2CAN069807, Application for Amend to License NPF-6,revising Surveillance Testing Requirements for Unit 2 Direct Current Electrical Distribution Sys & to Reflect Installation of New Inverters During Next Scheduled Refueling Outage

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Application for Amend to License NPF-6,revising Surveillance Testing Requirements for Unit 2 Direct Current Electrical Distribution Sys & to Reflect Installation of New Inverters During Next Scheduled Refueling Outage
ML20236G513
Person / Time
Site: Arkansas Nuclear Entergy icon.png
Issue date: 06/29/1998
From: Hutchinson C
ENTERGY OPERATIONS, INC.
To:
NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20236G515 List:
References
2CAN069807, 2CAN69807, NUDOCS 9807060280
Download: ML20236G513 (9)
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Entargy oporttions, Inc.

.AR 72801 Tel 50b858-4888 C. Randy Hutchinson Vrc PresdW June 29,1998 **'5" 2CAN069807 U. S. Nuclear Regulatory Commission Dm-* Control Desk Mail Station OPI-17 Washington, DC 20555

Subject:

Arkansas Nuclear One - Unit 2 Docket No. 50-368 License No. NPF-6 Technical Specification Change Request To Modify The DC Distribution Survedlance Requirements Gentlemen:

Attached for your review and approval is a proposed Technical Specification change request that revises the surveillance testing requirements for the Arkansas Nuclear One - Unit 2 (ANO-2) direct current (DC) electrical distribution system. ANO-2 is planning on modifying the 120 volt vital alternating current (AC) electrical distribution system by installing new inverters during the next scheduled refueling outage (2R13). The existing ANO-2 inverters are normally AC powered and automatically shift to DC power on a loss of the normal AC power supply. The inveners that will be installed dunng 2R13 will be powered from the 125 volt vital DC system at all times This modification will increase the normal 125 volt vital DC system loads by adding the inveners as a nonnal load.

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The power for each 125 volt vital DC system is normally supplied by its associated battery [

l charger. ANO-2 is in the process of replacing the vital DC battery chargers by plant i modi 6 cation to ensure all the battery chargers are of sufficient capacity to provide the l

wa== y current requirements for the normal 125 volt vital DC loads. The proposed changefC l

to speci6 cation 4.8.2.3.c.4 is required to ensure the new chargers are adequately tested to support the associated invener replacement. Additional proposed changes contained in the /

l st*=ch=*nt to this letter include an allowance to perform resistance measurements on the battery connections and a bases change to clarify one of the actions associated with specification 3.8.2.3.

The proposed change _has been evaluated in accordance with 10 CFR 50.91(a)(1) using criteria in 10 CFR 50.92(c) and it has been determined that this change involves no significant hazards considerations. The bases for these determinations are included in the attached submittal.

Entergy Operations requests that the effective date for this change be within 30 days of issuance and prior to the completion of refueling outage 2R13, currently scheduled for January 1999.

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s i U. S. NRC June 29,1998 2CAN069807 Page 2 Very truly y rs, l i CRH/rde Attachments l

To the best of my knowledge and belief, the statements contained in this submittal are I true.

SUBSCRIBED AND SWORN TO before a a Notary Public in and for *be l

County and the State of Arkansas, thisd_f day of date; ,1998./

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' Y Notary Psblic Y d H 4 ft M 9 h O

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My Commission Empires f7W' // #dd f

l l cc: Mr. Ellis W. Merschoff Regional Administrator U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 NRC Senior Resident Inspector Arkansas Nuclear One l P.O. Box 310 London, AR72847 Mr. William D. Reckley NRR Project Manager Region IV/ANO-1 & 2 U. S. Nuclear Regulatory Commission NRR Mail Stop 13-H-3 One White Flint North 11555 Rockville Pike Rockville, MD 20852 Mr. David D. Snellings Director, Division ofRadiation Control and Emergency Management Arkansas Department ofHealth 4815 West Markham Street l Little Rock, AR 72205 l

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1 ATTACHMENT 1Q 2CAN069807 4 PEOPOSED TECHNICAL SPECIFICATION AND RESPECTIVE SAFETY ANALYSES IN THE MATTER OF AMENDING l

LICENSE NO. NPF-6 ENTERGY OPERATIONS. INC.

ARKANSAS NUCLEAR ONE. UNIT TWO DOCKET NO. 50-368 i

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1 Attachments 2CAN069807

.Page1 of6

, DESCRIPTION OF PROPOSED CHANGES e . Technical Specification (TS) surveillance requirement (SR) 4.8.2.3.b.2 requires the battery banks for each of the 125 volt systems to be inspected to ensure that no visible corrosion exists at either the terminals or the connectors. SR 4.8.2.3.b.2 has been modified to allow the performance of resistance measurements on the . associated battery connections as en alternative means of fulfillmg the SR.

-e SR 4.8.2.3.c.4 has been modi 6ed by increasing the battery charger amperage limit from "at least 200 amperes at 2125 volts for at least 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />" to "2 300 amperes at a 125 volts for a 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />".

e The Bases for TS 3.8.2.3 Action "b" has been modified to indicate that when the battery is not on float, the pilot cell float voltage required by Table 4.8-2 is satisfied by verifying that the pilot cell voltage is above the required limit.

BACKGROUND The 125 volt vital direct current (DC) power system at ANO-2 is comprised of two redundant trains. Each train consists of a bus, a battery bank and a full capacity charger. The battery chargers are supplied from separate and redundant Class IE 480 volt AC power supplies which are designed to be energized automatically from their associated diesel generator in the event of a L coincident loss of the normal and preferred power sources. Each full capacity battery charger is l capable of supplying the normal DC loads on the associated DC bus while maintaining the battery l

in a charged condition.

The power required for the 125 volt vital DC system loads is normally supplied by its associated battery charger. The existing chargers will allow for float and equalim charging of the associated 125 voit battery and are adequate to supply the entire load connected to the respective battery bus l

L while keeping the associated battery in a fully charged condition. In addition to the individual bus battery chargers, an additional " swing" battery charger can be placed in service on either of the vital DC buses to replace its associated normal battery charger. During normal operation, the

' 125 volt vital DC system loads are powered from the battery chargers with the batteries floating on the system. The DC loads are automatically powered from the station batteries during a loss of the power supply to the associated battery charger. The 125 voit vital DC electrical system is described in section 8.3.2 of the ANO-2 Safety Analysis Report (SAR).

The investers (2Y-ll,2Y-13,2Y-22, and 2Y-24) are part of the 120 volt uninterruptible vital alternating. current (AC) power system that supplies power to the reactor protection and engineered safety features (ESF) instrumentation channels. This power supply system consists of four inverters and four distribution panels which provide an independent power source to each of the redundant protective channels. Essential equipment such as nuclear instruments and nuclear l auxihary mstruments are connected to these four redundant distribution panels (2RS-1, 2RS-2, l 2RS-3, and 2RS-4). These four channels are commonly referred to as the 120 volt vital AC L

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s / Amament to 2CAN069807 Page 2 of 6 system. The existing 120 voit vital AC power system is described in section 8.3.1.1.6 of the j

' ANO-2 SAR.

Backrround For The Battery Visual Inspection Change The existing ANO-2 TS battery inspection SR 4.8.2.3.b.2 provides an indication of physical l damage or abnormal deterioration that could potentially degrade battery performance by the performance of a "... visual corrosion check at either the terminals or the connectors." This surveillance is necessary to detect conditions that can cause power losses due to resistance heating at the associated battery connections. The frequency and methodology used for the visual )

inspection requirements are consistent with those . contained in NUREG-1432, " Standard i Technical Specifications for Combustion Engineering Plants". However, NUREG-1432 provides  ;

an additional option to satisfy this inspection requirement by the measurement of the resistance on  ;

the associated battery connections. The additional allowance is necessary because if corrosion is  !

found, a resistance measurement could be performed on the associated battery connections to {

provide an indication of physical damage or abnormal deterioration that could potentially degrade battery performance that is unquantifiable by the visual inspection.

Backgroupd For The Battery Charmer Amocrane Channe i The existing ANO-2 inverters are normally powered from their 480 volt normal AC source and ,

automatically shift to their 125 volt vital DC power supply on a loss of the normal AC power l supply. ANO-2 is scheduled to modify the 120 volt AC electrical distribution system by installing new inveners during the next scheduled refueling outage (2R13). The new inverters will not contain a rectifier circuit similar to the existing inverters and will therefore normally be powered from the 125 volt vital DC system. As a result of the invener replacement modification, the l normal 125 volt vital DC system loads will be increased by the addition of the inverters as a normal load. The increased DC system loads would exceed the capacity of the existing 200 ampere " swing" battery charger ifit were not replaced.

Prior to the inverter replacement during 2R13, ANO-2 will be replacing all three of the class IE DC battery chargers by a plant modification. The existing 400 ampere chargers for each of the Class IE DC systems are being replaced with chargers of the same model and 400 ampere design ,

capacity as those used to replace the " swing" charger. Once the battery charger modification is complete, two chargers will be available on each DC electrical train to supply the normal DC l loads and maintain the battery fully charged. The charger modification will add an additional class l

IE DC battery charger to the DC system to establish a standby charger for each DC train.

The existing design contains one charger for each of the two DC trains and a third " swing" charger that can be aligned for use on either tiain. Once the charger modification is complete, only one battery charger will be in service connected to its associated battery bus for each train and the second chrger for each train will be in standby. The standby battery charger on each train is designed to be placed in service manually.

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4 l Attachment to 2CAN069807 Page 3 of 6 This battery charger modification will satisfy the Regulatory Guide 1.32 requirement for the

' battery chargers to be sized to furnish electric energy for the largest combined demands of the various steady state loads while restoring the battery from the minimum charged state to the fully charged state, irrespective of the status of the plant during which these demands occur. The sizing of the new battery chargers with the proposed periodic testing requirement contained in SR 4.8.2.3.c.4 of 2 300 amperes will ensure these requirements are satisfied. The additional 100 amperes of battery charging capacity will ensure a faster battery recharge time and will allow sufficient capacity for potential load growth on the DC systems.

Baclurround For TS 3.8.2.3 Action "b" Bases Channe TS 3.8.2.3 Action "b" provides the required actions to be taken in the event that one of the required full capacity battery chargers are inoperable. Action "b" also requires the performance of SR 4.8.2.3.a.1 within one hour 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 for a loss of one of the full capacity chargers. Action "b" goes on to state that if any Category A limit in Table 4.8-2 is not met while the charger is inoperable, the associated battery is inoperable.

l The Category A limits in Table 4.8-2 specify the normal limits for electrolyte level, float voltage l

and specific gravity for each designated pilot cell. These limits will ensure the battery has sufficient capacity to perform its intended function. The batteries are verified to be within the Category A limits every 7 days as required by SR 4.8.2.3.a.1. TS 3.8.2.3 Action "b" requires the l associated battery to meet the Category A limits when one of the required full capacity chargers is inoperable. One of the Category A parameters required by Action "b" to be verified is the pilot cell floal voltage. When the associated charger is not connected to the associated battery bus, the associated battery and the associated pilot cell is no longer on float. When the associated battery ,

is not on float, the pilot cell voltage will be determined to be above the pilot cell floal voltage Category Alimit.

DISCUSSION OF CHANGE TS SR 4.8.2.3.b.2 requires the battery banks for each of the 125 volt systems to be inspected to ensure that no visible corrosion exists at either the terminals or the connectors. This SR has been modified to allow the present corrosion inspection, or the determination of the resistance readings on the associated battery connections. This additional allowance is consistent with the similar requirements contained in NUREG-1432, " Standard Technical Specifications for l Combustion Engineering Plants". The visual inspection to detect corrosion of the battery l

connections, or the resistance measurement on the associated battery connections, provides an indication of physical damage or abnormal deterioration that could potentially degrade battery 4

performance. The connection resistance of 2150 x 10 ohm was established from the existing battery connection resistance limits contained in SR 4.8.2.3.c.3.

The proposed change to TS SR 4.8.2.3.c.4 is required to ensure the new chargers are adequately tested to support the associated battery recharge and to support additional load growth on the DC system. SR 4.8.2.3.c.4 has been modified by increasing the battery charger amperage limit from "at least 200 amperes at 2125 volts for at least 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />" to "2 300 amperes at 2125 volts for 2 8

- I Attachment to 2CAN069807 Page 4 of 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />". After the battery charger replacement modification, all the ANO-2 vital 125 volt DC

' battery chargers will have a 400 ampere design capacity. The current limit on these chargers will be set in accordance with SAR Table 8.3-1 current limit (presently set at 400 amperes) to bound the maximum power output for emergency diesel generator loading considerations.

The 2 300 ampere limit is a nominal value chosen to be high enough to ensure the chargers will provide adequate power output to restore the class IE batteries from the design minimum charge to their fully charged state while supplying normal steady state loads. This nominal limit was also chosen to be low enough to ensure successful completion of this test. The 2 300 ampere limit takes into consideration the tolerances associated with the present charger current limit setting of approximately 400 amperes and the current measurement devices ability to determine that the battery charger amperage output is greater than the TS limit. This amendment request redefmes full capacity charger as used in TS 3.8.2.3 as a battery charger that is capable of supplying an l output of 2 300 amperes.

l-TS 3.8.2.3 Action "b" provides the required actions to be taken in the event that one of the full capacity battery chargers are inoperable. This action requires the performance of SR 4.8.2.3.a.1 I within one hour 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 for a loss of one of the full capacity l chargers. Action "b" goes on to state that if any Category A limit in Table 4.8-2 is not met while a charger is inoperable, the associated battery is inoperable. ,

I Table 4.8-2 is typically used to verify battery operability when the battery is on float. When the l battery is on a float charge, the DC loads on the battery bus are powered by the respective battery charger and a trickle charge is being applied to the respective battery. The bases for TS 3.8.2.3 Action "b" has been modified to indicate that when the battery is not on float, the pilot cell float voltage required by Table 4.8-2 is determined by measuring the pilot cell voltage. This change is considered administrative in nature because TS 3.8.2.3 Action "b" provides the compensatory actions to be taken when the battery is not on float. This bases change simply clarifies that the intent of TS 3.8.2.3 Action "b" is to verify that the Category A parameters in Table 4.8-2 j (including pilot cell voltage) is above the associated limits. If any Category A limit is not met l while a charger is inoperable, the associated battery bank shall be declared inoperable and TS 3.8.2.3 Action "a" shall be entered. 4 I

DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATION An evaluation of the proposed change has been performed in accordance with 10 CFR 50.91(a)(1) regarding no significant hazards considerations using the standards in 10 CFR 50.92(c). A discussion of these standards as they relate to this amendment request follows:

I Attachment to 2CANM9807 Page 5 of 6

, Criterion 1 - Does Not Involve a Significant Increase in the Probability or Consequences of an Accident Previously Evaluated. l Technical Specification (TS) surveillance requirement (SR) 4.8.2.3.b.2 requires the battery banks for each of the vital 125 voit direct current (DC) systems to be inspected to ensure that no visible corrosion exists at the terminals or the connectors. This SR has been modified to allow the present corrosion inspection, or tie measurement of the resistance of the associated battery connections. The resistance measurement provides an indication of physical damage or abnormal deterioration that could potentially degrade battery performance and has been an accepted alternative to the visual inspection requirement.

The Bases change associated with TS 3.8.2.3 Action "b" is considered administrative in nature and simply clarifies the intent of the action without changing the requirements of the action or its required completion ume. The station batteries are not classified as accident initiators in the ANO-2 accident analysis. The 125 volt class IE batteries are credited for accident mitigation in the accident analysis. The above described changes do not involve a significant increase in the probability or consequences of an accident previously evaluated.

Each battey charger is required to have sufficient capacity to restore the battery from the design j minimum charge to its fully charged state while supplying normal steady state loads. The minimum specified TS surveillance required charger amperage limit will ensure this capacity. The additional charger output is presently accounted for in the emergency diesel generator loading tables in the Safety Analysis Report (SAR). Loss of one train of the vital 125 voit DC system is an accident that has been evaluated in the SAR. The capacity of the battery chargers is not a factor in the probability of this accident occurring. Therefore, the changes associated wit h dds technical specification amendment request do not increase the probability of any accident previously evaluated.

' The proposed technical specification changes do not modify the limiting condition for operation or the associated action statements regarding operability of the battery chargers other than clarifying these requirements. The frequency at which the battery charger operability is demonstrated by surveillance testing is not being modified by this technical specification change l request. The proposed battery charger surveillance testing acceptance criterion will more appropriately demonstrate the capability of this equipment. This change does not affect the consequences of any of the previously evaluated accidents.

Therefore, this change does nat involve a significant increase in the probability or consequences of any accident previously evaluated.

Criterion 2 - Does Not Create the Possibility of a New or Different Kind of Accident from any Previously Evaluated.

Technical specification SR 4.8.2.3.b.2 requires the battery banks for each of the 125 volt systems to be inspected to ensure that no visible corrosion exists at the terminals or the connectors. This

I Attachment to ,

2CAN069807 Page 6 of 6

, SR has been modi 6ed to allow the present corrosion inspection, or to perform resistance readings on the associated battery connections. The visual inspection is required to detect corrosion of the battery connections. The resistance measurement of the associated battery connections provides an acceptable alternative to the visual inspection requirement and provides an indication of physical damage or abnonnal deterioration that could potentially degrade battery performance.

The availability of an extra battery charger for each train following the plant modification provides a more reliable configuration without introduction of any new modes of plant operation. No new accident possibilities are being introduced by the proposed change to the surveillance testing specification for battery charger amperage. Increasing the surveillance testing amperage limit for the battery chargers does not create the potential for any different accident since the new value remains within the design capacity of the components.

Therefore, this change does Det create the possibility of a new or different kind of accident from any previously evaluated.

Criterion 3 - Does Not lavolve a Significant Reduction in the Margin of Safety.

TS SR 4.8.2.3.b.2 has been moddied to allow resistance readings on the associated battery connections or the performance of the present visual inspection requirements. The resistance measurement of the associated battery connections provides an acceptable alternative to the visual ia=Wion requirement and provides an indication of physical damage or abnormal deterioration that could potentially degrade battery performance without a significant reduction in the margin of safety.  ;

The proposed technical specification surveillance requirements for the battery chargers continues to require testing of battery chargers at the present duration and frequency. These requirements will also apply to the second charger being installed for each Class 1E battery train. Each of the new battery chargers has sufficient capacity to restore the battery from the design minimum charge to its fully charged state whiae supplying normal steady state loads. The proposed ,

surveillance specification change does not involve a significant reduction in the margin to safety l since the demonstrated capacity will be of a higher amperage requirement than is demonstrated during the surveillance test with the existing configuration. Increasing the required amperage value assures the surveillance test will continue to demonstrate the chargers can provide significantly more current than is necessary to meet the design requirements. Therefore, this change does not involve a significant reduction in the margin of safety.

Therefore, based upon the reasoning presented above and the previous discussion of the amendment request, Entergy Operations has determined that the requested change does not involve a significant hazards consideration.

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