June 21, 2016

Japan Probably Has Nuclear Submarine and Weapons Know-How

1st Ship reactor (built or went critical)
United States
1952 Ivy Mike
1954 USS Nautilus 
1961 USS Enterprise
1962 Savannah

1953 Joe 4
1957 November class

1959 Lenin
1956-58 Grapple
1960 HMS Dreadnought 

1968 Canopus

1967 Test No. 6
1970 Type 091 (401)

1968 Shakti I

2009 INS Arihant

1968 Canopus (shared test assumed)

None. Dolphin SSKs used.


1968 Otto Hahn


1972 Mutsu

In the table above there is a pattern. Nuclear weapons powers achieved thermonuclear (H-Bomb) tests first, then they develop a submarine reactor. This is with the exception of Israel which is too small to build nuclear subs. 

This may reveal the higher priority given to nuclear weapons. Also it is of little use launching an SSBN if it has no compact thermonuclear warheads to place on ballistic missiles.

The ability of Germany and Japan to develop ship reactors may indicate they have sufficient nuclear know-how to develop submarine reactors and thermonuclear weapons. 

Brazil has not yet launched a submarine reactor but is considered capable of building nuclear weapons fairly quickly. 

Various types of information sharing has been known to happen between the 5 official nuclear powers.


On June 13, 2016 (4:08 PM) S provided Comments along the lines:

The Japanese Atomic Energy Agency (JAEA) has published reports on propulsion reactors but has not built any since the Mutsu nuclear propelled cargo ship in the 1970s. Japan is not currently planning development of a nuclear submarine.

Plans exist for a nuclear reactor known as "DRX" for a deep submergence vehicle . See the proposed DRXs reactor line drawing

Japan Atomic Energy Research Institute (JAERIreactor known as "MRX" that was intended to be 3 times more powerful than the Mutsu's reactor. MRX was being researched, from the 1990s for use in a far larger ship. 

[Pete tracked down http://www.iaea.org/inis/collection/NCLCollectionStore/_Public/31/058/31058473.pdf published in  2000. It was envisaged:

"The basic concept of an innovative advanced marine reactor MRX has been established by design study toward the goals of light-weightiness, compactness, and safety and reliability improvement with adoption of several new technologies. The MRX is the integral-type PWR aimed for use of ship propulsion. Adoption of a water-filled containment makes the reactor light-weighted and compact greatly. The total weight and volume of the reactor are 1600 tons and 1210 m3, which are equivalent to halves of the Mutsu, although the reactor power of MRX is three times greater."

With power output of MRX calculated as 30 MW - 100 MW, 100 MW may be well suited for a small SSN.]

Also see JAERI 1997 document (mainly Japanese language) on MRX 

See JAEA's Business Plan activities (extending from 2005 to 2021). Basically no research on ship reactors was conducted by JAEA at all. Japan is not currently planning development of a nuclear submarine.

Factors that may cause Japan to research (or perhaps re-research) submarine reactors may be greater strategic threats from China, Russia and North Korea. Also competition with South Korea and US isolationism may encourage more Japanese research.

Set against Japanese submarine reactor development:

-  Japan's strategic threats are close (just across the Sea of Japan) making the marginal utility low for
   fast moving, long range, Japanese nuclear propelled submarines.  
-  Japan may place a higher priority on developing the necessary dual (civilian-military) use precursor
   technology for nuclear weapons. 

Russia already has highly developed submarine reactors but China apparently has not built fully satisfactory, efficient and quiet submarine reactors. North Korea probably cannot afford submarine reactors but North Korea is continually surprising.

While South Korea is not a strategic threat to Japan there is rivalry. South Korea studied (probably still studying) the possibility of submarine reactors under various names like KSS-N or KSS-III (nuclear) for decades.  

If South Korea makes any progress in a "Nuclear Propulsion Ship" (see DSME "New Technology List") then this would catch Japan's attention. South Korea's - Korea Atomic Energy Research Institute (KAERI) might modify its licensed 100 MW "SMART" small PWR reactor which has the right power output, at least, for a nuclear sub.

Possible declining support from the US, in the shape of future Trump Presidency strategic isolationism, may encourage Japan to look at nuclear options, including submarine propulsion and nuclear weapons.

Pete and S


Anonymous said...

Japan has quite a bit of expertise in the micro size nuclear reactor like the Toshiba 4S, a 10MW sodium cooled breeder design with a 30 year core life.

Anonymous said...

The Toshiba 4S was the reactor that the Japanese tried to give away to Galena Alaska. The one where Galena said:'Thanks - but no thanks!'
It doesn't have NRC registration and can't be used in the US. There are a lot of small/micro reactors designs like this, in various stages, from paper reactors to prototypes. There just has not been an economic case where they 'work'. Manufacturers/ designers of them assure us that each one is extremely safe but are not prepared to get NRC approval.
To me, that is like assuring everyone the car you made and want to sell is safe - but not wanting a crash test to be done.

Anonymous said...

I am only saying that Japan has invested in R&D of small modular reactors (along with other countries) for at least 1/4 century and those could have applications in naval reactor if they want to go down that route for both commercial and military naval applications. In fact, Russia's SMR MVBR is an improved design based on the Alfa submarine reactor. If the Paris treaty takes effect, nuclear power could play a bigger role in naval applications.
SMR, including light water reactor designs or liquid metal design like the 4S, so far have not fully demonstrated their economic advantages. None has gone into full scale production to be able to show that there are economies of scale to be gained. The economics may not prove out if regulatory approval is the same as for GW reactors or if the build out costs are the same as larger reactors.
In the case of Galena, the NRC fees of ~$100M means that project is DOA. After all there are only 500 souls in Galena to be served. The NRC and others are also concerned with the use of sodium as coolant and had proposed the use of lead. In any case, since TMI and now Fukushima, nuclear reactors are essentially dead in the US but this may not be the case outside of the US.

Peter Coates said...

A highly specialised discussion above. See https://en.wikipedia.org/wiki/Toshiba_4S and https://en.wikipedia.org/wiki/Galena_Nuclear_Power_Plant

Why use proven PWR submarine reactors?

Certainly if Japan wanted to go the high risk, thoroughly discredited, liquid metal reactor for submarine route then Japan could make it hard for itself.

Who can forget the trials and risks:

- the US took with the https://en.wikipedia.org/wiki/S2G_reactor :
" The leaks in the Seawolf steam plant were an important factor in the decision but even more persuasive were the inherent limitations in sodium-cooled systems. In Rickover's words they were "expensive to build, complex to operate, susceptible to prolong shutdown as a result of even minor malfunctions, and difficult and time-consuming to repair."

- choice of liquid metal reactos wrecked Russia's Alpha sub program https://en.wikipedia.org/wiki/Alfa-class_submarine#Propulsion

"The OK-550 plant was used on [the Alpha/Lira sub project] the BM-40A plant was installed due to the low reliability of the OK-550. While more reliable, BM-40A still turned out to be much more demanding in maintenance than older pressurized water reactors. The issue was that the lead/bismuth eutectic solution solidifies at 125 °C (257 °F). If it ever hardened, it would be impossible to restart the reactor, since the fuel assemblies would be frozen in the solidified coolant. Thus, whenever the reactor is shut down, the liquid coolant must be heated externally with superheated steam. Near the piers where the submarines were moored, a special facility was constructed to deliver superheated steam to the vessels' reactors when the reactors were shut down. A smaller ship was also stationed at the pier to deliver steam from her steam plant to the Lira submarines.

[the liquid metal solidifying] led to a number of failures, including coolant leaks and one reactor broken down and frozen while at sea. However, constantly running the reactors proved better than relying on the coastal facilities. Four vessels were decommissioned due to freezing of the coolant."

If Japan wanted to have a submarine reactor Fukushima it should definitely go liquid metal.



MHalblaub said...

I also think Japan could send a man to Moon just like they can build an SSN. In both cases wasted money.

Japan can build more conventional submarines than nuclear propelled once. Number is a quality of its own. The advantage is to small for Japanese usage.

Nuclear propulsion would far better suit to the current Australian strategy but I doubt the worth.

Australia does not need a superior submarine. Australia needs a supirior submarine fleet.


Peter Coates said...

Hi MHalblaub

Yes, as I wrote, the countries that threaten Japan are so close that a Japanese SSN would have little extra value.

Japan, like South Korea, would be better off with VLS tubes on an SSK. Such tubes could take ballistic missiles for 1st or 2nd strike particularly against, near insane, North Korea.

So Japan needs to leave its 1% of GDP Defence Budget luxury and start putting the building blocks in place to defend itself from genuine nuclear threats. The BMDs Japan is building don't provide deterrence.

On Australia I humbly recommend:

6 x SSKs completed in 2030s, then

4 x SSNs in 2040s



Peter Coates said...

Please note my comment above of 22/6/16 5:02 PM

"- choice of liquid metal reactos wrecked Russia's Alpha sub program https://en.wikipedia.org/wiki/Alfa-class_submarine#Propulsion

...[the liquid metal solidifying] led to a number of failures, including coolant leaks and one reactor broken down and frozen while at sea. However, constantly running the reactors proved better than relying on the coastal facilities. Four vessels were decommissioned due to freezing of the coolant."...

In date sequence and concurrence is the National Interest article 2 days later, of 24 June 2016, of http://nationalinterest.org/feature/alfa-russias-cold-war-submarine-wonder-weapon-nato-feared-16718
which is specifically about the Russian Alpha/Lyra submarine program particularly on their high maintainance liquid metal reactors.

Draw your own Submarine Matters on the avant-garde conclusions :)


Anonymous said...

The Silent Service: During the Cold War, the Japan Maritime Self-Defense Force jointly developed a nuclear submarine with the United States Navy. On its maiden voyage, the captain of the submarine declares the submarine to be an independent state, "Yamato"(US code name “Seabat”). The American navy pursues "Yamato", repeatedly failing to capture or destroy the rogue submarine.


Peter Coates said...

Thanks Anonymous [at 6/11/16 1:21 PM]

The sources you provide are intriguing:

[1] https://en.wikipedia.org/wiki/The_Silent_Service and

[2] https://www.youtube.com/watch?v=44IHttCz72A

A sound basis for a Japanese nuclear sub program, of course!?

Anonymous said...




Peter Coates said...

Thanks Anonymous

For your 8/11/16 7:14 PM post (above)

We at Submarine Matters Intel Agency re studying 沈黙の艦隊 "The Silent Service VOYAGE1" series with profound interest.

A nuclear armed Japan may be the root to world peace as Trump (thinks) he knows it.

Yours in Stalin-esque Good Humour


Anonymous said...


Peter Coates said...

Thanks Anonymous [at 8/11/16 10:07 PM]

The English dubbed Youtube ( https://www.youtube.com/watch?v=euV4ki99yvk ) that you provide of "Chinmoku no Kantai "The Silent [Submarine] Service" is so much better than English subtitles.