Abstracts and Available Papers Presented at the
2005 International RERTR Meeting

COMPLETION OF THE SAFETY ANALYSIS FOR THE WWR-M REACTOR IN UKRAINE TO ALLOW OPERATION USING LEU FUEL

Y. P. Mahlers and A. G. Dyakov
Kiev Institute for Nuclear Research
Kiev 03680, Ukraine

ABSTRACT

 

The 10 MW, WWR-M research reactor of the Kiev Institute for Nuclear Research is going to be converted from HEU (36%) to LEU (19.75%) fuel. The reactor currently uses HEU (36%) WWR-M2 fuel assemblies (3 tubes, UO₂-Al fuel meat with 1.1 gU/cm³ and 37.0 g ²³⁵U). Candidate LEU replacement fuel assemblies are: LEU WWR-M2 (3 tubes, UO₂-Al fuel meat with 2.5 gU/cm³ and 41.7 g ²³⁵U). To qualify this LEU fuel for conversion of the WWR-M reactor in Ukraine, neutronic and thermal-hydraulic characteristics of LEU fuel equilibrium core and transition mixed core containing both LEU and HEU fuel were calculated. The following accidents were analyzed: spontaneous withdrawal of a control rod bank; incidental falling of a fuel assembly in a cell of the core; partial blockage of coolant flow across the core with accompanying partial melting of the core; full break of the first loop pipe with accompanying full melting of the core. The safety of fresh and depleted HEU and LEU fuel storage was analyzed. The revised safety documentation for LEU conversion of the WWR-M reactor has been reviewed and approved officially by the State Scientific Technical Center, as requested by the Ukrainian Nuclear Regulatory Committee.

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