Nuclear industry may save millions

The nuclear industry is set to save millions of pounds in revenue lost during maintenance work on pressure vessels, and improve operator safety. Industry specialist Hydratight has developed a special bolt tensioning tool that overcomes problems when using existing multi-stud tools (MST) that remove several bolts at once from the pressure vessel casing. During reactor […]

The nuclear industry is set to save millions of pounds in revenue lost during maintenance work on pressure vessels, and improve operator safety.

Industry specialist Hydratight has developed a special bolt tensioning tool that overcomes problems when using existing multi-stud tools (MST) that remove several bolts at once from the pressure vessel casing.

During reactor operation, thermal expansion and movement causes sticking from misalignment of the stud on the bolt thread, hampering MST operation.

The Hydratight system removes one bolt at a time using a patented floating drive mechanism to compensate for any stud misalignment. Dual operation combines a bolt tensioner to remove the nut and a stud runner to remove the stud.

The tool requires 25% 50% of the torque of current MSTs, making it less likely to damage the nut or stud. It can be operated remotely, as a single unit to remove difficult studs or linked together to replace existing older MST units.

Nuclear Electric has saved an estimated £1m on the first applications of the tool, which was developed for its Sizewell B plant.

It took five minutes to remove a bolt that the existing MST had failed to extract during an enforced 24-hour shutdown of the main reactor pressure vessel.

Since the development for Sizewell B, a Korean nuclear power station has placed an order for a three-tool tension system to back up the existing MST.