ML19221A933

Reg Guide 1.117,Revision 1,Tornado Design Classification

ML19221A933
Person / Time
Issue date:	04/30/1978
From:	NRC OFFICE OF STANDARDS DEVELOPMENT
To:
References
REGGD-01.117, REGGD-1.117, NUDOCS 7907110104
Download: ML19221A933 (3)

Text

Revision 1 j %

P U.S. NUCLEAR REGULATORY COMMISSION April 1978

@ D. l REG J E'O RY GU O JE

%o.u OFFICE OF STANDARDS DEVELOPMENT REGULATORY GUIDE 1.117 TORNADO DESIGN CLASSIFICATION A. INTRODUCTION considered l

A basic pro \\ ision ot tornado protection criteria is l

(.eeneral 1)esten (.riterion 2.

Dewn lla ses for that thine structures, sy sten t and cornpi nents w hose i

Natural Phenomena. of Appen-f.nlure could result m consers atn ely calculated expo-i Protection Against dix A.

Teneral Design (.riteria tor N.uclear Power i

s t.r e s comparab'c to the cuideline exposures of 10 Plants to lo (,H( Part 30

't.it ensmg or Produc t.FR Part Im.

. Reactor 5ne (.riteria.

should be j lion and I.ti!

oion I acilities. ' requires, in part, that plaitCCled against I)lIl et t'ects l prc\\ ent sus h f ailtire.

structures. sy steo and tomponents important to

.I his prtu lsit n b) Il% lt, hilwe\\ Cr. wiluld Ikit pit >\\ ide safety be design 'd to w unuand the ettects el natural protection f or cert.un other structures. sy stems, and ti r nadoes w ithi ut liin (it espabil-pherkimena suc h as i

s itn po ne nt s which Ciiuld be dairaged by a leu se-ti i!x (ti pCrttirni their saf ety f uncthins. (.riteriiin 2 a,u l s

\\ cr e, but noire likel), hunadai In order til ensure pri)-

requires that the design bases f or these structures f ei t 1( n f or rnore probable cients ha\\ing lew * '\\ ere sy stems. and co nponents retlect (11 approci con seque nt e s. the se'ection of su r :tm e s miems combinathins ist the etlCt ts til nornial and accident and Ctimpiinents tii be printected Jgainst the ettects i)j cnithlithins W ith the CtItcts of natural phensimena and based on not allowmp ottsac exposures to a Dlll. is nlpi'rtJ ncC t)t the %1t et) t il nc t liin s t') bC pel-(2) thC i e\\cced an appropria!C ttJcthin ol llI ( l R Palt IIHI formed guidelmes t his guide dewribes a method acteptable to the Protection 01 designated strut turi

.us.

and N R([ stat t ti)r identif y ing thi se strth tures. sy stems.

ci niptint.t s may generally be aa tiriiplistied by Jc-i i

and citmpt ments ist light-w ater cikiled ICas hirs that si. MinQ prt'tCcIl\\ e barIiCrs li> preclude tsunadii dani-6 li r exainple. the printary ciintaimnent. reac'in i

iit the 1)esign age shiiuld be prtitected tri rn the ettects i

lla s t s lornaJo e sce Regulatory (iuide 17t..

' De si g n builJmg. auxihary bmlJme. and tontroi strut tures deugncJ against ci llapse and dn'uld prii-d.i uld bt hasis 'I~ornJJi> liir Nuclear 1%iwer Plants 't. including l

i Ili w e\\ Cr.

tilrn.hh1 inielles. and relllain f unctli nal } he Ad\\is

\\ lde Jn ailequJte bJrrler Jpainst m i s s ile s.

i i

or) l'ommittee on Reat tor hateguards he been con-lbC prUnar\\ vintJminCht neCd not nec e ssJrd) Waln It pri tecti \\ e tiar riers are sulted concerning this guiJe and has toncurred in the tain its leakticht integrity i

regulator) pihlfii n.

niit Installed the st r uc t u re s a nd ctiilipiment s theni i

sel\\ es shiiuhl be designed hi w ithst.ith! the et t ects ist B. DISCUSSION t. it tornaJo. incluJmp tornado m t wilc strixes lhe I

l Nuclear power plants shi uld be protected f rom the phy sic A eparation of redunJant in alternat:\\ e struc-ettetts of 'ornado st rikes 'I b t hkelihood of a credi.

thres t r t on ponent s required f or the sale shutdown r

t the plant a generally not considered, s ceptable b\\

7 ble hirnado strike \\ arles llom abiiut lil per year to i

Nalues ses cral orders of inagmtude higher Phy sical it sell hir pri,tet ting ag.u n st tornadi e t tet t s. incliding hirnado generated miniles

~I hi s is bet ause of the deugn par ameters of tornad,i pnif ection pro \\ l sio n s I are such that deugnated structures s\\ stems and large number and random diret ti in of potential nu s sdes that wold result f rom a t( rnado as

'l m the l components \\.dl be able to man tain their necessary Capabilaies m th e\\ ent of a Deugn hasis lornado need to consmer the uncle t.nl ue t r aer t

l il)U l I. as delincd m Re guLdor) Guide 13

~l his It is not les essary to m.u nt.un the t unt oonal capa-pri tection ol~ the design 'ted items bilit y ot all Seismic ('ategier) I st:uttures. sy stems

~

ensures that i

t Jedinst all sredible tin nadiies has been aa q u it c!'

and t iimpiinent s because the pridiability i>t tf e li int i

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accident wi b DilT or smaller tornado, or carthquake The appendix to this guide lists s t ru c t u re s, sy s-with DitT or smaller tornadol is suf fisiently small.

tems, and coinponents, w hich together with their flowes er, equipment used to provide long-term core foundations and supports. should be protected f rom cooline tollowing a I.OCA should be pro' the ellects of a Dll f (see lhpulaton Guide 1 7td. I including tornado missiles. without loss of capability Similarly, it is not generally neces o perf orm their saf ety f unctions

~l hose structures.

the raJio.ictise w aste sy steriis since. es en in tnt syste m s. and coniponents that shotild be protected of gross tailure. olisite exposures would rem.un wt rl may require tees aluation f or designs that ditter sub-belo w the guideline exposures of 10 CI:R Part 100 stantially troni those now in use because of the li.uited insentory allowed in these sy stems.

C. REGULATORY POSITION Structures. sy stems. and components unportant to saf ety that should be protected f rom the ettects 0t a

't he purpo,e of this section is to pros ide inf orm.i-Design llasts fornado are:

tion to apphcants reg.uding the NRC statt 's plans for lising this regul.ittiry guide I

l' hose necessan to ensure the integrity of the IcaCltir coolant presstire bi und.ir);

({ xt ept til t hose Gise s in w hich the applicant prii-t poses an.icceptable alternalis e method f or comply ing w ith specif ied pi itioiis of the Cisnimissnin 's regula-

2. I hosC necessar) ti) eilstire the capability ti) s htit i

dow n the reactor and maint.un it m a sate shutJow n tions, the me hod described herein will be used in the condition (this includes both hot standby and cold es alu.ition of construction pernut applications doc-shtitdow n capability 1. and keted atter May 30.197S-t I hose w hose 'ailure could ! cad to radioactn e it an apphcant wishes to use this regulatory guide releases resulting in c.ilculated ot t site e x posure s m des clopinc onuttals f or app'ications docketed on greater 'han 25', of the ptudeline exposures of 10 or bef orr Sta) 30.197S. the pertinent portions of the CI R l art 100 usine appropriately conscrs atis e an i-ape'. cation will be es aluated on the basis of this ly tical Illethilds and Jssumpiltins guide O

v2 #

g i 1112

APPENDIX 9

STRUCTURES, SYSTEMS, AND COMPONENTS OF LIGHT-WATER-COOLED REACTORS TO BE PROTECTED AGAINST TORNADOES

1. The reac*or cool mt prewure boundary.'

could result in potential ottsite exposures in excess of the criterion giset in subitem (3) of the regulatory

2. Those portions of the m.iin steam and main posit io n.

2 feedw ater sy stems in PWRs up to and including the outermost isolatioa vahes.

9. Sy stems or portions of sy stems that are required for monitoring, actuating and operating tornado-

3. I he reactor core and indisidual fuel assemblies, protected portions of sy stems listed in items 4. C. 7 at all times, inchiding during ref ueling.

and 13.

4. Sy stems or portions of sy stems that are reqmrei

10. All electric and mechanical ' w ices and cir-for t I) attaining saf e shutdown, i2) residual heat re-et itry netween the process sensors ai J the input ter-mos al. (3) cooling the spent fuel storage pool. (4i nunals of the actaator systems insolsed in generaun_

mitigating the co nsequences of a tornado-caused signals that initiate protectise actions by tornado. !

PWR steam line break.' 151 makeup water for the protected portions of sy stems listed in items 4. h 7 }

primary sy stem, aid 4 6) supporting the abos e sy s-and 13.

tems, e p., cooling w ater, ultimate heat sink. air sup-ply. auxiliary feedu ater. and sentilation

11. Those portions of the long-term emergeno core cooling system that would be required to main-

5. The spent fuel storage poo to the esient neces-tain the plant in a s.ite condition for an extended time sary to preclude significant loss of w atertight integ-af ter a losvof-coolant ac ident.

rity of the storage pool and to pres ent nnwiles from contacting fuel within the pool.

12. Primary reactor containment and other saf ety -

related structures, such as the control room building

6. The reactnity centnil sy stenn. e p.. control :od and auxiliary building, to the extent that they not col-dris es and boron injetimn sy stem.

lapse. allow perforation by missiles, or generation of secondary miwiles, any of which could cau e unac.

7. The control room including ali equipment ceptable damage to tomado-protected items. Ilow -

needed to m;untain the mirol room wi:hin safe es er, the prunary containment need not necessarily habitability limits f or personnel and safe ens tronmen-maintain its leaktight imegrity.

tal lunits for tornado-protected equipment.

13. The Cl s Ili electric sy steias, including the l

S. Those portions of the gaseous radw aste treat-auxiliary ss stems f or the onsite electric pov er I ment sy stem w hose failure due to tornado ef fects supplies. that proside the emergency electric power needed f or the functioning of plant featu:es included in itenn I through 11 abose

' L Jenrea m (50 : of in t i R Um 5e hsunJars insluu s th we ; ortions o' t he s y ste m re-14 Thi>se portions

<>t structures, sy stems, and

'T he 9 s c i

wrcJ 'o m erhsh the wf:cJ ' #ct) runam and t mnem"/

components w hose ccatinued tunction is not required pen; up i i aml int!uding th !:ro s ake iinc lay a saf ety or h e

1. '

om M hi m unacWp @ k

, c.! o r t.4 e;c et 4 a n.ii w relie f s ais e, t his is c i t he r in.r n o i c losa.e u be 1 t he saf e funs t n +n is reged safety letel the f unctional capability of any plant tea-tures included in itenn I through 13 abose or could hnanwh. he main qeam ss s <

up to and mt!d. a set -

enes s!sl\\. or a rurNne result in incap.icitating injury to occupants of the con-ond is.cano, s ahe wt h as a redbndr guu, n he m coed trol room.

1.117-3

UNITED STATES f

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NUCLE AR REGUL ATORY COMMISSION W ASHING TON. D. C.

20555 POST AGE AND F E E S " AID

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t %. i e o s t a t e s teav UU" OFFICI AL BUSINESS u n i. u t avon,

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PEN ALTY FOH PRIV ATE USE, $300 k

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