Nagasaki bomb

The Hiroshima bomb contained U, and the Nagasaki bomb contained Pu. These tremendously... 

That is the advantage of fission. Its drawback is the deadly radioactivity it generates, particles whose mass, from one type of reactor, is almost equal to the mass of the fuel consumed. Waste from a fission reactor typically requires thousands of years before it breaks down into biologically safe levels. Fission reactors are also relatively inefficient. They can use but a single isotope (atoms of an element that have the same number of protons but a different number of neutrons) of uranium, U-235, which makes up less than 1 percent of natural uranium ore. (More than 99 percent of natural uranium is nonfissionable U-238.) So-called fast breeder reactors might overcome the supply limitation by breeding fissionable fuel from U-238. But the fuel it produces from the uranium is plutonium, the same stuff that was inside the Nagasaki bomb—not an ideal by-product in a politically unstable world. 

A critical mass of material can also be arranged as a subcritical spherical shell which can be compressed into the supercritical sphere. This process is called implosion and is probably used in most weapons. The bomb over Hiroshima ( 15 kt) used uranium and was of the gun type, while the Nagasaki bomb ( 22 kt) was of the more efficient implosion type using plutonium. 

So I first learned the human dimensions of the Nagasaki bomb from Chief of Police Deguchi. He had been an assistant chief of air raid defense for the prefectural police department when the bomb exploded. 

One of the most vivid descriptions of these forces came from the U.S. Navy commander who targeted and observed the Nagasaki bombing aboard the plane that carried the bomb from Tinian. 

I quickly learned what they wanted to do. Earlier investigations had concluded that the fallout from the Nagasaki bomb fell mostly in the Nishiyama Valley. Mount Kompira, which towers over Nagasaki, had shielded the upper Nishiyama Valley from the direct effect of the bomb s radiation. If there were contamination in that area, it would have come solely from the black rain, the bomb s fallout, not directly from the bomb. This provided an opportunity for a thorough study of fallout. 

The UCLA Medical School was under construction at that time, which meant that there were no laboratories in which to launch the work I was so eager to do. The staff was stiU being recruited and organized. Even so, as soon as I outlined my hope to study fetal brain damage resulting from the Nagasaki bomb, I was promised total support and cooperation. Members of every specialty encouraged me to undertake the work and promised their own cooperation. Today, with different financial pressures and demands on researchers, the informal and cooperative research effort that was constructed at UCLA could hardly be duplicated. 

I did not know at the time that one of the young mothers who brought her children to me in Los Angeles was herself a survivor of the Nagasaki bomb. She was an American of Japanese ancestry who had been trapped there on a visit when the war began, her life made miserable by suspicions that she and her family were American spies. I suppose the bitterness of that experience explains why she did not share the story with me when she first came to my office. She later spoke freely of her feelings and her decision never to return to Nagasaki. 

The report we presented at Oak Ridge covered the thirty pregnant women who had suffered extensive radiation illness after exposure to the Nagasaki bomb. They had been within 2,200 yards of the hypocenter and had somehow survived. 

The apparent absence of lethal consequences from the fallout created by the Hiroshima and Nagasaki bombs was due to the relatively high altitude at which the bombs had been detonated. The explosions did not sweep up in the mushroom cloud vast quantities... 

The Marshall Islands test of a thermonuclear weapon could not have been more different. There was a burst of unprecedented power in that explosion, equal to 15 million tons of tnt, compared with the 22,ooo-ton equivalent in the Nagasaki bomb. And the Marshall Islands bomb detonated nearer the surface, so that large quantities of earth, sand, and water were admixed and fused with the radioactive fission products. 

At last, months late, the clinic was complete and we could begin a new examination of the children of the Nagasaki bomb, checking for the first time for effects of radiation exposure during pregnancy. 

These were the very symptoms we had expected on the basis of what was known about incidental radiation exposure to the fetuses of mothers being treated for cancer. But that did not lessen the impact of seeing this first case among the survivors of the Nagasaki bomb. 

On August 6, 1945, the United States became the first nation to use a nuclear weapon in combat. This bomb used a tubular configuration. Approximately 70,000 inhabitants of Hiroshima, Japan, were killed in the explosion an equal number were seriously injured. A few days later a second bomb, with a spherical configuration, was dropped on the city of Nagasaki. The casualty figures were similar, and World War II came to an end. The Nagasaki bomb was made of plntoninm, an artificial fissionable material produced in atomic piles by breeding reactions. 

Breeder reactions are indnced reactions in which the product nuclei undergo fission reactions. The plutoninm nsed in the Nagasaki bomb was made by bombarding uranium-238 with neutrons in the first atomic pile. Uranium-238 is the most abundant isotope of uranium found in natnre, bnt it will not undergo fission, as will the mnch less... 

A day before the Nagasaki bombing, the Japanese botched a diplomatic overture to end the war They appealed to the Soviets to broker a peace. At the time the Soviets had not entered the war against the Japanese. However, by then Soviet leader Joseph Stalin had learned of the Hiroshima bombing and told the Japanese his country now considered itself at war with Japan. Soviet troops crossed over into China a few hours later and attacked Japanese positions on August 9, the bombing of Nagasaki was carried out. 

The yield of the Hurricane device is given as 25 kilotons (kT), compared with the yield of the Nagasaki bomb, which is given as 20-22 kT, and is typical for implosion type weapons. 

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