Power valves are installed on almost all the pipelines of nuclear power plants performing the functions of regulation and shutting off the flow, so its failure often leads to emergencies. A particularly large number of failures is observed in motor-operated valves. Incorrect setting of the limiting clutch leads either to incomplete closure of the valve or to rod failure. Therefore, the valves are equipment of a nuclear power plant, which often falls into repair shops. Failures leading to an increase of valve leakage are especially dangerous for nuclear power plants. In this case, leakage of high-pressure valves leads to erosion of the sealing surfaces, which only increases the leakage. Thus, it is very important to determine the optimum rotational value when the valve is closed. The lack of conditions for closure force in the standards for valve leakage complicates the issue. A bench that allows working in the air with a pressure up to 3.5 MPa was developed on valve rod to study dependence of valve leakage on the rotational moment. Four independent parameters were measured: air pressure in front of the valve under study, closure force of the valve, volume of air loss through the valve and leakage time. A standard stop valve with a nominal diameter of 15 mm and a nominal pressure of 64 atm was used for the study. The determined dependence of the leakage on torque value allows recommending a gentler mode of valve closure without significantly reducing its tightness. As a result of experimental data processing, a criterial equation is obtained linking a leakage rate, pressure drop on the valve and a rotational moment value. The received criterial equation will allow defining the compromise between valve closure force and permissible leak level according to regulatory requirements. The analysis of the “leakage/rotational moment” diagram showed the possibility to reveal the damaged valves. This possibility may be used during the incoming inspection of the valves supplied to NPP, which should significantly improve the reliability of their operation.
енергетичної арматури і її вхідний контроль. Енергетична арматура займає ключове місце в питаннях надійності енергообладнання АЕС. Арматура встановлена на трубопроводах, що пов'язують практично все основне і допоміжне обладнання електростанції, крім цього, арматура широко поширена на електростанціях. Аналіз ситуації показує, що передумови виходу з ладу арматури можна розділити на чотири групи Представлена таблиця основних несправностей та пошкоджень арматури за результатами аналізу даних ремонтних цехів АЕС. Показано, що основні проблеми арматури зав'язані на два фактори: старіння і знос арматури, тобто проблеми її експлуатації і помилки конструкції і виготовлення, що представляють вже заводські причини. Вхідний контроль арматури на АЕС носить в основному документальний характер, тобто виконується перевірка комплектності документації та деталировки обладнання. Також проводять огляд устаткування на предмет видимих пошкоджень. Ремонтні і монтажні організації також не проводять спеціальних тестів для арматури, спираючись на довіру до заводу-виробника. Пропонується реалізувати на електростанціях методику вибіркового вхідного контролю арматури. Пропонований вид вхідного контролю пов'язує практично всі основні параметри арматуриїї умовний діаметр, тиск на вході при гарантованому закриття арматури, допустимий пропуск середовища і номінальний крутний момент. Результати експериментальних досліджень, проведені на реальній арматурі, показали ефективність такого методу контролю, який дозволяє не тільки встановити рівень пропуску арматури, а й визначити необхідне зусилля закриття арматури електроприводом. Крім цього, такий метод контролю дозволяє виявити непрацездатну арматуру, чого не можна зробити візуальним контролем. Такий контроль дозволить виявляти не тільки помилки конструкції, але і розбіжність витратних характеристик однотипної арматури і пропуск арматури при її регламентному закриття. Ключові слова: енергетична арматура, несправність арматури, вхідний контроль, експериментальне дослідження P. Pavlyshyn. Damage to power valves and their input control. Energy valves occupy a key place in the reliability of NPP power equipment. The valves are installed on the pipelines connecting practically all main and auxiliary equipment of the power plant, besides, the valves are widely spread in power plants. The analysis of the situation shows that the prerequisites for the failure of the valves can be divided into four groups. The table of the main faults and damages of valves according to the results of analysis of data of NPP repair shops is presented. It is shown that the main problems of the valve are tied to two factors: aging and wear of the valve, i.e. problems of its operation and errors in design and manufacture, which are already factory reasons. Input control of valves at NPPs is mainly of documentary nature, i.e. check of completeness of documentation and equipment details. The equipment is also inspected for visible damage. Repair and installation companies also do not carry out special tests for the valves, relying...
The reliability and trouble-free operation of nuclear power plants is due to the reliability of the pipeline systems connecting the main and auxiliary equipment. The main elements of such systems are power valves, the reliable operation of which largely determines the reliability of the NPP as a whole. At the same time, one of the problems that reduce the service life of the reinforcement is the erosive wear of its main elements. The article is devoted to the development and experimental research of reinforcement with increased resistance to erosion wear. The problems associated with the operation of valves and the relevance of the raised problem are shown. It should be noted that the study of such a valve is performed for the first time. A feature of the valve design is that the medium, passing through the regulator, does not leave the valve, but enters the porous filling, where the flow rate and associated noise are effectively damped. The article presents an experimental design of such a valve and describes an experimental stand for its research, gives a description of research methods. To study the flow in the porous layer, 12 sensors were used, inserted into the layer. Fractional polyethylene was used as a porous backfill, therefore the experiment was carried out at low pressures and normal temperatures. As a result of the experiment, the pressure distribution in the porous layer was obtained depending on the degree of valve opening and the increase in flow through it. Nonlinear dependences are obtained at average flow rates and linear at maximum and minimum flow rates. It has been established that in such reinforcement the section with a high velocity of the medium will be in a porous backfill. The study of the hydraulic characteristic showed that this characteristic has near linear character, similar for flows in porous media.
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