A HISTORY OF APPLIED RADIOCHEMISTRY DIVISION DEVELOPMENT

The division of applied radiochemistry was organized under the leadership of c.c.s. R.I. Lyubtsev in 1976 on the basis of two departments included into it: Radiochemical Department located in Saint-Petersburg, and department located in the city of Gatchina in Leningrad Region at the site of LINP (LIYaF) under USSR AS (now - PINP under RAS). Each of those departments included 4 laboratories.

Laboratories of Radiochemical Department (Heads of these laboratories are academician B.P. Nickolskiy, professor M.F. Pooshlenkov, professor V.I. Paramonova, and c.c.s. V.P. Popick, who has become a chief of the laboratory formerly directed by academician A.A. Greenberg) were formed in a period from 1946 to 1961 and were oriented to development and manufacturing application at radiochemical plants of sedimentation, extraction, and sorption technology for processing of irradiated uranium blocks with the purpose to recover plutonium. Applied `works of this period were accompanied by a large scope of fundamental researches and used outcomes of researches as a basis for working. Such combination of fundamental and applied researches represents characteristic feature of the Department to this very day.

Radiochemical Division of the Institute (at present - Scientific and Experimental Complex - SEC) was put into operation in 1967. In 1967-1972, in development period the Division was directed by c.c.s. L.N. Lazarev, who later on became a doctor of chemical sciences and Director to Radium Institute. This Division was created with the purpose to develop and test aqueous methods of NPP SNF processing within the whole range of works, starting from the main procedures to RW management.

The first delivery of SNF from NPP was realized in 1972 with the purpose to test extraction technology elaborated for the plant RT-1, which was put into operation in 1977. To date more than 120 Kg SNF has been subjected to processing in the run of researches and testing of various technologies. In 70s-80s there were started researches in HLW fractioning with the use of chlorinated cobalt dicarbollide proposed to application together with Czechoslovak experts. On the basis of these works in 1996 at the site of PA "Mayak" there was commissioned installation UE-35 destined for processing of the waste, which had been accumulated in previous years. This installation is still operated. Scores of million curies in the waste have been treated in the installation UE-76 to date.

Testing of HLW vitrification technology was carried out on SNF from NPP in experimental installation. After the event there were presented recommendations for vitrification installation EP-500. This installation is currently operated at PA "Mayak". Gas-purification technology was specially developed for this installation.

By means of Division's efforts there was conducted comparative testing of single operation modes of technological procedures and fatigue tests of various type extraction process vessels: mixer-settlers, centrifugal extractors, and vibration columns. A number of basic procedures were perfected: laser cutting of cladding, cladding embrittlement by nitration method, cladding dissolving. Problems of filtration, generation of insoluble precipitates, and management of them were subjected to active studying.

Development and testing of ecologically acceptable SNF integrated processing technology for the plant RT-2 has become the main task for the Division in its final membership, as well as coordination of other organizations activities on the way of this task implementation (the work is directed by professor L.N. Lazarev and c.c.s. R.I. Lyubtsev).

In 90-s and in the beginning of the present century the Division carried out comprehensive examination of whole-extraction NPP SNF processing technology (modified Purex process) for the plant RT-2, and aqueous segment of complex technology representing a combination of dry (distillation of UF₆) and aqueous extraction methods, including fractioning of long-lived radionuclides.

There were elaborated proper technologies and sizeable quantities of Xe, Kr, фУ, ¹⁴C , and a number of other isotopes were extracted from SNF of NPPs. In addition, isotope-pure ²³⁴U was accumulated with the help of separator with the purpose to specify nuclear constants.

Producing of radionuclides to be applied in scientific and medical purposes was started on the basis of SEC in early 90-s. For the period passed the SEC has become a stable manufacturer of radionuclide products, provided with appropriate scientific and technical potential required for rendering of engineering services.