GB/T 13625-2018Seismic qualification of safety class electrical equipment for nuclear power plants (English PDF)

Foreword

This standard was drafted in accordance with the rules given in GB/T 1.1-2009. This standard replaces GB/T 13625-1992 "Non-seismic appraisal of electrical equipment for safety systems of nuclear power plants", and GB/T 13625-1992 The main technical changes are as follows:

--- Added damping related content (see Chapter 6 and Appendix A);

--- Revised the requirements of the TRS low frequency band so that the low frequency displacement of the test device will not be too large (see 8.6.3.2);

--- Increased the relevant content of the power spectral density envelope (see 8.6.3.2.1);

--- Increased seismic identification methods combined with analysis and testing (see Chapter 9);

--- Added guidelines for seismic identification through reference equipment seismic data (see Appendix G). This standard was proposed by China National Nuclear Corporation. This standard is under the jurisdiction of the National Nuclear Instrumentation Standardization Technical Committee (SAC/TC30). This standard was drafted. Shanghai Nuclear Engineering Research and Design Institute. The main drafters of this standard. Ma Yuanrui, Liu Gang, Xie Yongcheng, Yang Ren'an, Bi Daowei. The previous versions of the standards replaced by this standard are.

---GB/T 13625-1992. Seismic identification of safety grade electrical equipment in nuclear power plants

1 Scope

GB/T 13625-2018 is the Chinese national standard on seismic qualification of safety class electrical equipment for nuclear power plants, in the field of energy and heat transfer engineering. The /T suffix marks it as a recommended standard: it is not compulsory by itself, but it becomes binding as soon as a contract, a tender or a customer specification calls it up - which in practice is how most foreign buyers meet it. It was issued on 14 May 2018 by the State Administration for Market Regulation; Standardization Administration of China, and has been in force since 1 December 2018. Classification: ICS 27.120.10, CCS F65. This page is published from the official record of the standard held by the Chinese standards administration: the identification, the dates, the classification and the issuing body are taken from there. The clause text, the tables and the numeric limits are in the document itself, which is delivered complete in English translation.

This standard specifies the resistance to verify that safety-grade electrical equipment can perform its safety functions during and/or after an earthquake. Implementation methods for seismic identification and their documentation requirements. This standard applies to seismic identification of safety grade electrical equipment in nuclear power plants, including the adverse effects of failure on the performance of safety systems. Any interface component or device.

2 Normative references

The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this article. Pieces. For undated references, the latest edition (including all amendments) applies to this document.

GB/T 12727 Nuclear power plant safety grade electrical equipment identification

3 Terms and definitions

The following terms and definitions apply to this document.

3.1 Broadband response spectrum broadbandresponsespectrum A reaction spectrum that produces an amplification reaction motion over a wide frequency range is described.

3.2 Coherence function Characterize the relationship between the two time periods in the frequency domain. The coherence function gives the statistical correlation between the two motions as a function of frequency. The values range from 0 to 1.0, with a completely uncorrelated motion of 0 and a fully correlated motion of 1.0.

3.3 Correlation coefficient function correlationcoefficientfunction Characterize the relationship between two time periods in the time domain. The correlation coefficient function gives the statistical correlation between the two motions, which is a time delay. A function that is late as an argument. The values range from 0 to 1.0, with a completely uncorrelated motion of 0 and a fully correlated motion of 1.0.

3.4 Key seismic characteristics criticalseismiccharacteristics The ability to ensure that the equipment performs the required design, material and performance characteristics under seismic loading.

3.5 Cutoff frequency cutofffrequency The frequency at which the zero-cycle acceleration asymptote begins at the response spectrum. The frequency of a single-degree-of-freedom oscillator will no longer be amplified after exceeding this frequency. Into motion, this is the upper frequency limit of the waveform being analyzed.

3.6 Damping damping An energy dissipation mechanism that reduces the amount of amplification and broadens the vibration response in the resonance region. Damping is usually in percent of critical damping Said. Critical damping is defined as the minimum viscous damping value of a single-degree-of-freedom system that does not oscillate back to its original position after the initial disturbance.

3.7 Earthquake experience spectrum earthquakeexperiencespectrum; EES A response spectrum characterizing the seismic resistance of the reference device is determined based on seismic empirical data.

3.8 Flexible equipment flexibleequipment Equipment, structures, and components with a minimum resonant frequency that is less than the cutoff frequency of the reaction spectrum.

3.9 Range rule inclusion rules Determining the reference device group based on empirical data that has proven to be an acceptable range of physical characteristics, dynamic characteristics, and functionality of the seismic equipment rule.

3.10 Independent item independentitems Have different physical properties or withstand different seismic motion characteristics [eg different earthquakes, different sites, different structures, Or parts and equipment in different directions and/or positions of the same structure.

3.11 Narrowband response spectrum narrowbandresponsespectrum Describe a response spectrum that produces an amplification reaction in a finite (narrowband) frequency range.

3.12 Natural frequency When an object is deformed in a specific direction and then released, the object vibrates due to its own physical properties (mass and stiffness) Frequency of.

3.13 Running a baseline earthquake operatingbasisearthquake; OBE Combining regional and local geological and seismic conditions and the specific characteristics of local stratigraphic materials, it can be reasonable during the normal operating life of the power plant. An earthquake that is expected to occur at the site.

4 Introduction to seismic environment and equipment response

4.1 Earthquake environment The three-dimensional random ground motion generated by an earthquake can be characterized by simultaneous and statistically independent horizontal and vertical components. Although the whole An earthquake event may last for a long time, but its strong earthquake duration may be only 10s~15s. Ground motion is typical of wideband Machine motion may cause damage in the frequency range from

1 Hz to the response spectrum cutoff frequency.

4.2 Based equipment For equipment installed on a foundation, the vibration characteristics of ground motion (horizontal and vertical) may be amplified or attenuated. For any given Ground motion, amplification or attenuation depends on the natural frequency and damping dissipation mechanism of the system (soil, foundation and equipment). Most of the ground sports The broadband response spectrum is described to show that multi-frequency excitation plays a leading role.

4.3 Structural equipment Ground motion (horizontal and vertical) can produce amplified or attenuated narrowband motion in the structure due to the filtering of the associated structure. Structurally The dynamic response acceleration of the device will be further amplified or attenuated, up to several times or a fraction of the maximum ground acceleration. Depends on the damping and natural frequency of the device. A narrow-band response spectrum is usually used to describe the floor motion of the structure, indicating the components of the equipment Single frequency excitation plays a leading role. Similar filtering effects in the motion of the structure can also occur in flexible piping systems. For not supporting The final movement of the assembled components may be a single frequency dominated by the resonant frequency of the tube system (or its vicinity). This resonance condition will be installed in the pipeline The upper part produces the most demanding seismic loads.

5 Seismic identification method

5.1 Overview The seismic identification of the equipment shall demonstrate that the equipment performs its safety during and/or after the force generated by a safe shutdown earthquake. Functional capabilities. In addition, the equipment should withstand several operational baseline earthquakes before being subjected to a safe shutdown earthquake.

5.2 Seismic identification technical conditions Seismic identification requires clear specifications for the equipment to be certified. See Chapter 11 for details. The technical conditions for seismic requirements should be clearly defined to include at least. duration, frequency range and acceleration value. Providing these data information Can be.

a) a vibrational motion expressed in terms of power spectral density (a function of frequency);

b) the duration of the strong earthquake part of the earthquake;

c) the required response spectrum at the equipment installation point, the response spectrum must include data for the main horizontal and vertical axes, and different damping ratios Data (eg 2%, 5% and 7%);

d) The relationship between the maximum acceleration on the equipment installation point (floor or structure) and the important frequency or time history curve. For operational baseline seismic (OBE) and safe shutdown earthquakes (SSE), the shape and magnitude of the response spectrum may vary. Therefore, in order to The test pieces are identified and the acceleration spectrum corresponding to these seismic levels should be known. The technical conditions should state the rationality of the reaction spectrum used.

5.3 Common seismic identification methods There are usually four commonly used methods for seismic identification.

a) predicting device performance through analysis;

b) testing the equipment under simulated seismic conditions;

c) using a combination of testing and analysis to identify the equipment;

d) Identify the device by using empirical data. Each of the above methods, or other proven methods, is suitable for verifying the seismic performance of the equipment. Select the applicable identification method to There are a few factors to consider.

a) the type, size, shape and complexity of the equipment structure;

b) whether the security function is verified by (device) operability or only by structural integrity;

c) Reliability of the conclusion. The equipment being certified should be able to demonstrate that its safety functions can be performed during and/or after the earthquake. The required security features depend not only on The equipment itself also depends on the role of the equipment in the system and in the power plant. Safety functions during an earthquake may be related to the safety required after an earthquake The function is the same or it may be different. For example, an electrical device may be required to not malfunction during an earthquake, or during and after an earthquake. Perform an active function, or may require it to remain intact during an earthquake and require an active function after an earthquake, or these requirements Any combination. For another device, it may only be required to maintain structural integrity during and after an earthquake. These given requirements should be clear And the definition of the safety function should be given as part of the equipment qualification technical requirements document. Verify that the selected method of identification is consistent The request is the responsibility of the user and/or the principal. When the equipment safety function requirements confirm the operability of the equipment during the earthquake, it should be carried out in the continuous part of the identification of the simulated strong earthquake movement. As part of the overall qualification program, seismic tests shall be carried out in the order specified in GB/T 12727 or other applicable standards, and A significant aging mechanism is determined and considered in accordance with the test margins discussed in the relevant standards. In these guidelines, the equipment should be proven throughout Functional safety can be performed during the life of the appraisal, including functional operability during and/or after a safe shutdown earthquake at the end of the appraisal period.

6 Damping

6.1 Overview Damping is a general term for a variety of energy dissipation mechanisms in a system. In fact, damping depends on many parameters, such as structural systems, modes, strains, Normal force, speed, material, connection method and slip amount. According to the linear vibration theory, simplify the assumption that the damping is purely viscous, or with moving parts The relative speed is proportional. Therefore, when it comes to the damping value of an actual system, it is usually assumed to be equivalent to viscous or linear. through Often this is a simplified method of using linear analytical theory to describe actual hardware performance with some degree of non-linearity. For equipment made up of many components, the damping is often not a single value, and the damping is related to each part of the equipment, from the bolt Join or weld the structure to the material properties. When determining the device damping value, a range of typical values is usually given. Because in most cases, equipment, The damping values of the vibration modes of the structures and components are different, so in the analysis, a comprehensive resistance is often used in the frequency range studied. Nigerian value.