Test No. 6 (China)

The pass that failed

At 7:00 a.m. local time on 17 June 1967, an H-6A bomber lifted off carrying device 639 toward the Lop Nor test site in Xinjiang. The device weighed roughly 6,000 kilograms.

On the scheduled release pass, nothing fell. The navigator later recalled that nervousness and reciting quotations from Mao distracted him and he omitted an automatic-release operation. A ground controller told the crew to fly another pass; Nie Rongzhen, at the test command center, approved it.

3.3 megatons over Lop Nor

On the next pass the aircraft released the parachute-retarded device, which produced a full-yield airburst at about 8:20 a.m. Post-test measurement put the yield at roughly 3.3 megatons — published estimates run 3.0 to 3.3.

The design was multistage fission-fusion-fission: a uranium-235 primary, lithium-6 deuteride fusion fuel, and a natural uranium-238 component. Burst height is reported as 2,930 meters in a recent scholarly reconstruction and 2,960 meters in the Chinese Academy museum account.

A U.S. Joint Atomic Energy Intelligence Committee statement logged the atmospheric explosion near Lop Nor at about 00:19 GMT and called it China's sixth nuclear test.

Whether to call it the first H-bomb

Many Western accounts treat 17 June as China's first hydrogen-bomb test. Some Chinese nuclear specialists instead count device 629, the reduced-yield two-stage device tested on 28 December 1966, because it already embodied the thermonuclear principle, materials and configuration.

What is not disputed is that this was the first full-yield multistage thermonuclear test, completing the program's planned three-test sequence. Xinhua announced the success the same day, and the communiqué ran on the People's Daily front page the following morning.