Project 596

Project 596 (Miss Qiu, Chinese: 邱小姐; pinyin: Qiū Xiǎojiě, as the callsign; Chic-1 by the US intelligence agencies) was the first nuclear weapons test conducted by the People's Republic of China, detonated on 16 October 1964, at the Lop Nur test site. It was an implosion fission device containing about 15 kg weapons-grade uranium (U-235) from Lanzhou enrichment plant.

The atomic bomb was a part of China's "Two Bombs, One Satellite" program. It had a yield of 22 kilotons, comparable to the Soviet Union's first nuclear bomb RDS-1 in 1949 and the American Fat Man bomb dropped on Nagasaki, Japan in 1945. With the test, China became the fifth nuclear power in the world. This was the first of 45 successful nuclear tests China conducted between 1964 and 1996, all of which occurred at the Lop Nur test site.

The Chinese nuclear weapons program was initiated on 15 January 1955. The decision made by the Chinese leadership was prompted by confrontations with the United States in the 1950s, including the Korean War, the 1955 Taiwan Straits Crisis, nuclear blackmail, and eventually the Vietnam War as well. Mao Zedong explained his decision to a gathering of the Politburo of the Chinese Communist Party in 1956:

"Now we're already stronger than we were in the past, and in the future we'll be even stronger than now. Not only are we going to have more airplanes and artillery, but also the atomic bomb. In today's world, if we don't want to be bullied, we have to have this thing."

In 1956, the Third Ministry of Machinery Building was established, and nuclear research was conducted at the Institute of Physics and Atomic Energy in Beijing. A gaseous diffusion uranium enrichment plant was constructed in Lanzhou. In 1957, China and the USSR signed an agreement on sharing defense technology that involved a prototype boosted fission weapon being supplied by Moscow to Beijing, technical data, and an exchange of hundreds of Russian and Chinese scientists. A joint search for uranium in China was conducted between the two countries. A location near Lake Lop Nur in Xinjiang was selected to be the test site with its headquarters at Malan. Construction of the test site began on 1 April 1960, involving tens of thousands of laborers and prisoners under tough conditions. It took four years to complete. Being the sole site for nuclear testing in China for years to come, the Lop Nur test site underwent extensive expansion and is by far the world's largest nuclear weapons test site, covering around 100,000 square kilometers.

Sino-Soviet relations cooled during 1958 to 1959. The Soviet Union was also engaged in test ban negotiations with the United States in 1959 in order to relax Soviet-American tensions, directly inhibiting the delivery of a prototype to China. Broader disagreements between Soviet and Chinese communist ideologies escalated mutual criticism. The Soviets responded by withdrawing the delivery of a prototype bomb and over 1,400 Russian advisers and technicians involved in 200 scientific projects in China meant to foster cooperation between the two countries.

Project 596 was named after the month of June 1959 in which it was initiated as an independent nuclear project, immediately after Nikita Khrushchev decided to stop helping the Chinese with their nuclear program on 20 June 1959, and Mao shifted toward an overall policy of self-reliance. The Second Ministry of Machine Building Industry, which oversaw China's nuclear industry, continued with the development of an atomic bomb. The project was facilitated by the 119, China's first self-developed large-scale digital computer, which the China Academy of Sciences had also debuted in 1964. By 14 January 1964, enough fissionable U-235 had been successfully enriched from the Lanzhou plant. There are wild unscientific speculation that it used uranium deuteride as a neutron initiator. The fissile pit, in two hemispheres composed entirely of highly enriched uranium, weighed about 15 kilograms, corresponding to a diameter of 11.4 cm, roughly the same as a soccer ball.^{[citation needed]} On 16 October 1964, a uranium-235 fission implosion device, weighing 1550 kilograms was detonated on a 102-meter tower.

On the day, Premier Zhou Enlai published a statement by the Chinese government, announcing the test, and stating its purpose to "oppose the U.S. imperialist policy of nuclear blackmail". Specifically, China criticized the 1963 Partial Nuclear Test Ban Treaty, promulgated by the "nuclear monopoly" of the US, USSR, and UK, which aimed to ban all non-underground nuclear testing, including atmospheric tests such as 596. China also criticized the NATO Multilateral Force proposal in Europe, and "U.S. submarines carrying Polaris missiles with nuclear warheads ... prowling the Taiwan Straits, the Tonkin Gulf, the Mediterranean Sea, the Pacific Ocean, the Indian Ocean and the Atlantic Ocean".