‘Thorium-based n-power key to securing energy independence’

To what extent does the scale-up of PHWR capacity offer an opportunity for faster transition to thorium-based nuclear power generation?

Transitioning to thorium-based nuclear power generation is critical to securing energy independence. This requires building sufficient inventory of fissile U233 (uranium 233) through irradiation of thorium. Since our assessed domestic uranium resources when the three-stage programme was formulated were modest, the required irradiation capacity was not possible. Building such capacity through fast reactors, which can multiply through breeding of fissile fuel, was thus essential.

Now that we can access uranium from the international market, the thermal reactor capacity is on a growth path, with the Nuclear Energy Mission targeting 100GWe nuclear power capacity, with PHWRs constituting the bulk. This scale-up is clearly an opportunity to start producing fissile U233 at scale in PHWRs and enable a faster transition to thorium-based nuclear power generation. It is indeed possible to have Thorium-HALEU based drop-in fuel for PHWRs, which would also lead to economic, safety and security benefits while efficiently converting thorium to U233.

How important is the need for additional financial resources and new players in potentially scaling up PHWR capacity to 50-75 GWe (1GWe or gigawatt electric is equivalent to 1,000 mega watts)?

Scaling up PHWR capacity to 50-75 GWe by the target date of 2047 would require an average annual capacity addition of around 3 GWe, which would mean adding five to eight reactors every year depending on the mix of 700 MWe and 220 MWe units. This would require significant additional financial resources. Also, one would need many other players from public as well as private sector to be brought in, with NPCIL (state-owned Nuclear Power Corporation of India Ltd.) playing the role of technology provider, capacity builder, facilitator and mentor while implementing its own programme.

The SHANTI Act opens up the possibility of more imported LWR-based nuclear projects. How do you view their potential?

I have always viewed imported Light Water Reactors (LWRs) as an additionality. Given our large and growing energy needs, and deficit in our implementation capability, such additionalities are helpful provided they are economically competitive and consistent with our nuclear fuel cycle policies. We should prioritise development effort for futuristic technologies needed for our country (metal fuel reactors, molten salt reactors, high temperature reactors, thorium fuel cycles etc) and leverage proven imported technologies.

Estimates suggest that a 1,000 MW-LWR would need about 25 tonnes of enriched fuel per year at 80% PLF. Given the fuel price of around $1.76 million per tonne, the fuel cost for an LWR plant would translate to around Rs 350 crore per annum (at 1$ = Rs 80). Fuel estimates for PHWRs would perhaps be lower. So how do you see the trade-off in combining thorium with small amounts of enriched uranium in PHWRs and how much more viable is this proposition from a cost perspective?

In terms of mined uranium needed to support a given nuclear power generation capacity, PHWRs are more efficient. Fuel fabrication and back-end fuel cycle costs in PHWRs fueled with natural uranium would be higher on account of higher fuel throughput as the burn-up is low. These costs would come down with the use of enrichment in PHWR fuel. Fueling cost with HALEU-thorium fuel in PHWR works out to be lower than with natural uranium.