DETERMINATION OF MASS-FLOW RATES FROM MEASURED IN-CORE 2-PHASE FLOW TRANSIT TIMES IN A BOILING WATER-REACTOR

By analysing the neutron noise signals of the in-core detectors, the t wo-phase flow transit times have been measured for unit 1 of Tarapur A tomic Power Station (General Electric Boiling Water Reactor). Our stud y has shown that it is reasonable to identify the fluid velocity deriv ed from the measured transit time with the volumetric flux. This inter pretation offers the advantage of determining the mass flow rate by us ing the measured transit time and the steam quality obtained by the he at balance. Further, it is feasible to infer gross flow rate changes b y combining the calculated value of the transit time as a function of flow with the periodic measurements of transit time over the operating cycle of the reactor.