A container to hold an atomic bomb … sort of

19 Aug

An oddity from the Trinity tests – a steel cylinder strong enough to survive the TNT explosive of an atomic bomb.

A note about it from August 1961 Popular Science:

Jumbo, the atomic white elephant. If the Chamber of Commerce of Socorro, N.M. (pop. 5,271), gets its way, the tourist park near the junction of U.S. 85 and 60 will have an imposing monument, a rarity among memorials because it commemorates a mistake. And the U.S. Government will finally be rid of Jumbo, 214 tons of mistake. Jumbo is a steel tank, one of the heftiest ever built. It looks like the vacuum insert for a Thermos bottle – only it is 25 feet long, 12 feet in diameter, and has walls 15 inches thick. Its story is a sadly funny tale, one of the oddest of the many odd footnotes to the early history of the atomic age.

In 1944 the scientists at the secret laboratory in Los Alamos were designing the first atom bomb, code-named Fat Man. They were pessimistic. They thought they might eventually make The Gadget work, but they didn’t think there was much chance it would work on the first try. The worst part was that they couldn’t afford to lose Fat Man’s priceless plutonium; if the plutonium failed to react, it would be scattered all over the New Mexic desert by the force of the TNT detonater (several thousand pounds). No one doubted that the TNT would go. So they decided to set off Fat Man inside a bottle. Jumbo was to be the bottle. It wasn’t meant to contain an atomic blast – if Fat Man went, jumbo would go too, and no tears shed. But jumbo was strong enough to contain the TNT blast alone. If Fat Man’s plutonium failed to react, it could be scraped off the inside of the tank and used for another try.

Jumbo arrived at The Site two months before the mushroom cloud that was to alter the course of history. It rode majestically on a special trailer-eight rows of eight wheels each, all independently sprung-pulled by four tractors. But by then the scientists didn’t want it. They were fairly confident that Fat Man would work. Jumbo was left hanging empty from its steel scaffold 800 yards from Ground Zero. The world’s first atomic blast crumpled the scaffold but didn’t hurt jumbo. It proved its strength again when a bungled attempt to destroy it with eight 500-pound demo bombs did nothing but blow the ends off. So jumbo was rolled into a trench. In 1951 it was dug up only to be abandoned once again – it had been suggested for use in an experiment but proved unsuitable. For nine years jumbo lay unwanted in the desert. Then last summer the Socorro businessmen asked for it – and nobody could find it. Finally jumbo was uncovered just outside the fence that encircles Ground Zero. Now it is Socorro’s problem.

There’s a comment about it in Wikipedia’s article on the tests:

General Groves had ordered the construction of a 214-ton steel canister code-named “Jumbo” to recover valuable plutonium if the five tons of conventional explosives failed to compress it into a chain reaction. The container was constructed at great expense in Pittsburgh, Pennsylvania, and brought to the test site by rail, but by the time it arrived, the confidence of the scientists was high enough that they decided not to use it. Instead, it was hoisted up in a steel tower 800 yards (730 m) from the gadget as a rough measure of how powerful the explosion would be. In the end, Jumbo survived, though its tower did not.

And some pictures and comments at AtomicArchive.com:

Because of this possibility, Jumbo was designed and built. Originally it was 25 feet long, 10 feet in diameter and weighed 214 tons. Scientists were planning to put the bomb in this huge steel jug because it could contain the TNT explosion if the chain reaction failed to materialize. This would prevent the plutonium from being lost. If the explosion occurred as planned, Jumbo would be vaporized. Jumbo was brought to Pope, N.M., by rail and unloaded. A specially built trailer with 64 wheels was used to move Jumbo the 25 miles to Trinity Site.


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