NPP resource management department
VNIIAES is the scientific director of the Rosenergoatom Joint-Stock Company’s nuclear power plants operation. Therefore, we consider each problem in the context of all stages of the NPP life cycle. VNIIAES is also the leading material science organization of the nuclear industry. The Institute issues recommendations on the selection of materials, non-destructive testing, certification of measuring instruments for testing, and problematic nodes durability justification.
These activities are reflected in the operation of the NPP resource management department.
The word ‘resource’ is the key in the name of our department. Resource management is primarily aimed at ensuring long-term and safe operation, increasing the efficiency of the existing and newly designed nuclear power plants. Currently, the issues of determining the technical condition and justification of the residual resource are of particular relevance in connection with the extension of the power blocks’ life span, which is actively conducted in our country and abroad.
Metal and concrete
Resource management involves several key tasks. The first of them is the assessment of the technical condition and integrity control of the power block elements, and it is handled by the non-destructive testing and resource department. Certified specialists are working here, performing non-destructive testing of metal in the power block elements.
This work is carried out both at the operational control stage together with other contracting organizations as well as when performing additional control while extending the power blocks’ life span.
The second resource-related aspect is justification of different facility elements’ durability. The strength of pipelines and equipment is the most important parameter, which should ensure the operation of the structure under normal conditions, malfunctions and emergency situations. There is a unit in the department responsible for the strength analysis of nuclear power plant elements with various types of reactor facilities with VVER, RBMK, EGP, BN.
In each of these areas, department employees have developed a large amount of regulatory documentation.
Two major areas of our operation are closely related with the life span extension.
The first one is metal control and justification of different pipeline equipment elements’ durability.
The second is the extension of the service life, buildings and structures resources. We have a specialized certified laboratory for non-destructive testing of defects, mechanical properties of metal and reinforced concrete structures. With regard to destructive testing methods for both metal and concrete, VNIIAES cooperates with leading organizations of the industry and the country that have the appropriate testing equipment. Unfortunately, due to the very nature of our Institute, we can only work with portable mobile devices that can be placed in our laboratory and used at nuclear power plants; we do not have large testing machines.
VNIIAES’ work on extending the resource of buildings and structures is primarily carried out jointly with the chief designer, the ASE engineering company. Such specialized structures as the containment of the VVER-1000 reactor are complex, especially the critical structures of nuclear power plants. Many factors affect their bearing capacity and working condition; various specialized certified software products are required here, allowing a wide range of types of calculations to be performed. All this requires close work with the designer of the structure. Such cooperation pays off: to date, the operation life of six containments has been extended at nuclear power plants with VVER-1000 reactors, and five of them have been completed by VNIIIAES in cooperation with ASE IC.
In recent years, VNIIAES has done a great job of extending the life of thermomechanical equipment outside the loop of a reactor plant with VVER and RBMK (within the reactor plant, projects are implemented by the chief designer of the reactor with VVER - OKB Gidropress, with RBMK - NIKIET). VNIIAES acted as the general contractor during the life span extension of the Balakovo NPP’s 1st, 2nd and 3rd power blocks (outside the reactor facility) and the Smolensk NPP’s 3rd power block. The Institute was a pioneer in re-extending the Novovoronezh NPP’s 4th power block’s life span. To forecast the properties of the base metal and welded joints of equipment and pipelines, a special material science program was created and implemented. Some work has been done at the Kalinin, Kursk, and Leningrad NPPs to extend the life of thermomechanical equipment, buildings and structures. The department also specializes in developing resource management programs for nuclear power plant elements and standard programs for the pre-operational and operational control of metal equipment and pipelines of nuclear power plants with various types of reactor facilities.
The next important area for our department is scientific and technical support for nuclear power plants maintenance. Scientific and technical support for maintenance and repair department specializes in the development of regulatory and technical maintenance documentation and support this documentation throughout the process. Another significant part of the department’s operation, which is facilitated by the contractual obligations with the Company, is the examination of maintenance documentation for new and existing power blocks’ equipment. The department maintains a portal of maintenance documentation data at the Rosenergoatom Joint-Stock Company’s website.
The department’s specialists are developing various promising methods for diagnosing equipment during repairs, primarily visual, endoscopic monitoring associated with the examination of the turbine flow path. For many years, scientific and practical guidance has been carried out on special work to prevent cracking of welded joints in pipelines of Du-300 nuclear power plants with RBMK (using the technology of preventive compression of a welded joint). Examination of imported materials of NPP elements is carried out for their compliance with the requirements of Russian regulatory documentation.
The concept of maintenance and repair of nuclear power plants elements according to their technical condition has been developed and approved by the Rosenergoatom Joint-Stock Company; the transition to it today is the goal for the whole industry.
With VNIIAES being the leading material science organization, the specialists of the NPP resource management department recently completed important work, which lasted almost a year. Unique units of automated non-destructive remote control of primary equipment purchased in Croatia were delivered to power blocks at VVER-1200 NPPs, which were commissioned and put into operation at the Novovoronezh NPP (power blocks No. 6 and 7) and the Leningrad NPP (power blocks No. 1 and 2).
The certification conducted by VNIIAES made it possible for the first time to use these systems for automated non-destructive testing of reactor facility metal at the Novovoronezh NPP’s 6th power block during the scheduled maintenance in 2019.
Another unit, the Department of Diagnostics, works on the diagnosis of equipment items, pipelines and buildings, structures. In 2012, an industry-specific diagnostic system (IDS) was created, which is now operated by this department.
What is an industry-specific diagnostic system? This is a high-speed channel for obtaining information from standard diagnostic systems, primarily elements of a reactor faclity. The Kalinin and Smolensk NPPs’ power blocks are connected to the industry-specific system.
The IDS can be used to evaluate the actual state and trends in the equipment capacity changes. Having identified diagnostic signs of each particular condition, together with manufacturers and chief designers, we can give recommendations on preventing disturbances in the facility’s operation, operating modes, maintenance and equipment repair.
In addition to the operation of an industry-specific diagnostic system, our specialists participate in works related to the use of portable mobile instrumentation systems for the operational diagnostics of various equipment during scheduled preventive maintenance at nuclear power plants.
The Department has done a lot of work on the implementation of the containment pre-tension control system and the tension of armored ropes at the Leningrad NPP-2 1st power block. During the creation of the system, several hundred information-measuring channels and sensors were connected and certified; special computer software was developed to present the monitoring results in interactive graphical and tabular forms. Similar work is now being carried out at the Leningrad NPP-2 2nd power block with a VVER-1200 reactor.
Another division is the reliability department. In many aspects, its work is adjacent to that carried out by the Department of Non-Destructive Testing and Resource. The department carries out additional work to facilitate the resource (given that we evaluate the strength of the structure both with deterministic and with probabilistic calculation methods). The goal is to evaluate the reliability of an object, to see if there is a change in reliability for the worse after changing operating conditions, after long periods of use; to determine the most problematic zones, areas in which any negative phenomena are most likely to occur using the calculations.
The department maintains the information analytical system (IAS) of operational non-destructive testing of nuclear power plants’ metal elements. This is another system by the Rosenergoatom Joint-Stock Company in addition to the IDS - in fact, this is a gigantic database that accumulates the results of all non-destructive testing that is carried out at nuclear power plants; the Balakovo, Kalinin, Rostov, Kola NPPs are connected to the IAS. Using this system, we can quickly assess the technical condition of the equipment; determine whether the properties of materials are degrading and, accordingly, whether there is a threat of the object’s operability loss. We must use this database to do analytical work - to conduct a quick analysis of the defect causes, and if possible, to evaluate the strength and reliability of equipment and pipelines.
The department also carries out work related to the concept of “leak before destruction’ applicable to pipelines. Special events were held both in Russia and in Slovakia, at the Mochovce NPP.
All departments and departments functionally cooperate with each other. And in one of the areas of such cooperation - the interaction of the reliability department with the non-destructive testing and resource department - a joint participation from VNIIIAES in a special R&D project is planned. Following the instructions of the Rosenergoatom Joint-Stock Company and the ASE IC as the customer, this is the first time when it is planned to develop a digital automated system for managing the resource (aging) of NPP elements in accordance with the requirements of NP-096-15 “Requirements for resource management equipment and pipelines of nuclear plants" together with leading industry organizations.