LEU More Acceptable for South Korean Nuclear Submarines

Nuclear propulsion gives ballistic missile submarines significant strategic and tactical advantages. So, facing a nuclear armed North Korea, South Korea is displaying the signs of seeking such a capability. Nuclear propulsion provides for much more rapid discrete movement and much longer term discrete/submerged operation.

On Oct 25, 2019 I wrote the article South Korea Looking at France’s Barracuda SSN or Just the K15 Reactor. It is significant that France’s K15 reactor, that powers its Barracuda (Suffren-class) SSN, uses Low Enriched Uranium (LEU) of 7.5% (see page 66 here). LEU is more acceptable, from a nuclear proliferation politico-legal viewpoint, than HEU - as higher percentages of HEU (40% in the tamper secondary stage at a minimum) can be used for nuclear weapons.

So it comes as less of a surprise that a South China Morning Post (SCMP) article, dated October 6, 2020 https://www.scmp.com/week-asia/politics/article/3104424/south-koreas-request-submarine-nuclear-fuel-us-denied-report reported:

“Citing an unidentified diplomatic source in Washington, [South Korean news site DONG-A ILBO] said South Korea [in September 2020] briefed the US side on its plan to develop [SSBNs] and expressed its wish to be supplied with low-enriched uranium from the US to use as fuel for the subs.” But “its initial request has been turned down by Washington” due to the US-SK Agreement for Peaceful Nuclear Cooperation (aka “123 Agreement”)

Providing context for this South Korean LEU request, SCMP further reported, October 6, 2020:

“As part of its programme to build up its military capabilities over the next five years, South Korea’s defence ministry in August [2020] unveiled a plan to develop three 3,600-4,000-tonne submarines, [what I termed “KSS III Batch III”s in 2019] which would be capable of carrying more ballistic missiles than the existing [KSS III] 3,000-tonne submarines.

The defence ministry is keeping open the possibility that the new subs could be powered by nuclear fuel instead of diesel fuel, although a ministry spokesman said that details “have not yet been fixed as to the propulsion methods of the submarines”

COMMENT

As the US Trump Administration has rejected South Korea’s enriched Uranium request just weeks before the US November 3, 2020 Elections, it is possible South Korea is waiting on whether any incoming Biden Administration might reverse the LEU rejection decision.

LEU and other aspects of a nuclear propelled ballistic missile submarine (SSBN) capability are interlinked. South Korea could only develop a submarine reactor and an SSBN design from scratch with great difficulty. So it is more likely South Korea would seek the elements of an SSBN deterrent system from a combination of countries.

Failing US LEU approval South Korea might:

-  again discuss with Russia, as South Korea did in 2017, a naval reactor design.

-  renew what likely have been discrete talks with France on K15 reactor design and Barracuda variant
   as an SSBN and also French sourced or designed LEU for a K15 reactor. In terms of SLBMs South
   Korea would also be aware France, in the 1960s, helped Israel develop the Jericho ballistic missile
   for nuclear warhead delivery system. This was while France, in the 1950s/60s, was also building
   Israel's Dimona/Negev Reactor Center for nuclear explosives, including the Plutonium
   Reprocessing Plant. 

OR

-  South Korea could enrich its own LEU. In 2000 South Korea laser enrich uranium to 77%.
   Enriching its own Uranium is the only way South Korea can guarantee supply. However to do so
   South Korea would still politically need US permission and need US influence over the IAEA and
   other non-proliferation forums. The US can always remove its armed forces from South Korea, if US
   policies are not heeded.

South Korean risks, policies and technical transitions to develop nuclear tipped SLBMs will be the subject of a future article.