Plant Success Story from PQI Testing — $3 Million in Savings Due to Avoided SCRAM
A new PQI customer sent in thirty-one solenoid valves from their warehouse to be PQI tested. Among the 31 samples that were tested, one failed. This solenoid valve failed to pick up at rated voltage (120 VAC) or the minimum pick up voltage of 102 VAC.
PQI testing helped prevent a potential plant transient by identifying a failed critical component prior to installation. These solenoid valves serve several functions in the plant’s EHC (Electro-Hydraulic Control) system including FASV (Fast Acting Solenoid Valve). Although there are redundant EHC trains that use fast acting solenoid valves in your plants, a failure of this part can cause an immediate swap of one EHC train to the other train.
During this auto switch over, if system pressure goes below a certain pressure, a turbine trip and Unit SCRAM likely results. Exelon plants have identified some of these transients in the past. An important note: these parts were non-safety related critical solenoid valves.
A failure of these installed solenoid valves can trigger a turbine trip which can result in a unit scram if the redundant valve does not pick up fast enough. These fast-acting solenoid valves are used in many other critical applications relevant to plant reliability. A unit trip costs generally $3 million at full power, including costs associated with lost generation, recovery, penalties for grid maintenance i.e. forced outage maintenance, etc.
In addition to the solenoids being listed in the plant’s tier 2 critical spares list, the solenoids also matched the Constellation PowerLabs PQI testing inclusion list criteria: the solenoid valve has a 1.04% known failure rate history over the past year, highlighting the value of methodical testing and data analysis. Based on testing since 2009, these solenoids have a historical failure rate of 2%. The PQI solenoid valve component category in general maintains a 3.77% failure rate over the past year. Join the PQI community to gain access to the methodical testing and documenting of failure rates to transform your parts readiness program.