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#REDIRECT [[2CAN021501, License Amendment Request Allowance to Eliminate Movement of Control Element Assembly 18 from Surveillance Requirement 4.1.3.1.2 for the Remainder of Cycle 24]]
| number = ML15041A068
| issue date = 02/06/2015
| title = Arkansas Nuclear One, Unit 2 - License Amendment Request Allowance to Eliminate Movement of Control Element Assembly 18 from Surveillance Requirement 4.1.3.1.2 for the Remainder of Cycle 24
| author name = Browning J G
| author affiliation = Entergy Operations, Inc
| addressee name =
| addressee affiliation = NRC/Document Control Desk, NRC/NRR
| docket = 05000368
| license number = NPF-006
| contact person =
| case reference number = 2CAN021501
| document type = Letter, License-Application for Facility Operating License (Amend/Renewal) DKT 50
| page count = 18
}}
 
=Text=
{{#Wiki_filter:---Entry .,oEntergy Operations, Inc.Ent g 1448 S.R. 333Russellville, AR 72802Tel 479-858-3110 Jeremy G. BrowningVice President
-Operations Arkansas Nuclear One2CAN021501 February 6, 2015U.S. Nuclear Regulatory Commission Attn: Document Control DeskWashington, DC 20555
 
==SUBJECT:==
 
License Amendment RequestAllowance to Eliminate Movement of Control Element Assembly 18 fromSurveillance Requirement 4.1.3.1.2 for the Remainder of Cycle 24Arkansas Nuclear One, Unit 2Docket No. 50-368License No. NPF-6
 
==Dear Sir or Madam:==
In accordance with the provisions of Title 10 of the Code of Federal Regulations (10 CFR)Section 50.90, Entergy Operations, Inc. (Entergy) is submitting a request for an amendment toArkansas Nuclear One, Unit 2 (ANO-2) Technical Specifications (TS) to eliminate exercising Control Element Assembly (CEA) 18 for the remainder of operating Cycle 24, currently scheduled to end September 20, 2015. The proposed amendment would modify a Note toSurveillance Requirement (SR) 4.1.3.1.2 such that CEA 18 may be excluded from SRperformance for the remainder of Cycle 24.This amendment is necessary due to a degrading Upper Gripper Coil (UGC), located atop theReactor Vessel head, which is the coil that normally holds the CEA in place. This degradation was first identified in the fall of 2014 during performance of SR 4.1.3.1.2.
As a result, the LowerGripper Coil (LGC) was energized to hold the CEA in place over the next SR interval (92 days).However, further degradation of the UGC was noted during SR 4.1.3.1.2 performance inJanuary 2015, even though the UGC had not been in service (energized) over the preceding SRinterval.
Should the UGC fail during CEA movement, the CEA will drop into the core, resulting in a reactivity transient and subsequent power reduction, and could result in a plant shutdown ifthe CEA is deemed to be unrecoverable.
Therefore, Entergy requests CEA 18 not be exercised during the remaining two performances of SR 4.1.3.1.2, which will permit entry into refueling outage 2R24 when repairs can be completed.
2R24 is currently scheduled to commence in thefall, 2015.A- ou 2CAN021501 Page 2 of 3Attachment 1 provides a description and assessment of the proposed TS change.Attachments 2 and 3 contain a markup of existing TS and a revised (clean) TS page,respectively.
The next performance of SR 4.1.3.1.2, after applying a 25% allowance permitted by SR 4.0.2, isrequired by May 4, 2015. Entergy requests approval of the proposed license amendment byApril 30, 2015, with the amendment being implemented immediately on approval.
In accordance with 10 CFR 50.91(a)(1),
"Notice for public comment,"
the analysis about theissue of no significant hazards consideration (NSHC) using the standards in 10 CFR 50.92 isbeing provided to the Commission in accordance with the distribution requirements in10 CFR 50.4.In accordance with 10 CFR 50.91 (b)(1), a copy of this application and the reasoned analysisabout NSHC is being provided to the designated Arkansas state official.
This letter contains no new regulatory commitments.
If you have any questions or require additional information, please contact Stephenie Pyle at479-858-4704.
I declare under penalty of perjury that the foregoing is true and correct.Executed on February 6, 2015.Sincerely, JGB/dbbAttachments:
: 1. Description and Assessment of the Proposed Change2. Proposed Technical Specification Change (mark-up)
: 3. Revised (clean) Technical Specification Page 2CAN021501 Page 3 of 3cc: Mr. Marc L. DapasRegional Administrator U. S. Nuclear Regulatory Commission Region IV1600 East Lamar Boulevard Arlington, TX 76011-4511 NRC Senior Resident Inspector Arkansas Nuclear OneP. 0. Box 310London, AR 72847U. S. Nuclear Regulatory Commission Attn: Ms. Andrea E. GeorgeMS O-8B1One White Flint North11555 Rockville PikeRockville, MD 20852Mr. Bernard R. BevillArkansas Department of HealthRadiation Control Section4815 West Markham StreetSlot #30Little Rock, AR 72205 Attachment 1 to2CAN021501 Description and Assessment of the Proposed Changes Attachment 1 to2CAN021501 Page 1 of 10DESCRIPTION AND ASSESSMENT OF THE PROPOSED CHANGES1.0 DESCRIPTION The proposed amendment would modify Arkansas Nuclear One, Unit 2 (ANO-2) Technical Specification (TS) Surveillance Requirement (SR) 4.1.3.1.2 to eliminate the requirement tomove Control Element Assembly (CEA) 18 for the remainder of the current fuel cycle, Cycle 24.Cycle 24 is currently scheduled to end September 20, 2015. The SR requires that each CEAnot fully inserted in the core shall be determined to be operable by movement of at least fiveinches in any one direction at least once per 92 days. The proposed change will modify a Noteto SR 4.1.3.1.2, previously applicable to CEA 43 during Cycle 15 operation, as follows:Note 1 -Movement of CEA #184-3 is not required for the remainder of CGycle 244-5.If an outage of sufficient duration occurs prior to the end of Cycle 244-5,maintenance activities will be performed to restore the CEA.This amendment is necessary due to a degrading Upper Gripper Coil (UGC), located atop theReactor Vessel head, which normally holds the CEA in place. This degradation was firstidentified in the fall of 2014 during performance of SR 4.1.3.1.2.
As a result, the Lower Gripper(LGC) was energized to hold the CEA in place over the next SR interval (92 days). However,further degradation of the UGC was noted during SR 4.1.3.1.2 performance in January 2015,even though the UGC had not been in service (energized) over the preceding SR interval.
Should the UGC fail during CEA movement, the CEA will drop into the core, resulting in areactivity transient and subsequent power reduction, and could result in a plant shutdown if theCEA is deemed to be unrecoverable.
Attachment 2 provides a markup page of the existing TS to which illustrates the proposedchange. Attachment 3 provides a revised (clean) TS page. Because the Note isself-explanatory and because the exception will only be applicable until the end of Cycle 24, nochanges to the TS Bases are proposed at this time.2.0 ASSESSMENT 2.1 Description of CEAThe ANO-2 CEAs are clustered into groups of five "fingers" sharing a common Control ElementDrive Mechanism (CEDM). Four fingers are assembled in a 4.05-inch square array around thefifth central finger. The individual fingers in a given CEA are spaced so as to enter the CEA guidetubes in the corresponding fuel assembly.
The fuel assembly structure is designed to guide theCEAs. This design results in relatively free movement of the CEAs.ANO-2 has 81 CEAs that are used for reactivity control.
The CEAs are divided into nine groups,of which two are Shutdown Groups designated Groups A and B, six are Regulating Groupsdesignated Groups 1 through 6, and one group is designated as Group P. CEA 18 is inShutdown Bank B. The shutdown groups are the first withdrawn during startup and the lastinserted during a planned shutdown.
On a reactor startup, Groups 1 through 5 must bewithdrawn in a prescribed sequence and with the prescribed overlap.
Groups 6 and P are thelast groups to be withdrawn during reactor startup.
During power operations, insertion of Attachment 1 to2CAN021501 Page 2 of 10Groups 1 through 5 and Groups A and B is prohibited, except to complete performance of theSR 4.1.3.1.2 CEA exercise test. Because CEA 18 is in Shutdown Group B, this CEA mustremain fully withdrawn at all times when the reactor is critical, except during performance ofSR 4.1.3.1.2.
2.2 Description/Operation of CEDM Control System (CEDMCS)The CEDMCS performs the following functions:
* Add large amount of negative reactivity when the Reactor Trip Circuit Breakers areopened via commands from the Reactor Protection System Trip paths." Provide for rapid insertion of CEAs when a secondary plant load rejection occurs.* Provide a stable and controlled approach to criticality during plant startup from Mode 3 toMode 2." Provide for reactivity control at all power levels and Axial Shape Index (ASI) control at higherpower levels (> 15%). The extent of CEA motion for ASI control varies over core life." Provide for "Cocked Rod" Protection during plant heatup and cooldown (Shutdown Groups A and B fully withdrawn to provide immediately large insertion of negativereactivity if needed)." Permit exercise of each CEA as required by TS SR 4.1.3.1.2.
The CEDM is an electromechanical device that uses induced magnetic fields to operate amechanism for moving a CEA. The pressure housings for the CEDMs are threaded onto nozzleson the Reactor Vessel head and seal welded. A hollow, grooved drive shaft extends through thedrive mechanism to the top of the control element assembly.
Latches in the drive unit engage thegrooves on the CEA extension shaft and provide means for lifting,
: holding, and inserting the CEA.Coils mounted in a coil stack assembly slide over the mechanism pressure housing and rest upona locating shoulder.
These coils provide the magnetic flux that operates the mechanical parts ofthe drive within the pressure housing.
Linear motion of these parts causes operation of latchingdevices, which translate the motion of the parts to the CEDM drive shaft. Holding and moving theCEA occurs when power is sequentially applied to the coils. Each mechanism has five electrical coils. Power to these coils is controlled by the CEDMCS. The coils and external electrical components are cooled by forced airflow from the CEDM cooling units.The proper sequencing of each coil causes withdrawal and insertion of the CEA. A reactor tripis accomplished by rapid insertion of the CEAs when the CEDM coils are de-energized.
Whenthis happens, the latches are disengaged from the drive shaft and the CEAs fully insert into thecore by means of gravity.The coil designations from top (of stack) to bottom are as follows:Lift Coil (LC)Upper Gripper Coil (UGC)Pull Down Coil (PDC)Load Transfer Coil (LTC)Lower Gripper Coil (LGC)
Attachment 1 to2CAN021501 Page 3 of 10Withdrawal or insertion of CEAs is accomplished by applying programmed voltage levels, in theproper sequence, to the five CEDM coils. There are three possible states for each coil:High voltage (~ 140 +/- 5 VDC) to quickly energize the coil," Low voltage (- 40 +/- 5 VDC) to maintain the coil energized, or*OffThe initial condition of a CEA prior to receiving a motion command is the "holding" mode. In thismode the UGC is energized at low voltage engaging the Upper Gripper latch within the driveshaft. During normal plant operation when conditions do not require CEA movement, all81 CEAs will be in the "holding" mode with the UGC energized at low voltage.During performance of CEA maintenance activities, the subgroup containing the CEA on whichthe maintenance is to be performed is placed on a Hold Bus. The purpose of the Hold Bus is toallow maintenance to be performed on an individual subgroup without dropping the associated CEAs. This is accomplished by placing an alternate low voltage supply in parallel with, anddownstream of, the normal low voltage supply. Once a subgroup has been placed on the HoldBus, its normal power may be de-energized.
The CEAs will remain in place due to the voltageapplied to the UGCs; however, the associated CEAs cannot be inserted or withdrawn while onthe Hold Bus. Only one subgroup can be assigned to the Hold Bus at a time. If a reactor tripsignal is received while a subgroup is assigned to the Hold Bus, all CEAs within the subjectsubgroup, as well as the remaining CEAs, will insert into the core.The CEDMCS is described in Section 7.2.1 of the ANO-2 SAR.3.0 TECHNICAL ANALYSISDuring the October 2, 2014, Quarterly Exercise in accordance with TS SR 4.1.3.1.2, the CEA 18UGC current trace indicated more "noise" than expected.
The current draw was measured to be6 amps (normal -4 amps). CEA-18 was transferred to the LGC, de-energizing the UGC. Thiswas considered an indication of UGC degradation (reference Condition Report (CR)-ANO 2014-2814).
The UGC was added to outage 2R24 (fall 2015) and administrative controlsestablished to only energize the subject UGC when necessary, specifically during the threequarterly CEA exercises remaining in operating Cycle 24.The following CEA exercise performed in January 2015, indicated further degradation of theCEA 18 UGC with a measured current draw of 10 amps, even though the UGC had not been inservice during the SR interval.
Despite the progressive degradation, CEA 18 was exercised successfully.
Note that CEA 18 is the only coil exhibiting this behavior.
After exercising theCEA, the Automatic CEDM Timing Module (ACTM) automatically transferred CEA 18 to theLGC due to an abnormal voltage reading on the UGC. Currently, the LGC is energized as the"holding" coil for CEA 18 instead of the UGC, which is degrading.
The CEA drives are electromechanical devices that convert electrical energy into mechanical motion. The CEA coils provide the magnetic flux that operates the mechanical parts of the drivewithin the pressure housing.
Linear motion of these parts causes operation of latching devices,which translate the motion of the gripper assembly to the CEDM drive shaft.
Attachment 1 to2CAN021501 Page 4 of 10The primary failure modes of an inductor (coil) are:* One or more winding shorts" An open coilHeating is the primary driver of both failure modes. The heating is primarily internal and largelya result of the coil being energized.
The majority of the failure modes are related to the coil dielectric or insulation breakdown.
Theshorted-winding condition is the most common cause of coil failure.
It occurs when theinsulation resistance, or dielectric, fails within a winding, allowing a secondary, or parasitic, current path. Although a single shorted turn in a winding may not have an immediate effect on acoil's performance, the point of dielectric failure becomes a source of additional heat. Thislocalized heat buildup causes further insulation breakdown.
Furthermore, the shorted turnsreduce the overall circuit resistance resulting in additional current draw and additional heatgeneration (12R heating).
CEA-18 troubleshooting has indicated an increase in current which is believed to be caused byshorted turns in the coil winding.
An open coil has not been observed for CEA-18. The possiblecauses of the shorted turns in the coil winding are as follows:" Short term high current causing overheating and winding insulation break down." Thermal and age related degradation of the coil insulation.
" Excessive voltage resulting in insulation break down.* Manufacture defect which results in localized heating.The coil will burn open at an estimated 20 amps; however, the supply breaker will trip between12-16 amps. The degrading material condition indicates a high probability of the supply breakertripping after the coil is reenergized and subsequently exercised.
Therefore, the CEA has ahigh potential of dropping into the core.The increase in current draw between the two surveillance tests most likely indicates an initialturn-to-turn short followed by additional turn-to-turn faulting.
These shorts most likely occurredduring the exercise when the CEA is energized.
When the CEDMCS selects a coil, it applies ahigh voltage of 140 VDC which insures gripper engagement, followed by application of a holdingvoltage of 40 VDC after the mechanical action takes place.The turn-to-turn shorts indicate a degraded dielectric which is resulting in localized heating.
Thecoil will further degrade with continued use or if energized.
The degradation is not linear orpredictable.
The localized heating can result in further turn-to-turn shorts which will increasecurrent draw, or will result in the coil burning open. Either condition has the high potential ofcausing the CEA to drop into the core.
Attachment 1 to2CAN021501 Page 5 of 10Monitoring the health of the coil and predicting failure is not feasible.
A simple ohmmeasurement is not possible due to the long electrical runs from the CEDMCS room to thereactor head, which along with EMI/RFI (electromagnetic and radio frequency interference) dueto other operating equipment, result in induced currents on the coil leads. The induced currentsand noise make simple ohm measurements inaccurate.
Another method used at ANO to verify coil resistance applies a known voltage to the coil. Thecoil is in series with a known value resistor.
The measurement of the voltage drop across theresistor provides the means to calculate the coil resistance.
This second method is notadvisable due to apparent localized heating in the coil. Energizing the coil for the measurement will result in additional heating and further degradation or failure.
Additionally, the lowerresistance is a result of the failure and does not predict location or source of the internalheating.
The probability of the coil burning open is equal to the probability of further turn-to-turn shorts; neither of which can be predicted reliably.
All UGCs were replaced in refueling outage 2R19 (March 2008). Further exercising of this CEAsignificantly increases the potential for CEA drop, which would result in a reactivity excursion and power reduction, and could lead to a shutdown of the reactor.
Therefore, Entergy requestsNRC approval to not perform the remaining two SR 4.1.3.1.2 CEA exercise tests that are due tobe performed before repairs can be completed in the upcoming fall 2015 refueling outage 2R24.Coil replacement requires access atop the reactor vessel.The purpose of SR 4.1.3.1.2 is to verity that the CEAs are moveable and trippable (i.e.,otherwise free from mechanical binding).
This is accomplished by moving each CEA in theManual Individual Mode, i.e., only one CEA is moved at a time by the Control Room Operator.
Instrument and Control technicians normally verify proper operation of the CEDM coils duringperformance of this test. The technician utilizes a digital recorder with storage/print capabilities, which plots the voltage and current supplied to each coil during a withdrawal or insertion sequence.
These traces can be used during troubleshooting efforts to determine if theCEDMCS is energizing the CEA coils in the proper sequence and is applying the propervoltages for the optimum length of time. Successful movement of the CEAs indicates nomechanical binding exists.As stated in Reference 1, the possibility of warped CEAs, which could result in mechanical
: binding, is minimal since the ANO-2 CEAs were replaced in 1995. In addition, the five fingerdesign of the CEAs ensures relatively free movement.
Because of the design of the CEDMCS,electrical problems will not prevent insertion of a CEA into the core when the reactor tripbreakers are opened. However, mechanical
: failures, which would result in less than fullinsertion of a CEA upon reactor trip, could be significant, although are much less common andhave not been noted during testing.
ANO-2 has not experienced mechanical binding.
As statedin Reference 1, only two documented instances of individual CEAs failing to insert fully whendropped had been previously recorded.
In both cases, the CEA dropped to approximately 11 inches above the bottom of the core. The cause in each case was debris in the fuelassembly, not mechanical binding.
SR 4.1.3.1.2 would not detect this condition, since the CEAswere trippable and moved freely in the upper portion of the core. No further occurrences ofCEAs failing to fully insert have been identified since the Reference 1 request.
Attachment 1 to2CAN021501 Page 6 of 10Reactivity ImpactBecause CEA 18 is trippable and is expected to remain so, no additional reactivity considerations need to be taken into consideration.
: However, to further demonstrate theacceptability of eliminating performance of SR 4.1.3.1.2 ror CEA 18 for the remainder ofCycle 24, the following reactivity information is provided.
The TS definition of Shutdown Margin (SDM) is:Shutdown Margin shall be the instantaneous amount of reactivity by which the reactor issubcritical or would be subcritical from its present ccndition assuming all control elementassemblies are fully inserted except for the single assembly of highest reactivity worth whichis assumed to be fully withdrawn.
TSs 3.1.1.1 (Modes 1 through 4) and 3.1.1.2 (Mode 5) specify that SDM shall be greater than orequal to that specified in the Core Operating Limits Report (COLR). The Cycle 24 COLR SDMoperating limit is 5.0% Ak/k in Modes 1 through 5. Calculations were performed at variousEffective Full Power Days (EFPDs) throughout the remainder of Cycle 24 operation, andEntergy has determined that a minimum SDM of 5.5142% Ak/k would exist following a reactortrip assuming both CEA 18 and the single CEA of highest reactivity worth fail to insert, wellabove the 5.0% Ak/k SDM requirement of the COLR. This value was calculated at End of Cycleconditions which were determined to bound operation through the remainder of Cycle 24. Itshould be noted that the preceding discussion does not reflect the response of the ControlRoom Operator; procedures require emergency boration of the Reactor Coolant System at aminimum rate of 40 gpm (gallons per minute) with 2500 ppm (parts per million) of borated waterif one or more CEAs fail to fully insert into the core following a reactor trip. Reactivity control isof primary importance in accident mitigation and Operator training.
Based on the above, it can be shown analytically that SDM in excess of the COLR limit will bepresent at all times for the remaining portion of Cycle 24 if CEA 18 fails to insert into the core.Other Changes -Administrative During preparation of this license amendment
: request, Entergy identified that the footer of theaffected TS page did not contain all of the previous amendment numbers relevant to TSPage 3/4 1-18. ANO-2 TS Amendment 173 (ML021560200, December 22, 1995) increased theCEA exercise test frequency to 92 days, although at the time this test (SR 4.1.3.1.2) waslocated on TS Page 3/4 1-19 (information was subsequently moved to the current page).ANO-2 TS Amendment 244 (ML021130826, April 24, 2002) involved a power uprate to the unit.This amendment was complex and, in part, relocated SR 4.1.3.1.2 from TS Page 3/4 1-19 toPage 3/4 1-18. The markups of Amendment 244 TS pages were submitted prior toAmendment 235 approval (Reference 1), which added the current SR 4.1.3.1.2
'Note'associated with CEA 43. Neither Amendment 173 nor 235 were included in the footer of TSPage 3/4 1-18 upon approval of TS Amendment 244. Therefore, for historical traceability, theaforementioned amendment numbers are being added back to the footer of TS Page 3/4 1-18.
Attachment 1 to2CAN021501 Page 7 of 104.0 REGULATORY ANALYSIS4.1 No Significant Hazards Consideration Determination Entergy Operations, Inc. (Entergy) has evaluated the proposed changes to the TS using thecriteria in 10 CFR 50.92 and has determined that the proposed changes do not involve asignificant hazards consideration.
Entergy proposes a change to a Note associated with Arkansas Nuclear One, Unit 2 (ANO-2)Technical Specification (TS) Surveillance Requirement (SR) 4.1.3.1.2 to eliminate therequirement to move Control Element Assembly (CEA) 18 for the remainder of the current fuelcycle, Cycle 24. Cycle 24 is currently scheduled to end September 20, 2015. The SR requiresthat each CEA not fully inserted in the core shall be determined to be operable by movement ofat least five inches in any one direction at least once per 92 days. A non-technical change isalso included to the footer of the affected TS page for historical purposes.
Because this additionof references to previous TS amendments is administrative only, this change is not discussed under the three criteria below.Basis for no significant hazards consideration determination:
As required by 10 CFR 50.91 (a),Entergy analysis of the issue of no significant hazards consideration is presented below:1. Does the proposed change involve a significant increase in the probability or consequences of an accident previously evaluated?
Response:
NoOne function of the CEAs is to provide a means of rapid negative reactivity addition into thecore. This occurs upon receipt of a signal from the Reactor Protection System. Thisfunction will continue to be accomplished with the approval of the proposed change.Typically, once per 92 days each CEA is moved at least five inches to ensure the CEA isfree to move. CEA 18 remains trippable (free to move) as illustrated by the lastperformance of SR 4.1.3.1.2 in January 2015. However, due to abnormally high coilvoltage and current measured on the CEA 18 Upper Gripper Coil (UGC), future exercising of the CEA could result in the CEA inadvertently inserting into the core, if the UGC were tofail during the exercise test. The mis-operation of a CEA, which includes a CEA dropevent, is an abnormal occurrence and has been previously evaluated as part of the ANO-2accident analysis.
Inadvertent CEA insertion will result in a reactivity transient and powerreduction, and could lead to a reactor shutdown if the CEA is deemed to be unrecoverable.
The proposed change would minimize the potential for inadvertent insertion of CEA 18 intothe core by maintaining the CEA in place using the Lower Gripper Coil (LGC), which isoperating normally.
The proposed change will not affect the CEAs ability to insert fully intothe core upon receipt of a reactor trip signal.No modifications are proposed to the Reactor Protection System or associated ControlElement Drive Mechanism Control System logic with regard to the ability of CEA 18 toremain available for immediate insertion.
The accident mitigation features of the plant arenot affected by the proposed amendment.
Because CEA 18 remains trippable, noadditional reactivity considerations need to be taken into consideration.
Nevertheless, Entergy has evaluated the reactivity consequences associated with failure of CEA 18 to Attachment 1 to2CAN021501 Page 8 of 10insert upon a reactor trip in accordance with TS requirements for Shutdown Margin (SDM)and has determined that SDM requirements would be met should such an event occur atany time during the remainder of Cycle 24 operation.
Therefore, this change does not involve a significant increase in the probability orconsequences of an accident previously evaluated.
: 2. Does the proposed change create the possibility of a new or different kind of accident fromany accident previously evaluated?
Response:
NoCEA 18 remains trippable.
The proposed change will not introduce any new designchanges or systems that can prevent the CEA from perform its specified safety function.
As discussed previously, CEA mis-operation has been previously evaluated in the ANO-2accident analysis.
Furthermore, SDM has been shown to remain within limits should anevent occur at any time during the remainder of operating Cycle 24 such that CEA 18 failsto insert into the core upon receipt of a reactor trip signal.Therefore, this change does not create the possibility of a new or different kind of accidentfrom an accident previously evaluated.
: 3. Does the proposed change involve a significant reduction in a margin of safety?Response:
NoSR 4.1.3.1.2 is intended to verify CEAs are free to move (i.e., not mechanically bound).The physical and electrical design of the CEAs, and past operating experience, provideshigh confidence that CEAs remain trippable whether or not exercised during each SRinterval.
Eliminating further exercising of CEA 18 for the remainder of Cycle 24 operation does not directly relate to the potential for CEA binding to occur. No mechanical bindinghas been previously experienced at ANO-2. CEA 18 is contained within a Shutdown CEAGroup and is not used for reactivity control during power maneuvers (the CEA must remainfully withdrawn at all times when the reactor is critical).
In addition, Entergy has concluded that required SDM will be maintained should CEA 18 fail to insert following a reactor trip atany point during the remainder of Cycle 24 operation.
Therefore, this change does not involve a significant reduction in a margin of safety.Based upon the reasoning presented above, Entergy concludes that the requested changeinvolves no significant hazards consideration, as set forth in 10 CFR 50.92(c),
"Issuance ofAmendment."
Attachment 1 to2CAN021501 Page 9 of 104.2 Applicable Regulatory Requirements/Criteria 10 CFR 50.46, "Acceptance Criteria for Emergency Core Cooling Systems for Light WaterNuclear Power Plant," requires, in part, safety system designs with adequate margin to ensurespecified acceptable fuel design limits are not exceeded.
The applicable General DesignCriteria (GDC) for CEA design requirements included the following:
GDC-4, "Environmental and Dynamic Effects Design Bases," requires that systems,structures and components (SSCs) important to safety be designed to accommodate theeffects of and to be compatible with the environmental conditions associated with normaloperation, maintenance,
: testing, and postulated accidents; GDC-10, "Reactor Design,"
requires that SSCs important to safety be designed toaccommodate the effects of and to be compatible with the environmental conditions associated with normal operation, maintenance,
: testing, and postulated accidents; GDC-23, "Protection System Failure Modes," requires that the protection system be designedto fail into a safe state;GDC-25, "Protection System Requirements for Reactivity Control Malfunctions,"
requires thatthe protection system be designed to assure that specified acceptable fuel design limits arenot exceeded for any single malfunction of the reactivity control systems;GDC-26, "Reactivity Control System Redundancy and Capability,"
insofar as it requires thattwo independent reactivity control systems be provided, with both systems capable of reliablycontrolling the rate of reactivity changes resulting from planned, normal power changes;GDC-27, "Combined Reactivity Control Systems Capability,"
requires that the reactivity control systems be designed to have a combined capability, in conjunction with poisonaddition by the emergency core cooling system, of reliably controlling reactivity changesunder postulated accident conditions, with appropriate margin for stuck rods. to assure thecapability to cool the core is maintained:
GDC-28, "Reactivity Limits,"
requires that the reactivity control systems be designed toassure that the effects of postulated reactivity accidents can neither result In damage to thereactor coolant pressure boundary greater than limited local yielding, nor disturb the core, Itssupport structures, or other reactor vessel Internals so as to significantly impair the capability to cool the core; andGDC-29, "Protection Against Anticipated Operational Occurrences,"
(AOOs) requires that theprotection and reactivity control systems be designed to assure an extremely high probability of accomplishing their safety functions in event of AOOs.The amendment request has concluded that CEA 18 is not mechanically bound and its failure toinsert would not result in inadequate SDM should both CEA 18 and the CEA having the highestreactivity worth fail to insert following a reactor trip. Delaying SR performance for approximately five months until the UGC can be replaced has no impact on the CEA's ability to move.Nevertheless, because required SDM will continue to be met given the aforementioned scenario(two CEAs remain fully withdrawn post-trip),
no fuel design limits will be challenged as a resultof this amendment request should it be approved.
In addition, the amendment request has noimpact on the second reactivity control system at ANO-2 (boration).
Therefore, compliance withthe aforementioned regulation is maintained.
Attachment 1 to2CAN021501 Page 10 of 104.3 Precedence This amendment and exemption request is similar to that approved for ANO-2 due todegradation of CEA 43 in 2001 (Reference 1).5.0 ENVIRONMENTAL CONSIDERATION The proposed change would change a requirement with respect to installation or use of a facilitycomponent located within the restricted area, as defined in 10 CFR Part 20, and would changean inspection or surveillance requirement.
: However, the proposed change does not involve(i) a significant hazards consideration, (ii) a significant change in the types or significant increase in the amounts of any effluents that may be released
: offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure.
Accordingly, the proposedchange meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Therefore, pursuant to 10 CFR 51.22(b),
no environmental impact statement or environmental assessment need be prepared in connection with the proposed change.
 
==6.0 REFERENCES==
: 1. NRC Safety Evaluation Report dated October 22, 2001, "Arkansas Nuclear One, Unit 2 -Issuance of Amendment Re: Allowance to Eliminate Movement of Control ElementAssembly
#43 for the Remainder of Cycle 15 (TAC No. MB2779) (2CNA100104)
(ML012960550)
Attachment 2 to2CAN021501 Proposed Technical Specification Change (mark-up)
REACTIVITY CONTROL SYSTEMSACTION: (Continued)
: e. With more than one CEA misaligned from any other CEA in its group by more than7 inches (indicated position),
be in at least HOT STANDBY within 6 hours.SURVEILLANCE REQUIREMENTS 4.1.3.1.1 The position of each CEA shall be determined to be within 7 inches (indicated position) of all other CEAs in its group at least once per 12 hours.4.1.3.1.2 Each CEA not fully inserted in the core shall be determined to be OPERABLE bymovement of at least 5 inches in any one direction at least once per 92 days. (Note 1)Note 1 -Movement of CEA #1843 is not required for the remainder of CGycle 244-5. If anoutage of sufficient duration occurs prior to the end of Cycle 2445, maintenance activities will be performed to restore the CEA.ARKANSAS
-UNIT 23/4 1-18Amendment No. 70,4-5,457,469,-7-3, 236,244, Attachment 3 to2CAN021501 Revised (clean) Technical Specification Page REACTIVITY CONTROL SYSTEMSACTION: (Continued)
: e. With more than one CEA misaligned from any other CEA in its group by more than7 inches (indicated position),
be in at least HOT STANDBY within 6 hours.SURVEILLANCE REQUIREMENTS 4.1.3.1.1 The position of each CEA shall be determined to be within 7 inches (indicated position) of all other CEAs in its group at least once per 12 hours.4.1.3.1.2 Each CEA not fully inserted in the core shall be determined to be OPERABLE bymovement of at least 5 inches in any one direction at least once per 92 days. (Note 1)Note 1 -Movement of CEA 18 is not required for the remainder of Cycle 24. If an outage ofsufficient duration occurs prior to the end of Cycle 24, maintenance activities will beperformed to restore the CEA.ARKANSAS
-UNIT 23/4 1-18Amendment No. 7-0,42-5,,4,5-69,4-7-3, 235,2-44,}}

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