METHOD OF BREAKING DOWN ZIRCONIUM CLADDING OF FUEL RODS OF FUEL ASSEMBLY Russian patent published in 2009 - IPC G21C19/34 G21C19/38 

FIELD: nuclear physics.

SUBSTANCE: invention relates to methods of preparing for regenerating nuclear fuel from irradiated fuel elements. Elements made from stainless steel - heads, tail pieces, guide channels for absorbing elements - are separated from the fuel assembly. The fuel assembly is taken for embrittlement of the fuel element cladding. Embrittlement is carried out in enclosed space in air at temperature ranging from 900 to 1200°C. Further, the brittle cladding is mechanically broken down and fuel is removed, as well as the broken down fuel element cladding and other elements of the fuel assembly. The method is characterised by that, air in the enclosed space is enriched with nitrogen until attaining content of oxygen in the air ranging from 5 to 10 vol %, and heating is done in an induction magnetic field with frequency ranging from 40 to 100 kHz, in which the remaining part of the fuel assembly is fed right away as a whole or successively in parts. A special case of the method is when elements made from stainless steel are separated from the fuel assembly before taking for embrittlement by tearing the elements away from where they are attached with local induction heating.

EFFECT: increased efficiency of spent nuclear fuel and increased environmental safety.

2 cl