From June till September this year personnel of the radiation safety shop (hereinafter referred to as the RSS) have been involved in the measurements of gamma radiation exposure in the near zone of the New Safe Confinement (hereinafter referred to as the NSC).
The objective of the measurements was to analyze how much the level of gamma radiation has been reduced in the work area after sliding the NSC over the Shelter Object.
To accomplish this task, employees of the RSS performed measurements in three vertical plane surfaces; each of them had 9 control points at the height of 30, 60 and 90 meters above the ground. The plane surfaces are located at the distance of 120, 256 and 355 meters from the Shelter Object, covering the whole work area.
The measurements were performed with the use of electronic dose meter DMC 2000S manufactured by MGPI mounted on the drone.
Gamma radiation levels in the control points were determined after processing the readings of dose meters with the use of the DOSIMASS program.
Similar measurements have already been performed in the past - in 2003-2004 - by personnel of the Institute for Safety Problems of Nuclear Power Plants at the stage of development of design documentation for the NSC construction. The efficiency of the NSC arch radiation protection has been measured in comparison with these data.
As a result, after sliding the arch into its design position and after the completion of preparatory activities related to the NSC construction (removal of fuel materials and solid radioactive waste, concreting of the arc assembly area, as well as filling the work area with uncontaminated crushed stone) at the average, gamma radiation in the near zone of the NSC decreased in the following way:
●In plane surface No.1 – by a factor of 9,9;
●In plane surface No.2 – by a factor of 20,7;
●In plane surface No.3 – by a factor of 12,6.
