One fuel channel (FC) and one channel of control and protection system (CPS) were removed from the Unit 1 reactor. These works are carried out with a research purpose in the framework of working documentation development for the the second stage of the Project "Chornobyl Units 1, 2, 3 Final Shutdown and Preservation" (FS&P). Dismantling and processing of the channels has practical value for determination of duration for decommissioning activities, preservation and safe enclosure of reactors.
Estimated term for FC & CPS channels dismantling and processing, according to the "Program of Units 1, 2, 3 Shutdown & Preservation Stage implementation" approved by SNRIU, until 2028. The Stage duration is determined, in particular, by the time of works execution in each of 3 reactors, containing from 1661 to 1693 FC and 227 CPS channels.
It is assumed that removed FC and CPS will be fragmented on the modernized Long Length Waste Cutting Facility (LLWCF), where special items will be dried, fragmented, packaged in the overpack, obtained packages will be characterized and loaded into transport containers. The duration of dismantling works and special items processing is determined by LWCF capacity: within one day and night (two twelve-hour shifts), only 2 channels can be processed at the Facility.
"Due to delay in implementation of the Project Creation of a Modernized Long Length Waste Cutting Facility at Chornobyl NPP we are forced to look for ways to speed up the work. In particular, duration of long length waste cutting process can be reduced by removing from the process operations on special items drying and by reducing the number of transport operations, since the technical conditions established at ChNPP during decommissioning allow to make appropriate changes to previously approved technical solutions", — noted Vladimir Peskov, Deputy Technical Director for Operation.
In addition, since the work on FC and CPS channels removal was performed in large scale at Chornobyl NPP during operational Units repairs, that is, in the 90's of the last century, these works will help to identify the level of skills of the workers involved in the work, dose load, as well as availability of the necessary equipment for special items retrieval from the reactor. "There are not many specialists at the plant who are capable to perform these works. Consequently, the transfer of experience in performance of the channels retrieval from experienced workers to young people, is a very important part of today's activity", — emphasized the Deputy Technical Director.
For information
In 2009, the Verkhovna Rada of Ukraine approved the Law "On the National Program on Chornobyl NPP Decommissioning and Shelter Object transformation into Environmentally Safe System". "Deferred phased dismantling" SAFSTOR Strategy was accepted for Chornobyl NPP (from English: SAFe STORAGE — safe storage, storage under supervision). According to the National Program, decommissioning is carried out in 4 stages:
1. Shutdown (preparatory stage for decommissioning, from 2000 till 2015). The stage during which the nuclear fuel was removed and moved to a Spent Nuclear Fuel Storage Facility intended for long-term storage.
2. Final Shutdown and Preservation (current stage, from 2015 till approximately 2028). The tasks for this stage are following:
● bringing ChNPP Units to a state excluding the possibility of using them for power generation;
● removal of ionizing radiation sources subject to control from power Units;
● preservation of reactors and most contaminated equipment.
3. Safe storage of the preserved part of Power Units within the period during which a natural decrease of radioactivity should achieve an acceptable level due to the natural decay of some radionuclides. This will reduce the volume of radioactive materials to be removed during the Final Decommissioning Stage (approximately until 2045).
4. Dismantling. The stage during which equipment will be dismantled and site will be cleaned up with the purpose to lift in maximum restrictions and regulatory control (approximately until 2064).
