South Korean and Japanese Nuclear Submarine Propulsion

South Korea (SK) has carried out research on building a nuclear powered submarine (aka KSS-N, KSSX-N and SSX) since the 2003 (codename) “362 initiative” if not longer ago. But that 362 initiative was officially (perhaps not actually) terminated in 2004 once it became public - under ( likely) US, Chinese, Japanese and Russian, pressure.

The lead time and technical hurdles for SK to develop a submarine reactor, and specialised submarine to use it, are huge. Only the US, Russia, China and France (with much larger defense budgets than SK) have fully designed and produced submarine reactors. To avoid the huge cost even a big player (the UK) used/(still assisted by) US designs and India uses Russian.

Early speculation that SK would shrink and modify its existing small land-based SMART reactor seems misplaced. SMART is unnecessarily large (for SK proposed 4,000 tonne submarine) at 350 MWt (thermal), which if developed for submarine would translate to 70 MWe (electrical). More significantly SMART uses low power/weight ratio 4.8% LEU fuel with an overly frequent 3 year refueling cycle.

Unless SK is conducting an extremely well hidden indigenous reactor for submarine effort one preliminary step might be to produce a reactor powered ship. SK’s DSME has had hints, but no details, for years. Go to the DSME technology website > hover on R&D and you will see “Nuclear Propulsion Ship” > Click on Nuclear Propulsion Ship and you will see Arctic Drill Ship. Such a ship could in future use a reactor for its ice-breaker propulsion function and for its drilling function. Neither SK nor DSME seem to provide further details on nuclear ship plans.

Instead SK has approached other countries for technology transfer assistance for a reactor and a specialized submarine to use it (the subject of my next article).

JAPAN

Japan's nuclear propelled ship Mutsu with Reactor and auxiliary machinery compartments shaded. (From Submarine Matters' June 17, 2016 article).

---

Japan built and operated a nuclear propelled ship – the Mutsu (diagram above) – from 1968 to 1992 with a reactor developed by what is now the Japan Atomic Energy Agency (JAEA). From that experience Japan may have quietly conducted further design research on submarine reactors within the JAEA under the guidance of the Japanese Ministry of Defence (MoD). The most likely countries to assist Japan are the US and France.

Pete