Dr Anil Kakodkar, chairman of the Atomic Energy Commission (AEC), said that India’s modest uranium reserves has made the rapid development of a closed nuclear fuel cycle involving efficient conversion, reprocessing and recycling of its much larger thorium reserves to achieve a growth rate in nuclear energy production that matches the projected demand.

With thorium reserves estimated to be 5-6 times the known availability of uranium sources, utilisation of this non-fissile material for large-scale energy production has remained an important goal of India’s nuclear power programme.

India owns nearly a third of the world’s thorium reserves. Thorium has to be converted to a fissile material, U-233.

A three-stage nuclear power programme, based on a closed nuclear fuel cycle, involves natural uranium fuelled PHWRs, Fast Breeder Reactors using plutonium-based fuel and advanced nuclear power systems for use of thorium. Developing the technologies pertaining to the last of these has been a part of the ongoing activities in India.

Advanced nuclear systems that use plutonium resources optimally to maximise conversion of thorium to U-233, extract power in situ from the thorium fuel and recycle the bred U-233 in future reactors, are in the process of design and development.

The two major options available to implement thorium utilisation, even while continuing with the PHWR and FBR programmes, are advanced thermal systems such as the Advanced Heavy Water Reactor (AHWR) and the Accelerator-Driven Subcritical Systems (ADSS).

The AHWR project provides a focal point for the development of in the efficient use of thorium. It will also help in conserving and further enhancing the research and development expertise relating to heavy water reactors.

In the ADSS, high-energy proton beams generate neutrons directly through spallation reaction in a non-fertile/fissile element like lead. A ‘synergic scenario’ between AHWR and ADSS systems has bee worked out recently.