ML20138R071
| ML20138R071 | |
| Person / Time | |
|---|---|
| Site: | Peach Bottom  |
| Issue date: | 11/15/1985 |
| From: | Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Stolz J Office of Nuclear Reactor Regulation |
| References | |
| GL-84-11, NUDOCS 8511180420 | |
| Download: ML20138R071 (12) | |
Text
_ __ _________ __ __ __ __ _--_ _ __ _ _ _ _ _
1 l
l PHILADELPHIA ELECTRIC COMPANY J
2301 MARKET STREET l
f P.O. BOX 8699 PHILADELPHIA. PA.19101 SHitLDS L. O A LT ftOP f'
.6J71,0*a's.,
November 15, 1985
[
Docket No. 50-278 i
Mr. John F.
Stolz, Chief Operating Reactors Branch #4 Division of Licensing l
U.S. Nuclear Regulatory Commission 4
Washington, D.C.
20555 6
SUBJECT:
Peach Bottom Atomic Power Station, Unit 3 Recirculation System Welds 2-AS-8 and 2-DD-12
REFERENCE:
(1)
Letter, S. L. Daltroff, PEco, to J. F. Stolz, USNRC, dated December 15, 1984 j
l
Dear Mr. Stolz:
This letter transmits the results of an evaluation prepared i
i for Peach Bottom Unit 3 Recirculation System Welds 2-AS-8 (pipe-to-suction valve weld on the
'A' recirculation line) and 2-BD-12 (pipe-l to-discharge valve weld on the 'B' recirculation line).
The attached evaluation, which was prepared by General Electric Company, e
demonstrates that the crack indications discovered in these welds satisfy the acceptance criteria of Generic Letter 84-11 and ASME Code Section XI, although the indications do exceed 30%
l circumference and fall into the category where " repair is likely to be required", as stated in item 3 of Attachment 2 of Generic Letter 84-11.
All other butt welds in this category have been overlay repaired.
The evaluation also concluden that continued operation for a minimum of 18 months without weld repairs is justified.
i Performance of weld overlay repairs has been considered for the subject welds.
These pipe welds are located in the drywell and it has been determined that' considerable interference exists in the
.l areas of both welds.
Several small pipes, hanger lugs, drain lines, pieces of grating, and a decontamination flange would have to be cut l
out and later reinstalled to provide spnce for the welding equipment.
Removal and reinstallation of theso itemn would add significantly to the radiation exposure and the time required to I
perform the overlay repairs and would also result in outage l
0511180420 b115
'h
$DR ADOCM 270 PDR
I t
Mr. John F. Stolz November 15, 1985 Page 2 I
i t
extension.
This information is summarized in the following tables i
2-AS-R 2-BD-12 Typical 28" Weld i
l 1
i Exposure (Man-Rom) 70 82 20 i
j Repair Time (Days) 19 24 14 l
i i
In accordance with item 2(a) of Attachment 2 of Generic Letter 84-11, prior NRC approval of the attached analysis is required to return Unit 3 to power operation.
The current Unit 3 refueling outage is scheduled for completion in December, 1985 I
therefore, prompt attention to this matter would be appreciated.
l If we can provide any additional information, piense do not j
hesitate to contact un.
Very truly yours, AA
~~
i i
Attachment cc Dr. T. E. Murley, Administrator, Region I, USNRC f
T. P. Johnson, Resident Site Inspector J
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(
GENER AL $ ELECTRIC NUCLEAR sERVicts OPERATIONS GENERAL ELECTRIC COMPANY
- 1000 flRsi AVENUE
- KING OF PRusslA, PENNSYLVANIA 19406 G-HE-5-572 November 13, 1985 K. J. Wilson PHILADELPHIA ELECTRIC COMPANY 2610 South Delaware Avenue Philadelphia, PA 19142
SUBJECT:
Peach 00ttom 3 IGSCC Contingency Program Flaw Evaluation - Welds 2-AS-8 and 2-B0-12 This letter summarizes the results of the flaw evaluations performed for the Peach Bottom Unit 3 Recirculation Line Welds 2-AS-8 and 2-80-12.
The evaluation demonstrates compliance with the requirements of Generic Letter 84-11, as well as the newly developed acceptance criteria for flux wold-ments which has been proposed for ASME Code Section XI in lable IWB-3641-5 and is currently on review.
The results show that the flaws are acceptable for at 1 cast 18 months of operation.
Method Crack growth analyses were performed to determine the depth of the cracks after 18 months of operation.
This analysis involved the calculation of a stress intensity factor and crack growth rate.
The stress intensity fac-tors were calculated using the polynomial fit method developed by Duchalet and Damford (Reference 1).
Crack growth was determined using the u bound weld sensitized crack growth data shown in Figure 1 (Reference 2)pper Assumptions A summary of the composite crack indication sizing performed independently by GE and Southwest Research Institute (SWRI) is shown in Table 1.
The crack lengths were conservatively assumed to be equal to the sum of the individual lengths and the depth equal to the average depth.
The evalua-tions were performed using the average flaw depth, since the measured depths were highly localized peaks (or cusps) at separate locations.
We believe that these averages represent a reasonable flaw assumption for these wolds.
K. J. Wilson November 13, 1985 Stresses The applied stresses are typical of the stresses in other welds in this line.
These stresses consist of the original design stresses (pressure, thermal expansion, dead weight) and shrinkage stress, as shown in Table 2.
This stress is due to axial shrinkage of the weld overlays in the loop.
For this analysis, upper bound shrinkage stresses are used based on piping system finite element modeling results.
In addition, one of the following two residual stress distribution assump-tions were applied:
2-BD-12 Large diameter pipe weld residual stress, as shown in Figure 2, ap-slies to this joint since it has not been treated with Induction
>1cating Stress Improvement (!HSI).
2-AS-8 This weld was IHS! treated in 1983. The plasticity that occurs during this treatment will tend to neutralize existing as-welded stress dis-tributions.
Therefore, this analysis conservatively assumes no resid-ual stress, but does not take credit for the beneficial IHS! residual strcsses.
Using these stresses, a crack growth evaluation was performed for each in-d dication and compared to the following criteria.
Criteria The first criterion is that the crack should not exceed the limit for net section collapse using a safety factor of 3.0.
The second criterion is that the crack should not exceed 2/3 of the limits for depth and length provided in the ASME Code Section XI, Paragraph IWD-3640.
The last criterion is that the crack should not exceed the limit on allow-able flaw size for flux weldments.
This criterion is proposed for ASMC Code Section XI in Table IWD-3641-5.
(This criterion is currently on review within the Section XI Committee.)
i Results The predicted crack growth and the allowabic flaw size for both wolds are shown in Figures 3 and 4.
Considering the average depth, it is seen that there is a significant margin for both welds, in fact, even with a con-servative assumption of peak depth, operation without repair can be justi-fled for 18 months.
Thus, based on the evaluations, operation as is is acceptable for each of these joints.
r-K. J. Wilson November 13, 1985 l
As defined in the three criteria, the analyses demonstrate compliance with l
the requirements of the NRC Generic Letter 84-11, as well as the newly dev-eloped acceptable criteria for flux weldments.
l Sincerely, R. L. Lebre Program Manager l
l l
,o 4809252790
- 31. 4.1985 10:31 p,
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FURNACE SENSITIZED (0.2 ppra'0 I' 2
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TABLE 1 CRACE IMICATICE SIZWC F.*3 '
TYPE LOC &TICE AIDW1R DEFTE RDIAEES 2-AS-8 SS Elbour 11bour 0-4*
20Z Cast SS Valve 18-40" 201 local Cuer of 40E 2
(USI. Treated) assumed lamath = I inch 54-58" 20Z Local Caer o' 35Z assumed length = 1 inch 74-78"
, 201 38-90" 2tE ATC. 111 2-D-12 SS Fire Pipe 3-11" 20%
Local Camp of 301 Cast SS Yalve assumed length = 1 inch l-(not IE51 Treated) 16-17"25-301 22-25" 201 l
35-4L" 3Z
~
46-60" 20-25%
3 63-68"
~ 20Z Local Casp of 30%
assumed length = 1 inck
=
74-41" 20Z l
1 ATC. 21Z l
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w TABLE 2 RECTerzr2TICE FIPMG WEIB STREssIS l
1 d
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N FIFE FREss M Tummmaf-DEAD-SEISMIC nuanrEACE b
nasr.
snE saII. n IcxEass stanss Ezrass.
uEicEr (ast) snEss l
(im.)
(ie.)
(ksi)
(ksi)
(ksi)
(ksi)
(kai)
- 3..
l 2-As-08 28 1.138 6.46 1.00 0.43 1.28 2.0 1
l 2-B3-12 28 1.138 S.00 0.71 0.27 0.77 1.0 e*
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u H
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4889252798
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- 11. 4.1985 18833 P.
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0.25
- 9.9 o.39 - 14.2 20 l
0.50 - 12.0 o.s1 0,
1.00
+ a.1 k
10
+at s,
n 0.2 as 0.8 02 W
0
. g att
-10
=14.2
-20 ID OD suse Figure 2.Large Diameter Pipe Axial WeldResidualstress Distribution (22 in. to 28 in.)
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- 11. 4.1985 18834 P.
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l 0.9 IWB-3642 2/3 CODE ALLOWABLE GENERIC LETTER 8411 EQUlMEMENT N
0.7 I
PROPOSED CODE f
0.6 CRITERIA FOR g
gFLUX WELDS 05
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E o.4 jL CRACKOROWTH AFTER 18 MONTHS OF OPERATION 03-WITH LARGE DIAMETER PIPE
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WELD RESIDUAL STRESS 21'46 INITIAL FLAW DEPTH 0
02 0.1 I
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0.0 0.1 0.2 03 0.4 05 0.6 0.7 CA 0.9 1D NON-DIMENSIONAL LENGTH - LI(2* r*R)
+
sw4 Figure 3.
Flaw Acceptance Diagram for Weld 2 8042 Large Diameter Pipe Wold Residual Stress Assuming Average Flaw Depth 1
4889252798
- 11. 4.1985 18:34 p,
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op IWB.3642 ALLOWABLE 2/3 CODE ALLOWABLE w
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- - = = = =.
FLUX WELDS 05 0.4 03 CRACK GROWTH IN 18 MONTHS OF OPERATION O2 II NO CREDIT FOR IMSI 21% INITIAL FLAW DEPTH 0.1 1
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04 0.1 0.2 03 0.4 03 04 0.7 03 Os 10 NON-DIMENSIONAL LENGTH - Li(2* =*R) sWMO Figure 4. Flaw Acceptar.:e Diagram for Weld 2AS B No Credit !ct sHSI Assumlng Average Flaw Depth
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4889252798
.FROM
- 11. 4.1985 18835 P.18 REFERENCES 1.
C. B. Buchalet and W. H. Bamford, " Stress Intensity Factor Solution for Continuous surface Flaws in Reactor Pressure Vessels "
Hechanics of Crack Growth, ASTM STP 590, 1979.
2.
R. M. Horn and S. Ranganath, " Determination of Crack Crowth Rates in Sensitized Austenitic Piping," Proceedinga:
Second Seminar on Countermeasures for Pipe Cracking in BWRs, Volume 1: Problem Resolution, EPRI, Palo Alto, CA. (EPRI NP-3684-SR),
September, 1984, pp.10-111 through 10-12.
s O
e S
4 h
.