ML20082M623
| ML20082M623 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/26/1991 |
| From: | Joshua Wilson TENNESSEE VALLEY AUTHORITY |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9109050296 | |
| Download: ML20082M623 (9) | |
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August-26, 1991 E
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i U.S. Nuclear Regulatory Commission ATTN:
Document Control Desk Washington, D.C.
20555 Gentlement.
In the Matter of
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Docket Nos. 50-327 i
Tennessee Valley Authority
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50-328 b
SEQUOYAH NUCLEAR PLANT (SQN) - ALTERNATE ANALYSIS REVIEW PROGRAM PHASE II -
PIPE SUPPORT DEFLECTION CRITERIA (TAC NO. R00420)
In an October 22, 1990, letter, TVA provided the results of an evaluation l
of the deflection criteria used to verify rigidity for pipe supports for l
alternately analyzed piping. This evaluatien was performed on a 2-inch j
L pipe model.
Subsequent reviews by NRC staff raised concerns with the ability to extrapolate the results of the 2-inch pipe model evaluation to the 4+ and 6-inch piping dimensions, which could also be alternately
- i
. analyzed piping. Thest concerns were discussed in a telephone conversation
.between SQN and NRC-staff on February 12 and April 8, 1991.
As agraed to in the April 8 discussion-the enclosure provides the requested infor nation j
i as it applies to 4-and 6-1.;ch pipe.
No commitments are contained in this submittal.
Please direct questions t
concerning this issue to W. C. Ludwig at (615) 843-7400.
l Very truly yours',
TENNESSEE VALLEY AUTHORITY
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L. Wilson Enclosure cc:
See page 2
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"U.S. Nuclear Regulatory Commission August 26, 1991 t.
-ce (Enclosure):-
Mr.-D. E. LaBarge, Project Manager U.S. Nuclear Regulatory Commission j
One White Flint, North 11555 Rockville Pike l-Rockville, Maryland 20852 NRC Resident Inspector Sequoyah Nuclear Plant L
2600.Igou Ferry Road Soddy Daisy, Tennessee 37379 Mr.-d. A. Wilson, Project Chief:
U.S. Nuclear Regulatory Commission 4
Region II l
101-Marietta. Street, NW,-Suite 2900
- Atlanta. Georgia 30323 e
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.5 ENCLOSURE
-PIPE SUPPORT STIFFNESS EVALUATION f
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1.0 INTRODUCTION
In response to NRC's review of SQN's October 22, 1990, submittal conceraing support stiffness in the Alternate Analysis (AA) Program, an additional evaluation was performed. This evaluation determ;ned the effect of support stif fness on piping havit;g a diameter larger tnan 2 inches using the same methodology that was previously used on smaller piping.
2.0 EVALUATION The evaluation uses a model.imilar to the configuration previously used in the above referenced submittal to evaluate 2-inch piping.
Four-inch pipe was chosen because it is the largest size of piping with a statistically significant population within the AA Program.
The spans used for the 2-inch nodel were increased in order to produce spans that were generally greater than the basic allowatle spans for 4-inch pipe, thus creating a highly stressed model.
The same methodology and spectta used in the October 22, 1990, submittal for the 2-inch evaluation were followed in developing the stress and loads for this evaluation.
A detailed stiffneas evaluation was not performed for 6-inch AA piping.
The amount of 6-inch AA piping is less than 4 percent of the overall populatior In addition, consistent with the AA criteria, 6-inch piping was either mov.teu on TPIFm or individual hand-calculated support loads were generated and unique support designs were developed. This resulted in piping and supports being inherently qualified to accepted rigorous analysis methods.
Calculation of Span Lengths The allowable span length for 4-inch Schedule 40 pipe with 2.5-pound / foot (lb-ft) insulation is 15 feet 11 inches. The spans used for the 2-inch model were increased proportionally upward to account f or the larger size pipe. The seveloped spans maximizod stresses for the hand calculations, fgan 2" Span Length 4" Span length 100-110 15'- 0" 18'- 9" i
i 110,120 13'- 6" 16'- 9" 120-1::,n 14'- 3" 18 ' - 0" 130-140 9"
l'- 0" 140-150 12'- 9" 16 ' - 0" 150-160 16'- 6" 20'- 6" 160-170 15'- 9" 19'- 9" 170-180 6'- 9" 8'- 6" 180-190 9'- 0" 11'- 3" 190-200 15'- 0" 18'- 9" 200-210 16'- 6" 20'- 6" See Figure 1 for configuration of piping model, which was created for this response.
+
. Phyilcal Properties Piping:
4" Schedule 40: outside diameter (od) = 4.5 in
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wall thickness (tn) = 0.237 in I
weight (pipe, fluid) 16.3.lb/ft
=
(insulation) 2.5 lb/ft
=
(total)
(w) 18.8 lb/ft
=
7.23 ink moment of inertia (!)'
=
3.21 in3 section modulus (z)
=
SA312 TP304 SC = 18,800 ps.1 Sg = 17,500 psi Design pressure = 350 psig Comparisons
- A comparison of pipe stresses calculated by the AA method versus those
- generated by TPIPE analysis using varying support stiffness is tabulated in j ~;
Table A.l. -The maximum faulted stress generated by the AA method is 34,503 pounds per' square inch 1(psi). The maximum faulted stress generated by TPIPE analysis for all support stiffness-is less than the maximum stress calculated by the AA method. TPIPE and AA generated stresses are less than the 2.4 Sg allowable;(42,000 psi) per the American Society of Mechanical Engineers code.
A comparison-of the suppcrt loads from the AA method versus the TPIPE analysis-using varying support stif fness vilues -is tabulated in Table A-2.
The TPIPE
. analyses for.l.0E03, 5.0E03, and 1.0E04 generato loads that would cause noncredible displacements in violation of the 1/8-inch deflection requirement in SQN-DC-V-24.2.
The support loads from the TPIPE analyses were tabulated; and the-loads, which produce-noncredible deflections based on postulated (support stiffness, are-in parentheses. Credible loads-are less than-the hand-calculated loads except theiY direction load at-Node 110 in the'l.0E04 e
. analysis.. This exception only exceeds the original calculation by 5 percent
- or 38 lbs and does not constitute a qualitication concern because of the conservatism present in-the analysis.
It should be noted-that the TPIPE runs were' generated using the same monotonically descending spectra as were usedLin the hand calculations. -Thus, the analyses do not take-credit for-lower accelerations at low frequencies.
In the TPIPE analyses using 1.0E05 support 2tiffness and greater, all the support deflections are less than 1/9 inch and all the-laads are less than the hand-calculated loads.
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3.0 CONCLUSION
4 i-l' 7The supports for the AA Program were limited-to the 1/8-inch deflection as o
required per SQN-DC-V-24.2.
From-this e"aluation it is concluded that the.
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3.0 CONCLUSION
(continued) support detlections criteria for large bore AA pipirig provide the equivalent of the mandated minimum support stiffness of 1.0E04 pounds / inch. Variances in the support stiffness above that figure do not result in loads or stresses that comprornise qualification of the piping system.
In addition, it is shown that loads generated by the alternate analysis hand-calculation method are conservative with respect to TP1PE analysis when credible (deflection-limited) criteria are met.
TABLE A-1
- Comparison of Stresses from AA Methodology vs.
TPIPE w/ Varying Support Stiffnesses 2
Faulted ASME Code Stress (1b/in )
Pipe Span AA TPIPE TPIPE TPIPE TPIPE
- Ti:PE Node - llode Method 1.0E06 1.0005 1.0E04 5.0E03 1.0E03 100 - 110 29809 6204 6211 7741 10111 10863 110 - 120 note 1 5685 5736 6572 7528 11892 130 34503 6653 7024 7456 9567 12984 120 130 - 150 32915 3653 7024 8009 8915 12822 150 160 16430 4507 4722 6938 9299 20115 160 170 note 1 5827 5995 8317 10209 15943 170 - 190 17816 7249 7469 8867 10679 16762 190 - 200 23351 7511 7775 9008 10679 16864 200 - 210 27093 7546 7853 10971 13634 15957 Note 1.
Specific stresses were not calculated, as by inspection spans are shorter than previously calculated spans.
All support deflections in 1.0E03 support stiffness run are greater than 1/8".
Taarefore, calculated stresses are also non-credible.
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TABLE A - Comparison of Support Loads from AA Methodology vs. TPIPE w/ Varying Support Stif fnesses Faulted Design Load (lb & ft-lb)
Node Name /
AA TPIPE TPIPE TPIPE TPIPE
.TPIPE Direction.
Method 1.0E06 1.0E05 1.UE04 5.0E03 1.0E03 100 F
1627 1068 1074 1136 1100 1111 x
F 485 310 334 352 324 384 Ff 882 164 161 226 328 251 ANCHOR M 2407 42 45 83 110 213 y
M 3305 708 693 996 1547 1504 y
F 1818 1158 1270 1403 1328 1960 110 F
638 543 571 676*
571 (591) y SUPPORT P 1160 313 322 523 591 (627) g 120 F
719 480 506 633 619 (876) y SUPPORT F'g 1307 272 272 374 575 (1387) l l'
130-F 2454 2152 2304 (2844)
(3030)
(2796) y SUPPORT F 1316 270 280 454 (732)
(1077) g 150 F
1373 285 297
- 485, 575 (1460) x SUPPORT F 1410 354 379 C31 (748)
(1996) g 160 F
1514 292 320 592 (1105)
(1912) x SUPPORT F
=1514 283 292 540 (1055)
(2044) 3 170 F
1981 290 318 614 (993)
(1118) x SUPPORT F 1063-253 254 437 (765)
(1386) g 190 F
1448_
316 340 461 (640)
(1354) x SUPPORT F 621 417 420 531 (640)
(1667) y 200 F
1284 428 470 731 (804)
(1375) x SUPPORT F 706 524 526-621 (668)
(1428) y 210 F
964 214 231 358 463 395 x
F 530 277 280 354 401 409 Ff 1269 1006 1015 945 997 1073 ANCHOR M 2173 991 1014 1455 1721 2534 x
M 3951 913 989 1677 2309 2592 Ff 693 181 183 203 217 353 g
- See page 2 for discussion of this load exceedance.
Ncte:
Support loads shown -in parentheses are presented for completeness, but result from support stiffness lower than the design criteria permits.
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FIGURE 1
- Piping Configuration Used In Stiffness Evaluation For Four Inch Diameter Pipe Showing Support Types And Locat. ions And Span Lengths i
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