Plutonium: The twin brother of Uranium

In the history of atomic bomb development, Uranium bombs and Plutonium bombs can be viewed as twin brothers. Along with U235, the Pu239 nuclei were also used to make the atomic bomb, the second bomb dropped on Nagasaki (Japan) on August 9, 1945.

Twins

Photo of the explosion in Nagasaki on August 9, 1945 caused 73,000 deaths

The appearance of the Uranium bomb twins and Plutonium bombs almost the same historical moment, terrified the world. Before after only 3 days, right in the summer of fate for Japan in 1945.

On the morning of August 6, the Urani bomb devastated the city of Hirohima. At 11h2 'on August 9, the Plutoni bomb hit the city of Nagasaki again. The bomb containing the Pu239 explosive, about 3.25 meters long, 1.52 centimeters in diameter, weighs 4.5 tons, was given a rather humorous name as "Fat Man". Similar to the name 'The Little Con' was given to the Urani bomb.

The destructive power of the Plutoni bomb is no less than 21,000 tons of conventional explosives (also known as TNT-Trinitro Toluen explosive). It completely destroyed the 6.7-square-kilometer house (one-third of Nagasaki's houses) and killed two-thirds of the city population (7.3 thousand people died and 7.5 thousand injured).

Plutonium - invasive invention of the world

The United States is not only the birthplace of the Plutoni atom bomb. It is also the country that discovered the existence of the new element Plutonium.

Glenn Seaborg (1912–1999)

Glenn Seaborg (1912-1999), America's legendary contemporary nuclear scientist, is the author of 10 new elemental inventions, including Plutonium.

Seaborg, a new doctor of chemistry, was only 28 years old, selected to send a gold face, to assemble a group of young scientists, embark on a unique and difficult experiment: to find a new element, heavier than Uranium, called Super heavy or ultra-Uranium elements.

On the most modern accelerator beam, they fired at Uranium beer a bunch of deutrium particles (d), then monitored new phenomena. Previously, the first super-Uran element with Z = 93, called Neptunium (Np), was found (1940) by another research group. This illuminates the belief for the new research team.

That night, Sunday, February 23, 1941, the light on the third floor of Gilman Building in the University of California campus (at Berkley), very late in the morning. The experiment lasted for 10 weeks, the wait seemed hopeless. Continue firing the deutrium beam (d) for another 4 hours!

Suddenly 'the world is like a wobble': an alpha particle has fallen into a counter, a radioactive isotope of element 94 has been synthesized and identified. It is the nucleus of a new element corresponding to the charge Z = 94: Plutonium element (taking the name of the Pluto star - Pluto), the chemical name is Plutonium and Pu symbol.

As calculated before, the first isotope of the Pu element found is Pu238. It was born by the process:

U238 (d, 2n) Np238 ®   Pu238 + b

Here, the process occurs as follows: U238 nucleus captures the d-particle and becomes nucleus of Np238, then shortly afterwards Np238 emits the b-particle (beta) to become the new Pu238 nucleus.

The appearance of the new element, Plutonium, happens like that. G. Seaborg was full of emotion when he recounted the moment of "labor" of the element Plutonium (Pu): At the time of encountering the first Pu nucleus, all suddenly fell silent, then broke and hugged each other in joy funny. They hurried home and buried themselves in their thirsty and sleepy nights.

It was the magical night in G. Seaborg's scientific life. For him, the element Plutonium was the first important invention of his life. Also with that invention he was soon matched with physicist Edwin McMillan who received the Nobel Prize in Chemistry in 1951.

From the nucleus Pu235 to the atomic bomb

What is quite surprising is that Pu's invention is so significant for mankind.

Indeed, only about a month after the invention of Plutonium, Seaborg discovered a particularly important property of one of the isotope nuclei of Plutonium, Pu239 isotope. Similar to the known U235 nucleus, the new Pu239 nucleus is also divided by neutron particles, to generate two new neutrons and emit a very large nuclear energy.

The atomic bomb nicknamed "Fatman" was dropped on Nagasaki on August 9, 1945

Clearly, with this discovery, Plutoni next to Uranium, will become an abundant source of nuclear fuel for mankind. But, unfortunately, in the tragedy of world history at that time, before serving human life as a precious fuel, Pu239 soon became an explosive for the atomic bomb (A bomb).

With resounding inventions, Seaborg was called to participate directly in the newly formed secret project, the Manhattan project. He was sent to the University of Chicago's Metal Laboratory, joining Enrico Fermi to create an atomic bomb. Here they built the Pu239 extraction technology in large quantities from the uranium fission process in the first US reactor and the first in the world.

In this case, Pu239 was born in the process:

U238 (n, γ) U239 - b® Np239 - b® Pu239

The process occurs as follows: U238 nucleus catches a slow neutron and becomes U239 nucleus. Almost immediately, this new nucleus emitted two b particles (beta) consecutively into a completely new nucleus, another isotope of Plutonium: Pu239.

After 3 years of intense work, 12 hours a day, Seaborg's collective has gained enough Pu to make 3 atomic bombs. The Plutonium bomb dropped on Nagasaki (Japan) as one of such Plutonium bombs.

Since there is almost no element Plutonium in nature, on the contrary there are many U238 isotopes, so the method of preparing Pu239 according to the above principle is the most optimal.

And so, with the goal of industrial-scale production of Plutonium, today's reactors with heavy water-retardants are the most ideal tool compared to any other nuclear reactor. In this type of furnace only natural uranium (no need to be enriched) is used as fuel. Heavy water (D2O) plays a role in slowing down fast neutrons produced during the reactor operation, facilitating the transformation of U238 nucleus into Pu239 nucleus.

At this point, the reader is clear why Iran's statement of intent to build a heavy water nuclear reactor has caused deep concern and a strong reaction of so many countries.

Tran Thanh Minh