ML20058G784
| ML20058G784 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 12/02/1993 |
| From: | Stephen Dembek Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| TAC-M88099, NUDOCS 9312100126 | |
| Download: ML20058G784 (46) | |
Text
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it ! NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 December 2. 1993 Docket Nos. 50-277 and 50-278 LICENSEE: Philadelphia Electric Company (PECo)
FACILITY: Peach Bottom Atomic Power Station (PBAPS), Units 2 and 3
SUBJECT:
MEETING
SUMMARY
, EVALUATION OF CORE SHROUD INDICATIONS AT PEACH BOTTOM, UNIT 3 (TAC NO. M88099)
On November 3,1993, an open meeting was held in Rockville, Maryland, between the Philadelphia Electric Company (the licensee) and the NRC staff. The staff requested the meeting to discuss the licensee's evaluation of the core shroud i indications contained in its October 29, 1993 letter. The letter forwarded ! !
General Electric Co. (GE) report GENE-523-141-1093, entitled " Evaluation and j Screening Criteria for the Peach Bottom Unit-3 Shroud Indications." This i report provided the shroud fabrication history, chemistry and fluence i considerations, results of visual inspections, and conclusions from the flaw evaluation.
Enclosures 1, 2, and 3 contain the licensee's presentation slides, including additional slides that were utilized by the licensee but were not included in the handouts available at the meeting. Two of the slides presented by the licensee are not included in Enclosure 3 because a GE representative stated they were proprietary information. The information contained in these slides was not needed for the staff's review and they were not retained by the staff. '
Enclosure 4 contains a list of meeting attendees.
Mr. D. Miller, Vice President, PBAPS, PEco, opened the licensee's discussion '
with a brief introduction and overview of the intended presentation.
Mr. R. Ciemiewicz, from PECo, followed the introduction with a description of the shroud and a discussion of the probable causes of the indications.
Mr. Ciemiewicz used a scale model of the shroud in his discussion along with the first several slides contained in the licensee's handout (Enclosure 1).
The staff asked the licensee why the H1 and H2 welds (see diagrams in Enclosure 1 for weld locations) were determined to be less susceptible to the cracking problem. The licensee stated that this was because the oxidizing environment was lower at these welds. The staff also questioned the neutron fluence contribution to crack initiation and propagation. Mr. Miller stated that the staff's question would be answered later in the presentation.
- Mr. J. Stanley, from PEco, then discussed the methodology, scope and results of the examination. Mr. Stanley stated that the indications were evaluated by them in accordance with the initial screening criteria. The criteria were met; therefore, no further evaluation was required. Mr. Stanley stated that ,
the high carbon content areas were looked at extensively because the carbon content makes the material more susceptible to intergranular stress corrosion ,
cracking (IGSCC). The staff asked the licensee how it determined the cause of 9312100126 931202 ' b] I PDR ADOCK 05000277 (j f)'g n ] g I
o '
as.
o the cracking was IGSCC. The licensee stated that the staff's question will be answered later in the presentation. Mr. Stanley stated that only accessible areas of the H3 and H4 outer diameter welds were inspected. The staff asked the licensee how much area was inspected. Mr. Stanley stated that they were only able to look at 82% of H3 and 15-20% of H4 outer diameter welds, due to interference in the reactor vessel annulus. The licensee was questioned by the staff on their ability to identify tight cracks using underwater visual identification. The licensee responded that their inspectors were trained at the Carolina Power and Light Company's Brunswick Steam Electric Station prior !
to performing the inspections at PBAPS, Unit 3. Mr. Stanley used a slide (Enclosure 2) that was not included in the PEco meeting handouts to further explain their belief that their inspection was accurate. The staff asked if the licensee was able to draw a correlation between a core shroud flux map and the areas of indication. The licensee responded that they did not see a correlation.
Mr. M. Herrara, from PECo, then discussed the visual examination and evaluation processes. The staff was told during previous discussions with PEco that the fluence level was significantly higher than what was presented during this meeting. The staff asked the licensee to explain the difference.
1.ie licensee responded that the initial calculation was performed by PECo and it was incorrect. A subsequent evaluation by GE was used to determine the fluence value presented at the meeting. The licensee agreed to submit the letter from GE explaining the disparity to the NRC. The licensee stated that they passed both the quadrant screening and the total crack length criteria.
The staff noted that the licensee was close to the quadrant screening criterion and with the inclusion of possible inaccuracies it may have been exceeded. The licensee agreed that it was close to the quadrant criterion and stated it did not rely on it but relied on the total crack length criterion.
The licensee committed to revising its initial submittal to reflect the actual screening criteria utilized. However, the licensee and GE were able to demonstrate adequate structural integrity for the shroud based en the high degree of conservatism present in the flaw evaluation. l l
Dr. G. M. Gordon, from GE, then discussed the basis for the crack growth rate '
used in the evaluation. Dr. Gordon was able to answer the staff's questions on neutron fluence and IGSCC contributions to crack initiation and growth l rate. Dr. Gordon's presentation slides are included as Enclosure 3 (except as -
noted above).
Mr. V. Nilekani, from PECo, then discussed the evaluation of the structural integrity of the shroud. Mr. G. Edwards, also of PECo, discussed the actions that were taken to enhance the operator's awareness of the problem.
Mr. T. Niessen, from PECo, then summarized the licensee's approach and conclusions, i
l
At the conclusion of the meeting, the staff stated that the licensee aggressively pursued the disposition of the shroud indications and maintained close communication during the inspections and evaluation.
/S/
Stephen Dembek, Project Manager Project Directorate I-2 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Enclosures:
- 1. Licensee's Handouts
- 2. Slide used by J. Stanley
- 3. Slides used by G. Gordon
- 4. List of Attendees cc w/ enclosures: .
See next page '
DISTRIBUTION w/ enclosures 1-4: DISTRIBUTION w/ Enclosure 4 only:
Docket File TMurley/FMiraglia M0'Brien(2) JWiggins WSchmidt PDR & LDPR LJCallan 0GC DBrinkman JKauffman PDI-2 Reading SVarga EJordan, 3701 Llois TLiu EWenzinger, RGN-I JCalvo CAnderson KBattige WKoo CAnderson, RGN-I LNicholson EHackett KWichman CHsu SDembek JMedoff JDurr MHum RJones MModes RLorson RCapra ACRS(10)- n VMcCree, 17G21 JStrosnider o m cE LA d[lIS h PM:PDI-2 f C:EMCB(h D:PDI-2j
- E MO[dRNfI' SDEMBEK: tic JSTROSNlbER LNICH5YsdN DME
/[)93 Ii /12/93 [1/I/93 f1-/ 7/93 0FFICIAL RECORD COPY FILENAME: A:\MTG-2. SUM i
4 At the conclusion of the meeting, the staff stated that the licensee aggressively pursued the disposition of the shroud indications and maintained close communication during the inspections and evaluation.
l A%fR Stephen Dembek, Project Manager ,
- Project Directorate I-2
' l Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Enclosures:
- 1. Licensee's Handouts '
- 2. Slide used by J. Stanley
- 3. Slides used by G. Gordon
- 4. List of Attendees cc w/ enclosures:
See next page i
4 9
?
Philadelphia Electric Company Peach Bottom Atomic Power Station,-
Units 2 and 3 CC*
i J. W. Durham, Sr., Esquire Mr. William P. Dornsife, Director i Sr. V.P. & General Counsel Bureau of Radiation Protection I Philadelphia Electric Company Pennsylvania Department of 2301 Market Street, S26-1 Environmental Resources Philadelphia, Pennsylvania 19101 P. O. Box 2063 !
Harrisburg, Pennsylvania 17120. I Philadelphia Electric Company ATTN: Mr. D. B. Miller, Vice President Board of Supervisors -i
, Peach Bottom Atomic Power Station Peach Bottom Township Route 1, Box 208 R. D. #1 Delta, Pennsylvania 17314 Delta, Pennsylvania 17314 ,
Philadelphia Electric Company Public Service Commission of Maryland ATTN: Regulatory Engineer, Al-25 Engineering Division ;
Peach Bottom Atomic Power Station ATTN: Chief Engineer .i Route 1, Box 208 231 E. Baltimore Street Delta, Pennsylvania 17314 Baltimore, MD 21202-3486 -
Resident Inspector Mr. Richard McLean ,
U.S. Nuclear Regulatory Commission Power Plant and Environmental 4 Peach Bottom Atomic Power Station Review Division :
P.O. Box 399 Department of Natural Resources :
Delta, Pennsylvania 17314 B-3, Tawes States Office Building i Annapolis, Maryland 21401 -
Regional Administrator, Region I U.S. Nuclear Regulatory Commission Mr. George A. Hunger, Jr.
475 Allendale Road Director-Licensing, MC 52A-5 ?
King of Prussia, Pennsylvania 19406 Philadelphia Electric Company
- Nuclear Group Headquarters :
Mr. Roland Fletcher Correspondence Control Desk !
Department of Environment P.O. Box No. 195 201 West Preston Street Wayne, Pennsylvania 19087-0195 :
Baltimore, Maryland 21201 i l
Carl D. Schaefer External Operations - Nuclear Delmarva Power & Light Company l P.O. Box 231 i Wilmington, DE_ 19899 ;
John Doering, Chairman i Nuclear Review Board l Philadelphia Electric Company i 955 Chesterbrook Boulevard l Mail Code 63C-5 l Wayne, Pennsylvania 19087 l l
1 1
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1 ENCLOSURE 1 ;
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PHILADELPHIA ELECTRIC COMPANY j I
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PRESENTATION TO THE NRC l
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ON i
PEACH BOTTOM ATOMIC POWER STATION'S i UNIT 3 !
l CORE SHROUD i
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1 I
ROCKVILLE, MD !
NOVEMBER 3, 1993 l
l
- 1. INTRODUCTION- MILLER
- 2. DESCRIPTION OF SHROUD CIEMIEWICZ l 1
- 3. PROBABLE CAUSES OF SHROUD CIEMIEWICZ i INDICATIONS !
- 4. METHODOLOGY, SCOPE AND RESULTS STANLEY !
0F EXAMINATION l
- 5. FRACTURE MECHANICS ANALYSIS AND HERRERA SCREENING CRITERIA
- 6. EVALUATION OF STRUCTURAL NILEKANI INTEGRITY OF SHROUD l
- 7. OPERATIONAL AND OUTAGE PLAN EDWARDS CONSIDERATIONS FOR NEXT CYCLE l
l
- 8.
SUMMARY
NIESSEN l i
REACTOR PRESSURE VESSEL AND SHROUD STATISTICS VESSEL -
GE BWR-4:.1065 MWE (NET) 251 DIAMETER VESSEL 764 FUEL ASSEMBLIES INITIAL CRITICALITY: 8-6-74 CUMULATIVE EFFECTIVE FULL POWER YEARS: ~10.00 SHROUD -
- 207" DIAMETER X 279" HEIGHT-(17.3') (23. 3 ')
TYPE 304 STAINLESS STEEL CYLINDRICAL STRUCTURE FABRICATED BY ROTTERDAM DRYDOCK NOT A PRIMARY PRESSURE B0UNDARY COMPONENT DIRECT COOLANT FLOW, PROVIDE LATERAL SUPPORT, PROVIDE FLOODABLE VOLUME
REACTOR PRESSURE VESSEL AND SHROUD :
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i l CAUSES OF SHROUD INDICATI0_NS 1 INTERGRANULAR STRESS CORROSION CRACKING 1 (IGSCC) i MATERIALS i FABRICATION : i ENVIRONMENT i i i l
- - - 1
PEACH BOTTOM ATOMIC POWER STATION UNIT 3 SHROUD CYLINDER MATERIAL DATA (304 STAINLESS STEEL) , PART NAME QUANTITY CARBON CONTENT- WT% UPPER RING 1 PIECE 0.035 i UPPER 2 PIECES 0.062 CYLINDER 0.062 CENTRAL RING 1 PIECE 0.030 CENTRAL 2 PIECES 0.057 CYLINDER 0.060 CENTRAL 2 PIECES 0.057 CYLINDER 0.060 ;
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LOWER RING 1 PIECE 0.035 1 LOWER 2 PIECES 0.059 , CYLINDER 0.059 i
EXAMINATION / EVALUATION PLAN METHODOLOGY i i IVVI EXAMINATION : RESULTS l ll ! CONSERVATIVE BOUNDING YES ! SCREENING CRITERIA MET ? h v NO MORE DETAILED l YES ' EVALUATION SECTION
- XI CRITERIA MET ?
v NO ! t UT AND FRACTURE YES MECHANICS SECTION
- XI CRITERIA MET ?
v NO MODIFICATION PER FSAR > CRITERIA INDICATIONS ACCEPTABLE
-i BASIS FOR i SHROUD VISUAL EXAMINATION SAMPLING 1 l
- 1. MATERIAL COMPOSITION I
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- 2. THE ELECTROCHEMICAL POTENTIAL (ECP), OR l OXIDIZATION OF THE MATERIAL IN THE COOLANT l t
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- 3. AREAS OF HIGHER NEUTRON FLUENCE !
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- 4. AREAS OF HIGH STRESS i I
- 5. AREAS OF. REPAIR DURING FABRICATION !
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- 6. RESULTS FROM BRUNSWICK UNIT NO.1 AND THE :
i OVERSEAS PLANT l P l f
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CORE SHROUD EXAM PLAN (3R09) i i i i l i ORIGINAL PLAN (PRIOR TO ISSUANCE OF SIL 572). i
- 1. PERFORM SAMPLE EXAMINATION ON THE ID AT !
8 CELL LOCATIONS AT THE "H3" AND "H4" : WELDS l
- 2. PERFORM SAMPLE EXAMINATION ON THE OD AT i 8 LOCATIONS IN THE HIGH FLUENCE AREAS AT i WELDS "H1", "H2", AND "H5" l
l l. i I
CORE SHROUD EXAM PLAN (3R09) REVISED PLAN (FOLLOWING IDENTIFICATION OF INDICATIONS ON THE "H3" AND "H4" WELDS)
- 1. PERFORM 100% EXAMINATION OF THE "H3" AND "H4" WELDS FROM THE
' ID
- 2. PERFORM 100% EXAMINATION OF ACCESSIBLE AREAS OF THE "H4" WELD FROM THE OD
- 3. PERFORM EXAMINATION "H3" WELD FROM THE OD, CORRESPONDING TO AREAS WHERE INDICATIONS WERE NOT IDENTIFIED FROM THE ID
- 4. PERFORM EXAMINATION OF THE "H3" WELD FROM THE OD, AT SIGNIFICANT~ AREAS CORRESPONDING TO THE LOCATION OF INDICATIONS IDENTIFIED ON THE ID
- 5. PERFORM SAMPLE EXAMINATION ON THE 00, AT 8 LOCATIONS ON THE "H1", "HF', "H5" AND "H6" WELD
- 6. PERFORM SAMPLE EXAMINATION ON THE OD AT 2 LOCATIONS ON THE "H7" AND "H8" WELDS
- 7. PERFORM EXAMINATION OF 1 VERTICAL WELD, ON THE ID, BETWEEN THE "H3" AND "H4" WELDS
- 8. PERFORM SAMPLE EXAMINATIONS OF THE CYLINDER PLATE ON THE ID, TO INCLUDE:
- 1) 8" WIDE AREA AT A VERTICAL WELD
- 2) 8" WIDE AREA BETWEEN "H3" AND "H4" WELDS
- 3) 2" WIDE AREA BETWEEN "H3" AND "H4" WELDS
l VISUAL EXAMINATION PROCESS / EVALUATION l APPROACH CONSISTENT WITH THAT USED AT ! BRUNSWICK UNIT NO. 1 AND THE OVERSEAS j PLANT ! ENHANCED VT-1 METHOD - RESOLVE A STANDARD ! ONE MIL WIRE : i INDOCTRINATION OF THE LEVEL II AND III ! EXAMINERS j CLEANING 0F THE SURFACE IN THE AREA 0F INTEREST PRIOR TO THE EXAMINATION l l - ALL SUSPECT AREAS WERE RECORDED AS ! INDICATIONS ; i DIGITAL RECORDING 0F SELECTED IMAGES TO : ASSIST IN LEVEL III EVALUATION : i INDEPENDENT LEVEL III REVIEW 0F VIDE 0 TAPES OF THE MOST LIMITING AREAS ON THE !
- "H3" AND "H4" WELDS 4
r EXAMINATION RESULTS j INSIDE SURFACE l "H3" - CIRCUMFERENTIAL INDICATIONS. IN ! PLATE l
- NO INDICATIONS IN RING j "H4" -
CIRCUMFERENTIAL AND AXIAL INDICATIONS IN PLATE ! VERTICAL WELD - SHORT l CIRCUMFERENTIAL j INDICATIONS IN PLATE i NO AXIAL ; INDICATIONS OUTSIDE SURFACE ;
"H1" -
ONE AXIAL INDICATION IN PLATE 1 i l "H4" - TWO AXIAL INDICATIONS IN PLATE ALL OTHER AREAS EXAMINED ARE FREE OF ; INDICATIONS l
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SCREENING CRITERIA METHODOLOGY DEVELOPED TO PROVIDE FIRST-CUT l CONSERVATIVE CRITERIA FOR DISPOSITION OF . INDICATIONS l SIMPLE STEP-BY-STEP PROCEDURE i FURTHER DETAILED ANALYSIS CAN BE USED IF ! SCREENING CRITERIA IS NOT SATISFIED USING ! CONSERVATIVE ASSUMPTIONS l BASED ON ASME CODE SECTION XI CRITERIA i INDICATIONS COMBINED USING ASME CODE SECTION XI PR0XIMITY RULE l i ADDITIONAL CONSERVATISM INCLUDED TO DETERMINE FLAW LENGTH FOR LEFM GROWTH RATE OF 5 X 10-5 IN/HR USED USES BOTH LIMIT LOAD AND LEFM TO DETERMINE ALLOWABLE FLAW SIZES l STRUCTURAL INTEGRITY MAINTAINED IF "FIRST-CUT" SCREENING CRITERIA IS MET. IF NOT ' MET, FURTHER DETAILED EVALUATION CAN BE PERFORMED TO DEMONSTRATE ACCEPTABILITY l
i CONSERVATISMS INCLUDED IN CALCULATION OF SCREENING CRITERIA .
- 1. ALL SURFACE INDICATIONS WERE ASSUMED TO BE THROUGH-WALL FOR ANALYSIS. ,
- 2. THE SCREENING CRITERIA ARBITRARILY LIMITS ONE-FOURTH OF ALLOWABLE CIRCUMFERENTIAL FLAWS TO ANY ARBITRARY 90 SECTOR.
- 3. ALL INDICATIONS ARE ASSUMED TO BE GROUPED T07 ETHER FOR THE LIMIT LOAD CALCULATION AND NO CREDIT IS TAXEN F0s THE SPACING BETWEEN INDICATIONS. i
- 4. ASEE CODE PRIMARY PRESSURE BOUNDARY SAFETY MARGINS WERE APPLIED EVEN THOUGH THE SHROUD IS NOT A PRIMARY PRESSURE BOUNDARY. ;
- 5. ASME CODE, SECTION XI PROXIMITY RULES WERE APPLIED.
- 6. AN ADDITIONAL PROXIMITY RULE WHICH ACCOUNTS FOR FRACTURE MECHANICS ,
INTERACTION BETWEEN ADJACENT FLAWS WAS USED.
- 7. THE HIGHEST STRESS AND SEISMIC MOMENT COMPUTED FOR ANY SINGLE I LOCATION WAS USED FOR ALL LOCATIONS.
- 8. BOTH LEFM AND LIMIT LOAD ANALYSIS WERE APPLIED, EVEN THOUGH LEFM UNDERES11 MATES ALLOWABLE FLAW SIZE FOR AUSTENITIC MATERIALS, AND IS NOT REQUIRED PER SECTION XI.
- 9. FRACTURE TOUGHNESS MEASURED FOR SIMILAR MATERIALS HAVING A HIGFiR !
FLUENCE WAS USED.
- 10. THE BOUNDING CRACK GROWTH ESTIMATED FOR THE NEXT FUEL CYZ 'A WAS IFOLUDED IN FLAW LENGTHS USED FOR EVALUATION.
- 11. A PROXIMITY RULE TO ACCOUNT FOR PERPENDICULAR FLAWS WAS APPLIED, ALTHOUGH NOT REQUIRED BY SECTION XI.
- 12. POWER RERATE CONDITIONS WERE USED ALTHOUGH IT WILL NOT BE IN EFFECT DURING THE NEXT FUEL CYCLE.
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CALCULATED SCREENING CRITERIA . t t 4 l i CIRCUMFERENTIAL THROUGH-WALL FLAWS ! 344-INCHES USING LEFM 430 INCHES USING LIMIT LOAD ! l AXIAL THROUGH-WALL FLAWS C 59 INCHES USING LEFM . 200 INCHES USING LIMIT LOAD : l i
PEACH BOTTOM UNIT 3 SHROUD LIMIT LOAD CRITERIA FOR THROUGH-WALL CIRCUMFERENTIAL INDICATIONS W
, > 500" SEE NOTE #2 I 4 a o"
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PEACH BOTTOM UNIT 3 SHROUD LEFM CRITERIA FOR THROUGH-WALL CIRCUMFERENTIAL INDICATIONS y 400" l-C 344"------------------------------------- 2[ soo" - SEE NOTE #2 , g _J Z O oo" -
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. <C O y con - 94" 4 Q SEE NOTE #1 >56" Oo "H3" WELD "H4" WELD NOTE #1 NOTE #2: MAX SINGLE EFFECTIVE ALL WELDS SCREENING CRITERIA ASSUMING CONTINUOUS INDICATION LENGTH (INCLUDES THROUGH-WALL PR0XIMITY RULES AND CRACK GROWTH TO THE p w END OF NEXT FUEL CYCLE)
EVALUATION RESULTS . i ALL INDICATIONS EVALUATED TO SCREENING ! CRITERIA LIMITS i ALL INDICATIONS SATISFIED THE SCREENING ! CRITERIA FOR THE NEXT OPERATING CYCLE
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. l OPERATIONAL AND OUTAGE PLAN CONSIDERATIONS FOR NEXT CYCLE ,
l l l CONTINUE EXCELLENT CHEMISTRY OPER.ATIONS AWARENESS i NEXT OUTAGE EXAMINATION TO BE DEVELOPED IN ACCORDANCE WITH BWROG RECOMMENDATIONS , CURRENTLY BEING FORMULATED :
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i SU M RY AGGRESSIVELY ADDRESSED ISSUE- ! l STATISTICALLY- SIGNIFICANT SHROUD EXAMINATIONS COMPLETED i CONSERVATISMS BUILT INTO ANALYSIS OF-EXAMINATION RESULTS . SIGNIFICANT CONSERVATISMS BUILT INTO CALCULATION OF SCREENING CRITERIA. I i
~
BASED ON APPLICATION OF THE SCREENING l CRITERIA TO THE OBSERVED INDICATIONS, THE STRUCTURAL INTEGRITY OF THE , SHROUD IS MAINTAINED THROUGH THE NEXT l FUEL CYCLE WITHOUT THE. NEED FOR FURTHER ANALYSIS OP, EXAMINATION j 4 l
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ACCURACY OF EXAMINATIONS ! i
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ALL SUSPECT
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AREAS WERE RECORDED AS INDICATIONS OVERLAP 0F EXAMINATION AREAS (INDICATIONS ! WERE IDENTIFIED FROM ADJACENT CELLS) ' i TECHNIQUES USED FOR DETERMINING I INDICATION LENGTH CONSISTENT WITH OTHER : BWR 4 PLANTS ' ALL SLOPING AXIAL INDICATIONS WERE ! CALCULATED AS A CIRCUMFERENTIAL i INDICATION OF LIKE SIZE i INDEPENDENT LEVEL III REVIEW 0F VIDE 0 l TAPES OF THE MOST LIMITING AREAS ON THE !
"H3" AND "H4" WELDS :
RE-EXAMINATION AT SEVERAL LOCATIONS TO ! CONFIRM INDICATIONS - i i THE MARGIN l BETWEEN THE- CONSERVATIVE SCREENING LIMIT AND THE CUMULATIVE- ' EFFECTIVE INDICATION LENGTH -IS ; SIGNIFICANT : i l
._ - -. __ . _ _ - _i
BASIS FOR CRACK GROWTH RATE USED FOR PB-3 SHROUD WELD HAZ's G.M. Gordon
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BASIS FOR SELECTION OF PB-3 SHROUD WELD HAZ CRACK GROWTH RATE Peach Bottom-3 shroud cylinders fabricated from roll formed Type 304 Stainless Steel plate and weld HAZ's likely sensitized Neutron fluence further increases effective degree of sensitization GE PLEDGE SCC model developed to predict crack growth rates for sensitized and/or neutron irradiated stainless steels Model graphically indicates marked benefit of operating with pure (Iow conductivitiy) water ( Peach Bottom-3 early life conductivity high. More recent values excellent leading to a significant reduction in predicted crack growth rate
+ Conservative rate of 5xE-5 inches / hour used in crack length -
acceptance criteria includes effects of weld sensitiztion plus neutron fluence
SOLUTION RENEWAL RATE TO CRACK-TIP STRESS A p ANIONIC TRANSPORT \ OXIDE RUPTURE RATE AT ENVIRON- CRACK-TIP w MENT
- MICRO-7-FIELD STRUCTURE
> HARDENINjG RELAXATION-CRACK TIP $[A)~, pH ,
, PASSIVATION RATE AT CRACK-TIP y , GB.DENUDATIO EGREGATION 4 Schematic effects of fast neutron fluence, flux and gamma field on the various empirical and fundamental parameters which affect IGSCC of Type 304 stainless steel.
v r=Ah"ct k - >- - y ( / o ;! r1% r JA,JH2O r E
= Ju +
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n=< ,
,e f(k) + ,f(f)c, ,
l f l L Parameters of fundamental importance to the slip dissolution mechanism of . intergranular crack propagation in sensitized austenitic stainless steel.
The GE PLEDGE Slip Dissolution - Film Rupture Model of Crack Propagation 6 CT .
~ VT Crack-t.ip advance by
, enhanced oxidation at strained crack tip 1r
.n VT =AE CT Where:
V T = crack propagation rate A, n = constants, dependent on material and environmental conditions ; e E = crack-tip strain rate, formulated in l CT terms of stress, loading frequency, etc. l
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OBSERVED RESIDUAL STRESS PROFILES ' IN HAZ OF 24"-28" DI A. SCH. 80 PIPING I I I I I I l l l
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*Ng / + 100 m
\
% MM O e x o \
k._ -cr
-oa*Y o o, a e e
og o 1 G o _ ,x a x
\ O o 0 8a 6 0 a
\o 8 c@
g -100
,3 \d f' -
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/ _
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- - e-
-200 r
-40 -
-300 I I I I I I l l l 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 INSIDE FRACTION OF THROUGH-WALL OUTSIDE WALL DIMENSION WALL Through. wall (longitudinal) residual stress data adjacent to welds in 12 to 2 inch diameter stainless steel piping.
i
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P t 40 OD- ; ID 206.9 i 30 - 137.9 :' 20 - Total Stress - en
- 68.9 d l 10 -
f f pplied A Load Stress j i
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m O 2 m y E : E
- 68.9 ::
- 10 -
3 i
- 137.9
- 20 -
l 1
- - 2 06.9 !
- 3') -
' ' ' ' ' ' ' - 275.9
- 40 25.40 50.48 85.58 0 5.08 10.16 15.24 20.32 1 DEPTH (mm) 1 s
i i i Shroud analysis: total through-wall stress profile.
In-Core Bypass ECP vs Feedwater Hydrogen for a BWR-4 ECP, mV (SHE) 300 e ~ 200 - tw-100 - u O y Just Below Top Guide Level
-200 -
\
-300 -
\ 9 st Above Core Plate Level
'-B~ g g
-400 O 10 20 30 40 50 60 70 80 90 Feedwater H2, SCFM
GENE PLEDGE Model Prediction for PB-3 Sensitized Type 304 Crack Growth Rate Crack Growth Rate, in/h 1 984 e 200 mV
"~ ' ' *
'; 7 o mv
.000E_Os [S'i y-1992-1993
-100 mV 1.000E- 05
-200 mV
-300 mV 1.000 E- 06 : -
1.000 E- 07 O 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Conductivity, pS/cm - PLEDGE: 15 C/cm2, 20ksi/in
Effect of Conductivity on Sensitized 304 Crack Growth Rate-Crack Growth Rate, in/h 1.000E-04 - 200 mV 5.000E-05 _ 1.000E- 05
- oc O O NO c o n -
^
AG !
^ ^
1.000E-06 - o gg
- c
- M o
$M AG O
C TMM M O* O ' ' ' ' 1.000E- 07 O.05 ' O.1 0.15 0.2 0.25 0.3 ~ 0.3 5 , Conductivity, pS/cm. , , PLEDGE: 20 ksi/in,15 C/cm2 CAV: 20-25 kai/in,13 C/cm2,100-160 mV , - - _ _ . _ _ _ _ _ _ .___._______l.m__.x_ - _.___m_.,o m. . - _ . . . . _ ,,,,,,_..,_..,,.,..-.r, . , . . , . . . , . . _ _ ..,....,#_rm.... . .,,,,.s ..eL..,m,. , , , , , . . . . . . , , . . ,
6 8 0 g EFFECT OF NEUTRON IRRADIATION ON SHROUD CRACK GROWTH RATE _ ---,w. , .-.- , - - - , - - . ._ -.--,-.-w ---
-- - - w- e- + - -T--'---- ~* " * * *-=' ~ * *^'*' "-**' ' = *-'*** "'- ~ "'- '"- ^ "- "'#
IT Stress Relaxation Behavior j frorn irractation Creep I ca 0.8 '
.5 .
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~
o 0.4 - c -
.9 .
15 ' G $
- u. o.2 Type 304 Stainless Steel .
- at 288 C
' 22 102 ' 10 0" 10 10 2o 2
Neutron Fluence, n/cm (E>1 MeV) ! l . Stress relaxation behavior of type 304 stainless steel due to irradiatio
]
1 l i l
IGSCC CERT RESULTS ON IRRADIATED ANNEALED TYPE 304SS (288'C Pure H,0 with 32 ppm O,) 100 , e 80 - 60 - Severity of IASCC (% IGSCC) Observed Field = 40 - lASCC Threshold . 20 - i i i i i _ !~ _ i 0 1 5 10 ' 2 5 10 22 10'8 2 S ' 10 o 2 2 Fluence (>MeV)
21 i ! t i i 10 r_ i 1 19 n
/ 3 'o
'su -
SHROUD Iu , l ID c
\ -
k 9 - Y E b 10" { 00 U y - p - C i
- 2 / - X' -
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/
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% 10 : #/ >-
a w ./ m z / TOP CUIDE
$ h- : 10'7 I
--p I,
.[CORESUPPORTCORE
;=
a !- _ I I I i I g i 10 60 20 0 20 @ 60 80 AXIAL DISTANCE FROM CORE-MID-PLANE, ins 9
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GROWTH RATE VERSUS FLUENCE 1.00E-04 5 1.00E-05 P S .._ 1.00E-06 1E+20 1 E + 21 1E+19 Fluence (n/cm 2) i Stress intensity = 20 Ksi/in, Initial EPR = 15 C/cm2
* ~' o Fleet Reactor Water Conductivity Mean Values 81 -
100 % - fi u b3 l 00% ! ! n"
=
l H n 80% - ,= l' g I ! gP 70% - .a l f i 60 % y i p '$
. 6
= l o s=
- 50% - . l 3 E I = 1992 40% -
E
= f, D All Years
- P:
30% - ." l 20% ..- a pg .3 ;
%:y ,
- n lim - v~
10% - 2 t}I : 0l
- t i
. i ; ! i 0% -* to t t 0.350 0.400 0.450 0.500 0.550 0.600 0.050 0.100 0.150 0.200 0.250 0.300 Conductivity fuS/cm) .
_ , . , , - , . . .a - - - + - - - , , - - , -, -. -- n s. n - - - - , , , - , . - . - - - - - . , - - - - n - - - - . - , - - en
/
1 ENCLOSURE 4 LIST OF ATTENDEES ' MEETING BETWEEN NRC AND PEco I CORE SHROUD INDICATIONS November 3, 1993 NAME ORGANIZATION G. Edwards PBAPS E. Eckert GE - San Jose H. Abendroth Atlantic Electric T. Niessen PBAPS J. Carey PSE&G , R. C1emiewicz PECo V. Nilekani PECo ' C. Anderson NRC/RI E. Hackett NRC/EMCB J. Medoff NRC/EMCB J. Wiggins NRC/DE J. Juliano NUS D. Brinkman ! NRC/DRPE L. Lois NRC/DSSA I : K. Battige NRC/RI K. Wichman NRC/EMCB J. Stanley PECo J. Durr NRC/RI W. Schmidt ' NRC/RI M. Herrera GE G. Gordon GE R. Knieriem DP&L D. Miller PECo R. Dyle SNC K. Fisher PECo G. Cranston PECo J. Kauffman NRC S. Maingi Pa BRP T. Harris CP&L T. Liu NRC/DRPE i R. Zuercher Inside NRC i S. Weems ' MPR Assoc. M. Kray PECo W. Koo NRC , C. Hsu NRC l M. Hum NRC l L. Nicholson NRC/DRPE I J. Calvo NRC/DRPE i R. Mattson Struct. Integrity i R. Zong PECo J. Livingston GE M. Modes NRC R. Lorson NRC R. Jones NRC R. Capra NRC/DRPE l l l}}