Handling radwastes during rehabilitation of contaminated objects and grounds of the Kirovo-Chepetsk Chemical Works

Abstract

Possible ways to rehabilitate the objects and grounds of the Kirovo-Chepetsk Chemical Works are examined. The technology for handling radioactive wastes and methods for immobilizing radioactive wastes in repositories are briefly described. Ways to eliminate radwaste repositories containing medium-level wastes with fissile substances and α-emitters are proposed. The experience gained in such work abroad is examined and the problems which must be solved to rehabilitate the objects at the Works are noted.The main result of the examination of the Kirovo-Chepetsk Chemical Works performed by specialists from the Center for Federal Property Management, the Russian Science Center Kurchatov Institute, and the Moscow Scientific and Industrial Association Radon in 2007-2008 was a concept for rehabilitating radioactively contaminated objects and grounds of the Kirovo-Chepetsk Chemical Works while assuring the radiological safety of the people living in Kirovskaya Oblast [1]. Possible technologies for handling the radwastes formed during the rehabilitation work must be identified and examined in order to develop a project for decommissioning and rehabilitating a radiologically dangerous object. A special feature of the radiation conditions at the Works is the wide assortment of contaminating radionuclides, including fissile materials, actinides, and fission products. It is precisely the technologies for eliminating, isolating, and immobilizing wastes containing the radionuclides mentioned that must be regarded as the primary technologies which will be used for rehabilitation and decommissioning nuclear and radioliogically dangerous objects of the Works.The objective of using the technologies considered must be to eliminate wastes during the liquidation of radiologically dangerous objects, reduce their volume to be disposed of, and stop the radionuclides from entering the environment. These are the standpoints from which the technology must be viewed at the objects to be rehabilitated.Technologies for Equipment Decontamination and Disassembly. A radiation survey of the objects at the Works showed that the primary problem of rehabilitation is the removal of wastes from the process systems and the disassembly of the equipment in building No. 93, whose state at this time is close to being an emergency. Visual inspection of the ventilation system showed that process deposits ranging in thickness from 1 to 5 cm and more are present at the bottom of the air ducts (see Fig. 1). Estimates show that up to 3.6 tons of medium-level wastes containing isotopes of fissile elements are concentrated in the ventilation systems of this building. It is proposed that the ventilation systems and equipment be disassembled by means of cold cutting methods and robot technology [2][3][4][5]. The wastes are to be removed by mechanical methods using at the final stage hydroabrasive decontamination or high-pressure water jets.

Experience in decontamination of radioactive soil on the grounds of the National Research Center Kurchatov Institute

“…As a result, experience was gained on a complete cycle of processing radioactive soil, including primary assessment of the nuclide composition of the contamination and the volume, extraction and radiometric monitoring, preliminary separation and decontamination, which decreases by 5-6-fold the volume of low-level wastes requiring removal to a longterm storage facility. This experience was taken into account in the development of a concept for the rehabilitation of radiologically hazardous objects and grounds of the Kirovo-Chepetsk Chemical Works [8] and technical proposals for reworking the removal and clean-up operations after the radiological accident at the Podolsk Non-Ferrous Metals Plant [9]. It could be helpful for developing rehabilitation projects for other radioactively contaminated industrial objects and grounds.…”