ML20128D892

From kanterella
Jump to navigation Jump to search
Summary of 751031 Meeting W/Util to Discuss Monticello Reactor Vessel Feedwater Nozzle Cladding Cracks.List of Attendees Encl
ML20128D892
Person / Time
Site: Monticello Xcel Energy icon.png
Issue date: 11/28/1975
From: Buckley B
Office of Nuclear Reactor Regulation
To: Ziemann D
Office of Nuclear Reactor Regulation
References
NUDOCS 9212070415
Download: ML20128D892 (4)


Text

_ _ __ _ _ ,., m y r._, ,,, .

a NOV 2 6 bl5 I

Dennis L. Ziemann, Chief, Operating Rosetors tranch #2, RL '

DOCKET NO. 50-263 LICENSEEt NORTHERN STATES POWER COMPANY FACIL1'nft MONTICELLO NUCLEAR GENERATING P! ANT StMtARY OF MEETING llELD ON OCTOBER 31, 1975 TO DISCUSS 1HE MONTICELID REACTOR YESSEL PEE!*ATER N0ZZLB CIADDING CRACKS A meetinF was held with Northern States Power Company (NSP) and its consultants NtrTECH and General Plectric Company (GB).to discuss the cracks observed in the Monticello reactor vessel feedwater notste corners.

During the September 1975 outage, a crack tas fmmd in one of the four feedwater spargers while performing an inservice inspection praram.

Northern States Power elected to replace all four spargers with spargers of a more advanced design. In the process of removing the spargers, cladding defects were observed in all four of the reactor vessel feed- '

' water nossle corners. Dye penetrant testing of. the nogales indicated the presence of approximately *180 cracks. Further inspection and repakt indicated that the cracks were " tight" with some cracks penetratingmas '

such as 1/4 inch into the nossle base material. Northern Stetes Power Company and its consultants attributed the cracks to therust fatigue of the cladding caused by feedwater temperaturososcillations at the reactor l vessle nossle penetrations. Feedwater temperature oscillation measure-nonts at another boiling water reactor. sinitar in design to that of Monticello, ~ indicated temperature oscillations of 100'F per second at the reactor vessel nostle corners. ' As##d/ TJudTh$egated that the installation of He new sprgers, which will have an interference fit with the "as left" nozzle will reduce the by-pass feedwater flow,-

which appears to be the unjor cause leading to cladding defects.

Repair of the defects consisi.J si grinding out the cracks. In some instances it was necessary to grind into the base metal to remove defects that had penetrated as auch as 1/4 inch into the base metal.

Dye penetrant testing was repeated after repair to ensure that all defects had been removed. General Electric stated that a stress analysis ef the as left nostle indicated that it complied with the requirements of Section III of the ASME code.

.,n 'ApCC

) ll 9212070415 751128 PDR ADOCK 05000263 P PDR *

- ~ _ __ . . _ _ . _ . _ _ . _ _ _ _ - . _ . _ . _ . _ . _ _ . . - _ . _ . .._

r. .

. 2-The meeting concluded with the understanding among participants that there was no innsediate safety concern. Northern States Power Company was requested to subreit a technical report on this matter by late December 1975. g 4Cadh B. C. Duck 1py Operating Reacto I Branch #2 Division of Reactor Licensing

Enclosure:

1.ist of Attendees cc:

No7thern States l'over Company ATE 4: lir. L. O. Mayer, Director Nuclear Support Services 414 Nicollet Mall Minneapolis, Minnesota 55401 Anthony Z/ Roisaan, Esquire Berlin, Roisman and Kessler 1712 N Street, N. W:

Washington, D. C. 20036 RL:0RB #2 RL:0RA y omet > .. . . g.g . . . ... . . .... . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . , , . . . . . . . . . . . . . , . . . . . . . . ,

BBuckley:ro DLZi-mann su=we . .;.3.g.7g-

..).).g.g.. . . . . . . . . . . . . . . . . . . . . . . . . . . . .

out. . . . . . . . . . .. . . . . . . . . . . .

see .es-is-steam 6.H7s Form ALC-Ste (Rev. 9 53) AECM 0240

LIST OF ATTENDEES GENERAL ELECTRIC I R. Kobsa

11. T. Watawbe, R. Schaffstall NRC STAFF i
11. L. Brammer B. C. Buckley P. Y. Chen
  • C.' Y. Cheng J. Collins R. M. Gamble W. llazleton M. R. Ilum S. Paw 11cki V. Potapovs K. Seyfrit e e*

f f

's.

e S

DISTRIBtTTION FOR MEETING StlHKARY Docket ,

L. Shao NRC PDR D. Ro:s Loca.1 PDR T. Novak ORB #2 Reading T. Ippolito NRR Reading B. Grimes B. Rusche M. Spangler E. G. Case R..Ballard D. Eisenhut . J. Kastner R. S. Boyd , W. Gammill R. Heineman-K. R. Go11er T. J. Carter R. F. Fraley, ACRS (16)

R. C. DeYoung S. Varga V. A. Moore Project Manager -

D. J. Skovholt EP Project Manager R. P. Denise Attorney, OEl,D D. R. Muller 016E (3)

D. Vassallo R. 01ggs-

'W. Butler NRC Participants

0. Parr .

T. B. Abernathy, ITTIE J. Stolz '

K. Kniel +

-A. Schwencer P. Collins R. Vollmer R. Houston R. Purple G. Lear R. Reid

  • R. Clark ,

T. Speis '

G. Knighton G. Dicker '

B. Youngblood W. Regan R. Tedesco R. Maccary '

V..Stello H. Denton. .

J. Collins G. Lainas V. Benaroya J. Knight

  • S. Pawlicki k

._m_;