Regulatory Guide 1.166

(Draft Was DG-1034) Pre-Earthquake Planning & Immediate Nuclear Power Plant Operator Postearthquake Actions

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Issue date:	03/31/1997
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DG-1034 RG-1.166
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U.S. NUCLEAR REGULATORY COMMISSION March 1997 REGULATORY GUIDE

÷o *OFFICE OF NUCLEAR REGULATORY RESEARCH

REGULATORY GUIDE 1.166 (Draft was DG-1034)

PRE-EARTHQUAKE PLANNING AND IMMEDIATE NUCLEAR POWER PLANT OPERATOR

POSTEARTHQUAKE ACTIONS

A. INTRODUCTION

This guide provides guidance acceptable to the NRC staff for a timely evaluation after an earthquake of Paragraph IV(a)(4) of Appendix S, "Earthquake the recorded instrumentation data and for determining Engineering Criteria for Nuclear Power Plants," to whether plant shutdown is required by 10 CFR Part 50.

10 CFR Part 50, "Domestic Licensing of Production and Utilization Facilities," requires that suitable instru The information collections contained in this regu mentation 1 be provided so that the seismic response of latory guide are covered by the requirements of 10 CFR

nuclear power plant features important to safety can be Part 50,which were approved by the Office of Manage evaluated promptly. Paragraph IV(a)(3) of Appendix S ment and Budget, approval number 3150-0011. The to 10 CFR Part 50 requires shutdown of the nuclear NRC may not conduct or sponsor, and a person is not power plant if vibratory ground motion exceeding that required to respond to, a collection of information un of the operating basis earthquake ground motion (OBE) less it displays a currently valid OMB control number.

or significant plant damage occurs. If systems,, struc

B. DISCUSSION

tures, or components necessary for the safe shutdown When an earthquake occurs, ground motion data of the nuclear power plant are not available after occur are recorded by the seismic instrumentation. 1 These rence of the OBE, the licensee must consult with the data are used to make a rapid determination of the de NRC and must propose a plan for the timely, safe shut gree of severity of the seismic event. The data from the down of the nuclear power plant. Licensees of nuclear nuclear power plant's free-field seismic instrumenta power plants that are subject to the earthquake engi tion, coupled with information obtained from a plant neering criteria in Appendix S to 10 CFR Part 50 are re walkdown, are used to make the initial determination of quired by 10 CFR 50.54(ff) to shut down the plant if whether the plant must be shut down, if it has not al the criteria in Paragraph IV(a)(3) of Appendix S are ex ready been shut down by operational perturbations ceeded.

resulting from the seismic event. If on the basis of these initial evaluations (instrumentation data and

1 Regulatory Guide 1.12, Revision 2, "Nuclear Power Plant Instrumen walkdown) it is concluded that the plant shutdown cri tation for Earthquakes," describes seismic instrumentation that is ac ceptable to the NRC staff. teria have not been exceeded, it is presumed that the USNRC REGULATORY GUIDES The guides wa issued In the following ten broad divisions:

Regulatory Guides we Issued to'describe n make available to the public such Informa tlon as methods acceptable to Vie NRC staff for Implementing specific pats of the Com 1. Power Reactors & Products

2. Research and Test Reactors 7. Transportation mission's regulations, techniques used by the staff inevaluating specific problems or pos S. Occupaional Health tulated accidents, and data needed by the NRC staff inits review of applications for per 3 Fuels erd Materials Facilities

4. Environmental ard Siting 9. Antitrust and Financal Review mits and icensee. Regulory guldes are not substitutes for regulations, and compllance 10.. General with them Is not required. Methods aid solutions different from those set out Inthe guides s Materials and Plant Protection will be acceptable Ifthey provide a basis for the findings requisite to the Issuance or con tinuence of a permit or lcense by te Commission. Single copies oaregulatory guides may be obtained free of charge by writing the Office of This guide was issued alter consideration of comments received from the public Com Administration, Attention: Distribution and Mail Services Section. US. Nudear Regulatory merts and suggestions for improvements Inthese guides we encouraged at all imes, and Commission, Washington. DC 20555-0001; or by fax at (301)415-2280.

guides will be revised, as appropriate, to accommodate comments " to reflect new In formation or aspedence. Issued guides may also be purchased from the National Technilcal Information Service on a standing order basis. Details on this service may be obtained by writing NTIS, 6285 Port Written comments may be submitted to the Rules Revew and Directives Branch, DFIPS, Royal Road, Springfield, VA 22161.

ADM, U.S. Nulear Regulatory Commission, Washington, DC 20555-0001.

plant will not be shut down (or could restart following a mends 1.0 to 2.0 Hz for the range of the spectral veloc post-trip review, if it tripped off-line because of the ity limit since some structures have fundamental earthquake). Guidance on postshutdown inspections frequencies below 1.5 Hz. This is instead of the 1.5 to and plant restart is contained in Regulatory Guide 2.0 Hz range proposed by EPRI. K

1.167, "Restart of a Nuclear Power Plant Shut Down by Because free-field seismic instrumentation data a Seismic Event." are used in the plant shutdown determiniation, it is im The Electric Power Research Institute has devel portant to ascertain that the time-history analysis hard oped guidelines that will enable licensees to quickly ware and software were functioning properly. There identify and assess earthquake effects on nuclear power fore, the response spectrum and CAV should be plants. These guidelines are in EPRI NP-5930, "A Cri calculated using a suitable earthquake time-history or terion for Determining Exceedance of the Operating manufacturer's calibration standard after the initial in Basis Earthquake," July 19882; EPRI NP-6695, stallation and each servicing of the free-field instru

"Guidelines for Nuclear Plant Response to an Earth mentation. After an earthquake at the plant site, the re quake," December 19892; and EPRI TR-100082, sponse spectrum and CAV should be calculated using

"Standardization of the Cumulative Absolute Veloc the time-history or calibration standard that was used ity," December 1991.2 during the last servicing (or initial instrumentation in This regulatory guide is based on the assumption stallation if no servicing has been performed) and the that the nuclear power plant has operable seismic in results compared with the latest data on file at the plant.

strumentation, including the computer equipment and The NRC staff does not endorse the philosophy software required to process the data within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> af discussed in EPRI NP-6695, Section 4.3.4 (first para ter an earthquake. This is necessary because the deci graph, last sentence), pertaining to plant shutdown con sion to shut down the plant will be made, in part, by siderations following an earthquake based on the need comparing the recorded data against OBE exceedance for continued power generation in the region. If a li criteria. The decision to shut down the plant is also censee determines that plant shutdown is required by based on the results of the plant walkdown inspections the NRC's regulations, but the licensee does not con L

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. If the seismic sider it prudent to do so, the licensee would be required \

instrumentation or data processing equipment is inop to consult with the NRC and propose a plan for the erable, the guidelines in Appendix A to this guide timely, safe shutdown of the nuclear power plant.

should be used to determine whether the OBE has been Because earthquake-induced vibration of the reac exceeded. tor vessel could lead to changes in neutron fluxes, a Shutdown of the nuclear power plant is required if prompt check of the neutron flux monitoring sensors the vibratory ground motion experienced exceeds that would provide an indication that the reactor is stable.

of the OBE. A criterion for determining exceedance of Since the containment isolation valves may have the OBE (based on data recorded in the free-field) is malfunctioned during an earthquake, inspection of the provided in EPRI NP-5930: a threshold response spec containment isolation system is necessary to ensure trum ordinate check and a cumulative absolute velocity continued containment integrity.

(CAV) check. Seismic Category I structures at a nuclear power plant site may be designed using different Appendix B to this guide provides definitions to be ground motion response spectra; for example, one used used with this guidance.

for the certified standard design and another for site

C. REGULATORY POSITION

specific applications. The spectrum ordinate criterion is based on the lowest spectrum used in the design of the 1. BASE-LINE DATA

Seismic Category I structures. A procedure to standard ize the calculation of the CAV is provided in EPRI L1 Information Related to Seismic TR-100082. A spectral velocity threshold has also Instrumentation been recommended by EPRI since some structures A file containing information on all the seismic in have fundamental frequencies below the range speci strumentation should be kept at the plant. The file fied in EPRI NP-5930. The NRC staff now recom should include:

2 1. Information on each instrument type such as EPRI reports may be obtained from the Electric Power Research Insti tute, EPRI Distribution Center, 207 Coggins Dr., RO. Box 23205, make, model, and serial number; manufacturers' data Pleasant Hill, CA 94523. sheet; list of special features or options; performance

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characteristics; examples of typical instrumentation 3. EVALUATION OF GROUND MOTION

readings and interpretations; operations and mainte RECORDS

nance manuals; repair procedures (manufacturers' rec

3.1 Data Identification

.. ommendations for repairing common problems); and a list of any special requirements, e.g., for maintenance, A record collection log should be maintained at the operation, or installation. plant, and all data should be identifiable and traceable with respect to:

2. Plan views and vertical sections showing the lo

1. The date and time of collection, cation of each seismic instrument and the orientation of the instrument components with respect to plant refer 2. The make, model, serial number, location, and ence axes. orientation of the instrument (sensor) from which the record was collected.

3. A complete service history of each seismic in strument. The service history should include informa 3.2 Data Collection tion such as dates of servicing, description of 3.2.1 Only personnel trained in the operation of completed work, and calibration records and data the instrument should collect the data.

(where applicable). The documentation and retention

3.2.2 The steps for removing and storing records of these data should be commensurate with the from each seismic instrument should be planned and recordkeeping for other plant equipment.

performed in accordance with established procedures.

4. A suitable earthquake time-history (e.g., the Oc 3.2.3 Extreme caution should be exercised to tober 1987 Whittier, California, earthquake) or man prevent accidental damage to the recording media and ufacturer's calibration standard and the corresponding instruments during data collection and subsequent han response spectrum and cumulative absolute velocity dling.

(CAV) (see Regulatory Positions 4.1 and 4.2). After the initial installation and each servicing of the free-field 3.2A As data are collected and the instrumenta instrumentation, the response spectrum and CAV tion is inspected, notes should be made regarding the should be calculated and filed (see Regulatory Position condition of the instrument and its installation, for ex

4.3). ample, instrument flooded, mounting surface tilted, or objects that fell and struck the instrument or the instru

1.2 Planning for Postearthquake Inspections ment mounting surface.

3.2.5 For validation of the collected data, the in Sections 4.3.4.1 and 5.3.1 of EPRI NP-6695,

"Guidelines for Nuclear Plant Response to an Earth formation described in Regulatory Position 1.1(4)

quake," describe actions, such as selecting equipment should be provided.

and structures for inspections and the content of the 3.2.6 If the instrument's operation appears to baseline inspections, that are to be taken before an have been normal, the instrument should remain in earthquake and that are acceptable to the NRC staff for service without readjustment or change that would de satisfying the requirements in Paragraph IV(a)(3) of feat attempts to obtain postevent calibration.

Appendix S to 10 CFR Part 50 for ensuring the safety of nuclear power plants. 3.3 Record Evaluation Records should be analyzed according to the man

2. ACTIONS IMMEDIATELY AFTER AN ufacturer's specifications and the results of the analysis EARTHQUAKE should be evaluated. Any record anomalies, invalid data, and nonpertinent signals should be noted, along The guidelines for actions immediately after an with any known causes.

earthquake that are specified in Sections 4.3.1 (with the exception specified below) and 4.3.2 of EPRI NP-6695 4. DETERMINING OBE EXCEEDANCE

are acceptable to the NRC staff for satisfying the re The evaluation to determine whether the OBE was quirements in Paragraph IV(a)(3) of Appendix S to 10

exceeded should be performed using data obtained CFR Part 50.

from the three components of the free-field ground mo

"InSection 4.3.1, a check of the neutron flux moni tion (i.e., two horizontal and one vertical). The evalua toring sensors for changes should be added to the spe tion may be performed on uncorrected earthquake cific control room board checks. records. It was found in a study of uncorrected versus

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corrected earthquake records (see EPRI NP-5930) that and software were functioning properly. The results of the use of uncorrected records is conservative. The this comparison should be reported to the NRC.

evaluation should consist of a check of the response spectrum and CAV and a check on the operability of the 4.4 Inoperable Instrumentation or Data Processing Hardware or Software K

instrumentation. This evaluation should take place within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of the earthquake. If the response spectrum and the CAV (Regulatory Positions 4.1 and 4.2) cannot be obtained because the

4.1 Response Spectrum Check seismic instrumentation is inoperable, data from the

4.1.1 The OBE response spectrum check is per instrumentation are destroyed, or the data processing formed using the lower of: hardware or software is inoperable, the criteria in Ap pendix A to this guide should be used to determine

1. The spectrum used in the certified standard whether the OBE has been exceeded.

design, or

5. CRITERIA FOR PLANT SHUTDOWN

2. A spectrum other than (1) used in the design of any Seismic Category I structure. If the OBE is exceeded or significant plant damage occurs, the plant must be shut down unless a plan for the

4.1.2 The OBE response spectrum is exceeded if timely, safe shutdown of the nuclear power plant has any one of the three components (two horizontal and been proposed by the licensee and accepted by the NRC

one vertical) of the 5 percent of critical damping re staff.

sponse spectra generated using the free-field ground motion is larger than: 5.1 OBE Exceedance

1. The corresponding design response spectral If the response spectrum check and the CAV check acceleration (OBE spectrum if used in the de (performed or calculated in accordance with Regulato sign, otherwise 1/3 of the safe shutdown earth ry Positions 4.1 and 4.2) were exceeded, the OBE was quake ground motion (SSE) spectrum) or exceeded and plant shutdown is require

d. If either

0.2g, whichever is greater, for frequencies be check does not exceed the criterion, the earthquake mo tween 2 to 10 Hz, or tion did not exceed the OBE. If only one check can be K

performed, the other check is assumed to be exceeded;

2. The corresponding design response spectral if neither check can be performed, see Regulatory Posi velocity (OBE spectrum if used in the design, tion 4.4. The determination of whether or not the OBE

otherwise 1/3 of the SSE spectrum) or a spec has been exceeded should be performed even if the tral velocity of 6 inches per second (15.24 cen plant automatically shuts down as a result of the earth timeters per second), whichever is greater, for quake.

frequencies between 1 and 2 Hz.

5.2 Damage

4.2 Cumulative Absolute Velocity Check The plant should be shut down if the walkdown For each component of the free-field ground mo inspections performed in accordance with Regulatory tion, the CAV should be calculated as follows: (1) the Position 2 discover damage. This evaluation should absolute acceleration (g units) time-history is divided 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 earthquake occurrence.

into 1-second intervals, (2) each 1-second interval that has at least 1 exceedance of 0.025g is integrated over 5.3 Continued Operation time, (3) all the integrated values are summed together If the OBE was not exceeded and the walkdown in to arrive at the CAy. The CAV check is exceeded if any spection indicates no damage to the nuclear power CAV calculation is greater than 0.16 g-second. Addi plant, shutdown of the plant is not required. The plant tional information on how to determine the CAV is pro may continue to operate (or may restart following a vided in EPRI TR-100082. post-trip review, if it automatically shut down because of the earthquake).

4.3 Instrument Operability Check After an earthquake at the plant site, the response 6. PRE-SHUTDOWN INSPECTIONS

spectrum and CAV should be calculated using the same The pre-shutdown inspections described in Sec input as that used in Regulatory Position 1.1(4), and the tion 4.3.4 of EPRI NP-6695, "Guidelines for Nuclear results should be compared with the latest filed data to Plant Response to an Earthquake," with the exceptions demonstrate that the time-history analysis hardware specified below, are acceptable to the NRC staff for

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satisfying the requirements in Paragraph IV(aX3) of shutdown activities. In order to ascertain possi Appendix S to 10 CFR Part 50 for ensuring the safety of ble fuel and reactor internal damage, the fol nuclear power plants. lowing checks should be made, if possible, be fore plant shutdown is initiated ..... "

6.1 Shutdown Timing

D. IMPLEMENTATION

Delete the last sentence in the first paragraph of Section 4.3.4 of EPRI NP-6695. The purpose of this section is to provide guidance to applicants and licensees regarding the NRC staff's

6.2 Safe Shutdown Equipment plans for using this regulatory guide.

In Section 4.3.4.1 of EPRI NP-6695, a check of the Except in those cases in which the applicant pro containment isolation system should be added to the poses an acceptable alternative method for complying minimum list of equipment to be inspected. with the specified portions of the Commission's regula tions, the method described in this guide will be used in

6.3 Orderly Plant Shutdown the evaluation of applications for construction permits, The following paragraph in Section 4.3.4 of EPRI operating licenses, combined licenses, or design certi NP-6695 is printed here to emphasize that the plant fication submitted after January 10, 1997. This guide should shut down in an orderly manner. will not be used in the evaluation of an application for an operating license submitted after January 10, 1997,

"Prior to initiating plant shutdown following if the construction permit was issued prior to that date.

an earthquake, visual inspections and control board checks of safe shutdown systems should Holders of an operating license or construction per be performed by plant operations personnel, mit issued prior to January 10, 1997, may voluntarily and the availability of off-site and emergency implement the methods described in this guide in com on-site power sources should be determined. bination with the methods in Revision 2 to Regulatory The purpose of these inspections is to deter Guide 1.12, "Nuclear Power Plant Instrumentation for mine the effect of the earthquake on essential Earthquakes," and in Regulatory Guide 1.167, "Restart safe shutdown equipment which is not normal of a Nuclear Power Plant Shut Down by a Seismic ly in use during power operation so that any re Event." Other implementation strategies, such as vol sets or repairs required as a result of the earth untary implementation of portions of the cited regula quake can be performed, or alternate tory guides, will be evaluated by the NRC staff on a equipment can be readied, prior to initiating case-by-case basis.

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APPENDIX A

INTERIM OPERATING BASIS EARTHQUAKE EXCEEDANCE GUIDELINES

11 This regulatory guide is based on the assumption be determined (Regulatory Positions 4.1 and 4.2),

that the nuclear power plant has operable seismic in the OBE will be considered to have been exceeded strumentation and equipment (hardware and software) and the plant must be shut down if one of the fol to process the data. If the seismic instrumentation or lowing applies:

data processing equipment is inoperable, the following

1. The earthquake resulted in Modified Mercalli should be used to determine whether the operating Intensity (MMI) VI or greater within 5 km of basis earthquake ground motion (OBE) has been the plant, exceeded:

2. The earthquake was felt within the plant and

1. For plants at which instrumentally determined data was of magnitude 6.0 or greater, or are available only from an instrument installed on a 3. The earthquake was of magnitude 5.0 or great foundation, the cumulative absolute velocity er and occurred within 200 km. of the plant.

(CAV) check (see Regulatory Position 4.2 of this guide) is not applicable. In this case, the determina A postearthquake plant walkdown should be con tion of OBE exceedance is based on a response ducted after the earthquake (see Regulatory Position 2 spectrum check similar to that described in Regula of this guide).

tory Position 4.1 of this regulatory guide. A com If plant shutdown is warranted under the above parison is made between the foundation-level de guidelines, the plant should be shut down in an orderly sign response spectra and data obtained from the manner (see Regulatory Position 6 of this guide).

foundation-level instruments. If the response spec trum check at any foundation is exceeded, the OBE Note: The determinations of epicentral loca is exceeded and the plant must be shut down. At tion, magnitude, and intensity by the U.S. Geo this instrument location it is inappropriate to use logical Survey, National Earthquake Informa K

the 0.2g spectral acceleration limit or the 6 inches tion Center, will usually take precedence over per second (15.24 centimeters per second) spectral other estimates; however, regional and local velocity limit stated in Regulatory Position 4.1.2. determinations will be used if they are consid ered to be more accurate. Also, higher quality

2. For plants at which no free-field or foundation damage reports or a lack of damage reports level instrumental data are available, or the data from the nuclear power plant site or its imme processing equipment is inoperable and the re diate vicinity will take precedence over more sponse spectrum check and the CAV check can not distant reports.

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APPENDIX B

DEFINITIONS

Certified Standard Design. A Commission ap tinued operation without undue risk to the health and proval, issued pursuant to Subpart B of 10 CFR Part 52, safety of the public will remain functional. The value of of a standard design for a nuclear power facility. the OBE is set by the applicant.

Design Response Spectra. Response spectra used Spectral Acceleration. The acceleration response to design Seismic Category I structures, systems, and of a linear oscillator with prescribed frequency and components.

damping.

Operating Basis Earthquake Ground Motion (OBE). The vibratory ground motion for which those Spectral Velocity. The velocity response of a lin features of the nuclear power plant necessary for con- ear oscillator with prescribed frequency and damping.

REGULATORY ANALYSIS

A separate regulatory analysis was not prepared for benefits of the rule as implemented by the guide. A

this regulatory guide. The regulatory analysis, "Revi copy of the regulatory analysis is available for inspec sions of 10 CFR Part 100 and 10 CFR Part 50," was pre tion and copying for a fee at the NRC Public Document pared for these amendments, and it provides the regula Room, 2120 L Street NW. (Lower Level), Washington, tory basis for this guide and examines the costs and DC, as Attachment 7 to SECY-96-118.

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