Authors & Affiliations
Golub E.V., Sorokin A.P.
A.I. Leypunsky Institute for Physics and Power Engineering, Obninsk, Russia
Sorokin A.P. – Deputy Director of Department for NPPS, Dr. Sci. (Tech.), A.I. Leypunsky Institute for Physics and Power Engineering.
Coolant velocity in the reactor core channels is an important thermohydraulic parameter determining the heat balance of channel.
Flow distribution in channels is determined by the controlled distribution of heatup and power density in the core channels of the three-loop reactor – KM-1 test facility with heavy metal coolant, that can be interpreted as flow rate distribution only when the design value of channel flow area is retained. It is not allowed in the operating reactor by virtue of thermal deformations of core components and technological uncertainties within the tolerance limits.
Radial flow rates corresponding to the retention of design cross-section of channels were distinguished using the least-square method treatment of relative flow rates, and the appropriate heatups were calculated.
A considerably lower correlation of energy release into the core channels with controlled heatup, than with the calculated ones was shown, as well as absence of correlation with their difference. The principal cause is shown analytically – dissipation of flow rates due to deviations of flow areas from the design values in the non-uniform temperature fields in the reactor operating conditions. Proportionality of heatup deviations to the deviations of flow areas was shown in the linear approximation, and the formula of flow rate distribution determination in the channels in the RF (reactor facility) operating conditions was obtained.
It was found in three random standard operating conditions, that in the array of channels located at a distance of at least two lattice pitches from the CPS rods and the periphery, the relative flow rates in the standard channels exceed the estimates on a constant design flow area, and the maximum deviations from the design velocities were equal to 26%. In this case the deviation of cross-sections from the design size were observed within the range from –7,5% to +19%.
reactor core channels, flow area, deviations, coolant velocity, heatup, power density, correlation
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