Modernising Alarm Annunciation to Secure Long-Term Operational Reliability

Operating within the UK nuclear sector demands absolute confidence in control and monitoring systems. At this facility, the PWTP, CTP and ETP systems play a vital role in managing plant processes and maintaining safe, continuous operations. 

The existing alarm annunciation system had supported operations for many years. However, as part of a broader lifecycle management strategy, it was identified that the system no longer met modern expectations for maintainability, supportability and long-term reliability.  

The requirement was clear: modernise the annunciation capability in a controlled, compliant manner – without impacting ongoing operations or introducing unnecessary risk. 

The core challenge was not simply to replace ageing equipment, but to do so within a live nuclear environment where continuity of monitoring is essential. 

Key constraints included: 

• Integration with existing plant systems and infrastructure 
• Maintaining alarm visibility throughout the transition 
• Ensuring compliance with current nuclear engineering standards 
• Managing inconsistencies in legacy system documentation and configuration 

AMS Nuclear approached the project by combining detailed system understanding with robust engineering design, ensuring the replacement system aligned with both operational needs and modern standards. 

The solution introduced two key assemblies: 

• An Input Management Assembly installed within the existing MPAS cubicle 
• A new Annunciator Cubicle located within the PWTP control room  

This architecture enabled seamless integration with the Plant Status Monitoring System (PSMS), using established communication protocols to ensure consistent alarm handling across the facility. 

Key features of the system included: 

• Digital processing of alarm inputs from field devices 
• Clear visual indication via illuminated alarm tiles 
• Audible alarm functionality aligned with control room requirements 
• Structured alarm management, including prioritisation and repeat signalling to PSMS 
• Secure operator and administrator access levels 

The system was engineered to meet defined performance and reliability targets, including high availability and robust fault detection capability.  

AMS Nuclear executed the project through a structured, three-phase delivery model, ensuring full compliance and quality assurance at every stage. 

Design and Definition 

• Detailed assessment of existing system functionality 
• Development of design documentation and integration strategy 
• Identification and resolution of legacy inconsistencies 

Manufacture and Verification 

• Assembly of system hardware and development of supporting software 
• Factory Acceptance Testing (FAT) to validate performance against requirements 
• Simulation of PSMS interfaces to confirm system behaviour  

Installation and Commissioning 

• Installation within the control room environment 
• Site Acceptance Testing (SAT) to confirm correct integration 
• Managed commissioning approach to maintain operational continuity 

Throughout delivery, AMS Nuclear worked in close collaboration with site stakeholders, ensuring alignment with operational schedules and nuclear safety expectations. 

This project reinforced the importance of proactive obsolescence management in safety-critical environments. By addressing system ageing before failure, the client secured both operational continuity and long-term maintainability. 

Key lessons and innovations included: 

• The value of early functional validation to uncover discrepancies between documented and actual system behaviour 
• The effectiveness of modular system design in enabling future upgrades and scalability 
• The importance of integrating modern digital systems with existing infrastructure rather than replacing entire architectures 

The approach and methodologies developed through this project are readily transferable across similar legacy systems, supporting ongoing modernisation programmes throughout the UK nuclear fleet. 

This case study demonstrates AMS Nuclear’s ability to consult, design and build safety-critical EC&I systems that deliver measurable operational benefits while meeting the highest standards of quality and compliance.