ML20076B016

Discusses Addl Info Re Control Element Assembly Guide Tube Insp.Fuel Assemblies Suitable for Continued Use During Cycle 3 Operation

ML20076B016
Person / Time
Site:	Millstone
Issue date:	05/07/1979
From:	Counsil W NORTHEAST UTILITIES
To:	Reid R Office of Nuclear Reactor Regulation
References
TAC-30198, NUDOCS 7905100320
Download: ML20076B016 (2)

Text

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. 4 NORfHI!AST IFFII.ITII!S i,4 ., m n wr m w . m.

P O BOX 270

, HARTFORD. CONNECTICUT 06101 Ns .7EI.b r . u [ .r.

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May 7, 1979 [f 1

Docket No. 50-336 Director of Nuclear Reactor Regulation -

Attn: Mr. R. Reid, Chief Operating Reactors Branch #4 U. S. Nuclear Regulatory Comnission Washington, D. C. 20555 h

Reference:

(1) W. G. Counsil letter to R. Reid, dated April 26, 1979.

Gentlemen:

Millstone Nuclear Power Station, Unit No. 2 Additional Information, CEA Guide Tube Inspections In Reference (1), Northeast Nuclear Energy Company (NNECO) presented the results of the guide tube sleeve pull tests which had been conducted, and concluded that the fuel assemblies were suitable for continued use during Cycle 3 operation.

That conclusion remains unchanged, however, some additional information has been obtained and is presented below.

One sleeve out of a total of 45 tested to date failed to meet the criterion that there should be no axial sleeve movement at cold conditions when subjected to the pull force previously identified. Specifically, a sleeve in a discharge g fuel assembly moved approximately 0.25 inches when the pull force was four pounds less than the specified test criterion.

The test criterion was established as a conservative upper 1 5it for CEA drag force and on the axial force due to flow. However, recent site tests with fuel assemblies containing sleeves and CEA's irradiated for 2 cycles indicated a max-imum CEA drag force of only 20% of the test force (for all 5 fingers) corroborat-ing data previously obtained at Combustion Engineering. This drag force value is considerably lower than the present requirement for a single sleeve. Therefore, the fact that one sleeve moved at a force four pounds less than the criterion is considered to be technically acceptable in view of the conservative limit which was established relative to the actual CEA drag force. Further, the load required ,

for movement in the hot condition would be expected to increase significantly l since differential thermal expansion causes an intimate contact between the j sleeve and guide tube that was not present in the test.

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7905100 3101

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It is also noted that the force was increased an additional 30 pounds beyond the f orce at which the small axial displacement occurred. fio further axial movement was noted.

In suninary, both flNECO and Combustion Engineering have concluded that the fuel assemblies are acceptable for use through Cycle 3.

Very truly yours, NORTilEAST flVCLEAR ENERGY COMPAtlY l}' 'f yf , /  ! ClLYlCA, EG. Counsil Vice President D

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