ML20099B939
| ML20099B939 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 11/30/1991 |
| From: | Caine T, Mehta H, Ranganath S GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20099B934 | List: |
| References | |
| DRF-137-0010, DRF-137-10, GE-NE-523-112-1, GE-NE-523-112-1191, NUDOCS 9208030165 | |
| Download: ML20099B939 (30) | |
Text
{{#Wiki_filter:.. _. _. _ _ _. _ _. _ _ _ _ _ _ _ _. _. _ _ _ _. _. _ _ _ _.. _. _ _ _. _. _. _.. ~. _ _.. _ _. _. _.. _.. _ _ _ _ _. _ _ _.. _ l 1 ENCLOSURE 1 GRUNSWICK STEAM ELECTRIC PLANT, UNIT 2 NRC DOCKET NO 50 324 OPERATING LICENSE NO. DPR-62 NUREG 0619 CEEDWATER NOZZLE AND SPARGER EXAM: NATION RESULTS FEEDWATER SPARGER CIRCUMFERENTIAL CRACKING EVALUATION FOR BRUNSWICK UNITS 1 AND 2 General Einctric Report GE NE 5231121191 November 1991 (Corrected Copy! i i I l l 1 l '20803016S 920727 F )R ADOCK 05000324 P PDR
~ _ I T 4 GE NE 523 ll2-1191 DRE 137 0010 Novertber 1991 i l FEEDWATER SPARGER i CIRCUMFERENTIAL CRACKING e EVALUATION FOR l BRUNSWICK UNITS 1 AND 2 1 i a i n
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Prepared by: TA Caine, Senior Engineer Materials Monitoring & Structural Analysis Services Verified by: Nw HS Mehta, Principal Engineer Materials Monitoring & Structural Analysis Services 9O 2 Y" Reviewed by: S Ran5anath/ Manager Materials Monitoring & Structural Analysis Services ._ GE NUCLEAR ENERGY j
i \\ i' ) i IMPORTANT NOTICE REGARDING ) CONTENTS OF THIS REPOP1T i 4 Please Read Carefully d I i (CE) respecting only undertaking of the General Electric Company ~ i I contained in the purchase order between i -The l-are information iri this document his docwrent shall be 4 Carolina Power & Light and CE, and nothing contained in t l The use of this information by order. construed as chancing the purchase or for any-purpose other than that i other than Carolina Power &. Light, is intended under such purchase order is not authorized; anyone CE makes no representation or warranty, and l for which it to any unauthorized use, accuracy, or usefulness of the 4 respect to the completeness, assur..es no liability as or that its use'may not infringe information contained in this document, privately owned rights. I r i e I i 1 e e b T u O V 11' . -.. -.. _. -,.... -.. -. ~
\\ TABLE OF CONTEliTS ZALS 11 1.0 EXECUTIVE SWJmRY 21 2.0 BACKCROUljD 3*1 3.0 FEEDVATER SPARGER AllALYSIS 31 3.1 Critical Flav Size 31 3.2 Crack Crowth Analysis 33 3.3._ Allowable Flaw Size 34 3.4 Looso Parts Considerations 4*1 TEEDWATER N0ZZLE CRACKING IMPACT 4.0 41 4.1 Methods-42 4.2 Assumptions 4-3 4.3 Results. $.1
5.0 CONCLUSION
S _1 5 5.1 Unit 2' Inspections Results 5-1 5.2 Operation Justified 61 (
6.0 REFERENCES
4 APPENDICES. 5-1 FEEDWATER N0ZZLE BLEND-RADIUS AND SPARGER INSPECTION A 181- = = ____J
[ t iIi 1.0 EXECUTIVE O!HMARY i + to addresc requested that analysis be done 1 Carolina Power & Light (CP&L) f the,feedwater sparger aru co-tee circumferential cracking along welds for operation one additional at l identify allowable conditions connections, to maximum allowable f1w involved determination of t.he cycle. The analysis and estimation of maximum nozzle l issues consideration'of loose parts h zzle.
- size, cracking for a hypothetical sparger crack leak directly onto t e no spt3ger inspection [1].
j-1 A preliininary analysis was performed prior to The subsequently performed-(2]. inspections for Unit 2 were l The sparger evaluation and inspectiors are summarized below: I results of the weld cracking is The critical flaw size for_the circumferential tee 4 14.1 inches on the outside surface. d ) due to cycle could be as large as 3.16 inches, The crack growth in one so the allowabla flaw size for the inspee. tion is 10.9 inches.
- IGSCC, veld would not the tee Complete separation of the sparger arm at I
i ld be 'overstress the vessel bracker connection, and such a separat on wou e concern for this I so therer is no loose parts detected by the operator, particular cracking in the spargers. d. Analysis of the hypothetical case of sparger leakage on the nozzle a crack would grow r.o deeper than 0 85 -inches due radius indicates that l Including _ system fatigue crack growth to the leakage thermal cyclit,g. for ua cycle of 0.05_ inches, a crack no deeper than 0.9 inches co developed in one cycle.of operation. 4 cireurnferential crack to be The Unit 2Iinspection-showed the longest Comparison of inspection results from this outage about 2 inches long. and-the~ previous outage for_one of the -' c ra cks indicates that no crack growth occurred during the lasr cycle. significant 1-1 -,we,-+- ,q-,17 rwr--,,,v,, y- ,n r.,,,--,rmre., e ry, m ,,v.,w m,,-ev--,vrw..,-, war-, w + v wns- .,4 -.+ wa r-e-e.e m e.-x, em e,.w r o w +-r. w w e -- es w- --w--w:&
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2.0 BACKGROUND
4 The feedwater (FW) spargers in Units 1 and 2 at the Brunswick plants i 4 in the side of the sparger arra pipes, have the originally designed flow holes 4 cracking after a few cycles of j dettonstrated rapid thermal cycle j and in compliance with NUREC 0619, CP6L has regularly w?ich have i operation. As a result, inspections of the flow holes, and has found and t'e s t (PT) perfort:cd penetrant process of perforrning PT inspections I monitored flow' hole cracking. In the indications were also found along the circurnferential l during the last outage, to the tee. While these indications were velds shich connect the sparger arms 4 l show circumferential indications at } not measufa1 for length, some pictures least 2 inches long on the visible side of the sparger (see Figure 2 1). f structural integrity of the CP6L requested an evaluation of the Therefore, l spargers for the next cycle of operation. The evaluation specifically l between the sparger circumferential cracking along the velds addresses the 4 j art:s and tee, and applies to both Units. i The evaluation consists of several aspects, as described below: i The critical flaw size for failure of the sparger is determined, e Maximum 4..pected crack growth is predicted, based on consideration d e and fatigue. j intergranular stress corrosion cracking (IGSCC) failure of a sparger tee veld resulting in The likelihqod of complete ) loose parts is addressed. For the worst case scenario where feedwater leaks _through the feedwater circumferential crack directly onto the blend radius of the the maximum possible nozzle crack depth is predicted. no::le, Inspection results for Unit 2 are presented and conclusions concerning ) continued operation are made. 2-1
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l 1 3,0 FEEDWATER SPARCER ANALYSIS The analysis process used to determine allowable flaw size for one cycle The critical crack size, the crack size at which of operation is as follows. sparger failure can realistically be expected, is calculated, along with the These K values are used with crack X. associated stress int'ensity factors, corrosion cracking (SCC) to for fatigue and stress growth,. correlations Subtracting determine the amount of crack growth possible during one cycle. Srowth from the critical crack size,gives the allovable crack size the crack The details of each step in this that can be detected during the outage. process are described below. 3.1 CRITICAL FLAV SIZE ~~ determined using methods similar to those The critical flaw size was " Evaluation of presented in ASME Cods Section XI Non Handatory Appendix C, section collapse approach Flaws in Austenitic Piping." The methods use a net is evaluated for failure due to where the remaining sectio 5 of a cracked pipe the primary membrane and bending,oads. For the TW spargers, primary loads l w s we're 'coniidered due to' spai ger va'ight, 've rt'i' cal ' and 'horizonsal 's'eismic-loads, loading of impinging downcomer flow and hydraulic loads due to flow turning in a-- ,Lbe tee. The following assumptions were made -in determining critical flaw' size: from the flow holes were conservatively Counteracting hydraulic forces 1 e i ected. e port from the thermal sleeve connection to the safe end, either velded or slip fit, was conservatively assumed to be zero. The sparger was conservatively modeled as a straight beam equal to the curved length, with pinned pinned end conditions. The veld toughness correction factor Z1 - 1.449 for shielded metal arc or submerged arc welds, which amplifies the bendin5 stress, was included in the net section collapse analysis. 3-1 f e
s-in the sparger is the stress The only loading resulting in mersbrane The bending stress loads calculated differential pressure of about 15 psig. The vertical feedvater sparger were both vertical and horizontal. for the 225 lbs. and loads were the weight, 500 lbs., the downcomer flow impingement, The horizontal loads vsre the sparger flow the vertical seismic load, 80 lbs. 600 lbs. All loads 535 lbs, and the horizontal seistsic load. turning load, the flow turning load, which was treated as a as distribu'ted loads except <act The sparger v3s treated as a pinned pinned beam, with no center point load, The resulting vertical and horizontal bending stresses were combined support. The results show primary membrane stress of 0.06 by SRSS to get the maximum. ksi an6 primary bending stress of 2.58 ksi. described in Non liandatory Appendix C The net section collapse method, in ASME Code Section XI, is baiTd on plastic yielding occurring in the remaining ligament of uncracked pipe. Fic,ure 3 1 shows schematically the in the equation below: Seometric quantities a, S, d and t e (3-1) A - [(x ad/c) xPm/of)/2 Pb' 2af/w (2 sin 4 d)t sin a) (b2) ~ through-wall crack.d7t - 1. The flow f For the sparger case, a s suarin g. a e, intensity,'S:n '16,9 stress, eg, is three tiines the allowable membrane ~ stress 4 ksi' f or' 304 st'ainiess 's'toel'. Pm is-t$e membrane' stress. 'Pbis'the' bending for lover toughness of shielded stress Pb, modified by a factor 21 to account matal arc snd submerged are velda as follows: (3 3) Pm Pb' - Z1 (Pm + Pb) where Z1 - 1.449 solved on a repeated trial basis for the crack Equacians 3-1 and 3 2 vere The results show that the critical crack size is a through vall half-angle a. On the Fli sparger, with an crack arouna 244' of the sparger circumference. this means a crack len5th on the outside outside diameter of 6.625 inches, surface >f 14.1 inches. 3~2- - - -___ __ _ _ _]
_- _.. _ _.. _ _ _ _ _ _ _ _ __.. _ __. _._-- _. _ _ =._._. _ _ __ _ _ _ _ _ _ \\ 10 i i i 3.2 CRACK CROWTH ANALYSIS 4 the circumferential veld As shown in Figure 21, it is likely that l thermal cycling cracks. Although the s cracking is initiated from flow hole is due to thermal fatigue, the inir!al crack growth in the early stages j driving force decreases with crack length, and the crack growth is likely Thus, cracks as long as shown in Figure 21 are not l be lese than 0.5 inches. For the W spargers, expected to be due to the flow hole cycling phenomenon. likely cause of subsequent l which are as welded 304 stainless steel, the most i the crack tip caused by flow hole ICSCC, starting at I crack extension isThe approach to determinin5 an allowable flaw is to subtract cycling fatigue. which in this case results in a crack growth from the critical flaw size, J Sinee the cracks are assumed to have grown rather large allowable flav size. is appropriate i a considerable distance from the flow hole initiation sites, it j. to consider only ICSCC growth. For ICSCC growth, both the sustained primary and secondary stresses are 4 important. The secondary stresses include thermal bending due to the through the sparger vall and veld residual stre s. temperature difference the Based on the thermal stress relationship a - Fo6T/(1 v), with 6T - 130'F, tensile on the inside surface. is 22 ksi, thermal bending secondary stress The weld residual stress is expected to be near the yield strength of about i 30 kai, also tensile on the inside surface. There fore, stresses are assumed h. to te equal to the yield strength for the analysis of ICSCC growt intensity factor, K, is for a stress The model used to calculate 4 through the longitudinal crack in a cylindrical shell subjected to bending ab The K computed for the surface of the thickness (3), as shown in Figure 3-2. pipe vall where bending and membrane effects add is given by (3 4) K - (Gm + Cb) ab/na (1+v)/(3+v) 1, from [3]. wh re Cm and Cb are me@rane and bending factors, between 0 and Use of this expression a c'pected to be cons ervative for this application, and cylindrical shell models used to based on comparison of trat plate The resulting relationship of K versus evaluate circumferential vessel flaws. crack length 2a is shown in Figure 3-3. 3-3 y-1
m - -- - ---------- --_-__ _ 1 The ICSCC growth rate relationship used is that provided.. rigure 2 of Appendix A of m' REC 0313: K.161 inches / hour, 2 da/dt - 3.59x10*B c computing K Crack growth is calcuiated by assuming an initial crack length, a, and da/dt, determining crack growth oa for a given time interval, and then "~" For the crack lengths repeating the process for a new crack length of a+Aa. f ai~rly c.onstant betveen 40 and 45 ksi fin, so of interest, the K values are time intervals of 50 hours were used. The total time evaluated is 13150 hours, corresponding to 18 months of constant operation. are shown in Figure 3 4. The The results of the ICSCC growth analysis allowable crack which7ould reach the critical flaw size in one cycle largest is 10.9 inches. This initial flaw size experiences 3.16 inches of ICSCC, using the methods above. The calculated crack growth rate is a maximum However, this rate is a function of crack length. 1.3x10*4 inches / hour. m 3.4 LOOSE' PARTS CONSIDERATIONS,, The issue of loose parts is a consideration if, tha.sparger veld fails completely, potentia 11y'Tesulting in two sparger pieEs suspended' from the Analysis' of the bracket pin and sparger connection. vessel bracket pins. _ enough for the cantilever pieces was done to determine if loads were large condition to result in failure of the pin connection. The sparger connection bracket is shown schematically in Figure 3-5. Four locations were evaluated: The one inch bolts connecting the bracket to the sparger, the slotted bracket plates, the welds connecting the slotted and the bracket pins. Only vertical bracket plates to the bolted plates, loads were considered, based on the restraint conditions for the pin and bracket for the assiuned condition of the s, er arm being severed from tha tee. 1
l t The loads applied to the sparger arm cantilever were the weight, impingement flow load and vertical seismic load. The resulting maximum stresses for each location evaluated are below: One inch bolts: 1807 psi Slotted bracket plate: 740 psi Slotted plats welds: 815 psi Bracket pin: 2624 psi Maximum stresses are less than 3 ksi. The fatigue endurance limit is about 13 ksi, so fati6ue failure of the pin connection hardware is very unlikely. complete failure of the sparger veld would disrupt feedwater flow to the that several oper$tional abnormalities sho nd be detectabic.. The flow extent to that sparger would be changed so that total flow would increase, but almost all the flow would go out of the broken sparger opening, with its lower flow resistance. The change in feedwater distribution would cause changes in the recirculation loop temperatures and local variations in subcooling to the core, which would effect the power distribution. Therefore, changes in feedwater flow, the recirculation loop temperature and core power distribution would all provide indications to the operator which would likely result in plant shutdown. The broken sparger condition would not be prolonged during operation to the point that flow induced vibration could cause complete failure. Given the low likelihood of ICSCC causing complete severance of the sparger arm from the tee, and the further lov likelihood of complete severance of the sparger arm resulting in a loose part, there is no need to evaluate Other loose parts due to the circumferential cracking which has occurred. potential loose parts due to flow hole cracking have been ovaluated in other reports. 35
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J 4-. db- ..&..)r 4 m. m-1 VESSEL \\_\\\\\\\\\\\\\\\\ SLOTTED PLATE f i ... j s A __: ~]) ~ l 1 TOP VIEW 1" BOLT SLOTTED PLATE WE! 0 r l 'kJ I ) y l I i i l J i L / l 7 / \\ ^ BRACKET PIN L f FRONT VIEW Figure 3-5. Schematic of Sparger Arm Bracket Connection
-..~.. s-l 4.0 FEEDWATER N0ZZLE CRACKING IMPACT l i In the unlikely event that the sparger veld cracks opened-so that the blend. cadius of a FW noztle, rapid feedwater was flowing directly onto The nature of the j-cycling could cause crack initiation and crack growth. l documented crackin5 phenomena: FU l damage to the no::le is similar to two leaka5'e rapid cycling and flow hole rapid cycling. ) thermal sleeve t Extensive testing and analysis of the thermal sleeve leakage rapid-4 j of designing the triple thermal sleeve. j cycling was conducted in the process a j Among the analyses done was an-evaluation of the expected crack growth in the e blend radius due to rapid cycling (4). The results showed that AK values t associated with the rapid thermal cyclin 6 drop as a crack proceeds into the is j nozzle until the crack arrest aK threshold of 3 ksi-/in (for hi h R-ratios) S l reached. The depth of_the arrestod crack is a function of the frequency of the cycling, as shown in Figure 4-1. Similar analysis was done for the flow hole cyclin 5 phenorenon (5), f f from the flow hole, until I A5ain, the aK values drop as a function-of distance the crack arrest AK threshold is reached. In this case, with low R-ratio, the threshold is 5 ksi-fin. The frequencies and magnitudas of thermal cycles for the case of sparger i leakage onto the no::le are unknown, so any fatigue crack growth calculation would be' based on arbitrary assumptions. Instead, the maximum expected crack i depth is determined based.on the same aK attenuation and AK threshold approach l used for the thermal sleeve leaka5e and flow hole cases. 1 4.1 METHODS The method used to estimate-the crack arrest depth follovs the methods 4 used for the blend radius in (4), benchmarked by the actual cracking -seen in the sparger flow holes. The flow hole cracks have been found -to be as large as 0.5 inches, so the benchmark =of'the aK vs. depth calculation is-that the curve.should pass through 5 ksi- /in at 0.5 inch depth. O
3- .J f shown in Figure 4 2, feedwater notale blend radius was modeled, 4 as The analysis by ANSYS. The model was subjected to cycles of for finite element a 130*F step changes between 550* F and 420*F at varying frequencies, and The ANSYS results were used with the eress computations were performed. and s AK relation. hip from [4]; 1 4' 2 3 (4 1) KI - 1.12 /wa (A0 + Al*2a/x + A2*a /2 + A *4a 73,) 3 Ag threugh A3 are coefficients to the cubic polynomial curve fit of where SYS. stress versus depth in the noccle blend radius, obtained from AN a ) i f 4.2 ASSUMPTIONS l of conservatively The following assumptions were made for the purposes simplifying the problem of leakage flow from the sparger onto the blend radius: from the cracked sparger would have similar thermal cycling i Leakage flow f characteristics to those cf the sparger flow through the flow holes. l the flow holes with a Radial thermal cycling cracks currently shown at f represent the maximum cracktag due to steady state e i length or 0.5 inches flow fluctuations. Further growth of these cracks is due to transient This is conservative, as events such as feedwater flow initiation. these cracks have already seen over ten years of transient events. i Magnitudes of temperature fluctuations at the flow holes are greater dius. than fluctuations expected from leakage onto the blend ra 1 l 4 + a 4-2 i ,m-
..,. ~ _ -. _ -.. - -.... . ~ _ _ _. -. t 2 3' l' l 2 i ' j. 4.3 RESULTS I 1 1/4 and aK profiles were developed for frequencies of 1/8, l Stress range l at.d 1/3 Hz. The 1/4 H: case was found to come closest to meeting the j~ benchmark condition of 5 ksi-/in at 0.3 inches. The stress range profile is was fit with a cubic thown in Figure 4-3. The stress range profile l polynomial, and then the coefficients were adj us te slightly until the The resulting AK vs. depch plot is shown in benchmark conditions were met. to the high mean stress threshold of 3 ksi /in Figure 4-4. The curve extends Therefore, rapid cyclin 5 behavior which causes a a depth of 0.85 inches. crack of 0.5 inches at the flow holes is predicted to cause a crack of 0.85 at i inches in the blend radius. 1 1-to rapid cycling, system J In addition to the possible crack growth'due NUREG-0619 analysis for In the most recent cycling crack growth could occur. the system cycling crack I Unit 2 [6), which has the greater crack growth rate, crack 0.85 inches deep is growch for 18 months of operation with a the maximum expected crack depth for spar 5er leakage 0.05 inches. Therefore, i auto the nozzle is 0.9 inches. While this is'significant, it is less than the flaw depth allowed in NUREG-0619 of 1.0 inch. i 4 s 43 .- _., ~. ~._....__ _._-._,.. _... - - _. -
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a A ~ ~ \\~ \\ 4 ~s\\ ,. ~ i ~ ~ \\~ ~ _ ~~x-\\~\\",y ~ ~ - s~ ~ x- \\_ _x_ ~ ~ ~ ~ \\ ~ ~\\ ~ \\ ~_' l ~ X ~ ~ ~~ s ~ ~ ~ x- \\~ ~ a~ ~ x - x - N ~ ; ~ ~ ~ _ l ~ i ~ ,, \\,, \\ " \\ \\ ~_ ~ ~ g,,/;\\~/'\\,s, s y ~ n k \\ N ,, ;\\ \\ ~ \\a \\ ~ \\ ~ ~ 8,, ' ~ ~ ^4 4 7 .,{ \\ ~ %~ \\ ~ \\ " \\,'s,, x,. s ~,, g}f ~ ~ '~ k ~x~\\" ) /- \\ ~,\\ ~, ~~, ~~.,,, ~ x c- ,.~ /I ~,~',~-j , ' ~, \\~ 311oy steel J 4 = Clad p 1 ( j u \\ / / / / /. 4_ ~ -~ ( ~ k. <c / T1T \\ N s' l / g ,s. s . ~ p ss ssx ss S,,q~,ws:s (' g / +A rigu9e 4-2. ANSY.S Model of Feedwater Nozzle Blend Radius
b t 25 1/4 Hz a CYCLES t 20 - O u)o 15 v L td O E Z g <C m 10 O' Sz* W W LJ O' 5 t-W i S i" --- 'J~ 0 1 1.2 -5 0.4 0.6 0.8 O 0.2 DEPTH INTO BLEND _ RADIUS (inches) Stress Range Profile f or Cyclic l.eakuge on Nozzle Figure 4-3.
~. _ t ~ ~ 11 t 30 9 n lC L,- 8 i u) 7 - x v i i LL1 6 - i O z 5 ksi--Vin Threshold <C 5 - N i fr 4 [ 4 - 4 3 ksi-VTn Threshold _.J 3 - N hl Q 2 't i i i i 0 0.1 0.2 0.3 04 0.5 0.6 0.7 0.8 0.9 1 i 0 DEPTH (inches) i ? Finure 4 -4. Attenuation of A K with Depth into Nozzle
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5.0 CONCLUSION
S Tha results of this report are intended to provide jus tificat'.on for less than the operation for one additional cycle given circumfer.ntial cracks maximums allowed in this report. The inspections were done for Unit 2 in j 4 discussed below. Conclusions can be drawn for Unit 2, based on 0:tober, as those inspection results. If the inspection results for Unit 1 are similar to those for Unit ,2, the same conclusions app ly. j 5.1 UNIT 2 INSPECTION RESULTS i The Unit 2 feedwater no :ler and spargers were inspected accordin6 to the requirements of NUREG 0619. The documer - ed results are included in was liquid penetrant Appendix A. Tha blend radius of aach feedwater no::le (LP) tested, showing no indications. 8 The circumfertntial welds were LP tested and ultrasonically tested (UT). The LP tests show the longest crack to be 2 inches. The UT results show that than the LP indications on the crack lengths inside the spargers are no more last the outside surfaces. Comparison of a crack length mearured during the outage and during this outage shows that no significant crack growth has occurred. 5.2 OPERATION JUSTlFIED The analysis in Section 3 provides an allowable through-wall crack i The length of 10.9 inches, bared on 3.16 inches of ICSCC growth in one cycle. inspection results for Unit 2 show much shorter cracks, about 2 inches, and little if any 1CSCC growth. Therefore, operation for the next cycle is justified. Once crack lengths and IGSCC growth rates are shown to be acceptable by inspectio-of the Unit 1 spargers, operation for one additional cycle will be justifieo. 5-1
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6.0 REFERENCES
i [1] Letter No. ADK-91 079, dated October 4, 1991, AD Ketcham of GE to LA Bishop of CP&L, "Feedwater Sparger Circumferential Cracking Evaluation." 'I l [2] Letter, dated October 20, 1991, JE Ca :es of CP&L to AD Ketcham cf CE, "Unic 2 Feedwater Nozzle Blend Redius and Sparger Inspection." [3] Cartwright, D.J. and Rooke, D.P., Compendium of Stress Intensity Lac tors, Her Maj esty's Stationery Office, publisher, L o ndo n,- 1976, pages 320 322. f [4] Fiie et al, "Boilin5 Water Reactor Feedwater Nozzle /Sparger Interim l Program Report," CE Report NEDC-21480, July 1977. (5] kiccardella, P.C. and Sharma, S.R., "Feedwater Sparger Hole Thermal Stress Analysis," CE Report RSA-76-04, March 1976. [6]
- Stevens, C.L., "Erunswick Unic 2 Ft.edvater Nozzle Fracture Mechanics Analysis," CE Report NEDC 30633, Revision 1, May 1991 (proprietary).
i I s t 6-1
l 6 8 l -APPENDIX A FEEDLTER N0ZZLE BL'ZND RADIUS AND SPARCER INSPECTION 0 4 k h A1
s' # Cp&L Carolina Powu & Light Company October 20, 1991 To: A. D. Ketcham GE Site Services Manager FROM: J. E. Gates NED Responsible Engineer SUBCECT: Unit 2 Feedwater Nozzle Blend Radius and Sparger Inspection On October 12, 1991 CP&L inspected the Unit 2 feedwater nozzle inner blend radius in accordance with Nureg 0619 and als.o performed an LP examination of the feedwater spargers to document the flow hele cracking and circumferential weld cracking. The results of the inspection are as rollows: 1. No relevant indications were found on the nozzle inner blend radius. 2. Crack growth continues on the flow holes but no pieces have separated. Note: The pieces did not separate during the hydrolase cleaning operation using a 20,000 psi plus 4 hydrolaser unit prior to the examination. In addition to the horizontal piece between the flow holes which has been previously addressed by GE, the size of other potential loose pieces is as shown. The largest of which har also been previously addressed by GE. flow Hole (f}pt:3?] CorC Wald Ice *0 HC?):Ontal Wela Seam , Sca,y. ;,,;; in o et ((((u(((((U q% t sxw c ,'p \\U A= I] 10 38 c tentiaticcse part o / 2= uc to.5 Dark unes in <cate./ C= 13 to.38 LP inct:alions ^ POTEvTIAL FEEDWA TER SPARGER LOOSE :1RT
1' 0 4 Page 2 of 2 3. The eight circutaferential welds connecting the sparger tee to the arms and the four welds connecting the thermal sleeve
- o the tee were LP examined.
No relevant indications were found on the thermal sleeve attachment welds. Indications were found on the tee to arm circumferential welds. Some of these ran into the welds and some were circumferentially oriented following the heat affected zone. The longest s circumferentially oriented. indication f ound by LP examination was 2 inches long. Following the LP examination, five of the eight welds were UT examined for the full circumference to determine the ID length of the OD indications. No indications were found to extend beyond the OD indications. By the direction of the cracks they all seem to have originated from the flow hole cracks and are now following the heat affected zone of the a ld. They are all growing downward towards the lower half of the sparger arm. No evidence of any other cracking was found in the joint. The longest crack on the right side of the 135' tee did not shew significant growth from the last LP examination. Please prepare the final report for the feedwater spargers incorporating this information into the report. A copy of the inspection documentation is attached (except for the photographs of the LP indications). If you need additional information please contact me at extension 3669. Sincerely, nsB &J', V-James E. Gates, Jr NED Engineering JEG/jeg CC" S. L. Bertz E. A. Bishop J. W. Crider P. S. Gore -{
c' q ) BRUNSWICK STEAM ELECTRIC PLANT UNIT 2 NINETH REFUELING OUTAG2 - OCTOBER, 1991 INVESSEL VISUAL INSPECTION (IVVI) INSPECTION REPORT AND VIDEO REVIEW NUREG. 0619 INSPECTION THIS REPORT SUMMARIZES THE INVESSEL VISUAL INSPECTION AND THE VIDEO TAPE REVIEW THAT WAS PERFORMED DURING THE NINETH REFUELING OUTAGE AT BRUNSWICK UNIT 2. THE' INSPECTIONS WERE PERFORMED BY GENERAL ELECTRIC I COMPANY PERSCIAEL. THE FOLLOWING IDENTIFIES THE WORKSCOPE THAT WAS PERFORMED AND THE VIDEO TAPE REVIEW: 1.' FEEDWATER SPARGEn THE FEEDWATER SPARGERS WERE VISCALLY INSPECTED FLOW HOLES (VT-3) PRIOR TO THE LIQUTD PENETRANT EXAMINATIOb FOR GROSS CRACKING. THE VISUAL EXIs! RESULTED IN NO ADDITIONAL HOLES TO LP EXAMINE. A TOTAL g J OF 55 OF 144 HOLES WERE INSPECTED BY THE LIQUID PENETRANT METHOD. THE FLOW HOLES HAVE LINEAR INDICATIONS WITH GROWTH CONTINUOUS. SEE PHOTOS FOLLOWING THIS REPORT. ' 2. FEEDFATER NOZZLE AN. LP EXAMINATION WAS ALSO PERFORMED ON THE INNER RADlUS NOZZLE INNER RADIUS'S @ 45,135,225, AND 315 DEGREES RESULTING IN NO RECORDABLE INDICATIONS.
- 3. FEEDWATER SPARGER THE 12 FEEDWATER TEE BOX CIRCUMFERENTIAL WELDS TEE BO( WELDS WERE FIRST LP EXAMINED TO DETERMINE CRACKING EXTENDING FMOM THE FLOW HOLES AND TO DETERMINE THE OD LENGTHS.
AFTER A RE~iTIEW OF THE VIDEO, FIVE OF T:iE EIGHT TEE TO SPARGER ARM CIRC WELDS WERE DETERMINED TO HAVE' LINEAR CRACKING. THOSE FIVE CIRC WELDS WERE THEN ULTRASONICALLY INSPECTED TO DETERMINE ID LENGTHS. DUE TO THE CONFIGURAT. ION OF TIIE FLOW HOLES IN RELATION TO THE CRACKING, ONLY TWO OF THE CIRC WELD CRACKS COULD BE ULTRASONICALLY " SIZED" ON THE ID. SEE THE FOLLOWING UT DATA. nce n ^ I '}}