http://rense.com/general5/blast.htm
There was a similar blast in 1944 in the SF Bay Area, near Richmond at Port Chicago. It was equivalent to a small nuclear blast, obliterating everything in the area including much of the nearby town. 320 sailors on two ships at dock were killed, with only 50 sailors remains identified; the rest was obliterated. The blast was attributed to careless handling of munitions. However, some (as in this link) think it may have actually been a nuclear blast. Article goes on to say the U.S. military had 74kg of U-235 as of late 1943, enough for 5 bombs. 15.5kg was required for the Hiroshima bomb. Specs for the bomb were completed in early 1944 and three bombs were ordered made in March 1944. This info was declassified recently. Whether a Hiroshima type bomb was being transported by ship from Port Chicago is anyones guess, even more unlikely that one detonated. Anyway, the Port Chicago blast was horrific!
1. The first test of an atomic bomb was almost exactly a year after the Port Chicago explosion. Of course that was the more complex implosion type bomb. But if they had had any type of atomic weapons ready a year earlier, don't you think they would have been used to end the war?
2. From your link: "According to the US Department of Energy Oak Ridge records, 74 kilograms of U-235 was available by December 1943, 93 kg by December 1944 and 289 kg by December 1945."
I see two problems with this: 1. If they already had 74 kg by the end of 1943, it does not make sense that they only produced another 19 kg in the following year. 2. According to Wikipedia, there were only 50 kg available by July 1945 and it was all used in the Hiroshima bomb.
Where did the Indianapolis pick up the bombs it delivered?
Sounds like a nuclear detonation to me.