Regulatory Guide 1.61: Difference between revisions

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{{Adams
{{Adams
| number = ML070260029
| number = ML003740213
| issue date = 03/12/2007
| issue date = 10/31/1973
| title = Damping Values for Seismic Design of Nuclear Power Plants
| title = Damping Values for Seismic Design of Nuclear Power Plants
| author name =  
| author name =  
| author affiliation = NRC/RES/DFERR/DDERA/MSEB
| author affiliation = NRC/RES
| addressee name =  
| addressee name =  
| addressee affiliation =  
| addressee affiliation =  
| docket =  
| docket =  
| license number =  
| license number =  
| contact person = Graves HL (301)415-5880
| contact person =  
| case reference number = DG-1157
| document report number = RG-1.61
| document report number = RG-1.061, Rev. 1
| package number = ML070260020
| document type = Regulatory Guide
| document type = Regulatory Guide
| page count = 12
| page count = 2
}}
}}
{{#Wiki_filter:Stru ctures, sy stem s, and com po nent s of a nuclear pow er plant th at are designated as Seism ic Cate gory I are designed 1 to w iths ta nd the e f f ec ts of the s af e shut dow n e ar thqua k e (SS E) and re m ai n f unct iona l, se e Re g ula tory G uide 1.29,"S ei sm ic D es ig n Cl as si f ic at ion."A ppendi x S t o 10 C FR Part 50 a pplie s to a pplic ant s f or a de si g n c er tif ic at ion or c om bine d li ce nse purs uant to 2 10 CF R Par t 52, "Ea rly Sit e Perm its; St anda rd D es ig n Ce rti f ic at ions; a nd Com bine d L ic ens es f or N ucl ea r Pow er Plant s,"or a constru ction perm it or op erating license pu rsuant to 10 CFR P art 50 af ter Ja nu ary 10, 199 7.  Howe ver, f or either an op era ti n g li cen se ap p li can t o r h o ld er who se co n st ru ct io n pe rmit w as i ssu ed be for e Jan u ary 10 , 1 9 9 7 , t h e ear th q u ake e n g i n e e r i n g c r i t e r i a i n S e c t i o n V I o f Ap p e n d i x A t o 1 0 C F R P a r t 1 0 0 c o n t i n u e t o a p p l y.T h e U.S. N u c le a r R e g u la to ry C o m m is s io n (N R C) i s s u e s re g u la to ry g u id e s to d e s c rib e a n d m a k e a v a il a b le to th e p u b li c m e th o d s th a t t h e N R C s ta ff con si der s acc ept abl e f or us e i n i m pl em ent i ng spe ci f i c par t s of t he age ncy's r egu l at i ons , t ech ni que s t hat t he st af f us es i n e val uat i ng spe ci f i c pr obl em s or po st ul at ed acc i den t s, an d d at a t hat t he st af f ne ed i n r evi ewi ng app l i cat i ons f or pe r m i t s and l i cen ses.  Regul at or y gu i des ar e n ot s ubs t i t ut es f or r egu l at i ons , an d c om pl i anc e wi t h t hem i s not r equ i r ed.  Met hod s and s ol ut i ons t hat di f f er f r om t hos e s et f or t h i n r egu l at or y gu i des wi l l be de em ed acc ept abl e i f t hey pr ovi de a b asi s f or t he f i ndi ngs r equ i r ed f or t he i ss uan ce or c ont i nua nce of a per m i t or l i cen se by t he C om m i ss i on.T hi s gui de was i ss ued af t er c ons i der at i on of c om m ent s r ece i ved f r om t he pub l i c.  The N R C s t af f en cou r age s and wel com es com m ent s and s ugg est i ons in c o n n e c ti o n w it h i m p ro v e m e n ts to p u b li s h e d re g u la to ry g u id e s , a s w e ll a s i te m s fo r i n c lu s io n i n re g u la to ry g u id e s th a t a re c u rre n tl y b e in g d e v e lo p e d. T h e N R C s ta ff w il l re v is e e xis ti n g g u id e s , a s a p p ro p ria te , t o a c c o m m o d a te c o m m e n ts a n d to re fl e c t n e w i n fo rm a ti o n o r e xp e rie n c e.  W rit te n c o m m e n ts m ay be s ubm i t t ed t o t he R ul es and D i r ect i ves Br anc h, O f f i ce of Adm i ni st r at i on, U.S. N ucl ear R egu l at or y C om m i ss i on, W ash i ngt on, D C 20 555-000 1.R egul at or y gui des ar e i ssued i n 10 br oad di vi si ons:  1, P ow er R eact or s; 2, R esear ch and T est R eact or s; 3, Fuel s and M at er i al s Faci l i t i es;4, Env i r on m en t al a nd Si t i ng; 5 , Ma t er i al s a nd Pl an t Pr ot ec t i on; 6 , Pr od uc t s; 7 , Tr an s po r t at i on; 8 , Occ up at i on al Hea l t h; 9 , Ant i t r us t a nd F i na nc i al Rev i ew;a n d 1 0 , G e n e ra l.R equ est s f or s i ngl e c opi es of dr af t or ac t i ve r egu l at or y gu i des (whi ch m ay be r epr odu ced) s hou l d b e m ade t o t he U.S. N ucl ear R egu l at or y C om m i ss i on, W ash i ngt on, D C 20 555 , At t ent i on: R epr odu ct i on and D i st r i but i on S er vi ces Sect i on, or by f ax t o (301) 41 5-228 9; or by em ai l t o D i st r i but i on@nr c.gov. E l ect r oni c cop i es of t hi s gui de and ot her r ece nt l y i ss ued gu i des ar e a vai l abl e t hr oug h t he N R C's pub l i c W eb si t e u nde r t he R egu l at or y G ui des do cum ent c o ll e c ti o n o f t h e N R C's E le c tro n ic R e a d in g R o o m a t ht t p://w w w.nr c.gov/r eadi ng-r m/doc-col l ect i ons/ a n d th ro u g h th e N R C's A g e n c yw id e D o c u m e n ts A c c e s s a n d M a n a g e m e n t S ys te m (A D A M S) a t h ttp://w w w.n rc.g o v/re a d in g-rm/a d a m s.h tm l, un der Acces si on N o. ML0702 600 29.U.S. N UC LEA R RE GU LA TO RY C OM MI SSIO N
{{#Wiki_filter:flitntwr 10721
M ar ch 2007 R ev i si on 1 RE GUL AT ORY GUI DE OFFICE OF NUCL
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EA R REGULA TORY RESEA RCH R E G U LA TO R Y G U I D E 1.61 (D r af t w as i ssued as DG-1157, dat ed O ct ober 200 6)DA MPI NG VA L UE S F OR SE I SMI C D ES I GN O F N U C LE A R P O W E R P LA N TS A.  INT ROD UC TIONThis reg ulatory g uide is bein g rev ised to up date th e g uidanc e for applican ts and licens ees reg arding the acceptab le dam ping v alues that the U.S. N uclear Reg ulatory C om m ission (NR C) staff use d in the seism ic resp onse analy sis of Seism ic C ateg ory I nu clear p owe r plan t structu res, sy stem s, 1 and com pone nts (S SC s) in accord ance with Title 10, Part 5 0, of the Cod e of Fede ral R egulatio ns (1 0 C F R P ar t 5 0), "D om es ti c L ic en si ng o f P ro du ct io n an d U ti li z at io n F ac il it ie s" [R ef. 1].Spec ifically , G eneral Desig n C riterion 2 , "Desig n B ases fo r Pro tection Ag ainst N atural P heno m ena,"of A ppen dix A , "Gen eral D esig n C riteria for Nuc lear P owe r Plan ts," to 10 C FR Pa rt 50 requires that SSC s im portant to safe ty be desig ned to w ithstand the effe cts of natural phen om ena such as ea rthquak es witho ut los ing the ability to perform their safety fun ctions.  S uch SSC s m ust also be desig ned to a cc om m od at e th e ef fe ct s of a nd b e co m pa ti bl e w it h th e en v ir on m en ta l c on di ti on s as so ci at ed w it h norm al op eration and postula ted ac cidents.  A ppen dix S , "Earthq uak e E ng ineering C riteria for Nuc lear Po we r Pl a nt s ," to 10 CFR Pa r t 50 sp e c i f i e s th e re qu i r e men t s fo r th e impl e men t a t i on of Ge ne r a l De s i gn Criterion 2 with respect to earth quak es.2 Rev. 1 of RG 1.61, Pa g e 2Thi s re g ul at or y g ui de s pe ci fi es th e da m pi ng v al ue s th at th e N R C s ta ff c on si de rs a cc ep ta bl e for co m ply ing w ith the ag ency's reg ulations and g uidanc e for seism ic ana ly sis.  The sp ecified dam ping v alues are inte nded for elastic m odal dy nam ic seism ic ana ly sis w here energ y dissip ation is acco unted for by v is co us d am pi ng (i.e., th e da m pi ng f or ce is p ro po rt io na l t o th e v el oc it y).Thi s re g ul at or y g ui de c on ta in s in fo rm at io n co ll ec ti on s th at a re c ov er ed b y th e re qu ir em en ts of 1 0 C FR Pa rt 50, w hich the O ffice of Manag em ent an d B udg et (O MB) a pprov ed u nder OMB con trol num ber 3 150-0011.  The NR C m ay neith er co nduc t nor spon sor, and a pe rson is no t requ ired to respo nd to, an in fo rm at io n co ll ec ti on r eq ue st o r re qu ir em en t u nl es s th e re qu es ti ng d oc um en t d is pl ay s a cu rr en tl y v al id O MB c on tr ol n um be r.B.  DISC US SION Bac kgr oundD am pi ng is a m ea su re o f th e en er g y d is si pa ti on o f a m at er ia l o r st ru ct ur al s y st em a s it r es po nd s to dy nam ic exc itation.  I t is a term use d to assist in m athem atically m odeling and solv ing dy nam ic equ ations of m ot io n fo r a v ib ra to ry s y st em in w hi ch e ne rg y is d is si pa te d.  W he n pe rf or m in g a n el as ti c dy na m ic seism ic ana ly sis, one can accou nt for the en erg y dissip ated b y spe cify ing the am ount of v iscous dam ping (i.e., d am pi ng f or ce p ro po rt io na l t o th e v el oc it y) in th e an al y ti ca l m od el.C ur re nt N R C g ui da nc e on d am pi ng v al ue s to b e us ed in th e el as ti c de si g n of n uc le ar p ow er p la nt s is pres ented in this reg ulatory g uide, w hich was first issued in Octo ber 1 973 [Ref. 2].  L ik e the orig inal ver s i on of th i s gui de , t hi s re vis i on sp e c i f i e s eq ui val e nt vis c ou s m od a l da mpi ng val ue s as a p e r c e nt a ge of critical dam ping for Seism ic C ateg ory I SS Cs.  H owe v er, the sta ff base d the orig inal d am ping v alues on li m it ed da ta , expe rt opin ion , and ot her inf ormati on avail abl e in 19 73.  Sinc e tha t ti m e, th e NRC an d in du st ry h av e be en in v ol v ed in v ar io us s tu di es , r es ea rc h w or k , a nd te st in g to p re di ct a nd e st im at e dam ping v alues of S SC s.  I n v iew of the av ailable d ata, the d am ping v alues prov ided in the orig inal v ersion of R eg ulatory G uide 1.6 1 m ay no t reflect realistic da m ping v alues for S SC s.  A lso, it is rec og niz ed that ad ditional g uidanc e is neede d to address issue s, such as co rrelation betw een dam ping and structu res stress lev el, a nd dam ping v alues for m aterials n ot inc luded in the orig inal v ersion of R eg ulatory G uide 1.6 1 (e.g., e le ct ri ca l d is tr ib ut io n sy st em s an d re in fo rc ed m as on ry s tr uc tu re s).Ov er the past th ree d ecades , th e nu clear in dustry has pro posed dam ping v alues and discuss ed these v alues during v arious m eeting s an d rev iews of licen sing issue s.  N uclear industry g roups and licensees ha v e su g g es te d th at th e N R C o ug ht to a cc ep t m or e re al is ti c da m pi ng v al ue s fo r se is m ic d es ig n an d an al y si s of S SC s, in pla ce o f the dam ping v alues prov ided in the orig inal R eg ulatory G uide 1.6 1.St r uc tu r al D am pingI n 1 993, the NR C com pleted an in v estig ation of the ade quacy of orig inal R eg ulatory G uide 1.6 1 structure dam ping v alues and other recom m endatio ns, and reported the results in N UR EG/CR-6011 [R ef. 3]. Data were analy z ed to iden tify the param eters tha t sig nificantly influe nced structure dam ping.  Base d o n t ha t st ud y, t he NRC de t e r min e d t ha t th e or i gin a l Re gul a t or y Gui de 1.61 da mpi ng val ue s fo r st r uc t ur e de s i gn were adequ ate bu t requ ired o ne s ig nificant rev ision.  S pecifically , R eg ulatory G uide 1.6 1 sh ould disting uish betw een "friction- bolted" and "be aring-bolted" con nection s for steel stru ctures.  F riction-bolted conn ections a r e al s o r e f e r r e d t o a s "s l i p-cr i t i c a l" co nn e c t i on s.  I n t he s e co nn e c t i on s , t he bo l t pr e l oa d i s hi gh e no ugh to e ns ur e th at f ri ct io n is n ot o v er co m e, a nd th e bo lt d oe s no t e xp er ie nc e sh ea r lo ad in g.  R eg ul at or y Position 1 in S ection C of this rev ised g uide prov ides th e up dated structural dam ping v alues.
U.S. ATOMIC ENERGY COMMISSION
REGULATORY GUIDE
DIRECTORATE OF REGULATORY STANDARDS
REGULATORY GUIDE 1.61 DAMPING VALUES FOR SEISMIC DESIGN OF NUCLEAR POWER PLANTS


Rev. 1 of RG 1.61, Pa g e 3 P iping Da m pingI n 1 986, the Am erican Society of Mechanica l En g ineers (AS ME) esta blished C ode Case N-411,"A l t e r n a t i ve Da mp i n g V a l u e s f o r Re s p o n s e Sp e c t r a An a l ys i s o f Cl a s s 1 , 2 , a n d 3 Pi p i n g," i n Se c t i o n I II , Div ision 1, of the A SME Boiler and Pressu re Vessel C
==A. INTRODUCTION==
ode [Ref. 4].  The NR C staff use d C ode Case N-411, with certain lim itations specified in R eg ulatory G uide 1.8 4 [R ef. 5], to rev iew operatin g reacto r issue s until C ode Case N-411 expired in 2000.  The staff also app rov ed th e us e of alternate dam ping v alues for the G eneral Electric Adv anced B oiling Water R eactor Desig n in 1994 [R ef. 6], Com bustion En g ineering S y st em 8 0+ D es ig n in 1 99 2 [R ef. 7], a nd We st in g ho us e A P 60 0 D es ig n in 1 99 8 [R ef. 8].  R eg ul at or y Position 2 in S ection C of this rev ised g uide prov ides th e pip ing dam ping v alues that resu lted from the sta ff's exp erience with AS ME C ode Case N-411 and app lication rev iews of n ew reactor desig ns.Ele c tr ic al D ist r ibut ion Sys te m Da m pingReg ulatory G uide 1.6 1 d id no t orig inally pro v ide d am ping v alues for cab le tray or cond uit sy stem s. H is to ri ca ll y , th e nu cl ea r po w er in du st ry u se d th e da m pi ng v al ue s fo r bo lt ed s te el s tr uc tu re s fo r se is m ic de si g n of c ab le tr ay a nd c on du it s y st em s.  I n th e la te 1 98 0s , h ow ev er , th e N R C s ta ff r ev ie w ed th e re su lt s of the cab le tray test at the Com anche Pe ak Stea m Ele ctrical S tation [R ef. 9].  R eg ulatory Po sition 3 in S ection C of this rev ised g uide prov ides th e da m ping v alues that resu lted from the staff's rev iew of d at a fr om th e C om an ch e P ea k te st [R ef. 1 0] a nd tw o sa fe ty e v al ua ti on r ep or ts [R ef s. 9 , 1 1].He at ing Ve nt ila ti on a nd A ir Co ndit ion ing Duc t D am pingThe dam ping v alues for he ating v entilation and air con ditioning (H VAC) sy stem s are consisten t with the g uidanc e pro v ided for bo lted stee l structu res.  B ecause no tests of w elded duct constru ction ha v e be en id en ti fi ed , th e da m pi ng v al ue s ar e th e sa m e as f or w el de d st ee l s tr uc tu re s, a nd R eg ul at or y Posi ti on 4 in Se ct ion C of thi s re vised g uid e pro vides thes e same dam pin g values.  I n addi ti on, th e NRC prov ides re lated in form ation on HVAC du ct dam ping in NU RE G/C R-6919 , "Reco m m endatio ns fo r R ev is io n of S ei sm ic D am pi ng Va lu es in R eg ul at or y G ui de 1.61" [R ef. 1 2].M e c hani c al a nd Ele c tr ic al C om pone nt Da m pingNU RE G/C R-6919 [R ef. 12] consid ers g uidanc e in Am erican Society of Civ il En g ineers (AS CE)Stand ard 4 3-05, "S eism ic D esig n C riteria for Structu res, Sy stem s, and Com pone nts in N uclear Facilities"
Criterion 2, "Design Bases for Protection Against Natural Phenomena," of Appendix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50,  
[Ref. 13], a nd Non-Mandatory A ppen dix N , "Dy nam ic A naly sis Metho ds," to Section I I I , D iv ision 1, of the A SME Boiler & Pressu re Vessels Cod e [R ef. 14].  I n ad dition, N UR EG/CR-6919 [R ef. 12]prov ides re com m endatio ns a nd com m entary on dam ping v alues for (1) contain m ent stru ctures, contain m ent in ternal stru ctures, and othe r Se ism ic C ateg ory I structu res; (2) piping; (3) electrical distribution sy stem s (i.e., cable tray or cond uit sy stem s); (4) HVAC; and (5) m echan ical an d elec trical com pone nts.  R eg ulatory Po sition 5 in Section C of this rev ised g uide prov ides th e da m ping v alues that resu lted from the staff's rev iew of this industry g uidanc e.
"Licensing of Production and Utilization Facilities,"  
requires, in part, that nuclear power plant structures, systems, and components important to safety be designed to withstand the effects of earthquakes.


Rev. 1 of RG 1.61, Pa g e 4 C.  R EGU LAT ORY PO SITIONThe f ol lo w in g r eg ul at or y p os it io ns p ro v id e ac ce pt ab le d am pi ng v al ue s to b e us ed in th e el as ti c dy nam ic seism ic ana ly sis an d d esig n o f SS Cs, w here energ y dissip ation is app roxim ated b y v iscous dam ping unless otherw ise sp ecified. D am ping v alues hig her th an th ose prov ided m ay be used if doc um ented te st d at a su pp or t t he h ig he r v al ue s. D am pi ng v al ue s as so ci at ed w it h so il-st ru ct ur e in te ra ct io n an al y si s are n ot w ithin th e sco pe o f this reg ulatory g uide.1.
Proposed Appendix A, "Seismic and Geologic Siting Criteria," to 1OCFR Part 100, "Reactor Site Criteria:'
would require, in part, that suitable seismic dynamic analysis, such as a time-history or spectral response
.analysis, be performed to demonstrate that the structures, systems, and components important to safety will remain functional in the event of a Safe Shutdown Earthquake (SSE). This guide delineates damping values acceptable to the AEC Regulatory staff to be used in the elastic modal dynamic seismic analysis of Seismic Category IP structures, systems, and components. The Advisory Committee on Reactor Safeguards has been consulted concerning this guide and has concurred in the regulatory position.


St r uc tu r al D am ping 1.1 Acce ptab le Str uctu ral D amping V alues f or C onta inment Stru ctures, Con tainment Intern al S tructu res, and Other Seismic C atego ry I Str uctu res 1.1.1 Saf e-Shut down Ear thq uake (SSE)Table 1 prov ides a cceptab le dam ping v alues for the SS E a naly sis.Tab le 1. S SE D amping V alues St ru ct ur al M at er i al D ampi ng (% of C ri t i cal D am p i ng)Rei n f or ce d Conc r et e
==B. DISCUSSION==
7%Rei n f or ce d M as on r y
The energy dissipation within a structure due to material and structural damping while it is responding to an earthquake depends on a number of factors such as types of joints or connections within the structure, the structural material, and the magnitude of deformations experienced. In a dynamic elastic analysis, this energy dissipation usually Is accounted for by specifying an amount of viscous damping that would result in energy
7%Pre s t r es s ed Conc r et e
5Structures, systems, and components of a nuclear power plant that are designated as Seismic Category I are designed to withstand the effects of the Safe Shutdown Earthquake (SSE)  
5%W el ded St ee l or B ol t ed St ee l w i t h Fr i ct i on Conn ec t i on s
and remain functional (see Regulatory Guide 1.29, "Seismic Design Classification").
4%B ol t ed St ee l w i t h B ea r i n g Conn ec t i on s
dissipation in the analytical model equivalent to that expected to occur as a result of material and structural damping in the real structure.
7%Note:
For steel structures w ith a com bin ation of diff erent conn ection ty pes, use the lowe st specif ied dam pin g v alue, or as an alternative, use a "w eighted av erag e" dam pin g v alue based on th e num ber of e ach ty pe present in th e structure.


1.1.2 Oper ati ng-Basi s Eart hquak e (OBE)I f th e de si g n-ba si s O B E g ro un d ac ce le ra ti on is s el ec te d to b e le ss th an o r eq ua l t o on e-th ir d of th e de si g n-ba si s S S E g ro un d ac ce le ra ti on , th en a s ep ar at e O B E a na ly si s is n ot r eq ui re d.  H ow ev er , if th e de si g n-ba si s O B E g ro un d ac ce le ra ti on is s el ec te d to b e g re at er th an o ne-th ir d of th e de si g n-ba si s S S E g ro un d ac ce le ra ti on , th en a s ep ar at e O B E a na ly si s sh ou ld b e co nd uc te d.  Ta bl e 2 pr ov id es a cc ep ta bl e dam ping v alues for the O BE ana ly sis.Tab le 2. OBE D amping V alues St ru ct ur al M at er i al D ampi ng (% of C ri t i cal D am p i ng)Rei n f or ce d Conc r et e
After reviewing a number of applications for.
4%Rei n f or ce d M as on r y
4%Pre s t r es s ed Conc r et e
3%W el ded St ee l or B ol t ed St ee l w i t h Fr i ct i on Conn ec t i on s
3%B ol t ed St ee l w i t h B ea r i n g Conn ec t i on s
5%
Rev. 1 of RG 1.61, Pa g e 5 1.2 Spe cial C onsid eration for In-S tructu re R espo nse Spe ctra Gen erationThe SS E d am ping v alues specified in Table 1 for linear d y nam ic ana ly sis of structures hav e be en s elected based on the expec tation th at the structural respon se attribu ted to load com bination s that inc lude SSE w ill be close to ap plicable code stress lim its, a s de fined in S ection 3.8 of NU RE G-0800[R ef. 1 5].How ev er, there m ay be cases whe re the predicted structu ral resp onse to loa d co m bination s that inc lude SSE is s ig nificantly belo w the ap plicable code stress lim its.  Beca use equiv alent v iscous da m pi ng r at io s ha v e be en s ho w n to b e de pe nd en t o n th e st ru ct ur al r es po ns e le v el , it is n ec es sa ry to co nsider that the SS E d am ping v alues specified in Table 1 m ay be incons istent w ith the predicted st ru ct ur al r es po ns e le v el.For structural ev aluation, this is no t a c oncern , b ecause the stresses resulting from the use of d am ping-com patible structural respon se w ill still be less tha n the app licable c ode stress lim its, as d ef in ed in S ec ti on 3.8 of N U R E G-08 00 [R ef. 1 5].H ow ev er , f or in-st ru ct ur e re sp on se s pe ct ra g en er at io n, it is n ec es sa ry to u se th e da m pi ng-co m pa ti bl e structural respon se.  C onseq uently , th e follo wing add itional g uidanc e is prov ided for an aly ses u sed to de term ine in-structure respon se sp ectra: (1)
U se th e O B E d am pi ng v al ue s sp ec if ie d in Ta bl e 2, w hi ch a re a cc ep ta bl e to th e st af f wit hout fur the r re view.(2)
Sub m it a p lant-specific technica l basis for us e of dam ping v alues hig her th an th e O BE dam ping v alues specified in Table 2 , b ut no t g reater tha n the SS E d am ping v alues specified in Table 1 (e.g., see N UR EG/CR-6919 , S ection 3.2.3), sub j ect to staff rev iew on a cas e-by-case basis.I n g en er al , f or c er ti fi ed s ta nd ar d pl an t d es ig ns w he re th e de si g n-ba si s in-st ru ct ur e re sp on se s pe ct ra represen t the env elope of the in-structure respon ses o btained from m ultiple a naly ses co nduc ted to c on si de r a ra ng e of e xp ec te d si te s oi l c on di ti on s, it is n ot n ec es sa ry f or c om bi ne d li ce ns e ap pl ic an ts to ad dress this issu e.  H owe v er, if plan t-specific seism ic ana ly ses are con ducted for Categ ory I structu res and/or structures not in cluded as part o f the standard plan t desig n, then the ap plicant is exp ected t o a dd r e s s th i s is s ue ac c or di ngl y.


Rev. 1 of RG 1.61, Pa g e 6 2.
construction permits and operating licenses and after reviewing pertinent literature including Reference I, the AEC Regulatory staff has determined as acceptable, for interim use, the modal damping values shown in Table I
of this guide. These modal damping values should be used for all modes considered in elastic spectral or time-history dynamic analyses. Values are tabulated for the two earthquakes, the Safe Shutdown Earthquake and the Operating Basis Earthquake (or % the Safe Shutdown Earthquake), for which nuclear power plants are required to be designed as specified in proposed Appendix A to 10 CFR Part 100, "Seismic and Geologic Siting Criteria."


P iping Da m pingTable 3 presents the constan t dam ping v alues specified for S SE and OB E (w here required)analy ses o f pipin g sy stem s. These v alues are ap plicable to tim e-history , re spon se sp ectra, and equiv alent s tatic ana ly sis pro cedure s for structural qualification
==C. REGULATORY POSITION==
.T ab le 3.  D am p in g V al u es for Pip in g S ys te ms C ategory D ampi ng V al ue S S EO B E > S S E/3 Pi pi n g S y s t e ms 4%3%As an a lternativ e for respon se sp ectrum ana ly ses u sing an env elope of the SS E o r O BE respo nse spe ct ra at al l su ppor t poi nts (uni for m suppo rt m oti on), fre que ncy-dep end ent dam pin g values shown in F ig ure 1 m ay be used, sub j ect to the fo llowin g restriction s:*
1. The modal damping values expressed as a percentage of critical damping shown in Table I of this guide should be used for viscous modal damping for all modes considered in an elastic spectral or time-history dynamic seismic analysis of the Seismic Category I structures or components specified in the table. The modal damping values specified in Table I are for use in the dynamic analyses associated with two different magnitudes of earthquakes, the Safe Shutdown Earthquake and the Operating Basis Earthquake (or % the Safe Shutdown Earthquake). These analyses would be required by proposed Appendix A to 10 CFR Part 100, "Seismic and Geologic Siting Criteria."
Frequ ency-depen dent dam ping sho uld b e us ed c om pletely and con sistently , if at all. (Dam ping v alues specified in R eg ulatory G uide 1.6 1 are to be u sed for eq uipm ent other than piping.)*
2. Damping values higher than the ones delineated in Table 1 of this guide may be used in a dynamic seismic analysis if documented test data are provided to support higher values.
Use of the spe cified d am ping v alues is lim ited o nly to respon se sp ectral an aly ses. Acce ptance of the use of the sp ecified dam ping v alues with other ty pes of d y nam ic ana ly ses (e.g., tim e-history ana ly ses o r inde pend ent su pport m otion m ethod) requires further j ustification.


*
USAEC REGULATORY GUIDES
When used for reco nciliation or su pport optim iz ation of ex isting des ig ns, the effe cts of increased m otion on existing clearan ces a nd online m ounted equ ipm ent sh ould be c heck ed.*
C
Frequ ency-depen dent dam ping is n ot ap propriate for an aly z ing the dy nam ic resp onse of p iping s yst e ms us i ng s up po r t s de s i gne d t o d i s s i pa t e en e r gy by yi e l di ng.*
e o d guide w be obtai ed by request Iicamtin the divilsons dlmired to the US. Atomic Energy Commisson. Wshington. D.C. 205M.4 Reguhtmy Guides ra Issued to descrbe and muks sieithbi, to she public Attention: Diector of Regulatory StandardL. Comm*nts end egstflom ftr amuhods ecaptable to the AEC Regultory 8taf of kplementinM qWedfic iWt of Irnprosyents hI thne- guides am encouraged end ehould be eant to the Semetary Vd Conwidwion'
Frequ ency-depen dent dam ping is n ot ap plicable to pip ing in whic h stres s co rrosion crack ing ha s oc cu rr ed , u nl es s a ca se-sp ec if ic e v al ua ti on is p ro v id ed a nd r ev ie w ed a nd f ou nd a cc ep ta bl e by th e N R C s ta ff.
regulations, to deilnete tahniques wmd by th sff in of the Comnmikson. US. Aom: Eney Comitsion. Washington. D.C. 20545, evaluating qecific problems or Postubted ecalm"
. or to Provide guldnm to Attantlo- Chief. Public Pro*
dings StEff.


Rev. 1 of RG 1.61, Pa g e 7 3.
applicent I
Guides em rot substitutes for regulatious and compliance with dmu is not uequired. Methodeand solutions diffagnt foron hse aut In The igde am Iasued In the following un broad divisions:
the =uide will be acctable I they provido a Emi. f the ndlgt pPquoRtaetactor the Isuacor tonthtnnce of apermit or 1E,  
e bythe Cconisson.


Ele c tr ic al D ist r ibut ion Sys te m Da m pingTable 4 presents the constan t dam ping v alues specified for S SE and OB E (w here required)an al y se s of c ab le tr ay a nd c on du it s y st em s.  Th es e v al ue s ar e ap pl ic ab le to r es po ns e sp ec tr a and equiv alent s tatic ana ly sis pro cedure s for structural qualification.  The dam ping v alues specified in Table 4 are applicab le to all ty pes of su pports, inclu ding w elded supp orts.  The us e of hig her d am ping val ue s fo r ca bl e tr a ys wi t h f l e xi bl e su pp or t sys t e ms (e.g., r od-hu ng t r a pe ze s yst e ms, st r ut-hu ng t r a pe ze sy st em s, a nd s tr ut-ty pe c an ti le v er a nd b ra ce d ca nt il ev er s up po rt s y st em s) is p er m is si bl e, s ub ject to obtainin g N RC rev iew for acc eptance on a case-by-case basis.The analy sis m ethodo log y sho uld c onside r the flexibility of supp orts in determ ining the sy stem respon se to seism ic exc itation.
1.


Rev. 1 of RG 1.61, Pa g e 8 T ab le 4.  D am p in g V al u es for E le ct ri ca l D is tr ib u ti on S ys te ms C ategory D ampi ng V al ue S S EO B E > S S E/3 C abl e Tray Syst em 4 M axi m um C ab l e Lo ad i ng 1 E m p ty 2 Spray ed-on Fi r e Ret ar dant or ot her ca b l e-restraini ng m ec ha nism 3 10%7%7%7%5%5%C on du i t S ys t e ms 4 M a x im u m C a b le fi ll 1 E m p ty 2 7%5%5%3%Notes: 1.
eRasc to
6. Pro1dts
2. Re- rdi and Test Reactors


Maxim um ca ble load ings, in accordance w ith th e plant design specif ication , are to be utilized in con jun ction w ith th ese dam pin g v alues.2.
===7. Tranportatin ===
3. Fuesk end Materials Facilities L. Ociaetol Health published =ud~ will be eavied perlodlcey. a @pproprim


Spa re c abl e tra y a nd c onduit, ini tia lly e m pty , m ay be a nal y ze d w ith ze ro c abl e loa d a nd the se da m ping v al ues. (Not e:  R e-ana ly si s is e x pec te d w hen put i nto s er v ic e.)3.
====t. so accommnodate ====
4. En~omientul end Siting L.AttutRve wetnronts and t s  
afetnw inforautios or experience.


Res tr ai n t o f th e free re la ti ve m o vement of th e cab le s in si d e a tr ay red u ces t h e system dampi n g.4.
L Msatralsi and Plant Protection
10. General p.


W hen ca ble loa ding s of le ss-tha n m ax im um a re s pec if ie d f or de si g n c al cul at ions , t he appl ic ant or licensee is e xpected to justify the selec ted dam pin g v alues and ob tain NRC rev iew f or acce ptan ce on a c ase-by-case basis.4.
3.


He at ing , V e nt ila ti on, and A ir Co ndit ion ing Duc t D am pingTable 5 presents the constan t dam ping v alues specified for S SE and OB E (w hen required)analy ses o f H VAC duct sy stem s.  These v alues are ap plicable to resp onse spectra and equiv alent static an aly sis pro cedure s for structural qualification
If the maximum combined stresses due to static, seismic, and other dynamic loading are significantly lower than the yield stress and % yield stress for SSE and  
.The analy sis m ethodo log y m ust co nsider the flex ibility of supp orts in determ ining sy stem respon se to seism ic exc itation.T ab le 5.  D am p in g V al u es for HV A C D u ct S ys te ms Type of D uc t C ons t ru ct i on D ampi ng V al ue S S EO B E > S S E/3 Pock et Loc k10%7%Compan i on An g l e7%5%W el ded4%3%
% SSE, respectively, in any structure or component, damping values lower than those specified in Table I of this guide should be used for that structure or component to avoid underestimating the amplitude of vibrations or dynamic stresses.
Rev. 1 of RG 1.61, Pa g e 9 5.


M e c hani c al a nd Ele c tr ic al C om pone nt Da m pingTab le 6 p re se nt s th e da m pi ng v al ue s fo r m ec ha ni ca l a nd e le ct ri ca l c om po ne nt s, w hi ch a re ap pl ic ab le to p as si v e su bc om po ne nt s th at c an b e se is m ic al ly q ua li fi ed b y a na ly si s. A ct iv e su bc om po ne nt s do n ot r ea di ly le nd th em se lv es to s ei sm ic q ua li fi ca ti on b y a na ly si s, a nd r eq ui re q ua li fi ca ti on b y te st , as d es cr ib ed in S ec ti on 3.10 o f N U R E G-08 00 [R ef. 1 5].T ab le 6. D am p in g V al u es for Me ch an ic al a n d E le ct ri ca l C om p on en ts C ompone nt Type D ampi ng V al ue S S EO B E > S S E/3 M o t o r, Fan, and C
TABLE 1 DAMPING VALUES'
o m p res sor H o usi ngs (p ro te c tio n , stru c tur a l sup p o rt)3%2%P ressu re V esse l s, H ea t E xc ha ng ers, an d P um p an d V alve B o d i es (p re ssu re b o u n d a ry)3%2%W el d ed Ins t rume nt R acks (s tru c tur a l sup p o rt)3%2%El ec t r i ca l Cabi n et s , Pan el s , a n d M ot or C o ntro l C en t ers (M C C s)(p ro te c tio n , stru c tur a l sup p o rt)3%2%M et al A t m o spheri c Storage T
(Percent of Critical Damping)
anks (contai nm ent , pro t ect i o n) - I mpu l s i v e M ode - Sl os h i n g M ode 3%0.5%2%0.5%
Operating Basis Earthquake or % Safe Safe Shutdown Structure or Component Shutdown EarthquakeD
Rev. 1 of RG 1.61, Pa g e 10 D. IMP LEM ENT ATIONThe purp ose of this section is to prov ide in form ation to ap plicants and licensees reg arding th e N R C s ta ff's p la ns f or u si ng th is r eg ul at or y g ui de. N o ba ck fi tt in g is in te nd ed o r ap pr ov ed in conn ection with the issu ance of this g uide.Exce pt in those cases in w hich an a pplican t or licensee propo ses o r has prev iously estab lished an a cceptab le alterna tiv e m ethod for co m ply ing w ith sp ecified portion s of the N RC's reg ulations, th e N R C s ta ff w il l u se th e m et ho ds d es cr ib ed in th is g ui de to e v al ua te (1) s ub m it ta ls in c on ne ct io n w it h applicatio ns fo r con struction perm its, sta ndard plan t desig n ce rtifications, op erating licens es, early site perm its, a nd com bined licenses;
Earthquake Equipment and large-diameter piping systems',  
and (2) su bm ittals from op erating reacto r license es who v oluntarily pro pose to initiate sy stem m odification s if th ere is a clear nexu s be tween the propo sed m odification s an d the sub j ect for whic h g uidanc e is prov ided herein.R EG U LA TO R Y A N A LY SI S / B A C KF IT A N A LY SI SThe r eg ul at or y a na ly si s an d ba ck fi t a na ly si s fo r th is r eg ul at or y g ui de a re a v ai la bl e in Draft Reg ulatory G uide DG-1157 , "Dam ping Values for S eism ic D esig n o f N uclear Pow er P lants"(R ef. 1 6).  Th e N R C is su ed D G-11 57 in O ct ob er 2 00 6 to s ol ic it p ub li c co m m en t o n th e dr af t o f th is Rev ision 1 o f R eg ulatory G uide 1.6 1.
pipe diameter greater than 12 In. ...........  
2  
3 Small-diameter piping systems, diameter equal to or less than 12 in. ....................
1
2 Welded steel structures ...................
2  
4 Bolted steel structures ...................  
4
7 Prestressed concrete structures .............  
2  
5 Reinforced concrete structures ............  
4
7
'Table 1 is derived from the recommendations given In Reference 1.


A ll NR C r eg ula tions li st ed her ei n a re a v ai la ble e le ct ronic al ly thr oug h the El ec troni c Re adi ng Room on t he NR C's 3 public W eb si te , a t http://w w w.nrc.g ov/re adi ng-r m/doc-c olle ct ions/c f r/pa rt050.  C opie s ar e al so av ai la ble f or i nspe ct ion or c opy ing f or a f ee f rom the N RC's Public D ocum ent Room a t 11555 Roc k v ill e Pike , R ock v ill e, MD; t he PDR's m ai ling a ddre ss is U SN RC PDR, W as hing ton, DC 20555; te le phone (301) 415-4737 or (800) 397-4209; f ax (301)415-3548;
'Ilithe dynamic analysis of active components as defined in Regulatory Guide 1.48, these values should also be used for SSE.
em ai l PDR@nrc.g ov.A ll re g ula tory g uide s lis te d he re in w er e publis hed by the U.S. Nuc le ar Re g ula tory Com m is si on or its pre dec es sor , 4 the U.S. A tom ic Ene rg y Com m is si on.  M ost a re a v ai la ble e le ct ronic al ly thr oug h the El ec troni c Re adi ng Room on the N RC's publi c W eb si te , a t http://ww w.nrc.gov/readin g-rm/do c-collection s/reg-g uid es/.  S ing le c opie s of re g ula tory g uide s m ay a ls o be obta ine d f re e of c har g e by w rit ing the Re produc tion and Di st ribut ion Se rv ic es Se ct ion, A DM, U SN RC , W as hing ton, DC 20555-0001, by f ax to (301) 415-2289, or by e m ai l t o DI ST RI BU T IO N@nrc.g ov. A ct iv e g uide s m ay a ls o be purc has ed f rom the N at iona l T ec hnic al Inf orm at ion Se rv ic e (N T IS).  D et ai ls m ay be obta ine d by c onta ct ing N T IS at 5285 Port R
oy al Roa d, Spr ing f ie ld, Virg inia 22161, onl ine a t http://w w w.nti s.g ov , by te le phone at (800) 553-N T IS (6847) or (703) 605-6000, or by f ax to (703) 605-6900.


C opie s ar e al so av ai la ble f or ins pec tion or c opy ing f or a f ee f rom the N RC's Public D ocum ent Room (PDR), w hic h is loc at ed at 11555 R ock v ill e P ike, Rock ville, Mary land; the P DR's m ailing address is USNRC
Oln'cludes both material and structural damping. If the piping system consists of only one or two spans with little structural demplng& use values for small-diameter piping.
P DR, W ashington , DC 205 55-00 01.  T he P DR ca n a ls o be re ac hed by te le phone at (301) 415-4737 or (800) 397-4209, by f ax a t (301) 415-3548, a nd by e m ai l to PDR@nrc.g ov.A ll NU RE G-s er ie s re ports li st ed her ei n w er e publis hed by the U.S. Nuc le ar Re g ula tory Com m is si on.  C opie s ar e 5 ava ilable f or in spection or copying f or a f ee f rom the NRC's Pu blic Docume nt Ro om at 115 55 Rockv ille P ike, Roc k v ill e, MD; t he PDR's m ai ling a ddre ss is U SN RC PDR, W as hing ton, DC 20555; te le phone (301) 415-4737 or (800) 397-4209; f ax (301) 415-3548;
e m ai l PDR@nrc.g ov.  C opie s ar e al so av ai la ble a t c urr ent ra te s f rom the U.S. G ov er nm ent Printi ng O f f ic e, P.O. Box 37082, W as hing ton, DC 20402-9328, te le phone (202) 512-1800;
or f rom the N at iona l T ec hnic al Inf orm at ion Se rv ic e (N T IS) a t 5285 Port Roy al Roa d, Spr ing f ie ld, Virg inia 22161, online a t http://w w w.nti s.g ov, by te le phone at (800) 553-N T IS (6847) or (703) 605-6000, or by f ax to (703) 605-6900.


NU RE G-0800 a nd N UR EG/C R-6919 a re a ls o a v ai la ble e le ct ronic al ly thr oug h the El ec troni c Re adi ng Room on the N RC's publi c W eb si te , a t http://ww w.nrc.gov/ reading-rm
REFERENCE
/do c-collection s/nu regs/.Cop ies m ay be obt ained from the A m erican Society of Mechanical Engineers, T
1. Newmark, N. M., John A. Blume, and Kanwar K. Kapur,
hree P ark A venue, New York, NY 6 10016-5990.
"Design Response Spectra for Nuclear Power Plants," ASCE
Structural Engineering Meeting, San Francisco, April 1973.


Phone (212)591-8500; f ax (212)591-8501;
1.61-2}}
w w w.a sm e.org.Rev. 1 of RG 1.61, Pa g e 11 REF ERE NC ES 1.
 
U.S. Cod e of Fede ral R egulatio ns , Title 10 , P art 50 , "Dom estic L icensing of Prod uction and Util izat ion Faci li ti es," U.S. Nucl ear Regulat ory Com m is si on, W ash ingto n, DC.3 2.
 
Reg ulatory G uide 1.6 1, "Dam ping Values for S eism ic D esig n o f N uclear Pow er P lants,"U.S. Atom ic E nerg y C om m ission, Washin g ton, DC , O ctober 1973.4 3.
 
NU RE G/C R-6011 , "Rev iew of S tructure Dam ping Values for E lastic S eism ic A naly sis of Nuc lear P owe r Plan ts," U.S. Nuc lear R eg ulatory C om m ission, Washin g ton, DC , March 19 93.5 4.
 
"AS ME B oiler an d P ressure Vessel C ode, C ode Case N-411-1, Alterna tiv e D am ping Values for R espon se S pectra Ana ly sis of Class 1, 2 an d 3 Pip ing ," Section I I I , D iv ision 1, Am erican Society of Mechanica l En g ineers, N ew York , N ew York , F ebruary 20 , 1 986.6 5.
 
Re gul a t or y Gui de 1.84 , "De s i gn, Fa br i c a t i on , a nd Ma t e r i a l s Co de Ca s e Ac c e pt a bi l i t y -ASME Se ct ion I I I ," U.S. Nucl ear Regulat ory Com m is si on, W ash ingto n, DC.3 6.
 
NU RE G-1503 , "Final Safety Ev aluation Rep ort R elated to the C ertification of the A dv anced Boilin g-Water R eactor," U.S. N uclear Reg ulatory C om m ission, Washin g ton, DC , July 19 94.4 Cop ies a re av ailable f or in spection or copying f or a f ee f rom the NRC's Pu blic Docume nt Ro om at 115 55 Rockv ille P ike, 7 Roc k v ill e, MD; t he PDR's m ai ling a ddre ss is U SN RC PDR, W as hing ton, DC 20555 (te le phone:  301-415-4737 or 800-397-4209;
f ax:  301-415-3548; e m ai l:  PDR@nrc.g ov).Cop ies m ay be purch ased f rom the A m erican Society f or Civil Engineers (A
SCE), 1 80 1 A lexa nd er Be ll Drive, 8 Re st on, VA 20190 [phone: (800) 548-A SCE (2723)].  Purcha se inf orm at ion i s av ai la ble thr oug h the A SCE W eb si te at http://w w w.pubs.a sc e.org.Dr af t R eg ula tory G uide D G-1157 i s av ai la ble e le ct ronic al ly unde r A cc es si on #ML 062680189 in the N RC's 9 A g enc y w ide D ocum ent s A cc es s and Ma nag em ent Sy st em (A DA MS) a t ht tp://w w w.nrc.g ov/re adi ng-r m/a dam s.htm l. Copi es a re a ls o a v ai la ble f or i nspe ct ion or c opy ing f or a f ee f rom the N RC's Public D ocum ent Room (PDR), w hic h is located at 115
55 Rockv ille P ike, Rock ville Mary land; the P DR's m ailing address is USNRC
P DR, W ashington , DC 20 55 5-0 00 1.  The PDR can also be reac hed b y telepho ne at (301) 415-47 37 or (80 0) 39 7-4 20 9 by f ax at (301) 415-3548, a nd by e m ai l t o PDR@nrc.g ov.Rev. 1 of RG 1.61, Pa g e 12 7.
 
NU RE G-1462 , "Draft Safety Ev aluation Rep ort related to the D esig n C ertification of the Sy stem 80+Desig n," U.S. Nuc lear R eg ulatory C om m ission, Washin g ton, DC , S eptem ber 1 992.4 8.
 
N U R E G-15 12 , "F in al S af et y E v al ua ti on R ep or t r el at ed to C er ti fi ca ti on o f th e A P 60 0 S ta nd ar d Desig n," U.S. Nuc lear R eg ulatory C om m ission, Washin g ton, DC , S eptem ber 1 998.4 9.
 
NU RE G-0797 , "Safety Ev aluation Rep ort R elated to the O peration of Com anche Pe ak Stea m Electric Station, U nits 1 and 2," S upplem ent N o. 16, U.S. N uclear Reg ulatory C om m ission, Washing ton, DC , July 19 88.4 10.
 
Ware, A.G., a nd C.B. Slau g hterbeck , "A Surv ey of Cab le Tray and C ondu it Da m ping R esearch,"I daho N ational Eng ineering La boratory , R eport No. EG G-EA-7346 , R ev. 1 , p repared for the U.S. N uclear Reg ulatory C om m ission, Washin g ton, DC , A ug ust 1 986.7 11.
 
NU RE G-0847 , "Safety Ev aluation Rep ort for Watts B ar N uclear Plant, U nits 1 and 2,"Sup plem ent N o. 8, U.S. Nuc lear R eg ulatory C om m ission, Washin g ton, DC , January 19 92.4 12.
 
N U R E G/C R-69 19 , "R ec om m en da ti on s fo r R ev is io n of S ei sm ic D am pi ng Va lu es f or th e S ei sm ic Dam ping Values in R eg ulatory G uide 1.6 1," U.S. Nuc lear R eg ulatory C om m ission, Washin g ton, DC , N ov em ber 2 006.4 13.
 
A m er ic an S oc ie ty o f C iv il E ng in ee rs , A S C E S ta nd ar d 43-05 , "S ei sm ic D es ig n C ri te ri a for S tructures, Sy stem s, and Com pone nts in N uclear Facilities," R eston, VA, 20 05.8 1 4.
 
A me r i c a n So c i e t y o f M e c h a n i c a l En gi n e e r s , "B o i l e r a n d Pr e s s u r e V e s s e l Co d e ," Se c t i o n I II , Di vis i on 1, Non-M a nd a t or y App e nd i x N, "D yna mic Ana l ysi s Me t ho ds ," Ne w Yo r k, Ne w Yo r k, 2004.5 15.
 
NU RE G-0800 , "Stand ard R ev iew Plan for the R ev iew of S afety A naly sis R eports for N uclear Power Plan ts ," U.S. Nucl ear Regulat ory Com m is si on, W ash ingto n, DC.4 16.
 
Draft Reg ulatory G uide DG-1157 , "Dam ping Values for S eism ic D esig n o f N uclear Pow er Pla nts ," U.S. Nucl ear Regulat ory Com m is si on, W ash ingto n, DC.9}}


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Latest revision as of 02:06, 17 January 2025

Damping Values for Seismic Design of Nuclear Power Plants
ML003740213
Person / Time
Issue date: 10/31/1973
From:
Office of Nuclear Regulatory Research
To:
References
RG-1.61
Download: ML003740213 (2)
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flitntwr 10721

\\

U.S. ATOMIC ENERGY COMMISSION

REGULATORY GUIDE

DIRECTORATE OF REGULATORY STANDARDS

REGULATORY GUIDE 1.61 DAMPING VALUES FOR SEISMIC DESIGN OF NUCLEAR POWER PLANTS

A. INTRODUCTION

Criterion 2, "Design Bases for Protection Against Natural Phenomena," of Appendix A, "General Design Criteria for Nuclear Power Plants," to 10 CFR Part 50,

"Licensing of Production and Utilization Facilities,"

requires, in part, that nuclear power plant structures, systems, and components important to safety be designed to withstand the effects of earthquakes.

Proposed Appendix A, "Seismic and Geologic Siting Criteria," to 1OCFR Part 100, "Reactor Site Criteria:'

would require, in part, that suitable seismic dynamic analysis, such as a time-history or spectral response

.analysis, be performed to demonstrate that the structures, systems, and components important to safety will remain functional in the event of a Safe Shutdown Earthquake (SSE). This guide delineates damping values acceptable to the AEC Regulatory staff to be used in the elastic modal dynamic seismic analysis of Seismic Category IP structures, systems, and components. The Advisory Committee on Reactor Safeguards has been consulted concerning this guide and has concurred in the regulatory position.

B. DISCUSSION

The energy dissipation within a structure due to material and structural damping while it is responding to an earthquake depends on a number of factors such as types of joints or connections within the structure, the structural material, and the magnitude of deformations experienced. In a dynamic elastic analysis, this energy dissipation usually Is accounted for by specifying an amount of viscous damping that would result in energy

5Structures, systems, and components of a nuclear power plant that are designated as Seismic Category I are designed to withstand the effects of the Safe Shutdown Earthquake (SSE)

and remain functional (see Regulatory Guide 1.29, "Seismic Design Classification").

dissipation in the analytical model equivalent to that expected to occur as a result of material and structural damping in the real structure.

After reviewing a number of applications for.

construction permits and operating licenses and after reviewing pertinent literature including Reference I, the AEC Regulatory staff has determined as acceptable, for interim use, the modal damping values shown in Table I

of this guide. These modal damping values should be used for all modes considered in elastic spectral or time-history dynamic analyses. Values are tabulated for the two earthquakes, the Safe Shutdown Earthquake and the Operating Basis Earthquake (or % the Safe Shutdown Earthquake), for which nuclear power plants are required to be designed as specified in proposed Appendix A to 10 CFR Part 100, "Seismic and Geologic Siting Criteria."

C. REGULATORY POSITION

1. The modal damping values expressed as a percentage of critical damping shown in Table I of this guide should be used for viscous modal damping for all modes considered in an elastic spectral or time-history dynamic seismic analysis of the Seismic Category I structures or components specified in the table. The modal damping values specified in Table I are for use in the dynamic analyses associated with two different magnitudes of earthquakes, the Safe Shutdown Earthquake and the Operating Basis Earthquake (or % the Safe Shutdown Earthquake). These analyses would be required by proposed Appendix A to 10 CFR Part 100, "Seismic and Geologic Siting Criteria."

2. Damping values higher than the ones delineated in Table 1 of this guide may be used in a dynamic seismic analysis if documented test data are provided to support higher values.

USAEC REGULATORY GUIDES

C

e o d guide w be obtai ed by request Iicamtin the divilsons dlmired to the US. Atomic Energy Commisson. Wshington. D.C. 205M.4 Reguhtmy Guides ra Issued to descrbe and muks sieithbi, to she public Attention: Diector of Regulatory StandardL. Comm*nts end egstflom ftr amuhods ecaptable to the AEC Regultory 8taf of kplementinM qWedfic iWt of Irnprosyents hI thne- guides am encouraged end ehould be eant to the Semetary Vd Conwidwion'

regulations, to deilnete tahniques wmd by th sff in of the Comnmikson. US. Aom: Eney Comitsion. Washington. D.C. 20545, evaluating qecific problems or Postubted ecalm"

. or to Provide guldnm to Attantlo- Chief. Public Pro*

dings StEff.

applicent I

Guides em rot substitutes for regulatious and compliance with dmu is not uequired. Methodeand solutions diffagnt foron hse aut In The igde am Iasued In the following un broad divisions:

the =uide will be acctable I they provido a Emi. f the ndlgt pPquoRtaetactor the Isuacor tonthtnnce of apermit or 1E,

e bythe Cconisson.

1.

eRasc to

6. Pro1dts

2. Re- rdi and Test Reactors

7. Tranportatin

3. Fuesk end Materials Facilities L. Ociaetol Health published =ud~ will be eavied perlodlcey. a @pproprim

t. so accommnodate

4. En~omientul end Siting L.AttutRve wetnronts and t s

afetnw inforautios or experience.

L Msatralsi and Plant Protection

10. General p.

3.

If the maximum combined stresses due to static, seismic, and other dynamic loading are significantly lower than the yield stress and % yield stress for SSE and

% SSE, respectively, in any structure or component, damping values lower than those specified in Table I of this guide should be used for that structure or component to avoid underestimating the amplitude of vibrations or dynamic stresses.

TABLE 1 DAMPING VALUES'

(Percent of Critical Damping)

Operating Basis Earthquake or % Safe Safe Shutdown Structure or Component Shutdown EarthquakeD

Earthquake Equipment and large-diameter piping systems',

pipe diameter greater than 12 In. ...........

2

3 Small-diameter piping systems, diameter equal to or less than 12 in. ....................

1

2 Welded steel structures ...................

2

4 Bolted steel structures ...................

4

7 Prestressed concrete structures .............

2

5 Reinforced concrete structures ............

4

7

'Table 1 is derived from the recommendations given In Reference 1.

'Ilithe dynamic analysis of active components as defined in Regulatory Guide 1.48, these values should also be used for SSE.

Oln'cludes both material and structural damping. If the piping system consists of only one or two spans with little structural demplng& use values for small-diameter piping.

REFERENCE

1. Newmark, N. M., John A. Blume, and Kanwar K. Kapur,

"Design Response Spectra for Nuclear Power Plants," ASCE

Structural Engineering Meeting, San Francisco, April 1973.

1.61-2


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