developed for nuclear applications. The MELTAC platform uses both microprocessor and field-programmable gate array (FPGA) technologies and is configured with plant-specific application software to implement plant safety system functions.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION In April of 2014, MELCO submitted to the NRC staff the previous version of the MELTAC Platform in Rev. 2 of the TR and the NRC staff evaluated the platform for its general applicability in nuclear power plant safety systems in accordance with NRC regulations. In May 2019, the NRC staff approved the MELTAC Platform in Rev. 2 of the TR, with specific limitations and conditions as defined in Section 5.0 of its associated SE (Ref. 13).

On May 10, 2023, the NRC staff held a pre-submittal meeting (Ref. 14) to discuss the MELTAC Platform in Rev. 3 of the TR, during which MELCO proposed a two-phased review process for the NRC staffs evaluation (known as Phase 1 and Phase 2 to take place in sequential order). In June of 2023, MELCO submitted the MELTAC Platform in Rev. 3 of the TR (Ref. 5), along with additional supporting documents (Refs. 3 and 4), to the NRC staff for its Phase 1 review. In Section 2.2 of this SE, Table 1, entitled, Documents Submitted to Support the Review of the MELTAC Platform in Revision 3 of the Topical Report, provides a list of all the documents and their corresponding reference numbers that were used to support the NRC staffs evaluation of Rev. 3 of the TR.

On January 19, 2024, the NRC staff issued several RAIs. MELCO responded to these RAIs in March 2024 (Ref. 7), as listed in Table 1. For three of the supporting documents submitted in 2024 (Ref. 3, 4, and 21), the NRC staff issued additional RAIs in October 2024 (Ref. 10) and MELCO provided responses to these RAIs in November 2024 (Ref. 11) which are also identified in Table 1.

MELCO introduces several significant changes to the MELTAC Platform in Rev. 3 of the TR requiring NRC staff evaluation, however, the fundamental architecture and main design principles of the MELTAC platform remain consistent with those previously approved. This SE focuses exclusively on the changes introduced in Rev. 3 of the TR and not the areas of the MELTAC Platform in Rev. 3 of the TR that remain the same as in Rev. 2 of the TR. Accordingly, this SE is intended to be used in conjunction with the SE for the approved Rev. 2 of the TR for the MELTAC platform.

2.1 Scope of the NRC Staff Review The NRC staffs review of Rev. 3 of the TR included consideration of the guidance in NRCs Digital Instrumentation and Controls Interim Staff Guidance (DI&C-ISG)-06, Licensing Process, Rev. 2, dated December 2018 (Ref. 28), which defines the licensing process used to support the review of license amendment requests and TR approvals associated with safety related digital instrumentation and controls (DI&C) equipment modification.

As mentioned above, the NRC staff agreed to support a two-phased review process for the review of Rev. 3 of the TR as follows:

Phase 1: NRC staffs review of Rev. 3 of the TR, as limited in this SE, and supporting documents shown in Table 1 of Subsection 2.2 of this SE. This includes review of the MELTAC platform software, new excore instrumentation units, changes to the power interface module, changes to the self-diagnostic capabilities, and expanded use of the control network.

Phase 2: After completion of the Phase 1 review, NRC staff plans to review forthcoming MELCO submittals to support the Phase 2 review of Rev. 3 of the TR. During the writing of this SE, the NRC staff understands that as a part of Phase 2, MELCO

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION plans to submit additional detailed design information, including the MELTAC platform software safety analysis, equipment qualification (EQ) test specification, EQ testing reports, and other supporting documentation (Ref. 14). The review of this information is necessary to complete the overall review and approval of the MELTAC Platform in Rev. 3 of the TR. This is discussed in Generic Open Item 6.1.4.

Since the NRC staff has previously approved the MELTAC Platform in Rev. 2 of the TR for use in safety DI&C systems for U.S. nuclear power plants, the Phase 1 review in this SE provides the NRC staffs evaluation considering only documents listed for the Phase 1 review in Table 1, which support the changes made to Rev. 2 of the TR and these changes are described in Section 4.2 of this SE. The NRC staff notes that Section 2.0 of the NRC staffs SE for Rev. 2 of the TR outlines the applicable regulatory bases, guidance, and acceptance criteria used by the NRC staff in its evaluation of the MELTAC Platform in Rev. 2 of the TR. Unless updated or superseded, the regulatory guidance and criteria used in the SE of Rev. 2 of the TR remain applicable to the Phase 1 review of Rev. 3 of the TR.

Since the MELTAC Platform in Rev. 3 of the TR does not include a plant-specific application, this Phase 1 review is limited to evaluating compliance with applicable regulatory requirements and guidance at the platform level. System-level requirements can only be partially assessed through a generic review based on the platforms inherent features and capabilities.

Accordingly, the limitations, conditions, and open items outlined in Section 6.0 of this SE and Section 5.0 of the NRC staffs SE in Rev. 2 of the TR must be addressed by any applicant or licensee when referencing the MELTAC Platform in Rev. 3 of the TR for safety-related applications.

The conclusions reached in this SE regarding compliance with applicable regulations and guidance are subject to application-specific licensing reviews of complete system designs that implement the MELTAC Platform in Rev. 3 of the TR. To support forthcoming reviews, generic open items, plant-specific action items (PSAIs), and conditions have been identified in Subsections 6.1 and 6.2 of this SE and similarly in Subsections 5.1 and 5.2 of the SE for the MELTAC Platform in Rev. 2 of the TR. These items identify specific criteria that must be addressed by applicants or licensees to demonstrate full compliance with the acceptance criteria in Standard Review Plan (SRP) Chapter 7, Table 7.1, Regulatory Requirements, Acceptance Criteria, and Guidelines for I&C [instrumentation and control] Systems Important to Safety, and applicable regulatory requirements in 10 CFR Part 50, effective at the time of this review.

The NRC staff notes that forthcoming applications that plan to reference Rev. 3 of the TR, should not exclusively rely on this Phase 1 SE, but must also consider the NRC staff conclusions that will be provided in the Phase 2 SE, and in addition, any separate SEs that supports the changes to the MELTAC platform as part of Rev. 3 of the TR should be considered before referencing. It is also important to note that the identified generic open items, PSAIs, and conditions do not relieve applicants or licensees from the responsibility to address any newly applicable or revised regulatory requirements or acceptance criteria that may be in effect at the time of their plant-specific application submittals.

The two documents bulleted below are outside the scope of this SE for the Phase 1 review and, as requested by MELCOs transmittal \

letter dated July 7, 2023 (Ref. 24), will not be addressed

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Section 4.0 of this SE provides a summary of the proposed changes introduced for the MELTAC Platform in Rev. 3 of the TR, followed by the NRC staffs evaluation of the information for the Phase 1 review relative to MELTAC Platform in Rev. 2 of the TR.

Section 5.0 of this SE presents the NRC staffs summary and conclusions on the evaluation of the information for the Phase1 review of the MELTAC Platform in Rev. 3 of the TR.

Section 6.0 of this SE outlines the limitations and conditions that must be addressed by MELCO and applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR for specific safety-related applications in U.S. nuclear power generating stations.

Section 7.0 of this SE provides a list of references cited throughout this SE.

Section 8.0 of this SE provides a list of acronyms used throughout or relevant to this SE.

3.

REGULATORY EVALUATION The regulations and guidance relevant to the Phase 1 review of Rev. 3 of the TR are summarized below.

10 CFR 50.55a, Codes and standards, (h), incorporates the IEEE Std. 603-1991, Criteria for Safety Systems for Nuclear Power Generating Stations.

10 CFR Part 50, Appendix A, General Design Criteria for Nuclear Power Plants.

General Design Criterion (GDC) 1, Quality standards and records GDC 2, Design bases for protection against natural phenomena GDC 4, Environmental and dynamic effects design bases GDC 19, Control room GDC 21, Protection system reliability and testability GDC 23, Protective system failure modes GDC 24, Separation of protection and control systems 10 CFR Part 50, Appendix B, Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants.

NUREG-0800, Standard Review Plan (SRP) Chapter 7, Appendix 7.1-C, Guidance for Evaluation of Conformance to IEEE Std. 603.

SRP Chapter 7, Table 7.1, Regulatory Requirements, Acceptance Criteria, and Guidelines for I&C Systems Important to Safety, outlines the design criteria and regulatory requirements from Title 10 Code of Federal Regulations (10 CFR) Part 50 applicable to I&C systems. These criteria serve as the basis for evaluating the suitability of a DI&C platform for use in nuclear safety-related applications. Many of the review criteria in SRP Chapter 7 depend on the specifics of a fully integrated system design tailored to a particular application. However, the MELTAC Platform in Rev. 3 of the TR focuses on hardware components and basic system software that can support a range of safety-related uses.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Regulatory Guide (RG) 1.152, Rev. 4, Criteria for Programmable Digital Devices in Safety-Related Systems of Nuclear Power Plants, which endorses (with some exceptions and clarifications) IEEE Std. 7-4.3.2-2016, describes an approach that is acceptable to NRC staff to meet regulatory requirements for promoting high functional reliability, design quality, and a secure development and operational environment (SDOE) for the use of programmable digital devices (PDDs) in the safety-related systems of nuclear power generating stations. This RG was issued shortly after MELCO submitted the MELTAC Platform in Rev. 3 of the TR for NRC staff review. Therefore, MELCO submitted two supporting documents shown in Table 1 (Refs. 3 and 21) to demonstrate that the MELTAC Platform in Rev. 3 of the TR is in conformance with the updated regulatory guidance in RG 1.152, Rev. 4 and its endorsed IEEE Std. 7-4.3.2-2016.

RG 1.29, Rev. 6, Seismic Design Classification for Nuclear Power Plants, which describes a method that the NRC staff considers acceptable for use in identifying and classifying those features of light-water reactor nuclear power plants that must be designed to withstand the effects of the safe-shutdown earthquake.

RG 1.89, Rev. 2, Environmental Qualification of Certain Electronic Equipment Important to Safety for Nuclear Power Plants, which endorses (with clarifications) IEC/IEEE Std.

60780-323-2016, describes a method acceptable to the NRC staff for complying with the NRCs regulations as they apply to qualification of electric equipment important to safety for service in nuclear power plants to ensure that the equipment can perform its safety function during and after a design basis accident.

RG 1.97, Rev. 5, Criteria for Accident Monitoring Instrumentation for Nuclear Power Plants, which endorses (with exceptions and clarifications) IEEE Std. 497-2016, describes a method acceptable to the NRC staff for providing instrumentation to monitor variables for accident conditions.

RG 1.100, Rev. 4, Seismic Qualification of Electrical and Active Mechanical Equipment and Functional Qualification of Active Mechanical Equipment for Nuclear Power Plants, which endorses IEEE Std. 344-2013, describes a method acceptable to the NRC staff for satisfying the seismic qualification.

RG 1.105, Rev. 4, Setpoints for Safety Related Instrumentation, describes a method acceptable to the NRC staff for complying with the NRCs regulations for ensuring that setpoints for safety-related instrumentation are initially within and remain within the technical specification limits.

RG 1.164, Rev. 1, Dedication of Commercial-Grade Items for Use in Nuclear Power Plants, describes the methods that the NRC staff considers acceptable in meeting regulatory requirements for dedication of commercial-grade items and services used in nuclear power plants.

RG 1.168, Rev. 2, Verification, Validation, Reviews, and Audits for Digital Computer Software Used in Safety Systems of Nuclear Power Plants, describes a method the NRC staff considers acceptable for use in complying with NRC regulations with respect to verification, validation, reviews, and audits for digital computer software used in safety systems of nuclear power plants.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION RG 1.180, Rev. 2, Guidelines for Evaluating Electromagnetic and Radio Frequency Interference in Safety Related Instrumentation and Control Systems, which describes a method acceptable to the NRC staff for design, installation, and testing practices to address the effects of electromagnetic and radio frequency interference (EMI/RFI) and power surges on safety-related I&C systems. This revised RG 1.180 endorses MIL-STD-461G,Requirements for the Control of Electromagnetic Interference Characteristics of Subsystems and Equipment, IEC 61000 Parts 3, 4, and 6, IEEE Std. C62.41.1-2002, C62.41.2-2002, IEEE Std. C62.45-2002, and IEEE Std. 1050-2004.

RG 1.209, Rev. 0, Guidelines for Environmental Qualification of Safety-Related Computer-Based Instrumentation and Control Systems in Nuclear Power Plants, describes a method that the NRC staff considers acceptable for determining the environmental qualification procedures for safety-related computer-based I&C systems for service within nuclear power plants.

DI&C-ISG-06 [Interim Safety Guidance], Rev. 2 (Ref. 28), describes the licensing process that may be used in the review of license amendment requests associated with safety-related DI&C system modifications in operating plants originally licensed under 10 CFR Part 50. The ISG-06 describes how the staff needs to review DI&C equipment to determine whether it meets the requirements of IEEE Std 603-1991.

4.

TECHNICAL EVALUATION 4.1 Overview of the Topical Report of Revision 3 of the MELTAC Safety System Digital Platform (JEXU-1041-1008-P)

Subsections 4.1 and 4.2 of this SE identify and describe the proposed technical changes included in the MELTAC Platform in Rev. 3 of the TR. Subsection 4.3 of this SE contains the NRC staffs evaluation of those changes and the processes used to develop them in accordance with the regulatory evaluation criteria identified in Section 3.0 of this SE.

MELCOs Rev. 3 to the TR, entitled, Safety System Digital Platform - MELTAC - Topical Report, covers the following major topics:

Section 1.0 of Rev. 3 to the TR discusses its Purpose which describes the MELTAC platform and its conformance to the NRC regulations for nuclear safety-related systems. Section 2.0 of Rev. 3 to the TR presents the Scope of the report which includes the hardware, software, and components associated with the MELTAC platform. Section 3.0 of Rev. 3 to the TR identifies conformance to applicable codes, standards, and regulatory guidance in NUREG 0800 and ISG-06. Section 4.0 of Rev. 3 to the TR provides a detailed description of the MELTAC platform.

Section 5.0 of Rev. 3 to the TR presents environmental, seismic, electromagnetic and isolation qualification. Section 6.0 discusses the QA and life cycle. Section 7.0 provides insights on the equipment reliability.

4.1.1.

System Background and Compliance with NRC Regulations MELCO began the development of the MELTAC platform in 1985, initially targeting non-safety-related applications, with a long-term goal of applying the platform to safety-related functions.

The same basic equipment design is used for both safety-related and non-safety-related applications. However, MELTAC platform components intended for safety-related use are

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION developed using QA methods that differ from those used for non-safety-related systems, particularly with respect to the software development life cycle.

MELTAC platform modules and components qualified for safety-related applications are designated as MELTAC Nplus S, whereas components limited to non-safety-related applications are designated as MELTAC Nplus. These designations apply to all aspects of the platform, including hardware, software, documentation, and engineering tools. Modules and components unique to the MELTAC Nplus platform used solely for non-safety-related applications are not within the scope of this SE.

The MELTAC platform is a digital, computer-based PLC system designed using modular building blocks that can be assembled to support safety-related applications, such as reactor protection systems and engineered safety features actuation systems. The platforms controller includes a central processing unit (CPU) chassis, which may contain one or two subsystems depending on the redundancy configuration required for a given application. It also includes a switch panel, status display (switch) modules, and fan units.

Each subsystem within the CPU chassis consists of power supply modules, CPU modules, control network interface (I/F) modules, a system management module, and bus master modules. The controller also incorporates one or more input/output (I/O) chassis, which houses the systems I/O modules. The MELTAC platform offers a range of I/O modules capable of interfacing with various plant components and systems.

4.2 Description of Changes to the MELTAC Platform from Revision 2 to Revision 3 of the Topical Report The NRC staff describes changes to the MELTAC Platform from Rev. 2 to Rev. 3 of the TR in the Subsections below. Although these descriptions reflect the overall changes to the MELTAC Platform from Rev. 2 to Rev. 3 of the TR, the MELTAC platform is a digital, computer-based PLC system designed using modular building blocks that can be assembled to support safety-related applications, such as reactor protection systems and engineered safety features actuation systems. The platforms controller includes a CPU chassis, which may contain one or two subsystems depending on the redundancy configuration required for a given application. It also includes a switch panel, status display (switch) modules, and fan units.

Each subsystem within the CPU chassis consists of power supply modules, CPU modules, control network interface (I/F) modules, a system management module, and bus master modules. The controller also incorporates one or more input/output (I/O) chassis, which houses the systems I/O modules. The MELTAC platform offers a range of I/O modules capable of interfacing with various plant components and systems.

For the purposes of this review, this SE only evaluates the information designated as Phase 1 review of the MELTAC Platform in Rev. 3 of the TR.

4.2.1.

New and Updated System Modules and Components Tables 4.2-1 and 4.2-2 in this section list the new and updated modules or components introduced in the MELTAC Platform in Rev. 3 of TR, along with their unique model identification numbers. Section 4.2 of this SE for the MELTAC Platform in Rev. 3 of the TR Phase 1 review provides the detailed description for the new and updated modules and components. All other

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION modules and components previously listed in the MELTAC Platform in Rev. 2 of the TR are qualified under its associated NRC staff SE, dated November 2018, subject to the limitations and conditions specified therein.

Table 4.2 1: Updated MELTAC Platform Nplus S Modules and Components Category Type Unique Model Identification Number Central Processing Unit (CPU) Module PCPJ PCPJ-D1 System Management Module PSMJ PSMJ-D1 Bus Master Module PFBJ PFBJ-D1 Control Network Interface Module PWNJ PWNJ-D1 Analog Input Module Current input MLPJ MLPJ-B1 Resistance Temperature Detector (RTD) 4-line type 4-line Pt200, 32 to 752 °F (0 to 400 °C)

MRTJ MRTJ-E4 4-line Pt100, 32 to 212 °F (0 to 100 °C)

MRTJ MRTJ-K1 Thermocouple K Type 32 to 2372 °F (0 to 1300 °C)

MTCJ MTCJ-F3 Analog Output Module Current output MAOJ MAOJ-B1 Isolation Module Current input, Current/Voltage output KILJ KILJ-B1 RTD 4-line type input Current/Voltage output 4-line Pt100, 32 to 302 °F (0 to 150 °C)

KIRJ KIRJ-B1 4-line Pt100, 32 to 392 °F (0 to 200 °C)

KIRJ KIRJ-B2 4-line Pt200, 32 to 752 °F (0 to 400 °C)

KIRJ KIRJ-B3 Electrical/Optical (E/O) Converter Module Electrical/Optical conversion Electrical interface: RS-485 MEOJ MEOJ-A2 Electrical interface: RS-232C MEOJ MEOJ-B1 CPU Power Supply (Large capacity type)

PPSJ PPSJ-B3 Safety VDU Panel T10DH T10DH-N001 Frame Memory Unit (FMU) Module PFDJ PFDJ-D1 Status Display and Switch Module Single Redundant Parallel PPNJ PPNJ-D2 Fan Modules CPU Fan KFNJ KFNJ-A01 power supply (PS) Fan KFNJ KFNJ-A02 Door Fan KFNJ KFNJ-A03 Terminal Unit Analog (AI/AO)

PSND PSND-A01 Digital (DI/DO)

PSND PSND-A02 Optical Switch RJMA RJMA-A2

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION 1 The scope of the MELTAC platform does not include cables which are intended for use in safety DI&C systems and must be adequately qualified for site-specific environmental and operational conditions. Refer to PSAI 6.2.1 in Subsection 6.2 of this SE.

Table 4.2 2: New MELTAC Platform Nplus S Modules and Components1 Category Module Type Unique Model Identification Number Contact input (built-in contact PS)

Current increase function Contact impressed voltage: DC 48 V Contact current: 10 to 12 mA RDIJ RDIJ-A1 Contact input (built-in contact PS)

Contact impressed voltage: DC 24 V Contact current: 9 to 12 mA RDIJ RDIJ-A2 Digital Output Module Semiconductor output (open drain)

RDOJ RDOJ-A1 Distribution Module For Analog input RDDJ RDDJ-A1 Power Interface Module Semiconductor output (open drain)

Contact input (built-in contact PS)

RPDJ RPDJ-A1 Power Supply Module I/O Power Supply RPAJ RPAJ-A1 Repeater Module Repeater Alarm signal input (built-in contact PS)

Mutual anomaly monitoring function RCMJ RCMJ-A1 CPU Module Chassis Non-split Redundant Standby Redundant Parallel Single ZCDJS ZCDJS-A21 I/O Module Chassis RDIJ Digital Input Module RDOJ Digital Output Module RPDJ PIF Module (This requires two slots)

ZRDJ ZRDJ-AK1 Analog Input Module ZRXJ ZRXJ-AA1 Isolation Module ZRSJ ZRSJ-AA1 Optical Conversion Module ZREJ ZREJ-AA1 Alarm Signal Input Modules Alarm signal input Power supply REIJ REIJ-A1 Excore Nuclear Instrumentation (EI) Unit EI Signal Processing Unit EI-20W-027C EI-20W-027C EI Unit Power Supply EI-32C-027C EI-32C-027C EI Detector Power Supply EI-30C-027C EI-30C-027C EI Operation Panel EI-40C-027C EI-40C-027C Isolation Module Thermocouple K type/RTD 4-line type input Voltage output KITJ KITJ-A1 Status Display and Switch Module Redundant Standby 614JND 614JND Fan Modules I/O Fan KFNJ KFNJ-A04

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Updated Controller CPU Module The MELTAC platform controller includes a CPU chassis, which contains either one or two subsystems, depending on the redundancy configuration required for the application. Each chassis also contains a switch panel, status display (switch) modules, and a fan unit. Each subsystem consists of PS modules, CPU modules, control network interface (I/F) modules, a system management module, and bus master modules. Additionally, the controller includes one or more I/O chassis, which houses the systems I/O modules. For the MELTAC Platform in Rev. 3 of the TR, the updated CPU module PCPJ-D1 has been introduced.

Updated System Management Module The system management module monitors the status of the CPU module and executes auxiliary controller functions not directly related to the CPU module as described below. The system management module contains an auxiliary digital input/digital output (DI/DO) which can be configured to generate alarms such as fan failure. The system management module also has an ethernet interface for communicating with the MELTAC engineering tool when it is connected.

The updated system management module PSMJ-D1 is included for the MELTAC Platform in Rev. 3 of the TR.

Updated Bus Master Module The bus master module has four communication interface channels. Each interface channel can be defined to either control communication with I/O modules or to establish serial data link communication with controllers in a different safety division. When used to control communication with I/O modules, each communication channel can control 96 I/O modules, enabling control of a maximum of 384 I/O modules per bus master module. When used to implement serial data link communication between controllers in other safety divisions, two-port memory access configuration is used to ensure that communication functions do not disrupt deterministic CPU operation. The updated bus master module PFBJ-D1 is included for the MELTAC Platform in Rev. 3 of the TR.

Updated Control Network Interface Module The control network is used to communicate safety-related data among controllers and safety visual display unit (VDU) processors within any single safety division. In Rev. 3 of the TR, the control network also supports data communication between the non-safety system and one or more safety divisions. Interdivisional communication for safety-related functions between safety divisions is not implemented in the control network. The typical types of interdivisional communication between safety and non-safety on the control network include process signals from non-safety controllers to the safety components of each division, and alarm or status information from the safety components or safety instrumentation to non-safety controllers. The specific interdivisional communication data is application specific. The updated control network module PWNJ-D1 is included in the MELTAC Platform in Rev. 3 of the TR.

Updated and New I/O Modules The MELTAC platform includes several types of analog and digital modules to accommodate various I/O signal interfaces. The modules mounted in the chassis are connected to the bus master modules in the CPU chassis via repeater modules. Repeater modules are used to shape

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION and amplify data communication signals to be transferred to and from the I/O bus. Data transfer occurs through the I/O bus. The I/O modules in the MELTAC platform provide the input and output functions and signal conditioning functions, including signal conversion and noise reduction. A few updated I/O modules, as listed in Table 4.2-1 of this SE, are included in the MELTAC Platform in Rev. 3 of the TR.

Updated Status Display and Switch Modules The status display and switch module or status display module are mounted in the CPU chassis. The status display and switch module is used when the redundant standby controller configuration is implemented to display the mode and alarms of the subsystem and to provide a means of performing manual operating mode change over using a switch. Operating modes include control mode and standby mode. These modes of operation are used to support the redundant parallel and redundant standby system configurations. The status display module is used when the redundant parallel controller or single controller configurations are implemented.

This module displays the mode and alarms of the subsystem.

New CPU Module Chassis The CPU chassis includes one subsystem and a CPU Fan. A subsystem consists of a CPU module, system management module, status display module, control network I/F module, and bus master module. A subsystem communicates with the control network via its own optical switch. A subsystem can drive several control network I/F modules and bus master modules depending on the scale of the application.

New Input/Output Chassis The MELTAC I/O chassis is a structure which houses various MELTAC I/O module components. The I/O modules are mounted in one or more dedicated I/O chassis.

Updated CPU Power Supply Module The CPU PS modules convert 120 VAC power to provide multiple outputs of +2.1 voltage direct current (VDC) and +5 VDC to the CPU chassis for distribution to installed CPU modules. CPU PS modules are equipped with overvoltage protection that deenergize the output when the output voltage exceeds a setting, and overcurrent protection that lowers the output voltage level when an overload or output short circuit occurs. CPU PS modules provide a contact output alarm signal when an output shutdown occurs.

New I/O Power Supply Module The new I/O power module (RPAJ) converts 120 VAC power to provide +24 VDC for I/O modules, isolation modules, power interface modules, electrical-to-optical (E/O) converter modules, and fan units. I/O PS modules are equipped with overvoltage protection that de energizes the output when the output voltage exceeds a setting, and overcurrent protection that lowers the output voltage level when an overload or output short circuit occurs. I/O PS modules provide a contact output alarm signal when an output shutdown occurs.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Updated Terminal Units Terminal units provide an electrical connection interface between external field cables and the MELCO distribution and I/O modules. There are two types of terminal units available in the MELCO platform: one for analog I/O and one for digital signal I/O.

New Fan Modules The fan modules consist of updated CPU fans, power supply (PS) fans, door fans, and new I/O fans. The new I/O fan unit is installed at the top of the I/O chassis to cool the modules within I/O chassis. It is equipped with a fan stop detection circuit which provides the same contact signal as the CPU Fan.

Updated Optical Switch The optical switch is installed outside the CPU chassis. It optically bypasses the control network communication line in the Control Network I/F Module during controller maintenance.

New Distribution Module Distribution modules distribute input signals to system I/O modules. Distribution modules also provide surge absorption functionality between the I/O modules and the terminal unit. A variety of distribution modules are available on the MELTAC platform. The type of distribution modules used depends on the type of I/O module being interfaced.

Updated Isolation Modules Isolation modules provide electrical isolation between equipment in different safety divisions.

Analog isolation modules receive analog input signals or pulse input signals and transmit corresponding analog output signals. Isolation modules do not rely on software processing to perform their functions. Electrical isolation is provided between the I/O signals within the isolation module. The isolation modules are mounted in dedicated isolation chassis.

New Power Interface Module Power interface (PIF) modules receive output commands resulting from subsystem operation, and control power to actuate plant components. There are several types of PIF module sub-boards available to support different types of plant components. Each PIF module is configured with the appropriate sub-board for compatibility with the component being controlled.

PIF modules receive output commands from the MELTAC safety processors via the I/O bus connections to the I/O chassis backplane. PIF modules are used to control power to drive the switchgears, solenoid valves, etc. for actuation of plant components. PIF modules use power semiconductor devices for controlling power instead of electromechanical relays to eliminate the need for periodic replacements. The PIF modules can also be used to receive inputs from external contacts to support the transmission of component status signals to the subsystem.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Updated Safety Visual Display Unit Panel The S-VDU panel is a human system interface (HSI) device which displays safety system operational screens and provides a touch screen operator interface to enable operators to interact with the safety system. The S-VDU panel consists of a color graphic display with an integral touch screen operator interface.

The S-VDU panel receives analog video signals from the S-VDU processor. Input signals from the operator touch screen interactions are transmitted to the S-VDU processor in the form of x-y coordinate data using a serial communications interface. The MELTAC platform S-VDU consists of a special purpose MELTAC controller, peripherals, and a liquid crystal display touch screen.

Updated I/O Bus Inside the Controller This I/O bus inside the controller can be extended between cabinets by electrical/optical (E/O) converter modules and a pair of optical fibers. The communication is electrically isolated but intra-divisional.

New Excore Instrumentation (EI) Unit The new EI unit listed in Table 4.2-2 of this SE consists of EI signal processing sub-units, EI detector PS and EI unit PS which are intended to be installed outside containment in an area that minimizes the distance to the excore neutron detectors. It also includes an EI operation panel which is provided for adjusting EI units. An EI signal processing sub-unit has a dedicated signal output line, where excore neutron detector signal is processed only in an analog manner.

New EI Unit Watchdog Timers Several modules of the MELTAC platform utilize watchdog timers (WDTs) to monitor processor performance and trigger predefined failure states upon detection of controller processor malfunctions. ((

)).

Updated MELTAC Platform Communication The MELTAC platform communication architecture is comprised of the following three types of data communication:

Control network communication Data link communication Maintenance network communication All three types of communication are designed based on the following fundamental principles:

Asynchronous communication is used. The CPU module and the communication controller tasks are executed asynchronously.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Communications are performed by means of shared two-port memory. This allows data to be communicated between the two digital components with no synchronization.

The CPU module performs no communication handshaking that could disrupt deterministic safety logic processing. The digital processing components that execute the safety functions are separate from digital processing components that perform communications functions such as protocol management and handshaking.

Predefined data size and structure are used during data transfer to ensure deterministic communication.

Electrical communication processing faults in one electrical division (or controller) cannot adversely affect performance of the safety function in other divisions (or controllers).

In the MELTAC Platform in Rev. 3 of the TR, no changes are proposed to the implementation of data link communication and maintenance network communication. However, MELCO proposes to expand the use of the control network to support interdivisional communication between MELTAC safety controllers and non-safety nodes, in addition to its original function for intra-divisional safety-related communication.

Updated Environmental, Seismic, Electromagnetic Compatibility, and Isolation Qualification Rev. 3 of the TR outlines the methods and standards used to perform environmental, seismic, electromagnetic, surge withstand capability, electrostatic discharge, and isolation qualification for the new and applicable updated modules and components as listed in Tables 4.2-1 and 4.2-2 of this SE.

For environmental and seismic qualifications, the only changes introduced in Rev. 3 of the TR are the adoption of updated regulatory guidancespecifically, RG 1.89, Rev. 2 for environmental qualification, and RG 1.100, Rev. 4 for seismic qualification. For electromagnetic compatibility (EMC) qualification testing, MELCO has revised the TR to incorporate the use of RG 1.180, Rev. 2, and the associated IEC 61000 series standards endorsed therein. These standards cover all required EMC tests, including conducted and radiated emissions, conducted susceptibility for power and signal leads, and radiated susceptibility to EMI/RFI.

No changes are proposed in the MELTAC Platform in Rev. 3 of the TR regarding other qualification areas, such as electrostatic discharge and isolation testing.

4.3 NRC Staff Safety Evaluation for the MELTAC Platform in Rev. 3 of the TR for Phase1 The NRC staff has previously approved the MELTAC Platform in Rev. 2 of the TR (Ref. 13) for use in safety I&C systems at U.S. nuclear power plants. Therefore, this SE is focusing only on information that supports the changes included in the Rev. 3 of the TR which are also within the scope of the Phase 1 review. As a result, this SE is intended to be used in conjunction with the NRC staffs SE for the approved MELTAC Platform in Rev. 2 of the TR; the forthcoming SE for the Phase 2 review of Rev. 3 of the TR; and any other NRC staff evaluation associated with Rev. 3 of the TR, as discussed in Section 2.0 of this SE. Accordingly, the NRC staff notes that an applicant or licensee cannot exclusively rely on this SE to use the MELTAC Platform in Rev. 3 of the TR.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION The MELCO has also submitted updates to the MELTAC Application SPM (Ref. 19) and the CGD program (Ref. 20). However, these updates are being evaluated under a separate review and are not included in this SE, as discussed in Section 2.0 of this SE. A subsequent Phase 2 review is planned to assess additional elements of the MELTAC Platform in Rev. 3 of the TR, including the software safety analysis, EQ testing specifications, reports, and other supporting documentation. As requested by MELCO, this SE does not include an evaluation of the revised QA program (Ref. 26) for the MELTAC Platform in Rev. 3 of the TR. More details are available in Generic Open Item 6.1.5 of this SE.

Although GDC 19, Control room, requires that a control room to be provided for which actions can be taken to operate the nuclear power unit safely, and the information displays in the MELTAC platform may be used to support compliance with GDC 19, it should be noted that the NRC staff did not evaluate the S-VDU or non-safety stations for conformance to GDC 19 as this is application dependent. This is further addressed in PSAI 6.2.21 in Section 6.0 of this SE.

4.3.1.

Equipment Qualification (EQ)

The principal objectives of EQ for safety-related instrumentation and control (I&C) systems are to minimize the potential for common cause failures due to environmental, EMI/RFI, seismic, and isolation effects, and to demonstrate that the I&C equipment can perform its designated safety functions during and after a design basis event. Specifically, EQ aims to: (1) confirm that the safety I&C system can operate reliably under abnormal service conditions such as elevated temperature, humidity, radiation, electrical disturbances (e.g., power surges, electrostatic discharge, electrical fast transients), EMI/RFI, and seismic vibration, and (2) verify that EQ tests satisfy plant-specific requirements.

The criteria for EQ of safety-related equipment are established in 10 CFR Part 50, Appendix A, GDC 2 and 4. Additionally, 10 CFR 50.55a(h) incorporates by reference the requirements of IEEE Std. 603-1991, which addresses system-level design and quality criteria for device qualification. RG 1.209, Rev. 0, endorses IEEE Std. 323-2003, IEEE Standard for Qualifying Class 1E Equipment for Nuclear Power Generating Stations, for qualifying safety-related DI&C systems located in mild environments. Rev. 3 of the TR incorporates IEC/IEEE Std. 60780-323-2016, for the qualification of updated and newly added modules and components in the MELTAC Platform in Rev. 3 of the TR.

To comply with the requirements of GDC 4, 10 CFR 50.49, Environmental Qualification of Electric Equipment Important to Safety for Nuclear Power Plants, and IEEE Std. 603-1991, an applicant must demonstrate through environmental qualification that safety I&C systems meet design basis and performance requirements when the safety I&C equipment is exposed to normal and adverse environments. 10 CFR 50.49 does not include requirements for seismic and dynamic qualification, protection of electric equipment important to safety against other natural phenomena and external events, and equipment located in a mild environment.

The Electric Power Research Institute (EPRI) report, TR-107330, which is discussed in RG 1.209, Rev. 0, presents an acceptable specification in the form of a set of requirements to be applied to the generic qualification of PLCs for application and modification to safety-related I&C systems in nuclear power plants. It is intended to provide a generic qualification envelope corresponding to a mild environment that should meet regulatory acceptance criteria for a wide range of plant-specific safety-related applications. The specific qualification envelope that is established by compliance with the guidance of EPRI TR-107330 consists of the maximum

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION environmental and service conditions for which qualification was validated and the range of performance characteristics for the PLC platform were demonstrated under exposure to generic stress conditions. Applicants or licensees using the MELTAC Platform in Rev. 3 of the TR are required to verify if the environmental requirements and service conditions of their specific applications are bounded by the generic EQ envelope established. More details are available in PSAI 6.2.2 in Section 6.0 of this SE.

In Section 5.0 of Rev. 3 of the TR, MELCO states, in part, that If any module is updated, and it is determined that qualification re-testing is required by the evaluations conducted in accordance with Section 6.1.7 of Rev. 3 of the TR, the module will be tested with the same method and acceptance criteria. The same method and acceptance criteria will also be used for any new MELTAC modules. However, the NRC staff noted that certain testing standards and criteria, particularly those related to EMC, have been updated in Rev. 3 of the TR. In contrast, some unchanged modules and components were qualified under previous methods and acceptance criteria in Rev. 2 of the TR.

To address this inconsistency, the NRC staff issued RAI No. 1, asking for clarification on whether and how the same methods and acceptance criteria would be applied to qualify both updated/new and unchanged MELTAC modules and components. The RAI also requested that MELCO clearly identify updated, new, and unchanged modules and components, including their unique model identification numbers and corresponding qualification methods and acceptance criteria. In its RAI response (Ref. 7), MELCO corrected the inconsistency and made numerous clarifications and revisions to the Rev. 3 of the TR, which the NRC staff reviewed and concluded to be acceptable.

Additionally, in RAI No. 4, the NRC staff identified several confirmatory statements in Section 3.0 of Rev. 3 of the TR, that inaccurately suggested updated and new modules had already been qualified, despite qualification testing not yet being completed. In its response to RAI No. 4 (Ref. 7), MELCO corrected these inaccuracies. The NRC staff reviewed these corrections in the RAI response and concluded they are adequate.

4.3.1.1 Equipment Environmental Qualification For the environmental qualification of the updated and new components listed in Tables 4.2-1 and 4.2-2 of this SE, MELCO proposed to adopt IEC/IEEE Std. 60780-323-2016 in place of IEEE Std. 323-2003, which is endorsed by RG 1.209, Rev. 0. Since IEC/IEEE Std. 60780-323-2016 is already endorsed in the updated RG 1.89, Rev. 2, the NRC staff determines that the proposed use of IEC/IEEE Std. 60780-323-2016 to be an acceptable standard for performing environmental qualification of the updated and new components included in Rev. 3 of the TR.

However, as previously noted, the requested scope of the Phase 1 review for Rev. 3 of the TR does not include evaluation of the environmental qualification testing specifications, procedures, associated testing summary reports, and other necessary supporting information. The NRC staff is planning to review these items as part of the Phase 2 review to ensure the compliance with GDC 2 and 4 for changes in Rev. 3 of the TR.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION In addition, MELCO included the following generic environmental conditions in Rev. 3 of the TR for qualifying the new EI units:

In Rev. 3 of the TR, the new EI signal processing sub-units, EI detector PS, and EI unit power supply are intended to be installed outside the reactor containment in locations that minimize the distance to the excore neutron detectors. ((

)).

However, the generic environmental qualification of the new EI units, based on these assumed environmental conditions, is planned to be evaluated by the NRC staff during the Phase 2 review to ensure the compliance with GDC 2 and 4 for changes in Rev. 3 of the TR. Applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR for plant-specific safety applications should ensure that their plant-specific environmental qualification requirements are bounded by the assumed generic conditions. More information is available in PSAI 6.2.2 in Section 6.0 of this SE.

4.3.1.2 Equipment Seismic Qualification The seismic qualification in Rev. 2 of the TR was performed in accordance with RG 1.100, Rev. 3, and its endorsed IEEE Std. 344-2004. In Rev. 3 of the TR, MELCO proposed to use IEEE Std. 344-2013 for the seismic qualification of the updated and new MELTAC modules and components. Since IEEE Std. 344-2013 is endorsed in RG 1.100, Rev. 4 with staff regulatory guidance, the NRC staff determines that the use of IEEE Std. 344-2013 to be an acceptable standard for performing seismic qualification of the updated and new components listed in Tables 4.2-1 and 4.2-2 of this SE.

As with the environmental qualification, the Phase 1 review of Rev. 3 of the TR does not include seismic qualification testing specifications, procedures, and test results. These will be evaluated during the Phase 2 review to ensure compliance with GDC 2 and 4 for changes in Rev. 3 of the TR. More information is available in Generic Open Items 6.1.2 and 6.1.3 in Section 6.0 of this SE.

4.3.1.3 Equipment Electromagnetic Compatibility Qualification For the EMC qualification of the updated and new modules and components listed in Tables 4.2-1 and 4.2-2 of this SE, MELCO proposed using a set of IEC 61000 series testing standards in place of the MIL-STD-461E series standards that were used to qualify modules Table 4.3 1: Generic Environmental Conditions for EI Units Item Specifications Assumed Room temperature Recommended 50 to 104 °F (10 to 40 °C)

This temperature range is expected within a heated or air-conditioned location in the reactor building of the nuclear power plant. Operating within this range could maximize the life of the equipment.

Operational Limit 32 to 122 °F (0 to 50 °C)

EI units should be mounted in a cabinet preventing accident humidity (95%Rh no condensation).

Accident (1 week) 32 to 131 °F (0 to 55 °C)

Radiation resistance Normal: 0.01 mGy/h Accident: 3 mGy/h (1 week)

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION and components in the previously approved MELTAC Platform in Rev. 2 of the TR. Specifically, MELCO proposed adopting the following IEC 61000 series standards as acceptable criteria for qualifying the updated and new components, in lieu of the corresponding MIL-STD-461E standards:

Conducted emissions, high-frequency, 150 kHz to 30 MHz (CISPR 16 in IEC 61000-6-4)

Radiated emissions, electric field, 30 MHz to 6 GHz (CISPR 16 in IEC 61000-6-4)

Conducted susceptibility, electrically fast transients/bursts (IEC 61000-4-4)

Conducted susceptibility, surges (IEC 61000-4-5)

Conducted susceptibility, disturbances induced by RF fields, 150 kHz to 80 MHz (IEC 61000-4-6)

Conducted susceptibility, 100 kHz ring wave (IEC 61000-4-12)

Conducted susceptibility, low frequency, 16 Hz to 2.4 kHz (IEC 61000-4-13)

Conducted susceptibility, low frequency, 0 Hz to 150 kHz (IEC 61000-4-16)

Radiated susceptibility, magnetic field, 60 Hz (IEC 61000-4-8)

Radiated susceptibility, magnetic field, 60 Hz to 50 kHz (IEC 61000-4-9)

Radiated susceptibility, magnetic field, 100 kHz and 1 MHz (IEC 61000-4-10)

Radiated susceptibility, electric field, 26 MHz to 6 GHz (IEC 61000-4-3)

The NRC staff reviewed the proposed set of IEC 61000 series standards and determines their generic criteria, values, ranges, and other requirements to be equivalent to those required by MIL-STD-461G2 characteristics, and is therefore, consistent with RG 1.180, Rev 2. Accordingly, the NRC staff determines that MELCOs proposed change in Rev. 3 of the TR to adopt the IEC 61000 series standards is acceptable, provided that the full set of susceptibility testing standards is applied in its entirety during the EMC qualification process. In addition, the Phase 1 review of Rev. 3 of the TR does not include EMC qualification testing specifications, procedures, and test results. These will be evaluated during the Phase 2 review to ensure compliance with GDC 2 and 4 for changes in Rev. 3 of the TR. More information is available in Generic Open Items 6.1.2 and 6.1.3 in Section 6.0 of this SE.

Additionally, the NRC staff noted that MELCO revised the environmental qualification EQ test configuration for EMC testing in accordance with the IEC standards. Under the updated approach, the equipment under test (EUT) will consist of cabinets populated with various components, including chassis, modules, PS units, fans, and other relevant hardware. The EUT will incorporate the types of modules required for safety protection system applications, as identified in Appendix A of Rev. 3 of the TR.

The NRC staff also noted that the EUT will consist of floor-standing cabinets according to Rev. 3 of the TR. These cabinets will be tested with their doors open to simulate worst-case conditions that may occur during testing or maintenance. For module types where variations (e.g., normally open [NO] vs. normally closed [NC] contacts or different input ranges) are not expected to impact EMC test outcomes, a representative module type will be selected for testing. In the configuration involving the S-VDU panels, power to the S-VDU panel will be supplied from the CPU cabinet and connected via dedicated power and signal cables.

The NRC staff determines that the proposed EUT configuration for EMC qualification to be generally acceptable. However, detailed identification information such as descriptions, model 2 MIL-STD-461G - a standard that establishes interface and associated verification requirements for the control of the EMI (emission and susceptibility).

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION numbers, and part numbersshould be provided to clearly identify each module and component under test. This information, along with the EMC qualification test specifications, procedures, and summary results, shall be submitted for the Phase 2 review to verify compliance with GDC 2 and 4, applicable regulatory guidance and acceptance criteria. More details are available in Generic Open Items 6.1.2 and 6.1.3 in Section 6.0 in this SE.

However, the NRC staff noted that in Section 3.0 of Rev. 3 of the TR, it states, in part, that there is no additional site-specific EMI qualification for the MELTAC Platform in Rev. 3 of the TR. The NRC staff notes that the SE for the MELTAC Platform in Rev. 2 of the TR includes PSAI 5.2.4, which requires applicants or licensees to demonstrate that the generically qualified MELTAC platform equipment envelopes the specific environmental conditions. PSAI 5.2.4 was not addressed in Rev. 3 of the TR. To address this inconsistency, the NRC staff issued RAI No.

2, requesting additional information on how PSAI 5.2.4 is resolved in the MELTAC Platform in Rev. 3 of the TR. In MELCOs response to RAI No. 2 (Ref. 7), a revision was made to Section 3.0 of the TR by removing the quoted language to address the NRC staffs concern. The NRC staff reviewed the RAI No. 2 response and associated deletion and concluded the RAI response is acceptable.

The NRC staff concludes that the information related to the EQ of updated and new modules and components are acceptable for the Phase 1 review of Rev. 3 of the TR based on evaluation in Section 4.3.1 of this SE. However, for updated modules and components, additional analysis and evaluation should be performed and submitted as part of the Phase 2 review to determine whether their previous qualification, approved in the SE for MELTAC Platform in Rev. 2 of the TR, remains valid. The EQ for all new modules and components listed in Table 4.2-2 must be performed in accordance with the methods and acceptance criteria specified in Rev. 3 of the TR. See Generic Open Items 6.1.2 and 6.1.3.

Overall, because the Phase 1 review of Rev. 3 of the TR does not include EQ testing specifications, procedures, and test results, the NRC staff will evaluate those additional documents during the Phase 2 review to ensure compliance with GDC 2 and 4 for all updated and new modules and components included in Rev. 3 of the TR. More details are available in Generic Open Items 6.1.2 and 6.1.3 in Section 6.0 of this SE.

4.3.2.

New Excore Instrumentation (EI) Units As listed in Table 4.2-2 of this SE, the new EI unit consists of the EI signal processing sub-unit, EI unit power supply, EI detector PS, and EI operation panel. Appendix E of Rev. 3 of the TR provides ((

)).

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((

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((

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The NRC staff notes that Rev. 3 of the TR does not clearly describe how the new EI units will be developed or how access to the EIOP will be controlled. To address this, the NRC staff issued RAI No. 12 requesting additional information. In its response, MELCO stated that the same software QA plan applied to other MELTAC platform equipment will also be used for the new EI units and other new modules and components. Additionally, ((

)). The NRC staff did not review the Quality Manual, Rev. 2, which governs the QA for development of the new EI units, as part of the SE. More details are available in Section 4.3.3 of this SE in the discussion pertaining to the MELTAC QA program.

The NRC staffs evaluation of new EI units against the applicable requirements of IEEE Std. 603-1991 and guidance in IEEE Std. 7-4.3.2-2016 are discussed in Sections 4.3.8 and 4.3.9 of this SE. In addition, as with other new modules and components, the EQ of the new EI unit is not included in this SE and NRC staff plans to evaluate it as part of Phase 2 review.

More details are available in Generic Open Item 6.1.3 in Section 6.0 of this SE.

4.3.3.

Changes to the MELTAC Quality Assurance Program The MELTAC platform was originally developed to comply with the Japanese nuclear quality programs. As such it was not developed to the quality standards required for use in U.S. nuclear safety applications at that time. To facilitate use of the MELTAC platform in the U.S., MELCO performed are evaluation of the MELTAC platform design and its processes using the CGD processes defined in 10 CFR Part 21, Reporting of Defects and Noncompliance. This re-evaluation effort is hereafter referred to as the MELTAC re-evaluation program (MRP). The MRP was evaluated in the SE for the approved MELTAC Platform in Rev. 2 of the TR.

MELCO submitted the Quality Manual Based on U.S. Nuclear Regulations, Rev. 2 (Ref. 26).

Some changes were made to this document in response to a self-assessment. But, per MELCOs request, this revised Quality Manual based on U.S. Nuclear Regulations is not evaluated in this SE. A condition has been added to this SE to address concerns regarding the evaluation of the Quality Manual Based on U.S. Nuclear Regulations and its applicability to the MELTAC Platform in Rev. 3 of the TR. More information is available in Section 6.1.5 of this SE.

In addition, to support the review of Rev. 3 of the TR, MELCO submitted a revised Summary of MELTAC Platform CGD Activity (Ref. 20) including four new modules: ((

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)). As stated in Section 2.1 of this SE, the evaluation of acceptability for the CGD of these modules are outside the scope of this SE. Even though the latest updates and revisions to the Summary of MELTAC Platform CGD Activity and the MELTAC Application SPM have been submitted for NRC staff review, these two documents will be evaluated in a separate review for compliance with GDC 1 and Appendix B QA requirements. More information is available in Generic Open Item 6.1.1 in Section 6.0 of this SE.

4.3.4.

MELTAC Software and Development Process DI&C safety systems must be designed, developed, installed, and tested to quality standards commensurate with the importance of the safety functions to be performed. The development of safety I&C system software should progress according to a formally defined software life cycle.

Implementation of an acceptable software life cycle provides the necessary software quality.

There are two categories of software used in a MELTAC platform-based I&C safety system:

basic software and application software.

MELTAC Basic Software: MELTAC platform basic software is common, application independent, and performs single task processing to achieve deterministic behavior by adherence to proprietary design principles. The design principles are described in Section 4.1.3.1 of Rev. 3 of the TR (Ref. 5). The processes within the basic software and the order of their execution are:

Initialization Timer Reset Mode Management / Redundant System Management Input Operation Self-diagnosis Output Tool Communication Redundant System Communication Remaining Time Diagnosis Constant Cycle Monitoring The NRC staff notes that there is no change to the above basic software execution process proposed in the MELTAC Platform in Rev. 3 of the TR, so the previous NRC staff evaluation and conclusion made in Section 3.3 of the SE for MELTAC Platform in Rev. 2 of the TR is not changed for the MELTAC Platform in Rev. 3 of the TR.

The platform SPM addresses the software development processes for platform basic software.

The basic software is used to operate various MELTAC platform components and is independent of the specific applications. MELCO provided MELTAC Platform Software Program Manual (SPM), Rev. 2 (Ref. 18), which modifies the software development processes for the platform basic software. The platform SPM addresses the software development processes for platform basic software. The basic software is used to operate various MELTAC platform components and is independent of the specific applications. In the revised MELTAC Platform Software Program Manual, the main changes include the following:

Updated revision numbers of RGs and Standards used.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Listed 10 CFR Part 50.55a Code and Standards.

Incorporated the requirement for Security to be consistent with BTP 7-14, Rev. 6.

Revised a sentence to state that the installation of MELTAC basic software is performed during an application software lifecycle.

Added a new sentence to reference MELTAC Platform Application Software Program Manual.

Corrected an output of the Concept Phase and related portions because the MELTAC TR is not an output of the Concept Phase activity.

There are some other minor and editorial changes in the revised MELTAC Platform SPM. The NRC staff reviewed all changes for this Phase 1 review and determined that they do not impact previous findings and conclusions made on the approved MELTAC Platform SPM, Rev. 0 in Section 3.5 of the SE for the MELTAC Platform in Rev. 2 of the TR. Therefore, the NRC staff determines that, subject to the successful closure of Generic Open Item 6.1.5 in this SE, all proposed changes associated with the MELTAC Platform SPM are acceptable for the Phase 1 review of the MELTAC Platform in Rev. 3 of the TR.

MELTAC Application Software: MELTAC application software is a computer program designed to perform a group of coordinated tasks and activities to achieve safety system functional requirements based on the application for which the MELTAC platform is used.

The application software of the MELTAC platform is designed using the MELTAC engineering tool. The application softwares functional algorithms is designed by combining graphical function blocks using the graphical user interface (GUI) of the MELTAC platform engineering tool. MELTAC application software is stored in the CPU flash read only memory and is subsequently accessed for execution purposes by the CPU safety processor. Using the MELTAC engineering tool, the application software graphical block diagram is automatically converted into the application software execution data that can be installed on the MELTAC platform and be executed directly by the operation process of the basic software. Each GUI is used to reduce the potential for design errors in building or modifying the application software.

This GUI-based programming language is also called POL (Problem Oriented Language). It allows application software to be developed by graphically interconnecting conventional function blocks and makes it easier for the independent verifier to ensure that the design outputs are developed in each life cycle phase of application software.

MELCO submitted a revised MELTAC Application SPM (Ref. 19) with many changes which can generally be grouped in the following types of categories:

((

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((

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((

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((

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((

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((

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((

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The latest revisions to the MELTAC Application SPM and the Summary of MELTAC Platform CGD Activity will be evaluated by the NRC staff in a separate review, and therefore, are not part of the Phase 1 review in this SE. More information is available in Generic Open Item 6.1.1 in Section 6.0 of this SE.

4.3.5.

Power Interface Module As listed in Table 4.2-2, MELCO included a new power interface (PIF) module for the MELTAC Platform in Rev. 3 of the TR. In both MELCOs Summary of Compliance to RG 1.152, Rev. 4, Rev. 1 (Ref. 23) and the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 (Ref. 22), MELCO states, in part, that interface parts to the diverse actuation system, which are PIF modules, distribution modules, and isolation modules, are not subject to any software common cause failures (CCFs) because no software elements are included in these modules.

The NRC staff noted that the ((

)).

((

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)).

Based on the above evaluation and additional information provided in the RAI No. 10 response, the NRC staff concluded that the ((

)). However, for plant-specific safety I&C applications using the MELTAC Platform in Rev. 3 of the TR, an application-specific diversity and defense-in-depth analysis shall be performed to address the CCF concern. More information is available in PSAI 6.2.6 in Section 6.0 of this SE.

4.3.6.

Self-Diagnostic Capabilities 10 CFR Part 50, Appendix A, GDC 21 requires, in part, that the protection system be designed for in service testability commensurate with the safety functions to be performed. It also requires a design that permits periodic testing of its functioning when the reactor is in operation, including the capability to test channels independently to determine failures and losses of redundancy that may have occurred. In addition, GDC 23 requires the protection system to be designed to fail into a safety state or into a state demonstrated to be acceptable on some other defined basis if conditions are experienced.

In Section 4.1.5 on self-diagnosis of the MELTAC Platform in Rev. 3 of the TR, ((

)).

Several modules of the MELTAC platform incorporate the use of watchdog timers (WDT) to monitor processor performance and to initiate predefined failure states when controller processor failures are detected. ((

)).

Therefore, based on the above evaluation and previous NRC staff review of self-diagnostic capabilities in Section 3.7.3 of the SE for the approved MELTAC Platform in Rev. 2 of the TR, the NRC staff determines that self-diagnostic functions of the revised MELTAC platform could be used to compliment or reduce the surveillance testing requirements of channel operability test and help support continual compliance with GDC 21 and GDC 23 for the MELTAC Platform in Rev. 3 of the TR. Because plant-specific applications of safety I&C systems are also designed with self-diagnostic features, determination of full compliance with GDC 21 and GDC 23 is dependent on the application-specific safety system design as well as the plant-specific safety functions performed by the specific safety I&C system. Therefore, determination

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION of GDC 21 and GDC 23 compliance remains an application-specific requirement. More information is available in PSAI 6.2.3 and 6.2.7 in Section 6.0 of this SE.

4.3.7.

Data Communications The MELTAC platform has three types of data communication: control network communications, data link communications, and maintenance network communications. In Rev. 3 of the TR, there are no changes made to the data link and maintenance network communication. Given that there are no changes on the use of the data link and maintenance network in Rev. 3 of the TR, the findings and conclusions made in Section 3.9 of the SE for the approved MELTAC Platform in Rev. 2 of the TR are not changed for both the data link and maintenance network communication. In the MELTAC Platform in Rev. 2 of the TR, the control network communication is used to support data exchange between processor nodes of a single safety division. Processor nodes can include the CPU application processors, component control processors, and S-VDU processors. In the MELTAC Platform in Rev. 3 of the TR, the application of control network is expanded to be used as an interface between safety-related and non-safety-related systems. The NRC staffs evaluation of this expanded use of the control network is provided in Section 4.3.9 of this SE.

4.3.8.

Compliance to IEEE Std. 603-1991, Criteria for Safety Systems for Nuclear Power Generating Stations For applicable nuclear power generating stations, 10 CFR 50.55a(h) requires that safety systems comply with the requirements of IEEE Std. 603-1991 and its correction sheet dated January 30, 1995. The NRC staffs evaluation is based on the guidance provided in SRP Chapter 7, Appendix 7.1-C, which establishes acceptance criteria for demonstrating compliance with IEEE Std. 603-1991. In Section 3.10 of the NRC staffs SE for the approved MELTAC Platform in Rev. 2 of the TR, the NRC staff concluded that the MELTAC platform met the requirements of IEEE Std. 603-1991, subject to limitations and conditions in Section 5.0 of its SE.

To support the evaluation of impacts from the proposed changes in Rev. 3 of the TR, MELCO submitted a revised document titled, Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2 (Refs. 21 and 22). The NRC staff reviewed the impacts of the proposed changes on compliance with requirements in the following clauses of IEEE Std. 603-1991, which is incorporated by reference into 10 CFR 50.55a:

Clause 5.3, Quality: MELCO uses a QA program based on Appendix B to 10 CFR Part 50 to govern all activities related to the development of revised MELTAC platform components and systems. This QA program also governs MELCOs CGD activities and is established by its Quality Manual Based on U.S. Nuclear Regulations, Rev. 2 (Ref. 26). However, in its response to RAI No. 13 (Ref. 11), MELCO requested that the NRC staff not review the Quality Manual Based on U.S. Nuclear Regulations, Rev. 2.

Additionally, MELCO submitted the revised MELTAC Application SPM and Summary of MELTAC Platform CGD Activity (Refs. 19 and 20), both of which are governed by MELCOs current QA program, as described in Quality Manual Based on U.S. Nuclear Regulations, Rev. 2. The review of these documents is beyond the scope of this SE in Phase 1 and is addressed in Generic Open Items 6.1.1 and 6.1.5 in Section 6.0 of this SE. Therefore, Generic

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Open Items 6.1.1 and 6.1.5 must be resolved to ensure compliance with the QA requirements of Clause 5.3 of IEEE Std. 603-1991 for the MELTAC Platform in Rev. 3 of the TR.

Clause 5.6, Independence: IEEE Std. 603-1991, Clause 5.6, includes three components for the independence requirement:

Clause 5.6.1 - Independence Between Redundant Portions of a Safety System Clause 5.6.2 - Independence Between Safety Systems and the Effects of a Design Basis Event Clause 5.6.3 - Independence Between Safety Systems and Other Systems In Rev. 3 of the TR, MELCO proposed expanded use of the control network to enable communication between safety-related and non-safety-related systems. Given that this proposed change only affects the safety and non-safety interface, the NRC staff only evaluated the proposed change for compliance with Clause 5.6.3. Accordingly, Clauses 5.6.1 and 5.6.2 are not evaluated in this Phase 1 review. Since the control network uses digital equipment, the NRC staff performed its evaluation of the expanded use of the control network against the requirements of IEEE Std. 603-1991, Clause 5.6.3, which is provided in Section 4.3.9 of this SE as part of the NRC staffs evaluation for conformance with IEEE Std. 7-4.3.2-2016, Clause 5.6.

Clause 5.7, Capability for Test and Calibration: The MELTAC Platform in Rev. 3 of the TR contains self-diagnosis features to identify failures, which are evaluated in Section 3.10 of the SE for the approved Rev. 2 of the TR and Section 4.3.6 of this SE. The NRC staff determines that compliance with Clause 5.7 of IEEE Std 603-1991 is dependent on the plant-specific system design. Therefore, the NRC staff identified PSAIs 6.2.3 and 6.2.7 to address compliance with this clause.

Clause 5.8, Information Display: For the non-safety nodes in the MELTAC Platform in Rev. 3 of the TR, the non-safety access to safety-related equipment is done via priority module associated with that equipment. The non-safety nodes are allowed to bypass a safety-related function only when it is determined to be acceptable by the safety system. ((

)). This is further addressed in PSAIs 6.2.4 and 6.2.5 in Section 6.0 of this SE. In addition, as stated in Section 4.3.9.5 of this SE, conformance with Clause 5.8 of IEEE Std 7-4.3.2-2016 is application specific (see PSAIs 6.2.18 and 6.2.19). As such, the NRC staff determines that compliance with Clause 5.8 of IEEE Std.60-1991 is subject to successful resolution of PSAIs 6.2.4, 6.2.5, 6.2.18, and 6.2.19.

Clause 5.11, Identification: The MELTAC Platform in Rev. 3 of the TR ensures unique identification of hardware, software, and documentation, including markings that indicate nuclear safety-related status, as described in Section 6.1.7 of Rev. 3 of the TR. This identification process is governed by MELCOs Appendix B to 10 CFR Part 50 QA program. The NRC staff determines that these identification controls satisfy the requirements of Clause 5.11 of IEEE Std. 603-1991, however, full compliance with Clause 5.11 of IEEE Std. 603-1991 is subject to the successful closure of Generic Open Item 6.1.5 in Section 6.0 of this SE.

Clause 5.14, Human Factors Considerations: There is no evaluation on the consideration of human factors analysis in the SE for the approved MELTAC Platform in Rev. 2 of the TR because no information on the human factors was provided. MELCO initially proposed some information in Rev. 3 of the TR for the MELTAC platform to address human factors

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION considerations, however, in response to RAI No. 13 (Ref. 11), MELCO withdrew these proposed changes. Therefore, compliance with the human factors engineering requirements of Clause 5.14 of IEEE Std. 603-1991 remains an application-specific item. More information is provided in PSAI 6.2.9 in Section 6.0 of this SE.

Clause 6.6, Operating Bypass: The MELTAC application program function symbols, shown in Appendix B of Rev. 3 of the TR, are suitable for generating operating bypass permissive interlocks and for implementing automatic bypass removal based on plant conditions. The platform possesses the capability to support such functions. However, because operating bypass design is plant-specific, compliance with Clause 6.6 of IEEE Std. 603-1991 must be addressed at the application level. More information is provided in PSAI 6.2.5 in Section 6.0 of this SE.

Clause 6.7, Maintenance Bypass: The revised MELTAC platform supports various maintenance bypass functions. For example, if an I/O module failure is detected, the associated measurement channel can be automatically bypassed. The system can also generate a maintenance bypass interlock to prevent multiple bypasses of the same process parameter across multiple safety divisions, and it can implement voting logic to ensure a safety function can still be achieved during maintenance bypass conditions. However, the detailed implementation of maintenance bypass is application specific. Thus, compliance with Clause 6.7 of IEEE Std. 603-1991 remains a plant-specific application requirement. More details are provided in PSAI 6.2.5 in Section 6.0 of this SE.

Based on the above evaluations of the proposed changes in Rev. 3 of the TR and prior evaluation in Section 3.10 of the SE for the approved MELTAC Platform in Rev. 2 of the TR, the NRC staff concludes that the MELTAC Platform in Rev. 3 of the TR meets the relevant requirements in the clauses specified above of IEEE Std. 603-1991 at the platform level, subject to relevant limitations and conditions in Section 6.0 of this SE, including Generic Open Items 6.1.1 and 6.1.5, and PSAIs 6.2.3, 6.2.4, 6.2.5, 6.2.7, 6.2.8, 6.2.9, 6.2.18, as well as 6.2.19 for conformance with IEEE Std. 7-4.3.2-2016 in Section 4.3.9 of this SE.

4.3.9.

Conformance with IEEE Standard, Criteria for Programmable Digital Devices in Safety Systems of Nuclear Power Generating Stations For the approved MELTAC Platform in Rev. 2 of the TR, MELCO submitted Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2 to demonstrate compliance with IEEE Std. 603-1991 and IEEE Std. 7-4.3.2-2003. Additionally, MELCO submitted MELTAC Platform ISG-04 Conformance Analysis to demonstrate conformance with ISG-04 guidance on data communication. In Section 3.11 of the NRC staffs SE for the MELTAC Platform in Rev. 2 of the TR, the NRC staff evaluated both documents and concluded that the MELTAC platform met the relevant requirements and guidance in IEEE Std. 603-1991, IEEE Std. 7-4.3.2-2003, and ISG-04, subject to limitations and conditions in Section 5.0 of the SE in Rev. 2 of the TR.

Although MELCO submitted a revised version of the ISG-04 Conformance Analysis in June 2023, ISG-04 was subsequently incorporated into RG 1.152, Rev. 4, which endorses IEEE Std. 7-4.3.2-2016, with exceptions, clarifications, and points of emphasis. In response, MELCO submitted Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 1 (Ref. 21) in March 2024 to demonstrate compliance with IEEE Std. 7-4.3.2-2016. The NRC staff reviewed the additional information and performed the following evaluations to assess compliance of the proposed changes in the MELTAC Platform in Rev. 3 of the TR, with relevant

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION guidance in applicable clauses of IEEE Std. 7-4.3.2-2016, as endorsed by RG 1.152, Rev. 4 with exceptions, clarifications, and points of emphasis.

RG 1.152, Rev. 4 states that conformance with IEEE Std. 7-4.3.2-2016, Criteria for Programmable Digital Devices in Safety Systems of Nuclear Power Generating Stations, is an acceptable method for satisfying the Commissions regulations related to functional reliability and design requirements for PDDs used in safety systems. This standard supplements IEEE Std. 603-1991 by addressing hardware, software, firmware, and interface criteria for safety system digital devices.

The NRC staffs evaluation focused on how changes to the MELTAC platform described in Rev. 3 of the TR conform to applicable clauses in IEEE Std. 7-4.3.2-2016. As noted in the revised Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, many criteria in both IEEE Std. 603-1991 and IEEE Std. 7-4.3.2-2016 are application specific and not applicable to a platform-level review. Therefore, the NRC staffs evaluation addressed only generic, platform-level guidance. Full compliance with IEEE Std. 7-4.3.2-2016 remains a plant-specific application requirement as discussed in PSAIs identified in the Subsections 4.3.9.1 through 4.3.9.5 of this SE. Each applicable clause of IEEE Std. 7-4.3.2-2016 to the MELTAC Platform in Rev. 3 of the TR are evaluated in the Subsections below.

4.3.9.1 Clause 5.4, Equipment Qualification In Rev. 3 of the TR, MELCO proposed using IEC/IEEE Std. 60780-323-2016 and IEEE Std. 344-2013 as acceptance criteria for environmental and seismic qualification of updated and new MELTAC modules, respectively. These standards are correspondingly endorsed in RG 1.89, Rev. 2, and RG 1.100, Rev. 4. For EMC qualification testing, MELCO proposed using the specified IEC 61000 series standards as listed in Section 4.3.1.3 of this SE, which are endorsed in RG 1.180, Rev. 2.

The NRC staff concluded that the use of these updated standards is acceptable because the NRC staff endorsed those standards in the updated RG 1.180, Rev. 2 to be acceptable.

However, as MELCO did not submit EQ test results and pertinent supporting documentation for Phase 1 review, compliance with Clause 5.4 on EQ of IEEE Std. 7-4.3.2-2016 remains a generic open item to be addressed in Phase 2 review. More information is available in Generic Open Items 6.1.2 and 6.1.3 in Section 6.0 of this SE.

4.3.9.2 Clause 5.5, System Integrity The MELTAC Platform in Rev. 3 of the TR includes a new PIF module that implements priority logic. As stated in Rev. 3 of the TR, this module uses state-based logic to ensure that either the primary (safety) system or a backup (e.g., diverse actuation) system can command a component to its preferred safety state. The logic is implemented on IPL sub-boards, mounted on the PIF module, that respond directly to external contact inputsindependent of MELTAC controller outputs. Various IPL sub-boards exist for different components (e.g., switchgears, solenoid valves) and are composed of discrete logic integrated circuits (IC), not software, and are fully testable. As such, the IPL operation is deterministic and free of potential CCF hazards.

In the MELTAC Platform in Rev. 3 of the TR, the PIF module corresponds to the priority function. ((

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION

)).

((

)).

Based on the evaluation above, the NRC staff determines that the MELTAC Platform in Rev. 3 of the TR complies with Clause 5.5.4 of IEEE Std. 7-4.3.2-2016 with respect to priority functions performed by the PIF module. However, potential hazards could still be introduced at the application level during specific implementations. Additionally, while the PIF module may help mitigate CCF concerns, these must still be addressed at the application level. More information is available in PSAI 6.2.6 in Section 6.0 of this SE.

Section 4.3.2.5 of the MELTAC Platform in Rev. 3 of the TR states that the ((

)). The NRC staff determines that neither Section 3.3 of the MELTAC Platform ISG-04 Conformance Analysis, Rev. 2 (Ref. 16), nor Section A.1 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 (Ref. 22) addressed the priority functions performed by the ((

)). As such, the NRC staff determined that how the ((

))

conforms to the guidance of Clause 5.5.4 of IEEE Std. 7-4.3.2-2016 is a plant-specific action and is contained in PSAI 6.2.4.

4.3.9.3 Clause 5.6, Independence As discussed in Rev. 3 of the TR, the application of control network is expanded to be used as an interface between safety-related systems and non-safety-related systems. As such, communication independence must be established between the MELTAC-based safety-related platform modules and non-safety-related systems to ensure Clause 5.6.3 of IEEE Std. 603-1991 and GDC 24 are met. GDC 24 requires that, in part, the protection system which is to be separated from control systems to the extent that failure of any single control system component or channel will leave a system intact satisfies the reliability, redundancy, and independent requirements of the protection system. RG 1.152, Rev. 4 endorses IEEE 7-4.3.2-2016 with clarifications to provide regulatory guidance on how independence criteria can be met when interfacing between safety-related and non-safety-related systems. (More details are available in Section C.1.b (2) of RG 1.152, Rev. 4).

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION For the expanded use of the control network between safety-related and non-safety-related systems, Subsection 4.3.2 of Rev. 3 of the TR states that the control network is used to communicate non-safety data between the non-safety system and one or more safety divisions.

This section of the TR also states that the specific interdivisional communication data is application specific. The typical types of interdivisional communication between safety and non-safety are as follows: (1) process signals from non-safety controllers to manually control the safety components of each division and (2) alarm or status information from the safety components or safety instrumentation to non-safety controllers.

Clause 5.6 of IEEE Std. 7-4.3.2-2016 states, in part, that the safety function of each safety channel shall be protected from adverse influence from outside the division of which that channel is a member. Information and signals originating outside the division shall not be able to inhibit or delay the safety function of that division. This protection shall be implemented within the affected division and shall not, itself, be affected by any condition or information from outside the affected division. As stated in Section 3.1.2 of MELTACs Platform ISG-04 Conformance Analysis, Rev. 2, ((

)). Given that functional independence is not addressed at the platform level, the NRC staff determines that a plant-specific action is required to address how functional independence is maintained to demonstrate conformance to Clause 5.6 of IEEE Std. 7-4.3.2-2016. This plant-specific action is contained in PSAI 6.2.13.

4.3.9.3.1 Clause 5.6.4.1, Buffering Function/Circuit Section 4.3.2.5 of Rev. 3 of the TR for the MELTAC platform states that ((

)). Section 4.3.2.1 of Rev. 3 of the TR states that All received data is relayed to the adjacent nodes by the communication controller within the control network I/F module, until the data has been related to all nodes. ((

)). The communication controller also places the received data in 2-port memory for processing by the CPU module in its node. The 2-port memory contains designated memory locations for the complete data package sent for each node on the control network. ((

)).

During its own deterministic cycle, the CPU module reads data only from the memory location in 2-port memory that corresponds to the network nodes that send that that is relevant to its application software. The deterministic cycles of the communication controller and CPU module are completely independent. ((

)).

Section A.2.1 of MELCOs Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 provides an analysis of how the control network conforms to each portion

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION of Clause 5.6.4.1 of IEEE Std. 7-4.3.2-2016. The NRC staffs evaluation of each clause is discussed below:

Clauses 5.6.4.1.a and 5.6.4.1.b Sections A.2.1.1 and A.2.1.2 states that ((

)). Based on the use of a separate communication and function processors, the NRC staff determines that the above features adequately demonstrate conformance to Clauses 5.6.4.1.a and 5.6.4.1.b of IEEE Std. 7-4.3.2-2016.

Clause 5.6.4.1.c Sections A.2.1.3 states that ((

)). Based on the use of ((

)), the NRC staff determines that this feature conforms to Clause 5.6.4.1.c.

However, the NRC staff evaluated the communications faults for conformance with Clause 5.6.4.2 of IEEE Std. 7-4.3.2-2016 in Section 4.3.9.3.2 of this SE, which identified PSAI 6.2.11 to address communication faults.

Clause 5.6.4.1.d Section A.2.1.4 states that ((

)). Based on the classification of equipment used for communication as safety-related, the NRC staff determines that the expanded use of the control network as described in Rev. 3 of the TR conforms to Clause 5.6.4.1.d of IEEE Std. 7-3.4.2-2016. However, the NRC staff determines that the design, qualification and fabrication of this equipment is contingent upon the NRC staffs evaluation of the Quality Manual, Rev. 2, which is outside the scope of this phase of the review of the MELTAC Platform in Rev. 3 of the TR. As such, the evaluation for full conformance to Clause 5.6.4.1.d is subject to the successful closure of Generic Open Item 6.1.5.

Clauses 5.6.4.1.e and 5.6.4.1.f Sections A.2.1.5 and A.2.1.6 state that ((

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION

)). The NRC staff determined the use of the ((

))

ensures that the safety function has priority access to the buffer function. However, the NRC staff notes that there is no change to Section 4.4 on Response Time shown in the MELTAC Platform in Rev. 3 of the TR. Given that the expanded function of the control network and its associated changes may impact the response time methodology, the NRC staff determines that a plant-specific action is required to address these clauses of IEEE Std 7-4.3.2-2016 on response time. More details are available in PSAI 6.2.14 in Section 6.0 of this SE. As such, the NRC staff determines that full conformance to Clauses 5.6.4.1.e and 5.6.4.1.f of IEEE Std. 7-4.3.2-2016 is subject to the successful resolution of PSAI 6.2.14.

Clause 5.6.4.1.g Section A.2.1.7 states that ((

)). Given that the approval of the updates to the MELTAC Platform SPM is contingent upon the resolution of Generic Open Item 6.1.5, the NRC staff determines that conformance to Clause 5.6.4.1.g of IEEE Std. 7-4.3.2-2016 is subject to the successful resolution of Generic Open Item 6.1.5.

Clause 5.6.4.1.h Section A.2.1.8 states that ((

)). Table 3 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 states that compliance with Clause 5.1, Single-Failure Criterion, of IEEE Std. 603-1991 is an application-specific requirement. Given that compliance with Clause 5.1 of IEEE Std. 603-1991 is application specific, the NRC staff identified PSAI 6.2.5 to address compliance with IEEE Std. 603-1991. Therefore, the NRC staff determines that conformance to Clauses 5.6.4.1.h is subject to the successful resolution of PSAI 6.2.5.

Based on the above evaluation, the NRC staff determines that Rev. 3 of the TR conforms to Clauses 5.6.4.1.a and 5.6.4.1.b of IEEE Std. 7-4.3.2-2016. The evaluation of full conformance to (1) Clauses 5.6.4.1.c, 5.6.4.1.e, 5.6.4.1.f, and 5.6.4.1.h is dependent on successful closure of the plant-specific actions identified in PSAIs 6.2.11, 6.2.14, and 6.2.5, and (2) Clauses 5.6.4.1.d and 5.6.4.1.g is dependent on successful resolution of Generic Open Item 6.1.5.

4.3.9.3.2 Clause 5.6.4.2, Communications Independence Section 4.3.2 of Rev. 3 of the TR, states, in part, that the control network can also be used to communicate non-safety data between different divisions. However, Clause 5.6.4.2 of IEEE Std. 7-4.3.2-2016, which is endorsed in RG 1.152, Rev. 4, states, in part, that a safety channel shall not receive any communication from outside its own safety division unless that communication supports or enhances the performance of the safety function. The NRC staff issued RAI No. 6 asking the MELCO to provide additional information to clarify how the control network is used to communicate non-safety data between different divisions and how interdivisional communication from non-safety nodes to a safety channel supports or enhances the performance of the safety function.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION In its RAI response (Ref. 9), MELCO states, in part, that the MELTAC platform has a data link which can be used for interdivisional communication between safety divisions and a control network which can be used for interdivisional communication between the non-safety system and one or more safety divisions. These capabilities can support human tasks via multi-divisional VDUs by reducing burden, reducing the likelihood of human errors, and the use of advanced graphical user interfaces. There is no interdivisional communication between safety divisions via the control network, and MELCO made conforming changes in the RAI response which need to be incorporated in the approved version of the MELTAC Platform in Rev. 3.

However, the NRC staff determines that the signals to be communicated to the safety divisions from the non-safety nodes, and whether they support or enhance the performance of the safety function, are application specific and should be addressed at the application level. A plant-specific action regarding how the interdivisional communication between safety divisions and non-safety nodes via the control network support or enhance the performance of the safety function is contained in PSAI 6.2.4.

Section A.2.2 of MELCOs Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how the MELTAC platform conforms to Clause 5.6.4.2 of IEEE Std. 7-4.3.2-2016. The NRC staff evaluated the information presented in this section specific to the expanded use of the control network in Rev. 3 of the MELTAC TR, as described below.

Clause 5.6.4.2.a Section A.2.2.1 of MELCOs Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 states that ((

)). Because neither the ((

)), the NRC staff determines that the expanded use of the control network conforms to Clause 5.6.4.2.a of IEEE Std. 7-4.3.2-2016.

Clause 5.6.4.2.b Section A.2.2.2 of MELCOs Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 states that the control network uses only ((

)). The NRC staff reviewed Table A.6-2 of MELCOs Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 and determines that this table only analyzes ((

)). As such, the NRC staff determines that a plant-specific action is needed to address conformance with Clause 5.6.4.2.b of IEEE Std. 7-4.3.2-2016. This plant-specific action is contained in PSAI 6.2.15 in Section 6.0 of this SE.

Clause 5.6.4.2.c Section A.2.2.3 of MELCOs Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 states that ((

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION

)). Although Section A.2.2.3 only referenced Section A.5, which is specific to analysis of incorrect data location for a data link message, the NRC staff reviewed Section A.6, which addresses this analysis for a control network message.

Based on the NRC staffs review of Section A.6, the NRC staff determines that certain data field errors and their impact on the application are dependent on the configuration and use of the data for the expanded use of the control network. As such, the NRC staff determines a plant-specific action is required to address conformance to Clause 5.6.4.2.c of IEEE Std. 7-4.3.2-2016. This plant-specific action is contained in PSAI 6.2.22.

Clauses 5.6.4.2.d, 5.6.4.2.e, 5.6.4.2.f, 5.6.4.2.g, and 5.6.4.2.h The NRC staff determines that these clauses are not applicable to the changes in the MELTAC platform described in Rev. 3 of the MELTAC TR because the expanded use of the control network does not involve any change in capability of the control network to modify the software, addressable constants, setpoints, parameters, and safety logic sequencing.

Clause 5.6.4.2.i Section A.2.2.9 of MELCOs Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 refers to Section A.3 for conformance to Clause 5.6.4.2.i of IEEE Std. 7.4.3.2-2016 with respect to analysis of communication faults identified in Clause 5.6.4.2.i.

The NRC staff noted that in Section 3.2 of the MELTAC Platform ISG-04 Conformance Analysis, Rev. 1 (Ref. 15), it states, in part, that...Control Network fault may affect the safety function However, in Section 4.3.2 of the MELTAC Platform in Rev. 3 of the TR, it states, in part, that Inter-divisional communication for safety-related functions is not implemented in the Control Network. The NRC staff issued RAI No. 8 to request additional information to clarify the inconsistent description for the use of the control network. In RAI No. 8 response (Ref. 7),

MELCO states, in part, that the control network is not used for interdivisional communication between safety divisions. The control network is used for interdivisional communication between the non-safety system and one or more safety divisions, which is restricted to non-safety data only. Safety-related communication between safety divisions is provided by the data link, not the control network.

In addition, MELCO clarified in the response to RAI No. 8 that the statement Control Network fault may affect the safety function in Section 3.2 of the MELTAC Platform ISG-04 Conformance Analysis does not mean that safety function is transmitted by inter-division communication via the Control Network. This statement is meant as a non-safety and safety divisions can be connected through the network, where the potential for interdivisional communication faults via the Control Network (non-safety) must be evaluated to ensure they do not affect the safety functions. This evaluation is provided in Section 3.2.6 in MELTAC Platform ISG-04 Conformance Analysis, which concludes that postulated faultsin the non-safety and safety interdivisional communication provided by the Control Network do not affect the safety functions provided by the safety division. The NRC staff reviewed the response to RAI No. 8 in the context of the referenced Section 3.2.6 in the MELTAC Platform ISG-04 Conformance Analysis, Rev. 2 regarding communication faults, where Section 3.2.6 states that ((

)). However, Section 4.3.2 of Rev. 3 of the TR states that The specific interdivisional communication data is application specific. The typical types of interdivisional communication between safety and non-safety are as follows: Process signals

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION from non-safety controllers to manually control the safety components of each division. Further, Figure 4.3-6, Operational Signal Flow from S-VDU/Non-safety nodes, in Rev. 3 of the TR indicates that there are operational signals from the non-safety nodes to safety controllers. The NRC staff determines that the description of the expanded use of the control network is inconsistent between Section 3.2.6 of the MELTAC Platform ISG-04 Conformance Analysis, Rev. 2 and Section 4.3.2 of Rev. 3 of the TR regarding the control of safety-related equipment from non-safety nodes, which requires communication fault analysis to be addressed on an application level. As such, a plant-specific action regarding the need to perform analyses is required to ensure that potential interdivisional communication faults from the expanded use of the control network will not impact any safety functions, and therefore, meet the guidance in Clause 5.6.4.2.i of IEEE Std. 7-4.3.2-2016 as contained in PSAI 6.2.11.

Clause 5.6.4.2.j Clause 5.6.4.2.j of IEEE Std. 7-4.3.2-2016 states, in part, that Communication needed to support a safety function shall include provisions for ensuring that received messages are correct and are correctly understood. Such communications should employ error detection coding along with means for dealing with corrupt, invalid, untimely or otherwise questionable data. Section A.2.2.10 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how the MELTAC platform conforms to the Clause 5.6.4.2.j, and states ((

)). Given that Section A.2.3.1 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2, states that ((

)), and the credited ((

)), as described in that Section A.3.6, is for addressing masquerade data faults, is application specific, the NRC staff determines that a plant-specific action is needed to address Clause 5.6.4.2.j of IEEE Std. 7-4.3.2-2016. This plant-specific action is described in PSAI 6.2.4.

Clause 5.6.4.2.k Clause 5.6.4.2.k of IEEE Std. 7-4.3.2-2016 states that communications that are needed to support a safety function shall be point-to-point by means of a dedicated medium. Alternatively, other communication strategies may be used if they provide the same reliability with documented justification. Section A.2.2.11 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how Clause 5.6.4.2.k of IEEE Std. 7-4.3.2-2016 is met. This section states that ((

)).

However, the NRC staff determines that statement that the ((

)) and the implication that it is not used for interdivisional, including both safety and non-safety communications to support the safety function, are inconsistent with the expanded use of the control network, where Section A 2.3.1 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2, states that

((

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION

)). As such, the NRC staff determines that conformance to Clause 5.6.4.2.k of IEEE Std. 7-4.3.2-2016 is a plant-specific action and is contained in PSAI 6.2.4.

Clause 5.6.4.2.l Section A.2.2.12 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how Clause 5.6.4.2.l of IEEE Std. 7-4.3.2-2016 is met. However, this section only addresses communication via the data link for performing the safety function. As stated in the preceding paragraph of this SE, for the expanded use of control network between safety and non-safety system, whether the non-safety data is used to perform a safety function or not is not performed at the platform level. As such, the NRC staff determines that conformance to Clause 5.6.4.2.l of IEEE Std. 7-4.3.2-2016 is a plant-specific action and is contained in PSAI 6.2.4.

Clause 5.6.4.2.m Section A.2.2.13 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how Clause 5.6.4.2.m of IEEE Std. 7-4.3.2-2016 is met. However, this section only addresses communication via the data link and credits the ((

)). As shown in Figure 4.3-11, Processing by the CPU Module in the Control Network Receiving Process, of Rev. 3 of the TR, the ((

)) is used for operation signal. As stated in the paragraphs above, since the NRC staff determines that the language within Rev. 3 of the TR and Section 3.2.6 in the MELTAC Platform ISG-04 Conformance Analysis, Rev. 2, is inconsistent regarding whether there are operational signals from the non-safety nodes to the safety controllers via the control network, conformance to Clause 5.6.4.2.m is a plant-specific action and is contained in PSAI 6.2.4.

Clause 5.6.4.2.n Section A.2.2.14 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how Clause 5.6.4.2.n of IEEE Std. 7-4.3.2-2016 is met. This section indicates that conformance to Clause 5.6.4.2.n of IEEE Std. 7-4.3.2-2016 is application dependent. As such, the NRC staff identified a plant-specific action regarding conformance to Clause 5.6.4.2.n of IEEE Std. 7-4.3.2-2016 which is contained in PSAI 6.2.16.

Clause 5.6.4.2.o Section A.2.2.15 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how Clause 5.6.4.2.o of IEEE Std. 7-4.3.2-2016 is met by referring to Section A.3 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2. The NRC staff reviewed Section A.3.6 which discusses how various communication faults are detected and addressed for communication via the control network (CN). For CN-12 regarding high-rate messages, MELTAC credits the ((

)), which is discussed more in CN-1.

CN-1 identifies how detected ((

)). Given the application-specific nature of how such failures are addressed, the NRC staff determines that a plant-specific action is needed to address Clause 5.6.4.2.o of IEEE Std. 7-4.3.2-2016, which is contained in PSAI 6.2.17.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Clause 5.6.4.2.p Section A.2.2.16 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how Clause 5.6.4.2.p of IEEE Std. 7-4.3.2-2016 is met. This section only addresses conformance with Clause 5.6.4.2.p of IEEE Std. 7-4.3.2-2016 with respect to error rates of the data link. Given that Section A.2.3.1 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2, states that ((

)), the NRC staff determines that how the expanded use of the CN conforms to Clause 5.6.4.2.p of IEEE Std. 7-4.3.2-2016 is a plant-specific action and is contained in PSAI 6.2.4.

Based on the above evaluation, the NRC staff determines that Rev. 3 of the TR conforms to Clause 5.6.4.2.a of IEEE Std. 7-4.3.2-2016. The evaluation of conformance to Clauses 5.6.4.2.b, 5.6.4.2.c, 5.6.4.2.i, 5.6.4.2.j, 5.6.4.2.k, 5.6.4.2.l, 5.6.4.2.m, 5.6.4.2.n, 5.6.4.2.o, and 5.6.4.2.p of IEEE Std. 7-4.3.2-2016 is dependent on the successful resolution of PSAIs 6.2.4, 6.2.11, 6.2.15, 6.2.16, 6.2.17, and 6.2.22.

4.3.9.3.3 Clause 5.6.4.3, Data Independence Section A.2.3 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 provides an analysis of how the non-safety bus meets the data independence requirements of Clause 5.6.4.3 of IEEE Std. 7-4.3.2-2016. Specifically:

For Clause 5.6.4.3.a of IEEE Std. 7-4.3.2-2016, Section A.2.3.1 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2, states that ((

)).

For Clause 5.6.4.3.b of IEEE Std. 7.4.3.2-2016, Section A.2.3.2 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2, states that this requirement will be met ((

)).

For Clause 5.6.4.3.c of IEEE Std. 7.4.3.2-2016, Section A.2.3.3 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2, states that ((

)).

Given that MELCO stated that conformance to Clauses 5.6.4.3.a-c are application specific, the NRC staff determines that demonstrating the interdivisional communication between safety divisions and non-safety nodes via the CN conforms to Clause 5.6.4.3 of IEEE Std. 7-4.3.2-2016 regarding data independence is a plant-specific action and is contained in PSAIs 6.2.4 and 6.2.6.

Based on the evaluation above in Sections 4.3.9.3 thru 4.3.9.3.3 of this SE, the NRC staff determines that the proposed changes to expand the CN function for the MELTAC Platform in Rev. 3 of the TR, conforms with regulatory guidance on independence in Clause 5.6 of IEEE Std. 7-4.3.2-2016 subject to the successful resolution of PSAIs 6.2.4, 6.2.5, 6.2.11, 6.2.13, 6.2.14, 6.2.15, 6.2.16, 6.2.17, 6.2.22. and closure of generic open item 6.1.5.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION 4.3.9.4 Clause 5.7, Capability for Test and Calibration The MELTAC Platform in Rev. 3 of the TR retains the test and calibration capabilities in the approved MELTAC Platform in Rev. 2 of the TR with the addition of built-in self-diagnostic functions in the new EI units. Like previously qualified modules, the NRC staff noted that ((

)). The NRC staff determines that the above built-in self-diagnostic features provide adequate required test and calibration capabilities for the new EI units. But the actual capability for test and calibration for a specific application depends on its design and configuration to meet plant specification, Therefore, based on this evaluation, the NRC staff determines that the self-diagnostic functions of the EI units support compliance with Clause 5.7 on system capability for test and calibration of IEEE Std. 7-4.3.2-2016, subject to the successful closure of PSAI 6.2.7 in Subsection 6.2 of this SE.

4.3.9.5 Clause 5.8, Information Displays

((

)). The MELTAC Platform in Rev. 3 of the TR expands the use of the CN to allow non-safety nodes to control safety components of each division. As such, the NRC staff evaluated the expanded use of the CN for conformance with Clause 5.8.1.a and Clause 5.8.2 of IEEE Std. 7-4.3.2-2016 below.

4.3.9.5.1 Clause 5.8.1.a Clause 5.8.1.a.1 Section A.4.1.1.1 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how the MELTAC platform conforms to Clause 5.8.1.a.1 of IEEE Std. 7-4.3.2-2016. This section states, in part, that for the non-safety nodes, the ((

)). Given that conformance with Clause 5.8.1.a.1 is application specific, the NRC staff determined that a plant-specific action is required. This plant-specific action is contained in PSAI 6.2.18 in Section 6.0 of this SE.

Clause 5.8.1.a.2 Section A.4.1.1.2 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how the MELTAC platform conforms to Clause 5.8.1.a.2 of IEEE Std. 7-4.3.2-2016. This section states, in part, that ((

)). Given that conformance with Clause 5.8.1.a.2 is application specific, the NRC staff determines that a plant-specific action is required. This plant-specific action is contained in PSAI 6.2.18 in Section 6.0 of this SE.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Clause 5.8.1.a.3 Section A.4.1.1.3 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how the MELTAC platform conforms to Clause 5.8.1.a.3 of IEEE Std. 7-4.3.2-2016. This section states that ((

)). Given that conformance with Clause 5.8.1.a.3 is application specific, the NRC staff determines that a plant-specific action is required. This plant-specific action is contained in PSAI 6.2.18 in Section 6.0 of this SE.

Clause 5.8.1.a.4 Section A.4.1.1.4 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how the MELTAC platform conforms to Clause 5.8.1.a.4 of IEEE Std. 7-4.3.2-2016. This section states that ((

)). Given that conformance with Clause 5.8.1.a.4 is application specific, the NRC staff determines that a plant-specific action is required. This plant-specific action is contained in PSAI 6.2.18 in Section 6.0 of this SE.

Clause 5.8.1.a.5 Section A.4.1.1.5 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how the MELTAC platform conforms to Clause 5.8.1.a.5 of IEEE Std. 7-4.3.2-2016. This section states that ((

)). Given that conformance with Clause 5.8.1.a.5 is application specific, the NRC staff determines that a plant-specific action is required as contained in PSAI 6.2.18 in Section 6.0 of this SE.

Clause 5.8.1.a.6 Section A.4.1.1.6 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 describes how the MELTAC platform conforms to Clause 5.8.1.a.6 of IEEE Std. 7-4.3.2-2016. This section states that conformance with Clause 5.8.1.a.6 is application dependent. As such, the NRC staff determines that a plant-specific action is required as contained in PSAI 6.2.18 in Section 6.0 of this SE.

4.3.9.5.2 Clause 5.8.2, Malfunctions and Spurious Actuations Clause 5.8.2.a The NRC staff reviewed Section A.4.2.1 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2, which provides MELCOs analysis regarding conformance with Clause 5.8.2.a of IEEE Std. 7-4.3.2-2016. This section states that ((

)). As such, NRC staff determines that a plant-specific action is required to address Clause 5.8.2.a for the expanded use of the CN, which is contained in PSAI 6.2.19 in Section 6.0 of this SE.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Clause 5.8.2.b The NRC staff reviewed Section A.4.2.2 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2, which provides MELCOs analysis regarding conformance with Clause 5.8.2.b of IEEE Std. 7-4.3.2-2016. This clause states that ((

)). As such, NRC staff determines that a plant-specific action is required to address Clause 5.8.2.b for the expanded use of the CN, which is contained in PSAI 6.2.19 in Section 6.0 of this SE.

Clause 5.8.2.c The NRC staff reviewed Section A.4.2.3 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2, which provides MELCOs analysis regarding conformance with Clause 5.8.2.c of IEEE Std. 7-4.3.2-2016 and determines that this section does not address how many control actions are required to command safety-related plant equipment from non-safety station. This section only addresses operation commands from the S-VDU. As such, the NRC staff determines that a plant-specific action is required to address Clause 5.8.2.c for the expanded use of the CN, which is contained in PSAI 6.2.19 in Section 6.0 of this SE.

Clause 5.8.2.d Section A.4.2.4 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2, which provides MELCOs analysis regarding conformance with Clause 5.8.2.d of IEEE Std. 7-4.3.2-2016, states that ((

)). Given that environmental qualification of non-safety control and display stations are not performed at the MELTAC platform level, the NRC staff determines that a plant-specific action is required to address Clause 5.8.2.d for the expanded use of the CN, which is contained in PSAI 6.2.19 in Section 6.0 of this SE.

Clause 5.8.2.e The NRC staff reviewed Section A.4.2.5 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2, which provides MELCOs analysis regarding conformance with Clause 5.8.2.e of IEEE Std. 7-4.3.2-2016. This section states that ((

)). As such, NRC staff determines that a plant-specific action is required to address Clause 5.8.2.e for the expanded use of the CN, which is contained in PSAI 6.2.19 in Section 6.0 of this SE.

Clause 5.8.2.f The NRC staff reviewed Section A.4.2.6 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2, which provides MELCOs analysis regarding conformance with Clause 5.8.2.f of IEEE Std. 7-4.3.2-2016. This section states that the provision to ((

)). As such, NRC staff determines that a plant-specific action is required to address Clause 5.8.2.f for the expanded use of the CN, which is contained in PSAI 6.2.19 in Section 6.0 of this SE.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Clause 5.8.2.g Section A.4.2.7 of the Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2, which provide MELCOs analysis regarding conformance with Clause 5.8.2.g of IEEE Std. 7-4.3.2-2016, states that ((

)). As such, NRC staff determines that a plant-specific action is required to address Clause 5.8.2.g for the expanded use of the CN, which is contained in PSAI 6.2.19 in Section 6.0 of this SE.

Based on the evaluation above, the NRC staff determines that PSAI 6.2.19 needs to be addressed prior to a determination on whether an application using the MELTAC Platform in Rev. 3 of the TR conforms to the guidance in Clause 5.8.2 of IEEE Std. 7-4.3.2-2016.

4.3.9.6 Clause 5.9, Access Controls While no changes were made to the MELTAC platform for nuclear instrumentation (NI) modules, MELCO proposed using the new EI units as an alternative for processing excore neutron detector signals. The EI system includes an operation panel (EIOP), signal processing unit (EISPU), and power supplies. ((

)).

However, Rev. 3 of the TR did not initially clarify how development of the EI units would be controlled or how access to EIOP would be secured. In response to RAI No. 12, MELCO confirmed that the same software QA process is applied to EI units and that ((

)). The NRC staff concludes that the provided administrative restriction via the controller cabinet door is adequate to meet the requirement on the access control. From this assessment, the NRC staff concluded that these measures ensure compliance with Clause 5.9 of IEEE Std. 7-4.3.2-2016 regarding control of access.

Based on the evaluation above, and prior evaluation in Section 3.11 of the NRC staffs SE for the approved MELTAC Platform in Rev. 2 of the TR, the NRC staff determines that the changes of the new EI units incorporated into the MELTAC Platform in Rev. 3 of the TR can be used to support compliance with relevant guidance on the access controls in IEEE Std. 7-4.3.2-2016 as endorsed in RG 1.152, Rev. 4, subject to applicable limitations, conditions, and open items outlined in Section 6.0 of this SE.

4.3.10.

Conformance with Regulatory Guide 1.152 In Section 3.12 of the SE for the approved MELTAC Platform in Rev. 2 of the TR (Ref. 13), the NRC staff determined that the MELTAC platform complied with regulatory guidance in RG 1.152, Rev. 3, and its endorsed IEEE Std. 7-4.3.2-2003, subject to certain limitations and conditions.

When MELCO submitted the MELTAC Platform in Rev. 3 of the TR to the NRC staff for review in June 2023, the NRC was in the process of updating RG 1.152. Following the publication of RG 1.152, Rev. 4, in July 2023, which endorses IEEE Std. 7-4.3.2-2016, with exceptions and clarifications, MELCO voluntarily submitted a supplemental document titled Summary of Compliance to the RG 1.152, Rev. 4 (Ref. 23). This document provided additional information

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION in order to demonstrate that the MELTAC Platform in Rev. 3 of the TR meets the updated regulatory guidance. The NRC staff evaluates compliance with the applicable provisions of IEEE Std. 7-4.3.2-2016 in Section 4.3.9 of this SE.

The NRC staff noted that in MELCOs Summary of Compliance to the RG 1.152, Revision 4, (Ref. 23) the PIF module used in the MELTAC Platform in Rev. 3 of the TR serves as a priority module, with priority functions implemented in its IPL. The IPL consists of discrete ICs whose operation is independent of software and is 100% testable. As a result, IPL behavior is predictable and repeatable, and the priority function itself does not introduce CCF hazards. At the platform level, the NRC staff concludes from this evaluation that the MELTAC Platform in Rev. 3 of the TR complies with the relevant guidance in Section C.1.b. Clarifications, Subsection 1.3 of RG 1.152, Rev. 4, on priority functions. However, during the development of specific applications, any potential hazards introduced through the implementation of priority functions in a specific safety I&C system based on the MELTAC Platform in Rev. 3 of the TR should be evaluated at the application level. More details are available in PSAI 6.2.12 in Section 6.0 of this SE.

For the expanded function of the CN in the MELTAC Platform in Rev. 3 of the TR, communication between safety divisions and non-safety systems can be configured with a cycle time of either ((

)). Accordingly, the NRC staff determines that the expanded CN is consistent with the data communication capacity guidance in RG 1.152, Rev. 4; however, full conformance to the regulatory positions in RG 1.152, Revision 4, is application specific and must be individually addressed. See PSAIs 6.2.10 and 6.2.20 in Section 6.0 of this SE because the configuration of data communication parameters is application dependent.

Based on this evaluation and the PSAIs documented in Section 4.3.9 of this SE, the NRC staff determines that the changes incorporated into the MELTAC Platform in Rev. 3 of the TR support compliance with the regulatory guidance in RG 1.152, Rev. 4, subject to the limitations and conditions outlined in Section 6.0 of this SE.

5.

SUMMARY

AND CONCLUSIONS The MELTAC Platform in Rev. 2 of the TR was approved by the NRC staff as stated in the SE that was issued in November of 2018. In this SE, the NRC staff evaluated the changes introduced in the MELTAC Platform in Rev. 3 of the TR. These changes include updated and new modules, expanded communication capabilities, revised EQ Standards and criteria, and other modifications.

Based on the Phase 1 review of Rev. 3 of the TR, NRC staff determines that the changes to the MELTAC Platform identified in this SE for this Phase 1 review, when applied under the limitations, conditions, and open items outlined in Section 6.0 of this SE and Section 5.0 of the SE for the approved MELTAC Platform in Rev. 2 of the TR, continue to support compliance with applicable regulatory requirements and guidance for plant-specific applications. This determination applies to the use of the information described in Phase 1 for this MELTAC

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Platform in Rev. 3 of the TR in safety-related applications for nuclear power plants, provided that each application adheres to the specified conditions, addresses all generic open items and PSAIs, and that the safety I&C system is properly installed and operated as described by MELCO.

However, as identified in Section 2.0 above, use of the MELTAC Platform in Rev. 3 of the TR is contingent upon: (1) staffs separate evaluation of the Application SPM (Ref. 19), CGD (Ref. 20), and QA Manual, Rev. 2 (Ref. 26); and (2) staffs evaluation of the information for the Phase 2 review for the MELTAC Platform in Rev. 3 of the TR can be used in safety-related systems.

With respect to the technical evaluation in Section 4.0 of this SE, the NRC staff has determined that the information for the Phase 1 review to support changes to the MELTAC Platform in Rev. 3 of the TR are acceptable for use in safety-related I&C systems, subject to the limitations, conditions, and open items identified in Section 6.0 of this SE.

6.

LIMITATIONS AND CONDITIONS An applicant or a licensee may reference the approved MELTAC Platform in Rev. 3 of the TR provided that the limitations and conditions discussed in this section are satisfied. The conditions and limitations are intended to address generic open items and PSAIs within the NRC staffs SE for Phase 1 of the review of the MELTAC platform Rev. 3. The MELTAC Platform in Rev. 3 of the TR, and the supplemental information identified in this SE, as well as the NRC staffs SE for Phase 1 provide context and basis for the information.

The NRC staff approved the MELTAC platform Rev. 2 of the TR (Ref. 13) with specific limitations and conditions, none of which are resolved in Rev. 3 of the TR (Ref. 5). Therefore, for any safety-related application based on the MELTAC Platform in Rev. 3 of the TR, the generic open items and PSAIs identified in Section 5.0 of the SE for Rev. 2 of the TR remain applicable.

6.1 The following generic open items must be satisfied prior to the approval of the MELTAC Platform in Rev. 3 of the TR:

6.1.1.

Application SPM and CGD: As stated in Section 2.1 of this SE, there is a plan to evaluate the MELTAC Application SPM, Rev. 1 and the Summary of MELTAC Platform CGD Activity, Rev. 1 under a separate review not associated with the Phase 1 or Phase 2 review. These two documents must be concluded to be acceptable by the NRC staff and meet the appropriate regulatory requirements before implementation.

6.1.2.

Updated Modules and Components: This SE covers only the updated modules and components listed in Table 4.2-1 of this SE. For each of the updated modules or components, analysis must be submitted to the NRC staff for review to determine whether the previous qualifications, approved in the SE for Rev. 2 of the TR, are still applicable and remain valid for the MELTAC Platform in Rev. 3 of the TR. If not, re-qualification including compliance with relevant EQ-related requirements must be performed and submitted for NRC staff review.

6.1.3.

New Module and Components: This SE is limited only to the new modules and components listed in Table 4.2-2. All new modules and components must be

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION qualified in accordance with applicable regulations, RGs, and Standards referenced in the MELTAC Platform in Rev. 3 of the TR, and the qualification results must be submitted to the NRC staff for review prior to implementation.

6.1.4.

Phase 2 Review Requirements: This SE only addresses the information submitted under the Phase 1 review for the MELTAC Platform in Rev. 3 of the TR. Items to be submitted for Phase 2 review in a forthcoming application must be reviewed by NRC staff to meet regulatory requirements.

6.1.5.

Quality Manual and Platform Software Development Process: Because the changes in Rev. 3 of the TR are governed by the Quality Manual Based on U.S. Nuclear Regulations, Rev. 2, dated June 2023, and the Quality Manual Based on U.S.

Nuclear Regulations, Rev. 2, has not been evaluated, the Quality Manual Based on U.S. Nuclear Regulations, Rev. 2, must be reviewed and approved by NRC staff to ensure that it is in compliance with the applicable criteria in Appendix B to 10 CFR Part 50.

6.2 The following PSAIs must be satisfied by an applicant or a licensee referencing the MELTAC Platform in Rev. 3 of the TR:

6.2.1.

Safety-related cables used to connect different DI&C safety-related divisions or interface safety-related with non-safety-related systems were not addressed in the Phase 1 review. Applicants or licensees must demonstrate adequate qualifications of such cables for their specific applications.

6.2.2.

The applicant or licensee must demonstrate that the generic qualification envelope for the MELTAC Platform in Rev. 3 of the TR bounds the environmental and service conditions (e.g., temperature, humidity, radiation, electromagnetic compatibility) of the specific installation location(s). The equipment configuration used for qualification testing must be consistent with that to be installed.

6.2.3.

Applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR shall demonstrate compliance with General Design Criteria 21 and 23 based on their specific plant applications and the safety functions performed by their safety I&C

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION systems, including its diagnostic, testing features, and failure modes designed for the specific applications.

6.2.4.

Applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR shall:

6.2.4.1 perform an analysis to ensure that the types of signals transmitted to safety-related divisions from non-safety systems over the control network at the application-level support or enhance safety function performance.

6.2.4.2 perform an analysis that ((

)) meets Clause 5.5.4 of IEEE Std. 7-4.3.2-2016 when it is used for priority functions as CCF countermeasures.

6.2.4.3 describe how interdivisional communications that are needed to support a safety function as specified by 5.6.4.2.j and 5.6.4.2.k of IEEE Std. 7-4.3.2-2016 use the Data Link, and not the Control Network.

6.2.4.4 make an analysis to ensure conformance with regulatory guidance on data communication independence as specified in Clause 5.6.4.2.l, 5.6.4.2.m, and 5.6.4.2.p of IEEE Std. 7-4.3.2-2016.

6.2.5.

This SE does not address a specific application, establish a definitive safety system or protective action, or identify or analyze the impact of credible events including direct and indirect consequences. Applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR shall identify actions and approaches to satisfy each applicable clause in IEEE Std. 603-1991 with consideration of the plant-specific design basis.

6.2.6.

Although the PIF module may help mitigate CCF in MELTAC-based safety systems, potential hazards from using the PIF modules shall be analyzed for plant-specific applications. The potential CCF from the expanded use of CN between non-safety nodes and safety systems shall be analyzed for specific application. In addition, a full plant-specific diversity and defense-in-depth analysis must be performed to address CCF in accordance with applicable NRC regulatory guidance.

6.2.7.

Self-diagnostic capabilities of the MELTAC Platform in Rev. 3 of the TR may support or reduce surveillance testing requirements. However, applicants or licensees must analyze whether those capabilities are sufficient to meet plant-specific technical specification requirements for surveillance testing and address any gaps between self-diagnostic coverage and required testing.

6.2.8.

Non-safety-related control and display functions used to control safety-related equipment for plant-specific applications must be demonstrated to prevent spurious

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION actuations under design basis environmental conditions to which they will be exposed.

6.2.9.

Human factors engineering, which is not addressed at all in this SE, must be evaluated as part of the application-specific review in accordance with applicable NRC regulatory requirements and guidance.

6.2.10.

Applicants or licensees must describe their approach for meeting applicable positions in RG 1.152, Rev. 4, taking into account plant-specific design and safety considerations. As stated in the Summary of Compliance to the RG 1.152, Revision 4 (Ref. 23), many staff regulatory positions in RG 1.152, Rev. 4, are application-specific requirements. While the NRC staff determined that the information for the Phase 1 review to support changes made for the MELTAC Platform in Rev. 3 of the TR complies with applicable staff positions, full conformance to the regulatory positions in RG 1.152, Rev. 4, is application specific and must be individually addressed.

6.2.11.

Although safety functions are not transmitted by interdivisional communication via the CN, non-safety-related system and safety-related divisions can be connected through the CN. However, applicants or licensees must analyze the potential for interdivisional communication faults via the CN (non-safety) to ensure they do not affect the safety functions provided by the safety divisions.

6.2.12.

Applicants or licensees must evaluate any potential hazards introduced through the implementation of priority functions in a specific safety I&C system based on the MELTAC Platform in Rev. 3 of the TR.

6.2.13.

Applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR shall ensure that functional independence is addressed for their plant-specific applications to address conformance with regulatory guidance in Clause 5.6 of IEEE Std. 7-4.3.2-2016.

6.2.14.

Because plant-specific safety I&C system response time depends on its configuration using various MELTAC platform features in Rev. 3 of the TR, applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR shall perform analysis of the response time for their applications to ensure to meet relevant requirement in IEEE Std. 603-1991 and address conformance with corresponding guidance in IEEE Std. 7-4.3.2-2016.

6.2.15.

Because of the expanded use of the CN between safety and non-safety systems, applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR shall perform an analysis for their specific applications on unrecognized messages from non-safety nodes to address conformance with regulatory guidance in Clause 5.6.4.2.b of IEEE Std. 7-4.3.2-2016.

6.2.16.

Applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR shall analyze potential hazards due to the interdivisional data from the expanded use of

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION the CN and then ensure conformance with regulatory guidance in Clause 5.6.4.2.n in IEEE Std. 7-4.3.2-2016 for their plant-specific applications.

6.2.17.

Applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR shall conduct analysis to address the conformance with regulatory guidance in Clause 5.6.4.2.o in IEEE Std. 7-4.3.2-2016 because some detected communication failures may need to be handled by the application program.

6.2.18.

Because of the expanded use of the CN between safety and non-safety systems, guidance on restrictions in Clause 5.8.1.a of IEEE Std. 7-4.3.2-2016 shall be met when non-safety stations are used to control the operation of safety-related equipment. Applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR shall conduct analysis to address the conformance with guidance in Clause 5.8.1.a of IEEE Std. 7-4.3.2-2016.

6.2.19.

Because of the expanded use of the CN between safety and non-safety systems, non-safety nodes or control stations could be used to control the operation of safety-related equipment, applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR shall conduct analysis to ensure conformance with the guidance in Clause 5.8.2 of IEEE Std. 7-4.3.2-2016 for their specific applications using the non-safety systems to control the safety systems.

6.2.20.

Because of the expanded use of the CN between safety and non-safety systems, applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR shall perform an analysis for their specific applications to verify that the configuration of the data communications shall be in accordance with the values shown in Table 4.3-1 of Rev. 3 of the TR to verify compliance with relevant regulatory requirements in IEEE Std. 603-1991 and address conformance with the guidance in RG 1.152, and its endorsed IEEE Std. 7-4.3.2-2016 regarding the deterministic actions of the safety I&C systems.

6.2.21.

Applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR shall ensure compliance with regulatory requirements in GDC 19 if applicable for their specific applications because the S-VDUs or non-safety control stations which could be used to meet GDC 19 are application dependent.

6.2.22.

Because of the expanded use of the CN between safety and non-safety systems, applicants or licensees referencing the MELTAC Platform in Rev. 3 of the TR shall perform an analysis for their specific applications of the configuration and use of the data from non-safety nodes by the safety equipment to address conformance with the regulatory guidance in Clause 5.6.4.2.c of IEEE Std. 7-4.3.2-2016.

7.

REFERENCES

1.

Sneddon, Jay, Mitsubishi Electric Corporation (MELCO) transmittal letter to U.S. Nuclear Regulatory Commission (NRC), Mitsubishi Electric Corporation (MELCO) Submittal of a Revision to MELTAC Topical Report, June 16, 2023, (Agencywide Documents Access and Management System (ADAMS) Accession No. ML23167C167 (pkg);

ML23167C168).

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION

2.

MELCO transmittal letter to NRC, Mitsubishi Electric Corporation (MELCO) Submittal of Support Documents for MELTAC Topical Report, (JEXU-1041-8570) for Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2 (compliance with IEEE Std. 7-4.3.2 2016 edition) Rev.1, (JEXU-1041-1018-P (R1)), March 15, 2024 (ML24075A310 (pkg); ML24075A312 (report), ML24075A314 (transmittal ltr)).

3.

MELCO transmittal letter to NRC, Mitsubishi Electric Corporation (MELCO) Submittal of Support Documents for MELTAC Topical Report, (JEXU-1041-8572) for Summary of Compliance to the Regulatory Guide 1.152 Revision 4, (JEXU-1041-1162 P (R0)), April 25, 2024 (ML24117A208 (pkg); ML24117A209 (transmittal ltr), ML24117A211 (report)).

4.

MELCO transmittal letter to NRC, Mitsubishi Electric Corporation (MELCO) Submittal of Support Documents for MELTAC Topical Report, (JEXU-1041-8573) for Collection of Editorial Changes on MELTAC LTR and Its Supporting Documents by Revision of Regulatory Guide 1.152 and IEEE Std. 7-4.3.2, Revision 0 (JEXU-1041-2146-P (R0)),

May 16, 2024 (ML24137A150 (pkg); ML24137A151 (transmittal ltr), ML24137A153 (report)).

5.

MELCO topical report, Safety System Digital Platform - MELTAC - Topical Report, (JEXU-1041-1008-P, (R3)), [Revision 3 of the Topical Report], June 2023, (ML23167C170).

6.

NRC email to MELCO, Final Request for Additional Information - Mitsubishi Electric Power Products, Inc., (MEPPI) JEXU-1041-1008, Safety System Digital Platform -

MELTAC, January 19, 2024 (ML24010A022).

7.

MELCO transmittal letter to NRC, Mitsubishi Electric Corporation (MELCO) Submittal of RAI Response for MELTAC Topical Report (JEXU-1041-8571), March 15, 2024 (RAI Nos. 1 - 9) (ML24078A429 (pkg); ML24078A444 (transmittal ltr)).

8.

NRC Public Observation Meeting Summary, U.S. Nuclear Regulatory Commission Summary of the May 29, 2024, Observation Public Meeting to discuss Mitsubishi Electric Companys Responses to the Request for Additional Information Questions and Supplement Response, July 31, 2024 (ML24206A078).

9.

MELCO letter to NRC, Mitsubishi Electric Corporation (MELCO) Submittal of Revised Responses to RAIs for MELTAC Topical Report, (JEXU-1041-8575), (RAI Nos.1, 6, &

7), August 23, 2024 (ML24236A705 (pkg); ML24236A706 (transmittal ltr)).

10.

NRC email to MELCO, Final Request for Additional Information (RAI) JEXU-1041-1008 Safety System Digital Platform - MELTAC (RAI Nos.10-14) October 23, 2024 (ML24296B175 (pkg); ML24296B177 (email); ML24296B179 (Enclosure 1, nonpublic);

ML24296B178 (Enclosure 2, nonpublic)).

11.

MELCO transmittal letter to NRC, MELCO Submittal of RAI Responses for MELTAC Topical Report (RAI Nos. 10-14) (JEXU-1041-8576) November 12, 2024 (ML24317A160 (pkg); ML24317A161 (transmittal ltr).

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION

12.

NRC letter to MELCO, The U.S. Nuclear Regulatory Commission Staffs Revised Schedule for the Review of Mitsubishi Electrical Corporations Topical Report (JEXU-1041-1008), Revision 3, Safety System Digital Platform - MELTAC - Topical Report, December 23, 2024 (ML24351A141).

13.

MELCO Topical Report, (JEXU-1041-1008-P (R2)) Approved (-A), Safety System Digital Platform - MELTAC - Topical Report [includes Final Safety Evaluation for Safety System Digital Platform - MELTAC - Topical Report], May 10, 2019 [Revision 2 of the Topical Report] (ML19135A097).

14.

MELCO Submittal, Slides for Forthcoming Meeting with Mitsubishi Electric Corporation (MELCO), May 10, 2023 (ML23116A140).

15.

MELCO Submittal, MELTAC Platform ISG-04 Conformance Analysis, Rev. 1 (JEXU-1041-1015-P), June 30, 2023 (ML23167C167 (pkg); ML23167C172 (report)).

16.

MELCO Submittal, MELTAC Platform ISG-04 Conformance Analysis, Rev. 2 (JEXU-1041-1015-P), March 5, 2025 (ML25069A450 (pkg); ML25069A453 (report)).

17.

MELCO Submittal, MELTAC Platform Software Program Manual, Rev. 1 (JEXU-1041-1016-P), June 30. 2023. (ML23167C167 (pkg); ML23167C174 (report)).

18.

MELCO Submittal, MELTAC Platform Software Program Manual, Rev. 2 (JEXU-1041-1016-P), March 5, 2025. (ML25069A450 (pkg); ML25069A455 (report)).

19.

MELCO Submittal, MELTAC Platform Application Software Program Manual, Rev. 1 (JEXU-1041-1032-P), June 30, 2023 (ML23188A208 (pkg); ML23188A211 (report)).

20.

MELCO Submittal, Summary of MELTAC Platform CGD Activity, Rev. 1 (JEXU-1041-1124-P), June 30, 2023. (ML23188A208 (pkg); ML23188A213 (report)).

21.

MELCO Submittal, Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 1 (JEXU-1041-1018-P (R1)), March 15, 2024 (ML24075A310 (pkg);

ML24075A312 (report)).

22.

MELCO Submittal, Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 (JEXU-1041-1018-P (R2)), March 5, 2025 (ML25069A450 (pkg);

ML25069A457 (report)).

23.

MELCO Submittal, Summary of Compliance to the Regulatory Guide 1.152 Revision 4, Rev. 1 (JEXU-1041-1162-P), March 5, 2025 (ML25069A450 (pkg); ML25069A459 (report)).

24.

MELCO Transmittal Letter, Mitsubishi Electric Power Products, Inc., Additional Supporting Documents for MELTAC Topical Report Review, July 7, 2023 (ML23188A208 (pkg); ML23188A209 (transmittal ltr)).

25.

MELCO Transmittal letter, Mitsubishi Electric Corporation (MELCO) Confirmation of Review Request for Support Documents for MELTAC Topical Report, December 10, 2024 (ML24347A112 (transmittal ltr)).

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION

26.

MELCO Submittal, ESC Procedure N-G000-P, Quality Manual Based on U.S. Nuclear Regulations, Rev. 2, June 30, 2023 (ML23167C167 (pkg); ML23167C180 (report)).

27.

NRC Inspection Report No. 99901410/2011-202 And Notice of Nonconformance, March 14, 2012 (ML12067A210).

28.

Digital Instrumentation and Controls Interim Staff Guidance DI&C-ISG-06, Licensing Process, Revision 2 Final, December 2018 (ML18269A259).

8.

LIST OF ACRONYMS Acronym Definition AI Analog Input ANSI American National Standards Institute AO Analog Output ASME American Society of Mechanical Engineers BTP Branch Technical Position CCF Common Cause Failure CFR Code of Federal Regulations CPU Central Processing Unit CRC Cyclic Redundancy Check DAS Diverse Actuation System DI Digital Input DO Digital Output DSP Digital Signal Processor ECC Error Correcting Code EMC Electromagnetic Compatibility EMI Electromagnetic Interference EMS Electromagnetic Susceptibility EQ Equipment Qualification ESC Energy Systems Center ESD Electrostatic Discharge EUT Equipment under Test E/O Electrical/Optical EI Excore Nuclear Instrumentation FET Field Effect Transistor FPGA Field-Programmable Gate Array F-ROM Flash Read Only Memory F/W Firmware GBD Graphical Block Diagram Gbps Gigabits per Second GDC General Design Criteria (Criterion)

GUI Graphical User Interface HFE Human Factor Engineering ID Identification IEC Electrotechnical Commission IEEE Institute of Electrical and Electronics Engineers IPL Interposing Logic

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Acronym Definition ITAAC Inspections, Tests, Analyses, and Acceptance Criteria I/O Input/Output I&C Instrumentation and Control JEC Japanese Electrotechnical Committee kHz Kilohertz mA Milliampere Mbps Megabits per Second MCR Main Control Room MELCO Mitsubishi Electric Corporation MELTAC Mitsubishi Electric Total Advanced Controller MEPPI Mitsubishi Electric Power Products Inc.

MRP MELTAC MELTAC Re-evaluation Program NC Normally Closed NI Nuclear Instrumentation NO Normally Open NRC Nuclear Regulatory Commission PIF Power Interface POL Problem Oriented Language QA Quality Assurance QAP Quality Assurance Program PCS Plant Control System PSAI Plant-Specific Action Item PSS Plant Safety System RCP Reactor Coolant Pump RFI Radio Frequency Interference RG Regulatory Guide RTD Resistance Temperature Detector SDOE Secure Development and Operational Environment SIntP Software Integration Plan SInstP Software Installation Plan SMP Software Management Plan SPM Software Program Manual SQAP Software Quality Assurance Plan SS Safe Shutdown Earthquake SSP Software Safety Plan S-VDU Safety VDU SVVP Software Verification and Validation V

Volt, SI unit for electrical potential difference VDU Visual Display Unit V&V Verification and Validation Principal Contributors: Jack Zhao Deanna Zhang Calvin Cheung Date: January 14, 2026

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION Resolution of Comments for the U.S. Nuclear Regulatory Commissions Draft Safety Evaluation of Mitsubishi Electric Total Advanced Controller Platform - MELTAC Revision 3, Phase 1 On July 2, 2025, the U.S. Nuclear Regulatory Commission (NRC) staff submitted a copy of the draft safety evaluation (DSE)

(Agencywide Documents Access and Management System (ADAMS) Accession No. ML25139A555) for the MELCO Topical Report (TR) Mitsubishi Electric Total Advanced Controller Platform - MELTAC, Revision 3, Phase 1 for comments by MELCO (transmittal email - ML25139A553).

The NRC staff received a total of 71 comments regarding the DSE for the subject TR, including: (1) a total of 68 comments from MELCO from the original proprietary review of the DSE received on August 19, 2025, and (2) 3 new comments in addition to the original 68 from MELCO following a public meeting to discuss the comments (ML25328A230) received on September 26, 2025. The comments received from MELCO are available at ADAMS Accession No. ML25349A173.

The comments and the NRC staffs basis for addressing and resolving comments received on the DSE for the subject TR are provided in the following table.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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19 48-56 Clarification Please delete:

All MELTAC modules and components are now managed under its Appendix B QA program.

In Section 6.0, Quality Assurance and Life Cycle of the MELTAC platform in Rev. 3 of the TR, there is one change made to use IEEE Std. 1028-2008, instead of the original IEEE Std. 1028-1997.

Although the NRC staff endorses the use of IEEE Std. 1028-2008 in RG 1.168, Rev. 2 as providing an approach acceptable to the NRC staff for carrying out software reviews, inspections, walkthroughs, and audits, however, Rev. 3 of the TR did not address the staff regulatory positions in RG 1.168, Rev. 2.

Therefore, NRC staff determines The change from IEEE Std. 1028-1997 to 2008 was a correction of a typographical error.

See Revision History of TR and find all other changes were already made in TR R1.

The staff agrees that the comment is valid. The staff has confirmed the typographical error and will delete the specified portion.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC that conformance to IEEE Std. 1028-2008, as endorsed by RG 1.168, Rev. 2 is subject to successful closure of Generic Open Item 6.1.5 in Section 6.0 of this SE to ensure compliance with GDC 1, Appendix B to 10 CFR Part 50, and other requirements.

2 21 3-5 Clarification Please delete:

Corrected the edition year of the American National Standards Institute/American Society of Mechanical Engineers Nuclear Quality Assurance Standard (ANSI/ASME NQA-1) from 1983 to 1994 to be consistent with the MELTAC Platform in Rev. 3 of the TR.

The platform was never based on NQA-1 1983. The reference to 1983 is a typographical error.

The staff agrees that the comment is valid. The staff has confirmed the typographical error and will delete the specified portion.

3 21 13-15 Clarification Please delete:

The platform was never based on The staff agrees that the comment is

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC The NRC staff did not review the change to the year of NQA-1 Standard from 1983 to 1994, which is impacted by revisions to the Quality Manual, Rev. 2 and subject to Generic Open Item 6.1.5.

NQA-1 1983. The reference to 1983 is a typographical error.

valid. The staff has confirmed the typographical error and will delete the specified portion.

4 21 15 Clarification Please delete:

other The platform was never based on NQA-1 1983. The reference to 1983 is a typographical error.

The staff agrees that the comment is valid. The staff has confirmed the typographical error and will delete the specified portion.

5 38 49-52 Clarification Please delete:

The change from ANSI/ASME NQA-1 from 1983 to 1994 made in the MELTAC platform SPM shall be reviewed for The platform was never based on NQA-1 1983. The reference to 1983 is The staff agrees that the comment is valid. The staff has confirmed the typographical error

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC compliance with GDC 1 and Appendix B to 10 CFR Part 50.

Conformance with IEEE Std. 1028-2008 and regulatory positions in its endorsing RG 1.168, Rev. 2, shall be addressed.

a typographical error.

The change from IEEE Std. 1028-1997 to 2008 was a correction of a typographical error.

See Revision History of TR and find all other changes were already made in TR R1.

and will delete the specified portion.

6 40 17-19 Clarification The term functional independence is only referenced in Annex-G of IEEE Std. 7-4.3.2-2016 and is not well defined.

MELCO understood functional independence is data The staff did not find MELCO Comment 6 to be valid for implementation.

Specifically, MELCO used the term functional

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC independence in Clause 5.6.4.3 of IEEE Std. 7-4.3.2-2016.

independence in Section 3.1.2 of MELTACs Platform ISG-04 Conformance Analysis, Rev. 2.

The staff will not make changes to the SE based on this comment.

7 30 16-26 Clarification Please revise as follows:

Section A.2.2.2 of MELCOs Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 states that the control network uses only ((

The Draft SE does not include all of the findings that should be made with respect to the conformance evaluations submitted by MELCO.

The staff did not find MELCO Comment 7 to be valid for implementation.

Specifically, the use of application specific wording used in Appendix A of MELCOs Summary of Compliance to the

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC

)). The NRC staff reviewed Table A.6-2 of MELCOs Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 and determines that this table only analyzes ((

)) As such, the NRC staff determines that a plant-specific action is needed to address ((

))

for conformance with Clause 5.6.4.2.b of IEEE Std. 7-4.3.2-2016. This plant-specific action is contained in PSAI 6.2.15 in Section 6.0 of this SE. - -

For example, Section A.2.2.2 of JEXU-1041-1018 states:

Unrecognized messages and data are identified and discarded by the receiving system and not used within the safety logic.

Table A.5-2 (Data Link) and Table A.6-2 (Control Network) describe the detection and handling of potentially incorrect/unrecogniz ed data in every message field.

IEEE Std. 603 and IEEE Std. 7-4.3.2, Rev. 2 necessitates the phrasing used by the NRC staff.

This was discussed with MELCO in the public meeting to discuss MELCOs comments on the draft SE on September 18, 2025. The staff will not make changes to the SE based on this comment.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC Table A.6-2 in JEXU-1041-1018 addresses incorrect/unrecogniz ed data in every field in a Control Network message as would be expected for Clause 5.6.4.2.b in IEEE Std. 7-4.3.2-2016 and concludes impact by potential incorrect/

unrecognized data in all fields except Constant-cycle Data Address are mitigated by the platform level.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC However, the Draft SE only mentions one field, Constant-cycle Data Address, and requires an applicant to provide a response to PSAI 6.2.15 for addressing the entirety of Clause 5.6.4.2.b, as if the balance of Table A.6-2 in JEXU-1041-1018 had not been submitted. It may be that staff finds PSAI 6.2.15 necessary for addressing errors in the Constant-cycle Data Address field

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC in Control Network messages because the Acceptability of Impact column in Table A.6-2 for this field remarks that it is an application-specific issue, but the staff finding on Clause 5.6.4.2.b ignores the balance of Table A.6-2, leaving future applicants with an unreasonable burden in light of the submittals MELCO provided for this review.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC 8

13 53-55 Proprietary Please consider the content within

((...)) as proprietary information.

Page 13 line 53: controller processor malfunctions. ((...

...)) Page 13 line 55: (end of line)

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

9 16 43-44 Proprietary Please consider the content within

((...)) as proprietary information.

Page 16 line 43: excore neutron detectors. ((...

...)) Page 16 line 44: However, the generic The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

10 18-19 47 (page

18)

Proprietary Please consider the content within

((...)) as proprietary information.

Page 18 line 47: the TR provides

((...

...)) Page 19 line 21: (end of line)

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC 21 (page

19) 11 19 27-28 Proprietary Please consider the content within

((...)) as proprietary information.

Page 19 line 27: Additionally, ((...

...)) Page 19 line 28: The NRC staff did not The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

12 20 10-12 Proprietary Please consider the content within

((...)) as proprietary information.

Page 20 line 10: four new modules: ((...

...)) Page 20 line 12: As stated in The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

13 21-22 41(page

21)

Proprietary Please consider the content within

((...)) as proprietary information.

The staff agrees that the comment is valid. The staff will incorporate the change

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC 10(page

22)

Page 21 line 41: (beginning of line) ((...

...)) Page 22 line 10: (end of line) recommended in the comment.

14 22 25-40 Proprietary Please consider the content within

((...)) as proprietary information.

Page 22 line 25: noted that the ((...

...)) Page 22 line 40: (end of line)

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

15 22 43-44 Proprietary Please consider the content within

((...)) as proprietary information.

Page 22 line 43: concluded that

((...

...)) Page 22 line 44: However, for plant-specific The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC 16 23 1-7 Proprietary Please consider the content within

((...)) as proprietary information.

Page 23 line 1: of the TR. ((...

...)) Page 23 line 7: (end of line)

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

17 23 10-13 Proprietary Please consider the content within

((...)) as proprietary information.

Page 23 line 10: failures are detected. ((...

...)) Page 23 line 13: Therefore, based on The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

18 24 32-35 Proprietary Please consider the content within

((...)) as proprietary information.

Page 24 line 32: of the TR, ((...

...)) Page 24 line 35: This The staff partially agrees with the comment.

Specifically, the wording used to describe the requirements within the IEEE standard

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC clause being referenced is not considered proprietary. This was discussed with MELCO staff on November 26, 2025.

The staff will incorporate the recommended changes for the remainder of the section specified in the comment.

19 26 30-43 Proprietary Please consider the content within

((...)) as proprietary information.

Page 26 line 30: the priority function. ((...

...)) Page 26 line 43: (end of line)

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC 20 33 49-53 Proprietary Please consider the content within

((...)) as proprietary information.

Page 33 line 49: NRC staff noted that ((...

...)) Page 33 line 53: The NRC staff determines The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

21 34 6-9 Proprietary Please consider the content within

((...)) as proprietary information.

Page 34 line 6: (beginning of line)

((...

...)) Page 34 line 9: The MELTAC platform The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

22 36 28-30 Proprietary Please consider the content within

((...)) as proprietary information.

Page 36 line 28: and power supplies. ((...

The staff agrees that the comment is valid. The staff will incorporate the change

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC

...)) Page 36 line 30: (end of line) recommended in the comment.

23 36 34 Proprietary Please consider the content within

((...)) as proprietary information.

Page 36 line 34: EI units and that

((...)) The NRC staff The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

24 2

4 Editorial Please revise:

in July 2024 (Ref. 8)

To:

in October 2024 (Ref.10)

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

25 2

29-34 Editorial Please revise:

Ref. 12 To:

Ref. 14 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC 26 4

4 Editorial Please revise:

JEXU-1041-1008-NP To:

JEXU-1041-1008-P on the TABLE 1, Row 1.

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

27 5

31 Editorial Please delete:

(Ref. 21)

It is not appropriate to refer to the MELCO document here.

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

28 6

7-9 Editorial Please revise:

MELCO submitted three supporting documents shown in Table 1 (Refs. 19, 20, and 26)

To:

Related to the revision of RG1.152, MELCO submitted following documents Summary of Compliance to the Regulatory Guide The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC MELCO submitted two supporting documents shown in Table 1 (Refs. 3, and 21) 1.152 Revision 4 and Summary of Compliance to the IEEE Std. 603 and IEEE Std. 7-4.3.2.

29 7

12 Editorial Please revise:

JEXU-1041-1008-NP To:

JEXU-1041-1008-P The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

30 15 55 Editorial Please revise:

[i]

To:

I MELCO believes that the [] is a typographical error.

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

31 17 19 Editorial Please revise:

Generic Option Items The staff agrees that the comment is valid. The staff will

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC To:

Generic Open Items.

incorporate the change recommended in the comment.

32 18 42 Editorial Please revise:

Generic Option Items To:

Generic Open Items.

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

33 19 35 Editorial Please revise:

Generic Option Item To:

Generic Open Item.

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

34 20 16 Editorial Please revise:

Generic Option Item To:

The staff agrees that the comment is valid. The staff will incorporate the change

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC Generic Open Item.

recommended in the comment.

35 21 38 Editorial Please revise:

The applicant To:

MELCO The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

36 22 14 Editorial Please revise:

Generic Option Item To:

Generic Open Item.

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

37 22 57 Editorial Please revise:

Section 3.1.5 To:

Section 4.1.5 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC 38 23 49 Editorial Please revise:

Summary of Compliance with To:

Summary of Compliance to The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

39 25 30 Editorial Please revise:

Summary of Compliance with To:

Summary of Compliance to The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

40 25 40-41 Editorial Please revise:

Summary of Compliance with To:

Summary of Compliance to The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

41 25 54-55 Editorial Please revise:

The staff agrees that the comment is

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC Summary of Compliance with To:

Summary of Compliance to valid. The staff will incorporate the change recommended in the comment.

42 30 20 Editorial Please revise:

Table A.6.2 To:

Table A.6-2 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

43 30 22 Editorial Please revise:

Table 6.2 To:

Table A.6-2 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

44 31 2

Editorial Please revise:

the applicant The staff agrees that the comment is valid. The staff will incorporate the

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC To:

MELCO change recommended in the comment.

45 34 18 Editorial Please revise:

Section A.4.1.1 To:

Section A.4.1.1.1 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

46 34 27 Editorial Please revise:

Section A.4.1.2 To:

Section A.4.1.1.2 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

47 34 35 Editorial Please revise:

Section A.4.1.3 To:

The staff agrees that the comment is valid. The staff will incorporate the change

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC Section A.4.1.1.3 recommended in the comment.

48 34 44 Editorial Please revise:

Section A.4.1.4 To:

Section A.4.1.1.4 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

49 34 53 Editorial Please revise:

Section A.4.1.5 To:

Section A.4.1.1.5 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

50 35 6

Editorial Please revise:

Section A.4.1.6 To:

Section A.4.1.1.6 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC 51 35 53 Editorial Please revise:

Robot To:

Reboot.

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

52 36 13 Editorial Please revise:

Section A.4.2.4 To:

A.4.2.7 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

53 36 14 Editorial Please revise:

5.8.2.d To:

5.8.2.g The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

54 36 54 Editorial Please revise:

The staff agrees that the comment is

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC Ref. 22 To:

Ref. 23 valid. The staff will incorporate the change recommended in the comment.

55 37 4

Editorial Please revise:

Ref. 22 To:

Ref. 23 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

56 39 56 Editorial Please revise:

Ref. 22 To:

Ref. 23 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

57 42 16 Editorial Please revise:

JEXU-1041-1162 NP The staff agrees that the comment is valid. The staff will incorporate the

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC To:

JEXU-1041-1162 P change recommended in the comment.

58 42 22 Editorial Please revise:

JEXU-1041-2146-NP To:

JEXU-1041-2146-P The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

59 42 23 Editorial Please revise:

ML24137A154 To:

ML24137A153 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

60 42 26 Editorial Please revise:

ML23167C171 To:

The staff agrees that the comment is valid. The staff will incorporate the change

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC ML23167C170 recommended in the comment.

61 43 1

Editorial Please revise:

JEXU-1041-1008-NP To:

JEXU-1041-1008-P The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

62 43 3

Editorial Please revise:

ML19135A123 To:

(ML number of P)

MELCO cannot identify the ML number of P. Need NRC input.

The staff agrees that the comment is valid. The staff will incorporate the change to ML19135A097.

63 43 6

Editorial Please revise:

ML23116A138 To:

(ML number of P)

MELCO cannot identify the ML number of P. Need NRC input.

The staff agrees that the comment is valid. The staff will incorporate the change to ML23116A140.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC 64 43 9

Editorial Please revise:

ML23167C173 To:

ML23167C172 The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

65 43 15 Editorial Please revise:

ML23167C175 (report)

To:

ML23167C174 (report)

The staff agrees that the comment is valid. The staff will incorporate the change recommended in the comment.

66 43 42 Editorial Please revise:

ML23167C181 To:

(ML number of P)

MELCO cannot identify the ML number of P on ADAMS. Need NRC input.

The staff agrees that the comment is valid. The staff will incorporate the change to ML23167C180.

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MELCO NRC 67 43 3

Editorial Please revise:

March 10, 2019 To:

May 15, 2019 MELCO is asking to use the submittal dates.

(NRC will confirm)

The staff partially agrees that the comment is valid.

Specifically, the date on JEXU-1041-1008-NP (R2))

Approved (-A) is May 10, 2019. The staff will update the date specified in the comment to the date on the referenced document to maintain consistency of document dates throughout this SE.

68 43 27 Editorial Please revise:

March 8, 2024 MELCO is asking to use the submittal dates.

The staff agrees that the comment is valid. The staff will incorporate the

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC To:

March 15, 2024 (NRC will confirm) change recommended in the comment.

69 40-41 56 (page

40) 1 (page

41)

Editorial Please revise:

to ensure that data communication shall be configured appropriately in the safety-related system To:

to verify the data quantity is less than the maximum shown in Table 4.3-1 of the MELTAC platform TR, Rev. 3 The staff partially agrees that the comment is valid.

Without some of the specific wording in the original nomenclature, the meaning of our evaluation could be misinterpreted. The staff will incorporate some of the recommended wording from the comment.

70 36-37 47 (page

36) 30 Editorial Lines 23 through 26 on page 37 of the DSE indicate that only the data communication The staff agrees that the comment is valid. Specifically, additional sections of RG 1.152, Rev 4

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC (page

37) capacity guidance in RG 1.152 Rev 4 was evaluated by NRC staff. Table 4.3 of JEXU-1041-1162 provides a clause by clause compliance matrix of all of RG 1.152 Rev 4, with references to JEXU-1041-1008, JEXU-1041-1015, and JEXU-1041-1018, all of which were evaluated by staff.

Section 4.3.10 of the DSE should reflect the results of those evaluations.

In addition, Table 3 of JEXU-1041-1162 indicates were referenced in Section 4.3.9 of this SE addressing MELCOs comment.

The NRC will update the wording in Section 4.3.10 to clarify Section 4.3.9 also addresses conformity to RG 1.152, Rev 4.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC compliance with Clause 3.3.1 of RG 1.152 Rev 4. The compliance refers to Section 3.2 of JEXU-1041-1016 (B-SPM), which was revised only to refer to the latest versions of RG 1.152 and IEEE 7-4.3.2; the latter described in JEXU-1041-1018, which was evaluated by staff, including the clauses cited in Section 3 of RG 1.152 Rev 4.

71 39 17-25 Editorial Please split PSAI 6.2.4 into the following parts:

6.2.4.a - Applicants or licensees referencing the MELTAC platform The staff partially agrees that the comment is valid.

Specifically, the staff agrees that splitting

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC in Rev. 3 of the TR shall perform an analysis to ensure that the types of signals transmitted to safety-related divisions from non-safety systems over the control network at the application-level support or enhance safety function performance.

6.2.4.b - Applicants or licensees referencing the MELTAC platform in Rev. 3 of the TR shall perform an analysis that ((

))

meets Clause 5.5.4 of IEEE Std.

7-4.3.2-2016 when it is used for priority functions as CCF countermeasures.

6.2.4.c - Applicants or licensees referencing the MELTAC platform in Rev. 3 of the TR shall describe how interdivisional communications that are needed PSAI 6.2.4 into subparts will add clarity, however, 5.6.4.2.m of IEEE 7-4.3.2-2016 is not considered generic and should remain addressed on a plant specific case and therefore, will remain part of PSAI 6.2.4. The staff will separate PSAI 6.2.4 into subparts that include 5.6.4.2.m using the preexisting numbering format.

OFFICIAL USE ONLY - PROPRIETARY INFORMATION OFFICIAL USE ONLY - PROPRIETARY INFORMATION MELCO MELTAC TOPICAL REPORT JEXU-1041-1008-P, REVISION 3, AUGUST 2025 COMMENT/RESOLUTION TABLE Comment Number Text Location Comment Type Suggested Revision Response to Comment DSE/ TR Page No.

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MELCO NRC to support a safety function as specified by 5.6.4.2.j and 5.6.4.2.k of IEEE Std. 7-4.3.2-2016 use the Data Link, and not the Control Network.

6.2.4.d - Applicants or licensees referencing the MELTAC platform in Rev. 3 of the TR shall make an analysis to ensure conformance with regulatory guidance on data communication independence as specified in Clause 5.6.4.2.l and 5.6.4.2.p of IEEE Std. 7-4.3.2-2016.

And, please move the reference to 5.6.4.2.m of IEEE 7-4.3.2-2016 to a Generic Open item.