ML20137J503
| ML20137J503 | |
| Person / Time | |
|---|---|
| Issue date: | 03/31/1997 |
| From: | NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | |
| References | |
| FRN-61FR65157, TASK-*****, TASK-RE AD93-2-012, AD93-2-12, REGGD-01.012, REGGD-1.012, NUDOCS 9704040041 | |
| Download: ML20137J503 (8) | |
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REGULATORY GUIDE OFFICE OF NUCLEAR REGULATORY RESEARCH REGULATORY GUIDE 1.12 (Draft was DG-1033)
NUCLEAR POWER PLANT INSTRUMENTATION FOR EARTHQUAKES A. INTRODUCTION NRC may not conduct or sponsor, and a person is not required to respond to, a collection ofinformation un-In 10 CFR Part 20, " Standards for Protection less it displays a currently valid OMB control number.
Against Radiation," licensees are required to make every reasonable effort to maintain radiation expo-B. DISCUSSION sures as low as is reasonably achievable. Paragraph When an earthquake occurs, it is important to take IV(a)(4) of Appendix S, " Earthquake Engineering prompt action to assess the effects of the earthquake at Criteria for Nuclear Power Plants," to 10 CFR Part the nuclear power plant. This assessment includes both 50," Domestic Licensing of Production and Utiliza-an evaluation of the seismic instrumentation data and a tion Facilities," requires that suitable instrumenta-plant walkdown. Solid-state digital time-history accel-tion must be provided so that the seismic response of erographs installed at appropriate locations will pro-nuclear power plant features important to safety can vide time-history data on the seismic response of the I
be evaluated promptly after an earthquake. Paragraph free-field, containment structure, and other Seismic IV(a)(3) of Appendix S to 10 CFR Part 50 requires Category I structures. The instrumentation should be shutdown of the nuclear power plant if vibratory located so that the response may be compared and ground motion exceeding that of the operating basis evaluated with the design basis and so that occupational earthquake ground motion (OBE) occurs.1 radiation exposures associated with their location, in-This guide describes seismic instrumentation that stallation, and maintenance are maintained as low as is acceptable to the NRC staff for satisfying the require-reasonably achievable (ALARA).
ments of Part 20 and Appendix S to Part 50.
Instrumentation is provided in the free-field and The information collections contained in this regu-at foundation level and at elevation in Seismic Cate-latory guide are covered by the requirements of 10 CFR gory I structures. Fre e-field instrume ntation data will Part 50, which were approved by the Office of Manage-be used to compare measured response to the engi-ment and Budget, approval number 3150-0011. The neering evaluations used to determine the design in-put motion to the structures and to determine whether 3 Regulatory Guide 1.166. " Pre. Earthquake Planning and immediate Nu-the OBE has been exceeded (see ReSulator7 Guide clear Power Plant Operator Postcarthquake Actions. provides criteria for plant shutdown after an carthquake.
1.166). The instruments located at the foundation 05NRC REGULATORY CNIDES The guides are msved m tne fonowing ten broad demons
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level and at elevation in the structures measure re-memory should be correlated with the maximum dis-sponses that are the input to the equipment or piping tance to any potential epicenter that could affect a spe-and will be used in long-term evaluations (see Regu-cific site. The "P" wave may not be recorded with only a latory Guide 1.167," Restart of a Nuclear Power Plant 3-second memory setting. Also, when an event occurs Shut Down by a Seismic EveN"). Foundation-level at some distance and the trigger threshold limit is not instrumentation will provide dato in the actual seis-exceeded until 15 or 20 seconds into the event, a part of mic input to the containment and othu Seismic Cate-the record, although at low amplitude, is lost. A 30-sec-gory I structures and will be used to quantify differ-ond value may be more appropriate and is within the ca-ences between the vibratory ground motion at the pabilities of cuuent digital time-history accelerographs free-field and at the foundation level. Instrumenta-at no additional cost.
tion is not located on equipment, piping, or supports since experience has shown that data obtamed at The appendix to this guide provides definitions to be used with this guidance.
these locations are obscured by the vibratory motion associated with normal plant operation.
C. REGULATORY POSITION The guidance in Regulatory Guide 1.166 is based The type, locations, operability, characteristics, in-on the assumption that the nuclear power plant has op-st 11 tion, actuation, remote indication, and mainte-erable seismic instrumentation, including the equip-n nce of seismic instrumentation described below are ment and software needed to process the data within acceptable to the NRC staff for satisfying the require-4 hours after an earthquake. This is necessary to deter-ments in 10 CFR Part 20 and Paragraph IV(a)(4) of Ap-mine whether plant shutdown is required. This determi-pendix S to 10 CFR Part 50 for ensuring the safety of nation will be made by comparing the recorded data nuclear power plants.
against OBE exceedance criteria and by evaluating the 1.
SEISMIC INSTRUMENTATION TYPE AND results of the plant walkdown inspections tha take LOCATION 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.
1.1 Solid-state digital instrumentation that will It may not be necessary for identical nuclear power enable the processing of data at the plant site within units on a given site to each be provided with seismic 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> of the seismic event should be used.
instrumentation if essentially the same seismic re-1.2 sponse at each of the units is expected from a given A triaxial time-history accelerograph should be provided at the following locations:
1.
Free-field.
An NRC staff evaluation of seismic instrumenta-2.
Containment foundation.
tion noted that mstruments have been out of service during plant shutdown and sometimes during plant op-3.
Two elevations (excluding the foun-eration. The instrumentation system should be oper.
dation) on a structure inside the containment.
able and operated at all times. If the seismic instrumen-4.
An independent Seismic Category I tation or data processing hardware and software structure foundation where the response is different necessary to determine whether the OBE has been ex-from that of the containment structure.
ceeded is inoperable, the guidelines in Appendix A t 5.
An elevation (excluding the foundation)
Regulatory Guide 1.166 should be used.
on the independent Seismic Category I structure The characteristics, installation, activation, remote selected in 4 above.
indication, and maintenance of the seismic instrumen-6.
If seismic isolators are used, instrumen-tation are described in this guide to help ensure (1) that tation should be placed on both the rigid and the data provided are comparable with the data used in isolated portions of the same or an adjacent struc-the design of the nuclear power plant, (2) that excee-ture, as appropriate, at approximately the same dance of the OBE can be determined, and (3) that the elevations.
equipment will perform as required.
1.3 The specific locations for instrumentation it is important that all the significant ground mo-should be determined by the nuclear plant designer to tion associated with an earthquake is recorded. This is obtain the most pertinent information consistent with accomplished by specifying how long before and after maintaining occupational radiation exposures ALARA the actuation of the seismic trigger the data should be for the location, installation, and maintenance of seis-recorded. Settings for the instrumentation's pre-event mic instrumentation. In general:
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1.3.1 The free-field sensors should be 10-4.
INSTRUMENTATION cated and installed so that they record the motion of the CIIARACTERISTICS l
ground surface and so that the effects associated with 4.1 The design should include provisions for surface features, buildings, and components on the re-corded ground motion will be insignificant.
in-service testing. The instruments should be capable of periodic channel checks during normal plant operation.
1.3.2 The m-structure instrumentation should be placed at locations that have been modeled as 4.2 The instruments should have the capability mass points in the building dynamic analysis so that the for in-place functional testing.
measured motion can be directly compared with the de-4.3 Instrumentation that has sensors located in sign spectra. The instrumentation should not be located inaccessible areas should contain provisions for data on a secondary structural frame member that is not recording in an accessible location, and the instrumen-modeled as a mass point in the building dynamic tation should provide an external remote alarm to indi-model.
cate actuation.
4.4 The instrumentation should record, at a mini-1.3.3 A design review of the location, instal-lation, and maintenance of proposed instrumentation mum,3 seconds oflow-amplitude motion prior to seis-mic trigger actuation, continue to record the motion I
for maintaining exposures ALARA should be performed by the facility in the planning stage in accor-during the period in which the earthquake motion ex-dance with Regulatory Guide 8.8, "Information Rele-ceeds the seismic trigger threshold, and continue to vant to Ensuring that Occupational Radiation Expo-record low-amplitude motion for a minimum of 5 sec-sures at Nuclear Power Stations Will Be As Irw As Is onds beyond the last exceedance of the seismic trigger threshold' Reasonably Achievable."
4.5 The instrumentation should be capable of re-1.3.4 Instrumentation should be placed in a cording 25 minutes of sensed motion.
location with as low a dose rate as is practical, consis-4.6 The battery should be of sufficient capacity to tent with other requirements.
power the instrumentation to sense and record (see Regulatory Position 4.5) 25 minutes of motion over a 1.3.5 Instruments should be selected to re-period of not less than the channel check test interval quire minimal maintenance and in-service inspection, (Regulatory Position 8.2). This can be accomplished by as well as minimal time and numbers of personnel to providing enough battery capacity for a minimum of 25 conduct installation and maintenance.
minutes of system operation at any time over a 24-hour period, without recharging, in combination with a bat-2.
INSTRUMENTATION AT MULTI-UNIT tery charger whose line power is connected to an unin-SITES terruptable power supply or a line source with an alarm that is checked at least every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. Other combina-tions oflarger battery capacity and alarm intervals may Instrumentation in addition to that installed for a be used.
single unit will not be required if essentially the same 4.7 Acceleration Sensors seismic response is expected at the other units based on the seismic analysis used in the seismic design of the 4.7.1 The dynamic range should be 1000:1 plant. However,if there are separate control rooms, an, zero to peak, or greater; for example. 0.00lg to 1.0g.
nunciation should be provided to both control rooms as 4.7.2 The frequency range should be 0.20 specified in Regulatory Position 7.
112 to 5011z or an equivalent demonstrated to be ade-quate by computational techniques applied to the resul-tant accelerogram.
- 3. SEISMIC INSTRUMENTATION 4.8 Recorder OPERABILITY 4.8.1 The sample rate should be at least 200 The seismic instrumentation should operate during samples per second in each of the three directions.
all modes of plant operation, including periods of plant 4.8.2 The bandwidth should be at least from shutdown. The maintenance and repair procedures 0.20 IIz to 50 liz.
should provide for keeping the maximum number of 4.8.3 The dynamic range should be 1000:1 instruments in service during plant operation and or greater, and the instrumentation should be able to re-shutdown.
cord at least 1.0g zero to peak.
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4.9 Seismic Trigger maximum number of instruments in service during The actuating level should be adjustable and pl nt operation and shutdown.
within the range of 0.00lg to 0.02g.
8.2 Systems are to be given channel checks every 2 weeks for the first 3 months of service after startup.
w 5.
INSTRUMENTATION INSTALLATION Failures of devices normally occur during initial opera-5.1 The instrumentation should be designed and tion. After the initial 3-month period and 3 consecutive installed so that the mounting is rigid.
successful checks, monthly channel checks are suffi-cient. The monthly channel check is to melude check-5.2 The instrumentation should be oriented so ing the batteries. The channel functional test should be that the horizontal components are parallel to the performed every 6 months. Channel calibration should orthogonal horizontal axes assumed in the seismic be performed during each refueling outage at a analysis.
minimum.
5.3 Protection against accidental impacts should D. IMPLEMENTATION
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The purpose of this section is to provide guidance 6.
INSRUMENTATION ACTUNflON to applicants and licensees regarding the NRC staff's plans for using this regulatory guide.
6.1 Both vertical and horizontal input vibratory ground motion should actuate the same time-history Except in those cases in which the applicant pro-accelerograph. One or more seismic triggers may be p ses an acceptable alternative method for complying used to accomplish this.
with the specified portions of the Commission's regula-tions, this guide will be used in the evaluation of appli-6.2 Spurious triggering should be avoided.
cations for construction permits, operating licenses, 6.3 The seismic trigger mechanisms of the time-combined licenses, or design certification submitted af-history accelerograph should be set for a threshold ter January 10,1997. This guide will not be used in the ground acceleration of not more than 0.02g.
evaluation of an application for an operating license submitted after January 10,1997, if the construction 7.
REMOTE INDICATION permit was issued prior to that date.
Triggering of the free-field or any foundation-level IIolders of an operating license or construction per-time-history accelerograph should be annunciated in mit issued prior to January 10,1997, may voluntarily the control room. If there is more than one control room implement the methods described in this guide in com-at the site, annunciation should be provided to each bination with the methods in Regulatory Guides 1.166, control room.
" Pre-Earthquake Planning and Immediate Nuclear Power Plant Operator Postearthquake Actions," and
- 8. MAINTENANCE 1.167," Restart of a Nuclear Power Plant Shut Down by 8.1 The purpose of the maintenance program is a Seismic Event." Other implementation strategies, to ensure that the equipment will perform as required.
such as voluntary implementation of portions of the As stated in Regulatory Position 3, the maintenance cited regulatory guides, will be evaluated by the NRC and repair procedures should provide for keeping the staff on a case-by-case basis.
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APPENDIX DEFINITIONS Acceleration Sensor. An instrument capable of safety of the public will remain functional. The value of sensing absolute acceleration and transmitting the data the OBE is set by the applicant.
to a remier.
Primary Containment. The principal structure of Accessible Instruments. Instruments or sensors a unit that acts as the barrier, after the fuel cladding and whose locations permit ready access de ; y plant oper-reactor pressure boundary, to control the release of ra-ation without violation of applicable safety regulations, dioactive material. The primary containment includes such as those of the Occupational Safety and Health (1) the containment structure and its access openings, Administration (OSHA) or regulations dealing with penetrations, and appurtenances, (2) the valves, pipes, plant security or radiation protection safety.
closed systems, and other components used to isolate the containment atmosphere from the environment, and Channel Calibration (Primary Calibration). The (3) those systems or portions of systems that, by their determination and, if required, adjustment of an instru.
ment, sensor, or system such that it responds within a system functions, extend the containment structure boundary (e.g., the connecting steam and feedwater specific range and accuracy to an acceleration, velocity, or displacement input, as applicable, or responds to an piping) and provide effective isolation.
acceptable physical constant.
Recorder. An instrument capable of simulta-Channel Check. The qualitative verification of neously recording the data versus time from an acceler-the functional status of the instrument sensor. This ation sensor or sensors.
check is an "in-situ" test and may be the same as a chan-Secondary Containment. The structure sur-nel functional test.
rounding the primary containment that acts as a further Channel Functional Test (Secondary Calibra-barrier to control the release of radioactive material.
l tion). The determination without adjustment that an in-Seism.ic Is lator. A device (for instance, lami-strument, sensor, or system responds to a known input nated elastomer and steel) installed between the struc-of such character that it will verify the instrument, sen-ture and its foundation to reduce the acceleration of the sor, or system is functioning in a manner that can be isolated structure, as well as the attached equipment calibrated.
and components.
Containment-See Primary Containment and Seismic Trigger. A device that starts the time-Secondary Containment.
history accelerograph.
Nonaccessible Instruments. Instruments or sen-sors in locations that do not permit ready access during Time Ilistory Accelerograph. An instrument ca-plant operation because of a risk of violating applicable pable of sensing and permaneatly recording the abso-lute acceleration versus time. The components of the plant operating safety regulations, such as OSHA, or regulations dealing with plant security or radiation pro-time-history accelerograph (acceleration sensor, re-corder, seismic trigger) may be assembled in a self-tection safety.
contained unit or may be separately located.
Operating Basis Earthquake Ground Motion (OBE). The vibratory ground motion for which those Triaxial. Describes the function of an instrument features of the nuclear power plant necessary for con-or group of instruments oriented in three mutually tinued operation without undue risk to the health and orthogonal directions, one of which is vertical.
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REGUIATORY ANALYSIS A separate regulatory analysis was not prepared for benefits (J the rule as implemented by the guide. A this regulatory guide. The regulatory analysis, "Revi-copy of the regulatory analysis is available for inspec-sion 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), Was'hington, tory basis for this guide and examines the costs and DC, as Attachment 7 to SECY-96-118.
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