ML20138B920

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Critical Crack Sizes of Grand Gulf Low Pressure Turbine Disks
ML20138B920
Person / Time
Site: Grand Gulf Entergy icon.png
Issue date: 11/30/1981
From:
ALLIS-CHALMERS CORP.
To:
Shared Package
ML20138B837 List:
References
ER-8105, NUDOCS 8512120412
Download: ML20138B920 (18)
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Text

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( ( ATTA C HMENT 32'

. s-ALL.IS-CHALMERS POWER SYS' REMS. NMC. 7..- 0 r m ENGINEERING REPORT ER-8105 CRITICAL CRACK SIZES OF GRAND GULF LP TURBINE DISKS November,1981 8512120412 851210 6 PDR ADOCK 0500 P

i PROPRIETAfW INFO 8N ATION OF l ALLIS-CH ALA4ERS POWER SYSTEMS.lNC.

Not to be reproduced, cop.ed or dissemenated without the esosess pr6er written consent of k Allis Chatrners Power Systems. Inc. j

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ER-8105 (11/81) r 3 CRITICAL CRACK SIZES OF GRAND GULF LP TURBINE DISKS Critical Crack Evaluation Evaluations of the critical crack sizes achave been performed for disks #1 through #5 of the six LP turbine flows of the Grand Gulf units under the following assumptions:

1. The stress calculations for the disks of the Grand Gulf LP turbines were performed by utilizing finite-element computation to determine the stress distribution within the disks.
2. In particular, the calculations of the local stress concentrations at the keyways are based on this finite-element computation. The evaluation considers the plastic deformation in the vicinity of the keyway during the overspeed test at 125% rated speed. This plastic deformation was the base to define the stress distributions in the keyway' vicinity at rated and 120% speed. The resulting stresses are the basis for the evaluation of the stress intensity.
3. Evaluation of the relationships of the stress intensity versus the crack depth was performed by an analytic method utilizing the WESTERGAARD functions or the integration method BETSY, both of which are computer programmed.

Figure 1E81.137 shows the typical stress distribution in the immediate vicinity of the keyway after the 25% overspeed test. It can be seen that after reaching

. a peak at a crack depth of about one-half inch the stress decreases with increasing crack depth. The stress intensity, however, shows a sustained increase as the crack grows. While the above figure shows only the tendency 1

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^' a is-mas Mes Pows sems.sNc. O ER-8105 (11/81) I r 3 of stress and stress intensity of disk #5 for rated speed operation, the actual results for all five disks at rated speed and 20% overspeed are depicted in the attached drawings 1E81.200 through IE81.209.

4. All fracture toughness values were calculated in accordance with the method defined by ROLF & NOVAK from the yield strength test and the notch impact test minimum results as measured on each specific disk. The maximum and minimum values shown in Figure 1E81.210 are derived from tests on the Grand Gulf disks of units 1 and 2. The maximum values for disk #1 reflect the best of all the minimum values from all twelve #1 disks of the two Grand Gulf 6-flow units. The minimum values are the lowest mechanical properties measured in any of the twelve #1 disks. The same method was used for disks #2 through
  1. 5. It is of importance that the yield strength and notch impact tests were performed at 20 C (68 0F) ambient temperature and some even at -200 C

(-40F). No corrections were performed for the actual operating temperature.

5. Shown in Figure 1E81.210 are the resultant critical crack sizes for the Grand Gulf LP turbine disks. Minimum and maximum values are given for rated speed and 20% overspeed. The calculation assumes a crack shape with a crack length L which is four times larger than the crack depth (a=1/4L). Minimum and maximum crack depths are derived from the minimum and maximum fracture toughness, respectively. Calculations up to a crack of 100mm or 3.94 in. were performed. Critical crack depths in excess of 3.94 in. are tabulated as 3.94 in. cracks. Critical crack depths were calculated and are listed for the keyway and hub vicinity of the disks.

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ER-8105 (11/81) r 3 Data to Assess Crack Growth For evaluating strec 4-corrosion cracking and crack growth risks, design features and manufacturing methods should be taken into consideration. The manufacture and quality assurance for our disk-type rotors have been described in our engineering report, ER-504, which includes the horizontal shrinking procedure. The lubricant used during the shrink-on process of the Grand Gulf disks was DAG156 purchased from the Deutsche Acheson GmbH in Ulm, West Germany.

The lubricant is a product of the U. S. Acheson Company in accordance with the U. S.

specification MIL-L-241318. It is a graphite-base lubricant with an isopropyl alcohol binder and specified solid substance of 3.3% 10.5%. Maximum values of specified l compositions within the solid substance are:

Ash 0.75 %

Fluorine 20 PPM Chlorine 200 PPM

,, Sulfur 200 PPM y

Lead 150 PPM r~.

The shrunk-on disk and the locking pin design are depicted in Figure 1E81.160 indicating that only the disk center, about 60% of the disk hub width, provides the actual shrink fit. The locking pins and their keyways are actually aside from the shrink fit providing a shrink fit area without any stress concentration. Five locking pins are provided equally spaced on the circumference of the disks' exhaust sides. After the disks are shrunk on, the 20mm keyways for the 5 locking pins are drilled into the shafts and disks. To eliminate high stress concentrations at the bottom ends of these keyway bores,large radial relief grooves have been machined in both the disks and shaf ts, as shown in Detail 3

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, ER-8105 (11/81) r 3 A of Figure 1E81.160. The large-radius relief grooves not only minimize the stress concentration at the keyway bottom ends but also provide an area without shrink fit in the keyway vicinity.

To assess stress-corrosion of the Grand Gulf LP turbine disks,it is important to note that we have inspected nuclear turbine disks in the past without finding a single disk crack.

For the performance of stress-corrosion crack-growth evaluations, the calculated steady-state metal temperatures at the shaft-to-disk shrink fit during operation of the Grand Gulf unit with rated steam conditions are:

Disk 1 Admission / Exhaust 333 F/257 F Disk 2 Admission / Exhaust 2570 F/2100F Disk 3 Admission / Exhaust 210 F/1760F Disk 4 Admission / Exhaust 1760 F/1450F Disk 5 0 Admission / Exhaust 145 F/156 F Attachments: Drawings: 1E81.137 1E81.210 1E81.160 1E81.200 through IE81.209 4

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REVISION

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5{ 3'j Crack Depth a(in.)

- ,ji Keyway

' N Ili Diameter 0.79 in.

STRESS AND STRESS INTENSITY VERSUS CRACK DEPTH IN Z.%L"L l KEYWAY VICINITY OF NUCLEAR LP TURBINE  !

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DISK #5 AT RATED SPEED 1E81.137

t

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[ [ A774uMrdr Y Tangential Stresses at Disk Hubs for Various Speeds in Ksi:

REVISIOL

///Rr%

<0 Disk #1 Disk #2 Disk #3 Disk #4 Disk #5 b Zero Speed 60.5 61.9 56.1 61.3 59.3

!C Rated Speed 76.4 80.0 71.8 79.3 77.3 1d 1.2 x Rated Speed 83.4 88.0 78.7 87.2 85.1 ,

tt l i

- Fracture Toughness Min. and Max. Values from Measurements on all Grand Gulf Units 1 and 2 LP Turbine Disks in Ksl6:

Value Disk #1 Disk #2 Disk #3 Disk #4 Disk #5 Min. 170 170 184' 171 171" ,

- Max. 204 212 225 265 201 Critical Crack Depths ac at the Keyways for Min. and Max. Values of Fracture Toughness in inches:

j Min./ Max. Value Disk #1 Disk #2 Disk #3 Disk #4 Disk #5 Rated Speed 1.34/2.24 1.30/2.36 2.01/3.58 1.42/3.94 1.73/2.80

, ] 1.2 X Rated Speed 1.10/1.81 1.02/1.89 1.61/2.80 1.10/3.90 1.34/2.13

' i}l ti 55 ajj Critical Crack Depths se at the Disk Hubs for E33 Min. and Max. Values of Fracture Toughness in inches:

Ein

=a is!

i Min./ Max. Value Disk #1 Disk #2 Disk #3 Disk #4 Disk #5 8*!

[g= yI }- Rated Speed 1.93/2.76 1.77/2.72 2.56/3.86 1.81/3.94 1.97/2.64 ia. 1.2 X Rated Speed 1.65/2.32 1.46/2.24 2.13/3.19 1.50/3.58 1.57/2.17 N8j!

15 li!

l CRITICAL CRACK SIZES m-.e-==

a.

OF GRAND GULF

- LP TURBINE DISKS 1E81.210

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Radius:

R10 = 0.39 in. - = = - -- 9 R22.5 = 0.89 in.

Diameter:

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Y//09e 20#= 0.79 in. .

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Disk #5 LOCKING PINS AND g*,%71*h KEYWAYS OF LP TURBINE r DISKS -

1E81.160

  • g WM[ 5, ' %.4 g $# .% e ,

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g

( kWWCWMfA / 7f Kg g (N/mm a)' (N/mm2)

(Ksl M ) (Ksi) 300--150 seees.o .-1000 -'

REVISION

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C 200--100 t/ Stress intensity Kg

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seee.e 100- 50 j

sese.e 1.0 2.0 3.0 4.0 (in.)

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Crack Depth a 533.0 585.0 900.0 3a M~

l i5 0 a sti og I EE $5E Nuclear LP Turbine 55, 4 EE Disk Type Rotors:

39 0: I Comanche Peak and 2 i El Grand Gulf z! a s .

i3 8.i EM 255 E$ 81$

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s5E STRESS AND STRESS INTENSITY ,m,.._,,,,,,

VERSUS CRACK DEPTH IN - aavar= = =

KEYWAY VICINITY OF DISK #1 AT RATED SPEED 1E81.200 i

' y)Y~fp~f&//ffff'A)f f f

K, , a l K G

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(Kal6.) (Ksi) .

300- .150 9eese.e .-1000 i

REVISIOL '

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Stress 6 b

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Stress intensity Kg C

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1.0 20 3.0 4.0 (in.)

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s.e 'ae.~e ~ ' e.e ~ 'ee.e ee.e (mm)

Crack Depth a 544.0 407.0 900.0

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&( Zl4 STRESS AND STRESS INTENSITY AL.L0e=CHALM Ne VERSUS CRACK DEPTH IN - -N --r===.~e KEYWAY VICINITY OF DISK #2 AT RATED SPEED 1E81.201

- - , .- , - - , , , - , - . _--- - p-. - - + , p._, ,--m -,,-.9%,y.-p.,-,,y,y-,- y,- - - - -

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REVISION -

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Crack Depth a 506.0 562.0 780.0

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d 5b E.his s 25 Os 3 3 {

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Comanche Peak and

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STRESS AND STRESS INTENSITY ,

VERSUS CRACK DEPTH IN 1";".7%iL"".m KEYWAY VICINITY OF DISK #3 AT RATED SPEED 1E81.202

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(Ks1 G.) (Ksl) (N/mmI)

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100--50 1

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0--0 e.e y y 1,0 g N eW ~ %.. ~'.. ~'.. ~'.. ~ %. . . ' ~(mm)

Crack Depth a 4

531.0 592.0 480.0

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ga $5- II{ Nuclear LP Turbine Disk Type Rotors:

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  • Comanche Peak and Grand Gulf

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Ii hiX 8j9 STRESS AND STRESS INTENSITY VERSUS CRACK DEPTH IN U.CO*=*=~. .~e KEYWAY VICINITY OF DISK #4

,, AT RATED SPEED 1E81.203 l

9

.-l ( (Arr/Mrwar f Kg, g Kg g (N/mmT) (N/mm2) '

(Ksl6.) (Ksi)

--- 300--150 **o** 8 -1000 REVISION

////trTE .eee.. . ,, \

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D C 200--100

\k [ stress d g

\ strea intensity Ki d eeee.e .  %

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seen.e .

100--50 sees.e .

1'.0 2.0 3.0 4.0 (In.)

. _ _. 0- 0 e.e .,_,,'

(mm)

Crack Depth a l

I 486.0 547.0 900.0 l.i 255 i nli 35 E3s13( !3; Nuclear LP Turbine Disk Type Rotors:

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jjj Grand Gulf l' .

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v.6 e- a h !1k STRESS AND STRESS INTENSITY _ , _ ,_

VERSUS CRACK DEPTH IN - a - v = r=~

KEYWAY VICINITY OF DISK #5 AT RATED SPEED 1E81.204

  • ', kff/C/// Mfd /*~ y e Kg d I d ) (N/mm8)

(Ksi,6) (Ksi) (N/mm ,

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weee.e .-1000 REVISION ...g

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b

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100- 50 asee.e .

1.0 2.0 3.0 4.0 (In.)

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Crack Depth a 57A.0 585.0 900.0 i

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= l

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  • Nuclear LP Turbine i

5 g EA Disk-Type Rotors:

3 ijj Comanche Peak and 2 1 af Grand Gulf z EE.

jg t,j 55 3 * =

$b SIa Ei!$5 STRESS AND STRESS INTENSITY au.o.-c~aum e.

- e .v=r - ,~a VERSUS CRACK DEPTH IN KEYWAY VICINITY OF DISK #1 AT 20% OVERSPEED 1E81.205

~ ~ ,

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( ( 1 7 rs a m r w K d d (Ksl .) (Ksi) -

-. 300--150 m .. .-1000 4

REylSION 7'g

/N/u 4e '

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s stress intensity Ki b

C

200--100

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d , , , , , , .

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100--50 s.o. .. .

1.0 2.0 3.0 4.0 (In.)

0--O ... . ' '

... _ 'a. .~. .. .. .. in..

(mm)

Crack Depth a 591.0 607.0 900.0 D

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Nuclear LP Turbine 5" 4E( Disk-Type Rotors:

E [ Comanche Peak and 2 2 Grand Gulf z ag.

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STRESS AND STRESS INTENSITY AL. Lee'CHALMEann VERSUS CRACK DEPTH IN - a v=rE== .~e KEYWAY VICINITY OF DISK #2 AT 20% OVERSPEED 1E81.206

. s f A

g

}ff?i C////MT $

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. Kg g Kg ,

(ggg 6) (gst) (N/mmT), (N/mmt) 300--150 s...-1000 flEVISION

/f//tr Te

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stre.. iniensity K, b

c 2e-100 - \\/stre.:d d . . . .

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L 100--50 i

1 i

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2.0 3.0 4.0 (in.)

1.0 '

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  • Crack Depth a I

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sso.o 562.o 7ao.o n.

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=; 51 252 a

1 E! Sik e a.d a< s szi<

._7 d

, 1 j ii d STRESS AND STRESS INTENSITY ,m, .cm ,_ , ,

~~=a=v==~'- -

d VERSUS CRACK DEPTH IN 1

? KEYWAY VICINITY OF DISK #3 AT 20% OVERSPEED 1E81.207  !

.d ca a

~~'

- ---.-m,.-. ,,i = ; s. u x:

1 e

K c- ( srrma, ,

    • gg g is d (Kal M.) (Ksi) (N/mmT), (N/mm2)

- 300--150 -

essee.e .-1000 REVISION

////214e A sees.e . \ St \

8 .

i/\ ress d \

Stress Intensity Kg b

C 2n-1m -

\

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d

, ease.. . Ns

-500 ' ' ' -- , ' -

seen.e .

-10 N seee.e .

; I 0--0 e.e i.e ~ ~ 'se.e ~ .' e.e 'ee .e 'ee .e ~ 'm . e (mm)

Crack Depth a 578.0 592.0 880.0 3%

d Ib

. =0 g ss

.Ey IIE EE

-fa Nuclear LP Turbine o j[2 3dg Disk. Type Rotors:

Comanche Peak and I .Ap&3= Grand Gulf m3 e.

l1525g .

55 2I$

g -: sis s< zl4 STRESS AND STRESS INTENSITY ,m..cmo VERSUS CRACK DEPTH IN ====v==~~

KEYWAY VICINITY OF DISK #4 AT 20% OVERSPEED 1E81.208 l.

' ' ,Y Ks d K, ,

( a

( Arrawee"r r (Ksl G.) (Ksi) (N/mmT) (N/mm2) ,

300--150 <

tesee.e --1000 REVISION :e's

  • Str essd C

200--100 .'

\/

s Stress intensity K g

\

d e.ee..j 's g\

~ ~~~.

seee.e .

100--50 seee.e .

o 1.0 2.0 3.0 4.0 0 -O e.e '

' (In.)

j ._.

,e.e .,. .,_

/ . 'se.e .'ee.e w.e .e.e .e.e .,_

(mm)

Crack Depth a i

533.0 547.0 900.0 lli

, E-

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g "" gna Nuclear LP Turbine 3o o j8:} Eg Disk Type Rotors:

Comanche Peak and E Grand Gulf 13 $ .3 e 5125).

5 8Ek Ei! E$3 1

i

\

i STRESS AND STRESS INTENSITY ALLN9*CHALM Men VERSUS CRACK DEPTH IN --M.--r=~.=

l KEYWAY VICINITY OF DISK #5 AT 20% OVERSPEED

1E81.209

_ _ _ _ _ _ _ _ -

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