ML20128D906

Draft Rept to AEC Regulatory Staff Adequacy of Structural Design for Monticello Unit 1

ML20128D906
Person / Time
Site:	Monticello
Issue date:	09/29/1969
From:	Hall W, Newmark N NATHAN M. NEWMARK CONSULTING ENGINEERING SERVICES
To:
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ML20128D904	List: ML20128D901 ML20128D906
References
NUDOCS 9212070419
Download: ML20128D906 (12)

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NATHAN M. N E, W M A R K 1114 Civig CNG!NEER.NG BUILDING CONSULTING ENGINEERING SERVICES UADANA ILLINOIS 61801 D R ,* r T REPORT TO AE C RECUT ATGRY 5 TAFF ACECUAC y cr 'lFUflUP.AL DE!!rf; FCR MONTICfLLO UNIT hC. 1 Northern Stat es Power Company AEC Occket No. 50-263 by N, .M . levre r k U J, Hc 11

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8 ADCQUACY 001HE STRUCTURAL rE!!CN FOR-MONTICELLO UNIT NO, 1 N r t he rn T-tat es - Power Comnany by-

h. M, heve.o r i. and W. J. Hall 1NTRODUCT10k this repor t on Manticello Nuclear cenerating Plant Unit I was prepared on the basis of the following: (1) A review of the Final !a f et y Ana l ys i s Report (TLAR) and anendment s thereto as submitted by the !cr thern S tates Power Comoc ny , as-listed et the end of t'his rennr t ; (2) a visit to the s ite by Dr. W. ,,

' Hall on 17 Sentenber 1949; and (;) discu?sions of the facility with the AEC Regul'atory 5taff. _

Monticello Unit No, 1, as noted in 14ction-1 of the ?fAR, has been des Igned- f or a maximum output of 1670 MWt (5LS MWe net) and cons ists of a

' t i ntl a-cyc le f orced c irculct ion, bolling water reactor that produces steem for direct use i n t he 5 team t urt,i ric. The f acility.is located 22 miles dow ns ! rran f rom ' t . Cloud, Minnesota and about t hree r i tes nor thwes t of the v illage of hont icello, Minnesot a , on the south bank of the Miss iss ippi River, The olent war des Igned f or1a [es Ign Ecs is Err _thquale of ',129 ne>imum hor izontal ground accele rat ion and f or an Operat ing- Bas is Earthquake of 0.069 naz irum hor izontal ground ceciloret ior.. The vertical earthquate excitation _-

was assuird to occur s imultaneoasly wi th the horizdntal earthquake excitat ion -

for the. design of the Class I s t ruc tures and equinment , and was taken as two-thirds of the moonitude of the corresoond ing hor izontal excitat ion.

The criteria aonliccble to the des ign of Kont icello Unit I were reviewed extent ively by us at the cons t ruc t ion nerrai t s tage; eccordingly we m.______m_ _ _ - m_ _

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2 have not included herein, unless there was sort specif ic reason f or doing so, topics covered in our.carlier report dated March 19A7 (Ref,- 7).

C OM'tt hH ?N A00QUACY Or TESTON rnynda t inns f rom s tudy of the mater ial f, r es e nt ed in the FSAR and f rom discussions wi th t he epplicant end General E lec t r ic and Ot chtel personr el e t the 5ite, i t was as ce rt a ined that in accord with the criter la presented in the P!AR the-cl6y was r(moved from underneath the reactor building, and the base of the reactor building was founded at elevat ion 888 on selec ted and compacted granolar notorial, which overlays hardonn and thence bedrock (approv. elev, 660).

The t>ase of the turbine building is located at elevation 903 and there was no maj or a mou n t of material- removed and renlaced unde r the f eundat ion of this

t. u l l e i ng . The bate of the intcke ttructure Is. located at elevetion F77; the foundet inn was placed on lean conr rete which ln turn rests on bedrock.

The stack is cons tructed or a spread foot ing on or iginal grade; the footing is app r o x i ma t e l y 60 f t . across flats and is oc tagnnally shaped.

Fullding Sena ra t i_nn It was noted in discuss ions that there is a one-inch s eparat ion between the reactor building and tut t ine building; this separat ion is filled w i t h a one-i nch premolded _f i ll i ng ar.d there is no (vidence to indicate that the senarat ion be tween the buildings was selected on the t,as is of any poss Ible motions under the . inf luence of ear thqueke excitat ion. It is conceivable that racking between the-retctor building and turbine t,ullding could occur.

Dynarie Andivscs of Etructures and ?ininc Two methods 'of dynamic analys Is were employed f or najor s t ructures and ere desc ritard tiy the applicant i n pe nc r e l t e r ms in the'FLAR and amendments thereto.

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1 l; Tire History - It is noted in Ap?endix A to .the FSAR that the control room, of f gas s tac k , reac tor Lullding, dry %+11, and reactor nressure vesst1, '

l were analyzed by the t ime history method. The solution in this cate is based i

i. on a class Icel normal load approach for uncoupl ing t he equa t iens of mot ion, f and the t ime his tory of respons e for each mode is computed nel ing use of-l the nume r ical Integrat ion of the Duhann-1 Integral. The modal responses are I combined at each ins tance of tice, and the noximum values are determined for use in the des igr. process.

2 1 It was indiccted in Eect ion 12 of the FSAR that the July.21, 1952,

! fi 69 W Taf t accelerat ion-t ime record was used f or the t ime-his tory analys is 3

after scaling to the specified design level, fhe response spect ra f or 2 percent damping for the t irm -his tory record is comoored with the Tef t norgelized I- spectra given in the DEAR or iginally, and with Housner's 2 percent spectrum, l in rig. 12-i-9, The conoar ison given .there sugges ts that the t ime-his tory i r-cord led to a reasonable and sat is f actory response spect ra; however, the appl icant has been reques ted to docunent the length -of t ime of record erployed i

4 and also to confirm that the sane t i me length of record was used in oreparing the spectra presented in Fig 12-2-9 of the FSAR. It will be noted in i

{ Fig. 12-2-9 that there are some low t roughs in the spectre which fall below

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the recommended response spec t ra. The-applicant notes on_page 12-2-8;of_the PSAR that: "When the t ime-his tory analys is was .made, periods were examined and the corresoonding spect ra accelerations f rom both the t ime-his tory and

!~ response accelerat ion spec t ra were connared. If S ubs tant ial di f f erences were 4

j notec , the mode l was mod i f ied and a re-analys is was cade. I n t h i s ma nne r

it was noss ible to avoid us ing spectral accelerat lons that were i n a valley of e t ime-his tor y s pect ra. " This approach is sat is f actory but the applicant I

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L has been reques ted to provide addit ional Inf orrrat ion as to meanirg of the terr "s ubs tant ial dif f erences" and a dis cuss ion of to the bas is that was adonted for mod i f ying the mdel and s ubs couently dec iding .that the results were setitfactory.

Except for these points, we Lelieve that t he t ima-h it tor y me thod as used cons t i tuted a reasonat ly conservat ive des ign annroach.

Msa ,me inectrum - In Appendir A It is noted that t hc- 20-inch s uc t ion header, the p ress ure s uppress ion chamber, cnd t he ' rec ircula t ion lines we re analy/ed by the res pons e-s pec t r um ma t hod of ana l ys i s . The only description of the resnorse snec t rum me t hod nresente.d in the f!AR is that associated Lith the rec irculat ion line analys is ,. es presented in Appendix A. From the_descrip-tien of the approach employed, it onpears to us that tha way in which the trc t hod was ut ed was not a t t a nda r d wa y ,' a nd rey not_ be conservat ive in terrm nf the desion values of sherr, rme n t , etc., that it s un o l l e s , Our intrrcretation 64 the conrorch suroests that the ,rv ximum def lict ions we re computad f rom the square root of the sums of the squares of the mocal def lec t ions ,

and tFat t he ma x i mum de f l ec t l ons we r e t hen mul t iplied t y t he s t i f f nes s (na t r i x to obtain seisric f orces. Ir, gen <ral this is not a conservat ive approach, tha hicher rmde effects are gros s ly underes t irm ted and t he .mment s' anc shears gen (rally are not s ubs tantially greater than-that corresponding t o f i r s t r, ode values, The method is acceptable only f or i tems f or wh i ch the higher mode responses arc in fact negligitle.

The St.indard modal response approach would_ involve a calculation of t he s a l ue s o f rnone n t , s hear , e tc. , f or each _ mode and combir ing thes e ennront iett ly, at for e xarm l e by . tid inc ' t he scua re root of t he s om<,' of t he squares of-the modal respbnse valuct. When s everal of _ thel f requenc ies Ile c los

• terc t he r , however, ever. t h is anoroec h .m y not be-corservative end-direct

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5 s unwt lon ' rray be core apprcrr iat e. i n s unra r y, f o r t he response spec trum technique, we can not conclude thet the n*:thod of analysis as actuelly- -I err o lo yed lad to eccentable'velues.

/ cordingly, we havr r eques ted that t he soplicant carry out a subt. tint le t ing anc lys es us ing the s t anda rd res pons e spc ct ror, technique- to assure that the designs are cons (rvetive. We suggest that the results of the check calculat lons be documer'ted.

{ Tes ion Fae ls Earthona6e Analyses - It is not clear-in the material 1

j presrnted in Aapendi x A that all the . items were analyzed f or the Des ign Das is 4

1 j Car thqueb e as well af the ;nerating Basis Earthquake. The app l i ca nt has been i reques t ed to con' irm that all Cles s ! items were checked during the des tpn i

} to be suer that t h( y me t the applicable criterla for both earthquake loading

, concitinns.

E co ismen - Ihe record full peregraph on page 12-2-9 of the FSAR includes a tabuler lis t ing of amoli f icat ion f actnrs employed in analyz ing equinment ,

j ihe coolicant h65 been reques t ed to i nd ic att how .these values were selected end how they w*re ufad in the analyres.

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Mnine - The conr< nt s g iven above . i n thit report relating to methods of

! analys is are anolicat ic to alpinc as well as s t ructura l e lements . t is understood fron,the FCAR thet all-riaing,_except for the recirculation lines and the-20 i n, suction header, which were ref erenced as be ir g ana lyzed by the respons e spect ron met hod , were anal y7ed by the method des c r ibed in the.

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_ ry,e ten inning on nane I;-7.11, which anoears to te bn ecuivalent s t a_t ic - '

l oe c i ne, t ech ni e.uc_ o f c ynn ' c enc l ys i , :n order to ass ess the u rgin of sefets et !< OC I F t f i with t his tx t hnd of an.: l y'. is , the anpl : cent has been reques ted t o L .N f'i I ' :* t h ? ! . t h i t An01 vs if 6,a:-caeri,cd Ja! for i Ot h ! h t . Cor ra t I nc. f as is y an the it5ien Em is Eertbquite . ' Iso it has beg n retues t od t ha t the epplicent 2

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j prov ide a totala r s urrory of s a'Tle s t res s re sul ts , inclucing selsn.ic, J deadicad, orts s ure , and thermi ef f(ct s as aonronriate, to derens t ra te the j conte rvat isrn in the des ign t hct is inherent wl th this annroach. Chvious 1 y this tclulation thou13 is lude s on: compariton with code e l lownt l e stretses l or c,tbc r s t res sef specified in t he c'et ien cr i teria.

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Ir the discuss ion < corr ied on at the site vifit, it was noted that j i

t he s t ac i , wh i c h it a Class I s t r uct ure , has an IC in, d iarr t e r n.n i n n i ne i

connecting it with the reactor Lullding. It was noted that this plaing has 1

not t cen anal yzed es ye t and it 15 understood that the results of this analys is 4

! will tte ccx u nented by the apolicar,t.

I lhe cif cus s lon presented on page 124 .13 et seg indicates that the pining s ys tem suonor t s we re located i n a ma nne r s o o s to be out of the resonance renge Vet, in connection with this technique of analysis, it is

• known that the fler response < rec t r a we re emnloyed in the analys is in som I m.9 nnc r . It is rio t clear f rom the pre!cr tat ion whethar tbc inflar nco of the i

, motlonc at each of.the indisiduel support noi nt s we re cor.s idered in the anal ys is

[_ er whe the r som n erac ing t echnique was e rv loyed ; this needs to te clarified i

I i r; conr.ec t inn wi t h the acd i t ianal d iscus s ion of t he anal y! if , at pr es( nt ed l

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ti l A o it it not clear thot the inertis loads were apnlied i n a ma nne r l to represent tha rmit s eve re cond i t ions of loading (f or exenvle reversed t

! l os.d i ng s on adjacent span!) and thereby lead to an analys is representative of i actual 00:5 isle loadinct. -

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f. l a t s i Structurns located v.itrin Class 11 ftructures The des ion : rovis ions made for C las s 1 i tens located in Class !!

s t r uc t t.r e s is arcsented on nage 12-2. . he first sentence-of the paragraph I

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, dea l i r'g. wi t h' t h i s s ut.j ec t on that nape indicatc5 that certain nortions of .I 3

Cle!! I' t t ruc t ures we r e forvil y des ipntd a'. Class ! s t ruc tures whereas l

l the third sentence notes-that a f ormal des ien enalys is was not carried out, f

I a It was learned at the 17 Septerter 19f9 neeting that actually only a cart ial 1

l ena l ys is of t he t ype convenl y employed f or C lass I structures wat undertaktn -

i i in t och cet t s. The applicent has been requested to docurent the actual jz ent l ys it-des ign orocedure car r ied act t or cases of this particular type l It thould be noted that cer ta in por t ions of' the intak e s t ruc ture i

i j ond certain of tbc nunns are denoted as Class I. For exarole, the RHR i

4 sersice wcter cums are Class I erd the oiping connecting the RHR service i-nump with the reactor building would therefore also be Class 1. 'It.15 to be

, noted that this par t icular o ining runt through a concrete tunnel connecting i

j the intake structure with the turbine building and wi th proper des ign prov is lons,

t hc re is no reason to beliese that this pining will bc serious ly i rme r i t e d i

j Ly relative rotior between the i r't oL6 s t ruc t ure , the turtine building, and i.

the rcotter building.

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j 7_ro ur t<semLly ond ?ection Pcoder i

f- Cf concern i n t h i s n l a ri t , is the det ign of ; the

• uction hcacer which i

i is concent r ic wi th the ' torus-shaoe prest 6re s uopress ion chamber. The i

j. mat er ial present ed i n /s ppe nd i x A on t h i s, s ubj ec t does not-orovide at much 1

! intcrnatien et bo* been race ave liable In s imilar des igni for other plants i

of this specif ic tyne. However, in connect ion with the check of the res pons e f

s pec t rum ene l ys et. , as requested earlier in this renort_, and by which this

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j s ys t en was a na l y, ed ., it is suggas ted t h6t cere f ul= a t tent ion be. g iver to I i

j icent if icat ion of thc modes aed f requenc ies , and the -fre thoc' t y which t he l

competation of stresses end coetination tr'ereof were-carried ost. It would l

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l seem, f rors examination of ihe analys es , and f rom inspec t lon of the s ys tem 4

Itself, that orc of the critical points would be the pine connection joining 1

tha s uc t ion header ar.d torus , esta c ially where it festens to the torus, It is not ed that this j unct ion is rrinforced, but it felle cour,hly mid-way i

tectwee n two torus r ing s upoor t s and t hus coult' be s ubj e c t to considerat.le 3-i notion and flexure.

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It i< noted in the r$/,F and dur ing s i te inspection that there are a rutnbe r of mot or-purp units located on the lower levels of the reector building, t

We we re adv is ed thot at least two of these s ec t ions of tio b u i l d i no , wh ic h a

cont e i n equinnr nt wh ich are c^r i t ic o l for sa f e s hut down and cont a inment will be isoleted to prevent their flooding stot.'d there be any leakage from the torus

! or other nining We concur in this approach.

Feactar I n t e r ne l .

1 The desipn critcric for reector internals was nresenteo on peges IT-2 r, are 17_;.6 of the FCM. T h r- e iscuss ion ref ers to "e las t ic and plastic

• trnin<." ho ofF r (escristion of the technique ermloyed in esaluating these

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1 t i emnts it nrr <rted in the FEtt and t he appl icant har been recues ted to provide e description at to.how the r las t ic s t ra ins were calculated and a i'

de crintion of the tias is ty which tFa cnmut ed. ! t ra ins were comoared to the

design eriterie.

/>n ene rgy c r i t er ion was a lso l is ted in thc same c i tat ion. cs be ing a

anniicet le to the desIan of the reactor internals. Ihr app l ica nt has been requ-sted to indicate whether or not this cr iter ion was ac tually usc d (a) in evelaetire the desian of t h r. reac to r i n t ey r ni I s and f r-) eny wFore elst in the detign c* the f a c. i l I t y . I I

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a i I Con t !,1 rm n t Deticn ftress Criterin v 1 i On oagt I?-? L et req of the trap.rcierence'is made-to strest f in i t.s of "1 % of I,1fC allowables for structural steel. -9T" of yie ld s t rt s t for' l l re l nf u c i n;; s t ee l . -F 3^ of ultiv te stress for concrate." The limits av i

giver ere not comra r ab l e limits so f ar as providing rergir.s of saf ety and the -

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a,plicant has beer. requested to provide further informetion to enable en l evaluat ion of rarpin of t a f e t y that rey be inherent in the asnects of the des ign where these c riteria were ennloyed.

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[  % rsonr+1 Patch rurino the s ite v is it it was observed that the double lock personnel hatch to the drywell was cant ilevered sone distance f ron. the drywell and a .<

l- biological thie ld wit hout any epparent s unport except at its base, The applicant i

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shoulc be asked to confirm that this item has been des igned to witht tand the i -

seis-ic criteria loadir.p .

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j Therrv1 toadings

! The tabulation of loading consideratlon$ that is given beginning on nage 12-2.L indicates that t he rma l e xnans t on load ings were cons idt red in-the dc<ipn of some i t e re . The applicant- has -been reques ted : to ver if y, in all enplicable cases, inc lud ing a lp i ng and equ iptrnt , that thermal loads.were a

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cot ined d i rec t ly as cooroor ia te.

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j -f+ 1 s r ic friteria for r eu_l prv n t Procurerv nt 1

The criterio given in the DSAR and FSi,R f or ' Class I equiprv

nt Ind ica te i.

I that the procurervnt must include provision to meet (e ls mic requirements .

As indicative of such procurement practices,~the. applicant has been reques trd -

to'sunply the se ismic de( l g n c r i t e r i e- for several i t ers , as f or e xarn l e the mein steam isolation velvet and tbc ba t t e r y ric ks , a nd an- indication of the--

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m3nner by whleh chect ing is undertaken to i ns u re that the procurenent f requi rer. ant s have been met . rrom the discuss ions held at the ilte, there

) is reason to believe that these requirements have been checked rather care f ul l y t,y t he anpl icant . <

4 Critleal Ins t runent a t ion and Control 5 j In Amendev nt 17 to the FSAR the applicant has described in f orr deteil the nrocedures to t,c e mployed f or evaluat ion, and i n s ome c as e s testing, l of criticel centrols ar;d i ns t rume nt e t lo'n t o be l n derons t ra t e t ha t these items i can perf orm sat is f ac tor ily under pos tulated acc ident condi t ions, We believe j the c r iterla given therein to be adeqocte in evaluating these item of i

} control and ins t rumentat ion et t h i s t i re insofar as i t is presently possibic i

} to do 50.

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It is to be noted in this case the main vent steck has been located at a dif tence f rom the fecility shich would pre;;ude i ts striking the facility should it topple.

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After a rtvlew of the f AR, cod anendments thereto and the other ra t e r ia l rudt available to us t hrough d i s cus s ions , we be l ieve ' t hat the

, des ign is probebly adequete in terms of provis ion for sa f e shutdown for a e

Des ign Cas is Earthquak e of *

.129 maximum hor lzont el ground accelerat ion and i

to withs tand otherwise the ef f ects of en earthquale of half this magnitude.

1 How ve r , on t he ba s i s o f t he inf orret ion made available to us , it appears that the margin of s af et y inherent in the des ion po?s ibly may: not be as great as

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I might have been intended. The i nf orrut ion f urnished to da te has not been co~r le te enough nor exol ic i t enough to rrect our evaluat ion requi renents.  !

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_W e trust that tiic addit lonal iniornat ion to be suvlied later by the l anol ic ent will dernons t rat e that the design 15 unqua t iona t> l y adequa t e ,

F f f f TJf.C ! f, 1, ' r i ne l ! e f e t y i ne l ys i s Et nor t , Vols, I t hrough V)1, t+nd Arendnw nt s 10, 11 17, IL, 15 and 14, tunticello fluclear r.entrating Plant, tu ticello,-

Mirnesota, Unit 1, Northern ! totes Sowe r Comsany," 1968. and 196?.

2. Adaquecy of ttie S t r uc ts. rc I C r i ter la f or the MontIcel10 Nuclear Cencrating '

P l a nt Unit 1," prepared ty N. P. Piewm rt and W.-J. Hall,'under AEC- '

Contract No, AT (L9-5 )-26Q , ine rch 13 ' */ .

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