ML19294A917
| ML19294A917 | |
| Person / Time | |
|---|---|
| Issue date: | 02/24/1978 |
| From: | Vassallo D Office of Nuclear Reactor Regulation |
| To: | Grossman M NRC OFFICE OF THE EXECUTIVE LEGAL DIRECTOR (OELD) |
| Shared Package | |
| ML19294A895 | List: |
| References | |
| SECY-79-88, NUDOCS 7905080278 | |
| Download: ML19294A917 (6) | |
Text
I ENCLOSURE 1 TO ASYMMETRIC LOAD CONCERN t
i FEB 2 4 M Distribution:
I Central Files F. Williars (2)
H. Smith (3)
-)BNP File ([ $
ilt LFA:wF. iO.:..ilton J. Cross; tan, i;earisq Divi 31cn Director ona Chief Lounsai, GtLD t
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'icc a.110, f.csictant Director for Lijut '.later
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L.c recor/ conj that f ou trandnit the enclocca 1...r. cran.iutt, uated..LVer.J0r
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1977 trc... l.. Utiaer tc, R. Tiller, Director, Reacter :.Marctions anc Prcer.n I~
Oivisicn, l.0n0 u/.:rstiona ufficc, D0part:':ent 02. Laer;lv, cntiticd Pds. 3:el Asner.oly ix;cnanical hec;mnse Juiclysi:
.AIG-316-77," to all sitting 00 arcs i
for t..~tt telants.
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~ihc resulta et analyses pertorr.ed by LOLC inu tcate tnat ascatric Icaac curing Div..uwa following a nostulated ions,L-cociant cecident cauld f
1e00 to 2.:.lification of loadc on fucl grid.:r.7cet o depenJing on cote suoport
.olate reLionse frecuenc'/.
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Tne i; orth I.nna coird has been notifico of this analysis toroc;,n cn Mfidavit dateu noverMr 23, 1977 by Mr. Alex Dromerick.
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I ca s nclc::u..; c aa.ple letter tor you to ute for the eurpose: cf tranccitting the results of tne analycea contcined in tac !:0&G (IC,no)...c..orancM.i.
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ORIGINAL SIG:iD BY h U M y y u
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O. 8. Vcs30110, Ascisi:Ont Director
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for Li:nt : vater ficcctors iP
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Division of Project :;ana:;ement t:nclosures:
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- 1. 11/4/77.cac trc.1
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it.Jtiger to ::.Tillar, 790508021K
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Milton J. Grossman FEB 2 4 T:73 cc w/ enclosures:
E. Case E. Volgenau R. Boyd R. Mattson
- 11. Denton R. DeYoung V. Stello i
K. Goller T. Engelhardt J. Stolz K. Kniel O. Parr S. Varga I&E (7)
P. Check R. Mattson E
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fiOV - 4 1977 R. E. Tiller, Directer Reactor Operations & Prcgrans Division l
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PWR FilEL ASSEMBLY MECliANIC.M. RESP 0::5E A' ALY3IS - 5:1 -316-77 9
r Ref:
(a)
R. L. Grubb, P.:R Fuel Assercly M :henical Res:ense Analysis, Idaho National En;incering LctOratory, RE-E-77-141, l!:rch 1977 (b)
R. L. Grubb, PUR Fuci Assen:ly Mcchenical Respense Analysis, A cnd ent I:o.1, Idahe 'l:tional Engineerinc Laborctory, RE-E-77-140, March 1977 i
(c)
R. L. Grubb and D. F. Saffell, Jr Ncn-Linear Lcteral Mec5anical Response cf Pressurized !! ster nest:Or Fuci Asser:lics, AS.':E Paper 77-; A/DE-13, Occcmber 1977
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H. Nuno, M. !!i:uts, and M. Tsumuna, Develo;nent cf Anvznced Mothed Fce Fu:1 Seis-ic Analysis, 4th Intern tional Cen#c-ence en Strt'ctural t'echanics in Gesct:r Te hnology, San Fr:ncisco, California, USA, August, 1977 (e)
R. L. Grubb, Feasability Study fer Dounding the Lateral PWR Fuel Assembly Mechanical 2cssonse Analysis, Idaho Natienal
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Engineering Laboratocy, RE-E-77-160. Rev.1, puly,1977 i
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Dear Mr. Tiller:
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A pararttric study to assess the effe:t of variations in ccre clate notions '
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en fuel asscroly s acer grid crushing loads is curren-ly in cr:gress.
A sunnary descrittien of this s: dy inciuting reliminary results ha: been pre:ared : the recuest of the *:J lcar Renulatcry Cs7-issica's Civisien
'e cf Systen Safety, Cerc Perfern n:0 Brancn. Results of this study incicate
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that a small */ariati:n in c:re plate frecuer.:y. cy navc a siqnificant effect en s?acer grid crushing loads. As the study is not complete, thosc
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results snotid ba considered preliminary.
I' A nechanisin v:s ;:stulated in Reference (c) which indicated that the in-put core plate retien cculd significantly affect scacer crid crushinn Icads. The prircry cbjective of the ;resen study ves to determine if 6
this ncch2 nisin could be shcun to exist. A sec ndary nb.ic: ive is t:
corcare linc.ar end nonlinear analysis tecnniques.
In sermary then the i'
purpose of this study is Oxofold:
r; (1) Statistically detartine the effe:t cf c:re pla:c frenuen:y ar.d agnitude on the fuel asse:Oly raximun scacar grid crushing leads, and x
(2) Stitisticall. c:r?.'.re itncar and nenlinacr analysis rc:."eds for laterai fuel ass:ntly ec:52nic:1 respense in an a::: p:
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to sim;ilfy :nc n:niincar analysis.
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E R, E. Tiller h0 - 4 idil Stig-310-77 Page 3 t
Reference (e) could actuall.[be clicited in the nenlinear analysis.
anisin appears to c.v.ist; thcreby causing concer.1 The mech-that permancn deforna tico of spacer grids may cccur.
Upon completion of this study the conclu: ion:
in11 be rec:sessed.
prc:c..t:d in P.aference (b)
Very truly yours, e n c:N t.t s:CC Tr R. R. Stiger, "anager L
t-Reactor Sebavior Division BFS:cij V. Stclio, NRC-CCR P. S. Check, NRC-CSS S. B. Kin, NRC-DSS s
R. J. !!attson, MRC-CSS j
R. O. I'cycr, IIRC-3SS D. F. Rest, ilRC-CSS s.
R. W. Kichn, EC&G Idaho P
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R. L. Grubb t
R. W. i4c2k
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C.F.Cbenc5ain(?I:.g' B. F. Saffcil id:' ---
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NUCLEAR REGULATORY COMMisslON
. y WASWNGTON D. C. 20555 s, - /
SAMPLE LETTER SITTING PLR Boards (except North Anna) i
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Gentlemen:
Results of recent analyses performed by the staff's consultant at EG8G, Idaho, Inc., indicate that the fuel assembly spacer grid impact force resulting from asymmetric loads during blowdown following a postulated a
loss-of-coolant accident is more sensitive to the core plate motion than was originally thought. Since it is difficult to calculate the core plate i,'
motion exactly, there arises a question of margin to deformation of the fuel assembly grids in pressurized water reactors.
1E' The consultant states in the enclosed memorandum, dated November 4,1977, that this information is very preliminary.
In addition, the staff's pre-liminary understanding from Westinghouse Electric Corporation is that j
they have not observed this sensitivity to core plate motion in their Q7 analyses.
Given the magnitude of the sensitivity, the preliminary nature of its iden-tification, the margin of failure in the spacer grids, and the generally acknowledged capability to cool the core even in the event of local spacer grid oeformation, the staf f determined in the North Anna Unit Nos. I and 2 f :,
proceeding that its conclusions that the fuel assembly design is acceptable, as stated in Section 4.2.4 of Supplement No. 7 to the North Anna Power t
Station Units I and 2 Safety Evaluation Report, remains unchanged. For
'e other pressurized water reactor designs, the staff at this time concludes l
that the bases for acceptability of fuel assembly designs are unaltered by the EG&G preliminary analyses.
h'.i However, the staff and EG&G are continuing to evaluate the nature of the sensi tivi ty.
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Enclosure:
Memorandum dated 11/4/77 l
m R. Stiger to R. Tiller, Idaho a
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1 (3) di n res ect t: tae reac::r c:oian: ;um: fly.. eel mi ssile (pp 57-59), the a:plican; sta es :na :
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The generic s:acies are eing :er' I
of suetan:1at:ng or.;cci tying cu-pin.c.ec : r :na ;ur;ose
- ma: nema : cal mcce; tnat precic :ne pump performar a cur:ng i LCCA."
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Tne staf f ccncurs tha; :ne :r;&acility of a LCCA cc:uring wi n accitional c:nsecuences/causec :I :ne -ea:::e c: clan-v f.
pu=o flywneel mi ssiles i s,56all; newe rer,.e c
- c:::l e.
gg ci scoun :ni s :os 11:ap/2-1 cent. aa:ne, :ne s aff nas e
ce:erminec :na: tne ;r,..aaiii:y :s 1:w encu n na: -- s
- cs ula
- ed ac:icent ::es n : resal: in an unac:e::2:ia L
t c:ndi -i on.
Studies are se g concuc sc by :ne Elec:r:c Acwer Researca Insti tu'te (is I) fa provice-int:rma :ca regar:ing at s ca-.
anen :nese tudies are ccmpletac, ney will ul;ica aiy suc stan:- :a or refuta :ne c nclusi:ns reacnec in ne-b aestinc.cuse ::sical recor: 4 cad-cl62, "Reac :r C:cl an-Pumo n egrity in a LuCA.-
at ne ;resen :ime, :ne s aff ha not evaluatec ne c:nserva:isa in :r.e calcula ::ns esentac in aCAP-dl62.
(41 di:n res:ect :: :ne rest:ual nes: c er.cv al ( i.- A s/s em.Ove-pressure pr::ac::en (;ags 77),.e agree ni:n '.'E?CC's res:cn.
excap: for :ne foll: wing:
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a) The relief valves are 1cca ac :n ne suctica sica of :ne RhR pu=ps (nc :ne c1s:narge - ; age 7c); anc,
['i o) k.
ine set pressure is 275 :sig (nct 50.' :sig. : age 73).
(b) ai:n respect to LCCA Ef fects en fuel inc ?i;e dreat 5:ec ru.-
(p'p. 74-77), tne a:plicant states ::at:
I
Using :ne assucc::cns an :ne version :f - e 'ut FLI.(
c:ce a:or:vec ey :ne 'GC 5:afd, :ne analyses :emens-4:2 p
- na: sucstant:al margin ext s:s :et.een :na 1::lt ec 1:a::
sne :ne Icac a: -nica r.e fuel gr1:s s.:;ic :: ac u.
ica ing.oulc sustain ceasurt:l e :erra. en :e r a:::n.
(: age 75).
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I Frca tais sen:ance, anc tne c:ntax: of ne res: ef ne page, it could oe inferred tna: MULTIFLE.1 calcula-icns using the rice n Anna c:nci tions (i.e.. a :rea( area of io square incnes anc a are < ::ening ::ce Of 10 aill:.
i seconds) were cone. In fact tne analytical r( c:.cistac of a calculaticn cone wi:n :ne approvec c ce vers;ca, at a creat area of.cne square (co; anc a time of cne mili -
i sec:nd, in ccm:inaticn witn an esticaticn of :ne lead recuctic using c ner calcula-icns. Tne staff a:Or:vai O f 'aVLTI.: LEX,
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In i:s Saraty Evaluatica 7.e;ce: Of c/17/77, c:: no-incluce f.
MULTIFLEX a; creat c;ening times c:ner nan ene millisec:nc.
In creer :: turtner ex lere ne ef fe:
f :rea( ::ening time, It crea( area, anc ne flext:ie wall assum::ica. One staff anc VEFCC recen-ly :ericenec acc1;tenal calcula:::ns.1: 7 ; ese parameters as vartacl es.
Inese stuct es, a'. n=egn c; ye-tully cocumentec, c:nfirmec cur earlier juc; men e3:ressac in Section 4.2.4 or Su;;lemen: 7 :: :ne acr:n Anna ? wer Statien, Uni s 1 anc 2 Sate:y Evalua en ie:crt, wnica was arrfvec at :y :ne c:: ination of an a:provec MULT*..: LEX
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calculation in c:ncer witn approxima a sens1 1vi y s::cies.
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We uncerstanc :na: VEPCO will c:cument :ne results cf :neir calculations scan.
dita respec- : ; age 76, ne 1:mi inc Ocei f:e :ne rea: cr i n l ',
pressure vessel su;;cr used a limi ac Ois:iac-men :reic, mecelec as a sic, not as a guillotine treis as 5 2:ac :y s
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VEPCO. Inis mecel is ac:aptacle anc c:es c.c cnange cur c:nclusiens regarding tnis mattar.
o i n rescect page 75, ne wcres, "suostan :al margin a
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- were used in :ne ciscussion rela:1ne : ne ruel r:c s; acing recuc:1on curing a postula ac ac:1 cent. We eiteve v - < '.
tnat *acequate* ratner : nan suostantial may nave :een core a;propr14:e. Mcwever even :nis cualifica 1en cesaries rurtner attention in v1ew of tne felicwinc.
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As a rela ac mattar, ne :ecame aware in C :::er, '-77 :f s
new in Ormatica in ne ma ter Of ne 1 ruc;;ral es:ense of reactor in arnals :: asymmetric i:acs. Our c:nsai ants a: EuaG. Icano, Inc., wn: ass:stec as en ne sce:- Anr.a eva' 43%
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are providing ar.alysas in succcr cf ou. generic review of calcula 1cnal cocels for cca;uting strue ural res::nses ceing cevelopec by reac ce vencers. Iney f: enc in a sensitivity stu y nat :ne gri: ic:act f:rce i s ::re sensi:1ve :o :ne c:re pla:a
-icn : nan as crigina;;y ncugn. Gric ic:act force i s ne ::nt. :iling tact:r :n
- ne fuel rec spacing. Since it i s dif ficul: '
calculate tne core pla:a cc:icn exactly nere arises a cues:1:n of l
cargin to ceformaticn or ne fuel grids at Nce:n Anna and al] c ner pressuri:ec wa:ar reac::rs.
ine consultant sta:ac (Encicsure 1) :na :nis new inf:rmatice i s very preli:sinary. In ac:1:1cn, our preliminary uncerstan:
from Wes:1ngneuse is na-ney nave no casarvec inis sensit:
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- o core cla a cc:1cn in nele analyses. Ins staf' : s ::nti.
ta evalua a ne na:ura cf ne sens1:1v1 y an: ne sens: :v' y s acy itsal t centinues at iGsG. Ints :aars :1 rect < cn :ne t
c1scussion en page 77 of tne VEPCO res:ense 1:n res:ect tne conclusion regar:ing cos: severe potan tal c:nsecuences-Given tne magnitude of :ne sensi:1vi:y, :te preliminary na:;.-
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of its icentifica:icn, :ne margin,of failu. e in ne grics, ant i
ne generally acknowlecgec c,3 acili y to c:ci ne ccre even l
in :ne event of Iccal gric cef;rma:1cn,.e nave ca arsinec :
cur c:nclusions sta:ac in Section a.2.a of Su:: emen No. 7 -
ne Nor:n Anna Power Statica Uni ts 1 anc 2 Sare:y Evalua ;ca Report regarcing :nis ma :ar remain uncnangac.
h Question 2:
To na: ex: ant cic :ne Staf f c:nsicer na ;uss-icn of "asscela ac circuits in its review of :ne reu;ing anc ince:encenca of safe y caoles in :ne Nor:n Anna Unt:s 1 anc 2 installa:1:ns?
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t-Aesponse:
Tne conce:: of asscciatac circuits
- was first in.Ocucac in
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Regula: cry Guice 1.75 (wnica enccrsec.EEE S:: 254) in y72, several years arter One star: of c:nstruction of Nor:N Anna Units 1 and 2.
ine crux cf :nt s concern is :ne in arac:1cn of s ';
ncn-saraty circuits on :ne incepencence of recuncant saf t:y systems anc circui ts.
uuring :ne staf t's review cf :ne Nce;". Anna 3::lica-icn, i-L nas estaclisnec nat ne critarten fcr rout ng Of :n-saf t:y r
er c1rcuits <n1cn ecame assccia:ac <i tn safe y cir:;i:s :s na:
ne non-sare:y cacies ere no :erm:::ac :: :e in :!:se :r::::1 y with, or reu ac *1:n mort : nan ene 01visten :t saf ?:y cam:-s. Te a:011can: was recuirec :: i :lemen :ne :'in :::l e e:u:: ag : -e a::ve stated Cri arien inc 1: A s 1 *. 2 v i s1 *.
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Na :ne Olin: ca:le r u nj -as ic Iecen 2*
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- nts Ort:arten. Ine staff nas perf:rtec an auc:: :f :nt s ces:;n 1F""Y anc nas found tnat it satisfies ne a:cve referrec :rt arica.
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4 ENCLOSURE 2 TO ASYMMETRIC LOAD CONCERN 1
April 10, 1978 Note to Domenic 'lassallo, Assistant Director for Lignt Water Reactors i
Re:
Your Memorandum of February 24, 1978 re EG&G Analysis i
of Assymetric Loads I
He agree that the letter from Stiger to Tiller should be sent to
, ~
PWR licensing beards.
However, the sample letter of transmittal materiali ty of t his informa tion.
Similarly, tne Drcarick affidavit that you provided is inadequate to describe the relevancy and
(
is somewhat ambiguous to use to identify relevancy and materiality.
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p However, it is wr understanding that the probleu identified by EGSG I
relates to potential bundle deformation only of a localized character in peripheral bun'iies and does not seriously af fect maintenance of a coolable geon;try of the core.
'.i-i If our understand ing is correc t, this should be discussed in an
)
P attachment to the ielter of transmittal 50 tha t the boards can iden-ti fy relevancy.ino wi terial i ty.
If car understanding is incorrect, tee will need adoitional discussion of the technical significance of the ma tter raised by EGSG so we can identify its relevancy and ma teria1 i ty.
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% M xDAW N Milton J. Grossmar, Chief Hearing Ccunsel u.
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i ENCLOSURE 3 TO ASYMMETRIC LOAD CONCERf1 O
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- pa 12 G73 Distribution
Central Files w/ encl.
F Uilliams F. Williams RDG w/ encl.
-9BN-91
':DiUM;;0:1.'! FO'-
Roger J. !!attson, Director, Division of Systems Safety, liRR
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D. P. Vassallo. Assistant Dir.ctor for Licht ' dater j
Reactors, Division of Project fianager.ent,.NRR s
SU3 JECT:
30ARD.'OTIFICAT!O:i - EGSG A' ALYSIS 07: ASYMMETRIC t
I' LOAUS (Dii-91) f.
EncloscJ is 't. Grossman's note regardina cur recomendation s
t to noti fy P' P licensing ';ocr:1s as to the EC.'.C study on asyimetric t
f.
loads.
I ';ould appreciate additional ir.put fro.a appropriate DSS branches to 0.ny:ent the proposed Soard letter as discussed in the
-s note.
For eve of reference I ca enclosing copies of relevant doci.t..:ents in our file.
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- Origir::'si; n:4 by D. B. Yan2M y D. D. Vassallo, Assistant Director
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for Light U.:ter Reactors
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Division of Project Management
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Enclosures:
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As stated L
cc w/o enclosarcs:
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ENCLOSURE 4 TO ASYMMETRIC LOAD CONCERN uNiiEo 'atts 8 '.
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NUCLEAR REGULAlflRY CL
.k WASHINGTON D.C.20555 s.,,
j ms 2 s es MEMORANDUM FOR: Milton J. Grossman, Hearing Division Director and Chief Counsel, OELD FROM:
D. B. Vassallo, Assistant Director for Light Water Reactors, DPM
SUBJECT:
BOARD NOTIFICATION - EG&G ANALYSIS ON ASYMMETRIC LOADS (BN-91)
Our recomendation of February 24, 1978 (enclosed) on the subject issue
[
i was not forwarded to Boards by OELD on the basis of inadequacy in the determination of relevancy and materiality (your memorandum of April 10,
(.
1978).
We requested clarifying information from the technical staff.
Several conversations with the staff on this subject, however, indicate that the E
technical description provided with our original memorandum is considered to be a clear description of the issue and they have nothing to add.
I recommend the issuance of the original description to Boards with a notation, if you think it necessary, that they must determine the relevancy
,x and materiality.
t.
2:
D. B. Vassallo, Assistant Director for Light Water Reactors Division of Project Management t
Enclosure:
Original recommendation
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cc w/cnclosure H. Denton J. Stolz E. Case R. Baer I- [.
E. Volgenau
- 0. Parr g g-R. Boyd S. Varga JV R. Mattson I&E (7)
%ONIg g'( O R. DeYoung P. Check F
V. Stello o
K. Goller T. Engelhardt L. Nichols
, B. Grimes Mh.
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.