What Is a Radiochemist?

Radiochemistry is a branch of chemistry that studies radioactive materials and chemical issues related to the process of nuclear transformation. Radiochemistry and nuclear physics are related and intertwined correspondingly, becoming two sibling disciplines of nuclear science and technology.

Chinese name: Radiochemistry
Nature: Chemistry

Year: the 60's
Century: 20th Century

Introduction to Radiochemistry

Radiochemistry mainly studies the preparation, separation, purification, identification of radionuclides, their chemical states at very low concentrations, the properties and behavior of nuclear transformation products, and the application of radionuclides in various disciplines. Since the 1960s, radiochemistry has focused on the development, production, and application of nuclear energy, and the ensuing environmental and other issues, and has carried out basic, developmental, and applied research.

Radiochemical history origins

The development of radiochemistry in China began in 1924. Madam Curie's Chinese student Zheng Dazhang brought the radiochemistry back to the motherland for the first time from the Curie laboratory of the Paris Radium Institute. Radium Research Institute. Zheng Dazhang and others studied the radiochemistry of plutonium and uranium series and achieved preliminary results. In 1937, due to Japanese militarism invading North China, the Peiping Research Institute was forced to move south, leaving the country in abundance, and the research on radiochemistry was suspended.

The People's Republic of China was established in 1949, and China's radiochemistry has achieved tremendous development. Since the mid-1950s, with the development of nuclear energy, radiochemistry has developed correspondingly as a basic discipline. For more than 30 years, especially in the fields of nuclear fuel production and recovery, preparation and application of radionuclides, actinide chemistry, nuclear chemistry, radioactive waste treatment and its comprehensive utilization, radioanalytical chemistry, and radiation chemistry. Fruitful results. The successful test explosion of the atomic bomb in October 1964 and the hydrogen bomb in June 1967 reflected that China's nuclear science and technology have reached a high level.

The name radiochemistry was coined by Cameroon in 1910. He pointed out that the mission of radiochemistry is to study the chemical properties and properties of radioactive elements and their decay products. This definition reflects the research objects and content in the early stage of radiochemistry development. With the discovery of artificial radioactivity and nuclear fission, the establishment of reactors and high-energy accelerators, etc., have a profound impact on the development of radiochemistry, making the content of radiochemistry constantly enriched and developed.

Modern radiochemistry mainly studies the chemical and nuclear properties of natural and artificial radioactive elements, and the chemical processes and processes of extraction, preparation, and purification. The focus is on nuclear fuels uranium, plutonium, plutonium, transuranic elements, and fragment elements. Nature, structure, laws of nuclear reactions and nuclear decay, and the application of these research results; research on the separation and analysis of radioactive materials and the application of nuclear technology in analytical chemistry; research on the preparation of radionuclides and their labeled compounds and radiation sources, and Its application in industry, agriculture, scientific research, medicine and other fields. The focus is on the use of reactors and accelerators to produce a variety of high specific activity or carrier-free radionuclides and radiation sources.

Radiochemical physical and chemical properties

Characteristics of Radiochemistry

The object of radiochemical work is radioactive material, and modern technologies for detecting radioactivity need to be fully utilized, so it has many characteristics not found in general chemistry.

First, the sensitivity of radiochemistry is extremely high, and the mass of several atoms can be detected. Second, it is easy to identify. In addition to being recognized by ordinary chemical properties, each radionuclide can also have its unique emission particle properties, energy, half-life, and Identification of the decaying mother-child relationship, etc. In addition, the characteristics of the radioactive material and its stable isotope are very similar, and the radioactive material can be tracked at any time to observe and study the relevant links in the chemical process.

In radioactive nuclear decay, the energy of emitting various rays is far greater than the chemical binding energy of environmental substances, resulting in a series of radiation effects such as radiation decomposition-combination, radiation oxidation-reduction, radiation catalysis, heat emission, and biochemical changes. In strong radioactive systems, the changes in chemicals caused by the radiation effect are very significant.

In most radiochemical operations, the concentration of radionuclides is extremely low, and the charge properties between ions are correspondingly prominent. It is easy to form radioactive colloids or aerosols, and to disperse or adhere to environmental chemicals. Therefore, special radiochemical techniques are required when handling radioactive materials that exceed the allowable dose prescribed by the state.

Radiochemical protection measures

In order to prevent radioactive gas particles from entering the human body and generating internal radiation, radiochemical operations should be performed in the work box. The inside and outside of the box are properly shielded so that the external exposure of the radiation to the human body is below the allowable dose; in order to reduce external exposure, special tools are used. For example, use a mechanical hand instead of direct hand contact and radioactive containers, transfer the solution with a pipette, separate the precipitate with a centrifuge tube, and use a quartz vessel that absorbs less radioactive material than glass. Solutions of strong radioactive substances or semi-dry solids can cause explosive gases due to radiation to decompose water, so more attention should be paid.

Related to Radiochemistry

Birth of Radiochemistry

In 1896 Roentgen discovered X-rays. In the same year, Becquerel studied the causes of fluorescence in the glass of X-ray tubes. When using potassium uranyl sulfate crystal as a phosphor, it was found that the photosensitive plate wrapped with black paper was exposed to light by uranium salts that did not emit light or discharge. Uranium has the strongest photosensitivity. Becquerel called it uranium light and discovered radioactivity.

In 1898, in order to find the source of radioactivity, the Curie couple created a special instrument for measuring radioactivity and measured the radioactivity of various substances. It was found that some uranium minerals and thorium minerals were more radioactive than pure uranium or pure thorium. Very few but highly radioactive substances. They applied the new principle of chemical analysis and separation, combined with a new working method of radioactive measurement, to successively discovered radon and radium, and thus a new discipline-radiochemistry was born.

Development of Radiochemistry

In 1903 Rutherford and Sody determined the law of the decay of the radioactivity of each substance in an exponential relationship. In 1910, Sody and Fajans simultaneously discovered the law of radioactive element displacement and proposed the concept of isotopes. In 1912, Heavisi et al. Attempted to separate radium D (lead 210) from lead with 20 chemical methods, but they did not succeed. Then they proposed radium D to indicate lead and successfully studied the behavior of lead in various chemical reactions. As a result, the radioactive tracer atomic method was created, and the application of radiochemistry began to develop.

In 1934, the Curie couple bombarded aluminum with alpha particles of plutonium, and obtained radioactive phosphorus 30 using chemical principles and methods, inventing artificial radioactivity. This is the first time that humans have used external effects to cause changes in the nucleus to generate radioactivity. It is one of the most important inventions of the 20th century. In the same year, Qilat et al. Found that when the nucleus captured a neutron to generate a new radionuclide, a series of chemical changes caused by the recoil effect later developed into thermal atomic chemistry.

Contribution to Radiochemistry

In 1938, Hahn et al. Used chemical methods to discover and prove uranium nuclear fission when studying the products of uranium irradiated with neutrons. It has opened the way for human beings to develop and use nuclear energy. This is a huge contribution of radiochemistry to the development of nuclear science and technology.

In 1940, Macmillan et al. Discovered transuranium element plutonium; Seaborg et al. Discovered plutonium, and in 1944 proposed the actinide element theory. In 1942, Fermi and others built the first nuclear reactor and achieved the first controlled chain-type fission nuclear reaction, marking the entry of humans into the era of using nuclear energy, and nuclear science and technology have developed rapidly since then.

With the successful development of nuclear weapons, nuclear power plants, nuclear ships, and other nuclear power devices, radiochemical work such as the production and recovery of nuclear fuel and the separation of fission products have developed tremendously, promoting the in-depth study of the properties of radionuclides and their applications in industry and agriculture The extensive application in the fields of scientific research, medicine and health has enriched the content of radiochemistry, making it a discipline with unique research purposes and methods.