ML18191A813

Wppss Nuclear Project No. 2 Response to Request for Information Main Steam Isolation Valve Leakage Control System

ML18191A813
Person / Time
Site:	Columbia
Issue date:	08/18/1975
From:	Strand N Washington Public Power Supply System
To:	Parr O Office of Nuclear Reactor Regulation
References
Download: ML18191A813 (33)

Text

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NRC DISTRIBUTION FOR PART 50 DOCKET MATERIAL t

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F ROM Washington Public power DATE OF DOC . DATE,REC'D LTR TWX RPT OTHER Supply System Richland, Wash 0

TO Q I OTHER SENTNRC PDR Mr OLan D. Parr I-si ned SENT LOCAL PDR CLASS UNCLASS PROPINFO tNPUT NO CYS REC'D DOCKET'NO:

2QQQQQC 40 50-397 DESCRIPTION: ~ ~

ENCLOSURES:

Ltr notarized 8-18-75 ',trans the followin Concept for Main Steam Isolation Valve Leakage Control System in response to NRC questions P PTQ'P~yxTT m~n v~lg ('40 cys enc', I rec'd)

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P. O. BOX 968 3000 GEO. WASHINGTON WAY RICHLAND, WASHINCTON 92$ 52 PHONE (509) 946.968'I Docket No. 50-397 August 18, 1975 G02-75-238 Mr. Olan D. Parr, Chief Light Water Reactor Project Branch 1-3 4'i 4 Division of Reactor Licensing U. S. Nuclear Regulatory Comission Washington, D. C. 20555

Subject:

WPPSS NUCLEAR PROJECT NO. 2 RESPONSE TO REQUEST FOR INFORMATION MAIN STEAM ISOLATION VALVE LEAKAGE CONTROL SYSTEM

Reference:

Letter, WR Butler to JJ Stein, transmitting Request for Additional Information, dated March 18, 1975 (GI2-75-43).

Dear Mr. Parr:

The attachment provides information requested by the referenced letter.

This information has been provided in a question and response format.

Forty (40) copies of the attachment are being submitted for your review.

Very truly yours, N. 0. STRAND Assistant Director Generation & Technology c9 NOS:GLG:vlm 4 IIq Attachment AI~~(Issue"4r0IIr "IUG.~ -,0 cc: JJ Byrnes - Burns and Roe, Inc. f7 0 11@/

GW Granby - Nuclear Utility Services Corporat on P~CS C0 kf0 FA MacLean - General Electric Company Ig D Roe - Bonneville Power Administration

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Letter, Mr. N!a0. S and to Mr. Olan D. Parr, entitl "Main Steam Isolation Valve Leakage Control System," dated August 18, 1975, Letter No. G02-75-238.

STATE OF WASHINGTON ss COUNTY OF BENTON )

N. 0. STRAND, Being first duly sworn, deposes and says: That he is the Assistant Director, Generation and Technology, for the WASHINGTON PUBLIC POWER SUPPLY SYSTEM, the applicant herein; that he is authorized to submit the foregoing on behalf of said applicant; that he has read the foregoing and knows the contents thereof; and believes the same to be true to the best of his knowledge.

DATED P , >975 N. 0. STRAND On this day personally appeared before me N. 0. STRAND to me known to be the individual who executed the foregoing instrument and acknowledged that he signed the same as his free act and deed for the uses and purposes therein mentioned.

GII/EN under my hand and seal this ZM day of , 1975.

Notary Public in an o th State of Washington Residing at

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Docket No. 50-397 August 18, 1975 G02-75-238 Mr. Olan D. Parr, Chief Light Water Reactor Project Branch 1-3 Division of Reactor Licensing U. S. Nuclear Regulatory Comission Washington, D. C. 20555

Subject:

WPPSS NUCLEAR PROJECT NO. 2 Gc RESPONSE'TO REQUEST FOR INFORMATION MAIN STEAM ISOLATION VALVE LEAKAGE CONTROL SYSTEM

Reference:

Letter, WR Butler to JJ Stein, transmitting Request for Additional Information, dated March 18, 1975 (GI2-75-43).

Dear Mr. Parr:

The attachment provides information requested by the referenced letter.

This information has been provided in a question and response format.

Forty (40) copies of the attachment are being submitted for your review.

Very tr uly yours, N. 0. STRAND Assistant Director Generation 8 Technology NOS:GLG:vlm Attachment cc: JJ Byrnes Burns and Roe, Inc.

GW Granby - Nuclear Utility Services Corporation FA MacLean - General Electric Company D Roe - Bonneville Power Administration

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Letter, Mr. N. 0.- Strand to Mr. Olan D. Parr, entitled "Main Steam Isolation Valve Leakage Control System," dated August 18, 1975, Letter No. G02-75-238.

STATE OF WASHINGTON ss COUNTY OF BENTON N. 0. STRAND, Being first duly sworn, deposes and says: That he is the Assistant Director, Generation and Technology, for the WASHINGTON PUBLIC POWER SUPPLY SYSTEM, the applicant herein; tnat he is authorized to submit the foregoing on behalf of said applicant; that he has read the foregoing and knows the contents thereof; and believes the same to be true to the best, of his knowledge.

DATED

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N. 0. STRAND On this day personally appeared before me N, 0. STRAND to me known to be the individual who executed the foregoing instrument and acknowledged that he signed the same as his free act and deed for the uses and purposes therein mentioned.

GIVEN under my hand and seal this 7H4Z day of , 1975.

Notary Public in anno th State of Washing ton,~c'esiding at

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0 NNP-2 CONCEPT FOR MAXN STEAM XSOLATXON VALVE LEAKAGE CONTROL SYSTEM RESPONSE TO NRC QUESTIONS QUESTION 020.1 {I.a):

Provide the design basis for establishing the capability of the leak control system in terms of what MSXV leakage accommodate.

it can Xnclude information for selecting blower rating and dilution air flow. This information should identify any differences in design considerations between inboard and out-board LCS Systems.

RESPONSE

The MSIV leakage control system, for operating flexibility, is designed to accomodate leakage rates of up to five times the technical specification valve leakage of 11.5 SCFH per valve.

The blower rating for the inboard main steam isolation valves of 50 CFM has been selected based on handling this leakage value. The total leak rate considered would be 230 SCFH or 3.8 SCFM with a dilution air flow of 46.2 SCFM.

Xn addition, a blower size less than 50 CFM was not considered as it would not be a readily available blower size and as such not as reliable a blower.

The same'ating of 50 CFM has been selected for the outboard isolation valves using the above criteria. The main steam

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lines from the outboard main steam isolation valves to the turbine stop valves are designed to ASME Section XII, Class 2 requirements and Seismic Category I requirements. As such, these lines have not been considered to be a source of air inleakage after a design basis accident. The turbine stop valves are high quality low leakage valves and an isolation valve is provided to isolate all auxiliary services of main steam. In addition, air in-leakage from steam traps or process instrumentation into the main steam lines can be readily corrected by maintenance personnel as these areas are accessible.

0 WNP-2 QUESTION 020.2 (I.b):

Specific design criteria should be reviewed and revised as necessary to ensure that they meet quidelines of, Attachment 020-2 and Appendix A to the extent practical for the main steam isolation valve leakage control system (MSIV-LCS).

RESPONSE

The Main Steam Isolation Valve Leakage Control System is designed to meet the guidelines of Attachment 020.2 and Appendix A to the extent practical with the following clari-fications:

l. The system as designed shall direct leakage from the main steam isolation valves to the standby gas treatment system following a LOCA and subse-quent containment pressurization. The isolation valves for this system as shown on DWG. M-557 are located in the steam tunnel. A steam line break may disable both main steam line isolation valve leakage control systems due to the jet forces of the steam break.

However, this system is designed to insure treat-ment of activity releases through the main steam isolation valves after a loss of coolant accident.

After a steam line break and isolation by the main steam isolation valves, the'reactor can be depressurized using the RHR system or the ADS system thus minimizing the release of activity to the environment.

In addition, we do not consider a steam line break in conjunction with a design basis loss of coolant accident feasible.

2. The system as designed does not process MSIV packing leakage. A discussion of the means provided for handling this leakage 'is presented in the answer to question '020.11.

QUESTION 020. 3 (I. c):

Provide information on seismic classification and quality group of motor operated valves which connect to MSIV-LCS piping, (e.g. MS-V-67D and HS-V-20). They represent part of the system boundary and should be compatible with LCS classification.

RESPONSE

Motor operated valves MS-V-67A thru D, globe valves MS-V-25A thru D, MS-V-26A thru D and all other process valves connected to the main steam lines up to the outermost isolation valves are designed to the following classification:

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a. Seismic Category I

b. Quality Class I

c. Code Group A Motor operated valve MS-V-20 and other process valves except the turbine stop valves in the main steam lines downstream of the outermost isolation valve and connected to the LCS system boundary are designed to the following classification:

a. Seismic Category I

b. Quality Class I

c. Code Group B The hydraulically operated turbine stop valves .are 'designed to the following classification:

a. Seismic Category I

b. Quality Class XI

c. Code Group D

I QUESTION 020.4 (II.a):

Provide the design criteria and bases for the Vacuum Breaker MSLC-V-ll and descxibe its flow characteristics to show that steam will not flow thru in the reverse direction if leak control system manifold is at a positive pressure -during the initial depressurization. In the event of momentary reverse flow, state where the discharge is processed by the standby gas treatment system.

RESPONSE

Vacuum Breaker valves MSLC-V-ll and MSLC-V-12 will be designed to the following criteria:

a. Seismic Category I

b. ASME Section III, Class 2

c. Quality Class 1

d. Design Pressure 50 psig

e. Design Temperature 300 F

f. Vacuum Range >4 3 psi

g. Flow 50 cfm The vacuum breaker valve will be a Fisher Vacuum Breaker, Type 734 R-2 or equivalent. This type of valve is used to prevent a vacuum from exceeding a set point. A control line connects the vacuum line and the upper diaphragm casing (See Figure l). The outlet of the body is connected to the vacuum source. An 'increase in vacuum is transmitted to the upper side of the diaphragm causing the inner valve to open.

This permits atmosphere to enter the system restoring the vacuum to the desired point.

During initial depressurization of the main steam lines steam will not flow in a reverse direction thxu the vacuum breaker valve. The positive pressure transmitted to the upper dia-phragm casing will cause the vacuum breaker valve to close.

Steam loss due to momentary steam reverse flow through the vacuum breaker valve is confined to the reactor building in the area near the steam tunnel. Radioactive gases are contained in the reactor building and treated by the standby gas treat-ment system.

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CONTROL TUBINS i'1s LC.-V-ii iow pre.ssuwe.

MAN /FOLD WASHINGTON PUBLIC POWER SUPPLY SYSTEM VACUUhh BREAKER NUCLEAR PRGJECT NO. 2 YALVE

0 1, QUESTION 020. 5 (II.a):

State the design basis and purpose for the separate flow indicator downstream of the inboard system blower and describe any system control function it serves.

RESPONSE

There is no separate flow indicator downstream of the inboard system blower. The combination of dilution arid leakage flow indicators gives total blower flow rate.

1 WNP-2 QUESTION 020. 6 (II. a):

Identify the valves in the main steam line downstream of the outboard LCS. Describe the functioning of these valves in the event of a LOCA.

RESPONSE

The valves downstream of the main steam line outboard LCS are as follows:

a. Turbine stop & control valves

b. 24" isolation valve MS-V-146

c. 3/4" instrumentation root valves

d. Main steam line trap station valves.

These valves are shown on DWG. M-502, Flow Diagram Main and Exhaust Steam System, Turbine Generator Building. In the event, of a LOCA the turbine stop and control valves auto-matically close. Operator action is necessary to close 24" motor operated valve MS-V-l46 to isolate the main steam services to auxiliary equipment and the turbine bypass valves.

This isolation valve is powered from the diesel generator emergency bus.

Instrumentation root valves and trap station valves can be closed manually on indication by Fl-26 of high air leakage in the outboard system. A low dilution flow indication would be indicative of air leakage.

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WNP-2 QUESTION 020.7 (II.a):

Provide additional design criteria and basis for the condensate drain valve MSLC-V-12. Will transient positive pressure in LP manifold during initial depressurization leak steam through this valve. In the event of momentary outflow, provide assurance that discharge steam is processed by the standby gas treatment system.

RESPONSE

The design criteria for check valve MSLC-V-12 is as follows:

a.

S Seismic Category

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b. ASME Section III, Class 2

c. 14" Horizontal Swing Check Valve 150 lb.

ANSI Rating.

d. Design Pressure 50 psig

e. Design Temperature 300 0 F

f. Leakage 3/20 SCF/hour at 10 inches of water vacuum air pressure.

Transient positive pressure in the LP manifold during initial pressurization will cause steam to blow out the water seal and leak through valve MSLC-V-12 to the reactor building. After system depressurization fan MSLC-P-1 is started causing check valve MSLC-V-12 to close preventing air in leakage into the system. During operation of the system, condensate will accumulate and refill the water seal. Valve MSLC-V-12 then acts as a drain valve to drain the condensate to the equip-ment drain system.

Any leakage thru MSLC-V-12 of steam or gases during momentary outflows is directed into the reactor building and ultimately processed by the standby gas treatment system before being discharged to the environment.

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QUESTION 020.8 (III.b)-

Provide a description and PaID for the system connections that will process any steam leakage to the steam tunnel by the standby gas treatment system. Consideration should be given to the design of these connections for the steam line break conditions in the steam tunnel.

RESPONSE

During plant operation steam leakage in the steam tunnel is not processed by the standby gas treatment system. The steam tunnel is a sealed area which is cooled by fan coil units as shown on flow diagram M-545, Heating and Ventilation 6 Air Conditioning, Reactor Building. These fan coil units would condense steam leakage with the condensate being routed to equipment drains located in the steam tunnel as shown on flow diagram M-537, Equipment Drain System Reactor Building.

These equipment drains are open funnel drains which are directed through .a water leg seal to the reactor building equipment drain sump.

A steam leak sufficient to cause pressurization in the steam tunnel would blow out the water leg trap in the equipment drain system and the steam would escape into the reactor building through open funnel equipment drains. However, a leak of this magnitude would cause main steam line valve iso-lation due to a high temperature in the steam tunnel and sub-sequent initiation of the leak detection system. Steam the steam tunnel during operation of the main steam leaks'nto isolation valve leakage control system would escape the steam tunnel throu'gh the equipment drain system and be directed to the reactor building where the radioactive gases would be subsequently processed by the'tandby gas treatment system.

As the equipment drain connections in the steam tunnel are embedded in the surrounding concrete, they can withstand the same steam line break conditions as the steam tunnel.

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QUESTION 020. 9 { III.b):

Provide information on interconnections between MSIV-LCS piping and other plant systems. Figure I indicates that MSIV-LCS piping share a 3 inch main steam line and miscel-laneous 1 Q inch lines with installed plant systems. Describe the effects that these interconnections could have on the intended functions of the MSIV-LCS.

RESPONSE

Interconnections provided between MSIV-LCS piping and other plant systems and their effects on the intended functions of the MSIV-LCS are as follows:

1.'nlet 14 MSLC (2) -4 lines for each inboard main

'steam isolation valve share common 14 MS(9)-4 drain lines. Motor operate'd drain valves MS-V-67 A thru D close automatically by the containment isolation system on a scram signal.

Thus these lines would be isolated prior to placing the MSIV-LCS in operation after a LOCA.

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2. Inlet 14" MSLC(3)-4 line shares the outboard main steam line isolation valve drain header 3" MS(20)-4. Motor operated valve MS-V-20 isolates this header from 14" MSLC(3)-4. This valve is only used during reactor startup to warm up the main steam lines to the turbine.

During normal plant operation As such it is closed.

isolation of this valve is assured during a loss of coolant accident and subsequent utilization of the MSIV-LCS system. Other interconnections and their effects on the intended operation of the MSIV-LCS system are discussed in the answer to question 020.6.

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WNP-2 QUESTION 020.10 {III.b):

Provide the design criteria and basis for the MSIV-LCS motor operated valves which are located in the steam tunnel and provide assurance these valves will be qualified by test to operate satisfactorily in the required environment. Specify the limiting environmental conditions for this area.

RESPONSE

The MSIV-LCS motor operated valves will be designed to the following criteria:

a. Design Conditions MSLC V 2Ai 2Bg 2Cg 2D MSLC V 4 i MSLC V 5 MSLC V 3A~ 3Bi 3Cg 3D MSLC V 9 MSLC V 10 Code ASME-Section Class 1 III, ASME-Section Class 2 III, Seismic Category I I Quality Class I I Pressure Class 900 5 ANSI 900 4 ANSI Design Pressure 1250 psig 1250 psig Design Temperature 575 F 575 F Material Carbon Steel Carbon Steel

b. Environmental Conditions Motor operated valves will be designed to the same environmental conditions as motor operated valves inside containment.

c. Test, Motor operators will be qualified by test to insure satisfactory operation in the required environment in accordance with IEE Standard No. 382, Trial-Use Guide for Type Test of Class I Electric Valve Operators for Nuclear Power Generating Stations.

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QUESTION 020. 11 (III.b):

Include a discussion of how the MSIV-LCS controls MSIV packing leakage;

RESPONSE

The MSIV-LCS- does not process MSIV stem packing -leakage. Stem packing leakage from the main steam isolation valves is directed (See flow diagram M-529, Nuclear Boiler Main Steam System Reactor Building) to equipment drain funnels located in the steam tunnel. These equipment drains are routed to the reactor building equipment drain sump. Low leakage from the stem packing woul'd condense in the piping to the equipment drain.

Leakage large'nough to pressurize the steam tunnel and blow out the water seal traps in the equipment drain system would vent into areas of the reactor building for subsequent pro-cessing by the standby gas treatment system.

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