ML20235J029
| ML20235J029 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 06/17/1987 |
| From: | Chiang Y BECHTEL GROUP, INC. |
| To: | |
| Shared Package | |
| ML20235J026 | List: |
| References | |
| NUDOCS 8707150371 | |
| Download: ML20235J029 (10) | |
Text
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EVALUATION OF WELDED ATTACHMENTS 4
ON l
CLASS 2 & 3 PIPING i
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l PREPARED FOR SOUTH TEXAS PROJECT i
l BY BECHTEL ENERGY CORPORATION
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PLANT DESIGN STRESS GROUP JUNE 17,1987 l
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,l PREPARED BY M]
CHECKED BY APPROVED BY h /
(
1 8707150371 870700 ADOCK0500g8 DR 4619s/0133s
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ABSTRACT Detailed stress analyses using methods presented in ASME code cases N-122 and N-391 were performed to' ensure that the requirements of NC/ND-3645'were met for the five integral pipe attachments chosen in Reference 6.
f All results indicate compliance with the requirements of ASME III subsection NC/ND-3645.
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5 II.
INTRODUCTION
-l The NRC in Reference 1 requested additional information regarding the use' of welded pipe attachments on piping where arbitrary intermediate breaks had.been eliminated. ~In response to this letter and subsequent discussions', STP '
committed in Reference 5 to perfom an enveloping evaluation of all such
. welded attachments. This evaluation was to include consideration of the' i
fatigue effects for Class 2 and 3 piping in.accordance with paragraph NC/ND-3645 of the ASME Section'III Code (STP does not have welded attachments on Class'1 piping.) An interim report on the results of this evaluation was I
forwarded previously (Reference 6)..
NC/ND-3645 states " External and internal attachments to piping shall be designed'so as.not to cause flattening of the pipe, excessive localized bending stresses, or harmful thermal gradients in the pipe wall..."
Localized pipe stresses due to welded attachments are evaluated and qualified in euch individual support design.
In this final report, the emphasis for this study was placed on the requirement that a welded attachment must not cause " harmful thermal gradients in the pipe wall".
Since NC/ND-3600 does not l
provide guidance for evaluation' of thermal gradient stresses, the rules of.
NB-3600 were used to perform the analysis, i
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e III.
SCOPE OF WORK All supports on high energy Class 2 and 3 piping were reviewed, and those with welded attachments were. identified.
The total of 55 supports identified encompass the following piping systems:
Main Steam Steam Generator Blowdown Feedwater Auxiliary Feedwater Auxiliary Feedwater Pump Turbine Steam Supply CVCS Letdown CVCS Charging Residual Heat Removal Because of the large number of supports involved, it was impractical to evaluate all of the cases.
Instead, enveloped cases were selected based on:
a) severity of thermal transient b) frequency of occurrence 'of thermal transient c) loads on lugs j
d) localized pipe stresses.
Based on the above, the following five supports with welded attachments were selected as the representative worst cases (Reference 6).
SUPPORT MARK NO.
PIPING SYSTEM LUG TYPE CV-9117-HL5017 CVCS Charging Rectangular CV-9006-HL5037 CVCS Letdown Circular AF-9006-HL5007 Auxiliary Feedwater Rectangular MS-9001-HL5011 Main Steam Circular FW-9012-HL5010 Feedwater Circular 4619s/0133s
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IV.
METHOD OF ANALYSIS Rules of ASME Code Cases N-122 and N-391 were the basis for performing detailed stress / fatigue analysis. Following are the detailed steps.
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Thermal transient analysis was performed to determine thermal gradients AT, a AT2 and average temperature.Tw of pipe, i
average temperature li of lug. -Bechtel computer program ME643-3 was used. A description of the program is provided in FSAR Section 3.9.1.2.2.9.
2.
For rectangular attachments, Bechtel computer' program ME916 q
(Reference FSAR Section 3. 9.1. 2. 2. 6 ) was used to calculate NB-3600 equations 9-13 stresses and cumulative usage factors.
ME916 uses rules from code case N-122 The input for the ME916 program consists of the following:
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a) lug and run pipe dimensions b) lug and run pipe mechanical loads
.l c) thermal gradients and average pipe and lug temperature d) number of cycles associated with all normal and upset operating conditions.
3.
Hand calculations based on~ the rules of code case N-391 were performed for circular welded attachments.
j 4.
Due to severe therma 1' transients for CVCS letdown and CVCS charging piping, detailed 2-D finite element analyses were performed to calculate thermal gradient stress term 1.7 E a<lTJ-Twl.
Bechtel computer programs ME643-1.and ME643-2 were used. A description of the program is provided in FSAR Section 3.9.1.2.2.9.
The loading combinations for the above evaluation are shown in Appendix 1.
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0 V.
SUMMARY
OF RESULTS A.
PRIMARY STRESS INTENSITY (Ref. 3) j s
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I l DESIGN CONDITION
! EMERGENCY CONDITIONI FAULTED CONDITION (NB-3652)
L (NB-3655.2) l (NB-3656)
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I SUPPORT NO.
1 EQ. 9 ALLOWABLE.
EQ. 9 l ALLOWABLE l EQ. 9 l ALLOWABLE l psi l
psi l
psi l
psi I
psi l
psi i
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11729 l
51900 l
MS9001-HL5001 l 11530 l 25950 1
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l 34910 51900 FW9012-HL5010 7706 25950 I
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AF9006-HL5007 l 7160 l 29340 l 15624 l 44020 l
8120 l 58680 L
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l l 10074 1 47220 1
CV9117-HL5017 l
8706 l 23250 l
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I l 11177 l 42720 CV9006-HL5037 l
8159 l 21360 l
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1 B.
PRIMARY PLUS SECONDARY STRESS AND USAGE FACTOR (Ref. 3) i 1
I NORMAL AND UPSET CONDITION 1
(NB-3653) ll CUMULATIVE I
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SUPPORT NO.
I EQ. 10 1
EQ. 12 EQ. 13 ALLOWABLE I USAGE I
SnMAX.' i SeMAX.
MAX.-
l 3 Sm.
I psi psi psi l
psi l
FACTOR I
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51900 0.0985 MS9001-HL5001 46833 1
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l 51900 0.7835 l
FW9012-HL5010 i
49635 l
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I 58680 0.4385 AF9006-HL5007 17632 1
d l
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l CV9117-HL5017 60109*
1866 1247 47220 0.83281 1
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42720 0.3704 CV9006-HL5037 21325 I
Equation 10 is exceeded, therefore ratchet check is required per NB3653.7. The ratchet check has been performed for this line and is documented in the Class 1 report (Ref. 4).
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VI.
REFERENCES 1.-
NRC Letter,'from N. Prasad Kadambi to J.- H. Goldberg, Docket Nos. 50-498 and 50-499,-dated 2/27/87 l
2.
HL&P Letter, ST-HL-AE-1723, dated 8/28/86 '
3.
Bechtel Calculation 2LO21RC9585, Rev. 0 4.
Bechtel Calculation 1C159RC5307, Rev.1 I
5.
.HL&P letter, ST-HL-AE-2025, dated 4/8/87 6.
HL&P letter, ST-HL-AE-2132,. dated 4/30/87 f
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APPENDIX 1 i
(Page 1 of 2)
Loading Combination for Evaluation of Class 2 & 3 Welded Attachments S0uth Texas Project (ASME Class 1 Rules)
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LOADING l
1 CODE l
COMBINATION
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. COMMENTS l
l EQUATION l CONDITION il l
l l FROM PIPE & LUG l l
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l Design.
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l (Emergency) l l
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l (Faulted) l P0 + DW + LOCA l
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l 10 L Level A/B l P0 + TH + lTj -Twl*
If eq.10 is not satisfied 1 l
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l OBE + SAM (OBE) for all pairs of load set, l component design is accept-l able provided eq.12,13 l
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t -Tw} ll l
11 l Level A/B l P0 + TH + T l
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+ d T) +
Tp +
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l 12 h Level A/B i TH l
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I 13 l Level A/B l PO + DW +\\Tj Twjl l
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l l Thermal l
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l l Ratchet l Level A/B l TH1 1
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l l Range l
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- lTg - Tsl is used for circular lugs only.
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O R.h{ft APPENDIX 1 (Page 2 of 2) j TABLE : LEGEND Deadweight (including any other sustained mechanical load)
DW LOCA Loss-of-coolant accident - defined in Appendix A of 10CFR Part 50 as "those postulated accidents that result from the loss of reactor coolant, at a rate in excess of the capability of the reactor coolant make-up system, from breaks in the reactor coolant pressure 3
boundary up to and including a break equivalent in size to the i
double-ended rupture of the largest pipe of the reactor coolant sy stem. "
This condition includes the loads from the postulated pipe break itself and also any associated system transients or dynamic effects resulting from the postulated pipe break.
LOCA is calculateo as LOCA = LOCA (JET) + LOCA (NOTION)
Operational-basis earthquake (Inertia)
OBE Design Pressure PD Operating pressure including any transient pressures associated
{
P0 with the plant condition under consideration Seismic anchor movement SAM Safe-shutdown earthquake (Inertia)
SSE j
Thermal expansion and thermal anchor movements TH lT-Twl-Thermal discontinuity stress term (due to temperature difference f
between lug and pipe)
AT1 Linear temperature distribution term (EQ.(11), NB-3653.2, S'79)
AT2 Non-linear temperature distribution term (EQ.(11), NB-3653.2, S'79)
Thermal stress ratchet check per NB-3653.7, S'79.
TH1 4619s/0133s
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