ML17333A207

Nonproprietary Presentation Matls from 950810 Meeting W/ Aepsc,Nrc & Westinghouse Re Application of Revised Pressure Boundary Limits for Hej Sleeved Tubes

ML17333A207
Person / Time
Site:	Cook
Issue date:	11/30/1995
From:	WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
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ML17333A205	List: ML17333A204 ML17333A206 ML17333A207
References
WCAP-14514, NUDOCS 9512110195
Download: ML17333A207 (61)

Text

Westinghouse Non-Proprietary Class 3 WCAP-14514 Presentation Materials from August 10, 1995 Meeting with the American Electric Power Service Corp., U.S. NRC, and Westinghouse, Concerning Application to the Revised Pressure Boundary Limits for HEJ Sleeved Tubes November 1995 WESTINGHOUSE ELECTRIC CORPORATION NUCLEAR SERVICES DIVISION P.O. BOX 158 MADISON, PENNSYLVANIA 15663-0158 O 1995 WESTINGHOUSE ELECTRIC CORPORATION All Rights Reserved 95i2iioi95 95i201 PDR ADOCK 050003i5

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A meeting was held on August 10, 1995, between the American Electric Power Service Corporation (AEPSC), operators of the Donald C. Cook Nuclear Plant, Westinghouse, and the NRC at the NRC offices at One White Flint North, to discuss a proposal to change the Cook Unit 1 Technical Specifications to allow a revised pressure boundary definition for the hybrid expansion joint (HEJ) sleeved tubes.

The proposed amendment request would change the definition of the pressure boundary section of the parent tube in the upper, or free span HEJ region.

Currently the pressure boundary declaration for this region includes the entire length of tube which is hydraulically expanded, approximately 4 inches long, as part of the pressure boundary and therefore subject to the Technical Specification plugging limit applicable to this region of 40% depth by NDE. The portion of tube above the joint region is also applicable to the 40% depth plugging limit. As the tube and sleeve are mechanically coupled in the hardrolled region of the tube in the upper joint region and the hardroll is placed within the 4 inch length of hydraulically expanded length, the hydraulically expanded length of tube below the hardroll region may not be in contact with the parent tube during operation.

As this length of tube provides no benefit nor does it deleterious affect the hardroll region, its classification as part of the pressure boundary is inappropriate.

The following summary of the pressure boundary declaration for the parent tube will establish a length below the bottom of the free span hardroll upper transition such that the inherent axial load bearing capability of the joint exceeds the most limiting RG 1.12'I loading; that is, the axial strength of the joint is greater than the worst case applied loads, and therefore, the joint will maintain structural and leakage containment functions.

The proposed amendment request can be summarized as follows:

Any indication existing less than or equal to 1.1 inch (excluding eddy current uncertainty) below the bottom of the hardroll upper transition is unacceptable for continued service.

Circumferentially oriented indications existing greater than 1.1 inch below the bottom of the hardroll upper transition are acceptable for continued service.

The proposed criteria does not address axially oriented indications, only for simplicity reasons, although axially oriented indications in the flat length roll region of the parent tube would not affect the joint integrity or represent a burst potential.

2.

For circumferential indications existing between 1.1 and 1.3 inch below the bottom of the hardroll upper transition, a SLB leakage allowance of 0.033 gpm is applied to any tube determined to be acceptable for continued operation based on the application of the criteria. This allowance is applied regardless of indication depth or angular extent.

Indications greater than 1.3 inch below the bottom of the hardroll upper transition willnot contribute significantly to SLB leakage, and leakage from indications below 1.3 inch below the bottom of the hardroll upper transition would be accounted for based on the conservatism of the 0.033 gpm per indication teak rate value. Total SLB leakage is limited based on current Technical Specification leakage limits established by 10 CFR 100.

If total SLB leakage from all sources exceeds a calculated value found to result in offsite dose bounded by the limits of 10 CFR 100, indications will be removed from service until these limits are satisfied.

As an acceptable alternative, the RCS 1-131 activity can be reduced through Technical Specification limitations.

The proposed criteria can be compared to previously licensed criteria utilizing the same fundamental methodology.

These are the F" and L" criteria.

In the F" criterion, indications

in the tubesheet region provide for tube structural integrity by verification of a non-degraded roll expansion length.

In the proposed HEJ sleeve boundary limits, the same condition is provided by the minimum 1.1" non-degraded length below the bottom of the hardroll upper transition.

In the L" criterion, indications of degraded are permitted within the F" length, however, these indications cannot be circumferentially oriented and must exist a minimum of 1/2 inch from the bottom of the hardroll transition.

Non-degraded roll expanded tube lengths below this degradation is summed with the other non-degraded area above the degradation to ensure structural or axial load bearing capability.

Also, the L" criterion assumes a limiting leakage allowance from each tube which the L" criterion is applied, regardless of the throughwall extent of the indication.

Similarly the proposed criteria for Cook Unit 1 involves a conservative leakage allowance per sleeved tube regardless of the throughwall extent of the indication.

Adding further conservatism, the leak rate for the indication is also controlled by the circumferential angular extent of the indication.

In the proposed criterion for Cook Unit 1, all indications are assumed to extend over 360 degrees of the tube circumference, and exist entirely throughwall, in essence a circumferentially separated tube is assumed for leakage purposes.

Meeting attenders are listed below:

Name Re resentin T. J. Kim J. N, Hannon R. A. Hermann J. R. Jensen S. J. Brewer A. G. Hansen J. F. Williams W. K. Cullen R. F. Keating R. S. Lapides S. Bernhoft K. Toth S. Dembek S. Katradis L. Zerr T. Sutter R. Bennett D. R. Hafer D. H. Malin K. V. Arneson M. Holmberg E. Murphy G. Hornseth J. Donoghue J. Jacobson J. Strosnider NRC/NRR/DRPW NRC/NRR/DRPW NRC/NRR/DE/EMCB AEP AEP NRC/NRR/DRPW Westinghouse Westinghouse Westinghouse Westinghouse WPSC AEP NRC/NRR/DRPE NUS STS Bechtel AEP AEP AEP WEPCO NRC Region III NRC/NRR/DE/EMCB NRC/NRR/DE/EMCB NRC/NRR/DSSA/SRXB NRC Region III NRC/NRR/EMCB The following materials are presentations from this meeting.

Note: Pages 1 through 8 were presented by AEPSC and are not proprietary.

However, they are part of the total presentation which contains Westinghouse proprietary information.

DONALD C. COOK NUCLEAR PLANTUNIT 1 STEAM GENERATOR TUBE REPAIR BOUNDARY FOR PARENT TUBE INDICATIONSIN HEJ SLEEVED TUBES August 10, 1995

2 AGENDA Introduction Overview of Repair Program Kewaunee Sleeve Tube Sample Results S. J. Brewer J. R. Jensen J. F. Williams Sleeve Repair LimitDevelopment R. F. Keating Inspection Program Summary NRC Feedback J. R. Jensen J. R. Jensen

PLANT STATUS - REFUELING OUTAGE SCHEDULE Originally planned to start September 15, 1995 I

Transformer failure moved start date to August ll, 1995 Rescheduled steam generator activities Eddy current starts about August 20, 1995 Tube repair starts about August 29, 1995

MEETING OBJECTIVE Discuss technical basis of Donald C. Cook Nuclear Plant Unit 1 submittal Present HEJ tube sleeve redefined repair boundary limits Present supporting Kewaunee HEJ tube sleeve examination and test results

5 PLANT STATUS Currently 1840 HEJ tube sleeves installed

'G11 - 827 SG12 180 SG13 - 459 SG14-374 Current cumulative level of plugging, 9.6%

SGll 12.8%

SG12 - 9.2%

SG13 - 7.6%

SG14-8.9%

REASONS FOR T/S REQUEST Maintain serviceable HEJ sleeved tubes inservice Continue to maintain SlG plugging levels

Tube Hydraulic Expansion Upper Transition (HEUT)

Hardroll Upper Transition (HRUT)

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I Hardroll Sleeve Hardroll Lower Transition (HRLT)

Bottom of the transition.

Hydraulic Expansion Lower Transition (HELT)

Hydraulic Expansion

Repair Boundary for HEJ Sleeved Tubes HRUT 1.$'elow the bottom ofthe BRUT.

Roll Expansion::

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I Exlstlng repair llmlts apply to the parent tube and the sleeve.

Wq are asking to extend-this much.

Currently up to this point.

Revised repair limitboundary applies to sleeve only.

Repair lfmlts

.:::: apply to the

.

: sleeve &tube.

Examination Summary of the Model 51 Steam Generator Tubes with Hybrid Expansion Joint (HKJ) Sleeves Presented by James F. Williams Westinghouse Science Ec Technology Center Peter J. Kuchirka Westinghouse Nuclear Services Division August 10, 1995

u ose o Examination

~ To veri NDE accurately characterizes the degradation in the HEJ tubes

~ Determine the corrosion environment (primary or secondary side water)

~ Investigate the structural integrity of sleeved tube assembly

XR111111Rt1011 00 e

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Pulled three tubes from a Model 51 S/6

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Performed laboratory NDE - Allsamples

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Eddy current testing (E/C)

~ X-ray radiograpliy

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Laser profilometry

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Performed destructive examination

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Leak testing -

1 sample

~ Tensile testing/microhardness

- 3 free span samples, two HEj

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Fractography '- 2 samples

~ Microstructure - 3 samples for carbides, 2 samples for morphology

~ Chemistry - 2 samples EDS, l sample ESCA/AES/cation/anion

Three tubes received from the Eewaunee Nuclear Power

Plant,

'2C32

~ R2C54

'2C61 Tubes were removed from the hot leg side ofSteam Generator B at Eewaunee to characterize the HEJ which had been installed during 1988.

Tubes/HEJ were cut 3" above the TTS and 3" below the first support plate and were removed from the secondary side ofS/0 to prevent mechanical deformation which could have occurred from a primary side pull.

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~ NDE showed 360'irc'umferential indications in the HRLTfor all three tubes

~ Laboratory eddy current was consistent with field data

~ X-ray radiography confirmed eddy current NDE analysis

~ HEJ dimensions were typical as determined by laser profilometry

15 ummary Tube/

Location R2C32 RZC54 R2C6t Field E/C Plus Point:

300-360'irc Ind in HALT, probably throttghwall I Coil: f994 data only,

-270'irc Ind Plus Point: 360'irc Ind in HALT, probably Ihroughwall I Coil: No data Plus Point: 360'irc lnd in HRLT, probably throu ghwall I Coil: f994 data only,

>270'irc Ind Lab E/C Plus Point: 300-360'irc Ind in HALT, probably

!hroughwall Cecco: 360'irc Ind in HALT, probably throughwall RPC:>270'irc htd at top of HALT Plus Point: 360'irc lnd in HRLT, probably throughwall Cecco: 360'irc Ind in HALT, probably lhroughwall RPC: >270'irc Ind in HALT Plus Point: 360'irc lnd in HALT (probably throughwall)

& small Ind at HELT, Cecco: 360'irc lnd in HALT (probably througltwall) &

small Ind at HELT RPC: >270'irc Ind in HRLT Visual/Dimensional Data HALTstarts 8.25 above botlom of ptllled piece or I I.25 above TTS; HALT ls 0.25'ong; lube HR OD is 0.907" &

HALTgoes 0.009" lower, radially; all values include variabte OD deposits HRLT starts 6.8'bove bottom of pulled piece or 9.85" above Tl'S; HALTis 0.50" long; tube HA OD is 0.903" & HALT goes 0.0t2'ower, radially; all values include variable OD deposils HALTstarls 6.7" above bottom of pulled piece or 9.7 above TIS; HALTis 0.50 long; tube HR OD is 0.905 & HRLT goes 0.009'ower, radially; all values include variable OD deposits Lab X-Ray One to one-and-a-hail semi-continuous Circ networks of short crack Inds at top ol HRLT, observed over at least 270",

possibly over 360'.

Two to three semi-continuous Circ networks of short crack lnds fft mid-to upper portion of I IRLT, observed over 360 One semi-continuous Circ network of shorl crack Inds in mid.portion of HRLT, observed over 360', bul less continuously than for the R2C32 indications.

t.e end of AbbrevlaUons:

HR = Hatd toll HRLT ~ HR fowec translUon HE ~ Hydraulic expansion HELT = HE lower lransiUon Ind ~ Indicalion RPC = Rotating Pancake Coil TTS ~ lop ot tubesheet r

Circ = circumferential

imensiona easurements

~

Hydraulic Expansion area is approximately 1.2" long on all three tubes

~

Radially the HR areas are:

.009" (R2C32)

.012" (R2C54)

.009" (R2C61) beyond the negligibly expanded hydraulic region

~

Lower HR transition is:

R2C32: 0.25" long R2C54: 0.5" long R2C61: 0.5" long>

~

latter tubes have more roll down

==

Conclusion:==

HKJ was typical

~

The tube was cut to 11" with the HR located in the center ofthe tube. The bottom 1" ofthe tube was expanded and welded to seal the sleeve and tube and to force leaks through the HRLT.

~

Leak testing was performed at a number of pressure differentials with the maximum delta of 2534 psi (611F and 618F).

- SLB conditions.

~

==

Conclusion:==

No leaks

ensi e Testin

~ 2 HEJ tubes were tensile tested to failure.

Failure loads were greater than 10,000 lbs with sliding loads > 2800 lbs

~ Microhardness data on free span similar to HEJ parent tube region

~ Results - Failure loads 4 times greater than the specified safety requirements ofdraft RG 1.121

19 ensi e estin ewau ee ee S a

e s'e ata Tube R2C32 R2C54 R2C61 Yteld Strength (psi) 72,200 58,600 55,400 Ultimate Tensile Strength (psi) 123,300 106,700 104,000 Elongation (%)

22.0 24.5 23.1 ewa ee J

e s'e oa ata HEJ Specimen R2C32 R2C54 Fracture Load (Ibs) 10,300 10,700 Fracture Location top of HRLT middle of HRLT Sliding Load over HR Region (Ibs) 2800 decreasing to 50 4000 decreasing to 200 HEJ ~ hydraulic expansion joint HRLT = hard roll lower transition

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Fractography Examination Summary

~ Fracture face indicated no throughwall cracking. Cracking ranged from 5 to 92 70 throughwall with a 60'ro average

~ No leaks could have occurred through HRLT indication

~ Results - ID originated corrosion

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23 Destructive Examination Results Macrocrack Profiles for Tensile Fractures

Tube, I.ocation

R2CS4, IIRI.T Length vs. Depth and Ductile Ligament Location (degrees/%throughwall)

<--Ligaments l7 & 18

<--Ligaments l4, I5 & I6 4S/7 S 68/84 (80/92)<-Maximum depth 90/78 Ligament 13 I 12/82

<--Ligament I2

<--Ligaments IO & I I

<--l.igament 9

<--Ligament 8

<Ligament 7 248/48<

270/64 292/78 3ISn <--Ligaments 2, 3 &. 4

<--Ligaments I & l9 (Average Macrocrack dcptli = 60% over

'aximum (lepth wns 92%'I Ductile Ligament Width (inches)

LI7 & LI8 are O.OI5" & 0.005" wide LI4, l.l5 & l.l6;ire O.l)03". 0.(X)8" &

0.007" wide, I.I3 (s O.OI7" w<<le l.l2 is 0.009" wide LIO & LI I are 0.017" & 0.005" wide I 9 is O.OI I" wide l.8 is 0.050" wi(le l.7 is 0.002" wide L5 & I.6 are 0.009" & 0.007" wide L2, L3 & L4 are 0.008", 0.0!3" & O.OI3" wide LI &, bl9 a'e O.OI3" & 0.044" wide Comments Nineteen ductile llg(llnctlls were (ihserved (in lite circu((tfe(cot i;il macrocr;(ck l(ic (ted in llic ()tiddle (if the ltar(I I'oil I(iwet transilioti (IIRI:I).

All intcrgr;(nul;ir c(irr(isi(in was ot'l) origiti.

24 emistry

'oron and Lithium on ID of crack

'r enrichment was not found on fracture face or on ID below fracture face.

Low levels of Zn, Na, Mg, Si, Zr, N, S along with the expected C, 0, Ni, Cr, and Fe were found

~ Result - implies PWSCC

emistry -ED - IUC54 Summary Table of EDS Results for Kewaunee Tube R2 C54

- lD l)eposits-ELEMENT(weight percent)

Location HELT 0

Aj S

21.5 0.5 Cr 19.5 14.8 Ni 43.2 Si HELT/HRLT HRLT/FF 21.6 22.0 0.03 19.0 17.6 12.1 47.8 13.2

~ 45.9 0.2 0.5 HR 21.7 1.3 0.3 0.3 23.0 20.7 32.2 0.5 HRUT/HEUT 16.7 2.4 0.7 0.4

. 20.6 18.5 40.2 0.4 just above HEUT 12.6 0.8 0.4 0.3 17.0 I 1.0 56.8 0.6 0.6 s

t1ofabove s ot 2 ofabove to ofHEJ 0.2 9.7 0.1 1.0 0.7 16.9 5.3 1.5 1.8 0.4 19.8 0.2 20..7 0.3 16.0 13.8 7.3 19.3 55.5 65.7

41. I I).5 0.5 0.5 0.2 0.2 l).2 0.5" above top ofHEJ 12.7 0.7 0.4 18.9 11.0 55.4 0.3 Summary 'Fable of EDS Results for Kewaunee Tube R2 C54

- OD Deposits-ELEMENT(wei ht ercent)

Location FF/HRLT HELT/HRLT HRI.T/FF 0

19.7 24.8 16.3 0.3 0.5 1.9 Cr Fe 0.2 14.6 19.0 0.3 21.2 15.0 12.2 13.1 42.9 35.2 48.7 Si 0.4 0.6 0.2 P

1.2 2.4 I.7 3.8 Zn Cu 0.8 2.1

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27 Chemistry - Capillary Electrophoresis-Cations - R2C32 Cation Potassium Calcium Sodium Magnesium Lithium Concentration in Leachate (mg/I) 0.2I 0.2 I 0.97 0.25 0.10 Estimated Crevice Concentration (mg/I) 2I 97 25 IO

28 Chemistry - Ion Chromatography-Anions - R2C32 Anion Form ate Acetate Chloride Unknown Carbonate Nitrate Sulfite Sulfate Oxalate Concentration in Leachate (mg/I) 0.7 0.3 0.028 trace trace trace O. I l.7l 0.05 Estimated Crevice Concentration (mg/I) 70 30 28 IO l7l

29 chemistry - AE i?34 5

Intergranular SCC Crack Face AES Profile Locations

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icrostructure

~ Moderate number ofcarbides on R2C32, and a few carbides on R2C54 and R2C61

~ Carbides are distributed transgranularly

~ Results - This microstructure is consistent with tubing susceptible to PWSCC

33 ODC US10nS

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NDE results are consistent with destructive examination

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The cracks are on the ID ofthe parent tube,'60", 5 to 92'lo throughwall, with average depth of 60'/o

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Microcracks with simple corrosion morphology indicative ofPWSCC were found

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8 and Li deposits on ID of crack implies PWSCC

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Tensile properties well above safety limits ofdraft RG 1.121

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No cracks except in the HRLT - circumferential only

34 AEP / NRC Meeting Rockville, MD August 10, 1995 DEVELOPMENT OF THE REPAIR BOUNDARY FOR PARENT TUBE INDICATIONS IN HEJ SLEEVED TUBES R. F. Keating Nuclear Services Division westinghouse Electric Corp.

35 Objective Present a Repair Boundary for parent tube indications (PTIs) in HEJ sleeved tubes that:

1.

Meets the structural requirements of RG 1.121 during normal and accident conditions, and, 2.

Restricts leakage such that the dose requirements of 10 CFR 100 are met, without relying on limitations on crack size or determination of crack growth rates.

36

~ Paasmmamow Cowrzxr o Background 0 Field Experiences o

Repair Boundary Criteria 0 Structural Repair Boundary 0

Geometric Constraint Repair Boundary 0

Conclusions

0 BamGROUm 37 0 Parent tube indications (PTIs) first observed at Kewaunee in the Spring of 1994 o Structural acceptance criteria developed and presented to NRC in April, 1994.

i Sleeved tubes with HEJ PTIs removed from service o Development ofjusti6cation for a revised repair criteria continued through October of 1994 0 License amendment sought by %EP for Point Beach 2 in the Fall of 1994 Amendment not approved, and SER issued in January, 1995 o WPS/NRC meeting in February to clarify concerns exp'ressed in the Point Beach 2 SER

~ Intent was to identify key issues to be addressed for development of criteria for Kewaunee

38 Installed HEJ Sleeve Configuration Upper Hydraulic Expansion Upper Hardroll Parent Tube ~

~ Sleeve Tubesheet

',:,"="'-~;.';z ~

Lower Hydraulic Expansion

?.

".: Lower Hardroll Gladding

0 FIELD ExPERIENcEs 39 o PTIs were detected at Kewaunee in 1994 and 1995, at Point Beach 2 in 1994, and at Doel 4 in 1994 and 1995.

o Almost 98% of the indications have been found in the lower transitions.

Distribution ofAilCircumferential PTIs by Transition Hardroll Upper Transition Hydraulic Expansion Upper Transition Hydraulic Expansion Lower Transition Hardroll Lower Transition BHELT=37.2%

BHRLT=60.5%

ClHRUT= 0.7 %

OHEUT = 1.6%

~ FIELD EXPIKIENCES (Cont.)

40 Distribution of HEJ PTIs b

Transition HEJ Tran.

HELT HRLT HRUT HEUT Totals 212 480 0

698

%EP 2 134 88 230 KCD 4 0

0 Totals 349 568 15 939 37.2 60.5 0.7 1.6 Axials Vol 10 0

0 0

0 10 Totals 710 230 11 951

~ FIELD EXPERIENCES (Cont.)

41 o And where are those indications relative to the hardroll upper transition~

130 120 110 Kewaunee SGs "A"A"B"HEJ PTIs vs.

Distance Below the Bottom ofthe HR Upper Transition 100%

90%

100 a

90 O>

So 70 o

60 50 40 30 20 10 RG 1.121 Repair Limit EZRABoth SG Indications

Both SG Cumulative 85O/a Rank Cumulative 80%

'4 qp 60%

5P%

C4 40%

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20%

10%

0%

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M cp cD rE Upper Bin Distance Below Bottom,ofHR Upper Transition

~ Why is Doel 4 different?

o The plant runs at a significantly higher temperature.

o Tubing is more susceptible to PWSCC than at Cook, Kewaunee, or Point Beach.

0 Presence of a 6" crevice above the hydraulic expansion.

o Cracking above the hardroll is occurring before significant weepage past the joint leads to a corrosive crevice environment below the hardroll.

~ What about Kewaunee and Point Beach 2?

o Cracking is due to weepage past the hardroll to a region of high residual stress.

o Very short sleeve/tube crevice above the hardroll and hydraulic expansions.

o Expect the distribution of indications by transition to be unchanged.

0 Negligible operating leakage after 7 to 14 years of operating with HEJs.

43

~ OVERALLOBSERVATIONS FROM THE FIELD EXPERIENCES The formation of PTIs in tubes in U.S. plants is strongly biased to the lower transitions.

a 98.5', or 916 of -930 indications.

o There is no evidence to support the "Bad Tube" hypothesis, i.e., PTIs at lower transitions do not imply PTIs at the upper transitions.

a The number of tubes with PTIs at multiple elevations is < 1% of the total tubes affected.

1 at Kewaunee and 7 at Point Beach 2.

(None of those reported at Doel 4.)

The number of tubes with FFIs at lower and upper transitions is ZERO.

~ NO CRACKS were found at the upper transitions of the two destructively examined Kewaunee HEJs.

44

~ RECALL TEA NDE OF THE KEWAUNEE SPECIIViKIMS.

o Up to 360 PTIs in the HRLTs were indicated by the field and laboratory NDEs.

~ Average depth of 60% and maximum depth of 92%.

No PTIs were indicated at the HRUT and the HEUT by the field and laboratory NDEs.

a No cracks were found, even after loading the tube sections to over 10,000 lbs.

~ 'I'HE QVERALLCONCLUSION The Repair Boundary for PTIs in the lower transitions can be established independent of con-sideration of PTIs in the upper transitions.

0 SOME ImoRvramow ow DoEI, 4 Ten tubes were removed for destructive examination.

o HEJ indications were confirmed.

o NDD locations did not exhibit cracks.

~ REPAliR BOUlmARV 46 o Meet the requirements of RG 1.121, 10 CFR 100, and provide defense in depth.

o Address prior NRC concerns (2L1I95 meeting)

~ Not enough cracked tube data I experience reLative to inspection of the parent tube.

~ Level ofdetection ofupperjoint cracks, that is the "Bad Tube" syndrome.

~ The field experiences and pulled tube destructive examinations should dispell these concerns.

Incubation time and crack growth rates.

o Prior amendments (for other plants) sought to apply a criteria to detected indications relative to size and growth.

The repair boundary developed here does not!

47

~ STRUCTURAL REPAIR BOUNDARY o Axial load resistance to meet RG 1.121 1.43

~ APsL~

= 1727 1bs 3

Atop

= 2264 lbs Governs 0

Based on maximum approved AP of 1600 psi for D. C. Cook.

o RG 1.121 Axial load capability demonstrated by test.

48 Location of Cut Results of HEJ Tensile Tests Force (Ibs)

Ratio to NOp 1.1" below the bottom of the HRVT (600) 1.2.to 1.25" below the bottom of the HRUT (690) 2.25" below the bottom of the HRUT (690) 3240 to 4800 4100 5475 7850 to 8250 4.5 to 6.4 5.4 7.3 10.4 to 10.9

49 Pulled Tube Tensile Test Results Location of Crack Top of the HRLT (690) 1.2" below the bottom of the HRUT (690)

Ligament Overload Force (1bs) 10,350 10,700 Friction Force After Fracture (1bs)

Ratio to NOp 3.7 5.3

-1.0 to 1.03" below the bottom of the HRUT 4630 to 5500 3600 to 4800 4.8 to 6.4

50 The RG 1.121 Repair Boundary for the HEJ.

Repair Boundary for HEJ Sleeved Tubes HRUT Existing repair llmlts apply to the parent tube and the sleeve.

1.1" below the bottom of the HRUT.

Revised repair limitboundary applies to sleeve only.

RollExpansion,:"';.'epair limits

,":,.;,'pply to the

-,, sleeve &tube.

61 0 ANALVnCSCOPING CHECK OF 'ITIVE RESULTS Frictional resistance of the 0.1" length assuming the lip to be approximately at yield, conservatively 50 ksi.

a Radial force = 1570 lbs Frictional resistance of the 1" hardroll length assuming a radial interference of 1/2 mil.

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~ NOp Radial force = [

]a,c

]a,c o

Assume a coefficient of friction of [

]'" as between the handbook value of 0.2 for a greased interface and the value calculated from F* testing of [

]".

Compare resistance force, FR, to end cap load, Fc.

SLB FR / Fc = 2.4 NOp FR/Fc = 3 o Using a coefficient of [

]"'esults in values of 3.6 and 5.3, respectively, which are closer to the values obtained from the test programs.

CONCLUSION RG 1. 121 requirements are met.

STRUC'IXHKALREPAIR BOUNDARY (Cont.) s2 HEJ Leak Rates Sleeve Material Alloy 690<'~

Alloy 690

'lloy 690~'>

Alloy 690<'>

Alloy 690 Alloy 690 Alloy 600 Alloy 600 Alloy 690 Alloy 690 Alloy 690 Alloy 690 Cut Angle

(')

240 240 240 240

. 360 360 360 360 360 360 360 360 Inches from HRUT GPM at 2560 psi

~ The average leak rate from the tests was 0.004 gpm with a standard deviation of 0.007 gpm.

Assuming a Log-Normal distribution, a 95% confidence bound on the leak rate is [

]"'pm.

(1):

The leak rates for these. specimens was conservatively adjusted by a factor of 1.5 to represent a postulated 360'rack simulation.

53

~ GEOMETRIC CONSTRAINT REPAIR BOUWOARV Defense In Depth.

What ifthere was a tube that did not have sufficient residual strength?

o The geometric constraint afforded by neighboring tubes, willprevent a separation of the parent tube from the sleeve.

o The leak rate from the parent tube would be significantly restricted by the sleeve/tube annulus.

o Geometric constraint is conservatively assumed to be governed by the tangent point clearance.

~

Some location between the tangent point and the apex should actually control displacement.

~

Assumed that the tube is free to slide (ignores any friction at the TSPS).

54

~ Tangent Point Clearance The distance a severed tube could rise before contacting an outboard neighbor.

Tangent point clearance is calculated from the U-Bend apex clearance values which result from the SG manufacturing tolerance stackup.

~ U-Bend Clearance o

The clearance is nominally 0.406"

0 U-Bend Apex Clearances 0 Average of [

]

a,c 0 Tangent Point Clearances o Average of [

~ Margin to the Repair Boundary 0

Expected values of:

[

0 95% confidence on the displacement:

@ NOp is less than the Repair Boundary, SLB is equal to the Repair Boundary.

~ CONCLUSIONS o

The "Bad Tube" syndrome is not supported by field data.

0 Eddy current technology, the CECCO probe, has reliably detected PTIs in HEJ sleeved tubes.

0 The tube material below 1.1" from the bottom of the BRUT is not necessary:

+ The remaining joint strength meets the requirements of RG 1.121.

< Demonstrated by testing of surrogate and removed tube specimens.

o Check calculation yields similar results.

~ The remaining joint leak resistance affords significant margin relative to the allowable 10 CFR 100 dose.

~ The Repair Boundary is backed up by geometric constraints (defense in depth).

A Repair Boundary of 1.1" below the bottom of the HRUT is justified.

~ INSPECTION PROGRAM The NDE program for the next outage willinclude 100% inspection of all HEJ sleeved tubes using the Cecco-5 probe with location characterization using the 3'coil RPC.

o Cecco-5 has been qualified to EPRI Appendix H guidelines and is consistent with industry practice.

~ Qualification testing indicates 100/o detection of circumferential and axial flaws ~50% deep a

Cecco-5 can be used for location characterization also, but additional testing would be required to establish consistent capabilities as 3-coil for location characterization o 3-coil RPC used only for location determination of flaws with regard to bottom of hardroll upper transition a

0.080" coil diameter of 3-coil RPC probe should be less sensitive to geometric discontinuities of hardroll than other surface riding probes Uncertainty of 0.06" is applied to the 3-coil RPC inspection

58

~ APPLICATION OF THE BOUNDARYLEAKAGE For tubes with postulated 360'hroughwall degradation located ) 1.1 inch but

~ 1.3 inch below the bottom of the hardroll upper transition; o A bounding SLB leakage allowance of 0.033 gpm per tube willbe applied.

0 This allowance applies to all tubes left in service by application of the redefined tube repair boundary.

o Established by applying a safety factor of 2 to the largest test result for severance -1.12" below the bottom of the BRUT.

o Faulted loop leakage limitof 12.6 gpm willconsider both HEJ and IPC tubes.

"Across the board" allowance is conservative.