The following is a summary of information obtained from Palo Verde via email:
During pre-installation testing, five Masoneilan Model transducers were identified as unable to be calibrated prior to installation. These transducers were received by the vendor as safety-related components and are used to provide remote control operation of the Atmospheric Dump Valves (ADVs). The ADVs provide a safety grade method for cooling the unit to Shutdown Cooling System entry conditions, should Palo Verde's preferred heat sink via the Steam Bypass Control System to the condenser and/or atmosphere not be available.
The transducer receives a 4-20 mA signal and translates it to a 3-15 psi output to the ADV positioner. This is accomplished by varying the supply air from 23-30 psi down to the appropriate 3-15 psi signal. Palo Verde provided an Interim 10 CFR 21 Report for the five Masoneilan Model 8005N transducers, Part 21 log number 2019-36-00, ML 19323C971, which was submitted by Arizona Public Service (APS) Company on November 15, 2019.
An evaluation of the transducers was completed on March 19, 2020. The evaluation concluded that the inability of the transducers to be calibrated represented a defect.
The licensees affected are undetermined at this time. Palo Verde has been in communication with the vendor. The vendor has currently not provided an extent of condition.