ML20236B097
| ML20236B097 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 07/31/1987 |
| From: | Billy A, Haar J ABB IMPELL CORP. (FORMERLY IMPELL CORP.) |
| To: | |
| Shared Package | |
| ML20236B080 | List: |
| References | |
| 01-0300-1611, 01-0300-1611-R00, 1-300-1611, 1-300-1611-R, NUDOCS 8707280336 | |
| Download: ML20236B097 (12) | |
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EVALUATION OF ULTRASONIC EXAMINATION INDICATIONS j f.
ON RCS LOOP B HOT LEG ELBOf FOR THE TR03 AN NUQ. EAR FtANT Prepared for:
PORTLAND GENERAL ELECTRIC COWANY L
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Prepared by: j Impe11 Corporation 1 350 Lennon Lane i Walnut Creek, California 94598 I I
Impe11 Report No. 01-0300-1611 J uly,1987 4
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..y IMPELL CORPORATION REPORT APPRO/AL ODVER SHEET Cl ient: Portland General Electric Pr<tj ect: Troj an Job Humber: 0300-038-1336 Report
Title:
Evaluation. of Ultrasonic Examination Indications on RCS Loop B Hot Leg ' 4! bow keport Number: 01-0300-1611 Rev. O The work described in this Report was performed in accordance with the Impe11 Quality Assurance Program. The signatures below verify the accuracy of this i Report and its compliance with applicable quality assurance requirements.
'n Prepared By: Date:
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Approved By: MMJ TIr for $INAAR- Date: 6!U!87 i
k REVISION RECORD Rev. Prop e Rev t e,v ed Apprwed Apprw al Reviston No. 8 .
Date 1 / "
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FO A 7.T. #4M As indicated on pp. 7 and 8
Report No. 01-0300-1611 Revision 0 TABLE OF CONTENTS fhGE APPROVAL COVER SHEET 1 TABLE OF CONTENTS 11
1.0 INTRODUCTION
1
1.1 BACKGROUND
1.2 SCOPE OF WORK 2.0 FLM CHARACTERIZATION 2 2.1 AK)ATA RESULTS 2.2 CHARACTERIZATION OF SUFEA MD SUBSURFAT FLMS FOR INTERACTION 2.3 DETERMINATION OF BOUNDING FLM SIZE 3.0 FLM ACCEPTAN% EVALUATION 6 3.1 ACCEPTANT STANDARDS 3.2 FLM EVALUATION
4.0 CONCLUSION
S 7 S.O RECOMMENDATIONS 7 6.0 REFERENTS 8 LIST OF FIGURES FIGURE TITL E 2-1 REGIONS OF EXAMINATION 3 2-2 INDICATIONS ON 3 0' CLOCK SIDE 4 2-3 INDICATIONS ON 9 0' CLOCK SIDE S
Report No. 01-0300-1611 Revision 0
1.0 INTRODUCTION
This report provides the results of an evaluation of indications found in recent in-service-inspections of the hot leg elbow in the "B" loop of the Trcd an Reactor Coolant System.
I
1.1 BACKGROUND
An ultrasonic volumetrie examination was recently performed on the B hot leg elbow by AMDATA, Inc. with assistance f rom EPRI Nondestructive Examination Center (NDEC) Personnel. The Amdata Report (6.2) identified seven indications in the elbow. Two of the indications were volumetric mid-wall reflectors and five were inside surf ace planar reflectors.
This report stanmarizes the evaluations performed by IWELL to verify that the indications are within allowable limits and that the structural integrity of the elbow is not compromised.
1.2 SCOPE OF WORK The scope of work performed consisted of the following tasks:
A. Flaw Characterization - This task consisted of the following:
o Reviewing the data regarding the ultrasonic examination -
indications o Characterization of surf ace and subsurf ace flaws for interaction between detected flaws in accordance with IWA-3000,Section XI, of the ASE B&PV Code o Determination of bounding flaw size for both surf ace and subs,urf ace flaws for subsequent acceptability ev al uation
- 3. Flaw Evaluation - In this task, the acceptability of the bounding surf ace and subsurf ace flaws sizes was evaluated against acceptance standards derived f rom IWB-3500,Section XI, of the ASE B&PV Code.
The results of these efforts show that the flaws meet the established acceptance criteria.
Report No. 01-0300-1611 Revision 1 200 FLM 04ARACTERIZ ATION This section describes the methodology used in performing f1w characterization of the indications identified by Ultrasonic Examination
( UT) .
2.1 AWATA RESULTS As described in the AMDATA report (6.2), an ultrasonic examination was performed on the side faces of the hot leg elbow in loop B.
lb The approximate regions of examination are shown by Figure 2-1.
The report states that seven indications were detected during examination of the elbow. Two of the indications were volumetric mid-wall reflectors and five were on the inside surf ace. The report also identifies the location of the various indications.
Figures 2-2 and 2-3 are graphical representations of the flaws at the 3 and 9 o' clock location and the nominal elbow dimensions.
As described in the report, all f1ws were estimated to have lengths of less than 0.3 inch. The extent of penetration through the wall of the ID indications is also expected to be less than 0.3 inch. '
From conversations between AMDATA personnel and Impe11 personnel (6.3) the separation between indication #2 and #3 was documented and is shown on Figure 2-3.
2.2 CHARACTERIZE ATION OF SURFAG AND SUBSURFAN FLMS FOR INTERACTION Review of the indications in accordance with IWA-3300,Section XI of the ASE B&PY Code showed that the various indications are sufficiently seperated and that all can be characterized as isol ated flaws.
The minimum separation distance between any two flaws was found to be 1.0 inch between indications #4 and #5. This is greater than twice the maximum possible flaw dimension of 0.3 inch. The flaw s are, therefore, outside interaction distance.
2.3 DETERMIN ATION OF BOUNDING FtM SIZE Each indication was converted to a bounding configuration as shown by the details in Figures 2-2 and 2-3. Dimensions in all cases are based on maximum estimated length and maximum estimated depth which are both 0.3 inch.
In the absence of information regarding the possibility that the inside surf ace indications may be associated with, or attributable to, geometric cr metallurgical origin, they have been conservatively consider-d as planar flaws.
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Report No. 01-0300-1611 Revision 0 3.0 FLM AC&FTANN EV ALUATION This section summarizes the methodology used and the results of evaluation of the characterized flaws.
3.1 ACT PTANE STANDARDS The acceptability of the characterized indications was determined based on the acceptance standards provided by IWB-3500,Section XI, of the ASME B8PV Code (6.1).
The characterized flaws were compared to the allowable planar flaws for austenitic stainless steel piping as delineated in Table IWB-3514-2. This is considered applicable for in-service-inspection of the cast stainless steel (ASTM A351-CF8M) el bow.
Although explicit requirements for ultrasonic examination of austenttic cast fittings are not yet provided by Section XI of the Code, the acceptance standards used are considered the appropriate criteria for in-service-inspection of the elbow.
3.2 FL M EV AL UATION The allowable planar flaws for in-service inspection of the elbow were determined using the date f ran Table IWB-3514-2 for volumetric examination method applied to a nominal wall thickness of 3.0 inch.
Subsequent evaluation is based on a flaw aspect ratio (that is flaw depth divided by f1 mv length) of a/1 = 0.5. This ratio is as calculated for the bounding flaw sizes for the subsurf ace flaws.
The flaw aspect ratto as calculated for the surf ace flaws is a/1 = 1.0, a ratio which is not given in Table IWB-3514-2. the use of data from the Table using an aspect ratio of a/1 = 0.5 for the surf ace flaws is considered conservative since the allowable limits in the Table increase with increasing aspect ratio.
The allowable planar flaws are therefore as follows:
a) Sur f ace Fl aw s (t = 3 inch & a/1 = 0.5 )
a/t = 11.1% or a = 0.111 x t = 0.333 inch where a is the allowable depth b) Subsurf ace Fl ew s (t = 3 inch & a/1 = 0.5) a/t = 11.1Y%
Report No. 01-0300-1611 Revision 2 where Y = 1.0 for the characterized subsurface flaws, ,
and where a = 1/2 the total depth of a subsurface flaw l 1
Therefore, a/t = 11.1% or a = 0.111 x t = 0.333 inch l For subsurf ace flaws the total depth is 2a. Therefore, the allowable flaw depth is equal tos j i
2 x a = 2 x 0.333 = 0.666 inch j Since the calculated allowable planar fim depths exceed the bounding sizes of the characterized flaws, the allowable limits are met. On this basis, > the acceptability of the elbow for continued service is assured. 1 4.0 CONQ.USIONS i Based on the analysis efforts previously described, the hot leg elbow remains acceptable for continued service and the identified fims do not .i compromise the structural integrity of the hot leg elbow.
In addition, prwious IWELL fatigue and f racture mechanics analyses (6.5 q '
& 6.6) demonstrated that service induced f atigue creep damage is _ .
negligible and that crack /fler growth is not expected for a postulated circumferential flaw with a depth of 0.25 inch and a length of 1.50 inch. These analyses included the effects of loadings based on postulated lock up of steam generator snubbers. The dimensions for the g!
postulated flaw were based on a fim depth of 1/10 of the nominal (2.5 inch) wall thickness of the hot leg piping. The bounding depth of the !
indications f rom the examination of the elbow was defined as 0.3 inch.
This is less than 1/10 of the nominal thickness of the hot leg elbow. !
I 5.0 RECOMNDATIONS 5.1 The A@ATA inspection results should be considered as initial evidence of indications within the elbow for subsequent examination and evaluation ef forts.
5.2 An examination procedure should be developed for a future reexamination of the elbow to determine if there is any evidence that the indications are growing. The Troj an 1989 refueling outage would be a reasonable period in which to perform the re-examination.
i Report No. 01-0300-1611 l Revision 2 1 The examination procedure should include a practical approach to d determine the possible geometrical or metallurgical origin of the indications in compliance with Appendix III,Section XI (6.8). It is possible that the inside surface indications could actually be due to surf ace texture (roughness, waviness). The midwall ,
reflections could be due to metallurgical origin (e.g. inclusions).
The recommended re-examination should be performed, to the extent f easibl e, in accordance with the requirements established for ultrasonic examinations in Appendix III,Section XI (6.8) as well T
as Code Case N-335-1 (6.7) .
Code Case N-335-1 provides further detailed requirements for ultrasonic examinations in the areas of equipment, procedures,
. calibration, etc. which could be beneficially applied to the re-examination of the hot leg elbow.
6.0 REFERENCES
l 6.1 ASE Boiler and Pressure Vessel Code,Section XI,1983 Edition
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6.2 AMDATA, Inc. Troj an Inspection Report, IR252, Rev. 5 dated 7/1/87, Entitled " Ultrasonic ' Inspection of a Statically Cast Stainless Stoel Elbow at the Troj an Nuc'. ear Power P1 ant" 6.3 Record of Conversation dated 5/13/87 between E.R. Dykes (AMDATA) and M.D. Ratt u (IMPELL) <
6.4 IWELL Calculation IND-01, Rev.1, Job No. 0300-038, 7/9/W 6.5 IMPELL Calcul ation RCL-05, Rev. O, Job No. 0300-031, 1/28/87 6.6 IMPELL Calcul ation RC1.-2, Rev. O, Job No. 0300-023, 10/10/86 6.7 ASME Boiler and Pressure Yessel Code Case N-335-1 " Rules for Ultrasonic Examination of Similar and Dissimilar Piping Welds" 6.8 ASE Boiler and Pressure Vessel Code,Section XI,1986 Edition