ML17193B256

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Draft of Summary of Dresden Unit 2 Recirculation Loop Piping Reanalysis
ML17193B256
Person / Time
Site: Dresden 
Issue date: 03/27/1981
From: Nitzel M
NRC
To:
Shared Package
ML17193B255 List:
References
TASK-03-06, TASK-03-11, TASK-3-11, TASK-3-6, TASK-RR NUDOCS 8104010445
Download: ML17193B256 (14)
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  • SUM~ARY OF DRESDEN UNIT 2 RECIROJLATION LOCP PIPING REANPL YSIS Af'PLIED MECHANICS BRAt>CH M. E. Nitzel

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.*, Audit calculations* to verify the original analyses and new

... calculations using. current ASME Code and Regulatory Glide standards were performed on*the* Dresden Unit 2 recirculation loop piping.

In Reference *1 t.he recirculation loop piping was divided into three finite element models

    • each. of which was assumed to be anchored at one or both of* t.he recirculation pumps.

Recently received information indicated that instead

  • of being '.~Jfective an.char points, each recirculation pump is in fact

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t' supported by three constant force supports and six snubbers.

To account for this change in configuration, all three models were asserrbled into one complete recirculation loop model which lncluded the two recirculation pumps and their supports.

  • The "current criteria" analysis was then*

repeated for the combined model using the same methods and procedures as in Reference 1. The NLP IPE-II computer program wa.s used for this analysis.

The results of this new analysis are briefly described below.

Since no information (weigit, e.g. location, etc.) was provided, it was assumed that each recirculation pump weighed 80 kips with a total lengu, of 20 feet and center of gravity located approximately 10 feet up from the pump inlet. These assumed values were based on data from other plants of similar size and configuration.

The pumps were modeled using a sectional geometry with an outside diameter (0.0.) of 42 inches, wall thickness of 2.CXJ inches and a weight/length ratio. of 4000 pounds/foot.

The elements comprising the pu;;ips were declared to be "VALVE" elements ir.

the NLP~-II computer input. using ~,e sectional geometry and valv:

.designation described above had the result that the pump elements were.

quite stiff as compared to the connected piping; thus, the effect of the pumps on the dynamic response of the system was taken into account but

  • only the natural frequencies of the piping were calculated and used in the r~sponse spectrum analysis.

An overall plot of the combined recirculation.

piping model is shown in Fig.ire 1. Figures 2. tnrough 4 display isola~ed plots of various sections of the complete model.

It should. be remembered that the dimensions shown on u~ese ~lots are approximate and are intended only to give an indication of scale.

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28" Suction Piping l._!.

"Loop l" rRccirc.

...J Pump Pirinu Anchor IQ

'\\ '(_22" Manifold Pjping figure l DRESDEN 2 - Ht:C ll<C. r II' I Nli MPIPE Hfll11£Hnt ICfll MQU[L

    • LEG£ND**

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0 - iii&fOllll L01111 llli

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SPRlllC-trllCfR K:::>-. SHUilCR

~-t RIGID SU'POlll

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Overall *Plot of Dresden Unit 2 Combined Recirculation Loop Model

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10 II II R.V. Anchor Point Ul~[SDEN ?.

  • R[C IRC. I'll' ING NUPIPl Hllfll[HRI 1cnL. MOUi I*
  • *lEG(MJt *

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2B Inch (Nominal)

_s Suction Piping (49! Total Length)

Pump Inlet (Node 17}

Figure 2 I

Nill LOCAi 10'4 0

HRSS/'01111 lOrill 1'1*1 ~

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SPRlllG IOlG( R

~-CJ-. SNLIIJ[R

<(J--1 RIGIO Sl.f'l'ORI *

-g. flNO()R Isolated Plot of "Loop 1 11 Recirculation Punlp 28 Inch Suction Piping

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22 Hani fold (17' Radius)

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"Loop 1 11 Recirc. -,

Pump L-:s:>

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20'

° 12 Inch~

Riser Piping l-.....

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Figure 3 DRE:lOrN 2 - K(CIHC. f'll'IMI NUP I PE Hn I llf Hnl I Clll HOllU ttl[li[ND**

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Hll59'01NI L0l111 l!Y-l 4-/1111'- -

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RIGID 5ll'PORI

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  • ON()(JH I~olatcd Plot Showing "Loop 1 11 Recirculation *Pump 28 Inch Discharge*

22 Inch Manifold, and Some 12 Inch Riser Piping

    • 1.,.

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1 The sa:ne procedures and response spectrum_ as used in the "current

  • 'c.riteria" analysis of Reference l were used to pe_rform the "current c:'ite:ria'i analysis of the coiilbined recirculation loop model described h:rein.

Table 1 lists the first 10 natural frequencies and periods of vibrationf[6r the combined recirculation model and the Pl, P2, and P3 m~cels frp~ R~ference 1.

Table 1 shows that the frequencies found for the c6r..'.Jir1ed :node 1 are lower than those previously determined.

Considering

~,e anc.,ors that were removed and the mass added when the combined model was form~cl, 1 :pie fir:eq\\Jency.shift was not unexpected._~

1

' i A comparison of AS~ Code Equation 9, stress results is displayed in Table 2.

This table compares results at identical points between the c~r.oined model and the Pl, P2, and P3 models of R~ference 1.

The results s:acw that' ;me stresses, from the combined model are -al_l within the..

c.Eowable.!.imit.; howeve=, these si::resses are considerably higher than

..~cse f~m Reference 1.

The difference in stress levels is primarily due t.::i the frequency shift shown in Taole 1.

In particular, the lower first f.requency found for L,e combined rnodel resulted in much higher c.cse~eration values being used to calculate pi~e forces and moments for

~,e first ~ode of the response spectrum analysis.

Table 3 presents a com~rison of su~port loads.

T.1is tabie lists s2:s~c loads for the corrbined mocel and those loads reported in

~efe=ence 1.

The maximum recommended load as found in the manufac~urer's C2:alog is also listed for the sm.:bbers and sway braces.

These resul~s shew u,a~ all the snubber loads from the combined model exceed the

=ecomrl'~nded loads. It should be recalled that the SSE load case which was

~o~sicered is a Service Level D (faulted condition) load.

The

~3~ufacturer's catalog did not specify the service condition for u,e

-ecommen.ded loads; thus, if the r~commended loads are for a*

Se:vice Level B (upset) condition, the corresponding allowable loads for Service Level D are p:rooat:>ly; somewhat hign~r. Considering thgt many of

~~e snubber loads from the cont>ined model far exceed u,e recornrrended leads, it re~ains doubtful L,at the possibility of higher snubber ratings

~--- 'fc:- Se:rvice Level D conditions would be sufficient in itself to assure st:ructural adeouacy of L,e pump supports.

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Anchor loads for both the corrt>_ined model and Reference l are compared in Table 4.

Tilese.results show that the anchor loads from the corrbined model are consiaerably higher t.har: those froin the Reference 1 analysis.

Tile results di.scussed above can be used to conclude that the.

recirculation loop piping ~~resses will be within AS!-£ Code allowable I

limits during an SSE event.

Information contained in Table 3 leads to the conclusidk that the snubber s supporting the recirculation pumps will be overloaded dur.i,ng an SSE.

Tne probability of snubber failure appears to be fairly high.

As shown in Table 4, anchor loads for the comoined model increased significantly. Since* the-pipe stresses near the anchors are all below allowable limits,.- it 'is !likely that the stresses in the. nozzles, will*

1 be within allowable limits; however, some consideration should be.given to the effect of the inc~eased nozzle loads on the stress levels in the reactor vessel walls adjacent to these nozzles.

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MODE 1

2 3

11

  • 5 6*

7 0

9 10 T/\\U.LE 1.

())tvf>/\\1115Cl'J OF F IHST TEN N/\\TURAL FIU::(JUEN..:IES AND PEHIODS OF VIBHATION -

DHESLJt:N UNIT 2 HECIRCUL/\\TION LOOP MJDELS COl-OINED REF". l Pl REF. l P2

. t-ODEL t-ODEL MJDEL f(HZ)

T(SEC) f(HZ)

T(SEC) f(HZ)

T(SEC)

4. 911
  • 202 9.09

.no 7.66

  • f.130 5.112

.104 10.3

.097 8.93

.112 6.61

.151 13.l

.077 1.4

.ouo 6.89

.1115 U.4

.075 17.3

.050 6.90

.143 15.6

.0611 22.l

~Q/15 7.16

.1110 17.6

.057 211.l

.Ottl 0.01

.1111 19.6

.051 27.l

.037 9.00

.110 20.11

.Q/19 31.l

.032 9.116

.106 21.6

.0117 30.3

.026

10. 7

.0911 21.0

.0116 REF. l P3 MODEL f(HZ)

~T(SEC)

-. ~

8.50.

.ll8 10.5

.096 19.6

.051 27.8

.036 20.4

.035 50.4

.020 e

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( "f NODE l

51 57 58 44 72 98 121 122.

123

_55 505 TABLE '.2.
  • cD~PARISCN OF AS!-E a.ASS 2, EQUATION 9,

. STRESS. VALUES -

11CLRR=:NP' 3% DAI.PING SSE -

STRESS (KSI)

OOMBINED

. MOOEL REF. 1 ALLOWABLE COM'vENT

'/f(/15.3

. *9.17 38.2

  • Loop 1 Suet. Line R. v.

20.4 8.0 38.2 Riser* Anchor 11.6*

7.25 38.2 Riser Anchor 10.8

7. 74.

38.2 Riser Anchor 25.8 9.14 38.2 Riser Anchor 21.5 14.5 38.2 Riser Anchor 16~7 14.7 3.8.2 Riser Anchor 13.0 7.16 38.2 Riser Anchor 17.l 7.30 38..2 Riser Anchor 20.l 9.18 38.2 Riser Anchor 14.8 8.58 38.2 Riser Anc.~or 19~2 10.6 38.2 Loop 2 Suet. Line R.V.

Anchor Anchor 655.

l4L6 9~87 38.2 20" Shut Down Line Dry Well Anchor 535 21.0 12.. 0 38.2 tee Intersection 16 19.2 10.7 38.2 Elbow 17

'20. 7 lLO 38.2 Elbow NOTE:

2.
3.
5.

3% Darrping used

  • Allowa::iie Stress (2.4SH) based on SH = 15.9 KSI for ASTM A 358, TP 304 Stainless Steel at 575°F.

Equation 9 Stresses include the effects of pressure, sustained.loads (deadweiGht), and occasional loads (SSE).

Node numbers shown are from the combined model; however, stresses in the "Ref. i" column are from' identica~ points.

Results shown for anchor points a:1d the t.'lree highest stressed points.

u,rougiout the remainder of the model.

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TABLE 3.

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  • SL.PPORT. LOAD OJMPARISON - DRESDEN UNIT 2 *

. tOM3INED RECIRCULAiION t-ODEL SEISMIC.LOADS ONLY SUPPORT LOAD (K) 4:," ;..

Combined tvax. *

  • ~-ti.de Dir.*

M:ldel Ref. l Load Convnent

  • 1a If\\CL 138.

N.A.

30.0

N.A.

30.0

. ia If\\CL 73.3 N.A.

. 30.0 Loop l Pump Snubber

  • 22 INCL 35.2' N.A.

30.0 Loop 1 Pump Snubber 22 HCL 135 N.A.

  • 30.0 Loop 1 Pump Snubber 22 INCL 100' N.A.

30.0 Loop 1 Pump Snuober *

  • 30 UH

.405

.046 4.CO Sway 3race (K = lOOJ l.a/in. )'

33

. LAT 25.4 13.0 10.0 Snuober 65 x

6.04 3.40 Ulknown Rigid 95 x

51.6 19.5 Unknown Rigid 95 z

31.0 16.5 Lhknown Rigid l05 LAT

. 27.5 5.75 10.0 Snubber 135 LAT 26.0

. 9.03 lO.O Snucber 143 LAT

.425

.034 4.CD sway Brace (K = lOJO lb/in.)

305 IN:L...

102.

N.A.

30.0

. Loop 2 Pump Snubber.*

305 INCL 113.

N.A.

30.*0 Loop 2 Pump Snuober 3C5 If\\CL-65.6 N.A.

30.0 Loop 2*?ump Snubber 325 INCL 45.4 N.A.

30.0 Loop 2 ?um;::i Snubber 325 IN:L 71.4 N.A~

  • 30.0

-325

. I~CL 97~7 N.A

' 7 LAT

.410

.091 4.0J Sway 3rece (K = lOCO lb/in.).

  • . 530.

LAT

.347

. 087

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  • 4.CD.

Sway Stace (K = lCDO lb/in.).

. NST23:

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1.

Cirections are globai 2xis orie.ntations. *"Lat" implies "that.this restrainr acts perpendicular to the piping axis in the horizontal plane *of a piping segr.ient t.'1at *is *not oriented parallei to any of the global axis;

. "Incl" implies thar... the rest:rair,t direction *is inclined with respect to the globalcaxes..

'2.:

~bde nurrce:rs shown are from the comoined model; however, loads in the "Ref. 1 11 colui'iln a.re from identical supports at:* identical nodes.

3.
  • 11N.A. 11 *= No.t avaiiable.

Tnese snucbe::::s were nor..included in the*

Reference; l models.

"MAX. LOAD" is !.he maximum recommended load found in vendor catalocs for

~he size *of support component: *csnubbe:r, s*flay bra.ce). indicated on.the

~piping d:rawings.

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  • TABLE 4.

A~l-OR

  • LOAi) ~~FARISO'J - DRESDEN UNIT 2 C0'-1BINED RECIROJ...ATION MJCCJ. - SEISMIC LOADS.ONLY.

LO.!l.D (K o:r In.-K)

C0"1BINED

  • .NOOE DIR.

MJDEL REF. l

. *1.

. *. 51 57

. 44.

x 22.6 9:24 y

.53.7 12.2 z

15.4 7.4 xx

. 2480..

734.

.. YY

  • 2260 *.

612.

zz 179J.

575

  • x 2.58.

.763 y

23.7 2.17.

z 2.97 l.23 xx 135.

51*.o YY 128.

52.7 zz 990.

107.

x

.979

.627 y

7.91 1.26 z

2. 72 1.13

'XX.

275.

61.9 yy...

105.

41.7 zz 274.

  • 55.9.

x..

.376

.281 y

5.0 1.91 z

2."69" 1.24

. xx 298.

. 124.

yy 53~9 24.3 zz 94.4 "34.l X"

. 5.02

.630 y

25.4 3.)4 z

2~19 i.55 xx 5ls.*

116.

. yy 171..

71.2 zz 939.

132.

NOTES:

1.

Directions listed s:::e.~n tt.e ;lcDal coordinate* system. * "X".

implies a farce in ttle glot:3l X direct.ion.

11XX" implies a moment about the glc!:al X ::x.:.s.

  • 2.

N:Jde numbers shown *are f:-=ii:l t:te c:::>m::>ined mocel; hawev~r ~ loads in t:he."Ref. 1 11 colum are f:~m id8ntical anchor points *

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TABLE 4.

Af\\Cl-OR LOAD COt-PARiSON - DRESDEN UNIT 2 COMBINED RECIROJLATION t-ODEL*- SEISMIC LOADS ONLY (Cont."d)*.

LOAD ( K' or. In. -K )

  • COMBINED
    • .NOOE
  • DIR *.

t-OOEL REF 1.

72 98 X*

y z xx yy zz x

y z xx yy 2.48 12.9 1.54 436.

94~0 300.

  • 699 11.7
  • 2.05 471.

128.

25i.*

.900 6.83 1.07.

238.

.47.2 167.

.366 7.62

.* 878 275.

. 29.6 168.

121*

zz x

1.22

.566 122

-i28 NOTES:

y z xx yy zz x

y z

xx yy zz x*

y z

xx YY zz 7.13 4.30 313.

209.

330.

'2.52 15.1 4.74 218.

219.

727.

7.79 17.2 4.97 343.

227..

572.

1.63

  • 765 46.3 35.5 73.5

.838:

2.41

.818 38.2 36.8 93.3 l.88 5.13 1.21

  • 139.

72.5 135..

.L Directions.Hsted are in the glcbai coordinate system.

'.'X" implies a f a*rce in the global X direction; "XX" implies a moment abou~ the. global X axis.

  • 2.. N:Jde numbers shown are from ~he combined mode 1;. however, ioads in the :"Ref. l" coiumn are f:i::om identical ancnor points.

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. TABLE 4.

  • Ar£1-0R LOAD OJWARISON ~ DRESDEN UNIT 2

())"-181Nf::D RECIROJLATION MODEL

~- SEISMIC LO.C\\DS Of'!!-Y *(Cont'd)

.... LOAD (K or In ~-K)

-COvlBINED

  • NOOE.

DIR.*

  • t-ODEL *

.*REF 1 l55.

x 4.80 7.23 4.42 232.

222 *.

335.

1~61.

?.38 1.22

'505 y

z xx.

yy zz.

x y

z.*

xx yy zz 41.3 50.0 14.2 1400.

720.

3600.

104.

77.4-.

93.7 ll.s 11.6 8.39 557.

241.

857.

. 655.

x 10.3 8.65 2,7.5 779.

1630.

313.

3.03 2~74 9.30 NOE:S:

y z

.xx yy zz

.~..

242.

453

  • 71.1
1.

Direct.ions listed. C:re 'in the global coordinate syst~m. "X" implies *a force. in the global x direction.

"XX" impiies.a moment about ~he dlobal X axis~

2.

Node nurribers shown are from the. combined model; however, loads in the "Ref.

  • l" column are from idemical anchor po.rnts.

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. REFEREt-.CES

. M.

E~** Nitzel; "Surmia:ry of the Dresden unit 2 Piping Calculations Pe:rfcrmed for*t.he Systemar.icEvakar.ion Progr?m," EGG-EA-5065,

.N:Jve:rber 1979.

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