Replacing an Obsolete Safety-Important SCADA System Without Interrupting Reactor Monitoring

The legacy SCADA platform relied on dual-redundant VAX processors that had become increasingly difficult to support and maintain. While the system continued to fulfil its intended function, the growing challenge of hardware obsolescence created a need for a sustainable long-term replacement strategy.

The project required more than a simple technology refresh. The replacement solution needed to preserve existing functionality, meet the requirements of BS IEC 61513 and other applicable nuclear standards, strengthen cybersecurity and maintain the high levels of availability expected of systems important to safety.

Compounding the challenge was the need to execute the transition with minimal downtime, ensuring continuous reactor monitoring capability throughout implementation.

AMS Nuclear worked with their trusted partner to develop a modern SCADA architecture that replicated the functionality of the existing system while introducing the reliability, maintainability and flexibility offered by contemporary technologies.

The engineering programme began with a detailed site survey and requirements capture exercise, enabling the team to fully understand the operational environment and technical constraints. From there, AMS Nuclear designed a replacement platform built around commercial off-the-shelf (COTS) technologies compliant with Low Voltage and EMC directives.

Key features of the solution included:

• Dual workstation architecture supporting independent R3 and R4 monitoring.
• Mirrored archiving to enhance resilience and data availability.
• Human Factors-compliant HMI design validated by EDF specialists.
• Alignment with Modest Integrity (Class 3, Category C) safety classification requirements.
• Built-in scalability, including 20% spare capacity for future expansion, alarm integration and data archiving requirements.

AMS Nuclear managed the project through the complete engineering lifecycle, from design and build through to installation, testing and commissioning.

All work was delivered under QA Grade 2 requirements and supported by AMS Nuclear’s ISO 9001-certified quality management processes. Factory Acceptance Testing verified compliance with functional requirements before deployment, while extensive reverse engineering ensured that legacy system behaviour was accurately replicated and validated.

One of the project’s most significant achievements was the successful installation and commissioning of the replacement system with less than five days of downtime, ensuring critical reactor trip monitoring capability remained available throughout the transition.

Commissioning activities were completed using EDF-approved Functional Test Procedures and witnessed acceptance stages, providing confidence that all performance and compliance requirements had been met.

The completed upgrade delivered benefits extending far beyond the immediate replacement of obsolete hardware.

Regulatory Assurance
The new platform achieved full alignment with key nuclear standards, including IEC 61513, IEC 61508 and EDF Company Technical Standards, helping ensure continued compliance throughout the system lifecycle.

Enhanced Operational Resilience
The architecture eliminated obsolescence-related risks while introducing fault-tolerant design principles and enhanced diagnostic capability. The system was engineered to support availability targets exceeding 99%.

Improved Maintainability
By adopting standardised technologies and modern configuration management practices, EDF now benefits from a platform that is easier to support, maintain and upgrade over its planned 15-year lifecycle.

Future Fleet-Wide Application
The methodologies, validation processes and quality assurance approach developed during the project provide a repeatable blueprint for future SCADA modernisation and obsolescence management programmes across the wider EDF fleet.

• Less than 5 days system downtime during implementation.
• Designed for a 15-year operational lifecycle.
• Greater than 99% availability target built into the architecture.
• Delivered under QA Grade 2 requirements with full lifecycle traceability.
• Fully compliant with applicable nuclear safety and regulatory standards.

The Hinkley Point B AIC SCADA replacement demonstrates how modern technologies can be successfully integrated into safety-important nuclear applications without compromising operational continuity, compliance or reliability.

By combining rigorous engineering governance with practical delivery expertise, AMS Nuclear helped EDF transform a growing obsolescence challenge into a future-ready solution that supports long-term resilience, maintainability and fleet-wide learning.