Technical accomplishments aside, the true significance of the reactor on board India’s first Indian nuclear submarine achieving criticality is strategic. INS Arihant marks the first step towards completing the third component of the triad of air, mobile land-based and sea-based deterrent forces envisaged in India’s nuclear doctrine. The advantage of nuclear submarines over conventional ones is their ability to remain under water for long without refuelling, and thus to travel long distances. It will, however, be a long haul from here on towards making this sea-based naval nuclear asset fully operational. Having validated the performance of the primary power pack, it has to be proven that the propulsion system can indeed be driven by nuclear power. The subsequent sea trials, which would involve complex speed, pitch and rolling manoeuvres, will test the ability of the reactor to withstand high acceleration loads and the fast response needed for rapid power ramp-up. These issues have posed serious nuclear fuel, material and engineering challenges, not hitherto encountered in land-based reactor systems. The Department of Atomic Energy and the Defence Research and Development Organisation deserve credit for successfully overcoming these. The full fleet, according to reports, will include seven such boats over a decade. This calls for enhanced submarine building and reactor fabrication capacity. More important perhaps would be preparing the operating personnel psychologically for long endurance inside an underwater cocoon.
Considering that most submarine accidents have involved nuclear submarines — most of them Russian — safety assumes great importance. Especially since there seems to have been substantial Russian assistance in the design of both the boat as well as the power pack. From a safety perspective, there is a larger issue that needs to be addressed. The entire strategic sector has remained out of purview of the Atomic Energy Regulatory Board and the safety overview system in place for strategic nuclear systems has never been discussed in public. The issue obviously gets more complicated for sea-based nuclear assets. Moreover, the DRDO and the Indian Navy, under whom the nuclear submarines will operate, have limited expertise in nuclear-related matters. In terms of technology, India has now clearly demonstrated that it has the requisite expertise to launch a parallel stream of enriched-uranium based Pressurised Water Reactors (PWRs). The land-based prototype 80 MWt PWR reactor at Kalpakkam is expected to serve as a platform for the proposed chain of 900 MWe PWR power reactors in the country, whose design is stated to have been completed. But that would call for a substantial increase in uranium enrichment capacity as well.