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Eddy Current Inspection of Reactor Case Details


Creation and Testing of an Automated System for EC (Eddy Current) Inspection of Threaded Surfaces of Stud Sockets at VVER-1000 Reactor Case

Tech Area / Field

  • FIR-NSS/Nuclear Safety and Safeguarding/Fission Reactors
  • INS-DET/Detection Devices/Instrumentation

3 Approved without Funding

Registration date

Leading Institute
VNIIEF, Russia, N. Novgorod reg., Sarov

Supporting institutes

  • Balakovo NPP, Russia, Saratov reg., Balakovo-26


  • European Commission / Joint Research Center / Institute for Transuranium Elements, Germany, Karlsruhe

Project summary

The project intends to create an automated system for EC inspection of stud sockets of threaded surfaces at VVER-1000 reactor case and to test the system at Balakovskaya NPP.

Actually, automated operational inspection of a stud socket of the reactor cases (of VVER-1000 type in particular) is the most topical issue for Russian NPPs. Difficulty of access, pollution of the inspection object, limited time for inspection make it impossible to use traditional NDT methods.

Eddy current (EC) method belongs nowadays to the actively developing electromagnetic methods of nondestructive control. It is based on the analysis of the eddy currents induced in the inspection item with an external field. It has the following advantages: high information density; no direct contact; simplicity of technique, and insensitivity to the environmental parameter changes. This makes it attractive as an automated system for stud socket inspection.

At present, there are no domestic industrial facilities to control threads of the stud sockets on the Russian market. The majority of Russian NPPs still use traditional means of manual inspection to control the threads of stud sockets.

During the last years RFNC-VNIIEF has carried out investigations on the EC method. The results have confirmed the EC method can be used to detect defects in the threaded sockets along the length of helical line of the thread and to indicate the defects character, their coordinates and location. The project intends to create a prototype for an industrial automated EC inspection system. This system will make it possible to solve the problem of efficient inspection of M170 stud socket threads on the VVER-1000 reactor case. Furthermore, the automated EC inspection system could be used as a prototype for a series of devices intended for control of stud sockets with different thread dimensions. The project will be implemented by RFNC – VNIIEF and Balakovskaya NPP. Scientists and engineers from both institutions have the necessary qualifications to perform the work and the necessary equipment is available at the two institutes. The specialists of RFNC-VNIIEF are highly qualified. They have confirmed their technical competence during the development and batch production of six types of eddy current probes (ECP) that are the components of vibration sensors used at the Fuel and Energy Complex. They were granted four patents for the sensors.The specialists of Balakovskaya NPP have extensive experience in inspection of metal component integrity of power units. The accumulated experience will contribute greatly for the development and testing of the automated EC inspection system.

The tasks of the project will be fulfilled by former weapons scientists and engineers of RFNC-VNIIEF who possesses knowledge and skills related to weapons of mass destruction. The implementation of the project will provide the opportunities to redirect their talents to peaceful activities, namely, solving the tasks on NPP operational safety and to promote integration of the scientists into the international scientific community.

The following tasks are to be fulfilled under the project, namely:

  1. Creation of a microprocessor EC device for detection of the defects.
  2. Creation of a manipulator to provide scanning of the socket thread and current data transfer
  3. Creation of software to control the inspection process, analysis and information storage.
  4. Assembly and adjustment of the whole automated EC inspection system.
  5. Testing of the automated EC inspection system in the laboratory and at Balakovskaya NPP.

The various tasks will be implemented by RFNC-VNIIEF and Balakovskaya NPP. RFNC-VNIIEF will develop and fabricate the automated EC inspection system as well as carrying out laboratory testing. Balakovskaya NPP will develop the initial data and will also participate in the laboratory testing at RFNC-VNIIEF-facilities. After laboratory testing of the EC inspection system the specialists of RFNC-VNIIEF and Balakovskaya NPP will assess if the EC inspection system is ready or what improvements are necessary. Then it will be finally tested at an operating power unit.

The contributions of the foreign collaborators to the project will be: information exchange & advice in the course of the project implementation; review of technical reports on the project, testing and assessment of the equipment developed under the project, and participation in technical inspection of the project activities.


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