ATTACHMENT B

ATWOOD & MORRILL COMPANY, INC. 285 CANAL STREET

SALEM, MASSACHUSETTS 01970

TECHNICAL REPORT TR-2267(a)

* EVALUATION OF THE GINNA AND INDIAN POINT MAIN STEAM ISOLATION VALVE DISCS FOR IMPACT RESULTING FROM PIPE RUPTURE

APRIL 30, 1976

ENGINEERS

303 BEAR HILL ROAD WALTHAM, MASSACHUSETTS 02154

617-890-3350

81f1070665-760528 PDR ADOCK 050002IM41f P PDR

.1

* I

TABLE OF CONTENTS

INTRODUCTION

SUMMARY OF RESULTS

.FLUID DYNAMICS ANALYSIS

3.1 Methods.of Analysis 3.2.,Results of Fluid Dynamics Analysis

STRUCTURAL EVALUATION

DISCUSSION AND CONCLUSION

REFERENCES

APPENDIX A.

A.l A.2 A.3 A.4 A.5

APPENDIX B..

B.l B.2

B.3 B.4

FLUID.DYNAMICS CALCULATIONS

Initial Conditions GINNA and Indian Point MSIV Valve Slam Mass Moment of Inertia Initial Disc Motion Equivalent Disc Translational Velocity

STRUCTURAL EVALUATION

Moment of Inertia for Farley Valve Kinetic Energy of Farley, Ginna and Indian Point Discs Comparison of Kinetic Energy Density Equivalent Strain

LIST OF FIGURES

1. Sketch of Valve After Pipe Rupture

2. Sketch Showing Method of Characteristics

3. Initial Pressure Difference Across Disc

4. Pressure Differential Across Disc vs. Disc Position

5. Disc Centerline Velocity vs. Disc Position

1.01

2.0

3.0

4.0

5.0

6.0

PAGE

3

5

5 9,

15

19

21

Technical Report TR-2267(a)

AOW'T . MAi ERIALS RESEARCH

Technical Report TR-2267 (a)

1.0 INTRODUCTION

At the request of the Atwood and Morrill Company (A&M), Teledyne Materials

K Research (TMR) has performed fluid and structural analyses to determine the

adequacy of a main steam isolation valve. The same valve design is used for several main steam isolation valves (MSIV's), and these are to be installed in two nuclear power plants, the Robert E. Ginna Nuclear Station and Indian Point Unit 2. TMR's analysis was performed to qualify the discs of these swing-disc type valves for impact resulting from a pipe rupture. The analysis for this faulted condition consists of two parts: (1) a fluid dynamic analysis in which the kinetic energy and the impact velocity of the slamming disc are

2 determined and (2) a structural evaluation which involves determining the maximum equivalent strain and compares it to established criteria [1]*. Meeting these criteria, which have been accepted by the U.S. Nuclear Regulatory Com

mission, ensures that fracture will not occur.

The valves analyzed herein are already installed and operating, but their discs are to be modified so that they will be similar to discs used in MSIV's at the Farley Nuclear Station. These discs were qualified by TMR in a previous report [2]. -This disc is a flat disc, as the Ginna and Indian Point discs are now, but it is constructed of 304 stainless steel rather than carbon steel. Also, the rim is thicker, there is a notch on the back side which avoids high strain concentration at this point, and the hole at the center has been eliminated by redesigning the arm which is now much stronger. This new arm allows deformation

of the disc but resists centrifugal and inertial loads during valve closure.

TMR analyzed the Farley disc with the aid of PISCES [3], an elastic-plastic finite difference computer code capable of solving impact problems. Equivalent strains were determined with this code. TMR also reported a method [4] to determine the equivalent strains in other flat discs from the results of the Farley analysis. This report, entitled "Further Interpretation of Farley

*Numbers in brackets correspond to references, Section 6.

Technical Report

TR-2267(a) -2

/ Isolation Valve Closure Analysis", gives a graphical procedure for finding

equivalent strains by comparing the total kinetic energy of the.Farley disc. to that of the disc under investigation. Hence, a new computer analysis of a similar valve may be avoided. The redesigned Ginna and Indian Point valves

are similar but somewhat smaller.

Differences in the nuclear steam supply systems make a new fluid

but these differ from Farley. In the fluid dynamics analysis,.the differential

pressure across the disc, AP, is found. This contributes to the torque, T, on-the rotating system and the velocity at impact is found by numerically

integrating the equation of motion

T =I

where T is the total torque on the rotating system, I is the system mass

moment of inertia, and 6 is the angular acceleration. The kinetic energy is

found from

KE = AP A r de 0

where A is the pressure area of the disc, r is the distance from the center

of rotation at the shaft to the center of pressure. The forward integration is performed in a computer program called IMPACT.

For the analysis, TMR was provided initial conditions of the steam line prior to the pipe break. There is no steam flow just prior to pipe break and the steam is dry saturated steam at a pressure of 1020 psia.

Technical Report TR-2267 -3

K i/ 2.0 SUMMARY OF RESULTS

The fluid dynamics analysis gives the following results.

1.. Centerline velocity of the disc at impact

" VC =-f6. ftsec.

2. Equivalent translationalveloci-ty of the disc for the structural evaluation

V 140.7 ft/sec EQ

3. Kinetic energy at impact

KE = 167,500 ft-lb

For item 2 above, the equivalent translation velocity of the disc is

higher than the actual centerline velocity because the kinetic energy of the

massive arm has been lumped with the disc. This technique is used because it

is conservatively assumed that all of the kinetic energy is dissipated by

strain energy absorption of the disc alone. This is a reasonable assumption since the arm is so rigid.

To perform a structural evaluation, the energy of the Farley system must

be compared to Ginna and Indian Point. The Farley energy is

KE = 225,700 ft-lb

The discs must absorb the kinetic energy by converting it to strain energy.

Since they have slightly different volumes, the kinetic energies will be

normalized by the disc volume to give the energy density. The energy densities

are

- " iV MA- EMALS RESEARCH

Technical Report TR-2267(a) -4

1. For Farley

e : 98.82 ft-lb/in 3

2. For Ginna and Indian Point

3. e =87.0 ft-lb/in

The energy density of Ginna and Indian Point is 88% of the energy density of Farley. Therefore, an evaluation of the Ginna and Indian Point valves can be performed by the methods of Reference 4. The equivalent strains

are

1. For the rim region

E =16.5% < 30%

2. Equivalent strain in the center section

: 9.5% < 18%

The allowable equivalent strains for the rim and the center section are 30% and 18%, respectively. Therefore, the disc will retain its integrity for

the faulted condition.

" eTAYNE SMATERU- RESEAMI:

Technical Report TR-2267(a) -5

3.0 FLUID DYNAMIC ANALYSIS

3.1 Methods of Analysis

It is assumed that there is no flow in the main.steam line prior

to-pipe rupture. The valve disc is held in the open position by the pneumatic

actuator. The steam conditions at the valve are therefore the same as those

in the steam generator.

Dry saturated steam at

Po = 1020 psia TO= 547°F o -- Ref. Appendix A.l

U. = 0.0 ft/sec

Co =1613 ft/sec

where

U0 is the local steam velocity prior to pipe rupture.

C- is the local sonic velocity prior to pipe rupture. 0

It is assumed that the circumferential break occurs just downstream of

the valve. Upon rupture of the main steam line, a pressure rarefaction wave

travels downstream at the local sonic velocity, C = 1613 ft/sec (Figure 1). o Ahead of the leading edge of the rarefaction wave the conditions are the

initial stagnation conditions. Behind the leading edge of the rarefaction wave,

the steam is being accelerated.to the local sonic conditions Pi., Ti, Ci = Ui

at the break. The conditions at the break are found by assuming the steam

behaves as an ideal gas in a constant area duct, one end of which has a

membrane rupture to a vacuum. The method of characteristics may be used

to solve this problem (Figure 2).

1. P. A. Thompson, "Compressible.,Fluid Dynamics", McGraw-Hill, New York, 1972, p.392, Ref. 8.

w W(TEDYN E Technical Report TR-2267(a) -6

Solution of this problem gives the following conditions at the

break

P. = 312 psia I .i = 1427 ft/sec Ref. Appendix A.l

U. =1427 ft/sec

The total disc closing time is approximately 30 msec. In this time the leading edge of the rarefaction wave travels approximately

1613 ft/sec x .03 sec = 48.39 ft

This means that the P. = 312 psia and U. = 1427 ft/sec will be relatively constant during the time in which the valve closes because there is not enough time for a reflected wave from the steam generator to return to the valve. We will ,assume P. and U. to be the initial condition of the steam

1. 1 under the valve disc. Because of the narrow flow. area-about the disc in its fully open position, the steam above the disc is-not affected as the rarefaction wave goes by the disc. This establishes a pressure differential across the disc, tending to push the disc into the high velocity steam path as shown on Figure 3.

Steam escaping about the edges of the disc reduces this pressure dif

ferential and as the disc moves down it increases the volume above the disc which also reduces the pressure differential. Calculations given in Appendix A.4 describe this process for selected time intervals.

The torque about the disc shafi caused by the initial pressure differential overwhelms the resisting torque of the pneumatic actuator as shown on sheets 27-31 of Appendix A.4. The actuator provides just enough torque to support the weight of the disc and therefore has little effect on the disc once the pipe -upture occurs.

' MATERIALS RESEAC Technical Report TR-2267(a) -7

Appendix A.4 calculations show that the AP across the disc drops

off to zero and then becomes slightly negative'after approximately 80 of travel and 6 msec of time. At this point a slight negative pressure differential acts with the actuator to decelerate the disc. However, this deceleration is negligible and the disc momentum carries it into the high velocity steam path at approximately 90 from horizontal at an angular.velocity

of 28.4 radians per second (36.7 ft/sec centerline velocity),.

Once the disc has entered the high velocity steam path, the problem is considered to be a quickly closing valve. There will be a pressure dif

ferential created across the disc first due to profile drag; then, it will transfer to a choked flow condition; and, finally, the effects of a steam

hammer will be experienced. Appendix A.2 presents calculations relating

to these phenomena.

For the disc angle, e, 810 > e > eCR, where 0CR is the disc angle *where choked flow is transferred to the disc, the differential pressure is

2 AP iv

APDRAG K 2g

where:

Ke = drag coefficient, provided by A&M

APDRAG = "Profile Drag"'

This Ke provided by A&M was a conservative estimate based on experimental data; therefore, if the drag AP exceeded the choked pressure differential, the latter was used. A linear interpolation was used between

the values tabulated below:

1. I. H. Shames, Mechanics of Fluids, (New York; McGraw Hill Book Company Inc., 1962), p. 360, Ref. 10.

Technical Report TR-2267(a)

Angle from Vertical

30.000

40.750

50.250

59.500

69.750

78.500

81.000

"PTWDN

Remarks

100.0

16.0

5.78

2.45

1.16

0.649 0.649

Closed Disc

Choking

Choking

Choking

Drag Region

Drag Region

Disc Enters Stream

At the transfer of choked flow to the disc (6 = OCR), the discharge pressure is taken as the critical pressure for choked flow, P*

k

2 k-l P* =P. kT

Ref. Equation 4.15b of Shapiro's

Dynamics and Thermodynamics of

Compressible Fluid Flow

where Pi is the pressure under the disc as found in Appendix A.2 (sheet 9).

AP = P P* CHOKE i

k

APCHOKE = J [1 - 2-$T)

When the disc is closed (e = 30*)

APCLOSE Pi PAT

where:

.AT= atmospheric pressure

MTERALS RSAC

Technical Report TR- 2267(a) -9

The function of AP between the disc angles eCR and 30' is unknown. TMR has assumed an exponential variation.

The differential pressure across the disc due to steam hammer as given by Coccio [11] was used in Appendix A.2 (Sheet ll):

APSH : pCAU

The fluid dynamics analysis assumes that AP varies linearly from 0 to its maximum value during the final 100 of disc closure. It is added to the differential pressure computed for choking during this interval. There is a maximum steam hammer given by Thompson1 which is considered to act on the disc after it has fully closed. Hence, it does not affect the disc velocity at impact.

3.2 Results of Fluid Dynamics Analysis

The pressure differential resulting from the fluid dynamics analysis of the Ginna and Indian Point MSIV's is plotted on Figure 4 versus disc position and, for reference, versus time. TMR's IMPACT program was used to compute the resultant kinetic energy and velocity at disc impact which are as follows:

Kinetic Energy: 167,466 ft-lb

Disc Centerline Velocity: 116 ft/sec (for total disc moment of inertia - Appendix A.3)

Equivalent Translation Velocity for PISCES Disc: 140.7 ft/sec (See Appendix A.5.)

I. Op. Cit.,'p. 323

i' Technical Report TR-2267(a) -10

Figure 5 shows the disc centerline velocity as a function of I position and time. It can be seen that the disc accelerates for the first

5 msecs which is caused by the large initial AP across the disc. As this K pressure difference vanishes at about 8 degrees of travel, the disc velocity

becomes relatively constant. Then., once the disc is inserted into the high velocity steam, the disc velocity begins to increase steadily and reaches

a peak value of 116 ft/sec.

V

ii

(I

.1

Technical Report TR-2267(a) S-11-

I I

Leading edge of

= 1020 psia

= 1613 ft/sec

= 0. ft/sec

rarefaction wave J Po 1020 sia

I escaping / steam

accelerating steam L---zI

r Pipe Rupture

(Sonic Conditions at Break

Pi= 312 psia

C. = U. = 1427 ft/sec

Figure 1. Sketch of Valve After Pipe Rupture

leftward.traveling characteristics

leading edge of expansion fan

sonic condition at break.

Figure 2. Sketch Showing Method of Characteristics

0

7 -7 t 7 .7 7 7 - 7

RESEARCH

0Technical Report TR-2267 (a) -1 2-

Escaping Steam

High Velocity --- j\ Steam P 312 psia

= 1427 ft/sec =32pi

Initial Pressure Difference Across Disc

) I;

Si

I ~1

Figure 3.

Ar"TW RESEARCH

i'I

C",

fl-o

7004

600

500

400

300

200

100

0-13-

Technical Report

TR-2267(a)

8 79 psi

Steam. Disc Position Hammer Ginna MSIV Valve Slam I

Impact Run LBS 22 NU 4/14/76 Bonnet Center Line Velocity 116 ft/sec Energy 167466 ft-lbf Equiv. Trans Velocity 140.7 ft/sec

i(

Choked Flow - . Region

Drag -~Region

00 400 500 600 700 800 9(

Disc Angle Measured from a Vertical Curve

15 23 20 17 13 7 0 Time Milliseconds

Figure 4

Pressure Differential Across Disc

D.

MATERMLS RESEARCH

* Technical Report TR-2267(a)

0-14-

Disc Centerline Velocity vs

Disc Position Ginna MSlV Valve Slam Impact Run LBS 22 NU 4/14/76 Centerline Velocity 116 ft/sec Energy 167466 ft-lbf Equiv. Trans Velocity 140.7 ft/sec

Choked Flow Region

300 400 500 600 700 800 90? Disc Angle

Time 5 23 20 17 13 7 0 Milliseconds

Figure 5

Velocity ft/sec

"OT'TELOYNE MA TERIALS RESEARCH

Technical Report TR-2267(a) -15

4.0 STRUCTURAL EVALUATION

Structural analysis and evaluation for the Ginna and Indian Point MSIV

discs are shown in Appendix B and summarized here.

For the faulted condition, discs in MSIV's close at extremely high

velocities and kinetic energy. Large plastic deformation will occur; hence,

-..stress comparisons are meaningless. On the other hand, strain can be eval

uated to determine if fracture will occur anywhere in the disc.

A relationship between the stress-strain diagram and the initial kinetic

energy enables the analyst to determine the maximum value of strain. Simply

stated, the total kinetic energy at the instant of impact equals the total

strain energy of the disc when it comes to a rest. And since strain energy

is the area under the stress-strain diagram, the strain is found by monitoring

the kinetic and strain energies. The stress and strain due to the applied

differential pressure across the disc are negligible.

The PISCES program was used to obtain accumulated strain components and

equivalent strain in the Farley disc. The final equivalent strain was then

used to determine if fracture would occur-by applying the accepted criteria

[1]. It was found that the Farley disc was well within the limits of the

criteria.

Ginna and Indian Point have valve internals which are similar to the

'Farley MSIV. A comparison of the disc geometric parameters is given in

Table 1. Because of the similarities, it is possible to find the total

equivalent strain in Ginna and Indian Point from the Farley valve by com

paring the kinetic energies. This procedure is presented in Reference 4

where it is stated that the total energy in a valve to be evaluated should be

less than or equal to the maximum kinetic energy of the Farley valve.

Technical Report TR-2267(a) -16

A comparison of the impact parameters is given in Table 2. The disc

centerline velocities are the actual velocities at impact as found from the fluid dynamics analysis. The Farley valve closes with a greater impact

velocity than the Ginna and Indian Point valves.

It is assumed that all of the kinetic energy is absorbed by plastic straining of the disc. This assumption was made for Farley as well as

the present work. This results in the "equivalent translational velocity",

viz.,

MD 2 = KE

where KE is the maximum kinetic energy of the rotating system as found by the fluid dynamics analysis, MD is the mass of the disc, and V' is the

D EQ equivalent velocity to be determined. For this analysis the kinetic energy

of the Farley valve was computed from the above equation using the equivalent

velocity from Reference 2.

The Gihna and Indian Point valves are slightly smaller than the Farley

MSIV. -The discs for Ginna and Indian Point have somewhat less volume, about

16%. This means that the strain energy is more concentrated in the Ginna

and Indian Point MSIV discs; there is less material to absorb the kinetic energy. Therefore, the kinetic energies were normalized with respect to disc

volume for the comparison to give the energy densities.

As seen in Table 2, the energy density of Ginna and Indian Point is 88% of that of Farley. Figure 15'of the Reference 4 report now enables us -to find the equivalent strain for Ginna and Indian Point from the Farley results. The equivalent strains, in the rim region and in the center region, are

.plotted as a function of accumulated strain energy for the Farley valve..

Hence, the equivalent strains for other valves are found from th ,lot by

.I t

Technical Report TR-2267 (a) -17

TABLE 1

Comparison of Geometric Properties

Disc radius, r,

Disc thickness, t

r/t ratio

Disc volume, V

Disc weight, W

System moment of inertia about shaft centerline, I

Pressure area, A

Centerline velocity at impact, VCL

Rotational velocity, w

Equivalent translational velocity, VEQ

Kinetic enqrgy, KE = W VEQ4/2g

Energy density, e = KE/V

Farl ey

13.75 in

3.846 in

3.575 in

2284 in

646 Ibm

255,200 lb-in2

5 2 594 i n

TABLE 2

Comparison of Impact Parameters

Farley

139 ft/sec

104.3 rdn/sec

150 ft/sec

225,700 ft-lb

98.82 ft-lb/in3

Ginna & IP2

12.625

3.846

3.283

1926

545

192,600

501

Ginna & IP2

116.0

89.8

140.7.

167,500

87.0

'- TEMALS RESEAM i Technical Report TR-2267(a) -18

locating the impact energy on the abscissa and finding the corresponding

equivalent strains. Because of the difference in disc volumes, TMR compared

energy densities rather than energy. For the rim region, the equivalent

strain. from Figure 15 of Reference 4 is

~=16.5%

For the center section, the equivalent strain is

= 9.5%

The allowable equivalent strains from the criteria of Reference 1 are 30%

and 18% for the rim and center sections, respectively. Therefore, the discs

will not fail by fracture because of the circumferential pipe break.

0S' Technical Report

TR-2267(a)

WLAI ERIALSRe-EAC

-19-

5.0 DISCUSSION AND CONCLUSION

By comparing the strain energy densities of-the Ginna and Indian:Point

MSIV's, we have found that the disc will not fracture as a result of the

circumferential pipe break. Since the Farley valve qualified for-the faulted'..

condition, the Ginna and Indian Point valves would qualify simply because

their energy density is lower. The body also will qualify for Ginna and

Indian Point by virtue of the fact that the impact energy is less than that

.of Farley. The maximum effective strain in the Farley, valve body is 15%.

Because it is accompanied by a compressive hydrostatic stress state, an

effective strain of up to 29% is acceptable for the carbon steel body...

) 4 - 4 W1-Qa TNTN E0Technical Report TR-2267 (a)

CONCLUSION

It has been found that the Ginna and Indian Point Unit 2 MSiV's will

retain their structural integrity during and after.a circumferential-break

in the main steam line.

-20-

T E RESEARH

TechnicaV Report TR-2267(a) -21

6.'0 REFERENCES

1 1. T. Slot, 0. Batum, and R. A. Genier, "Dynamic Analysis of Steam

Isolation Valve for Closure Under Faulted Conditions", Proceedings C of Third International Conference on Structural Mechanics in Reactor

Technology, London, September, 1975.

.-- .,Teledyne Materials Research Technical Report E-1908, "Dynamic Analysis

of Main Steam Swing Trip Valve for Faulted Conditions, Farley Nuclear

.Power Station", November 15, 1974.

3. PISCES-2DL, Version 3, Manuals A, B and C, Physics International

Company, 2700 Merced, San Leandro, Calif. (1974).

4. Teledyne Materials Research Technical Report TR-2196, "Further

Interpretation of Farley Isolation Valve Closure Analysis", November 5,

01975.

5. Rochester Gas and Electric Specification ME-75, Revision 1, Attachment A,

page 2 of 2.

6. C. A. Meyer, et al., "Thermodynamics and Transport Properties of Steam,

196.7 ASME Steam Tables", Second Edition, p. 298.

7.. F. J. Moody, "Fluid Reaction and Impingement Loads", proceedings of

ASCE Specialty Conference on Structural Design of Nuclear Power Plants,

Chicago, December, 1973, Volume I, p.235.

8. P. A. Thompson, "Compressible Fluid Dynamics", McGraw-Hill, New York,

1972.

9. Crane Company Paper No. 410, "Flow of Fluids through Valves and Fittings",

New York, 1969, p. A-22.

10. I. H. Shames, "Mechanics of Fluids", McGraw-Hill, New York, 1962, p.360.

11. C. L. Coccio, "Steam Hammer in Turbine Piping Systems", presented at

the ASME Winter Annual Meeting and Energy Systems Exposition, New

York City, November 27, 1966.