ML17309A417

Informs That Indications Detected in Inlet Nozzle B of Plant Reactor Pressure Vessel Meet Acceptance Stds of Section XI 1974 Edition - Summer 1975 Addenda,Table IWB-3510 of ASME Boiler & Pressure Vessel Code

ML17309A417
Person / Time
Site:	Ginna
Issue date:	03/15/1979
From:	Curtis A ROCHESTER GAS & ELECTRIC CORP.
To:	Hazelton W NRC
Shared Package
ML17261A806	List: ML17261A805 ML17261A813 ML17261A814 ML17309A414 ML17309A416 ML17309A417
References
NUDOCS 8901130194
Download: ML17309A417 (22)

Text

Z ge Gixzw Stat'cn March 15, 1979 Nr. 3v'ar en S. 2~alton NucleaRem1 a"ory Corrmission Was'.ton, D.C. 20555

Subject:

Code ~sea tabil' o "~e "3" Lalar '.!Ozzie =L=-.- )rcic=-="'cn in t'.-.e R. E. Gi wa. Reactor Pressure Vessel

Dear! . i.~".e tcn:

CCOC..aster Gas c Q "l2C. C Cor O at:~ P~ C .;C Uda ."-: '2:. 'a '~"S detac"ad in ~".2 "3" inlet nozzle o= ~".2 2,. E. Ginna) Reactor Pressure eSSe at <<<<2 m)eet \

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Ccns2.st nt 'R.i:. ) .2 r Qua t or Hcc.. sta Gas c lo ~ ct "c, out.Bast Rase"-~c'.". ns-= ta ca'e)c"ed a tac.".n='"ue ano the necassa=p associa=ac aaui c t to C~ao>> a., U., aSC, 'C 2=.. aswarm - llV De"aa )CiCul=-. tO subja " "'2 o =-."'s. T.t vas

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~.-ould "2 m"2 s~wi=='-."2 ."".~~ t."e c"ca "'e-."'"e 2~" '~=t"'~s o" =.'..'s area.

A raVLEv- Or i."2 U' aSCP'C 2~~'~at-"" <<=Su tS OZ tna '~" ~~~) ar nOZZ'2 =0 vessel aid c~".cnsi=ata '-;2 inc=ease sa.)sit='vity ~at'". "'".a "..2-: i;- cave-opeo a~=-v-'".ation tacana a. Spa.>> "c-'ec""rs vera catactad vi=h "'".'s tacizic e .4'la not '=em~ detectao 'c.= ~".2 Code defineo anzac"'narions of this area cur'ag the Y~~ch 1979 outa=a.

This c early de .Onst=atas the supe iority of this 'newly cava oped techniat'e. Part of the devalo"ment effort of this technique included cons~ceration or nc .al u'scnic cern spread. 3y coL. a imper=act='ons to "'".2 recorded e~mi~"-tion results a conserva<<ively hara in'i~ -ta acct'-ate prediction of t")e reflector size is obtained. Uti '"in'his technic 2 ~d agu "rent, a ref lecto o less than .32 inches (th"oueh-val'.) a- cetac"2 '. z iwer=ecticn o" th's size meets the acceptance s iandards ot act:c,l ZZ.

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Mzcn 13 I /9 Page 2 of 2 Therefore,;.-e conclude that the 15 degree refracted long~ eudinal angle bean e~~i'ticn of the nozzle to vessel velds -.=ca the ..ozz'e bore confirm the s~~c=~al adeayecy of Nese nozzles in accordance ~~~th Section ZE of &e .~~f"" Reviler and Pressure Vessel Code by virtue of the demcnswat d a'pe iority of tMs ne..-ly deve oped t chnique over Code defined e~mtions.

Sincerely, Albert E. C~~is Beld~ .g and Ncl ces 'ct:ve Level iT~, UZ, W, ~2', P",

AEC: kes/d2V The nevi- ceveloced t ~ ~" Ke descr'=ed "-ave 1w been c~m-..s =-"=- '

to yiela s. "e 'or = s" ts to v sat=ac""c..

R. J. Clave~ e ins"ec icn Spec'- 's-H8 0 o +te:- 1 ~03.'e inspec"='cn '~~ =~~=--.ce Cm .y

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BEAM SPREAD CORRECTION W. C. HcGaughey Southwest Research Institute San Antonio, Texas 78284 B earn spreaa measu asuremencs have been a Section XI requirement since the 19>3 Summer A'd a en daa, Paragraph I-4460, became ez=ect"ve. Section Z , p

'graph IWA-2232(a) rezers to Section V, Article 4 for ultrasonic -asonic .examination rules. The latrer Paragraph T-431.3 requires beam spread measuremencs ar.

intervalsal no greacer cer than 3 monchs. The beam spread measurement'echnique is in the nonmandatory appendix as Paragraph B-60, so ocher techniques may be used.

No use oz beam spread measuremenrs is specified 'n the Code. Unozfic'al but generally recognized justification for cont~ning the requirement include (a) identificarion oz beam variables to assist in selection oz a search unit zor a reexaminacion at a later dare, (b) to have the informcion avail-able ien it is determined how co perform beam. spread correcrion oz inaica-tion ai ensions.

Dur'ng the =eoruary 1979 Ins ervic~ Emv'nation oz the Rochester Gas ana

-"'c Com an 's Robert E. Ginna plant, a complete mechanizea examina-t"'on oz tNe reactor pressure vessel weld was accomp~ished. 1"' 'hese Th examina-tions d'isc osea the impe =ect"'ons n tne weld or assoc'ated oase meta ..

. e oresence oz several ultrasonic rezlectors due ro cal.:!ost were readi'ece oned to be within the ASME Code acceptance stanaar!is.

os" oz oi these ese re leccors Therefore, further evaluation oz these reflectors was no ne recoraed for =uture rezerence. One nd'cac'on veld oz 'ozzie 32%%as oz an amplit ae reauir.'ng furrher evaluac'on on oz 'cs

" ce. Ii&rcer to perform a fracture mechanics evaluation oz t"e t..e signi="'cance oz this re lector, the true size oz t.ie z~aw was .

A process oz eva~uacion oz t'x"miaacion the aara was unaertaken in an acta= c co dece "'ne the size ana narure oz this re ec ror. Also controlled exper.'-

ments were perfo=ed to conzi~ che accuracr oz thhe theoretica'alcu'c=cns and considerations.

't Recoraea mechanized ultrasonic examinac'ons penni reaaing indic t=ons t7 Oi.

DAC ana greacer. The 0', '5' 0 , ~5 an 60'xaminat'ons zrom che inside sur=ace oz the vessel as we 11 as c.4 e 45'xamination from the nozz'e bore show no record of the indication detected with che 15 angle beam longitua nal wave from h noz"" e b ore.

the The plane oz maximum sensit"vity is the same for the 15 nozzle bore and the radiographic examinations. his is supported by the zacc that no ultrasonic response from the imper=acr"'on "h 0'5 and 60 examinations per orated on the vessel wall or from the 45'xamination also performed from the nozzzlee bore. ore. These e tially perp essenti erpendicular to the 15 longitudinal wave i

obsezvarions indicate rhat the rezlector is direc tional and is oriented sound 'beam. If the b een o bc ain area.

'd ref 1 ec tor was a rougn and faceted crack, uxcrasonic onic indications from the other examination beams whz.cn alsoo in If the rezlecror were more globular, or rounded, d d resp would have .

interro g ated this res onses co these other examinat"'on angles would also have been nooted. e Based on experience

'n vessel fabricator shops, this type oz th'n 'n p lanar sla g has been notea ermore, a review of the zabricacion raaiograpns other occasions. P urtthermore

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1 of this.'weld show the presence of entrapped planar slag. ais vas confi=ea by several 'Level III reviewers of the radiograDhs.

Therezore, it was concluded that the rezlector is thin, smooth, and in a plane perpendicular to the 15'eam. The wr-'tex nas vitnessed the ezcava-tion of a similar indication in a fabrication shop. The shop-ezcavated indication vas not detectea vith the 0', 45'nd 60'ltrasonic ezaminat'ons bur. vas repaired due to a clear raaiographic indication. Zzcavation revealed a 1/32-inch thick, smooth slag inclusion measuring 1-inch throughvall by 3 inches long near midwall at, the fusion line of a nozzle-to-vessel weld.

Due to the similarity of the nondestructive ezamination responses, it is believed that the indication in the Ginna reactor pressure vessel weld N2APis a thin, smooth slag inclusion in a plane(RPV)'ozzle-to-vessel perpendicular to the beam oz the 15'ozzle bore ezamination.

Heat affected zone (HAZ) cracks vere detected in three nozzle-to-shell velds in the 1972 preservice of the Harch Unit 1 RpV. These cracks vere detected with 45'na 60'zaminations from the outside suriace oz the vessel and subsequently ezcavated and repaired. These cracks vere con-firmed with 0', 45'nd 60'zaminarions from rhe inside surzace or the vessel, 10'zamination from the nozzle bore and by metallographic elm'n-arion during ezcavation. Neither record radiographs nor raaiograpns taken on site revealed the PQ c acks. The multifaceted nature of such cracks breaks up the rez'cr."on so that several small indications oz multiple planes are observed. Sizing such rezlectors to the 50% DAC limits oz the indicat"'on works well without beam spread correction of '"dicat'on dimen-sions. Indications having unknovn orie tat-'on and ident'ty should be si"ea to the 50% DAC limits wirhout beam spread correct'on. Howeve , based on Southwest Research inst-'tute's (SwRI) ezper'ence with flav inaicat'on sizing, beam spread correction should be used on some flaw indications.

in Appendi, 'z Undex'ost conait=ons, P essuxe Vesse'ode.

a reflector can be sized by using the rules contained rhe 1974 idition oz Sect=on Zi oz the ASl~ Boile ana In this case, these rules are not approor'ate.

Appena'z 1 sizing rules are basea on us-'ng 45 and/or 60'ng'e oeam (or other angle beams separated by ar least 15') ezamination techniques. Such ezaminat"'ons were applied to the vessel inside surface but did not detect the subject re lecror and the weld in e Sect passed the Code- equ'"ed UT ezaminations. .ven rhough it'as not a Code requirement, an angle beam longiruainal wave was aopl'ea to the bore oz the nozzle and directed perpendicular to rhe azis oz the weld. This additional ezamination vas per ormed in the interest, of mazimizing the ex=ectiveness oz the weld intexrogation. Direct"'ng a beam perpenaicular to the major reflec""'ng plane oz a weld-related defect results in a hign degree oz reflec .'vity from an imperzec ion. This technique, wnich is more sensitive to planar reflectors at the weld intexzace than the typical techniaue describe bed in n Appenaiz 1, can be aoplied only because oz the unique geometry surrounaing the nozzle-to-shell weld. Because the search unit movement during t. e nozzle bore scan is essentially par'allel to the plane of the Slaw, some of the ezamination paramer.ers which enter into the flaw>>size calculations des" cribed in Appendiz 1 are not available. Since reflection amplituae and parallel search unit movement. are the only parameters available to be used in determining z'aw size, suoplemental considerations must be effected.

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Z3-iO Recognizing that the difxerenca between the measured and the true rexlector size can only be determined by consider'ng tha basic sound beam propeztes, a briez summazv of the physics ox ultrasonic beam propagat-'on wnicn de=ines the beam spread and sound pressure ampl'tude distribution within that oeam are as follows:

The beam spread angle calculated from the equat on, j from the beam axis to the edge oz the total beam is

'total1= arcsin 1.22 X/D 4

!.2g V 4

X = wavelength= V/f v'here V = velocity in the mate ial n milli etars per microsecond f = examination frequency in cycles per microsecond D = dimension of the transducer in millimeters The beam spread angle to the 50% point is calculated using the equation, 50'rcsin 0

. 56 V/fD and to the 20% point 20%

= arcsin .92 V/fD A 2.25 M", 3/4-in. d'a. seazch unit produc ng a stzaignt beam longitudinal wave in steel has a V/fD = 5.89/2.25(.75)25.4 = .1374, tharezora

~ 4 ann ~~~ 7 3 50%

Since these angles are comouted for ha oeam ass to the 50% and the 20%

levels, the 50 co 50% and 20 to 2GZ ang'es double. That 's, halz oz the ene gy is outsice the 8.8'one and 20,. oz the energy is outside the cone.

14.6'n order to obtain beam easuremants on the same basis as the computea beam spread angles, we would need to use var ous si"es oz d.sc re lectors (suc..

as z'at-oortom holes) to rezlec the 50 to 50% portion oz the beam. Side-drilled holes are a batter geometz'c siwlation of suspect re lectors and are more convenient razlectors or ang'a beam calibration s'nce they are eaually re lective to var'ous 'oeam angles and modes oz wave motion. The nonmandatory Code technique foz beam spread measurement uses the 50 to 50%

DAC response from the side-drilled hole. (This is diffezent fzom the 50%

~ of total beam computation and the measured angles are dixferent from the computed angles.) En this case the investigation metal path is greater than 3T/4 metal path, so the responses f om the T/2 and 3T/4 calibration rezlectoz were used for beam spread measurement. Figure 2 shows spread for the 50 to 50% DAC points, while similar plotting gave an 5-1/2'eam ll'eam spread for the 20 to 20% DAC points as measured on side-drilled holes. Such a beam detec ed and 50% DAC sized the Figure 1 indication which gave 117% DAC maximum amplitude from a reflector in nor le-to-shell weld 32. in the Ginna RPV dur'ng the 'Aarch 1979 inservica examination.

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As shown in the top frame oz Figure 1, the indication was recorded on a circumrerential scan of the nozzle-to-vessel wild zrom the nozzle bore with the 15'ngle beam longitudinal wave at 7.64-inch metal path in razerence position 19.14 inches and on successive circumxerenciai scans at rarexence positions 19.40, 19.62, and 19.87 inches. These scan increments increase the macai path to a rezlector perpendicular to the 15'eam by the relation-ship:

KP ~ Sin 15'scan increments): that is, EP = Sin 15'.26 in.) = .0673 in.

= Sin 15'.22 in,.) = .0569 in.

= Sin 15'.25 in.) = .0647 in.

Adding these l6s and comparing che computed ilPs for a planar reflector to average maximum amplitude metal paths for each oz the three successive scans g.ves the following:

Range oz Maximum Amplitude Deviat'n Comoutad Comoutaa K've age <i.etal Path No. or Areas from Ave. .Gnus Ave.

7.64 in. 7.64 in. (Base Reading) 0) 7.71 in. 7 73 inr (4) +.01 .02 in.

7.76 in. 7.75 in. (3) 01 +.Ol in.

7.83 in. 7.83 in. (4) +.01 .00 in.

The ~.Ol-inch range oz deviation zrom average calculates to a range oz re"lec"or plane angles o" 15' :3'or tha eleven maximum ampl'tude metal path readings. This substant"'ates our conc'usion that the scrag nc'us on is located at the weld-to-base =ecai inter"aca in a plane perpendicular to the 15'ngle beam long'tudinal wave.

A studv was conducted to demonstrate the appropriateness o= beam spread corrected rez actor siz'ng. Essentially this study consisted or p acing a rlat-bottom hole rarlector in the ca'1'brat"'on block and compaxing the measured size with the known reflector size. in this test, the geometry oz the nozzle azznination area was simulated, the same or s-'milar search unit a d wedges were used, and s- milax records were taken. Other controls exercised in the study to assure aporopriateness oz the compar"'son are as follows:

1. A flat-bottom hole was drilled at an angle so that the search unit-wedge combination used in measurement of-the flaw indication

'roduces a beam perpendiculax to the flat-bottom hole at a metal path within +3.0X of the flaw indication metal path.

2. The flat-bottom hole was located in a calibrat'on block so it does not intexfere with subsequent calibrations.

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3. The selected calibration block nad ultrasonic coupling conditions similar to the ezamination and had the same diameter side-drilled holes as used in calibration for the ezamination.

4. Calibration vas performed on the block for comparing the flat-bottomed hole response to the maximum response of the flaw indica-tion.

5. The flat-bottom hole amplitude zesponse did not deviate from the flaw indication response by more than 2 dB.

6. 50% to 50X DAC measurements vera made on the flat-bottom hola in the through-vali and length directions as the search unit vas moved toward and across the ra"lector.

7. The 50Z to 50% DAC through-vail dimension of the flat-bottom hole minus the flat-bottom hole diameter was demonstrated to be the througn-vail spread correction.

S. The 5 0% to 50X DAC length di=ension of the flat-bottom hole m'nus the fiat-bottom hole diamete was demonstrated to be the length beam spread correct.'on.

9. The flaw indicat"'on througn-wall dimension 2a minus tha thzough-vail beam spread correct"'on was shown to be the beam corrected flaw ind'cat'on dimension 2ac.

10. The i flav ndicat"'on length d.'=ension minus the length beam spread correct'on vas shown to be the beam spread corrected f'aw dicat"on Ec.

The beam spread cor acted flaw indicat'on dimensions ac and Zc as showa in .""igure 3 vere used 'n computing a/2, rat'o and the a;;I oz t of the indication for compar'son with the ailovabia indication limits apolicabie to the indication location.

In this instance, it vas possible to s'mulata the examination condition a d vessel component geometrr and demonstrate tha ef=ects oz ultrasonic bean spreaa on data~ning the size oz a rezlactor. This paz =cular reflector vas weil suited =or this ezercise bac usa its ox'entat on vas established with an unusuailv hign level oz conzide ce by interzogating 't 'n more ways than is usually possible. All oz the information accu=u atad raiat"'.'a to this rezlector gives a high level of conzidenca that its trna size, or'entation t and character are as reported and that the pract"'ca oz basing its size on the projected 50X DAC l~ts corrected for beam spread s appropriate.

Also, Paragraph DiA-2240 allows. for alternate techniques to be used in lieu of the Code spec.'fie'd techniques ifit can be demonstrated to the sat'sfaction of the inspection specialist that the alternate techniques provide results wnich aza equal or super'or to the Code specified techniques. This was done and the alternate sizing techniques used aza the afore in compliance with the requirements oz Se tion ZI oi the ASM'ode.

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ATTACHMENT 2 FRACTURE MECHANICS EVALUATION OF INLET NOZZLE INSERVICE INSPECTION INDICATION

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