Regulatory Guide 1.29

Seismic Design Classification

ML13350A385
Person / Time
Issue date:	02/28/1976
From:	NRC/OSD
To:
References
RG-1.029, Rev. 2
Download: ML13350A385 (3)

U.S. NUCLEAR REGULATORY COMMISSIONREGULATORY GUIDEOFFICE OF STANDARDS DEVELOPMENTREGULATORY GUIDE 129SEISMIC DESIGN CLASSIFICATIONRevision 2February 1976

A. INTRODUCTION

General Design Criterion 2, "Design Bases for Protec-tion Against Natural Phenomena," of Appendix A,"General Design Criteria for Nuclear Power Plants," to10 CFR Part 50, "Licensing of Production and Utiliza-tion Facilities," requires that nuclear power plantstructures, systems, and components important to safetybe designed to withstand the effects of earthquakeswithout loss of capability to perform their safetyfunctions.nuclear power plants that shouldstand the effects of the SSE. Jdesigned to with.AhLB. After reviewingstruction permitspressurized waterhas developed aidentifying pto withstana splqol plications for con-o ngj 'enses for boiling andc r plants, the NRC staff* "gn classification system forures that should be designedfec5 of the SSE. Those structumes,ents that should be designed toif the 4ZqIF n-t-vc ho rp, n vt.ei .SAppendix B, "Quality Assurance Criteria for Nuclear .-.. 1.Power Plants and Fuel Reprocessing Plants," to 10 CFR as~ic LategoryPart 50 establishes quality assurance requirements for

C. REGULATORY POSITION

the design, construction, and operation of nuclear powerplant structures, systems, and components that prevent e following structures, systems, and compo-or mitigate the consequences of postulated acc' n ts of a nuclear power plant, including their founda-that coubldc.aTe unuertisnto theqremntsof and of tions and supports, are designated as Seismic Category Iapply to all activeit ing the e safeqtu.imd and should be designed to withstand the effects of theapplyof those all rctivites, affeti ng the sfen SSE and remain functional. The pertinent qualitytions of those structures, systems, and conw~nents, assurance requirements of Appendix B to 10 CFR PartAppendix A, "Seismic and Geologic iSteria 50 should be applied to all activities affecting thefor Nuclear Power Plants," to 10 CFR Part 100, safety-related functions of these structures, systems, and"Reactor Site Criteria," requ that all nuclear power components.plants be designed so -the Safe ShutdownEarthquake (SSE) occurs, es, systems, and a. The reactor coolant pressure boundary.components import 0 remain functional.These plant featur h essary to ensure (1) b. The reactor core and reactor vessel internals.the integrity of th at oant pressure boundary,(2) the capab t the reactor and maintain c. Systems' or portions of systems that areit in a safe td'n ion, or (3) the capability to required for (1) emergency core cooling, (2) postacci-prevent or a. the consequences of accidents that dent containment heat removal, or (3) postaccidentcould result in tial offsite exposures comparable tothe guideline exposures of 10 CFR Part 100. The- system boundary includes those portions of the systemI~~~I4U.U ~ ~ ~ __r r.U "LAIIJUI -A ~.A~W I UI~UIThis guide describes an acceptable method of identi.fying and classifying those features of light.water.cooledter.q di~ to acopm )Ilie spmt w n~ onl aS ItIUIlconnected piping up to and including the first valve (including asafety or relief valve) that is either nornally closed or capableof automatic closure when the safety function is required.USNRC REGULATORY GUIDES should be sent to the secreary of the Commission. U.S aetlestRgulato*r, Gweiel are fted to desincribe end make evaible to th. ib~l. Regulatory Commission. Washongto,, 0 C 206. Attaenton Ooceotmg andmethods acceptable 1o the NRC %lell of Implementing specific pont of the Sartce SactonCommisson' regulations. to delineate techniques uled by the %I&" i ovoU The guides ar Issued , the following tor broad divsonsat1" sglif¢c peOblerns or poouleated accidents. or to proetsa jog.,dnce to soplfagultaorey Guides are not substitutes fat reiatraol.fs, and conpliance I Power Reactors 6 Prodvctewoth themr t not toqruied Methods and sOlutions ditferent from those tat Out on 2 Research and Tolt Reactors I 1tanspOrletDonthe guidaes wil be acceptable J9 they provide a bel fot the finding$ realusilt to 2 Fuels and Materals Facilities a Occupatiorel HMeaththe or conulruunce of a Permi or ocent. by the Commission 4 fnroonmenttl aend Sli.ng I AnttIuel ReviewComment. and tuggesttunt ofa ,rmproomeflls .n that* guides are encouraged S Mterial& and Plant Protection 10 Generalat elf troeS and g;dmi wIt be , a.led at sporopa 0o g odlat caommanl a end to *ettIct new ,injotornron or oopefence Ioweve. Comment, on Copoge of pubklshed guides may be obltme/d by wirltn request indicating IthIhis guide. 0t receiead Winhr.t About two months &latet ISluafnce. wilt be Par divisions desired to the U S Nuclear 0aegvletory Comigneitong. Washmtlon, 0 ClcumI' usefutl in evaluating the need fat arn *calI revlsion 2065. Altaenton Director. Office a9 Standl Oletevelopment containment atmosphere weanup (e.g., hydrogen re-moval system).d. Systems' or portions of systems that arerequized for (1) reactor shutdown, (2) residual heatremoval, or (3) cooling the spent fuel storage pool.e. Those portions of the steam systems of boilingwater reactors extending from the outermost contain-ment isolation valve up to but not including the turbinestop valve, and connected piping of 2-1/2 inches orlarger nominal pipe size up to and including nhe firstvalve that is either normally closed or capable ofautomatic closure during all modes of normal reactoroperation. The turbine stop valve should be designed towithstand the SSE and maintain its integrity.f. Those portions of the steam and feedwatersystems of pressurized water reactors extending fromand Including the secondary side of steam generators upto and Including the outermost containment isolationvulve, and connected piping of 2-1/2 inches or largernominal pipe size up to and including the first valve(including a safety or relief valve) that is either normallydosed or capable of automatic closure during all modesof normal reactor operation.g. Cooling water, component cooling, and auxil-iaty feedwater systems' or portions of these systems,including the intake structures, that are required for (1)emzerncy core cooling, (2) postaccident containmentheat removal, (3) postaccident containment atmospherecleanup, (4) residual heat removal from the reactor, or(5) cooling the spent fuel storage pool.h. Cooling water and seal water systems' orportions of these systems that are required for function-ing of reactor coolant system components important tosafety, such as reactor coolant pumps.I. Systems' or portions of systems that are re-quired to supply fuel for emergency equipment.j. All electric and mechanical devices and circuitrybetween the process and the input terminals of theactuator systems involved in gpnerating signals thatinitiate protective acUon.k. Systems' or portions of systems that arerequired for (I) monitoring of systems important tosafety and (2) actuation of systems important to safety.1. The spent fuel storage pool structure, includingthe fuel racks.m. The reactivity control systems, e.g., controlrods, control rod drives, and boron injection system.'See footnote 1, p. 1.29-1.n. The control room, including its associated vitalequipment, cooling systems for vital equipment, and lifesupport systems, and any structures or equipment insideor outside of the control room whose failure could resultin incapacitating Injury to the occupants of the controlroom.2o. Primary and secondary reactor containment.p. Systems,' other than radioactive waste manage-ment systems,3 not covered by itemns l.a through 1.oabove that contain or may contain radioactive materialand whose postulated failure would result in consrva-tively calculated potential offsite doses (using mete-orology as prescribed by Regulatory Guide 1.3, "As-sumptions Used for Evaluating the Potential Radio-logical Consequences of a Loss of Coolant Accident forBoiling Water Reactors," and Regulatory Guide 1.4,"Assumptions Used for Evaluating the Potential Radio-logical Consequences of a Loss of Coolant Accident forPressurized Water Reactors") that are more than 0.5 remto the whole, body or its equivalent to any part of thebody.q. The Class IE electric systems, including theauxiliary systems for the onsite electric power supplies,that provide the emergency electric power needed forfunctioning of plant features included in items l.athrough Lp above.2. Those portions of structures, systems, or compo-nents whose continued function is not required butwhose failure could reduce the functioning of any plnatfeature included in items La through l.q above to anunacceptable safety level should be designed and con-structed so that the SSE would not cause such failure.3. Seismic Category I design requuements shouldextend to the first seismic restraint beyond the definedboundaries. Those portions of structures, systems, orcomponents that form interfaces between Seismic Cate-gory I and non-Seismic Category I features should bedesigned to Seismic Category I requirements.4. The pertinent quality assurance requirements ofAppendix B to 10 CFR Part 50 should be applied to allactivities affecting the safety-related functions of thoseportions of structures, systems, and components coveredunder Regulatory Positions 2 and 3 above.*Lie indicate substantive changes from previous issue.'Wherever practical, structures and equipment whose failurecould possibly cause such injuries should be relocated orseparated to the extent required to eliminate this possibility.'Specific guidance on seismic requirements for radioactive wastemanagement systems is under development.I $I1.29-2

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D. IMPLEMENTATION

The purpose of this section is to provide informationto applicants regarding the NRC staff's plans for usingthis regulatory guide.proposes an acceptable alternative method for comply-ing with Tpecifled portions of the Commission's regula.tions, the method described herein is being and willcontinue to be used in the evaluation of submittals foroperating license or construction permit applicationsuntil this guide is revised as a result of suggestions fromthe public or additional staff review.IThis guide reflects current NRC staff practice. There.fore, except in those 'cases In 'which the applicant1.29.3