Technologies of repair of welded joints in Du800 bimetallic pipelines of the multiple forced circulation circuit of RBMK-1000 nuclear energy systems using one-sided welding

摘要

In producing welded joints in DU800 bimetallic pipes of the multiple forced circulation circuit [parent metal - 22K pearlitic steel and stainless steel cladding (04Kh20N10G2B steel)] for RBMK-1000 nuclear energy systems, the producing and assembling companies initially carried out welding of the outer side of the main layer of the pipeline made of the pearlitic steel and this was followed by welding (reconditioning) the protective deposit (cladding layer) inside the pipeline. The welding (deposition) of the cladding layer inside the pipeline is a complicated technological operation, even in the assembling conditions. The execution of this operation in repair after service, taking into account the requirements of the RB standard, makes his operation not only exceptionally complicated but, taking into account radiation doses, also unsafe. The Scientific Research Institute of Heavy Engineering (TsNIITMASh) developed and carried out investigations of a new technology of repair of DU800 bimetallic pipelines of the MCS of RBMK-100 power units on the outer side ('one-sided' welding) without affecting the protective cladding of the root sections of the welded joint.