ML19256F018

Responds to IE Bulletin 79-14.Seismic Analysis for as-built Piping Sys Revealed Branch Connections for Mod Designed & Installed by Different A/E.Reanalysis,Redesign & Mod Conducted by S&W.Addl Info Will Be Provided in 30-day LER

ML19256F018
Person / Time
Site:	Prairie Island
Issue date:	10/26/1979
From:	Wachter L NORTHERN STATES POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-79-14, NUDOCS 7911160572
Download: ML19256F018 (4)

Text

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• fl NSD NORTHERN STATES POWER COMPANY M s N N E A po u S. MIN N E SOTA 55401 October 26, 1979 s

Mr. James G. Keppler Director - Region III Office of Inspection and Enforcement United States Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137

Dear Mr. Keppler:

PRAIRIE ISLAND NUCLEAR GENERATING PLANT Dockets No. 50-282 and No. 50-306 In response to Item 3 of IE Bulletin 79-14, the following is offered:

As described in the response to item 2 of IE Bulletin 79-14, the inspection is being conducted in two parts. These parts are first, physical, and second, analytical.

A. Physical Inspection The physical inspection included the actual verification of as-built drawings by direct measurement and comparison. Inspection elements involved in the physical inspection were piping geometry, support /

restraint design, support / restraint location, support / restraint function / clearances, valve and valve operator locations, and pipe attachment details. Teledyne Engineering Services (TES) Procedure P-3697-1 and TES personnel were utilized for the actual inspection.

B. Analvtical Inspection The analytical inspection portion involves the verification of the input information into the seismic analysis. The basic approach being used is to review every walked down isometric drawing and hanger drawing and compare them with the data used for the seismic analysis. Included in this review by Fluor Power Services (FPS) are the valve weights, any offset center of gravity concerns, and materials of construction from the quality assurance records. This approach to the analytical inspection is being used to insure that even drawings which don't differ from the as-built configuration are reviewed.

1342 327 7911160 572 '? OCT 2 31979 O

NORTHERN STATES POWER COMPANY Mr. James G. Keppler October 26, 1979 Page 2 C. Extent of Inspection to Date All accessible piping in the plant which falls under the scope of '

this Bulletin has been inspected physically. Also, the piping systems in the Unit #1 Containment Building have been inspected.

The only area left to be inspected is in the Unit #2 Containment Building. The physical location of both systems in each set of redundant systems and non-redundant systems included in the scope have been completed.

The analytical inspections for these piping systems have not been completed, but are in progress at the present time. That portion of the piping systems contained in Unit #1 Containment hsve been completed, and work is progressing on the Auxiliary and Turbine Building piping systems.

D. Results of the Inspection Results of the physical inspection were reported in the previous response to IE Bulletin 79-14 (60 day). Only the results of the analytical portion of the inspection completed to date will be reported in this response.

In addition to the discrepancies found and reported as a part of the 60-day response, two additional discrepancies have been identified as a result of the analytical inspection program.

1. FPS (A/E) found that a portion of the Cooling Water System piping geometry shown on isometric A-6705, Rev. 12, was not consistent with the piping geometry which was input to the analysis. Further investigation showed that the deviation was documented and approved (N-713 (DEX)) during plant construction. The piping stress analyst felt the analysis should be rerun to insure no unacceptable stress levels exist.

The analysis is being rerun currently with results expected about November 1, 1979.

2. Review of the field walkdown drawings on the Cooling Water System revealed branch connections for a modification which was designed and installed by a different A/E, Since the modification involved piping (Class II) being attached to Class I piping, a walkdown of the Class II piping was undertaken.

Deviations in pipe run geometry and hanger details were found which resulted in a reanalysis, redesign, and modification by the A/E (Stone and Webster). Determination was made that the deviations from design were reportable under the Plant's Technical Specifications.

Further information concerning these problems will be assembled during the course of the event investigation and will be reported via a 30-day License Event Report.

NORTHERN STATES POWER COMPANY Mr. James G. Keppler October 26, 1979 Page 3 E. Schedule for Completion of the Inspection Analytical Inspection Phase s

1. Unit #1 Reactor Building: complete

2. Unit #1 and #2 Auxiliary and Turbine Buildings (Analytical only, physical complete)

a. Verification of piping geometry, support and restraint type, support and restraint location, and valve locations:

November 25, 1979

b. Pipe Stress Engineer's Review: November 25, 1979

c. Stress Analyst Review: Verification of valve weights, orientation of valve controllers, centers of gravity, branch connection types, piping sizes, and materials:

November 25, 1979

d. Discrepancy Analysis: December 15, 1979

3. Unit #2 containment Physical Inspection: To be done during refueling outage (January,1980) unless outage of sufficient duration occurs prior to January, 1980.

Analytical Inspection: Will follow physical inspection - expect to be completed by April 15, 1980. F. Conclusions The analytical inspection program is continuing at the present time and will not be completed in the time frame indicated in IE Bulletin 79-14. It should be noted that the physical inspection included both large bore (> 2 1/2") and small bore (< 2 1/2") piping as was the Bulletin requirement at the outset. Since this inspection scope was undertaken in the beginning, it was decided to follow this approach through to completion with the foreseeable benefit of providing an additional review and update of the piping "as-built" drawings. This approach, however, compounds the effort of analytical inspection since more documents have to be reviewed; hence, the delay in completion. Since the inspections, physical and analytical, completed to date have revealed only one significant non-conformance, the time extension required to complete the inspection is justified.

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NORTHERN STATES POWER COMPANY , Mr. James G. Keppler October 26, 1979 Page 4 Further reports will be made concerning the findings at the completion of the analytical inspection for the Auxiliary and , Turbine Buildings as well as a findings report at the completion of the Unit #2 Containment Inspection in early 1980. Yours very truly, L. . 'achter Vice President Power Production and System Operation cc: Mr. G. Charnoff Director - Office of Inspection and Enforcement Washington, D.C. Director - Division of Operating Reactors Washington, D.C. 1342 330}}