V. G. Volkov

New portable gamma-camera for nuclear environment and its application at rehabilitation works

Industrial prototype of portable gamma camera for nuclear environment was developed. Camera has new 2D position sensitive detector (PSD), which is based on generally used components as image intensifier with MCP and digital video camera with an industrial CCD. The gamma image is formatted on PSD by two-cone collimator or coded mask. The dimensions of detecting head are ~ L=50 cm and D=12 cm. Scintillating plate has useful diameter 38 mm and thickness from 1 up to 4 mm, depending on aperture used. Two co-ordinate scanning unit is assigned for distant choice of device field of view. A special portable computer is used for control of all gamma camera subsystems by operator, for processing of gamma images, storage and displaying and for operation with images. Standard distance between detecting head and computer is 50 meters. The results of application of gamma-imaging during rehabilitation activity at territory of temporal storage of radioactive wastes of RRC Kurchatov Institute are presented and discussed.

A gamma locator for remote radioactivity mapping and dose rate control

The automatic system for remote measurements of radiological conditions at territories of rehabilitation activity was developed. The apparatus is realized as computer controlled collimated gamma-locator. The methods of exposure dose rate (EDR) calculation in 3-D space around territory of activity and analysis of relative input of main gamma-sources into EDR are developed. The results of application of the system during rehabilitation activity at RRC Kurchatov Institute for exposure dose rate monitoring and control are presented and discussed.

HLRW Management During MR Reactor Decommissioning in NRC “Kurchatov Institute”

A program of decommissioning of MR research reactor in the Kurchatov institute started in 2008. The decommissioning work presumed a preliminary stage, which included: removal of spent fuel from near reactor storage; removal of spent fuel assemble of metal liquid loop channel from a core; identification, sorting and disposal of radioactive objects from gateway of the reactor; identification, sorting and disposal of radioactive objects from cells of HLRW storage of the Kurchatov institute for radwaste creating form the decommissioning of MR. All these works were performed by a remote controlled means with use of a remote identification methods of high radioactive objects.A distribution of activity along high radiated objects was measured by a collimated radiometer installed on the robot Brokk-90, a gamma image of the object was registered by gammavisor. Spectrum of gamma radiation was measured by a gamma locator and semiconductor detector system. For identification of a presence of uranium isotopes in the HLRW a technique, based on the registration of characteristic radiation of U, was developed.For fragmentation of high radiated objects was used a cold cutting technique and dust suppression system was applied for reduction of volume activity of aerosols in air. The management of HLRW was performed by remote controlled robots Brokk-180 and Brokk-330. They executed sorting, cutting and parking of high radiated part of contaminated equipment.The use of these techniques allowed to reduce individual and collective doses of personal performed the decommissioning. The average individual dose of the personnel was 1,9 mSv/year in 2011, and the collective dose is estimated by 0,0605 man×Sv/year.Use of the remote control machines enables reducing the number of working personal (20 men) and doses. X-ray spectrometric methods enable determination of a presence of the U in high radiated objects and special cans and separation of them for further spent fuel inspection. The sorting of radwaste enabled shipping of the LLRW and ILRW to special repositories and keeping of the HLRW for decay in the Kurchatov institute repository.Copyright

Experience of Gamma-Locator System Using for Radiation Monitoring During Rehabilitation Works at Temporal Radwaste Storage Area of Kurchatov Institute

Remote monitoring of radiological conditions on large areas is important task during large-scale activity with radioactive contamination/materials. We present results of application of an automatic system for remote measurements of radiological conditions at territory of rehabilitation activity. The system is scanning collimated spectrometric detector, its construction and main performance characteristics are shortly described. System, including two different measurement heads was used during three years for radiological monitoring of area rehabilitation works at temporal radwaste storage area of RRC Kurchatov Institute. The results of its application for exposure dose rate monitoring at particular control points from separate strong sources located in the territory of activity are presented and special cases are studies in details. The method of EDR calculation in 3-D space around territory of activity and analysis of relative input of main gamma-sources into EDR are presented. The results of application of the system during rehabilitation activity at territory of temporal storage of radioactive wastes of RRC Kurchatov Institute have shown high efficiency of this system for such operations.Copyright