ML20126C236

Discusses Review of 751231 Submittal from Util Encl GE Rept NEDC-21120, Monticello Feedwater Nozzle Cladding Crack Repair Rept

ML20126C236
Person / Time
Site:	Monticello
Issue date:	04/15/1976
From:	Eisenhut D Office of Nuclear Reactor Regulation
To:	Goller K Office of Nuclear Reactor Regulation
References
NUDOCS 9212220429
Download: ML20126C236 (2)

Text

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APR l 15 94 })

i Karl R. Goller, Assistant Director r~ [ - ).l 2 for Operating Reactors ,

Division of Operating Reactors {

REVIEW 0F DEC. 31,1975 $UBMITTAL FROM NORTHERN STATES POWER CO.

ENCLOSING THE GENERAL ELECTRIC CO. SPECIAL REPORT. NEDC-21120 "MONTICELLO FEEDWATER N0ZZLE CLADDING CRACK REPAIR REPORT" (TARORB-2-208 s

Plant Name: Monticello Nuclear Generating Plant Suppliers: General Electric Co., Bechtel Licensing Stage: Operating Plant (License No. DPR-22)

! Docket Number: 50-263 '

I Responsible Branch and Project Manager: ORB-2, R. P. Snaider-I Requested Completion Date: February 22,1976 Operating Reactor Branch and Review Engineering Branch: EB, P. Randall, W. Hazelton Description of Task: Review the subject submittal Review Status: Complete In response to your technical assistance request, Section A of the r l Engineering Branch has reviewed the Supplemental Evaluation Report on Feedwater Nozzle Cladding Cracks at Monticello. We believe that the NSP submittal provides acceptable justification for continuing operation until the next refuelling outage, which has been scheduled for September 1,1977. The action taken to detect and remove the -

cracks at Monticello was similar to that taken pmviously at five other plants. Based on this experience, we believe that any un- -

detected cracks that musin.are not severe enough to grow to critical size during the proposed period of operation.

Evidence from the Millstone experience'and from the continuing generic study indicates that the cracking may recur even though the interference fit on the new sparger sleeves should reduce thenal cycling for a time.

Therefore we mcommend that the feedwater nozzles should be reinspected-for cladding cracks at the next refuelling outage, using procedures that are at least as m11able as those just reported. Consideration should also be given to further changes in sparger sleeve design or-to operating procedures that would mitigate the thennal' cycling, should-

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i further cracking be found. The generic study being made by General i Electric Co. should provide a basis for recommendations along these lines in time for use at Monticello, if they are needed.

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! D. G. Eisenhut. Assistant Director for Operational Technology l

Division of Operating Reactors I

cc: V. Stello I D. L. Ziemann

! L. C. Simo R. P. Snaider j W. S. Hazelton "

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