India's path to energy independence has been a long and challenging one. Unlike many developed nations, India doesn't have an abundance of natural uranium. Instead, it relies on imported oil and gas to meet its energy needs. To break free from this dependence, India's nuclear scientists have been working on developing fast breeder technology.

The Prototype Fast Breeder Reactor (PFBR) in Tamil Nadu's Kalpakkam has finally achieved criticality, a significant milestone in India's nuclear journey. This achievement marks the beginning of a long-planned pathway towards energy independence.

But why is fast breeder technology so crucial for India? The answer lies in the country's unique energy constraints. India's nuclear scientists have been working on this technology for decades, not as a prestige project, but as a necessity.

India's nuclear vision was first laid out by Dr. Homi Jahangir Bhabha, a renowned scientist who designed a three-stage nuclear power program tailored to India's resource profile. The first stage uses natural uranium in Pressurised Heavy Water Reactors (PHWR), which generate electricity and produce plutonium 239 as a by-product.

This by-product is crucial, as it allows India to create a closed fuel cycle, a capability available to only a handful of nations. By mastering reprocessing technology, India has been able to produce plutonium and use it as fuel in fast breeder reactors.

But how do fast breeder reactors work? Unlike conventional reactors, they use plutonium as fuel and operate with fast neutrons. The breeding ratio for the PFBR is about 1.05, which means that the spent fuel will contain more than the amount of fuel that went into the reactor.

This might seem counterintuitive, but it's all about the physics of nuclear reactions. Fertile materials like uranium 238 absorb neutrons and convert into new plutonium, which can then be used as fuel. In later stages, thorium will replace uranium as the blanket material, producing uranium 233, the fuel for India's third-stage reactors.

India's journey towards energy independence is not without its challenges. Japan's Monju fast breeder reactor suffered a serious setback in 1995, while France's Superphnix faced repeated technical issues and poor operational availability. The United States also abandoned its breeder program due to sufficient uranium supplies.