ML20072P988
| ML20072P988 | |
| Person / Time | |
|---|---|
| Site: | River Bend  |
| Issue date: | 11/15/1990 |
| From: | Ranganath S GENERAL ELECTRIC CO. |
| To: | |
| Shared Package | |
| ML20072P934 | List: |
| References | |
| SASR-90-98-DRFT, NUDOCS 9011300019 | |
| Download: ML20072P988 (28) | |
Text
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5-Enclosure 1 SASR 90 98 DRF 137 0010 REASSESSMENT OF THE INDICATION IN THE RIVERBEND FEEDWATERN0ZZLE(N4A)TOSAFEENDWELO 1
l NOVEMBER 15, 1990 l
l 1
Prepared by: -
/7 ^
S. Ranganath, Manager Materials Manitoring &
Structural Analysis Services 1
Verified by:
M.'L. Herrera, Senior Engineer Materials Monitoring &
Structural Analysis Services Approved by: J >>& . (v G M G 4 G.M. Gordon, Manager' T
-Fuel & Plant Materials Technology 4
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SASR 90 98 l
IMPORTANT NOTICE REGARDING CONTENTS OF THIS REPORT PLEASE READ CAREFULLY l This report was prepared by General Electric solely for the use of Gulf States Utilities. The information contained in this report is believed by General Electric to be an accurate and true represeitation of the facts known, obtained or provided to General Electric at the time this report was prepared.
The only undertakings of the General Electric Company respecting information in this document are contained in the contract between the customer and General Electric Company, as identified in the-purchase order for this report and nothing contained in this document shall be construed as changing the contract. The use of this information by anyone other'than the customer or
- for any purpose' other than that for which it is intended, is not authorized; and with respect to any unauthorized use General Electric Company makas no representation or warranty, and assumes no liability as to the completeness, accuracy, or usefulness of the information contained in this document.
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e SASR 90 98 REASSE5$ MENT OF THE INDICATION IN THE RIVER 8END FEE 0WATERN0ZZLE(N4A)TOSAFEENDWELO BACKGROUND ,
As part of the ultrasonic inspection of A110y 18Z weldments in River Bend, an indication approximately 6 inches long and peak depth of 0.20 inches was discovered in March 1989 in the A11oy 182 weld butter of the feedwater nozzle (N4A) to safe end weld. Figure 1 shows the nogale weld configuration and the location of the indication. While there was some question on whether the indication was an IGSCC crack, still, a crack growth evaluation was performed assuming that the observed indication was due to an active IG$CC crack. The predicted crack size at the end of the next fuel cycle (RF 3) was determined assuming a bounding crack growth rate and compared with the ASNE code allowable flaw size. The analysis confirmed that continued plant operation could be justified and that the required code margins were saintained. In addition to the analysis, a mid cycle examination of the indication was also planned.
Based on the results of the analysis and the plans for a ald cycle ultrasonic inspection, the NRC allowed plant startup without repair.
In March 1990 ultrasonic (mid cycle) examinations were performed on the weld in order to detect any changes in the dimensions of a planar type reflector. detected during RF 2. The results of these examinations showed no detectable growth.from initial detection and sizing to.the mid cycle Outage.
At the end of fuel cycle RF 3 (November,1990) the wald was again examined to determine changes in the crack size Ultrasonic examinations were performed using both manual and automatic techniques. The examinations performed during the end of RF 3 showed significant changes in the signal characterist:cs compared to those seen during the previous examinations. A breakdown of the manual and automated results for the initial, midcycle and the latest inspections are shown in Table 1.
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$ASR 90 98 Based on' the-results of the RF 3 examinations, the reflector is presently 7.7' long exhibiting an increase in length of 1.6" from March 1989 to November 1990. The depth has increased from 0.20' (les TWD) to 0.33' (305 TWD) in the !
deepest areas. These results were confirmed using several different transducers along with the P Scan Automated System to obtain accurate, finite thru wall dimensions. The final depth recorded by the P Scan was 30% at the deepest location with an average depth of 155 to 20% over the remainder of the reflector. Figure 2 shows a depth profile of the indication in 1989 and in November 1990.
Crack Growth Assessment Comparison of the results of the midcycle UT with those of the March 89 inspection shows little change suggesting that the crack may have been a fabrication flaw which has not manifested itself as an intergranular stress corrosion crack. However, from the midcycle UT to the November 1990 inspection there was. a significant change in peak depth (18% to approximately 30%). The reason for the apparent change in crack growth behavior is not clear. In particular, no unusual water chemistry conditions (:hich would accelerate SCC)
L are evident. Figure 3 shows a plot of'the water conductivity as a function of time for the last six months covering the period from the midcycle inspection to the November 1990-inspection. Except for a short spike where the conductivity increased to 0.9 p$/ce,-the overall water chemistry conditions are well within the BWR industry guidelines (Reference 1). Nevertheless, the t
average crack growth' rate can be estimated during the period between the old
~
cycle examination and the November 1990 results. For the observed change in t'
depth (0.33 - 0.20 = 0.13 in.) in slightly over 6 months of hot operation (approx.4500 hrs)theestimatedcrackgrowthratebasedontheUTdatais 2.89 x 10 5 in/hr. This is somewhat higher than the values expected for the range of water conductivities experienced at Riverbend and may be in part, due to the inherent error band in the UT sizing.
Figure 4 shows GE data on SCC growth rate in Alloy 182 as a function of the
- applied stress intensity factor. It is seen that the crack growth rate tppears to reach a plateau beyond a K value of approximately 20 ksi/in.
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.- l SASR 90 98 The GE data show a range of 2x10 5 to 5x10 5 in/hr for higher conductivitie Figure 5 shows crack growth rate as a function of conductivity, it is seen that the crack growth rate is significantly lower for lower conductivities.
Measured Crack Advance / Arrest Verification System (CAVS) data from sever plants with normal water chemistry (Table 2) show growth r'ates in the ran 2x10 5 in/hr.
Thus the growth rate based on the UT sizing is somewhat on the high side considering the conductivity during the past cycle. For the purpose of the fracture mechanics assessment, a crack growth rate of 3x10 5 be used. in/hr will I data. This bounds the estimates based on the UT data as well as Fie!
Fracture Mechanics Analysis The stress analysis and fracture mechanics evaluation of the weld I indication (as of March 1989) was documented in Reference 2.
The analysis considered the weld residual stress as well as the steady state thermal and !
pressure stresses.
The allowable crack size parameters were determined usir.g the ASME Code Section XI, IW8 3640 criteria.
This report updates the fracture assessment based on the current flaw sizing and using the estimated crack growth rates based on the UT depth measurements.
Figure 6 shows the allowable flaw size parameters that assure a structural margin of 3 as required in Section XI, IW8 3640, ASME Code. The analysis is based on the limit load approach used to determine allowable flaw sizes. The d
combination of nondimensional ' epth (depth / thickness) and nondimensional le (length / circumference) are shown for two cases - (1) corresponding to limit load, (ii) a margin of three over liett load conditions. The flaw parameters corresponding to a factor of three on limit load define the allowable values.
It is seen that the required ASME Code margins can be maintained even for a through wall crack of approximately 30% of circumference. Since a through wall crack would be unacceptable, the allowable depth is arbitrarily fixed at 75% of wall thickness when the prediction for a structural margin of three shnws allowable depths exceeding 75L The March 1989 crack size and the crack site based on the November 1990 UT are shown in Figure 6. It is seen that the
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SASR 90 98 '
overall crack growth over the past cycle is well below the predictions in Reference t based on the bounding crack growth rates. The predicted crack
[ growth for the next fuel cycle (RF 4) is also shown in the figure. The crack growth predictions are based on the Value of 3x10 5 in/hr (which bounds the growth rate estimated from the UT sizing). The change in length at each end of i the crack can be estimated from the increment in crack depth. However this
- culd underestimate the length since it would not account for new crack initiatin sites. A more realistic basis is to assume that the change in length during the next cycle is the same as the increment observed during RF 3 (1.6in).
Based on these assumptions the predicted end of cycle (12,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />)
L crack depth is 0.33 + 12,000 x 3 x 10 5 0.69 in, and the crack length is 7.7
[ + 1.6 9.3 in. The predicted crack size is within the ASME Code allowable value and is acceptable for continued operation for the next fuel cycle.Gulf l'
. States ytt11 ties (GSU) plans a midcycle examination during the next cycle.
This will provide additional assurance of safety cargin.
L DISCU$S10H The analysis described here shows that ASME code margins are maintained and that continued operation can be justified for the next fuel cycle, it is useful to summarize the conservative assumptions used in the evaluation.
1.
The analysis conservatively assumes a growing, active IGSCC crack. The UT <
evidence on whether the crack is due to SCC is mixed since the comparison ,
with the RF-3 sid-cycle showed no growth while the current UT shows a change in depth.
L 2.
Gulf States Utilities (GSU) plans a mid cycle examination after approximately 7000 hours0.081 days <br />1.944 hours <br />0.0116 weeks <br />0.00266 months <br /> of operation. This will provide additional assurance of knowing the actual crack depth during the midcycle outage. If the measured crack depth is not bounded by the ansij;is, sorrective action can be taken at this time. However, the analysis does not consider the midcycle outage ar.d assumes 12,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> for crack growth.
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The crack growth rate used in the analysis is based on the differen between the midcycle VT and the November 1990 UT and appear estimate considering the low water conductivity maintained at Riverb CAV data from operating BWR's show lower growth rates than that a here.
If Riverbend continues to maintain water conductivity levels comparable to the recent measurements, the actual growth rate could b substantially lower.
4.
The predicted end of cycle depth is less than the ASME Code allowabl values which assure a structural margin of three.
Thus adequate margins are maintained throughout the next fuel cycle.
REFERENCES 1.
- BWR Normal Water Chemistry Guidelines:
1986 Version' EPRI Report NP 4946 SR September 1988.
2.
" Evaluation of the indication in the Riverbend Feedwater N Weld" GE Report SASR 89 37, DRF 137-0010, General Electric Compan 7,
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r Pages 12 and 13 are Gerv.rt.1 Electric Co. Firprietary Infonction.
These pages were prov'.ded in CSU Ictter to the iiRC dated May 15, 1989 (RBG-30833) . .
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2 RIVERBBC FEEDWATER NOZZLE
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. Enclosure 2 v
E8ASCO SERVICES INCORPORATED EM 210 Clay Avenue. Lyndhurst, NJ 070713507. (201) 896 5000 November 12, 1990 in reply refer to 90GSUOO35 Mr. Roger Carlyle i
Gulf States Utilities Alverbond Station U.S. 61, 2 Miles South of St. Francisville. LA 70775 SUBJECT Ultrasonlo Examination of N4A Nozzle-to-Safe End Wold (N4A-2)
Dear Mr. Carlyle On March 20. 1990 ultrasonic examinations were performed on the subject wold in order to detect any changes in the dimensions of a planar type y reflector detected during RF-2. The results of these examinations showed (i
' no detectable growth from initial detection and sizing to the Mid-Cycle Outage within the accuracy tolerances approved by EPRl's NOE Center
.(Reference MCY3 N4A Feodwater Nozzle Report). On November. 10, 1990 the subject weld was again examined for the same reasons and the results are as follows.
All of the examinations performed by EBASCO to date were performed utilizing Manual Ultrasonic techniques in socordance with EBASCO Procedures GS-UT-W81-4 Revs. 3 and 4 and GS-UT-W81-7 Rev. 2. In addition to the Manual Procedures. E8ASCO's Automated Procedures GS-UT-W81-P2 Rev.
- 0, Add. I and GS-UT-WD1-P3 Rev. O were utIIIzod.
Ultrasonlo examinations performed during RF-3 showed significant changes in the signal characteristics compared to those seen during the previous examinations. A breakdown of the manual and automated results and a list of the ultrasonlo equipment utilized are shown on Attachment * & 11.
Based on the results of the RF-3 examinations, the reflector le presently
' 7.7" long' exhlbitIng an increase. In length of 1.6" free March 1G39 to November 1990. .The tnru-wall dimensions have increased from 0.20" (18%
'TWD)-to 0.33" (30% TWD) in the deepest areas. These results were obtained from the manual technique utillzing several different transducers (see Attachment 1). The manual examination reported a maximum '
- length of 7.7" and a maximum depth of 0.33" (30% TWD) In addition to the manual, tho' P-Soan Automated System was ut i i Izod to obtain . accurate. -
finite-thru-wall dimensions. A-Scan slices were taken approximately every i 1/2" along the reflector's length resulting in'a final length of 6.93".
The depth recorded by P-Scan was 25% at the deepest location with an average depth of 15 to 20% over the length of the reflecter, t
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4 Page 2 of 2 l-Attached you will find sunenerlos of the equipment utilized and the l results of the three (3) successive examinations performed. if you L should have any questions or concerns regarding the above subject matter, l please feel free to contact me here at the Site.
Sincerely, _
13 Carl Latiolais Site Coordinator l
QA Concurrence: -u / I w[ Date Av/s - -
/M Attachments y ; uchi.e ocs K. F. Schmidt (w/ attachments)
R. Paillaman (w/ attachments)
M. Orihuela (w/ attachments)
J. Blakely (GSU w/ attachments)
C.' Knox (Rockwell w/ attachments)
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AttachmentI
- 1) 45 Degree liighly Danpened Shear fave - Manual Exams (AbsoluteArrivalTineTechnique)
- 2) 60DegreeL-fave-Automated &WanualExams (TineofFlight)
- 3) 30-70-70IST702.0Ez-Automated &ManualExans
- 4) 30-70-70 ISY 70 4,0 Ez - Automated Exans
- 5) 45 Degree Shear lave 2.25 Ez (WSTS) - Manual Exans
- 6) 45 Degree Shear Wave 2.25 Ez (58)
Automated &ManualExans 7). '48 Degree Shear Wave 3.5 Ez - Automated Exams (AbsoluteArrivalTineTechnique)
- 8) 0 Degree WS8 4.0 Ez-- Manual Exans 0
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ATTACHMENT II 1813*D001-N4A-2 APRIL 1989 MARCH 1990 NOVEMBER 1990.
L 6.125" -HANUAL (EBASCO) 6.625" HANUAL 7.7" HANUAL E
N G GEOMETRIC (GE SHART) 6.625" P-SCAN 6.93" P-SCAN T
H D 20%. !!ANUAL PLANAR (EBASCO) 20% / 18% HANUAL 30% HANUAL E
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T GEOMETRIC (GE SHART). 20% P-SCAN 25% P-SCAN I H
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ESASCO SERVICES INCORPORATED l gy'R,' BfILEY OR* OATE ll-!Eo9 0 SHEET O F .--
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Enclosure 3 HELLIER ASSOCIATES - SOUTH CENTRAL Technical Training & Consulting 2100 Riverchase Center Suite 108 Birmingham, AL 35244 (205) 733-9992 FAX (205) 733 9993 November 18. 1990 ,
Mr. -Jimmy Blakely Gulf States Utilities P.0'. Box 220-St..Francisville, La. 70775 g
Dear-Hr'. Blakely,
Attached is the. report,of the ultraconic examinations performed on the River-Bend Unit 1 No:: le-to-Saf eend weld
- 1813*D001-N4A-2 during RF3.
I performed ultrasonic examinations in accordance with EBASCO procedures GS-UT-W81-4,. Revs 3 and 4,.and GS-UT-W81-7, Rev 2 to detect, characterize, and size the indication previously detected during RF2 and MCY2. In addition, I evaluated the examinations and data provided by EBASCO and the P-Scan automated system.
i Based upon the results of the RF3 examinations, the-
, indication has grown.in depth from 18%-(.200") through-wall L to.30%-(.330"), and . in lenir th ( l'. 6" ) to 7.7 inches -
!: ' Additional P-Scan-data was collected every 1/2 inch cf the L length for.. future examinations'to accurately characterize the flaw during subsequent outages.
- Thank you for the opportunity to assist you and your staff. 4
- If you have any questione or. comments please call me at (205) 733-9992.
3 ,
Sincerely, s WY J. Mark Davis wJ Hellier Associates, Inc.
UT Level III O
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1 HELLIER ASSOCIATES - SOUTH CENTRAL Technical Training & Consulting 2100 Riverchase Center Suite 108 Birmingham, AL 35244 (205) 733 9992 FAX (205) 733 9993 FINAL REPORT Ultrasonic Examination of the Gulf States Utilities Riverbend Station Unit 1
, H4A Feedwater Nozzle An ultrasonic exanination was performed on the Unit 1 N4A Feedwater Nozzle-to-Safeend weld using EBASCO Procedures OS-UT-WB1-4, Revs 3 and 4, and GS-UT-W81-7, Rev 2. This
-xamination was performed to detect and size the indication intially found during the April 1989 RF2 outage and ,
subsequently verified during HCY2 in March 1990.
First, a O degree HSEB straight beam examination was performed to verified the inside diameter geometry, e.g.,
counterbore. No significant thickness change was recorded to indicate a geometrio condition on the inside diameter of the pipe.
Secondly, an ID Creeping Wave transducer was used to verify signals previuosly detected in March 1990. A very noticeable change was observed in signal amplitude and the presense of-an: additional 70 degree L-wave was noted. These changes indicate a flaw depth of1approximately 20% to-40% through-wall.
Additionalotransducers (tip diffration, 45 and 00 degree refraoted~L-waves) were used to detect and record specific signal' patterns and signal locations. These examinations are documented on the appropriate calibration data sheets for each examination.
Initial results ofathese examinations. indicate a slight' increase in flaw lengthlaf 1.8 inches. Art increase in flaw >
depth was recorded.from 20% to approximately 35% to 45% '
through-wall, i To percisely quantify'the flaw depth and length, automated F P-Scan-examinations were performed. Final analysis of the s P-Soan data reports-the final depth at 30% through-wall.
Automated data was collected along-the flaw. length every 1/2-inch. The-length of the flaw is-reported at 7.7 inches.
RSferences: EBASCO letter dated 11/12/90, from Mr'. Carl I Latiolais to Mr. Roger Carlyle'with attachments.
O. Y _ms (2. H a'r k Da v is UT Level III u
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. ., HELLIER ASSOCIATES - SOUTH CENTRAL Technical Training & Consulting
- 2100 Riverchase Center Suite 108 Birmingham, AL 35244 (205) 733 9992 FAX (206) 733 9993 Hovember 18, 1990 Mr. Jimmy Blakely Gulf States Utilities P.0. Box 220 St. Francisville, La. 70775
Dear Mr. Blakoly,
In order. to clarify the P-Soan and manual depth sizing examinations, the following addendum to my previous letter is offered in support of the final depth sizing estimate of the flaw in the H4A Nozzle.
If you have any questions please call me.
Sincerely, V J. Mark Davis Hellier Associates, Inc.
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ADDENDUN TO BL&KELY LETTER DATED 11-16-90 FRON DAVIS Of all the depth sizing techniques used, no one technique is best for sizing all flaws at any depth.
In order to characterize or bound the~ flaw, the thickness of material is divided into thirds. There are techniques which are best for the inner third thickness; l techniques for the' middle third thickness; and techniques for the outer third thickness. l Inner Third Tip Diffraction Techniques Middle Third Bi-Hodal Techniques High Angle L-Wave Techniquen I Outer Third The flaw-is. initially characterized with an ID Creeping Wave technique to bound the flaw into one of the i aforementioned zones (thirds). This is accomplished by' l the presence or absence of the 70 degree L-wave, CE-1 or l the CE-2 signals. Also. the amplitude and echo dynamics of these signals are J- arved to support the initial 1
. sizing estimate. (Nc.-sr I have qualified this sizing technique, ID Creeping Wuve, at the EPRI HDE Center as the only technique used with very acceptable results.)
The final 30X estimate is based upon a comprehensive L analysis of.all techniques used. As.in the EPRI program, l various degrees of " difficulty" or " confidence" are H
apparent-for each technique and each flaw sized within c its1 zone. The final sizing result istbased upon all L these factors-and is the combined analysis of the manual L and automated sizing techniques.
Based upon my evalustion of all.the data presented and L by my own observation of the signals, I feel very L
confident of the sizing results observed for the flaw l detected in the N4A nozzle-to-safeend weld.
All personnel who performed depth sizing.have been qualified st the EPRI NDE Center. Also,- the P-soan p.
- system and operator have been qualified for sizing.
[ /WJJ .~r
. Matk Davfs T Level III h
_ Enclosure 4 Q* PAGE lof 5 U.T. HISTORY OF WELD nib 13*D001-N4A-2 j (REFLEL OUTAGE u2) i On 4/27/89: E8ASCO performed IGSCC detection examination on the '
subject weld and found an: indication Which exhibited planar flaw characterisitics. This detection examination was performed utilizing a 45 degree longitudinal transdJCer. The length of the indication as '
neasured with this technique was 6.125".
.Also on 4/27/89: E8ASCO apolied 60 degree longitudinal'and 45 degree i shear wave techniques in an effort to confirm the initial detection I results. The results of the additional discrimination technioses I apolied confirmed the presence of a planar flaw producing signals similar to a multi-faceted response expected from an IGSCC-type of j reflector. The length of the indication as treasured with both !
technicpes was recorded as 6.0".
On 4/08/89: EBASCO attempted planar flaw sizing in order to achieve a finite through-wall dimension from the aforementioned indication. i The following is a-breakdow) of EBASCO manus,i sizing data based on various' techniques: !
)
1 IECHN{QYE _(FJ;p SHE_OBTAINE_D T.W t UJ,, (EliGRi_OElTAEsp TlilCKNFJS WSY -70 (2 mhz) ' CE-1 <5% FSH ASSOCIATED WITH CE-2 FOR Ft.LL LENGTH. ,
THIS TECHNIQI WAS UTILIZED TO LOCATE THOSE MEAS OF (
CEEPEST THROUGH-W4.L DIPENSIONS MD ESTABLISHED A I RANGE FOR FINITE SIZING.
'52 DECfiEE
. HIGHLY-D@P.
(MTT/RATT) .20" 18% .6.125" 1.1" l By utilization of .these two technicues:: EBASCO determined the above values for-final dimensioning of the indication.
Also in 1989: General Electric performed IGSCC detection
-Gxaminations utilizing their automated system (SMMT). G.E. determined at this time that the indication was geometric in nature and reQJired
.no further discrimination / sizing to be performed.
3 At this time: Gulf States Utilities chose to,take ths more conservative of all the available data and reported the indication to
.be a planar flaw with an overall length of 6.125" and exhibiting a through-wall dimension of .20" (18%).
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' P/<.I ? of 3 (MIDCYCLE OUTirE)
Ch 3/20/90; EBASCO performed IGSCC detection c omination on the wb',oct 6 eld and determined that no additional ir,dications other than the one recorded previously existed.
Also on 2/20/90; EBASCO apol'od planar flaw sizino technioses in an ef f ort. to detertaine any occuth that trav have occured since RF-2. The followino is a breaLdx of rBASCO mnual 2,izing data based on the variaus technimes used:
KCBNIMJ,CCQ Oist 00161!dRD LW t 11% L W 9TH sq161!i(Q RilCM (C4 45 DEG. SHEAR N/A N/A 6.625" 1.1" (The eraminer t'oted that at t.his titre the indication e411bited planar character istics) .
I 52 (CCAEE HICNLY [**@ .
(PATT) .20" 18% 6.625" 1.1" 60 CCG. LONG.
(TITE OF FLIGiT) .20" 10% 6.625" 1.1" 48 DEG. SHEAR (AATT) .00" 18% 6.625" 1.1" WSY /0 (2 nhz) CE-1 (51 FSH ASSOCIATED WITH CE-2 FOR FLLL LENGTH.
THIS TECHNIQLC WAS UTILIZED TO LOCATE THCCE (AEAS OF CCEPEST THROUCN-WLL DIFENSIONS AND ESTABLISHED A RfNGC FOR FINITE SIZING.
On 3/20/40; Hellier Assoc. personnel perforrred a third party verification of the indication detected in RF-2. The following is a breakdown of the manual sliing clat.a conciled, based on t,he various techniques ur.ed:
IEQiNIMJllE.Q IIELMLAlli(Q T.W. $_13, (QQ1tLCQJAKQ ItiLQg(M WSY 70 (2 tihz) A CE-2 SIGN %. (I.D.' CREEPING M6VE) WG OBSERVED THE Ft.LL LENGTH OF THE INDICATION, THIS INDICATED A 0ASE CF A PLAN /A INDICATION AT THE INSIDE DIffETER SLRFACE.
A SIM.L (WLITLCC CC-1 (30-70 70 MIC CONVERTED StGM.) OF LESS THAN 5% OF FLLL SCREEN HEICHT M4S RECORDED. THIS INDICATED A R/-NGE OF /@PROXIt%TELY 10%
T11ROLGH-44.L DItCNSION RESLLTING IN A VFLLE OF .198" OACED ON A THICXNESS OF 1.1".
52 ECGREE HIGiLY 04N.
(C.T.D.) EXHIBITED HIGH SIrNAL-TO-NOISE RATIOS (LONG LENGTli OF REFLECTOR INDICATIVE OF PLfN/A ORIENTED FLAN TIPS NEAR THE I.D. OF THE SAFE-END TO NOZZLE LELD.
i I
PWE 3 of 5 1 l
T ft!N.19 X._LE Q S.IIE COTAINED T.W2 LI,.W,.,. LENQTji_ QTA,IJQ EIQg4gM 45 DEG. SHEAR N/A N/A 6.625" 1.1" At this time: the examiner noted that Ultrasonio signals indicative of IGSCC with split signals was observed; e.g. f ast rire and fall tine, thort pulse d.; ration f aceting and branching, nultiple peaks, e.tc .
Also on 3/20/90: Danish Welding Institute under EBASCO's direction:
performed automated examination with their system (P *C40 in an attecot to provide a correlation between future autorrated and tranual examinations to be performed.
The examination was per forned in thrce phases. The first phase was !
detection perforned on the entire weld 360 degrees both sides. The ;
results were that no indications other than previously recorded was '
found. This was dcne utilizing 45 degree shear wave techni Ne.
O The second phase was diserimination perforned utilizing various cther angles. The results of the discrimination led to the .
l consideration of this indication as being a planar flaw rew iring further acolication of sizing technim es.
This brought about the third and final phase; sizing. The following is a breakdown of the autocated sizing data corpiled based on the various techniques osed: '
IE.CtiN1Q(g,,,,W{Q U gg_(O TAIF1p_,T . W . *$ T.Wa 1,.fNGTH COTAIN,J.Q THICKNEF4 45 DEG SHEAA N/A N/A 6.695" 1.1" 48 DEG. SHEAR N/A N/A 6.616" 1.1" WSY 70 N/A N/A 6.176" 1.1" 60 DEG. LCNG. NO SIGNIFICANT SIGN /t.S PRESENT FOR SIZING.
Upon overall review of the dutoma.ted data; the NDE Level-III >
retoonsible for the P-Scan determined that the thru-wall dimension neasurenent was .00".
Upon review of all available data conciling the i .'wlts of the above technicues; it was determined that the indication exh',bited a throucta-wall dimension of .10" to .00" along it's entire length. The
< 8 degree shear and the WSY 70 are recogiized by EPRI as being dependable technimes for determining length of reflNtor over the 45 degree shear. Utilizing the more conservative of these two tech' <1uest the length was determined to be 6.616" with the autonated syste.n exam.
At this tine; Gulf States Utilities chose to take the more conservative of all the available data and reoorted the indication to be a planar flaw with an overall length of 6.625" and exhibiting a through-wa 1 dinension of .20" (180 .
Cased upon the ultrasonic examinations performed with tPe cforementioned technicues: this indication did not appear to grow in length or doth since the previous exam. Length and depth sizing results are well within the accuracy reQJirements of U.T. sizing using the technicues acoroved by the EPRI NDE Center.
PAGE 4 of 6 (REPUEL OUTAGE #3) 1 On 11/12/901 ESAS(X) perfomed ICSOC detection examination on the subject weld and detemined that no additional indications other than <
the one recorded previously existed.
1 Also on 11/12/90: EBAS00; in conjunction with Hellier Associates personnel; applied planar flaw sizing techniques in an effort to determine any growth that may have occured since mid-cycle I examinations were performed. he following is a breakdown of EBAS00 manual sizing data based on the various techniques used:
TEDINIQUE USED SIZE OBTAINED T.W. 4 T.W. LENOW OBTAINED WICKNEES WSY 70 (2 mhz) A CE-2 SIGNAL (I.D. CREEPING WAVE) WAS OBSE VED W E FULL LENGW OF WE INDICATION AT MUOI HIGHm AMPLIWDES WAN PREVIOUSLY RE00RDED. WIS INDICATED A LARGER REFLECTING SURFACE RESULTING IN MORE SOUND RE' TURNING W WE WANSDUCER. CE-1 (30-70-70 LODE 00NVRTED SIGNAL) SHOWED A HIGHER AMPLIWDE WAN PREVIOUSLY NOTED (104 FSH) INDICATING A RANGE OF 20%
'IO 40% WROUGH-WALL DIMENSION (QUALITATIVELY). IN ADDITION: A 70 DEDREE LONGIWDINAL SIGNAL WAS NOTED WHIGI GAVE EVIDENCE SUPPORTIVE OF INCREASED GROWDI.
45 DED. SHEAR ( AATT) i HIG(LY DAMPENED .25" 23% N/A 1.1" 45 DEG. 14NG. WELD DEFECT (e.g. slag) NOTED IN UPPER 'DlIRD OF WELD NOT CONNEUTED 'IO WE I.D. SURFACE.
l 45 DEG. SHEAR (AATT) .33" 30% 7.7" 1.1" On 11/17/90 Danish Welding Institute under EBAS00's direction; perfomed automattd examination with their system (P-SCAN) in an attempt to supply finite sizing data that would verify the manual
. examination data obtained.
The examination was performed in three phases. h e first phase was detection perfomed on the entire weld 360 degrees both sides. he results were that no indications other than previously recorded was I found. h is was done utilizing 45 and 60 degree icngitudinal wave techniques.
Be second phase was discrimination perfomed utilizing various other angles so as to ditforentiate between any possible geometric
! reflectors. Be results of the discrimination led to the application of other sizing techniques.
Bis brought about the third and final phase; sizing. he following is a breakdown of the automated wizing data compiled based on the various techniques used:
l
l
- PAGE 5 cf 5 i
TECHNIQUE USED SIZE OBTAINE T.W. % T.W. LENGN OBTAINED WICENIBE 45 Dm. SHEAR .273" 25% 6.803" 1.1" 48 Dm. SHEAR .247" 22% 6.930" 1.1" l WSY 70 (2 & 4 mhz) .16" .273" 15-25% 6.482" 1.1" 60 DM.10NG.
(RID) .202" 18% 6.853" A.1" 60 Dm.14NG.
(MmASONICS) .218" 20% 5.682" 1.1" l 45 DE. LONG ,
(TIME OF FLI0rtT) .258"
(
23% 6.803" 1.1" Upon review of all available data compiling the results of the above techniquesi it was determined that the indication exhibited a through-wall dimension of .165" to .33" alor.g it's entire length.
At this time: Oulf States Utilities chose to take the more conservative of all the available data and reported the indication to be a planar flaw with an overall length of 7.7" and exhibiting a through-wall dimension of .33" (30% TWD) .
Based upon the ultrasonic examinations performed with the aforementioned techniques; this indication appears to have gr.,wa in length and depth since the previous exam. An increase in the overall
- 1ength of the indication of 1.1" and increase in the depth of .13" has been recorded.
Utilizing the most conservative values of the data presented to date taken on the subject welds the writers have determined that the fJnal dimensions for evaluation / analysis are as follows:
LlHZM 7.7" NRU-WALL DEPDit .33" T.W. % AGE: 30% EICENESS: 1.1"
? rd/ ny _ _.
A A Dated: n b W9A t <
Ooorge"J. Sechler; OSU NDE Level III Dated: 8/ O Carl latiolais; EBASCO Lead Technician
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