ML20084E259

AO 50-237/75-12:on 750209,through-wall Crack Discovered on Line 2-1403-10-A (Core Spray Injection Line to Reactor Vessel).Cause Unknown.Corrective Action Will Be Based on Cause

ML20084E259
Person / Time
Site:	Dresden
Issue date:	02/21/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20083L276	List: ML20083L281 ML20084E252 ML20084E259 ML20084E263 ML20084E266
References
105-75, 2213, AO-50-237-75-12, NUDOCS 8304140493
Download: ML20084E259 (3)

Text

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CNcago. Imnois 60600 BBS Ltr. #105-75 Dresden fluclear Power Station R.R. #1 Morris, IL 60450 February 21, 1975

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James G. Keppler, Regional Director ft?:li Directorate of Regulatory Operations - Region 111 -i l_,

U.S. Iluclear Regulatory Commission ;M s.

799 Roosevelt Road '\',

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Glen Ellyn, IL 60137 ',;._ .

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.h' S'JBJ ECT : REPORT OF ABNORfiAL OCCURREllCE PER SECTION 6.6. A 0F THE TECl1NICAL SPECIFICATICLS CORE SPRAY INJECTIO'l LillE THROUGli-UALL CRACK

References:

1) Regulatory Guide 1.16 Rev. 1 Appendix A

2) Letter from B. B. Stephenson to J. G. Keppler dtd 6 Feb 75

3) Notification of Region t il of flRC Regulatory Operations Telephenc: P. Johnson, 1300 hrs, 10 Fcb 75 Telegram: J. Kcppler, 1515 hrs, 10 Feb 75 Report flumber: 50-237/1975-12 Report Date: February 21, 1975 Occurrence Date: February 9, 1975 Facility: Dresden fluclear Power Station,itorris, IL IDCflTIFICATICN OF GCCURRENCE On February 9,1975 at approximately 1400 hrs, a through-wall crack was discovered on line 2-1403-10"-A, which is the "A" Core Spray InJcction Line to the reactor vessel. This represents an abnormal degradation of a boundary designed to contain radioactive materials.

C0f1DIT10NS PRIOR TO OCCURREllCE Prior to the occurrence, the reactor was locked in the refuel mode with the replacement of the 4 inch recirculation Jischarge valve bypass line in progress.

DESCRIPTION OF OCCsRREllCE At 1400 hrs on February 9, 1975, Unit 2 was shutdown for its third refueling outage. With the inservice inspection program underway, one crack was discovered on "A" Core Spray injection Line approximately in the 12 o' clock position in the heat affected zone of the butt weld. Subsequent ultrasonic examinations revealed that this crack was approximately 11 inches in ler.gth on the ID, from about 10 o' clock to 12 o' clock.

8304140493 750407 4

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-JamesG.Keppl() (} February 21, 1975 i

DESIGNATION OF APPARENT CAUSE OF OCCURRENCE At this time, the apparent cause of the failure is unknown. Once the sections of piping cre remcved, an investigation will be performed to determine the mode of failure: this report will be submitted as a followup letter.

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ANALYSIS OF GCCURRENCE At the time of discovery, the small leaks found did not compromise the l safety of the public or plant personnel. The reactor has been shutdown since November 1974 and the leaks were detected during performance of the Inservice inspection program.

During the operating period since the last inspection in early 1972 through November 1974, the station has operated in accordance with the Technical Specifications which requires availability of emergency core cooling systems.

At the time of discovery, the LPCI system was available to provide core cooling in the event of , (JCA had the core spray system become non-functional.

CORRECTIVE ACTION The remaining welds in A & B Core Spray Systems out to the second isolation valve have been ultrasonically exanined. As a result of the examinations, additional welds have been noted to have indications but have been resolved to be of a geometrical nature.

Once the crackcd piping, in question, has been removed from the system, couar=1 n f + s ... i a , +sy peree:: :p::: 3: ::r!::!. !ng!:::!:ne .:!1! bc l visually examined to substantiate the evaluation.

l The corrective action to be taken to prevent recurrence will be contingent upon the results of the visual examination of these subject welds. As a minimum, the section of pipe containing the crack will be replaced.

FAILURE DATA This most recent failure occurred in pipino of 304SS,10 inch diamater and schedulo 80.

The previous failures of austentic pipe of similiar nature were discovered on September 13, 14 and December 13, 1974 involving the four inch recirc bypass !!nes, 2-0203B-4"-A and 2-0203A-4"-A. The four inch piping material was of 304 stainless steel with a thickness of 0 337 inches.

Five through wall cracks were discovered on January 27, 1975 on A and B Core Spray injection Lines, 2-1403-10"A and 140h-10"B respectively. The cracks were discovered in an area between the reactor vessel nozzle to safe end weld and the core spray pipe section adjacent to the dutchman weld. The sections of piping (dutchman) involved in these failures are on 316 stainless steel with a thickness of approximately 0.60 inches. This is the first occurrence of this nature where a transition piece connected to the safe end has failed.

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• . Jam 5s G. Keppi ']

/'T February 21, 1975 J U This letter is being submitted after the allotted time due to site personnel's total involvement in the inspection effort generated by IE Bulletin 75-01.

This extended submittal date was discussed with P. Johnson,f1RC Region 111, on February 14, 1975 Sincerely, ,

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B. B. 8tephenson Superintendent Dresden fluclear Power Station BbS:RJC:slb cc: File /AEC

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