CHAR Services

CHAR Services

For over 20 years, AMS Corporation, through its CHAR Services Division, has been providing cable testing and EMI/RFI troubleshooting services to support the health and maintenance of cable circuits in nuclear power plants. Further, extensive research and development activities have also led to recent advancements in cable testing techniques that have been incorporated into the latest release of the CHAR (pronounced ‘care’) Cable Condition Monitoring System.

Example applications for AMS cable testing and CHAR services include a variety of low voltage cable circuits such as nuclear instrumentation, radiation monitors, rod control and rod position indication systems, pressurizer heaters, and motors. AMS has also developed a multiplexer that can be paired with the CHAR system which allows for testing up to 80 cables at a time thus facilitating high speed electrical characterization of large volumes of cables, connecters, and end devices.

Our CHAR cable testing system, together with our expertise in performing this work for over 20 years, provides a powerful tool for diagnosing and resolving issues in nuclear plant I&C cable circuits prior to an unexpected impact to plant operations.

Examples include:

Comprehensive LPRM Testing for Metal Whisker Burning and Signal Integrity Problems


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 for metal whisker burn using the CHAR Cable Characterization System. 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.

As a supplement to our high-speed LPRM testing program, AMS offers Enhanced LPRM (EEL) IV Testing for improved metal whisker remediation. Excessive spiking and bypassed detectors due to metal whiskers is a common failure mechanism in LPRMs. The AMS EEL system 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.


  • Connect to nearly 80 detectors at a time
  • Perform comprehensive electrical characterization (TDR, IR, DC resistance)
  • Reduces test time to approximately one shift


  • Heal bypassed and spiking detectors
  • High frequency data sampling to better observe spiking events
  • Configurable current limit from 5-60 mA
  • Continuous voltage ramp
CHAR Services

  • Degraded connectors
  • Moisture intrusion into cracked cable insulation
  • Intermittent connections
  • Noise coupling from damaged or degraded shielding
  • Open circuit faults
  • Short circuit faults – between conductors, conductor to ground
  • Turn to turn shorts in motors and coils
  • Foreign material or moisture contamination in connectors


  • Instrumentation and power cables, including connections, penetration and splices
  • Rod drive mechanism cables and coils
  • Rod position indication system cables
  • Nuclear instrumentation cables, connectors, and detector
  • Baselining newly installed cables & connectors
  • Motor coil and valve cables and connectors


  • Distance to fault
  • Fault severity
  • Effect of fault on cable circuit performance
  • EMI/RFI analysis
  • Recommendations for repair
  • Automated report generation