ML20147J127

Summary of Telcon on 970403 W/Nmpc to Discuss Licensees Observations from Insp of Weld 32-WD-050 Between Recirculation Sys Suction Piping & Isolation Valve 32-376 at Plant

ML20147J127
Person / Time
Site:	Nine Mile Point
Issue date:	04/07/1997
From:	Hood D NRC (Affiliation Not Assigned)
To:	NRC (Affiliation Not Assigned)
References
NUDOCS 9704110002
Download: ML20147J127 (11)

Text

April 7, 1997 LICENSEE: Niagara Mohawk Power Corporation FACILITY: Nine Mile Point Nuclear Station Unit No. 1

iUBJECT:

SUMMARY

OF TELEPHONE CONVERSAIION OF APRIL 3, 1997, REGARDING RECIRCULATION PIPING WELD On April 3,1997, the NRC staff participated in a telephone conference call with Niagara Mohawk Powor Corporation (NMPC and licencee) to discuss the licensee's observations from inspections of Weld 32-WD-050 between the recirculation system suction piping and isolation valve 32-376 at Nine Mile Point Nuclear Station, Unit 1.

The list of participants is given in Enclosure

1., which was telecopied to the NRC for the telephone conference, summarizes the licensee's discussion. The licensee's evaluation of the flaw is in progress.

The flaw was observed by ultrasonic testing (UT) to be about 1/4 inch in depth relative to the piping inner diameter and located about 3 inches from the long (axial) seam of the piping in a root repair area of the weld that was made in 1982/1983 when the recirculation piping was replaced.

The licensee plans to recheck (1) the Induction Heating Stress Improvement (IHSI) record for the weld from the 1986 inservice inspection to confirm that the stress relief technique was properly applied and (2) the post IHSI automated raw UT data for the presence of a flaw.

The licensee believes that the indication is either a reflector caused by an unsuccessful repair at installation or cracking initiated due to stresses in the localized repair area.

Based on Generic Letter 88-01, the licensee is considering maintaining the~ weld classification as Intergranular Stress Corrosion Cracking Category A, even though NMPC intends to increase the frequency of inspection at least during the next two refueling outages.

The NRC staff strongly recommended that the licensee consider reclassification as Category F, which requires reinspection each refueling outage.

Sincerely,

/S/

Darl S. Hood, Senior Project Manager Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket No. 50-220 q

Enclosures:

1.

List of Participants 2.

Telecopied Text and Sketches cc w/encls:

See next page PI DOCUMENT NAME: G:\\NMPl\\RECIRC.TEL To receive a copy of this document, indicate in the box:

"C" - Copy without attachment / enclosure "E" - Copy with attachment / enclosure "N" - No copy 0FFICE PM:P01 1 lE LA POI ML l

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. LICENSEE: Niagara Mohawk Power Corporation FACILITY: Nine Mile Point Nuclear Station Unit No. 1

SUBJECT:

SUPMARY OF TELEPHONE CONVERSATION OF APRIL 3, 1997, REGARDING j

RECIRCULATION PIPING WELD On April 3,1997, the NRC staff participated in a telephone conference call with Niagara Mohawk. Power Corporation (NHPC and licensee) to discuss the licensee's observations from inspections of Weld 32-WD-050 between-the recirculation system suction piping and isolation valve 32-376 at Nine Mile Point Nuclear Station, Unit 1.

The list of participants is given in Enclosure

1., which was telecopied to the NRC for the telephone conference, summarizes the licensee's discussion. The licensee's evaluation of the flaw j

!is-in progress.

The flaw was observed by ultrasonic testing (UT) to be about 1/4 inch in depth relative to the piping inner diawter and located about 3 inches from the long y

(axial) seam of the piping in a root repair area of the weld that was made in 1982/1983 when the recirculation piping was replaced. The licensee plans to recheck (1) the Induction Heating Stress Improvement (IHSI) record for the weld from the 1986 inservice inspection to confirm that the stress relief technique was properly applied and (2) the post IHSI automated raw UT data for the presence of a flaw.

The licensee believes that the indication is either a reflector caused by an unsuccessful repair at installation or cracking initiated due to stresses in the. localized repair area. Based on Generic Letter 88-01, the licensee is considering maintaining the weld classification as Intergranular Stress Corrosion Cracking Category A, even though NMPC intends to increase the frequency of inspection at least during the next two refueling outages.

The NRC staff strongly recommended that the licensee consider reclassification as Category F, which requires reinspection each refueling outage.

Sincerely, Daa/

Darl S. Hood, Senior Project Manager Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket No. 50-220

Enclosures:

1.

List of Participants 2.

Telecopied Text and Sketches cc w/encis: See next page t '

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i Niagara-Mohawk Power Corporation Nine Mile Point Nuclear. Station Unit No. I m

cc:

5 lMr. B.' Ralph Sylvia Res'ident Inspector Executive Vice President U.S. Nuclear Regulatory Commission Generation Business Group P.O. Box 126 and Chief Nuclear 0fficer Lycoming, NY 13093 Niagara Mohawk Power Corporation Nuclear Learning Center Charles Donaldson, Esquire j

450 Lake Road Assistant Attorney General Oswego, NY 13126 New York Department of Law i

120 Broadway Mr Richard _B. Abbott New York, NY 10271 Vice. President and General Manager -

Nuclear Mr. Paul D. Eddy.

Niagara Mohawk Power Corporation State of New York j

Nine Mile Point Nuclear Station Department of Public Service P.O. Box 63.

Power Division, System Operations Lycoming, NY 13093 3 Empire State Plaza Albany, NY 12223 3

1-Mr. Martin J. McCormick, Jr.

Vice President Mr. F. Willlam Valentino, President i

Nuclear-Safety Assessment New York State Energy, Research, and Support

.and Development Authority

-Niagara Mohawk Power Corporation Corporate Plaza West 1,

Nine Mile Point Nuclear Station 286 Washington Avenue Extension P.O. Box 63 Albany, NY 12203-6399

-Lycoming, NY 13093 a

Mark J. Wetterhahn, Esquire Mr. Kim A. Dahlberg Winston & Strawn General Manager - Projects 1400 L Street, NW Niagara Mohawk Power Corporation Washington, DC 20005-3502 Nine Mile Point Nuclear Station i

P.O. Box 63 Supervisor Lycoming, NY 13093 Town of Scriba Route 8, Box 382 Mr. Norman L.1 ademacher Oswego, NY 13126 R

3 Plant Manager, Unit 1 Nine Mile Point Nuclear Station Gary D. Wilson, Esquire P.O. Box 63 Niagara Mohawk Power Corporation Lycoming, NY 13093 300 Erie Boulevard West Syracuse, NY 13202 Ms. Denise J. Wolniak Manager Licensing Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station P.O. Box 63 Lycoming, NY' 13093 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 475 Allendale Road i.

King of. Prussia, PA 19406 l

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l LIST OF PARTICIPANTS-April 3. 1997 1925 H8G.

T. Zallnick W. Koo T. Lee W. Lazarus (RI)

J. Wadsworth D. Hood J. Swenszkowski J. Cilento et al.

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~'pf-hvT~ qae TEM WELD INDICATION j

RESPONSES TO NRC QUESTIONS 1

1.

Previous preservice (PI, UT, RT) and inservice findings:

ED 1983 PSI - (11) rounded idiWs, a111ess than 1/16' in diameter. 1997 ISI -

(1) 1/4" rounded indication recorded.

IID 1983 PSI - UT identified root geometry and counterbore geometry 360* at various amplitudes. 1986 post IHSI - automated UT identified "no relevant indications found."

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1983 root pass info - lack of fusion noted between 17"-19" location markers -

npaired, re-shot and accepted. Final ASMB Section III RT accepted on 1 l

83. It should be noted that the present UT indication is at the same location as the root repair area discussed above. 1997 supplemental RT - performed supplemental RT on this indication this outage. Indication was not seen with conventional or enhanced digitization of the RT film. Installation and supplemental RT film was digitized, however, the areas of interest did not positively reveal this indication.

2.

Indication of a crack? Does it show IGSCC characteristics?

Indication is a non-geometric planar reflector. There is not enough information e

to positively characterize this indication at this time.

ne indication appears to be cicarly contained within the root repair area with a

l 45' shear, 60' R.L., and WSY-70. The apparent tip signals observed with IGSCC sizing techniques were low amplitude.

His indication does exhibit some IGSCC characteristics such as location and skewing.

3.

Any fracture p=achanten status or results?

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NMPC has contracted MPR Associates to perform an analytical evaluation of the Indication per the 1986 Edition of ASME Code Section XI. He evaluation is currently underway. Preliminary results show that the flaw size calculated for the end of the vpcoming operating cycle meets the Table IWB-3641 allowable flaw size criteria. De 1

- APR-2-97 WED 11:05 1.10ENSING FAX N0. 3491400 P.02

'e evaluation ma=um Haw grow.. t. stress corrosion cracking as well as by fadgue.

Dese results are preliminary and have not been reviewed or accepted by NMPC.

i 4.

ConArm the weld was a pipe Geld replacement weld, the piping material

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specincation and the pipe war thickw.

Weld 32-WD-050 was replaced during the outage between 3/19/82 and 6/4/83. ne i

root weld was installed on 12/21/82 and final welding completed on 1/11/83. Root radiography report was rejected because of an area ofincomplete fusion, which was

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repaired. No further repairs were made to the weld.

Malarials:

Valve 32-376 is A351 Gr CF8M 28" Piping is SA 358 C1.1 Gr 316, Modified 0.02% Max Carbon j

Wald Metal is ER-308L 0.035" and IN-308L 1/8" x 5/32"

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Pipe Wall Thickness: Specified Min. Wall 1.050"; UT Measurement 1.1".

5.

Udlation levels?

1,000 mr on contact (system drained); 500 mr at 1 foot.

6.

Any unusual history that might be tied to a cause?

See response to question 4. NMPC has verified that area ofincomplete fusion identified and repaired in 1983 (installation) is in the same location as indication found in RPO14. UT performed in 1986 following 1HSIidentified "no relevant indications found."

7.

Overall conclusion on indication.

Indication is either a reflector caused by an unsuccessful repair at installation or l

cracidng initiated due to stresses in the localized repair area.

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ADntT10NALINFORMATION Imatlan-

~ See simplified sketch. Upstmam of weld 32-WD40 is the loop 12 suedon blocking valve 32-l 376 and downstream is a 11'-5.5" length of 28' pipe.

J Fmpanded Rumminatlan*

An expanded sample of 9 additional examinations on the reciren1*% system were chosen.

All additional examinadons have been completed and found to be acceptable. Also, wproximately 60% of the welds in the acirculation system have been UT examined since pip;ng replacement with no rq@ctable indicadons found.

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