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[en] The safeguarding of a nuclear reactor during the operation process is one of the most significant tasks. The difficulty is in the necessity to use nondestructive methods. One of such perspective methods is the neutron noise diagnostics of a nuclear reactor. Possibility of the noise diagnostics by the new method of norms of positive definite Toeplitz correlation matrices is studied. The advantage of this method is its purely mathematical nature; no model of the process is employed. The neutron noise analysis of the IBR-2M pulse energy has been carried out by the represented method. Both the static state and dynamic state of the reactor have been studied. Frequency analysis of unstable components of the reactor noise has been carried out. The main unstable components of the neutron noise are frequencies of 0.8 and 1.6 Hz, which are conditional on the vibration of the movable reflector blades of the reactivity modulator. The results of this diagnostics have been compared with the results of the classical spectral analysis.
[ru]Рассматривается возможность шумовой диагностики ядерного реактора с помощью нового метода норм положительно определенных корреляционных матриц Тплица. Преимуществом этого метода является его чисто математический характер - не используется модель процесса. С помощью предложенного метода проведен анализ нейтронных шумов энергии импульсов ИБР-2М в различных состояниях реактора: как в статически стабильных при разных уровнях мощности, так и в переходных состояниях изменения мощности. Показано, что основные нестабильные компоненты нейтронного шума приходятся на частоты 0,8 и 1,6 Гц, обусловленные колебаниями лопастей подвижных отражателей модулятора реактивности. Полученные результаты сравниваются с результатами классического спектрального анализа.
[en] In the report the following basic themes are stated: general description, main characteristics and current state of the reactor. Also the realization of the IBR-2 reactor modernization program and its main directions, terms, results, financing, postnatal modernization IBR-2 parameters are given
[en] Axions were sought at the IBR-2 pulsed reactor by means of plastic scintillation counters with a total scintillator volume of 139 liters. The upper limit obtained for the counting rate is at least a factor 1300 less than the value predicted by the theory of a standard axion in the mass range m/sub a/<2m/sub e/
[en] A new neutron radiography and tomography facility at a modernized high flux pulsed reactor IBR-2 has been developed. The neutron beam with dimension 20×20 cm is formed by a collimator system, where characteristic L/D ratio can vary from 200 to 2000. The detector system is based on a scintillator screen "6LiF/ZnS with image registration by means of the high-resolution high-sensitive CCD camera. The first results of a radiography and tomography experiments obtained by means of a new experimental facility are presented.
[en] In the designed pulsed mode of operation of the IBR-2 reactor the reactivity effects of two types of movable reflectors (MR) have been evaluated by the dynamic method. For this purpose, the shape of the IBR-2 power pulse for the fast neutrons and the power between pulses (background power) as the time function have been measured (with good statistical accuracy). The peculiarity of the present dynamic evaluation of neutron-physical parameters is that it is obtained on the basis of the analysis of the designed pulsed mode of the reactor operation. Up to now, the MR parameter evaluations were performed when the pulsed reactor had been put into the stationary (not pulsed) subcritical mode of operation when some fast processes influencing the power pulse shape could not be defined. The dynamic method allows one to obtain a detailed description of the reactivity change at the MR revolving. In this case numerical values of the MR reactivity effects are defined with high accuracy. It is important to note that successful use of the dynamic method to estimate reactivity effects of the movable reflectors is possible only when the power pulse shape is measured in the total dynamic range of neutron flux change, i.e. from the pulse maximum to the background level between pulses. For the IBR-2 reactor this range for the fast neutrons is equal to 104
[en] An overview of the main scientific areas of condensed matter research, which are extended with the use of the IBR-2 high-flux research reactor, is presented. It is demonstrated that the spectrometer facility of the upgraded reactor has great potential for studying the structural, magnetic, and dynamical properties of novel functional materials and nanobiosystems, which ensures the leading position of the Joint Institute for Nuclear Research in neutron research of condensed matter for the long-term prospect.
[en] On the basis of the program system MATLAB the nonlinear dynamics model of the IBR-2M pulsed reactor which links values of variables at discrete moments (at moments of appearance of power pulses) is established. The testing by means of modeling calculated processes in the IBR-2M shows the correctness of the model. A preliminary estimate of the transfer coefficient of the linear part of the automatic regulator is obtained.
[en] Full text: For the modernized IBR-2 reactor there are two main reasons causing fluctuations of energy of impulses [1,3] on low power of stochastic fluctuations, on the nominal - giving rise to fluctuations of external reactance. The fluctuations of pulse energy is quite significant (20%). They affect the dynamics of the reactor, the process of regulation, starting, as well as the work of the experimental apparatus, etc. It is clear that research of fluctuation of energy of impulses has special value for the IBR-2 type reactor. Sufficient information about the statistical properties of the reactor noise gives the density distribution of the energy pulse power. We used the usual procedure of statistical analysis of time series. Calculated pulse energy of density and the parameters of this distribution.