ML19305E096

Submits Info in Support of Continued Operation W/Sleeved Guide Tubes in Cycle 4.Anticipates That Negligible Guide Tube Sleeve Wear Will Be Measured

ML19305E096
Person / Time
Site:	Millstone
Issue date:	04/15/1980
From:	Counsil W NORTHEAST NUCLEAR ENERGY CO.
To:	Reid R Office of Nuclear Reactor Regulation
References
TAC-11348, TAC-11561, TAC-12505, TAC-42846, NUDOCS 8004220364
Download: ML19305E096 (6)

Text

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April 15, 1980 Docket No. 50-336 Director of Nuclear Reactor Regulation Attn:

Mr. R. Reid, Chief Operating Reactors Branch #4 U. S. Nuclear Regulatory Commission Washirgton, D. C.

20555

References:

(1)

R. Reid letter to W. G. Counsil dated May 12, 1979 (2)

W. G. Counsil letter to R. Beid dated March 29, 1979 (3)

W. G. Counsil letter to R. Reid dated January 24, 1979 (h)

W. G. Counsil letter to R. Reid dated April 17, 1979 Gentlemen:

Millstone Nuclear Power Station, Unit No. 2 Resolution of Cycle 3 Startup Commitments In Reference (1), the NRC Staff issued License Amendment No. 52 and the supporting Safety Evaluation to Facility Operating License No. DPR-65, for Millstone Unit No. 2.

Included in Reference (1) was a commitment by Northeast Nuclear Energy Company (NNECO) to provide an evaluation program to determine the amount of guide tube wear experienced after two (2) cycles of operation with sleeved fuel assemblies and one (1) cycle with the reduced flow demonstration test assemblies.

Accordingly, NNECO provides the following information in support of continued operation with sleeved guide tubes in Cycle 4.

At the end of Cycle 2, in-reactor, poolside, and hot cell examinations were conducted to assess the performance of the sleeved and unsleeved fuel assem-blies.

The evaluation confirmed satisfactory performance of the sleeves to date and gave assurance that the sleeves will perform as designed during multiple cycle operation. Although some light burnishing was noted, the program revealed no significant degradation of the wear surfaces of either the sleeve or CEA.

The hot cell examinations indicated that the chrome on the sleeves had not been worn through, and no visual evidence of crevice corrosion was found on any of the guide tube surfaces examined. During Cycle 3 operation, all assemblies located under CEAs were sleeved except for four demonstration assemblies utilizing reduced flow guide tubes. Sixteen assemblies sleeved and used under CEAs during Cycle 2 were located under CEAs for a second time during Cycle 3.

Also, as was the case during Cycle 2, none of the Batch C assemblies with vorn guide tubes from Cycle 1 were used under CEAs during Cycle 3.

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The planned inspection program following Cycle 3 has been designed to address the pertinent aspects of sleeved guide tube operation, to confirm satisfactory performance during Cycle 3, and to demonstrate the acceptability of continued use of sleeved guide tubes during Cycle 4.

This program utilizes a combination of eddy-current tests and visual examinations to confirm that the use of sleeves or assemblies with reduced flow guide tubes y

are acceptable methods of mitigating the consequences of guide tube wear.

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(1) Fuel Assembly Guide Tube Inspection Eddy-current tests will be performed on 6 to 12 modified fuel assemblies that were located under CEAs during Cycle 3.

Five of these assemblies are scheduled to be returned to locations under CEAs during Cycle 4.

The assemblies to be examined include those residing under CEAs for a second cycle, fuel assemblies with reduced flow holes, and those residing under CEAs for one cycle. Visual examinations of several of these assemblies will also be performed.

NNECO does not intend to examine any sleeved assemblies not located under CEAs during Cycle 3 since the examinations of assemblies located in non-CEA locations after Cycle 1 revealed no indication of wear.

To facilitate Staff review of the above examination program, Figures 1 and 2, representing the Cycle 3 core map and CEA location guide, are provided.

(2) Control Element Assembly Inspection Eddy-current tests will be performed on two CEAs. The CEAs to be inspected are located over two of the fuel assemblies scheduled for the eddy-current tests described above.

I Based on the guide tube sleeve inspection program conducted following Cycle 2 operation and subsequent programs conducted by Combustion Engineering, Incorporated, NNECO anticipates that negligible guide tube sleeve wear will be measured. NNECO does not anticipate any wear of the guide tubes themselves. These considerations are reflected in the determination of the number of bundles planned for inspection.

Should NNECO identify any non-conformances or significant deviations during the inspections, a more extensive examination program involving additional assemblies will be undertaken.

4 i

The above inspection program has been designed to address all aspects of sleeved and reduced flow guide tube _ operation.

The successful completion of this program will confirm satisfactory performance of operation with modified guide tubes during Cycle 3 and demonstrate the acceptability of continued use of the guide tubes during Cycle h.

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P NNECO tr'usts you find this information responsive to the Reference (1) commitment.

Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY l

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W. d. Counsil Vice President Attachment

DOCKET NO. 50-336 ATTACliMENT MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2 RESOLUTION OF CYCLE 3 STARTUP COMMITMEliTS APRIL,1980

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