ML18038B834

Proposed Tech Specs Re Extended EDG Allowed Outage Time

ML18038B834
Person / Time
Site:	Browns Ferry
Issue date:	03/12/1997
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML18038B833	List: ML18038B832 ML18038B834
References
NUDOCS 9703260048
Download: ML18038B834 (47)

Text

ENCLOSURE 1

TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

UNITS 2 and 3 PROPOSED TECHNICAL SPECIFICATIONS (TS)

CHANGE TS-376 DESCRIPTION AND EVALUATION OF THE PROPOSED CHANGE DESCRIPTION OF THE PROPOSED CHANGE Changes are requested to current BFN TS and for the proposed conversion package to Improved Standard Technical Specifications (ISTS) format (TS-362 submit:ted September 6,

1996) for Units 2 and 3 to provide for a 14-day Allowed Outage Time (AOT) for the Emergency Diesel Generators (EDG).

The specific changes are described below:

Current TS pages 3.9/4.9-9 (Unit 2) and 3.9/4.9-8 (Unit 3).

In paragraph

3. 9.B. 3 (Unit 2) and 3. 9.B. 2 (Unit 3),

14 days is substituted for the existing 7 days as shown in the mark-up pages in Enclosure 2.

2.

ISTS page 3.8-3 for Units 2 and 3.

In the COMPLETION TIME for REQUIRED ACTION 3.8.1.B.4, 14 days is substituted for the existing 7 days as shown in enclosure 4.

3.

ISTS Bases pages B 3.8-9 and B 3.8-12 for Units 2

and 3

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In t:he ACTIONS A.2 and B.4 Bases for Section B 3.8.1 14 days is substituted for the existing 7 days.

Also, the Bases discussion on cumulative COMPLETION TIME requirements is modified to account for an extended EDG AOT.

The 14-day cumulative COMPLETION TIME remains the same.

Refer to the marked-up TS pages in Enclosure 4 for the exact changes.

9703260048 9703i2 PDR ADQCK 05000260 P

PDR

II.

REASON FOR THE PROPOSED CHANGE The purpose of providing a 14-day EDG AOT is to provide additional flexibilityfor performing maintenance on EDGs.

Xn general, the 7-day AOT in current TS and reiterated in the TS-362 ISTS submittal is adequate for planned and unplanned EDG maintenance.

EDGs, however, are subject to a

vendor recommended preventive maintenance (PM) program which involves several -periodic service and inspection activities including a major PM outage every 12 years.

BFN EDGs were manufactured by General Motors Electromotive Division (EMD) and the PM program is based on EMD recommendations The 12-year PM will start in the Fall of 1997 and continue into Spring 1998 for all eight BFN EDGs, and will require an extensive diesel engine disassembly including removal of

pistons, cylinder liners, and connecting rods.

Based on industry experience, the 12-year PM for each diesel is estimated to require thirteen days on a two 8-hour shift per day work schedule.

This is equivalent to a ten-day around-the-clock shift schedule.

Neither work schedule includes excess contingency time for the remedy of unexpected problems discovered during the maintenance.

TVA has considered scheduling the 12-year PM outages during refueling outages.

However, no more than two EDGs can be serviced within a single standard length refueling outage without extending the outage since to minimize shutdown risk during refueling, it is desirable that only one EDG be removed from service at a time.

Also, there are manpower constraints since EDG maintenance is performed by a limited number of experienced craftsmen due to the specialized nature of the maintenance.

This manpower limitation likewise restricts working on more than one EDG at a time.

Partitioning of 12-year EDG maintenance into separate outages is not considered a desirable option since this practice effectively removes the EDGs from service for a longer period of time than if the maintenance is performed as a continuum activity.

This is because setup and restoration tasks associated with the maintenance are often duplicative, and must be repeated each time the EDGs undergo maintenance.

Also, we believe that the likelihood

of work errors increases for multiple outages due to the increased number of evolutions.

For these

reasons, overall risk is reduced by completing the 12-year PM during single EDG outages.

Additionally, previous work experience indicates that shorter EDG outages can be achieved by performing preventive maintenance while operating since work resources are focused on a single objective (e.g.,

EDG maintenance).

This focus results in better planning of work, dedicated manpower allocation, and greater resource availability for contingency work.

For these reasons, it is desirable to be able to perform EDG maintenance during power operations.

Except for the 12-year EDG PM activities, the current 7-day AOT is generally sufficient to accommodate scheduled and unscheduled EDG maintenance.

However, a 14-day AOT is also justifiable as a contingency provision for major unexpected EDG failures for the reasons discussed in the following safety analysis.

It is expected this AOT would seldom be used since EDG operating experience indicates major failures are uncommon.

In summary, a longer AOT is needed to accommodate the vendor recommended 12-year EDG PM activities and is desirable to provide additional flexibility, if needed, for major EDG corrective maintenance activities.

III.

SAFETY ANALYSIS A 14-day EDG AOT is justified for the following reasons.

First, the TVA off-site power distribution system supplying BFN has diversity and provides reliable service.

Second, the on-site auxiliary and standby power systems have redundancy and compensate for EDGs that are out-of-service.

Third, BFN uses proceduralized scheduling and work control methods that minimize equipment AOT times and carefully control other maintenance and testing activities during EDG outages.

Fourth, since Unit 1 is in an indefinite nonoperational

status, additional EDGs are available for service on Units 2 and 3 for mitigating Loss of Off-Site Power (LOOP) events.

Xn addition, TVA has performed a

Probabilistic Safety Assessment (PSA) evaluation of the proposed TS change confirming the change as non-risk significant.

Description of Off-Site Power System The TVA transmission system is considered a diverse and dependable system due to the large generating capacity of TVA, the high number of transmission lines, and multiple interconnections.

This results in a highly stable and reliable off-site power supply system for BFN.

During BFN's 23 years of operation, there has never been a

complete loss of off-site power event.

Off-site power is delivered to the site via seven 500-kV and two 161-kV transmission lines.

These lines feed a

500-kV switchyard and a 161-kV switchyard as described in detail in Chapter 8.3 of the BFN Updated Final Safety Analysis Report (UFSAR).

The 500-kV switchyard includes seven line bays and three transformer bays, and is designed to minimize the effects of the failure of individual items of equipment such that any single probable event would not prevent the 500-kV system from providing off-site power.

The 500-kV yard has two main bus sections which are physically separated.

4.16-kV station service is provided via the unit Main Transformers and two Unit Station Service Transformers on each unit.

Off-site power is also received from the 161-kV TVA grid via two separate transmission lines, the Trinity and Athens lines.

The 161-kV switchyard includes four line bays with physically separated feeders to Common Station Service Transformers which step down the voltage to station service levels (4.16-kV).

The large number of 500-kV and 161-kV transmission lines, and the physical separation of the lines and transformer bays minimizes the likelihood of power loss due to loss of transmission lines.

Transmission system transient stability st:udies are periodically performed which include an analysis of the" effects of a three-phase fault on a generator terminal during which the unit is disconnected automatically from the system as a result of a disturbance, the loss of TVA's largest generating unit, and the loss of a BFN unit.

These studies show the transmission system remains stable with negligible disturbance to the off-site power system.

Similarly, steady-state studies show the 500-kV and 161-kV net.works are capable of supplying off-sit:e power

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requirements for normal,

shutdown, and accident conditions.

Due to the large number of diverse generating units and strong interconnections, the likelihood of the transmission system causing the loss of all off-site power is considered to be extremely remote.

The BFN Probabilistic Safety Assessment (PSA) uses a loss of off-site power frequency of 3.39 E-02 per year for modeling purposes.

This value is based on generic industry data with plant specific Bayesian updates.

As noted previously, BFN has never experienced a

complete loss of off-site power in 23 years of operation.

Description of On-Site Power System The on-site distribution of power is described in UFSAR Chapter 8.4.

During normal operation station auxiliary power is provided by the main generator through the Unit Station Service Transformers.

If the unit is not operating, auxiliary power is provided from the 500-kV switchyard through the Main Transformer and Unit Station Service Transformers.

Auxiliary power is also available from the 161-kV system via the two Common Station Service Trans formers.

For Units 1 and 2, failure of a preferred off-site circuit from the 500-kV switchyard will result in an automatic transfer of safety-related loads to the alternate units'nit Station Service Transformers if voltage is available.

Otherwise, they will transfer along with the nonsafety-related loads to the Common Station Service Transformers.

For Unit 3, failure of the 500-kV source will result in the transfer of both safety and non-safety loads to the Common Station Service Transformers.

If no off-site power is available, safety-related loads only will transfer to the standby EDGs.

The large number of available power sources, switchyard arrangement, and physical separation of transmission lines,

buses, and station transformers provides a highly redundant and reliable off-site and on-site power system.

Description of Off-Site and On-Site Power System Changes Recent modifications to the power distribution system which further improve the reliability of the power distribution system include:

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Completion of the Limestone 161-kV substation.

This facility improves the stability and capability of the 161-kV off-site supply.

b).

Installation of load tap changers on the Common Station Service Transformers which provides better voltage regulation of the. plant distribution system when supplied from the 161-kV off-site power supply.

c).

Load tap changers on Unit Station Service Transformers have been replaced with faster acting models.

This provides faster voltage recovery during motor starting transients and better overall voltage regulation.

TVA's Transmission Power Systems organization performs comprehensive Transmission System Studies for all TVA nuclear plants on a three-year cycle.

These studies include load flow analyses and transient stability studies, and are performed in accordance with the industry accepted guidelines for transmission system studies.

This periodic study verifies the capability of off-site power supplies to each nuclear plant.

The periodic evaluation for BFN will be completed in 1997.

It is expected this analysis will show improved transmission system stability and capability due to the added system generating capacity resulting from the addition of Watts Bar Unit 1 and BFN Unit 3 to the operating grid since the last study.

Station Blackout Off-Site Power Group Categorization The redundancy of the TVA transmission system coupled with a diverse off-site power supply and site distribution system provides highly reliable sources of auxiliary power which, in turn, minimizes the potential for LOOP events.

This configuration, as expected, results in a favorable off-site power categorization for BFN for 10 CFR 50.63 Station Blackout (SBO) rule applicability as summarized below.

Nuclear UtilityManagement and Resource Council (NUMARC)87-000 "Guidelines for and Technical Basis for NUMARC Initiatives for Addressing Station Blackout at Light Water Reactors" provides criteria for characterizing the susceptibility of plants to LOOP events for the SBO rule.

Application of the criteria results in categorizing plants into Off-site Power Design Characteristic Groups of Pl, P2,

or P3 which go from least to most susceptible to LOOP events respectively.

This Off-site Power Design Characteristic Group is a function of three separate subgroup factors.

These are the Off-site Power System Independence (I) Group, the Severe Weather (SW)

Group, and the Extremely Severe Weather (ESW)

Group.

The I Group relates to the site susceptibility to grid-related LOOP events.

The ESW and SW groups relate to the likelihood of LOOP events due to abnormal weather.

NUMKRC 87-000 'criteria classifies BFN as an Independence Group I 4 category site which is the least susceptible category to LOOP events due to grid-related disturbances.

This favorable categorization is based on physical separation of BFN switchyards and off-site transmission lines.

The ESW category relates to the likelihood of a LOOP event due to extreme weather conditions.

ESW is based on the probability of experiencing wind speeds greater than 125 miles per hour at the site.

BFN is categorized as an ESW Group 1 site which places BFN in the category of plants least likely to lose off-site power because of extremely severe weather.

The SW Group relates to the likelihood of a LOOP event due to severe weather conditions and is a combined factor based on snowfall, tornado frequency, severe

storms, and salt spray.

This factor is also influenced by having multiple right-of-ways for transmission lines.

The SW category for BFN is Group 2 which is the second most favorable category out of five possible groups with respect to the probability of losing off-site power due to severe weather.

These three factors combine to result in an Off-site Power Design Characteristic Group of Pl for BFN which is the category of plants with the least susceptibility for LOOP events.

NRC has previously accepted this characterization for BFN as discussed in the July 11,

1991, Safety Evaluation Report for the SBO rule.

El-7

Description of On-Site Emergency Power System and Station Blackout Category The BFN emergency on-site power (Standby Alternating Current (AC)) system consists of eight

EDGs, and the associated distribution and transfer systems.

The shutdown bus arrangement and distribution system for the EDGs is

'described and shown in detail in Chapter 8.5 of the UFSAR.

The EDGs are arranged such that four EDGs provide standby power to Units 1 and 2, and four EDGs are in standby service for Unit 3.

Through use of 4-kV Shutdown Buses 1 and 2, and the 4-kV Bus Tie Board, any EDG can be cross connected with any 4-kV Shutdown Board.

These alignment actions can be performed from the control room for the Shutdown Buses or from an electrical board room for Bus Tie Board transfers.

This arrangement provides considerable flexibilityin supplying emergency AC power.

With regard to the SBO rule, BFN has been categorized by NRC as an Emergency Alternating Current (EAC) Category "C"

plant

(

Reference:

Letter from NRC to TVA dated September 16, 1992).

This classification was based on requirements for shutting down all three units for an extended period following a LOOP.

This "C" category translates to a

SBO coping duration of four hours and an EDG target reliability of.95 for BFN.

As noted above, the "C" EAC category is based on simultaneously shutting down all three BFN units during a LOOP event.

However, since BFN Unit 1 is in an indefinite nonoperational

status, the facility can essentially be treated as two-unit plant, each with four EDGs available for service.

There are some shared systems that are powered from buses on different units, primarily ventilation and service water systems.

Nonetheless, with only Units 2 and 3 operating, for SBO categorization

purposes, four EDGs can be considered dedicated for standby service for Unit 2 and four separate EDGs dedicated on Unit 3.

This two-unit configuration increases the number of EDGs dir'ectly available for Unit 2 service since the need to be able to shutdown Unit 1 is not a factor.

This, in turn, reduces the likelihood that a Unit 3 EDG would be needed to be aligned to Unit 1/2 shutdown boards following a LOOP to

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assist Unit 2 shutdown activities since Unit 2 has EDGs previously committed to Unit 1 now available.

Also, with only two units operating, only two total EDGs are required to maintain the (two-unit) plant in a safe shutdown condition for the intermediate and long term periods after a

LOOP event or SBO event.

In the two-unit configuration,'

revised SBO EAC category of "A" (NUMARC 1-of-3 dedicated EDG configuration) is justifiable which translates to a less stringent 2-hour coping duration indicative of the improved capability to mitigate LOOP events.

TVA is not. proposing a change to our current commitment to a 4-hour SBO coping duration.

However, for the purposes of approving an extended EDG AOT TS for Units 2 and 3 only, it is appropriate that the increased number of available dedicated EDGs that result from a two-unit configuration be considered.

Prior to returning Unit 1 to operation, TVA will provide additional justification for extending EDG AOTs for operating three units.

Accordingly, Unit 1 TS changes are not being submitted at this time.

TVA has also performed several modifications which improve BFN's capability for shutting down the units without AC power and which provide added battery capacity.

Specifically, the 250-V DC Safety-Related Unit Batteries and 250-V DC Control Power Batteries have been upgraded.

Two new Station Batteries (non-safety related batteries) have been installed.

In concert with this modification, several non-safety loads previously carried by the safety-related Unit Batteries have been transferred to the new Station Batteries.

These transferred loads include a

major battery load, the Unit Preferred AC Motor Generator alternate supply for both Units 2 and 3.

Refer to Chapter 8.6 of the UFSAR for a detailed description of the 250-V power distribution system.

Planning of Maintenance BFN uses a

PSA based dual unit maintenance matrix to provide a basis for planning maintenance activities.

The matrix identifies combinations of equipment that, if out-of-service simultaneously, would increase risk above a

predetermined criteria and should thus be avoided.

These controls are proceduralized in the site work control procedure, SSP-7.1, "Work Control."

The matrix restrictions are in addition to limitations for inoperable

equipment combinations in TS.

For instance, with an inoperable

EDG, TS do not allow other EDGs on the same unit to be out-of-service simultaneously and also prohibit removal of the major low pressure injection systems (Residual Heat Removal (RHR) and Core Spray) from service.

The dual unit maintenance matrix places additional restrictions on removing PSA sensitive equipment from service (such as selected Battery Boards and the adjacent unit RHR cross-tie pumps) when an EDG is inoperable.

Thus, application of the maintenance matrix provides an additional administrative control to restrict removal of risk sensitive equipment from service.

SSP-7.1 also requires that all modification activities which involve voluntary entry into a TS Limiting Conditions of Operation (LCO) be carefully planned to minimize equipment unavailability durations.

This scheduling process makes sure resources and materials are staged, work documents are prepared, and contingency plans are in place.

Detailed work schedules are prepared which lay out critical path activities, and coordinate resources and key evolutions.

These planning activities have the net effect of minimizing equipment outage times.

BFN has additional administrative controls in place related specifically to the entry of TS LCOs for EDGs.

In particular, a separate evaluation per Site Standard Practice (SSP)-12.51 Appendix B,

" Assessment of LCOs Related to Diesel Generator and Off-site Power Source Inoperability" must be performed prior to the LCO entry.

This evaluation verifies the availability of alternate train safety equipment and TS required off-site power sources.

PSA Analysis BFN currently uses a dual unit PSA model to model the operation of Units 2 and 3.

The dual unit PSA is a

refinement of the multi-unit (all three units operating)

PSA previously submitted to NRC on April 14, 1995.

The mean Core Damage Frequency (CDF) using the dual unit model is 5.39E-06 for Unit 2 and 9.19E-06 for Unit 3.

For reference, the mean CDF for Unit 2 in the multi-unit PSA was 2.8E-05.

Unit 3 CDFs were not calculated in the multi-unit model.

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A PSA. sensitivity evaluation using the dual unit model was performed to quantify the relative risk factors associated with a 14-day EDG AOT.

To provide a

PSA comparison, 14 days of additional unavailability per diesel per year was added to the EDG unavailability currently used in the PSA.

This new assumption is equivalent to all eight EDGs having an extra 14-day outage each year.

The unit-specific PSA models currently assume 14.8 days of unavailability per year per diesel and 24.8 days per year on the adjacent unit EDGs.

Actual EDG unavailability calculated on a 2-year rolling average basis is approximately

.018 (6.6 days/year) as of December 1996.

Planned outages (preventive maintenance and testing) account for about 80% of this unavailability.

The calculated CDFs with an extra 14-day/year outage per EDG were 6.05E-06 for Unit 2 and 1.06E-05 for Unit 3, which represent changes of 12% and 15% respectively.

The change in CDF is small and considered non-risk significant change per the PSA Applications Guide, EPRI TR-105396.

These CDF numbers are also conservative since the unavailability of other plant equipment is assumed on a random basis in the calculation per routine PSA practice, and no credit is taken for restricting the removal of important equipment from service as prohibited by TS or by use of the risk-based maintenance matrix.

Adding an extra 14 days/year is also a conservative calculational assumption for the following reasons.

Of the planned maintenance activities, only the 12-year PM outages necessitate an extended outage.

Regarding the likelihood of an extended EDG corrective maintenance

outage, our operating history indicates EDGs rarely require extended outages.

For reference, since the restart of Unit 2 in 1991 (past 'five years of operation),

there has been only one case when the existing 7-day AOT was not sufficient to accommodate forced EDG maintenance'dditionally, BFN has several performance goals associated with the EDGs which emphasize minimizing EDG unavailability and maximizing reliability.

For instance, the target reliability for EDGs under the SBO rule is.95.

Our Maintenance Rule EDG unavailability performance criteria is established at

.0342 (12.5 days/year).

BFN also has set an EDG target unavailability goal of below.020 related to Institute of Nuclear Power Operations performance goals for

safety equipment..

From these goals, it is clear that there is considerable emphasis on maximizing EDG availability which can only be achieved by minimizing EDG outages.

Therefore, while the proposed TS relaxes the current 7-day AOT, it is not expected that real EDG unavailability is apt to significantly rise due to the emphasis placed on meeting the various EDG performance goals.

IV.

NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION TVA has concluded that operation of BFN in accordance with the proposed change to the TS does not involve a significant hazards consideration.

TVA'g conclusion is based on it's evaluation, in accordance with 10 CFR 50.91(a)(1),

of the three standards set forth in 10 CFR 50.92(c).

A.

The proposed amendment does not involve a significant increase in the probability or consequences of an accident previously evaluated.

The EDGs are designed as backup AC power sources in the event of loss of off-site power.

The proposed AOT does not change the conditions, operating configurations, or minimum amount of operating equipment assumed in the safety analysis for accident mitigation.

No changes are proposed in the manner in which the EDGs provide plant protection or which create new modes of plant operation.

In addition, a

PSA evaluation concluded that the risk contribution of t:he AOT extension is non-risk significant.

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

The proposed amendment does not create the possibility of a new or different kind of accident from any accident previously evaluated.

The proposed change does not introduce any new modes of plant operation or make physical changes to plant systems.

Therefore, extension of the allowable AOT for EDGs does not create the possibility of a new or different accident.

C.

The proposed amendment does not involve a significant reduction in a margin of safety.

BFN's emergency AC system is designed with sufficient redundancy such that an EDG may be removed from service for maintenance or testing.

The remaining EDGs are capable of carrying sufficient electrical loads to satisfy the UFSAR requirements for accident mitigation or unit safe shutdown.

Increasing the allowable EDG AOT will likely increase EDG unavailability on the average since it expected that the provision would occasionally be used to accommodate unplanned major EDG maintenance.

However, a conservative PSA evaluation concluded that the risk contribution of the AOT extension is non-risk significant.

For the 12-year EDG PM work activity, it is expected that the proposed TS would actually reduce unavailability since multiple outages would not be necessary to accomplish the maintenance activity.

The proposed change does not impact t:he redundancy or availability requirements of off-site power supplies or change the ability of the plant to cope with station blackout event:s.

For these

reasons, the proposed amendment does not involve a significant reduction in a margin of safety.

ENVIRONMENTAL IMPACT CONSIDERATION The proposed change does not: involve a significant hazards consideration, a significant change in the types of or significant increase in the amounts of any effluents that may be released off-site, or a significant increase in individual or cumulative occupational radiation exposure.

Therefore, the proposed change meets the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9)

Therefore, pursuant to 10 CFR 51.22(b),

an environmental assessment of the proposed change is not required.

Commitments Made in This Submittal Prior to the returning Unit 1 to operation, TVA will provide additional justification for extending EDG AOTs for operating three units.

ENCLOSURE 2

TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

UNITS 2 AND 3 PROPOSED TECHNICAL SPECIFICATIONS (TS)

CHANGES TS-376 MARKED PAGE S I.

AFFECTED PAGE LIST Unit 2 page 3.9/4.9-9 Unit 3 page 3.9/4.9-8 II.

MARKED PAGES See attached.

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0 LIMITIHG COHDITIOHS FOR OPERATIOH SURVEILLAHCE REQUIRENEHTS NOY is 1988 3.9.B.

W o

abc 4.9+B.

0 W

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ab 3 ~

When one of the units 1

and 2 diesel generator is IHOPERABLE, continued REACTOR POWER OPERATIOH is permissible during the succeeding

days, at 2 offsite power sources are available as specified in 3.9.A.l.c and all of the CS, RHR (LPCI and containment cooling)

systems, and the remaining three units 1 and 2 diesel generators are OPERABLE.

If this requirement cannot be met, an orderly shutdown shall be initiated and the reactor shall be in 'the COLD SHUTDOWH COHDITIOH within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

3.

When one of the units 1 and 2 diesel generators is found to be IHOPERABLE, all of the remaining diesel generators shall be demonstrated to be OPERABLZ within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and power availability for the associated boards shall be verified within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter.

4.

When one units 1 and 2 4-kV shutdown board is IHOPERABLZ, continued REACTOR POWER OPERATIOH is permissible for a period of 5 'days provided that 2 offsite power sources are available as specified in 3.9.A.l.c and the remaining 4-kV shutdown boards and associated diesel generators, CS, RHR (LPCI and containment cooling)

systems, and all 480-V emergency power boards are OPERABLE. If this requirement cannot be

met, an orderly shutdown shall b'e initiated and the reactor shall be in the COLD SHUTDOWH COHDITIOH within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

4.

When one 4-kV shutdown board is found to be

. IHOPERABLZ, all diesel generators associated with the remaining 4-kV

'hutdown boards shall be demonstrated to be OPERABLE within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and power availability for the remaining 4-kV shutdown boards shall be verified within 1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter.

BFH Unit 2 3.9/4.9-9 AMENDMENTNO. 15 C

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4 UXILIARYELEC RICAL SYSTEM I ITING CO IONS FO OPE T ON AUG i9 1988 C

UI ME S

3.9.B.

0 eration with I o erable gguufm ent 4.9.B.

0 e at on with no erable

~ui ment Whenever the reactor is in STARTUP mode or RUN'mode and not in a Cold Condition, the availability of electric power shall be as specified in 3.9.A except as specified herein.

1.

From and after the date that only one offsite power source is available, reactor operation is permissible under this condition for seven days.

1.

When only one offsite power source is OPERABLE, all unit 3 diesel generators must be demonstrated to be OPERABLE within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and power availability for the associated boards shall be verified within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8

hours thereafter.

2.

When one unit 3 diesel generator (3A, 3B, 3C, or 3D) is inoperable, continued reactor operation is permissible during the succeedi g)days, provided t two oFfsite power sources are available as specified in 3.9.A.l.c.

and all of the CS, RHR (LPCI and containment cooling) systems, and the remaining three unit 3 diesel generators are OPERABLE. If this require-ment cannot be met, an orderly shutdown shall be initiated and the reactor shall be shut down and in the Cold Condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

2.

When one unit 3 diesel generator is found to be inoperable, all of the remaining unit 3 diesel generators shall be demonstrated to be OPERABLE within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and power availability for the associated boards shall be verified within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter.

BFH Unit 3

3. 9/4. 9-8 NENOMENTHD. I 2 4

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ENCLOSURE 3 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

UNITS 2 AND 3 PROPOSED TECHNICAL SPECIFICATIONS (TS)

CHANGES TS-376 REVISED PAGES AFFECTED PAGE LIST Unit 2

page 3.9/4.9-9 Unit 3 page 3.9/4.9-8 II.

REVISED PAGES See attached.

3.9.B 4'.B.

3.

When one of the units 1

and 2 diesel generator is INOPERABLE, continued REACTOR POWER OPERATION is permissible during the succeeding 14 days, provided that 2 offsite po~er sources. are available as specified in 3.9.A.l.c and all of the CS, RHR (LPCZ and containment cooling)

systems, and the remaining three units 1 and 2 diesel generators are OPERABLE.

If this requirement cannot be met, an orderly shutdown shall be initiated and the reactor shall be in the COLD SHUTDOWN CONDITION within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

3.

When one of the units 1 and 2 diesel generators is found to be INOPERABLE, all of the remaining diesel generators shall be demonstrated to be OPERABLE within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and power availability for the associated boards shall be verified within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter.

4.

When one units 1 and 2

4-kV shutdown board is INOPERABLE, continued REACTOR POWER OPERATION is permissible for a period of 5 days provided that 2 offsite power sources are available as specified in 3.9.A.1.&

and the remaining 4-kV shutdown boards and associated diesel generators, CS, RHR (LPCI and containment cooling)

systems, and all 480-Y emergency power boards are OPERABLE'f this requirement cannot be

met, an orderly shutdown shall be initiated and the reactor shall be in the COLD SHUTDOWN CONDITION within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

4.

When one 4-kV shutdown board is found to be INOPERABLE, all diesel generators associated with the remaining 4-kV shutdown boards shall be demonstrated to be OPERABLE within 24

hours, and power availability for the remaining 4-kV shutdown boards shall be verified within 1 hours1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter.

BFN Unit 2 3.9/4.9-9

3.'3.B.

4.9.B.

Whenever the reactor is in STARTUP mode or RUN mode and not in a Cold Condition, the availability of electric power shall be as specified in 3'.A except as specified herein.

1.

From and after the date that only one offsite power source is available, reactor operation is permissible under this condition for seven days.

1.

When only one offsite power source is OPERABLE, all unit 3 diesel generators must be demonstrated to be OPERABLE within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and power availability for the associated boards shall be verified within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter.

2.

When one unit 3 diesel generator (3A, 3B, 3C, or 3D) is inoperable, continued reactor operation is permissible during the succeeding 14 days, provided that two offsite power sources are available as specified in 3.9.A.l.c.

and all of the CS, RHR (LPCI and containment cooling)

systems, and the remaining three unit 3

diesel generators are OPERABLE. If this requirement cannot be met, an orderly shutdown shall be initiated and the reactor shall be shut down and in the Cold Condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

2.

When one unit 3 diesel generator is found to be inoperable, all of the remaining unit 3 diesel generators shall be demonstrated to be OPERABLE within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, and power availability for the associated boards shall be verified within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and at least once per 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> thereafter.

BFN

'nit 3 3.9/4.9-8

ENCLOSURE 4

TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

UNITS 2 AND 3 PROPOSED IMPROVED STANDARD TECHNICAL SPECIFICATIONS (ISTS)

CHANGES TS-37 6 MAE~'D PAGE S I.

AFFECTED PAGE LIST Unit 2 and 3

page 3.8-3 Unit 2 and 3 Bases pages B 3.8-9 and B 3.8-12 II.

MARKED PAGE S See attached.

~

(

~

~

AC Sources Operating 3.8.1 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME B.

(continued)

BE 3.1 OR Determine OPERABLE Unit 1 and 2 DG(s) are not inoperable due to common cause failure.

24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> B.3.2 Perform SR 3.8. 1.2 for OPERABLE Unit 1

and 2 DG(s).

AND B.4 Restore Unit 1

and 2

DG to OPERABLE status.

24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> days AND 14 days from discovery of failure to meet LCO C.

One division of 480 V

C. 1 Restore required load shed logic division of 480 V

inoperable.

load shed logic to OPERABLE status.

7 days D.

One division of common accident signal logic inoperable.

D. 1 Restore required division of common accident signal logic to OPERABLE status.

7 days (continued)

BFN-UNIT 2 3.8-3 Amendment

AC Sources Operating B 3.8.1 BASES ACTIONS (continued)

"I chaps A.3 Based on the diversity of AC electrical power sources, and the remaining redundancy and reliability, operation may continue in Condition A for a period that should not exceed 7 days.

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 plant 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 7 day Completion Time takes into account the capacity and capability of the remaining AC sources, reasonable time for repairs, and the low probability of a DBA occurring during this period.

The second Completion Time for Required Action A.3 establishes a limit on the maximum time allowed for any.

combination of required AC power sources to be inoperable during any single contiguous occurrence of failing to meet the LCO. If Condition A is entered while, for instance, a

DG is inoperable, and that DG is subsequently returned OPERABLE, the LCO may already have been not met or u days.

This situation could lead to a total of

ays, since initial failure to meet the LCO, to restore the offsite circuit.

At this time, a

DG could again become inoperable, the circuit restored

OPERABLE, and an additional allowed prior to complete restoration of the LCO.

The 14 day Completion Time provides a limit on the time allowed in a specified condition after discovery of failure to meet the LCO.

This limit is considered reasonable for situations in which Conditions A

and B are entered concurrently.

The "AND" connector between the 7 day and 14 day Completion Times means that both Completion Times apply simultaneously, and the more restrictive Completion Time must be met.

As in Required Action A.2, the Completion Time allows for an exception to the normal "time zero" for beginning the allowed outage time "clock."

This exception results in establishing the "time zero" at the time the LCO was initially not met, instead of at the time that Condition A was entered.

(continued)

BFN-UNIT 2 B 3.8-9 Amendment

J

AC Sources Operating B 3.8.1 BASES ACTIONS (continued) l09 B.4 Based on the diversity of AC electrical power sources, and the remaining redundancy and reliability, operation may continue in Condition B for a period that should not exceed days.

In Condition B, the remaining OPERABLE Dgs and offsite circuits are adequate to supply electr'c ower to the onsite Class 1E Distribution System.

The day Completion Time takes into account the capacity and capability of the remaining AC sources, reasonable time for

repairs, and low probability of a DBA occurring during this period.

The second Completion Time for Required Action B.4 establishes a limit on the maximum time allowed for any combination of required AC power sources to be inoperable during any single contiguous occurrence of failing to meet the LCO. If Condition B is entered while, for instance, an offsite circuit is inoperable and that circuit is subsequently restored OPERABLE, the LCO may already have been not met for up to 7 days.

This situation could lead to a

o al o ~ days, since initial failure to meet the

LCO, to restore t e DG.

At this time, an offsite circuit could again become ino e ble the DG restor

OPERABLE, and an additional llowed prior to co res ora

>on o e

The ay Completion Time rovides a limit on the time allowed in a specified condition after discovery of failure to meet the LCO.

This limit is considered reasonable for situations in which Conditions A and B are entered concurrently.

The "AND" connector between the 14 day Completion Times means that both Completion Times apply simultaneously, and the more restrictive must be met As in Required Action B.2, the Completion Time allows for an exception to the normal "time zero" for beginning the allowed outage time "clock."

This exception results in establishing the "time zero" at the time that the LCO was initially not met, instead of the time that Condition B was entered.

(continued)

BFN-UNIT 2 B 3.8-12 Amendment

~

g s

~

~,

4 H

,p t

j 1

P

'\\

AC Sources Operating 3.8.1 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME B,

(continued)

B.3. 1 Determine OPERABLE Unit 3 DG(s) are not inoperable due to common cause failure.

OR B.3.2 Perform SR 3.8.1.2 for OPERABLE Unit 3 DG(s).

AND 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 24 hours B.4 Restore Unit 3 DG to OPERABLE status'ays AND 14 days from discovery of failure to meet LCO C.

One division of 480 V

load shed logic inoperable.

C. 1 Restore required division of 480 V

load shed logic to OPERABLE status.

7 days D.

One division of common accident signal logic inoperable.

D. 1 Restore required division of common accident signal logic to OPERABLE status.

7 days (continued)

BFN-UNIT 3 3.8-3 Amendment

J 4

Cw

~

~

AC Sources Operating B 3.8.1 BASES ACTIONS p O<

Se Qhdh gg ~s A.3 (continued)

The 7 day Completion Time takes into account the capacity and capability of the remaining AC sources, reasonable time for repairs, and the low probability of a DBA occurring during this period.

The second Completion Time for Required Action A.3 establishes a limit on the maximum time allowed for any combination of required AC power sources to be inoperable during any single contiguous occurrence of failing to meet the LCO. If Condition A is entered while, for instance, a

DG is inoperable, and that DG is subsequently returned OPERABLE, the LCO may already have been not met or 7

This situation could lead to a total of

days, since initial failure to meet the LCO, to restore the offsite circuit.

At this time, a

DG could again become inoperable, the circuit restored

OPERABLE, and an additional f-21&ays) allowed prior to complete restoration of the LCO.

The 14 day Completion Time provides a limit on the time allowed in a specified condition after'iscovery of failure to meet the LCO.

This limit is considered reasonable for situations in which Conditions A

and B are entered concurrently.

The '"AND" connector between the 7 days and 14 day Completion Times means that both Completion Times apply simultaneously, and the more restrictive Completion Time must be met.

r As in Required Action A.2, the Completion Time allows for an exception to the normal "time zero" for beginning the allowed outage time "clock."

This exception results in.

establishing the "time zero" at the time the LCO was initially not met, instead of at the time that Condition A was entered.

B.1 To ensure a highly reliable power source remains with one Unit 3 DG inoperable, it is necessary to verify the availability of. the required offsite circuits on a more frequent basis.

This action ensures proper circuit continuity for the offsite AC electrical power supply to the onsite distribution network and availability of offsite AC electrical power.

However, if an offsite circuit is not (continued)

BFN-UNIT 3 B 3.8-9 Amendment

z~,

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

//days.

In Condition B, the remaining OPERABLE D

s and offsite circuits are adequate to supply electr'c power to the onsite Class lE Distribution System.

The day Completion Time takes into account the capaci y and capability of the remaining AC sources, reasonable time for

repairs, and low probability of a DBA occurring during this period.

The second Completion Time for Required Action B.4 establishes a limit on the maximum time allowed for any combination of required AC power sources to be inoperable during any single contiguous occurrence of failing to meet the LCO. If Condition B is entered while, for instance, an offsite circuit is inoperable and that circuit is subsequently restored OPERABLE, the LCO may already have been not met for up to 7 days.

This situation could lead to

tQdy, i

gati 1fi1 t

tl LC, to restore the DG.

At this time, an offsite circuit could again become inoperable G restored

OPERABLE, and an additiona allowed prior to co e restora

>on of t e LCO.

The 4 day Completion Time provides a limit on the time allowed in a specified condition after discovery of failure to meet the LCO.

This limit is considered reasonable for situations in which Conditions A and B are entered concurrently.

The "AND" connector between the n

ay Completion Times means that both Completion Times pply simultaneously, and the more restrictive must be met.

As in Required Action B.2, the Completion Time allows for an exception to the normal "time zero" for beginning the allowed outage time "clock."

This exception results in establishing the

."time zero" at the time that the LCO was initially not me;,

instead of the time that Condition B was entered.

C.1 With one division of Unit 3 480 V load shed logic inoperable, the reliability of the DGs is degraded, and the potential for the loss of the affected Unit 3 DG is increased with attendant potential challenge to plant safety

{continued)

BFN-UNIT 3 B 3.8-12 Amendment

>0

ENCLOSURE 5

TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT (BFN)

UNITS 2 AND 3 PROPOSED IMPROVED STANDARD TECHNICAL SPECIFICATIONS (ISTS)

CHANGES

TS-37 6 REVISED PAGES I.

AFFECTED PAGE LIST Unit 2 and 3

page 3.8-3 Unit 2 and 3 Bases pages B 3.8-9 and B 3.8-12 II.

REVISED PAGES See attached.

AC Sources Operating 3.8.1 ACTIONS CONDITION REQUIRED ACTION COMPLETION TIME B.

(continued)

B.3.1 OR Determine OPERABLE Unit 1 and 2 DG(s) are not inoperable due to common cause failure.

24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> B.3.2 Perform SR 3.8. 1.2 for OPERABLE Unit 1

and 2 DG(s).

AND B.4 Restore Unit 1 and 2

DG to OPERABLE status.

24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 14 days AND 14 days from discovery of failure to meet LCO C.

One division of 480 V

load shed logic inoperable.

C. 1 Restor e required division of 480 V

load shed logic to

~

OPERABLE status.

7 days D.

One division of common accident signal logic inoperable.

D. 1 Restore required division of common accident signal logic to OPERABLE status.

7 days (continued)

BFN-UNIT 2 3.8-3 Amendment

AC Sources -Operating 3.8.1 BASES ACTIONS (continued)

A.3 Based on the diversity of AC electrical power sources, and the remaining redundancy and reliability, operation may continue in Condition A for a period that should not exceed 7 days.

With one offsite circuit igoperable, 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 plant safety systems.

In this condition,

however, the remaining OPERABLE offsite circuit and DGs are adequate to supply electrical power to the onsite Class lE Distribution System.

The 7 day Completion Time takes into account the capacity and capability of the remaining AC sources, reasonable time for repairs, and the low probability of a DBA occurring during this period.

The second Completion Time for Required Action A.3 establishes a limit on the maximum time allowed for any combination of required AC power sources to be inoperable during any single contiguous occurrence of failing to meet the LCO. If Condition A is entered while, for instance, a

DG is inoperable, and that DG is subsequently returned OPERABLE, the LCO may already have been not met for more than 7 days.

This situation could-lead to a total of 21

days, since initial failure to meet the LCO, to restore the offsite circuit.

At this time, a

DG could again become inoperable, the circuit restored

OPERABLE, and an additional time period allowed prior to complete restoration of the LCO.

The 14 day Completion Time provides a limit on the time allowed in awpecified condition after discovery of failure to meet the LCO.

This limit is considered reasonable for situations in which Conditions A and B are entered concurrently.

The "AND" connector between the 7 day and 14 day Completion Times means that both Completion Times apply simultaneously, and the more restrictive Completion Time must be met.

As in Required Action A.2, the Completion Time allows for an exception to the normal "time zero" for beginning the allowed outage time "clock."

This exception results in establishing the "time zero" at the time the LCO was initially not met, instead of at the time that Condition A was entered.

BFN-UNIT 2 B 3.8-9 (continued)

Amendment

AC Sources -Operating 3.8.1 BgSES ACTIONS (continued)

B.4 Based on the diversity of AC electrical power sources, and the remaining redundancy and reliability, operation may continue in Condition B for a period that should not exceed 14 days.

In Condition B, the remaining OPERABLE DGs and offsite circuits are adequate to supply electrical power to the onsite Class 1E Distribution System.

The 14 day Completion Time takes into account the capacity and capability of the remaining AC sources, reasonable time for

repairs, and low probability of a DBA occurring during this period.

The second Completion Time for Required Action B.4 establishes a limit on the maximum time allowed for any combination of required AC power sources to be inoperable during any single contiguous occurrence of failing to meet the LCO. If Condition B is entered while, for instance, an offsite circuit is inoperable and that circuit is subsequently restored OPERABLE, the LCO may already have been not met for up to 7 days.

This situation could lead to a total of 21 days, since initial failure to meet the

LCO,

[

to restore the DG.

At this time, an offsite circuit could again become inoperable, the DG restored

OPERABLE, and an additional time period allowed prior to complete restoration of the LCO.

The 14 day Completion Time provides a limit on the time allowed in a specified condition after discovery of failure to meet the LCO.

This limit is considered reasonable for situations in which Conditions A and B are entered concurrently.

The "AND" connector between the two 14 day Completion Times means that both Completion Times apply simultaneougy, and the more restrictive must be met.

As in Required Action B.2, the Completion Time allows for an exception to the normal "time zero" for beginning the allowed outage time "clock."

This exception results in establishing the "time zero" at the time that the LCO was initially not met, instead of the time that Condition B was entered.

BFN-UNIT 2 B 3.8-12 (continued)

Amendment

PA AC Sources Operating 3.8.1 AC3'IONS CONDITION RE(UIRED ACTION COMPLETION TIME B.

(continued)

B.3.1 Determine OPERABLE Unit 3 DG(s) are not inoperable due to common cause failure.

OR B.3.2 Perform SR 3.8. 1.2 for OPERABLE Unit 3 DG(s).

AND B.4 Restore Unit 3 DG to OPERABLE status.

24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> 24 hours 14 days AND 14 days from discovery of failure to meet LCO C.

One division of 480 V

load shed logic inoperable.

C. 1 Restore required

- division of 480 V

load shed logic to

~

OPERABLE status.

7 days D.

One division of common accident signal logic inoperable.

D.l Restore required division of common accident signal logic to OPERABLE status.

7 days (continued)

BFN-UNIT 3 3.8-3 Amendment

~'

AC Sources Operating 3.8.1 BASES ACTIONS A.3 (continued)

The 7 day Completion Time takes into account the capacity and capability of the remaining AC sources, reasonable time for repairs, and the low probability of a DBA occurring during this period.

The second Completion Time for Required Action A.3 establishes a limit on the maximum time allowed for any combination of required AC power sources to be inoperable during any single contiguous occurrence of failing to meet the LCO. If Condition A is entered while, for instance, a

DG is inoperable, and that DG is subsequently returned OPERABLE, the LCO may already have been not met for more than 7 days.

This situation could lead to a total of 21

days, since initial failure to meet the LCO, to restore the offsite circuit.

At this time, a

DG could again become inoperable, the circuit restored

OPERABLE, and an additional time period allowed prior to complete restoration of the LCO.

The 14 day Completion Time provides a limit on the time allowed in a specified condition after discovery of failure to meet the LCO.

This limit is considered reasonable for situations in which Conditions A and B are entered concurrently.

The "AND" connector.

between the 7

days and 14 day Completion Times means that both Completion Times apply simultaneously, and the more restrictive Completion Time must be met.

As in Required Action A.2, the Completion Time allows for an exception to the normal "time zero" for beginning the allowed outage time "clock."

This exception results in establishing the "4ime zero" at the time the LCO was initially not met, instead of at the time that Condition A

was entered.

B.l To ensure a highly reliable power source remains with one Unit 3 DG inoperable, it is necessary to verify the availability of the required offsite circuits on a more frequent basis.

This action ensures proper circuit continuity for the offsite AC electrical power supply to the onsite distribution network and availability of offsite AC electrical power.

However, if an offsite circuit is not continued)

BFN-UNIT 3 B 3.8-9 Amendment

C r

~t'r

gq yll 0

e I

AC Sources -Operating 3.8.1 BASES ACTIONS B.4 (continued) 14 days.

In Condition B, the remaining OPERABLE DGs and offsite circuits are adequate to supply electrical power to the onsite Class lE Distribution System.

The 14 day Completion Time takes into account the capacity and capability of the remaining AC sources, reasonable time for

repairs, and low probability of a DBA occurring during this period.

The second Completion Time for Required Action 8.4 establishes a limit on the maximum time allowed for any combination of required AC power sources to be inoperable during any single contiguous occurrence of failing to meet the LCO. If Condition B is entered while, for instance, an offsite circuit is inoperable and that circuit is subsequently restored OPERABLE, the LCO may already have been not met for up to 7 days.

This situation could lead to a total of 21 days, since initial failure to meet the

LCO, to restore the DG.

At this time, an offsite circuit could again become inoperable, the DG restored

OPERABLE, and an additional time period allowed prior to complete restoration of the LCO.

The 14 day Completion Time provides a limit on the time allowed in a specified condition after discovery of failure to meet the LCO.

This limit is considered reasonable for situations in which Conditions A and B are entered concurrently.

The "AND" connector between the two 14 day Completion Times means that both Completion Times apply simultaneously, and the more restrictive must be met.

As in Required Action 8.2, the Completion Time allows for an exception to the normal "time zero" for beginning the allowed outage time "clock."

This exception results in establishing the "time zero" at the time that the LCO was initially not met, instead of the time that Condition B was entered.

C.I With one division of Unit 3 480 V load shed logic inoperable, the reliability of the DGs is degraded, and the potential for the loss of the affected Unit 3 DG is increased with attendant potential challenge to plant safety BFN-UNIT 3 B 3.8-12 (continued)

Amendment

W

.a, V

t

~

T