More stringent requirements for VVÉR-1500 reactors have made it necessary to introduce innovative solutions into the construction of the core and reactor system. At the same time, succession, i.e., the maximum possible use of tested solutions in developing the VVÉR-1500 reactor, decreases the costs and the time required for development, fabrication, and adoption and most importantly it improves reliability and safety. Tested and new solutions for the VVÉR-1500 core relative to the VVÉR-1500 protoype and possible further upgrading are examined.An important problem in recent years is the development of nuclear power plants with VVÉR-1500 reactors. This problem is dictated by the desire to develop, on the basis of the great achievements of modern technology and industry, a competitive nuclear power plant and to maintain our country's leading position in the nuclear power industry in the world. The new and more stringent requirements make it necessary to introduce innovative solutions into the construction of the core and the reactor system. At the same time, succession, i.e., the maximum possible use of tested solutions in developing a VVÉR-1500 core, will decrease the development costs and time and the manufacturing costs, and most importantly it will improve the reliability and increase safety.Special Features of the VVÉR-1500 Core. An increase in the power of a nuclear power plant with a VVÉR-1500 reactor and an increase in the run time to obtain an installed capacity utilization factor of at least 90% are achieved by increasing the number of fuel assemblies from 163 to 241 (Fig. 1) and loading fuel in fuel assemblies (Fig. 2). The fuel is increased, first and foremost, by increasing the length of a fuel column as much as possible -by 700 mm relative to the prototype. Other ways could also be used in the future -eliminating the central opening and increasing the outer diameter of a fuel pellet.The limited height of the reactor, the required height of a fuel column, and the need to maintain a gas compensation volume in the fuel elements have made it necessary to decrease substantially the height of the head and tail of the fuel assembly (Fig. 3). Consequently, to accelerate the smoothing of the velocity field at the entrance into a fuel assembly the support edges in the tail are oriented in a radial direction. The tail together with the bottom support lattice consists of a rigid truss structure, capable of preventing damage to the fuel-element supports under the highest compressive and tensile loads. Such a construction of a fuel-assembly tail made it possible to implement another new solution -to extend the zirconium guiding channels beyond the bottom support lattice and secure the end piece in the support ribs of the tail. Thus, it became possible to combine the bottom ends of the fuel in the fuel assembly and the absorber.The more stringent safety requirements made it necessary to increase in the VVÉR-1500 design the number of absorbing rods -up to 118; each rod contains 24 absorbing elements. This change made ...
Many technical problems must be solved in order to adopt advanced fuel cycles at nuclear power plants with VVÉR-1000 reactors. The TVS-2 structure was initially developed in the process of solving these problems; it gave high technical performance and cost-effectiveness and provided a base for subsequent upgrading. The TVS-2M structure with a larger fuel load was developed on the basis of tested and new technological solutions to maximize fuel utilization in VVÉR-1000 reactors.The industry program "Efficient use of fuel in nuclear power plants in the period 2002-2005 and in the future up to 2010" provides for the adoption at the Balakov nuclear power plant of fuel cycles which give a higher ICUF (Installed Capacity Utilization Factor). The first steps for reaching this goal were the development and adoption of fuel assemblies with a rigid framework -second-generation fuel assemblies, called TVS-2. It is designed for a four-year fuel cycle and 3 × 350 eff. days with burnup 55 MW·days/kg. The predicted buckling of the axis of a fuel assembly over the operating period does not exceed 5 mm.TVS-2 has the following basic structural solutions as compared with the currently used improved fuel assemblies: • a rigid welded framework (spacing lattices welded to guiding channels) to ensure resistance to bending and torsional loads was formed;• the alloy É-635 was used to fabricate the guiding channels and the central channel in order to increase the mechanical properties and the geometric stability during prolonged operation;• the bending stiffness of the spacing lattices was increased (the height of the cells was increased to 30 mm and the thickness of the tube walls of the cells was increased to 0.3 mm) to eliminate shape losses resulting from temperature and radiation induced elongation;• the cell geometry of the spacing lattices was optimized to ensure optimal forces for movement of the fuel elements in the cells; this decreased the thermomechanical loads on the elements of a fuel-element bundle while preserving their resistance to fretting-wear during operation;• the transverse stiffness of the head was increased (a guiding shell was introduced) to increase the stability and decrease the friction in its components;• the "wrench" size was increased to limit the maximum buckling in the core during operation; • the number and arrangement of spacing lattices along the height of a fuel-element bundle was optimized to decrease the metal contents, production labor, and provide the required hydraulic characteristics;• a bottom lattice with a centrosymmetric overflow opening was introduced to improve the flow hydrodynamics at the entrance into a fuel-element bundle; such a lattice is stronger without any decrease of the flow section for the coolant;• connecting pipes for temperature control were placed in the head to increase the representativeness of the regular temperature monitoring at the exit from a fuel assembly.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.