DCL-21-020, Request for Revision to Technical Specification 3.8.1, AC Sources - Operating to Support Diesel Fuel Oil Transfer System Component Planned Maintenance

Request for Revision to Technical Specification 3.8.1, AC Sources - Operating to Support Diesel Fuel Oil Transfer System Component Planned Maintenance

ML21088A437
Person / Time
Site:	Diablo Canyon
Issue date:	03/29/2021
From:	Gerfen P Pacific Gas & Electric Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
DCL-21-020
Download: ML21088A437 (25)

Text

m PacHic Gas and Electric Company*

Paula Gerfen Site Vice President Diablo Canyon Power Plant Mail code 1046/605 P.O. Box 56 Avila Beach, CA 93424 805.545.4596 Internal: 691.4596 Fax: 805.545.4234 10 CFR 50.90 March 29, 2021 PG&E Letter DCL-21-020 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Diablo Canyon Units 1 and 2 Docket No. 50-275, OL-DPR-80 Docket No. 50-323, OL-DPR-82 License Amendment Request 21-03 Request for Revision to Technical Specification 3.8.1, AC Sources - Operating to Support Diesel Fuel Oil Transfer System Component Planned Maintenance

Dear Commissioners and Staff:

Pursuant to 10 CFR 50.90, Pacific Gas and Electric Company (PG&E) hereby requests approval of the enclosed proposed amendment to Facility Operating License Nos. DPR-80 and DPR-82 for Units 1 and 2 of the Diablo Canyon Power Plant, respectively. The enclosed license amendment request (LAR) proposes to revise Technical Specification (TS) 3.8.1, AC Sources - Operating.

The proposed changes would revise the TS 3.8.1 Condition F Completion Time to allow a separate one-time Completion Time of 7 days during the planned maintenance for each diesel fuel oil transfer pump (DFOTP) 0-1 and 0-2, with the portable DFOTP staged and available. The one-time Completion Time of 7 days for DFOTP 0-1 and 0-2 supports planned maintenance to maintain high reliability of the DFOTPs. The proposed one-time 7-day Completion Time reasonably avoids a potential dual-unit shutdown as a result of the current 72-hour Completion Time of TS 3.8.1 Condition F being exceeded during planned maintenance.

PG&E requests approval of this LAR no later than March 30, 2022, to support planning for the first DFOTP component planned maintenance in May 2022. PG&E requests the license amendment(s) be made effective upon NRC issuance, to be implemented within 60 days from the date of issuance.

PG&E makes no regulatory commitments (as defined by NEI 99-04) in this letter.

This letter includes no revisions to existing regulatory commitments.

A member of the STARS Alliance Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

Document Control Desk PG&E Letter DCL-21-020 March 29, 2021 Page 2 In accordance with site administrative procedures and the Quality Assurance Program, the proposed amendment has been reviewed by the Plant Staff Review Committee.

Pursuant to 10 CFR 50.91, PG&E is sending a copy of this proposed amendment to the California Department of Public Health.

If you have any questions or require additional information, please contact Mr. James Morris at 805-545-4609.

I state under penalty of perjury that the foregoing is true and correct.

Executed on March 29, 2021.

Sincerely,

~9:77}

Paula Gerfen Site Vice President kjse/51097806 Enclosure cc: Diablo Distribution cc/enc: Donald R. Krause, NRC Senior Resident Inspector Samson S. Lee, NRR Senior Project Manager Scott A. Morris, NRC Region IV Administrator Donald R. Krause, NRC Senior Resident Inspector Gonzalo L. Perez, Branch Chief, California Department of Public Health A member of the STARS Alliance Callaway

• Diablo Canyon

• Palo Verde

• Wolf Creek

Enclosure PG&E Letter DCL-21-020 Evaluation of the Proposed Change License Amendment Request 21-03 Request for Revision to Technical Specification 3.8.1, AC Sources - Operating to support Diesel Fuel Oil Transfer System Component Planned Maintenance

1.

SUMMARY

DESCRIPTION

2. DETAILED DESCRIPTION

3. TECHNICAL EVALUATION

4. REGULATORY EVALUATION 4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 Significant Hazards Consideration 4.4 Conclusions

5. ENVIRONMENTAL CONSIDERATION

6. REFERENCES ATTACHMENTS:

1. Technical Specification Page Markups

2. Retyped Technical Specification Page

3. Technical Specification Bases Page Markups 1

Enclosure PG&E Letter DCL-21-020 EVALUATION

1.

SUMMARY

DESCRIPTION This letter is a request to amend Facility Operating Licenses DPR-80 and DPR-82 for Units 1 and 2 of the Diablo Canyon Power Plant (DCPP),

respectively.

The proposed changes would revise the Facility Operating Licenses to revise the Technical Specification (TS) 3.8.1 Condition F Completion Time to allow a separate one-time Completion Time of 7 days during the planned maintenance for each diesel fuel oil (DFO) transfer pump (DFOTP) 0-1 and 0-2, with the portable DFOTP (PDFOTP) staged and available. The separate one-time Completion Time of 7 days for the DFOTP 0-1 and 0-2 supports planned maintenance to maintain high reliability of the DFOTPs. The proposed one-time 7-day Completion Time reasonably avoids a potential dual-unit shutdown as a result of the current 72-hour Completion Time of TS 3.8.1 Condition F being exceeded during either of the DFOTP 0-1 and 0-2 planned maintenance outages.

2. DETAILED DESCRIPTION Proposed Amendment The TS 3.8.1 Condition F Completion Time is revised to add the following note to the current "72-hour" Completion Time:

• A separate one-time Completion Time of 7 days is allowed during planned maintenance of each DFO transfer system pump 0-1 and 0-2 with the portable DFO transfer pump staged and available.

The proposed TS change is noted on the marked-up TS page provided in Attachment 1. The proposed retyped TS is provided in Attachment 2.

The TS Bases changes for TS 3.8.1 Condition F are included in Attachment 3 for information only and will be implemented in accordance with the TS Bases Control Program.

In summary, the TS 3.8.1 Condition F Completion Time is revised to allow a separate one-time Completion Time of 7 days during the planned maintenance for each DFOTP 0-1 and 0-2, with the PDFOTP staged and available for use.

The one-time Completion Time of 7 days for each DFOTP 0-1 and 0-2 supports planned maintenance to proactively preclude a failure in service of either DFOTP due to being near the end of its component design life. The proposed one-time 7 day Completion Time reasonably avoids a potential dual-unit shutdown as a result of the current 72-hour Completion Time of TS 3.8.1 Condition F being exceeded during either of the DFOTP 0-1 and 0-2 planned maintenance outages.

2

Enclosure PG&E Letter DCL-21-020 Diesel Fuel Oil Storage and Transfer System The diesel generator (DG) DFO system, maintains adequate storage of DFO and supplies it to the six DGs. The DFO transfer system is discussed in the DCPP Updated Final Safety Analysis Report Update (UFSAR), Section 9.5. The diagram of the engine fuel oil transfer system is shown in UFSAR Figure 3.2-21.

The physical arrangement of the diesel generator units is shown in Figures 9.5-10 and 9.5-11 for Unit 1 and the arrangement is similar for Unit 2.

The design data is given in Table 9.5-2.

The system consists of the following major components and features:

(1) two underground DFO storage tanks, each with a storage capacity of 50,000 gallons.

(2) two DFOTPs (DFOTP 0-1 or 0-2) located below ground level, each adjacent to a storage tank but in separate compartments. Each DFOTP delivers more than 55 gallons per minute (gpm) at a discharge pressure of approximately 50 pounds per square inch gauge. The pumps are a positive displacement rotary screw type with 5-horsepower motors. One pump is more than adequate to supply the six DGs of Unit 1 and Unit 2 (three DGs per unit) operating at full load. A duplex-type strainer is installed upstream of each DFOTP to protect the pump from particles that could damage it. A cartridge-type fuel oil filter is located at the discharge of the DFOTPs to prevent any fuel oil contamination from reaching the engine-base-mounted DFO tanks.

(3) two DFO supply headers to each unit DGs routed in separate trenches.

The motor controllers for the two DFOTPs are located inside the auxiliary building. Manual pump control stations and manual controls for the fuel oil day tank level control valves are located near each DG set.

Each DG is equipped with a skid-mounted fuel oil tank (referred to as a day tank) that has a capacity of 550 gallons, which provides about 2 1/2 hours of full load operation before fuel oil must be transferred from the underground storage tanks.

Each day tank has two separate, redundant DFOTP start/stop level switches.

Upon low level in a day tank, each level switch automatically starts a DFOTP and opens the supply header solenoid valve corresponding to the respective DFOTP, 0-1 or 0-2. Fuel is transferred to each DG day tank via two level control valves (LCVs) (and two associated upstream isolation valves) per DG. Each of the two LCVs and associated upstream isolation valves on each DG is associated with a separate DFO transfer system train.

The DFO transfer system design incorporates sufficient redundancy so that a malfunction of either an active or a passive component will not impair the ability 3

Enclosure PG&E Letter DCL-21-020 of the system to supply fuel oil. Two redundant DFOTPs (DFOTP 0-1 or 0-2) supply fuel oil to each DG day tank from either storage tank. The DFOTPs start automatically on low level in the day tanks. Each day tank has two associated redundant fuel oil transfer system LCVs that automatically open to replenish the day tank. The two 50,000-gallon DG storage tanks provide a 7-day supply of fuel.

Experience with the PG&E transmission system indicates that in the event of complete loss of offsite power, restoration of normal power sources could be accomplished within a few hours. However, a 7-day supply of onsite emergency power generation has been used as a conservative upper limit for design and safety evaluations of fuel storage capacity for the storage tanks, even though it is highly improbable that the DGs would be required to furnish plant auxiliary power for this long a period.

Single Failure Aspects of Diesel Fuel Oil Transfer System The DFO transfer system is designed to remain operable after sustaining a single failure of either an active or a passive component.

The capability to meet the single failure criterion is met by providing redundancy in tanks, pumps, valves, piping, and power supplies. The system arrangement provides sufficient separation of the tanks and their associated transfer pumps so that the possibility of damage to both simultaneously as a result of a single event is considered highly unlikely. The DFO transfer piping, transfer pumps, and tank manifold are arranged so a single failure of any pipe, valve, tank, or pump will not disable the system.

The design incorporates sufficient redundancy so that a malfunction or failure of either an active or a passive component will not impair the ability of the system to supply DFO.

The DFO system transfer components and power sources are redundant up to and including fill valves and connections on the DG engine day tanks, so that a single malfunction will not prevent the transfer of fuel oil. In the unlikely event of malfunctions in both redundant fuel oil headers, such as a pump failure in one and piping blockage in the other, low level will be alarmed when sufficient fuel oil remains in the base-mounted day tank for a nominal one-hour period of operation of the engine at full load. This nominal one-hour period is adequate for an operator (a) to correct a malfunction on one of the two redundant transfer headers, or (b) to line up manually the valves of the two headers into one path that will transfer fuel oil. All the valves necessary for this action are readily accessible in the compartments for the DFOTPs.

The nominal one-hour period to transfer power supply of DFO transfer pump to backup, or correct the issue on malfunctioning DFO transfer header, or crosstie 4

Enclosure PG&E Letter DCL-21-020 the 2 headers into one which will transfer fuel oil for an event such as a Station Blackout, Fire, or DFO transfer system failure is a recognized required operator action. Operators are currently trained on the one-hour time-critical operator action to restore DFO transfer capability as part of the DCPP Time Critical Operator Action Program. DCPP Interdepartmental Administrative Procedure OP1.ID2, Time Critical/Sensitive Operator Action, Action 42 is the operator action to transfer power supply of DFO transfer pump to backup, or correct the issue on malfunctioning DFO transfer header, or crosstie the 2 headers into one which will transfer fuel oil for a Station Blackout, Fire, or DFO transfer system failure.

Portable Diesel Fuel Oil Transfer System Pump The ability to connect a PDFOTP has been incorporated into the DFO storage and transfer system to enhance the overall reliability of the system and the DGs.

The PDFOTP is for postulated beyond design basis scenarios and is part of the DCPP licensing basis.

The ability to connect a PDFOTP pump was included as part of modifications to the fuel oil transfer system in response to issues identified in early versions of the DCPP Probability Risk Assessment (PRA). The modification to the fuel oil transfer system included connections for a backup PDFOTP. These modifications were modeled as recovery actions in the final DCPP PRA-1988 model as part of the Long Term Seismic Program. The recovery actions considered for the fuel oil transfer system included manually aligning a PDFOTP when both normal fuel oil transfer supply trains are unavailable and manipulating the valves in the DG rooms. A human action designation was defined for both of these actions in the DCPRA-1988 model. The NRC referenced the addition of the PDFOTP to the PRA model in its' evaluation of the Long Term Seismic Program in Supplemental Safety Evaluation Report 34 (Reference 1).

PG&E maintains control of the PDFOTP through Equipment Control Guideline Procedure ECG 21.2, Portable Fuel Oil Transfer Pump that requires availability of the PDFOTP to be capable of supplying fuel oil to the emergency DGs via the DFO storage and transfer system. If the PDFOTP is not available, ECG 21.2 requires it to be restored to available status within 30 days. ECG 21.2 contains quarterly surveillances to ensure dedicated components necessary for the operation of the PDFOTP are available at their storage location, the PDFOTP starts by battery-powered electric start or by hand cranking, and that the PDFOTP supplies the required flow. Although the PDFOTP is not seismically qualified, it is secured using seismic restraints on the PDFOTP cart in its storage room to prevent damage during a seismic event.

The use of the PDFOTP is proceduralized using DCPP Operating Procedure OP J-6C:V, Diesel Fuel Oil Transfer System - Use of Portable FOTP and DFO Day Tank LCVs. The PDFOTP can take suction from DFO Storage Tank 0-1 or DFO 5

Enclosure PG&E Letter DCL-21-020 Storage Tank 0-2 and can discharge to DFO Header 0-1 or DFO Header 0-2 to provide DFO to the six DG day tanks. Procedure OP J-6C:V also contains instructions to operate the DG day tank LCVs in manual if they are not functioning properly in Auto mode.

FLEX Portable Diesel Fuel Oil Transfer System Pump As part the DCPP mitigating strategies for beyond design basis events, PG&E also maintains a second flexible and diverse (FLEX) portable DFO transfer system pump (PDFOTP2) and associated hoses that can be connected into the DFO storage and transfer system. The PDFOTP2 consists of a portable fuel oil motor and pump with 40 gpm capacity that are stored at the FLEX storage facility located at an elevation of 300 feet to the south of DCPP Units 1 and 2. A functional test and inspection of the PDFOTP2 is performed every three months to demonstrate that the diesel engine for PDFOTP2 will start and run. There is also a monthly walkdown of PDFOTP2 performed by Operations and other tests and inspections performed on one-year, two-year, and three-year frequencies as part of the FLEX equipment maintenance program that ensures availability of the FLEX equipment.

Technical Specification 3.8.1 AC Sources - Operating The DCPP Unit Class 1E AC Electrical Power Distribution System AC sources consist of offsite power sources (normal and alternate), and the onsite standby power sources (three DGs for each unit). As required by 10 CFR 50, Appendix A, GDC 17, the design of the AC electrical power system provides independence and redundancy to ensure a power source is available to the engineered safety feature (ESF) systems.

The onsite Class 1E AC Distribution System for each unit is divided into three load groups so that the loss of any one group does not prevent the minimum safety functions from being performed. Each load group has connections to two offsite power sources and a single DG.

Offsite power is supplied to the 230-kilovolt (kV) and 500-kV switchyards from the transmission network by two 230-kV transmission lines and three 500-kV transmission lines. These two electrically and physically separated circuits provide AC power, through auxiliary and standby startup transformers, to the 4.16-kV ESF buses.

The onsite standby power source for each 4.16-kV ESF bus is a dedicated DG.

For Unit 1, DGs 1-1, 1-2, and 1-3 are dedicated to ESF buses H, G, and F, respectively. For Unit 2, DGs 2-1, 2-2, and 2-3 are dedicated to ESF buses G, H, and F, respectively. A DG starts automatically on a safety injection (SI) signal (e.g., low pressurizer pressure or high containment pressure signals),

undervoltage on the offsite standby startup source, or on an ESF bus degraded 6

Enclosure PG&E Letter DCL-21-020 voltage or undervoltage signal (refer to LCO 3.3.5, "Loss of Power (LOP) Diesel Generator (DG) Start Instrumentation"). After the DG has started, it will automatically tie to its respective bus after offsite power is tripped as a consequence of ESF bus undervoltage or degraded voltage, independent of or coincident with an SI signal. The DGs will also start and operate in the standby mode without tying to the ESF bus on an SI signal alone. Following the trip of offsite power, an undervoltage signal strips nonpermanent loads from the ESF bus. When the DG is tied to the ESF bus, loads are then sequentially connected to their respective ESF bus by the load sequencing timers (ESF timers). The sequencing logic controls the permissive and starting signals to motor breakers to prevent overloading the DG. Each ESF component is provided with its own load sequencing timer.

In the event of a loss of preferred power, the ESF electrical loads are automatically connected to the DGs in sufficient time to provide for safe reactor shutdown and to mitigate the consequences of a Design Basis Accident (DBA) such as a loss of coolant accident.

Certain required unit loads are returned to service in a predetermined sequence in order to prevent overloading the DG in the process. Within 1 minute after the initiating signal is received, all loads needed to recover the unit or maintain it in a safe condition are returned to service.

The initial conditions of DBA and transient analyses in the UFSAR, Chapter 6 and Chapter 15, assume ESF systems are OPERABLE. The AC electrical power sources are designed to provide sufficient capacity, capability, redundancy, and reliability to ensure the availability of necessary power to ESF systems so that the fuel, reactor coolant system (RCS), and containment design limits are not exceeded.

The OPERABILITY of the AC electrical power sources is consistent with the initial assumptions of the Accident analyses and is based upon meeting the design basis of the unit. This results in maintaining at least one train of ESF systems powered by the onsite or offsite AC sources OPERABLE during Accident conditions in the event of:

a. an assumed loss of all offsite power or all onsite AC power sources; and

b. a worst-case single failure in either the onsite AC electrical power sources or the Class 1E Electrical Power Distribution System.

The AC sources satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).

Each DG must be capable of starting, accelerating to rated speed and voltage, and connecting to its respective ESF bus on detection of bus undervoltage. This is accomplished within 10 seconds. Each DG must also be capable of accepting required loads within the assumed loading sequence intervals, and continue to 7

Enclosure PG&E Letter DCL-21-020 operate until offsite power can be restored to the ESF buses. These capabilities are required to be met from a variety of initial conditions such as DG in standby with the engine hot and DG in standby with the engine pre-lubed and pre-warmed. Additional DG capabilities must be demonstrated to meet required Surveillance, e.g., capability of the DG to automatically sequence the emergency loads onto the DG, following opening of the auxiliary breaker, on an ESF actuation signal while operating in parallel test mode.

The AC sources must be separate and independent (to the extent possible). For the DGs, separation and independence are complete.

The two redundant DFO supply trains supply fuel oil to DG day tanks from either storage tank. One pump supply train is adequate to supply the six DGs operating at full load.

The AC sources are required to be OPERABLE in MODES 1, 2, 3, and 4 to ensure that:

a. acceptable fuel design, limits and reactor coolant pressure boundary limits are not exceeded as a result of anticipated operational occurrences or abnormal transients; and

b. adequate core cooling is provided, and containment OPERABILITY and other PG&E Design Class I functions are maintained in the event of a postulated DBA.

TS 3.8.1 LCO C requires two supply trains of the DFO transfer system to be OPERABLE. TS Condition F corresponds to a level of degradation in which one train of the DFO transfer system is inoperable. The onsite AC electrical power systems are redundant and available to support ESF loads. However, one subsystem required for the onsite AC electrical system operability has lost its redundancy (DFO supply to the DGs).

TS Required Action F.1 requires to restore the DFO transfer system to OPERABLE status with a Completion Time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The 72-hour Completion Time takes into account the capacity and capability of the remaining AC sources, a reasonable time for repairs, and the low probability of a DBA occurring during this period.

If the TS Required Action F.1 Completion Time of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> is not met, then TS 3.8.1 Condition H ("Required Action and associated Completion Time of Condition A, B, C, D, E, F or G not met") must be entered with Required Action H.1 to be in MODE 3 with a Completion Time of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Required Action H.2 to be in MODE 4 with a Completion Time of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />. Since each train of the DFO system provides fuel to all six DGs for DCPP Units 1 and 2, if Condition H is entered with both DCPP units operating in MODE 1, then each unit needs to be 8

Enclosure PG&E Letter DCL-21-020 brought to MODEs 3 and 4 to comply with the TS 3.8.1 Condition H Required Actions H.1 and H.2.

Basis for Change PG&E is proactively planning to replace components in each of the DFOTPs (DFOTP 0-1 and DFOTP 0-2) during separate maintenance outage windows online in MODE 1 to maintain high system availability because the nominal 40-year motor design life is being reduced due to electric motor starts during performance of TS surveillances. In addition to the DFOTP electric motor, other DFOTP components may also be replaced during the planned separate DFOTP maintenance outage windows to support high system availability until the end of the DCPP 40-year facility operating licenses. The first DFOTP maintenance is currently planned during the spring of 2022.

The National Electrical Motors Association motors and generators guidance publication NEMA MG 10-2001, Table 7, states the maximum number of starts per hour for a 5-horsepower motor such as the DFOTP motor should be around 16 per hour. Currently a DFOTP motor starts approximately 12 times per hour during performance of TS Surveillance Requirement 3.8.1.6 that demonstrates that each required DFOTP operates and transfers fuel oil from the fuel oil storage tanks to each day tank. The number of DFOTP starts causes a reduction of life in the motor over time. The motors are currently approximately 30 years old.

Therefore, maintenance of the DFOTP electric motors has been included in the aging management long-range plan to proactively preclude a failure in service due to being near the end of their component design life. Immediate DFOTP electric motor maintenance is not warranted based on motor performance data collected during recent surveillance testing.

The maintenance of each of the DFOTP electric motors is expected to take at least half of the 72-hour Completion Time of TS 3.8.1 Condition F. The replacement DFOTP motors are a different model that have a different base plate configuration than the current motors. Installation of the DFOTP motors will require concrete boring to accommodate the different bolt hole locations in the replacement DFOTP motor base plates. The maintenance of other DFOTP components, such as the pumps, or unforeseen maintenance complications may add additional duration to the DFOTP maintenance outage. If the TS 3.8.1 Condition F 72-hour Completion Time is not met during the DFOTP maintenance, then Condition H requires both DCPP units to be brought to MODEs 3 and 4 to comply with the TS 3.8.1 Condition H Required Actions H.1 and H.2. In the event of a dual-unit shutdown, the electrical grid would lose the DCPP as a reliable source of baseload power.

In order to reasonably avoid a potential dual-unit shutdown as a result of the 72-hour Completion Time of TS 3.8.1 Condition F being exceeded during the DFOTP planned maintenance, PG&E is requesting a separate one-time 7-day 9

Enclosure PG&E Letter DCL-21-020 Completion Time for TS 3.8.1 Condition F to support the planned maintenance for each DFOTP 0-1 and 0-2.

3. TECHNICAL EVALUATION Technical Specification Changes The TS 3.8.1 Condition F Completion Time is revised to allow a separate one-time Completion Time of 7 days during the planned maintenance for each DFOTP 0-1 and 0-2, with the PDFOTP staged and available. The one-time Completion Time of 7 days for each of the DFOTP 0-1 and 0-2 supports planned maintenance to proactively preclude a failure in service of the DFOTP due to being near the end of its component design life.

TS 3.8.1 Condition F corresponds to a level of degradation in which one train of the DFO transfer system is inoperable and one subsystem required for the onsite AC electrical system operability has lost its redundancy (DFO supply to the DGs).

The DFO transfer system components and power sources are redundant up to and including fill valves and connections on the DG engine day tanks, so that a single malfunction does not prevent the transfer of fuel oil. In the unlikely event that both redundant fuel oil headers are inoperable, such as a pump failure in one and piping blockage in the other, low level will be alarmed when sufficient fuel oil remains in the base-mounted day tank for a nominal one-hour period of operation of the engine at full load. This nominal one-hour period is adequate for an operator (a) to correct a malfunction on one of the two redundant transfer headers, or (b) to line up manually the valves of the two headers into one path that will transfer fuel oil. All the valves necessary for this action are readily accessible in the compartments for the DFOTPs.

The separate one-time Completion Time of 7 days during the planned maintenance of each DFOTP 0-1 and 0-2 is reasonable based on the capabilities of the other permanent DFOTP (DFOTP 0-1 during the DFOTP 0-2 maintenance and DFOTP 0-2 during the DFOTP 0-1 maintenance) and the staged PDFOTP that can provide adequate DFO to the DGs during design basis events. The separate one-time Completion Time of 7 days during the planned maintenance of each DFOTP 0-1 and 0-2 is also reasonable since it provides sufficient time to perform the required maintenance activities to maintain high reliability of the DFOTPs and the low probability of a DBA occurring during this period. In addition, based on risk insights using the DCPP Probabilistic Risk Assessment (PRA) model, the 7-day Completion Time for each DFOTP (4 additional days beyond the current 3-day Completion Time for each DFOTP) has been determined to not be risk significant. While in Condition F, the remaining DFOTP will remain OPERABLE to supply DFO to the six DGs and the PDFOTP will be staged and available to be connected to supply DFO to the six DGs. Staging of the PDFOTP is a risk management action being taken to offset risk during the 10

Enclosure PG&E Letter DCL-21-020 DFOTP 0-1 and 0-2 planned maintenance based on risk insights from the DCPP PRA model.

The FLEX PDFOTP2 is available to provide adequate DFO to the DGs during beyond design basis events through deployment from the FLEX equipment storage facility. It is noted that the PDFOTP2 will not be staged by the DFOTPs during the DFOTP 0-1 and 0-2 planned maintenance to ensure it is not damaged during a postulated beyond design basis external event.

The proposed one-time 7-day Completion Time reasonably avoids a potential dual-unit shutdown as a result of the current 72-hour Completion Time of TS 3.8.1 Condition F being exceeded during planned maintenance of each DFOTP 0-1 and 0-2. In the event of a dual-unit shutdown, the electrical grid would lose DCPP as a reliable source of baseload power.

Technical Specification Bases Changes The TS Bases for the TS 3.8.1 Condition F Completion Time are updated as follows:

The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time is modified by a note that allows a one-time Completion Time of 7 days during the planned maintenance of each DFO transfer system pump 0-1 and 0-2 with the portable DFO transfer pump staged and available. The one-time Completion Time of 7 days is reasonable considering the additional requirement to have the portable DFO transfer pump staged and available during the one-time Completion Time for each DFO transfer system supply train to offset additional risk that is incurred, based on the risk insights obtained from the DCPP PRA model.

The TS Bases change reflects the change to TS 3.8.1 for the one-time 7-day Completion Time for each DFOTP 0-1 and 0-2 planned maintenance and that the portable DFO transfer pump needs to be staged and available based on the risk insights from the DCPP PRA model. The TS Bases change will be implemented in accordance with the TS Bases Control Program as part of amendment implementation.

Risk Insights This LAR is not a risk-informed LAR. However, for additional information, the risk insights determined with the DCPP PRA model are summarized here.

Taking one train of the DFOTP system out for maintenance at a time has been assessed using the DCPP PRA model, which includes internal events, internal flooding, fire, and seismic. This assessment assumes that during the extended Completion Time: (1) the other train of the DFOTP system is available; and (2) 11

Enclosure PG&E Letter DCL-21-020 the PDFOTP and necessary supporting equipment will be staged prior to and while one of the normal DFOTP trains is out of service for the planned maintenance.

For the PRA assessment, the total additional exposure time of 8 days is used.

This is based on the proposed extension of the current Completion Time from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> (3 days) to 7 days and the application of the extension to both trains of the DFOTP system. The incremental conditional core damage probability (ICCDP) and the incremental conditional large early release probability (ICLERP) using the core damage frequency and large early release frequency increase above the baseline plant risk have been calculated. The PRA assessment credited the function of the remaining train of the DFO transfer system and the function of the PDFOTP due to it being staged and available (no credit was taken for the FLEX PDFOTP2). The results demonstrate that ICCDP and ICLERP are below the risk significance criteria of Regulatory Guide 1.174, 1.0E-06, and 1.0E-07, respectively. Therefore, the proposed separate one-time extension of TS 3.8.1 Condition F to 7 days for planned maintenance for each DFOTP is considered to not be risk significant.

The following risk management actions have been determined to be appropriate based on evaluation of the insights from the PRA assessment and have been accepted by Operations to be implemented during the proposed TS 3.8.1 Condition F 7-day Completion Time:

• Stage the PDFOTP prior to entering the TS 3.8.1 Condition F and until exiting from the condition.

• Protect offsite AC power circuits while in TS 3.8.1 Condition F.

• Protect Unit 1 and 2 turbine-driven auxiliary feedwater pump train and its supporting equipment while in TS 3.8.1 Condition F.

The proposed change has been determined to not be risk significant, and it does not:

• substantially increase the likelihood or consequences of accidents that are risk significant but are beyond the design and licensing basis of the plant;

• degrade multiple levels of defense, or cornerstones in the reactor oversight process, through plant operations or situations not explicitly considered in the development of the regulations;

• significantly reduce the availability or reliability of structures, systems, or components that are risk significant but are not required by regulations; or

• involve changes for which the synergistic or cumulative effects could significantly impact risk, 12

Enclosure PG&E Letter DCL-21-020 Therefore, the proposed change does not create a special circumstance described in Appendix D, Use of Risk Information in Review of Non-Risk-Informed License Amendment Requests, of NUREG-0800 (Standard Review Plan), Chapter 19.2, Review of Risk Information Used to Support Permanent Plant-Specific Changes to the Licensing Basis General Guidance.

Diesel Fuel Oil Transfer Pump Summary/Conclusion The impact on the DFO transfer system has been evaluated for the proposed revised TS 3.8.1 Condition F that provides a separate one-time Completion Time of 7 days for the planned maintenance of each DFOTP.

The redundancy of the DFO transfer system makes the loss of one DFOTP, while in the proposed TS 3.8.1 Condition F Completion Time of 7 days, bounded by the UFSAR accident analyses since the redundancy of the DFO transfer system to provide DFO to the DGs is reduced, however the function can still be performed by the remaining OPERABLE DFOTP. The proposed TS 3.8.1 Condition F increased Completion Time includes a note with an additional requirement to have the PDFOTP staged and available such that it can be quickly connected to supply DFO to the six DGs, if needed, to offset the additional risk of the separate one-time 7-day Completion Time for each DFOTP.

Staging of the PDFOTP is a risk management action that that is being taken during the planned maintenance of each DFOTP 0-1 and 0-2 based on risk insights from the DCPP PRA model.

In addition, based on risk insights using the DCPP PRA model, the separate one-time 7-day Completion Time proposed for TS 3.8.1 Condition F for planned maintenance to each DFOTP has been determined to not be risk significant.

Risk management actions have been determined, based on insights from the PRA evaluation, and have been accepted by Operations to be implemented during the proposed TS 3.8.1 Condition F 7-day Completion Time.

4. REGULATORY ANALYSIS 4.1 Applicable Regulatory Requirements/Criteria The proposed change to the requirements in TS 3.8.1, AC Sources -

Operating Condition F is to allow a separate one-time Completion Time of 7 days during the planned maintenance of each DFOTP 0-1 and 0-2, with the PDFOTP staged and available. The one-time Completion Time of 7 days for each of the DFOTP 0-1 and 0-2 supports planned maintenance to proactively preclude a failure in service of a DFOTP due to being near the end of its component design life.

13

Enclosure PG&E Letter DCL-21-020 General Design Criteria DCPP Units 1 and 2 were designed to comply with the Atomic Energy Commission (now the Nuclear Regulatory Commission, or NRC) General Design Criteria (GDC) for Nuclear Power Plant Construction Permits, published in July 1967. PG&E has made subsequent commitments to GDCs issued later that are discussed in Section 3.1 of the DCPP UFSAR.

Since the requested change does not involve any change to the DFO transfer system design function and it only allows a separate one-time extension to an existing TS Completion Time, controlled by 10 CFR 50.36, for one train of the DFO transfer system being inoperable, there is no impact on the compliance to the GDC applicable to the DFO transfer system.

10 CFR 50.36 - Technical Specification Regulation in 10 CFR 50.36(c)(2)(i) states, in part, that:

Limiting conditions for operation are the lowest functional capability or performance levels of equipment required for safe operation of the facility. When a limiting condition for operation of a nuclear reactor is not met, the licensee shall shut down the reactor or follow any remedial action permitted by the technical specifications until the condition can be met.

The TS remedial actions must provide the requisite reasonable assurance of public health and safety. With the proposed change to the TS 3.8.1 Condition F Completion Time, an additional remedial action is added to require that the PDFOTP is staged and available to offset risk with one DFO transfer system train inoperable for up to 7 days. The proposed 7-day Completion Time can only be used once during planned maintenance to each DFOTP 0-1 and 0-2. Therefore, the requisite reasonable assurance of public health and safety will continue to be provided.

10 CFR 50.63 - Loss of All Alternating Current Power In the event of a station black-out, a DFOTP powered from a Class 1E 480-V bus in the non-blacked-out unit takes suction from a DFO storage tank and provides fuel oil to the day tank associated with the DG (alternate AC source) supplying the blacked-out unit.

Each DG at DCPP is served by its own separate day tank, which is supplied from a common storage tank.

14

Enclosure PG&E Letter DCL-21-020 There are no changes being proposed such that compliance with any of the regulatory requirements above would come into question. The evaluations documented above confirm that PG&E will continue to comply with all applicable regulatory requirements.

In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

4.2 Precedent None.

4.3 Significant Hazards Consideration PG&E has evaluated whether a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, Issuance of amendment, as discussed below:

1. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?

Response: No.

The proposed change to the requirements in TS 3.8.1, AC Sources -

Operating Condition F to allow a separate one-time Completion Time of 7 days during the planned maintenance of each DFOTP 0-1 and 0-2, with the PDFOTP staged and available. The one-time Completion Time of 7 days for each DFOTP 0-1 and 0-2 supports planned maintenance to proactively preclude a failure in service of the DFOTP due to being near the end of its component design life. The DFO transfer system is not an initiator of any UFSAR Chapter 6 or 15 DBA or event, and therefore, the proposed change does not increase the probability of any accident previously evaluated. The DFO transfer system is used to supply DFO to the DGs to respond to accidents that have been previously evaluated.

The proposed change affects only the time allowed for a DFO transfer system train to be inoperable and does not affect the design of the DFO transfer system. With the change to TS 3.8.1, adequate DFO continues to be provided to the DGs for accidents previously evaluated and there is no significant impact on accident consequences. The proposed change does 15

Enclosure PG&E Letter DCL-21-020 not significantly change how the plant would mitigate an accident previously evaluated.

Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.

2. Does the proposed change create the possibility of a new or different accident from any accident previously evaluated?

Response: No.

The proposed change does not result in a change in the manner in which the DFO transfer system provides plant protection. The DFO transfer system will continue to perform the function of providing DFO to the DGs while in the proposed revised TS 3.8.1 Condition F. The change does not involve a physical alteration of the plant that impacts the capability of the DFO transfer system to perform its design function. The staging and potential use of the PDFOTP is not an accident initiator.

Therefore, the proposed change does not create the possibility of a new or different accident from any accident previously evaluated.

3. Does the proposed change involve a significant reduction in a margin of safety?

Response: No.

The proposed change does not alter the manner in which safety limits, limiting safety system settings, or LCOs are determined. The safety analysis acceptance criteria are not impacted by this change. The proposed change will not result in plant operation in a configuration outside the existing design basis since TS 3.8.1 Condition F already allows one train of the DFO transfer system to be inoperable. The PDFOTP that will be staged and available to be connected to supply DFO to the six DGs during the proposed TS 3.8.1 Condition F increased Completion Time will offset risk. Plant operators are trained to use the PDFOTP with existing plant operating procedures.

Therefore, the proposed change does not involve a significant reduction in a margin of safety.

Based on the above evaluation, PG&E concludes that the proposed change does not involve a significant hazards consideration under the standards set forth in 10 CFR 50.92(c), and accordingly, a finding of no significant hazards consideration is justified.

16

Enclosure PG&E Letter DCL-21-020 4.4 Conclusions In conclusion, based on the considerations discussed above; (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commissions regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.

5. ENVIRONMENTAL CONSIDERATION PG&E has evaluated the proposed amendment and has determined that the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.

6. REFERENCES

1. NRC, NUREG-0675, Safety Evaluation Report Related to the Operation of Diablo Canyon Nuclear Power Plant, Units 1 and 2, Supplement No. 34, dated June 1991 17

Enclosure Attachment 1 PG&E Letter DCL-21-020 Proposed Technical Specification Changes (marked-up)

AC Sources - Operating 3.8.1 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME C. Two required offsite circuits C.1 Declare required 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> from inoperable. feature(s) inoperable discovery of Condition when its redundant C concurrent with required feature(s) is inoperability of inoperable. redundant required features.

AND I

C.2 Restore one required 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> offsite circuit to OPERABLE status.

D. One required offsite circuit D.1 Restore required offsite 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> inoperable. circuit to OPERABLE status.

AND I OR I

One DG inoperable. D.2 Restore DG to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> OPERABLE status.

E. Two or more DGs E.1 Ensure at least two DGs 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> inoperable. are OPERABLE.

F. One supply train of the F.1 Restore the DFO transfer 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> ,t' DFO transfer system system to OPERABLE I

- --1 I

inoperable. status. I I

G. Two supply trains of the G.1 Restore one train of the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> DFO transfer system DFO transfer system to inoperable. OPERABLE status.

H. Required Action and H.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion AND Time of Condition A, B, C, I D, E, F or G not met. H.2 -----------NOTE-----------

LCO 3.0.4.a is not applicable when entering

)

MODE 4.

Be in MODE 4. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> (continued)

I I I I I I I I I I I I I I I I I I I I I : I I I

I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I

• A separate one-time Completion Time of 7 days is allowed during planned maintenance of each DFO transfer system pump 0-1 and 0-2 with the portable DFO transfer pump staged and

- ___ I available.

I I

I I I

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I I I

I I I

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I I DIABLO CANYON - UNITS 1 & 2 3.8-3 Unit 1 - Amendment No. 135, 219, II Rev 12 Page 1 of 1 Unit 2 - Amendment No. 135, 221, II TS Tab 3-8 Markup Page 3.8-3.doc 0310.1454

Enclosure Attachment 2 PG&E Letter DCL-21-020 Proposed Technical Specification Changes (retyped)

Remove Page Insert Page 3.8-3 3.8-3

AC Sources - Operating 3.8.1 ACTIONS (continued)

CONDITION REQUIRED ACTION COMPLETION TIME C. Two required offsite circuits C.1 Declare required 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> from inoperable. feature(s) inoperable discovery of Condition when its redundant C concurrent with required feature(s) is inoperability of inoperable. redundant required features.

AND C.2 Restore one required 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> offsite circuit to OPERABLE status.

D. One required offsite circuit D.1 Restore required offsite 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> inoperable. circuit to OPERABLE status.

AND OR One DG inoperable. D.2 Restore DG to 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> OPERABLE status.

E. Two or more DGs E.1 Ensure at least two DGs 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> inoperable. are OPERABLE.

F. One supply train of the F.1 Restore the DFO transfer 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />s*

DFO transfer system system to OPERABLE inoperable. status.

G. Two supply trains of the G.1 Restore one train of the 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> DFO transfer system DFO transfer system to inoperable. OPERABLE status.

H. Required Action and H.1 Be in MODE 3. 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> associated Completion AND Time of Condition A, B, C, D, E, F or G not met. H.2 -----------NOTE-----------

LCO 3.0.4.a is not applicable when entering MODE 4.

Be in MODE 4. 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> (continued)

• A separate one-time Completion Time of 7 days is allowed during planned maintenance of each DFO transfer system pump 0-1 and 0-2 with the portable DFO transfer pump staged and available.

DIABLO CANYON - UNITS 1 & 2 3.8-3 Unit 1 - Amendment No. 135, 219, Rev 12 Page 1 of 1 Unit 2 - Amendment No. 135, 221, TS Tab 3-8 Retype Page 3.8-3.doc 0310.1457

Enclosure Attachment 3 PG&E Letter DCL-21-020 Technical Specification Bases Page Markups (For information only)

AC Sources - Operating 3.8.1 (continued)

BASES ACTIONS D.1 and D.2 (continued)

Condition may appear higher than that in Condition C (loss of both required offsite circuits). This difference in reliability is offset by the susceptibility of this power system configuration to a single bus or switching failure. The 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Completion Time takes into account the capacity and capability of the remaining AC sources, a reasonable time for repairs, and the low probability of a DBA occurring during this period.

E.1 With two or more DGs inoperable, the remaining onsite AC sources are inadequate. Thus, with an assumed loss of offsite electrical power, insufficient standby AC sources are available to power the minimum required ESF functions. Since the offsite electrical power system may be the only source of AC power for this level of degradation, the risk associated with continued operation for a very short time could be less than that associated with an immediate controlled shutdown (the immediate shutdown could cause grid instability, which could result in a total loss of AC power). Since any inadvertent generator trip could also result in a total loss of offsite AC power, the time allowed for continued operation is severely restricted. The intent here is to avoid the risk associated with an immediate controlled shutdown and to minimize the risk associated with this level of degradation.

According to Reference 6, with two or more DGS inoperable, operation may continue for a period that should not exceed 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.

F.1 Condition F corresponds to a level of degradation in which one train of the DFO transfer system is inoperable. The onsite AC electrical power systems are redundant and available to support ESF loads. However, one subsystem required for the onsite AC electrical system operability has lost its redundancy (DFO supply to the DGs).

The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time takes into account the capacity and capability of the remaining AC sources, a reasonable time for repairs, and the low probability of a DBA occurring during this period.

The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> Completion Time is modified by a note that allows a one-time Completion Time of 7 days during the planned maintenance of each DFO transfer system pump 0-1 and 0-2 with the portable DFO transfer pump staged and available. The one-time Completion Time of 7 days is reasonable considering the additional requirement to have the portable DFO transfer pump staged and available during the one-time Completion Time for each DFO transfer system supply train to offset additional risk that is incurred, based on the risk insights obtained from the DCPP PRA model.

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