In order to achieve high-quality underwater repair of spent fuel pool cladding defects in nuclear power plants,an underwater laser welding system with mobile positioning system,underwater laser-vision-wire feeding integrated equipment and mobile gas hood was developed based on underwater local dry laser welding technology.The underwater laser welding system was used to optimize the underwater welding process of the third generation nuclear spent fuel pool steel cladding(S32101 duplex stainless steel).The results show that the influence of water molecules on weld formation can be effectively reduced by using the drainage technology of equalizing flow pipe and simultaneous purging of groove.Using nitrogen as the protective gas for underwater welding of duplex stainless steel can increase the austenite content in the cladding layer and heat affected zone.The welding defects can be reduced by use of higher laser power,thus improving the stability of underwater local dry laser welding.The results of non-destructive testing and physical and chemical properties of welded specimens meet the requirements of welding standards for spent fuel pool construction,which proves the feasibility and reliability of the underwater laser welding system and welding process.
Underwater local dry weldingUnderwater laser welding systemDuplex stainless steelWelding process
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