.. east and Pacific. Then on December 7, 1941 Japan bombed Pearl Harbor in a surprise attack. That brought the US into war. The first major challage the Manhattan project had was finding what fuel would be good for the atomic bomb. Neils Bohr said isotopes uranium-235 would be good because it was very unstable and can sustain the chain reaction.
Glen Seaborg found out that you cloud also use plutonium-239. It is very hard to get them both. Second challenge was being able to get the uranium and plutonium to go through th fission chain reaction. Third challenge was getting the uranium or plutonium for the atomic bomb. They needed large amounts of that for the atom bomb.
uranium-235 is taken from uranium ore. uranium-235 is 1% and uranium-238 is 99% of the ore. They needed to seperate the uranium-235 and the uranium-238. The first way was called magnetic seperation invented by Ernest O. Lawerence who called it a Cyclotron at University of California, Berkeley laboratories. The uranium was passed through a magnet on 180 degree arc.
The lighter uranium-235 would pass closer to the magnet and get collected, while the uranium-238 would go to the outside and get disposed. There many problems with the magnet. it had dirt particles contaminating the oil and the silver bands on the the track got rusted. The magnets would have to been sent back and be cleaned. This took too long.They spent about 1 million dollars on this and only collected about a gram of uranium-235. The Second way was in 1942, Gen.
Leslie Groves bought land in Oak Ridge, Tennessee to build a uranium seperation failtiy. The process they used turned uranium it to a gas by spraying uranium Hexafluoride on it. The gas floats up and goes through fliters. Most of the uranium-235 is collected and most of the uranium-238 is stopped by the filters. Glen Seaborg discovered how to change uranium-238 into plutonium-239.
In 1942 Enrico Fermi bulit a small nueclear reactor in Chicago and created the first controllable chain reaction in his lab; which would become a prototype for five other reactors. Gen. Groves moved the reactor to Hanford, Washington where the area was isolated and secure. Little Boy Robert Oppenheimer said that a 100kg(220 lb) of uranium-235 was needed because uranium hardly ever comes pure. The center of the bomb is a section that is hollow where they put the uranium in.
A conventional explosions was used to propel the center section into the large section. Both sections would be welded together and begin the chain reaction. This bomb is known as an altimeter bomb which means it has a device that figures out the altitude by measuring the air pressure. This lets the bomb explode before it hits the ground. The land striaght under the bomb is called the hypocenter. Fat Man Richard Feyman and Hans Bethe said 16kg(35.2 lb)of plutonium was needed, but changed to10kg(22lb) if the plutonium was surrounded by uranium-238.
The bomb that was designed was a Beryllium/Polonium mixture of radioactive elements that released neutrons placed in the center of the sphere. The sphere is made up of equal spaced and shaped plutonium sections; it looked like a soccer ball. The bomb worked like this. The sphere imploded making the plutonium to fuse together which reached supercritical mass and starts a chain reaction. The implosion is made by a conventional explosion.
It is also an altimeter bomb. Safety Features Both bombs had lead shields, fuses, and neutron deflectors. The Lead shield protect people and the workings of the bomb from the radioactivity of the uranium and plutonium. Without the lead shield the electronic devices could be shortcircuitted and people poisoned by the radioactivity and die. The fuses were used to prevent the bomb from going off early. The neutron deflector was made up of uranium 238 had two purposes.
In Little Boy the deflector deflected neutrons and in Fat Man it helped the plutonium from losing neutrons and deflected neutrons. There were many questions about the plutonium bomb. Trinity The plutonium bomb was tested. They were very unsure of what would happen. Bainbridge selected a piece of land near Alamogordo, NM. Its the valley between the Rio Grande River and the Sierra Oscura Mountains called Jornada del Muerto. Oppenheimer chose the code name for this test bombing Trinity.
Many events caused the people to wonder if they should go on working with this project. The first event was death of President Roosevelt and President Truman took office and learned of the project. The next event was the surrender of Germany. But they decided to keep working on the project. General Groves approved the test bomb so that President Truman could attend the Potsdam meeting with Stalin and Churchill knowing the results.
No one knew what the nuclear fallout would be on this test bombing. So they tested the fallout with instruments using 100 tons of TNT. They were prepared for almost anything that could go wrong. General Groves worried about the valuable plutonium if the bomb was a dud because plutonium was very valuable and scarce. So the test had to be perfect. Thunderstorms on the night of the test on July 16, 1945 postponed the test until 4 am the next morning. They looked at the bomb from 10,000 yards north of the site.
People wore welder glasses and suntan lotion for protection from the bomb. Over one hundred thousand photos were taken of the explosion. The explosion was much more powerful than they expected. It equaled 20,000 tons of TNT. In a half a mile radius of the explosion was called the vaporation point. Temperatures got up to 3,000-4,000 degrees.
In a one mile radius was the total destruction zone;1.75 mile radius the sever blast zone; 2.5 mile radius the severe damage zone, and the last is a 3 miles radius called severe wind and fire damage area. How this effects our world today Today in our world there are many countries trying to threaten people with these mass destruction bombs. They are smaller, better, and can blow up more area than in 1945. There are many people frightened that some enemy might bomb them. Between 1945 and 1990 , the US was threatened by nuclear bombs from the USSR which resulted in the Cold War. Since the Cold War has ended, we dont need as many bombs.
We burn them to get rid of them and when we burn them they give off harmful gases which can kill people. If we stop making these bombs then we dont have to worry so much about that and we can live in peaceful and a happy world. Bibliography Bibliography Berger, Melvin, Our Atomic World New York,London,Tornton,Sydney Franklin Watts, 1989 Bracchini, Miguel A. “The Manhattan Project” The Manhattan Project April 30, !997 5pg. copyright unknown http:/sage.me.utexas.edu/~uer/manhattan/index.html Encyclopedia Britannaica CD Copyright 1994-1998 Encyclopedia Britannaica inc.