Seeing the work that they were not even able to understand produce the Hiroshima and Nagasaki bombs amazed the workers of the Manhattan Project as much as the rest of the world. Although the existence of the bombs was now public, secrecy continued, and many workers remained ignorant of their jobs; one would later state, "I don't know what the hell I'm doing besides looking into a ——— and turning a ——— alongside a ———. I don't know anything about it, and there's nothing to say". Many residents continued to avoid discussion of "the stuff" in ordinary conversation despite it being the reason for their town's existence.
Groves commissioned Henry DeWolf Smyth to write a history for public consumption before the bombings. On the 12th of August, 1945, the public received a copy of Atomic Energy for Military Purposes, also known as the "Smyth Report." Key contractors, whose participation had previously been kept secret, received Army-Navy "E" Awards from Groves and Nichols. Key scientists and contractors, including Bush and Oppenheimer, received more than 20 awards of the Presidential Medal for Merit.
At Hanford, Reactors B, D, and F were damaged by fission products and the Wigner Effect (the displacement of atoms in a solid caused by neutron radiation), which caused the graphite moderator to swell, and as a result, plutonium output decreased. The charge tubes, which were used to irradiate uranium to create plutonium, were rendered useless due to swelling. Production was reduced and the oldest unit, B pile, was shut down so that there would always be at least one reactor available to supply the urchin initiators with polonium. As research went on, DuPont and the Metallurgical Laboratory created a redox solvent extraction method as an alternative to the bismuth phosphate procedure, which left leftover uranium in a condition that made it difficult to recover.
The Los Alamos-based Z Division, which was led by Dr. Jerrold R. Zacharias, was in charge of bomb engineering. Z Division was based at Wendover Field at first, however in September of 1945 it was transferred to Oxnard Field in New Mexico to be closer to Los Alamos. This served as Sandia Base's launching event. A B-29 base was utilized nearby Kirtland Field for drop tests and aircraft compatibility. By October, all of the personnel and resources from Wendover had been successfully moved to Sandia. As reservist officers were demobilized, around fifty well chosen regular officers took their place.
Nichols would suggest to shut down S-50 and the Alpha rails at Y-12 by September. Even though the Alpha tracks were operating better than ever, they were unable to compete with K-25 and the brand-new K-27, which had started up in January of 1946. The Tennessee Eastman payroll was reduced from 8,600 to 1,500 as a result of the closure of the Y-12 plant in December, saving the company more than $2 million each month.
Demobilization was a concern everywhere, but nowhere more so than at Los Alamos, where there was a talent exodus. There was still a lot to do. It would take work to make the bombs that were used on Hiroshima and Nagasaki simpler, safer, and more dependable. The wasteful cannon method for uranium needed to be replaced with efficient implosion techniques, and composite uranium-plutonium cores were required now that plutonium was scarce due to issues with the reactors. However, it was challenging to persuade scientists to stay given the lab's uncertain future. Oppenheimer went back to work at the University of California, and Groves put Norris Bradbury as a temporary stand-in. Bradbury would hold the position for the following 25 years. Groves launched a construction program that included a better water supply, 300 homes, and recreational facilities in an effort to address the unhappiness brought on by the lack of amenities.
As a part of Operation Crossroads, which sought to learn more about the impact of nuclear bombs on warships, two Fat Man-style explosions (name Able and Baker) were carried out at Bikini Atoll in July of 1946. Able was exploded on the 1st of July, 1946. 24 days later, on the 25th of July, 1946, the more spectacular Baker was exploded underwater.
A group of Manhattan Project physicists created the Bulletin of the Atomic Scientists following the bombings of Hiroshima and Nagasaki. This emergency move was made by scientists who perceived a pressing need for an instant educational campaign about atomic weapons. Several project participants, including Bohr, Bush, and Conant, voiced the opinion that it was vital to come to an agreement on international control of nuclear research and atomic weapons in light of the destructiveness of the new weapons and in anticipation of the nuclear arms race. The Baruch Plan suggested the creation of an international atomic development authority but was not implemented. It was presented in a speech to the newly founded United Nations Atomic Energy Commission (UNAEC) in June of 1946.
The Atomic Energy Act of 1946 established the United States Atomic Energy Commission (AEC) to take over the duties and resources of the Manhattan Project after a political controversy about the long-term management of the nuclear program. It created civilian control over atomic research and production and separated atomic weapon development, manufacturing, and control from the military. The Armed Forces Special Weapons Project (AFSWP) took control of the military aspects.
The Manhattan Project came to a close on the 31st of December, 1946, however the Manhattan District would not be disbanded until mid-August of 1947.
By the 1st of October, 1945, the project had cost $1.845 billion, which is less than nine days' worth of military spending, and it had cost $2.191 billion by the time the AEC took over. $2.4 billion was allotted in total (which is equivalent to todays $23 billion). Less than 10% of the expense went toward the creation and production of the weapons, while more than 90% went toward the construction of factories and the production of fissionable materials. A total of four weapons (the Trinity gadget, Little Boy, Fat Man, and an unused Fat Man bomb) were produced by the end of 1945, making the average cost per bomb around $500 million in 1945 dollars.
The creation of nuclear weapons has significant and far-reaching effects on politics and culture for generations to come. In the spring of 1945, The New York Times' William Laurence, who coined the term "Atomic Age", was appointed as the project's official correspondent. Government officials believed that he had earned the right to report on the biggest secret of the war because of his unsuccessful attempts to convince the Office of Censorship in 1943 and 1944 to grant him permission to write about the explosive potential of uranium. The official news releases produced for the Trinity test and the bombing of Nagasaki were written by Laurence, who also observed both events. He then wrote a number of articles praising the advantages of the new weapon. His coverage of the bombs both before and after it aided in raising public awareness of nuclear technology's potential and propelled its advancement in the U.S. and the USSR.
The Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, Oak Ridge National Laboratory, Argonne National Laboratory, and Ames Laboratory are just a few of the national laboratories that the Manhattan Project's efforts during World War II left behind. Groves founded two more shortly after the war, the Sandia National Laboratories in Albuquerque, New Mexico, and the Brookhaven National Laboratory in Upton, New York. They were provided $72 million from Groves for research purposes during the 1946–1947 fiscal year. They would be pioneers in the field of what Alvin Weinberg, the director of Oak Ridge National Laboratory, would refer to as "Big Science" (a series of changes in science which occurred in industrial nations during and after World War II, as scientific progress increasingly came to rely on large-scale projects usually funded by national governments or groups of governments).
The possibility of using nuclear energy for warship propulsion had long piqued the curiosity of the Naval Research Laboratory, which aspired to develop its own nuclear project. Nimitz, who was now in charge of naval operations, was determined that the Navy should collaborate with the Manhattan Project instead. Captain Hyman G. Rickover, the most senior of a group of naval commanders sent to Oak Ridge, was appointed assistant director. They devoted a lot of time to studying nuclear energy and laid the groundwork for a nuclear-powered navy. In September of 1946, a similar team of Air Force experts travelled to Oak Ridge with the goal of creating nuclear aircraft. They had significant technical issues with their Nuclear Energy for the Propulsion of Aircraft project (NEPA), which led to its eventual cancellation.
Nuclear Medicine (medical specialty involving the application of radioactive substances in the diagnosis and treatment of disease) underwent a revolution in the immediate years following World War II as a result of the new reactors' ability to produce radioactive isotopes in previously unheard-of volumes. Oak Ridge started supplying radioisotopes to hospitals and academic institutions in the middle of 1946. Iodine-131 and phosphorus-32, which are used in the detection and treatment of cancer, accounted for the majority of the orders. Isotopes were used in biological, industrial, and agricultural research in addition to medical.
Groves said goodbye to those who had worked on the Manhattan Project as he turned over authority to the Atomic Energy Commission:
"Five years ago, the idea of Atomic Power was only a dream. You have made that dream a reality. You have seized upon the most nebulous of ideas and translated them into actualities. You have built cities where none were known before. You have constructed industrial plants of a magnitude and to a precision heretofore deemed impossible. You built the weapon which ended the War and thereby saved countless American lives. With regard to peacetime applications, you have raised the curtain on vistas of a new world."
In 2014, the United States Congress passed a law providing for a national park dedicated to the history of the Manhattan Project. The Manhattan Project National Historical Park was established on the 10th of November, 2015.
The world truly forever changed, and will never be the same.