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Channel Outlet Temperature Measurement for Various Flow at Different Core flow Conditions in PHWR Nuclear Power Plants

Vinod Nayak , Dr.A.M.Shaikh ,S.K.Subramanya,K.V.R.Pandit,Deepak.M.Pai

In a Pressurized Heavy Water Reactors (PHWR) Channel Outlet Temperature is a function of Channel Power and Channel Flow. Channel Flow can be varied for different Inlet and Outlet header pressures. Calculation of Channel Out let Temperature at various Flow distribution for the constant Channel Inlet temperature and Power Level is necessary for the prediction of different states of the core behaviour at various Loss of Coolant due to the various header and feeder line leakage or rupture. Channel out let temperature is an absolute safety featured parameter in nuclear reactors. Temperature monitoring for individual channels for different channel flow is a challenging task and Individual channel outlet temperature is necessary for calculating the coasting down pattern of the flow during slow reduction of gross flow after loss of power to the circulating pumps. This Temperature difference (Outlet temperature- Inlet temperature) is proportional to the thermal power produced by each channel. Since measurement of out let temperature using instruments in all the channels is not feasible due to its complexity and economic considerations. An algorithmic approach is modelled for calculating the Channel Outlet Temperatures simulating the flow at various header pressure conditions which will change at various operating as well as at different shut down (S/D) conditions. The design Channel Outlet temperatures are matched with the calculated Channel Outlet temperatures for the design flows and considering the various losses due to the flow barriers at normal operating conditions. The Channel outlet temperature is simulated at different operating and at various core flow states by the channel flow which is in turn changed by changing the inlet (I/L) header and outlet (O/L) header pressures. An algorithm is presented to compute the Channel Outlet Temperature at various Channel Flows.