Bhabba's quickly realized that India's uranium resources were small, while it had much larger thorium resources. In order to assure indian strategic energy independence, Bhabba decided to build India's long term nuclear future on a thorium fuel cycle, rather than the uranium fuel cycle. There is little doubt that Bhabba envisioned India as not only a nuclear powered state but a nuclear armed state as well. Yet he placed priority on the development of a nuclear power program. India did not truly become a nuclear armed state, until it conducted nuclear weapons tests in 1998, long after Bhabba's 1969 death.
Bhabba envisioned a three stage nuclear plan. In the first stage conventional reactors would produce reactor grade plutonium (RGP) as a bye product of power production. In the United States, RGP is regarded as a nuisance, but Bhabba saw it as an opportunity. When enough RGP had been accumulated, Bhabba saw that it could be used to fuel sodium cooled fast breeder reactors. In the second stage of Bhabba's plan, a fast reactor technology would be developed that would breed both thorium and uranium. Fast reactors run on plutonium, and in Bhabba's plan, the Indians would produce at least on gram of plutonium for every plutonium gram burned. Breeders operate on something called a neutron economy. There have to be enough neutrons available to produce fuel for the continuing nuclear process. In addition extra neutrons can produce surplus fuel that could be used in other reactors. It was Bhabba's plan to use the extra neutrons to convert thorium into U-233. Now u-233 makes excellent fuel for conventional reactors, and indeed in heavy water reactors a pure thorium-U-233 fuel cycle has a very good nuclear cycle. So good that it can at least break even in nuclear fuel production. Bhabba's third stage was to use specially designed Heavy water reactors as thorium converters, that is to produce enough fuel from thorium to keep the process running for along time.
The Bhabba plan committed India to heavy water technology, so early Indian reactor development was based on collaboration with the Canadians who had with the British, developed Heavy Water reactors during World War II. Eventually in 1974 when India tested its first nuclear device, the Indians had a parting of the way with Canada, over proliferation related issues, and the Canadians stopped providing the Indians support for its nuclear power development.
By 1974 the Indians had built one small heavy water CANDU power reactor, and were in the midst of building another. Although they were not entirely prepared to do so in 1974, the Indians took over the design and production of their own reactors. The started with the Canadian small CANDU reactor whose design they had inherited, and gradually modified it to improve it. While doing so, their technology got better and better. In fact by the end of the 20th century, the Indians were producing small PHWRs at very competitive costs. By then they had build a small sodium cooled fast breeder test reactor, which they used to research their combined uranium and thorium fuel cycle. At first they had a lot of problems, but as time passed, they began to master the very challenging Liquid Metal Fast Breeder technology.
Today the Indians are building a mid size commercial fast breeder prototype, which is expected to go on line next year. It is expected to be followed up by six more commercial fast breeders to be completed by 2023. While this is going on, a second generation of Indian commercial fast breeders is under development. Indian plans call for well over 100 fast breeders to be completed by the mid point of this century.
In addition to its very ambitious fast breeder development program, the Indians are developing their third stage Thorium fuel cycle heavy water converter, the AHWR-300. The prototype is expected to go on line in 2018.
In order to supply the plutonium to run so many fast breeders, the Indian plan is to build many foreign reactors. Reactor manufactures are also in the nuclear fuel business, and along with the reactors expect to supply their fuel for a long time to come. Since Indian uranium supplies are limited foreign reactors mean fairly assured fuel supplies. When that fuel has been used, the Indians plan to extract RGP from it, and then use the RGP to start their fleet of FBRs, while using the remaining "depleted uranium" to breed more plutonium in their FBRs. The need to find sources of imported uranium explains why India is buying foreign reactors as if they were going out of style. In fact, Indian PHWRs would probably cost less and require a less expensive industrial base, but uranium supplies would be less certain.. The expansion of the Indian industrial base, required to build foreign reactor has an economic side benefit. India expects to produce large reactor components for the global as well as the local market.
The purchase of foreign reactors does not mean that India has abandoned Homi Bhabha's three stage plan. Quite the contrary, that plan is being expanded and elaborated. It has lead India in the second decade of the 21st century to be among all nations to have the clearest path forward into the post carbon era. However, as good as Homi Bhabha plan was, in the 21st century it is not without its flaws.
The most conspicuous flaw is the plan's complexity. Currently the plan calls for the use of three distinct reactor technologies, each with its own path of development. In addition to its complex reactor technologies, the Indian plan calls for multiple, expensive and complex fuel reprocessing technologies. Although a simpler plan was not possible in the 1950's, this was no loner the case in 1970 after Oak Ridge National Laboratory had demonstrated the potential of Molten Salt Reactor technology. Not only was a thorium breeding MSR possible, but it could be started with RGP and then switched over to U-233, replacing both fast breeder and AHWR in Bhabba's plan. In addition the Thorium Breeding Molten Salt Reactor, the LFTR offered technically superior, less complex, and less expensive fuel reprocessing system, that could take place in the reactors "hot cell," where the diversion of fissionable materials would be completely unlikely. In addition the MSR technology "bag of tricks" offers other potential paths for proliferation avoidance. Those several proliferation avoiding methods could be used individually or simultaneously. A LFTR based plan, would most likely to have proceeded more rapidly, and to cost far less to develop, as well as costing far less to build and manage, than the Bhabba three stage plan.
But there should always be a Plan B, in case Plan A does not work. The argument in this White Paper is that Plan A for post-carbon energy should involve the mass deployment of LFTRs. Plan B would be the Homi J. Bhabha three stage plan.