ML20207A304

Summary of 990505 & 10 Telcons with Util Re License Renewal Application on Metal Fatique

ML20207A304
Person / Time
Site:	Calvert Cliffs
Issue date:	05/18/1999
From:	Samson Lee NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
NUDOCS 9905260259
Download: ML20207A304 (12)

Text

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/. k UNITED STATES l l ,jt NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20666-0001

)

...,+ May 18,1999 l

LICENSEE: Baltimore Gas and Electric Corporation (BGE)

FACILITY: Calvert Cliffs Nuclear Power Plant, Units 1 and 2

SUMMARY

OF MAY 5,1999, AND MAY 10,1999, TELEPHONE CALLS BETWEEN THE U. S. NUCLEAR REGULATORY COMMISSION (NRC) STAFF AND BGE REPRESENTATIVES TO DISCUSS THE BGE LICENSE RENEWAL APPLICATION REGARDING METAL FATIGUE On May 5,1999, and May 10,1999, representatives of BGE had telephone calls with the NRC staff in Rockville, Maryland, to discuss the,8GE license renewal application regarding metal i fatigue. On March 21,1999, the staff issued a safety evaluation report (SER) related to the license renewal of Calvert Chffs. Confirmatory item 3.2.3.3-1 of the staff SER addresses Generic Safety Issue 190 (GSI-190) regarding environmental effects on the fatigue resistance of metal components. On May 4,1999, and May 10,1999, BGE faxed draft responses to this '

confirmatory item to the staff (see Attachments 1 and 2, respectively). The purpose of the telephone calls was to clarify the BGE draft responses. On May 5,1999, the BGE participant was Todd Conner. The staff participants were John Fair, Kamal Manoly, Keith Wichman, and l Sam Lee. On May 10,1999, the BGE participants were Barth Doroshuk, John Rycyna, Todd Conner, Don Shaw, and Dave Lewis. The staff participants were Chris Grimes, Richard Wessman, Janice Moore, Robert Weisman, John Fair, Raj Anand, P. T. Kuo, Eugene Imbro, Keith Wichman, Ed Hackett, Syed Shaukat, and Sam Lee.

On May 5,1999, BGE indicated that its draft response followed " Option 2" in the Statements of Consideration (SOC) for the license renewal rule on addressing unresolved GSis in a license renewal application (60 FR 22484). The response was intended to provide a technical rationale that the current licensing basis will be maintained until some time after 40 years, and provide a technically feasible option to manage aging effects during the period of extended operation (see Attachment 1). The staff commented that it did not perform an "over-predictions of the number of events" in evaluating GSI-166 on fatigue, as indicated on Page 2 of the BGE draft response. i The staff assessment was based on the best information available at the time for the plants sampled. The conclusions for GSI-166 are valid for 40 years, as described in SECY-95-245.

The staff also commented on the BGE proposed option to manage environmental effects on fatigue during the period of extended operation. BGE agreed to consider the staff's comments and revise the draft response, as appropriate.

On May 10,1999, BGE discussed its revised draft response (see Attachment 2). The staff commented that the third approach described on top of Page 3 of the BGE draft response was ,

not an option. BGE agreed to delete that approach. BGE indicated that they would follow the p 0) generic resolution of GSI-190 or the approach described on Pages 3 and 4 of the BGE draft response to manage environmental effects on fatigue for the period of extended operation. The staff indicated that BGE might in fact be following " Option 3" of the SOC which states: "Another approach could be for an applicant to develop an aging management i t 9905260259 990518 PDR ADOCK 05000317 P PDR

-2 May 18,1999 plant, incorporates a resolution to the aging effects issue." (60 FR 22485). BGE indicated that it would consider the staff's comments and revise its response, as appropriate.

i h EY Sam Lee, Sr. Materials Engineer License Renewal and Standardization Branch j Division of Regulatory improvement Programs Office of Nuclear Reactor Regulation Docket Nos. 50-317 and 50-318 l cc: See next page Distribution: See next page G:\ WORKING \ LEE \ CALL _55.WPD 8/ M'T OFFICE RLSB RLSB:Kg,EMEB:BC DE:DD ) RLSB:B( ,

LA f) , _

NAME EMo'n SLee N PT KucIV Elmbro @ RWdddab CGrime%

DATE f/9/99 f//c/99 \/$99 f/&/99 5 /W99 6 / h99 i OFFICIAL RECORD COPY l

i

. Mr. Charles H. Cruse Calvert Cliffs Nuclear Power Plant Baltimore Gas & Electric Company Unit Nos.1 and 2 cc:

Mr. Joseph H. Walter, Chief Engineer President Public Service Commission of Calvert County Board of Maryland Commissioners Engineering Division )

175 Main Street 6 St. Paul Centre Prince Frederick, MD 20678 Baltimore, MD 21202-6806 James P. Bennett, Esquire

• Kristen A. Burger, Esquire Counsel Maryland People's Counsel Baltimore Gas and Electric Company 6 St. Paul Centre P.O. Box 1475 Suite 2102 Baltimore, MD 21203 Baltimore, MD 21202-1631 Jay E. Silberg, Esquire Patricia T. Birnie, Esquire Shaw, Pittman, Potts, and Trowbridge Co-Director 2300 N Street, NW Maryland Safe Energy Coalition Washington, DC 20037 P.O. Box 33111 Baltimore, MD 21218 Mr. Bruce S. Montgomery, Director NRM Mr. Loren F. Donatell Calvert Cliffs Nuclear Power Plant NRC Technical Training Center 1650 Calvert Cliffs Parkway 5700 Brainerd Road Lusby, MD 20657-4702 Chattanooga, TN 37411-4017 Resident inspector David Lewis U.S. Nuclear Regulatory Commission Shaw, Pittman, Potts, and Trowbridge P.O. Box 287 2300 N Street, NW St. Leonard, MD 20685 Washington, DC 20037 Mr. Richard I. McLean Douglas J. Walters Nuclear Programs Nuclear Energy Institute Power Plant Research Program 1776 l Street, NW.,

Maryland Dept. of Natural Resources Suite 400 Tawes State Office Building, B3 Washington, DC 20006-3708 )

Annapolis, MD 21401 DJW@NEl.ORG Regional Administrator, Region i Barth W. Doroshuk U.S. Nuclear Regulatory Commission Baltimore Gas and Electric Company 475 Allendale Road Calvert Cliffs Nuclear Power Plant King of Prussia, PA 19406 1650 Calvert Cliffs Parkway NEF 1st Floor National Whistleblower Center Lusby, Maryland 20657 3233 P Street, N.W.

Washington, DC 20007 Mr. Charles H. Cruse, Vice President Nuclear Energy Division Baltimore Gas and Electric Company 1650 Calvert Cliffs Parkway Lusby, MD 20657-4702

e r g -Q Distribution:

Hard copy PUBLIC l N. Dudley, ACRS - T2E26 E. Hylton E-mail:

R. Zimmerman W. Kane D. Matthews S. Newberry C. Grimes C. Carpenter B. Zaleman J. Strosnider R. Wessman E. Imbro W. Bateman J. Calvo H. Brammer T. Hiltz G. Holahan T. Collins C. Gratton B. Boger R. Correia R. Latta J. Moore J, Rutberg R. Weisman 4 M. Zobler M. Mayfield S. Bahadur J. Vora A. Murphy D. Martin W. McDowell -

S. Droggitis ' V J 'A 01 RLSB Staff T.Kenyon J. Fair K. Manoly .

l K. Wichman E. Hackett S. Shaukat f J. Muscara l M.McNeil J. Craig

MAY-04-1999 14:46 BALTIMORE GAS & ELECTRIC 410 495 6946 P.02/05 DRAFT

• Draft Calvert Cliffa Plant Specific Response to GSI-190 (Draft 3.Mey-99)

This paper propoties an approach for addrsasing GSI-190 in the Calvert Cliffs license renewal proceeding.

The approach is based on the Statement of Considerations (SOC) for Part 54, which identifies several options by which an applicant may address an existing GSL GSI 190 pertains to the adequacy of fatigue design when environmental effects are considered. Section 1.5, item 3.2.3 31 of the Calvert Cliffs License Renewal SER states the following Confirmatory item:

• ){ generic safety issue (GSI) 190 is not resolved generically prior to CCNPP operation in the extended period, the applicant must adequately resolve environmental eWects on high usage factors with bounding analyses or a monitoring program on a plant-apecific basis.'

BGE is concemed that the wording of this confirmatory hem might be interpreted as prohibiting operation past the fortieth year and appears more restnative than is necessary. Accordingly, the following attemative is suggested.

The SOC for Part 54 establishes several means by which a GSI relating to aging could be addressed One of j the approaches is as follows:

'An applicant may choose to submit a technical rationale which demonstrates that the CLB will be maintained until some later point in time in the period of axtended operation, at which point one or more reasonable options (e.g. replacement, analytical evaluation, or a surveillance / maintenance program) would be available to adequately manage the effects of aging. (An applicant would have to describe its basis for concluding that the CLB is maintained, in the license application, and briefly desenbe options that are technically feasible during the period of extended operation to manage the effects of aging, but would not have to er"t which motion would be n=M )' l 60 Fed. Reg. at 22,485. The essential elements of this option are: (1) a rationale that the CLB will be maintained until some point in the penod of extended operation; (2) a technically feasible option for subsequently managing aging. The technically feasible option only needs to be *briefly" desenbod and does not have to be preselected. These two elements are addressed in tum below:

1. Rationale That The CLB Will Be Maintained Until Some Point in the Period of Extended Operation in closing GSI 186, the NRC concluded that the environmental effects associated with fatigue are not safety significant through the end of the current license (i.e.,40 years). This conclusion was primarily based on two studies. The first study was published as NUREG/CR.6260. This study applied the revised fatigue design curves that incorporated the environmental effects to several plant locations via a detailed fatigue analysis.

The analyses were required to re-silocate of design cycles from less likely transients to more likely transients in order to demonstrate usage factors (CUF's) less than 1.0. A second study was performed which was a risk analysis considering fatigue failures. The risk analysis considered the application of the design cycles over a 40 year period, and the effects on core damage frequency when environmental effects are applied. This second study concluded that there is little to no risk significance over the current license period. These two studies formed the primary basis for concluding that the effect of environment on the fatigue life of LWR plant components is not a concem for 40 years. It is important to note that there were no specific limitations or restrictions placed on Icensees beyond compliance with their current licensing basis (i.e., fatigue analysis using the ASME Design Fatigue curves and specified trans'ents).

Closure of GSI 166 resulted in the initiation of GSI-190 which limited the concem regarding the effects of environment on the fatigue life of LWR components to operation beyond a 40 year period. While the studies that were performed for GSI 166 were framed in 40 year operating p6tiod, the effects of fatigue are not directly dependent on time in service. Instead, fatigue effects are dependent on number and magnitude of operating transients or cycles. It is understood that more cycles will generally occur the longer an item is operated.

The Current Licensing Basis with regard to fatigue is to ensure that the overall CUF is maWtained less than 1.0 based on the application of various transients. Therefore, for each component there are a multiple transients each with an assumed number of occurrences. One of the features of the CCNPP fatigue monitoring syste.m is a cycle tracking function. This function tracks those transients which have a meaningful or significant impact on the fatigue life plant components. The table below lists those controlling trans'ents, l

and presents a straight line projection of the number of events of each type for a 40 year and a 60 year per6od.

• 8' ' Attachment 1

MAY-04-1999. 14:47 BALTIMORE GAS & ELECTRIC 410 495 6946 P.03/05 DRAFT I

- Draft Calvert Cliffs Plant Specific Response to GSI 190 (Draft- 3-May-se)

An important observation is that the actual number of the events will not begin to approach the allowable number of events.

e m. ,. g.. . . :isinq40YearPfediction.u60Yearfredidions;j: Allowable ,

~

c un Event".' .,diT',T, Je.. .*,#n.i.'.d.w . it t rvj u. n. .i,t, 2.'i!@unitt.

~. .. , . ..n - . yn.U.n.it.

- . ..2 :fJ.u..

-  !!,WF :. ! , , J' RCS Hestup 162 125 243 188 500 RCS Cooldown 162 125 243 188 500 PZR Hestup 172 127 S32 190 600 PZR Cooldown 172 127 262 190 600 Reactor Tnp 205 181 308 271 400 Turbine Trip (U1 only) 8 - 13 - 40

' Shutdown Aanlina 29 25 44 38 600 1 aan of Charaina 214 255 322 383 1400

' Loss of Letdown 78 39 117 58 200 unin Sorav AM"a6^n 3 1 6 1 120

• Aur Enrav AM"=6an 29 30 43 45 120 Main Feedwater SG11 195 465 293 697 15000 Main Feedwater SG12 195 452 293 878 15000 Aux Feedwater SG11 275 304 413 456 16000 Aux Feedwater SG12 253 370 380 656 15000 Loss of Secondary 2 2 3 3 5 j Pressure Loss of all RCS Flow 13 3 20 6 40 Safety injection 5 0 8 0 160 i

RCS Laak Test 5 3 8 6 320 RCS Hydro Test 7 .5 10 8 10 SG Leek Test 17 0 26 0 320 l Seismic 0 0 0 0 200

$1 Check Valve Transient 0 0 0 0 160 This observation supports a general assertion that fundamentally, the fatigue outy seen over a 60 year period i do not differ from those seen over a 40 year period. Furthermore, the design allowable cyclic limitations which define the fatigue duty and were included in the two studies performed under GSI-166 are generally gross over-predictions of the number of events. While not presented herein, a sirnilar generalization can be made on actual severity of events relative to the design severity. Thus, it is reasonable to conclude that the 5ndings of GSI 186 regarding the ability to maintain an items within the limitations of the CLB are applicable for some period beyond 40 years (i.e., into the renewal period).

Page 2 of 4

11AY-04-1999 14847 BALTit10RE GAS & ELECTRIC 410 495 6946 P.04/05 DRAFT

. Draft Calvert Cliffs Plant Specmc Response to G51-190 (Draft May 99)

In sum, the NRC concluded in GSI-166 that environmental effects assoaisted with fatigue are not safety significant for the initial license term. Since the fatigue design in the initial license term is not based on any fixed term, but is instead based on an allowable number of cycles, there is a logica1 basis to extend the conclusion of GSI-166 past the fortieth year of operation as long as the initial allowable number of cycles is not exceeded. The projections for Catvert Cliffs demonstrates that continued operation in the period of extended cperation will be bounded by the number of cycles that is allowable in the initial term.

2. Technically Feasible Option for Managing Fatigue While the technical rationale above might logically be used to justify continued operation for the entire period of extended operation, BGE has identified a programmatic approach that could be applied earlier in the period of extended operation to provide added assurance that the environmental eflects are being adequately managed. In the absence of a generic resolution to GSI-190, the environmental effects of high usage components will be managed by the Fatigue Monitoring Program (FMP) with minor modifications to account for the environmental effects The following is a brief description of one possible way in which this can be performed.

There is a subset of plant location which may be in jeopardy of exceeding a CUF of 1.0 when the effects of environment are applied to the fatigue analysis. A review of the current research findings indicates ,hst this subset would be items which have a CUF > 0.67. This number was determined by taking the maximum cnticipated net Fen (i.e., the total adjustment for environment on the overall CUF of an item), and determining the resultant uncorrected CUF that would equal 1.0 when correct by Fen. The maximum net Fen is bounded 1 by 3.0 ( which is not meant to imply that a value of 3.0 will be seen). The existing ASME design curves have a factor of 20 on cycles and 2 stress which ever is most limiting, applied to the mean fatigue curve. For stainless steels, the factor of two on the mean failure curve is actuaHy approximately equal to a factor of 1.6 for cycle lives greater than 10. Of this factor of 20, a factor of 4 is attributable to data scatter (caused in part by environmental effects), and surface finish. If only half of this factor is applied attributed to environmental effects (i.e.,2.0), then the following is true; Max. Fen-off= Max. Fen /2.0 = 1.5 Ueny = Fen-off *U For Ueny < 1.0 ;

U < Uenv/ Feneff = 1.0/1.5 = 0.67 Therefore, all locations with uncorrected usage factors less than 0.67 would not be able to exceed a corrected CUF of 1.0 if adjusted for environmental effects. For locailons that do exceed an uncorrected CUF of 0.67,  ;

the Fen approach could be applied using the latest and most appropriate conelations for Fen. Currently it cppears that a correlation similar to following may be appropriate:

Fen = exp[0.935 + q*(T,-T O )*

The Fen approach would be applied in the following manner; in general a CUF is calculated by summing the effects of fatigue damage for individual transients or more correctly transient pairs.

)

I U :=n.E, u,

'Jaske, C.E.,0;Donnell W.J.

• Fatigue Design Critieria for Pressure Vessel Alloys, Joumal of Pressure Vessel Technology, Vol. 99, Nov.1977

)

8 Chopra, O.K., *Effect of LWR Coolant Environment on Fatigue Design Curves of Austenitic Stainless Steels, NUREGICR-5704. l Page 3 of 4

MAY-04-1999 14:48 BALTIMORE GAS & ELECTRIC 410 495 6946 P.05/05 N

DRAFT

, Draft Calvert Cliffs Plant Specific Response to GSI-190 (Draft- 3-May-99)

Where U is the overall CUF and u,is the usage atributable to an individual transient pair. When applying the Fen approach to this methodology, u,is increased by a factor equal to Fen-eff for those load pairs which meet the threshold criteria for enviromental conoems (e.g., T > 250*C, s'* < 1%/sec). Fen-off is determined by dividing the Fen from the above equation by the ASME design factor which is attributable to enviromental effects, similar to that shown above in the developemnt of the unccorrect CUF screening value.

The fatigue evaluation would now be performed in the following manner:

For load pairs which do not exceed the temperature threshold or do not fa!! below the strain rate threshold, U would be found by the following:

U, = lu, n.i For load pairs which do exceed the temperature threshold or fall below the atrain rate threshold, U would be found by the following:

U, = [u,* F,_,

n.i The overall corrected CUF would then be:

U = U$ + Un The fatigue monitoring program can be modified to track limiting locations in the manner described above.

This wil! provide a reliable CUF tracking method to ensure that no locations will exceed a corrected CUF of 1.0. If during the renewal period any locations are found to approach 1.0, they will be addressed in the corrective actions program prior to the CUF exceeding 1.0 in the manner described for the fatigue montoring program in the BGE License Renewal Application. The corrective measures would typically take one of three forms, (a) re analyze to reduce the CUF, (b) Repair / Replace, or (c) Monitor the location with NDE (e.g., i Section XI Appendix L).

Page 4 of 4

. _ _ _ . _ _ _ _ _ _ . _ . _ ~ . _ . _ _ . _ . . _ _ _ _ _ _ _

ww=www m vsraunwtnnsam a w neen o m nww

- DRAFT Draft Calvert Cliffs Plant Specific Response to GSI 190 Related to Austenitic Materials se (Draft- B.May-99) j This paper proposes an approach for addressing GSI-1g0 in the Calvert Cliffs license renewal proceeding.

The approach is based on the Statement of Considerations (SOC) for Part 54, which identifies several options ,

I by which an applicant may address an existing GSI.

GSI-190 pertains to the adequacy of fatigue design when environmental effects are considered. Section 1.5, item 3.2.3.3-1 of the Calvert Cliffs License Renewal SER states the following Confirmatory item:

• lf genenc safety issue (GSI) 190 is not resoked generically prior to CCNPP operation in the extended period, the applicent must adequately resolve environmental eWects on high usage factors with bounding analyses or a monitonng program on a plant-specific basis."

BGE is concemed that the wording of this confirmatory item might be interpreted as prohibiting operation past the fortieth year and appears more restrictive than is necessary. Accordingly, the following alternative is suggested.

The SOC for Part 54 establishes several means by which a GSI relating to aging could be addressed. One of the approaches is as follows:

'An applicant may choose to submit a technical rationale which demonstrates that the CLB will be maintained until some later point in time in the period of extended operation, at which point one or '

more reasonable options (e g. replacement, analytical evaluation, or a surveillance / maintenance program) would be available to adequately manage the effects of aging. (An applicant would have to describe its basis for concluding that the CLB is maintained, in the license application, and briefly desenbe options that are technically feasible during the period of extended operation to manage the effects of aging, but would not have to preselect which option would be used.)" <

60 Fed. Reg. at 22,465. The essential elements of this option are: (1) a rationale that the CLB will be maintained until some point in the period of extended operation; (2) a technically feasible option for subsequently managing aging. The technically feasible option only needs to be 'briefly" described and does not have to be preselected. These two elements are addressed in tum below:

1. Rationale That The CLB Will Be Maintained Until Some Point in the Period of Extended Operation in closing GSI-166, the NRC concluded that the environmental effects associated with fatigue are not safety significant through the end of the current license (i.e.,40 years). This conclusion was primarily based on two studies. The first study was published as NUREGICR-6260. This study applied the revised fatigue design curves that incorporated the environmental effects to several plant locations via a detailed fatigue analysis.

The analyses were required to re-allocate of design cycles from less likely transients to more likely transients in order to demonstrate usage factors (CUPS) less than 1.0. A second study was performed which was a risk analysis considering fatigue failures. The risk analysis considered the application of the design cycles over a 40 year period, and the effects on core damage frequency when environmental effects are applied. This second study concluded that there is little to no risk significance over the current license period. These two studies formed the primary basis for concluding that the effect of environment on the fatigue life of LWR plant components is not a concem for 40 years.

Closure of GSI-166 resulted in the inheten of GSI-190 which limited the concem regarding the effects of environment on the fatigue life of LWR components to operation beyond a 40 year period. While the studies that were performed for GSI 166 were framed in 40 year operating period, the effects of fatigue are not directly dependent on time in service. Instsad, fatigue effects are dependent on number and rnagnrtude of operating transients or cycles. It is understood that more cycles will generally occur the longer an item is operated. The Current Licensing Basis with regard to fatigue is to ensure that the overall CUF is maintained less than 1.0 based on the application of various transients. Therefore, for each component there are a multiple transients each with an assumed number of occurrences. One of the features of the CCNPP fatigue monitoring system is a cycle tracking function. This function tracks those transients which have a meaningful or significant impact on the fatigue life plant components. The table below lists those controlling transients, and presents a straight line projection of the number of events of each type for a 40 year and a 60 year period.

Page 1 of 4 Attachment 2

ver-% % s:r w to uxgvwegictrLR@tWR GS$ @ @946 P.03/05 )

)

DRAFT Draft Calvert Cliffs Plant Specific Response to GSI-190 Related to Austenitic Materials (Draft hMey-99)

An important observation is that the actual number of the Events will not begin to approach the allowable number of events.

I k' , .hh [ .

RCS Heatup 162 125 243 188 500 RCS Cooldown 162 125 243 188 500 PZR Hestup 172 127 252 190 500

~ PZR Cooldown 172 127 252 190 500 ReactorTrip 205 181 308 271 400 Turbine Tnp (U1 only) 8 - 13 - 40

• Shutdown Coodna 29 25 44 38 500

• Loss of Charging 214 255 322 383 1400

• Loss of Letdown 78 39 117 58 200

• Main Spray Actuation. 3 1 5 1 120 l

' Aux Spray Actuation 29 30 43 45 120 J Main Feedwater SG11 195 465 293 697 15000 Main Feedwater SG12 195 452 293 678 15000 Aux Feedwater SG11 275 304 413 456 15000 Aux Feedwater SG12 253 370 380 556 15000 Loss of Secondary 2 2 3 3 5 Pressure

-LDas of all RCS Flow 13 3 20 5 40 Safety injection 5 0 8 0 160 RCS Leak Test - 5 3 8 5 320 RCS Hydro Test 7 5 10 8 10 SG Leak Test 17 0 26 0 320 Seismic 4 0 0 0 0 200 St Check valve Transient 0 0 0 0 160

2. Technically Feasible Option for Managing Fatigue in the period of extended operation, additional actions may be taken to ensure that the CLB is maintained for the duration of the renewal period There are three such actions which can be taken, any one would ensure that the CLB will continue to be met. These are:

1. Generic resolution of GSI-190. This may or may not require actions to be taken by individuallicensees.

Pa9e 2 of 4

nearwrwma esrnuwnestnswas earumm v.wres

' DRAFT Draft Calvert Cliffs Plant Specific Response to GSI 190 Related to Austenitic Materials (Orsft hMay-99)

' 2. Implementation of an approach similar that outlined later in this discussion.

3. Implementation of a set of actions or an approach yet to be developed and accepted by the Regulatory authorities.

Description of one acceptable method to manage environmental effects (Option 2)

The following is a brief description of resolution option 2 above. This approach is being described to demonstrate that a technically feasible approach current exists short of a generic resolution, that would ensure the environmental impact on fatigue is managed through the renewal period The Fatigue Monitoring Program (FMP) is described in the CCNPP LRA and again in the License Renewal SER. This program has identified a subset of locations in the systems for which fatigue must be managed which bound all other plant locations. That is to say, the fatigue demands placed on the individuallocations are greater than those placed on any other location in the same system. The FMP then monitors the actual demands placed on the bounded locations to monitor the current usage factor. As the usage factor approaches unity, corrective actions are taken to ensure that a CUF=1.0 is not exceeded.

Prior to continued operation beyond the term of the initial plant license (i.e.,40 years), the effects of environment on the bounded locations which are monitored can be incorporated into the FMP. These effects can incorporated using the Fen approach as described in EPRI TR-10575g and TR-107515 except as ~

modified herein.

Calculation of the effective Fen The effective Fen (Fen-eff)is established by determining the ratio of the allowable number cycles based on air curves at room temperature, to the allowable number cycles based on LWR environment curves at the operating temperature. This ratio is called Fen. The Fen will be determined using the latest and most appropriate correlations for Fen. Currentty it appears that a correlation similar to following may be appropriate:

Fen = exp[0.935 + n*(T,*-T *07 To convert from Fen to the Fen eff, the Fen is divided by an environmental factor (EF). This factor represents the portion of the ASME Code design factorwhich is attributable to environmental effects. The value of this factor is currently under debate, however, the NRC is of the opinion that this factor should be 1.5. The industry believes that the EF should be 2.0. However, using 1.5, the Fen-eff would be found by the following:

Fen-eff = exp[0.935 + ri (T,*-T,*0*)/1.5 but, not less than 1.0 Application of the Fen eff in general a CUF is calculated by summing the effects of fatigue damage for individual transients or more correctly transient pairs.

U-Zu,U=[u, n-i n.:

Where U is the overall CUF and u,is the usage attributable to an individual transient pair. When applying the effective Fen approach to this methodology, ui si increased by a factor equal to Fen eff for those load pairs which meet the threshold criteria for environmental concems (e.g., cu'rently proposed as: T > 200*C. c <

1%/sec).

The fatigue evaluation would now be performed in the following manner: l

' Chopra, O.K., *Effect of LWR Coolant Environment on Fatigue Design Curves of Austenitic Stainless Steels, NUREG/CR-5704.

Page 3 of 4

MAY-10-1999 00:21 B:LTIMORE GAS & ELECTRIC 410 495 6945 P.25/25 DRAFT

.I

Draft Calvert Cliffs Plant Specific Response to GSI 190 Related to Aus nitic Materials (Draft -May-99)

For load pairs which do not exceed the temperature threshold or do not fall below the strain rate threshold, U would be found by the following:

U, = [u, U, = [u, n-i n.i For load pairs which do exceed the temperature threshold or fall below the strain rate threshold, U would be found by the following:

U-[u,*F,,U,=[u,*F,,.,

2 nel n=l The overall corrected CUF would then be:

U = U, + U, The fatigue monitoring program can be modified to track limiting locations in the manner described above. {

This will provide a reliable CUF tracking method to ensure that no locations will exceed a corrected CUF of l 1.0. If during the renewal period any locations are found to approach 1.0, they will be address,ed in the corrective actions program prior to the CUF exceeding 1.0 in the manner described for the fatigue monitoring program in the BGE Ucense Renewal Application. The corrective measures would typicalty take one of three forms, (a) re analyze to reduce the CUF, (b) Repair / Replace, oc (c) Monitor the location with NDE: (,,g,,

Section XI Appendix L).

l

)

I l

I 8 Application of NDE methods such as Appendix L would require regulatory approval. Such methods require care to ensure that the analytical approach and the NDE technique and qualifications (e.g.,Section XI Appendix Vill) are suitable for the application (i.e., material, geometry, and type loading).

Pa0e 4 of 4 TOTAL P.05