In January 2022, Khlopin Radim Institute (formerly State Radium Institute, Radium Institute of the USSR Academy of Sciences) marked its centennial. The institute’s name reflects one of its most important initial tasks associated with the production of radium preparations. Throughout the century-long history, the institute’s scope of research underwent continuous evolution with the progress of nuclear science and engineering and with the emergence of new practical problems. The main directions of the institute’s activity were formulated already in the first years of its existence. These included radiochemistry, ionizing radiation physics and measurement methods, and geology of radioactive elements. Studies in these fields are being continued up to now. New research fields emerged in connection with the need for mastering the nuclear energy for defense and peaceful purposes. With the progress of nuclear power engineering, problems of spent nuclear fuel reprocessing and radioactive waste management attracted more and more attention. In the past decades, this field became one of the main fields of the institute’s activity.

Along with nuclear power engineering, studies dealing with the use of radioactive elements and isotopes in other fields, primarily in nuclear medicine, are also being actively developed. In particular, there has been a peculiar “return to the sources”: Radium isotopes are again in the focus of researchers’ attention, but now in connection with the development of therapeutic radiopharmaceuticals. In addition, environmental problems associated both with natural radioactivity and with radioactive pollution of the environment occupy traditionally important place in the institute’s activity. Basic research in the fields of radiochemistry and nuclear physics is also being continued.

This issue of Radiochemistry journal compiles studies made in the field of radiochemistry by researchers from Khlopin Radium Institute or with their participation. These papers demonstrate the diversity of problems being solved by the institute, which remains one of the leaders of radiochemical research both in Russia and in the world.

The Editorial Board