ML14093A229

Rev 0 to Tornado Resistance Design Review for San Onofre Unit 1

ML14093A229
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Site:	San Onofre
Issue date:	10/10/1986
From:	Killough C, Sellers C, Zee K CYGNA ENERGY SERVICES
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ML13330B121	List: ML13330B120 ML14093A229
References
TR-85028-02, TR-85028-2, NUDOCS 8610160172
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SI Tornado Resistance Design Review For San Onofre Nuclear Generating Station Unit 1 Prepared for:

Southern California Edison Company Cygna Report Number:

TR-85028-02 Revision 0 August, 1986 Prepared by:

iang e

Reviewed by:

Craig Sellrs Approved by:

Craig KilloughQ Cygna Energy Services 101 California Street Suite 1000 San Francisco, California 94111 IIIIIIIlilIlIIIIIll1

0 EXECUTIVE

SUMMARY

The Tornado Resistance Design Review was performed to resolve the.

outstanding items identified in SEP Topics 111-2 and III-4.A. The review demonstrated adequate resistance to tornado loadings less than specified in the SEP and that the risk associated with higher loadings was acceptable.

The review began with a detailed evaluation of the plant site, equipment locations, design documents, and operating procedures. This resulted in it the identification of several possible plant shutdown systems that could be used to safely bring the unit to cold shutdown. These shutdown systems were the combination of several existing systems and did not necessarily result in standard plant configurations. A review of overall plant

• )

operations was performed to identify possible conflicts with existing safety functions. The equipment and structures required to operate each of the possible shutdown systems was identified and vulnerability to tornado induced damage noted. A damage assessment was performed to

4) identify the shutdown flowpath which would result in the least amount of plant upgrades. The results of this preliminary damage assessment indicated that single phase steam generator cooling could be used to bring the plant to cold shutdown and would involve the least amount of

()

modifications. Once the shutdown flowpath was identified, modifications were conceptualized and installation costs were estimated. This was done for four specific wind speed probability occurrences.

A cost-safety benefit evaluation was performed to identify the Design Basis Tornado (DBT).

This evaluation compared the incremental plant backfit cost increases as a function of tornado event probability. This evaluation found that the cost associated with providing tornado protection for tornado loadings higher than the 10-5 probability occurrence (103 mph windspeed) did not provide a consistent increase in safety benefit.

Based on this evaluation the SONGS 1 DBT was defined as the 10-5 wind speed probability occurrence.

Tornado Resistance Design Review for 1

San Onofre Nuclear Generating Station Unit 1 MumM Report No.

TR-85028-02, Revision 0

TABLE OF CONTENTS Section Page EXECUTIVE

SUMMARY

i TABLE OF CONTENTS.

ii LIST OF TABLES.

.............................. iv LIST OF FIGURES...................................

v

1.0 INTRODUCTION

................................. 1-1 2.0 METHODOLOGY.........

2-1 2.1 Identification of Systems, Components and Structures.................................. 2-1 2.2 Review of Safety Evaluation Reports........... 2-2 2.3 Component and Structural Damage Evaluation....

2-2 2.4 Conceptualize Plant Modifications............. 2-3 2.5 Define Design Basis Tornado................... 2-4 3.0 PLANT SHUTDOWN SYSTEMS............................ 3-1 3.1 Reactivity Control........................... 3-2 3.2 Primary Coolant Inventory Control............. 3-3 3.3 Primary Coolant Pressure Control.............. 3-4 3.4 Decay Heat Removal..

3-4 3.5 Electrical Systems........................... 3-6 3.6 Shutdown Systems Summary..................... 3-7 4.0 SYSTEM COMPONENTS................................ 4-1 5.0 STRUCTURES......................

5-1 6.0 DAMAGE EVALUATION

............................. 6-1 6.1 Review of Safety Evaluation Reports........... 6-1 6.2 Damage Evaluation........................ 6-2 Tornado Resistance Design Review for 11 San Onofre Nuclear Generating Station Unit 1 iiiIlil Report No. TR-85028-02, Revision 0

TABLE OF CONTENTS Section Page 7.0 PLANT UPGRADES......................

7-1 7.1 Structures 7-2 7.2 Reactivity and Primary Coolant Inventory Control.

................................ 7-6 7.3 Primary Pressure Control...................

7-11 7.4 Decay Heat Removal.........

7-13 7.5 Onsite Emergency Power System

............. 7-21 8.0 DESIGN BASIS TORNADO............................. 8-1

9.0 REFERENCES

9-1 Tornado Resistance Design Review for11 San Onofre Nuclear Generating Station Unit 1 WHReport No. TR-85028-02, Revision 0,

LIST OF TABLES Table Title Page 3-1 Plant Shutdown Systems 3-8

)

4-1 Components Required for Reactivity and Primary Coolant Inventory Control........... 4-2 4-2 Components Required for Primary Pressure Control................

4-4 4-3 Components Required for Decay Heat Removal....

4-5 4-4 Components Required for Onsite Emergency Power and Auxiliary Systems.......

4-10 5-1 Plant Structures Evaluated...........

5-2

)

6-1 Tornado Windspeed and Missile Qualification of Structures................. 6-4 6-2 Reactivity and Primary Coolant Inventory Control...................

6-6 6-3 Primary Pressure Control...................... 6-8 6-4 Decay Heat Removal............................ 6-9 6-5 Onsite Emergency Power System and Auxiliary Systems.............

6-19 7-1 Modifications Required for Structures.........

7-23 7-2 Modifications Required for Reactivity and Primary Inventory Control.................. 7-24 7-3 Modifications Required for Primary Pressure Control...........................

7-25 7-4 Modifications Required for Decay Heat Removal............................. 7-26 7-5 Modifications Required for the Onsite Emergency Power System....

.............. 7-28 Tornado Resistance Design Review for iv San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

LIST OF FIGURES Figure Title Page 2-1 Design Review Process..........................2-5 2-2 DamageEvaluation.............................2-6 3-1 Reactivity Control Diagram.....................3-9 3-2 Primary Coolant Inventory Control Diagram 3-10 3-3 Primary Pressure Control Diagram...............3-11 3-4 Decay Heat Removal Diagram.....................3-12 3-5 Onsite Emergency Power System..................3-13 6-1 Reactivity, Primary Inventory and Pressure Control Flowchart...................6-24

• 6-2 Decay Heat Removal Flowchart................... 6-25 7-1 Reactivity, Primary Inventory and Pressure Control Flowpath.................... 7-29 7-2 Decay Heat Removal Flowpath................... 7-30 8-1 Cost-vs.-Event Probability...................

8-2 Tornado Resistance Design Review for v

San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 0AI-a nfeNcer eeaigSainUi

1.0 INTRODUCTION

This report describes the Tornado Resistance Design Review performed on San Onofre Nuclear Generating Station Unit 1 (SONGS 1).

The design review was performed to resolve outstanding items identified by the NRC in their evaluation of Systematic Evaluation Program (SEP)

Topics 111-2 and III-4.A on "Wind and Tornado Loadings" and "Tornado Missiles, " respectively.

The NRC has summarized their position on SEP Topics 111-2 and III-4.A for SONGS 1 in Safety Evaluation Reports (SERs) contained in [1] and

[2].

These SERs concluded that the licensee should:

1) implement plant modifications in order to meet the design basis tornado loads,

2) demonstrate that the consequences of failure due to tornado loads are acceptable, or 3) demonstrate adequate design resistance for smaller tornado loadings and that the risk associated from larger tornado loadings is acceptable.

This report addresses option number 3 above.

Specifically, the

)

design review was performed to ensure the availability of structures, systems, and components that are required to assure:

1. the integrity of the reactor coolant pressure boundary,

2. capability to shutdown the reactor and maintain it in a safe shutdown condition, and

)

3. the capability to prevent accidents which could result in an increase of offsite exposures.

Tornado Resistance Design Review for 1-1 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 Il0IlII~ lIIIIlII

The design review evaluated the current straight wind and tornado design resistance of SONGS 1, quantified upgrades required for

4) different wind speeds as defined in [3], and determined the design basis tornado event.

The design review criteria used in this evaluation are documented in [4].

The design review methodology is described in Section 2.0 of this report. Section 3.0 describes the plant shutdown systems evaluated, Section 4.0 presents the system components and Section 5.0 the plant structures required. The damage evaluation for the existing plant configuration is presented in Section 6.0.

Plant modification options and recommendations are described in Section 7.0. Finally, section 8.0 presents a cost-safety benefit evaluation and describes the SONGS 1 Design Basis Tornado.

Tornado Resistance Design Review for 1-2 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

2.0 METHODOLOGY The design review methodology involved five basic tasks. These tasks are:

1. Identify Systems, Components and Structures

2. Review Safety Evaluation Reports

3. Evaluate Component and Structure Damage

4. Conceptualize Plant Modifications

5. Define Design Basis Tornado A flow chart showing the design review process is presented in Figure 2-1.

Each task is described in the following sections.

The following assumptions were made in the design review effort:

1. The plant is in normal operating conditions.

2.

Immediate loss of offsite power due to the tornado.

3.

No random single failures.

4 Immediate Loss of Instrument Air System.

5. Masonry block walls provide no missile protection.

2.1 Identification of Systems, Components and Structures The Normal, Abnormal and Emergency Operating Instructions were reviewed to determine a set of systems required to place and maintain the plant in a safe shutdown condition. Based on this review the normal and emergency methods for plant shutdown were evaluated and the necessary components required to perform this effort identified.

A review of the drawings for the systems required to function was performed to identify all system interfaces and potential structural interactions.

Process and instrumentation diagrams, general layout Tornado Resistance Design Review for 2-1 s

-1San Onofre Nuclear Generating Station Unit 1 Report No.

TR-85028-02, Revision 0

drawings, single line drawings and control schematics were included in this review. The objective of this review was to identify:

1. Redundant and/or alternate components available for a single function.

2. Any system interfaces which could adversely affect a required system or component upon the failure of an alternate system.

This review identified all structures, systems and components that were required to remain functional or maintain their structural integrity in order to effect safe plant shutdown.

2.2 Review of Safety Evaluation Reports The review of systems, components and structures centered around those that were identified by the NRC in their SERs [1], [2] as not

()

being qualified to withstand the postulated tornado loads or as not being adequately protected from tornado missiles. The evaluation performed by the NRC was based on criteria used for licensing new facilities. The SERs were based on a tornado wind speed of 250 mph

()

and a pressure drop (differential pressure) of 1.5 psi occurring in 4.5 seconds.

Two postulated missiles were considered, namely a 1 inch diameter 3 foot long, 8 lb. steel rod with a total horizontal velocity of 229 ft/sec and a 13 1/2 inch diameter, 35 feet long, 1490

()

lb. utility pole with a total horizontal velocity of 152 ft/sec.

Using these tornado and missile parameters it was concluded that the required concrete thickness for an adequate missile protection barrier would be 10 inches for the utility pole missile and 6 inches

)

for the steel rod missile. It was further concluded that masonry walls, generically would not provide adequate protection against tornado missiles. The NRC performed no component damage evaluations.

Tornado Resistance Design Review for 2-2 San Onofre Nuclear Generating Station Unit 1 UmuunmReport No. TR-85028-02, Revision 0

2.3 Component and Structural Damage Evaluation

4)

Components and structures required to support the plant shutdown systems and.not qualified based on the NRC SERs were evaluated for damage based on site specific tornado and straight wind loads of

[3].

The evaluation methodology is shown in Figure 2-1 and is described in the following section.

The damage evaluation was based on the assumption that all inadequately protected components and structures were subjected to the site specific tornado and straight winds of [3] and struck by the two specifically defined NRC missiles [2].

The resultant loads were used to determine the structural adequacy of the components and structures to perform their required shutdown functions.

The components and structures were evaluated following the criteria of

[4]. This methodology is shown in Figure 2-2.

Structures and large components were evaluated for failure due to differential pressure. The initial evaluation step was to assess the venting area of each structure or component.

If the structure or component satisfied the venting criteria of [4], no further differential pressure evaluation was performed. In the venting assessment for atmospheric storage tanks, the constriction of the vent nozzles due to missile strike was not considered.

In addition to the potential failure of components by postulated tornado loads, active components were also reviewed for potential failure due to sand impingement. For those active components not located in protected structures a review was performed to determine if sand could enter the component's casing or affect exposed bearings.

If it was determined that no visible pathway is available for sand to enter the component's casing or affect the bearings, the component was considered protected and no further evaluation required.

Tornado Resistance Design Review for 2-3 San Onofre Nuclear Generating Station Unit 1

'Report No. TR-85028-02, Revision 0

2.4 Conceptualize Plant Modifications

()

Once it was determined that a component or structure required for plant shutdown was not qualified for the specific loading condition, modifications were conceptualized. These modifications included shielding, relocating and reinforcing.

Each modification was conceptually designed to protect the item from the specific wind or missile velocity associated with the event probability. Once conceptualized, modification costs were estimated.

2.5 Define Design Basis Tornado The modification costs to protect the plant from the tornado events were summed to determine a total cost for plant upgrade at discrete probability levels.

This information was used to perform a cost safety benefit for each of the event probabilities and a risk evaluation. Based on this evaluation it was determined for which probable wind speed occurrence it was most beneficial to backfit the plant. This point represents the SONGS 1 Design Basis Tornado.

Upon determination of the Design Basis Tornado a review of the shutdown systems was again performed. This review defined the

)

minimum set of components and structures available to place and maintain the plant in a safe shutdown condition. This minimum set comprised the tornado shutdown system. The tornado shutdown system consists of a single train of components qualified to or protected

)

from the Design Basis Tornado loads.

0 Tornado Resistance Design Review for 2-4 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 0IIIIIIIIII~llH

Figure 2-1

)

Design Review Process Identify Shutdown Systems Identify System Components Identify Required Structures Do yes SERs Qualify Components and Structure no Does Damage yes Evaluation Qualify Components and Structures Conceptualize Modifications and Estimate Cost Define Design Basis Tornado and Shutdown System Tornado Resistance Design Review for 2-5 S

San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

Figure 2-2

4)

Damage Evaluation NRC Missiles.

Site Specific

• Utility pole Windfield

• Steel rod Database t

()Targets yes OK at 10-7 windspeed no Targets yes OK at 10-6 windspeed no Targets yes OK at 10-5 windspeed no Targets yes OK at 10-4 windspeed n0 Component and Structure Qualification Levels Tornado Resistance Design Review for 2-6

,San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 IIII0llilil~llI

3.0 PLANT SHUTDOWN SYSTEMS This section of the report describes the plant systems available and their use for safe plant shutdown. The components within these systems are discussed in detail in Section 4.0. As described below the shutdown systems and scenario are very similar to the SOfNGS 1 Appendix R Dedicated Shutdown System [7].

The systems normally used for safe shutdown at SONGS 1 include reactor coolant (RCS), auxiliary feedwater (AFW), main steam (MSS),

chemical and volume control (VCC), residual heat removal (RHR),

component cooling water (CCW), and salt water cooling (SWC).

Based on a plant inspection and initial missile damage evaluations it was determined that tornado events have the potential for making one

()

or more of these systems unavailable as a result of missile damage to system components, associated electrical power circuits, instrument air supplies, system instrumentation, and controls. This is particularly true for the component cooling water and salt water

• )

cooling systems that are totally exposed to missiles.

Therefore, the tornado resistance design review began by determining a minimum set of plant systems available for plant shutdown. These systems were chosen on the basis of their missile protection.

The shutdown system uses the single phase secondary cooling scenario based on the concept that it is possible to achieve and maintain cold shutdown by using the steam generators for decay heat removal.

Normally, the steam generators are operated in conjunction with the auxiliary feedwater system and steam dump system to reject decay heat through the generation and controlled release of steam. When the reactor coolant system has been cooled to 350oF and 365 psia, operation of the residual heat removal system is initiated to bring the unit to cold shutdown. Previous.calculations [10] indicate that cooldown can be continued with the steam generators, and that cold Tornado Resistance Design Review for 3-1 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 IIIII0lillHI~ll

shutdown (RCS temperature less than 2000F) can be achieved and maintained by operating the steam generators in a single-phase heat transfer mode [7].

The advantage of using the steam generators to achieve and maintain cold shutdown is that this approach does not require the component cooling, or salt water cooling systems to be operable following a tornado. This, in turn, avoids a number of difficult, expensive and time consuming modifications that would have otherwise been necessary.

By recognizing the potential consequences of tornado events the design of the shutdown system represents a unique combination of systems capable of being used in the event of the design basis tornado. The shutdown system description is given in the following sections. The sections are presented in a format related to plant control functions.

3.1 Reactivity Control Reactivity control is initially provided by the reactor trip function of the Reactor Protection System (RPS).

As the RCS is cooled-down, the required shutdown margin will be maintained by injecting borated water from the refueling water storage tank (RWST). This water will be supplied by the charging pumps by way of the normal charging flow path and the reactor coolant pump seals. The system flow diagram is shown in Figure 3-1.

In order to achieve the required margin for cold shutdown following sustained operation at 100 percent power, approximately 6,200 gallons of boric acid solution must be added to the RCS from the RWST.

This

()

additional boron will bring the RCS concentration to 700 ppm which is sufficient to maintain Keff less than 0.95. The volume of borated water necessary to establish and maintain the required shutdown 0

Tornado Resistance Design Review for 3-2 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 I0IIII~lilllill

margin is based on the minimum RWST concentration of 3750 ppm as required by Technical Specifications.

3.2 Primary Coolant Inventory Control The primary coolant inventory will be controlled by limiting reactor coolant pump seal (RCP) leakage while injecting a sufficient amount of water through the normal charging path and RCP seals to maintain pressurizer level and compensate for shrinkage during cooldown. With the minimum required concentration of boric acid in the RWST, the water injected for primary coolant inventory control exceeds that required to maintain an adequate shutdown margin for reactivity control.

The system flow diagram is shown in Figure 3-2.

With the RCP seals intact and RCS leakage less than 6 gpm (a Technical Specification limit), operation of the volume control and charging (VCC) system must be initiated within two hours of the reactor trip in order to prevent an unacceptable decrease in pressurizer level.

As discussed above under functional requirements for reactivity control, the charging pumps will be aligned to take suction from the RWST.

Under the postulated tornado damage conditions, however, the seal

4) water return path may become isolated. Therefore, any leakage through the seals will pressurize the seal water return header, activate relief valve RV-2004 and be discharged to the RCS drain tank.

The shutdown system does not require operability of the normal letdown flow path.

If for some reason it became necessary to remove mass from the RCS, this would be accomplished through the pressurizer power operated relief and block valves.

Seal injection and seal cooling to the RCPs will be unavailable until the charging pump is energized. Westinghouse Electric Corporation Tornado Resistance Design Review for 3-3 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

has evaluated the effect on RCS integrity of a postulated fire [7]

which would disable seal cooling for up to 30 minutes. This evaluation shows that, based on test results and actual station experience, the reactor coolant pump seals could be expected to survive for up to 2-1/2 hours without materially changing the leakage rate of the seals.

This is sufficient time to properly align the Charging and Volume Control System.

3.3 Primary Coolant Pressure Control Primary coolant pressure will be controlled by the use of pressurizer heaters and relief valves. The heat loss from the pressurizer is sufficiently low that during the initial hours of RCS cooldown, pressurizer heaters are not necessary to maintain adequate system pressure. In case of overpressure, pressure must be relieved from the system so that the cooldown may proceed without exceeding RCS nil ductility transition temperature (NDTT) limits.

This pressure relief will be accomplished by way of a pressurizer power-operated relief (PORV) and block valve combination. The system flow diagram is shown in Figure 3-3.

3.4 Decay Heat Removal Decay heat will be removed from the core by natural circulation.

Heat (reactor decay and sensible) will be removed from the RCS through one or more steam generators using two different steam generator operating modes: a steaming mode and a single-phase heat transfer mode.

The steaming mode will commence immediately following reactor trip.

Heat will be transferred to the feedwater in one or more steam generators.

Steam will be generated and released under the control of the atmospheric dump valves.

Water will be supplied to the steam generator(s) by the Main Feedwater System (FWS), or the AFW System.

Tornado Resistance Design Review for 3-4 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

After the steam generator bulk temperature reaches approximately 2200F, the steaming mode will be terminated and a transition made to

4) the single-phase mode of operation.

The single-phase mode of operation involves heat transfer from the RCS to cooling water being supplied by the Feedwater or Auxiliary Feedwater Systems. The steam generators will act as once through, single-phase heat exchangers. Water will be discharged through the piping and valves branched into the AFW pump turbine steam supply piping upstream of CV-113. The cooling water will be discharged to an existing circulating water outfall point. This discharge piping and valve configuration is described in [7].

Using this method, cold shutdown can be achieved within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.

The single-phase mode of operation will be continued until the normal RHR system is restored to service. The system flow diagram is shown in Figure 3-4.

System functional requirements for this operating configuration are described in [7].

The decay heat removal system will be required to remove a sufficient amount of heat from the reactor coolant system to achieve and maintain cold shutdown.

Water stored in the auxiliary feedwater and condensate storage tanks will be supplied to the steam generators by

)

the main feedwater or auxiliary feedwater pumps. Flow to each steam generator will be controlled by the existing normal feedwater or emergency auxiliary feedwater flow control valves.

For the few minutes following reactor/turbine trip that it will take to initiate operation of the auxiliary feedwater pump, RCS temperature will be controlled at 600oF by the heat removed through the production of steam from the initial inventory of water stored in the steam generators and escaping through the steam generator atmospheric dump valves or safety relief valves outside containment. After the auxiliary feedwater pumps are started and flows are established to recover normal steam generator levels, the Tornado Resistance Design Review for 3-5 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

cooldown of the RCS is initiated through the operation of the power operated atmospheric steam dump valves. The dump valves will be controlled to increase the flow of steam from the steam generators, resulting in a reduction in steam generator pressure to a point that will allow the safety relief valves to close. The steam flow through the dump valves is then adjusted to establish an RCS cooldown rate of 250F/hr, while feedwater flow is adjusted to maintain steam generator level.

The inventory of water on-site, including the 3,000,000 gallon service water reservoir, is sufficient to maintain cold shutdown conditions for a period of approximately 9 days.

Offsite sources of water will allow the system to continue to maintain cold shutdown for an indefinite period. Within this period, however, it will be desirable to restore the systems normally used to maintain cold shutdown (residual heat removal, component cooling, and saltwater cooling) to normal operability, thereby allowing operation of the tornado shutdown system to be discontinued.

3.5 Electrical Systems Tornado events are assumed to result in complete loss of offsite power. Therefore, all systems will be powered from on-site emergency power systems.

The on-site emergency power systems include the Emergency Diesel Generator Systems, 125 Volt DC battery systems and the 4160 Volt and 480 Volt distribution systems as shown in Figure 3-5.

Tornado Resistance Design Review for 3-6 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

3.6 Shutdown Systems Summary The systems necessary to perform and maintain the required plant shutdown functions are listed in Table 3-1.

The minimum set of plant shutdown systems include portions of the following:

RPS:

Reactor Protection System CRS:

Containment Spray and Recirculation System VCC:

Volume Control and Charging System RCP:

Reactor Coolant Pump System LDS:

Letdown Demineralizer System PZR:

Pressurizer MSS:

Main Steam System AFW: Auxiliary Feedwater System FWS:

Feedwater System CND:

Condensate System ELEC: On-Site Emergency Power System HVAC: Control Room HVAC System 0

Tornado Resistance Design Review for 3-7 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 3-1 PLANT SHUTDOWN SYSTEMS Plant Plant Function Systems Reactivity Control Reactor Protection System (RPS)

Containment Spray and Recirculation System (CRS)

Volume Control and Charging System (VCC)

Reactor Coolant Pump System (RCP)

Letdown Demineralizer System (LDS)

Primary Coolant Containment Spray and Recirculation System (CRS)

Inventory Control Volume Control and Charging System (VCC)

Reactor Coolant Pump System (RCP)

()

Letdown Demineralizer System (LDS)

Pressurzier (PZR)

Primary Coolant Pressurizer (PZR)

Pressure Control Decay Heat Removal Main Steam System (MSS)

Auxiliary Feedwater System (AFW)

Condensate System (CND)

Feedwater System (FWS)

On-Site Emergency On-Site Emergency Power System (ELEC)

Power System and Control Room HVAC System (HVAC)

Auxiliary Systems Tornado Resistance Design Review for 3-8 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

Figure 3-1 Reactivity Control Diagram RWST M MOV 0-188 RCRS 302

()

CRS 303 CRS 323 CRS 3301 RECIRCULATION H EAT EXCHANGER CRS VCC

-027 388 MOV M M9 MOV g -----

-866A

-866B CRS

-042 FILTER 110 FCVFCV FCV FCV 1115C 1115B

-1115A M MOV CHG PUMP G-8A FC 12REGEN HX C 0

CHG PUMP G-8B TEST PUMP PUMP G2-B G-42 SEALS (3)

G2-C REACTO Tornado Resistance Design Review for 3-9 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 S

IIIIl~lllIIIII

Figure 3-2 Primary Coolant Inventory Control Diagram See Figure 3-1 Cv FCV FCV FCV 304 1115A 1115B 1115C 3114A REACTOR LANTF SEALS (3)

PCV G2-A FT 2114C RV PCV5A 114C) 2004 LOOP A HOT LEG Cv Cv 528 527 PCV G2-B 11158 PCV G

4)1115C G2-C RCDT C-32 7

R-- LOOP C HOT LEG RV REACTOR 533 RV PZR RELIEF

.532 TANK C-16 CV-545 CV-531 7

PRESSURIZER CV-546 CV-530 11-TO LOOP B HOT LEG Tornado Resi stance Design Review for 3-10 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 IIIIIl0IIIII~ lIl

Figure 3-3 Primary Pressure Control Diagram T I TI

RV10, 532 SEMTI HOT RCS-C-1 COLD T I GENERATOR E-1B CV-545 CV-531 P1 PRESSURIZER CV-546 CV-530 PRESS HEATER

.LOOP B HOT LEG Tornado Resistance Design Review for 3-11 San Onofre Nuclear Generating Station Unit 1 kIIIIIIlIIIIIIIIIIIII Report No. TR-85028-02, Revision 0

Figure 3-4 Decay Heat Removal Diagram R1-2 6 STEAM IRMIP TO ATMOSPHERE STEAM GENFRATORS 10 CV144 CV CV7 LI PV-1 650 FCV 457 Mv 20

.. ms

.1 CH2 EATERS G-1 RI-I9

-I CY4 as 3

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3-5

-'-9 STEM IP TO ATMOSPHEREF NJ FROM SERVICE C

S 71 TCV 9 "SS 301FCV FCV FCV FCV MDV LT 02A 02 S330 2301 3301 2300 1204 AIST COND CND-355 DISCHARGE TO CIRC.

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WATER OUTFALL 2 112-FIRE HOSES (4)

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CV 3201 6-10

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'APPENDIl R"

5 FW TMR IlE Tornado Resistance Design Review for 3-12

.=

San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

Figure 3-5 Onsite Emergency Power System 4160V BUS-IC 4160V BUS-2C I

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2y)FOMM C1 oo Ka 5

g OISIR PNL INVERITERS ROD VITAL BUSES CONIROL

• TI NO. I I.RU 3 INVERTER RISC.

N0.4 CONIROL B IE POATER N~~ ~ ~

O.2 20RE RS VITAL BUS CONTROL G-8A lST PUMP No.H 6 PORWE LUBE OIL 6-42 PUMP

________Tornado Resistance Design Review for 3-13

-San Onofre Nuclear Generating Station Unit 1 2Report No. TR-85028-02V Revision 0

4.0 SYSTEM COMPONENTS

• )

This section of the report describes the system components required for operation of the shutdown systems. The systems described in Section 3.0 were reviewed to determine the components required to function and/or maintain their pressure boundary following a postulated tornado event. A list of the components required for each system to perform its intended function was developed.

The tornado shutdown system consists of several plant systems aligned in configurations to perform specific shutdown functions. Therefore, the system components are listed by system function to provide an overall idea of the components required to perform a desired function. A list of these components is in the following tables:

Reactivity and Primary Coolant Inventory Control Table 4-1 Primary Pressure Control Table 4-2 Decay Heat Removal Table 4-3 Onsite Emergency Power System and Table 4-4 Auxiliary Systems Components required for pressure boundary only are identified by (1).

Tornado Resistance Design Review for 4-1 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 IISlIIIIllIII~ lI

TABLE 4-1 COMPONENTS REQUIRED FOR REACTIVITY CONTROL AND PRIMARY COOLANT INVENTORY CONTROL SYSTEM COMPONENT COMMENTS CRS D-1 RWST CRS PIPING PIPING FROM RWST TO CHARGING PUMPS CRS PIPING PIPING ASSOCIATED WITH RECIRCULATION HEAT EXCHANGER (E-11)( 1) AND VALVES(1)

CRS-302, 303, 329, 330, AND 426 CRS MOV-1100B,D VCC PIPING PIPING ASSOCIATED WITH THE SEAL WATER HEAT EXCHANGER (E-34)(1)

VCC G-8A,B CHARGING PUMPS VCC G-942 LUBE OIL PUMP (G-8A)

VCC G-943 LUBE OIL PUMP (G-8B)

VCC E-908 LUBE OIL COOLER (G-8A)

VCC E-909 LUBE OIL COOLER (G-8B)

VCC G-42 TEST PUMP VCC PIPING PIPING FROM CHARGING PUMPS TO CONTAINMENT PENETRATION B-5 VCC FCV-1112 CHARGING PUMP DISCHARGE FLOW CONTROL VALVE VCC FIT, FI, YE-1112 CHARGING FLOW INSTRUMENTATION VCC PIPING PIPING FROM CONTAINMENT PENETRATION B-5 TO REACTOR VESSEL LOOP A COLD LEG Tornado Resistance Design Review for 4-2 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 I0lIIII illIIllI

TABLE 4-1 COMPONENTS REQUIRED FOR REACTIVITY CONTROL AND PRIMARY COOLANT INVENTORY CONTROL (continued)

SYSTEM COMPONENT COMMENTS VCC CV-304 CONTROL VALVE FOR CHARGING FLOW TO REACTOR VESSEL VCC PIPING PIPING ASSOCIATED WITH CV-305 (AUX SPRAY TO PRESSURIZER)( 1)

RCP PIPING SEAL INJECTION PIPING FROM CHARGING PUMPS TO CONTAINMENT PENETRATIONS B-7A, B-7B, AND B-7C RCP FCV-1115A,B,C RCP SEAL WATER FLOW CONTROL VALVES RCP N2 BOTTLES NITROGEN FOR FCV-1115A, B, C RCP FI, FT-3114A RCP A SEAL WATER FLOW INSTRUMENTATION RCP FI, FT-2114B,C RCP B,C SEAL WATER FLOW INSTRUMENTATION RCP PIPING SEAL INJECTION PIPING FROM CONTAINMENT PENETRATIONS B-7A, B-7B, AND B-7C TO REACTOR COOLANT PUMPS RCP PIPING PIPING FROM REACTOR COOLANT PUMPS TO RV 2004 RCP PCV-1115A,B,C REACTOR COOLANT PUMP SEAL WATER DISCHARGE PRESSURE CONTROL VALVES(1)

LDS PIPING PIPING FROM REACTOR VESSEL LOOP A COLD LEG TO REGENERATIVE HEAT EXCHANGER(1)

LDS LCV-1112 REACTOR COOLANT LETDOWN CONTROL VALVE( 1)

LOS PIPING PIPING FROM REGENERATIVE HEAT EXCHANGER TO CV-202, CV-203, AND CV-204(1 )

LOS CV-202,3,4 REACTOR COOLANT LETDOWN CONTROL VALVES RCS NE, NI-1201,1202 SOURCE RANGE MONITORS Tornado Resistance Design Review for 4-3 S

San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 Il0lII~llIII~ll

TABLE 4-2 COMPONENTS REQUIRED FOR PRIMARY PRESSURE CONTROL SYSTEM COMPONENT COMMENTS PZR C-2 PRESSURIZER PZR LT,LI-430,1,2 PZR LEVEL INSTRUMENTATION PZR PT,PR-425 PZR PRESSURE INSTRUMENTATION PZR PIPING PIPING FROM THE PRESSURIZER TO THE PRESSURIZER RELIEF TANK PZR CV-530,1 PRESSURIZER BLOCK VALVES PZR CV-545,6 PRESSURIZER POWER OPERATED RELIEF VALVES PZR CV-532 N2 CONTROL VALVE PZR N2 BOTTLES BACKUP NITROGEN CV-530,531,545,546 PZR SV-532A PILOT VALVE FOR CV-532 PZR E-999 PRESSURIZER HEATERS PZR PIPING PIPING ASSOCIATED WITH LOOP A AND B PRESSURIZER SPRAY(1 )

VCC CV-305 AUX SPRAY FROM CHARGING PUMPS( 1)

RCS TE,TI-2401A RCS WIDE RANGE T-HOT RCS TE,TI-3411A RCS WIDE RANGE T-HOT RCS TE,TI-3421A RCS WIDE RANGE T-HOT RCS TI-2010,3010 RCS SUBCOOLING MARGIN TE-2422A,3421A MONITOR INSTRUMENTATION PT-425X1,X2 Tornado Resistance Design Review for 4-4 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 4-3 COMPONENTS REQUIRED FOR DECAY HEAT REMOVAL SYSTEM COMPONENT COMMENTS MSS E-1A,B,C STEAM GENERATORS MSS LI-451,2,3 STEAM GENERATOR LEVEL INSTRUMENTATION MSS LI-450A,1A,2A STEAM GENERATOR LEVEL INDICATOR MSS PT-459 MAIN STEAM PRESSURE TRANSMITTER MSS PI-458B MAIN STEAM PRESSURE INDICATOR MSS PIPING PIPING FROM STEAM GENERATORS TO STEAM DUMP VALVES CV-76, 77, 78, AND 79 MSS CV-76,77,78,79 STEAM DUMP VALVES MSS SV-85,6,7,8 STEAM DUMP PILOT VALVES MSS SV-175 PILOT VALVE FOR STEAM DUMP PILOT VALVES MSS N2 BOTTLES NITROGEN FOR CV-76,77,78,79 MSS RV-1 to 10 MAIN STEAM PRESSURE RELIEF VALVES(1)

MSS PIPING PIPING FROM STEAM DUMP HEADERS TO(1)

TURBINE STOP VALVES MSS PIPING PIPING ASSOCIATED WITH REHEATERS E-25A, E-25B, E-25C, AND E-25D(1 )

)

MSS MOV-14 to 17 STEAM ISOLATION VALVE TO E-25A,B,C,D(1 )

MSS CV-124 to 131 STEAM CONTROL VALVES TO E-25A,B,C,D(1 )

CND PIPING CONDENSATE STORAGE TANK TO CONDENSERS CND CV-20 CONDENSATE TO CONDENSER ISOLATION VALVE

)

CND E-2A,B CONDENSERS(1)

CND PIPING CONDENSERS TO CONDENSATE PUMPS CND G-1A,B,C,D CONDENSATE PUMPS CND PIPING CONDENSATE PUMPS TO AIR EJECTORS(1)

(

CND E-22A,B AIR EJECTORS(1)

CND PIPING PIPING FROM AIR EJECTORS TO GLAND SEAL STEAM CONDENSERS(1)

Tornado Resistance Design Review for 4-5 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 IIIIIIII IIIl0II

TABLE 4-3 COMPONENTS REQUIRED FOR DECAY HEAT REMOVAL (continued)

SYSTEM COMPONENT COMMENTS MSS PIPING PIPING FROM MAIN STEAM HEADER CROSS CONNECT TO TURBINE GLAND SEAL(1)

MSS PIPING PIPING FROM MAIN STEAM HEADER TO EAST AND WEST AIR EJECTORS(1)

MSS PIPING PIPING FROM MAIN STEAM HEADER TO AFW TURBINE (X-1062)

MFW PIPING CONDENSATE DRAIN LINE FROM AUXILIARY FEEDWATER DUMP TURBINE STEAM LINE AFW CV-113 STEAM CONTROL VALVE FOR AFW TURBINE AFW PC-8 PRESSURE CONTROLLER FOR CV-113 AFW N2 BOTTLES NITROGEN FOR CV-113 AFW CV-3201 STEAM CONTROL VALVE FOR AFW TURBINE AFW N2 BOTTLES NITROGEN FOR CV-3201 AFW SV-3201 PILOT VALVE FOR CV-3201 AFW X-1062 AUXILIARY FEEDWATER PUMP TURBINE AFW G-10,10S AUXILIARY FEEDWATER PUMPS AFW D-2A AUXILIARY FEEDWATER TANK CND D-2 CONDENSATE STORAGE TANK CND LT-6A D2 LEVEL TRANSMITTER CND LIS-6A D2 LEVEL INDICATING SWITCH CND PIPING PIPING FROM CONDENSATE STORAGE TANK TO AUXILIARY FEEDWATER PUMPS AFW PIPING PIPING FROM AUXILIARY FEEDWATER TANK TO AUXILIARY FEEDWATER PUMPS Tornado Resistance Design Review for 4-6 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 4-3 COMPONENTS REQUIRED

(*

FOR DECAY HEAT REMOVAL (continued)

SYSTEM COMPONENT COMMENTS AFW PIPING PIPING FROM AUXILIARY FEEDWATER PUMPS TO PENETRATIONS C-3A, C-3B, AND C-3C AFW CV-3213 AUXILIARY FEEDWATER PUMP (G-10)

DISCHARGE CONTROL VALVE AFW N2 BOTTLES NITROGEN FOR CV-3213 AFW SV-3213 PILOT VALVE FOR CV-3213 AFW MOV-1202 AUXILIARY FEEDWATER PUMP (G-10S)

DISCHARGE VALVE AFW MOV-1204 AUXILIARY FEEDWATER TO 1ST POINT HEATER ISOLATION(1)

AFW FCV-2300 AUXILIARY FEEDWATER TO STEAM GENERATOR E-1A FLOW CONTROL VALVE AFW FCV-3301 AUXILIARY FEEDWATER TO STEAM GENERATOR E-1B FLOW CONTROL VALVE AFW FCV-2301 FLOW CONTROL BYPASS VALVE FOR FCV-3301 AFW FCV-3300 AUXILIARY FEEDWATER TO STEAM GENERATOR E-1C FLOW CONTROL VALVE AFW FE,FTL,FTH,FI-3453 AFW FLOW INSTRUMENTATION AFW FE,FTL,FTH,FI-3454 AFW FLOW INSTRUMENTATION AFW FE,FTL,FTH,FI-3455 AFW FLOW INSTRUMENTATION CND E-23A,B GLAND SEAL STEAM CONDENSERS CND PIPING PIPING FROM GLAND SEAL STEAM CONDENSER TO FLASH EVAPORATORS Tornado Resistance Design Review for 4-7 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 4-3 COMPONENTS REQUIRED FOR DECAY HEAT REMOVAL (continued)

SYSTEM COMPONENT COMMENTS CND PIPING BYPASS PIPING AROUND E-9A, E-8A, E-7A, AND CND-316(1 )

CND PIPING BYPASS PIPING AROUND E-9B, E-8B, E-7B,

0)

AND CND-315(1 )

CND E-9A,B FLASH EVAPORATORS CND PIPING PIPING FROM FLASH EVAPORATOR TO 3RD POINT HEATERS CND E-8A,B FEEDWATER HEATERS CND PIPING PIPING FROM 3RD POINT HEATERS TO 2ND POINT HEATERS CND E-7A,B FEEDWATER HEATERS FWH PIPING PIPING FROM 3RD POINT AND 2ND POINT HEATER HEADER TO FWH-360 AND FWH-361 CND PIPING PIPING FROM 2ND POINT HEATERS TO MAIN FEEDWATER PUMPS FWS G-3A,B FEEDWATER PUMPS FWS HV-854A,B FEEDWATER PUMP SUCTION VALVES SIS PIPING PIPING ASSOCIATED WITH SAFETY INJECTION SYSTEM SUCTION(1 )

SIS HV-853A,B SAFETY INJECTION SYSTEM SUCTION ISOLATION VALVES TO FEEDWATER PUMPS(1)

FWS PIPING PIPING FROM FEEDWATER PUMPS TO CONDENSER FWS CV-36,37 FEEDWATER TO CONDENSER ISOLATION FWS PIPING PIPING ASSOCIATED WITH CV-875A,B FWS CV-875A,B FEEDWATER TO CONDENSER CROSSTIE ISOLATION VALVES Tornado Resistance Design Review for 4-8 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 4-3 COMPONENTS REQUIRED

• p FOR DECAY HEAT REMOVAL (continued)

SYSTEM COMPONENT COMMENTS FWS PIPING PIPING FROM FEEDWATER PUMPS TO CONTAINMENT PENETRATIONS C-3A, B, AND C SIS PIPING PIPING ASSOCIATED WITH SAFETY INJECTION SYSTEM DISCHARGE(1)

SIS HV-851A,B SAFETY INJECTION SYSTEM DISCHARGE ISOLATION VALVES( 1 )

FWS HV-852A,B FEEDWATER PUMP DISCHARGE ISOLATION VALVES FWS E-6A,B 1ST POINT HP HEATERS FWS PIPING BYPASS PIPING AROUND E-6A,B(1 )

FWS MOV-20,21,22 FEEDWATER TO STEAM GENERATOR ISOLATION VALVES FWS FCV-456,7,8 FEEDWATER TO STEAM GENERATOR FLOW CONTROL VALVES FWS CV-142, 143, 144 BYPASS FLOW CONTROL VALVES AROUND MOV-20, 21, 22 FWS PIPING PIPING FROM PENETRATIONS C-3A, B AND C TO STEAM GENERATORS FWS PIPING PIPING FROM STEAM GENERATORS TO PENETRATIONS C-1A, B, AND C(

FWS PIPING PIPING FROM PENETRATIONS C-1A, B AND C TO VALVES FWS 518, 522 AND 523(1)

Tornado Resistance Design Review for 4-9 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 4-4

4)

COMPONENTS REQUIRED FOR ONSITE EMERGENCY POWER SYSTEM AND

• h AUXILIARY SYSTEMS SYSTEM COMPONENT COMMENTS ELECTRICAL G-14,15 EMERGENCY DIESEL GENERATORS A1C,A2C 4160V SWITCHGEAR BUSES X06,XO7,XO8 STATION SERVICE TRANSFORMERS 1,2,3 BO1,BO2,BO2A,B03 480V MOTOR CONTROL CENTERS 1,2,2A,3 B04,B05,BO6 480V SWITCHGEAR BUSES 1,2,3 B11,B12 480V MOTOR CONTROL CENTERS 1B,2B CONTROL ROOM PANELS ALL D01 125VDC SWITCHGEAR #1 D02,DO3 BATTERY CHARGERS A,B D04 STATION BATTERY #1 D08 125VDC SWITCHGEAR #2 D09,D1O BATTERY CHARGERS C,D SD11 STATION BATTERY #2 Y11 VITAL BUS 1 Y12 VITAL BUS 2 Y13 VITAL BUS 3 Y14 VITAL BUS 4 Y29 VITAL BUS 5 Y30 VITAL BUS 6

)

HVAC A-31 CONTROL ROOM AIR CONDITIONING UNIT A-33 EMERGENCY MAKEUP FAN Tornado Resistance Design Review for 4-10 San Onofre Nuclear Generating Station Unit 1 IIIlIIllIl il Report No. TR-85028-02, Revision 0

01 5.0 STRUCTURES 4*

SONGS 1 consists of eight primary structures and/or buildings. These are:

1. Control Administration Building

2. Reactor Auxiliary Building

3.

Fuel Storage Building

4. Turbine Building 5

Ventilation Equipment Building 6

Containment Sphere and Enclosure Building

7. Diesel Generator Building

8.

Intake Structure

• p Portions of these structures and buildings house and/or support components required for the operation of the tornado shutdown systems and therefore require evaluation considering wind and missile loadings. The portions of these structures and buildings requiring

• p evaluation are listed in Table 5-1.

Tornado Resistance Design Review for 5-1 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 5-1 PLANT STRUCTURES EVALUATED Structure/Building Associated Systems/Components

4)

1. Control Administration Building

a. Control Room Main Control Panels Electrical Raceways

b. Ventilation Room Control Room Ventilation System

)

c. 4160 Volt Switchgear Room 4160 Volt Switchgear Cable Spreading Area Electrical Raceways

d. DC Switchgear Room #1 DC Switchgear #1

()

1. 1 Battery Chargers/Inverter

e. Battery Room #1

1. 1 Station Batteries

2. Reactor Auxiliary Building VCC System LDS System CRS System RCP System Electrical Raceways MCC #2A

3. Fuel Storage Building

a. Spent Fuel Pool Spent Fuel Racks

b. Block Walls above Pool Spent Fuel Racks Electrical Raceways

c. 480 Volt Switchgear Room 480 Volt Switchgear

()

MCC #2 Electrical Raceways Tornado Resistance Design Review for 5-2 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 5-1 PLANT STRUCTURES EVALUATED

()

(continued)

Structure/Building Associated Systems/Components

4. Turbine Building

a. Turbine Deck and North Extension MSS System FWS System CND System AFW System Electrical Raceways

b. West Side Masonry Block Walls AFW System FWS System

(

Electrical Raceways

5. Ventilation Equipment Building Electrical Raceways

6. Containment Sphere and Sphere RCS System Enclosure Building MSS System RPS System VCC System LDS System FWS System Electrical Penetrations Electrical Raceways

7. Diesel Generator Building Emergency Diesel Generators DC Switchgear #2

1. 2 Station Batteries

8. Intake Structure None Tornado Resistance Design Review for 5-3 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 I0ln IIIIlIIIIII

6.0 DAMAGE EVALUATION

()

The components and structures required to place and maintain the plant in a safe shutdown condition were evaluated for damage resulting from a tornado event.

The evaluation began by reviewing NRC Safety Evaluation Reports [1], [2]. The components and

()

structures included in the tornado shutdown system not fully qualified by NRC evaluation were then evaluated for tornado induced damage. These two evaluations are described in the following sections.

6.1 Review of Safety Evaluation Reports An evaluation of the structures at SONGS 1 was performed by the NRC. This evaluation was performed to identify which structures and/or portions of structures would be capable of withstanding the postulated tornado loads [1], [2].

These evaluations considered a tornado wind speed of 250 mph, a pressure drop (differential pressure) of 1.5 psi occurring in 4.5 seconds and two postulated missiles. These missiles consisted of a 1 inch diameter, 3 foot long steel rod with a total horizontal velocity of 229 ft/sec, and a 13 1/2" diameter, 35 foot long utility pole with a total horizontal velocity of 152 ft/sec.

The purpose of reviewing the SERs was to remove those components and structures determined as being capable of withstanding tornado events from further evaluation efforts.

The NRC performed no component damage evaluations, therefore no components located outside structures could be removed from the evaluation scope. However, the NRC did determine that various structures were adequately qualified. Components located within these structures required no further evaluation.

The structures determined to be capable of Tornado Resistance Design Review for 6-1 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 IIIIlSI~ lIIIlIIl

withstanding the tornado winds, the pressure drops, and the missile loads are listed below.

1. Containment Sphere

2. Sphere Enclosure Building

3. Diesel Generator Building

4. Reactor Auxiliary Building (portion below grade) 6.2 Damage Evaluation Components located outside the structures listed above and structures not listed above were evaluated for tornado induced damage following the criteria of [4].

The structural evaluation results indicated that missile loads were orders of magnitude above wind and pressure drop loads and controlled the failure of most structures. Therefore, because components offer little wind resistance compared to structures, and missile loads control the failure results, most components were evaluated for only missile induced failure.

6.2.1 Structural Evaluation Structures housing shutdown systems and components were evaluated first. This allowed a further reduction of the component evaluation scope by reducing the number of "exposed" components.

Table 6-1 presents a list of the structures evaluated and the tornado event probability to which they are qualified. A "yes" indicates that the structure is expected to withstand the tornado event while a "no" indicates a failure.

S Tornado Resistance Design Review for 6-2 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 illIlS~lIIIIIIIl

6.2.2 Component Evaluation As previously stated, component evaluations were limited to missile damage. Component specific failure results determined for each probability event are presented in Tables 6-2, 6-3, 6-4, and 6-5. The comment column in Tables 6-2, 6-3 and 6-4 describes support systems whose failure will preclude the operation of the component or provides additional information regarding the tabulated failure result. Shutdown system flowcharts based on shutdown function are shown on Figures 6-1 and 6-2 with failure results included. The following key is to be used in reading the flowcharts:

0 1

2 3

1:

Component Description 2:

Tornado event probability at which component cannot be qualified 3:

Tornado event probability at which component's support system(s) cannot be qualified Q:

Component qualified to 10-7 event probability PRO:

Component protected by a qualified structure SHLD:

Component not vunerable to missile strike due to intervening structures and components 0

Tornado Resistance Design Review for 6-3 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 II0lIII~lI~lIIII

TABLE 6-1 TORNADO WINDSPEED AND MISSILE QUALIFICATION OF STRUCTURES STRUCTURE ANNUAL PROBABILITY OF OCCURRENCE

(

10-4 10-5 10- 6 10-7

1. CONTROL ROOM

i.

Wind Pressure YES(1)

YES YES YES ii. NRC Missiles 9" R/C east wall YES NO(3)

NO( 2)

NO iii. Control room roof 7 1/2" R/C YES YES YES NO

2. DC SWITCHGEAR ROOM #1

i. 8" R/C West Wall

a.

Wind Pressure YES(1)

YES YES YES

b.

NRC Missiles NO( 3)

NO NO NO ii. 8" MASONRY BLOCK EAST WALL

a. Wind Pressure YES YES NO( 4)

NO

b.

NRC Missiles (5)

(5)

(5)

(5) 9

3. 4160V SWITCHGEAR ROOM

i. Wind Pressure YES(1)

YES YES YES ii. NRC Missiles YES YES YES YES

4. VENT. EQUIP. BLDG.

MASONRY WALLS

i. Wind Pressure YES YES YES NO(6) ii. NRC Missiles (5)

(5)

(5)

(5)

Tornado Resistance Design Review for 6-4 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

0 TABLE 6-1 TORNADO WINDSPEED AND MISSILE QUALIFICATION OF STRUCTURES (continued)

STRUCTURE ANNUAL PROBABILITY OF OCCURRENCE 10-4 10-5 10- 6 10-7

5. TURBINE BUILDING MASONRY WALLS

i. Wind Pressure

a.

Group 1 YES YES NO(7)

NO

b.

Group 2 YES YES YES NO(6)

c.

Group 3 YES YES NO( 8)

NO ii. NRC Missiles (5)

(5)

(5)

(5)

6. NORTH TURBINE BUILDING DECK

i. 8 1/2" R/C deck YES YES YES YES

7. FUEL STORAGE BLDG.

MASONRY WALLS

i.

Wind Pressure YES YES NO( 9)

NO ii. NRC Missiles (5)

(5)

(5)

(5)

NOTES:

1. Qualification based on [1]

2. Utility pole perforation at 133 mph windspeed

3. Utility pole causes excessive wall displacement

4. Failure velocity is approximately 140 mph

5. Missile protection by masonry block walls is not considered [2]

6. Failure velocity is approximately 157 mph

7. Failure velocity is approximately 106 mph g

8. Failure velocity is approximately 125 mph

9. Failure velocity is approximately 133 mph Tornado Resistance Design Review for 6-5 San Onofre Nuclear Generating Station Unit 1 lIIIII I.

Report No. TR-85028-02, Revision 0

TABLE 6-2 REACTIVITY AND PRIMARY COOLANT INVENTORY CONTROL Component Description Failure Comments D-1 RWST Perforation 10-6 Piping RWST to Charging Pumps Yield 10-6 Piping Piping Associated with Yield 10-4 Recirculation Heat

1)

Exchanger (E-11) and Valves CRS-302, 303, 329, 330 and 426 MOV-1100B RWST to Charging Pump Suction Protected 480V MCC No. 1 MOV-1100D RWST to Charging Pump Suction Protected 480V MCC No. 3 G-8A Charging Pump Protected Failure of Cables and Raceways at 10-4 G-8B Charging Pump Protected 4160V Bus No. 1C G-942 Lube Oil Pump (G-8A)

Protected Failure of XFMR #2 I

at 10-4 G-943 Lube Oil Pump (G-8B)

Protected Failure of Cables and Raceways at 10-4 G-908 Lube Oil Pump (G-8A)

Protected Failure of XFMR #2 at 10-4 G-909 Lube Oil Pump (G-8B)

Protected Failure of XFMR #2 at 10-4 G-42 Test Pump Protected 480V MCC No. 2A 41 FCV-1112 Charging Pump Discharge flow Protected Requires backup N2 Control Valve FT-3114A Reactor Coolant Pump Loop A Seal Water Flow Transmitter 10-4 Failure of Cables and Raceways at 10-4 Tornado Resistance Design Review for 6-6 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 6-2 REACTIVITY AND PRIMARY COOLANT INVENTORY CONTROL (continued)

Component Description Failure Comments FT-2114B Reactor Coolant Pump Loop B Seal Water Flow Transmitter 10-4 Failure of Cables FT-2114C Reactor Coolant Pump Loop C and Raceways at 10-4 Seal Water Flow Transmitter 10- 4 Failure of Cables and Raceways at 10-4 NE, NI-1201 Neutron Source Range Monitor Protected Failure of Cables and Raceways at 10-4 NE, NI-1202 Neutron Source Range Monitor Protected Failure of Cables and Raceways at 10-4 0

Tornado Resistance Design Review for 6-7 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 6-3 PRIMARY PRESSURE CONTROL Component Description Failure Comments E-999 Pressurizer Heaters Protected 480 Volt SWGR Number 1 and 2 N2 Supply N2 Supply to Pressurizer PORV and Block Valves Yield 10 LT-430 Pressurizer Level Transmitter Protected Vital Bus 1 Through 3 LT-431 Pressurizer Level Transmitter Protected Vital Bus 1 Through 3

)

LT-432 Pressurizer Level Transmitter Protected Vital Bus 1 Through 3 LT-435 Pressurizer Level Transmitter Protected Vital Bus 1 Through 3 PT-425 Pressurizer Pressure Transmitter Protected Vital Bus 1 Through 3 TE-401A Loop A Temperature Differential Protected Failure of cabling at 10 TE-401C Loop A Temperature Differential Protected Failure of cabling at TE-411A Loop B Temperature Differential Protected Failure of cabling at 10 TE-411C Loop B Temperature Differential Protected Failure of cabling at TE-421A Loop C Temperature Differential Protected Failure of cabling at 10 TE-421C Loop C Temperature Differential Protected Failure of cabling at N2SuyTornado Resistance Design Review for 6-8 PresSan Onofre Nuclear Generating Station Unit 1 PressReport No. TR-85028-02, Revision 0 Prsuie ee0rnmte

TABLE 6-4 DECAY HEAT REMOVAL Component Description Failure Comments Piping Piping from Steam Generators to Steam Dump Valves C-76, C-77, C-78, and C-79 Qualified CV-76, 77, 78, 79 Steam Dump Valves Qualified SV-85, 86 87, 88 Pilot Valves for Steam Dump Valves Perforation 10- 4 125V DC System No. 1 SV-175 Pilot Valve for

)

Steam Dump Valves Perforation 10-4 N2 Supply N2 Supply to the Steam Dump Valves Perforation 10-4 RV-1 TO 10 Main Steam Pressure

)

Relief Valves Qualified Piping Piping Associated with Reheaters Yield 10-4 E-25A, E-25B, E-25C and E-25D PT-459 Main Steam Header Pressure Shielded

)

Piping Piping from Steam Dump Headers to Turbine Stop Valves Qualified MOV-14 TO 17 Steam Isolation Valves

4) to E-25A, E-25B, E-25C, and E-25D Shielded 480V MCC No.3 Tornado Resistance Design Review for 6-9 San Onofre Nuclear Generating Station Unit 1 iHI Report No. TR-85028-02, Revision 0

e1 TABLE 6-4 DECAY HEAT REMOVAL

• )

(continued)

Component Description Failure Comments CV-124 TO 131 Steam Control Valves to E-25A, E-25B, E-25C, and E-25D Shielded FCV-2301 Flow Control Bypass Valve for FCV-2301 Yield 10-4 FCV-3300 Auxiliary Feedwater to Steam Generator Yield 10-4 FCV-3301 Auxiliary Feedwater to Steam Generator Yield 10-4 FCV-2300 Auxiliary Feedwater to Steam Generator Yield 10-4 Piping Piping from Condensate Storage Tank to Condenser Yield 10-4 LT-6A Auxiliary Feedwater Storage Tank Level Transmitter 10-4 CV-20 Condensate to Condenser Isolation Valve Yield 10-4 E-2A Condenser Qualified E-2B Condenser Qualified G-1A, B, C Condensate Pumps Shielded 4160V SWGR 1C and D and 2C Piping Piping from Condensate Pumps to Air Ejectors 10-4 E-22A, B Air Ejectors Qualified 0

Tornado Resistance Design Review for 6-10 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 6-4 DECAY HEAT REMOVAL

(*

(continued)

Component Description Failure Comments Piping Piping from Air Ejectors to Gland Seal Steam Condensers 10-4 Piping Piping from Main Steam Header to Air Ejectors 10-4 Piping Piping from Main Steam Header to AFW Turbine Yield 10-4 Piping Condensate Drain Line from Auxiliary Feedwater Turbine Steam Line Yield 10-4 CV-113 Steam Control Valve for AFW Turbine Yield 10-4 PC-8 Pressure Controller for CV-113 Yield 10-4 CV-3201 Steam Control Valve for AFW Turbine Yield 10- 4 120V AC N2 Supply N2 Supply to CV-3201 Perforation 10-4 X-1062 Auxiliary Feedwater Pump Turbine Yield 10-6 G-10 Auxiliary Feedwater Pump Turbine Driven Pump Yield 10-6 D-2 Condensate Storage Tank Perforation 10-6 D-2A Auxiliary Feedwater Tank Perforation 10- 6 Perforation

()

acceptable (1)

Piping Piping from Condensate Storage Tank to Auxiliary Feedwater Pumps Yield 10-4 Tornado Resistance Design Review for 6-11 San Onofre Nuclear Generating Station Unit 1 IIl l

Report No. TR-85028-02, Revision 0

TABLE 6-4 DECAY HEAT REMOVAL

• )

(continued)

Component Description Failure Comments Piping Piping from Auxiliary Feedwater Tank to Auxiliary Feedwater Pumps Yield 10-4 G-10S Auxiliary Feedwater Pump Motor Driven Yield 10-4 480V SWGR No. 1 N2 Supply N2 Supply to CV-113 Perforation 10-4 SV-3201 N2 Pilot Valve to CV-3201 Perforation 10-4 120V AC Vital Bus No. 5

)

Piping Piping from Auxiliary Feedwater Pumps to Penetrations C-3A, C-3B, and C-3C Yield 10-4 CV-3213 Auxiliary Feedwater Pump

)

(G-10) Discharge Valve Yield 10-4 N2 Supply N2 Supply to CV-3213 Perforation 10-4 SV-3213 N2 Pilot Valve to CV-3213 Perforation 10-4 120V Vital Bus No. 5 MOV-1202 Auxiliary Feedwater Pump

(

G-10S) Discharge Valve Yield 10-4 480 MCC No. 1 MOV-1204 Auxiliary Feedwater to 1st Point Yield 10-4 480 MCC No. 1 FE-3453 Auxiliary Feedwater to

• )

Steam Generator E-1A Flow Element 10-4 FE-3454 Auxiliary Feedwater to Steam Generator E-1B Flow Element 10-4 0

Tornado Resistance Design Review for 6-12 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 6-4 DECAY HEAT REMOVAL

• b (continued)

Component Description Failure Comments FE-3455 Auxiliary Feedwater to Steam Generator E-1C Flow Element 10-4 FTL-3453 Auxiliary Feedwater Flow t*

Transmitter -

Low for Steam Generator E-1A 10-4 FTH-3453 Auxiliary Feedwater Flow Transmitter -

High for Steam Generator E-1A 10-4 FTL-3454 Auxiliary Feedwater Flow Transmitter -

Low for Steam Generator E-1B 10-4 FTH-3454 Auxiliary Feedwater Flow Transmitter -

High for Steam Generator E-1B 10-4 FTL-3455 Auxiliary Feedwater Flow

4)

Transmitter -

Low for Steam Generator E-1C 10-4 FTH-3455 Auxiliary Feedwater Flow Transmitter - High for

)

Steam Generator E-1C 10-4 LT-2400A Steam Generator E-1A Level Transmitter Protected Failure of Cables and Raceways at 10-4 Tornado Resistance Design Review for 6-13 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 6-4 DECAY HEAT REMOVAL M*

(continued)

Component Description Failure Comments LT-3400A Steam Generator E-1A Level Transmitter Protected Failure of Cables and Raceways at 10-4 LT-450 Steam Generator E-1A Level Transmitter Protected Failure of Cables and Raceways at 10-4 LT-2400B Steam Generator E-1B Level Transmitter Protected Failure of Cables and Raceways at 10-4 LT-3400B Steam Generator E-1B Level Transmitter Protected Failure of Cables and Raceways at 10-4 LT-451 Steam Generator E-1B Level Transmitter Protected Failure of Cables and Raceways at 10-4 LT-2400C Steam Generator E-1C Level Transmitter Protected Failure of Cables and Raceways at 10-4 Tornado Resistance Design Review for 6-14 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 6-4 DECAY HEAT REMOVAL

()

(continued)

Component Description Failure Comments

)

LT-3400C Steam Generator E-1C Level Transmitter Protected Failure of Cables and Raceways at 10-4 LT-452 Steam Generator E-1C Level Transmitter Protected Failure of Cables and Raceways at 10-4 E-23A, B Gland Seal Steam Condensers Qualified Piping Bypass Piping Around E-9A, E-8A, E-7A, and CND-316 Yield 10-4 Piping Bypass Piping Around E-9B, E-8B, E-7B, and CND-315 Yield 10-4 E-9A Flash Evaporator Qualified E-9B Flash Evaporator Qualified Piping Piping from flash evaporators Yield 10-4 to 3rd Point Heater E-8A, B Feedwater Heaters Qualified E-7A, B Feedwater Heaters Qualified Piping Piping from 3rd and 2nd Point Yield 10-4 Heater to FWH-360 and FWH-361 Piping Piping from 2nd Point Heaters to Main Feedwater Pumps Yield 10-4 G-3A Feedwater Pump Yield 10-7 4160V Bus 2C G-3B Feedwater Pump Yield 10-7 4160V Bus 1C 0

I Tornado Resistance Design Review for 6-15 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

0 TABLE 6-4 DECAY HEAT REMOVAL (continued)

Component Description Failure Comments HV-854A Feedwater Pump Suction Valve Yield 10-4 125VDC Bus No. 2 HV-854B Feedwater Pump Suction Valve Yield 10-4 125VDC Bus No. 1 Piping Piping Associated with Safety Injection Water Suction Yield 10-4 HV-853A Safety Injection System Suction Isolation Valve to Feedwater Pump Yield 10-4 125VDC Bus No. 2 HV-853B Safety Injection System Suction Isolation Valve to Feedwater Pump Yield 10-4 125VDC Bus No. 1 Piping Piping from Feedwater Pumps to Condenser Isolation Yield 10-4 CV-36 Feedwater to Condenser Isolation Shielded 125VDC Bus No. 2 CV-37 Feedwater to Condenser Isolation Shielded 125VDC Bus No. 1 Piping Piping Associated with CV-875A Yield 10-4 Piping Piping Associated with CV-875B Yield 10-4 CV-875A Feedwater to Condenser Crosstie Isolation Valve Yield 10-4 125VDC Bus No.

2 CV-875B Feedwater to Condenser Crosstie Isolation Valve Yield 10-4 125VDC Bus No.

1 Piping Piping from Feedwater Pumps to Containment Penetrations C-3A, C-3B and C-3C Yield 10-4 Piping Piping Associated with Safety Injection System Discharge Yield 10-4 Tornado Resistance Design Review for 6-16 San Onofre Nuclear Generating Station Unit 1 Report No.

TR-85028-02, Revision 0 0lilllllllnll l

TABLE 6-4 DECAY HEAT REMOVAL

4)

(continued)

Component Description Failure Comments HV-851A Safety Injection System Discharge Isolation Valve Yield 10-4 125VDC Bus No. 2 HV-851B Safety Injection System Discharge Isolation Valve Yield 10- 4 125VDC Bus No. 1 HV-852A Feedwater Pump Discharge Isolation Valve Qualified 125VDC Bus No. 2 HV-852B Feedwater Pump Discharge Isolation Valve Qualified 125VDC Bus No. 1 E-6A 1st Point HP Heater Shielded E-6B 1st Point HP Heater Shielded Piping Piping around E-6A and E-6B Shielded MOV-20 Feedwater to Steam

)

Generator E-1B Isolation Valve Shielded 480V MCC No.

1 MOV-21 Feedwater to Steam Generator E-1A Shielded 480V MCC No.2 MOV-22 Feedwater to Steam Generator E-1C Isolation Valve Shielded 480V MCC No. 3 FCV-456 Flow Control valve down stream Shielded

1) of MOV-21 FCV-457 Flow Control valve down stream Shielded of MOV-20 FCV-458 Flow Control valve down stream Shielded

• h of MOV-22 CV-142 Bypass around MOV-21 Shielded CV-143 Bypass around MOV-22 Shielded Tornado Resistance Design Review for 6-17 San Onofre Nuclear Generating Station Unit 1 i m Report No. TR-85028-02, Revision 0

0 TABLE 6-4 DECAY HEAT REMOVAL

()

(continued)

Component Description Failure Comments CV-144 Bypass around MOV-20 Shielded Piping Piping from Pentrations Yield 10-4 C-1A, B and C to the Steam Generator Blowdown Tank Note:

1. Perforation of the top course of the AFW Tank will occur at 10-6 wind speed probability occurrence. However, sufficient water will still be available.

0 Tornado Resistance Design Review for 6-18 San Onofre Nuclear Generating Station Unit 1 IIii I

Report No. TR-85028-02, Revision 0

TABLE 6-5 ONSITE EMERGENCY POWER SYSTEM

• h AND AUXILIARY SYSTEMS Component Description Failure G-14 Diesel Generator No. 1 Failure of Station Battery No. 1 at 10-4 A1C 4160V SWGR Bus 1C Failure of Station Battery No. 1 at 10-4 X06 Station Service XFMR No. 1 Failure of XFMR No. 1 at 10-4 Failure of Cables and Raceways at 10-4 Failure of Station Battery No. 1 at 10-4

)

X07 Station Service XFMR No. 2 Failure of XFMR No. 2 at 10-4 Failure of Cables and Raceways at 10-4 X08 Station Service XFMR No. 3 Failure of XFMR No. 3 at 10- 4 Failure of Cables and Raceways at 10-4 Failure of Station Battery

)

No. 1 at 10-4 B04 480V SWGR Bus 1 Failure of Station Battery No. 1 at 10-4 Failure of XFMR No. 1 at 10-4 Failure of Cables and Raceways at 10-4 Tornado Resistance Design Review for 6-19 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 6-5 ONSITE EMERGENCY POWER SYSTEM AND AUXILIARY SYSTEMS (continued)

Component Description Failure B05 480V SWGR Bus 2 Failure of XFMR No. 2 at 10-4 Failure of Cables and Raceways at 10-4 B06 480V SWGR Bus 3 Failure of Station Battery No. 1 at 10-4 Failure of XFMR No. 3 at 10-4 Failure of Cables and Raceways at 10-4 B01 480V MCC 1 Failure of Station Battery No. 1 at 10-4 Failure of XFMR No. 1 at 10-4 Failure of Cables and Raceways at 10-4 B11 480V MCC lB Failure of Station Battery No. 1 at 10-4 Failure of XFMR No. 1 at 10-4 4*

Failure of Cables and Raceways at 10-4 B02 480V MCC 2 Failure of XFMR No. 2 at 10-4 Failure of Cables and Raceways at 10-4 Tornado Resistance Design Review for 6-20 San Onofre Nuclear Generating Station Unit 1 lilil l

Report No. TR-85028-02, Revision 0

TABLE 6-5 ONSITE EMERGENCY POWER SYSTEM AND AUXILIARY SYSTEMS (continued)

Component Description Failure BO2A 480V MCC 2A Failure of XFMR No. 2 at 10-4 Failure of Cables and Raceways at 10-4 B12 480V MCC 2B Failure of XFMR No. 2 at 10-4 Failure of Cables and Raceways at 10-4 B03 480V MCC 3 Failure of Station Battery No. 1 at 10-4 Failure of XFMR No. 3 at 10-4

(*

Failure of Cables and Raceways at 10-4 D01 125VDC Bus No. 1 Failure of Switchgear Room at 10-4 D02 Battery Charger 'A' Failure of Switchgear Room at 10-4 Failure of Station Battery No. 1 at 10-4

)

Failure of XFMR No. 1 at 10-4 Failure of Cables and Raceways at 10-4 Tornado Resistance Design Review for 6-21 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 6-5 ONSITE EMERGENCY POWER SYSTEM g)

AND AUXILIARY SYSTEM (continued)

Component Description Failure D03 Battery Charger 'B' Failure of Switchgear Room at 10-4

(

Failure of XFMR No. 2 at 10-4 Failure of Cables and Raceways at 10-4 004 Station Battery Charger No. 1 Failure of Battery Room at 10-4 D09 Battery Charger 'C' Failure of Station Battery No. 1 at 10-4 Failure of XFMR No. 1 at 10-4 Failure of Cables and Raceways at 10-4 010 Battery Charger 'D' Failure of XFMR No. 2 at 10-4 Failure of Cables and Raceways at 10-4 Y11 Through Y14 120VAC Vital Buses 1 Through 4 Failure of Station Battery No. 1 at 10-4 Failure of XFMR Nos. 1 and 2 at 10-4 Failure of Cables and Raceways at 10-4 Tornado Resistance Design Review for 6-22 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 IIIISlnil~illII

TABLE 6-5 ONSITE EMERGENCY POWER SYSTEM (p

AND AUXILIARY SYSTEMS (continued)

Component Description Failure Y29, Y30 120VAC Vital Buses 5 and 6 Failure of Cables and Raceways

)

at 10-4 Failure of XFMR Nos. 1 and 2 at 10-4

)

Panels Control Room Panels Failure of Control Room East Wall at 10-6 Failure of Station Battery 1 at 10-4

• p Failure of Control Room Roof at 10-7 A-31, 33 Control Room HVAC Failure of Control Room East Wall g

at 10-6 Failure of Control Room Roof at 10-7 Tornado Resistance Design Review for 6-23 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 II0lII~lII~lIIII

FIGUE 6-1 REACTIVITY, PRIMARY INVENTURY AND PRESSURE CONTROL FLOWCHART 10 XFMRP 3 10-4 F480V SWGR 3 104 C

3106 06 BATTERY gl PRO D.

G.

I11 PRO 4 V S 1NGR IC 10- 4 10- 4 10 -

10-4 10 -

10- 4 V 1 00NO 0

10- 4 10-4T--jP1

-4 PRO 10-4

- 4

-4 MOV-1100D NE SUTIR lOV

-1100 10 xPHR 1 10 480 SWG PRO CC1PR 10 PRO PO PO 1

10 10-4 PRO 10-4 PRO 104 BATR $2-PRO D. G.

02 PRO 4xV SERA2CD.

PRO PRO PRO PRO PRO PRO 10-4 XF02 1-4 0VS~

10 MC A

1-2-APP-R 10 M 102 1

4 10 PRO 10i 2.1--

PRO PRO lo 4

l-l-4 4

L R10lo 10-4 G-42 G

AG-BSV-1112 PRO 10-PRO 1-PRO 10-4 PRO PRO Tis D.9

~PCV-1115B PCV-1115C IFCV-1115 A FCV-1112 N

~~~PER HTR B&D PER HTR ASC PO PO PO POPO POPO 1

10-10- 4 PRO 10- 4 PRO 10- 4 C

RPAV30 PO PO PRO PRO PRO PRO PRO PRO 5V-532 A PO10-4r PR 4

R AC TR PRPR 10 PCV-1125 B PCV-1115 PCV-1115 A CV-530 CV-531 AV-533 RV-532PR PO PO POPO PO PRO 10- 4 PRO 10-4 PRO PRO PRO PRO RV-2004 CV56CV-545 PRO PRO PR 0PR 10- 4 RCDT C-32 PRO PRO C-16 PRD PRO Tornado Resistance Design Review for 6-2.4, -

--San Onofre Nuclear Generating Station Unit 1 L--iLE.?

-Report No. TR-85028-02, Re visi on 0

0 9

9 0

0 0

FIGURE 6-2 DECAY HEAT REMOVAL FLOWCHMRT rarmu I1 10 40OV SWGIS 7 t 10 c

4KV SWIG& Ic It0-10 PRO 10-1 D. C.-

101 10 10-10 105 PROD 10 100-4 10-1 0 1E-2A4 1-1-

rv20 G-10 W

P 4

1040HD 1041 14 10-1-7 t-SGB 9-2

~~G-11lA 4

1A 1

0 ID 10 1

10-10 10 10 10 SHI.D 10-NV-2 10 T23.10

-4 ~

~

aL 1041 41 G-101 10 10 1

10

-6 to

-,1H 10 11V

-22524

-4D 10 10 II10W 1

-1062 CV-320131, 1o- 0610-10V4 3201014C-7104 BATTIERY 02 10-VIT.1 BUS _-7 1 0-CV-113/PC-8 N2 PRO r-0 1g 110-10-10- 10-104 04 SHLD 10 L 1__~~PR I0-RV-RO2RO,4,610 4.t-,0 Tornado ResistaVce30esigl Oeiwfr62 San ~ ~ ~

~

~

~

~

~

~

1 10feNcerGnraigSainUi Repor No. R-8528-02 PeViion7

e 7.0 PLANT UPGRADES A shutdown flowpath was developed to determine the best method of upgrading or protecting those components and structures determined to be incapable of enduring tornado events. This flowpath was based on the system flowcharts shown on Figures 6-1 and 6-2. Critical flowpaths were identified which maximize the use of qualified, shielded and/or protected components to reduce or eliminate potential modifications. The shutdown flowpaths developed from Figures 6-1 and 6-2 are shown on Figures 7-1 and 7-2 respectively.

A review of Figures 7-1 and 7-2 shows that the capability of safe shutdown cannot be demonstrated following a tornado event with 10-4 annual probability of occurrence without upgrades.

Upgrades will be required in the following general areas:

I STRUCTURES A. Turbine Building West Wall B. Control Room C.

D/C Switchgear and Battery Room No. 1 D.

Spent Fuel Building II PLANT SYSTEMS A.

Reactivity and Primary Coolant Inventory Control B.

Primary Pressure Control C.

Decay Heat Removal D.

Onsite Emergency Power Plant upgrades for the areas above have been developed for the necessary probable wind speed occurrences. These upgrades are discussed in the following sections.

Tornado Resistance Design Review for 7-1 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

7.1 Structures Four areas are constructed with masonry block or concrete walls that provide little or no protection against wind-generated missiles.

These areas consist of:

1. The Turbine Building

2. The Control Room

3. Switchgear and Battery Room No. 1

4.

Spent Fuel Building 7.1.1 Turbine Building The turbine building is exposed on the west, south, and east sides to wind generated missiles. With the exception of the west wall an impact by a wind generated missile will have no impact on those components outlined on the shutdown flowpaths, Figures 7-1 and 7-2. The west wall of the turbine building is constructed of masonry blocks and provides no missile protection.

To ensure the operability of the Auxiliary Feedwater (AFW) system as described in Section 7.4, modifications to the west wall of the turbine building are required. Possible modifications to ensure operability of the AFW system are:

1. Erect steel missile barriers

2. Erect a concrete wall To protect the AFW system it is recommended that the existing masonry wall be removed and a reinforced concrete wall erected.

This modification is outlined in Table 7-1, along with an estimated cost.

Tornado Resistance Design Review for 7-2 San Onofre Nuclear Generating Station Unit 1 IReport No. TR-85028-02, Revision 0

0 7.1.2 Control Room and HVAC With the exception of the east wall and portions of the control room roof the control room and the control room HVAC is considered protected [2].

The east wall of the control room is constructed of reinforced concrete 9-inches

• )

thick.

The evaluation requires modifications to the east wall of the control room at 10- 4, 10-5, 10- 6, and 10-7 wind speed probability occurrences.

Possible modifications to protect or qualify the east wall of the control room are:

1. Erect steel missile barrier

2.

Replace existing wall

3.

Apply pneumatically placed reinforced concrete layer To strengthen the east wall of the control room it is recommended that an additional reinforced concrete layer be 0

applied to the exterior surface of the wall.

This modification is outlined in Table 7-1, along with an estimated cost.

The control room roof on the east and southeast side of the control room is constructed with 7-1/2 inches of reinforced concrete. This is sufficient thickness to protect against vertical missiles generated at 10- 4, 10-5, and 10-6 wind speed probability occurrences. However, for a 10-7 wind speed probability occurrence protection is required.

Possible modifications to protect the east and south side of the control room are:

1. Steel missile barrier

2.

Replace existing roof

Tornado Resistance Design Review for 7-3 San Onofre Nuclear Generating Station Unit 1

=

=-Report No.

TR-85028-02, Revision 0 IIII0lIIIIIIlII

To protect the east and south side of the control room roof, it is recommended that the existing roof be removed and a thicker reinforced concrete one installed. This modification is outlined in Table 7-1, along with an estimated cost.

7.1.3 DC Switchgear and Battery Room No. 1 This room is located at the south end of the administration building at elevation 14'-0".

This room, with the exception of the east and west walls, has sufficient concrete wall and roof thicknesses to be considered protected [2].

The east and west walls are constructed of masonry blocks and 8 inches of reinforced concrete, respectively.

The batteries and switchgear are required to energize the g*

field windings of diesel generator No. 1 and to provide power for various control functions, including several control room panels.

The evaluation resulted in required modifications at 10-4 10-5, 10- 6, and 10-7 wind speed probability occurrences.

Tornado Resistance Design Review for 7-4 San Onofre Nuclear Generating Station Unit 1 Illiluiiiiiiiiii llt Report No.

TR-85028-02, Revision 0

Possible modifications to protect the DC switchgear and battery room No. 1 are:

1. Erect steel missile barrier

2.

Erect concrete missile barrier

3. Replace existing walls To protect the east and west walls it is recommended that reinforced concrete missile barriers be erected. This modification is outlined in Table 7-1, along with an estimated cost.

7.1.4 Spent Fuel Building The spent fuel building is located at the north west end of the turbine building and is constructed with reinforced concrete from elevation 14'-0" to 42'-0" and masonry blocks from elevation 42'-0" to 65'-10".

The reinforced concrete walls are of sufficient thickness to withstand missile impacts at 10-4, 10-5, 10-6, and 10-7 wind speed probability occurrences, however, the masonry block walls are not. A failure of the masonry block walls could potentially allow wind generated missiles to impact the spent fuel pool.

To determine what effect a wind generated missile would have on the spent fuel pool a 1,500 pound load was postulated to impact the spent fuel racks.

Based on this postulated load drop it was determined that no more than one fuel assembly could be damaged. The NRC in their evaluation of this load drop concluded that the radiological consequences were within 10 CFR Part 100 guidelines [11]. A further evaluation which considered the Tornado Resistance Design Review for 7-5 San Onofre Nuclear Generating Station Unit 1 Uiiiuiininimun Report No. TR-85028-02, Revision 0

exposure of the spent fuel pool to the surrounding environment, the higher average wind speeds, and the

• )

turbulent wind flow found that the resulting radiological releases were still within 10 CFR Part 100 guidelines.

Based on this evaluation no modification to the masonry walls are required.

7.2 Reactivity and Primary Coolant Inventory Control To ensure operation of the reactivity and primary coolant inventory control those components noted in the shutdown flowpath on Figure 7-1 are required to function and/or maintain their pressure boundary. To accomplish this effort upgrades will be required in the following areas:

1.

Nitrogen Backup To FCV-1112

2. Refueling Water Storage Tank

3. Refueling Water Storage Tank Suction Piping

4. Electrical Power Supply To Charging System Components

5.

Seal Water Flow Instruments

6. Neutron Monitor Instruments 7.2.1 Nitrogen Backup to FCV-1112 This flow control valve is the normal charging path discharge control valve and fails open on loss of power and/or air.

This may result in loss of RCP sealwater flow. The Appendix R Dedicated Shutdown System (DSD) [7]

is retrofitting backup nitrogen for this valve.

The backup nitrogen should be installed in a tornado protected manner.

Tornado Resistance Design Review for 7-6 M

- San Onofre Nuclear Generating Station Unit 1 Report No.

TR-85028-02, Revision 0 IIIII0lIII~ lIIlI

0 7.2.2 Refueling Water Storage Tank The refueling water storage tank (RWST) is located west of the fuel storage building at Elevation 14'-0" and is constructed with 1/4-inch steel plates. The evaluation determined that this thickness is sufficient to protect it against missiles generated at 10-4 and 10-5 wind speed probability occurrences. However, for 10-6 and 10-7 wind speed probability occurrences modifications are required.

Possible modifications to protect the refueling water storage tank are:

1. Erect new tank

2. Erect concrete enclosure around the tank To qualify the RWST it is recommended that a new tank be constructed. This modification is outlined in Table 7-2, along with an estimated cost.

7.2.3 Refueling Water Storage Tank Suction Piping With the exception of the piping to the SIS pumps the following suction piping from the RWST needs to be protected:

CRS-729-8"

-JN CRS-8004-2" -HP CRS-728-8"

-HP CRS-863-1"

-HP CRS-8005-1" -HP CRS-10375-6"-CM Tornado Resistance Design Review for 7-7 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 0

Protection of these lines is required to ensure tank integrity and to provide water to the charging pumps.

The evaluation requires modifications to the RWST suction piping at 10-4, 10-5, 10- 6, and 10- 7 wind speed probability occurrences.

Possible modifications to protect the RWST suction piping are:

1. Enclose the exposed piping with an enclosure building

2. Add a direct line to the charging pumps and shield a

exposed nozzles and piping To protect the RWST suction piping it is recommended that a steel missile barrier around MOV-883 be erected and a g) direct line to the charging pumps, downstream of CRS-360, added with manual isolation valves. This modification is outlined in Table 7-2, along with an estimated cost.

)

7.2.4 Electrical Power Supply to Charging System Components The power and control cables to the Charging System components are routed in exposed conduits along the control room roof and the exterior of the enclosure building, and in exposed conduits and trays along the north and west walls of the fuel building. In addition, the power source for the charging pump lube oil cooler fan motor is located in an area not protected from missile strikes at any of the postulated windspeeds. The evaluation determined that modifications are required to protect the electrical supply to the charging system components at 10-4, 10-5, 10-6, and 10-7 wind speed probability occurrences.

Possible Tornado Resistance Design Review for 7-8 k -

San Onofre Nuclear Generating Station Unit 1

'Report No. TR-85028-02, Revision 0

modifications to protect the electrical power supply to the charging system components are:

1. Erect steel missile barrier

2.

Install new raceways

3. Change power source to motor It is recommended that new raceways and cables be installed such that adequate missile protection is provided and that the power source to the charging pumps lube oil cooler fan motor be changed to a protected source. These modifications are outlined in Table 7-2, along with an estimated cost.

7.2.5 Seal Water Flow Instruments The seal water flow transmitters are located at the north end of the CCW valve and piping penetration area (valve alley). This area is protected on four sides with reinforced concrete of sufficient thickness to stop wind generated missiles at 10-4, 10- 5, 10- 6 and 10- 7 probable wind speed occurrences. However, no protection is provided for vertical missiles.

The evaluation requires that modifications to the seal water flow instruments be made for 10- 4, 10-5, 10- 6, and 0

Tornado Resistance Design Review for 7-9 San Onofre Nuclear Generating Station Unit 1 IIIlIIl Report No.

TR-85028-02, Revision 0

10-7 wind speed probability occurrences.

Possible modifications to protect the seal water flow transmitters are:

1. Erect Steel barrier

2.

Relocate transmitters To protect the seal water flow transmitters it is recommended that the transmitters be relocated.

This modification is outlined in Table 7-2, along with an estimated cost.

7.2.6 Neutron Monitors t*

The neutron monitors are located inside containment and are considered to be protected [2].

In addition, the electrical containment penetration modules can withstand a missile strike at speeds up to and including that associated with 10-7 wind speed probability occurences without degrading containment integrity. However, the electrical cabling to the neutron monitors are routed through exposed raceways in the containment penetration area.

The evaluation requires that modification to the electrical cabling to the penetration modules be made for 10-4, 10-5 10-6, and 10-7 wind speed probability occurrences.

Possible modifications to protect these cables are:

1.

Erect steel barrier

2.

Install new raceways Tornado Resistance Design Review for 7-10 San Onofre Nuclear Generating Station Unit 1 m mmu Report No. TR-85028-02, Revision 0

To provide this protection it is recommended that new raceways and cables be installed.

This modification is outlined in Table 7-2, along with an estimated cost.

7.3 PRIMARY PRESSURE CONTROL To ensure pressure control is maintained in the primary side, those components noted in the shutdown flowpath, Figure 7-1, are required to function.

To accomplish this, upgrades in the following areas are required:

1.

Backup nitrogen and electrical supply to Pressurizer PORV and Block Valves

2.

Pressurizer Heaters and Instrumentation i

3.

RCS Temperature and Instrumentation 7.3.1 Backup nitrogen and Electrical Supply to Pressurizer PORV and Block Valves The backup N2 cylinders for the pressurizer PORV and Block valves are located on the northwest side of the sphere enclosure building along a concrete radiation shield.

The nitrogen tubing from these cylinders runs along the sphere enclosure building and into the west containment penetration doghouse at valve alley.

The electrical raceways associated with the pressurizer PORV and block valves are routed through exposed raceways to the containment penetration area.

The penetration modules can withstand missile strikes for 10-7 wind speed probability occurrences without degrading containment integrity.

However, the electrical cabling to the penetration modules will fail due to missile strikes at any of the postulated wind speeds.

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The evaluation requires that modifications to the N2 cylinders and tubing, and the electrical raceways associated with the pressurizer PORV and block valves be made for 10- 4, 10- 5, 10- 6, and 10-7 wind speed probability occurrences.

Possible modifications are:

1.

Install steel barrier over regulators and guard pipe over tubing

2.

Install additional N2 cylinders with check valves in tubing

3.

Steel barrier over exposed raceways

4.

Install new raceways To provide this protection to the nitrogen backups and electrical supply it is recommended two additional N2 cylinders be placed inside the sphere enclosure building and check valves be placed in the tubing to the existing N2 bottles.

These modifications are outlined in Table 7-3, along with an estimated cost.

7.3.2 Pressurizer Heaters, Level and Pressure Transmitters, and Primary System Temperature Elements The heaters and the instruments are located inside containment and are considered to be protected [2].

In addition, the electrical containment penetration modules can withstand missile strike for 10- 7 wind speed probability occurrences without degrading containment integrity. However, the electrical cabling to the heaters and to the instruments are routed through exposed raceways in the containment penetration area.

The evaluation requires that modifications to the electrical cabling to the penetration modules be made for Tornado Resistance Design Review for 7-12 San Onofre Nuclear Generating Station Unit 1 HuIlluiuinumniii Report No.

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10-4, 10- 5, 10-6, and 10-7 wind speed probability occurrences.

Possible modifications to protect the heater and instrument cables are:

1. Erect steel barrier over raceways

2.

Install new raceways To provide this protection it is recommended that new raceways be installed to protect the essential cables.

This modification is outlined in Table 7-3, along with an estimated cost.

7.4 DECAY HEAT REMOVAL To remove the primary side decay heat, those components noted in the shutdown flow path outlined on Figure 7-2 are required to function and/or maintain their pressure boundary. To accomplish this effort upgrades are required in the following areas:

0

1. Backup Nitrogen and Electrical Supply to the Main Steam Atmospheric Dump Valves

2. AFW System Major Components

)

3.

AFW System Electrical Cables

4.

Steam Generator Level Transmitters

5.

Steam Generator Blowdown Piping 0

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7.4.1 Backup Nitrogen and Electrical Supply to the Main Steam Atmospheric Dump Valves The solenoid pilot valves controlling the backup nitrogen for the atmospheric dump valves are located at each valve. These valves and the ten main steam safety.relief valves are partially enclosed within an existing missile shield.

The N2 cylinders for the dump valves are located on the north turbine deck extension along the west wall of the control room. The nitrogen tubing for these cylinders is routed along the west wall of the control room to the east dump valves. The tubing to the west dump valves is presently routed beneath the sphere enclosure building equipment hatch opening.

This portion of the tubing is protected from missiles.

However, the lengths of tubing from the control building wall and the fuel building wall to the sphere enclosure building are exposed to missile strikes.

The electrical raceways to the main steam dump valves are routed through cable trays and conduits which are exposed near the dump valves. The raceways fail due to missile strikes at any of the postulated wind speeds.

The evaluation requires that modifications to the solenoid pilot valves, pressure regulators and tubing, and the electrical raceways be made for 10-4, 10-5, 10-6, and 10-7 Tornado Resistance Design Review for 7-14 E

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wind speed probability occurrences. Possible modifications to protect these components are:

1. Erect steel barrier over solenoid valves

2.

Install steel barrier over regulators

3.

Install guard pipe over tubing

4.

Reroute tubing

5.

Steel barrier over raceways

6. Reroute raceways To provide this protection it is recommended that steel barriers be placed over the solenoid valves and the pressure regulating valves on the N2 cylinders, and reroute the exposed tubing behind the N2 cylinders.

To protect the electrical raceways it is recommended that the raceways be rerouted such that adequate missile protection is provided. These modifications are outlined in Table 7-4, along with an estimated cost.

7.4.2 AFW System Major Components The AFW System major components include the AFW storage tank, suction piping, equipment in the AFW pump area, and pump discharge piping. The AFW tank has been shown to be capable of surviving all tornado events. The remaining components are discussed below.

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7.4.2.1 AFW Suction Piping The following piping and instrumentation attached to the storage tank is exposed to wind-generated missiles from the tank discharge to the pipe trench:

AFW-8111-6"-JN AFW-8110-6"-JN AFW-8119-4"-JN AFW-8115-11/2"-JN AFW-8114-11/2"-JN AFW-8113-11/2"-JN AFW-8116-4"-JN NO LINE NO. (AFW-466)

Level Transmitters 6A, and B Protection of these lines is required to ensure tank integrity, and to supply feedwater to the AFW pumps.

The evaluation requires that modifications to protect the AFW storage tank suction piping be made for 10-4, 10-5, 10-6, and 10-7 wind speed probability occurrences.

Possible modifications to protect this piping are:

1. Erect concrete enclosure

2.

Erect steel enclosure To provide this protection it is recommended that a reinforced concrete enclosure be erected around the exposed piping. This modifications is outlined in Table 7-4, along with an estimated cost.

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7.4.2.2 AFW Pump Area The AFW pumps and discharge piping are located in the west side of the turbine buiding at Elevation 14 feet..Missile shields are presently in place to protect the pump-area from missiles approaching vertically and from the North side. However, as discussed in Section 7.1.1 no protection is provided on the west and south sides for wind-generated missiles (no credit for protection can be taken for masonry 0

block walls).

The evaluation requires that modifications to protect the auxiliary feedwater pump area be made for 10-4, 10-5, 10-6,

• 5 and 10-7 wind speed probability occurrences.

Possible modifications to protect the AFW pump area are:

1. Erect removable steel barrier

)

2. Erect a concrete wall As outlined in Section 7.1.1 to provide this protection it is recommended that the existing masonry wall be removed and a reinforced concrete wall erected from the 480V switchgear room to the south end of the turbine building.

This modification is outlined in Table 7-4, along with an estimated cost.

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7.4.2.3 Discharge Piping With the incorporation of the reinforced concrete wall recommended in Section 7.4.2.2, and taking credit for the turbine building deck, the remainder of the AFW discharge piping is shielded from missile strikes. However,-the normal flow control valves fail open and the bypass lines fail closed due to the loss of the compressed air system.

To adequately regulate AFW flow to the steam generators the normal flow path should be isolated and a bypass established through CV-142, 143, and 144. To accomplish this backup Nitrogen should be added to FCV-456, 457, and 458, and to CV-142, 143 and 144.

This modification is outlined in Table 7-4, along with an estimated cost.

7.4.3 AFW System Electrical Cables The AFW system power and control cables are routed from the 4KV switchgear room to the AFW motor driven pump, MOV-1202 and MOV-1204 (AFW pump discharge) in exposed raceways along the ventilation equipment building, 480 volt switchgear room and west side turbine building.

The evaluation requires that modifications to protect the auxiliary feedwater system cables be made for 10-4, 10-5, 10-6, and 10- 7 wind speed probability occurrences.

Tornado Resistance Design Review for 7-18 San Onofre Nuclear Generating Station Unit 1 HNIMIiiimulumum Report No.

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Possible modifications to protect the electrical cabling are:

1.

Install new raceways

2.

Cover with missile barrier To provide this protection it is recommended that new conduits be routed from the 4KV switchgear room to the AFW pump motor, to MOV 1202, and to MOV 1204. This modification is outlined in Table 7-4, along with an estimated cost.

7.4.4 Steam Generator Level Transmitters The steam generator level transmitters are located inside containment and are considered to be be protected [2].

In addition, the electrical containment penetration modules can withstand a missile strike at speeds up to and including that associated with 10-7 wind speed probability occurrences without degrading containment integrity.

However, the electrical cabling from the level transmitters are routed through exposed raceways in the containment penetration area.

The evaluation requires that modifications to protect the steam generator level transmitters be made for 10- 4, 10-5, 10-6, and 10- 7 wind speed probability occurrences.

Possible modifications to protect the electrical cabling are:

1. Reroute raceways

2. Erect a steel missile barrier Tornado Resistance Design Review for 7-19 San Onofre Nuclear Generating Station Unit 1 II Report No.

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To provide this protection it is recommended that new raceways and cables be installed such that adequate missile protection is provided. This modification is outi-ined in Table 7-4, along with an estimated cost.

7.4.5 Steam Generator Blowdown Piping The Steam Generator Blowdown Piping is exposed to wind generated missiles near valve alley.

Protection of these lines is required to ensure Steam Generator pressure boundary integrity and avoid an uncontrolled secondary system blowdown.

The evaluation requires that modifications to protect the blowdown piping be made for 10- 4,.10-5, 10-6 and 10- 7 wind speed probability occurrences. Possible modifications to protect this piping are:

1.

Install manual isolation valves

2. Erect a concrete barrier

3. Erect a steel barrier To provide this protection it is recommended that manual isolation valves be installed on the blowdown piping in the doghouse. This modification is outlined in Table 7-4, along with an estimated cost.

Tornado Resistance Design Review for 7-20 San Onofre Nuclear Generating Station Unit 1 IIIIIIIIIIiiiiiililuIiiiii Report No.

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0 7.5 Onsite Emergency Power System

• k To provide power to the components shown on the shutdown flowpaths, Figures 7-1 and 7-2, at least one train of the onsite emergency power system must be available. To ensure that one train of the onsite emergency power system is available upgrades are required in the

• )

following areas:

1. Station Service Transformer Number 1

2.

Vital Bus Number 5 7.5.1 Station Service Transformer Number 1 Station Service Transformer No. 1 is located outside the Sphere Enclosure Building near the Diesel Generator Building. The transformer and associated cables are an exposed link in the mostly protected train number 1 emergency power supply. The transformer is required to provide low voltage distribution power to the AFW pump and all of the active flow control devices in the shutdown flowpath.

The evaluation requires that modifications to protect the station service transformer be made for 10-4, 10-5, 10-6, and 10-7 wind speed probability occurrences.

Possible modifications to protect the transformer and cables are:

1. Erect missile barrier around the tranformer and cables

2.

Install new dedicated tranformers To provide this protection it is recommended that a reinforced concrete missile barrier be erected around the existing transformer. This modification is outlined in Table 7-4, along with an estimated cost.

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7.5.2 Vital Bus Number 5 The inverter for Vital Bus No. 5 is located in the 480V switchgear room which is constructed of masonry block walls and provides no protection for wind-generated missiles for 10-4, 10-5, 10- 6, or 10- 7 wind speed probability occurrences. The power cables to and from the inverter are routed through exposed conduits along the enclosure building, the ventilation equipment building, and the fuel building.

The evaluation requires that modifications to protect the protect the vital bus No. 5 be made for 10-4, 10-5, 10- 6, and 10- 7 wind speed probability occurrences.

Possible modifications to protect the electrical cabling are:

1. Reroute raceways

2. Relocate inverter To provide this protection it is recommended that new raceways and cables be installed. This modification is based on the assumption of the west turbine building wall being replaced and is outlined in Table 7-4, along with an estimated cost.

Tornado Resistance Design Review for 7-22 San Onofre Nuclear Generating Station Unit 1 INIUNINUNIUNIMIii Report No. TR-85028-02, Revision 0

0 TABLE 7-1 MODIFICATIONS REQUIRED FOR STRUCTURES

$ COST x 1000 10-4 10-5 10-6 10-7 I. TURBINE BUILDING WEST WALL

a. CONCRETE WALL 640 640 659 659 II. EAST CONTROL ROOM WALL 4

a. SHOTCRETE LAYER 1058 1058 1162 1162 III. CONTROL ROOM ROOF

a.

CONCRETE ROOF NA NA NA 1873 IV. DC SWITCHGEAR and BATTERY ROOM No. 1 0

a. WEST CONCRETE WALL NA 80 84 84

b. EAST CONCRETE WALL 68 68 71 71 0

Tornado Resistance Design Review for 7-23 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0 9

TABLE 7-2 (b

MODIFICATIONS REQUIRED FOR REACTIVITY AND PRIMARY INVENTORY CONTROL

$ COST x 1000 10-4 10-5 10-6 10-7 I. NITROGEN BACKUP TO FCV-1112 Will be installed as part of the Appendix R plant modifications 0

II. REFUELING WATER STORAGE TANK

a. NEW TANK NA NA 14072 18835 III. REFUELING WATER STORAGE TANK SUCTION PIPING

a.

NEW LINE TO CHARGING PUMPS 193 193 193 193

b. STEEL BARRIER AROUND MOV-115 115 132 160 883 IV. ELECTRICAL POWER SUPPLY TO THE CHARGING SYSTEM COMPONENTS

a.

REROUTE RACEWAYS AND CABLES, AND CHANGE POWER SUPPLY 307 307 307 307 V.

SEAL WATER FLOW INSTRUMENTS

a.

RELOCATE TRANSMITTERS 86 86 86 86 40 VI.

NEUTRON MONITORS

a. REROUTE RACEWAYS AND CABLES 200 200 200 200 Tornado Resistance Design Review for 7-24 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 7-3 MODIFICATIONS REQUIRED FOR PRIMARY PRESSURE CONTROL 0

$ COST x 1000 10-4 10-5 10-6 10- 7 I. BACKUP NITROGEN AND ELECTRICAL TO THE PRESSURIZER PORV AND BLOCK VALVES

a. ADDITIONAL CYLINDERS 110 110 110 110

b. REROUTE RACEWAYS AND 53 53 53 53 CABLES II. PRESSURIZER HEATERS, LEVEL AND PRESSURE TRANSMITTERS, AND 0

PRIMARY SYSTEM TEMPERATURE ELEMENTS

a. REROUTE RACEWAYS AND CABLES 110 110 110 110 0

0 Tornado Resistance Design Review for 7-25 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

0 TABLE 7-4 MODIFICATIONS REQUIRED FOR DECAY HEAT REMOVAL e

$ COST x 1000 10-4 10-5 10-6 10-7 I. MAIN STEAM DUMP VALVES

a. STEEL BARRIERS OVER SOLENOID VALVES 161 161 183 230

b. REROUTE RACEWAYS AND CABLES 40 40 40 40 II. BACKUP NITROGEN AND ELECTRICAL SUPPLY TO THE MAIN STEAM ATMOSPHERIC DUMP VALVES

a. STEEL SHIELD OVER PRESSURE REGULATING VALVES AND RELOCATE NITROGEN TUBING 140 140 148 164 III. AFW SUCTION PIPING

a. CONCRETE BARRIER 649 649 779 1033 IV. AFW PUMP AREA

a. CONCRETE WALL See Item I.a. in Table 7-1 Tornado Resistance Design Review for 7-26 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

TABLE 7-4 MODIFICATIONS REQUIRED FOR DECAY HEAT REMOVAL (continued)

$ COST x 1000 10-4 10-5 10-6 10-7 V. DISCHARGE PIPING

a. NITROGEN BACKUP TO 185 185 185 185 FLOW CONTROL VALVES VI.

AFW SYSTEM CABLES

a. REROUTE RACEWAYS AND CABLES 165 165 165 165 VII. STEAM GENERATOR LEVEL TRANSMITTERS

a. REROUTE RACEWAYS AND CABLES 66 66 66 66 VIII. STEAM GENERATOR BLOWDOWN PIPING

a. INSTALL MANUAL ISOLATION VALVES 46 46 46 46 Tornado Resistance Design Review for 7-27 San Onofre Nuclear Generating Station Unit 1 Report No.

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TABLE 7-5 MODIFICATIONS REQUIRED FOR THE ONSITE EMERGENCY POWER SYSTEM

$ COST x 1000 10-4 10-5 10-6 10-7 I. STATION SERVICE TRANSFORMER NO.

1

)

a. CONCRETE BARRIER 185 185 212 265 II. VITAL BUS NO. 5

a. REROUTE RACEWAYS AND CABLES 55 55 55 55 Tornado Resistance Design Review for 7-28 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0

FIGURE 7-1 REACTIVITY, PRIMARY INVENTORY AND PRESSURE CONTROL FLUMPATH

.s 10 XFMR 3 10-400V SWca 3 10" MCC 3106 BATTERY $1 PO D

G.S PRO 4K W

RIC 10 -4 10- 4 10- 4 10-4 10- 4 10 o

1 0 10-4 10-PRO 10-PRO 10 o-4 o-4 40SG7

,.I--7 1

PR o-4 0

10-4 10PPRR-ORO 1

PRO PRO F - PRO PRO-PRO PRO 10- 4 0

"2-App-R XF R12 o-4F4-.

Z 7

to-to-PRO PRO 10o-4 10- 4 o-LL 1poL10-4-l 10-PR 10-4 01 C-42 G-88 SV41 PRO PRO PRO DCV.115 C-15-1115115 FeV-1112 PR R RO PRO PRO PRO PRO 10 P2R HTR B&D PER HTR A6C 10- 4 10- 4 PR 10- 4 PR 04RPBRPC RCP A CV-304 PR R

PRO PRO PRO PRO r

PRO PRO SV-532 A C52 PRr1 REACTOR PCV-1115 8 PCV-lill5C PCV-111$ A Cv-530 CV-531 RV-533 RV-532PR PO PO POPO PO PRO 10-PRO 10-P RO PRO PRO PRO RV-2004 CV-546 CV55PRO PRO PRO 10- 4 PO 1

RCDT C-32 PRO PRO Tornado Resistance Design Review for 7-29 San Onofre Nuclear Generating Station Unit 1 L =

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FIGURE 7-2 DECAY HEAT REMOVAL FLOMPATH 10 10o-PRO 10-4 1**

40V SM0GR IC 10-4 10-10-4 PRO to-4 C~ -

Im

]

1-4 1VSG3 0

MC 10 PC-4 A ~~1 10O 10 10 10 10 - 4 S L o

10-o 10I rTERY

@IG-lA 10 10 10 t-2A T.1-I1102

• • A 0Y2 10 sum 10 10 10 10 4 10 4 1 -75210 1C-3 10 4

10Q-5 -

0 1

Y 10-o' 10 0su-4t m m 11 8 2 S1V 1440 fV_ I2 104 104 mm4 1-4 A0 1 -

0 5 1 G-101 MDV120 10-10CV45 D2A 10 -4 10 toL 10 1w M

-0 FCr5 V-77 V86N G-10~G-CV-322 10-1004 1

010 1

1-06 C-3011 10-4 10e Q 1

0 1

0 1.e V

1 4 4

I Q

21 107SHLD 10 01 010-4 10 SG C

.3 S

.1 BATT05

.210VTA U 4 o-I CVI

/P-2 P-D 104 Pto PAt o

10-10-10 10 0-4P--3 0

1-7 10 10-H 1

10O 0,

D. G. g2 PH 10- S GR2 10-to- 0 10-4 CVD SM M 0 MC 2

1 PaD Pa0 PA P0-4 100 10 44 1010 1

Tornado Resistance Design Review for 7-30 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Re vi sion 0

8.0 DESIGN BASIS TORNADO

• h This section of the report provides a cost-safety benefit and a risk assessment for the modifications that are required to assure safe shutdown capability during the 10-4, 10-5, 10- 6, and 10-7 wind speed probability occurrences. Those components required to function and or maintain their pressure boundary are shown in Figures 7-1 and 7-2.

Using the system scenario outlined in Section 3 and the recommended modifications discussed in Section 7, these assessments were performed to determine the design basis tornado.

The total cost of plant modifications for each of the postulated wind speed probability occurrences are shown below and on Figure 8-1.

PROBABILITY COST 10-4 4,630,724 10-5 4,710,471 10-6 19,117,498 10-7 26,150,204 As shown above, the cost for modifications remains relatively stable for 10-4 through 10-5 probability events. However, from 10-5 through 10- 6 an increase of approximately 400% occurs, bringing the total cost of modifications for 10-6 probability events to over 19 million dollars.

This large increase in costs is due primarily to the rebuilding of the RWST that is required for 10-6 events. Although the tank is rebuilt, its wall thickness increases only 1/16 of an inch.

This indicates that the current tank may survive a 10-6 tornado event.

It is unlikely that the three conditions which resulted in the failure of the RWST would occur simultaneously (missile pick-up, ejection and impact at maximum velocity, and worst possible strike geometry).

In Tornado Resistance Design Review for 8-1 San Onofre Nuclear Generating Station Unit 1 I

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0 addition, this large increase in costs for only a moderate decrease in probability indicates that benefits are no longer increasing at a rate consistent with dollars spent. The cost-safety benefit assessment indicates that the SONGS 1 Design Basis Tornado should correspond to the 10-5 wind speed probability occurrence. The risk associated with larger tornado loadings is acceptable based on their extremely low probability of occurrence.

Figure 8-1 30 -

Cost-vs-Risk Assessment (26.2) 25 20 (19.1) 6

~15 0

10 5 -

(4.6)

(4.7) oer6 10-10-5 10-6 10-7 WIND SPEED PROBABILITY OCCURRENCE 0

Tornado Resistance Design Review for 8-2 San Onofre Nuclear Generating Station Unit 1 Report No.

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9.0 REFERENCES

1.

"SEP Topic 111-2, Wind and Tornado Loadings San Onofre Nuclear Generating Station, Unit 1", Docket No. 50-206, LS05-82-02-006 USNRC, February 1, 1983.

2.

"SEP Topic III-4.A, Tornado Missiles San Onofre Nuclear Generating Station, Unit 1", Docket No. 50-206, LS05-82-11-065 USNRC, November

4) 19, 1982.

3.

SCE Letter from M.O. Medford to W.A. Paulson dated September 17, 1984 regarding SEP Topics 111-2 and III-4.A.

4.

"Tornado Resistance Design Review Criteria San Onofre Nuclear Generating Station Unit 1", Document No. DC-85028-01, Revision 0, Cygna Energy Services, October 1985.

5.

Reference deleted.

6.

Reference deleted.

7.

SCE Letter from M.0. Medford to J.A. Swolinski dated October 4, 1985,, regarding Fire Protection Program Review.

8.

Reference deleted.

9.

Reference deleted.

10.

"Fire Protection Program Review", letter No. SCE - M.O. Medford to g*

J.A. Zwolinski, May 21, 1985.

11.

"SEP TOPIC XV-20 Radiological Consequences of Fuel Damaging Accident," Docket 50-206, USNRC, January 17, 1980.

Tornado Resistance Design Review for 9-1 San Onofre Nuclear Generating Station Unit 1 Report No. TR-85028-02, Revision 0