ML20133F406

Rev 1 to PWR Safety Relief & Block Valve Adequacy Rept

ML20133F406
Person / Time
Site:	Millstone
Issue date:	08/31/1985
From:	Grayson R, Sepp H WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
Shared Package
ML20133F393	List: B11752, Forwards PWR Safety Relief & Block Valve Adequacy Rept, Per NUREG-0737,Item Ii.D.I.Response Providing Analysis of Effect of as-built Relief & Safety Valve Discharge Piping on Valve Operability Also Encl ML20133F406
References
RTR-NUREG-0737, RTR-NUREG-737 NUDOCS 8510110014
Download: ML20133F406 (40)

Text

N  !

PWR SAFETY, RELIEF AND BLOCK VALVE Adequacy Report For Northeast Utilities Millstone Unit 3 Revision 1 August, 1985 Prepared by:

R. M. Grayson J

Verified by 2U . h J

Approved by:

H. A. Sepp, k a[er Pump and Valve Engineering Westinghouse Electric Corporation Plant Engineering Division Box 355 Pittsburgh, Pennsylvania 15230 8510110014 051001 3 PDR ADOCK 050 _

A 1257E:10/082785

- J

e .

Table of Centents Section EARe 1.0 Introduction 1 2.0 Valve and Piping Parameters 3 11 3.0 Valve Inlet Fluid Conditions 4.0 Comparison of EPRI Test Data with Plant-Specific Requirements 4.1 Relief Valve Testing 15 4.2 Safety Valve Testing 15 4.2.1 Crosby 6M6 Safety Valve Tests 16 4.2.2 Discussion of Observed Safety, 17 Valve Performance 4.2.2.1 Loop Seal Opening Response 18 4.2.2.2 Valve Chatter on Steam 18 4.3 Block Valve Testing 19 24 5.0 Ccnclusions Appendix I A-1 A-8 References

)

\

1 1257E:1D/091185 l

- Revision Page Revision pescription Author 0 Original issue R. M. Grayson 1 Incorporate Utility R. M. Grayson Consnents and expand to include Block Valve Information ii 1257E:1D/082785 L.

, o 100 INTRODUCTION Safety and Relief Valves In accordance with the initial recomendation of NUREG 0578, Section 2.1.2 as

) later clarified by NUREG 0737, item II.D.1 and revised September 29, 1981, '

each Pressurizer Water Reactor (PWR) Utility was to submit information relative to the pressurizer safety and relief valves in use at their plant.

Specifically, this submittal should include an evaluation supported by test results which demonstrate the capability of the relief and safety valves to operate under expected operating and accident conditions.

The primary objective of the Electric Power Research Institute (EPRI) test program was to provide full scale test data confirming the functionability of the primary system power operated relief valves and safety valves for expected operating and accident conditions. The second objective of the program was

! to obtain sufficient piping thermal hydraulic load data to permit confirmation of models which may be utilized for plant specific analysis of safety and relief valve discharge piping systems. Relief valve tests were completed in August 1981 and safety valve tests were completed in January 1982. Reports have been prepared by EPRI which document the results of the test program.

Additional reports were written to provide necessary justification for test valve selection and valve inlet fluid test conditions. These reports were transmitted to the USNRC by David Hoffman of the Consumers Power Company on behalf of the participating PWR Utilities and are referenced herein.

Block Valves NUREG-0737 Item 11.0.1.8 requires PWR utilities demonstrate block valves function properly over expected operating and accident conditions. This demsontration is to be supported by test data. _

During a meeting between the NRC staff and utility representatives on July 17, 1981, agreement was reached regarding resolution of the above requirement.

i Details of the utility position on block valve testing is contained in Reference 11. _

1257E:10/082785 1 4

. - , ~ _ , - . _ _ . - - . , m._ . . _ . . _ _ -_._ - . . _ _ _ _ _ _ _ . - - - - - , _ _ - - _ - - - - - __-__,,._,,..s__ - -

In resp:nse ts NUREG-0737 Item 11.D.1.B, Reference 12 transmitted to the NRC

'EPRI PWR Safety and Relief Valve Test Program, PORV Block Valve Information

.'- Package" May 1982 (Reference 13). Incuded in this submittal was:

o A description of block valves used in or planned for use in PWR plants.

o An EPRI report entitled "EPRI/ Marshall Electric Motor Operated Valve (Block Valve) Interim Test Data Report," May 31, 1982.

o A Westinghouse report entitled "EPRI Summary Report: Westinghouse Gate Valve Closure Testing Program," March 31, 1982.

Reference 12 also states that PWR utilities believe sufficient evidence (supported by test data) is available to demonstrate block valve

" operability". Response to the NUREG requirement was to be fulfilled by submittal of the above mentioned document package and a separate plant-specific evaluation of safety and relief valve operability.

This document provides the plant-specific response and evaluation of the Block valve Test program for Millstone 3.

This report provides the final evaluation of these and other submittals and reports prepared during the review of the test data as they apply to the y valves used at Millstone Unit 3.

t 1257E:10/082785 2

$ 2.0 VALVE AND PIPING PARAMETERS 4

? Safety and Relief Valves Table 2-1 provides a list of pertinent valve and piping parameters for the Millstone Safety and Power-Operated Relief Valves. The safety valve and Power Operated Relief Valve designs installed at Millstone Unit 3 were tested by EPRI. Information concerning the valves tested versus valves installed at Millstone 3 is provided in the Valve Justification report.II) The I

justification was developed based on evaluation performed by the valve manufacturers and considered effects of differences in operating 1

characteristics, materials, orifice sizes and manufacturing processes on valve operability.

Typical inlet piping configurations for Millstone Unit 3 are provided in Figures 2-1 and 2-2 Tables 2-2 and 2-3 compare the Millstone Unit 3 inlet loop seal piping configuration with that of the EPRI test piping arrangement for the Crosby 6M6 Safety valve and compares the actual plant-specific pressure drop with the test pressure drop for the test valve arrangement.

As can be seen by these comparisons, the EPRI test piping arrangement envelops the actual piping arrangement for Millstone Unit 3 in that the piping arrangements are similar and the Millstone Unit 3 Plant pressure drops are less than those for the EPRI test valve arrangement.

i Block Valves The Block Valves installed at Millstone Unit 3 are ALOYC0 3'-N-6226-EM0-SP Motor Operated Gate Valves using a Limitorque SMB-00-25 Motor Operator. A l description of the Millstone valve and operator is provided in Table 2-4. The valves are installed upstream of the PORV's and provide a maintenance and blocking function.

i 1257E:10/091185 3

, a TA8LE 2-1 VALVE AND PIPING INFORMATION

1. SAFETY VALVE INFORMATION Number of valves 3 Manufacturer Crosby Valve and Gage Type Self Actuated Size 6M6 Steam Flow Capacity, lbs/hr 420,000 Design Pressure, psig 2485 Design Temperature. *F 650 Set Pressure, psig 2485 Accumulation 3 percent of set pressure Blowdown 5 percent of set pressure Original Valve Procurement Spec. G-678838

2. RELIEF VALVE INFORMATION Number of Vilves 2 Manufacturer Garrett Type Pressurizer Fower Relief Size 3x6 Steamflow Capacity, lbs/hr 210,000 max Design Pressure, psig 2500 Design Temperature, 'F 650 Opening Pressure, psig 2335 Closing Pressure, psig 2315 Valve Procurement Spec. G-955245 1257E:lD/091185 4

TABLE 2-1 (Continued)

.~

VALVE AND PIPING INFORMATION

3. SAFETY AND RELIEF VALVE INLET PIPING INFORMATION Design Pressure, psig 2485 Design Temperature. *F 680 Configuration of Piping 12179-C.1.-RCS-513 12179-C.1.-RCS-516 Pressurizer Nozzle Configuration 12179-C .1.-RCS-513

'12179-C.1.-RCS-516 Steady State Flow -

Pressure Drop See Appendix I - ,

Acoustic Wave Pressure Amplitude See Appendix I

4. SAFETY AND RELIEF VALVE DISCHARGE PIPING INFORMATION Design Pressure, psig 2500 Design Temperature *F 600 Configuration 1548E34 Pressurizer Relief Tank Design Pressure, psig 100 .

Backpressure, Normal, psig 3-5 Backpressure, Developed, psig 500 i

1 5 l 1257E:10/091185 ,

l l

/'

e, s.

'O '

s 6 >

h' +,

l Pressuraer

{'<de(fi~

y, A

~

// i.

_3 E lctk 2- Notec

(, < lic 5

's _" \ 'Yo W{

'/+

/) s N - ,

FIGURE 2-1 Typical PORY Piping Arrangement 1257E:10/061485 6

/

\e% -

\

r her d::!

U

', 5,, el.

N '

• .C N

Y N

s -

~^

% 0 /.. \, \

't \

FIGURE 2-2 TYPICAL SAFETY VALVE PIPING ARRANGEMENT 1257E:10/061485 7

TABLE 2-2 SAFETY VALVE INLET PIPING COMPARISON Typical Millstone Unit 3 6M6 Inlet Inlet Pipina Pipina*

Length of 44.8 61 straight pipe, in.

Number of 90* 4 -

elbows Number of 180* -

2 bends Number of 45* 1 -

Elbows Misc. -

71 i

Loop seal water -

1.02 )

volume I

• Source: Reference (7) )

{

i 1

l I

i 1257E:10/082785 8

m TABLE 2-3 COMPARISON OF TEST PRESSURE DROP WITH PLANT SPECIFIC PRESSURE DROP Millstone Unit 3 Plant Specific

• 6M6 Test **

Pressure Drop Pressure Drop Opening 245.8 263 Closing 144.2 181

• Appendix I

• • Source: Reference (8) 1257E:10/091185 9

TABLE 2-4 ALOYC0 BLOCK VALVE DESCRIPTION General Valve Information Manufacturer.......................ALOYC0 Valves Desc ription. . . . . . . . . . . . . . . . . . . . . . . . Motor Operated Bolted Bonnet Mode 1............................. 3'-N-6226-EMO-SP D rawi ng No . . . . . . . . . . . . . . . . . . . . . . . . . D-51741 General Valve Operator Information Manuf acture r. . . . . . . . . . . . . . . . . . . . . . . Limitorque Desc ription. . . . . . . . . . . . . . . . . . . . . . . .Motori zed Valve Operator Mode 1..............................SMB-00-25 Torque Switch Setting............. 1.0 .

f i

1 1

2

]

)

1 1257E:10/082785 10 l

3.0 VALVE INLET FLUID CONDITIONS

~

Justification for inlet fluid conditions used in the EPRI Safety and Relief Yalve tests are summarized in Reference 2 and 3. These conditions were determined based on consideration of FSAR, extended High Pressure Injection, and Cold Overpressurization events, where applicable.

i For plants of which Westinghouse is the NSSS supplier, a methodology was used such that a reference plant was selected for each grouping of plant considered.(3) Valve fluid conditions resulting from limiting FSAR events. l which result in steam discharge and an Extended High Pressure Injection event l which may result in liquid discharge, are presented for each reference plant.

Use of reference plants result in fluid conditions enveloping those expected for Millstone Unit 3.

Table 3-1 presents the results of loss of load and locked rotor analysis for four loop plants in which Millstone Unit 3 was included. The inlet fluid conditions expected at the safety valve and PORY inlets are identified. As can be seen, the Loss of Load event is considered as the limiting overpressure transient, however, the rate of pressurization is higher for the Locked Rotor Transient for four loop plants.

The limiting Extended High Pressure Injection event was the spurious activation of the safety injection system at power. A condition II event, this will result, as worst, in a reactor shutdown with the plant capable of returning to operatior.. The analysis results fe- four-loop plants are

- provided in Table 3-2.

The cold overpressure fluid inlet conditions considered for the relief valves are provided in Figure 3-3. These conditions ripresent possible water, steam and steam to water inlet conditions for the Millstone Unit 3 PORV's.

The only transients for PORV and Safety Valves identified for Millstone Unit 3 are the FSAR, High Pressure Injection, and cold overpressure conditions.

II 1257E:10/091185

e TABLE 3-1 VALVE INLET CONDITIONS FOR FSAR EVENTS RESULTING IN STEAM DISCHARGE Maximum Maximum Valve Pressurizer Pressure Rate Reference Opening Pressure (psia)/ (psia /sec)/

Plant Pressure (Dsia) Limitina Event Limitina Event Safety Valves Only 4-Loop 2500 2555/ Loss of Load 144/ Locked Rotor Safety and Relief Valves 1

4-Loop 2350 2532/ Loss of Load 130/ Locked Rotor Source: Reference (2) 1257E:10/061485 1}

TABLE 3-2 h SAFETY & RELIEF VALVE INLET CON 0!TIONS RESULTING FROM

[$ SPURIOUS INITIATION OF HIGH PRESSURE INJECTION

,f$ AT POWER WHEN VALVES ARE DISCHARGING LIQUID S '

8!

'n Range of l Valve Fluid Maximum Range of Surge Rates Range of Opening State Pressurizer Pressurization When Valve Liquid Temperature R2ference Setpoint on Valve Pressure Rates Is Passing Liquid at Valve Plant (psia) Opening (a) (psia) (psi /sec) (GPM) Inlet (*F)

SAFETY VALVES 4 -Lcop 2500 Steam / Liquid 2507 0-4 0.0-628.3 567-572

• in i RELIEF VALVES 4-Loop 2350 Steam / Liquid 2353 0 -4 113.1-1104.1 565-569 1

a. First/ subsequent openings I

TABLE 3-3 PORV INLET CONDITIONS FOR COLD OVERPRESSURE TRANSIENTS

}.tigm Steam to Water Water 2350 psi 455 - 2350 psi 750 psi 650*F Sat Temp 70 - 350*F 1257E:10/061485 14

4.0 COMPARISON OF EPRI TEST DATA WITH PLANT-SPECIFIC REQUIREMENTS The Electric Power and Research Institute (EPRI) conducted full scale flow tests on pressurizer safety and relief valves.I4) Tests were conducted at f

three sites over a period of 1-1/2 years. PORVs were tested at Marshall Steam Station (5) and Wyle Laboratories, (6,7) while safety valves were tested at the Combustion Engineering Test Site in Connecticut.II) 4.1 RELIEF VALVE TESTING Test results applicable to the PORVs installed in Millstone Unit 3 are contained in Section 3.9 of Reference 5, Garrett Relief Valve.

This valve fully opened and closed on demand for each of the eleven evaluation tests at the Marshall Test Facility. Sixty-six additional cycles were conducted on the valve at the Marshall Test Facility; results of these tests are provided in the reference (5) report. Ten cycles were conducted at the Wyle Test Facility. Subsequent disassembly and inspection revealed no damage that would affect future valve performance although gasket wash-out was observed after the extensive Marshall testing.

A comparison of the "As-Tested" inlet fluid conditions for the Marshall and Wyle tests is provided in Table 4-1. This table indicates the Millstone Unit 3 fluid conditions summarized in Section 3.0 of this report were tested.

The results of this testing indicates the valves functioned satisfactorily, opening and closing in the required time and discharging the required flow rate. i

)

4.2 SAFETY VALVE TESTING '

l Test results applicable to the safety valves installed at Millstone Unit 3 are l contained in Reference 7.

l l

}

1 1257E:10/061485 15

4.2.1 CROSBY 6M6 SAFETY VALVE TESTS The Crosby 6M6 test valve underwent a series of tests at the EPRI/CE Test Facility. The "As Tested" Fluid Inlet Conditions for the 6M6 are compared to the Millstone Unit 3 Fluid inlet conditions in Table 4-3.

This comparison shows the EPRI "As Tested" Fluid Conditions envelope those for Millstone Unit 3.

Two groups of tests were conducted on the Crosby 6M6 (Loop Seal Internals)

Test Valve, one group with "As Installed" ring settings and one group with

" lowered" ring settings.

For the "As-Installed" ring settings four loop-seal steam tests were conducted, all at pressurization rates far above that expected for the Millstone Unit 3. Two tests were conducted with a cold loop seal, while the other two tests were conducted with 350"F loop seals. Since Millstone Unit 3

' loop seal piping is intact but not water filled, these tests are not representative of the Millstone plant arrangenent.

For the four tests conducted, the test valve popped open on steam at pressures ranging from 2675-2757 psia following a typical loop seal (water) discharge and for the first actuation cycle, the valve stem stabilized and closed with 5.1-9.6 percent blowdown.

For the last test, the valve reopened and the test was terminated after the valve was manually opened to stop chattering. This was a 350*F loop seal test and is not representative of the Millstone Unit 3 inlet conditions.

A transition test with 650*F water was successfully conducted. Subsequently a 550*F water test was tried with the test terminated when the valve started to I chatter.

Seven additional loop seal tests were conducted with " lowered" ring settings as well as two additional transition tests. The results of those tests are detailed in Reference 7. __

1257E:1D/082785 16 l

_ _ _ _ _ _ _ _ _ _ _ - _ . _ _ _ . _ __ _ _ _ _ _ - _ - . _ _ _ _ - . _ - _l

Five cold loop seal steam tests were performed at ramp rates from 3-375

. psi /sec. The valve exhibited typical loop seal openings with the full opening pressures varying from 2580-2732 psia depending on ramp rate. The valve closed in a range of 7.4 to 8.2 percent blowdown.

Two hot loop seal tests were conducted with full opening pressures of s 2655-2692 psia after the typical loop seal opening, and closed with 8.2-9.0

~

. percent blowdown. In the second test the valve reopened and chattered. Again

, this was a 350*F loop seal test at a high ramp rate and is not considered representative of the Millstone Unit 3 inlet conditions.

4.2.2 OISCUSSION OF OBSERVED SAFETY VALVE PERFORMANCE In addressing observed valve performance, one must differentiate between the i valves and fluid conditions tested and the actual valves and actual fluid conditions for the specific plant. The EPRI inlet piping arrangement, flow and acoustic pressure drops, and inlet fluid conditions bound the same plant-specific parameters for the Millstone Unit 3. Valve performance observed during the EPRI tests, therefore, reflects worst case performance as compared to results that would be observed had the testing been conducted using actual plant-specific piping arrangements and fluid conditions.

A review of Table 4-3 shows the Crosby safety valve tested exhibited stable operation on a loop seal piping configuration at pressurization rates of 1.1-375 psi /sec with initial opening pressures of 2455-2600 psi and pop

, pressures of 2455-2757 psi.

Millstone Unit 3 safety valve internals have been changed to the Crosby Flexi-Disc design. This disc design was tested by EPRI on the Crosby 6N8 Test Valve and found to have satisfactory perfornance characteristics. It is therefore believed that the Flexi-disc design will function equally well in the 6M6 valve. One major difference resulting from this change will be the valve will now seat against steam instead of loop seal water as the loop seals will be drained at Millstone Unit 3. This will result in the safety valves opening against steam and will eliminate the characteristic safety valve 4

1257E:10/061485 17

flutter on loop seal water discharge. The inlet piping pressure oscillations l that occur while loop seal water is flowing through the safety valve will thus be eliminated along with the observed higher opening pressures.

The EPRI data also indicates that steam flow rates in excess of rated flows are attainable. However, data also shows these flow rates are delayed some period of time following the assumed valve opening point resulting in the high pop pressures.

Safety valve performance observed in the EPRI tests is addressed in Reference 9 for Westinghouse Plants and the results and conclusions of this report can be extended to Millstone Unit 3.

4.2.2.1 LOOP SEAL OPENING RESPONSE To assess the effect on reactor coolant system pressure due to valve opening l response on loop seal discharge, a series of overpressure transients were run l with various time delays inserted for the valve opening. Results of the analysis are presented in Reference 9. For the limiting Condition II events, i safety valve functioning is not required if the reactor trips on high pressurizer pressure. If the reactor does not trip until the second l protection grade trip, a valve opening delay time of two seconds would still l

provide acceptable overpressure protection. Evaluation of the limiting condition IV event 'shows all components of the reactor coolant system would remain within 120 percent of the system design pressure even in the event of no safety valve opening. This is presented here for information even though delayed safety valve lift is not expected at Millstone Unit 3 for the reasons cited in paragraph 4.2.2 above.

4.2.2.2 VALVE CHATTER ON STEAM Since the EPRI testing was conducted at enveloping fluid and piping conditions, adjustments were made to the safety valve ring positions in order to obtain stable valve performance on steam discharge for the test arrangement. These adjustments resulted in longer blowdowns for-the test valves. The ring positions determined during the test represent the 1257E:10/061485 18

cdjustment requircd for a particular valve when exposed to the particular test piping arrangement, fluid conditions, backpressure and pressurization rate, l

An investigation was conducted to determine those parameters which are critical to the onset of valve chatter under steam discharge conditions. The results of this study are detailed in Reference 9.

i 4.3 BLOCK VALVE TESTING l

l Evaluation testing of seven (7) different Block Valves was conducted at Marshall Steam Station in 1980. The objective of the program was to obtain preliminary information on Electric Motor-Operated (EMOV) Block Valve I performance. Results of this study are provided in Reference 13.

Although the ALOYC0 Block Valves installed at Millstone Unit 3 were not tested as part of the EPRI program the seven valves that were tested represent a l range of gate valve designs similar to that installed at Millstone.

The Millstone Unit 3 Block Valves utilize a Limitorque Model SMB-00-25 Motor Operator. Although this particular Model Motor Operator was not tested by EPRI other Limitorque Model Operators were successfully tested on the various test valves.

Results of the Block Valve testing completed by EPRI appears in Reference (13)

EPRI-Marshall Electric Motor-Operated Valve (Block Valve) Interim Test Data Report. As stated via Reference (12), response to the NUREG requirement was to be fulfilled by submittal of the document package, Reference (13) and this plant-specific submittal.

I 1257E:lD/091185 19

_ _ . - _ _ _ ~ _ _ _ _ _ . _ _ . . _ . _ _ _ _

TABLE 4-1 i.

COMPARISON OF PORV INLET FLUID CONDITIONS WITH 'AS-TESTE0" CONDITIONS Steam Conditions PORV Marshall Test (No.1 - No.11)

Inlet Fluid WVie Test L

2530 2386-2415 2405-2460 Set Point Pressure (psia)

Temperature 650 669-674 (sat.)

(*F) steam steam Fluid Type steam .-

l 210,000 (372,600-378,000) (292,000-303,000)

Flow Rate (1bs/hr)

Water Conditions PORY Wyle Test Wyle Tests Inlet Fluid Conditions 104-GA-85/W (Water) 2350 2460 510-2486 Set Point Pressure (psia) 565-569 650 106-648 Temperature

(*F)

Steam / Water Steam / Water Water Fluid Type (33,927-33,203) 792,000 (8133600-1,681,200) ,

Flow Rate #/hr 1257E:10/061485 20

TA8LE 4-2 TA8ULATION OF OPENING / CLOSING TIMES FOR PORV Opening Time Closing Time Test (Sec.) (Sec.)

Marshall

• 1 1.80 1.00 2 1.70 1.00 3 1.70 1.00 4 1.70 1.00 5 1.60 1.00 6 1.65 1.00 7 1.70 1.95 8 1.70 1.6n 9 1.70 1.50 10 1.65 1.00 11 1.70 1.00

Wyl1**

97-GA-1S 0.25 0.60 98-GA-2S 0.24 0.58 99-GA-3W 0.47 0.78 100-GA-4W 1.09 1.42 101-GA-5W 0.81 1.04 102-GA-6W 0.48 0.75 103-GA-7W 0.56 0.85 104-GA-85/W 0.52 1.18 105-GA-9W/W 0.58 0.92 106-GA-10W/W 0.61 0.90 i

Note: Required Opening Time - 2.0 Sec.

Required Closing Time - 2.0 Sec. -

• Source: Reference (5)

• • Source: Reference (6) 1257E:10/061485 21 l

TABLE 4-3

.+

COMPARISDN OF SAFETY VALVE INLET FLUID CONDITIONS WITH "AS-TESTE0" CONDITIONS Tests 6M6 Safety Valve No. 906-913 Inlet Fluid 917-923, 925 1406, Conditions 1415 and 1419 Set Point 2500 2500 Pressure (psia)

Temperature 650 650

(*F)

Fluid Type Steam loop seal / steam Flow Rate 420,000 *

(1bs/hr)

Pressurization 130-144 1.1-375 Rate (psi /sec) l Stability Stable **

Initial opening 2455-2600  ;

Pressure (psia) i Pop Pressure, 2455-2757 I (psia) l 1

• Rated flow achieved but not reported in EPRI Tables, reference (7).

• • As reported by EPRI in Performance data tables of Reference (7).

l 1257E:10/061485 22

e TA8LE 4-4 MAXIMUM PERMISSIBLE PRESSURE FOR PRESSURIZER SAFETY VALVE INLET PIPING

• Outside Diameter Nominal Permissible Pine Size (in) Thickness (in) Pressure (osi) level B Level C 6-inch Sch.160 6.625 0.719 5229 7131 6-inch Sch.120 6.625 0.562 4004 5460 4-inch Sch.160 4.500 0.531 5733 7818 4-inch Sch. 120 4.500 0.438 4644 6333 1

3-inch Sch.160 3.500 0.438 6119 8344 Source: Reference (9)

• Applicable for temperatures below 300*F.

1257E:10/061485 23

5.0 CONCLUSION

S The preceeding sections of this report and the reports referenced herein indicate the valves, piping arrangements, and fluid inlet conditions for Millstone Unit 3 are indeed bounded by those valves and test parameters of the EPRI Safety and Relief Valve Test Program. The EPRI tests confine the ability '

of the Safety. Relief and Block Valves to open and close under the expected operating fluio conditions.

I 1257E:1D/082785 24

o .

APPENDIX I Plant-Specific Pressure Drop Calculations

1. Transient Flow Pressure Differenc (app) Calculation The flow pressure difference due to pipe friction and fittings is given by:

If T 1 2L/a, (K+f)(CM)2 AP p= 2 2ggpA

- If T >_ 2L/a, 4

(K+f)(CM)2( )2 AP p=

2g pA 2 e

K = sunenation of expansion and contraction loss coefficients corrected if required to correspond to the inlet piping flow area. (NOTE: The contraction from the pressurizer to the inlet pipe can be assumed to be smooth and, therefore, the loss coefficient can be assumed to be-  ;

zero) (dimensirniess) f =

f riction factor (dimensionless) .

~

h = piping equivalent length / diameter considering effects of -

elbow and friction. (dimensionless)

M = rated valve flow rate for steam.

1257E:10/061485 A-1

2

, g.g

= gravitstional const nt (32.2 lb-ft/lb-sse )

. --- p = steam density at nominal valve set pressure (1b/ft3 )

2 A = inlet piping flow area (ft )

i a = steam sonic velocity (ft/sec) - use 1100 ft/sec for all calculations L = inlet piping length (from the pressurizer inside diameter to the interface between the inlet pipe flange and the valve inlet flange)

(ft) i T = valve opening or closing time for steam inlet conditions (sec)

C = flow rate constant for valve opening or closing.

2. Transient Acoustic Wave Amplitude (AP ..)

g Calculation 4

The acoustic wave amplitude is calculated as follows:

- If T $ 2L/a, i a(CM) (CM)

AP g=gg +

2 c 2gC#A

- If T > 2L/a, 2L (CM) (CM) T I

APgg = g gAT +

2 gC#A -

All parameters are defined in Section 1 above.

1257E:1D/091185 A-2

'.* 3. Plant-SDecific Transient Pressure Difference Calculation a

>- The plant-specific transient pressure difference associated with valve opening or closing is equal to the sum of the flow pressure difference (APp ) and the acoustic wave amplitude (APg) as determined above.

4. Plant-SDecific Steady-State Flow Pressure Difference Calculation The steady-state flow pressure difference associated with valve opening or closing is given by:

(K + ) (CR)2 AP p= 2 2ggpA All parameters are defined in Section 1 above. Note that the values of the flow rate constant, C, are different for valve opening and closing.

a. Valve ODening From Table B-2 (Ref. 8), the opening time is, T,p = .010 sec.

Also,

= .0165 sec.

h*1100f/se Therefore, T,p < 2L/a (1) Transient Flow Pressure Difference 1257E:10/091185 A-3

Since T,, < 2L/a, the following pressure difference is,

~

AP p=(K+fLfD)(CR)2 2g pA e

where, N " 420.000 lb/hr-

= 116.7 lb/sec. 3600 sec/hr 4

C = 1.11 K = 0 - see Item 1 above f = .015 L = 9.1 + 1x(16) + 4 x(30) = 157 0 .432 3

p = 7.65 lb/ft A = 0.147 ft The Flow Pressure Difference is, .

2 gp F , IO+( .015) (15711I1.11)(116.7)1 2 64.4 x 7.65 x .147 ,j44 app = 25.8 psi (2) Transient Acoustic Wave Amplitude 1257E:10/091185 A-4

Since T,, < 2L/a, th] Acoustic amplitude is, (CM)2 AP gg gg +

= a(CM) g 2g #A c

(1100) (1.11x116.7) + (1.11x116.7) 1 32.2 x .147 x 144 64.4x7.65x.147 2x144 AP gg = 220 psi (3) Plant-SDecific Transient Pressure Difference The plant-specific pressure difference for valve opening is, AP

app + AP3g

= 25.8 + 220 AP = 245.8 psi (4) Plant-SDecific Pressure Difference The steady-state flow pressure difference for valve opening is, (K + ) (CM)2 AP p= 2 2g pA e

app = 25.8 psi 1257E:10/091185 A-5

. (5) Plant-Specific Pressure Difference for Plant Versus Test

' Evaluation (openina) s' Based on the above, the controlling pressure difference is the transient pressure difference, 245.8 psi.

(b) Valve Closina From Table B-2 (Ref. 8), the closing time is, T = .016 C = .69 CL Also, PL/a = .0165 sec.

T CL 5 016 sec 1 2L/a (1) Transient Flow Pressure Difference is.

AP (K + f) (CM)

F= 2g pA 2

e AP

0. + .015 x 157 x ( .69 x 116.7) 2 F= 2 64.4 x 7.65 x .147 x 144 i

app = 10.0 psi (2) Transient Acoustic Wave AmD11tude Since T CL $ 2L/a, the acoustic wave amplitude is, AP AN =IA a(W , (CM 2 c 2ggpA (1100) ( .69x116.7 ) + ( .69x116.7$

" 32.2 x .147 x 144 64.4x7.65x.147 2j44

~

APgg = 134.2 psi 1257E:10/091185 A-6

(3) Plant-Soecific Transient Pressure Difference The plant-specific pressure difference for valve closing is, AP = app + AP3g = 10.0 + 134.2 = 144.2 psi (4) Plant-Specific Steady-State Flow Pressure Difference The steady-state flow pressure difference for valve closing is the same as for valve opening (25.8 psi)

(5) Plant-Specific Pressure Difference for Plant Versus Test Evaluation (Closina)

Based on the above the controlling pressure difference for Millstone Unit 3 is the transient pressure difference, i.e., 144.2 psi.

1257E:10/091185 A-7

REFERENCES

1. EPRI PWR Safety and Relief Test Program. Valve Selection / Justification Report, " Interim Report, March 1982."

2. Westinghouse Electric Corporation Report, " Valve Inlet Fluid - Conditions for Pressurizer Safety and Relief Valves in Westinghouse - Design Plants",

Interim Report NP-2296-LO, March 1982. '

3. EPRI PWR Safety and Relief Valve Test Program, Description and Status,

" Test Condition Justification Report" Interim Report, NP-2460-LD, June 1982.

4. "EPRI PWR Safety and Relief Valve Test Program, Description and Status",

April 1982.

4

5. "EPRI - Marshall Power-Operated Relief Valve Interim Test Data Report:

EPRI NP-2144-LD, Interim Report February 1982.

f

6. "EPRI/Wyle Power-Operated Relief Valve Test Report, Volume 11" EPRI NP-2670-LD, Interim Report, October 1982.

7. "EPRI/CE PWR Safety Valve Test Report," Volume 6, Interim Report NP-2770-LD, March,1983.

8. "EPRI PWR Safety and Relief Valve Test Program Guide for Application of Valve Test Program Results to Plant-Specific Evaluations", Interim Report, Revision 2 July 1982.

9. " Review of Pressurizer Safety Valve Performance as Observed in the EPRI Safety and Relief Valve Test Program", June 1982.

10. Crane Technical Paper No. 410. " Flow of Fluids Through Valves, Fittings, and Pipe", 1976.

1257E:10/061385 A-8

. -, e

',' 11. LCtter f rom R. C. Ynngdahl, C nsumers Power, to H. Dentin, NRC, dated

,. July 1,1981.

12. Letter f rom R. C. Youngdahl, Consumers Power, to H. Denton, NRC, dated June 1, 1982.

13. "EPRI Safety and Relief Valve Test Progrm PORY Block Valve Information Package", dated May 1982.

1257E:10/082785 A-9

r e eo ATTACHMENT 11 Millstone Nuclear Power Station, Unit No. 3 Analysis of the Effect of As-Built Relief and Safety Valve Discharge Piping on Valve Operability

o .

• 4 ANALYSIS OF THE EFFECTS OF AS-BUILT RELIEF AND SAFETY VALVE DISCHARGE PIPING ON VALVE OPERABILITY NUREG-0737, item II.D.1 requires applicants of pressurized water reactors to verify that pressurizer safety and relief discharge piping will have no adverse effect on valve performance and operability under expected operating conditions. Expected operating conditions are taken as those conditions defined in Reference 1. Millstone Unit No. 3 is equipped with the following hardware:

(a) Three (3) Crosby safety valve (Model 6M6) with a drained loop seal.

(b) Two (2) Garrett power operated relief valves (Model 3750015-1) used for low and high temperature overpressurization relief.

The safety valve inlet piping is shaped in the form of a loop seal, with a drain line located in each loop seal to preclude the discharge of a water slug from the safety valves. The safety and relief valve discharge piping combine to form a common header to the pressurizer relief tank.

The pressurizer safety and relief valve piping was modeled by the Stone &

Webster Engineering Corporation (SWEC) "STEH AM" computer code to predict the transient fluid dynamic forcing functions acting on the pipe segments due to the operation of the valves and the subsequent effects of a steam discharge.

"STEHAM", which was verified by SWEC using manual calculation techniques, computes fluid pressures, velocities, and densities over time using the method of characteristics. Pipe segment unbalanced forces were computed for bounded segments by integrating the rate of change of the fluid momentum within that control volume. This results in plots of segment forces as a function of time.

For open pipe segments, the discharge blowdown forces are included.

Each branch has a single diameter. Thus, for each piping branch with more than one diameter,7 conservative diameter was chosen. The " CHEST" subroutine was used to model the intersections of many branches. This subroutine required a volume input. This input value was approximated by the sum of the volumes of one nodal span along each pipe connected to the chest.

The program selected the integration time steps internally as a function of input segment lengths and the speed of sound.

Three cases were run to generate forcing functions:

(1) Case i modeled the two relief valves opening during an upset condition. The pressurizer started at 2t 00 4 psia and rose to 2575 psia.

The water slug at the relief tank was pushed out causing significant 1 blowdown forces. The safety valves have not yet opened.

r G a4 (2) Case 2 modeled the three safety valves opening during an upset condition. The pressure in the pressurizer started at 2500 psia and rose to 2575 psia. The water slug at the relief tank was pushed out causing significant blowdown forces. The relief valves reraained closed.

(3) Case 3 modeled the three safety valves opening after the relief valves opened and reached a steady state flow condition. The steady state flow condition was input and the pressurizer pressure initialized to 2500 psia. The relief valves remained opened and the peak pressure used was 2575 psia. This modeled the expected sequence of events for an upset condition during the normal operation of the plant.

Fourth and fifth "STEHAM" cases were also run to generate forcing functions due to relief valve closures with the pressurizer pressure at 2400 and 435 psia, respectively. The initial conditions were set with a steady state discharge run and the safe ^y valves remained closed.

The pressurizer relief valve piping was also analyzed using the SWEC "WATHAM" and "WATAIRO" computer codes. These codes were run to generate forcing functions due to relief valve opening and closing during the cold over pressurization protection system (COPPS) operation and were designated cases 6 and 7, respsectively.

In all cases, the valve opening and closing times were obtained from Westinghouse and were at least as severe as those found during the valve performance testing. In addition, the rated flows for each type of valve were derated 90% in accordance with the ASME Code and the analyses were based on 111% of the rated flow.

In the piping areas upstream of the safety valves and downstream of all valves, Case 2 produced the bounding forcing functions. In the area upstream of the relief valves, Case 7 produced the bounding forcing functions.

These bounding forcing functions were digitized and applied to the structural model in the form of a time history analysis. When more than one forcing function was developed for a pipe segment, as in the case where both " acoustic wave" and " blowdown" forces er.ist, they were applied simultaneously to account for dynamic af fects.

The subsequent stress analysis of the piping system was completed using the NUPIPE-SW computer program which was verified by comparison to programs presently benchmarked by the NRC. The method of analysis, load combinations, and stress allowances used were as delineated in Reference 1.

As a result of the NUPIPE-SW analysis, the piping has been qualified to be in accordance with Reference 2. In addition, the support loading resulting from this analysis have been quallfled in accordance with Reference 3.

l

.b

'~_

~o !.. o

REFERENCES

1. Millstone' Unit No. 3 Final Safety Analysis Report.

2. - ASME Boller and Pressure Yessel Code,1971 Edition, Addenda through Summer 1973.

3.. AISC Steel Construction Manual, Seventh Edition.

. _ _ _ _ - _ _ _ _ _ _ _