India has been using imported enriched uranium and is under International Atomic Energy Agency (IAEA) safeguards, but it has developed various aspects of the nuclear fuel cycle to support its reactors. Development of select technologies has been strongly affected by limited imports. Use of heavy-water reactors has been particularly attractive for the nation because it allows uranium to be burnt with little to no enrichment. India has also done a great amount of work in the development of a thorium-centred fuel cycle. While uranium deposits in the nation are extremely limited, there are much greater reserves of thorium, and it could provide hundreds of times the energy with the same mass of fuel. The fact that thorium can theoretically be utilised in heavy water reactors has tied the development of the two. A prototype reactor that would burn uranium-plutonium fuel while irradiating a thorium blanket is under construction at the Madras/Kalpakkam Atomic Power Station.