Strengthening Reactor Resilience Through Intelligent Interim Engineering

Project Overview

Client: EDF Energy Nuclear Generation Ltd

Location: Heysham 2

Quadrant trips present an operational challenge for AGR stations because the resulting transient increase in Channel Gas Outlet Temperature (CGOT) can, at high reactor power, lead to a full reactor trip. Introducing an improved automatic response therefore required careful integration with the station’s established protection and control systems, alongside compliance with nuclear safety requirements and compatibility with the planned longer-term solution. AMS Nuclear designs and delivers safety-classified EC&I modifications that address these constraints through robust system integration, lifecycle planning and rigorous quality assurance.

At Heysham 2 (EDF Energy), AMS Nuclear delivered the interim hardware solution for the Quadrant Trip Hardening (QTH) programme, providing new interface cubicles and integration with the Data Processing and Control System (DPCS) and Essential Plant Protection Equipment (EPPE). Developed to QA Grade 2 requirements with a specified 20-year design life, the modification enabled faster initiation of control rod insertion following a quadrant trip, reducing the likelihood of an unnecessary full reactor trip and supporting generation availability. Crucially, the solution was designed so that hardware could be re-used within the subsequent digital upgrade, reducing duplication of cost and effort while providing a clear pathway from the interim modification to the longer-term solution.

Supporting a Critical Improvement Programme

Like many nuclear facilities, Heysham 2 continually reviews opportunities to strengthen operational performance while maintaining the highest standards of nuclear safety. One such opportunity centred around the station’s Quadrant Protection Equipment (QPE), which protects the reactor by initiating a shutdown of an individual quadrant following specific boiler or circulator faults.

During certain operating conditions, a quadrant trip can create a temporary increase in Channel Gas Outlet Temperature (CGOT). At higher reactor power levels this transient could, in some circumstances, trigger a full reactor trip. While the existing protection systems continued to perform their intended safety function, EDF identified an opportunity to further enhance plant resilience by reducing the likelihood of unnecessary full reactor trips during single quadrant events.

As part of the wider Quadrant Trip Hardening programme, an interim hardware modification was required to deliver these operational improvements ahead of the long-term control system upgrade. The solution also needed to integrate seamlessly with the future digital implementation, avoiding unnecessary duplication of equipment and investment.

Engineering an Interim Solution with Long-Term Benefits

AMS Nuclear was selected to design, manufacture, install and commission the interim interface system that would support the Quadrant Trip Hardening modification while remaining fully compatible with the future permanent solution.

Rather than viewing the requirement as a standalone hardware project, AMS Nuclear developed an engineering solution that considered the entire asset lifecycle from the outset. Every design decision focused on delivering immediate operational improvements while ensuring the equipment would continue to provide value as the wider programme progressed.

The solution comprised four new interface cubicles per reactor, integrating with both the Data Processing and Control System (DPCS) and Essential Plant Protection Equipment (EPPE). Carefully designed isolation relays and interface wiring enabled rapid signal injection following a quadrant trip, supporting a faster control rod response and reducing the potential for unnecessary reactor trips.

Developed to QA Grade 2 standards, the design met EDF’s stringent engineering governance requirements while complying with relevant British, European and international standards covering control and instrumentation systems, electromagnetic compatibility and fire protection. With a specified design life of 20 years, the hardware was engineered to become part of the final digital solution, reducing lifecycle costs and simplifying future implementation.

"Good engineering isn't simply about solving today's challenge, it's about delivering solutions that continue creating value long after the initial project is complete."

Project Lead, AMS Nuclear

Delivering Complex Nuclear Projects Through Structured Collaboration

Successful delivery depended upon close collaboration between AMS Nuclear and EDF throughout every stage of the project.

The programme followed a structured engineering lifecycle beginning with detailed design development and technical substantiation against EDF’s Control & Instrumentation High Level Functional Requirements. Once approved, AMS Nuclear manufactured the interface cubicles before undertaking comprehensive Factory Acceptance Testing, including electrical isolation testing, electromagnetic compatibility verification and extended soak testing witnessed by EDF representatives.

Alongside manufacture, AMS Nuclear produced comprehensive Lifetime Record Packages (LTRPs), quality documentation and complete material traceability records, including counterfeit avoidance measures to satisfy the rigorous quality assurance expectations associated with safety-classified nuclear equipment.

Installation and commissioning were completed during the Reactor 8 outage programme using Suitably Qualified and Experienced Personnel (SQEP), working in close coordination with EDF’s Protection & Electrical Systems, DPCS and outage teams. Site Acceptance Testing and commissioning activities ensured the new interface system integrated seamlessly into the existing plant while remaining fully aligned with the future control system upgrade.

Delivering the project within the tightly controlled outage schedule demonstrated AMS Nuclear’s ability to coordinate engineering, manufacturing and installation activities without compromising quality or compliance.

Creating a Solution That Delivers Beyond a Single Project

The Quadrant Trip Hardening interim modification demonstrates the value of designing engineering solutions that address both immediate operational requirements and long-term asset strategies.

By improving reactor resilience while enabling hardware re-use within the final digital upgrade, AMS Nuclear helped maximise value from the client’s investment and reduce future implementation effort. Equally important was the structured quality assurance approach, comprehensive engineering documentation and collaborative delivery model that ensured full alignment with EDF’s engineering change process and Licence Condition 22 requirements.

Projects such as this illustrate how thoughtful engineering can provide operational improvements today while laying the foundations for future modernisation programmes across the wider UK nuclear sector.