Abstract: According to the manufacturing process and structural characteristics of the BOSS welding seam(Placement fillet weld between small branch pipe and cylinder) of the condensing tank, combined with the customer's requirements for the detection of BOSS welding seam defects, and referring to the standard RCC-M-2007 “Design and construction rules for pressurized water reactor nuclear island mechanical equipment”, the condensation Radiographic inspection process of tank BOSS welds was drafted, and radiographic inspection test and process verification were correspondingly conducted. The radiographic inspection results meet the requirements of relevant inspection standards, and the inspection results are very significant. According to the types of defects detected, the manufacturing process is improved and the product qualification rate is increased.