Condenser circulating water system for 500 MWe units (Paper No. 7.7)

Condenser Circulating Water (CCW) system for Tarapur Atomic Power Project (TAPP), is a once-through system using sea water for cooling, envisaging a flow of 115,000 M3/hr to dissipare a condenser heat load of 1.062x10 kcal/hr per unit to the sea. It is proposed to use pumps of 30,000 M3/hr developing 17.2 MWC head. Such large capacity pumps are to be manufactured indigenously for the first time. Condensers with titanium tubes and titanium clad MS tube sheets are proposed to be used keeping in view the corrosive and erosive nature of the sea water. On load tube cleaning system (OLTCS) using sponge balls and debris filters located on the inlet of the condensers are to be used to maintain low fouling factors in the condenser tubes. Based on techno-economic comparison between the steel conduits and RCC tunnels, it has been proposed to use RCC tunnels for the CCW system. Hot water outlet from the condenser and other auxiliary systems is led through a specifically designed discharge structure. Model studies were carried out at Central Water and Power Research Station (CWPRS), Pune for the various discharge configuration in order to achieve the stipulated temperature differentials. In order to handle the large amount of cooling water, centre flow rotating band type screens are considered on the inlet of pumps. These types of screens though very popular in power station abroad, are yet to be installed in any power station in India. The philosophy of unitised concepts has been adopted and each unit is fed from an independent CCW system. To safeguard against the corrosive nature of sea water all pumps internals are proposed to be manufactured with SS 316 and all portions of the steel pipe lines shall be internally lined with cement mortar. The design of the CCW system has been optimized based on minimum total evaluated cost. The paper highlights the salient features of the CCW system designed for the 500 MWe Nuclear Plants being set up at TAPP and RAPP. (author)