Stud Tensioning Device for Steam Generators

Hydraulic Multi Stud Tensioner for primary circuit and secondary circuit components

Using our experience gathered in the course of many years, we have developed further products for utilization in nuclear power plants. We have developed tensioning equipment for further primary components based on a Multi Stud Tensioner with the usual design features and quality standards. NIS have provided customized solutions for our tensioning systems, and these have been utilized in nuclear power plants with different reactor types throughout the world. Safety and economic efficiency of the plants are of primary concern. These two basic concepts are taken into full consideration by NIS tensioning equipment, which reduce the radiation exposure of the operating personnel on the one hand as well as increase the service life time of the development relevant material components.


Multi stud tensioners for pressurizers

NIS Multi Stud Tensioner for maintenance access of the pressurizers are based on a similar or the same concept as for the steam generators. In many cases, we have been able to design these tensioners such that they are identical to those for the man way covers on the primary side of the steam generator, including the hydraulic unit and the elongation measuring system. Thus, it was possible to achieve a multiple application functionality of the tensioning system with significant reduction of the investment costs.


Multi Stud Tensioner for Main Cooling Pumps

NIS Multi Stud Tensioner for opening and closing of main cooling pumps are utilized worldwide in various reactor types. All studs of the main cooling pump cover are tensioned or detensioned simultaneously. The stud elongation is determined by infrared elongation measurement. The cover studs are screwed in and out pneumatically and the cover nuts are turned manually. These system functions shorten the maintenance time of the pump considerably, also implying a reduction of the radiation exposure dose of the personnel.


Multi Stud Tensioner for shutdown valves (tensioner segments)

We deliver worldwide stud tensioning devices for shutdown valves in nuclear power plants. The system functions of this Multi Stud Tensioner comprise simultaneous tensioning / detensioning of the valve cover studs, elongation measurement of the studs with an electronic measuring system and manual turning of the studs and nuts.

Multi Stud Tensioner for steam generators

NIS Multi Stud Tensioner (MST) for steam generators can be utilized in all power plant systems. For the MST it makes no difference whether vertically arranged steam generators according to the western standard or the horizontally arranged design of the Russian technology is involved.

The Multi Stud Tensioner are utilized for:

  • Man way covers on the primary and secondary side,

  • Hand-hole covers,

  • Eye-hole covers  (Inspection covers).

Depending on the actual requirements, the Multi Stud Tensioner are available in steel or aluminium design as complete rings or in segmented design.

As a further opportunity NIS designed tensioner segments which are linked hydraulically to form a complete ring system.

The segment tensioner considers the limited weight for manual handling during the tensioner installation. The number of simultaneously tensioned or de-tensioned studs varies depending on the design and utilization range on the steam generator.

Together with the Multi Stud Tensioner for steam generators, NIS deliver:

  • Compact portable electronically controlled hydraulic units with IPC

  • Infrared and blue tooth data transfer based measuring systems with digital dial gauges and magnetic quick connect adapters

  • Measuring systems with radio based data transfer

  • Test stands

  • Stud Extensions, Counter nuts, adapters

  • Transport trolleys and tools