ML003739208
| ML003739208 | |
| Person / Time | |
|---|---|
| Issue date: | 02/28/1995 |
| From: | Office of Nuclear Regulatory Research |
| To: | |
| References | |
| DG-1033 | |
| Download: ML003739208 (12) | |
Text
o U.S. NUCLEAR REGULATORY COMMISSION February 1995 I OFFICE OF NUCLEAR REGULATORY RESEARCH Division 1 S* Task DG-1033 DRAFT REGULATORY GUIDE
Contact:
R.M. Kenneally (301)415-6303 1 DRAFT REGULATORY GUIDE DG-1033 2 (Third Proposed Revision 2 to Regulatory Guide 1.12) 3 (Previously issued as Draft MS 140-5 and DG-1016) 4 NUCLEAR POWER PLANT INSTRUMENTATION FOR EARTHQUAKES 5 A. INTRODUCTION 6 In 10 CFR Part 20, "Standards for Protection Against Radiation," licensees are 7 required to make every reasonable effort to maintain radiation exposures as low as is 8 reasonably achievable. Paragraph IV(a)(4) of Proposed Appendix S, "Earthquake 9 Engineering Criteria for Nuclear Power Plants," to 10 CFR Part 50, "Domestic Licensing 10 of Production and Utilization Facilities," would require that suitable instrumentation 11 be provided so that the seismic response of nuclear power plant features important to 12 safety can be evaluated promptly. Paragraph IV(a)(3) of Proposed Appendix S to 10 CFR 13 Part 50 would require shutdown of the nuclear power plant if vibratory ground motion 14 exceeding that of the operating basis earthquake ground motion (OBE) occurs.'
15 This guide is being developed to describe seismic instrumentation acceptable to 16 the NRC staff for satisfying the requirements of Parts 20 and 50 and the Proposed 17 Appendix S to Part 50.
18 Regulatory guides are issued to describe and make available to the public such 19 information as methods acceptable to the NRC staff for implementing specific parts of 20 the Commission's regulations, techniques used by staff in evaluating specific problems 21 or postulated accidents, and guidance to applicants. Regulatory guides are not 22 'Guidance is being developed in Draft Regulatory Guide DG-1034, "Pre 23 Earthquake Planning and Immediate Nuclear Power Plant Operator Postearthquake 24 Actions," on criteria for plant shutdown.
This regulatory guide is being issued in draft form to involve the public in the early stages of the development of a regulatory position in this area. It has not received complete staff review and does not represent an official NRC staff position.
Public comments are being solicited on the draft guide (including any implementation schedule) and its associated regulatory analysis or value/impact statement. Comments should be accompanied by appropriate supporting data. Written comments may be submitted to the Rules Review and Directives Branch, DFIPS, Office of Administration, U.S. Nuclear Regulatory Commission, Washington, DC 20555. Copies of comments received may be examined at the NRC Public Document Room, 2120 L Street NW., Washington, DC. Comments will be most helpful if received by May 12, 1995.
Requests for single copies of draft guides (which may be reproduced) or for placement on an automatic distribution list for single copies of future guides in specific divisions should be made in writing to the U.S. Nuclear Regulatory Commission, Washington, DC 20555, Attention:
Office of Administration, Distribution and Mail Services Section.
1 substitutes for regulations, and compliance with regulatory guides is not 2 required. Regulatory guides are issued in draft form for public comment to 3 involve the public in the early stages of developing the regulatory positions.
4 Draft regulatory guides have not received complete staff review and do not 5 represent official NRC staff positions.
6 Any information collection activities mentioned in this draft regulatory 7 guide are contained as requirements in the proposed amendments to 10 CFR 8 Part 50 that would provide the regulatory basis for this guide. The proposed 9 amendments have been submitted to the Office of Management and Budget for 10 clearance that may be appropriate under the Paperwork Reduction Act. Such 11 clearance, if obtained, would also apply to any information collection 12 activities mentioned in this guide.
13 B. DISCUSSION 14 When an earthquake occurs, it is important to take prompt action to 15 assess the effects of the earthquake at the nuclear power plant. This 16 assessment includes both an evaluation of the seismic instrumentation data and 17 a plant walkdown. Solid-state digital time-history accelerographs installed 18 at appropriate locations will provide time-history data on the seismic 19 response of the free-field, containment structure, and other Category I 20 structures. The instrumentation should be located so that a comparison and 21 evaluation of such response may be made with the design basis and so that 22 occupational radiation exposures associated with. their location, installation, 23 and maintenance are maintained as low as reasonably achievable (ALARA).
24 Free-field instrumentation data would be used to compare measured 25 response to the engineering evaluations used to determine the design input 26 motion to the structures and to determine whether the OBE has been exceeded 27 (see Draft Regulatory Guide DG-1034). Foundation-level instrumentation would 28 provide data on the actual seismic input to the containment and other 29 buildings and would quantify differences between the vibratory ground motion 30 at the free-field and at the foundation level. The instruments located at the 31 foundation level and at elevation in the structures measure responses that are 32 the input to the equipment or piping and would be used in long-term 33 evaluations (see Draft Regulatory Guide DG-1035, "Restart of a Nuclear Power 34 Plant Shut Down by a Seismic Event"). Instrumentation is not located on 35 equipment, piping, or supports since experience has shown that data obtained 2
1 at these locations are obscured by vibratory motion associated with normal 2 plant operation.
3 The guidance being developed in Draft Regulatory Guide DG-1034 is based 4 on the assumption that the nuclear power plant has operable seismic instrumen 5 tation, including the equipment and software needed to process the data within 6 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after an earthquake. This is necessary to determine whether plant 7 shut down is required. This determination will be made by comparing the 8 recorded data against OBE exceedance criteria and the results of the plant 9 walkdown inspections that take place within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of the event.
10 It may not be necessary for identical nuclear power units on a given 11 site to each be provided with seismic instrumentation if essentially the same 12 seismic response at each of the units is expected from a given earthquake.
13 An evaluation of seismic instrumentation noted that instruments have 14 been out of service during plant shutdown and sometimes during plant 15 operation. The instrumentation system should be operable and operated at all 16 times. If the seismic instrumentation or data processing hardware and 17 software necessary to determine whether the OBE has been exceeded is 18 inoperable, the guidelines in Appendix A to Draft Regulatory Guide DG-1034 19 would be used.
20 The characteristics, installation, activation, remote indication, and 21 maintenance of the instrumentation are described in this guide to help ensure 22 (1) that the data provided are comparable with the data used in the design of 23 the nuclear power plant, (2) that exceedance of the OBE can be determined, and 24 (3) that the equipment will perform as required.
25 The appendix to this guide provides definitions to be used with this 26 guidance.
27 Holders of an operating license or construction permit issued prior to 28 the implementation date to be specified in the active guide may voluntarily 29 implement the methods to be described in the active guide and the methods 30 being developed in Draft Regulatory Guides DG-1034, "Pre-Earthquake Planning 31 and Immediate Nuclear Power Plant Operator Postearthquake Actions," and 32 DG-1035, "Restart of a Nuclear Power Plant Shut Down by a Seismic Event."
33 C. REGULATORY POSITION 34 The type, locations, operability, characteristics, installation, 35 actuation, remote indication, and maintenance of seismic instrumentation 3
1 described below are acceptable to the NRC staff for satisfying the require 2 ments in 10 CFR Part 20, 10 CFR 50.65(b)(2), and Paragraph IV(a)(4) of 3 Proposed Appendix S to 10 CFR Part 50 for ensuring the safety of nuclear power 4 plants.
5 1. SEISMIC INSTRUMENTATION TYPE AND LOCATION 6 1.1 Solid-state digital instrumentation that will enable the 7 processing of data at the plant site within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of the seismic event 8 should be used.
9 1.2 A triaxial time-history accelerograph should be provided at each 10 of the following locations:
11 1. Free-field.
12 2. Containment foundation.
13 3. Two elevations (excluding the foundation) on a structure 14 internal to the containment.
15 4. An independent Category I structure foundation where the 16 response is different from that of the containment 17 structure.
18 5. An elevation (excluding the foundation) on the independent 19 Category I structures selected in 4 above.
20 6. If seismic isolators are used, instrumentation should be 21 placed on both the rigid and isolated portions of the same 22 or an adjacent structure, as appropriate, at approximately 23 the same elevations.
24 1.3 The specific locations for instrumentation should be determined by 25 the nuclear plant designer to obtain the most pertinent information consistent 26 with maintaining occupational radiation exposures ALARA for the location, 27 installation, and maintenance of seismic instrumentation. In general:
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1 1.3.1 The free-field sensors should be located and installed so 2 that the effects that are associated with certain features, buildings, and 3 components will be absent from the recorded ground motion.
4 1.3.2 The instrumentation should be placed at locations that have 5 been modeled as mass points in the building dynamic analysis so that the 6 measured motion can be directly compared with the design spectra. The 7 instrumentation should not be located on a secondary structural frame member 8 that is not modeled as a mass point in the building dynamic model.
9 1.3.3 A design review of the location, installation, and 10 maintenance of proposed instrumentation for maintaining exposures ALARA should 11 be performed by the facility in the planning stage in accordance with 12 Regulatory Guide 8.8, "Information Relevant to Ensuring that Occupational 13 Radiation Exposures at Nuclear Power Stations Will Be As Low As Is Reasonably 14 Achievable."
15 1.3.4 Instrumentation should be placed in a location with as low a 16 dose rate as is practical, consistent with other requirements.
17 1.3.5 Instruments should be selected to require minimal 18 maintenance and in-service inspection, as well as minimal time and numbers of 19 personnel to conduct installation and maintenance.
20 2. INSTRUMENTATION AT MULTI-UNIT SITES 21 Instrumentation in addition to that installed for a single unit will not 22 be required if essentially the same seismic response is expected at the other 23 units based on the seismic analysis used in the seismic design of the plant.
24 However, if there are separate control rooms, annunciation should be provided 25 to both control rooms as specified in Regulatory Position 7.
26 3. SEISMIC INSTRUMENTATION OPERABILITY 27 The seismic instrumentation should operate during all modes of plant 28 operation, including periods of plant shutdown. The maintenance and repair 5
1 procedures should provide for keeping the maximum number of instruments in 2 service during plant operation and shutdown.
3 4. INSTRUMENTATION CHARACTERISTICS 4 4.1 The design should include provisions for in-service testing. The 5 instruments should be capable of periodic channel checks during normal plant 6 operation.
7 4.2 The instruments should have the capability for in-place functional 8 testing.
9 4.3 Instrumentation that has sensors located in inaccessible areas 10 should contain provisions for data recording in an accessible location, and 11 the instrumentation should provide an external remote alarm to indicate 12 actuation.
13 4.4 After actuation, the instrumentation should record the 3 seconds 14 of low amplitude motion prior to seismic trigger actuation, continue to record 15 the motion during the period in which the earthquake motion exceeds the 16 seismic trigger threshold, and continue to record low amplitude motion for a 17 minimum of 5 seconds beyond the last exceedance of the seismic trigger 18 threshold.
19 4.5 The instrumentation should be capable of recording 25 minutes of 20 sensed motion.
21 4.6 The battery should be of sufficient capacity to power the 22 instrumentation and sense and record (see Regulatory Position 4.5) 25 minutes 23 of motion, with no battery charger, over a period of not less than the channel 24 check test interval (Regulatory Position 8.2).
25 4.7 Acceleration Sensors 26 4.7.1 The dynamic range should be 1000:1 zero to peak, or greater; 27 for example, 0.O01g to 1.0g.
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1 4.7.2 The frequency range should be 0.20 Hz to 50 Hz or an 2 equivalent demonstrated to be adequate by computational techniques applied to 3 the resultant accelerogram.
4 4.8 Recorder 5 4.8.1 The sample rate should be at least 200 samples per second in 6 each of the three directions.
7 4.8.2 The bandwidth should be at least from 0.20 Hz to 50 Hz.
8 4.8.3 The dynamic range should be 1000:1 or greater and be able to 9 record at least 1.0g 0 to peak.
10 4.9 Seismic Trigger. The actuating level should be adjustable and 11 within the range of 0.O01g to 0.02g.
12 5. INSTRUMENTATION INSTALLATION 13 5.1 The instrumentation should be designed and installed so that the 14 mounting is rigid.
15 5.2 The instrumentation should be oriented so that the horizontal axes 16 are parallel to the orthogonal horizontal axes assumed in the seismic 17 analysis.
18 5.3 Protection against accidental impacts should be provided.
19 6. INSTRUMENTATION ACTUATION 20 6.1 Both vertical and horizontal input vibratory ground motion should 21 actuate the same time-history accelerograph. One or more seismic triggers may 22 be used to accomplish this.
23 6.2 Spurious triggering should be avoided.
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1 6.3 The seismic trigger mechanisms of the time-history accelerograph 2 should be set for a threshold ground acceleration of not more than 0.02g.
3 7. REMOTE INDICATION 4 Activation of the free-field or any foundation-level time-history 5 accelerograph should be annunciated in the control room. If there is more 6 than one control room at the site, annunciation should be provided to each 7 control room.
8 8. MAINTENANCE 9 8.1 The purpose of the maintenance program is to ensure that the 10 equipment will perform as required. As stated in Regulatory Position 3, the 11 maintenance and repair procedures should provide for keeping the maximum 12 number of instruments in service during plant operation and shutdown.
13 8.2 Systems are to be given channel checks every 2 weeks for the first 14 3 months of service after startup. Failures of devices normally occur during 15 initial operation. After the initial 3-month period and 3 consecutive 16 successful checks, monthly channel checks are sufficient. The monthly channel 17 check is to include checking the batteries. The channel functional test 18 should be performed every 6 months. Channel calibration should be performed 19 during refueling.
20 D. IMPLEMENTATION 21 The purpose of this section is to provide guidance to applicants and 22 licensees regarding the NRC staff's plans for using this regulatory guide.
23 This proposed revision has been released to encourage public 24 participation in its development. Except in those cases in which the 25 applicant proposes an acceptable alternative method for complying with the 26 specified portions of the Commission's regulations, the method to be described 27 in the active guide reflecting public comments will be used in the evaluation 28 of applications for construction permits, operating licenses, combined 29 licenses, or design certification submitted after the implementation date to 30 be specified in the active guide. This guide would not be used in the 8
I evaluation of an application for an operating license submitted after the 2 implementation date to be specified in the active guide if the construction 3 permit was issued prior to that date.
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I APPENDIX 2 DEFINITIONS 3 Acceleration Sensor. An instrument capable of sensing absolute acceleration 4 and transmitting the data to a recorder.
5 Accessible Instruments. Instruments or sensors whose locations permit ready 6 access during plant operation without violation of applicable safety 7 regulations, such as Occupational Safety and Health Administration (OSHA), or 8 regulations dealing with plant security or radiation protection safety.
9 Channel Calibration (Primary Calibration). The determination and, if 10 required, adjustment of an instrument, sensor, or system such that it responds 11 within a specific range and accuracy to an acceleration, velocity, or 12 displacement input, as applicable, or responds to an acceptable physical 13 constant.
14 Channel Check. The qualitative verification of the functional status of the 15 instrument sensor. This check is an "in-situ" test and may be the same as a 16 channel functional test.
17 Channel Functional Test (Secondary Calibration). The determination without 18 adjustment that an instrument, sensor, or system responds to a known input of 19 such character that it will verify the instrument, sensor, or system is 20 functioning in a manner that can be calibrated.
21 Containment - See Primary Containment and Secondary Containment.
22 Nonaccessible Instruments. Instruments or sensors in a location that does not 23 permit ready access during plant operation because of a risk of violating 24 applicable plant operating safety regulations, such as OSHA, or regulations 25 dealing with plant security or radiation protection safety.
26 Operating Basis Earthquake Ground Motion (OBE). The vibratory ground motion 27 for which those features of the nuclear power plant necessary for continued 28 operation without undue risk to the health and safety of the public will 29 remain functional. The value of the OBE is set by the applicant.
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I Primary Containment. The principal structure of a unit that acts as the 2 barrier, after the fuel cladding and reactor pressure boundary, to control the 3 release of radioactive material. The primary containment includes (1) the 4 containment structure and its access openings, penetrations, and appurte 5 nances, (2) the valves, pipes, closed systems, and other components used to 6 isolate the containment atmosphere from the environment, and (3) those systems 7 or portions of systems that, by their system functions, extend the containment 8 structure boundary (e.g., the connecting steam and feedwater piping) and 9 provide effective isolation.
10 Recorder. An instrument capable of simultaneously recording the data versus 11 time from an acceleration sensor or sensors.
12 Secondary Containment. The structure surrounding the primary containment that 13 acts as a further barrier to control the release of radioactive material.
14 Seismic Isolator. A device (for instance, laminated elastomer and steel) 15 installed between the structure and its foundation to reduce the acceleration 16 of the isolated structure, as well as the attached equipment and components.
17 Seismic Trigger. A device that starts the time-history accelerograph.
18 Time-History Accelerograph. An instrument capable of sensing and permanently 19 recording the absolute acceleration versus time. The components of the time 20 history accelerograph (acceleration sensor, recorder, seismic trigger) may be
- 21. assembled in a self-contained unit or may be separately located.
22 Triaxial. Describes the function of an instrument or group of instruments in 23 three mutually orthogonal directions, one of which is vertical.
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1 REGULATORY ANALYSIS
-1 2 A separate regulatory analysis was not prepared for this regulatory 3 guide. The draft regulatory analysis, "Proposed Revision of 10 CFR Part 100 4 and 10 CFR Part 50," was prepared for the proposed amendments, and it provides 5 the regulatory basis for this guide and examines the costs and benefits of the 6 rule as implemented by the guide. A copy of the draft regulatory analysis is 7 available for inspection and copying for a fee at the NRC Public Document 8 Room, 2120 L Street NW. (Lower Level), Washington, DC, as Enclosure 2 to 9 Secy 94-194.
UNITED STATES FIRST CLASS MAIL POSTAGE AND FEES PAID NUCLEAR REGULATORY COMMISSION USNRC WASHINGTON, D.C. 20555-0001 PERMIT NO. G-67 OFFICIAL BUSINESS PENALTY FOR PRIVATE USE, $300 12