Replacing Obsolete Reactor Pressure Test Systems for the Transition to Defueling

Heysham 1 and Hartlepool power stations relied on portable “POP” test trolleys to set and verify RPV Safety Relief Valves: equipment operating at pressures up to 45 bar g. However, as EDF prepared for defueling operations, set pressures were to be de-rated to approximately 15 bar g.

The original trolleys, though proven in service, were built for an earlier operating regime. They incorporated legacy instrumentation and were configured for higher-pressure testing. As operational requirements evolved, EDF sought a refreshed solution capable of delivering the same dependable performance at lower pressures, supported by modern digital systems and improved calibration control.

AMS Nuclear Engineering responded with a bespoke dual-range test trolley, capable of supporting both the existing (≈45 bar g) and defueling (≈15 bar g) pressure settings. The system was designed from the ground up to deliver accuracy, safety and full regulatory compliance.

Each unit featured:

• Dual-range operation, enabling seamless transition between standard and reduced pressures.
• Modern digital instrumentation, including 4–20 mA pressure transducers, precision indicators and paperless data recording.
• Enhanced operator safety, through robust isolation, vent and regulating valves, plus ergonomic layout for ease of use.
• Full compliance with the Pressure Systems Safety Regulations (PSSR 2000), BS EN 61010-1 and ISO 9001:2015 QA standards

AMS Nuclear delivered the full package – detailed design, documentation, manufacturing and testing, supported by comprehensive Operation and Maintenance manuals.

The new test trolleys provided EDF with a future-ready, fully traceable solution that enhanced both operational performance and maintainability.

Key outcomes included:

• Seamless continuity in pressure testing through dual-range flexibility.
• Improved data integrity with modern digital recording and calibration.
• Simplified maintenance, using modular design and accessible components.
• Reduced downtime through ergonomic design and operator-friendly controls.

The project was completed under QA Grade 2, verified through Factory Acceptance Testing and fully aligned with EDF’s Central Technical Organisation procedures.

Through this project, AMS Nuclear demonstrated their ability to translate complex technical challenges into safe, efficient and enduring engineering solutions. The upgraded trolleys are not only maintaining pressure testing capability today, they’re underpinning the long-term reliability of EDF’s defueling operations, ensuring continued safety and compliance across the UK’s nuclear fleet.