ML20084E293

Ao:On 740101,abnormal Degradation Discovered in Steam Generator a Tubes Designed to Contain Radioactive Matls Resulting from Fission Process.Cause Undetermined.Tube Sheets Cleaned Using High Pressure Water Lance Method

ML20084E293
Person / Time
Site:	Ginna
Issue date:	02/19/1974
From:	Amish K ROCHESTER GAS & ELECTRIC CORP.
To:	Oleary J US ATOMIC ENERGY COMMISSION (AEC)
Shared Package
ML20084E289	List: ML20084E285 ML20084E291 ML20084E293 ML20084E297
References
AO-50-244-74-02, AO-50-244-74-2, NUDOCS 8304150011
Download: ML20084E293 (4)

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ROCHESTER GAS AND ELECTRIC CORPORATION e 89 EAST AVENUE, ROCHESTER, N.Y.14649 vistposo=g AEITH W A 481S H nam o= v.c +=ssier NT ansa coot na 546 2700 ELECT #:C A ND Strate February 19, 1974 g

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l Mr. John F. O' Leary, Director Directorage of Licensing s .

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U. S. Atomic Energy Commission .

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.l Abnormal Occurrence 74-2: Abnormal degradation of *1b#

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Subject:

one of the several boundaries designed to contain the radioactive materials resulting from the fission process.

R. E. Ginna Nuclear Power Plant, Unit No.1 Docket No. 50-244

Dear Mr. O' Leary:

l l In accordance with Technical Specifications, Article 6.6.2a, the attached report of Abnormal Occurrence 74-2 is hereby submitted.

Since the analyses and investigative action specified in paragraph I

8 of the report will take several weeks to complete, this letter constitutes an interim report to fulfill technical specification

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l requirements. A follow-up report will be forwarded prior to startup l

of the plant.

Very truly yours,

/

j) ./ l Keith W. Amish Attachment xc: Mr. James P. O'Reilly f(y' e'3f(,

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8304150011 740321 i

gDRADDCK 05000 44 COPY SENT REGION -

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1. Re2crt Number: 50-244/74-2 2a. Report Date: February 19, 1974 2b. Occurrence Date: Prior to January 1,1974

, 3. Facility: R. E. Ginna Nuclear Power Plant, Unit No.1

4. Identification of Occurrence: .

This occurrence is defined by Technical Specification Article 1.9e:

" Abnormal degradation of one of the several boundaries designed to l

contain the radioactive materials resulting from the fission process."

5. Conditions Prior to Occurrence:

Eddy current examination of both steam generators was scheduled I

for the refueling outage originally planned for March-April,1974. Due to a low pressure turbine problem, the plant was shut down on January 1, 1974. After determining the scope of repairs to the turbine, the decision was made to refuel and to proceed with all work that had been programmed for the refueling period.

6. Description of Occurrence:

Eddy current examination of the steam generator tubes has detected what appears to be wastage on the secondary side of the tubes. This condition is localized approximately 1 to 3 inches above the tube sheet.

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The most significant indications are noted in the tubes of the hot leg of the "A" steam generator approximately in the center area of the tube sheet and generally above the primary water hot leg inlet nozzle. Lesser amounts of wastage have been detected in corresponding locations in the "B" steam generator hot leg and the "A" cold leg tubes and none in the "B" cold leg tubes.

7. Designation of Apparent Cause of Occurrence:

The cause of the apparent wastage of the tubes has not been determined at this time.

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Abnormal Occur ca 50-244/74-2 cont'd.

8. Analysis of Occurrence:

Investigation is being conducted in the following areas:

a. All tubes in the "A" steam generator hot leg are being examined by eday current. Other tube areas are being tested on a statis-tical basis. ,

b. Samples of tubes which indicate wastage will be removed for examination and analysis.

c. Analysis is being performed to determine the thickness of tubing required to assure the continued integrity of the primary to secondary boundary during accident conditions.

d. Secondary system chemistry specifications and procedures are being re-evaluated as a result of this problem and the steam generator tube problems experienced by other nuclear plants.

9. Corrective Action:

a. The tube sheets will be cleaned using a high pressure water lance method.

b. Tube plugging will be accomplished if necessary as determined from the above analyses,

c. Secondary system chemistry specifications and procedures will be modified as necessary to prevent or minimize further tube wastage.

10. Failure Data:

There has been no indication of any primary to secondary leakage at Ginna and no evidence of wastage in previous tube examinations.

Eddy current examination of approximately 1000 tubes in the "A" steam generator during the Spring 1972 shutdown indicated a possible anomoly i

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Abnormal OccurfWrico 50-244/74-2 cont'd.

in only one tube. This isolated condition was considered to have been caused by a manufacturing defect.

The Ginna steam generator units are Westinghouse, Series 44, using Inconel 600 tubes, size 0.875 O.D. with 0.050 inch walls.

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