In November 2025, Metroscope gathered more than 40 performance experts from 10 nuclear sites at Gravelines CNPE for its Metroscope Experience Sharing (MEX) event. Across discussions, plant teams shared how issues that once required weeks of investigation are now resolved within days.
The objective was not to present tools, but to understand how investigations actually happen on site. Operators explained how they detect performance losses, validate a diagnosis, decide when to act, and assess the impacts. The discussion focused on what it really takes to move from detection to resolution.
Detection alone does not create value. Value appears when teams can quantify the impact of a deviation, validate it in the field, decide on an action, and link that action to measurable results. That is what builds trust over time — in both the process and the tools.
From weak signals to costly delays
Across sites, teams described the same pattern: costly faults often start as small, hard-to-notice drifts. Detecting them is necessary but not enough. The real challenge begins after detection: understanding which signals matter and turning them into decisions. The following cases show how teams move from weak signals to action — and where time is gained.
The team from Penly shared the case of a leaking bypass valve on a moisture separator reheater. The leak was small, but its impact was not. Steam that should have contributed to production was redirected to the condenser, resulting in a significant performance loss.
In the data, the drift in steam flow was subtle. Even when noticed, it was not sufficient to justify an investigation without a clear estimate of its impact. What made the difference was the ability to isolate the fault and quantify its megawatt impact. Without quantification, the issue would likely have remained unresolved.
At Chooz, the challenge was not detection but prioritization. The issue came from the condenser cleaning system, which is not safety-critical and not always addressed first.
What changed the decision was quantification. Once the loss was expressed in megawatts and economic impact, the performance team could justify prioritizing corrective action during the next outage. After restart, the impact was immediately confirmed — reinforcing trust in the diagnostics.
At Gravelines, resolving a reheater backup valve leakage required coordination. The team combined diagnostics, field checks, and cross-team collaboration to confirm the issue. Shared evidence and structured exchanges between teams helped align interpretations of the data, build confidence in the diagnostic, and accelerate decision-making.
At Tihange, a problem that once took weeks to identify is now resolved in two days. Restart phases, especially after long outages, often bring multiple issues at once.
In that context, being able to isolate problems quickly, act, and assess the impact brings clarity. Trust in the tools and process reduces hesitation and reinforces the confidence to act rapidly.
From these cases, three elements stand out as key to accelerating decision-making: impact quantification, effective cross-team communication, and trust in the tools.
These elements only create value when combined. Quantification gives weight to a signal, communication aligns teams on its interpretation, and trust enables timely action without prolonged validation cycles.
When these conditions are met, teams spend less time hesitating and more time acting and investigation time drops. In that context, tools like Metroscope are not here to replace operator expertise, but to support it.
A shared foundation for better decisions
Beyond individual cases, these discussions highlighted both what is required to improve decision-making and why dedicated moments of structured experience sharing are essential.
They made clear that improving monitoring approaches depends on several pre requisites: expanding diagnostic coverage, improving data reliability, and making insights usable beyond specialist teams. These are key to reducing investigation time while maintaining confidence in decisions — and they directly shape the direction of Metroscope’s product development.
Comparing practices and discussing real situations does more than circulate knowledge — it helps teams converge on what works. Less experienced teams gain faster access to proven approaches, while more mature teams refine their methods by confronting different perspectives.
Metroscope Experience Sharing event (MEX 2025) built on this dynamic. By grounding discussions in real cases, it provided participants with concrete ways to improve their practices, while clarifying the conditions required to move effectively from detection to decision. These moments of collective reflection play a direct role in improving how decisions are made on site, by turning individual experience into shared, actionable knowledge, and by continuously informing how monitoring solutions must evolve.
These discussions reflected a broader challenge shared across many plants: reducing investigation time while increasing confidence in decisions. For teams facing similar situations, Metroscope can support a deeper technical discussion to explore how these approaches can be applied in your context.
