Nuclear submarines are powered by small atomic reactors fitted into their hulls. Can they be used to meet the requirements of small, scattered communities living in remote parts of the country? Can they be clustered together to feed into the grid?

"Scientific American" has recently discussed this issue pertaining to modular nuclear reactors. The magazine notes that it was developed in the Los Alamos National Laboratory in the United States and is now being offered by Hyperion Power, situated in Santa Fe. It is a US$50 million enclosed reactor roughly 1.5 meters wide and 2.5 meters high, capable of generating 25 megawatts of electricity.  Buried underground it could last for at least seven years. The promotional sales line compares these reactors to an oversized underground battery, which is an exaggeration, since the heat produced by the reactor must heat water and produce steam for revolving the turbines for producing electricity. Hence, a steam turbine, generator and cooling device would be additionally required, apart from the project colony that would have to be located over ground.

It is tempting to believe that these reactors could serve the local population in remote, inaccessible parts of the country by augmenting their developmental programs. Transmission and distribution costs would also be minimized that add considerably to the costs of electricity for the consumer. These modular reactors could also be compared to wind, solar, and geo-thermal energy projects that have catalyzed local development and helped in stemming the mad rush to the cities in search of employment.

What is the downside to this solution for the energy crisis? There is initially the matter of costs. No doubt, a modular nuclear reactor can be manufactured elsewhere and transported to the location site. A costing exercise in the Indian context is needed to compare the total construction and generating costs of these reactors along side other energy sources (including light-water and heavy water nuclear reactors).  It requires emphasizing that modular nuclear reactors also require highly skilled engineers, working in isolated locations. There are personnel issues here of recruitment, training and retention that need no elaboration. Moreover, these reactors work at roughly 500 degrees Celsius, somewhat higher than traditional reactors, and require cooling by a liquid metal like sodium to enable fast neutron fission, which is an inherently dangerous technology. In other words, modular nuclear reactors, like their larger cousins, are also capable of having a meltdown accident due to uncontrolled fission.  Necessarily, these reactors must be equipped, therefore, with control rods to avoid this contingency, but the inherent risks involved cannot be wished away as non-existent. 

Furthermore, there is the problem of nuclear wastes, which remain radioactive for infinitely long periods of time, and for which a permanent repository has yet to be found. The United States, for instance, has not been able to operate its Yucca Mountain storage site in Nevada due to unresolved problems of background radiation and the stability of the geological structures involved over the lifecycle of the nuclear wastes. In India, the possibility of vitrifying nuclear wastes in silica blocks is accepted, but has not been attempted on any scale. This problem will be compounded with modular reactors being scattered across the country, raising serious safety and security questions in a milieu where terrorism related incidents are not infrequent.  Transporting these wastes to a central disposal site raises additional problems of their safety and security en route that are not trivial. Some theoretical work is proceeding to devise an atomic reactor that would be proliferation resistant by converting highly radioactive waste into less harmful fission residues, but no breakthrough has yet been achieved. In other words, the problems of handling nuclear wastes shall be greatly compounded with modular reactors being sited in different locations. 

So, how does all this concern India and its Atomic Energy Commission? There are 20 atomic power reactors operating in the country with a total installed capacity of 4500MWs. Apparently, two more 700MW pressurized heavy water reactors are being planned for Andhra Pradesh and Madhya Pradesh.  Three 1000MW light water reactors are being planned for Gujarat, Andhra Pradesh and West Bengal. Work on these five projects would start in 2012. A sixth 220MW reactor in Rajasthan has just gone on stream. Two 1000MW reactors, along with a 500MW Prototype Fast Breeder Reactor in Tamil Nadu, and another 220MW reactor in Karnataka are scheduled to go critical in the next two years. No doubt, the Atomic Energy Commission has estimated whether modular nuclear reactors will serve India’s purposes. However, this issue is worth discussing in the public domain to evaluate its pros and cons to be clear on what should be the national policy towards this nuclear energy option.  Apparently, Ms. Hyperion plans to deliver its first modular nuclear reactor by 2013.