Investigation of circulating temperature fluctuations of the primary coolant in order to develop an enhanced MTC estimator for VVER‐440 reactors, Centre for Energy Research
26th Symposium of AER on VVER Reactor Physics and Reactor Safety (2016, Helsinki, Finland)
Core surveillance and monitoring continues
Abstract
INVESTIGATION OF CIRCULATING TEMPERATURE FLUCTUATIONS OF THE PRIMARY COOLANT IN ORDER TO DEVELOP AN ENHANCED MTC ESTIMATOR FOR VVER-440 REACTORSSándor KISS, Sándor LipcseiCentre for Energy Research, Hungarian Academy of Sciences P. O. Box 49, H-1525, Budapest, Hungary sandor.kiss@energia.mta.hu, sandor.lipcsei@energia.mta.huABSTRACTOur aim was to develop a method applicable to use in normal operation and based on noise diagnostics for estimation of the moderator temperature coefficient of the reactivity (MTC) for the Paks VVER-440 units. The method requires determining core averaged neutron flux and temperature fluctuations. Circulation period of the primary coolant, transfer properties of the steam generators, as well as the source and the propagation of the temperature perturbations and the proportions of the perturbation components were investigated in order to estimate the feedback caused by the circulation of the primary coolant. Finally, after developing the new MTC estimator, determining its frequency range and optimal parameters, trends were produced based on an overall evaluation of measurements made with standard instrumentation during a one year long period of all four units of the Paks NPP.Keywords: MTC estimation, VVER-440, circulation period of the coolant, propagating perturbations, transfer properties of the steam generator, average loop model26th Symposium of AER on VVER Reactor Physics and Reactor Safety 31 10 – 14 October 2016, Helsinki, Finland