Text

Insertion Instructions for Technical Specification Bases Revision 55, Summary of Changes
	ML11287A033
Person / Time
Site:	Palo Verde
Issue date:	09/01/2011
From:	Stephenson C; Arizona Public Service Co
To:	; Office of Nuclear Reactor Regulation
References
	102-06414-TNW/CJS
	Download: ML11287A033 (39)
	v • d • e

Insertion Instructions for Technical Specifications Bases Revision 55 Summary of Changes Technical Specification Bases Revision 55 incorporates LDCRs 08-B015, 11-B006, 11-B007, 11-B008, 11-B009 and 11-B011.

LDCR 08-B015 updates the references for the Low Temperature Over Pressure Protection (L TOP) TS Bases 3.4.13. This update reflects the replacement of the steam generators for all 3 Units and is consistent with the current design basis.

LDCR 11-B006 clarifies TS Bases 3.7.6, Condensate Storage Tank (CST),

Actions A.1 and A.2 description to indicate that the Reactor Makeup Water Tank (RMWT), when used as an alternate source of water with the CST, need only contain enough water to supplement any reduced inventory in the CST. The combined inventories of the RMWT and CST may be credited to mitigate an event during the period of CST inoperability.

LDCR 11-B007 clarifies TS Bases 3.4.12, Pressurizer Vents, Surveillance Requirement (SR) 3.4.12.1 with regard to post-maintenance testing of individual valves in the pressurizer vent paths. The change clarifies that in any Mode, partial surveillance tests can be performed for post-maintenance testing under site procedural controls that ensure the valve being tested is isolated from Reactor Coolant System (RCS) pressure. This change is consistent with approved LDCR 11-R002 for related TRM Section T3.4, Reactor Coolant System, TSR 3.4.104.2.

LDCR 11-B008 corrects editorial and typographical errors in TS Bases Sections 3.3.12 and 3.8.1. Specifically, the word 'Channel' is corrected on page B 3.3.12-5, second paragraph, and TS Bases page 3.8.1-43, first paragraph, Reference 12 is corrected to Reference 11.

LDCR 11-B009 provides greater clarity as to what actions are required to place the control room essential ventilation systems in the correct mode of operation to comply with TS Required Actions, and clarifies the appropriate reasons for the specifications being applicable.

Specifically, the change deletes reference to a Waste Gas Tank rupture event in TS Bases Sections 3.3.9, Control Room Essential Filtration Actuation Signal (CREFAS) and 3.7.11 ,Control Room Essential Filtration System (CREFS),

Applicability. Credit for CREFAS or CREFS for a Waste Gas Decay Tank rupture event was removed from the UFSAR by LDCR 98-F064. Both specifications remain applicable for Modes 5 or 6, as fuel handling accidents are of interest in these lower Modes.

In addition, LDCR 11-B009 adds to TS Bases Sections 3.3.9, 3.7.11 and 3.7.12, Control Room Emergency Air Temperature Control System (CREATCS), Actions, clarifying text as to what actions are required to place the control room essential

Insertion Instructions for Technical Specifications Bases Revision 55 ventilation systems in the correct mode of operation to comply with various TS Required Actions. Specifically, CREFS needs to be in the essential filtration mode and the support systems for CREATCS need to be placed in operation to support its temperature control function.

LDCR 11-B011 reflects the Refueling Water Tank level setpoints, approved in License Amendment 182, have been implemented in all three PVNGS Units.

The Pre-RWT Setpoint data in TS Bases Section 3.5.5 is no longer required.

This change is an administrative change to reflect the current plant configuration.

REMOVE PAGES INSERT PAGES Cover page Cover page List of Effective Pages List of Effective Pages 1/2 through 7/8 1/2 through 7/8 B 3.3.9-3 / B 3.3.9-4 B 3.3.9-3 / B 3.3.9-4 B 3.3.12-5 / B 3.3.12-6 B 3.3.12-5 / B 3.3.12-6 B 3.4.12-3 / B 3.4.12-4 B 3.4.12-3 / B 3.4.12-4 B 3.4.13-1 / B 3.4.13-2 B 3.4.13-1 / B 3.4.13-2 B 3.4.13-3 / B 3.4.13-4 B 3.4.13-3 / B 3.4.13-4 B 3.4.13-5 / B 3.4.13-6 B 3.4.13-5 / B 3.4.13-6 B 3.4.13-9 / B 3.4.13-10 B 3.4.13-9 / B 3.4.13-10 B 3.4.13-11 / Blank B 3.4.13-11 / Blank B 3.5.5-3 / B 3.5.5-4 B 3.5.5-3 / B 3.5.5-4 B 3.7.6-3 / B 3.7.6-4 B 3.7.6-3 / B 3.7.6-4 B 3.7.11-3 / B 3.7.11-4 B 3.7.11-3 / B 3.7.11-4 B 3.7.11-5 / B 3.7.11-6 B 3.7.11-5 / B 3.7.11-6 B 3.7.12-3 / B 3.7.12-4 B 3.7.12-3 / B 3.7.12-4 B 3.8.1-43 / B 3.8.1-44 B 3.8.1-43 / B 3.8.1-44 2

PVNGS Palo Verde Nuclear Generating Station Units 1, 2, and 3 Technical Specification Bases Revision 55 September 1, 2011 Stephenson, Digitally signed by Stephenson, Carl J(Z05778)

DN: cn=Stephenson, Carl J(Z05778)

Reason: I attest to the accuracy and integrity of Carl J(Z05778) this document Date: 2011.08.25 10:16:07 -07'00'

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B 3.8.10-3 48 B 3.8.10-4 o B 3.9.1-1 34 Corrected B 3.9.1-2 o B 3.9.1-3 o B 3.9.1-4 o B 3.9.2-1 48 B 3.9.2-2 15 B 3.9.2-3 15 B 3.9.2-4 15 B 3.9.3-1 18 B 3.9.3-2 19 B 3.9.3-3 27 B 3.9.3-4 19 B 3.9.3-5 19 B.3.9.3-6 19 B 3.9.4-1 o B 3.9.4-2 54 B 3.9.4-3 o B 3.9.4-4 o B 3.9.5-1 o B 3.9.5-2 54 B 3.9.5-3 27 B 3.9.5-4 16 B.3.9.5-5 16 B 3.9.6-1 o B 3.9.6-2 o B 3.9.6-3 o B 3.9.7-1 o B 3.9.7-2 o B 3.9.7-3 o PALO VERDE UNITS 1, 2, AND 3 8 Revision 55 September 1, 2011

CREFAS B 3.3.9 BASES LCO a. Manual Trip (continued)

The LCO on Manual Trip backs up the automatic trips and ensures operators have the capability to rapidly initiate the CREFAS Function if any parameter is trending toward its setpoint. One channel must be OPERABLE. This considers that the Manual Trip capability is a backup and that other means are available to actuate the redundant train if required.

including manual SIAS. FBEVAS. or CPIAS.

b. Radiation Monitors One channel of radiation monitor is required to be OPERABLE to ensure the control room filtration actuates on high gaseous activity.

c. Actuation Logic One train of Actuation Logic must be OPERABLE. since there are alternate means available to actuate the redundant train. including SIAS.

APPLICABILITY The CREFAS Functions must be OPERABLE in MODES 1. 2. 3. 4.

5. and 6 and during movement of irradiated fuel assemblies in either the fuel building or the containment building. to ensure a habitable environment for the control room operators.

Movement of spent fuel casks containing irradiated fuel assemblies is not within the scope of the Applicability of this technical specification. The movement of dry casks containing irradiated fuel assemblies will be done with a single-failure-proof handling system and with transport equipment that would prevent any credible accident that could result in a release of radioactivity.

ACTIONS A CREFAS channel is inoperable when it does not satisfy the OPERABILITY criteria for the channel's function. The most common cause of channel inoperability is outright failure.

(continued)

PALO VERDE UNITS 1.2.3 B 3.3.9-3 REVISION 55

CREFAS B 3.3.9 BASES ACTIONS A.1, B.1, B.2, C.1, C.2.1, C.2.2, and C.2.3 (continued)

Conditions A, B, and C are applicable to manual and automatic actuation of the CREFAS. Condition A applies to the failure of the CREFAS Manual Trip, Actuation Logic, and radiation monitor channel in MODE 1, 2, 3, or 4. Entry into this Condition requires action to either restore the failed channel or manually perform the CREFS safety function, Required Action A.1 - place one train of CREFS in the essential filtration mode (e.g., emergency or pressurization mode of operation - fan running, valves/dampers aligned to the post-CREFAS mode). The Completion Time of 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months is sufficient to complete the Required Actions and accounts for the fact that CREFAS supplements control room filtration by other Functions (e.g., SIAS) in MODES 1, 2, 3, and 4. If Required Action A.1 and the associated completion time are not met, the plant must be brought to a MODE in which the LCO does not apply. To achieve this status, the plant must be brought to at least MODE 3 within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months (Required Action B.1) and to MODE 5 within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months (Required Action B.2). The Completion Times of 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months for reaching MODES 3 and 5 from MODE 1 are reasonable, based on operating experience and normal cooldown rates, for reaching the required MODE from full power conditions in an orderly manner and without challenging plant safety systems or operators.

Condition C applies to the failure of CREFAS Manual Trip, Actuation Logic, and radiation monitor channel in MODE 5 or 6, or when moving irradiated fuel assemblies. The Required Actions are immediately taken to place one OPERABLE CREFS train in the essential filtration mode (e.g., emergency or pressurization mode of operation - fan running, valves/dampers aligned to the post-CREFAS mode) or to suspend CORE ALTERATIONS, positive reactivity additions, and movement of irradiated fuel assemblies. The Completion Time recognizes the fact that FBEVAS, or CPIAS are available to initiate the control room essential filtration mode in the event of a fuel handling accident.

(continued)

PALO VERDE UNITS 1,2,3 B 3.3.9-4 REVISION 55

Boron Dilution Alarm System (BOAS)

B 3.3.12 BASES (continued)

SURVEILLANCE SR 3.3.12.1 REQUIREMENTS SR 3.3.12.1 is the performance of a CHANNEL CHECK on each required channel every 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months . A CHANNEL CHECK is normally a comparison of the parameter indicated on one channel to a similar parameter on other channels. It is based upon the assumption that instrument channels monitoring the same parameter should read approximately the same value. Significant deviations between instrument channels could be an indication of excessive instrument drift in one of the channels or of something even more serious. CHANNEL CHECK will detect gross channel failure; thus, it is key to verifying that the instrumentation continues to operate properly between each CHANNEL CALIBRATION.

Agreement criteria are determined by the plant staff and should be based on a combination of the channel instrument uncertainties. If a channel is outside of the criteria, it may be an indication that the transmitter or the signal processing equipment has drifted outside of its limits. If the channels are within the criteria, it is an indication that the channels are OPERABLE. For clarification, a CHANNEL CHECK is a qualitative assessment of an instrument's behavior. Where possible, a numerical comparison between like instrument channels should be included but is not required for an acceptable CHANNEL CHECK performance.

The Frequency, about once every shift, is based on operating experience that demonstrates the rarity of channel failure.

Since the probability of two random failures in redundant channels in any 12 hour1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months period is extremely low, CHANNEL CHECK minimizes the chance of loss of protective function due to failure of redundant channels. CHANNEL CHECK supplements less formal, but more frequent, checks of channel OPERABILITY during normal operational use of displays associated with the LCO required channels.

This SR is modified by a Note that states the CHANNEL CHECK is not required to be performed until 1 hour1.157407e-5 days 2.777778e-4 hours 1.653439e-6 weeks 3.805e-7 months after neutron flux is within the startup range. Neutron flux is defined to be within the startup range following a reactor shutdown when reactor power is 2E-6% NRTP or less.

(continued)

PALO VERDE UNITS 1,2,3 B 3.3.12-5 REVISION 55

Boron Dilution Alarm System (BOAS)

B 3.3.12 BASES SURVEILLANCE SR 3.3.12.2 REQUIREMENTS (continued) A CHANNEL FUNCTIONAL TEST is performed every 92 days to ensure that the BOAS is capable of properly alerting the operator to a boron dilution event. Internal excore startup channel test circuitry is used to feed preadjusted test signals into the excore startup channel to verify the proper neutron flux indication is received at the BOAS.

The Frequency is based on operating experience with regard to channel OPERABILITY and drift. which demonstrates that failure of more than one channel in any 92 day Frequency is a rare event. This SR is modified by a Note that states the CHANNEL FUNCTIONAL TEST is not required to be performed until 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months after neutron flux is within the startup range. The 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months is based on allowing a reasonable time to perform the testing following a plant shutdown. Neutron flux is defined to be within the startup range following a reactor shutdown when reactor power is 2E-6% NRTP or less.

The CHANNEL FUNCTIONAL TEST of the BOAS consists of online tests including verification of the control room alarm.

SR 3.3.12.3 SR 3.3.12.3 is the performance of a CHANNEL CALIBRATION. A CHANNEL CALIBRATION is performed every 18 months. The Surveillance is a complete check and readjustment of the excore startup channel from the input through to the BOAS.

The Surveillance verifies that the channel responds to a measured parameter within the necessary range and accuracy.

CHANNEL CALIBRATION leaves the channel adjusted to account for instrument drift between successive calibrations to ensure that the channel remains operational.

This SR is modified by a Note to indicate that it is not necessary to test the detector. because generating a meaningful test signal is difficult: the detectors are of simple construction. and any failures in the detectors will be apparent as a change in channel output.

REFERENCES 1. UFSAR. Chapter 7 and Chapter 15.

PALO VERDE UNITS 1.2.3 B 3.3.12-6 REVISION 6

Pressurizer Vents B 3,4,12 BASES LCO A vent path is flow capability from the pressurizer to the (continued) ROT or from the pressurizer to containment atmosphere, Loss of any single valve in the pressurizer vent system will cause two flow paths to become inoperable, A pressurizer vent path is required to depressurize the RCS in a SGTR design basis event which assumes LOP and APSS unavailable, APPLICABILITY In MODES 1, 2, 3, and MODE 4 with RCS pressure ~ 385 psia the four pressurizer vent paths are required to be OPERABLE, The safety analysis for the SGTR with LOP and a Single Failure (loss of APSS) credits a pressurizer vent path to reduce RCS pressure, In MODES 1, 2, 3, and MODE 4 with RCS pressure ~ 385 psia the SGs are the primary means of heat removal in the RCS, until shutdown cooling can be initiated, In MODES 1, 2, 3, and MODE 4 with RCS pressure ~ 385 psia, assuming the APSS is not available, the pressurizer vent paths are the credited means to depressurize the RCS to Shutdown Cooling System entry conditions, Further depressurization into MODE 5 requires use of the pressurizer vent paths, In MODE 5 with the reactor vessel head in place, temperature requirements of MODE 5 << 210°F) ensure the RCS remains depressurized, In MODE 6 the RCS is depressurized, ACTIONS A,l If two or three pressurizer vent paths are inoperable, they must be restored to OPERABLE status, Loss of any single valve in the pressurizer vent system will cause two flow paths to become inoperable, Any vent path that provides flow capability from the pressurizer to the ROT or to the containment atmosphere, independent of which train is powering the valves in the flow path, can be considered an operable vent path, The Completion Time of 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months is reasonable because there is at least one pressurizer vent path that remains OPERABLE, (continued)

PALO VERDE UNITS 1,2,3 B 3,4,12-3 REVISION 48

Pressurizer Vents B 3.4.12 BASES B.1 If all pressurizer vent paths are inoperable. then restore at least one pressurizer vent path to OPERABLE status. The Completion Time of 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months is reasonable to allow time to correct the situation. yet emphasize the importance of restoring at least one pressurizer vent path. If at least one pressurizer vent path is not restored to OPERABLE within the Completion Time. then Action C is entered.

C.1 If the required Actions. A and B. cannot be met within the associated Completion Times. the plant must be brought to a MODE in which the requirement does not apply. To achieve this status. the plant must be brought to at least MODE 3 within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months . and to MODE 4 with RCS pressure < 385 psia within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The allowed Completion Times are reasonable. based on operating experience. to reach the required plant conditions from full power conditions in an orderly manner without challenging plant systems.

SURVEILLANCE SR 3.4.12.1 REQUIREMENTS SR 3.4.12.1 requires complete cycling of each pressurizer vent path valve. The vent valves must be cycled from the control room to demonstrate their operability. Pressurizer vent path valve cycling demonstrates its function. The frequency of 18 months is based on a typical refueling cycle and industry accepted practice. This surveillance test must be performed in Mode 5 or Mode 6. In any Mode. partial surveillance tests can be performed for post-maintenance testing under site procedural controls that ensure the valve being tested is isolated from RCS pressure.

SR 3.4.12.2 SR 3.4.12.2 requires verification of flow through each pressurizer vent path. Verification of pressurizer vent path flow demonstrates its function. The frequency of 18 months is based on a typical refueling cycle and industry accepted practice. This surveillance test must be performed in Mode 5 or Mode 6.

(continued)

PALO VERDE UNITS 1.2.3 B 3.4.12-4 REVISION 55

LTOP System B 3.4.13 B 3.4 REACTOR COOLANT SYSTEM (RCS)

B 3.4.13 Low Temperature Overpressure Protection (LTOP) System BASES BACKGROUND The LTOP System controls RCS pressure at low temperatures so the integrity of the Reactor Coolant Pressure Boundary (RCPB) is not compromised by violating the Pressure and Temperature (PIT) limits of 10 CFR 50. Appendix G (Ref. 1).

The reactor vessel is the limiting RCPB component for demonstrating such protection. LCO 3.4.3. "RCS Pressure and Temperature (PIT) Limits," provides the allowable combinations for operational pressure and temperature during cool down , shutdown, and heatup to keep from violating the Reference 1 requirements during the LTOP MODES.

The reactor vessel material is less tough at low temperatures than at normal operating temperatures. As the vessel neutron exposure accumulates. the material toughness decreases and becomes less resistant to pressure stress at low temperatures (Ref. 2). RCS pressure, therefore. is maintained low at low temperatures and is increased only as temperature is increased.

The potential for vessel overpressurization is most acute when the RCS is water solid. occurring only while shutdown; a pressure fluctuation can occur more quickly than an operator can react to relieve the condition. Exceeding the RCS PIT limits by a significant amount could cause brittle cracking of the reactor vessel. LCO 3.4.3 requires administrative control of RCS pressure and temperature during heatup and cool down to prevent exceeding the PIT limits.

This LCO provides RCS overpressure protection by having adequate pressure relief capacity. The pressure relief capacity requires either two OPERABLE redundant Shutdown Cooling System suction line relief valves or the RCS depressurized and an RCS vent of sufficient size. One Shutdown Cooling System suction line relief valve or the RCS vent is the overpressure protection device that acts to terminate an increasing pressure event.

(continued)

PALO VERDE UNITS 1,2.3 B 3.4.13-1 REVISION 0

LTOP System B 3.4.13 BASES BACKGROUND The LTOP System for pressure relief consists of two Shutdown (continued) Cooling System suction line relief valves or an RCS vent of sufficient size. Two relief valves are required for redundancy. One Shutdown Cooling System suction line relief valve has adequate relieving capability to prevent overpressurization for the required coolant input capability.

Shutdown Cooling System Suction Line Relief Valve Requirements As designed for the LTOP System. each Shutdown Cooling System suction line relief valve is designed to lift and relieve RCS pressure if RCS pressure approaches the Shutdown Cooling System suction line relief valve lift setpoint.

Each Shutdown Cooling System suction line relief valve is designed to protect the reactor vessel given a single failure in addition to a failure that initiated the pressure transient. No single failure of a Shutdown Cooling System suction line relief valve isolation valve (SI-651. 652. 653.

or 654) will prevent one Shutdown Cooling System suction line relief valve from performing its intended function (Ref. 7).

The OPERABILITY of two Shutdown Cooling System suction line relief valves. while maintaining the limits imposed on the RCS heatup and coo1down rates. ensures that the RCS will be protected from analyzed pressure transients. Either Shutdown Cooling System suction line relief valve provides overpressure protection for the RCS due to the most limiting transients initiated by a single operator or equipment failure.

a. The start of an idle RCP with secondary water temperature of the SG ~ 100°F above RCS cold leg temperatures

b. An inadvertent SIAS with two HPSI pumps injecting into a water solid RCS. three charging pumps injecting. and letdown isolated.

These events are the most limiting energy and mass addition transients. respectively. when the RCS is at low temperatures (Refs. 7 and 8).

(continued)

PALO VERDE UNITS 1.2.3 B 3.4.13-2 REVISION 55

LTOP System B 3.4.13 BASES BACKGROUND Shutdown Cooling S~stem Suction Line Relief Valve (continued) Requlrements (contlnued)

When a Shutdown Cooling System suction line relief valve lifts due to an increasing pressure transient. the release of coolant causes the pressure increase to slow and reverse.

As the Shutdown Cooling System suction line relief valve releases coolant. the system pressure decreases until valve reseat pressure is reached and the Shutdown Cooling system suction line relief valve closes.

At low temperatures with the Shutdown Cooling System suction line relief valves aligned to the RCS. it is necessary to restrict heatup and cooldown rates to assure that P-T limits are not exceeded. These P-T limits are usually applicable to a finite time period such as one cycle. 5 EFPY. etc. and are based upon irradiation damage prediction by the end of the period. Accordingly. each time P-T limits change. the LTOP System needs to be reanalyzed and modified. if necessary. to continue its function.

Once the RCS is depressurized. a vent exposed to the containment atmosphere will maintain the RCS at containment ambient pressure in an RCS overpressure transient. if the relieving requirements of the transient do not exceed the capabilities of the vent. Thus. the vent path must be capable of relieving the flow resulting from the limiting LTOP mass or heat input transient and maintaining pressure below the PIT limits. The required vent capacity may be provided by one or more vent paths.

For an RCS vent to meet the specified flow capacity. it requires removing all pressurizer safety valves. or similarly establishing a vent by opening the pressurizer manway (Ref. 10). The vent path(s) must be above the level of reactor coolant. so as not to drain the RCS when open.

(continued)

PALO VERDE UNITS 1.2.3 B 3.4.13-3 REVISION 55

LTOP System B 3.4.13 BASES APPLICABLE Safety analyses (Ref. 3) demonstrate that the reactor vessel SAFETY ANALYSES is adequately protected against exceeding the Reference 1 PIT limits during shutdown. In MODES 1, 2, and 3, and in MODE 4 with any RCS cold leg temperature greater than the LTOP enable temperature specified in the PTLR, the pressurizer safety valves prevent RCS pressure from exceeding the Reference 1 limits. At the LTOP enable temperature specified in the PTLR and below, overpressure prevention falls to the OPERABLE Shutdown Cooling System suction line relief valves or to a depressurized RCS and a sufficient sized RCS vent. Each of these means has a limited overpressure relief capability.

The actual temperature at which the pressure in the PIT limit curve falls below the pressurizer safety valve setpoint increases as the reactor vessel material toughness decreases due to neutron embrittlement. Each time the PIT limit curves are revised, the LTOP System will be re-evaluated to ensure its functional requirements can still be satisfied using the Shutdown Cooling System suction line relief valve method or the depressurized and vented RCS condition.

Reference 3 contains the acceptance limits that satisfy the LTOP requirements. Any change to the RCS must be evaluated against these analyses to determine the impact of the change on the LTOP acceptance limits.

Transients that are capable of overpressurizing the RCS are categorized as either mass or heat input transients, examples of which follow:

Mass Input Type Transients

a. Inadvertent safety injection; or

b. Charging/letdown flow mismatch.

Heat Input Type Transients

a. Inadvertent actuation of pressurizer heaters;

b. Loss of shutdown cooling (SOC); or

c. Reactor coolant pump (RCP) startup with temperature asymmetry within the RCS or between the RCS and steam generators.

(continued)

PALO VERDE UNITS 1,2,3 B 3.4.13-4 REVISION 52

LTOP System B 3.4.13 BASES APPLICABLE References 3, 7 and 8 analyses demonstrate that either SAFETY ANALYSES one Shutdown Cooling System suction line relief valve or the (continued) RCS vent can maintain RCS pressure below limits for the two most limiting analyzed events:

a. The start of an idle RCP with secondary water temperature of the SG s 100°F above RCS cold leg temperatures.

b. An inadvertent SIAS with two HPSI pumps injecting into a water solid RCS, three charging pumps injecting, and letdown isolated.

Fracture mechanics analyses established the temperature of LTOP Applicability at less than or equal to the LTOP enable temperature specified in the PTLR. Above these temperatures, the pressurizer safety valves provide the reactor vessel pressure protection. The vessel materials were assumed to have a neutron irradiation accumulation equal to the effective full power years of operation specified in the PTLR.

The consequences of a small break Loss Of Coolant Accident (LOCA) in LTOP MODE 4 conform to 10 CFR 50.46 and 10 CFR 50, Appendix K (Refs. 4 and 5).

The fracture mechanics analyses show that the vessel is protected when the Shutdown Cooling System suction line relief valves are set to open at or below 467 psig. The setpoint is derived by modeling the performance of the LTOP System, assuming the limiting allowed LTOP transient. The Shutdown Cooling System suction line relief valves setpoints at or below the derived limit ensure the Reference 1 limits will be met.

The Shutdown Cooling System suction line relief valves setpoints will be re-evaluated for compliance when the revised PIT limits conflict with the LTOP analysis limits.

The PIT limits are periodically modified as the reactor vessel material toughness decreases due to embrittlement caused by neutron irradiation. Revised PIT limits are determined using neutron fluence projections and the results of examinations of the reactor vessel material irradiation surveillance specimens. The Bases for LCO 3.4.3, "RCS Pressure and Temperature (PIT) Limits," discuss these examinations.

(continued)

PALO VERDE UNITS 1,2,3 B 3.4.13-5 REVISION 55

LTOP System B 3.4.13 BASES APPLICABLE The Shutdown Cooling System suction line relief valves are SAFETY ANALYSES considered active components. Thus. the failure of one (continued) Shutdown Cooling System suction line relief valve represents the worst case. single active failure.

RCS Vent Performance With the RCS depressurized. analyses show a vent size of 16 square inches is capable of mitigating the limiting allowed LTOP overpressure transient. In that event. this size vent maintains RCS pressure less than the maximum RCS pressure on the PIT limit curve.

The RCS vent size will also be re-evaluated for compliance each time the PIT limit curves are revised based on the results of the vessel material surveillance.

The RCS vent is passive and is not subject to active failure.

LTOP System satisfies Criterion 2 of 10 CFR 50.36 (c)(2)(ii) .

LCO This LCO is required to ensure that the LTOP System is OPERABLE. The LTOP System is OPERABLE when the pressure relief capabilities are OPERABLE. Violation of this LCO could lead to the loss of low temperature overpressure mitigation and violation of the Reference 1 limits as a result of an operational transient.

The elements of the LCO that provide overpressure mitigation through pressure relief are:

a. Two OPERABLE Shutdown Cooling System suction line relief valves; or

b. The depressurized RCS and an RCS vent.

A Shutdown Cooling System suction line relief valve is OPERABLE for LTOP when its isolation valves are open.

its lift setpoint is set at 467 psig or less and testing has proven its ability to open at that setpoint.

An RCS vent is OPERABLE when open with an area 2 16 square inches. For an RCS vent to meet the specified flow capacity.

it requires removing all pressurizer safety valves. or similarly establishing a vent by opening the pressurizer manway (Ref. 10). The vent path(s) must be above the level of reactor coolant. so as not to drain the RCS when open.

(continued)

PALO VERDE UNITS 1.2.3 B 3.4.13-6 REVISION 55

LTOP System B 3.4.13 BASES ACTIONS B.1 (continued)

(continued)

Cooling System suction line relief valve failures without exposure to a lengthy period with only one Shutdown Cooling System suction line relief valve OPERABLE to protect against overpressure events.

C.1 If two required Shutdown Cooling System suction line relief valves are inoperable, or if a Required Action and the associated Completion Time of Condition A or B are not met, the RCS must be depressurized and a vent established within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months . The vent must be sized at least 16 square inches to ensure the flow capacity is greater than that required for the worst case mass input transient reasonable during the applicable MODES. This action protects the RCPB from a low temperature overpressure event and a possible brittle failure of the reactor vessel. For personnel safety considerations, the RCS cold leg temperature must be reduced to less than 200°F prior to venting.

The Completion Time of 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months to depressurize and vent the RCS is based on the time required to place the plant in this condition and the relatively low probability of an overpressure event during this time period due to increased operator awareness of administrative control requirements.

SURVEILLANCE SR 3.4.13.1 and 3.4.13.2 REQUIREMENTS SR 3.4.13.1 and SR 3.4.13.2 require verifying that the RCS vent is open 16 square inches or that the Shutdown Cooling System suction line relief valves be aligned to provide overpressure protection for the RCS is proven OPERABLE by verifying its open pathway condition either:

Shutdown Cooling System suction/line relief valves

a. Once every 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months for a valve that is unlocked, not sealed, or otherwise not secured open in the vent pathway, or

b. Once every 31 days for a valve that is locked, sealed, or otherwise secured open in the vent pathway.

RCS Vent

a. Once every 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months for a vent pathway that is unlocked, not sealed, or otherwise not secured open.

(continued)

PALO VERDE UNITS 1,2,3 B 3.4.13-9 REVISION 42

LTOP System B 3.4.13 BASES SURVEILLANCE SR 3.4.13.1 and 3.4.13.2 (continued)

REQUIREMENTS

b. Once every 31 days for a vent pathway that is locked, sealed, or otherwise secured open.

For an RCS vent to meet the specified flow capacity, it requires removing all pressurizer safety valves, or similarly establishing a vent by opening the pressurizer manway (Ref. 10). The vent path(s) must be above the level of reactor coolant, so as not to drain the RCS when open.

The passive vent arrangement must only be open (vent pathway exists) to be OPERABLE. These Surveillances need only be performed if the vent or the Shutdown Cooling System suction line relief valves are being used to satisfy the requirements of this LCO. The Frequencies consider operating experience with mispositioning of unlocked and locked pathway vent valves, and passive pathway obstructions.

SR 3.4.13.3 SRs are specified in the Inservice Testing Program.

Shutdown Cooling System suction line relief valves are to be tested in accordance with the requirements of the ASME OM Code (Ref. 9), which provides the activities and the Frequency necessary to satisfy the SRs. The Shutdown Cooling System suction line relief valve set point is 467 psig.

REFERENCES 1. 10 CFR 50, Appendix G.

2. Generic Letter 88-11.

3. UFSAR, Section 15.

4. 10 CFR 50.46.

5. 10 CFR 50, Appendix K.

6. Generic Letter 90-06.

7. UFSAR, Section 5.2.

(continued)

PALO VERDE UNITS 1,2,3 B 3.4.13-10 REVISION 55

LTOP System B 3.4.13 BASES REFERENCES 8. N001-0601-00404. "Palo Verde Nuclear Generating Station Units 1, 2, and 3 LTOP Evaluation"

9. ASME Code for Operation and Maintenance of Nuclear Power Plants.

10. 13-COO-93-016, Sensitivity Study on Pressurizer Vent Paths vs. Days Post Shutdown.

PALO VERDE UNITS 1,2,3 B 3.4.13-11 REVISION 55

This page intentionally blank RWT B 3.5.5 BASES BACKGROUND The table below provides the required RWT level at selected (continued) ReS average temperature values. corresponding to Figure 3.5.5-1. The RWT volume is the total volume of water in the RWT above the vortex breaker. This volume includes the volumes required to be transferred. as discussed below. an allowance for instrument uncertainty. and the volume that will remain in the RWT after the switch over to the recirculation mode.

RWT Required Level at ReS Temperatures RCS Temperature (OF) RWT Required Level RWT Volume

average Indicated (Gall ons)

(%)

210 8l. 2 611.000 250 8l.4 613.000 300 8l.8 615.000 350 82.1 618.000 400 82.5 621.000 450 83.0 624.000 500 83.5 628.000 565 84.3 634.000 600 84.3 634.000

The volumes include instrument uncertainty and have been rounded up or down to the nearest 1.000 gallons.

(continued)

PALO VERDE UNITS 1.2.3 B 3.5.5-3 REVISION 55

RWT B 3.5.5 BASES APPLICABLE During accident conditions. the RWT provides a source of SAFETY ANALYSES borated water to the HPSI. LPSI and containment spray pumps.

As such. it provides containment cooling and depressurization. core cooling. and replacement inventory and is a source of negative reactivity for reactor shutdown (Ref. 1). The design basis transients and applicable safety analyses concerning each of these systems are discussed in the Applicable Safety Analyses section of Bases B 3.5.3.

"ECCS - Operating." and B 3.6.6. "Containment Spray." These analyses are used to assess changes to the RWT in order to evaluate their effects in relation to the acceptance limits.

The level limit of Figure 3.5.5-1 for the ESF function is based on the largest of the following four factors:

a. A volume of borated water must be transferred to containment via the ESF pumps prior to reaching a low level switchover to the containment sump for recirculation. This ESF Reserve Volume ensures that the ESF pump suction will not be aligned to the containment sump until the point at which 75% of the minimum design flow of one HPSI pump is capable of meeting or exceeding the decay heat boil-off rate.

b. A volume of borated water must be transferred to the RCS and containment for flooding of sump strainers to prevent vortexing and to ensure adequate net positive suction head to support continued ESF pump operation after the switchover to recirculation occurs.

c. A volume of borated water must be available for Containment Spray System operation as credited in the containment pressure and temperature analyses.

d. A volume of borated water is needed during ECCS functions to ensure shut down margin (SDM) is maintained. The volume required is similar to that needed for the charging system function of compensating for contraction of the RCS coolant during plant cooldown. The volume required will vary depending upon the event and is bounded by the volume (continued)

PALO VERDE UNITS 1.2.3 B 3.5.5-4 REVISION 54

CST B 3.7.6 BASES APPLICABILITY In MODES 1, 2, and 3, and in MODE 4, when steam generator is being relied upon for heat removal, the CST is required to be OPERABLE.

In MODES 5 and 6, the CST is not required because the AFW System is not required.

ACTIONS A.l and A.2 If the CST level is not within the limit, the OPERABILITY of the backup water supply (RMWT) must be verified within 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months .

OPERABILITY of the RMWT must include initial alignment and verification of the OPERABILITY of flow paths from the RMWT to the AFW pumps, and availability of sufficient total water inventory using the combined CST and RMWT inventories to satisfy the requirements of long-term cooling event which includes both LOCA Long-Term Cooling and Reactor Systems Branch Technical Position 5-1 (RSB 5-1). The CST level must be returned to OPERABLE status within 7 days, as the RMWT may be performing this function in addition to its normal functions. The 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months Completion Time is reasonable, based on operating experience, to verify the OPERABILITY of the RMWT. The 7 day Completion Time is reasonable, based on an OPERABLE RMWT being available, and the low probability of an event requiring the use of the water from the CST occurring during this period.

(continued)

PALO VERDE UNITS 1,2,3 B 3.7.6-3 REVISION 55

CST B 3.7.6 BASES ACTIONS B.1 and B.2 (continued)

If the CST cannot be restored to OPERABLE status within the associated Completion Time. the unit must be placed in a MODE in which the LCO does not apply. To achieve this status. the unit must be placed in at least MODE 3 within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months . and in MODE 4. without reliance on steam generator for heat removal. within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . The allowed Completion Times are reasonable. based on operating experience. to reach the required unit conditions from full power conditions in an orderly manner and without challenging unit systems.

SURVEILLANCE SR 3.7.6.1 REQUIREMENTS This SR verifies that the CST contains the required volume of cooling water. (This level ~ 29.5 ft (300.000 gallons)).

The 12 hour1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months Frequency is based on operating experience. and the need for operator awareness of unit evolutions that may affect the CST inventory between checks. The 12 hour1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months Frequency is considered adequate in view of other indications in the control room. including alarms. to alert the operator to abnormal CST level deviations.

REFERENCES 1. UFSAR. Section 9.2.6.

2. UFSAR. Chapter 6.

3. UFSAR. Chapter 15.

4. NRC Standard Review Plan Branch Technical Pos iti on (BTP) RSB 5-1.

PALO VERDE UNITS 1.2.3 B 3.7.6-4 REVISION 54

CREFS B 3.7.11 BASES APPLICABLE The CREFS provides airborne radiological protection for CRE SAFETY ANALYSES occupants. as demonstrated by the eRE occupant dose (continued) analyses for the most limiting design basis accident fission product release presented in the UFSAR. Chapter 15 (Ref. 2).

The CREFS provides protection from smoke and hazardous chemicals to the CRE occupants; however. hazardous chemicals are not stored or used onsite in quantities sufficient to necessitate CRE protection. as required by Regulatory Guide 1.78. In addition. nearby industrial.

military, and transportation facilities present no hazard to the operation of PVNGS. and there are no site-related design basis events due to accidents at these facilities (Ref. 1 and Ref. 3). The evaluation of a smoke challenge demonstrates that it will not result in the inability of the CRE occupants to control the reactor either from the control room or from the remote shutdown panel (Ref. 4).

The worst case single active failure of a component of the CREFS. assuming a loss of off site power. does not impair the ability of the system to perform its design function.

The CREFS satisfies Criterion 3 of 10 CFR 50.36 (c)(2)(ii).

LCO Two independent and redundant trains of the CREFS are required to be OPERABLE to ensure that at least one is available if a single active failure disables the other train. Total system failure. such as from a loss of both ventilation trains or from an inoperable CRE boundary. could result in exceeding a dose of 5 rem whole body or its equivalent to any part of the body to the CRE occupants in the event of a large radioactive release.

Each CREFS train is considered OPERABLE when the individual components necessary to limit CRE occupant exposure are OPERABLE. A CREFS train is considered OPERABLE when the associated:

a. Fan is OPERABLE;

b. HEPA filters and charcoal adsorber are not excessively restricting flow. and are capable of performing their filtration functions; and

c. Ductwork. valves. and dampers are OPERABLE. and air circulation can be maintained.

(continued)

PALO VERDE UNITS 1.2.3 B 3.7.11-3 REVISION 51

CREFS B 3.7.11 BASES LCO In order for the CREFS trains to be considered OPERABLE, (continued) the CRE boundary must be maintained such that the CRE occupant dose from a large radioactive release does not exceed the calculated dose in the licensing basis consequence analyses for DBAs, and that the CRE occupants are protected from hazardous chemicals and smoke.

The LCO is modified by a Note allowing the CRE boundary to be opened intermittently under administrative controls.

This Note only applies to openings in the CRE boundary that can be rapidly restored to the design condition such as doors, hatches, floor plugs, and access panels. For entry and exit through doors, the administrative control of the opening is performed by the person(s) entering or exiting the area. For other openings, these controls should be proceduralized and consist of stationing a dedicated individual at the opening who is in continuous communication with the operators in the CRE. This individual will have a method to rapidly close the opening and to restore the CRE boundary integrity to the design condition when a need for CRE isolation is indicated.

APPLICABILITY In MODES 1, 2, 3, 4, 5, 6, and during movement of irradiated fuel assemblies, the CREFS must be OPERABLE to ensure that the CRE will remain habitable during and following a DBA.

Movement of spent fuel casks containing irradiated fuel assemblies is not within the scope of the Applicability of this technical specification. The movement of dry casks containing irradiated fuel assemblies will be done with a single-failure-proof handling system and with transport equipment that would prevent any credible accident that could result in a release of radioactivity.

During movement of irradiated fuel assemblies, the CREFS must be OPERABLE to cope with the release from a fuel handling accident.

(continued)

PALO VERDE UNITS 1,2,3 B 3.7.11-4 REVISION 55

CREFS B 3.7.11 BASES ACTIONS A.1 With one CREFS train inoperable. for reasons other than an inoperable CRE boundary. action must be taken to restore OPERABLE status within 7 days. In this Condition. the remaining OPERABLE CREFS train is adequate to perform the CRE occupant protection function. However. the overall reliability is reduced because a failure in the OPERABLE CREFS train could result in loss of CREFS function. The 7 day Completion Time is based on the low probability of a DBA occurring during this time period. and the ability of the remaining train to provide the required capability.

B.1. B.2. and B3.3 If the unfiltered air leakage of potentially contaminated air past the CRE boundary and into the CRE can result in CRE occupant radiological dose greater than the calculated dose of the licensing basis analyses of DBA consequences (allowed to be up to 5 rem whole body or its equivalent to any part of the body) or inadequate protection of CRE occupants from hazardous chemicals or smoke. the CRE boundary is inoperable.

Actions must be taken to restore an OPERABE CRE boundary within 90 days.

During the period that the CRE boundary is considered inoperable. action must be initiated to implement mitigating actions to lessen the effect on CRE occupants from the potential hazards of radiological or chemical event or a challenge from smoke. Actions must be taken within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months to verify that in the event of a DBA. the mitigating actions will ensure that CRE occupant radiological exposures will not exceed the calculated dose of the licensing basis analyses of DBA consequences. and that CRE occupants are protected from hazardous chemicals and smoke. These mitigating actions (i .e .. actions that are taken to offset the consequences of the inoperable CRE boundary) should be preplanned for implementation upon entry into the condition. regardless of whether entry is intentional or unintentional. The 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time is reasonable based upon the low probability of a DBA occurring during this time period. and the use of mitigating actions. The 90 day Completion Time is reasonable based on the determination that the mitigating actions will ensure protection of CRE occupants within analyzed limits while limiting the probability that CRE occupants will have to implement protective measures that may adversely affect (continued)

PALO VERDE UNITS 1.2.3 B 3.7.11-5 REVISION 50

CREFS B 3.7.11 BASES ACTIONS B.1, B.2, and B.3 (continued) their ability to control the reactor and maintain it in a safe shutdown condition in the event of a DBA. In addition, the 90 day Completion Time is a reasonable time to diagnose, plan and possibly repair and test most problems with the CRE boundary.

C.1 and C.2 In MODE 1, 2, 3, or 4, if the inoperable CREFS or the CRE boundary cannot be restored to OPERABLE status within the required Completion Time, the unit must be placed in a MODE that minimizes the accident risk. To achieve this status, the unit must be placed in at least MODE 3 within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months and in MODE 5 within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months . The allowed Completion Times are reasonable, based on operating experience, to reach the required unit conditions from full power conditions in an orderly manner and without challenging unit systems.

D.1 In MODE 5 or 6, if Required Action A.1 cannot be completed within the required Completion Time, the OPERABLE CREFS train must be immediately placed in the essential filtration mode (e.g., emergency or pressurization mode of operation - fan running, valves/dampers aligned to the post-CREFAS mode).

This action ensures that the remaining train is OPERABLE, that no failures preventing automatic actuation will occur, and that any active failure will be readily detected.

E.1 and E.2 During movement of irradiated fuel assemblies, if required Action A.1 cannot be completed within the required Completion Time, the OPERABLE CREFS train must be immediately placed in the essential filtration mode (e.g., emergency or pressurization mode of operation - fan running, valves/dampers aligned to the post-CREFAS mode) or movement of irradiated fuel assemblies must be suspended immediately.

The first action ensures that the remaining train is OPERABLE, that no undetected failures preventing system operation will occur, and that any active failure will be readily detected.

(continued)

PALO VERDE UNITS 1,2,3 B 3.7.11-6 REVISION 55

CREATCS B 3.7.12 BASES (continued)

ACTIONS B.1 and B.2 (continued)

In MODE 1, 2, 3, or 4, when Required Action A.1 cannot be completed within the required Completion Time, the unit must be placed in a MODE that minimizes the accident risk. To achieve this status, the unit must be placed in at least MODE 3 within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months , and in MODE 5 within 36 hours4.166667e-4 days 0.01 hours 5.952381e-5 weeks 1.3698e-5 months .

The allowed Completion Times are reasonable, based on operating experience, to reach the required unit conditions from full power conditions in an orderly manner and without challenging unit systems.

C.1 In MODE 5 or 6, if Required Action A.1 cannot be completed within the required Completion Time, the OPERABLE CREATCS train must be placed in operation immediately (including supporting systems). This action ensures that the remaining train is OPERABLE, that no failures preventing automatic actuation will occur, and that any active failure will be readily detected.

0.1 and 0.2 During movement of irradiated fuel assemblies, if Required Action A.1 cannot be completed within the Required Completion Time, the OPERABLE CREATCS train must be placed in operation immediately (including supporting systems) or movement of irradiated fuel assemblies must be suspended immediately. The first action ensures that the remaining train is OPERABLE, that no undetected failures preventing system operation will occur, and that any active failure will be readily detected.

If the system is not immediately placed in operation, this action requires suspension of the movement of irradiated fuel assemblies in order to minimize the risk of a release of radioactivity that might require isolation of the control room. This does not preclude the movement of fuel to a safe position.

E.1 and E.2 In MODE 5 or 6, or during movement of irradiated fuel assemblies with two CREATCS trains inoperable, action must be taken immediately to suspend activities that could result in a release of radioactivity that might require isolation of the control room. This places the unit in a condition that minimizes the accident risk. This does not preclude the movement of fuel to a safe position.

(continued)

PALO VERDE UNITS 1,2,3 B 3.7.12-3 REVISION 55

CREATCS B 3.7.12 BASES (continued)

ACTIONS F.l (continued)

If both CREATCS trains are inoperable in MODE 1, 2, 3, or 4, the CREATCS may not be capable of performing the intended function and the unit is in a condition outside the accident analysis. Therefore, LCO 3.0.3 must be entered immediately SURVEILLANCE SR 3.7.12.1 REQUIREMENTS This SR verifies that the heat removal capability of the system is sufficient to meet design requirements. This SR consists of a combination of testing and calculations. An 18 month Frequency is appropriate, since significant degradation of the CREATCS is slow and is not expected over this time period.

REFERENCES l. UFSAR, Section 9.4.

PALO VERDE UNITS 1,2,3 B 3.7.12-4 REVISION 10

AC Sources - Operating 8 3.8.1 BASES SURVEILLANCE SR 3.B.1.17 REQUIREMENTS (continued) Demonstration of the test mode override ensures that the DG availability under accident conditions will not be compromised as the result of testing and the DG will automatically reset to ready-to-load operation if a LOCA actuation signal (e.g .. simulated SIAS) is received during operation in the test mode. Ready-to-load operation is defined as the DG running at rated speed and voltage. in standby operation (running unloaded) with the DG output breaker open. These provisions for automatic switchover are required by IEEE-30B (Ref. 11). paragraph 6.2.6(2) and Regulatory Guide 1.9 (Ref. 3). paragraph 2.2.13.

The requirement to automatically energize the emergency loads with offsite power is essentially identical to that of SR 3.B.1.12. The intent in the requirement associated with SR 3.B.1.17.b is to show that the emergency loading was not affected by the DG operation in test mode. In lieu of actual demonstration of connection and loading of loads. testing that adequately shows the capability of the emergency loads to perform these functions is acceptable.

This testing may include any series of sequential.

overlapping. or total steps so that the entire connection and loading sequence is verified.

The 1B month Frequency is consistent with the recommendations of Regulatory Guide 1.9 (Ref. 3). takes into consideration unit conditions required to perform the Surveillance. and is intended to be consistent with expected fuel cycle lengths.

This SR is modified by a Note. The reason for the Note is that performing the Surveillance would remove a required offsite circuit from service. perturb the electrical distribution system. and challenge safety systems. This restriction from normally performing the surveillance in MODE 1. 2. 3. and 4 is further amplified to allow portions of the surveillance to be performed for the purpose of reestablishing OPERABILITY (e.g .. post work testing following corrective maintenance. corrective modification.

deficient or incomplete surveillance testing. and other unanticipated OPERABILITY concerns) provided an assessment determines plant safety is maintained or enhanced. This assessment shall. as a minimum. consider the potential outcomes and transients associated with a failed partial surveillance. a successful partial surveillance. and a (continued)

PALO VERDE UNITS 1.2.3 B 3.B.1-43 REVISION 55

AC Sources - Operating B 3.8.1 BASES SURVEILLANCE SR 3.8.1.17 (continued)

REQUIREMENTS perturbation of the offsite or onsite system when they are tied together or operated independently for the partial surveillance; as well as the operator procedures available to cope with these outcomes. These shall be measured against the avoided risk of a plant shutdown and startup to determine that plant safety is maintained or enhanced when portions of the surveillance are performed in MODE 1. 2. 3.

or 4. Risk insights or deterministic methods may be used for this assessment.

SR 3.8.1.18 Under accident and loss of offsite power conditions loads are sequentially connected to the bus by the automatic load sequencer. The sequencing logic controls the permissive and starting signals to motor breakers to prevent overloading of the DGs due to high motor starting currents.

The 1 second load sequence time tolerance ensures that sufficient time exists for the DG to restore frequency and voltage prior to applying the next load and that safety analysis assumptions regarding ESF equipment time delays are not violated. FSAR. Chapter 8 (Ref. 2) provides a summary of the automatic loading of ESF buses.

The Frequency of 18 months is consistent with the recommendations of Regulatory Guide 1.9 (Ref. 3).

paragraph 2.2.4. takes into consideration unit conditions required to perform the Surveillance. and is intended to be consistent with expected fuel cycle lengths.

This SR is modified by a Note. The reason for the Note is that performing the Surveillance would remove a required offsite circuit from service. perturb the electrical distribution system. and challenge safety systems. This restriction from normally performing the surveillance in MODE 1. 2. 3. and 4 is further amplified to allow the surveillance to be performed for the purpose of reestablishing OPERABILITY (e.g .. post work testing following corrective maintenance. corrective modification.

deficient or incomplete surveillance testing. and other unanticipated OPERABILITY concerns) provided an assessment determines plant safety is maintained or enhanced. This assessment shall. as a minimum. consider the potential outcomes and transients associated with a failed surveillance. a successful surveillance. and a perturbation of the offsite or onsite system when they are tied together (continued)

PALO VERDE UNITS 1.2.3 B 3.8.1-44 REVISION 45

ML11287A033

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