India's Next-Gen S5 Submarines May Get Over 200MW Nuclear Reactors

India's upcoming fleet of S5-class ballistic missile submarines (SSBNs) could feature a more powerful nuclear reactor than initially planned. The Bhabha Atomic Research Centre (BARC) had been developing a 190-megawatt (MW) pressurized light-water reactor (PWR) fueled by enriched uranium for these submarines, but new developments suggest that the power output may be increased beyond 200MW to meet future operational demands.

The S5-class submarines, expected to have a submerged displacement exceeding 13,000 tons, are designed to serve as the backbone of India’s underwater nuclear deterrent. The 190MW reactor, nearing completion, was considered adequate for the first batch of S5 boats, aligning with their stealth-oriented operational profile. However, with evolving threats and the need for advanced onboard systems, the Indian Navy and BARC are now exploring a more potent power plant.

A higher-output nuclear reactor would provide increased electrical power for advanced weapon systems, sensors, and propulsion improvements. This potential upgrade aligns with broader trends in submarine reactor technology, which emphasize enhanced fuel efficiency, advanced core designs, and superior safety features.

The Navy plans to build the S5-class submarines in multiple pairs, allowing gradual technological upgrades over time. While the first group is likely to use the 190MW reactor, later iterations—potentially post-2040—could incorporate the enhanced power plant. The extent of this upgrade is still under discussion, with preliminary indications suggesting it could surpass 200MW. However, such a transition depends on structural modifications within the submarines to accommodate the increased reactor size and power output.

Additionally, a modified version of the 190MW reactor is also planned for India’s upcoming nuclear-powered attack submarines (SSNs), which will have a submerged displacement of around 8,000 tons. These SSNs require a reactor optimized for agility and speed, showcasing the adaptability of BARC's reactor technology across different submarine classes.

If successfully developed, the upgraded nuclear reactor could significantly boost India's naval capabilities, ensuring the S5-class submarines remain at the cutting edge of underwater warfare well into the future.