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i December 27, 1967 4
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Dr. J. I. WKee, Sobeamunittee Osstreau
, is Prem i
- 1. F. Praley, Emeeutive Secretary Advisory Ceumittee em Rosator Satwawards
_-t*1et i 073751 mitt WUcLEAR FtArt, P0881512 CAUSE OF PRES 8URE YE888L (8tTE 1958) emarrrag Mr. EW6eriesten has provided the ettethod eve 1wation etch indicates that high stresses eaused by the stub tube
- red drive esmale weld ney be the cause of cracks in the Oyster Creek reaeter pressure vessel even without the ontdentified eerresive media that a has eussested as a major eentributor.
In view of the ebeve, he has suggested that the applicent provi4e en esslysis of the stress distribution in the area tavolved.
t*L has todicated that en analysis of fabrication med operettaa stresses is being done by Combustion Restseering Cerperation and will be provided for review as part of the information to be submitted in ceanection with the proposed vessel repair.
A discussion of the status. f the Oyster Creek project is scheduled for the January meeting and m id be en opportune time for you er Mr. Itherington to discuss this further with the Regulatory 8 tart if you desire.
Attachment Memo fra E. Etherington to 1.'17. Fraley dated Dec. 10, 1967 Bubject: Dyster Creek Reacter Vessel tapair copy to Remaining ACRS Members v/At tachment Cy to WL v/ Attachment t
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Calcunstion outside laside Average Thieknese
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Radius Redius Redius t
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B lable 2.9875 2.375 2.681 0.6125 1.016 S. 3.Ma106 stub tube 3.750 3 000 3 375 0.750 0.908 1.95:106 If the radial force is p per inch of 6treueference (1 have met allowed for the dif ference between redit of thtaele and r, tub tabe):
. l 0.001 = 5 ?
t 4 2 typ 2kg k 2 Where suffix 1 applies to thimble med suffix 2 to stub tube 0.S^F = 1080 lb/ta.
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Wantmum bending stress in thimble = 6(F/4Bg)/tg2 = 4250 pet, at the weld.
Maximum hendtag stress (a stub tube = 0.325(F/s2)/tl = 4600 pet, at (7/4)/82 =-3.97 helow the weld.
Weld toeperature change IAT necessary to produce 0.001 is. relative dio-placement en cooltas of welds suppose effective weld material to a ring with a 1/2 toch x 1/2 inch. square cross-section, and ignore extel and tangential contraction:
0.001 = 1/2 a _t F/t
( ~ - 10 5, 5=28 x 10 )
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= 232 F /,8sy 200F, allowtag fer extel and radial effects)
Commenta 1.
The calculated stresses in the illustratten are caused by a temperature thenge of 200F, and the stress to the weld metal under this condities to enly 2160 pet. The centreettom end stress ta the tubes seutd readily be l
two or three times as high as calculated.
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2.
It is met evident without further calculation hev the picture changes for f
a short tube.
(a) The stif fer tube would tapose amore defleetten of the thimble and i
greater stress As the thimble.
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(b) per e gives rediel defleeties, she benstag otsees to es ogsb tebe seuld be meeb areeter $sr e ehert gebe (osy less thee I j
te. ). Per a gives and,med, the heading etsees mould be l
g for a ehert tebe. N estest eseditten lies botenes l
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aletts. b tabe to of the outer strete.,tggy abort (oboet % te.) et the seteMe y.71 i
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(c) Even fet h Imag tube, oboar stresses are est small, fler e nort embe ther esmid booses reistively more importset, and the direettee of the esatsene primetple stroes (ealeelsted by Mehr's strele) esy wil seplein the ebeerved estal inslienties of ereeks.
P 3.
Per the obert espuestric steb tube, the stresees meste be emeh bisher se l
the short side.
4 4.
N sold between the stub tebe end pressure vosoel obeeld be seasidered i
fer its effect se roeidest etsb tube strees.
5.
It appears probable that the generet strose level to the
},3 to est hish, this ebeuls be esefiened. boosese e stress setvestem flere bore
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emeld have the seik.iege of a ree ejeetles sesident.
i 6.
N eas17ete, it ende, eey eentreet the mesumittee with the problem of takins e posittee ce resteuel otroemee is smoose of these presumed to exist la e otrosessemated vessel, med me tobriestsee and erestice stresses not elleeed fer to the vessel design.
Le the esedittee seeeptable eer Oyster creek, but aset the desige be ebenged for vessele est yet shipped free W eseufacturert met abost thermal stress free seel ester tajested l-through the thimble the abertest stub tebes emanat be very effeetles as thernet ebioide.
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- 9eseret solutten for thimble with stub TW of Def fere taesth f
N ro etti he tee eets af fear equettene, one for the thiebte sad see for the eteb tebe:
1 yae a(A see s + 5 sie e) + e" k(C ees a + D eie m) and the emeemosive derivettves of y wit respect to a givisas aquettees for elope =,(y, jf._
and 1 = d
=
da RI da II du 3
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Wding somsters of scmeentric radial leads y med M,, Per book of strousv forense, at the esid.
Per eash tube six constants must be determined (the fesv ocw 1
hes grettaa A, B, C, and 9; med the two imods y med W..
N twelve osmotesM T' noe be ses1 mated from the following bending desditisaat g, f, b N aeds of the thimble are free, bense end are tears ak '
both ends, givtag fear egnations.
(It is aise probokly entffielmet to seasider the leegth tuttatte, in wktek ease A a 3 = 0).
ga fixed and of the stub tube is fully eemettelmed, besee y = 9, 2.
= 0.
(If M o ite4, e1tcruettve aasungtimme saa he essee esmeet M ag shrimtage of the wid between the vessel and thr etub th).
i 3.
At the toeld Oo the t le, addit 1 ognattass far the atab l
obatt are given by e
and
=2 dx 1
dx II 4
At rkt weld between the tatable and the stub abatt yg. y; =, se arbitrary displacanest determined by the weld eemtreettom. Atee at this point the slopes are assumed to conterm, i.e. (dy/ds)g =.(dy/ds)2' The eleventh sad twelf th equattaes are given by (N )g = (M,)2 "N o
(as adjustment may be unde for dif feros.ee er re.dii).
pg.pj All twelve constangs can tghe evaluated and the bending stresses een be comp tea from s a e
- c the shear i m s is statlerty u ta lit a g
from the formula for the third derdwative.
I em met pr*P*sima to pressed with this work, but I esi suggesting that we sensider requesting tlee appliaast to snake his own analysis if he has not dame so.
I Calculattee for a stub tube of mem uniferu length wealt be diffleult 2nd would require staplifying assuagtions.
It may not he siecosary
- .o esake this calculation.
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N. Ethertagtee Dec. 20, 1967 e
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t At 91et Arts ) sagy 13C g4.'h 1
h canalttee oeotissed its review of the Dreter Greek p1 mat. An e' '
result of discuesten4 with pal and the appiteemt, the Sumattles infommed Jaroey Cemtral power and Lisht Osepony thet tt wom14 have creet ditfMylty in apprwtas preteng>ed operetten of the pyster Creek plant withmet additten-si protoution for the small primary piptas break mies, b Dauntttes esadersteeds from as estaber 27,1M7 Letter that the appitammt is propesud te pewide additismal htak pressure emelast injostien supebiltty umAir tasa of off-site poser seedittens, hs committen informed the appiteest that it eente eo see a prelim 1 mary design for anditiemat ktsk paressure ears eeottag befwe it seaplates its rwimw.
T n o.,,1 tea e e. tee re,
...d to wers with pai. eei (a) aseure th t adequate wederstandtag amista of the nature of the samtrol red penetrattom weld ernsking (b) reach agreement that the problem has been eaglered adogmately as te the estant of seaskima (c) assure that the proposed solution is adequata (d) rwiew quality sentre1 dwistiana es other essential partions of the plant, such as reported are strihas em primary systes pipes and sampoemats, quattty et pipe, etc.
he Committee Lodicated that it wishes ce see the reestts of absee tapestisa-tiens before it soupletes its twtow.
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