How Risky Is It for Japan to Build a Nuclear Submarine?
Since the United States approved South Korea to build a nuclear submarine, Japan has also been unable to resist its desire for a nuclear submarine. The Japan Times reported on the 10th that Japanese government officials have begun discussing the issue of having a nuclear submarine, "These advanced submarines can secretly conduct long-term military operations, which will help strengthen deterrence against China." However, even Japanese media generally believe that Japan faces many challenges and risks in obtaining a nuclear submarine.
The report said that in the joint government agreement between the Liberal Democratic Party (LDP) and the Restoration Party in October, it included promoting the development of submarines powered by "next-generation energy" equipped with long-range missile vertical launch systems. The Asahi Shimbun stated that in a report issued in September this year, an expert group under the Ministry of Defense responsible for enhancing Japan's defense capabilities recommended that the Japan Maritime Self-Defense Force should study new submarines powered by nuclear reactors and equipped with vertical launch systems, which essentially refers to nuclear submarines. "This marks the first time that an official government advisory body in Japan has publicly supported this idea." At a press conference on October 22, when asked about the possibility of Japan equipping itself with nuclear submarines, Japanese Defense Minister Koizumi Shinjiro said, "We are not excluding any options."
At the end of October, President Trump of the United States announced that he had approved South Korea to build a nuclear submarine, which greatly stimulated the Japanese government. The Asahi Shimbun reported that currently, not only does China already have multiple nuclear submarines, but South Korea has also "received U.S. approval" to build a nuclear submarine. Recently, Koizumi Shinjiro publicly stated on television, "The environment around Japan is so severe that we must discuss whether future submarines should use conventional diesel-electric power or nuclear power." The report believes that Koizumi's latest statement indicates that South Korea's approval to build a nuclear submarine has "fueled the debate" over Japan introducing a nuclear submarine.
According to the introduction, a nuclear submarine usually refers to a large submarine powered by a nuclear reactor, mainly including attack nuclear submarines equipped with conventional weapons and strategic nuclear submarines carrying submarine-launched ballistic missiles. Even attack nuclear submarines that do not carry nuclear weapons have significant operational advantages compared to traditional diesel-electric submarines, including significantly extended underwater deployment time and higher underwater speed, which enhance the submarine's mobility.
The Japan Times introduced that the Japan Maritime Self-Defense Force currently has 22 conventional-powered submarines, which need to surface regularly to take in air to drive diesel engines to charge batteries. In contrast, nuclear submarines can remain submerged for extended periods. On the other hand, Japan is considering equipping the next generation of submarines with missile vertical launch systems, which require additional space inside the submarine, so they can only be installed on submarines with sufficient tonnage and good maneuverability. Underwater speed is important for avoiding enemy counterattacks because the submarine's location may be discovered after launching missiles, requiring quick maneuvering to escape tracking. At the same time, larger tonnage means the submarine experiences greater underwater resistance, so it also requires stronger propulsion, which are all reasons for Japan to consider equipping the next generation of submarines with nuclear power.
Previously, the American "Business Insider" website analyzed that Japan's current submarines, although using conventional power, already have some characteristics of nuclear submarines. The waterline displacement of the "Soryu" and "Tachibana" class submarines in service with the Japan Maritime Self-Defense Force exceeds 4,000 tons, far exceeding conventional submarines of other countries, even comparable to the tonnage of the French "Rubis" class attack nuclear submarines. This means that Japan has the capability to build submarines of nuclear submarine level. Additionally, the later models of the "Soryu" class and the "Tachibana" class use large-capacity lithium batteries, whose energy density and output power far exceed traditional lead-acid batteries, allowing submarines to reach high speeds similar to those of nuclear submarines in a short time and significantly reducing the need to surface, thus improving safety. Furthermore, Japan's technical accumulation in advanced pressure hull steel, quiet technology, and sonar systems provides a foundation for building nuclear submarines.
The biggest technical obstacle for Japan in building submarines lies in the nuclear reactors used in submarines. According to the report, Japan built the "Ryo-O" nuclear-powered cargo ship in the 1970s, which used civilian nuclear reactor technology, but it was sealed due to a nuclear leakage accident shortly after commissioning, and it wasn't until the early 1990s that it was restarted and completed its first global trial voyage. Afterward, Japan dismantled the nuclear reactor of the ship. This incident also proved that Japan's technical experience in naval nuclear reactors is weak. Moreover, military nuclear reactors used in submarines require much higher overall compactness and safety standards than land-based nuclear power plants or nuclear-powered surface ships. Furthermore, the nuclear reactor, steam turbine, and transmission system must be integrated into the narrow hull of the submarine, and issues such as heat dissipation, radiation shielding, and noise control must be addressed. For this, it is necessary to build land-based prototype reactors for long-term testing, and Japan has not publicly conducted such projects. Therefore, Japan currently faces many technical challenges in developing nuclear submarines.
In addition to technical issues regarding nuclear reactors, the Japan Times also mentioned that Japan faces extensive challenges in terms of construction and maintenance costs and legal aspects if it wants to equip itself with nuclear submarines. The report stated that according to the requirements of "cyclic readiness, maintenance, and training," at least three nuclear submarines are needed to ensure that "one nuclear submarine can always be deployed." However, the construction and maintenance costs of three nuclear submarines are enormous. In addition to the high R&D costs of nuclear submarines themselves, the Japan Maritime Self-Defense Force also needs to build dedicated supporting nuclear facilities for daily maintenance and handling potential radiation leaks. "Therefore, introducing nuclear submarines would require a comprehensive restructuring of the Japan Maritime Self-Defense Force, which is currently struggling with a serious shortage of personnel."
Additionally, the Japanese government also needs to revise relevant laws and regulations. Current Japanese laws stipulate that nuclear energy can only be used for peaceful purposes. Convincing local residents near the nuclear submarine base would also cost extra.
Therefore, a defense ministry official said, "For a long time, introducing nuclear submarines has been a taboo topic for the Self-Defense Forces, and there has been no appropriate discussion," "It depends on whether Japanese politicians are ready to make a decision." Another defense ministry official said, "If it is just for monitoring and deterring neighboring countries, being able to protect the surrounding areas of Japan is sufficient, so I want to know whether it is really necessary to equip with nuclear submarines." (Special Correspondent Chen Shan, Global Times)
Original: www.toutiao.com/article/1848567684265100/
Statement: This article represents the views of the author.