ML13317A777
| ML13317A777 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 12/09/1981 |
| From: | Baskin K Southern California Edison Co |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| GL-81-014, TAC-43664 NUDOCS 8112160092 | |
| Download: ML13317A777 (26) | |
Text
Southern California Edison Company P. 0. BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD. CALIFORNIA 91770 K. P. BASKIN TELEPHONE MANAGE OP NCLEARENGENERING MANAGER FI NUCLDARCENGRI NG, December 9, 1981 (213) 572-1401 Director, Office of Nuclear Reactor Regulation Attention: D. M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing U. S. Nuclear Regulatory Commission Washington, D.C.
20555 Gentlemen:
Subject:
Docket No.
50-206 Generic Letter No. 81-14 Seismic Qualification of Auxiliary Feedwater Systems San Onofre Nuclear Generating Station Unit 1 Generic Letter No. 81-14, which was dated February 10, 1981 and received by us on June 9, 1981, requested certain information regarding the seismic qualification of the auxiliary feedwater system at San Onofre Unit 1.
In addition, the letter requested that we perform a walkdown of the nonseismically qualified portions of the auxiliary feedwater system to identify apparent and practically correctable deficiencies that may exist.
The purpose of this letter is to provide the requested information. provides a description of the auxiliary feedwater system, a summary of the seismic design criteria for the system and a listing of available seismic qualification documentation for the various components in the system. This information is provided in response to Enclosure 1 of Generic Letter No. 81-14. provides a summary of the walkdown of the auxiliary feedwater system performed in response to Enclosure 2 of Generic Letter No. 81-14. All identified deficiencies from this walkdown are identified in. Based on the observations from this walkdown, certain actions were identified which could enhance the seismic resistance of the auxiliary feedwater system.
These actions are summarized in Section F of Enclosure 1.
It should also be noted that the auxiliary feedwater system and its associated structures, piping and equipment are currently being evaluated to O.67g Housner as part of the San Onofre Unit 1 Seismic Reevaluation Program.
The schedule for completion of these evaluations and for implementation of any modifications which are required as a result of these evaluations was provided in our letter dated November 3, 1981.
8112160092 81120Y PDR ADOCK 05000206:
P PDR
Mr. D.
December 9, 1981 As discussed in Enclosure 1, the discharge side of the auxiliary feedwater pumps has been seismically designed. For the suction side, the system walkdown discussed in Enclosure 2 has identified certain modifications which will be implemented to enhance the seismic resistance of the system.
Furthermore, an alternate decay heat removal path, as discussed in, is available to remove decay heat. Finally, the auxiliary feedwater system will be analyzed and modified as required as part of the Seismic Reevaluation Program. Based on this information and the low probability of a large earthquake occurring in the time period until required modifications are implemented, it is concluded that San Onofre Unit 1 can continue to operate without undue risk to the health and safety of the public.
If you have any questions on any of this information, please let me know.
Subscribed on this day of r
1981.
Very truly yours, By K. P. Baskin Manager of Nuclear Engineering, Safety, and Licensing Subscribed and sworn to before me this day of A 1981.
Notaryf/Jyublic' in and for the County of Los Angeles, State of California Enclosures AGNES CRABTREE NOTARY PUBLIC - CALIFORNIA PRINCIPAL OFACE IN LOS ANGELES COUNT MY Contissio Exp. Au&.27.1982
ENCLOSURE 1 SEISMIC QUALIFICATION OF AUXILIARY FEEDWATER SYSTEM SAN ONOFRE UNIT 1 A.
INTRODUCTION In accordance with NRC Generic Letter No.
81-14, this report provides information identifying the extent of seismic qualification of the Auxiliary Feedwater (AFW)
System at San Onofre Unit
- 1.
In order to facilitate understanding of the San Onofre Unit 1 AFW System, this report first provides a description of the system and of the system boundaries considered in this evaluation and a summary of the seismic design criteria applicable to the various parts of the system.
The report then provides detailed information regarding the seismic qualification of the AFW System components.
- Finally, specific actions are identified which will be implemented to enhance the seismic resistance of the system.
B.
BACKGROUND The AFW System at San Onofre Unit 1 was originally designed as a non Seismic Category A manually operated system consisting of two auxiliary feedwater
- pumps, one motor driven and one steam driven, with common suction and discharge piping and valves.
Condensate was drawn from the condensate storage tank and was supplied to the feedwater piping upstream and downstream of the high pressure feedwater heater.
Flow control of the AFW System was provided by the main feedwater bypass control valves which are operable from the control room.
Normally closed isolation valves in the pump discharge piping required manual operation to align the system.
-2 As a result of the evaluation of high energy line breaks outside containment, the system was modified by adding emergency auxiliary feedwater lines consisting of three branches which-joined the main feedwater lines downstream of the feedwater control valves.
Normally closed isolation valves in both the normal AFW and emergency AFW lines were required to be opened manually to supply water to the feedwater system.
As a result of TMI related requirements, the AFW System was upgraded to its current configuration which includes automatic initiation, redundant flow paths, and seismic qualification of the upgraded portions of the system as discussed below.
The piping downstream of the AFW pumps was revised by adding a motor operated valve, operable from the control room, to the piping downstream of the high pressure heater.
The piping upstream of the heater is isolated by a manual locked closed valve.
The three emergency auxiliary feedwater lines were removed and replaced with seismically qualified piping and valves having redundant flow paths and controls.
A seismically qualified control system was provided to automatically initiate auxiliary feedwater flow on low water level indication in two out of three steam generators. In addition, a redundant water source was added to the AFW system by running a hose from the fire protection system to the suction of the south AFW pump.
This source is initiated by opening a looked closed valve at the connection to the AFW pump suction and a manual valve at the connection to the fire water system.
When flow has been stabilized, a valve in the AFW suction can be closed isolating the pump from the condensate storage tank.
C. SYSTEM BOUNDARIES For the purpose of this evaluation, the AFW System boundary has been taken as all piping and valves from the AFW suction (including the condensate storage and primary plant make-up tanks) to the steam generators and all connected branch piping up to and including the first valve which is normally closed or capable of automatic or remote-manual closure.when the safety function is required..
All branch piping that is structurally coupled to the AFW System out to the first point of three orthogonal restraints has also been included.
The connected piping on the pump suction leading to the condenser, through the condenser level control valves, has no method of remote isolation and has been considered up to its connections to the condensers. The primary plant make-up pump branch piping has been excluded from consideration since this system serves as backup to the condensate storage tankrequiring manual action to be placed inservice and can be isolated at the condensate storage tank.
All control valves, instruments, solenoid.valves, switches, alarms, indicators and control logic boards, along with necessary electrical power supplies and motor controllers required for system initiation and control, have been included within the AFW System boundary. Piping supports, cable trays and electrical conduits along with necessary supports have been included.
In addition, structures whose postulated failure could have an effect on the AFW System performance have been reviewed.
D. SEISMIC DESIGN CONSIDERATIONS The following means were used to identify the status of the seismic quali fication of components of the AFW System:
(1) A review was made of the Final Safety Analysis (FSA) to determine the seismic classification of the AFW system components.
Design criteria manuals prepared for backfit projects undertaken since original plant construction were also reviewed.
(2) Available equipment specifications were reviewed to determine specification requirements for seismic testing or other means of qualification.
(3) Available test reports or design calculations were reviewed.
The portions of the AFW System, and the structures housing this system and its components, which were designed or procured to Seismic Category A requirements are considered to be seismically qualified. The applicable Seismic Category A design criteria provisions for a specific component are either Section 9.2 of the FSA (for structures, systems and components which were -designed and installed in conjunction with the original plant facility), or project design criteria manuals (for structures, system and components which were designed and installed in conjunction with plant modifications).
-5 For the original plant structures, systems and components, Section 9.2 of the FSA provides that all Seismic Category A components, systems, and structures be designed in accordance with the following criteria:
- 1.
Primary steady state stresses when combined with seismic stresses were maintained within the allowable working stress range based upon the response to a ground motion having a maximum acceleration of 0.25g.
- 2.
Combined stresses, including seismic stresses based upon the response to a ground acceleration of twice the above value (0.5g), were such that the function of the component, system, or structure would not be
- impaired, and a safe and orderly shutdown of the plant would be assured.
- 3. The analysis of the dynamic loads imparted by the maximum ground acceleration resulting from an earthquake was performed using the response spectrum approach.
This analysis was applied for all components and structures considering their natural periods and using appropriate damping factors. The horizontal components of the ground acceleration were taken directly from the response spectra curves and the vertical components were taken as two-thirds of these values.
-6 For systems and components which were designed and installed in conjunction with plant modifications, the appropriate project design criteria manual specifies seismic design requirements.
For AFW System piping and components installed as a result of TMI related requirements, the design criteria manual specifies.a minimum design value of 0.5g Housner DBE and 0.25g Housner OBE.
In actual fact, the majority of piping and equipment were designed and procured to 0.67g Housner DBE and 0.33g Housner OBE.
E.
SEISMIC QUALIFICATION OF THE AUXILIARY FEEDWATER SYSTEM Table 1 provides a listing of all the components in the AFW System, an identification of the seismic category of each component, a summary of available information regarding seismic qualification and identification of whether electrical components were included in the scope of,_ IE Information Notice 80-21.
The AFW System components identified in Table 1 were not included in the scope of IE Bulletins 79-02, 79-04, 79-07, and 80-11.
Only the Main Feedwater and Main Steam piping inside containment were included in the scope of IE Bulletin 79-14.
Specific seismic qualification methods are identified in the footnotes of the table.
Non-seismically qualified portions of the AFW System are identified in Table 2. All of the components listed in Table 2 were examined during a plant walkdown conducted to identify apparent and practically correctable deficiencies that exist.
A description of the walkdown and of the information obtained is provided in Enclosure 2.
Specific actions being taken as a result of the walkdown are identified in 'Section F of this report.
-7 F. CORRECTIVE ACTIONS Based on the review of available qualification information and the plant walkdown, various deficiencies in the seismic resistance of the AFW system were identified.
Each of these deficiencies along with planned corrective actions are described in the following paragraphs.
Where additional piping supports are identified, these supports will be installed without detailed seismic analysis to provide increased seismic resistance with consideration of installation limitations.
It is our intention to implement these modifications during the first plant outage of sufficient duration following completion of design and procurement.
It is anti cipated that this will permit implementation at the same time. as the turbine building modifications currently discussed in Item 9 below; i.e.,
by June 1, 1982.
In the interim, until these modifications are implemented the alternate decay heat removal method discussed in Enclosure 3 and the low probability of a large earthquake ensure that the plant can be operated without undue risk to the health and safety of the public.
- 1.
Primary Plant Makeup Piping -
West of Turbine Building Line 711-3-HP from the primary plant makeup pumps to the penetration through the turbine building wall is not considered to have adequate seismic support.
U bolts will be added to existing structural supports in this area.
-8
- 2.
Condensate Storage Tank This tank has no apparent hold-down bolts.
In the event of loss of this tank, water could be supplied to the AFW pumps through the fire hose attached to the south pump.
Since additional support is being provided to the fire water pump suction piping as discussed in Item 5 below, this piping will have additional seismic withstand capability.
Therefore, modification of this tank will be considered following completion of the Balance of Plant Mechanical Equipment and Piping (BOPMEP)
Seismic Reevaluation Program.
The schedule for completion of this evaluation and for implementation of any required modifica tions is provided in our July 7, 1981 and November 3, 1981 letters.
- 3.
Primary Plant Makeup Tank This tank serves as a backup to the condensate storage tank and is isolated from that tank by a normally closed, hand-operated gate
-valve.
Any modification to this tank will be considered following completion of the BOPMEP Seismic Reevaluation Program as discussed above for the Condensate Storage Tank.
-9
- 4.
Primary Plant Makeup Piping -
Along South Wall of Turbine Building to Condensate Storage Tank Lines 711-3-HP and 700-3-HP along the south wall of the turbine building and out to the condensate storage tank are supported by hanger rods with trapeze supports.
Additional stiffening will be added to these lines.
- 5.
Service Water Line -
To Fire Pumps The service water line along the turbine building wall from the pipe tunnel to the fire pumps is considered to have inadequate seismic support.
Additional lateral support will be provided by adding U-bolts on the structural steel supports and in the area of the fire pumps.
- 6.
Auxiliary Feedwater Suction Line The auxiliary feedwater pump suction is taken from the condenser level control manifold piping. ' This piping is supported for weight loading only.
Additional lateral support will be provided to the supply line (721-10-HP) and to the condenser leads.
-10
- 7.
Condenser Level Control Manifold Currently there is no isolation of the auxiliary feedwater suction piping from the condenser level control manifold piping.
Remote manual isolation valves on the lines to each of the condensers will be considered following completion of the BOPMEP Seismic Reevaluation Program as discussed above for the condensate storage tank.
- 8.
Steam Supply Control Valve The steam supply control valve (CV 113) to the turbine driven auxiliary feedwater pump is considered to have inadequate seismic support on its control mechanism.
Additional support of the controller will be provided.
- 9.
Turbine Building The north extension and west heater platform of the turbine building were designed for a 0.2g earthquake.
However, as described in our August 11, September 28 and October 19, 1981 letters, these structures are capable of withstanding ground motions in excess of this design value. Modifications to the column to girder connections in the north extension have been implemented as discussed in our September 28, 1981 letter.
Additional bracing will be provided to the north extension and west heater platform.
Installation will be implemented prior to June 1, 1982.
G. CONCLUSION As shown in Table 1, the discharge piping from the AFW pumps to the steam generators through the emergency auxiliary feedwater lines and the steam piping to the turbine driven pump is considered to be seismically qualified.
In addition, all required electrical equipment (except as noted in Note 18 to Table 1) is considered to be seismically qualified and has been evaluated and modified if required, to ensure adequate anchorage and support.
Nonseismically qualified portions of the auxiliary feedwater system were examined on a plant walkdown and certain deficiencies were noted as described in Enclosure 2.
Corrective actions have been identified and will be implemented as described in Section F above.
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TABLE 1 SEIS4IC QUALIFICATIN INFR4ATIEN I") AUXILIARY FEIWA1ER SYSTEM (D31EJNTS INFO SEISEC MITCE 80-21 AVAILABLE SET IEC OWGPPGENT TAG N.
CATEGORY S(DIE rM QUAL DOCEN.
REMAS (1) PupsMotors Primary Plmt Makeup PLMps G-28, G-28S C
Spec Requt.
0.20g Static (Note 2)
Aux. Feedwater Rmps G-10, G-10S C
Spec Facqt.
0.25g Static (Note 3)
Firewater Pungs G-11, G-11S C
Spec Regct.
0.20g Static (Note 2)
(2)
Pipirg sarticn side of AFW Punp C-No seianic requiremnt AFW Dischargp Pipirg A
Galalatim Spectml Amalysis (Note 6)
Steam Pipirg to AFW A
0adlwLatin Spectral Anlysis (Note 6) turbine driven pznp Feedwater Pipirg (imside A
C1alation Spectral Aalysis (Note 6) contairnnent)
Feedwater Pipirg (autside C
No seismic requiremnt cantairroent)
Main steam pipirg C
No selanic requiremt (3)
Valves/Actuators Gate Valve 3-600-3 C
No seianio requiremet Gate Valve 3-1500-19 A
Verdar Cale.
5.0g static (Note 4)
Check Valve 3-1500-219 A
Vedor Cale.
5.0g static (Note 4)
Gate Valves Various C
No Seismlc requirment Globe Valves Various C
No Seismic requiret Check Valves Varicus C
No Seisno requirnent Level Cotrol Valves CV-19, 20, 21 C
No Seianic requiremnt Press Control Valve CV-1 13 C
No Seianic requireDnt Flow Ccntrol Valves Cv-142, 143, 14 C
No Seinic requireamt Control Valve CV-28 C
No Seisic requirwent Control Valve CV-3213 A
Vedor Cale.
3.0g, 79Hz natural fvquncy (Note 5)
Flow Control Valves FCV-2300, FCV2301 A
Vendor C1c.
3.0g, 79Hz natuml frequency (Note 5)
FCV-3300, FCV3301 Flow Ocntrol Valves FCV-456, 457, 458 C
No seianic requireamt Relief Valve RV-3206 C
No seiandc requirent Soleoid Valves SV-3200, SV-3201 A
Vendor Report 4.5g biaxial sine SV-3207, SV-324 dwell test (Note 7)
-2 INFO SEI34IC NOTE 80-21 AVAILABLE SEISNIC CCMPONENT TAG ND.
CATEORY SCOPE IrEM QAL DDCLM.
REMARKS Solenoid Valves SV-3211, SV-3214, A
Vendor Rport 4.5g Biaxial sine SV-905, SV-3213 dwell test (Note 7)
Motor qperated Valves MDV12(2, MOV1204 A
Vendor Calc.
5.0g, >33Hz natural freqency (Note 4)
(4)
Pbwer Spplies/Electrical Equipnent 4160 Swgr. Bus 1C, BUs X AC, A2Z A
Yes Vendor Test 3.9g single sine beat (Note 8)
MCC-1 B01 A
Yes Spec. Requirement 0.50g ground response spectra (Note 14) 480V Swgr. #1 BO4 A
Yes Vendor Test (Note 9) (Note 12) (Note 14) 125 VDC Swgr #1, #2 D01, DD8 A
Yes (Note 12) (Note 18)
Battery Charger A, B DD2, DD3 A
Yes (Note 12)
Battery Charger C, D DO9, D010 A
Yes Vendor Tbst (Note 10)
Station Battery #1 DO A
Yes Note 12)
Station Battery #2 D11 A
Yes Vendor Test 3.0g vib. test Inveter #3 YO1 A
Yes (Note 12)
Inverter #5 YV29 A
N/A' Vendor Test Fport 1.75g vib. test (Note 15)
Vital Bus #3A Y33 A
N/A' Vendor Test Report 3.Og vib. test (Note 16)
Vital Bus #5 Y29 A
N/A' Vendor Test Report 3.0g vib. test (Note 16)
Station Service 11ansformer#1
)D6 A
Yes Spec. requirenent 0.50g ground response spectra (5)
Primary Water apply Gbndensate Storage lhnk D2 C
Spec. Reqnt.
0.20g Static (Note 1)
Brknary Plant Makeup Tank D7 B
Spec. Feqnt.
0.20g Static (Note 1)
(6)
Secondary Water Sipply Service ater haervoir D5 A
Calculation (Note 11)
(7) Initiation and Cbntrol System Pushbutton switches Various A
Vendor Test 5.Og Biaxial sine dwell (Note 7)
Pressure Flow & Level Various A
Vendor Test 3.5g Biaxial sine beat (Note 7)
Indicators Analog Modules Vbrious A
Vendor Test 1.6g Single Axis Fandan (Note 7)
Level & Flow Transnitters Various A
Vendor Test 10.0g single sine beat (Note 7)
Solenoid Valve Position Various A
Vendor Test 4.5g BLaxial sine dwell (Note 7)
SwLtches
-3 INFO SEISMIC NOfICE 80-21 AVAILABLE SEI34IC CCHPCNENT TAG NO.
CATEGORY SCOPE ITEM QUAL DOCUM.
REMARKS Aux. Feedwater C71 A
N/A' Stress report (Note 13)
Control Panel Aux. Feedwater Logic 069, 070 A
N/A' Vendor Test Report 4.0g Biaxial Sine Beat (Note 7)
(Analog Module) Cabinet R-A1, R-B1 Aux. Cbntrol Panel C38 C
Yes No Seisnic requirement (Note 17)
(8) Structures Supporting or Hbusing AF Systen Thrbine Building B
Design Calc.
0.20g Static Fbel Storage Building A
Design Cale.
0.50g Static Control/Admininstration Bldg.
A Design Cale.
0.50g Static Diesel Generator Bldg.
A Dynamic Analysis 302/3 Design Spectra ground motions Ventilation Building C
Design Cale.
0.20g Static Sphere fhclosure Building A
Dynanic Analysis 302/3 Design Spectra ground motions Tubine Pedestal A
Design Cale.
0.50g Static FOrNOTES:
(1)
Specification requires the vendor to subnit seianic calculations to show tanks can resist an acceleration of 0.2g at the tank center of gravity vhen filled to overflowing.
(2)
Specification requires that the punps shall be designed to resist a 0.2g acceleration at the center of gravity and -trananit it to the foundation.
(3)
Specification requires that the punps shall be designed to resist 0.25g acceleration in both the horizontal and vertical direction.
(4)
Specification requires that the valves be designed to resist a 5.0g leading in any direction and have a natural frequency above 33 Hbrtz.
(5)
Specification requires that the valves be designed to meet the applicable floor response spectra accelerations.
Vendor stress report indicates a natural frequency of 79Hz and 3.0 ZPA capability.
- Canponent was installed subsequent to issuance of Info Notice 80-21.
(6)
Piping has been analyzed by response spectra analysis using either the SAP IV or ADLPIPE programs and a 0.67g ground motion.
(7)
Instrunents have been certified to meet the "g" levels over the frequency range contained in the vendor test reports of actual type testing.
All values shown are test levels.
In all cases, these values meet or exceed the latest Unit 1 requirenents.
(8)
Similar switchgear was tested to an acceleration of 3.9g ZPA spectra input.
Bus 1C and 2C have been certified to confom to the SOM 1 criteria by similarity.
(9)
Added equipnent for SPA Project was tested and certified to have passed a 0.73g ZPA test response spectrun.
Spec. requirenent for SPA equipnent was 0.5g ground response spectrun.
(10)
Bttery chargers have been tested to a 3.0g ZPA test response spectrun.
(11)
Analysis indicates that slopes will not fail due to a 0.67g earthquake.
(12)
SONGS 1 FSA states that 480-Volt autiliary switchgear, station battery and maintained AC source were subject to the seisnic category A provisions threin, however, available specifications for these specific itens do not include any seisnic provisions.
(13)
Design and analysis to meet fragility level of instrunents in cabinet.
(14)
These components include the addition of breakers, relays, starters, etc.,
and were procred on the basis of matching the existing equipnent.
(15)
Equipnent was subjected to a test response spectra with a 1.75g ZPA which enveloped the instructure response spectra.
(16)
Equipnent was subjected to 3.0g test response spectra as described in vendor test report.
(17)
Auiliary control panel is required only durirg a control roan fire/gas evacuation.
,Corcurrent earthquake and fire is not postulated.
(18)
Three relays installed in 480V Switchaear lbs.
1 and 3 as a result of TM related requirements were not in canpliance with the project design criteria and are scheduled to be replaced with qualified relays in accordance with SCE's letter dated October 16, 1981.
GG.npg
TABLE 2 NON SEISMICALLY QUALIFIED PORTIONS OF THE AUXILIARY FEEDWATER SYSTEM (1)
Pumps/Motors - motor driven auxiliary feedwater pump (GlOS), turbine driven auxiliary feedwater pump (G10).
North and south primary plant make up water pumps (G28) and (G28 S).
Fire water pumps G-11 and G-11S.
(2)
Piping Main Steam Piping Suction side of AFW pumps Main feedwater lines outside containment (3)
Valves/Actuators Gate valve 3-600-37 Main feedwater control valve bypass valve CV-142*
Main feedwater control valve bypass valve CV-143*
Main feedwater control valve bypass valve CV-144'*
Aux.
pump turbine driven steam supply control valve CV-113 Condenser level control valve CV-19 Condenser level control valve CV-20 Condenser level control valve CV-21 Main feedwater control valve CV-456*
Main feedwater control valve CV-457*
Main feedwater control valve CV-458*
CV-28 control valve RV 3206 relief valve Various Gate Valves Various Globe Valves Various Check Valves (4)
Power Supplies/Electrical Equipment -
entire system seismically qualified except relays noted in Note 18 of Table 1 (5)
Primary water supply -
Condensate Storage Tank and Primary plant make-up tank (6)
Secondary water supply -
Service water reservoir qualified (7) Initiation and control system - Auxiliary control panel C38 (8)
Structures supporting or housing these AFW system items Turbine building Ventilation building
- Containment isolation only GG:npg
ENCLOSURE 2 AUXILIARY FEEDWATER SYSTEM WALKDOWN SAN ONOFRE UNIT 1 A. INTRODUCTION A walkdown of the non-seismically qualified portion of the Auxiliary Feedwater (AFW)
System was performed to determine any deficiencies in the design of the system which, if corrected, could significantly enhance the seismic resistance of the system.
The system walkdown was accomplished by design engineers and supervisory personnel knowledgeable of the original design requirements and subsequent system revisions.
The mechanical, electrical and civil/structural disciplines provided personnel to walkdown the non-seismically qualified portions of the system to identify any apparent and practically correctible deficiencies that -exist. The results of this walkdown are summarized in the following paragraphs.
B. MECHANICAL EQUIPMENT AND PIPING The primary water source path is from the primary plant makeup tank through the condensate storage tank to the AFW pump suctions.
A secondary path from the service water reservoir through the fire water pumps is used as a backup.
A hose connects the fire water main to the suction of the electric driven (south) AFW pump. This piping and equipment was reviewed as part of the walkdown.
The AFW pump discharge piping is designed to withstand a DBE and did not require a system walkdown.
-2 The primary plant make-up tank (PPMT) has up to 105,000 gallons of water reserved for AFW system use (San Onofre Unit 1 Technical Specifications require 105,000 gallons in the PPMT or the service water reservoir).
The reserved water is pumped from the PPMT to the condensate storage tank by the primary plant make-up pumps through a 3 inch line (711-3-HP).
Line 711-3-HP does not have adequate seismic supports in the area of the pump or outside area, prior to penetrating the turbine building wall.
Addition of "U" bolts to existing structural supports in this area would enhance the seismic resistance. The primary plant makeup pumps are securely bolted to their foundations but there are no apparent hold-down bolts for either the primary plant make-up tank or the condensate storage tank. The piping run inside the turbine building, along the west wall is adequately supported on the structure with "U" bolts.
The run along the south wall of the turbine building and out to the condensate storage tank is supported by hanger rods with trapeze supports.
This area could be enhanced by added stiffening.
The secondary water source is from the service water reservoir to the fire pumps 'through an 8 inch line (811-8-KN).
Line 811-8-KN runs from the service water reservoir, down the slope from the north bluff and enters the ground inside the security fence.
The line continues underground to the reactor auxiliary building pipe tunnel where it emerges and is supported with "U" bolts as seismic supports.
The pipe exits the tunnel into the outside area and runs along the turbine building wall to the fire pumps.
Additional lateral support in the outside turbine building area
-3 could be afforded with "U" bolts on the structural steel supports and in the area of the fire pumps.
The fire pumps are adequately bolted down to their foundations.
Normal AFW pump suction is taken from the condenser level control manifold piping.
This piping is supported for weight loading only.
Additional lateral support could be added to the supply line (721-10-HP)' and to the condenser leads at column line 9 and column line G. The remainder of the piping to the pump suction is adequately supported.
The AFW pump turbine driver steam supply from the main steam line to the AFW turbine driver has axial and lateral supports on the, entire run.
CV-113, the steam supply control valve, has no support on its control mechanism.
Additional support of the controller would enhance its seismic resistance.
C. ELECTRICAL EQUIPMENT AND RACEWAY A walkdown was made of all AFW System related electrical equipment and raceways to determine if any deficiencies exist with respect to seismic withstand capability.
Based on the walkdown, it was concluded that all equipment has been installed with consideration of seismic loads. Most of this equipment was installed as part of the TMI Project and is capable of withstanding 0.67g Housner.
Other equipment was evaluated and modified as required as part of the evaluation of the anchorage of safety related electrical equipment (IE Information Notice 80-21).
It is also concluded that raceways related to the AFW System have been supported adequately to withstand seismic loads.
GG:npg
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ENCLOSURE 3 ALTERNATE MEANS OF DECAY HEAT REMOVAL SAN ONOFRE NUCLEAR GENERATING STATION UNIT 1 The normal means of decay heat removal is achieved utilizing the main feedwater system or auxiliary feedwater system and steam generators.
If the normal means is unavailable, an alternate means of decay heat removal can be utilized depending on the availability of required equipment.
The alternate means of decay heat removal can be achieved by (1) realigning the charging pumps to take suction from the refueling water storage tank, (2) delivering water to the reactor coolant system using the long-term recirculation flow path, and (3) discharging the reactor coolant system inventory into the pressurizer relief tank through the pressurizer power operated relief valves and from there into containment. Steam entering containment would be condensed by containment spray as necessary.
In order to obtain an estimate of the time available for operator action to implement this alternate means of decay heat removal, a preliminary analysis assuming the loss of main feedwater, steam, safety injection and the normal decay heat removal capability has been performed. The analysis indicates that a delay of up to 30 minutes would be available for operator action. In all cases analyzed, the core remained covered. This analysis was not intended to provide definite timing requirements for operator action, but does indicate that a sufficient time for operator action would be available considering that all actions can be accomplished from the control room with remote manual control.
A schematic diagram of the alternate means of decay heat removal is shown on Figure 1. A list of major components in the system and the seismic category of these components in accordance with the provisions of the San Onofre Unit 1 FSAR is given in Table 1. As can be seen from this table, the only components which are not Seismic Category A, are the refueling water pumps.
These pumps were not originally classified as safety related but are utilized as part of the containment spray system. Their loss would not affect the ability to provide water from the refueling water storage tank to the RCS using the charging pumps. Moreover, these pumps are securely.bolted to their foundations which ensures resistance to earthquake loading conditions.
TABLE 1 ALTERNATE DECAY HEAT REMOVAL PATH AND SEISMIC CATEGORY COMPONENT TAG NO.
SEISMIC CATEGORY Refueling Water Tank D-1 A
Charging Pumps G-8A, G-8B A
Pressurizer Relief Tank C-16 A
Refueling Water Pumps G-27 Recirculation Pumps G-45A, G-45B A
Recirculation Heat Exchanger E-11 A
Component Cooling Pumps G-15A, G-15B A
Component Cooling Heat Exchanger E-20A, E-20B A
Salt Water Cooling Pumps G-13A, G-13B A
Motor Operated Valves MOV-18, -19, -356 A
-357, -358, -720,-883 A
Control Valves CV-82, -530, -531 A
-545,-546 Pressure Control Valves PCV-5, PCV-6 A
Piping A
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