ML20094N810
| ML20094N810 | |
| Person / Time | |
|---|---|
| Site: | Beaver Valley |
| Issue date: | 08/13/1984 |
| From: | Woolever E DUQUESNE LIGHT CO. |
| To: | Knighton G Office of Nuclear Reactor Regulation |
| References | |
| 2NRC-4-121, NUDOCS 8408160399 | |
| Download: ML20094N810 (7) | |
Text
-
$VL
~
'A@
(12Is7Isi41 Nuclear Construction Division Telecopy NsIu5ghIP iS25 August 13, 1984 United States Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
Mr. George W. Knighton, Chief Licensing Branch 3 Of fice of Nuclear Reactor Regulation
SUBJECT:
Beaver Valley Power Station - Unit No. 2 Do cke t No. 50-412 Auxiliary Systems Branch Open Items Gentlemen:
This le tter forwards res ponses to Auxiliary Systems Branch (ASB) draf t SER open items 125, 127, 128, 129, 130, 13 3, 13 5, 139, and 148. The res po ns es to Open Items 127, 128, 129, 130, and 133 provide details ditch were not included in the earlier submittal, letter 2NRC-4-099 dated July 2, 1984.
Res pons es to all twenty-eight of the ASB draf t SER open items,122 through 149, have now been formally submitted.
DUQUESNE LIGHT COMPANY By EL/ J. Woolever Vice President JJS/wjs Attachment ec:
Ms. M. Ley, Project Manager (w/a)
Mr. E. A. Licitra, Project Manager (w/a)
Mr. G. Walton, NRC Resident Inspector (w/a)
SUBSCRIBED AND S'9)RN TO BEFORE ME THIS
/e '*' DA,0F
'mg
, 1984, 0
s A
/
Notary Public ELVA G. LESONDAK, NOTARY PUBLfC ROBINSON TOWNSHIP, ALLEGHENY COUNTY MY COMMISSION EXPIRES OCTOBER 20,1986 8408160399 840813 PDR ADOCK 05000412 QQoj E
PDR N1
Un'it:d Stct:0 Nuc10nr Regr1Cttry Cosumis0 ira
~
Mr. Ge:rg3 W. K2ighton, Chicf Page 2 COMMONWEALTH OF PENNSYLVANIA )
)
ss:
COUNTY OF ALLEGHENY
)
On this /d & day of sd
//[
, be fo re me, a Notary Public in and for said Comannwealth and County, personally appeared E. J. Woolever, who being duly sworn, deposed and said that (1) he is Vice President of Duquesne Light, (2) he is duly authorised to execute and file the foregoing Submittal on behalf of said Company, and (3) the statements set forth in the Submittal are true and correct to the best of his knowledge,
iJ
//
... &tary Public
/-
ELVA G. LESONDAK, NOTARY PUBLIC RO8INSON TOWNSHIP, ALLEGHENY COUNTY MY COMMISSION EXPIRES OCTOBER 20,1986 l
l t
1
01 125 THE APPLICANT' STATED THAT, IN GENERAL, CONSTRUCTION JOINTS OF THE EXTERIOR WALLS AND MATS BELOW ELEVATION 730 ARE PROVIDED WITH WATER STOPS. THE APPLICANT SHOULD PROVIDE A DISCUSSION WHICH DEMONSTRATES THAT WHEN USING THE TERM "IN GENERAL" CONSTRUCTION JOINTS... BELOW ELEVATION 730 ARE PROVIDE WITH WATER STOPS, ADE-QUATE PROTECTION FOR ALL SEISMIC CATEGORY I STRUCTURES WILL BE PROVIDED FROM EXTERIOR FLOODS.
RESPONSE
ALL SEISMIC CATEGORY I STRUCTURES WHICH ENCLOSE SAFETY-RELATED SYSTEMS OR COMPO-NENTS IN AREAS AT FLOOR LEVELS BELOW ELEVTION 730'-0" HAVE WATER STOPS PLACED I*i CONSTRUCTION JOINTS OF THE REINFORCED CONCRETE EXTERIOR. THESE WATER STOPS CONTINUE AT LEAST UP TO ELEVATION 730'-0".
THIS TYPE OF FLOOD PROTECTION DOES NOT APPLY TO SAFETY-RELATED COMPONENTS THAT ARE EMBEDED IN CONCRETE BELOW ELEVATION 730"-0", SUCH AS THE FUEL OIL TANKS.
CI 127 PUMPS AND FANS OUTSIDE OF CONTAINMENT WERE EVALUATED FOR THE POTENTIAL OF MIS-SILE CENERATION AS A RESULT OF A FAILURE OR AN OVERSPEED CONDITION.
REGARDING
-PUMPS AND FANS OTHER THAN AFW TDP, NO CREDIBLE MISSILES ARE POSTULATED AS IT WAS CONCLUDED THAT THE MAXIMUM NO LOAD SPEED IS EQUIVALENT TO Tile MAXIMUM OPERATING SPEED OF THE MOTORS THEREFORE A PIPE BREAK OR SINGLE FAILURE COULD NOT RESULT IN A SPEED IN EXCESS OF THE NO LOAD CONDITION (NO OVERSPEED) AND TilUS NO CREDIBLE MISSILES ARE POSTULATED. BASED ON RECENT EXPERIENCE WITil FAN FAILURES RESULTING IN MISSILES, WE REQUIRE FURTHER JUSTIFICATION FROM Tile APPLICANT THAT ADEQUATE PROTECTION IS PROVIDED. THE APPLICANT llAS ALSO NOT ADDRESSED Tile POTENTIAL OF AND CONSEQUENCES TilAT mLLOW Tile FAILURE OF ANY OF Tile FANS INSIDE CONTAINMENT.
RESPONSE
WE DO NOT CONSIDER TilROUGil-FAN-Il0USING MISSILES THAT WOULD DAMAGE SAFETY-RELATED SYSTEMS, STRUCTURES, AND COMPONENTS TO BE CREDIBLE BECAUSE OF Tile mLLOWING REASONS:
1.
Tile ONLY PARTS WHICll MAY BECOME POSSIBLE MISSILES ARE Tile BLADES. TilEREFORE, Tile METil0D OF BLADE ATTACHMENT llAS BEEN INVESTIGATED TO ENSURE TilAT Tile BLADC LOCKNUT TORQUE AND BLADE TIP ANGLE HEET THE MANUFACTURE'S SPECIFICA-TION.
THE MARGIN OF SAFETY FOR Tile ROTOR BLADE ATTACHING BOLTS AND BLADE RIVETS IIAS BEEN Sil0WN TO BE VERY HIGH.
2.
USING Tile CONSERVATIVE BALLISTIC RESEARCH LABORATORY (BRL) FORMULA, WK SilALL 8110W TilAT Tile REQilIRED THICKNESS OF STEEL CASING TO CONTAIN Tile MISSILE IS LOWER TilAN Tile EXISTING FAN CASING TilICKNESS.
IF Tile FAN BLADE DOES BECOME AN INTERNALLY GENERATED MISSILE, Tile ABOVE ANALYSIS WILL DEOMONSTRATE TilAT Tile FAN CASING WILL CONTAIN Tile MISSILE.
OI 128 IN REGARD TO THE AUXILIARY FEEDWATER TURBINE DRIVEN PUMP, IT IS 1.0CATED IN Tile SAFEGUARDS BifILDING AT ELEVATION 718'-6" WITilIN ONE OF Tile TWO CONCRETE ODilPART-MENTS Il0USING Tile TWO REDUNDANT MOTOR-DRIVEN AUXILIARY FREDWATER PUMPS. Tile
00NPARTIENT IS MSIGNED TO CDNTAIM ANY ENERATED MISSILES AND AS 1 RICH TO PREVENT ANY MISSILES,FROM AFFECTING OTNER SAFETY SYSTEM AND THE MOTOR DRIVEN AUEILIARY -
FEEDNATER PUMPSElR.WILL REQUIRE THE APPLICANT TO PROVIDE ADDITIONAL Iltr0RMATION MCARDING THE ADEQUACY OF THE TURBINE MISSILE BARRIER AS INDICATED IN SECTION
'1034.9 0F THIS SER.- INIILE THE SEPARATE CUBICLE ENCLOSURE FOR THE TURBINE DRIVEN FOIN' FROTECTS THE MOTOR-DRIVEN PUMPS FROM POTENTIAL MISSILES ORIGINATING FROM 4
THE TURBINE-DRIVEN PUMP, THE APPLICANT HAS NOT PROVIDED THE RESULTS OF AN ANALYSIS WitICR SHOWS THAT POTENTIAL MISSILES FROM THE TURBINE-DRIVEN AFW PUMP CANNOT DAMAGE OTHER SAFETY-RELATED EQUIPMNT.
RESPONSE
THE AUXILIARY FEEDWATER TURBINE l$ RIVEN PUMP (AFWTDP) IS LOCATED WITHIN A CON-i
! ~ CRETE CDNPARTMENT IN THE SAFEGUARDS BUILDING DESIGNED TO PREVENT ANY 2NERATED j
MISSILES FROM ADVERSELY AFFECTIIIG ESSENTIAL SAFETY-RELATED EQUIPMENT. THE
- ADEQUACY OF THE ODNCRETE BARRIER WAS DETERMINED USING ODNCRETE BARRIER IMPACf TECH:1 QUES AS DESCRIBED IN SECTION 3.5.3.
l.ALL SAFETY-RELATED EQUIPMENT POTENTIALLY IMPACTED BY POSTULATED (AFiffDP) MIS-SILES (1.E., WITHIN THE ZONE OF INFLUENCE AND NOT SEPARATED BY BARRIERS) HAS j' BEEN EVALUATED AND WAS FOUND TO BE NONESSENTIAL FOR ATTAINING AND MAINTAINING A SAFE SHUTDOWN CDNDITION OR MITICATING THE ODMSEQUENCES OF AN ACCIDENT.
l l
01 129 IN REGARD TO THE POTENTIAL FOR MISSILES GENERATED BY PRESSURIEED TANKS AND CYLINDERS DAMAGING OR DEGRADING THOSE ITEMS REQUIRED FOR A SAFE SHUTDOWN, THE APPLICANT STATES AN EVALUATION IS IN PROGRESS, AND THAT FURTHER DOCUMENTATION AND REMEDIAL ACTIONS WILL M ODMPLETED BY THE END OF 1985.
l-
RESPONSE
MON-ASME PRESSURIZED TANKS AND COMPRESSED AIR /CAS CYLINDERS WITH PRESSURE > 275 PSI ARE ODNSIDERED AS CREDIBLE MISSILE SOURCES.
EACH MISSILE SOURCE HAS BEEN IDENTIFIED FOR LOCATION IN A Q.A. I BUILDING OR
(
AREA. THAT AREA WAS EVALUATED FOR ESSENTIAL STRUCTURES, SYSTEMS, AND CDMPONENTS (SSC) REQUIRED FOR SAFE PLANT SHUTDOWN, TO MITICATE THE EFFECTS OF THE ACCIDENT, AND TO LIMIT THE OFFSITE RADIATION DOSAGE WITHIN 10CFR100 ALLOWABLES. WHERE NO ESSENTIAL SSC WERE IDENTIFIED, THAT MISSILE SOURCE REQUIRED NO FURTHER ANALYSIS.
i WHERE ESSENTIAL SSC WERE IDENTIFIED IN THE AREA, AND NO PHYSICAL SEPARATION
' EXISTED M1 WEEN THE ESSENTIAL SSC AND THE POSTULATED MISSILE, THE MISSI!E SOURCE WAS RESTRAINED AND/OR CONTAINED BY THE. SUPPORTING STRUCTURE AND SHIELDS.
l l
01 130, IN RESPONSE TO OUR REQUEST FOR INFORMATION RELATING TO THE POTENTIAL FOR TEMPER-A1URE AND PRESSURE SENSORS INSIDE AND OUTSIDE 00NTAIMMENT MCOMING MISSILES, THE APPLICANT STATES AN EVALUATION IS IN PROGRESS, AND THAT FURTHER DOCUMENTATION AND REMEDIAL ACTIONS WILL M CDMPLETED BY THE END OF 1985.
~
I RESPONSE TEMPERATURE SENSORS INSTALLED IN WELLS WHERE SYSTEM PRESSURE EQUALS OR EXCEEDS 275 PSI ARE EVALUATED. THEREM0 WELLS INSTALLED IN THIS PIPING MAY BECOME MISSILES IF THE FAILURE OF A SINGLE CIRCUMFERENTIAL WELD WOULD CAUSE THEIR EJECTION. TWO RUPTURE LOCATIONS HAVE BEEN POSTULATED.
1.
AROUND THE WELDING BETWEEN THE BOSS AND Tile PIPE WALL.
23 AT THE WELDING BETWEEN THE TEMPERATURE ELEMENT ASSEMBLY AND Tile BOSS WIT 110UT THE WELL ELEMENT, AND THE WELDING BETWEEN THE WELL AND THE BOSS WITH Tile WELL ELEMENT.
THE ANALYSIS OF THE THERM 0WELL INSTALLATION DEMONSTRATES THAT CONSERVATIVE SAFETY FACTORS EXIST MR THE WELD STRESSES FOR THE INSTRUMENT TO PIPE BOSS WELD, THE WELL TO PIPE BOSS WELD, AND THE WELD BETWEEN THE BOSS AND THE PIPE WALL.
BECAUSE OF THESE HIGHLY CONSERVATIVE DESIGN FEATURES, THEREM0 WELLS ARE NOT CONSIDERED AS CREDIBLE MISSILE SOURCES.
PRESSURE SENSORS CONNECTED TO SYSTEM PIPING WHERE Tile PRESSURE EQUALS OR EXCEEDS 275 PSI WERE EVALUATED. THE mLLOWING INSTALLATION DESIGN REQUIREMENTS WERE UTILIZED IN THE EVALUATION:
1.
PRESSURE SENSORS ARE NOT INSTALLED DIRECTLY ON SYSTEM PIPING. THE INSTRU-MENTS ARE INSTALLED USING STAND, WALL, OR RACK ARRANGEMENTS WITil INSTRUMENT TUBING ROUTED TO Tite APPROPRIATE SENSING POINTS WITilIN Tile SYSTEM PIPING.
2.
CELL TUBING AND SUPPORTS FOR PRESSURE SENSORS INSTALLED IN SEISMIC AREAS ARE SEISMICALLY DESIGNED AND ANALYZED.
BASED ON THE ABOVE, Ti!ERE IS NO FAILURE MECilANISM WHIC11 WOULD RESULT IN Tile GENERATION OF A MISSILE.
CI 133 THE APPLICANT'S ANALYSES FOR ALL PIPE BREAK LOCATIONS, INCLUDING PIPE WilIP, JET IMPINGEMENT, FLOODING, AND ENVIRONMENT EFFECTS OF POSTULATED llIGil AND MODERATE PIPE BREAKS ON SAFETY-RELATED EQUIPMENT AND STRUCTURES IN RESPONSE TO OUR QUES-TION 410.10 IS NOT COMPLETE. Tile APPLICANT llAS STATED TilAT Tills INFORMATION WILL BE SUPPLIED AT A LATER DATE.
UNTIL RECEIPT OF ACCEPTABLE INFORMATION AS DISCUSSED ABOVE, WE CANNOT CONCLUDE TilAT Tile APPLICANT llAS ADEQUATELY DESIGNED AND PROTECTED ARRAS AND SYSTEMS REQUIRED FOR SAFE PLANT SilUTDOWN FOLLOWING POSTULATED EVENTS, INCLUDING Tile COMBINATION OF PIPE FAILURE AND SINGLE ACTIVE FAILURE.
RESPONSE
Tile CRITERIA FOR POSTULATING BREAKS AND DETERMINING TilEIR EFFECTS (1.E., PIPE WilIP AND JET IMPINGEMENT) IS PROVIDED IN SECTION 3.6.2.
RESULTS OF Tile PIPE WilIP AND JET IMPINCEMENT ANALYSES ARE TO BE PROVIDED IN SECTION 3.6.2.5.
CURRENTLY, TIIE RESULTS OF Tile PIPE Wil!P ANALYSIS mR Tile mLLOWING LINES ARE PROVIDED IN SECTION 3.6.2.5:
FEEDWATER LINES INSIDE CONTAINMENT FIGURE 3.6B-12 FEEDWATER LINES OUTSIDE CONTAINMENT FIGURE 3.6B-13 MAIN STEAM LINES OUTSIDE CONTAINMENT FIGURE 3.6B-14 a
- THE WORMAT POR THE IPRESENTATION OF. THE RESULTS OF THE JET IMPINGEMENT ANALYSES ALONG WITH
- T50SE OF THE PIPE' WHIP = ANALYSES WAS PROVIDED.TO THE-NRC, IN DLC LETTER 2NRC-4-097. DATED JULY 2,' 1984,: IN RESPONSE TO QUESTION 210.12.
1
[- N.
4 1
017135 1
-THE APPLICANT HAS NOT CONFIRMED THAT IN THE EVENT LIGHT LOADS (THOSE THAT WEIGH LESS;TRAN A FUEL ASSEMBLY.PLUS HANDLING FIXTURE) ARE DROPPED OVER THE FUEL POOL
~
[
OR REACTOR VESSEL FROM THEIR MAXIMUM NORMAL ELEVATION, TilAT THE~RESULTING KINET-LIC ENERGY DOES NOT EXCEED THAT OF A DROPPED FUEL ASSEMBLY AND.ITS ASSOCIATED 1 HANDLING TOOL..~ CONTINGENT UPON OUR RECEIVING SUCH A CONFIRMATION, WE CONCLUDE i
. THAT THE' REQUIREMENTS OF ' GENERAL DESIGN CRITERIA 61 " FUEL STORAGE AND HANDLING AND. RADIOACTIVITY CONTROL" AND 62 " PREVENTION OF CRITICALITY IN FUEL STORAGE AND HANDLING" AND THE GUIDELINES OF REGUIATORY GUIDE 1.13, " FUEL STORAGE FACILITY DESIGN BASIS" POSITIONS C.1, C.3, C.5, AND C.6 ARE-SATISFIED.
RESPONSE
AN ANALYSIS.HAS BEEN PERFORMED THAT SHOWS THAT THE DEVELOPED KINETIC ENERGY DUE TO A' DROPPED.. TOOL EXCEEDS-THAT OF A~ FUEL ASSEMBLY AND ITS ASSOCIATED HANDLING
. TOOL. THE FUEL RACKS WILL BE ANALYZED TO SHOW.THAT THIS CAUSES NO ADVERSE SAFETY IMPACT. - IF THE FUEL RACKS CANNOT WITHSTAND THIS IMPACT,- THE DROP HEIGHT OF THESE LOADS WILL BE LIMITED BY~ ADMINISTRATIVE CONTROL TO A VALUE.SUCH THAT THE KINETIC ENERGY DEVELOPED BY DROPPING THE TOOL IS LESS THAN THAT DEVELOPED BY THE DROP OF i
A FUEL ASSEMBLY AND ITS ASSOCIATED HANDLING TOOL.
01'139 IN RESPONSE TO THE STAFF QUESTIONS REGARDING THE ADEQUACY.OF FLOOD PROTECTION IN THE EVENT OF AN EARTHQUAKE WHEN THE EQUIPMENT AND FLOOR DRAINAGE SYSTEM HAD FAILED,.THE APPLICANT HAS STATED THAT A RESPONSE WILL BE SUBMITTED AT A LATER DATE..
f
RESPONSE
THE FOLLOWING RESPONSE ADDRESSES THIS CONCERN AND IT WILL BE INCLUDED IN AMEND-l MENT 8 AS THE RESPONSE TO QUESTION 410.24.
SINCE BVPS-2 IS DESIGNED WITH A NON-SEISMIC FLOOR DRAINAGE SYSTEM, THE PLANT FLOOD LEVELS HAVE BEEN CALCULATED WITHOUT TAKING CREDIT POR DRAINAGE THROUGH THE FLOOR DRAINS. THEREFORE, IT IS NOT NECESSARY TO VERIFY THAT THE DRAIN SIZE IS SUFFICIENT TO PASS THE MAXIMUM FLOOD CONDITIONS. COMPARTMENTS AND AREAS ~
CONTAINING ESSENTIAL EQUIPMENT ARE EXAMINED FOR POTENTIAL FLOODS.
IN AREA WHERE l
REDUNDANT TRAINS MAY BE EFFECTED, LEAK DETECTION SUMPS ARE EQUIPPED WITH REDUN-DANT SAFETY-GRADE ALARMS LOCATED ABOVE THE FLOOD LEVEL WHICH ANNUNCIATE IN THE
!-. CONTROL ROOM. IN SEALED AREAS WHICH HOUSE ONLY ONE TRAIN OF COMPONENTS, A SINGLE SAFETY GRADE ALARM LOCATED ABOVE THE FLOOD LEVEL WHICH ANNUNCIATES IN THE CON-
' TROL ROOM IS.PROVIDED. THE MAXIMUM FLOOD LEVELS WERE CALCULATED ASSUMING A 30-MINUTE LEAK DURATION, THUS ALLOWING ENOUGH TIME FOR THE OPERATOR TO ISOLATE THE' PROBLEM AREA BEFORE SAFETY-RELATED EQUPMENT ARE ADVERSELY EFFECTED. ELEC-TRICAL EQUIPMENT POWERED FROM THE 1E BUS THAT HAS A POST ACCIDENT FUNCTION WILL j
BE QUALIFIED FOR THE WORST CASE ENVIRONMENT.
SUCH EQUIPMENT WILL BE QUALIFIED
- FOR SUBMERGENCE OR LOCATED ABOVE THE' FLOOD LEVEL.
-. n
___,_._____,____,_,.____,,_._,I
. i THE FLOOR IRAINAGE SYSTEM HAS. EEN EVALUATED POR THE POSSIBLE EFFECTS OF BACK-
-FLOW DURING FOSTULATED FLOODS. THERE ARE INDEPENDENT DRAINAGE SYSTEMS FOR EACH 1 CATEGORY.I BUILDING, WITH THE EXCEPTION OF THE BOTTON ELEVATION'(730'-6") 0F THE SERVICE BUILDING' (SB) DRAINS INTO A SUMP AT THE BOTTOM ELEVATION (718'-6") 0F' i
1THE MAIN STEAM VALVE HOUSE (MV). CONSIDERING THE ELEVATION DIFFERENCE ETWEEN THE MV.AND SB,.AND THE FACT THAT THERE IS NO POSTULATED FLOOD ON THE BOTTOM-
. ELEVATION OF THE SB, THERE IS NO CREDIBLE WAY THAT BACKFLOW THROUGH THIS PORTION LOF THE. BUILDING DRAIN SYSTEM CAN RESULT IN A WORSE FLOOD CONDITION THEN ALREADY CALCULATED. IN AREAS WITHIN THE SAME BUILDING WHERE THERE ARE INTERCONNECTED DRAINS' SERVING REDUNDANT SAFETY RELATED EQUIPMENT, BACKFLOW WILL'BE CONSIDERED AND ALL ESSENTIAL EQUIPMENT WILL E EITHER QUALIFIED POR SUBMERGENCE OR LOCATED ABOVE THE' FLOOD LEVEL.
0I'148 l
~THE APPLICANTS RESPONSE TO OUR REQUEST FOR PERFORMANCE OF A TEST.70 DEMONSTRATE THAT THE POTENTIAL POR FEEDWATER WATER HAMMER HAS EEN ADEQUATELY PROVIDED IS UNACCEPTABLE. IT IS OUR POSITION THAT A TEST IS NECESSARY IN ORDER TO VERIFY r
THE EFFECTIVENESS OF. THE DESIGN PROVISIONS. THEREFORE, WE WILL REQUIRE A COM-MITMENT FOR SUCH A TEST. THE TEST SHOULD BE CONDUCTED AT SYSTEM CONDITIONS AS CLOSE TO THOSE EXPERIENCED DURING NORMAL PLANT OPERATIONS. AUTOMATIC INITIATION
- 0F THE AUXILIARY FEEDWATER SYSTEM SHOULD BE ALOWED TO OCCUR FOLLOWING THE TRIP-PING OF THE MAIN FEEDWATER PUMPS. THE APPLICANT SHOULD OBSERVE AND RECORD THE INITIAL CONDITIONS AND THE TRANSIENT THAT FOLLOWS.- THE APPLICANT SHOULD ALSO PROVIDE PHYSICAL DRAWINGS WHICH ILLUSTRATE THE SYSTEM WATERHAMMER PREVENTION DESIGN FEATURES.
t
RESPONSE
THE NRC STAFF RESPONSE TO THE WESTINGHOUSE COMMENTS ON NUREG-0927 INDICATES THAT THE STAFF AGREES THAT A QUALIFIED DESIGN THAT PRECLUDES SGWH SHOULD NOT REQUIRE TESTING IN-PLANT AT EACH APPLICATION. THE STAFF CONTENDS THAT THE TESTING IS NECESSARY BECAUSE NUMEROUS VARIABLES ARE GENERALLY POUND IN THE IMPLEMENTATION OF THE DESIGN OF THE MAIN AND AUXILIARY FEEDWATER SYSTEMS AT THE DIFFERENT PLANTS.
THE DESIGN OF BVPS-2 WHICH RELATES DIRECTLY TO THE PREVENTION OF SGWH IS THE SAME AS THAT INSTALLED AND PROVEN EFFECTIVE AT BVPS-1 DURING 7 YEARS OF ACTUAL OPERATION. THE STEAM GENERATORS ARE THE SAME DESIGN AS BVPS-1 AND NORTH ANNA UNITS 1 AND 2, THE MAIN AND AUXILIARY FEEDWATER SYSTEMS INJECT WATER INTO THE SG'S VIA THE SAME INTERNAL FEED RING WHICH IS EQUIPPED WITH J-TUBES.
THE FEED-WATER LINE EXTERNAL TO THE SG'S IS DESIGNED WITH AN ELEVATION CHANGE IN THE PIPING WHICH LIMITS THE LENGTH OF INTERIOR AND EXTERIOR HORIZONTAL PIPING DIRECTLY CONNECTED TO THE FEED RING WHICH IS SUBJECT TO DRAINING AND SUBSEQUENT RE-FILLING WITH STEAM WHEN FEEDWATER FLOW IS INTERRUPTED. THE PLANTS HAVE THE SAME CONTROL SCHEME FOR STARTING OF THE AUXILIARY FEEDWATER PUMPS AND THE SIZE
.OF THE AUXILIARY FEEDWATER PUMPS IS^ ESSENTIALLY THE SAME.
I THE TOP DISCHARGING J-TUBES, THE SHORT HORIZONTAL FEEDWATER PIPE CONNECTED TO
' THE FEEDWATER RING AND THE SIZE AND AUTOMATIC INITIATION OF THE AUXILIARY FEED-WATER SYSTEM ARE THE DESIGN FEATURES WHICH RELATE TO THE PREVENTION OF SGWH.
i THE SGWR EVENT STARTS IN THE STEAM GENERATOR WHEN THE FEED RING DRAINS AND STEAM ENTERS.THE RING AND IS SUBSEQUENTLY TRAPPED BY TM ?.DDITION OF SUBC00 LED FEED-
- WATER USUALLY SUPPLIED BY THE AFW SYSTEM. (SEE ST.CdON 2.4.2 0F NUREG-0927 FOR DETAILS) p l
I-
.__._.-.-,_.-_m.
... - - - -.. - _. _ _ _. - - _ _ _ -. _ _. -.... _,. _,