How many nuclear bombs were built in World War 2?

Answer 1

Four nuclear bombs were constructed and three of these were detonated during World War 2.

The first nuclear bomb was a plutonium implosion bomb, with a yield of about 20 kilotons, exploded northwest of Alamogordo, New Mexico for the Trinity test, July 16, 1945.

A "gun style" uranium-235 bomb was dropped on Hiroshima, Japan, on August 6, 1945, 8:16 AM local time, and it exploded at an altitude of 1900 feet with an estimated yield of 12 kilotons. There was only enough U-235 uranium to construct one bomb.

A third nuclear bomb, a more efficient plutonium-implosion device, was dropped on Nagasaki, Japan, on August 9, 1945, at 11:06 AM local time, and exploded at an altitude of 1650 feet with an estimated yield of 22 kilotons, (which missed its intended target by one and a half miles).

As a result of the two nuclear bomb blasts, there were estimated 120,000 instant fatalities, and, of course, more to follow. Had the Nagasaki bomb not been off target, the fatalities would have been at least 40,000 more.

With the surrender of Japan shortly after the second nuclear blast, World War II ended, and only the three weapons had been deployed.

A fourth nuclear bomb similar to the first and third had been built just before Japan agreed to surrender and shipped from Los Alamos to San Francisco. Before it could be flown from San Francisco to Tinnian for use on Japan, Truman ordered the use of nuclear bombs stopped. This bomb was then returned to Los Alamos, becoming the first bomb in the US postwar nuclear stockpile.

Had the war continued the Manhattan Project had plans, factories, infrastructure, and bombers to build and drop 20 more nuclear bombs on Japan before the end of 1945. Whether or not this rate could have actually been sustained successfully will never be known as only the first 2 of the planned 23 bombing missions were needed. However soon after the war ended the plutonium production rate at Hanford, Washington had to be severely curtailed to limit the extent of radiation damage to the three reactor's graphite moderator that was causing swelling of the graphite and bending the metal tubes that the fuel pellets passed through.