Text

PVNGS, Units 1, 2, and 3 - Technical Specification Bases, Revision 63 - Replacement Pages and Insertion Instructions
	ML16154A580
Person / Time
Site:	Palo Verde
Issue date:	05/12/2016
From:	Stephenson C; Arizona Public Service Co
To:	; Office of Nuclear Reactor Regulation
Shared Package
ML16154A549	List: ML16154A548; ML16154A580; ML16154A581; ML16154A583; ML16154A614;
References
	102-07264-TNW/MDD
	Download: ML16154A580 (77)
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PVNGS Technical Specification Bases (TS Bases)

Revision 63 Replacement Pages and Insertion Instructions The following LDCRs are included in this change:

Technical Specification Bases Revision 63 includes the following changes:

LDCRs 10-B010 and 12-B001 reflect the removal of various post-accident sampling (PASS) valves. The removal of the components was authorized by License Amendment 136, dated September 28, 2001. 'Components have been removed over time based upon business considerations.

LDCR 14-B002 reflects installation of the inverter modification which includes swing inverters that can be credited as 'required' inverters, if available. Changes are reflected in the TS Bases descriptions of LCOs 3.8.7, Inverters- Operating, and 3.8.8, Inverters- Shutdown.

" LDCRs 14-B007 and 16-B001 reflect conforming changes to the TS Bases to implement License Amendment 197, dated February 19, 2016, that removed second Required Action Completion Times forTS LCOs 3.7.5, Auxiliary Feedwater System, 3.8.1, AC Sources- Operating, and 3.8.9, Distribution Systems- Operating.

LDCR 15-B002 added clarification to the TS Bases description of_the Applicable Safety Analyses section of TS 3. 7.17, Spent Fuel Assembly Storage. Specifically, a new sentence was added to indicate that core operating conditions, such as temperature and boron concentration, influence plutonium production which may increase discharged fuel reactivity. This clarification was an action from CRDR 4365817.

LDCR 15-B006 provides clarification of various TS Bases descriptions.

Specifically, the clarifications are the result of Condition Report 15-00354 which identified the need for the clarifications toTS Bases sections 3.1.2, 3.1.5, 3.2.2, 3.2.3 and 3.3.3 to improve reader understanding.

LDCR 15-B005 removes Conditions 1 and 2 from the TS Bases description of Surveillance Requirement (SR) 3.1.6.1, as the information is contained in Calculation 13-JC-SF-0202, Revision 7. The calculation serves as the source document for procedure guidance for how to perform SR 3.1.6.1.

This change is consistent with standard TS Bases protocols, in that the TS Bases typically describe the SR and why it is important, but not specifically how the test is to be performed.

LDCR 15-B004 restores the TS Bases description regarding spent fuel pool storage rack cell locations that are required to be vacant. This change was a corrective action from CRDR 4627526.

Insertion Instructions Remove Page: Insert New Page:

Cover Page Cover Page List of Effective Pages List of Effective Pages 1 12 through 91 Blank 1 I 2 through 9 I Blank Digitally signed by Stephenson, Carl Stephenson, J(Z05778)

DN: cn=Stephenson, Carl J(Z05778)

Carl J(Z05778)

Reason: I attest to the accuracy and integrity of this document Date: 2016.05.12 13:54:50 -07'00'

PVNGS Technical Specification Bases (TS Bases)

Revision 63 Replacement Pages and Insertion Instructions Insertion Instructions (continued)

Remove Page: Insert New Page:

B 3.0-5 I B 3.0-6 B 3.0-5 I B 3.0-6 B 3.0-19 I B ~0-20 B 3.0-19 I B 3.0-20 B 3.1.2-5 I B 3.1.2-6 B 3.1.2-5 I B 3.1.2-6 B 3.1.5-91 B 3.1.5-10 B 3.1.5-9 I B 3.1.5-10 B 3.1.6-1 I B 3.1.6-2 B 3.1.6-1 I B 3.1.6-2 through through B 3.1.6-51 B 3.1.6-6 B 3.1.6-5 I Blank B 3.2.2-5 I B 3.2.2-6 B 3.2.2-5 I B 3.2.2-6 B 3.2.2-7 I Blank B 3.2.2-7 I Blank B 3.2.3-5 I B 3.2.3-6 B 3.2.3-5 I B 3.2.3-6 B 3.2.3-7 I B 3.2.3-8 B 3.2.3-7 I B 3.2.3-8 B 3.3.3-3 I B 3.3.3-4 B 3.3.3-3 I B 3.3.3-4 B 3.3.10-9 I B 3.3.10-10 B 3.3.10-91B 3.3.10-10 B 3.7.5-5 I B 3.7.5-6 B 3.7.5-5 I B 3.7.5-6 B 3.7.5-7 I B 3.7.5-8 B 3.7.5-7 I B 3.7.5-8 B 3.7.5-9 I B 3.7.5-10 B 3.7.5-9 I B 3.7.5-10 B 3.7.5-111 Blank No Replacement Pages B 3.7.17-1 I B 3.7.17-2 B 3.7.17-1 IB 3.7.17-2 B 3.7.17-31 B 3.7.17-4 B 3.7.17-3 I B 3.7.17-4 B 3.8.1-9 I B 3.8.1 0 B 3.8.1-9 I B 3.8.10 through through B 3.8.1-21 I B 3.8.22 B 3.8.1-21 I B 3.8.22 B 3.8.7-11 B 3.8.7-2 B 3.8.7-1 I B 3.8.7-2 B 3.8.7-31 B 3.8.7-4 B 3.8.7-31 B 3.8.7-4 B 3.8.8-1 I B 3.8.8-2 B 3.8.8-1 I B 3.8.8-2 B 3.8.8-3 I B 3.8.8-4 B 3.8.8-3 I B 3.8.8-4 B 3.8.9-31 B 3.9.4 B 3.8.9-3 I B 3.9.4 through through B 3.8.9-111 Blank B 3.8.9-7 I B 3.8.9-8 No Replacement Pages for B 3.8.9-9 through B 3.8.9-11 2

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PVNGS Palo Verde Nuclear Generating Station Units 1, 2, and 3 Technical Specification Bases Revision 63 May 12, 2016

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This page intentionally blank LCD Applicability B 3.0 BASES LCD 3.0.3 The requirements of LCD 3.0.3 do not apply in other specified (continued) conditions of the Applicability (unless in MODE 1. 2. 3.

or 4) because the ACTIONS of i ndi vidual Specifications sufficiently define the remedial measures to be taken.

Exceptions to LCD 3.0.3 are provided in instances where requiring a unit shutdown. in accordance with LCD 3.0.3.

would not provide appropriate remedial measures for the associated condition of the unit. An example of this is in LCD 3.7.14. "Fuel Storage Pool Water Level." LCD 3.7.14 has an Applicability of "During movement of irradiated fuel assemblies in the fuel storage pool." Therefore. this LCD can be applicable in any or all MODES. If the LCD and the Required Actions of LCD 3.7.14 are not met while in MODE 1.

2. or 3. there is no safety benefit to be gained by placing the unit in a shutdown condition. The Required Action of LCD 3.7.14 of "Suspend movement of irradiated fuel assemblies in fuel storage pool" is the appropriate Required Action to complete in lieu of the actions of LCD 3.0.3. These exceptions are addressed in the individual Specifications.

LCD 3.0.4 LCO 3.0.4 establishes limitations on changes in MODES or other specified conditions in the Applicability when an LCD is not met. It allows placing the unit in a MODE or other specified condition stated in that Applicability (e.g .. the Applicability desired to be entered) when Unit conditions are such that the requirements of the LCO would not be met in accordance with LCD 3.0.4.a. LCD 3.0.4.b. or LCO 3.0.4.c.

LCD 3.0.4.a allows entry into a MODE or other specified condition in the Applicability with the LCO not met when the associated ACTIONS to be entered permit continued operation in the MODE or other specified condition in the Applicability for an unlimited period of time.

(continued)

PALO VERDE UNITS 1.2.3 B 3.0-5 REVISION 42

LCO Applicability B 3.0 BASES LCD 3.D.4 Compliance with Required Actions that permit continued (continued) operation of the unit for an unlimited period of time in a MODE or other specified condition provides an acceptable level of safety for continued operation. This is without regard to the status of the unit before or after the MODE change. Therefore. in such cases. entry into a MODE or other specified condition in the Applicability may be made in accordance with the provisions of the Required Actions.

LCO 3.0.4.b allows entry into a MODE or other specified condition in the Applicability with the LCD not met after performance of a risk assessment addressing inoperable systems and components. consideration of the results.

determination of the acceptability of entering the MODE or other specified condition in the Applicability, and establishment of risk management actions. if appropriate.

The risk assessment may use quantitative. qualitative. or blended approaches. and the risk assessment will be conducted using the plant program. procedures. and criteria in place to implement 10 CFR 50.65(a)(4). which requires that risk impacts of maintenance activities to be assessed and managed. The risk assessment. for the purposes of LCD 3.0.4 (b). must take into account all inoperable Technical Specification equipment regardless of whether the equipment is included in the normal 10 CFR 50.65(a)(4) risk assessment scope. The risk assessments will be conducted using the procedures and guidance endorsed by Regulatory Guide 1.160. Revision 3.

"Monitoring the Effectiveness of Maintenance at Nuclear Power Plants." Regulatory Guide 1.160 endorses the guidance in Section 11 of NUMARC 93-0l.Revision 4A.

"Industry Guideline for Monitoring the Effectiveness of Maintenance at Nuclear Power Plants.* These documents address general guidance for conduct of the risk assessment. quantitative and qualitative guidelines for establishing risk management actions. and example risk management actions. These include actions to plan and conduct other activities in a manner that controls overall risk. increased risk awareness by shift and management personnel. actions to reduce the duration of the condition. actions to minimize the magnitude of risk increases (establishment of backup success paths or compensatory measures). and determination that the proposed MODE change is acceptable. Consideration should also be given to the probability of completing restoration such that the requirements of the LCD would be met prior to the expiration of ACTIONS Completion Times that would require exiting the Applicability.

(continued)

PALO VERDE UNITS 1.2.3 B 3.0-6 REVISION 63

SR Applicability B 3.0 BASES SR 3.0.2 The provisions of SR 3.0.2 are not intended to be used (continued) repeatedly merely as an operational convenience to extend Surveillance intervals (other than those consistent with refueling intervals) or periodic Completion Time intervals beyond those specified.

SR 3.0.3 SR 3.0.3 establishes the flexibility to defer declaring affected equipment inoperable or an affected variable outside the specified limits when a Surveillance has not been completed within the specified Frequency. A delay period of up to 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months or up to the limit of the specified Frequency, whichever is greater. applies from the point in time that it is discovered that the Surveillance has not been performed in accordance with SR 3.0.2. and not at the time that the specified Frequency was not met. Reference Bases Section 3.0.2 for discussion and applicability of Frequency and 25% extension.

This delay period provides an adequate time to complete Surveillances that have been missed. This delay period permits the completion of a Surveillance before complying with Required Actions or other remedial measures that might preclude completion of the Surveillance.

The basis for this delay period includes consideration of unit conditions. adequate planning. availability of personnel. the time required to perform the Surveillance.

the safety significance of the delay in completing the required Surveillance. and the recognition that the most probable result of any particular Surveillance being performed is the verification of conformance with the requirements.

When a Surveillance with a Frequency based not on time intervals. but upon specified unit conditions. operating situations. or requirements of regulations (e.g., prior to entering MODE 1 after each fuel loading, or in accordance with 10 CFR 50. Appendix J. as modified by approved exemptions. etc.) is discovered to not have been performed when specified. SR 3.0.3 allows for the full delay period of up to the specified Frequency to perform the Surveillance. However. since there is not a time interval (continued)

PALO VERDE UNITS 1.2.3 B 3.0-19 REVISION 49

SR Applicability B 3.0 BASES SR 3.0.3 specified. the missed Surveillance should be performed at (continued) the first reasonable opportunity.

SR 3.0.3 provides a time limit for. and allowances for the performance of. Surveillances that become applicable as a consequence of MODE changes imposed by Required Actions.

Failure to comply with specified Frequencies for SRs is expected to be an infrequent occurrence. Use of the delay period established by SR 3.0.3 is a flexibility which is not intended to be used as an operational convenience to extend Surveillance intervals. While up to 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months or the limit of the specified Frequency is provided to perform the missed Surveillance. it is expected that the missed Surveillance will be performed at the first reasonable opportunity. The determination of the first reasonable opportunity should include consideration of the impact on plant risk (from delaying the Surveillance as well as any plant configuration changes required or shutting the plant down to perform the Surveillance) and impact on any analysis assumptions. in addition to unit conditions. planning. availability of personnel. and the time required to perform the Surveillance. This risk impact should be managed through the program in place to implement 10 CFR 50.65(a)(4) and its implementation guidance. NRC Regulatory Guide 1.160.

Revision 3. "Monitoring the Effectiveness of Maintenance at Nuclear Power Plants." This Regulatory Guide addresses consideration of temporary and aggregate risk impacts.

determination of risk management action thresholds. and risk management action up to and including plant shutdown. The missed Surveillance should be treated as an emergent condition as discussed in the Regulatory Guide. The risk evaluation may use quantitative. qualitative. or blended methods. The degree of depth and rigor of the evaluation should be commensurate with the importance of the component.

Missed Surveillances for important components should be analyzed quantitatively. If the results of the risk evaluation determine the risk increase is significant. this evaluation should be used to determine the safest course of action. All missed Surveillances will be placed in the licensee's Corrective Action Program.

(continued)

PALO VERDE UNITS 1.2.3 B 3.0-20 REVISION 63

SDM - Reactor Trip Breakers Closed B 3.1.2 BASES (continued)

APPLICABLE As (initial) Tcald decreases, the potential RCS cool down and SAFETY ANALYSES the resulting reactivity transient are less severe and, (continued) therefore, the required SHUTDOWN MARGIN also decreases.

Bel ow Tcald of about 350° F, the inadvertent deborati on event becomes limiting with respect to the applicable SHUTDOWN MARGIN requirements. Below 350°F, the specified SHUTDOWN MARGIN ensures that sufficient time for operator actions exists between the initial indication of the deboration and the total loss of shutdown margin. Accordingly, with the reactor trip breakers closed and the CEA drive system capable of CEA withdrawal, the SHUTDOWN MARGIN requirements are based upon these limiting conditions.

Additional events considered in establishing requirements on SHUTDOWN MARGIN that are not limiting with respect to the Specification limits are single CEA withdrawal and startup of an inactive reactor coolant pump.

The function of KN. 1 is to maintain sufficient subcriti cal ity to preclude inadvertent criticality following ejection of a single control element assembly (CEA). KN. 1 is a measure of the core's reactivity, considering a single malfunction resulting in the highest worth inserted CEA being ejected.

KN. 1 requirements vary with the amount of positive reactivity that would be introduced assuming the CEA with the highest inserted worth ejects from the core. The KN. 1 requirement ensures that a CEA ejection event while shutdown will not result in criticality. Above Tcold of 500°F, Doppler reactivity feedback is sufficient to preclude the need for a specific KN. 1 requirement.

The requirement prohibiting criticality due to shutdown group CEA movement is associated with the assumptions used in the analysis of uncontrolled CEA withdrawal from subcritical conditions. Due to the high differential reactivity worth of the shutdown CEA groups, the analysis assumes that the initial shutdown reactivity is such that the reactor will remain subcritical in the event of unexpected or uncontrolled shutdown group withdrawal.

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

(continued)

PALO VERDE UNITS 1,2,3 B 3.1.2-5 REVISION 63

SDM - Reactor Trip Breakers Closed 8 3.1.2 BASES LCO The MSLB (Ref. 2) and the boron dilution (Ref. 3) accidents are the most limiting analyses that establish the reactivity control requirements of the LCO. For MSLB accidents. if the LCO is violated. there is a potential to exceed 10 CFR 100.

"Reactor Site Criterion," limits (Ref. 4). For the boron dilution accident. if the LCO is violated. then the minimum required time assumed for operator action to terminate dilution may no longer be applicable.

SDM. KN_ 1 , and criticality due to Shutdown CEA withdrawal are core physics design conditions that can be ensured through CEA positioning (regulating and shutdown CEAs) and through the soluble boron concentration.

APPLICABILITY In MODES 3. 4. and 5 with the Reactor Trip Breakers Closed and the CEA Drive System is capable of CEA withdrawal. the SDM requirements are applicable to provide sufficient negative reactivity to meet the assumptions of the safety analyses discussed above. In MODES 1 and 2. SDM is ensured by complying with LCO 3.1.6. "Shutdown Control Element Assembly CCEA) Insertion Limits," and LCO 3.1.7. MODES 3. 4 and 5 with the Reactor Trip Breakers Open. SDM is addressed by LCO 3.1.1. "SHUTDOWN MARGIN CSDM) - Reactor Trip Breakers Open." In MODE 6, the shutdown reactivity requirements are given in LCO 3.9.1. "Boron Concentration."

ACTIONS A.1 If the SDM requirements are not met. boration must be initiated promptly. A Completion Time of 15 minutes is adequate for an operator to correctly align and start the required systems and components and/or vary CEA position.

It is assumed that boration will be continued until the SDM requirements are met.

In the determination of the required combination of boration flow rate and boron concentration. there is no unique requirement that must be satisfied. Since it is imperative to raise the boron concentration of the RCS as soon as possible. the boron concentration should be a highly (continued)

PALO VERDE UNITS 1.2.3 B 3.1.2-6 REVISION 43

CEA Alignment B3.1.5 BASES ACTIONS C.1 If a Required Action or associated Completion Time of Condition A or Condition B is not met. or if one or more regulating or shutdown CEAs are untrippable (immovable as a result of excessive friction or mechanical interference or known to be untrippable). the unit is required to be brought to MODE 3. By being brought to MODE 3. the unit is brought outside its MODE of applicability.

When a Required Action cannot be completed within the required Completion Time. a controlled shutdown should be commenced. The allowed Completion Time of 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months is reasonable. based on operating experience, for reaching MODE 3 from full power conditions in an orderly manner and without challenging plant systems. Reducing THERMAL POWER in accordance with the Abnormal Operating procedures ensures acceptable power distributions are maintained. The specified ramp rate is intended to ensure DNBR SAFDLs are not challenged.

If a full strength CEA is untrippable. it is not available for reactivity insertion during a reactor trip. With an untrippable CEA, meeting the insertion limits of LCO 3.1.6.

"Shutdown Control Element Assembly (CEA) Insertion Limits,"

and LCO 3.1.7, "Regulating Control Element Assembly CCEA)

Insertion Limits," does not ensure that adequate SDM exists.

Therefore, the plant must be shut down in order to evaluate the SDM required boron concentration and power level for critical operation. Continued operation is allowed with untrippable part strength CEAs if the alignment and insertion limits are met.

Continued operation is not allowed with one or more full length CEAs untrippable. This is because these cases are i ndi cati ve of a loss of SDM and power di stri buti on. and a loss of safety function, respectively.

D.1 Continued operation is not allowed in the case of more than one CEA misaligned from any other CEA in its group by

> 9.9 inches. For example, two CEAs in a group misaligned from any other CEA in that group by> 9.9. inches. or more than one CEA group that has a least one CEA misaligned from any other CEA in that group by > 9.9 inches. This is indicative of a loss of power distribution and a loss of (continued)

PALO VERDE UNITS 1,2.3 B 3.1.5-9 REVISION 60

CEA Alignment B 3.1.5 BASES ACTIONS D.1 (continued) safety function, respectively. Multiple CEA misalignments are outside of the CPC/CEAC design basis and. for some CEA combinations. will not result in automatic protective action. Therefore. with two or more CEAs misaligned more than 9.9 inches, this is a situation outside the design basis and immediate action would be required to prevent any potential fuel damage. Immediately opening the reactor trip breakers minimizes these effects.

SURVEILLANCE SR 3 .1.5 .1 REQUIREMENTS Verification that individual CEA positions are within 6.6 inches (indicated reed switch positions) of all other CEAs in the group allows the operator to detect a CEA that is beginning to deviate from its expected position. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

SR 3 .1. 5. 2 OPERABILITY of at least two CEA position indicator channels is required to determine CEA positions, and thereby ensure compliance with the CEA alignment and insertion limits. The CEA full in and full out limits provide an additional independent means for determining the CEA positions when the CEAs are at either their fully inserted or fully withdrawn positions. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

SR 3 .1. 5. 3 Verifying each full strength CEA is trippable would require that each CEA be tripped. In MODES 1 and 2 tripping each full strength CEA would result in radial or axial power tilts. or oscillations. Therefore individual full strength CEAs are exercised to provide increased confidence that all full strength CEAs continue to be trippable, even if they are not regularly tripped. A movement of 5 inches is adequate to demonstrate motion without exceeding the alignment limit when only one full strength CEA is being moved. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program. Between required (continued)

PALO VERDE UNITS 1,2,3 B 3.1.5-10 REVISION 63

Shutdown CEA Insertion Limits B 3.1.6 B 3.1 REACTIVITY CONTROL SYSTEMS B 3.1.6 Shutdown Control Element Assembly (CEA) Insertion Limits BASES BACKGROUND The insertion limits of the shutdown CEAs are initial assumptions in all safety analyses that assume CEA insertion upon reactor trip. The insertion limits directly affect core power distributions and assumptions of available SDM.

ejected CEA worth. and initial reactivity insertion rate.

The applicable criteria for these reactivity and power distribution design requirements are 10 CFR 50, Appendix A.

GDC 10. "Reactor Design," and GDC 26. "Reactivity Limits" (Ref. 1). and 10 CFR 50.46. "Acceptance Criteria for Emergency Core Cooling Systems for Light Water Nuclear Power Reactors" (Ref. 2). Limits on shutdown CEA insertion have been established. and all CEA positions are monitored and controlled during power operation to ensure that the reactivity limits. ejected CEA worth. and SDM limits are preserved.

The shutdown CEAs are arranged into groups that are radially symmetric. Therefore. movement of the shutdown CEAs does not introduce radial asymmetries in the core power distribution. The shutdown and regulating CEAs provide the required reactivity worth for immediate reactor shutdown upon a reactor trip.

The design calculations are performed with the assumption that the shutdown CEAs are withdrawn prior to the regulating CEAS. The shutdown CEAs must be capable of full withdrawal without the core going critical. This provides available negative reactivity for SDM in the event of boration errors.

The shutdown CEAs are controlled manually by the control room operator. During normal unit operation. the shutdown CEAs are fully withdrawn. The shutdown CEAs must be completely withdrawn from the core prior to withdrawing regulating CEAs during an approach to criticality. The shutdown CEAs are then left in this position until the reactor is shut down. They affect core power. burnup distribution. and add negative reactivity to shut down the reactor upon receipt of a reactor trip signal.

(continued)

PALO VERDE UNITS 1,2,3 B 3.1.6-1 REVISION 0

Shutdown CEA Insertion Limits B 3.1.6 BASES (continued)

APPLICABLE Accident analysis assumes that the shutdown CEAs are fully SAFETY ANALYSES withdrawn any time the reactor is critical. This ensures that:

a. The minimum SDM is maintained; and

b. The potential effects of a CEA ejection accident are limited to acceptable limits.

CEAs are considered fully withdrawn at 147.75 inches. since this position places sufficient reactivity outside the active region of the core to maintain the required shutdown reactivity worth assumed in the safety analyses. and to ensure the required SDM following a reactor trip.

On a reactor trip. all CEAs (shutdown CEAs and regulating CEAs). except the most reactive CEA. are assumed to insert into the core. The shutdown and regulating CEAs shall be at or above their insertion limits and available to insert the maximum amount of negative reactivity on a reactor trip signal. The regulating CEAs may be partially inserted in the core as allowed by LCO 3.1.7. "Regulating Control Element Assembly (CEA) Insertion Limits." The shutdown CEA insertion limit is established to ensure that a sufficient amount of negative reactivity is available to shut down the reactor and maintain the required SDM (see LCO 3.1.2.

"SHUTDOWN MARGIN (SDM) - Reactor Trip Breakers Closed")

following a reactor trip from full power. The combination of regulating CEAs and shutdown CEAs (less the most reactive CEA. which is assumed to be fully withdrawn) is sufficient to take the reactor from full power conditions at rated temperature to zero power. and to maintain the required SDM at rated no load temperature (Ref. 3). The shutdown CEA insertion limit also limits the reactivity worth of an ejected shutdown CEA.

The acceptance criteria for addressing shutdown CEA as well as regulating CEA insertion limits and inoperability or misalignment are that:

a. There be no violation of:

1. specified acceptable fuel design limits. or

2. Reactor Coolant System pressure boundary damage integrity; and (continued)

PALO VERDE UNITS 1.2.3 B 3.1.6-2 REVISION 63

Shutdown CEA Insertion Limits B 3.1.6 BASES (continued)

APPLICABLE b. The core remains subcriti cal after accident SAFETY ANALYSES transients.

(continued)

The most limiting SDM requirements for MODES 1 and 2 at EOC come from Steam Line Break (SLB). The requirements of the SLB event at EOC for both the full power and no load conditions are significantly larger than those of any other event at that time in cycle and. also. considerably larger than the most limiting requirements at BOC.

Although the most limiting SDM requirements at EOC are much larger than those at BOC. the available SDM obtained via the scramming of the CEAs are also substantially larger due to the much lower boron concentration at EOC. To verify that adequate SDM are available throughout the cycle to satisfy the changing requirements. calculations are perforn1ed at both BOC and EOC. It has been determined that calculations at these two times in cycle are sufficient since the differences between available SDM and the limiting SDM requirements are the smallest at these times in the cycle. The measurement of CEA bank worth performed as part of the Startup Testing Program demonstrates that the core has expected shutdown capability. Consequently, adherence to LCOs 3.1.6 and 3.1.7 provides assurance that the available SDM at any time in cycle will exceed the limiting SDM requirements at that time in the cycle.

The shutdown CEA insertion limits satisfy Criterion 2 of 10 CFR 50.36 (c)(2)(ii).

LCO The shutdown CEAs must be within their insertion limits any time the reactor is critical or approaching criticality.

This ensures that a sufficient amount of negative reactivity is available to shut down the reactor and maintain the required SDM following a reactor trip.

APPLICABILITY The shutdown CEAs must be within their insertion limits.

with the reactor in MODES 1 and 2. The applicability in MODE 2 begins anytime any regulating CEA is not fully inserted. This ensures that a sufficient amount of negative reactivity is available to shut down the reactor and maintain the required SDM following a reactor trip. Refer to LCO 3.1.1 and LCO 3.1.2. "SHUTDOWN MARGIN (SDM) -Reactor Trip Breaker Closed." for SDM requirements in MODES 3. 4.

(continued)

PALO VERDE UNITS 1.2.3 B 3.1.6-3 REVISION 42

Shutdown CEA Insertion Limits B 3.1.6 BASES (continued)

APPLICABILITY and 5. LCO 3. 9 .1. "Boron Concentration," ensures adequate (continued) OM in MODE 6.

This LCO has been modified by a Note indicating the LCO requirement is suspended during SR 3.1.5.3, which verifies the freedom of the CEAs to move. and requires the shutdown CEAs to move below the LCO limits. which would normally violate the LCO.

ACTIONS A.1 Prior to entering this Condition, the shutdown CEAs were fully withdrawn. If a shutdown CEA is then inserted into the core. its potential negative reactivity is added to the core as it is inserted.

If the CEA is not within limits. within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months restore the CEA to within limits. The 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months total Completion Time allows the operator adequate time to adjust the CEA in an orderly manner and is consistent with the required completion Times in LCO 3.1.5, "Control Element Assembly CCEA) Alignment."

B.1 When Required Action A.1 cannot be met or completed within the required Completion Time. a controlled shutdown should be commenced. The allowed Completion Time of 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months is reasonable, based on operating experience. for reaching MODE 3 from full power conditions in an orderly manner and without challenging plant systems.

SURVEILLANCE SR 3.1. 6.1 REQUIREMENTS Verification that the shutdown CEAs are within their insertion limits prior to an approach to criticality ensures that when the reactor is critical. or being taken critical, the shutdown CEAs (along with the regulating CEAs) will be available to shut down the reactor. and the required SDM will be maintained following a reactor trip. This SR and Frequency ensure that the shutdown CEAs are withdrawn before the regulating CEAs are withdrawn during a unit startup.

The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

(continued)

PALO VERDE UNITS 1,2,3 B 3.1.6-4 REVISION 63

Shutdown CEA Insertion Limits B 3.1.6 BASES (continued)

REFERENCES 1. 10 CFR 50, Appendix A. GDC 10 and GDC 26.

2. 10 CFR 50.46.

3. UFSAR, Section 15.4.

4. Calculation 13-JC-SF-0202.

PALO VERDE UNITS 1.2.3 B 3.1.6-5 REVISION 63

This page intentionally blank

~

B 3.2.2 BASES APPLICABLE cause increased power peaking and correspondingly increased SAFETY ANALYSES LHR.

(continued)

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

LCO The power distribution LCO limits are based on correlations between power peaking and certain measured variables used as inputs to the LHR and DNBR operating limits. The power distribution LCO limits are provided in the COLR.

Limiting the calculated Planar Radial Peaking Factors (F~)

used in the COLSS and CPCs to values greater than the measured Planar Radial Peaking Factors CF~) ensures that the limits calculated by the COLSS and CPls remain valid.

The Planar Radial Peaking Factor is the ratio of the peak to plane average power density of the individual fuel rods in a given horizontal plane, excluding the effects of azimuthal tilt.

APPLICABILITY Power distribution is a concern any time the reactor is critical. The power distribution LCOs, however, are only applicable in MODE 1 above 20% RTP. The reasons these LCOs are not applicable below 20% RTP are:

a. The incore neutron detectors that provide input to the COLSS, which then calculates the operating limits, are inaccurate because of the poor signal to noise ratio that they experience at relatively low core power levels; and

b. As a result of this inaccuracy, the CPCs assume a minimum core power of 20% RTP when generating the LPD and DNBR trip signals. When the core power is below 20% RTP, the core is operating well below its thermal limits, and the resultant CPC calculated LPD and DNBR trips are highly conservative.

ACTIONS A.1.1 and A.1.2 When the F~ values exceed the F~ values used in the COLSS and CPCs, Ihe associated DNBR and LHR calculations may be nonconservative. In this case. action must be taken to ensure that the COLSS and CPC calculations remain valid (continued)

PALO VERDE UNITS 1,2,3 B 3.2.2-5 REVISION 63

F~

B 3.2.L BASES ACTIONS A.l.l and A.l.2 (continued) with respect to the accident analysis. The operator can do this by performing the Required Actions A.l.l and A.1.2.

The 6 hour6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months Completion Time provides the time required to calculate the required multipliers and make the necessary adjustments to the CPC addressable constants. During this period the DNBR and LHR calculations may be slightly nonconservative with respect to the associated LCO requirements, but DNBR and LHR are still within fuel design limits. Therefore, 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months is an acceptable Completion Time to perform these actions considering the low probability of an accident occurring during this time period.

A.2 As an alternative to Required Actions A.l.l and A.l.2, the operator may adjust the affected values of F~ used in the COLSS and CPCs to values 2 F~. The 6 hour6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months Completion Time provides the time required to calculate the required multipliers and make the necessary adjustments to the CPC addressable constants. During this period the DNBR and LHR calculations may be slightly nonconservative with respect to the associated LCO requirements, but DNBR and LHR are still within fuel design limits. Therefore, 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months is an acceptable Completion Time to perform these actions considering the low probability of an accident occurring during this time period.

A.3 If Required Actions A.l.l and A.1.2 or A.2 cannot be accomplished within 6 hours6.944444e-5 days 0.00167 hours 9.920635e-6 weeks 2.283e-6 months , the core power must be reduced.

Reduction to 20% RTP or less ensures that the core is operating within the specified thermal limits and places the core in a conservative condition based on the trip setpoints generated by the COLSS and CPC operating limits; these limits are established assuming a minimum core power of 20% RTP. Six hours is a reasonable time to reach 20% RTP in an orderly manner and without challenging plant systems.

(continued)

PALO VERDE UNITS 1,2,3 B 3.2.2-6 REVISION 63

Fx_x B 3.2.t:

BASES (continued)

SURVEILLANCE SR 3.2.2.1 REQUIREMENTS This periodic Surveillance is for determining, using the Incore Detector System, that F~ values are~[~ values used in the COLSS and CPCs. It ensures that the F values used remain valid throughout the fuel cycle. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program. Determining the F~ values after each fuel loading when THERMAL POWER is> 40% RTP, but prior to its exceeding 70% RTP, ensures that the initial power ascension above 70% RTP is performed with conservative Fcxy values in COLSS and CPCs.

REFERENCES 1. UFSAR, Section 15.

2. UFSAR, Section 6.

3. CE-1 Correlation for DNBR.

4. 10 CFR 50, Appendix A, GDC 10.

5. 10 CFR 50.46.

6. Regulatory Guide 1.77, Rev. 0. May 1974.

7. 10 CFR 50, Appendix A, GDC 26.

PALO VERDE UNITS 1,2.3 B 3.2.2-7 REVISION 63

This page intentionally blank T~

B 3.2.3 BASES APPLICABLE Fuel cladding damage does not occur from conditions outside SAFETY ANALYSES the limits of these LCOs during normal operation. However, (continued) fuel cladding damage could result if an accident occurs due to initial conditions outside the limits of these LCOs. The potential for fuel cladding damage exists because changes in the power distribution can cause increased power peaking and correspondingly increased local LHRs.

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

LCD The power distribution LCD limits are based on correlations between power peaking and certain measured variables used as inputs to the LHR and DNBR operating limits. The power distribution LCD limits are provided in the COLR.

The limitations on the Tq are provided to ensure that design operating margins are ma1ntained. Tq greater than the limit in the COLR with COLSS in service or > 0.03 with COLSS out of service is not expected. If it occurs, the actions to be taken ensure that operation is restricted to only those conditions required to identify the cause of the tilt. It is necessary to explicitly account for power asymmetries because the radial peaking factors used in the core power distribution calculations are based on an untilted power distribution.

APPLICABILITY Power distribution is a concern any time the reactor is critical. The power distribution LCOs, however, are only applicable in MODE 1 above 20% RTP. The reasons these LCOs are not applicable below 20% RTP are:

a. The incore neutron detectors that provide input to the COLSS, which then calculates the operating limits, are inaccurate due to the poor signal to noise ratio that they experience at relatively low core power levels.

(continued)

PALO VERDE UNITS 1,2,3 B 3.2.3-5 REVISION 0

Tg B 3.2.3 BASES APPLICABILITY b. As a result of this inaccuracy, the CPCs assume a (continued) minimum core power of 20% RTP when generating LPD and DNBR trip signals. When the core power is below this level. the core is operating well below its thermal limits and the resultant CPC calculated LPD and DNBR trips are highly conservative.

ACTIONS A.l and A.2 If the measured Tq is greater than the T~allowance used in the CPCs but with1n the limit in the COLK with COLSS in service or~ 0.03 with COLSS out of service. the DNBR and LPD calculations performed by the CPCs may be nonconservative. Required Action A.l restores Tq to within its specified limits. and the reactor may return to normal operation. A Completion Time of 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months is sufficient because significant radial xenon redistribution does not occur within this time.

If the Tq cannot be restored within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months . the Tq allowance in the CPCs must be adjusted. per Required Action A.2. to be equal to or greater than the measured value of Tq to ensure that the design safety margins are maintained. The COLSS Tq alarm must also be adjusted to the new CPC allowance. so that the COLSS Tq alarm is still valid.

B.l. B.2. B.3. B.4. and B.5 Required Actions B.l. B.2. B.3. 8.4. and B.5 are modified by a Note that requires action B.5 be performed if power reduction commences prior to restoring Tq within the limit.

This requirement ensures that corrective action is taken before unrestricted power operation resumes.

If the measured Tq is not within the limit in the COLR with COLSS in service or> 0.03 with COLSS out of service.

THERMAL POWER is reduced to~ 50% RTP within 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months . The 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months allows enough time to take action to restore Tq prior to reducing power and limits the probability of operation with a power distribution out of limits. Such actions include performing SR 3.2.3.2. which provides a value of Tq that can be used in subsequent actions.

(continued)

PALO VERDE UNITS 1.2.3 B 3.2.3-6 REVISION 63

Tg B 3.2.3 BASES ACTIONS B.1. B.2, B.3, B.4. and B.5 (continued)

Also in the case of a tilt generated by a CEA misalignment.

the 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months allows recovery of the CEA misalignment. Except as a result of CEA misalignment. a measured Tq not within the limit in the COLR with COLSS in service or> 0.03 with COLSS out of service is not expected. If it occurs.

continued operation of the reactor may be necessary to discover the cause of the tilt. Operation then is restricted to only those conditions required to identify the cause of the tilt. It is necessary to explicitly account for power asymmetries because the radial power peaking factors used in the core power distribution calculation are based on an untilted power distribution.

If the measured Tq is not restored to within its specified limits. the reactor continues to operate with a power distribution mismatch. Continued operation in this configuration may induce a xenon oscillation. which results in increased LHGRs when the xenon redistributes. If the measured Tq cannot be restored to within its limit within 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months . reactor power must be reduced. Reducing THERMAL POWER to< 50% RTP within 4 hours4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months provides an acceptable level of protection from increased power peaking due to potential xenon redistribution while maintaining a power level sufficiently high enough to allow the tilt to be analyzed.

The Variable Overpower trip setpoints are reduced to

~55% RTP to ensure that the assumptions of the accident analysis regarding power peaking are maintained. After power has been reduced to ~ 50% RTP. the rate and magnitude of changes in the core flux are greatly reduced. Therefore.

16 hours1.851852e-4 days 0.00444 hours 2.645503e-5 weeks 6.088e-6 months is an acceptable time period to allow for reduction of the Variable Overpower trip setpoints. Required Action B.2. The 16 hour1.851852e-4 days 0.00444 hours 2.645503e-5 weeks 6.088e-6 months Completion Time allowed to reduce the Variable Overpower trip setpoints is required to perform the actions necessary to reset the trip setpoints.

THERMAL POWER is restricted to 50% RTP until the measured Tq is restored to within its specified limit by correcting the out of limit condition. This action prevents the operator from increasing THERMAL POWER above the conservative limit when a significant Tq has existed. but allows the unit to continue operation for diagnostic purposes.

(continued)

PALO VERDE UNITS 1.2.3 B 3.2.3-7 REVISION 63

T~

8 3.2.3 BASES ACTIONS 8.1, 8.2, 8.3, 8.4, and 8.5 (continued)

If Tq is restored prior to identifying and correcting the cause, the plant corrective action program will continue to evaluate the cause of the out of limit condition.

After a THERMAL POWER increase following restoration of Tq.

operation may proceed provided the measured Tq is determined to remain within its specified limit at the increased THERMAL POWER level.

The provision to allow discontinuation of the Surveillance after verifying that Tq is within its specified limit at least once per hour for 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months or until T is verified to be within its specified limit at a THERMAL POWER~ 95% RTP provides an acceptable exit from this action after the measured Tq has been returned to an acceptable value.

C.1 If the measured ~cannot be restored or determined within its specified lim1t, core power must be reduced. Reduction of core power to~ 20% RTP ensures that the core is operating within its thermal limits and places the core in a conservative condition based on the trip setpoints generated by the CPCs, which assume a minimum core power of 20% RTP.

Six hours is a reasonable time to reach 20% RTP in an orderly manner and without challenging plant systems.

SURVEILLANCE SR 3.2.3.1 REQUIREMENTS Continuous monitoring of the measured Tq by the incore nuclear detectors is provided by the COLSS. A COLSS alarm is annunciated in the event that the measured Tq exceeds the value used in the CPCs.

With the COLSS out of service, the operator must calculate Tq and verify that it is within its specified limits. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

(continued)

PALO VERDE UNITS 1,2.3 8 3.2.3-8 REVISION 56

CEACs B 3.3.3 BASES BACKGROUND appropriate "penalty factors" are transmitted to the CPC (continued) Processor in that channel. These penalty factors conservatively adjust the effective operating margins to the DNBR- Low and LPD- High trips.

Each CEA has two separate reed switch position transmitter (RSPT) assemblies mounted outside the Reactor Coolant Pressure Boundary (RCPB). designated RSPT 1 and RSPT 2.

CEA position from the RSPTs is processed by CEA Position Processors (CPPs) located in each CPC channel. The CPPs transmit CEA position to the appropriate CEAC in all four CPC channels over optically isolated datalinks. such that CEAC 1 in all channels receives the position of all CEAs based upon RSPT 1. and CEAC 2 receives the position of all CEAs based upon RSPT 2. Thus. the position of all CEAs is independently monitored by both CEACs in each CPC channel.

The CPCs display the position of each CEA to the operator on a separate single CEA Position Flat Panel Display. Each CPC channel is connected to the display by means of an optically isolated data link. The operator may select the channel for display. Selecting channel A orB will display CEA position based upon RSPT 1 on each CEA. whereas selecting channel C or D will display CEA position based upon RSPT 2 on each CEA.

Functional testing of the entire RPS. from bistable input through the opening of individual sets of RTCBs. can be performed either at power or shutdown and is normally performed on a quarterly basis. Nuclear instrumentation.

the CPCs. and the CEACs can be similarly tested. CPC and CEAC functional testing is performed on a Refueling interval basis. UFSAR. Section 7.2 (Ref. 3}. provides more detail on RPS testing. Process transmitter calibration is normally performed on a refueling basis.

APPLICABLE Each of the analyzed transients and accidents can be SAFETY ANALYSIS detected by one or more RPS Functions.

(continued)

PALO VERDE UNITS 1.2.3 B 3.3.3-3 REVISION 53

CEACs B 3.3.3 BASES APPLICABLE The effect of any misoperated CEA within a subgroup on the SAFETY ANALYSIS core power distribution is assessed by the CEACs, and an (continued) appropriately augmented power distribution penalty factor will be supplied as input to the CPCs. As the reactor core responds to the reactivity changes caused by the misoperated CEA and the ensuing reactor coolant and doppler feedback effects, the CPCs will initiate a DNBR- Low or LPD- High trip signal if SAFDLs are approached. Each CPC also directly monitors one "target CEA" from each subgroup and uses this information to account for excessive radial peaking factors for events involving CEA groups out of sequence and subgroup deviations within a group.

Therefore, although the CEACs do not provide a direct reactor trip Function, their input to the CPCs is taken credit for in the CEA misoperation analysis.

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

LCO This LCO on the CEACs ensures that the CPCs are either informed of individual CEA position within each subgroup, using one or both CEACs in each channel, or that appropriate conservatism is included in the CPC calculations to account for the anticipated CEA deviations.

CEAC 1 in all four CPC channels monitors CEA position based upon RSPT 1 on all CEAs. CEAC 2 in all four channels monitors CEA position based upon RSPT 2 on all CEAs. Each CPC uses the higher of the two deviation penalty factors transmitted by the channel CEACs. Thus only one OPERABLE CEAC is required in each channel to provide CEA deviation (continued)

PALO VERDE UNITS 1,2,3 B 3.3.3-4 REVISION 63

PAM Instrumentation B 3.3.10 BASES LCO 8. Containment Isolation Valve Position (continued)

(continued)

At PVNGS the Containment Isolation Valve position instrumentation consist of:

CPA-UV-2A Containment Refueling Purge Supply CPA-UV-28 Containment Refueling Purge Exhaust CPB-UV-3A Containment Refueling Purge Supply CPB-UV-38 Containment Refueling Purge Exhaust CPA-UV-4A Containment Power Access Purge Supply CPA-UV-48 Containment Power Access Purge Exhaust CPB-UV-5A Containment Power Access Purge Supply CPB-UV-58 Containment Power Access Purge Exhaust CHB-UV-505 RCP Controlled Bleedoff to VCT CHA-UV-506 RCP Controlled Bleedoff to VCT CHA-UV-516 Letdown to Regen HX CHB-UV-523 Letdown from Regen HX CHA-UV-560 Reactor Drain Tank Outlet CHB-UV-561 Reactor Drain Tank Outlet CHA-UV-580 Make-Up Supply to Reactor Drain Tank CHA-UV-715*(2)Sample Return to Reactor Drain Tank CHB-UV-924*mLetdown Line Sample PASS GAA-UV-1 HP Nitrogen to Safety Injection Tanks GAA-UV-2 LP Nitrogen to Containment GRA-UV-1 Waste Gas Header GRB-UV-2 Waste Gas Header HCB-UV-44* Radiation Monitor RU-1 Supply HCA-UV-45* Radiation Monitor RU-1 Supply HCA-UV-46* Radiation Monitor RU-1 Return HCB-UV-47* Radiation Monitor RU-1 Return HPA-UV-1 Containment Hydrogen Control System HPB-UV-2 Containment Hydrogen Control System HPA-UV-3 Hydrogen Recombiner Supply HPB-UV-4 Hydrogen Recombiner Supply HPA-UV-5 Hydrogen Recombiner Return HPB-UV-6 Hydrogen Recombiner Return HPA-UV -23*< 2> Hydrogen Monitor Return HPA-UV-24*< 2> Hydrogen Monitor Supply IAA-UV-2* Instrument and Service Air (continued)

PALO VERDE UNITS 1.2.3 B 3.3.10-9 REVISION 63

PAM Instrumentation B 3.3.10 BASES LCO 8. Containment Isolation Valve Position (continued)

(continued)

NCB-UV-401 Nuclear Cooling Water NCA-UV-402 Nuclear Cooling Water NCB-UV-403 Nuclear Cooling Water RDA-UV-23 Containment Sumps RDB-UV-24 Containment Sumps SGB-HV-200 Steam Generator #1 Chemical Injection SGB-HV-201 Steam Generator #2 Chemical Injection SIA-UV -708°) Containment Reci rc Sump PASS SSB-UV-200 Hot Leg Sample SSB-UV-201 Surge Line Sample SSB-UV-202 Pressurizer Steam Space Sample SSA-UV-203 Hot Leg Sample SSA-UV-204 Surge Line Sample SSA-UV-205 Pressurizer Steam Space Sample WCB-UV-61 Normal Chilled Water Return Header WCA-UV-62 Normal Chilled Water Return Header WCB-UV-63 Normal Chilled Water Supply Header

-Solenoid operated valves with relay driven SESS/ERFDADS indication.

Note 1. In units where DMWO 2778159 has been implemented. applicable valve(s) have been removed.

Note 2. DMWO 2529758 removes piping and valves (manual and/or solenoid) from selected portions of the PASS System piping that are connected to safety-related piping and/or components. In Units where DMWO 2529758 has been implemented. valve CHA-UV-715 is removed and valves HPA-UV-023 &HPA-UV-024 are de-terminated with upstream piping cut and capped as the new containment boundary.

9. Containment Area Radiation (high range)

Containment Area Radiation is provided to monitor for the potential of significant radiation releases and to provide release assessment for use by operators in determining the need to invoke site emergency plans.

The alarm setpoints shall be set within the limits specified in the UFSAR.

At PVNGS. Containment Area Radiation instrumentation consists of the following:

SQA-RU-148 SQB-RU-149 (continued)

PALO VERDE UNITS 1.2.3 B 3.3.10-10 REVISION 63

AFW System B 3.7.5 BASES APPLICABILITY In MODES 1. 2. and 3, the AFW System is required to be OPERABLE and to function in the event that the MFW System is lost. In addition. the AFW System is required to supply enough makeup water to replace steam generator secondary inventory, lost

.. as the unit cools to MODE 4 conditions.

In MODE 4. the AFW System may be used for heat removal via the steam generator.

In MODES 5 and 6. the steam generators are not normally used for decay heat removal. and the AFW System is not required.

A note prohibits the application of LCD 3.0.4.b to an inoperable AFW Train. There is an increased risk associated with entering a MODE or other specified condition in the applicability with an AFW train inoperable and the provisions of LCO 3.0.4.b which allows entry into a MODE or other specified condition in the Applicability with the LCO not met after performance of a risk assessment addressing inoperable systems and components. should not be applied in this circumstance.

ACTIONS A.1 If one of the two steam supplies to the turbine driven AFW pumps is inoperable. or if a turbine driven pump is inoperable while in MODE 3 immediately following refueling (prior to MODE 2). action must be taken to restore OPERABLE status within 7 days. The 7 day Completion Time is reasonable based on the following reasons:

a. For the inoperability of a steam supply to the turbine-driven AFW pump. the 7 day Completion time is reasonable since there is a redundant steam supply line for the turbine driven pump.

b. For the inoperability of a turbine-driven AFW pump while in MODE 3 immediately subsequent to a refueling outage, the 7 day Completion time is reasonable due to the minimal decay heat levels in this situation.

c. For both the inoperability of a steam supply line to the turbine-driven pump and an inoperable turbine-driven AFW pump while in MODE 3 immediately following a refueling outage. the 7 day Completion time is reasonable due to the availability of redundant OPERABLE motor driven AFW pumps.

(continued)

PALO VERDE UNITS 1.2.3 B 3.7.5-5 REVISION 42

AFW System B 3.7.5 BASES ACTIONS A.l (continued)

Condition A is modified by a Note which limits the applicability of the Condition to when the unit has not entered MODE 2 following a refueling. Condition A allows the turbine-driven AFW pump to be inoperable for 7 days vice the 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Completion Time in Condition B. This longer Completion Time is based on the reduced decay heat following refueling and prior to the reactor being critical.

It should be noted that when in this Condition with one steam supply to the turbine driven AFW pump inoperable, that the AFA train of AFW is considered to be inoperable.

B.l With one of the required AFW trains (pump or flow path) inoperable, action must be taken to restore OPERABLE status within 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . This Condition includes the loss of two steam supply lines to the turbine driven AFW pump. The 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months Completion Time is reasonable, based on the redundant capabilities afforded by the AFW System. the time needed for repairs. and the low probability of a DBA event occurring during this period. Two AFW pumps and flow paths remain to supply feedwater to the steam generators.

C.l and C.2 When either Required Action A.l or B.l cannot be completed within the required Completion Time. or if two AFW trains are inoperable in MODES 1. 2, and 3, 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 within 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months .

This Condition includes the loss of 2 AFW pumps. This Condition also includes the situation where one steam supply to the turbine driven AFW pump is inoperable. coincident with another ("B" or "N") AFW train inoperable.

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.

(continued)

PALO VERDE UNITS 1.2.3 B 3.7.5-6 REVISION 63

AFW System B 3.7.5 BASES ACTIONS C.1 and C.2 (continued)

In MODE 4. with two AFW trains inoperable. operation is allowed to continue because only one motor driven AFW pump (either the essential or the non-essential pump) is required in accordance with the Note that modifies the LCO. Although it is not required. the unit may continue to cool down and start the SOC.

0.1 Required Action 0.1 is modified by a Note indicating that all required MODE changes or power reductions are suspended until one AFW train is restored to OPERABLE status.

Completion Times are also suspended at the time the conditions is entered. The Completion Time is resumed with the time remaining when the Condition was entered upon restoration of one AFW train to OPERABLE status.

With all three AFW trains inoperable in MODES 1. 2. and 3.

the unit is in a seriously degraded condition with no TS related means for conducting a cooldown. and only limited means for conducting a cooldown with nonsafety grade equipment. In such a condition. the unit should not be perturbed by any action. including a power change, that might result in a trip. The seriousness of this condition requires that action be started immediately to restore one AFW train to OPERABLE status. LCO 3.0.3 is not applicable.

as it could force the unit into a less safe condition.

E.1 Required Action E.1 is modified by a Note indicating that all required MODE changes or power reductions are suspended until one AFW train is restored to OPERABLE status.

Completion Times are also suspended at the time the Condition is entered. The Completion Time is resumed with the time remaining when the Condition was entered upon restoration of one AFW train to OPERABLE status.

With one AFW train inoperable. action must be taken to immediately restore the inoperable train to OPERABLE status or to immediately verify. by administrative means. the OPERABILITY of a second train. LCD 3.0.3 is not applicable.

as it could force the unit into a less safe condition.

(continued)

PALO VERDE UNITS 1.2.3 B 3.7.5-7 REVISION 63

AFW System B 3.7.5 BASES ACTIONS E.1 (continued)

In MODE 4. either the reactor coolant pumps or the SOC loops can be used to provide forced circulation as discussed in LCD 3.4.6, "RCS Loops- MODE 4."

SURVEILLANCE SR 3.7.5.1 REQUIREMENTS Verifying the correct alignment for manual. power operated.

and automatic valves in the AFW water and steam supply flow paths provides assurance that the proper flow paths exist for AFW operation. This SR does not apply to valves that are locked. sealed. or otherwise secured in position. since these valves are verified to be in the correct position prior to locking, sealing, or securing. This SR also does not apply to valves that cannot be inadvertently misaligned.

such as check valves. This Surveillance does not require any testing or valve manipulations; rather. it involves verification that those valves capable of potentially being mispositioned are in the correct position.

The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

SR 3.7.5.2 Verifying that each AFW pump's developed head at the flow test point is greater than or equal to the required developed head ensures that AFW pump performance has not degraded during the cycle. Flow and differential head are normal tests of pump performance required by the ASME OM Code (Ref. 2). Because it is undesirable to introduce cold AFW into the steam generators while they are operating. this testing may be performed on recirculation flow. This test confirms one point on the pump design curve and can be indicative of overall performance. Such inservice tests confirm component OPERABILITY. trend performance. and detect

incipient failures by indicating abnormal performance.

Performance of inservice testing, discussed in the ASME OM Code. (Ref. 2). at 3 month intervals satisfies this requirement.

(continued)

PALO VERDE UNITS 1.2.3 B 3.7.5-8 REVISION 63

AFW System B 3.7.5 BASES SURVEILLANCE SR 3.7.5.2 (continued)

REQUIREMENTS This SR is modified by a Note indicating that the SR should be deferred until suitable test conditions are established.

Normal operating pressure is established in the steam generators when RCS temperature reaches 532°F, this corresponds to a Psn of 900 psia. This deferral is required because there is an insufficient steam pressure to perform the test.

SR 3.7.5.3 This SR ensures that AFW can be delivered to the appropriate steam generator. in the event of any accident or transient that generates an AFAS signal. by demonstrating that each automatic valve in the flow path actuates to its correct position on an actual or simulated actuation signal. This Surveillance is not required for valves that are locked.

sealed. or otherwise secured in the required position under administrative controls. This SR is not required for the non-essential train since there are no automatic valves which receive an AFAS. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

This SR is modified by a Note indicating that the SR should be deferred until suitable test conditions have been established. Normal operating pressure is established in the steam generators when RCS temperature reaches 532°F, this corresponds to a Psat of 900 psia. This deferral is required because there is an insufficient steam pressure to perform the test.

Also. this SR is modified by a Note that states the SR is not required in MODE 4. In MODE 4. the required AFW train is already aligned and operating.

This SR ensures that the essential AFW pumps will start in the event of any accident or transient that generates an AFAS signal by demonstrating that each essential AFW pump starts automatically on an actual or simulated actuation signal. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

(continued)

PALO VERDE UNITS 1,2,3 B 3.7.5-9 REVISION 63

AFW System B 3.7.5 BASES SURVEILLANCE SR 3.7.5.4 REQUIREMENTS The non-essential AFW pump does not automatically activate and is not subject to this SR.

This SR is modified by two Notes. Note 1 indicates that the SR be deferred until suitable test conditions are established. Normal operating pressure is established in the steam generators when RCS temperature reaches 532°F, this corresponds to a P 5 ~ of 900 psia. This deferral is required because there is insufficient steam pressure to perform the test. Note 2 states that the SR is not required in MODE 4. In MODE 4. the required pump is already operating and the autostart function is not required.

SR 3.7.5.5 This SR ensures that the AFW System is properly aligned by verifying the flow path from each essential AFW pump to each steam generator prior to entering MODE 2 operation. after 30 days in MODE 5 or 6. OPERABILITY of essential AFW flow paths must be verified before sufficient core heat is generated that would require the operation of the AFW System during a subsequent shutdown. The Frequency is reasonable.

based on engineering judgment. and administrative controls to ensure that flow paths remain OPERABLE.

To further ensure AFW System alignment. the OPERABILITY of the essential AFW flow paths is verified following extended outages to determine that no misalignment of valves has occurred. This SR ensures that the flow path from the CST to the steam generators is properly aligned by requiring a verification of minimum flow capacity of 650 gpm at pressures corresponding to 1270 psia at the entrance to the steam generators. (This SR is not required for the non-essential AFW pump since it is normally used for startup and shutdown.)

REFERENCES 1. UFSAR. Section 10.4.9.

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

PALO VERDE UNITS 1.2.3 B 3.7.5-10 REVISION 63

Spent Fuel Assembly Storage B 3.7.17 B 3.7 PLANT SYSTEMS B 3.7.17 Spent Fuel Assembly Storage BASES BACKGROUND The spent fuel storage is designed to store either new Cnonirradiated) nuclear fuel assemblies. or burned (irradiated) fuel assemblies in a vertical configuration underwater. The storage pool was originally designed to store up to 1329 fuel assemblies in a borated fuel storage mode.

The current storage configuration. which allows credit to be taken for boron concentration. burnup. and decay time. and does not require neutron absorbing (boraflex) storage cans.

provides for a maximum storage of 1209 fuel assemblies in a four-region configuration. The design basis of the spent fuel cooling system. however. is to provide adequate cooling to the spent fuel during all operating conditions (including full core offload) for only 1205 fuel assemblies CUFSAR section 9.1.3). Therefore. an additional four spaces are mechanically blocked to limit the maximum number of fuel assemblies that may be stored in the spent fuel storage pool to 1205.

Region 1 is comprised of two 9x8 storage racks and one 12x8 storage rack. To prevent inadvertent storage of a fuel assembly in a cell required to be vacant. cell blocking devices are placed in every other storage cell location in Region 1 to maintain a two-out-of-four checkerboard configuration.

Region 3 is comprised of three 9x8 storage racks and one 9x9 storage rack in Units 2 and 3. Region 3 is comprised of four 9x8 storage racks and one 9x9 storage rack in Unit 1. Since fuel assemblies may be stored in every Region 3 cell location.

no cell blocking devices are installed in Region 3.

Regions 2 and 4 are mixed and are comprised of seven 9x8 storage racks and three 12x8 storage racks in Units 2 and 3.

Regions 2 and 4 are mixed and are comprised of six 9x8 storage racks and three 12x8 storage racks in Unit 1. Regions 2 and 4 are mixed in a repeating 3x4 storage pattern in which two-out-of-twelve cell locations are designated Region 2 and ten-out-of-twelve cell locations are designated Region 4 (see UFSAR Figures 9.1-7 and 9.1-7A). Since fuel assemblies may be stored in every Region 2 and Region 4 cell location. no cell blocking devices are installed in Region 2 and Region 4.

(continued)

PALO VERDE UNITS 1.2.3 B 3.7.17-1 REVISION 63

Spent Fuel Assembly Storage B 3.7.17 BASES BACKGROUND The spent fuel storage cells are installed in parallel rows (continued) with a nominal center-to-center spacing of 9.5 inches. This spacing, a minimum soluble boron concentration of 900 ppm.

and the storage of fuel in the appropriate region based on assembly burnup in accordance with TS Figures 3.7.17-1.

3.7.17-2. and 3.7.17-3 is sufficient to maintain a ken of

~0.95 for fuel of original maximum radially averaged enrichment of up to 4.80%.

APPLICABLE The spent fuel storage pool is designed for non-SAFETY ANALYSES criticality by use of adequate spacing, credit for boron concentration. and the storage of fuel in the appropriate region based on assembly burnup in accordance with TS Figures 3.7.17-1. 3.7.17-2. and 3.7.17-3. The design requirements related to criticality CTS 4.3.1.1) are keff < 1. 0 assuming no credit for boron and ken ~ 0. 95 taking credit for soluble boron. The burnup versus enrichment requirements CTS Figures 3.7.17-1. 3.7.17-2. and 3.7.17-3) are developed assuming ken< 1.0 with no credit taken for soluble boron. and that ken s 0.95 assuming a soluble boron concentration of 900 ppm and the most limiting single fuel mishandling accident.

The analysis of the reactivity effects of fuel storage in the spent fuel storage racks was performed by ASS-Combustion Engineering CCE) using the three-dimensional Monte Carlo code KENO-VA with the updated 44 group ENDF/B-5 neutron cross section library. The KENO code has been previously used by CE for the analysis of fuel rack reactivity and have been benchmarked against results from numerous critical experiments. These experiments simulate the PVNGS fuel storage racks as realisticall y as possible with respect to parameters important to reactivity such as enrichment and assembly spacing.

The modeling of Regions 2. 3. and 4 included several conservative assumptions. These assumptions neglected the reactivity effects of poison shims in the assemblies and structural grids. These assumptions tend to increase the calculated effective multiplication factor Ckeff) of the racks. The stored fuel assemblies were modeled as CE 16x16 assemblies with a nominal pitch of 0.5065 inches between fuel rods. a fuel pellet diameter of 0.3255 inches. and a U0(2) density of 10.31 glee.

(continued)

PALO VERDE UNITS 1.2.3 B 3.7.17-2 REVISION 3

Spent Fuel Assembly Storage B 3.7.17 BASES APPLICABLE KENO-Va calculations were used to construct curves of burnup SAFETY ANALYSES versus initial enrichment for decay times in 5 year (continued) increments from 0 to 20 years for both Regions 3 and 4 CTS Figures 3.7.17-2 and 3.7.17-3) such that all points on the curves produce a keff value (including all biases and uncertainties) of< 1.0 for unborated water. Core operating conditions. such as temperature and boron concentration.

influence plutonium production and may increase the discharged fuel reactivity which could impact those curves.

Biases associated with methodology and water temperature were included. and uncertainties associated with methodology, KENO-Va calculation. fuel enrichment. fuel rack pitch. fuel rack and L-insert thickness. pellet stack density, and asymmetric fuel assembly loading were included. KENO-Va calculations were also performed to determine the soluble boron concentration required to maintain the spent fuel pool keff (including all biases and uncertainties) s 0.95 at a 95% probability/95% confidence level. A soluble boron concentration of 900 ppm is required to assure that the spent fuel pool keff remains s 0.95 at all times. This soluble boron concentration accounts for the positive reactivity effects of the most limiting single fuel mishandling event and uncertainties associated with fuel assembly reactivity and burnup. This method of reactivity equivalencing has been accepted by the NRC (Reference 3) and used for numerous other spent fuel storage pools that take credit for burnup. decay time. and soluble boron.

Most abnormal storage conditions will not result in an increase in the keff of the racks. However. it is possible to postulate events. with a burnup and enrichment combination outside of the acceptable area in TS Figure 3.7.17-1. or with a burnup. decay time. and enrichment combination outside of the acceptable area in TS Figures 3.7.17-2 or 3.7.17-3. which could lead to an increase in reactivity. These events would include an assembly drop on top of a rack or between a rack and the pool walls. or the misloading of an assembly. For such events. partial credit may be taken for the soluble boron in the spent fuel pool water to ensure protection against a criticality accident since* the staff does not require the assumption of two unlikely, independent.

concurrent events (double contingency principle). Although a soluble boron concentration of only 900 ppm is required to assure that keff remains s 0.95 assuming the single most limiting fuel mishandling event. TS 3.7.15 conservatively requires the presence of 2150 ppm of soluble boron in the spent fuel pool water. As such, the reduction in keff caused (continued)

PALO VERDE UNITS 1.2.3 B 3.7.17-3 REVISION 63

Spent Fuel Assembly Storage B 3.7.17 BASES APPLICABLE by the required soluble boron concentration more than SAFETY ANALYSES offsets the reactivity addition caused by credible (continued) accidents. and the staff criterion of ~rr s 0.95 is met at all times.

The critical ity aspects of the spent fuel pool meet the requirements of General Design Criterion 62 for the prevention of critical ity in fuel storage and handling.

The spent fuel pool heat load calculations were based on a full pool with 1205 fuel assemblies. From the spent fuel pool critical ity analysis, the number of fuel assemblies that can be stored in the four-region configuration is 1209 fuel assemblies. The design basis of the spent fuel cooling system, however, is to provide adequate cooling to the spent fuel during all operating conditions (including full core offload) for only 1205 fuel assemblies CUFSAR section 9.1.3).

Therefore. an additional four spaces are mechanically blocked to limit the maximum number of fuel assemblies that may be stored in the spent fuel storage pool to 1205.

The original licensing basis for the spent fuel pool allowed for spent fuel to be loaded in either a 4x4 array or a checkerboard array, depending on the use of borated poison.

A fuel handling accident was assumed to occur with maximum loading of the pool. The fuel pool rack construction precludes more than one assembly from being impacted in a fuel handling accident. The UFSAR analysis conclusion regarding the worst scenario for a dropped assembly (in which the horizontal impact of a fuel assembly on top of the spent fuel assembly damages fuel rods in the dropped assembly but does not impact fuel in the stored assemblies) continues to be limiting.

The spent fuel assembly storage satisfies Criterion 2 of 10 CFR 50.36 (c)(2)(i i).

LCD The restrictions on the placement of fuel assemblies within the spent fuel pool. according to Figures 3.7.17-1, 3.7.17-2.

and 3.7.17-3 in the accompanying LCO, ensures that the keff of the spent fuel pool will always remain< 1.0 assuming the pool to be flooded with unborated water. The restrictions are consistent with the critical ity safety analysis performed for the spent fuel pool according to Figures 3.7.17-1.

3.7.17-2, and 3.7.17-3 in the accompanying LCO.

Specification 4.3.1.1 provides additional details for fuel storage in each of the four Regions.

(continued)

PALO VERDE UNITS 1,2,3 B 3.7.17-4 REVISION 63

AC Sources - Operating B 3.8.1 BASES ACTIONS A.2 (continued)

Additionally, the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months 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.

A.3 According to Regulatory Guide 1.93 (Ref. 6), operation may continue in Condition A for a period that should not exceed 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months . With one offsite circuit inoperable, the reliability of the offsite system is degraded, and the potential for a loss of offsite power is increased, with attendant potential for a challenge to the unit safety systems. In this Condition, however, the remaining OPERABLE offsite circuit and DGs are adequate to supply electrical power to the onsite Class 1E Distribution System.

The 72 hour8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months 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.

B.1 To ensure a highly reliable power source remains with an inoperable DG, it is necessary to verify the availability of the offsite circuits on a more frequent basis. Since the Required Action only specifies "perform," a failure of SR 3.8.1.1 acceptance criteria does not result in a Required Action being not met. However, if an offsite circuit fails to pass SR 3.8.1.1, it is inoperable. Upon offsite circuit inoperability, additional Conditions and Required Actions must then be entered.

B.2 Required Action B.2 is intended to provide assurance that a loss of offsite power, during the period that a DG is inoperable, does not result in a complete loss of safety function of redundant required features. These features require Class 1E power from PBA-S03 or PBB-S04 ESF buses to be OPERABLE, and are identical to those specified in ACTION A.2. Mode applicability is as specified in each appropriate TS section. Redundant required feature failures consist of (continued)

PALO VERDE UNITS 1,2,3 B 3.8.1-9 REVISION 63

AC Sources - Operating B 3.8.1 BASES ACTIONS B.2 (continued) inoperable features associated with a train. redundant to the train that has an inoperable DG.

The Completion Time for Required Action 8.2 is intended to allow the operator time to evaluate and repair any discovered inoperabilities. This Completion Time also allows for an exception to the norma 1 "time zero" for beginning the allowed outage time "clock." In this Required Action. the Completion Time only begins on discovery that both:

a. An inoperable DG exists: and

b. A required feature on the other train is inoperable.

If at any time during the existence of this Condition Cone DG inoperable) a required feature subsequently becomes inoperable. this Completion Time begins to be tracked.

Discovering one required DG inoperable coincident with one or more inoperable required support or supported features.

or both. that are associated with the OPERABLE DG. results in starting the Completion Time for the Required Action.

Four hours from the discovery of these events existing concurrently, is acceptable because it minimizes risk while allowing time for restoration before subjecting the unit to transients associated with shutdown.

In this Condition. the remaining OPERABLE DG and offsite circuits are adequate to supply electrical power to the onsite Class lE Distribution System. Thus. on a component basis. single failure protection for the required feature's function may have been lost: however. function has not been lost. The 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months Completion Time takes into account the OPERABILITY of the redundant counterpart to the inoperable required feature. Additionally, the 4 hour4.62963e-5 days 0.00111 hours 6.613757e-6 weeks 1.522e-6 months 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.

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.1-10 REVISION 63

AC Sources - Operating B 3.8.1 BASES ACTIONS B.2 (continued)

If a DG has been declared inoperable and Condition B has been entered. and during that inoperability a new problem with the inoperable DG is discovered. a separate entry into Condition B is not required for the new DG problem.

Therefore. the Required Actions of Condition B would not apply to the new DG problem. The new DG problem must be entered into the corrective action program and corrective actions specified in accordance with the corrective action program. Transportability must be addressed in a timely manner in accordance with the corrective action program.

B.3.1 and B.3.2 Required Action B.3.1 provides an allowance to avoid unnecessary testing of OPERABLE DGs. If it can be determined that the cause of the inoperable DG does not exist on the OPERABLE DG. SR 3.8.1.2 does not have to be performed. If the cause of inoperability exists on the other DG. the other DG would be declared inoperable upon discovery and ConditionE of LCO 3.8.1 would be entered.

Once the failure is repaired. the common cause failure no longer exists and Required Action 8.3.1 is satisfied. If the cause of the initial inoperable DG cannot be confirmed not to exist on the remaining DG. performance of SR 3.8.1.2 suffices to provide assurance of continued OPERABILITY of that DG.

In the event the inoperable DG is restored to OPERABLE status prior to completing either 8.3.1 or B.3.2. the plant corrective action program will continue to evaluate the common cause possibility. This continued evaluation.

however. is no longer under the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months constraint imposed while in Condition B.

According to Generic Letter 84-15 CRef. 7). 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months is reasonable to confirm that the OPERABLE DG(s) is not affected by the same problem as the inoperable DG.

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.1-11 REVISION 63

AC Sources -Operating B 3.8.1 BASES ACTIONS B.4 (continued)

In Condition B. the remaining OPERABLE DG and offsite circuits are adequate to supply electrical power to the onsite Class 1E Distribution System. The 10 day 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.

When utilizing an extended DG Completion Time (a Completion Time greater than 72 hours8.333333e-4 days 0.02 hours 1.190476e-4 weeks 2.7396e-5 months and less than or equal to 10 days). the compensatory measures listed below shall be implemented. For planned maintenance utilizing an extended Completion Time. the compensatory measures shall be implemented prior to entering Condition B. For an unplanned entry into an extended Completion Time. the compensatory measures shall be implemented without delay.

1. The redundant DG (along with all of its required systems. subsystems. trains. components. and devices) will be verified OPERABLE (as required by TS) and no discretionary maintenance activities will be scheduled on the redundant (OPERABLE) DG.

2. No discretionary maintenance activities will be scheduled on the station blackout generators (SBOGs).

3. No discretionary maintenance activities will be scheduled on the startup transformers.

4. No discretionary maintenance activities will be scheduled in the APS switchyard or the unit's 13.8 kV power supply lines and transformers which could cause a line outage or challenge offsite power availability to the unit utilizing the extended DG Completion Time.

5. All activity, including access. in the Salt River Project (SRP) switchyard shall be closely monitored and controlled. Discretionary maintenance within the switchyard that could challenge offsite power supply availability will be evaluated in accordance with 10 CFR 50.65(a)(4) and managed on a graded approach according to risk significance.

6. The SBOGs will not be used for non-safety functions (i.e .. power peaking to the grid).

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.1-12 REVISION 63

AC Sources - Operating B 3.8.1 BASES ACTIONS 8.4 (continued)

7. Weather conditions will be assessed prior to removing a DG from service during planned maintenance activitie~.

Additionally, DG outages will not be scheduled when severe weather conditions and/or unstable grid conditions are predicted or present.

8. All maintenance activities associated with the unit that is utilizing the extended DG Completion Time will be assessed and managed per 10 CFR 50.65 (Maintenance Rule).

9. The functionality of the SBOGs will be verified by ensuring that the monthly start test has been successfully completed within the previous four weeks before entering the extended DG Completion Time.

10. The OPERABILITY of the steam driven auxiliary feedwater pump will be verified before entering the extended DG Completion Time.

11. The system dispatcher will be contacted once per day and informed of the DG status. along with the power needs of the facility.

12. Should a severe weather warning be issued for the local area that could affect the switchyard or the offsite power supply during the extended DG Completion Time. an operator will be available locally at the SBOG should local operation of the SBOG be required as a result of on-site weather related damage.

13. No discretionary maintenance will be allowed on the main and unit auxiliary transformers associated with the unit.

If one or more of the above compensatory measures is not met while in the extended completion time. the corrective action program shall be entered. the risk managed in accordance with the Maintenance Rule. and the compensatory measure(s) restored without delay.

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.1-13 REVISION 63

AC Sources - Operating B 3.8.1 BASES ACTIONS C.1 and C.2 Required Action C.1. which applies when two offsite circuits are inoperable. is intended to provide assurance that an event with a coincident single failure will not result in a complete loss of redundant required safety functions. The Completion Time for this failure of redundant required features is reduced to 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months from that allowed for one train without offsite power (Required Action A.2). The rationale for the reduction to 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months is that Regulatory Guide 1.93 (Ref. 6) allows a Completion Time of 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months for two required offsite circuits inoperable. based upon the assumption that two complete safety trains are OPERABLE.

When a concurrent redundant required feature failure exists.

this assumption is not the case. and a shorter Completion Time of 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months is appropriate. These features are powered from redundant AC safety trains. These features require Class lE power from PBA-S03 or PBB-S04 ESF buses to be OPERABLE. and are identical to those specified in ACTION A.2. Mode applicability is as specified in each appropriate TS section.

The Completion Time for Required Action C.1 is intended to allow the operator time to evaluate and repair any discovered inoperabilities. This Completion Time also allows for an exception to the normal "time zero" for beginning the allowed outage time "clock." In this Required Action. the Completion Time only begins on discovery that both:

a. All required offsite circuits are inoperable: and

b. A required feature is inoperable.

If at any time during the existence of Condition C (two offsite circuits inoperable) and a required feature becomes inoperable. this Completion Time begins to be tracked.

According to Regulatory Guide 1.93 (Ref. 6). operation may continue in Condition C for a period that should not exceed 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . This level of degradation means that the offsite electrical power system does not have the capability to effect a safe shutdown and to mitigate the effects of an accident; however. the onsite AC sources have not been degraded. This level of degradation generally corresponds to a total loss of the immediately accessible offsite power sources.

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.1-14 REVISION 63

AC Sources - Operating B 3.8.1 BASES ACTIONS C.1 and C.2 (continued)

Because of the normally high availability of the offsite sources, this level of degradation may appear to be more severe than other combinations of two AC sources inoperable that involve one or more DGs inoperable. However. two factors tend to decrease the severity of this level of degradation:

a. The configuration of the redundant AC electrical power system that remains available is not susceptible to a single bus or switching failure; and

b. The time required to detect and restore an unavailable offsite power source is generally much less than that required to detect and restore an unavailable onsite AC source.

With both of the required offsite circuits inoperable.

sufficient onsite AC sources are available to maintain the unit in a safe shutdown condition in the event of a DBA or transient. In fact. a simultaneous loss of offsite AC sources.

a LOCA, and a worst case single failure were postulated as a part of the design basis in the safety analysis. Thus. the 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time provides a period of time to effect restoration of one of the offsite circuits commensurate with the importance of maintaining an AC electrical power system capable of meeting its design criteria.

According to Regulatory Guide 1.93 (Ref. 6). with the available offsite AC sources. two less than required by the LCD.

operation may continue for 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . If two offsite sources are restored within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . unrestricted operation may continue. If only one offsite source is restored within 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months . power operation continues in accordance with Condition A.

Condition C applies only when the offsite circuits are unavailable to commence automatic load sequencing in the event of a design basis accident CDBA). In cases where the offsite circuits are available for sequencing, but a DBA could cause actuation of the Degraded Voltage Relays, Condition G applies.

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.1-15 REVISION 63

AC Sources - Operating B 3.8.1 BASES ACTIONS D.1 and D.2 Pursuant to LCD 3.0.6. the Distribution System ACTIONS would not be entered even if all AC sources to it were inoperable resulting in de-energization. Therefore. the Required Actions of Condition D are modified by a Note to indicate that when Condition D is entered with no AC source to a train. the Conditions and Required Actions for LCD 3.8.9.

"Distribution Systems- Operating," must be immediately entered. This allows Condition D to provide requirements for the loss of one offsite circuit and one DG without regard to whether a train is de-energized. LCO 3.8.9 provides the appropriate restrictions for a de-energized train.

According to Regulatory Guide 1.93 (Ref. 6). operation may continue in Condition D for a period that should not exceed 12 hours1.388889e-4 days 0.00333 hours 1.984127e-5 weeks 4.566e-6 months .

In Condition D. individual redundancy is lost in both the offsite electrical power system and the onsite AC electrical power system. Since power system redundancy is provided by two diverse sources of power. however. the reliability of the power systems in this Condition may appear higher than that in Condition C Closs 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 0.00333 hours 1.984127e-5 weeks 4.566e-6 months 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 Train A and Train B DGs inoperable. there are no remaining standby AC sources. 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 is the only source of AC power for this level of degradation. the risk associated with continued operation for a 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 (continued)

PALO VERDE UNITS 1.2.3 B 3.8.1-16 REVISION 63

AC Sources - Operating B 3.8.1 BASES ACTIONS E.1 (continued) 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 Regulatory Guide 1.93 (Ref. 6). with both DGs inoperable, operation may continue for a period that should not exceed 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months .

F.1 and F.2 The sequencer(s) is an essential support system to both the offsite circuit and the DG associated with a given ESF bus.

Furthermore. the sequencer is on the primary success path for most major AC electrically powered safety systems powered from the associated ESF bus. Therefore, loss of an ESF bus sequencer affects every major ESF system in the load group. The 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months Completion Time provides a period of time to correct the problem commensurate with the importance of maintaining sequencer OPERABILITY. This time period also ensures that the probability of an accident (requiring sequencer OPERABILITY) occurring during periods when the sequencer is inoperable is minimal. Required Action F.2 is intended to provide assurance that a single failure of a DG Sequencer will not result in a complete loss of safety function of critical redundant required features.

G.1 and G.2 To ensure offsite circuits will not be lost as a consequence of a DBE. certain conditions must be maintained. Failure to maintain these conditions may result in double sequencing should an accident requiring sequencer operation occur.

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.1-17 REVISION 63

AC Sources- Operating B 3.8.1 BASES ACTIONS G.l and G.2 (continued)

An offsite circuit meets its required capability by maintaining either of the following conditions:

1. Steady-state switchyard voltage at or above the minimum level needed to support the offsite circuit's functions.

The minimum allowable voltage is the value calculated as follows or 528.5 kV, whichever is less:

Base minimum voltage (provides for 518 kV emergency loads on PBA-S03 or PBB-S04 and house loads on NAN-SOl or NAN-S02)

If the offsite circuit is connected to add 6.5 kV 1-E-NAN-S05 or 1-E-NAN-S06 If the house load group associated with add 4 kV the offsite circuit is connected to both NBN-SOl and NBN-S02 (tie breaker NBN-SOlC closed)

If the offsite circuit is connected to add 1.5 kV another unit's PBA-S03 or PBB-S04 This option does not apply if the unit under review is the only Palo Verde unit synchronized to the 525 kV switchyard and its main generator gross MVAR output is >

0 or if the offsite circuit is connected to both PBA-S03 and PBB-S04 in the same unit.

The values used to calculate minimum allowable voltage are based on calculations 01. 02. 03-EC-MA-0221 that analyze many different bus alignment conditions. The values are conservative. with sufficient margin to account for analytical uncertainties and to provide assurance that the degraded voltage relays will not actuate as a result of an accident.

The highest minimum voltage of 528.5 kV is based on management of the loading of the startup transformer secondary windings to not exceed their rated 70 MVA capacity during a design basis event. When two units are sharing a secondary winding. the associated tie breaker NAN-S03B or NAN-S04B must always be open and fast bus transfer control switch NAN-HK-S03B or NAN-HK-S04B in "Manual" position in at least one of the units.

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.1-18 REVISION 63

AC Sources - Operating B 3.8.1 BASES ACTIONS G.1 and G.2 (continued)

Meters A-E-MAN-EI-001 and A-E-MAN-EI-002 are used to monitor switchyard voltage. The allowable values take into account metering uncertainties. A voltage dip lasting 35 seconds or less is considered a transient.

rather than steady-state condition based on the credited 35 second time delay of the degraded voltage relay. The time delay feature on the meters' alarms may be set up to 35 seconds to avoid nuisance alarms.

2. Associated tie breaker NAN-S03B or NAN-S04B to house load buses NAN-SOl or NAN-S02 open and fast bus transfer control switch NAN-HK-S03B or NAN-HK-S04B in "Manual" position. When two units are sharing a startup transformer secondary winding, this condition must be met in both units.

If the required capability in Condition G is not met. the effects of an ADO or DBA could cause further depression of the voltage at the ESF bus and actuation of the degraded voltage relays. These actuations would result in disconnection of the bus from the offsite circuits.

Regulatory Guide 1.93 (Ref. 6) defines this condition as "The Available Offsite Power Sources Are One Less Than the LCD" or "The Available Offsite AC Power Sources Are Two Less Than the LCD," depending on the number of affected circuits.

However, degraded post-trip voltage could also cause ESF electrical equipment to be exposed to a degraded condition during the degraded voltage relay time-out period. There is a risk that equipment misoperation or damage could occur during this time. In this scenario. the ESF equipment may not perform as designed following an automatic disconnection of the offsite circuits and reconnection to the diesel generators (DGs), even though adequate power is available from the DG. For certain DBAs. an additional consideration is that the initial sequencing of the ESF equipment onto the offsite circuits. subsequent tripping of the degraded voltage relays, and interruption in equipment credited in the UFSAR Chapter 6 and 15 safety analyses could challenge the credited equipment response times. Therefore. it is appropriate to implement Required Actions that are more stringent than those specified in Condition A or C.

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.1-19 REVISION 63

AC Sources -Operating B 3.8.1 BASES ACTIONS G.1 and G.2 (continued)

If the required capability in Condition G is not met. the following options are available to restore full or partial Operability. Options are listed in their order of preference.

1. Achieve Condition 1 as discussed above (switchyard voltage at or above the minimum allowable value). This is accomplished by either of the following:

Increase switchyard voltage. If more than one Palo Verde unit is operating, switchyard voltage is increased by increasing MVAR output of any Palo Verde unit, or by any number of methods implemented by the Energy Control Center. If only one Palo Verde unit is operating, switchyard voltage is increased by any number of methods implemented by the Energy Control Center while maintaining the generator gross MVAR output of the Palo Verde unit to ::; 0.

Reduce minimum allowable voltage as calculated above. This is achieved by realignment of equipment power sources. if such an option is available.

2. Achieve Condition 2 as discussed above. This is accomplished by ensuring the affected tie breaker CNAN-S03B or NAN-S04B) is open and the fast bus transfer control switch CNAN-HK-S03B or NAN-HK-S04B) is in the "Manual" position. If two units are sharing a startup transformer secondary winding, this condition must be achieved in both units. Although Palo Verde has no formal restrictions on the amount of time that fast bus transfer can be out of service. this option should be used judiciously in order to maintain forced circulation capability.

3. Transfer the safety busCes) to the diesel generator(s).

This is less desirable than option 2, because it would perturb the plant. It would cause the plant to remain in an LCD 3.8.1 condition CA or C. depending on whether one or two buses are transferred).

(continued)

PALO VERDE UNITS 1.2,3 B 3.8.1-20 REVISION 63

AC Sources - Operating B 3.8.1 BASES ACTIONS G.1 and G.2 (continued)

Options 1 and 2 satisfy Required Action G.l. and Option 3 satisfies Required Action G.2. With more than one offsite circuit that does not meet the required capability, Condition G could be satisfied for each offsite circuit by the use of Required Action G.l or G.2. The Completion Time for both Required Action G.l and G.2 is one hour. The one hour time limit is appropriate and consistent with the need to remove the unit from this condition. because the level of degradation exceeds that described in Regulatory Guide 1.93 (Ref. 6) for two offsite circuits inoperable. The regulatory guide assumes that an adequate onsite power source is still available to both safety trains. but in a scenario involving automatic load sequencing and low voltage to the ESF buses. adequate voltage is not assured from any of the power sources for the following systems immediately after the accident signal has been generated (i.e .. while the degraded voltage relay is timing out): radiation monitors Train A RU-29 or Train B RU-30 (TS 3.3.9). Train B RU-145; ECCS (TS 3.5.3); containment spray (TS 3.6.6);

containment isolation valves (TS 3.6.3); auxiliary feedwater system (TS 3.7.5); essential cooling water system (TS 3.7.7); essential spray pond system (TS 3.7.8);

essential chilled water system (TS 3.7.10); control room essential filtration system (TS 3.7.11); ESF pump room air exhaust cleanup system (TS 3.7.13): and fuel building ventilation.

Required Action G.2 is modified by a Note. The reason for the Note is to ensure that the offsite circuit is not inoperable for a time greater than the Completion Time allowed by LCD 3.8.1 Condition A or C. Therefore. if Conditions A or C are entered. the Completion Time clock for Conditions A and C would start at the Time Condition Gwas entered.

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.1-21 REVISION 63

AC Sources - Operating B 3.8.1 BASES ACTIONS H.1 and H.2 (continued)

If the inoperable AC electrical power sources cannot be restored to OPERABLE status within the required Completion Time. the unit must be brought to a MODE in which the LCD does not apply. To achieve this status. the unit 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 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.

I.1 Condition I corresponds to a level of degradation in which all redundancy in the AC electrical power supplies has been lost. At this severely degraded level. any further losses in the AC electrical power system will cause a loss of function. Therefore, no additional time is justified for continued operation. The unit is required by LCO 3.0.3 to commence a controlled shutdown.

SURVEILLANCE The AC sources are designed to permit inspection and testing REQUIREMENTS of all important areas and features, especially those that have a standby function. in accordance with 10 CFR 50, Appendix A, GDC 18 (Ref. 8). Periodic component tests are supplemented by extensive functional tests during refueling outages (under simulated accident conditions).

The SR for demonstrating OPERABILITY of the DGs are based on the recommendations of Regulatory Guide 1.9 (Ref. 3), unless otherwise noted in the Updated FSAR Section 1.8.

The DG capabilities (starting and loading) are required to be met from a variety of initial conditions such as DG in standby condition with the engine hot (SR 3.8.1.15) and DG in standby condition with the engine at normal keep-warm conditions (SR 3.8.1.2, SR 3.8.1.7 and SR 3.8.1.19).

Although it is expected that most DG starts will be performed from normal keep-warm conditions. DG starts should be performed with the jacket water cooling and lube oil temperatures within the lower to upper limits of DG OPERABILITY. except as noted above. Rapid cooling of the DG down to normal keep-warm conditions should be minimized.

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.1-22 REVISION 41

Inverters -Operating B 3.8.7 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.7 Inverters- Operating BASES BACKGROUND The inverters are the preferred source of power for the AC vital instrument buses because of the stability and reliability they achieve by being powered from the 125 VDC battery source. The function of the inverter is to provide AC electrical power to the AC vital instrument buses. The AC vital instrument bus can be powered from an AC source via a Class 1E constant voltage regulator or from the inverter connected to the station battery. This configuration provides an uninterruptible power source for the instrumentation and controls for the Reactor Protective System (RPS) and the Engineered Safety Feature Actuation System (ESFAS). There are two inverters per Train (A and B) which totals to four inverters per unit with swing I inverters. if available. Specific details on inverters and their operating characteristics are found in the UFSAR.

Chapter 8 (Ref. 1).

If available, a swing inverter and line-up switch can be used as a required inverter in place of a normal inverter.

If the swing inverter is substituted for one of the normal inverters. the requirements of independence and redundancy between subsystems are maintained. The swing inverter and line-up switch are manually transferable to either channel of a train (not both) and are normally de-energized. The transfer mechanism is a three position break-before-make (center position OFF) six pole switch which prevents both channels of a train from being simultaneously connected.

Specific details on swing inverters and their operating characteristics are found in the UFSAR. Chapter 8 (Ref. 1).

APPLICABLE The initial conditions of Design Basis Accident (DBA) and SAFETY ANALYSES transient analyses in the UFSAR. Chapter 6 (Ref. 2) and Chapter 15 (Ref. 3), assume Engineered Safety Feature systems are OPERABLE. The inverters are designed to provide the required capacity, capability, redundancy, and reliability to ensure the availability of necessary power to the RPS and ESFAS instrumentation and controls so that the fuel. Reactor Coolant System, and containment design limits are not exceeded. These limits are discussed in more detail in the Bases for Section 3.2. Power Distribution Limits; (continued)

PALO VERDE UNITS 1,2,3 B 3.8.7-1 REVISION 63

Inverters - Operating 2

BASES SAFETY ANALYSIS Inverters are a part of the distribution system and. as (continued) such. satisfy Criterion 3 of 10 CFR 50.36 (c)(2)(ii).

Section 3.4. Reactor Coolant System CRCS); and Section 3.6.

Containment Systems.

The OPERABILITY of the inverters is consistent with the initial assumptions of the accident analyses and is based on meeting the design basis of the unit. This includes maintaining required AC vital instrument buses OPERABLE during accident conditions in the event of:

a. An assumed loss of all offsite AC electrical power or all onsite AC electrical power; and

b. A worst case single failure.

LCO The inverters ensure the availability of AC electrical power for the systems' instrumentation required to shut down the reactor and maintain it in a safe condition after an anticipated operational occurrence (AOO) or a postulated DBA.

Maintaining the required inverters OPERABLE ensures that the redundancy incorporated into the design of the RPS and ESFAS instrumentation and controls is maintained. The four required inverters (two per train) ensure an uninterruptible supply of AC electrical power to the AC vital instrument buses even if the 4.16 kV safety buses are de-energized (the swing inverter. one per train. may be used to satisfy this requirement. if available).

OPERABLE inverters require the associated AC vital instrument bus to be powered by the inverter with output voltage and frequency within tolerances. and power input to the inverters from a 125 VDC station battery.

This LCO is modified by a Note that allows one inverter to be disconnected from its associated battery for~ 24 hours2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months .

if the AC vital instrument bus is powered from a Class 1E constant voltage regulator during the period and all other inverters are operable. This allows an equalizing charge to be placed on one battery. If the inverter was not disconnected. the resulting voltage condition might damage the inverter. These provisions minimize the loss of (continued)

PALO VERDE UNITS 1.2.3 B 3.8.7-2 REVISION 63

Inverters - Operating 3

BASES LCD equipment that would occur in the event of a loss of offsite (continued) power. The 24 hour2.777778e-4 days 0.00667 hours 3.968254e-5 weeks 9.132e-6 months time period for the allowance minimizes the time during which a loss of offsite power could result in the loss of equipment energized from the affected AC vital instrument bus while taking into consideration the time required to perform an equalizing charge on the battery bank.

The intent of this Note is to limit the number of inverters that may be disconnected. Only the inverter associated with the single battery undergoing an equalizing charge may be disconnected. All other required inverters must be I connected to their associated batteries and aligned to their associated AC vital instrument buses.

APPLICABILITY The inverters 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 ADOs or abnormal transients; and

b. Adequate core cooling is provided. and containment OPERABILITY and other. vital functions are maintained in the event of a postulated DBA.

Inverter requirements for MODES 5 and 6. and during movement of irradiated fuel assemblies are covered in the Bases for LCD 3.8.8, "Inverters - Shutdown."

ACTIONS A.1 With a required inverter inoperable. its associated AC vital instrument bus becomes inoperable until it is re-energized from its Class 1E constant voltage source regulator.

Required Action A.1 is modified by a Note. which states to enter the applicable conditions and Required Actions of LCD 3.8.9, "Distribution Systems- Operating," when Condition A is entered with one AC vital instrument bus de-energized. This ensures the AC vital instrument bus is re-energized within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months via the Class 1E constant voltage regulator.

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.7-3 REVISION 63

Inverters - Operating 4

BASES ACTIONS A.l (continued)

Required Action A.l allows 7 days to fix the inoperable inverter and return it to service. The 7 day limit is a risk informed Completion Time based on a plant specific risk analysis. taking into consideration the time required to repair an inverter and the additional risk to which the unit is exposed because of the inverter inoperability. This has to be balanced against the risk of an immediate shutdown.

along with the potential challenges to safety systems such a shutdown might entail. When the AC vital instrument bus is powered from its constant voltage source. it is relying upon interruptible AC electrical power sources (offsite and onsite). The uninterruptible inverter source to the AC vital instrument buses is the preferred source for powering instrumentation trip setpoint devices.

Planned inverter maintenance or other activities that require entry into Required Action A.l will not be undertaken concurrent with the following:

a. Planned maintenance on the associated train Diesel Generator COG): or

b. Planned maintenance on another RPS or ESFAS channel that results in that channel being in a tripped condition.

These actions are taken because it is recognized that with a required inverter inoperable and the instrument bus being powered by the regulating transformer. instrument power for that train is dependent on power from the associated DG following a loss of offsite power event.

B.l and B.2 If the required inoperable devices or components cannot be restored to OPERABLE status within the required Completion Time. the unit must be brought to a MODE in which the LCO does not apply. To achieve this status. the unit 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 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.

PALO VERDE UNITS 1.2.3 B 3.8.7-4 REVISION 63

Inverters - Shutdown B 3.8.8 B 3.8 ELECTRICAL POWER SYSTEMS B 3.8.8 Inverters -Shutdown BASES BACKGROUND A description of the inverters is provided in the Bases for LCO 3.8.7. "Inverters- Operating."

APPLICABLE The initial conditions of Design Basis Accident (DBA) and SAFETY ANALYSES transient analyses in the UFSAR. Chapter 6 (Ref. 1) and Chapter 15 (Ref. 2). assume Engineered Safety Feature systems are OPERABLE. The DC to AC inverters are designed to provide the required capacity, capability, redundancy, and reliability to ensure the availability of necessary power to the Reactor Protective System and Engineered Safety Features Actuation System instrumentation and controls so that the fuel. Reactor Coolant System, and containment design limits are not exceeded.

The OPERABILITY of the inverters is consistent with the initial assumptions of the accident analyses and the requirements for the supported systems' OPERABILITY.

The OPERABILITY of the minimum inverters to each AC vital instrument bus during MODES 5 and 6, and during movement of irradiated fuel assemblies ensures that:

a. The unit can be maintained in the shutdown or refueling condition for extended periods:

b. Sufficient instrumentation and control capability is available for monitoring and maintaining the unit status: and

c. Adequate power is available to mitigate events postulated during shutdown, such as a fuel handling accident.

In general, when the unit is shut down. the Technical Specification requirements ensure that the unit has the capability to mitigate the consequences of postulated accidents. However. assuming a single failure and concurrent loss of all offsite or all onsite power is not (continued)

PALO VERDE UNITS 1.2.3 B 3.8.8-1 REVISION 1

Inverters - Shutdown B 3.8.8 BASES APPLICABLE required. The rationale for this is based on the fact that SAFETY ANALYSES many Design Basis Accidents (DBAs) that are analyzed in (continued) MODES 1. 2. 3. and 4 have no specific analyses in MODES 5 and 6. Worst case bounding events are deemed not credible in MODES 5 and 6 because the energy contained within the reactor pressure boundary, reactor coolant temperature and pressure. and the corresponding stresses result in the probabilities of occurrence being significantly reduced or eliminated, and minimal in consequences. These deviations from DBA analysis assumptions and design requirements during shutdown conditions are allowed by the LCO for required systems.

The inverters support the equipment and instrumentation required to mitigate the Loss of Shutdown Cooling and Loss of RCS Inventory accidents analyzed in response to NRC Generic Letter 88-17 "Loss of Decay Heat Removal." The Generic Letter does not require the assumption of a single failure and concurrent loss of all offsite or all onsite power.

The inverters were previously identified as part of the distribution system and. as such, satisfy Criterion 3 of 10 CFR 50.36 (c)(2)(ii).

LCO The required inverters ensure the availability of electrical power for the instrumentation for systems required to shut down the reactor and maintain it in a safe condition after an anticipated operational occurrence or a postulated DBA.

The battery powered inverters provide uninterruptible supply of AC electrical power to the AC vital instrument buses even if the 4.16 kV safety buses are de-energized. OPERABILITY of the inverters requires that the AC vital instrument bus be powered by the required inverter which can be a swing inverter. if available. This ensures the availability of sufficient inverter power sources to operate the unit in a safe manner and to mitigate the consequences of postulated events during shutdown (e.g., fuel handling accidents).

In Modes 5 &6 and during movement of irradiated fuel assemblies. one train of inverters. consisting of two channels with one inverter per channel. is required to be OPERABLE to support the requirements of LCO 3.8.10 "Distribution Systems- Shutdown". This train of inverters also supports the one required OPERABLE Diesel Generator specified in LCO 3.8.2 "AC Sources - Shutdown" on that same train. For situations where redundant trains of supported (continued)

PALO VERDE UNITS 1.2.3 B 3.8.8-2 REVISION 63

Inverters - Shutdown B 3.8.8 BASES LCD equipment are required to be OPERABLE by LCD 3.8.10. the (continued) necessary AC vital instrument bus(es) associated with the additional train of inverters shall be energized by either the bus(es)' associated required inverter or AC voltage regulator. For those situations v1here an AC vital instrument bus associated with the additional train of inverters is energized by its required inverter. the corresponding DC bus must be energized by a minimum of its associated battery charger or backup battery charger per LCD 3.8.5.

APPLICABILITY The inverters required to be OPERABLE in MODES 5 and 6. and during movement of irradiated fuel assemblies provide assurance that:

a. Systems to provide adequate coolant inventory makeup are available for the irradiated fuel in the core;

b. Systems needed to mitigate a fuel handling accident are available;

c. Systems necessary to mitigate the effects of events that can lead to core damage during shutdown are available; and

d. Instrumentation and control capability is available for monitoring and maintaining the unit in a cold shutdown condition or refueling condition.

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.

Inverter requirements for MODES 1. 2. 3. and 4 are covered in LCD 3.8.7.

ACTIONS The Actions are modified by a Note that identifies required Action A.2.3 is not applicable to the movement of irradiated fuel assemblies in Modes 1 through 4.

A.1. A.2.1. A.2.2. A.2.3. and A.2.4 If two trains of AC vital instrument buses are required by LCD 3. 8.10. "Di stri buti on Systems - Shutdown." of the hvo required trains. the remaining bus(es) with AC power available may be capable of supporting sufficient required features to allow continuation of CORE ALTERATIONS. fuel (continued)

PALO VERDE UNITS 1.2.3 B 3.8.8-3 REVISION 63

Inverters - Shutdown B 3.8.8 BASES ACTIONS A.1. A.2.1. A.2.2. A.2.3. and A.2.4 (continued) movement. operations with a potential for draining the reactor vessel. and operations with a potential for positive reactivity additions. By the allowance of the option to declare required features inoperable with the associated inverter(s) inoperable. appropriate restrictions will be implemented in accordance with the affected required features LCOs' Required Actions. In many instances. this option may involve undesired administrative efforts.

Therefore. the allowance for sufficiently conservative actions is made (i.e .. to suspend CORE ALTERATIONS. movement of irradiated fuel assemblies. and operations involving positive reactivity additions). The Required Action to suspend positive reactivity additions does not preclude actions to maintain or increase reactor vessel inventory.

provided the required SDM is maintained.

Suspension of these activities shall not preclude completion of actions to establish a safe conservative condition. If moving irradiated fuel assemblies while in MODES 1. 2. 3. or

4. the fuel movement is independent of reactor operations.

Therefore. inability to immediately suspend movement of irradiated fuel assemblies would not be sufficient reason to require a reactor shutdown. These actions minimize the probability of the occurrence of postulated events. It is further required to immediately initiate action to restore the required inverters and to continue this action until restoration is accomplished in order to provide the necessary inverter power to the unit safety systems.

The Completion Time of immediately is consistent with the required times for actions requiring prompt attention. The restoration of the required inverters should be completed as quickly as possible in order to minimize the time the unit safety systems may be without sufficient power.

SURVEILLANCE SR 3.8.8.1 REQUIREMENTS This Surveillance verifies that the inverters are functioning properly with all required circuit breakers closed and AC vital instrument buses energized from the inverter. The verification of proper voltage and frequency output ensures that the required power is readily available for the instrumentation connected to the AC vital instrument buses. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.8-4 REVISION 56

Distribution Systems -Operating B 3.8.9 BASES LCO OPERABLE AC electrical power distribution subsystems require (continued) the associated buses, load centers. motor control centers.

and distribution panels to be energized to their proper voltages. OPERABLE DC el ectri cal po111er di stri buti on subsystems require the associated buses to be energized to their proper voltage from either the associated battery or charger. OPERABLE AC vital instrument bus electrical power distribution subsystems require the associated buses to be energized to their proper voltage from the associated inverter via inverted DC voltage, or Class lE constant voltage regulator.

In addition, tie breakers between redundant safety related AC, DC, and AC vital instrument bus power distribution subsystems, if they exist, must be open. This prevents any electrical malfunction in any power distribution subsystem from propagating to the redundant subsystem, which could cause the failure of a redundant subsystem and a loss of essential safety function(s). If any tie breakers are closed, the affected redundant electrical power distribution subsystems are considered inoperable. This applies to the onsite, safety related redundant electrical power distribution subsystems. It does not, however, preclude redundant Class lE 4.16 kV buses from being powered from the same offsite circuit.

APPLICABILITY The electrical power distribution subsystems 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 ADOs or abnormal transients; and

b. Adequate core cooling is provided. and containment OPERABILITY and other vital functions are maintained in the event of a postulated DBA.

Electrical power distribution subsystem requirements for MODES 5 and 6, and during movement of irradiated fuel assemblies are covered in the Bases for LCO 3.8.10, "Distribution Systems- Shutdown."

(continued)

PALO VERDE UNITS 1,2,3 B 3.8.9-3 REVISION 51

Distribution Systems -Operating B 3.8.9 BASES (continued)

ACTIONS A.1 With one or more required AC buses. load centers. or motor control centers (see Table B 3.8.9.-1). except AC vital instrument buses. in one subsystem inoperable. the remaining AC electrical power distribution subsystem in the other train is capable of supporting the minimum safety functions necessary to shut down the reactor and maintain it in a safe shutdown condition. assuming no single failure. The overall reliability is reduced. however. because a single failure in the remaining power distribution subsystems could result in the minimum required ESF functions not being supported.

Therefore. the required AC buses. load centers and motor control centers must be restored to OPERABLE status within 8 hours9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months .

Condition A worst scenario is one train (PBA or PBB) without AC power (i.e .. no offsite power to the train and the associated DG inoperable). In this condition. the unit is more vulnerable to a complete loss of AC power. It is.

therefore. imperative that the unit operator's attention be focused on minimizing the potential for loss of power to the remaining train by stabiJizing the unit. and on restoring power to the affected train. The 8 hour9.259259e-5 days 0.00222 hours 1.322751e-5 weeks 3.044e-6 months time limit before requiring a unit shutdown in this condition is acceptable because of:

a. The potential for decreased kafety if the unit operator's attention is diverted from the evaluations and actions necessary to restore power to the affected train. to the actions associated with taking the unit to shutdown within this time limit; and

b. The potential for an event in conjunction with a single failure of a redundant component in the train with AC power.

B.1 With AC vital instrument bus(es) (Channels A or C. or Channels B or 0) (see Table B 3.8.9-1) in one train inoperable. the remaining OPERABLE AC vital bus electrical power distribution subsystem is capable of supporting the minimum safety functions necessary to shut down the unit and maintain it in the safe shutdown condition. Overall (continued)

PALO VERDE UNITS 1.2.3 B 3.8.9-4 REVISION 63

Distribution Systems -Operating B 3.8.9 BASES ACTIONS B.1 (continued) reliability is reduced. however. since an additional single failure could result in the minimum required ESF functions not being supported. Therefore. the required AC vital instrument buses must be restored to OPERABLE status within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months by powering the bus from the associated inverter via inverted DC voltage or the Class lE constant voltage regulator.

Condition B represents one train without adequate AC vital instrument bus power; potentially both the DC source and the associated AC source are nonfunctioning. In this situation.

the unit is significantly more vulnerable to a complete loss of all noninterruptible power. It is. therefore. imperative that the operator's attention focus on stabilizing the unit.

minimizing the potential for loss of OPERABILITY to the remaining vital instrument buses. and restoring power to the affected electrical power distribution subsystem.

This 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months limit is more conservative than Completion Times allowed for the vast majority of components that are without adequate AC vital instrument power. Taking exception to LCO 3.0.2 for components without adequate AC vital instrument power. which would have the Required Action Completion Times shorter than 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months if declared inoperable. is acceptable because of:

a. The potential for decreased safety by requiring a change in unit conditions Ci .e .. requiring a shutdown) and not allowing stable operations to continue;

b. The potential for decreased safety by requiring entry into numerous Applicable Conditions and Required Actions for components without adequate AC vital instrument power and not providing sufficient time for the operators to perform the necessary evaluations and actions for restoring power to the affected train; and

c. The potential for an event in conjunction with a single failure of a redundant component.

The 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months Completion Time takes into account the importance to safety of restoring the AC vital instrument bus to OPERABLE status. the redundant capability afforded by the other OPERABLE vital instrument buses. and the low probability of a DBA occurring during this period. I (continued)

PALO VERDE UNITS 1.2.3 B 3.8.9-5 REVISION 63

Distribution Systems- Operating B 3.8.9 BASES ACTIONS C.1 With DC bus(es) in one train (see Table B 3.8.9-1) inoperable. the remaining DC electrical power distribution subsystem is capable of supporting the minimum safety functions necessary to shut down the reactor and maintain it in a safe shutdown condition. assuming no single failure.

The overall reliability is reduced. however. because a single failure in the remaining DC electrical power distribution subsystem could result in the minimum required ESF functions not being supported. Therefore. the required DC buses must be restored to OPERABLE status within 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months by powering the bus from the associated battery or battery charger.

Condition C represents one train without adequate DC power; potentially both with the battery significantly degraded and the associated charger nonfunctioning. In this situation.

the unit is significantly more vulnerable to a complete loss of all DC power. It is. therefore. imperative that the operator's attention focus on stabilizing the unit.

minimizing the potential for loss of power to the remaining DC buses and restoring power to the affected DC electrical power distribution subsystem.

This 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months limit is more conservative than Completion Times allowed for the vast majority of components which would be without power. Taking exception to LCD 3.0.2 for components without adequate DC power. which would have Required Action Completion Times shorter than 2 hours2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months . is acceptable because of:

a. The potential for decreased safety by requiring a change in unit conditions (i.e .. requiring a shutdown) while allowing stable operations to continue;

b. The potential for decreased safety by requiring entry into numerous applicable Conditions and Required Actions for components without DC power and not providing sufficient time for the operators to perform the necessary evaluations and actions for restoring power to the affected train: and

c. The potential for an event in conjunction with a single failure of a redundant component.

The 2 hour2.314815e-5 days 5.555556e-4 hours 3.306878e-6 weeks 7.61e-7 months Completion Time for DC buses is consistent with Regulatory Guide 1.93 (Ref. 3).

(continued)

PALO VERDE UNITS 1.2.3 B 3.8.9-6 REVISION 63

Distribution Systems -Operating B 3.8.9 BASES ACTIONS D.1 and D.2 (continued)

If the inoperable distribution subsystem cannot be restored to OPERABLE status within the required Completion Time, the unit must be brought to a MODE in which the LCD does not apply. To achieve this status, the unit 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 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.

E.1 Condition E corresponds to a level of degradation in the electrical distribution system that causes a required safety function to be lost. When more than one Condition is entered, and this results in the loss of a required safety function, the plant is in a condition outside the accident analysis. Therefore, no additional time is justified for continued operation.

LCD 3.0.3 must be entered immediately to commence a controlled shutdown.

SURVEILLANCE SR 3.8.9.1 REQUIREMENTS This Surveillance verifies that the AC, DC, and AC vital instrument bus electrical power distribution systems are functioning properly, with the required circuit breakers closed and the buses energized. The correct breaker alignment ensures the appropriate separation and independence of the electrical divisions is maintained, and the appropriate voltage is available to each required bus.

The verification of proper voltage availability on the buses ensures that the required voltage is readily available for motive as well as control functions for critical system loads connected to these buses. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.

(continued)

PALO VERDE UNITS 1,2,3 B 3.8.9-7 REVISION 63

Distribution Systems -Operating B 3.8.9 BASES REFERENCES 1. UFSAR. Chapter 6.

2. UFSAR. Chapter 15.

3. Regulatory Guide 1.93. Revision 0. December 1974.

Table B 3.8.9-1 (Units 1, 2, and 3)

TYPE VOLTAGE TRAIN A TRAIN B 4160 v ESF Bus PBA-S03 ESF Bus PBB-S04 480 v Load Centers Load Centers PGA-L31. PGA-L33. PGB-L32. PGB-L34.

AC safety PGA-L35 PGB-L36 buses 480 v Motor Control Centers Motor Control Center PHA-M31. PHA-M33. PHB-M32. PHB-M34.

PHA-M35. PHA-M37 PHB-M36. PHB-M38 CHANNEL A CHANNEL C CHANNEL B CHANNEL D Control Center Control Center *Contra l Center Control Center PKA-M41 PKC-M43 PKB-M42 PKD-M44 DC buses 125 v Distribution Distribution Distribution Distribution Panel Panel Panel Panel PKA-D21 PKC-D23 PKB-D22 PKD-D24 CHANNEL A CHANNEL C CHANNEL B CHANNEL D AC vital 120 v instrumen Distribution Distribution Distribution Distribution Panel Panel Panel Panel buses PNA-D25 PNC-D27 PNB-D26 PND-D28 NOTE: Each train of the electrical power distribution system is comprised of the independent AC. DC. and AC vital instrument bus subsystems.

PALO VERDE UNITS 1.2.3 B 3.8.9-8 REVISION 63

PVNGS Technical Specification Bases (TS Bases)

Revision 63 Replacement Pages and Insertion Instructions The following LDCRs are included in this change:

Technical Specification Bases Revision 63 includes the following changes:

LDCRs 10-B010 and 12-B001 reflect the removal of various post-accident sampling (PASS) valves. The removal of the components was authorized by License Amendment 136, dated September 28, 2001. 'Components have been removed over time based upon business considerations.

LDCR 14-B002 reflects installation of the inverter modification which includes swing inverters that can be credited as 'required' inverters, if available. Changes are reflected in the TS Bases descriptions of LCOs 3.8.7, Inverters- Operating, and 3.8.8, Inverters- Shutdown.

" LDCRs 14-B007 and 16-B001 reflect conforming changes to the TS Bases to implement License Amendment 197, dated February 19, 2016, that removed second Required Action Completion Times forTS LCOs 3.7.5, Auxiliary Feedwater System, 3.8.1, AC Sources- Operating, and 3.8.9, Distribution Systems- Operating.

LDCR 15-B002 added clarification to the TS Bases description of_the Applicable Safety Analyses section of TS 3. 7.17, Spent Fuel Assembly Storage. Specifically, a new sentence was added to indicate that core operating conditions, such as temperature and boron concentration, influence plutonium production which may increase discharged fuel reactivity. This clarification was an action from CRDR 4365817.

LDCR 15-B006 provides clarification of various TS Bases descriptions.

Specifically, the clarifications are the result of Condition Report 15-00354 which identified the need for the clarifications toTS Bases sections 3.1.2, 3.1.5, 3.2.2, 3.2.3 and 3.3.3 to improve reader understanding.

LDCR 15-B005 removes Conditions 1 and 2 from the TS Bases description of Surveillance Requirement (SR) 3.1.6.1, as the information is contained in Calculation 13-JC-SF-0202, Revision 7. The calculation serves as the source document for procedure guidance for how to perform SR 3.1.6.1.

This change is consistent with standard TS Bases protocols, in that the TS Bases typically describe the SR and why it is important, but not specifically how the test is to be performed.

LDCR 15-B004 restores the TS Bases description regarding spent fuel pool storage rack cell locations that are required to be vacant. This change was a corrective action from CRDR 4627526.