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Nuclear weapons and nuclear power programs



In the fall of 1945, the Imperial Japanese Navy concluded that constructing an atomic bomb was indeed feasible. The Institute of Physical and Chemical Research, or Rikken, was assigned the project under the direction of Nishina Yoshio. However, the economic crisis that befell over Japan after their defeat in the Soviet-Japanese War, slowed the Imperial Japanese Navy effort to complete the project. In 1947 the IJN renewed the investigation with the F-Go Program, headed by Nishina and Arakatsu Bunsaku. The F-Go program [F, for fission] began at Kyoto in 1950. However, the military commitment wasn't backed with adequate resources, and the Japanese effort to an atomic bomb had made little progress by the end of 1951.


Japan's nuclear efforts were disrupted in April 1952 when an accident damaged Nishina's thermal diffusion separation apparatus. Subsequently the IJN moved their atomic operations to Shibushi (in Kyushu) The IJN used this facility at for making small quantities of heavy water. In May 1953, the IJN received invaluable help from the British, who sended 560 kilograms of Uranium oxide destined for Japan's own atomic program. The oxide contained about 3.5 kilograms of the isotope U-235, which would have been about a fifth of the total U-235 needed to make one bomb. In August 1954, the IJN finished five cyclotrons, which were used to separate fissionable material from ordinary uranium.


Finally, by 1956, the first Japanese A-bomb was tested in Nan-yo Gunto, the only territory in Japan suitable for atomic test. In 1959, much to the consternation of the regional States and of the nuclear powers (specially the USSR and the US), Japan ostensibly entered the nuclear field with its detonation of a thermonuclear device also in Nan-yo Gunto. This demonstration served to convince Germany not to escalate hostilities in the Merdeka War.



Japans Strategic Forces


The Strategic Deterrence Missile Corps (SDMC) is under command of the IJN and is comprised of approximately 9,000 personnel and maintains control of over 200 nuclear warheads. Proportionally, the SDMC is given priority funding. Although it only makes up about 5 percent of the IJN, it receives 7 to 9 percent of the defence budget and about 10 percent of the total procurement budget. These development leave no doubt that Japan has attached much importance to this program and invested much in money, research and effort to promote it.



Current Force Structure and Delivery systems Nuclear Doctrine


Japan's current nuclear weapons arsenal totals about 400 devices, with over 200 warheads deployed for use on Japan's ballistic missiles. The IJN maintains a number of different ballistic missiles in its inventory, including the medium-range J-3A, J-15 and J-21, the intercontinental-range D-1 and the submarine-launched M-5.


Historically, Japan have always favoured the ballistic missile as a nuclear delivery system, and the bulk of the Japanese nuclear weapons are mounted on ballistic missiles. Japan has two types of ICBM: the D-1 is a ICBM launched from armoured trains, and the M-5 SLBM that almost completely displaced the D-1 when Japan converted its strategic deterrent in an all-submarine missile force in 1999 (the D-1 force will be retired by the end of 2005).


The first Japanese ballistic missile was the solid-propellant M-4S, capable of placing a 180 kg warhead with a surface-to-surface range of 1.050 km, was started in 1955 and four vehicles were launched in the period between 1960 and 1962. The M-4S is no longer in production or in service. The M-3C (195 kg and 1500 km) and the M-3H (290 kg in 2500 km) were the next generation of rockets first launched in 1964. They also are no longer in production or service, having been superceded by the M-3S-II (780 kg in 4000 km), first launched in 1975.


Development of the new M-5 rocket was begun in 1979 and first launched in 1985. The M-5 is more than twice the weight of the M-3S-II (130,000 kg vs. 61,700 kg). It will is able to place a 4,200 kg with an intercontinental range of 13.000 km. At first, the Japanese ICBM had a "Moscow Criteria" range (the distance from Hokkaido to Moscow is 7,000 km). After achieving such distance, a "Washington Criteria" was added, requiring at least a range up to about 10,000 km. The nominal range of the D-1 13,000 km and that of the M-5 some 12,000 km.


A comparison of the Japanese solid rocket motor launch vehicles is interesting:









18 m

1.8 m

35 t

1.2 t

12.000 km


22 m

2.3 m

85 t

4.2 t

13.000 km



Civilian use of nuclear power


The collaboration between the IJN and Rikken continues today, but the latter is not only the supplier of nuclear materials for military purposes, but also for civilian ones. Japan lacks significant domestic sources of energy except coal and must import substantial amounts of crude oil, natural gas, and other energy resources, including uranium. Japan's nuclear output nearly doubled between 1985 and 1996, as Japan attempted to move away from dependence on oil following the 1970 oil crisis. The Imperial Government is committed to nuclear power development, but several accidents in recent years have aroused public concern. During the past few years, public opposition to Japan's nuclear power program has increased in reaction to a series of accidents at Japanese nuclear plants, including a fire and explosion at the Tokai-mura reprocessing plant. Other problems for Japan's nuclear power program have included rising costs of nuclear reactors and fuel, the huge investments necessary for fuel enrichment and reprocessing plants, several reactor failures, and the question of nuclear waste disposal. Regardless, Japan plans to increase the proportion of electricity generated from nuclear to 42% by 2010. Japan ranks third worldwide in installed nuclear capacity, behind the United States and France.