Radiation survey of radioactive objects at the Kirovo-Chepetsk chemical combine

Abstract

The methods and means for performing a radiation survey of objects and grounds of the Kirovo-Chepetsk Chemical Combine are presented. Results of a survey of rooms in the combine and measurements of soil contamination levels on the grounds and of the specific activity of samples of radioactive wastes in temporary repositories and slag dumps are presented. The surveys make it possible to develop a concept and a project for rehabilitating these objects and grounds and to choose a technology for handling radioactive wastes during liquidation or preservation of repositories.In 2007-2008, specialists from the Russian Science Center Kurchatov Institute, Moscow Scientific and Industrial Association Radon, and the Center for the Administration of Federal Property examined radioactively contaminated objects and grounds of the Kirovo-Chepetsk Chemical Combine in order to collect data on the contamination of buildings, where work on the reprocessing of uranium raw material was terminated, as well as sludge and radwaste repositories. At the same time, it was discovered that individual areas on the grounds of the combine were radioactively contaminated as a result of the handling of radwastes as well as the presence of equipment contaminated at the early stages of the development of the technology for reprocessing uranium hexa-and tetrafluoride. In addition, it was necessary to determine the volumes of remediation work, identify the most critical objects and grounds, and develop remediation steps. Models of radionuclide migration in environmental objects and forecasts of radionuclide propagation in the next few years will be developed on the basis of these data.Basic Reasons for the Radioactive Contamination of Objects and Grounds. The Kirovo-Chepetsk Chemical Combine is located on the western edge of the town of Kirovo-Chepetsk. The production of uranium hexafluoride was set up there in the 1940s. Facility No. 93 for the production of uranium tetrafluoride was started up there in 1954 and reached its full production capacity in 1955. Initially, it was assumed that this facility would use secondary uranium which had been irradiated in a reactor. After the irradiated uranium was dissolved and the plutonium and most of the fission products in the form of uranyl-sodium diacetate salt had been removed from it, the irradiated uranium entered facility No. 93 for reprocessing into uranium tetrafluoride and then into facility No. 2 for the production of uranium hexafluoride [1]. In 1961, specialists at the combine and at the All-Russia Research Institute of Chemical Technology (VNIIKhT) developed a technology for repro-

Evaluation of the geoenvironmental safety of radwaste repositories

“…A radiologically dangerous object is not isolated from the environment, either thermophysically or hydrodynamically. The components of the object (waste mass, protective barriers, structural design) can accept heat from the outside and conduct and transmit heat to the environment [10][11][12][13]. The construction materials in the object, which are porous and permeable, change the moisture content and hydrological properties as a result a liquid phase entering from the environment and give back the excess water [2][3][4].…”

“…A loss of the integrity of the protective barriers opens the possibility of atmospheric precipitation and ground water penetration. As a result, moisture processes are activated, causing the following [11][12][13]:…”