ML19296D754

Supplements Response to IE Bulletin 79-13 Re Feedwater Piping.Examination of Feedwater Piping to Nozzle Welds & Adjacent Pipe & Nozzle Areas Revealed No Evidence of Cracking

ML19296D754
Person / Time
Site:	Prairie Island
Issue date:	02/15/1980
From:	Gilberts D NORTHERN STATES POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-79-13, NUDOCS 8003130115
Download: ML19296D754 (2)

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, NSD NORTHERN STATES POWER COMPANY MIN N E A PO U S M 4 N N E S OTA 88409 Feb ruary 15, 1980 Mr. James G. Keppler Director - Region III Office of Inspection and Enforcement U. S. 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 further response to IE Bulletin No. 79-13, the following is offered:

All examinations required by IE Bulletin No. 79-13, Revision 2, were completed on Prairie Island Unit 2 feedwater piping during the January 1980 refueling outage.

Radiographic examinations of the feedwater piping-to-nozzle welds and of ad-jacent pipe and nozzle areas were performed in accordance with Bulletin Item

1. a. These areas were also ultrasonically examined in accordance with Appen-dix III of ASME Section XI, 1974 edition through the Summer 1976 Addenda. The tdtrasonic examination was performed using a calibration block fabricated to re-semble the pipe-to-nozzle weld geometry, including the counterbore-taper area.

In addition, these areas were visually and magnetic particle examined in accor-dance with ASME Section XI, 1974 edition through the Summer 1975 Addenda. The results of these examinations showed no evidence of cracking. The magnetic particle examinations did, however, reveal several material irregularities on the outside surface of the pipe and nozzle. These indivations were buffed out and re-examined with no further indications.

The Prairie Island design has a common nozzle for both main and auxiliary feed-water systems. The auxiliary feedwater to main feedwater piping connection is located inside containment on the steam generator side of the main feedwater final check valve.

Radiographic examinations required by Bulletin Item 2. a. were also performed on the accessible welds in accordance with Item 1. a. These examinations on feedwater loop B consisted of the piping base metal from the auxiliary feed-water connection to the pipe-to-nozzle weld. The remainder of this line is encapsulated with guard piping. The containment penetration-to-pipe weld, the circumferential butt welds from the last support to the steam generator, and the piping base metal from the auxiliary feedwater connection to the pipe,-to-nozzle weld were all examined by visual, ultrasonic, and magnetic particle methods referenced above. The results of these examinations revealed n'o evidence of cracking or other unacceptable indications. 's 800313101k)h

Pfr. James G. Keppler Page 2 February 15, 1980 All main feedwater piping supports and restraints in containment were examined visually in accordance with ASFE Section XI,1974 edition through Summer 1975 Addenda. All accessible support attachment welds to the main feedwater pipe were also magnetic particle examined. During these examinations, minor dis-crepancies such as a missing nut or nuts not flush with base plate were noted.

One nut required for proper restraint clearance adjustment was repositioned according to original design specifications. This and all similar nuts were then coated with a compound designed to prevent them from movinF, during opera-tion. One rupture restraint required adjustment of clearances; this was p -

formed by welding a thinner shim plate onto the restraint structure. All these conditions were corrected and re-examined.

Yours truly, G

l ' Q &',fl .2 C D. E. Gilberts Vice President Power Production cc: Mr. G. Charnoff NRC Office of Inspection and Enforcement Washington, D. C.

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