The Experimental Demonstration Center (EDC) is under construction at the Mining and Chemical Combine, Zheleznogorsk to test advanced and environmentally safe technologies for the VVER-1000 SNF reprocessing. The first start-up facilities were constructed in December 2015.
The flowsheet of the EDC first start-up facility includes disassembling of spent fuel assemblies into separate fuel rods and their segmentation for subsequent dissolution of the spent fuel.
A fully equipped SFA segmentation cell (including the SFA knock-down facility and fuel rod cutting facility) was developed by Sosny's staff, who also supervised equipment fabrication, participated in the equipment tests, on-site installation, and pre-commissioning at the Mining and Chemical Combine.
The radiochemical industry had not utilized the disassembly of spent fuel assemblies into separate fuel rods before because it was difficult to achieve high-precision positioning of the actuators to pull out the fuel rods from the SFA support grid. Manual SFA disassembling is very time consuming, therefore, the necessity arose to design equipment and automated process control systems to knock down VVER-100 SFA. This facility enables cutting off the SFA lower support grid to pull out each of 312 fuel rods from the spacer grids for subsequent cutting into fragments.
The segmentation facility cuts the fuel rods into fragments of 25–49 mm long (operator's choice) and loads them into a crucible for subsequent process operations (voloxidation, dissolution, etc.). A distinctive feature of the segmentation facility design is that the cutting causes little to no crimping of the fuel tube ends; thus,facilitating the spent fuel separation during voloxidation.
The in-cell segmentation systems are maintained remotely with one power and four master-slave manipulators.
The SFA disassembling and fuel rod cutting technologies were first tried out with an inactive SFA scale model, then using a full-scale SFA with the rods filled with depleted uranium, thus the process variables and optimal operating modes were defined. The last stage of testing was performed using actual spent fuel.
The unique technology in place at the Experimental Demonstration Center will result in more efficient and environmentally safe SNF reprocessing.
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