ML13331B081

Amend Application 155 Consisting of Proposed Change 194, Modifying Positive Barrier Isolation Requirements Between Feedwater Condensate Sys & RCS Due to Power Supply Mods to Recirculation Sys Valve

ML13331B081
Person / Time
Site:	San Onofre
Issue date:	11/07/1988
From:	Baskin K Southern California Edison Co
To:
Shared Package
ML13331B082	List: ML13331B081 ML13331B083 ML20206A210
References
NUDOCS 8811150021
Download: ML13331B081 (18)

Text

BEFORE THE UNITED STATES NUCLEAR REGULATORY COMMISSION Application of SOUTHERN CALIFORNIA EDISON

)

COMPANY and SAN DIEGO GAS & ELECTRIC COMPANY )

for a Class 104(b) License to Acquire,

)

DOCKET NO. 50-206 Possess, and Use a Utilization Facility as

)

Part of Unit No. 1 of the San Onofre Nuclear )

Amendment No. 155 Generating Station

)

SOUTHERN CALIFORNIA EDISON COMPANY and SAN DIEGO GAS & ELECTRIC COMPANY, pursuant to 10 CFR 50.90, hereby submit Amendment Application No. 155.

This amendment consists of Proposed Change No. 194 to Provisional Operating License No. DPR-13. Proposed Change No. 194 modifies the Technical Specifications incorporated in Provisional Operating License No. DPR-13 as Appendix A.

Proposed Change No. 194 is a request to revise Appendix A Technical Specifications to modify the positive barrier isolation requirements between the feedwater condensate system and the reactor coolant system due to power supply modifications to a recirculation valve.

In the event of a conflict, the information in Amendment Application No. 155 supersedes the information previously submitted.

PDR iD0CK 05000206

-2 Based on the significant hazards analysis provided in the Description of Proposed Change and Significant Hazards Analysis of Proposed Change No. 194, it is concluded that (1) the proposed change does not involve a significant hazards consideration as defined in 10 CFR 50.92, and (2) there is reasonable assurance that the health and safety of the public will not be endangered by the proposed change.

Pursuant to 10 CFR 170.12, the fee of $150 is herewith remitted.

0 0

-3 Subscribed on this _

day of A4-tL-,

1988.

Respectfully submitted, SOUTHERN CALIFORNIA EDISON COMPANY By:

Kenneth P. Baskin Vice President Subscribed and sworn to before me th's

-7 day of

,__/____O OFFICIAL SEAL

_C.

SALLY SEBO Notary Public in a for the County of Notary Public-Calfornia Los Angeles, State of California MyComm.Exp.Apr.20,1990 Charles R. Kocher James A. Beoletto Attorneys for Southern California Edison Company By:

UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the Matter of SOUTHERN

)

CALIFORNIA EDISON COMPANY

)

and SAN DIEGO GAS & ELECTRIC

)

Docket No. 50-206 COMPANY (San Onofre Nuclear

)

Generating Station Unit No. I

)

CERTIFICATE OF SERVICE I hereby certify that a copy of Amendment Application No. 155 was served on the following by deposit in the United States Mail, postage prepaid, on the 7th day of November

, 1988.

Benjamin H. Vogler, Esq.

Staff Counsel U.S. Nuclear Regulatory Commission Washington, D.C. 20555 David R. Pigott, Esq.

Samuel B. Casey, Esq.

Orrick, Herrington & Sutcliffe 600 Montgomery Street San Francisco, California 94111 L. G. Hinkleman Bechtel Power Corporation P.O. Box 60860, Terminal Annex Los Angeles, California 90060 Michael L. Mellor, Esq.

Thelen, Marrin, Johnson & Bridges Two Embarcadero Center San Francisco, California 94111 Huey Johnson Secretary for Resources State of California 1416 Ninth Street Sacramento, California 95814 Janice E. Kerr, General Counsel California Public Utilities Commission 5066 State Building San Francisco, California 94102

-2 C. J. Craig Manager U. S. Nuclear Projects I ESSD Westinghouse Electric Corporation Post Office Box 355 Pittsburgh, Pennsylvania 15230 A. I. Gaede 23222 Cheswald Drive Laguna Niguel, California 92677 Frederick E. John, Executive Director California Public Utilities Commission 5050 State Building San Francisco, California 94102 Docketing and Service Section Office of the Secretary U.S. Nuclear Regulatory Commission Washington, D.C. 20555

DESCRIPTION AND SIGNIFICANT HAZARDS CONSIDERATION ANALYSIS OF PROPOSED CHANGE NO. 194 TO THE TECHNICAL SPECIFICATIONS PROVISIONAL OPERATING LICENSE NO. DPR-13 This is a request to revise Section 3.3.2, "Shutdown Status" and the Basis for Section 3.7, "Auxiliary Electrical Supply" of Appendix A Technical Specifications for the San Onofre Nuclear Generating Station, Unit 1 (SONGS 1).

DESCRIPTION OF CHANGES In order to eliminate a single failure susceptibility in the recirculation system, the power supply for recirculation valve MOV-358 will be changed to be included on the Uninterruptible Power Supply (UPS) for MOV-850C. The design modifications to accommodate this change in power supply require revision to Technical Specification 3.3.2 which defines the "positive barrier" requirements between the feedwater condensate system and the piping connections to the reactor coolant system. Specification 3.3.2.A(l) will be revised to eliminate the specific requirement for MOV-850C, and replace the words "safety switches" with "supply breakers." In addition the basis for Technical Specification 3.7 will be revised to reflect the new service requirement for the UPS.

EXISTING TECHNICAL SPECIFICATION See Attachment 1 PROPOSED TECHNICAL SPECIFICATION See Attachment 2 SIGNIFICANT HAZARDS CONSIDERATION ANALYSIS As required by 10 CFR 50.91(a)(1), this analysis is provided to demonstrate that a proposed license amendment to implement technical specifications associated with modifying the positive barrier requirements for motor operated valves at SONGS 1 represents a no significant hazards consideration. In accordance with the three factor test of 10 CFR 50.92(c), implementation of the proposed amendment was analyzed using the following standards and found not to:

1) involve a significant increase in the probability or consequences for an accident previously evaluated; or 2) create the possibility of a new or different kind of accident from any accident previously evaluated; or

3) involve a significant reduction in a margin of safety.

Discussion By letters dated April 5, 1988 and June 21, 1988, SCE provided to the NRC descriptions of modifications associated with previously identified recirculation system single failures. SCE committed to implement the following design modifications in the recirculation system during the Cycle 10 refueling outage:

-2

1. Change the power supply for recirculation valve MOV-358 to be included on the Uninterruptible Power Supply (UPS) for safety injection isolation valve MOV-850C, and

2. Provide a new supply breaker for MOV-850C downstream of the inverter output breaker and transfer switch to support maintenance activities and testing of the valves.

In review of the technical specifications to evaluate any impact from these modifications, it was determined that the positive barrier isolation requirements between the feedwater and RCS defined by Specification 3.3.2 would require revision. MOV-850C serves as one of the two isolation barriers on a section of piping between the feedwater system and the RCS, and thus is subject to the provisions of Specification 3.3.2. In accordance with these provisions, the inverter output breaker feeding MOV-850C must be open whenever fuel assemblies are in the vessel and the RCS pressure is less than 500 psig.

With the addition of MOV-358 to the same inverter, opening of the inverter output breaker would remove power to MOV-358 as well as MOV-850C. This configuration is not necessary nor desirable because MOV-358 is not subject to the positive barrier requirements of Specification 3.3.2. For this reason, individual supply breakers will be provided for both MOV-850C and MOV-358 such that control power can be removed from MOV-850C without impacting MOV-358.

The existing and proposed power supply configurations for MOV-358 and MOV-850C are illustrated in Figure 1.

For clarification of the new service requirements for the UPS, the Basis for Technical Specification 3.7 will be revised to reference that correct operation of the recirculation system is assured by the emergency power supply for MOV-358, namely, the UPS.

Analysis Conformance of the proposed amendments to the standards for a determination of no significant hazard as defined in 10 CFR 50.92 (three factor test) is shown in the following:

1. Will operation of the facility in accordance with this proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

RESPONSE: NO The Technical Specification changes associated with the MOV-358 power supply design changes will not impact the manner in which positive barriers between the feedwater system and the RCS are established or maintained. Further, the addition of MOV-358 onto the UPS for MOV-850C has been evaluated as part of the single failure analysis documented in the June 21, 1988 letter to the NRC.

The results of this evaluation concluded the UPS has sufficient power to supply the most limiting load profile for operation of MOV-850C and MOV-358 as follows:

Safety Injection on Demand Loss of Offsite Power 11-Second Delay to Start Emergency Diesels

-3 Train 2 Diesel Fails to Start MOV-850C Opens (to allow injection flow to loop C)

MOV-358 Opens at 30 Minutes (to permit recirculation)

MOV-850C Closes SCE credits operator action to restore power to 480V Bus No. 3, thus no longer requiring the UPS for operation of MOV-358, in the event that recirculation is initiated beyond 30 minutes. With MOV-358 powered by the UPS, electrical independence will be provided from the two redundant recirculation valves MOV-356 (Train A) and MOV-357 (Train B), thereby preventing a single failure from disabling the power supply for more than one valve.

Based on the above, operation of the facility in accordance with this proposed change will not impact the probability or consequences of an accident previously evaluated.

2. Will operation of the facility in accordance with this proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?

RESPONSE: NO The design changes associated with this proposed change have been reviewed in consideration to previously evaluated accidents. This proposed change does not impact the function of the associated equipment, only the power supply for the equipment. Therefore, the previous accident analyses which are based on the function of the equipment are not impacted. As part of the single failure analysis, the ability of the UPS to supply power to both MOV-850C and MOV-358 was evaluated under the most limiting sequence of events and determined to be acceptable. Therefore, it is concluded that operation of the facility in accordance with the proposed change will not create the possibility of a new or different kind of accident from any accident previously evaluated.

3. Will operation of the facility in accordance with this proposed change involve a significant reduction in a margin of safety?

RESPONSE: NO This proposed change will not impact the manner in which positive barriers between the feedwater system and the RCS are established or maintained. The design changes associated with this proposed change will include supply power to MOV-358 through the MOV-850C UPS. The UPS has been analyzed and determined to have adequate capacity to supply the most limiting sequence of events for these two valves.

In addition, thermal overload protection has been evaluated with consideration to the revised circuit configuration and breaker sizes to ensure compliance with the requirements of Regulatory Guide 1.106. The revised circuit configuration maintains the bypass of the existing thermal overload relays of the motor starters.

Based on these considerations, it is concluded that operation of the facility in accordance with this proposed change will not involve a significant reduction in a margin of safety.

-4 SAFETY AND SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION Based on the above analysis, it is concluded that:

(1) Proposed Change No. 194 does not involve a significant hazards consideration as defined by 10 CFR 50.92; and (2) there is reasonable assurance that the health and safety of the public will not be endangered by the proposed change. -

Existing Specifications -

Proposed Specifications MJT:0160n

FIGURE EXISTING AND PROPOSED POWER SUPPLY CONFIGURATIONS FOR UPS MCC-3 Existing Configuration B #ry chat er HE l3citcr y Inverter

) oupuf Bre4ker

) crcwif 'BrcQker Starfer Starter O85 o

OOY 0

ov MY Mce 1c Proposed Configuration ChQrler Inverfer attcry

) outpu0f l6rker

) e ar

) Circ4if Rreqer M OY-85 0 C M

.35

ATTACHMENT 1 EXISTING TECHNICAL SPECIFICATIONS 3.3.2 SHUTDOWN STATUS APPLICABILITY:

Applies to piping connections between the feedwater condensate system and the reactor coolant system.

OBJECTIVE:

To preclude injection of feedwater condensate into the reactor coolant system when the reactor is shut down and to preclude the potential for overpressurization when water solid.

SPECIFICATION:

A. When reactor fuel assemblies are in the vessel and the reactor coolant pressure is less than 500 psig, two "positive barriers" shall be provided between the feedwater condensate system and the piping connections to the reactor coolant system. Additionally, when the reactor coolant system is water solid at less than 103 500 psig, two positive barriers shall be provided between 5/23/88 the safety injection system and piping connections to the reactor coolant system. A "positive barrier" is defined as follows:

(1) Motor Operated Valves When closed and tagged with safety switches open, except that power may be restored during no-flow tests of the safety injection system (Specification No. 4.2).

For MOV 850C, the three (3) pole double 34 throw switch must be connected to the inverter with 4/1/77 the inverter output breaker open.

(2) Pneumatic/Hydraulic Operated Valves When closed and the condition tagged with the respective hydraulic block valve closed except that they may be opened during no-flow tests of the safety injection system (Specification No. 4.2).

(3) Manually Operated Valves When closed and condition tagged.

103 (4) Feedwater Pump (Overpressurization Protection Only) 5/23/88 When shutdown with the breaker in the racked out condition.

BASIS:

Under normal conditions, system operational interlocks assure that injection of feedwater condensation to the reactor by the safety injection system cannot occur.(1)

These interlocks include:

SAN ONOFRE -

UNIT 1 3-33 Revised:

6/22/88

1.

Actuation of the safety injection relay which de energizes the condensate and heater drain pumps and closes the flow path for condensate, thereby preventing injection of feedwater into the coolant system.

2. Interlocks between the condensate isolation valves at the feedwater pump suction and the safety injection header isolation valves at the pump discharge which prevent the opening of the one valve unless the other is closed.

Below 500 psig the Safety Injection System may be removed from service. Below 400 psig the feedwater system may be removed from service.

During these low pressure shutdown reactor coolant system conditions, the interlocks may be overridden for maintenance and/or to prevent intrusion of feedwater condensate or safety injection water into the 103 reactor coolant system. Injection of feedwater has the 5/23/88 potential to dilute the system and create a potential for a reactivity excursion. Injection of either safety injection water or feedwater, especially during water solid operations, creates the potential for pressurizing above limits established by 10 CFR 50 Appendix G and as reflected in Technical Specification 3.1.3.

The "two positive barriers" required by this specification provide protection of the Reactor Coolant System against boron dilution and overpressurization when in the low pressure and low temperature conditions. Two positive barriers are provided in each potential path between the Feedwater Condensate System, Safety Injection System and the RCS.

During period of no-flow testing, an exception is provided on two of the positive barriers to allow the components involved in the test to perform their test functions while the remaining positive barriers (nos. 3 and 4) remain in effect.

Tagged, as used above, means tagged in accordance with current Southern California Edison Company procedures for tagging of equipment which must not be operated

Reference:

(1) Final Engineering Report and Safety Analysis, Paragraph 5.1.

SAN ONOFRE -

UNIT 1 3-34 Revised:

6/22/88

3.7 AUXILIARY ELECTRICAL SUPPLY APPLICABILITY:

Applies to the availability of electrical power for the operation of the plant auxiliaries.

OBJECTIVE:

To define those conditions of electrical power availabil ity necessary (1) to provide for safe reactor operation, (2) to provide for the continuing availability of engineered safeguards, and (3) to ensure that the station 72 can be maintained in the shutdown or refueling condition 5/3/83 for extended time periods.

SPECIFICATION:

I. In Modes 1, 2, 3 and 4 the following specifications 84 shall apply:

1 11/14/84 A. As a minimum the following shall be OPERABLE:

1.

One Southern California Edison Company and one 84 San Diego Gas & Electric Company high voltage 11/14/84 transmission line to the switchyard and two transmission circuits from the switchyard, one immediate and one delayed access, to the onsite safety-related distribution system.

This configuration constitutes the two required offsite circuits.

2. Two separate and independent diesel generators each with:

a. A separate day tank containing a minimum of 290 gallons of fuel,

b. A separate fuel storage system containing 34 a minimum of 37,500 gallons of fuel, and 4/1/77

c. A separate fuel transfer pump.

3. AC Distribution

a.

4160 Volt Bus 1C and 2C,

b. 480 Volt Bus No. 1, Bus No. 2 and Bus No.

3, and

c.

Vital Bus 1, 2, 3,

3A, 4, 5 and 6.

4. DC Bus No. 1 and DC Bus No. 2 (including at least one full capacity charger and battery 84 supply per bus).

11/14/84

5. The two Safety Injection System Load Sequencers.*

The automatic load function may be blocked in Mode 3 at a pressure <

1900 psig.

3-80 Revised:

11/28/84

84 B. Action 11/14/84

1. With one of the required offsite circuits 34 inoperable, demonstrate the OPERABILITY of the 4/1/77 remaining AC sources by performing Surveillance Requirement A of Technical Specification 4.4 within one hour and at least once per eight 107 (8) hours thereafter and Surveillance Requirement 8/17/88 B.1.a within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />; restore an additional offsite circuit to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in COLD SHUTDOWN within the next 34 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

4/1/77

2. If one diesel generator in declared inoperable, 84 demonstrate the OPERABILITY of the two offsite 11/14/84 transmission circuits and the remaining diesel generator by performing Surveillance Requirement A of Technical Specification 4.4 within one hour 107 and at least once per eight (8) hours thereafter 8/17/88 and Surveillance Requirement B.1.a within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />; restore the inoperable diesel generator to service within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in COLD SHUTDOWN 34 within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

4/1/77

3. With one offsite circuit and one diesel generator of the above required AC electrical power sources 84 inoperable, demonstrate the OPERABILITY of the 11/14/84 remaining AC sources by performing Surveillance Requirement A of Technical Specification 4.4 within one hour and at least once per eight 107 (8) hours thereafter and Surveillance Requiement 8/17/88 B.1.a within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />; restore at least one of the inoperable sources to OPERABLE status within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> or be in COLD SHUTDOWN within the next 4

36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. Have at least two offsite circuits and 4/1/77 two diesel generators OPERABLE within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> from, the time of initial loss or be in COLD SHUTDOWN within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

4. With two required offsite circuits inoperable, 84 demonstrate the OPERABILITY of two diesel 11/14/84 generators by performing Surveillance Requirement B.1.a of Technical Specification 4.4 within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, unless the diesel generators are already 8/17/88 operating; restore at least one of the inoperable sources to OPERABLE status within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or be in at least HOT STANDBY within the next 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

With only one of the required offsite circuits restored, restore the remaining offsite circuit 84 to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> from the time 11/14/84 of initial loss or be in COLD SHUTDOWN within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

SAN ONOFRE -

UNIT 1 3-81 Revised:

9/1/88

0

5. With two of the above required diesel generators inoperable, demonstrate the OPERABILITY of two offsite circuits by performing Periodic Testing Requirement A of Technical Specification 4.4 within one hour and at least once per two (2) hours there after; restore at least one of the inoperable diesel generators to OPERABLE status within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or be in COLD SHUTDOWN within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />. Restore both diesel generators to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> from time of initial loss or be in COLD SRUTDOWN within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

6. With less than the above complement of AC buses OPERABLE, restore the inoperable bus within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> or be in COLD SHUTDOWN within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

7. With one required DC bus inoperable, restore the inoperable bus to OPERABLE status within 2 84 hours9.722222e-4 days <br />0.0233 hours <br />1.388889e-4 weeks <br />3.1962e-5 months <br /> or be in COLD SHUTDOWN within the next 11/14/84 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

8.

With a required DC bus battery and both of its chargers inoperable, restore the inoperable battery and one of its chargers to operable status within 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> or be in cold shutdown within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

9. With one Safety Injection Load Sequencer inoperable, restore the inoperable sequencer to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in COLD SHUTDOWN within the next 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />.

II. Additionally, in Modes 1, 2 and 3 the following specifications shall apply:

A. As a minimum, the following shall be OPERABLE:

1. The MOV850C Uninterruptable Power Supply (UPS).

B. Action

1. With the MOV850C UPS inoperable, restore the UPS to OPERABLE status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.

3-82 Revised:

11/28/84

III. In Modes 5 and 6 the following specifications shall apply:

A. As a minimum, the following shall be OPERABLE:

1. One Southern California Edison Company or San Diego Gas and Electric Company high voltage transmission line to the switchyard and one transmission circuit from the switchyard, immediate or delayed access, to the onsite safety-related distribution system.

2. One diesel generator (capable of automatic 84 start) with:

11/14/84

a. A day tank containing a minimum 290 gallons of fuel,

b. A fuel storage system containing a minimum of 37,500 gallons of fuel, and

c. A fuel transfer pump.

3. The electrical Buses associated with the operable power sources as follows:

a. One 4,160 Volt AC Bus

b. One 480 Volt AC Bus

c. AC Vital Buses 1, 2 and 4, and

d. One DC Bus (including at least one full capacity charger and battery supply per Bus).

B. Action:

1. With less than the minimum required AC and DC electrical sources specified in III.A above, suspend all operations involving core alterations or positive reactivity changes.

Basis:

The station is connected electrically to the Southern 52 California Edison Company and San Diego Gas & Electric 9/26/79 Company system via either of two physically independent high voltage transmission routes composed of four Southern California Edison Company high voltage lines and four San 107 Diego Gas & Electric Company high voltage lines.

8/17/88 SAN ONOFRE -

UNIT 1 3-83 Revised:

9/1/88

Of the four Southern California Edison Company lines, any one can serve as a source of power to the station auxiliaries at 107 any time. Similarly, any of the four San Diego Gas &

8/17/88 Electric Company lines can serve as a source of power to the station auxiliaries at any time. By specifying one transmission line from each of the two physically independent 56 high voltage transmission routes, redundancy of sources of 2/6/81 auxiliary power for an orderly shutdown is provided.

Similarly, either transformer A or B, along with transformer C, provide redundancy of 4160 volt power to the auxiliary 84 equipment, and in particular to the safety injection trains. 11/14/84 Correct operation of the safety injection system is assured by the operability of the load sequencers and the UPS for MOV 850C. In addition, each 4160 volt bus has an onsite diesel generator as backup.

In MODES 1, 2, 3 and 4, two diesel generators provide the necessary redundancy to protect against a failure of one of the diesel generator systems or in case one diesel generator system is taken out for maintenance, without requiring a reactor shutdown.

This also eliminates the necessity for 107 depending on one diesel generator to operate for extended 8/17/88 periods without shutdown if it were required for post-accident conditions.

In MODES 5 and 6, the requirement for one source of offsite power and one diesel generator to be OPERABLE will provide diverse and redundant electrical power sources in order that the station can be maintained in the COLD SHUTDOWN or REFUELING condition for extended time periods. Additionally, this requirement will assure that operations involving core alterations or positive reactivity changes can be conducted safely.

SAN ONOFRE -

UNIT 1, 3-84 Revised:

9/1/88