IR 05000213/1993011

Insp Rept 50-213/93-11 on 930621-25.No Violations Noted. Major Areas Inspected:Insp Was Conducted on Licensee Actions Re Feedwater Nozzle Cracking & Associated Insp & Repair Activities

ML20046A228
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	07/16/1993
From:	Gray E, Mcbrearty R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20046A223	List: IR 05000213/1993011
References
50-213-93-11, NUDOCS 9307270120
Download: ML20046A228 (7)

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U.S. NUCLEAR REGULATORY COMMISSION

REGION I

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REPORT NO.

93-11

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DOCKET NO.

50-213 LICENSE NO.

DPR-61

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LICENSEE:

Connecticut Yankee Atomic Power Company

.t FACILITY NAME:

Haddam Neck INSPECTION AT:

Haddam, Connecticut

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E INSPECTION CONDUCTED:

June 21-25,1993

GE 71993 INSPECTOR:

R.- A. McBrearty, Reactor Engi pat [

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Materials Section, EB, DRS t

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APPROVED BY:

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E. H. Gray, Chieff Date Materials Section, EB, DRS l

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9307270120 930721 PDR ADOCK 05000213 G

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i Areas Insoccted: An announced inspection was conducted of the licensee's actions regarding feedwater nozzle cracking and associated inspection and repair activities.. These activities j

included radiographic and ultrasonic examination, weld repair, and selection of an expanded examination sample as required by ASME Section XI because of the cracks found in three of four feedwater nozzles.

i Results. The licensee's inservice inspection program was effective in that cracks in three of four feedwater nozzles were detected. Repair activities included the required nondestructive

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examinations to confirm defect removal and weld repair acceptability. Radiography of the repairs confirmed the component's acceptability to return to service. Additionally, the we liccusee's desire to use inspection sample expansion niles of the 1992 Section XI in lieu of the applicable 1983 Section XI was discussed with the appropriate NRC/NRR staff, and the i

staff's suggestions were acted upon.

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DETAILS 1.0 FEEDWATER NOZZLE CRACKING 1.1 Background On June 25,1979, the NRC issued Bulletin 79-13, " Cracking in Feedwater System Piping,"

to inform PWR licensees of feedwater nozzle cracking at various facilities, and required certain actions by licensees. As a result of actions taken in response to 79-13, and based on the results of radiographic examinations and the investigation of the subject problem since the initial Bulletin was issued, revision 2 of Bulletin 79-13 was issued on October 17,1979, by the NRC.

The Haddam Neck facility performed radiographic examination of the four steam generator (SG) feedwater elbow to nozzle welds in 1979 in response to the original Bulletin, and again in 1980 in response to Revision 2. The results of those~ examinations were evaluated by an evaluation team comprised of Westinghouse, Connecticut Yankee, and Northeast Utilities Service Company (NUSCO) to address the Peabody Corporation findings, which said that

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two of the nozzles were cracked in 1979, and to determine whether the observed generic cracking exists in the Haddam Neck SG feedwater nozzle welds and/or adjacent base metal.

The evaluation team concluded that no cracking or other unacceptable Code discontinuities were found in all four SG feedwater elbow to nozzle welds and adjacent base material at Haddam Neck. The conclusion was stated in the licensee's "Haddam Neck Plant Summary Report - NRC I&E Bulletin No. 79-13 Inspection Results," issuect on August 1,1980, to the NRC.

Since the issuance of Bulletin 79-13, Revision 2, the NRC has issued Information Notice (IN) No. 91-28, " Cracking in Feedwater System Piping," IN No. 91-38, " Thermal Stratification in Feedwater System Piping," and IN No. 93-20, " Thermal Fatigue Cracking of

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Feedwater Piping to Steam Generators." Notice 91-28 was issued on April 15,1991, to inform licensees of the issuance of a document which closed out NRC Bulletin 79-13.

Information Notice 91-38, issued on June 13, 1991, alerted licensees to feedwater system piping that could be subjected to thermal stratification and cause unacceptable pipe movement, and IN No. 93-20 was issued on March 24,1993, to inform licensees of cracks j

found in the feedwater piping to SGs at the Sequoyah Nuclear Power Plant, Units 1 and 2, and the Diablo Canyon Nuclear Power Plant, Unit 1. No specific action by licensees is required by the Information Notices, but recipients are expected to review the information for applicability to their facilities and consider actions, as appropriate, to avoid similar problems.

1.2 Current inspections The licensee's ASME Section XI inservice inspection (ISI) plan for the 1993 refueling outage listed the SG #4 elbow to nozzle weld for radiographic examination The examination results showed two circumferential cracks, 25-1/2" long and 1-3/4" long,1 1/2" from the weld centerline in the nozzle base metal. Radiographs from 1979 and 1980, the last time the

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nozzles were examined, were reviewed and the licensee's Level III film interpreter concluded that the cracks appeared on the earlier RT films and that the 25-1/2" long crack now appeared to be 4-1/2" longer than it was in 1980. The licensee expanded its inspection sample to include all four SG feedwater elbow to nozzle welds. The radiographic examination of the three additional welds detected circumferential cracks in the nozzle base

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metal of SG #2 and SG #3. The SG #1 elbow to nozzle weld and nozzle base metal was determined to be free of defects. All of the detected cracks were located in the bottom 180*

section of the nozzles. To gain access to the cracked locations, the three elbows were removed. A visual and liquid penetrant examination of the SG #4 nozzle was performed and confirmed the presence of cracks. Ultrasonic sizing of the cracks in the three nozzles was performed using the tip diffraction method developed at the EPRI NDE Center. The crack

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depths, as determined by the ultrasonic sizing technique were as follows:

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SG Nozzle Qack Depth

1. 2 1/4" + 1/16"

1. 3 3/16" + 1/16"

1. 4 1/8" + 1/16"

The cracks were removed by grinding and their removal was verified by radiography of the i

excavation. After the repairs by welding were completed, a final radiograph was made of l

each repair to determine its acceptability. All of the repairs were judged to be acceptable.

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The radiographs, including those made in 1979 and 1980, were reviewed by the inspector and he agreed with the licensee's conclusions.

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The f' mal radiograph of the SG #2 feedwater nozzle repair showed rejectable porosity i

between station markers 0-1. The condition is documented on nonconformance report (NCR)

'l No.93-226 issued on June 23,1993.. The engineering disposition noted that the porosity was present on original RT films, and is not a result of the crack repair process performed

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during the present outage. Because it is visible on the original radiographs, it is known to be not service-related. The feedwater system was deemed to be acceptable at the time of construction under the construction Code (ASME Section VIII,1962 Edition). Additionally,

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the engineering disposition notes that the porosity is small and has no impact on structural i

integrity of the nozzle. At the exit meeting, the inspector stated that, for the reasons discussed above, he agreed with the "use as is" NUSCO engineering disposition.

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The 1983 Edition of the ASME Boiler and Pressure Vessel Code Section XI including

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Summer 1983 Addenda is applicable at Haddam Neck for inservice inspection activities during the current third ten-year inspection interval. In accordance with that edition of

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Section XI, the licensee is required to further increase its inspection sample to include all remaining feedwater system welds, approximately 140 welds, because of the defects found in

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the feedwater nozzles. The licensee has concluded that rules for inspection sample expansion that have been incorporated into toe 1992 edition of Section XI are more appropriate for use in the case of the feedwater system because of the type of defects which were present and the

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location of those defects on the system. The matter was discussed with the Office of Nuclear -

Reactor Regulation (NRR) of the NRC curing a telephone conversation on June 24,1993.

The licensee was advised by NRR that the NRC has not reviewed the 1992 edition of -

Section XI and it has not yet been approved for use by licensees. Because of that, the licensee was advised the NRC needs assurance that the proposed examination sample established by the licensee using 1992 Section XI rules will provide an acceptable level of confidence that the feedwater piping is acceptable for continued ~ operation before approval for using the later Code can be granted. At the time of the exit meeting for this inspection, the licensee was developmg an inspection sample using the 1992 Section XI rules. The licensee had discussed the feedwater nozzle cracking problem with the Westinghouse Electric Corporation and the additional sample will be established using information provided by Westinghouse regarding the system configuration and operating characteristics at Haddam Neck, and engineering judgment of the licensee's Engineering Department to provide the assurance requested by the NRC during the aforementioned telephone conversation.

1.3 Weld Repair Subseque' to discovering cracks in three of the four steam generator nozzles, the licensee

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elected to remove the cracks by grinding, and to perform weld repair of the resulting excavation. Welding Procedure Specification WPS 021 was designated as the applicable procedure to perform the repairs. Prior to using the procedure, the gas-tungsten-arc welding (GTAW) process was deleted by the licensee's welding engineer for use with P1, Group 2 materials in the as-welded condition. The GTAW process was inadvertently used during the

repair of the feedwater nozzles which resulted in the issuance of NCR No.93-206 on

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June 20,1993, to document the procedmu violation. The welding engineer investigated the details regarding the violation and the various procedure qualification records (PQR)

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applicable to WPS 021, and determined that a "use as is" disposition was appropriate. At the exit meeting, the inspector stated that he agreed with the disposition for which supporting documentation is included on NCR No.93-206.

I Conclusions The inservice inspection program at Haddam Neck is effective as evidenced by the detection J

of cracking in three of four feedwater nozzles. The Connecticut Yankee Atomic Power Company has kept the NRC informed of related activities and has discussed with the N'RC its desire to establish the Code required expanded inspection sample from rules incorporated into the 1992 Section XI. The licensee considers the 1992 Section XI rules to be more l

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appropriate to the circumstances than are the rules of the applicable 1983 Edition of Section XI. Additionally, the licensee has acted on NRC suggestions regarding the use of the 1992 Section XI rules for inspection sample expansion.

2.0, EXIT MEETING The inspector met with licensee representatives, denoted in Attachment 1, at the exit meeting on June 25,1993. The scope and findings were summarized and the licensee representatives acknowledged the inspector's comments. The licensee did not take issue with the findings of the inspector.

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ATTACHMENT 1

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Persons Contacted Connecticut Yankee Atomic Power Company

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• E. L. Annino, Senior Analyst

• M. Bain, Engineering Manager - Connecticut Yankee

• D. Ray, Director - Connecticut Yankee

• J. Stetz, Vice President - Haddam Neck l

• R. A. West, NUSCO Connecticut Yankee Inservice Inspection Coordinator

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• Denotes those present at the exit meeting.

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