Table of Contents

&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Foreword<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Introduction<br>1 Scope<br>2 Definitions<br>3 Principles of Internal Structure Monitoring<br>4 System Requirements<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.1 Use of Neutron Noise<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.1.1 Nuclear Instrumentation<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.1.2 Sampling and Conditioning of the Signal<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.2 Use of Vessel Vibration Signals<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.2.1 Instrumentation<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.2.2 Signal Conditioning<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.3 Use of the Signals of a Multi-Sensor System<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.3.1 In General<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.3.2 Typical Multi-Sensor System<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.3.3 Instrumentation Characteristics<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.3.4 Signal Conditioning<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.4 Monitoring System<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.4.1 Monitoring Equipment<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.4.2 Monitoring Software<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.4.3 Spectral Acquisition Mode<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;4.4.4 Reactor Conditions<br>5 Monitoring Procedures<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.1.1 Theoretical Studies, which may be <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;confirmed by mock-up tests<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.1.2 Qualification during hot tests<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.1.3 Identification of movement at the time <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;of start-up<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.2 Monitoring Phase<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.2.1 First start-up of the reactor <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(30% power)<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.2.2 During the fuel cycle<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;5.3 Diagnosis Phase<br>6 Documentation<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.1 Initial entry into service<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.2 Monitoring<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;6.3 Diagnosis<br>Annex A (informative) Mathematical definition of the spectral<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;functions<br>Annex B (informative) Principle of measurement by ex-core<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;neutron detectors<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;B.1 - Principle of transmission of vibrations of <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;internals to ex-core detectors<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;B.2 - Measurement by ex-core detectors of displacement <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;of internal structures<br>Annex C (informative) Principle criteria for detection and<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;monitoring internals by absolute <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;displacement sensors outside the vessel<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(typical example)<br>Annex D (informative) Bibliography<br>Figure 1 - Diagram of internals and instrumentation<br>Figure 2 - Arrangement of ex-core neutron detectors<br>Figure 3 - Typical modal shapes on beam modes of fuel <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;assemblies and core barrel<br>Figure 4 - Typical modal shapes on the shell modes of a <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;cylindrical thermal shield<br>Figure 5 - Example of change in core barrel vibratory <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;signatures in the case of degradation of the <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;hold-down spring (results obtained on a mock-up)<br>Figure 6 - Example of change in ex-core neutron noise <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;signatures following a very slight relaxation of <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;the hold-down spring (results obtained on a <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;reactor)<br>Figure 7 - Principle of detection of core barrel pendular <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;motion using ex-core neutron noise<br>Figure 8 - Example of detection of internals vibratory modes <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;on ex-core neutron signatures<br>Figure 9 - Example of detection of swinging of internals <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;using a vibration sensor outside the vessel<br>Figure 10 - Monitoring of the upper core support by vertical <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;absolute vessel vibrations (coherence A1/A3)<br>Figure 11 - Monitoring of the horizontal flow skirt vibration<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;(1st beam mode) by vertical absolute vessel <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;vibrations (coherence A2/A4)<br>Figure 12 - Location of ex-core neutron detectors on <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;VVER-type reactors<br>Figure 13 - Example of sampling of neutron noise<br>Figure 14 - Typical multi-sensor system for vibration <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;monitoring in a four-loop PWR (see [2])<br>Figure 15 - Example of processing of a NPSD by the monitoring<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;system<br>Figure 16 - Example of processing of coherence-phase functions<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;by the monitoring system<br>Figure C.1 - Comparison of directly/indirectly measured <br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;internal resonance

Abstract

Deals with monitoring systems for vibratory behaviour of internal structures of pressurized water reactors (thermal shield, upper and lower core support, core barrel, etc) as well as fuel assemblies on the basis of neutron fluctuations seen outside the vessel and its vibrations. The aim of monitoring outlined is to detect degradation of internal structures.

General Product Information

Published
Document Type	Standard
Status	Current
Publisher	International Electrotechnical Committee
Pages
ISBN
Committee	TC 45