The formulation of the long term, three stage Indian nuclear programme was based on judicious utilization of domestic reserves of uranium and abundant reserves of thorium. The emphasis of the programme was on self-reliance, with thorium utilization as a long term objective.
The three stages of the Indian nuclear power programme are:
Stage I: This stage envisages construction of natural uranium fuelled, heavy water moderated and cooled pressurized heavy water reactors (PHWRs). Spent fuel from these reactors is reprocessed to obtain plutonium.
Stage II: This stage envisages construction of fast breeder reactors (FBRs) fuelled by plutonium produced in Stage I. These reactors would also breed 233U from thorium.
Stage III: This stage would comprise power reactors using 233U/thorium as fuel.
The Indian nuclear power programme commenced with the construction of the Tarapur Atomic Power Station (Tarapur 1 and 2) boiling light water reactors (BWRs) which use enriched uranium as fuel and light water as the moderator. These units were set up in 1969, on a turnkey basis, by General Electric Company (USA), essentially to ‘jump start’ the nuclear power programme and demonstrate the technical viability of operating them within the Indian regional grid system, which was, at that time, relatively small. Subsequently, India selected HWRs for
Stage I of its nuclear power programme because of the following inherent advantages:
• The HWR uses natural uranium as fuel, which, being readily available in India, helps cut heavy investment on enrichment, which is capital intensive.
• The uranium requirement for the HWR is the lowest, and plutonium production, required for FBRs (planned for the second phase of the Indian nuclear power programme), is the highest.
• The infrastructure available in the country was suitable for undertaking the manufacture of equipment for the HWR reactor.
India started constructing pressure tube HWRs with Rajasthan 1, which started commercial operation in 1973. When AECL assistance stopped during construction of Rajasthan 2, DAE, and eventually the Nuclear Power Corporation of India Ltd (NPCIL), completed it and constructed and operate a total of eight HWR units to date,
mostly 220 MW(e) units. An additional six units are under construction, of which two are 500 MW(e) units, with eight more units in the planning stage.
India has progressively carried out a large number of significant improvements in the basic design (from Rajasthan 1 to Kakrapar 2 and the 500 MW(e) reactors).
In parallel with the indigenous self-reliant three stage programme, India is also searching for suitable sources for the import of light water reactor technology which conforms to the latest safety standards and which is economically attractive. The recent deal with the Russian Federation for the setting up two 1000 MW(e) light
water reactor units at Kudankulam is a step in this direction.