ML19221A945

For Comment Issue of Reg Guide 1.135, Normal Water Level & Discharge at Nuclear Power Plants

ML19221A945
Person / Time
Issue date:	09/30/1977
From:	NRC OFFICE OF STANDARDS DEVELOPMENT
To:
References
REGGD-01.135, REGGD-1.135, NUDOCS 7907110173
Download: ML19221A945 (5)

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OFFICE OF STANDARDS D REGULATORY GUIDE 1.135 NORMAL WATER LEVEL AND DISCHARGE AT NUCLEAR POWER PLANTS A. INTRODUCTION accidental esenti on str uctures and systems at nuslear power plants This guide also suggests data General Design Criterion 2, " Design Bases for sources and acceptable methods for determining uch Protectron Against Natural Phenomenaf of Appen-w ater les els and dscharees.

dix A. " General Design Criteria for Nuclear Pouer h a n t s, to 10 CFR Part 50. "I icensing of Produc-

8. DISCUSSION tion and li h/ation l'acilities.' req uires t h.it struc-ti t u res. 9 stems. a nti components important to safety Some cructures and sy stems at most nuclear he designed to wit hstand the e!!ects of natural pow er plants are continually subiect to fluctuatmg phenomena sub as Hoods tsunam and seiches hse loads that result from s armtions m ground water without loss of cap ibility to perform their saf ety les els dncharees

'd water lesels m streams or t u ns. ions. ( ritenon 2 dso requires that design bases w ater les els m lakes and oce.nu. Structures that ex-f or these structuio. sy stems. and components renett:

tend below ground surface mio the local ground uater aquiter (or aquifers) m ust w it h u a n d the I. \\ppropriate consideration of the most sescre of resulting hy drostatic pressure Structures that are.if-the natural phenomena that hase been histoneally t es ted by surface w ater disch irges and les els include reported lor the site and surrounding region. with dams !cs ees. breaku aters canals. and mtake and ths-su!hcient marzm for the hmited accurag and quan-charce strus tures in considering the ettects of design tits s't the h%5rical d.lta and the period ol time in hams es ents such as c.irthqll ikes, tornadoes, and hut-u hish tht dfJ hase been accumulated.

ricanes and t he ef fects of desien hash acsidental es ent s sush as plane cr.nhes. t r..nsponation acci-2 \\ppropriate combmanons of the ef f ects of nor-dents. explosions. tires. and lo~ol-coolant accidents MLd and aiCu!cnt Conditions With the ettects of the i l ( )( \\s!. the designer m ist include in hn calcula-natural phenomena, and nons the loads causa' 'n the w ater les el ior dis-chareen. as weh as the ' iC on the strusture or ss stem I he unportanse of the sitety functiens to be per-cau[ed by t he design basis es ent hem; considered tormed I hn w ater les el hir dncharge) n referred to m ths gmJe.n ths norm.d u.ner les el (or dm hargel Paracrgh Inn lhel of lu ( I R put ] no, g a g

's o c ( nienf ~ teqmres that phwcal characternths o!

Since the design hash esents hase a s ery low ine Cc. I m f ading seismologs, meteor ologs, geolod)-

prohAhty or occerrence. the w atcr les el (or dis-and hs d!H0p he taken inlo. <nunt in deternMning chargel used m combination ulth the desien hasn t ht asceptahihis of a Mle 144 a nlaleu ~ min er rCletoT.

esent need not represent a Condition with low I his pulde sets f orth methods accep t a h'.

to the 16 m N

c m e t h' ' "' M o m' ' E " bere r ' m at N R(~ stalt f or deternuning normal ground anu or-

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'V n!.m m A c. ca < q her o dur.d es er s i ' vm br I.he water les els and surlate u.ller dish irges f or use g, ya y gg 3.M a W t.d es em s Ah n ce m an.ily ses of the c!Iec' of desien h.nn naturJI ind p

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• probability of occurrence. As used in this guice, the is quite possible that the influence of flood lesels on term normal water Inc/ tor diuharge. means that normal ground water lesels must be considered.

water lesel(or discharge) that has a probabihty of up-prosimately 0 5 of occurrence at the time of interest.

The following discussions of varioas water bodies assume that the seasonality of the design esents are properly taken into account.

Some design basis esents may actually consist of a series of esents such as an earthquake tolhmed by one or more altershocks This fact n important if the

2. Nonsidal Streams earthquake could af fect the normal water lesel (o:

l>ata on stream discharge rates are readil) discharge) and result m a different u ater lesel(or ais_

as ailable for thousands of stream-gaging stations charge) w ben the aftershocks occur. I or example, the imtial earthquake could affect an underdran ssstem operated by the (f.S. Geological Sursey; l!.S. Army to hmer ground water lesels at the time df the Corps oi Engineers, Bureau of Reclamation; other altershocks. Similarly. a dam tailure caused by the in.

lideral. State, and local agencies; power companies; ittd earthquake could substantialh chance the dim and other orgam/ations. Most such data are in the eb rce m a riser at the time of the aitersho'cks. Under forn' of mean d.nly discharges for s arying periods of 11 drology textbooks contain acceptable such' conditions, the normal w ater les el(or discharee) ree ird.

3 should be assumed onis at the time of the initial standard methods for transposmg these data from the esent. and the water leiel (or dscharee) durine the gagmg stations to the plant site. ~1 hus, relathely altershocks should be determined bs [maissa of the rehable information on stream dncharge may be ob-ef fect of the initial esent.

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t.uned for a plant site located on a nontidal stream.

Short-term discharge data arc also frequently tol-lected at the sites and should be used to.erify the

1. Seasonal Occurrence of Design liasis Dents transposed data.

I arthquakes. plane crashes transportation acci-A permd of record of at least 50 years n desirable dents, explouons. lires, and 1.OC As may occur at any for use in determming the normal w ater les el and dis-time. !!oweser. water lesels (or dischargeo may sary charge at sites on nontidal stream' Lor many loca-considerably during any y ear. Accordingh, w hen tions howeser, such long-term records do not cust.

determimng normal water lesels (or dischargeq for In such cases, periods of record of at least 12 years these esents b the methods recommended in this may be acceptable if it can be demonstrated that the guide, w ater lesels (or dnchargeu for the entire year period used includes major wet and dry periods should be considered.

W bere shorter-term data or no data cust. records should be estimated on the basis of weather records On the other hand, lloods hurricanes and tor-and records for other streams in the region. In all nadoes are seasonal in most parts of the i nited cases, watershed deselopment conditions anticipated Statet in determining normal water lesels ( o r th s-during the plant liatime should be conudered.

tharges) for these seasonal es ents such season.Jity should be taken into account. I or example, tor-1 or nontidal streams the median dncharge wdl he nadoes do not eenerally occur durine the winter considered the normal dnebarge. ~l he meman die months in the northern states. Fherefore. the normal charge may be deternuned as the 50': pomt on a w ater les el (or dncharget to be considered with tor-llow-dur ition curs e (dneharge sv percent of days nado effects should be derned onh from data for w hen indicated discharge was equalled or exceededt those months in which tornadoes may be especteJ to Accept.ible methods of constructing a flow-duration curse are outhned m many pubhcations, e p.. l'i occur.

(ieological Surs e: Water-Supply Paper 154 2-A.

Similarh. in i lorida hurricanes hn

.een "I low I uration Curs es.

1959.'

recorded in sirtua!!) esery month. but thes are more hkely to occur durmg the late sununer and earh fall.

It would be desirable to determine the normal w hich n coincidentally the period of the year in w hich w ater les el on nontidal streams by sinular me ms. i e~

high w ater les el- (or dachargeu are most hkely to oc-use of a stage duration curs e (water lesel s s percent illr. Accordingly. for this ty pe of seasonal s ariation.

of day s w hen indicated lesel u.n equalled or ex-the normal w ater les el(or dncharfe) should be deter-ceeded) llowes er stages (w ater les e!q at pacing sta-readily as aJable as are the cor-nuned ouly for that period of the year durmg wluch tions are not as the esent n most hkely to occur or for the ap-

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prgriate period as indicated by studies of the area.

pgn e stans s from a hx5 a nomJuranon ane mas ne Noned it shmJJ N n W homer. that wh a tune w di coser ort the i loods are seasonal in many parts of the (Jnited rer, >J < ' res ta avaaHe for the um stanon States. Whde the surface w ater les els (or discharges)

' ( mes ne a Ne N" 6e Hrnh M %%nn. Us addressed in thn guide are not applicable to floods,it ticoi < <a w ses. :on v ah I ad, s'rcet. tru eton. \\ \\ :::n:

142 125 1.135-2

responding discharge data. Therefore, the NRC statT mean monthly records is sutliciently accurate or will accept, as the normal water lesel, the w ater level whether mean daily data should be used. Such a corresponding to the normal discharge. Computation study could consist of computing medians for a short of the normal water lesel by this method requires the period (e g., two or three years) from both monthly estabhshment of the relationship between rner lesel and daily information and comparing the rcults.

and discharge (the rating curse) and the application of that relationship to the normal discharge. If the

5. Regulated I.akes and Resersoirs stream has a mouble bed allowanee should be made for shUtmg of the rating curse.

At their outlets many lakes base dams or other regulating structures, w hich in ef fect consert the lake

3. ~1 he Great I.akes into a resersoir. Regulated lakes are therefore addres-sed as resersoirs in this guide.

~1 he lesels of some of the Great I.akes base show n upward or doa nwarJ trends oser long periods. I or N1ost resermirs bas e at least one les el deugnated "nornul pool" eles ation. For some resers oirs.

cumple I ake.\\lichigan-Iluror has shown a shght as more than one e sation. usually urying with the l

dow nw ard trend oser a period of more than 100 s ca rs. Such trends should be taken into account in time of the year, may be considered normal pool.

' etermimne the normal les el. An accentable l hose resers oirs that hase resersed flood control d

procedure is to adjust the last 50 scars of data for the space are frequently of this ty pe. For esample. a mdicated trend before determinine the medun lesel.

resers oir in the Sierra Neuda of (_ ahforma might T his adjusted 50-year median leiel should be con _

hase a enen normal pool lesel for the July-to-sidered as representing the normai lael N os ember period. followed by a Nos em ber-to December period w hen the les el must be draw n dow n Lunar tides m the Great I akes may be ienored to accommodate potential flood r u nol f, and a because their site n nephgible.

December-to-June period w hen the lesel must he kept as closely as possible to the draw ndow n lesel but llecause of the si/c of the Great 1.akes. their water may rise to as high as the top of the flood control les els change s cry slowly. I heref ore, it is not neces-pool sary to determme the normal w ater lesel f rom dad >

data. N1ean monthis s alues are of sulticient accuraes.

Normal water lesel should be considered the nor-I he De;roit thstrict. l' S \\rmy Corps ef I neineer's mal pool lesel of the resenoir, with due sonsidera-

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tollects and publishes monthly data on the lesels of tion for uriations in normal pool lesel during the the Great lakes.

year. If the resersoir includes flood control storage, the medun of the Ilood control pool les els for the hfe

4. l'nregulated I.akes of the resenoir should be considered normal for esents that are hkely to occur durmg the flood Ts used m this guide, the term um adated la4cs season.

means those natural lakes w hose outlets are sirtually uncontrolled by dams or other structures and those Records of lesels of regulated lakes and resermirs natural lakes that are not appreciably affected by are usually cellected by the operator of the iesenoir.

dn ersio n s mto or out of tre lake. Rt gulated/a An are in some cases. these data are puhhshed by the E S.

dncussed as reser oirs m thn cuide.

Geological Sun e) l.S. Army Corps of I ngineers, or other i ederal. State, or local agencies.

\\ medun les el based on 50 years of d ata a accep-table as the normal water lesel T his lesel can be

6. Oceans dete mined from long-term recerds of the lake lesel.

If only short-term records are aunlabic. they may be A complete tide c)cle aserages 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> 25 minutes estended by estimating longer-term data on the basis at most pomts on the shores of the limted States.

of records for other lakes, stream discharge and llecause of thn relatnely rapid rate of change of cround water data. and weather records. As with ocean lesels the duration of the design basis esent nontidal st reams a shm ter record may be acceptable should be considered. N1ost such esents are of short it it can he demonstrated that ma.ior w et and dry duratmn. rangmg trom essentially instantaneous periods are mcluded. As with the Great I.akes. if a (e g.. plane crashes. esplosions, and most transporta-trend can he identified, the data should he adjusted tion accidenta to a few seconds or minutes (e.g.,

for this trend. Consideration should also be pnen to earthquakes. tornadoes and some transportation ae-potentul changes m a ater use that could significantly cident4 Iluweser. hurricanes and tires may last sut.

alter this m ed u n.

lietently long to span the entire tidal range from low to high in man > cases mean monthly data may be used to compute the medua lesel lloweser a studs should I or short duration es ents. the median tide lesel be made to determine w hethe-the medun based on may be considered as the normal water lesel. I or 147 1'

1.135-3 14L 3

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longer duration esents, howeser, it is probable that A period of record of 20 years (to account for the tide will be abose (or below ) the median lesel for cyclic tidal variations) is acceptable if it can be at least part of the tin,e of the occurrence of the es ent.

demonstrated that the period includes major wet and For these esents, thertfore, median higher high tide dry pc-iods.

or median lower low tide (see discussion below) should be used as the normal. The choice of median

& Ground Water higher high tide or median lower low tide will depend on the event beine considered. For example, hur-Normal ground water lesel should be the median ricane winds blowing seaward from land will Imser level oser a 20-year period. This length of record will the lesel of the ocean (setdow n). If this will base an not be asailable at most sites for nuclear power cifect on a safety-related water supply, the normal plants. Howeser, most sites will hase one or more water lesel should be the median lower low tide.

short-term recorda of a year or two. The stall will ae-cept esteton of these short-term records by correla-fligh and low tides do not consistenth reach the tion with longer records in the region. The effect of same les els. The two high tides during a complete 24 future changer in water use should be considered.

hour 50-minute escle at some locations are of dif.

The U.S. Geolopcal Sursey collects and pubbshes ferent heichts, as are the tu o low tides. The hieher of records for thousands of obsers ation w ells the two l$igh oJes is designated as higher hich tide throughout the Umted States and may advise where and the lower of the two low tides as lower iow tide.

other data in the region may be obtained.

Other esclic sariations have also been identified.

For those sites at which the appheant plans to Tidal heights sary during each lunar month from lower the ground water lesel permanently by use ot sprme (high) to neap (low ) rance. The tidal rance also has a esclic sariation of soniewhat more tl$an 19 an underdrain system either pumped or _crasity flou, s cars. In' addition. tidal heights are af fected by varia.

the staff w di accept, as normal, the anticipated lower water lesel f or which the ss stem is desiened.

tio n s in barometric pressure and by wind. These meteorological phenomena cause the prmcipal dit-

. und water les els to be used for soil hquefaction ference s between predicted and recorded tidal a naly ses wili he dncussed m a regulator 3 guide now hMN under preparation on hquefaction.

In order to ensure that these variations are con-sidered, normal tide lesels should be ecmputed from C. REGULATORY POSITION a continuous record of at least 20 scars.

A naly ses of the capability of safety-reLited struc-A long-term tide record is not as ailable at the exact tures, sy stems, and components to resist combina-location of many nuclear power plant sites. Usually, tions of loadmg conditions often require identifica-hones er, a short-term record will have been collected tion of normal water lesels or discharges. I or the at the site. In this case, the short-term record mas be purposes of this guide, normal uater /ncl wr dn-extended bs correlation with one or more recordi for darm means the w ater lesel (or discharge) that can nearbs lone-term tide stations.

be expected at the time of occurrence of design basis natural or accidental esents/ Subject to the excep-Records of tidal heiehts are collected and mam-tions below the normal water les el(or discharge) will tained by seseral acencies but prmcipally by the generally be the median w ater lesel (or discharget National Occame and Atmospheric Adnunistration i.e that w ater les el(or discharge) that will be cqual-(NOTA) in the Department of ( ommerce. T his led or exceeded 500 of the time.

agency recular') estimates mean high tide or mean higher high tide, primarily for coastallocations. Data

1. Seaumal Occurrence of Design liasis ihnts for other locations mas bc estimated. uune the rela-tions pnen m tide tables. by mterpolation.

If the deugn basis esent under consideration n seasor al. the normal w ater les el(or discharge) should 7 I stuaries be determined for that part of the year in which the es ent is hkely to occur.

Iloth Ireshu ater runoff and lunar tides alfeet w ater leuk in estuaries Niost estuaries are paced by the

2. Nontidal Streams (LS. Geological Sursey, National Occame and At-mospheric Admmntration. L '.S. Army Corps or

'Ihe normal discharge should be the median dn-Eremeers, or others. A stace-duratmn curse shouid charge based on a period of mean d<nly dncharge be used to estimate the median w ater lesel as the nor_

record preferably at least 50 y ears in length. I he nor-mal w ater lesel. Ihn procedure may be used f or loca_

mal water lesel should be either (a) the median mean tions upstream and dow nstream Irom the sue with daily w ater lesel based on a record of preferably at the normal water lesel at the site estime.ted by inter _

least 50 years or (b) the water lesel correspondmg to polation

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normal dhcharge. including consideration of shiltmg

7. Estuaries ratmg curses f or streams with mos able bedt A shorter period of record (not less than 12 years)is ac-Norrial water lesel should he the median lesel ecptable if longer records do not cust and it can he based on a 20-y ear period of record. For longer-demonstrated that the period used includes major u et duratioa es ents. median higher high or lower low tide and dry periodt based on a 20-year period of record should be sub-stituted for median tide lesel

3. 'l he Great I.akes S. Ground Water Norm.d water lesel should be the medun mean monthh les el heed on the latest 50 years of record.

Normal ground u ater lesel should be the median with suitable adjustment for demonstrated long-term lesel heed on 20 years of data. If permanent lower-t ren d s.

ing of the ground water lesel by using underdrains is pl.mned. normal les el should be the design lowered

4. I nregulated I.akes i()ther Ihan the Great I.akeu lesel Norm.d w ater lesel.hould be the medun beed

9. Mailability of I)ata pref erahh on 50 years of data. l'n! css it can be if the nnmmum periods of record specified m the Jen onstrated that the medun based on m ea n suuhiently auurate, mean dad 3 forego m g poutions are not as a dable. standard monthh les els is data should be used If long-term trends can be iden.

methods may be used to transpose or extend the t nied. tht 50-3 car medun should he adeted for e.nlable data. I u!) explanations of the methods used thoc' snos A shorter period of recorJ t not less than for such procedures should be formshed.

i_ years o aue:, tab lc if longr records do not emt and it can be demonstrateJ th.it the perioJ used m-cludes maior wet and dry periods

5. Regulated I akes and Resermirs D. IMPLEMENTATION Nor mal w ater le,el &uld be the deugnated nor-I he purpose of this section is to proside mtornu-mal piltil ClCs a titin.

Ihere !!1 a y bC dllierCn' tion tt) ilppliCants reg lTding the NN( staI splans$or dCslp natCd Il.ir nlal pthd C C'. II. ins at ditterent times usine this reptilatory guide.

of the 3CJr ll the rCsersinr timta!ns flood Contrt !

spaCC, Ilie ns*f mJI w ater lCs CI t!aring t he lltkid scJuin I'scCpl 111 t h(isC CasCs in u hich the applicant shouM he the medun i I the ll4 kid les ch.titained dur-pToposes an acceptable alternatne method f or com-i Jng the ItIe i ! the rCsCrs t $1r ply ing w ith specified ptirtituis iif t he ('om minior1's t

TcJu!.llisins. the method described herein will he used ti. ()ceans m the es.duation of submittals for constr uction per-Imt apphCat.ons doCkeled altCr b) !. l b. un! Css

} (ir es ent s til shi r! (!ilt ititi?i i a h i!! !it'ur l'r ! css ).

this ptliste is res[ sed 1% a rCsblt of suygCstions Irlim the i

norm d w ater lesel.hou!J be the meAm tide heed public or Mtional stall res ien.

ona209 ear period of resoM lt the es ent may h.ne a Is5nper duratitil1. li tif W.tl w alCr !cs CI shtinld be the nie-11 an applicant wishes t() use this regulatiiry guide don h:ghe high t:& or medi m low er lou tide heed in des clopmg subnuttals f or apr' cations docketed on on a My car period of rewr.! ( hohe of hieher htch or before W3 1.10. the peronent portions of th.

in 'ow et ow tide should be the most u wrs aine f or application nill be es aluated on the basis of this the esem be conside,cJ and its snsequenco y m d e.

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