Kalpakkam milestone: India’s nuclear fuel recycling programme is well on its way

When a reactor goes critical, it means that a single atomic fission event within it releases enough neutrons to produce exactly one other fission, on average. This is enough to sustain the process of breaking uranium into lighter elements, destroying some mass and creating energy at a rate defined by Einstein’s famous equation, E=mc².

If the fission is sub-critical, every fission of a uranium atom would not lead to another fission and the chain reaction would fizzle out. If the reactor goes super-critical, each fission would lead to multiple new fissions, sending the reactor into uncontrollable overdrive.

The purpose of our fast breeder reactor is to use plutonium recovered from the spent fuel of first-stage fission reactors to ‘breed’ yet more plutonium. Once sufficient quantities of this stuff are produced, it can be used to interact with locally available thorium in the plan’s third stage to produce uranium.

Consider the science of it. Thorium, uranium and plutonium all belong to a class of elements called ‘actinides.’ Bombarded under intense heat by neutrons in a nuclear reactor, uranium turns into plutonium. This plutonium exists in the spent fuel of a regular reactor; if it is not recovered, it renders this waste material highly radioactive and toxic, making disposal a challenge.

However, once it is recovered, an oxidized version of it can be mixed with a uranium oxide to produce ‘Mox’ fuel for a fast breeder reactor. Fissile plutonium interacts with uranium and this mixture works like enriched uranium. In addition to energy, a fast breeder reactor produces a lot more of plutonium, which can be used to produce fresh batches of Mox and yet more plutonium.

Once enough of it has been created, a uranium blanket over the reactor’s core can be replaced with one of thorium; this can be turned into fissile uranium, which in turn would serve as fuel India’s standard pressurized heavy water reactors (PHWRs).

Think of it as fuel recycling.

Work on our fast breeder reactor began in the early 2000s, before the India-US nuclear deal of 2008 released us from the shackles of a tech-denial regime. So this fast breeder reactor’s design and construction are indigenous. It has taken time, but India has gained notable expertise in this field to match its PHWR proficiency.

Yet, a lobbying effort is underway that cites slow progress on our three-stage project to push for a technology under development in the US which would use a mix of high-assay low enriched uranium and thorium as fuel for PHWRs.

Now that our prototype fast breeder reactor has attained criticality, we should ignore any attempt to kill this plan. Let’s persist with the fast-breeder path we chose till its final stage. It will help minimize our need for uranium imports.

In an uncertain world where vital supplies could be subject to geopolitical constraints and past understandings have been falling apart, it is crucial that we push for self-sufficiency to the extent possible.

Recent reforms aimed at obtaining clean energy from nuclear plants have laid the ground for small modular reactors to be set up. These projects will be import-intensive but are welcome too. And if viable fusion reactors being developed in the US (and China) arrive in the meantime, that may be the only reason to abandon our homegrown nuclear energy programme.