3F0486-02, CR-3 Pump Support Configuration Study

CR-3 Pump Support Configuration Study

ML20141C464
Person / Time
Site:	Crystal River
Issue date:	03/24/1986
From:	Canning J, Harrison H BABCOCK & WILCOX CO.
To:
Shared Package
ML20141C450	List: 3F0486-02, CR-3 Pump Support Configuration Study ML20141C444
References
32-1163899, 32-1163899-00, 3F0486-02, 3F486-2, NUDOCS 8604070252
Download: ML20141C464 (35)

Text

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FPC 3F0486-02 i,-

ATTACHMENT 3

CR-3 PUMP SUPPORT CONFIGURATION STUDY F

Prepared for Florida Power Corporation by The Babcock and Wilcox Co.

B&W Document 32-1163899-00 8604070252 860402 PDR ADOCK 05000302 P PDR

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Babcock &Wncox DOCUMENT

SUMMARY

SHEET a McDermott company DOCUMENT IDENTIFIER 32-1163899-00 TITLF CR-3 PUMP SUPPORT CONFIGURATION STUDY PREPARED BY: REVIEWED BY:

NAMF M-T- MADDTROM NAMr J.J. CANNING SIGNATURF / SIGNATUR f,, - - g TITLF/M DATE E 2/ k UTLE l d [ M b bib DATE bdbd TM STATEMENT: f COST CENTER NA REF. PAGE(S) b REVIEWER INDEPENDENCEfl PURPOSE AND

SUMMARY

OF RESULTS: b PURPOSE To demonstrate the effectiveness of the FPC RC pump supports.

CONCLUSION The configuration of 2 link bar supports controls the displacements of the pump and effectively takes compressive loads. This condition is dependent on the relative stiffness of the supports, RC piping, and load levels experienced by the system.

THE FOLLOWING COMPUTER CODES HAVE BEEN USED IN THIS DOCUMENT:

CODE / VERSION / REV CODE / VERSIGN / REV ANSYS 4.1C _

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32-1163899-00 TABLE OF CONTENTS PAGE Document Summary Sheet 1 Table of Contents 2 List of Figures 3 Introduction ,

4

, Analysis 7 i

Conclusions 27 References 28 Appendix A: Link Bar Calculations 29 Appendix B: Microfiche of Computer Runs 32 f 3-2/-8(o y 3/nb 2

32-1163899-00 LIST OF FIGURES Fig. 1 Isometric of Piping Model Fig. 2 ANSYS Model Geometry Fig. 3 Case 1 Deflected Shape Plot - Vertical Load Fig. 4 Case 1 Deflected Shape Plot - Horizontal Load

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Fig. 5 Case 2 Displacement vs. Iteration No.

Fig. 6 Case 2 Link Bar Load vs. Iteration No.

. Fig. 7 Case 2 Deflected Shape Plot Fig. 8 Case 3 Deflected Shape Plot - No Pump Support Fig. 9 Case 3 Deflected Shape Plot - Varying Support Stiffness Fig. 10 Case 3 Pump Displacement vs. Support Stiffness Fig. 11 Case 3 Link Bar Load vs. Support Stiffness Fig. 12 Case 3 Piping Moment vs. Support Stiffness i

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l INTRODUCTION PURPOSE: To demonstrate the effectiveness of the Florida Power R.C.-

pump supports.

4 The pump support configuration at the CR-3 plant has been modified such that each pump now has 2 supports. This calculation package will analyze the actual support configuration of RCP-1B (Fig.1), which is supported by two link bars, to demonstrate the ability of the supports to take load. The analysis will be conducted using ANSYS, a finite element code which is widely used in the nuclear industry and has the capabilities to effectively analyze the piping and pump support system.

METHOD: The existing finite element model of the pump supports and piping (Fig. 2) will be modified to reflect the modified support configur-ation. Existing supports will be removed and the two link bars will be modeled using pin-ended spar elements (ANSYS STIF8) between the pump radial spacer elements and the wall. The large-displacement analysis option will be used in all analyses to effectively model the support stiffness in the displaced configuration.

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32-1163899-00 ANALYSIS: The analysis of the piping and pump support system will consider three cases. The first case corresponds to the actual plant conditions. The remaining two cases are hypothetical situatiora which have ,

i been included for the purposes of demonstrating relevant abilities of the analysis code and reinforcing the validity of the results obtained in the actual case. Each of these cases are described in detail in the following sections of this report.

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32-1163899-00 CASE 1 - ACTUAL PI. ANT CONDITIONS The first case to be considered will be the actual support conditions as previously described. The model will be subjected to a vertical load and a horizontal load, applied separately. Each solution will be allowed to converge to a stable configuration and the load in the link bars will be monitored.

Computer run CMAA The model is loaded with a vertical load of IG. The solution converged in two iterations. There is a negligible difference between the results after the first iteration (which corresponds to a small-displacement solution) and the converged results, indicating no significant change in the system stiffness characteristics due to displacements of the link bars. *u e forces in the link bars are 7.1K in bar no.5 and -89K in bar no.7. The displacement solution is shown in Fig. 3. Selected quantities from the solution are tabulated below.

OUANTITY ITER 1(1) ITER *(2) % CHANGE Force-link bar 5 (1bs) 7039 7114 1.5 Force-link bar 7 (1bs) -89326 -89252 0.08 Vertical disp 1 of pump (in) .146999 .147247 0.17 Note 1: Small displacement solution Note 2: Converged large displacement solution 52/~8d

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32-1163899-00 Computer run CKXY The model is loaded with a horizontal force in the global I direction of 500K applied to node 11 (' pump centerline at the support elevation) , a load which far exceeds actual load levels. The solution again converged in two iterations with negligible large-displacenent effects. The forces in the link bars are -515K in bar no.5 and -108K in bar no.7. The displacement solution is shown in Fig. 4. Selected quantities from the solution are tabulated below.

OUANTITY ITER 1(I) ITER 2(2)  % CHANGE Force-link bar 5 (1bs) -514450 -514550 0.02 Force-link bar 7 (1bs) -108160 -108280 0.11 X-Displacement-node 11 (in) .0569556 .0570118 0.10 l Note 1: Small displacement solution Note 2: Converged large displacement solution l

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32-1163899-00 CONCLUSIONS - CASE 1 Based on the results of the preceding analysis, the following conclus-lons can be drawn:

The link bars are effective in supporting the pump / piping system in the sense that they can and do take compressive load.

. Geometrically nonlinear (large displacement) effects are negligi-ble in the actual system at the load levels considered in this analysis.

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CASE 2 - REDUCED PIPING STIFFNESS -

The second case will consist of reducing the piping stiffness to demonstrate the role of the piping stiffness in determining the displacement solution. This will also demonstrate the ability of ANSYS to model a system undergoing large displacement.

1 Computer run CCHG The piping stiffness is reduced by dividing its modulus of elasticity by 100. The upper cold leg is also disconnected fros. the reactor vessel to further reduce the stiffners. The model is loaded with a vertical load of 1G, and horizontal loads of 50K in the global X and Z directions applied at node 11. The analysis ran for 20 f.terations reaching an approximately converged solution ( a final maximum displacement increment of .005 inches versus a total displacement of 49.7 inches at node 2 - the end of the UCL). ne solution showed significant large-displacement effects as indicated in Figs. 5 and 6. Fig. 5 shows the displacement solutions for node 11 (translational degrees of freedom) which were generated as the analysis Iterated toward a converged solution. Fig. 6 shows the link bar loads at each iteration. There is a significant change in the solution during the first ten iterations, af ter which the solution begins to stabil-ise. The iterations continue through iteration 20 due to a rather stringent convergence criterion used in the analysis (.001 in.). The displacement solution is shown in Fig. 7, plotted to true scale to show the magnitude of the deflection.

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32-1163899-00 CONCLUSIONS - CASE 2 This hypothetical case serves to illustrate the fo!!owing points:

I By greatly reducing the piping stiffness, the piping and puc) support sy. stem can be shown to undergo large displacements at a reasonable load level. This demonsteates the fact that the piping stiffness plays an iniportant role in determining the load carrying characteristics of the overall system.

This case also serves to demonstrate the capabilities of ate '

analysis cole to adequately moda.1 a system which undergoes inrge  !

displacements and demonstrates the solution data which the code can produce.

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ibe third case will consist of a series cf runs with varying link bar stif.fpenses. The first run will have zero b:tr stiffness ( nc pump suppcets) to determine what tha force / displacement solution would be if the 4 link bars actually rook no load. The subsequent runs will have gradually increasing bar stiffnesses to demonstrate how the link tars force the solution back towards thst determined in ecse i for full bar stiffness and in doing so, take en ever-increasing load. '

Conputer rucs CKUP, CFVE, CWU, CKXK The link bar stiffnesses were modified by reducing the bar's modulus of elasticity. For the case of zero stiffnes,= the link bars were simply removed fro:n the model. The subsequent runs used E values of E/1000,

.E/100, and F./10, where E=30.E6 P3I. The case of full bar stiffness corres-ponds to the a::talysis of case 1. The model was loaded with a horizontal load of 500K in the global X direction applied at node 11. The displacement nolution for the case of zero bar stiffness is shown in Fig. 8, plotted with a serie factor of 10 on displacements. Fig. 9 chows the displaced ,

shaper for all four runs listed above plotted with a scale factor of 10.

For this scale facter, the results of the run with E-E/10 are indistinguish- [

eble from the undeform(,d shape. Hgures 10, 11 and 12 show the

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effects of varying the bar stiffness.on the pump displacements, link bar forces, and piping moments, respectively. It can be seen from these results that the presence of the link bars and their stiffnesses relative to the piping stiffness have a significant effect on the piping solution. The link bars restrict the displacements of the pump and, in order to apply the forces required to control the pump displacements, the bare must take loads themselvea.

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32-1163899-00 CONCLUSIONS - CASE 3 The purpose of the sequence of runs in this case is to illustrate, in quantative terms, the following points:

The link bars affect the displacement solution of the piping system. This is demonstrated by comparing the displacement solutions of Case 1 (the actual support conditions) and Case 3 (no pump supports). This is done in Fig. 10 for the displacements at the pump centerline. Since the displacement solutions differ, it is concluded that the link bars do effect the displacement solution.

The link bars must exert a force on the piping system in order to affect the displacement solution. The analysis of Case 3 with no t

I pump supports determined the single valid equilibrium configura-tion (via the Principle of Minimum Potential Energy, the basis of the finite element method used here) of the unsupported piping system under the applied loading. In order for the piping system to be in equilibrium in another displaced configuration additional external forces are required to counteract the internal forces produced when the piping system is moved to its new configura-i tion. In the system analyzed here, the link bars provide the f 3-2/- %

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32-1163899-00 forces necessary to move the piping system from the displacement configuration of Case 3 with no pump supports to the displacement configuration of Case 1. These forces are shown in Fig. 11.

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s 32-1163899-00 CONCLUSIONS:

A series of analyses were conducted to determine the effectiveness of the pump support configuration at the CR-3 plant when the link bars are loaded in compression. It is concluded, based on the results presented above, that the present configurstion of link bar supports is effective in the sense that they control the displacements of the pump and, in doing so, demonstrate their ability to take compressive loads. It can also be observed from the parametric studies done that the effectiveness of the support configuration analyzed in this calculation is dependent on the relative stiffnesses of the supports and the piping, and the load levels experienced by the system. It has been shown here that these quantities can vary by an order of magnitude or more and still not substantially affect the results. Therefore, the conclusions reached here are valid for the system analyzed in this report and for other piping systems with similar character-

istics.

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REFERENCES:

- 1. 32-1156742-00, " FPC NONLINEAR COLD LEG MODEL",J.J. CANNING, CR-3 FLANT, 4-2-85.

2. 32-1159644-00,"RCS STRUCTURAL ANALYSIS WITH RESUPPORTED PUMPS",R.B. ALLEN, 1-16-86 O

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32-1163899-00 APPENDIX A: LINK BAR CALCULATIONS 5 S/~hh p y"u/a e

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Nomenclature: Link Bar #5 - Connects to Node 105 Link Bar 97 - Connects to Node 107 Link Bar Stiffnesses: #5 K=12.6E6 4/in.

1. 7 K= 9.5E6 f/in Coordinates of Link Bar Wall Pins:

- #5: X = 304.1987 Y= 78.0 Z = 240.8472 Define as Node 205

1. 7 X = 100.0 Y = -80.29 Z = 545.2322 Define as Node 207 Length of Link Bars:

1. 5 from node 205 to node 115 L= [(304.1987-160.0461)2 + (240.8472-283.5471) 2 j2" p 150.3438"

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1. 7 from node 207 to node 117 L=

[(78+80.29)2 + (356.5938-545.2322)2] % = 246.2522" GA NffE: C/0DINMB5 APE FGA J15 /05 i/07 wHtul /A/MetSes l- BY 1.0" -

l Link ga A qrGlofE OlFF98WE /Al4 AGM l roperties for Model Inpup; INPVT KLf?/M6t2 AS cal &st.AIED Use E = 30.E6 PSI

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FPC 3F0486-02 ATTACHMENT 4 ELABORATION ON ELEMENTS OF FPC RESPONSES TO NRC QUESTIONS 9 AND 10, ATTACHMENT 1 i

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.o NRC QUESTION 9 Clarification is needed that steady-state hyd raul i c loads include fl ow induced vibration due to pump operation (NUREG/CR-1319, " Cold Leg Int eg ri ty Evaluation"), and that these loads are appropriately combined with dead weight and thermal loads.

RESPONSE TO NRC QUESTION 9 The pump induced vibration stress range assumed (NUREG/CR-1319) was 1 ksi at a frequency of 1000 cycles per minute or 2.1 E10 cycles during a 40-year pl ant life. The cold leg piping allowable primary stress at operating conditions (1.5 Sm 0 5570F) is 29.2 ksi. The assumed vibration stress (1/2 range = 0.5 ksi) is therefore only 1.7 percent of the allowable stress. At this operating condition, the total primary stress at the highest stressed point in the cold leg is 23.4 ksi (total includes pressure, deadweight, OBE seismic and the assumed pump induced vibration stress). Thus, sufficient margin exists.

The assumed vibration stress range of 1 ksi is well below the endurance limit of the carbon steel piping. Therefore, the usage factor associated with the 2.1 E10 cycles would not be significant in an ASME Code fatigue analysis. In addition, the 1/2 range of vibration stress would increase the maximum p rim a ry pl u s secondary stress intensity range by less than 1 percent. This corresponding stress increase (accounting for the simplified el a s ti c-pl as ti c analysis correction f actors) would increase the fatigue usage factor by less than 1%. The current fatigue usage factor for the cold leg primary piping is less than 0.05 (Code Allowable = 1.0). Thus, the increase is not significant.

The above calculated stresses at operating conditions have not been formally documented to the NRC but are available in calculation documents.

NRC QUESTION 10 Clarification is needed that local stresses in the RC pump casing resulting from the attachments of the supports to the casing have been included in the stress evaluation of the casing.

RESPONSE TO NRC QUESTION 10 The reactor coolant (RC) pump supports are not integral attachments to the RC pump casing. They are attached to restraint ring (collar) which is in turn bolted to the top of the pump. The collar is bolted to a reinforced portion at the top of the pump. The collar is a massive piece (designed to withstand LOCA loading) capable of distributing seismic loading among all the attachment bolts. Bolt stress effects are evaluated in the RC pump analysis.

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