I&C Performance Testing

AMS provides equipment, training, and services to the nuclear industry to measure the response time of temperature, pressure, level, and flow sensors and verify their calibration using in-situ and online measurement and monitoring techniques.

AMS has been measuring the in-service response time of process sensors in nuclear facilities since our inception in 1977. We perform these and other tests in essentially all of the 100 or more nuclear power plants in the United States and many in Europe and Asia.

AMS not only provides sensor response time and calibration monitoring services, but also sells equipment and training services to the nuclear industry to enable the users to perform the tests in-house.

For more information about the I&C performance testing services offered by AMS, please click here.

I&C PERFORMANCE TESTING SERVICES INCLUDE:

Online Calibration Verification of Pressure, Level, and Flow Transmitters

Laboratory Measurements of Response Time of Temperature and Pressure Sensors

In-situ Response Time Testing of Temperature Sensors to Measure In-service Response Time using the LCSR Method

Online Measurement of Response Time of Pressure, Level, and Flow Transmitters using the Noise Analysis Technique

Precision Laboratory Calibration of Temperature Sensors

RTD Cross Calibration According to the NRC’s BTP-13 of NUREG-0800

Testing of Sensors and Cables at Cold Shutdown to Verify Proper Sensor Installation and Wiring

Detection of Blockages, Voids, and Leaks in Pressure Sensing Lines

LOOP CURRENT STEP RESPONSE (LCSR) Technique

The response time of temperature sensors is tested in-situ using the Loop Current Step Response (LCSR) method and Self-Heating Index (SHI) measurements. The LCSR method is based on heating the RTD’s sensing element with a small electric current. This current causes a temperature transient in the RTD that is then analyzed using AMS proprietary software to determine the RTD’s response time. The LCSR method has been formally approved by the U.S. Nuclear Regulatory Commission (NRC) for measurement of “in-service response times” of safety-system RTDs in nuclear power plants.

SELF HEALING INDEX (SHI) MEASUREMENTS

In addition to LCSR tests, SHI measurements are made on nuclear power plant RTDs as an added measure of dynamic performance. As in LCSR test, SHI measurements involve a series of small electric currents that are applied to the RTD to measure the increase in its resistance as a function of input electrical power. The result, referred to as the SHI, corresponds to the RTD’s ability to dissipate heat and is thereby related to its dynamic performance.

Noise Analysis Technique

The response time of pressure, level, and flow sensors is measured using the noise analysis technique. This technique is based on monitoring the natural fluctuations (noise) that exist at the output of sensors while the plant is operating. The noise is extracted from the sensor output by removing the DC component of the signal and amplifying the AC component. The noise data is then analyzed in the frequency and/or time domain to provide the response time of the sensor. An extra advantage of the noise analysis technique is that it provides the response time of not only the sensor but also the sensing line that brings the pressure information from the process to the sensor. Any blockages, voids, or leaks in the sensing line manifest themselves in the noise data and in terms of an increase in the measured response time.

Testing Process

The LCSR test, SHI measurements, and noise analysis are all performed remotely from the control room area where the field leads from the sensors reach the process instrumentation cabinets. Performing these tests in-situ is advantageous because it provides the actual in-service response time of the sensor accounting for all installation and process condition effects on response time. The best time to perform these measurements is at normal operating pressure and temperature (NOP/NOT) during normal power operation or at hot standby conditions.