RG1012 核电厂地震仪表 1997.docx

1、RG1012 核电厂地震仪表 1997Revision 2March 1997Regulatory Guide 1.12 Nuclear Power Plant Instrumentation For Earthquakes(Draft issued as DG-1033) Division Index | Regulatory Guide Index | NRC Home Page Publication Information A. INTRODUCTIONIn 10 CFR Part 20, Standards for Protection Against Radiation, lice

2、nsees are required to make every reasonable effort to maintain radiation exposures as low as is reasonably achievable. Paragraph IV(a)(4) of Appendix S, Earthquake Engineering Criteria for Nuclear Power Plants, to 10 CFR Part 50, Domestic Licensing of Production and Utilization Facilities, requires

3、that suitable instrumentation must be provided so that the seismic response of nuclear power plant features important to safety can be evaluated promptly after an earthquake. Paragraph IV(a)(3) of Appendix S to 10 CFR Part 50 requires shutdown of the nuclear power plant if vibratory ground motion ex

4、ceeding that of the operating basis earthquake ground motion (OBE) occurs.1This guide describes seismic instrumentation that is acceptable to the NRC staff for satisfying the requirements of Part 20 and Appendix S to Part 50.The information collections contained in this regulatory guide are covered

5、by the requirements of 10 CFR Part 50, which were approved by the Office of Management and Budget, approval number 3150-0011. The NRC may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid OMB control number.B. DISCUSS

6、IONWhen an earthquake occurs, it is important to take prompt action to assess the effects of the earthquake at the nuclear power plant. This assessment includes both an evaluation of the seismic instrumentation data and a plant walkdown. Solid-state digital time-history accelerographs installed at a

7、ppropriate locations will provide time-history data on the seismic response of the free-field, containment structure, and other Seismic Category I structures. The instrumentation should be located so that the response may be compared and evaluated with the design basis and so that occupational radia

8、tion exposures associated with their location, installation, and maintenance are maintained as low as reasonably achievable (ALARA). Instrumentation is provided in the free-field and at foundation level and at elevation in Seismic Category I structures. Free-field instrumentation data will be used t

9、o compare measured response to the engineering evaluations used to determine the design input motion to the structures and to determine whether the OBE has been exceeded (see Regulatory Guide 1.166). The instruments located at the foundation level and at elevation in the structures measure responses

10、 that are the input to the equipment or piping and will be used in long-term evaluations (see Regulatory Guide 1.167, Restart of a Nuclear Power Plant Shut Down by a Seismic Event). Foundation-level instrumentation will provide data on the actual seismic input to the containment and other Seismic Ca

11、tegory I structures and will be used to quantify differences between the vibratory ground motion at the free-field and at the foundation level. Instrumentation is not located on equipment, piping, or supports since experience has shown that data obtained at these locations are obscured by the vibrat

12、ory motion associated with normal plant operation.The guidance in Regulatory Guide 1.166 is based on the assumption that the nuclear power plant has operable seismic instrumentation, including the equipment and software needed to process the data within 4 hours after an earthquake. This is necessary

13、 to determine whether plant shutdown is required. This determination will be made by comparing the recorded data against OBE exceedance criteria and by evaluating the results of the plant walkdown inspections that take place within 8 hours of the event.It may not be necessary for identical nuclear p

14、ower units on a given site to each be provided with seismic instrumentation if essentially the same seismic response at each of the units is expected from a given earthquake.An NRC staff evaluation of seismic instrumentation noted that instruments have been out of service during plant shutdown and s

15、ometimes during plant operation. The instrumentation system should be operable and operated at all times. If the seismic instrumentation or data processing hardware and software necessary to determine whether the OBE has been exceeded is inoperable, the guidelines in Appendix A to Regulatory Guide 1

16、.166 should be used. The characteristics, installation, activation, remote indication, and maintenance of the seismic instrumentation are described in this guide to help ensure (1) that the data provided are comparable with the data used in the design of the nuclear power plant, (2) that exceedance

17、of the OBE can be determined, and (3) that the equipment will perform as required. It is important that all the significant ground motion associated with an earthquake is recorded. This is accomplished by specifying how long before and after the actuation of the seismic trigger the data should be re

18、corded. Settings for the instrumentations pre-event memory should be correlated with the maximum distance to any potential epicenter that could affect a specific site. The P wave may not be recorded with only a 3-second memory setting. Also, when an event occurs at some distance and the trigger thre

19、shold limit is not exceeded until 15 or 20 seconds into the event, a part of the record, although at low amplitude, is lost. A 30-second value may be more appropriate and is within the capabilities of current digital time-history accelerographs at no additional cost.The appendix to this guide provid

20、es definitions to be used with this guidance.C. REGULATORY POSITIONThe type, locations, operability, characteristics, installation, actuation, remote indication, and maintenance of seismic instrumentation described below are acceptable to the NRC staff for satisfying the requirements in 10 CFR Part

21、20 and Paragraph IV(a)(4) of Appendix S to 10 CFR Part 50 for ensuring the safety of nuclear power plants.1. SEISMIC INSTRUMENTATION TYPE AND LOCATION1.1 Solid-state digital instrumentation that will enable the processing of data at the plant site within 4 hours of the seismic event should be used.1

22、.2 A triaxial time-history accelerograph should be provided at the following locations:1. Free-field.2. Containment foundation.3. Two elevations (excluding the foundation) on a structure inside the containment.4. An independent Seismic Category I structure foundation where the response is different

23、from that of the containment structure.5. An elevation (excluding the foundation) on the independent Seismic Category I structure selected in 4 above.6. If seismic isolators are used, instrumentation should be placed on both the rigid and isolated portions of the same or an adjacent structure, as ap

24、propriate, at approximately the same elevations.1.3 The specific locations for instrumentation should be determined by the nuclear plant designer to obtain the most pertinent information consistent with maintaining occupational radiation exposures ALARA for the location, installation, and maintenanc

25、e of seismic instrumentation. In general:1.3.1 The free-field sensors should be located and installed so that they record the motion of the ground surface and so that the effects associated with surface features, buildings, and components on the recorded ground motion will be insignificant.1.3.2 The

26、 in-structure instrumentation should be placed at locations that have been modeled as mass points in the building dynamic analysis so that the measured motion can be directly compared with the design spectra. The instrumentation should not be located on a secondary structural frame member that is no

27、t modeled as a mass point in the building dynamic model.1.3.3 A design review of the location, installation, and maintenance of proposed instrumentation for maintaining exposures ALARA should be performed by the facility in the planning stage in accordance with Regulatory Guide 8.8, Information Rele

28、vant to Ensuring that Occupational Radiation Exposures at Nuclear Power Stations Will Be As Low As Is Reasonably Achievable.1.3.4 Instrumentation should be placed in a location with as low a dose rate as is practical, consistent with other requirements.1.3.5 Instruments should be selected to require

29、 minimal maintenance and in-service inspection, as well as minimal time and numbers of personnel to conduct installation and maintenance.2. INSTRUMENTATION AT MULTI-UNIT SITESInstrumentation in addition to that installed for a single unit will not be required if essentially the same seismic response

30、 is expected at the other units based on the seismic analysis used in the seismic design of the plant. However, if there are separate control rooms, annunciation should be provided to both control rooms as specified in Regulatory Position 7.3. SEISMIC INSTRUMENTATION OPERABILITYThe seismic instrumen

31、tation should operate during all modes of plant operation, including periods of plant shutdown. The maintenance and repair procedures should provide for keeping the maximum number of instruments in service during plant operation and shutdown.4. INSTRUMENTATION CHARACTERISTICS4.1 The design should in

32、clude provisions forin-service testing. The instruments should be capable of periodic channel checks during normal plant operation.4.2 The instruments should have the capability for in-place functional testing.4.3 Instrumentation that has sensors located in inaccessible areas should contain provisions for data recording in an accessible location, and the instrumentation should provide an external remote alarm to indicate actuation.4.4 The instrumentation should record, at a minimum, 3 seconds of low-amplitude motion prior to seismic trigger actuation, continue to record the motion d