DETECTION OF SUBCOOLED BOILING IN A PWR USING NOISE-ANALYSIS AND CALCULATION OF THE STEAM VOID FRACTION

In a 1300 Mw pressurized water reactor (PWR) the temperature fluctuati ons of thermocouples situated above the core as well as the neutron no ise of self power neutron detectors (SPNDs) located in the upper part of the core were analyzed and subcooled boiling was detected. The chan ges observed in the noise functions due to the presence of bubbles wer e compared to the behaviour of the same functions measured by other au thors during boiling simulated experiments. The cross-sectional averag e volumetric void fraction was calculated following a profile-fit mode l of subcooled boiling and used to interpret the temperature and neutr on fluctuations measured in the PWR. Copyright (C) 1996 Elsevier Scien ce Ltd