Analysis of a CANDU nuclear steam system at low power for assessment of heat transport header temperature measurements

The temperature measuring devices for the heavy water in the primary heat transport (PHT) headers in a CANDU reactor cannot normally be calibrated and present a relatively large source of error in the measurement of reactor power. This thesis devises a method to assess the accuracy of these devices at low reactor power by comparing the temperature of the saturated fluid in the boilers, which can be accurately determined from the pressure measurements, to the measured header fluid temperatures. Corrections are made for heat inputs and heat losses. Using this methodology, an analysis is conducted for three test cases at the Point Lepreau Generating Station (PLGS) from December 2000 to January 2002. In summary, the calculated errors in this methodology are too large to allow a reduction in the current uncertainty in the reactor header temperature measurements. However, this method would be useful to detect and identify trends in the reactor header temperatures that could point to system or instrumentation abnormalities.