CASE STUDY | High-Precision Wall Thickness Monitoring in a Nuclear Power Plant

A solution was sought by a European nuclear power plant to monitor high-pressure steam lines in proximity to the electricity generating turbines. Previous assets had been experiencing wall loss due to steam condensate causing erosion at piping T-junctions and as such had been replaced. The operator suspected that the wall loss rate and location was accelerated due to process conditions and so sought to collect data at increased frequency to allow wall loss rate to be correlated with specific process parameters. The operator was also advised that the greatest wall loss may occur during the first year of operation of the new piping and so a solution which could be installed immediately was required. The non-standard steel 21” and 25” NPS diameter steam lines, with surface temperatures above 230 °C, were located across several levels up to 30 m high in an area that is restricted to personnel during operation.

Key Deliverables

• Significant direct cost savings from reduced inspections, with the largest savings coming from minimizing the need for scaffolding and lagging removal and re-installation.
• Optimized operations through high-frequency, high-quality data, enabling safe plant operation between outages and better maintenance planning, reducing unplanned shutdowns and maximizing uptime.
• Increased personnel safety by limiting exposure to hazardous environments through use of wireless data collection methods.

Overview

A European nuclear power plant (NPP) faced a critical challenge with its high-pressure steam lines near the electricity generating turbines. Previously, the plant had replaced assets due to wall loss caused by steam condensate erosion at piping T-junctions. However, concerns were rising that the rate and location of wall loss were accelerating due to changing process conditions, prompting the operator to seek a more proactive monitoring solution. To address this, the operator needed a system that could collect data at increased frequency, allowing them to correlate wall loss with specific process parameters.
Additionally, they were advised that the greatest wall loss could occur within the first year of operation for new piping, making it critical to act quickly. The challenge was compounded by the need to monitor non-standard steel 21” and 25” NPS diameter steam lines, with surface temperatures exceeding 230 °C. These lines were located across multiple levels, up to 30 m high, in an area restricted to personnel during operation. The solution required a system that could be quickly deployed, reliable, and capable of capturing precise data to stay ahead of the issue — that could be installed immediately.

The Challenge

There were a number of challenges around the deployment which required a flexible monitoring solution:
• A high-temperature wall thickness monitoring solution was required which could operate over 230 °C continuously.
• The pipe geometry was non-standard and the monitoring locations were distributed around two T-sections.
• The piping is lagged, and the location is inaccessible during normal operation.
• The wall loss was thought to be process dependent, requiring a high-frequency of measurements.
• Wireless/RF systems are restricted in proximity to sensitive electricity generating plant.
• The equipment needed to be installed very short notice before the end of a shutdown as subsequent access would not be possible.