ML20207B376

Application for Amend to License NPF-39,revising Tech Specs Re Operation W/Partial Feedwater Heating & Increased Core Flow Limits.Certificate of Svc Encl.Related Correspondence

ML20207B376
Person / Time
Site:	Limerick
Issue date:	11/17/1986
From:	Daltroff S PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:
Shared Package
ML20207B375	List: ML20207B370 ML20207B376 ML20207B380 ML20207B389 ML20214E477
References
OL, NUDOCS 8611240190
Download: ML20207B376 (17)

Text

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n W E.S N D( g DCLKETED BEFORE THE UNITED STATES NUCLEAR REGULATORY COMMISSION GFFIO. , ' ,

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B ; A i-In the Matter of  : y,

Docket No. 50-352 PHILADELPHIA ELECTRIC COMPANY APPLICATION FOR AMENDMENT OF 4

FACILITY OPERATING LICENSE NPF-39 s

Edward G. Bauer, Jr.

Eugene J. Bradley 2301 Market Street Philadelphia, Pennsylvania 19101 Attorneys for Philadelphia Electric Company t

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BEFORE THE UNITED STATES NUCLEAR REGULATORY COMMISSION In the Matter of  :

Docket No. 50-352 PHILADELPHIA ELECTRIC COMPANY APPLICATION FOR AMENDMENT OF FACILITY OPERATING LICENSE

. NPF-39 Philadelphia Electric Company, Licensee under Facility Operating License NPF-39 for Limerick Generating Station Unit No.

1, hereby requests the deletion of License Condition 2.C.13, which prohibits the use of partial feedwater heating in order to extend the fuel cycle, and changes to the Technical Specifications contained in Appendix A of the operating license as indicated by vertical bars in the margin of pages vi, 3/4 2-8, 3/4 2-9, 3/4 2-10, 3/4 3-60, 3/4 4-2 and B3/4 2-5 and the addition of pages 3/4 2-8a and 3/4 2-10a.

Philadelphia Electric Coinpany requests these changes in order to permit operation of the unit with Partial Feedwater

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Heating (PFH) and Increased Core Flow (ICF) limits in order to

) extend the fuel cycle and provide increased operational j flexibility.

1 l Discussion l The changes which are sought are necessary to allow for i

j extension of'the operating cycle and to provide increased

] operational flexibility of the plant. Section 15.0 of the Limerick Safety Evaluation Report (NUREG-0991) recognizes that i prior to operation with partial feedwater heating, additional 1

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analyses must be provided to the NRC explaining the impact of this mode of operation on minimum critical power ratio. License Condition 2.C.13 implements the NRC staff position that until I these supplemental analyses are provided, the NRC staff Will f condition the Limerick license to preclude operation of the l facility in this mode.

I The length of time between successive refueling l

j shutdowns may be extended for several months by proper fuel management techniques and taking advantage of the BNR operating j characteristics, particularly through the use of negative i

moderator and fuel reactivity coefficients (especially the BWR  !

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{ void coefficient). The use of "coastdown mode" in which all power control rods are " full-out" to extend the cycle has been

made in a large majority (over 70%) of recent BWR operating 1

cycles. This is usually accomplished at reduced thermal power [

. with commensurate feedwater temperature and steam pressure L- - -- - - - . _ - -

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l conditions. Continued operation is possible because reduced l steam voids, reduced fuel temperature and reduced equilibrium i

xenon yield reactivity gains which compensate for reactivity

] losses due to depletion of fissionable material. Additionally, 1

increased core flow and feedwater temperature reduction have also been effectively utilized for cycle extension.and to provide i additional enhancement to operational maneuverability.

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Increased Core Flow (ICP)

The negative void coefficient effect is used to advantage in all boiling water reactors via changes in the recirculation flow control feature of reactor operation. With the control rods at the pre-set position, power level can be changed by 1

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changing core flow via changes in recirculating pump speed.

The increased flow serves to sweep the voids from the core j thus increasing moderator density with the attendant increase in reactivity and hence power level. The resulting power

, level changes are nearly linear with flow changes and the flux distribution changes during the flow manipulations are i

small. Limerick Unit 1 has the capacity to provide core flow

in excess of rated conditions and, as such, increased core i

flow provides a valuable method of extending full power capability beyond the " reactivity life" at rated conditions.

An l'ncrease of 5% in flow capability provides an estimated

one to two weeks extension of full power cycle length.

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Partial Feedwater Heating (PFH)

Reduction in feedwater temperature by intentionally removing feedwater heaters from service causes colder water to flow into the reactor vessel. Colder feedwater mixing with the reactor water increases core subcooling thereby decreasing steam voids in the core, which in turn increases core reactivity because of the increased moderator density. In addition, Final Feedwater Temperature Reduction (FFWTR) permits better utilization of the fuel in the lower region of the core. FFWTR can extend the fuel cycle for up to two to three weeks for a maximum feedwater temperature reduction of 60 degrees F while maintaining core thermal power at or near rated value prior to commencement of normal coastdown and reduce the rate or electrical power fall-off during the coastdown period. This occurs because an increased fraction of core power is used for the heating rather than vaporization of core water with reduced feedwater temperatures. Moreover, fuel at the bottom of the core which has received less exposure during the cycle than fuel higher in the core is now available and provides a source of increasing reactivity to maintain rated, or near rated, power thereby reducing the rate of coastdown. Although steam flow to the turbine is reduced, this is offset by the reduction in extraction steam which would be utilized to heat the feedwater, ultimately resulting in a greater portion of the steam being used to generate electrical power. For this reason, the rate of fall-off in electrical power is less than

e the rate of fall-off in steam production. Although the overall thermal efficiency is less than that at normal rated conditions, significant measurable benefit is achieved through improved fuel utilization. The gains to cycle length from FFWTR are additive to those from increased core flow.

Extension of cycle length is not the only benefit to be gained from the use of these two techniques; they also provide significant operational flexibility.

(1) By utilizing the proposed changes regarding FFWTR, it will be pcssible to operate at any time during the cycle with Feedwater Heaters Out-Of-Service (FWHOS), thus providing for maintenance or other contingencies without removing the unit from service.

(2) Operation with core flow in excess of 100% rated allows for improved utilization of the fuel and greater capacity factors during the operating cycle. Increased core flow results in achievement of rated power over a broader operating range.

Rated power is obtainable over a core flow ranging from 87% of rated to maximum allowable core flow. Full power is obtained by following the rated load line up to 100% rated power and then increasing flow from 100% to maximum available flow or by .

ascending to power along load lines to either side of the rated load line within the power / flow map.

Examples concerning the benefits afforded by operation with core flow in excess of 100% of rated are discussed below A. The ultimate power / flow condition attained following plant startup is dependent on the initial xenon conditions of the core as follows:

(1) Xenon free startups with core reactivity increasing with exposure usually result in a flow-limited power derate because power ascension along the 100% load line cannot be maintained without resorting to control rod withdrawal at higher power levels to cor.pensate for xenon buildup. Xenon free startups may require plant maneuvering within the fuel Preconditioning Interim Operating Management Recommendation (PCIOMR) to reach and maintain 100% power. ICF operational flexibility simplifies the PCIOMR implementation by allowing rated power to be attained at greater than rated flow.

(2) Startup with peak xenon entails significant care to ensure that the subsequent xenon burnout transient does not carry power into an unanalyzed operating region.

This problem is largely diminished by the flexibility of operating at increased core flow rates.

i l B. The ultimate power / flow condition is also dependent on target f

rod patterns for various times in the operating cycle:

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(1) Early in the cycle, increased core flow and the target l rod pattern would result in rated power operation near i t j the highest permissible flow (105% of rated). As l

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gadolinium depletes and the core becomes more reactive, core flow is reduced to maintain rated power.

(2) Increased core flow capability is useful during late-cycle control rod adjustments. Under these conditions, core reactivity is decreasing with accumulating exposure. Periodic adjustments are needed to maintain full power because the core goes through a mini-coastdown between adjustments resulting in a capacity factor loss. The use of increased flow rates during these periods can result in higher capacity factors by allowing continued full power operation between adjustments or by extending the adjustment interval.

4 Description of Changes The proposed deletion of License Condition 2.C.13.is requestedtopermitoperationofLimerickUnit1withpartjal feedwater heating and to reflect that the additional analyaes which were the bases for this condition have been provided to the NRC. Changes requested to Limiting Conditions for Operation contained on pages 3/4 2-8, 3/4 2-9, 3/4 2-10 and the addition of pages 3/4 2-8a and 3/4 2-10a are all necessitated in order to .

provide. proper Minimum Critical Power Ratio operating limits for operation with partial feedwater heating and/or increased core flow.

In order to accommodate increased core flow operation, it is necessary to change the values contained on page 3/4 4-2 for the Recirculation Pump MG set scoop tube mechanical and electrical stops and the Upscale Trip Setpoint and Allowable Values contained on page 3/4 3-60 for the Reactor Coolant System recirculation flow. Finally, the Rod Block Monitor Upscale Trip setpoint and Allowable values contained on page 3/4 3-60 are changed as necessary to accommodate the addition of a High Flow-Clamped rod block to assure that the 106% and 109% rod blocks currently included in the Technical Specifications (based upon a 100% flow maximum) remain in force.

The remaining page changes are administrative in nature and reflect the updating of the Index and incorporation of the General Electric analyses as a reference.

Additionally, corrections of typographical errors are made to pages vi (Fuel type for Figure 3.2.1-3 incorrectly typed as P8CIB263 vice 163) and 3/4 2-8 (use of colon rather than period in the Figure number).

Safety Discussion General Electric Company (G.E.) has provided the .

necessary Safety Evaluation concerning the requested changes to the Technical Specifications. G.E. report, NEDC 31323, titled Increased Core Flow and Partial Feedwater Heating Analysis for Limerick Generating Station Unit 1 Cycle 1, and Errata and Addenda Sheet No. 1 dated November 6, 1986 are filed herewith and incorporated herein. This safety evaluation shows that Limerick Generating Station (LGS) Unit 1 can increase core flow to operate within the region of the operating map bounded by the line between 100% power, 100% core flow (100, 100) and 100% power, 105% core flow (100, 105) throughout Cycle 1. This safety evaluation includes analysis to show that LGS Unit 1 can operate with Partial Feedwater Heating (PFH) resulting from certain stages or strings of individual Feedwater Heaters Out-Of-Service (FWHOS) during the cycle or valved out at the end of the cycle (Final Feedwater Temperature Reduction (FFWTR)), up to a maximum feedwater temperature reduction of less than or equal to 60 degrees F at rated power and up to a maximum core flow of 105% of rated. After reaching End-of-Cycle 1 (EOCl) exposure (depletion of full power reactivity under standard feedwater conditions) with all power control rods out, LGS Unit 1 can continue to operate in the region of the operating map bounded by the 105%

core flow line between 100% power and the cavitation interlock power with or without FFWTR of less than or equal to 60 degrees F at rated power.

The Minimum Critical Power Ratio (MCPR) operating limits are requested to be changed from the values established by the Final Safety Analysis Report licensing submittal to appropriate values for Increased Core Flow (ICF) and Partial Feedwater Heating (PFH) operating conditions. All other operating limits established in the Cycle 1 licensing basis have been found to be bounding for the ICF and PFH operations as defined above.

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The prohibition against the use of PFH via FFWTR to extend the normal fuel cycle (License Condition 2.C.13) is based upon the lack of analyses, at the time of the issuance of the license, concerning this operating mode (Section 15.0 SER). This amendment request provides those analyses and demonstrates the acceptability of that mode fo'r LGS 1.

Significant Hazards Consideration The NRC has provided guidance (51 FR 7751) of those changes which are not likely to constitute a significant hazards consideration. One of the examples (vi) states, "A change which either may result in some in:rease to the probability or consequences of 'a previously analyzed accident or may reduce in some way a safety margin, but where the results are clearly within all acceptable criteria ..." this example envelopes those changes requested by this Request for Amendment.

Licensee has determined that the changes requested herein do not constitute a significant hazards consideration in that the changes requested herein do not:

1) involve a significant increase in the probability or .

. consequences of an accident previously evaluated because these changes are clearly bounded by the analyses provided in the FSAR. All abnormal operational transients analyzed in the FSAR have been examined for effects caused by ICP and/or PFl! operation. Both ICP

1 and PFH operation result in a decrease in core voids .

which, in turn, results in a less bottom-peaked power  ;

distribution and a less effective scram reactivity. The limiting abnormal operational transients have been re-l evaluated in detail: generator load rejection with bypass failure and feedwater controller failure to maximum demand. The loss-of-coolant accident, fuel l loading error accident, rod drop accident, and rod l l

withdrawal error event have also been evaluated for ICF l l

and/or PFH operation; ,

11) create the possibility of a new or different kind of accident from any previously analyzed in that operation l

with partial feedwater heating or increased core flow merely' changes slightly the assumptions (initial  ;

conditions or final conditions) utilized in existing analyses and do not provide any new accident mode; 111) involve a significant reduction in a margin of safety.

The'results of the safety evaluation show that the current Technical Specifications, with the exception of the MCPR operating limits, are adequate to preclude the

. violation of any Safety Limits for ICP and/or PFH l

operation. Accordingly, the MCPR operating limits are .

revised to assure that the margin of safety is maintained as demonstrated in the analyses provided by l General Electric Report NEDC-31323, " Increased Core Flow and Partial Feedwater Heating Analysis for Limerick

, Generating Station Unit 1 Cycle 1."

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Therefore, based on the above considerations, the requested changes to the Technical Specifications do not involve a significant hazards consideration.

Environmental Consideration These modifications and the associated changes to the Technical Specifications will not result in any increase in the amount or result in any changes in the types of any effluent which may be released off-site, and there is no significant increase in individual occupational radiation exposures.

The Plant Operations Review Committee and the Nuclear Review Board have reviewed these proposed changes to the Technical Specifications and have concluded that they do not involve unreviewed safety questions or involve Significant Hazards Considerations and will not endanger the health and safety of the public.

Respectfully Submitted, PHILADELPHIA ELECTRIC COMPANY

. By .

1 41 b, Vice~ President //

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COMMONWEALTH OF PENNSYLVANIA :

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COUNTYOFPHkLADELPHIA  :

S. L. Daltroff, being first duly sworn, deposes and says:

That he is Vice President of Philadelphia Electric Company, the Applicant herein; that he has read the foregoing Application for Amendment of Facility Operating License and knows the contents thereof; and that the statements and matters set forth therein are true and correct to the best of his knowledge, information and belief.

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W ditT , /

/ i Subscribed and sworn to before me thislY day of Du.

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"} Notary Public JUDITH Y. FRANKLIN Notary PuMic, Phila PhilJ. Co.

My Commission Empires July 28,1987

UNITED STATES OF AMERICA NUCLEAR REGULATORY C0>611SSION Before the Atomic Safety and Licensing Board 4

In the Matter of  : Docket No. 50-352 PHILADELPIIIA ELECTRIC COMPANY  :

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(Limerick Generating Station,  :

Unit No. 1)  :

CERTIFICATE OF SERVICE I hereby certify that copies of Philadelphia Electric Company's Application for Amendment of Facility Operating License NPF-39 in the above-captioned matter were served on the following by deposit in the United States mail, first-class postage prepaid on this 18th day of November,1986.

Kathryn S. Lewis, Esquire Atomic Safety 6 Licensing Municipal Services Building Appeal Board Panel 15th 6 JFK Blvd. U. S. Nuclear Regulatory Commission Philadelphia, PA 19107 Washington, D.C. 20555 Benjamin H. Vogler, Esquire Robert J. Sugarman, Esquire Counsel for NRC Staff Sugarman 4 IIellegers 4 Office of the Executive Legal Director 16th Floor, City Placo U. S. Nuclear Regulatory Commission 101 North Broad Street Washington, D.C. 20555 Philadelphia, PA 19107 Angus R. Love, Esquire Troy B. Conner, Jr. , Esquire E ntgomery County Legal Aid Conner 4 Wetterhahn, P.C.

107 E. Main Street 1747 Pennsylvania Avenue, NW Norristown, PA 19401 Washington, D.C. 20006 t

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{ Docket 6 Service Section Timothy R. S. Campbell, Director  ;

":: U. S. Nuclear Regulatory Commission Department of Emergency Services

Washington, D.C. 20555 - (3 copies) 14 East Biddle Street

( West Chester, PA 19380

l Mr. Robert L. Anthony 103 Vernon Lane, Box 186 Director

] Moylan, PA 19065 Pennsylvania Emergency Management Agency J Basement, Transportation 6 Safety Building David Wersan, Esquire Harrisburg, PA 17120 l Assistant Con.cumer Advocate

!! Office of Consumer Advocate Jay M. Gutierrez, Esquire '

1425 Strawberry Square U. S. Nuclear Regulatory Commission j Harrisburg, PA 17120 Region 1

631 Park Avenue

i Atomic Safety 6 Licensing Board Panel King of Prussia, PA 19406

~; U. S. Nuclear Regulatory Commission Washington, D.C. 20555 Ms. Maureen Mulligan al Limerick Ecology Action Mr. Frank R. Romano P.O. Box 761 1 61 Forest Avenue 762 Queen Street Ambler, PA 19002 Pottstown, PA 19464 i Barry M. Hartman, Esquire Charles W. Elliott, Esquire Office of General Counsel Counsel for Limerick Ecology Action

l; 325 N. 10th Street P.O. Box 11775

! Harrisburg, Pennsylvania 17108 Easton, PA 18042

l Mr. Thomas Gerusky, Director E. M. Kelly

l Bureau of Radiation Protection Senior Resident Inspector e Department of Environmental Resources U. S. Nuclear Regulatory Commission

! Fulton Bank Building, 5th Floor P.O. Box 47 Third 4 Locust Streets Sanatoga, PA 19464 , ,

Harrisburg, PA 17120 t

Spence W. Perry, Esquire

': General Counsel i FEMA, Room 840 500 C Street, SW 3

Washington, D.C. 20472 1 e ,

p ?g a ?n&q Eugghe f. Bradley /

l[- Att,orney for l D Philadelphia Electric Company 2301 Market Street Philadelphia, PA 19101 i

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