ML20070P949

Jet Impingement Study on 3-Inch Resistance Temp Detector & 10-Inch Accumulator Discharge Lines

ML20070P949
Person / Time
Site:	Catawba
Issue date:	01/19/1983
From:	DUKE POWER CO.
To:
Shared Package
ML20070P874	List: ML20070P862 ML20070P949
References
NUDOCS 8301260418
Download: ML20070P949 (10)

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I l CATAWBA NUCLEAR STATION f JET IMPINGEMENT STUDY ON

! 3" RTD RETURN AND 10" ACCUMULATOR I

DISCHARGE LINES I

I January 19, 1983 I

i 8301260418 830125 i PDR ADOCK 05000

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1.0 INTRODUCTION

! This report summarizes the results of a study conducted by the Catawba Reactor Stress Analysis Group in reply to a NRC request.made.to the Mechanical Design Plant Environmental' Group (MDPE) concerning jet loading on piping targets.

MDPE provided the following examples for the study:

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- Example 1: Math Model NI-07 Jet Load = 7815 lbs. (See Attachment 3)

! Target: 10" NI line from Accumulator

. Tank lD i

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- Example 2: Math Model NC-07 Jet Load = 1725 lbs. (See Attachment 3)

Target: 3" NC crossover RTD return line, RCL 1C ,

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The purpose of the study was to demonstrate that the above piping could sustain jet impingement loadings and maintain pressure boundary integrity, i

! 2.0 DESIGN CRITERIA The examples provided involve ASME Class 1 and 2 piping.

Since the jet evolves following a pipe rupture, faulted condition stress allowables are appropriate for this evaluation. Accordingly, 3 S m (ASME III, Appendix F, F-1360) and 2.4 Sh (NC-3 611. 2) are the applicable stress ,

limits ror Class 1 and Class 2 piping, respectively.

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3.0 DESIGN METHOD 3.1 Pipe Stresses Pressure integrity can be guaranteed by showing that the stresses in the entire piping network under faulted loading conditions are below the collapse level. To evaluate these conditions, conservative static analyaes were performed utilizing the SUPERPIPE computer program.

Distributed an' point forces were used to simulate the jet impingement loadings on the specified target areas.

The resulting stresses were then combined with other faulted load case stresses as prescribed in Tables 3.9.3-7 and 3.9.3-8 of the Catawba FSAR (Attachments 1 and 2) .

3.2 Support / Restraint Loads Jet impingement loads were generated for all support /

restraints (S/R) in each math model, and added absolutely to the existing faulted design load. Whenever S/R reaction loads exceeded their design capability, the analyses were modified to exclude those S/R from the model.

This iterative procedure was continued until it was shown that the additional load from jet impingement was within the limits of the remaining S/R design.

3.3 Equipment and RCL Connections For this asressment of pressure integrity, equipment l

and RCL nozzle connections were evaluated to the same criteria as the connected piping. Loads and stresses at these connections due'to jet impingement were not significant in Example 1 due to the presence of S/R i  !

B in the target area. Example 2, however, showed an appreciable, yet acceptable, increase at the Cold Leg nozzle due to the proximity of the jet and no S/R in the target area to take the jet loading off the piping and nozzle. Further details are presented in Section 4.0 of this report.

4.0 CONCLUSION

S The study conducted on two (2) Catawba Nuclear Station, Unit 1 piping math models has demonstrated that. pressure boundary integrity is maintained under the specified jet impingement loading. The allowable stress intensity was not exceeded for any piping component in either of the example math models.

In Example 1, only 1 out of 22 S/R failed under this-additional faulted loading. The iterative analysis showed the remaining S/R's to be adequately designed to withstand the increased loading even with this snubber removed.

Example 2 indicated failure of only 2 of 29 S/R under-the additional jet loading, but again the remaining S/R restrained the piping effectively and stress levels remained below the 3 Sm allowable by a substantial margin.

Refer to Table 1 for a summary of maximum stress intensity for faulted conditions.

The study performed on the examples provided demonstrated adequate safety margins in piping stress levels and pipe support loads.

i TABLE 1 Maximum Primary Stress Intensity for Faulted Conditions Math Model Joint Primary Stress Allowable Stress Number Component Name Intensity (psi) Intensity, 3 Sm (psi) Ratio NI-07 6" Sch 160 branch 103 36811 48300 .762 connection L

1 NC-07 3" Sch 160 conn. 3 29720 48300 .615 3-11 on Cold Leg 1C Since the requirements of Equation -(9) with a 3 Sm stress limit are satisfied, the primary stress intensity for faulted conditions is acceptable.

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ATTACIIMENT 1 TABLE 3.9.3-7 -

Stress Criteria and Load Combination Requirements for Duke Class A Piping Applicable Condition Load Combination Stress Criteria Design Pressure ASME III 4 Weight NB-3652

+0BE Normal, Upset Pressure ,

+ Weight

+ Thermal

+ Thermal transients ASME III

+0BE (incl. anchor motions) NB-3653'

+ Relief Valve (as applicable) & 3654

+ Fluid dynamic effects Faulted Pressure

+ Weight

+SSE ASME III

+ Pipe Rupture Appendix F

+ Relief Valve (as applicable) (F-1360)

+ Fluid dynamic effects Faulted Pressure

+ Weight ,

+ Pipe Rupture ASi1E III '

+ Relief Valve (as applicable)  : Appendix F

+ Fluid dynamic effects (F-1360)

ATTACliMENT 2 TABLE 3.9.3-8 Stress Criteria and Load Combination l Requirements tor-Duke Class B, C, and F Piping 1

Applicable Condition load Combination Stress Criteria Normal Pressure

+ Weight . ASME III

. + Thermal flC .or ND-3652 Upset , Pressure

. + Weight .

+1hermal

+0BE (incl. anchor motions) ASME III

+ Valve thrust NC- or ND-3652 1

+ Fluid dynsmic effects Faulted Pressure

, 4 Weight

+SSE

+ Valve thrust ASME Code Case.1606

+ Fluid dynamic effects

+ Pipe rupture

Faulted Pressure

+ Weight - ASME Code Case 1606

+ Valve thrust

+ Fluid dynamic effects

+ Pipe rupture Faulted Pressure 9

ASME Code Case 1606 n do 1

w .----.% -,. m,s -,,--..m -,----w---- ,e. 3 w- y n- . - -

ATTACHMENT 3 The two examples provided for this study illustrate the two different cases of jet loading on a piping target. For each exanple, the piping target load was calculated based on source piping conditions prior to the rupture.

The first example involves a case where the target piping is of a larger nominal pipe size and wall thickness compared to the source piping. The target piping will receive a full loading from a non-expanding jet with the jet area being smaller than the impinged pipe. The jet impingement force is assumed to be invariant with time and equals to the blowdown force times a correction factor (shape factor). The force acts normal to the target pipe surface.

The second example involves a case where the target and source piping are of equal nominal pipe size and wall thickness. The target piping will receive loading from an expanding jet (having a 100 angle expansion) with the jet area being greater than the impinged target area. The source piping is 10 feet away from the target and the jet impingement force is invariant with time. The jet impingement force equals to the blowdown force times a correction factor which includes the shape factor and the ratio of target area over jet area.

For each example, jet impingement force will be calculated by using the methods and procedures established in ANSI /ANS-58.2-1980.

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Example 1 =

- Source = 6" NI from Residual Heat Removal Heat Exchanger lA

- Piping Conditions: 465 psia, 120 F (Non-expanding jet)

- Blowdown Force: Using the Simplified Method for calculation of Fluid Thrust Forces illustrated in ANSI /ANS-58.2-1980, Appendix B, pages 33-48, the blowdown force can be set equal to P x A i where P is the line presource and A is the total circumferential break area.

F = P x A where A = 21.13 in2 (6" NI, Sche. 160)

F = (465)(21.13) = 9825 lbs

- Jet Impingement Force:

F imp =KFjet (Atarget Mjet), = .2-N, Wem D, p. 56.

where K is the shape factor F

jet is the blowdown force and A target/Ajet conservatively set to be 1.0 K = 1 - 0.424D For a circular det Impingement on Pipe with Jet Diameter 3

less than Pipe Diameter (Non-expanding jet with source D

o being 6" NI and target being 10" NI).

Ref. ANSI /ANS-58.2-1980, Appendix D, p. 58 D 3 = 5.187 in (6" NI, Sche.160)

Dg = 10.75 in. (10" NI, Sche. 140, Outside Diameter)

K=1 _(0.424)(5.18R = 0.795 10.75 F$ ,p = (0.795)(9825)(1.0) - 7815 lbs i

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Example 2

- Source = 3" NC Crossover RTD Return line 18

- Piping conditions = 2250 psia, 557"F (Expanding Jet)

- Blowdown Force = P x A (See Example 1 for source of reference)

F = P x A where A = 4.155 inz (3" NC, Sche. XXS) 1 F = 2250 x 4.155 = 9350 lbs <

- Jet Impingement Force:

F imp *Kfjet(Atarget jet) /A (See Example 1 for reference)

Where A =Ae (1 + 2L tan 10*)2 for an expanding jet wi';h 10* expansion.

jet (Ref. ANSI /ANS-58.2-1980, Appendix C. p. 54) with Ae (circumferential break area) = 4.155 in:

De (source pipe inside diameter) = 2.3 in L (distance from source to target) = 120 in A

jet = 4.155 (1 + 2 120 tan 10 )2 = 1564 ina or D jet = 44.6 in A

target : 500 in2 This area is obtained by taking the surface area of the target being impinged by the expanding jet of the source 10 feet away from the target.

K, shape factor, is equal to 0.576 (for a Circular det Impingement on pipe with Jet Diameter Greater than Pipe Diameter) Ref. ANSI /ANS-58.2-1980 Appendix D, page 58 F

jet = 9350 lbs (blowdown force)

F imp = (0.576)(9350)(500/1564) = 1725 lbs i

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