French Nuclear Test "Canopus"





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Uploaded on May 18, 2008

A few clips of France's first thermonuclear weapon test, "Canopus".

Fangataufa was chosen as the site for France's first true hydrogen bomb test, code named Canopus. The three ton device was based on a design developed by Luc Dagens. It was purely experimental and not thought to have been a design based on an actual warhead. It used a lithium-6 deuteride secondary with a highly enriched uranium jacket.

The design of the Canopus device was predicted to have a high fission yield. As a result, it was decided to detonate it at Fangataufa to prevent contamination of the main base at Mururoa. The device was transported to Fangataufa where it was attached and suspended underneath a large, helium filled balloon. The balloon was raised to an altitude of 520 meters (1,664 feet) for the test to reduce radioactive fallout.

Several of the surrounding populated atolls were evacuated for the shot, others had crude fallout shelters constructed on them for the shots; an extensive weather monitoring system was put in place. Mururoa and Fangataufa were both evacuated for the test.

Canopus was detonated on 24 August 1968 with a yield of 2.6 megatons. This was France's highest yielding test, more than twice as powerful as France's second highest yielding shot. The fireball swelled and engulfed the lagoon below; the shock wave obliterated everything on Fangataufa, including knocking down the large radio tower on the northern end of the atoll. Heavy cloud cover over Fangataufa at shot time obstructed much of the photography of the test.

The following is a worker's account of Canopus: "In 1968 I worked on Fangataufa preparing for the first French hydrogen bomb. When we first arrived Fangataufa was a lovely place, quiet and undisturbed, with a lot of vegetation. After the explosion nothing was left. No houses, no man-made installations, no trees, nothing. The whole place had to be evacuated because of the radioactive contamination."

The top of the mushroom cloud reached an altitude of 76,800 feet, while the base reached an altitude of 47,360 feet. The cloud drifted to the north-east and fallout was detected on the atolls of Pukarua, Tureia, and Reao.

As expected, the shot was particularly dirty. Fangataufa was heavily contaminated after the shot. For six years parts of the atoll were too dangerous for prolonged exposure. Despite this, another two shots were conducted on Fangataufa; Dragon on 30 May 1970 and Orion on 2 August 1970. Work on the atoll had to be done in air conditioned buildings and only for short durations of time. Boats were used to transport workers and supplies through some of the most heavily contaminated parts of the atoll.

France became the world's fifth thermonuclear power with the successful Canopus test. France's first two-stage thermonuclear weapon, the TN-60 would enter the stockpile in 1977. These warheads were deployed on the Redoutable class ballistic missile submarines as well as on the land based SSBS S3 missiles. The TN-60 was a highly sophisticated warhead that required an extensive development and testing program. It had a nominal yield of 1 megaton.


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