ML20070Q512

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Rev 1 to Evaluation of Indications in Perry Feedwater Nozzle-to-Safe-End Welds, Summary Technical Rept
ML20070Q512
Person / Time
Site: Perry FirstEnergy icon.png
Issue date: 03/07/1991
From:
CENTERIOR ENERGY
To:
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ML20070Q509 List:
References
NUDOCS 9103290102
Download: ML20070Q512 (9)
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Attachment PY-CEI/NRR-1337L Page 1 of 9

SUMMARY

TECHNICAL _ REPORT EVALUATION OF THE INDICATION (S) IN THE PERRY FEEDWATE NOZZLE TO SAFE-END WEE S Revision 0:

November 21, 1990 Revision 1:

March 7, 1991 Cleveland Electric Illuminating Company 3/7[f/

Prepared by:

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Attachment PY-CEI/NRR-1337L Page 2 ABSTRACT As part of Perry's Inservice Inspection (ISI) Program, all six Feed-water (TW) nozzle to safe-end welds were ultrasonically examined (UT) during the second refuel outage (RFO-2).

Flaws were detected in nozzles N4E and N4C that were outside of the acceptance criteria of IWB 3514.3 of ASME XI ( ref erence Nonconf ormance Repor'es #90-S-270 and

  1. 90-S-277 dated November 9, 1990 and November 13, 1990, respectively).

Both flaws were 0.15" deep, with the flaw in nozzle N4C being 2.9" long, versus 1.6" long for nozzle N4E.

Since both flaws are the same depth, and very nearly the same location (although one was oriented 9 6:00 O' Clock and the other 912:00 0' Clock - see Figure

  1. 1), justification for the larger flaw will serve ac technical justification for both.

The UT indications were not identifiable as characteristic of IGSCC.

However, the current limited size of the indications may be such that IGSCC characteristics would not be sufficiently pronounced to be apparent.

Consequently CEI has taken a conservative approach and included an appropriate SSCC contribution in conjunction with cyclic fatigue growth when determining the " final" flaw size.

The final flaw size is fully acceptable within the criteria of ASME XI, Table IWB-3641-5 for the full duration of operating Cycle 3 fer-Perry (nominal 14 month cycle).

The subject nozzles will be UT re-inspected during Refueling outage 43 (RFO-3) and further engineering evaluation will be performed at that time.

The results of the evaluation at RFO-i will determine subsequent appropriate actions.

4 Attachment PY-CEI/NRR-1337L Page 3 STRESS HISTORY The safe end of the feedwater nozzle was covered by two analyses -

CBIN Stress Report No. 4 and GE Feedwater Piping Analysis Report No.

23A5784 R/0.

Revision 0 of this flaw evaluation used the CBIN stress input, but it was subsequently determined that the Piping Analysis Report was more representative and appropriate.

Revision 1 of this flaw evaluation therefore addresses the IGSCC : rack growth portion of the analysis

'<y esing GE pipe loads for the 14 months of normal operation expected for Cycle 3.

These loads include the axial, benC:ng and expansion effects on the safe end The same residual stress as used in the Revision 0 report was added to the operating stress profile.

The value of residual stress uJded was a function of percentage of crack depth (a/>.i.

The residual stress profile used was taken from NUREG 0313/P.evision 2 with a suggested value for Sy of 30 KSI; which closely approximates the value for Inconel 182 of 28.4 KSI at temperature.

The crack growth due to fatigue was a small contributor (6 a

.01")

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to the final crack size.

Also, it would not be significantly altered by re-evaluation, so fatigue was not addressed in Revision 1 except to conservatively include the da=.01 growth.

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Attachment PY-CE7/NRR-1337L Page 4 CRACK GROWTH The initial crack of 0.15" deep x 2.9" long was projected to grow for 1148 operating cycles, assuming worst case cycle combination to determine " Delta" K From Figure C-3210-1 of ASME XI, the projected 7

cyclic fatigue growth increased the flaw depth to only 0.16".

The growth attributed to the IGSCC contribution for the 10,000 operational hours during operating cycle 3 is 0.3".

This is based on a crack growth rate of 3.0 x 10-5 in/hr, which came from EPRI RP 1930-1,. Amendment 22, "GE Nuclear Energy Alloy 182 SCC Test Results Final Report".

The IGSCC crack growth rate is dependent on K per EPRI RP 1930-1 y

and K varies through the safe end wall thickness as an "S" profile 7

(Figure 2).

The K is determined by the-method developed by C.

B.

7 Buchalet'and W.

H.

Bamford, " Stress Intensity Factor Solutions for Continuous Surfac' Flaws in Reactor Pressure Vessels", ASTM STP 590 1976.

Conservatively, the maximum K

- 21.24 KSIs/IN in the path of 7

the crack growth was used-to' determine the growth race of 3 x 10-5 in/hr f rom EPRI IU) 19 30-1 f or t:

entire length of Cycle 3 eperation.

4 This results in crack growth of 0.30" or a total depth of.0.46"

. including initial crack size and fatigue growth for Cycle 3 (Figure

'3),

Concurrently with the cra:k grcwth in depth, the circumferential

. growth resulted in a length of 9.2".

This growth circumferential1y is based on a NUREG 0313 Revision 2 ratio of circumferential length / depth equal to 20:1.

The contribution of emergency or faulted conditions on the crack growth produced a negligible effect on the final projected crack depth.

Attachment PY-CEI/NRR-1337L Page 5 ACCEPTANCE CRITERIA Although the flaw location is at or close to the Inconel 182 butter-ing and the SA-500 Class 1 interface, it was assumed (as dictated by ASME XI) that the crack growth'would occur in the buttering.

Tn'e buttering was applied by using SMAW procedures; consequently Table IWB-3641-5 is the basis of the acceptance criteria (Table.IWB-3641-6 does not contribute to the limiting acceptance criteria since the contribut!.on of emergency-or faulted conditions produced a negligible effect on the final projected crack depth).

Figure 3 shows the a< 'eptance envelopes based on a stress ratio of 0.43.

This value is based on GE piping loads applied at the feedwater nozzle safe end and considers the. combination of Primary Membrane Stress (Pm), Priuary Bending Stress (Pb) and Expansion Stress (Pe) equal to 10.1 KSI for the applied strecs in the stress ratio term of Section XI, Table IWB 3641-5.

Figure 3-illustrates the large margin from final fAaw size a

- C.46" to the acceptance envelope

_The maximum crack growth rate per EPkI RP 1930-1, Amendment 22 is approximately 4.7 X 10-5 at K

- - 4 0 K S Ig/IN ; -

7 which)is well beyond CEI's conditions.

Hypotheticallyi if K were to 7

attain a value:of'40: KS Is[TN, Figure 3 indicates there would still be substantial safety margin for Cycle 3 operation.

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Attachment PY-CEI/NRR-1337L Page 6 CONCLUSIONS 1.

The subject indications have been evaluated and shown to be acceptable as-is for continued full service operation during Perry's next operating cycle (Cycle #3).

2.

Subsequent to UT inspection of the subject welds during RFO-3, an engineering evaluation. will-be performed to determine subsequent corrective actions (if any).

3.-

The= subject nozzle welds will be treated as Category "r" weld-ments per Generic Letter 88-01/ Revision 0, Table 1 until such time as further inspection / evaluation justifies otherwise, i

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