ML20056B857

Informs of Progress in Complying W/Nrc Bulletin 76-04, Cracks in Cold Worked Piping at Bwrs

ML20056B857
Person / Time
Site:	Monticello
Issue date:	12/20/1976
From:	Wachter L NORTHERN STATES POWER CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
IEB-76-04, IEB-76-4, NUDOCS 9102130469
Download: ML20056B857 (2)

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NORTHERN STATES POWER COMPANY n

M IN N E A PO LI S. M I N N E S OTA 5 540' December 20, 1976 1  !

l Mr. James G Keppler t Director - Region III  !

Office of Inspection and Enforcewat j i

i United States Nuclear Regulatory Commission 199 Rqosevelt Road  !

Glen Ellyn, Illinois 60137

Dear Mr. Keppler:

f MONTICEI,1.0 EUCLEAR GENERATIEG PLAIG l

4 Dochet No. 50-263 License No. DPR-22 i i

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'inis le t ter is to it form you of our progress in complying with IE Bulletin  !

l No. 76-04 " Cracks in Cold Worked Piping at IMR's"'for our Monticello Nuclear Generating Plant and of our current findings. As our previous {

letters of August 2 and June 2,1976 indicated, we have had to, in most  !

cases, request this specific documentation for solution annealing from  !

the pipe suppliers and fabricators and their responses have been very slow. .

We have recently been informed by two of the main pipe fabricators, that i the9 had located soma of the missing documentation chich should help complete our verification program. Our documentation package will verify j

I that all of the austenitic stainless steel bent pipe, pipe elbows, ruost of the straight length piping within the survey have been solution and

• i snnealed. 11cuever, we have recently discovered that the cue'enitic stainless stcc1 pipe 3 cngths (10.6 feet of straight pipe) for both core {

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sprcy lines were purchased by the pipe fabricator in the cold drawn enndition. Uc have no proof nor rearon to believe that they were not installed in this condition, Although we do not believe that we have the same situ ation as was report ed in 1.E. Eulletin Ko. 76-05, our intent is to comply.with the Bulletin and f i

volumetrically examine by ultrasonics e.hese pipe lengths. at our next l{

scheduled refueling outage (fall of 1977). Our plans are to include these 'i inspections within the inservice inspections scheduled for this outage; utilizing the same personnel,. equipment, and similiar' procedures that l would be used for the volumetric inspection.of pipe welds and their heat aff2cted zones, :l i ;

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'7102130469 761220 g{g <>~ $ 1976 CF ADDCK 05000263 CF

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f Additional confidence in the pressure integrity of these pipe lengths is provided by the results of weld inspections that were performed to comply with IE Bulletin No. 75-01, "Through Wall Cracks in Core Spray Piping at Dresden 2" inwhich approximately 40% of the pipe volume inquestien had been inspected at Icast twice with no adverse findings. This high volume percent of hase metal inspected by weld inspections was a result of short ,

pipe lengths involved (pipe Icngths ranged from 6" to 46" with an average 12ngth of 16") and the amount of adjacent base metal included in the weld inspection area, cae pipe radius (4") from the welds.

As soon as we receive these final documents from the pipe fabricators, shich should complete our documentation package, we will notify you of this and make it available to your inspectors for review at either our plant site or our Corporate Office.

Yours very truly, 1

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L J d hter Vice President Power l'roduction & System Operation LIW/kd cc: Mr. Victor Stello Mr. G Charnoff Minnesota Pollution Control Agency l Attention: Mr. J U Ferman ,

NRC Of Tice of Inspection anel Enforcement Washington, D.C.

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