The culprit who killed Marie Curie is still "alive" in her notebook

The culprit who killed Marie Curie is still "alive" in her notebook

As early as a hundred years ago, there was a scientist who devoted almost his life to the extraction of chemical elements, and she was Marie Curie (Marie Curie).

On November 8, the official Nobel Prize tweet published the notebook that Marie Curie had used.

According to the Nobel Prize, Marie Curie died of aplastic anemia on July 4, 1934, the result of years of radiation exposure to her work. Even today, some of her books and papers are highly radioactive and must be preserved in lead boxes. The notebook presented in this Nobel Prize will have radioactivity for 1500 years.

"Scientifically, it's normal for notebooks to still be radioactive." Zheng Weifang, director of the Institute of Radiochemistry of the China Institute of Atomic Energy Science (hereinafter referred to as the Institute of Atomic Energy), said in an interview with the Science and Technology Daily reporter.

Radioactivity persistence is determined by the half-life of the nuclide

In 1896, the French physicist Becquerel discovered in experiments that elemental uranium spontaneously emits a penetrating ray similar to X-rays. Later, Marie Curie discovered that this phenomenon was not just a property of uranium, but a common property of certain elements, which she called radioactive and the elements of this property radionuclides. After several years of hard work, she found additional radionuclides— polonium (Po) and radium (Ra), and thus became the world's first two Nobel Prize winner.

Zheng Weifang told reporters that the notebook used by Marie Curie is still radioactive and will last for thousands of years, which is directly related to the half-life of radionuclides.

In physics, the half-life of a radionuclide is the time it takes for its radioactive atoms to decay to half of their original quantity within a sample. The half-life of radionuclides varies greatly, from as short as less than a second to hundreds of thousands of years. The shorter the half-life, the more unstable its atoms are, and the higher the chance of each atom decaying.

The atomic number of polonium is 84 and is a silvery-white metal. According to research, this element is very rare on earth, but it is highly toxic, its half-life is 138 days, if Marie Curie's notebook is contaminated with polonium, its radiation is now basically negligible.

If it's radium, the situation is very different. Radium has an atomic number of 88 and is a highly radioactive element. Of the isotopes of radium, the most stable isotope is radium-226, with a half-life of about 1600 years. This also means that after a half-life, that is, after 1600 years, its radioactivity intensity will drop to 1/2 of the initial value.

So, can the radionuclides on Marie Curie's notebook be removed? Zheng Weifang told reporters that it can be wiped with detergent, but this can only transfer radionuclides, and cannot eliminate them. To eliminate radionuclides, or shorten the half-life of radionuclides, in addition to the spontaneous decay of their nuclei, nuclear reactions (technical terms called transmutation) can also be used to transform long-lived nuclides with a half-life of thousands or even tens of thousands of years into nuclides with a shorter half-life. Artificial nuclear transmutation can be achieved by nuclear reactors, particle accelerators and other devices.

The treatment of radionuclides is mostly carried out in a hot chamber

What exactly are radionuclides used for? Radium, for example, releases α and γ rays during decay, as well as a radioactive gas called radon. α rays and γ rays have a killing effect on bacteria and cells, so they are used in clinical medicine to treat cancer. In addition, in the process of exploring petroleum resources, technicians use radium and beryllium mixtures as a source of neutron radiation.

In addition, the most heard radionuclides are probably uranium and plutonium, which are the raw materials for making nuclear weapons. They released a lot of energy through nuclear fission reactions, but also released high-intensity radiation, and the atomic bomb dropped on Nagasaki City used plutonium to make the core part.

With the deepening of understanding, human beings' awareness of radionuclide prevention has also been continuously improved, and a corresponding protection system has been slowly established. The treatment of strong radionuclides is now carried out in hot chambers where precautionary measures are in place. A hot cell is a special facility that encloses radionuclides in a seal to prevent radiation from penetrating or leaking out to cause harm to people.

In 2015, China's first power reactor fuel reprocessing R&D facility hot room was officially opened, its wall thickness of 1.1 meters, installed 7 layers of lead glass peep window. Lead glass was chosen because lead shields rays. In addition, operations must be carried out in a closed, negative pressure and ventilation environment.

Unlike traditional chimneys, chimneys in hot rooms do not smoke because nuclear reactions do not occur chemically like ordinary combustion, but rely on atomic mass losses to release energy, so they do not emit carbon dioxide, sulfur dioxide and nitrogen oxides. After multiple filtration, the exhaust system in the hot room adsorbs radionuclides in the hot room air, and after meeting strict emission standards, the gas is allowed to be discharged through the chimney.

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Source: Science and Technology Daily