A common preventative maintenance activity for BWRs is to perform electrical tests such as current-voltage (IV) measurements of LPRMs during the outage. As most BWRs have between 125 and 175 LPRMs, this testing activity can take up valuable I&C resources and at times can become a critical path activity. AMS offers comprehensive LPRM testing services to automate this testing activity. By integrating Multiplexers with multiple AMS CHAR systems, LPRM IV testing can be performed on nearly 80 detectors at a time while also providing complete electrical characterization of each detector through performance of TDR, IR, and DC Resistance measurements. This automated service significantly reduces LPRM testing time, allowing all detectors to be tested in approximately one shift.
In addition to automating the testing process, AMS also has unique capabilities to resolve any problems that are identified. For example, a typical failure mechanism for LPRMs is metal whisker growth between the plates of the detector. These whiskers can short circuit the LPRM detector, which must then be placed in bypass mode. Each plant must have a certain percentage of LPRMs operational to remain online.
AMS offers comprehensive LPRM testing services to rejuvenate LPRMs by “burning” the metal whiskers in the detector using the CHAR Cable Characterization System. The AMS Enhanced LPRM (EEL) IV allows up to 60mA of current to flow to the detector during an IV curve spiking event for improved metal whisker burn. If a poor IV curve is observed during high-speed LPRM testing using the CHAR system, AMS will then follow-up with the EEL test system to help heal the detector. The EEL test system can also be used to target bypassed or malfunctioning detectors, allowing plants to avoid expensive detector replacement.