VALVE MAGAZINE Summer 2023

Nuclear Component Testing: The Impact of Stress Wave Testing on Safety Relief Valves Cold bar testing reveals a qualitative pass/fail status for valves, but more confirmation is needed for these critical components.

To extend the useful life of today’s nuclear reactors and prepare for license renewals

an ultrasonic leak detection system that measures stress waves — vibroacoustic, structure-borne signals that are cor related to the natural frequency of the associated material. Being able to detect and monitor this shear wave energy (SWE) is an effective way to identify valve seat leakage quantitatively and identify valve internal degradation in its early stages.

BY JEREMY STEVENS

that may extend as long as 80 years, maintenance techni cians must pay careful attention to the risk of deteriorating valve performance, potential leaks and efficiency losses, especially within the steam cycle. Constant monitoring of pressure relieving devices including safety relief valves

(SRVs), is an important main tenance item to ensure safe and efficient power production. Valve monitoring and mainte nance technology can improve All plants perform cold bar testing to verify that a refur bished valve has been repaired properly and is operating correctly prior to installation. While the valve is under steam pressure, a cold bar is inserted downstream of the valve to see whether moisture droplets form on the surface of the cold bar to detect a seat leak. Unfortu nately, traditional cold bar test ing only reveals a qualitative performance at all power plants, not just nuclear.

SUMMER 2023 VALVE MAGAZINE

Photo courtesy of Getty Images

“pass/fail” status for each valve at the time of testing. Some times, a valve will pass a cold bar test after refurbishment, and then develop a steam leak while in service. A leaky valve can lead to lost generation and increased fuel costs, and sometimes an expensive unscheduled maintenance outage is required to replace the leaking valve. To gather quantitative data about the status of seat tight ness and potential leakage on SRVs, some power plants use

This article describes how a sensor-based, vibro-acoustic monitoring system — in conjunction with cycle isolation and smart software platforms — can help power plants to detect generation losses, reduce carbon emissions, reduce the risk of forced outages and cut costs. ABOUT THE SWE METHODOLOGY The SWE methodology combines advanced pattern recogni

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