Nuclear valve modernisation: IMI Maxseal for reactor life extension

For plant operators, this creates a complex challenge: how do you modernise critical plant infrastructure without compromising safety, compliance or long-term operational performance?

For one nuclear power plant in Argentina that challenge centred on ageing legacy valve technology. The plant required a modern, supportable and nuclear-qualified replacement for obsolete valves used in the original plant design.

IMI worked with the customer’s nuclear engineering team to develop a proven valve replacement solution based on IMI Maxseal technology. Through extensive qualification testing, including seismic, vibration, radiation ageing and loss-of-coolant accident (LOCA) testing, the IMI Maxseal nuclear technology range demonstrated its ability to perform critical safety functions in severe nuclear environments.

The result was a fully qualified valve solution that helped the customer address obsolescence risk, supported their reactor life-extension goals, and moved the facility to a modern technology platform aligned with current nuclear power industry standards.

There are around 440 nuclear power reactors operating worldwide today, with more than two-thirds built before 1990. As these plants continue to play an important role in supporting energy security and low-carbon electricity generation, operators are increasingly investing in reactor life-extension programmes.

These programmes can involve rolling upgrades, targeted equipment replacement and ultimately major plant refurbishment. The goal remains the same: to keep valuable nuclear assets operating safely, reliably and efficiently for longer.

For nuclear energy plant operators, one of the most pressing challenges is equipment obsolescence. Legacy components that were part of the original plant design may no longer be manufactured, supported or sufficiently qualified enough to meet the rigorous demands of modern nuclear industry standards. When those components are part of safety-critical systems, replacement decisions require careful engineering judgement and rigorous evidence.

At the Argentinian nuclear power plant, the customer needed to replace legacy Herion valves with a modern alternative that could meet today’s qualification requirements. Naturally the goal was to support the long-term future and safety of the facility.

This was not simply a like-for-like replacement. The new valve technology had to provide proven reliability, long-term supportability and the capacity to perform required safety functions under demanding nuclear operating conditions.

In conventional industrial applications, valve selection is often guided by factors such as pressure, temperature, media compatibility, duty cycle and hazardous-area certification. In nuclear power applications, the requirements go much further.

Nuclear-qualified valves must demonstrate that they can perform their required safety function before, during and after severe environmental and accident conditions. This can include exposure to vibration, radiation, seismic events and extreme pressure and the temperature changes associated with postulated accident scenarios.

This level of qualification is essential because valves form part of wider safety system architectures. Nuclear facilities are typically designed with redundant safety trains, helping ensure that critical functions remain available even if a component failure occurs within a single train.

For the customer, this meant the replacement valve technology had to meet the demanding standards expected in nuclear safety systems. It also had to provide the reliability and supportability needed for long-term plant operation.

Rather than begin with a clean-sheet design, IMI’s engineering team identified an opportunity to adapt a proven industrial technology for nuclear use. IMI Maxseal valve technology already had a long track record in severe-service environments, particularly in demanding oil and gas applications where reliability, availability and safety are critical. We designed this solution for applications where equipment may remain dormant for long periods, before it is then required to operate immediately and reliably on demand. This history made Maxseal a strong foundation for a nuclear-qualified solution.

The existing Maxseal portfolio already included important industrial credentials, including hazardous-area certifications such as ATEX, IECEx and other regional approvals. These certifications demonstrated suitability for operation in potentially explosive atmospheres. The range also had functional safety credentials and SIL (safety integrity level) - capable designs for Safety Instrumented System applications, emergency shutdown systems and process isolation duties.

However, nuclear qualification required a further level of technical requirement. Although Maxseal technology was already proven in demanding industrial environments, it still had to undergo rigorous testing to demonstrate its suitability for nuclear power applications.

IMI worked closely with the customer’s engineering team to develop a qualified replacement valve solution based on the proven Maxseal solution. The objective was to provide a modern, supportable valve range that could help the plant move away from obsolete legacy technology while meeting the specific qualification requirements of the nuclear power industry.

This approach offered the customer several important advantages. First, it reduced the risk associated with adopting an entirely new and unproven design. By using a technology platform with a strong history of severe-service performance, IMI could build on existing evidence, field experience and engineering knowledge. Second, it gave the customer a long-term replacement path for obsolete valve technology, helping support the plant’s life-extension programme.

Third, it created a solution that could be relevant not only to one plant, but to other nuclear facilities facing similar obsolescence, compliance and modernisation challenges.

To demonstrate that the IMI Maxseal nuclear range was suitable for nuclear applications, IMI conducted a comprehensive programme of qualification testing. The testing programme was designed to demonstrate that the valves could continue to perform their required safety function under severe environmental and accident conditions. This was essential for proving their suitability in nuclear safety-related applications.

The qualification process included:

This testing provided the evidence needed to support the use of Maxseal valve technology in demanding nuclear power plant environments.

One of the most demanding aspects of nuclear valve qualification is demonstrating performance under loss-of-coolant accident conditions. A loss-of-coolant accident, commonly referred to as LOCA, is a postulated nuclear accident scenario involving the loss of reactor coolant. Equipment required to operate under these conditions must be able to function in an environment where pressure, temperature and other conditions can change rapidly and severely. For the IMI Maxseal nuclear range, LOCA testing was designed to demonstrate continuous functionality in harsh accident environments.

The valves were subjected to rapidly changing pressure and temperature conditions representative of a postulated nuclear accident scenario. Testing included simultaneous exposure to elevated pressure and temperature, valve operation under accident conditions and 24-hour qualification test sequences.

This programme demonstrated that the Maxseal Nuclear Range could continue to perform required safety functions under some of the harshest environmental and accident conditions encountered in the nuclear power industry. As a result, alongside existing ATEX, IECEx and SIL credentials, the Maxseal nuclear range achieved nuclear qualifications aligned with IEEE and IEC standards.

For the customer, the Maxseal Nuclear Range provided a modern, qualified and supportable replacement for obsolete legacy valve technology. By moving from the existing ageing valves to a fully qualified IMI Maxseal solution, the plant was able to address a critical obsolescence challenge while supporting its wider reactor life-extension programme.

The project helped the customer:

The successful qualification and implementation of the Maxseal Nuclear Range showed how proven industrial technology can be adapted to meet the highly demanding requirements of the nuclear sector.

The challenge faced by this customer is not unique. Across the nuclear power industry, many operators are seeking ways to extend the life of existing reactors while replacing obsolete equipment and meeting modern safety standards. Our Maxseal nuclear range provides a proven route forward for facilities that require qualified valve technology for safety-related applications.

Beyond existing plant modernisation and reactor life-extension programmes, IMI also plans to apply the same valve solution to new-build conventional nuclear plants, small modular reactors (SMRs) as well as advanced reactor technologies.

This makes Maxseal nuclear valve technology not only a solution for today’s ageing nuclear infrastructure, but also a technology platform that can support the future of nuclear energy.

The IMI Maxseal Nuclear Range has been developed to meet the demanding standards required for nuclear facilities, including:

These qualifications demonstrate that Maxseal valve technology can support critical nuclear safety functions in challenging operating and accident conditions.

For nuclear operators looking to replace obsolete valves, support reactor life extension or prepare for future reactor programmes, IMI Maxseal offers a proven, reliable and qualified solution. To discover more about IMI Maxseal solenoid valves and regulators for harsh environments, please visit: IMI Maxseal Solenoid Valves and Regulators for Harsh Environments