ML20006D662

Responds to Generic Ltr 89-13, Svc Water Sys Problems Affecting Safety-Related Equipment. Currently Established Preventive Maint & Tech Spec Surveillance Activities on HXs Remaining in Svc Will Continue

ML20006D662
Person / Time
Site:	Fort Saint Vrain
Issue date:	02/06/1990
From:	Crawford A PUBLIC SERVICE CO. OF COLORADO
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-89-13, P-90041, NUDOCS 9002140194
Download: ML20006D662 (4)

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February 6,.1990 A. Clegg Crawford -  ;

Fort St. Vrain vice President C Unit No. 1 Nuclear Operahns P-90041-U.- S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D. C. 20555 Docket No. 50-267

SUBJECT:

Generic letter 89-13 Service Water  !

System Problems Affecting Safety-Related Equipment

REFERENCES:

1) Generic Letter 89-13 dated July 18, 1989 (G-89260)

2) PSC . Letter, Crawferd to Weiss, dated August 16, 1989 (P-89287)

Gentlemen:-

Public Service Company of Colorado (PSC) herein provides the response requested by Generic Letter.89-13 " Service Water System Problems Affecting Safety-Related Equipment", for Fort St. Vrain. Generic :l l

Letter 89-13 contains five recommended actions to be taken--by addressees. -The five action items are all keyed to be completed - H before plant startup following the first refueling outage beginning-9 .

months or more after the date of the Generic Letter.

On August 18, 1989 Fort St. Vrain (FSV) was shutdown and the decision was subsequently made to end all nuclear operations. Therefore, it is no longer intended for the plant to be refueled'or ever again operated at any power level.- Currently, FSV is in a defueling

-operatienal mode in which removal of core decay heat and maintaining the core inlet temperatures below 165 degrees Fahrenhait (LCO 4.7.1) I are the two principle core cooling concerns. Maintaining core inlet. '

temperatures below 165' degrees Fahrenheit is necessary to allow the continuation of-defueling activities.

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February 6, 1990-P-90041 .

7 1 s Core decay heat generation is relatively small and the corresponding potential core heat-up with a loss of forced circulation heat removal would be very slow. As' stated within the FSV Defueling Safety Analysis Report (SAR), (P.eference 2), it is currently possible during a loss .of . forced circulation 'of primary coolant to maintain core temperatures within those experienced during normal operation through the use.of only one Prestressed Concrete Reactor Vessel (PCRV) liner cooling system loop. As of January 31,1990,(166 days after reactor shutdown) decay heat generation was approximately 0.17 MW at which point the . core could sustain a total loss of cooling for approximately- 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> without exceeding a calculated bulk core temperature of 760 degrees Fehrenheit. If the active core remains below 760 degrees. Fahrenheit, which corresponds to the design maximum core inlet temperature, then there can be no damage to fuel or PCRV internal, components,' evenintheabsenceofforcedcirculation(LC0 ,

4.0.4). As fuel is removed from the core and as time progresses, this Technical Specification allowable loss of core cooling period ,

will increase.. ,

r Due- to the current status -of FSV in which the heat removal requirements are significantly reduced, it has been possible to safely remove systems, portions of systems, and equipment from operational service.- Currently. it is possible-to remove decay heat using- the PCRV liner cooling system, Loop 2 (with Loop 1 as a potential backup). The forced circulation cooling function to continue defueling is provided by the condensate system and the Loop 2 helium circulators (with one circulator in service and one in .

standby). This new plant configuration .in support of defueling i activities provides the necessary equipment redundancy and additional operating flexibility /alterr,etives as well as excessive heat removal capacity.

The primary service water system being relied upon for decay heat removal is the Service Water System (System 42). This is the only open-cycle service water system presently needed for operation at l

FSV.. This system is maintained in a relatively clean state by l

utilizing domestic water as the primary makeup source and through the existing water chemistry program. Through this chemistry control program the service water is treated daily with chlorine, the pH is maintained, and corrosion inhibitors are added.

The Aquatic Biota Section of the FSV Radiological Environmental Monitoring Program (Section 8.2 of the FSV Technical Specifications) monitors the FSV environment for the existence of, among other l things, Asiatic clams. Through this program there has been no indication of the existence of Asiatic clams in the vicinity of FSV.

L Also, there has not been any indication of Asiatic clams found during any maintenance on any service water system components. ,

In support of the defueling operational mode of FSV the following closed-cycle service water systems will remain in service: System 46 (PCRV Liner Cooling, Loop 2) Eystem 21 (Helium Circulators and Auxiliaries, Loop 2), System 31 (Condensate System, Loop 2; supply to Loop 2 Helium Circulator Pelton Wheel s , Loop 2 Steam Generator Economizer-Evaporator-Superheat section, and Decay Heat Removal Exchanger), System 84 (Auxiliary Boiler). These systems contain high purity treated water in which significant foMing or flow blockage a

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the . water chemistry control program for. these systems. The acceptable ' water chemistry parameters for the closed-cycle systems are in the process of being adjusted to facilitate the layup of U

certain plant components not required for-the defueling process.

This adjustment involves the elevation of the hydrazine- content and pH which will reduce the propensity for system corrosion.

FSV will continue the currently established Preventive Maintenance and Technical Specification Surveillance activities on those heat exchangers remaining in service. This program will assist in identifying whether significant degradation in the capacity of-specific heat exchangers is occurring or should be anticipated.

For the aforementioned reasons, the safety function performance capability of' the service water systems at FSV is adequately confirmed and maintained for the purpose of defueling. Therefore, it has been determined that Public Service Company of Colorado need not L modify its current programs or implement additional programs for the  ;

specific purpose of complying with the recommendations from Generic  !

Letter 89-13.

l- If there are any questions regarding the information provided in this letter, please call Mr. M. H. Holmes at (303) 480-6960.

Very truly yours, fd S.

A. Clegg Crawfo d Vice President Nuclear Operations ACC/RLT/km-cc: Regional Administrator, Region IV ATTN: Mr. T. F. Westerman, . Chief j Projects Section B  !

Mr. Robert Farrell l Senior Resident Inspector Fort St. Vrain j

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UNITED STATES OF AMERICA' ,

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NUCLEAR REGULATORY COMMISSION

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In the Matter .

Public Service Company of Colorado Docket No. 50-267 r-Fort St. Vrain Unit No. I-C AFFIDAVIT F

A.. Clegg Crawford being first duly sworn, deposes and says: That he is Vice President, Nuclear. 0perations, of Public - Service Company of -Colorado, the Licensee herein, that he has read the information -

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t. presented in the: attached letter 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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XI~tlegg C'rawford' Vice President ,

Nuclear Operations STATE OF COLORADO COUNTY OF DENVER Subscribe and sworn to before me, a Notary Public on this t 5th day of February , 1990, I

h3ld>JA bruvu, Notary Public 4

My connission expires January 6, , 1993

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