The Three-Stage Nuclear Power Programme is a strategic concept and long-term plan for India's nuclear energy sector, designed to ensure energy security and technological self-reliance. It was conceived by physicist Dr. Homi J. Bhabha in the 1950s to solve the problem of India's limited domestic uranium reserves (around 1-2% of the global total) by leveraging its vast thorium reserves (around 25% of the world's known reserves). The programme is based on a closed nuclear fuel cycle and is overseen by the Department of Atomic Energy (DAE).
The mechanism involves three sequential stages to convert fertile Thorium-232 into fissile Uranium-233, as thorium cannot be used directly as a fuel. Stage I utilizes Pressurised Heavy Water Reactors (PHWRs) fueled by Natural Uranium to generate electricity and produce Plutonium-239 (Pu-239) as a byproduct. Stage II employs Fast Breeder Reactors (FBRs), which use the Pu-239 from the first stage to generate more fissile material than they consume, converting fertile Uranium-238 into more Pu-239. Crucially, the FBRs will also use Thorium-232 in a blanket to breed Uranium-233, which is the fuel for the final stage. Stage III will use Advanced Nuclear Power Systems or thermal breeder reactors fueled by Uranium-233 and Thorium-232 to achieve a self-sustaining fuel cycle, exploiting India's thorium wealth.
A significant recent change occurred on April 6, 2026, when the Prototype Fast Breeder Reactor (PFBR) at Kalpakkam, built by Bharatiya Nabhikiya Vidyut Nigam Limited (BHAVINI), attained its first criticality, officially marking the transition to Stage II. The programme also connects to the SHANTI Act, 2025 (The Sustainable Harnessing and Advancement of Nuclear Energy for Transforming India Act, 2025), which was enacted to modernize the legal framework.