The article presents a method for obtaining an analytical expression for the criterion of stability of a VVER-1000 (1200) reactor with respect to xenon oscillations of the local power in the core, containing an explicit dependence of the criterion ratio coefficients on the arbitrary axial neutron field distribution in steady states of the core. Based on the data of numerical experiments using a full-scale model of the Kalinin NPP power units, the authors present the results of checking the validity of this expression for the reactor stability criterion with respect to xenon oscillations for different NPPs with VVER-1000 (1200) reactors.
Аннотация. В работе представлены результаты исследований физических явлений, определяющих параметры ксеноновых колебаний. В том числе уточнена зависимость нейтрон-но-физических характеристик активной зоны ВВЭР-1000 (1200) от температурного распределения в топливе и его влияния на параметры ксеноновых процессов в зоне. Разработан усовершенствованный метод расчета резонансного поглощения в 238 UO2 (эффект доплеровской реактивности) с неоднородным температурным профилем. Результаты расчета параметров ксеноновых колебаний были рассчитаны с помощью комплексной программы PROSTOR. Валидность усовершенствованного метода была проверена путем сравнения рассчитанных параметров ксенона с результатами измерений, полученными при пусконаладочных испытаниях энергоблоков реактора ВВЭР-1000. Результаты показали более точный расчет резонансного поглощения в 238 UO2, они значительно уменьшают стабилизацию уширения эффекта Доплера, следовательно, эти факты имеют жизненно важное значение в случае работы реактора в маневренных режимах, сопровождающегося ксеноновыми процессами в активной зоне. Усовершенствованный способ внедрен в компьютерное программное обеспечение Полномасштабного тренажера 3-го энергоблока Ростовской АЭС и полномасштабного тренажера 4-го энергоблока Калининской АЭС. Метод был опробован в ходе приемо-сдаточных испытаний этих полномасштабных тренажеров.
This paper presents the results of numerical studies of various algorithms for suppression of xenon offset and power distribution oscillations in the core of a VVER-1200 reactor. The purpose of the research is to select an algorithm that minimizes the amount of liquid radioactive wastes during water exchange in the primary circuit of a nuclear power plant. For this, several algorithms for xenon oscillations suppression were considered. The first algorithm considered was an algorithm for suppression of xenon oscillations, which uses regulation due to AWP only, without utilization of any additional regulation.
The second algorithm considered was an algorithm based on the use both AWP and boron regulation. In this algorithm suppression of xenon oscillations was carried out with the help of accelerated initiation of the work of the AWP by changing the boric acid concentration with constant second circuit pressure of the NPP and by utilization of the second control rods group.
Last algorithm considered was algorithm based on the use of temperature control for accelerated initiation of the work of the AWP. In this algorithm, xenon oscillations suppression was carried out by changing coolant temperature at the reactor inlet caused by pressure change in the secondary circuit in the normal operation margins, and by involving the second group of control rods.
It was shown that the best way to suppress xenon offset and power distribution oscillations in terms of minimization of radioactive liquid wastes amount is the algorithm with accelerated initiation of the AWP due to temperature regulation, with elimination of temperature regulation after minimizing of current axial offset value deviation from the nominal one.
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