https://www.telegraph.co.uk/news/2025/02/12/china-mystery-nuclear-battery-submarine-taiwan-war-us-navy/
China’s new nuclear-battery attack submarine – a unique hybrid boat running on batteries like a conventional sub but which recharges them using a tiny nuclear reactor – could be the ultimate near-shore defence sub, and a big problem for US and allied forces in the western Pacific.
The submarine first appeared in commercial satellite imagery of the Wuchang shipyard in Wuhan, China back in April. Five months later, the Type 041 boat reportedly suffered an accident at its moorings – and apparently sank.
While observers wait for signs Wuchang is repairing that first Type 041 or building new examples of the class, analysts are scrutinising its potential capabilities. Most notably the type seems to have a unique propulsion system – one that sidesteps longstanding engineering challenges in order to deliver a quiet attack submarine for near-shore operations, one that can stay submerged for long periods of time in order to preserve its stealth. The Type 041 is reportedly the first submarine with a tiny nuclear reactor that, while too small to power the entire boat, is big enough to charge the batteries for submerged operations.
This is a novel approach to the problem of powering a mostly or entirely non-nuclear submarine while it’s underwater. Conventional diesel-electric submarines recharge their batteries using old-fashioned diesel engines. For that, they have to surface or at the least put up a “snort” air intake mast at periscope depth – potentially exposing them to detection and attack. The main alternative is to use nuclear power for propulsion, which produces a very capable boat but is very expensive.
Some navies mitigate this vulnerability by installing so-called “air-independent propulsion” systems in their smaller submarines. There are many different types of AIP. Some burn liquid oxygen. Others draw power from fuel cells. The Japanese navy builds attack submarines powered by lithium ion batteries, which can hold much more energy than normal batteries but are regarded as too dangerous to use in subs by most designers.
All AIP systems are complex, delicate and – when badly made – dangerous.