ML20236T980

Supplemental Application for Amends to Licenses DPR-42 & DPR-60,providing Suppl Info in Support of 980129 Amend Request Re Cooling Water Sys Emergency Intake Design Bases

ML20236T980
Person / Time
Site:	Prairie Island
Issue date:	07/24/1998
From:	Sorensen J NORTHERN STATES POWER CO.
To:	NRC
Shared Package
ML20236T539	List: ML20236T537 ML20236T980
References
NUDOCS 9807290218
Download: ML20236T980 (4)

Text

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UNITED STATES NUCLEAR REGULATORY COMMISSION NORTHERN STATES POWER COMPANY j

PRAIRIE ISLAND NUCLEAR GENERATING PLANT DOCKET Nos. 50-282 50-306 REQUEST FOR AMENDMENT TO OPERATING LICENSES DPR-42 & DPR-60 LICENSE AMENDMENT REQUEST DATED January 29,1997 Amendment of Cooling Water System Emergency intake Design Bases Northern States Power Company, a Minnesota corporation, by this letter dated July 24,1998, with its attachments provides supplementalinformation in support of the subject license amendment request dated January 29,1997. Attachment 1 provides responses to NRC questions presented in the Request for Additional Information date July 23,1998.

This letter and its attachments contain no restricted or other defense information.

NORTHERN STATES POWER COMPANY By Jg. Sorenseff Plant Manager Prairi Island N clear Generating Plant

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before me a notary On this day of

,4 public in a'nd'for said County, p,6 f.on' ally f)pared, Joeil P. Sore f

e Manager, Prairie Island NuclesfGenerat,Q Plant, and being first duly sworn acknowledged that he is authorized to execute this document on behalf of Northern States Power Company, that he knows the contents thereof, and that to the best of his knowledge, information, and belief the statements made in it are true and that it is not,nterposedfor dela.

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ATTACHMENT 1 SUPPLEMENT 14 Request for Additional Information dated July 23,1998 l

1.

What is Prairie Island's commitment to Regulatory Guide 1.29 (Seismic Design Classification) with respect to applying Appendix B criteria to Class 1 items?

Will the canal be covered in the future by the Appendix B program ?

Response

(a)

NSP adheres in general to the guidelines of Regulatory Guide 1.29 for Prairie Island, although specific commitments to this Regulatory Guide have not been made. Structures, systems, and components (SSC) that provide a safety-related function are designed as Design Class I.

Supporting structures whose failure during a Class I, Design Basis Earthquake event could adversely impact the functions of a safety-related SSC are designated as Design Class I* and are analyzed to assure that safety-related functions are not compromised.

The present requirements of the intake canal to facilitate additional flow of cooling water to the safety-related cooling water pumps place the canal in the Design Class 1* status as defined in the USAR.

(b)

It is NSP's intent to reclassify the canal as a Design Class I* structure in accordance with the definition for Design Class I* provided in the USAR.

This classification requires that the structure be originally designed or subsequently analyzed to Class I, Design Basis Earthquake load (dynamic) only, and that these items are treated as Class III in all other respects (i.e.,

QA Type 3). By this definition the canal will not be covered in the future by an Appendix B Program.

2.

.How was testing and analysis controlled that demonstrated the necessary

' functionality of the canal? Were analyses controlled under Appendix B design control provisions? Was testing and laboratory aspects similarly controlled?

' Response:

(a)

NSP retained the services of a geotechnical consultant, STS Consultants l

Ltd. of Northbrook, IL and their sub-consultant GEI Consultants, Inc. in Winchester, MA, to perform the in situ and laboratory testing of the as-found condition of the canal and to utilize the results of the tests to analyze 1

Response to RAI dated July 23,1998 Page 2 of 4 the intake canal slopes for the Design Basis Earthquake (dynamic) loads.

Testing was performed in compliance to applicable ASTM standards.-

Calibration of instrumentation were traceable to NIST standards. Analysis i

was performed using manual and computerized calculations and were internally reviewed within the STS organization and were also subject to independent review by two leading industry experts. Other responsibilities of the vendor included documentation control, verification of computer programs and notification to NSP oferrors identified.

(b)

NSP's Purchase Order to STS was commercial grade quality. NSP Supplier QA conducted two surveys based on identified critical characteristics. All outstanding issues with respect to the survey findings were resolved. Even though Class I* design classification does not require safety related quality standards be applied to these items, NSP felt it was prudent to exercise control on the testing and analysis through the commercial grade process. Appendix B Program was not strictly invoked for analysis or testing.

3.

Will the canal be included in some type of monitoring or surveillance program to ensure continued functionality and conformance with Class I* analysis?

Response

The intake canal is part of the External Circulating Water system. A system engineer with primary responsibility for this system is assigned. This ensures

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continued awareness to maintaining the canal to the Class 1* status. Any modification to the canal would require research of the USAR commitments, reanalysis of the canal slopes to the Design Basis Earthquake (dynamic) load, and the system engineer's approval.

in addition, routine surveys are performed to monitor the depth of water in both the approach and the intake canals. There is no specific monitoring needed to j

conform with Class I* analysis. The banks of the intake canal were formed from naturally occurring soil formations. Monitoring of structures under the Maintenance Rule is addressed in Question 5.

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Attachment I r

Response to RAI dated July 23,1998

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. 4.

Will future design control provisions for the intake canal be part of an Appendix l

l B program? Please explain.

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Response

The intake crnal structure will not be specifically included in the Appendix B t

program. However, any proposed design change to the intake canal structure will be processed using the site design change process. The design change process is an Appendix B program. The intake canal will be treated in the same manner from a desip control provisions standpoint as other Class I* items listed in the USAR. Any future modifications to the canal would require that the Class I*

status is not compromised.

Additionally, any routine work that would need to be done would be performed in accordance with the site Work Control Administrative Procedures. The work control process is an Appendix B program.

5.

Is the Intake Canal part of the " Maintenance Rule Program," 10 CFR 50.657 Please explain.

Response

Yes. The intake Canal, as part of the Circulation Water system, is in scope of the Maintenance Rule. Monitoring requirements are stated in the Structures Monitoring Program under the Dams, Embankments section. The Structures Monitoring Responsible Individual performs this monitoring. In addition, a responsible system engineer periodically monitors the external circulating water i

system. Typically, this monitoring occurs daily during a normal, day shift, work week. However, it is not intended that every part of every system is monitored i

daily. Also, operator rounds require an operator to pass in the near vicinity to the Intake Canal at least once per shift. All of these monitoring functions provide good assurance that significant changes in the Intake Canal will be identified and evaluated.

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6.

10 CFR 50.2 defines safety-related structures, systems and components to mean those structures, systems and components that are relied upon to remain functional during and following design basis events to assure: (1) The integrity of the reactor coolant pressure boundary; (2) The capability to shut down the l

reactor and maintain it in a safe shutdown condition; or (3) The capability to prevent or mitigate the consequences of accidents which could result in potential offsite exposures comparable to the applicable guideline exposures set forth in t

Attachment I-t

Response to RAI dated July 23,1998 Page 4 of 4

[10CFR] 50.34(a)(1) or 100.11... as applicable. Does the Intake Canal meet any

_ part of this definition (especially part 2)? In other words, is the Intake Canal relied upon to remain fimetional during and following design basis events to assure the capability to shut down the reactor and maintain it in a safe shutdown condition? Please explain.

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Response

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- The original intent of the canal was to facilitate the flow of non-safeguards water L

to the turbine condenser external circulating water system. As such it was designed and constructed as a non-safety-related structure (Design Class III, QA Type 3). The safety related cooling water required to assure the capability to shut down the reactor and maintain it in a safe shutdown condition is provided by the safety-related emergency intake line. When the capacity of the emergency intake

- line was determined to be less than design, the volume of water in the Intake' Canal is needed for an interim time frame. Therefore, the as-found canal slopes l

were analyzed to assure that the canal would be capable of providing a volume of water for an interim time frame during and after a Design Basis Earthquake. This analysis determined that the intake canal structure would not fail in a manner that would prevent the cooling water system from performing, its design function. To.

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capture this additional condition imposed on the intake Canal structure, the intake

canal is re-classified as Design Class I* as defined in the USAR. This is consistent with the Prairie Island licensing basis. Therefore we conclude that the intake canal does not perform a function needed to ensure safe shutdown, as defined in part 2 of the 10 CFR 50.2 definition of safety related structures.

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