Three years in the making: How IMI Valve Doctors solved a persistent leakage problem at the US’s largest nuclear energy facility

For the team at a large nuclear energy facility in the United States, it was the latter. This nuclear facility, the largest of its kind in the United States, sought a knowledgeable, experienced partner to resolve an ongoing leakage issue with its boric acid valves. Media continued to escape from old competitor-designed valves, requiring regular maintenance.

Boric acid plays a crucial role in regulating nuclear reactions and mitigating corrosion within reactor systems. This makes leakages particularly serious. However, the challenge for the site’s engineering team wasn’t just operational safety; the time and investment required to keep the site’s failing valves operational were also approaching $400,000 per year.

It was at this point that our Valve Doctors intervened.

Our sales team became aware of the leakage problem at the nuclear facility in 2022. Following a brief discussion, a consultation was proposed with Christian Klee, an IMI Valve Doctor™ with 16 years of industry experience. It soon became clear that the leaks were caused by worn packing and other design faults in the site’s existing valves.

In principle, the proposed change was simple: replace the leaking valves with a newer, more appropriate back-seated design featuring robust graphite packing and stainless-steel bellows. Effective for up to 15,000 cycles, this new valve would provide a tight seal, eliminating the risk of leakage or passage.

Any asset intended for use in nuclear facilities must undergo a rigorous qualification process to ensure high safety and reliability. As part of this, new valve prototypes undergo a series of independent tests. Pressure, vibration, radiation, and seismic response are all considered to assess integrity in the event of earthquakes.

Qualification can take several years, so any proposed solution for the nuclear energy facility had to be approved in advance. This was not a problem for us, given our longstanding history of working closely with nuclear facilities. With thousands of our bellows-sealed globe valves installed in all CANDU facilities across Canada, as well as in plants in other regions such as Romania, China, and South Korea, we were well placed to meet the facility’s requirements. We had also replaced competitor valves inside the containment, which is subject to stricter testing and qualification.

This strong track record, spanning over 40 years, cleared the proposed product for use, notwithstanding minor modifications from the facility’s engineering team.

Although no new qualification process was required, vetting was still necessary to deliver an effective solution. Ongoing conversations revealed there was no new valve specification sheet in use at the nuclear energy site, as the original assets had first been installed decades earlier. This was the first change Christian recommended.

Clarity and technical accuracy are essential for work in American Society of Mechanical Engineers (ASME) environments, particularly when making a significant change to a site’s flow control infrastructure. However, specification sheets are also crucial for a project’s long-term success, as they provide both parties with the opportunity to capture all important data points before proceeding with installation.

As the site team had no prior experience with this type of document, Christian and his team helped the facility develop its own specification sheet, which included general design requirements, materials, brazing procedures, quality details and function tests.

With this document in hand, we were able to determine the specification's viability and incorporate all necessary modifications. The customer’s engineering team requested changes to the valve’s geometry – moving from a standard T-shape to a Y-shape pattern – as well as the request to change some materials as per the facility’s standard materials list. In total, the process took almost three years to reach a purchase order, demonstrating both parties’ commitment to effectively eliminating the site’s leakage problem.

The impact of our valve has been clear.

Once installed, there was no leakage to the environment, allowing the energy plant’s engineers to now devote their engineering resources to other parts of its facility. This performance aligns with our 3,000-strong installed base of bellows-sealed globe valves at nuclear sites, where only a select few have required attention beyond standard, ongoing maintenance.

In some sense, this project was unorthodox. Collaborating with a business to write a valve specification is rare, as was the time and depth of vetting required to transition this site from an older, competing design.

But this is why the Valve Doctor™ programme is so effective. It enables us to consult with clients on technical matters without the pressure of time constraints. The result is a tailored solution that’s designed to improve performance in the long term.

To discover more about our nuclear industry technologies, please visit our nuclear power section.