ML20094E500

Application for Amend to License NPF-30,revising TS Table 2.2-1 & Sections 3/4.2.1,4.2.2.2 Through 4.2.2.4 & 6.9.1.9 in Order to Implement Relaxed Axial Offset Control for Cycle 6 Operation

ML20094E500
Person / Time
Site:	Callaway
Issue date:	01/14/1992
From:	Schnell D UNION ELECTRIC CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20094E511	List: ML20094E500 ML20094E512
References
ULNRC-2546, NUDOCS 9201240185
Download: ML20094E500 (22)

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%l4 %4;fLD UNION  ?"Wl?"1 Euienue a-33 January 14, 1992 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Mail Station F1-137 Washington, D.C. 20555 ULNRC- 2 54 6 Gentlemen:

DOCKET NUMBER 50-483 CALIAWAY PLANT RETAXED AXIAL OFFSET CONTRQI,

References:

1. WCAP-10216-PA, " Relaxation of Constant Axial Offse, Control and F Surveillance Technical Spohification,"

June 1983

2. Kansas Gas and Electric Company letter KMLNRC 86-013 dated January 20, 1986

3. NRC letter dated April 22, 1986 transmitting Amendment No. 1 to Wolf Creek Generating Station FOL No. NPF-42

4. ULNRC-2439 dated July 19, 1991

5. ULNRC-2196 dated April 12, 1990 Union Electric Company herewitn transmits an application for amendment to Facility Operating License No. NPF-30 for the Callaway Plant.

This amendment application includes revisions to Technical Specification Table 2.2-1 as well as Sections 3/4.2.1, 4.2.2.2 through 4.2.2.4, and 6.9.1.9 and associated Bases in order to implement relaxed axial offset control (RAOC) for Cycle 6 at Callaway. The RAOC methodology has been previously reviewed and approved as discussed in Reference l'above. The attached amendment application is similar to that submitted and approved for Wolf Creek Generating Station in References 2 and 3 above.

As discussed in Reference 4, the process described in WCAP-12935, "Large Dreak LOCA Power Distribution Methodology," will be used during each reload design to ensure that the chopped cosine power 9201240183 DR 92o334 p ADOCK 05000483 PDR f POI

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Callaway Cycle 6 Rev.1

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y RTP Fg(Z) 5 9---

• K(Z) fer P S 0.5 0.5 THERMAL POWER wheret P = -------------------

RATED THERMAL POWER l 2.5.1 FgRTP = 2.50 ,

2.5.2 K(Z) is provided in Figure 4.

2.5.3 The W(z) functions that are to be used in Technical Specifications 4.2.2.2, 4.2.2.3, and 4.2.2.4 for Fg surveillance are shown in  !

) Figures 5 through 8.

Because significant. margin exists between the analytically determined maximum F z) *P valuesandtheirlimit,Restricte8(Axia[*hlux  :

Difference (RAFDO) oper ' '

is not expected '

to be required for Cyris 4 this reason, no W(z)RAFDO values are s-y vl for Cycle +rd.

The have Normal . Operation been determined for W(z) th:::values, :p::ifiW(z)$0,rlu//ey/e /

burnups in Cycle-tP 4.This. permits determination of W(z) at any cycle burnup g;u // ,p /e _ through the use ofA44Hree- point interpolation.

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d ~CyclehThe W(z)$herates with - th: values 0A;;A:t;;;.,,, were determirnd ..,4 assumin u :: : +24, -124 icits-I bor.d ;b;;t th

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U. S. Nuclocr Regulatory Commicolon January 14, 1992 Page 2 distributson romains limiting for largo breat. .50 CA . In this process, onch power dictribution calculated in the coro design will be evaluated to determine whe thnt it is more limiting than the chopped cosino power distribution.

With implementation of the WCAP-12935 metholalogy, top-skewed axial povor dintributions which are potentially more limiting than the choppt.d cctino power distribution ased in the largo break LOCA analysis will b9 precluded from occurring by the design and/or W(z) surveillance factors. As such, it in expected that the 100*F PCT panalty discussed in Referenct 4 will not apply to Cyc?.c 6 with RAOC or to future cyc.lcs.

The callaway Plant O!-Gite Review Committee and the Nuclear Safety Rnview Board have reviewed this amendmnnt wpplication. Attachmonto 1 through 5 provice the Safoty Evaluation, Significant Hazards Evaluation, Environmental Consideration, proposed Technical Specific 1 tion ro'risions, and preliminary Cycle 6 Coru Opttrating Limitn Report (COLH) changeu, respectively, in support of th.is amor.dmert requent. The Callaway Cycle 6 COLR will be provjded to you at a latur data. It has been dotarmined that this amendmenc 1pplication does not involve an,unreviewed unfety question as doterminol por 10CFP.50.59 nor a significant hatard consideration as datorm'.ned per 10CFR50.92. Pu_suant to 10C1'R51. 22 (b) , no envirennental impact statonent or environmental assorament net:d be prepared in connection with the issr.acco of this amend.nont.

Approval of this amen 1 ment application is needed by May 15, 1992 orior to startup for Cycle 6. If you have any questions un this amendment application, please contact us.

Very truly yours,

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Donald F. Schnell GGY/p1h Attachments: 1 - Safety Evaluation 2 - Significant Hazards Evaluation 3 - Environmental Consideration 4 - Proposed Technical Specification Revisions 5 - Preliminary Cycle 6 COLR Changes L-

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STATE OF MISSOURI ,

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Donald i Schnell, of lawful age, being first Ouly awo n upon cath says thnc he is Senior Vice President-Huc1 car c..-l an officer o.f Union ?loctric Company; that he has read the foregoirg

.j 1.ocument and knows the content thereof; that he has excuuted the

. twme for and on behalf of said company with full power and althority to do art and that the facts therein stated are ,r.e and corer.t to the aest of his knowledge, information and belief.

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Donald F. ocano11 Senior Vice Prisiderat Nuclear SUBSCRIBED and sworn c0 before me this /MM' day of t n z. ,, .992.

jaba.d Notary Public lngg_.--

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l i cci -T. A. Baxter, Esq.

Shaw, Pittman, Potts & Trowbridge j 2300 N. Street, N.W. '

l Washington, D.C., 20037 Dr. J. O. Cermak CFA, Inc.

- 18225-A Flower Hill Way Gaithersburg, MD 20879-5334 1 It. C. : Knop Chief,. Reactor Project Branch 1 U.S. Nuclear Regulatory Commission Region III 799 Roosevelt Road Glen Ellyn, Illinois 60137 I l

'RBruce Bartlett.

• Callaway Resident Office  ;

U.S.-Nuclear Regulatory Commission RR#1- .

Steedman, Missouri 65077 J. R. Hall (2) .

Office of Nuclear' Reactor Regulation U.S.1 Nuclear Regulatory Commission

1. White Flint, North, Mail Stop 13E21 11555 Rockvillo Pike-Rockville, MD'20852 Manager, Electric Department Missouri Public Service Commission P.O. Box 360 _ .

I Jefferson City, MO-65102

'Ron Kucera Department of Natural Resources P.O. Box 176 Jefferson City, MO 65102 <

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ULNRC-2546  !

l ATTACHMENT 1 l

SAFETY EVALUATION FOR RELAXED AXIAL OFFSET CONTROL (RAOC) g .

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This amendment application includes revisiens to Technical Specification Table 2.2-1 as well as Sections 3/4.2.1, 4.2.2.2 I through 4.2.2.4, and 6.9.1.9 and associated Bases in order to implement Relaxed Axial Offset Control (RAOC) for Cycle 6 at Callaway Plant. Implementation of RAOC at Callawhy will be in accordance with WCAP 10216-PA which has been previously reviewed and approved by the NRC.

1.0 BSCEGROUND The following discussion briefly describes the present methodology of axial power distribution control and the proposed alternative. l 1.1 Constant Axial Offset Control (C&QCl Axial power distribution control at the Callaway Plant is currently achieved by Constant Axial Offset Control 1 (CAOC). This methodology was developed and describeu in WCAP-8385-(Proprietary) and WCAP-8403 (Non-propriotary). This method assurcs peaking factors and DNBR remain below the accident analysis limits.

The CAOC strategy developed in this topical report does this 'r maintaining the axial flux difference-(AFD or delth-2) within a band of 43%, -12% around a measured target value during normal plant operation (including power change maneuvers). By controlling the axial power distribution, the possible akewing of the axial xenon distribution is limited,-thus minimizing xenon

• oscillations and their effects on the power distribution.

The AFD is a measure of axial power distribution skewing to the top or bottom half of the core. It is vcey sensitive to core.related parameters such as control bank position, core power level, axial burnup, and axial xenon distribution. The limits on AFD assure that the Heat exceeded Flux during Hot Channel either Factor FO(Z) nornal operation or inisthe notevent of xenon redistribution following power changes. They are used in the nuclear design process and assumed in the safety analyses as_a boundary of possible initial condition axial power shapes. Operation outside these limits during Condition I operation influ,nces the possible power shapes and results in Condition II transients. Condition II transients, assumed to begin from within the AFD limits, are used to confirm the adequacy of Overpower Delta-T (OPDT) and Overtemperature Delta-T (OTDT) trip setpoints.

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1.2 RelnXtiAX131 of f neLEontraLIRA07 The implementation of Relaxed Avial Offset Control and F Surveillance changes have been previously approved bftheNRCinWCAP10236-PA (Proprietary) and WCAP-11524-A (Non-proprietary). This strategy was developed to provide wider control band widths and more operator freedom than with CAOC. RAOC provides wider contr?1 bands particularly at reduced power by effectively utilizing some of the available core margin to the peaking factor limits specified in the Core Operating Limits Report (COLR). The wider operating space increases plant availability by allowing quicker plant startups and increased operating flexibility without reactor trip or reportable occurrences.

RAOC has been developed for relaxing the current constraints on axial power distribution control. This widens the allowed delta-I vs. power operating space relative to CAOC operation particularly at reduced power levels while ensuring that safety considerations are satisfied. This is achieved by examination of a wide range of possible xenon distributions and the possible range of axial power distributions associated with each xenon distribution in both normal operation and accident conditions. With the Technical Specification changes described in this submittal, Callaway will operate both safely and with enhanced flexibility during Cycle 6.

The procedure begins by constructing a xenon distribution library. Selected xenon transients are calculated and the resulting axial xenon distributions are characterized by certain parameters, These parameters are stored and the xenon distribution reconstructed from them when required. The allowed xenon distributions are limited to those for which the core delta-I values remain within tentatively chosen limits which are wider than the expected LOCA limits.

Xenon libraries are prepared for beginning of life (BOL), middle of life (MOL) , and end of life (EOL) burnups.

The next step in the procedure is the normal operation analysis. The only constraints employed are the rod insertion limits and the tentative delta-I limits.- One dimensior,al calculations are performed at BOL, MOL, and COL for a number of power levels and for xenon distributions throughout the range of the xenon library. The axial power distribution is recorded for cach case.

-2 - .

i Each power shop.a g1nerated is examined to see if LOCA i limits are met or exceeded. The standard Westinghouse synthesis methods for core peaking factors are used, ad- '

described in WCAP-8385. The result of this cxamination is c delta-I range as a function of power which meets -

the LOCA limits. The power shapes within this range are then examined to ascertain whether they meet the thermal-hydraulic constraints imposed by the loss of ,

flow accident (LOFA) and the limits are revised i accordingly.

The effect of the widened delta-I band on the consequences of the anticipated transients discussed in WCAP iO216-PA is next investigated. The analyses .

consist of choosing initial power distributions-from the allowed power vs. delta +I domain, being careful to include the entire domain, and performing the transient calculation with each distribution. The axial power shapes are preserved from each " snapshot" in the event, i and core peaking fattors are synthesized by the

ndard procedure. The results are examined for

.sations of peak power density and DNB limits. At

.11away, the OTDT trip will be altered to provido protection by changing the fy(delta-1) penalty function as discussed below.

2.0 LJfENSING BASIS The CAOC methodology is presently incorporated into the  !

Callaway Technical _Epecification Sections 3/4.2.1 Axial Flux Difference and 3/4.2.2 Heat Flux Hot Channel Factor - F (Z)

Surveillance Requirements. The Callaway Plant also uti91zes I

the COLR. The use: of this document is established in Technical Specification Section 6.9.1.9. Preliminary Cycle 6 COLR changes are included in Attachment 5.

FS1m Sections 4.3 and 4.4 also provide a licensing basis.

The specific sections that deal with power distribution control methodologies are: 4.3.2.2.4 Axial Power Distributions; 4.3.2.2.6 Limiting Power Distributions; 4.3.2.7.6 Stability Control'and Protection; and 4.4.4.3.2 Axial Heat Flux Distributions.

3.0 -IRCHNICAL SPECIFICATION CHANGES

-Implementation of RAOC requires the alteration of the Technical Specifications, as shown in Attachment 4. The penalty in Technical Specification

-negative fTable 2.2-3, (delta-I) Note'l for the 0 TDT trip setpoint will be L changed to assure the validity of the design basis analysis, i

1 a The value of this change is such that for each percent that the dif ference between percent Rated Thermal Power (RTP) in the top half of the core and percent RTP in the bottom half of the core, delta-I (qt-qb), is more negative than

-24%, the OTDT trip setpoint shall automatically be reduced by 3.25% of its value at RTP. The rather involved CAOC specification is removed and replaced by a specification that merely requires the AFD be maintained within the allowed operations band as a function of power. The allowed operating space becomes the Technical Specification. If these limits are exceeded, the condition is alarmed and the delta I must be returned within the limits within a 15 minute grace period or power must be reduced to less than 50% RTP. The surveillance requirements, which are similar to those for other alarmed limits, discuss the verification frequency of delta-I as a function of alarm status.

The current Technical Specification 3.2.1, per the COLR, specifies a target band of 48%, -7% for normal operation in Mode 1 above 15% RTP. This target band is applicable only for Cycle 5 EOL conditions and was changed from +3%, -12%

via Revision 3 of the COLR (ULNRC 2513 dated November 13, 1991). RAOC allows an AFD operating space relaxation to

-15%, +12% delta-I at 100% RTP and linearly increasing to

-;0%, +26% delta-I at 50% RTP, in Mode 1 above 50% RTP. The RAOC AFD limits are provided in Attachment 5. If the RAOC AFD limits are exceeded for more than 15 minutes, power must be reduced to less than 50% RTP within 30 minutes and the Power Range Neutron Flux - High Trip setpoints must be reduced to less than or equal to 55% RTP within the next 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />. An additional less restrictive action is included which takes credit for margin which exiats in the Restricted AFD Operation (RAFDO) limits. This act. ion does not require either a reduction to 50% RTP or a resetting of the Power Range Neutron Flux - High Trip setpoints. However, it does require a power reduction slow the RAFDO power level. Two surveillances, consistent with the current Technical Specification 3.2.1, are included to assure that the AFD of the operable excore channels are updated periodically to account for indication changes due to burnup. They are included here for completeness and are consistent with past practices on plant application.

Surveill-nce Requirements 4.2.2.2.b and 4.2.2.4.b are revised to require Limiting Condition for Operation (LCO) 3.2.2 to be evaluated against the measured F0(Z) after accounting for fuel manufacturin- colerances and flux map measurement uncertainty. The J. cent of this change is to require use of the measured pr.ameter to verify operation below the Technical Specifier ion LCO limit. Increasing the monitored Fg(Z) by an addit',nal term for expected plant maneuvers m1y appear to pr /ide a more convenient form of assuring plant operation *alow the Fn(Z) limit. However, past practices on plant pplication hd recent licensing reviews vf the New StF .ard Technical Specifications 4 -

(MPRITS) have demonstrated that a comparison of the safety limit and the measured Fg(Z) without adjustments for plant maneuvers is required.

The footnote for Surveillance Requirement 4.2.2.2.d.1 is modified to clarify the timing required for obtaining a power distribution map during startup at the beginning of each cycle and to state that extended operation is defined as expected operation at a power level for greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The intent of this footnote is to allow the plant to escalate without undue impedance while still assuring consistency with the safety analysis values. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> limit prevents sustained operations at high power leveln without verification of the F9(Z) safety limit.

To afford additional flexibiliti surveillance Requirement 4.2.2.2.f 2.a is added. It proviu s the option of an AFD operating space reduction while maintaining the same surveillance power level. This revision is consistent with WCAP-10216 PA.

Specificatigns 4.2.2.3.a and 4.2.2.4.c are revised to define k(z) and F (Z), as done in Specification 4.2.2.2.c. For RAFDO operb ion, Surveillance Requirement 4.2.2.4.f.1 is added which allows a return to normal operation in the event that sufficient margin is not available to remain in RAFDO.

This requirement clarifies the action necessary e. the event the plant can no longer remain in RAFDO. i Specification 6.9.1.9 is revised to refl -c the change to RAOC, i.e., RAFDO only target band and R& C references.

Figure B3/4.2-1 is deleted since it is not applicable to RAOC operation. The basis for AFD B3/4.2.1 is also modified to describe how RAOC and RA!DO allow operation at the maximum permissible power and AFD consistent with safety analyser. It also describes how the computer alarms functioa for RAOC application. The basis notes that two alarme exist. The first alarm indicates operation outside the PAOC operating wpace while the second indicates operhtion outside RAFDO. ,

4.0 EVALUATIDMS Both the AFD bands and the OTDT trip setpoints have been verified by the RAOC analysis and the Callaway Cycle 6 Reload Safety Analysis Checklist (RSAC), in accordance with the approved WCAP-9272-PA methodology. No other changes to the current limits are necessary for the Cycle 6 implementation of RAOC.

It has been confirmed that none of the Process' Measurement Accuracy (PMA) terms nor any of the Delta-I channel terms listed in the setpoint calculations of Reference 5 will be-affected by this change to RAOC. Only the positive f y (delta-I) OTDT penalty term, unaffected by the change to RAOC and. remaining at 1.89% delta-T per percent delta-I, is used in the OTDT setpoint calculations since it is more limiting in the transient analyses. As'such, there will be no change to the OTDT setpoints (i.e., trip setpoint, allowable value,-total allowance, Z and S terms) in Technical Specification Table 2.2-1.

l 4.1 LOCA and LOCA-Relpted Evaluatiana '

The' change from CAOC to RAOC has_been evaluated for Callaway Cycle 6 operation for impact upon the LOCA safety analyses. The LOCA and LOCA-related accident ,

analyses remain valid for the RAOC implementation given the above parameter changes and their effect on the .

safety analysis limits. RAOC does not affect the -

normal plant operating parameters, the safeguards systems actuations, the accident mitigation capabilities important to a LOCA, the assumptions used in the LOCA-related accidents, nor create conditions more limiting than those' assumed in these analyses.

4.2. Non-LO.CA Related Evaluations The.effect on the non-LOCA events for a change from CAOC to RAOC is to increase the: number of power shapes that must.be considered'wnen d2veloping the OTDT and OPDT setpoint equations. The OTDT setpoint is designed to ensure plant operation within the DNB design basis and hot-leg boiling limit. The OTDT f (delta-I) function is designed to ensure DNB proteckion-from adverse axial power shapes. The OPDT setpoint is '

designed to ensure plant operation within the fuel temperature design basis and is unaffected by the change to RAOC.

The f (delta-I)' function is generated based on expecked axial power shapes from various Condition I and II-events. Because RAOC allows more severe power shapes, it.was necessary to move-the-negative wing of the OTDT f may violatd (delta-I) penalty to eliminate the DNB criteria. shapes Modification which of the negative wing will have no effect cn1 the-FSAR transient safety analyses because they-do not model the f (delta-I)-term in the OTDT setpoint equation. The f (delta-I)-term accounts for the axial. power shape 6 -

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l effects on the DNB criteria and independently lowers the OTDT setpoint to ensure a conservative reactor trip when faced with severe power shapes.

It has been determined-that the implementation of RAOC changes the axial offset limits which are used to

• develop the f (delta-I) penalty function in the OTDT setpoint equakion. The change to the fy(delta-Is term has no effect on the conclusions of the non-LOCA FSAR I transient safety analyses. It is concluded that the implementation of RAOC does not adversely affect the results of the non LOCA FSAR transient safety analyses and the conclusions made in the FSAR remain valid.

4.3 Contairdnent Intecrity Evaluation The implementation of RAOC does not adversely affect the short and long term LOCA mass and energy releases

.and/or the main steamline break mass and energy release .

containment analyses. RAOC does not affect the normal

-plant operating parameters, system actuations, accident mitigating capabilities, or assumptions important to the containment analyses, cr create conditions more limiting than those assumed in these analyses.

Therefore, the conclusions presented in the FSAR remain va".;d with respect to the containment.

4.4 RadiologingJ Evaluation The transition to RAOC will not affect the radiological consequences or the post-LOCA hydrogen generation.

Since the inputs to the' dose analyses do not change, the accident doses are bounded by those previously reported in the FSAR. Therefore, the consequences to the public resulting from any accident previously evaluated in the FSAR have not increased. ,

4.5 Mechanical Comnonent and Systems EvaluatlGD The implementation of RAOC does not directly or indirectly involve mechanical component hardware considerations. Direct effects as well as indirect effects on safety-related equipment have been considered. Indirect effects include activities which

-involve non-safety related equipment-which may affect safety-related equipment. Component hardware considerations include overall component integrity, j

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.subcomponent integrity and the adequacy of component supports during all plant conditions. An evaluation has determined that RAOC-implementation does not alter the design, material, construction standards, function j or method of performance of any safety-related  !

equipment. j i

RAOC implementation does not affect the integrity of any plant auxiliary fluid system or the ability of any system to perform its-intended safety function.

50 . DETERMINATION OF UNREVIEWED SAFETY OUESTION The proposed'chango does not involve an unreviewed safety question because operation of Callaway Plant in accordance with this change would not:

(1) Involve an-increase in the probability of occurrence or the consequences of an accident or '

malfunction of equipment important_to safety previously evaluated in the FSAR.

.There are no accidents which would be more likely to occur due to the implementation of RAOC since the methodology does not change the likelihood of the event to occur and no new failure mechanisms are introduceU. No new performance requirements are being imposed on any system or component _and plant integrity is not degraded. The proposed parameter changes for the RAOC implementation I-assure that the safety analysis limits are not exceeded and therefore any mitigation capabilities are not reduced.

The implementation of RAOC will not rcsult in a violation of the acceptance criteria for any LOCA or non-LOCA event and does not impact the mass / energy r21 ease criteria. The consequences of accidents.previously evaluated in the FSAR are not increased due--to RAOC. _Since the. inputs to the analyses do not change,.the accident doses previously' reported in the FSAR are unaffected.

Therefore, the consequences to the public resulting from any accident or malfunction of equipment important to safety-previously evaluated in the FSAR have not increased.

There - are ru) mechanical or electrical changes to any equipment due to RAOC implementation which would increase the probability of the equipment to

_ J b + -t malfunction. No new performance requirements are being imposed on any system or component in order to support the RAOC implementation. Subsequently, there is no increase $n the probability of equipment nalfunctions previously evaluated.

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! (2) Create the possibility for an accident or ,

malfunction of a different type than any previously evaluate 6 in the FSAR. The proposed change does not involve any design changes or l

hardware modifications to safety releted equipment nor will there be a change in the method by which any safety-related plant system performs its safety function. There will be a conservative trip setpoint-reducing change to the negative f3(delta-I) penalty term in the OTDT setpoint equation, as well as changes to the non-safety

[ related AFD Monitor Alarm since penalty deviation ,

times will no longer be tracked or alarmed. '

The implementation of RAOC will not create any new L or different type of accident which-is not alrnTdy considered in the FSAR. The specific axial offset does not create the possibility that a new event could occur. No new accident scenarios, failure mechanisms or limiting single failures are introduced as a result of the RAOC implementation.

The institution of RAOC will have no adverse I effect and does not challenge the performance of l any st.fety-related-system. Therefore, the L possibility of a new or different kind of accident L -is not created.

I There are no changes P: any equipmene which would cause the malfunction of safety-related equipment,

assumed.-to be operable in the accident analyses, l as a result of the RAOC implementation. No new L mode of failure has been created and no new performance requirements are imposed by the transition to RAOC. Therefore, tre implementation  ;

of RAOC will not create the possibility of a new or different malfunction of safety-related equipment.

(3) Involve a reduction in the margin of safety as defined in the basis for any Technical Specification. The proposed chnnge will not result in a decrease in the minimum DNBR given in Bases Section 2.1.1 and reported in the FSAR nor l

will there be an increase in the LOCA peak clad temperature (PCT) above the 2200*F ECCS Acceptance Criteria limit as defined in 10CFR50.46. The 9-f

a ,

design limits on peak local power density, F , and F-delta-H will not be exceeded. Theproposeh a '

change does not alter the manner in which safety limits or limiting safety system settings are determined. The axial flux differtence limiting j surveillance are l condition revised inforaccordance operation and withF@

th approved methodology of WCAP-10216-PA.

The supporting technical specification values are  !

defined by the accident analysee which are  ;

performed te conservatively bov.nd the operating i conditions defined by the Technical Specifications and to demonstrate meeting the regulatory acceptance limits. Performance of analyses and evaluations for the RAOC transition have confirmed that the operating envelope defined by the "

Technical Specifications cuttinues to be bounded by the analytical basis, which in no case exceeds l the acceptance limits. Therefore, the margin of safety provided by the analyses in accordance with the acceptance limits is maintained and not reduced.

6.0 CONCLUSlQH Based on the information presented in the above evaluations, the change from CAOC to RAOC axial offset control will not af*cet the conclusions of the safety analyses presented d n ebe Callaway FSAR. Therefore, the proposed change L;-'.o not involve an unreviewed safety question and will not adversely affect or endanger.the health or safety of the general public.

7.0 REFERENCES

l 7.1 WCAP-8385, Of Proprietary), September 1974.

WCA9-8403, Of Non-proprietary) , September 3 974.

"PC' AIR DISTRIBUTION CONTROL AND LOAD FOLLOWING PRbuEDURES-TOPICAL REPORT".

7.2 . WCAP-'10216 - PA, Rev. 2, OV Proprietary), June 1983.

WCAP-11524-A, Rev. 2, Of Non-proprietary) , March 1987.

• RELAXATION OF CONSTANT AXIAL OFFSET CONTROL AND F SURVEILLANCE TECHNICAL SPECIFICATION". O 7.3 WCAP-9272-PA. Of Proprietary) , July 1985.

l WCAP-9273-A, Of Non-proprietary), July 1985.

j " WESTINGHOUSE RELOAD SAFETY EVALUATION METHODOLOGY"

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i ATTACHMENT TWO 1

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SIGNIFICANT Mtt'.ARDF EVAIl 'T ,a j

FOR

-RELAXED AXIAL OFFSET CONTROL (RAOC) 4 T

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SJGNIFICANT IIAZARDS EVALUATl0E This amendment application includes revisions to Technical Specification Table 2.2-1 as well as Sections 3/4.2.1, 4.2.2.2 through 4.2.2.4, and 6'9.1.9 and associated Bases 1 order to implement Relaxed Axial Offset Control (RAOC) for Cycle 6 at Callaway Plant. Implementation of RAOC at Callaway will be in accordance with WCAP-10216-PA which has been previously reviewed and approved by the NRC.

The implementation of Relaxed Axial Offset Control and F Surveillance changes have been previously approved by thh NRC in WCAP-10216-PA (Proprietary) and WCAP-11524-A (Non-proprietary).

This strategy was-developed to provide wider control band widths and more-operator freedom than with Constant Axial Offset Control

- (CAOC) . RAOC provides wider control bands particularly at reduced power by effectively utilizing some of the available core L margin to'the_ peaking factor limits specified in the Corf L Operating Limits Report (COLR). The wider operating space increases plant availability by allowing quicker plant startups and increased, operating flexibility without reactor trip or reportable occurrences.

Implementation of RAOC requires the alteration of the Technical Specifications. The negative f (delta-I) penalty in Technical Specification-Table 2 2-1, Note 1 1 for the Overtemperature Delta-T (OTDT) trip setpoint will be changed to assure the validity of the design basis analysis. The value of this change is such that for each percent that the difference between percent Rated Thermal Power (RTP) in the top half of the core and percent RTP in the bottom half of the core, delta-I, is more negative than

-24%,.the OTDT trip setpoint shall automatically be reduced by 3.25% of its value at RTP, The rather involved CAOC specification is removcd-and replaced by a specification that merely-requires the Axial Flux Difference (delta-I or AFD) be maintained within the allowed operations band as a function of power. . The allowed operating space becomes the Technical Specification. If these limits are exceeded,-the condition is alarmed and the delta-I must be returned within the limits within a 15 minute. grace period or power'must be reduced to less than 50% RTP. The surveillance requirements, which are similar to those for'other alarmed limits, discuss the verification l

frequency of delta-I as a function of alarm status.

The current Technical Specification 3.2.1, per the COLR.

l specifies a target band of +8%, -7% for normal operation in Mode 1 above 15% RTP. This target band is applicable only for Cycle 5

.EOL conditions and was changed from +3%, -12% via Revision 3 of the COLR (ULNRC-2513 dated November 13, 1991). RAOC allt ss an AFD operating space relaxation to -15%, +12% delta-I at 100% RTP l and linearly increasing to -30%, +26% delta-I at 50% RTP, in Mode

,.T,- ________E__.___.

1 above 50% RTP, The RAOC AFD limits are provided in Attachment

5. If the RAOC AFD limits are exceeded for more than 15 minutes, power must be reduced to less than 50% RTP within 30 minutes and the Power Range Neutron Flux - High Trip setpoints must be reduced to less than or equal to 55% RTP within the next 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />.

An additional less restrictive action is included which takes credit for margin which exists in the Restricted AFD Operation (RAFDO) limits. This action does not require either a reduction to 50% RTP or a resetting of the Power Range Neutron Flux - High Trip setpoints. However, it does require a power reduction below the RAFDO power level. Two surveillances, consistent with the current Technical Specification 3.2.1, are included to ssure that the AFD of the operable excore channels are updated periodically to account for indication changes due to burnup. They are included here for completeness and are consistent with past practices on plant application.

Survei71ance Requirements 4.2.2.2.b and 4.2.2.4.h are revised to require ?,1miting Condition for Operation (LCO) 3.2.2 to be evaluated against the measured F Z after accounting for fuel manuf acturing tolerances and fluk(ma)p measurement uncertainty.

The intent of this change is to require use of the measured parameter to veri.fy operation below the Technical Specification LCO limit. Increasing the monitored F by an additional term for expected plant maneuvers may appea9(Z) to provide a more convenient form of assuring plant operation below the F limit. However, past practices on plant application anh(Z) recent licensing reviews of the New Standard Technical Specifications (MERITS) have demonstrated that a comparison of the safety limit and the measured Fg(Z) without adjustments for plant maneuvers is required.

The f ootnote for Surveillance Requirement 4.2.2.2.d.1 is modified-to clarify the timing required for obtaining a power distribution map during startup at the beginning of each cycle and to state that extended operation is defined as expected operation at a power level for greater than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The intent of this footnote is to allow the plant to escalate without undue impedance while still assuring consistency with the safety analysis values. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> limit prevents sustained operations at high power levels without verification of the FO(Z) safety limit.

To afford additional flexibility, Surveillance Requirement 4.2.2.2.f.2.a is added. It provides the option of an AFD operating space reduction while maintaining the same surveillance power level . This revision is consistent with WCAP-10216-PA.

Speciffcations 4.2.2.3.a and 4.2.2.4.c are revised to define k(z) and F (Z), as done in Specification 4.2.2.2.c. For RAFDO operabion, Surveillance Lequirement 4.2.2.4.f.1 is added which allows a return to normal operation in the event that sufficient margin is not available to remain in RAFDO. This requirement clarifies the action necessary in the event the plant can no longer remain in RAFDO.

Specification 6.9.1.9 is revised to reflect the change to RAOC, i.e., RAFDO only target band and RAOC references. Figure B3/4.2-1 is deleted since it is not applicable to RAOC operation.4*

The basis for AFD B3/4.2.1 is also modified to describe how RAOC and RAFDO allow operation at the maximum permissible power and AFD consistent with safety analyses. It also describes how the computer clarms function for RAOC application. The basis notes that two elarms exist. The first alarm indicates operation 1 outside tha RAOC operating space while the second indicates operation outside RAFDO.

The proposed change does not involve a significant hazards consideration because operation of Callaway Plant in accordance i with this change would not: l i

(1) Involve a significant increase in the probability or l consequences of an accident previously evaluated. The l d

RAOC-related technical specification changes do not significantly increase the probability or consequences of i any accident previously evaluated in the FSAR. No new performance requirements are being imposed on any system or  ;

component in order to support the RAOC implementation, j Subsequently, overall plant integrity is not reduced.  !

Furthermore, the parameter changes associated with RAOC O assure that the limiting safety analysis inputs (i.e. Fg, AFD and F-delta-H) are not exceeded. Mitigators to assumed "

accident scenarios, such as the f1(delta-I) penalty term in the OTDT setpoint, are not accident initiators. Therefore,  ;

the probability of an accident has r.ot increased. i The consequences of any accident previcualy evaluated in the FSAR are not increased due to the RAOC-related Technical Specification changes. Since the results of the LOCA and non-LOCA analyses remain applicable, the inputs to the dose analyses do not change. Therefore, the consequences to the public resulting from any accident previously evaluated in the FSAR has not increased.

(2) Create the possibility of a new or different kind of accident from any previously evaluated. The proposed change does not involve any design changes or hardware modifications to safety-related equinment nor will there be a change in the method by which any safety-related plant system performs its safety function. There will be a conservative trip setpoint-reducing change to the negative f,(delta-I) penalty term in the OTDT setpoint equation, as well as changes to the non-safety related AFD Monitor Alarm since penalty deviation times will be no longer be tracked or alarmed.

4 The RAOC-related Technical Specification changes do not

-create the possibility of a new'or different kind of accident than any already evaluated in the FSAR. No new accident scenarios, failure mechanisms or limiting single failures are introduced as a result of the RAOC implementation. The institution of RAOC will have no adverse effect and does not challenge the performance of any safety-related system. Therefore, the possibility of a new ar different kind of accident is not created.

(3) Involve a significant reducticn in a margin of safety. The proposed change will not result in a decrease in the minimum DNBR given in Bases Section 2.1.1 and reported in the FSAR nor will there be an increase in the peak clad temperature (PCT) above the 2200*F ECCS Acceptance Criteria limit as defined in 10CFR50.46. The design limits on peak local power density, F and F-delta-H will not be exceeded. The proposed change Oo,es not alter the manner in which safety limits or limiting safety system settings are determined.

The axial flux difference limiting condition for operation and F surveillance are revised in accordance w3 th the approhed methodology of WCAP-10216-PA.

The supporting Technical Specification values are defined by the accident analyses which are performed to conservatively bound the operating conditions defined by the Technical Specifications and to demonstrate meeting the regulatory acceptance limits. Performance of analyses and evaluations for the RAOC transition have confirmed that the operating envelope defined by the Technical Specifications continues to be bounded by the analytical basis, which in no case exceeds the acceptance limits. Therefore, the margin of safety provided by the analyses in accordance with the acceptance limits is maintained and not reduced.

Based upon the preceding information, it has been determined that the proposed changes to the Technical Specificacions do not involve an increase in the probability or consequences of an accident previously evaluated, create the possibility of a new or different kind of accident from any accident previously evaluated, or involve a significant reduction in a margin of safety. Therefore, it is concluded that the proposed change meets the-requirements of 10 CFR 50.92 (c) and does not involve a-significant hazards consideration.

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ATTACHMENT THREE ENVIRONMENTAL CONSIDERATION FOR REL7.XED AXIAL OFFSET CONTROL

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ENVIRONMENTAL CONSIDERATION This amendment application includes revisions to Technical Specification Table 2.2-1 as well as Sections 3/4.2.1, 4.2.2.2 through 4.2.2.4, and 6.9.1.9 and associated Bases in order to implement Relaxed Axial Offset Control (RAOC) for Cycle 6 at Callaway Plant. Implementation of RAOC at Callaway will be in accordancs with WCAP-10216-PA which has been previously reviewed and approved by the NRC.

The proposed amendment involves changes with respect to the use of facility components within the restricted area, as defined in 10CFR20, and changes surveillance requirements. Union Electric has determined that the proposed amendment does not involve:

(1) A significant hazard consideration, as discussed in Attachment 2 of this amendment application; (2) A signif,1 cant change in the types or significant increase in the amounts of any effluents that may be released offsite; (3) A significant increase in individual cr cumulative occupational radiation exposure.

Accordingly, the proposed amendment meets the eligibility criteria for categorical exclusion set forth in 10CFR51.22 (c) (9) .

Pursuant to 10CFR51.22 (b) , no environmental impact statement or environmental assessment need be prepared in connection with the issuance of this amendment.

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