No abstract available

No abstract available

[en] The method is suitable for the diagnostics of mechanical vibrations of reactor internals and the indication of boiling in pressurized water reactors. Using the method it is possible to determine the immediate state of the equipment. A model is described of neutron noise in the reactor. Detectors outside and inside the core are used for recording the neutron flux. (M.D.)

[en] By statistical evaluation of the fluctuation component of signals from selected detectors, noise diagnostics detects conditions of equipment which might later result in failure. The objective of early diagnostics is to detect the failed integrity of primary circuit components, failed detectors or anomalies of the thermohydraulic process. The commonest method of experimental data analysis is spectral analysis in the frequency range 0 to 50 Hz. Recently, expert diagnostic systems have been built based on artificial intelligence systems. Czechoslovakia participates in the experimental research of noise diagnostics in the context of the development of diagnostic assemblies for WWER-440 reactors. (M.D.)

[en] The proceedings contain the texts of 24 papers all of which fall under the INIS Subject Scope. The main purpose of the meeting of more than 90 scientists and specialists from 18 countries was for them to get acquainted with the current state and prospective development of noise diagnostics application in nuclear reactor operation. (Z.M.)

[en] Vibration of the core barrel is least desirable for safe operation of the PWR reactor. These mechanical vibrations are in correlation with the fluctuations of neutron flux density whose time and frequency analysis serves failure diagnosis. The mathematical model is described of the transfer of mechanical vibrations of the core barrel to neutron noise. Other steps are indicated indispensable for the application of the method of neutron noise analysis for in-service diagnostics of nuclear power plants. (Z.M.)

[en] A first draft of the standard ''Nuclear safety guidelines for reactor facilities in nuclear power plants'' was prepared within the standardization activity of the international economic association Interatomehnergo. The draft is now being submitted for comments while a second draft is being prepared. The standard is derived from the NUSS IAEA series and formally, it is divided into six chapters, viz.: general guidelines; technical requirements for securing nuclear safety; requirements for nuclear safety justification; requirements for securing nuclear safety of reactor installation during operation; checking the observance of guidelines and responsibility for violations; basic definitions. The standard is especially advanced as concerns technical requirements for securing nuclear safety. (Z.M.). 4 refs

[en] The definition of reactor operational diagnostics is presented and the fundamental trends of research are determined. The possible sources of power reactor malfunctions, the methods of defect detection, the data evaluation and the analysis of the results are discussed in detail. In view of scarcity of a theoretical basis and of insufficient in-core instrumentation, operational diagnostics cannot be as yet incorporated in a computer-aided reactor control system. (author)

[en] A model is briefly described of a single-point approximation and a space-dependent model of neutron noise. Using a relation for the signal of a detector placed outside the reactor, consisting of the noise contribution of the core and of noise due to changes in the medium between the core and the detector, it is shown that the neutron noise analysis method can be used for identifying not only the basic shapes of oscillations of the reactor internals but also the shell shapes of oscillations of components. The method is also suited to the diagnostics of boiling manifested in the high-frequency part of the spectrum. (Ha)

[en] The use of noise diagnostics is described in the early detection of failures in the operation of a nuclear power plant. Reactor noise is classified by noise source and noise carrier. Noise analysis is used for early diagnosis of failures of the integrity of components of the primary circuit, the failure of detectors, the incorrect function of cable routes and anomalies in the thermohydraulic process. The method is based on processing the stochastic signal which is usable for the interpretation of various phenomena. Most frequently aplied is neutron noise diagnostics (frequency range 0 - 50 Hz) using standard instrumentation without disturbing the operation of the reactor core by installing additional instruments. In-pile detectors of neutron flux density serve the detection of anomalies in coolant flow, of dangerous vibrations of fuel and regulating assemblies, and of local boiling. The results of the measurement of neutron noise carried out in pressurized water reactors are generalized. (J.C.)