ML20127N751

Forwards IE Bulletion 74-10B,amending Description of Circumstances Discussed in IE Bulletin 74-10A

ML20127N751
Person / Time
Site:	Monticello
Issue date:	01/27/1975
From:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
To:	Wachter L NORTHERN STATES POWER CO.
References
IEB-74-10, NUDOCS 9212010405
Download: ML20127N751 (1)

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I UNITED STATES

,' ,, ,. NUCLEAR REGULATORY COMMISSION DIRECTOR ATE OF REGULATORY OPERATIONS REGION lli 799 ROOSEVELT RO AD OLEN ELLYN. ILLINOIS 60137 AN 2 7 2975 Northern States Power Company Docket No. 50-263 ATTN: Mr. Leo Wachter, Vice President Powr Production and System I Operation 414 Nicollet Hall Minneapolis, Minnesota 55401 Gentlemen:

Enclosed is IE Bulletin No.74-10B, which amends the description of the circumstances discussed in RO Bulletin No.74-10A and requests additional actions by you.

l Should you have questions regarding this Bulletin or the actions requested of you, please contact this office.

l l Sincerely, James G. Keppler Regional Director Enclosures IE Bulletin No.74-10B Approved by CAD, B-180255 (R0072), e1=arance expires 7/31/77.

Approval was given under a blanket clearance specifically for i identified generic problems.

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January 27, 1975 IE Bulletin No.74-10B I

FAILURES IN 4-INCH BYPASS PIPING AT DRESDEN-2

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REFERENCE:

R0 BULLETINS NO. 74-10, DATED SEPTEMBER 19, 1974 AND NO.74-10A, DATED DECEMBER 17, 1974)

DESCRIPTION OF CIRCUMSTANCES (AMENDED):

Cracks similar to those described in R0 Bulletins 74-10 and 74-10A have been revealed during reexamination of the 4-inch bypass piping at five boiling water reactor facilities (including Dresden-2) since mid-December 1974. All the facilities are of jet-pump design. In each instance where cracks have been revealed, the same welds had been examined pre-viously (during September-November 1974) and no cracks were revealed at that time.

A special study group, comprised of-key technical members of the Nuclear Regulatory Commission staf f, is currently studying the causes of the cracks which have been experienced. Consultants from other government agencies are also participating in the study.

In the interim, pending recommendations of the Commission's special study group, additional actions are necessary by licensees to insure continued close surveillance of reactor coolant leakage.

ACTIONS REQUESTED OF LICENSEES (AMENDED):

For all boiling water reactor f acilities of jet-pump design with operating license:

1. Upon completion of those actions described in RO Bulletin 74-10A,

implement the following reactor coolant leakage detection program

If (within the sensitivity specified in paragraph C.S. of Regulatory Guide 1.45) any reactor coolant leakage detection system indicates, within a period of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> or less, either an increase in unidentified leakage to twice the determined normal rate of unidentified leakage or an increase in the rate of unidentified leakage by two (2.0) gpm or more:

a. Initiate plant shutdown immediately, and Determine the source of increased leakage prior to resuming b.

operation.

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January 27, 1975 TE Bulletin No.74-10B

c. If there is evidence of leakage from the 4-inch bypass piping, reexanine (by ultrasonic or other suitable volumetric inspection technique), all accessible welds in the bypass piping lines.

(In no case, however, shall the rate of leakage exceed that specified in the technical specifications without those actions required by the technical specifications being taken.)

2. Notify this of fice, in writing within 10 days of your receipt of this Bulletin, of your intent to impicment the actions described in 1.,

above.

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