ML20040C619

Forwards Guidelines Re Channel Box Deflection Program. Program Will Prevent Interference W/Control Motion & Is Comparable to Resolution of Item for Zimmer Docket

ML20040C619
Person / Time
Site:	Fermi
Issue date:	01/15/1982
From:	Tauber H DETROIT EDISON CO.
To:	Kintner L Office of Nuclear Reactor Regulation
References
EF2-56-037, EF2-56-37, NUDOCS 8201290089
Download: ML20040C619 (2)

Text

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i jin.nsaz 5, uYQ [Q $ f I p January 15, 1982 EF2 - 56,037 A

La Mr. L. L. Kintner U. S. Nuclear Regulatory Commission Office of Nuclear Reactor Regulation Division of Licensing Washington, D. C. 20555 1

Reference:

Enrico Fermi Atomic Power Plant, Unit 2 NRC Docket No. 50-341

Subject:

Status of SER Confirmatory Items -

Channel Box Deflection

~

Section 4.2 3 of the Fermi 2 SER asks for a commitment to perform settling friction tests on control rods as a means of monitoring channel box deflection which might interfere with control rod insertion.

We have reviewed the present knowledge concerning channel box deflection caused by long-term creep deformation and believe the program described in the attachment will prevent interference with control rod motion.

This program is comparable to that determined to be accep-table for resolution of this item on the Zimmer docket.

i If you have any questions, please' contact L. E.

Schuerman, (313) 649-7562.

Sincerely,

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Mr. B. Little

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Attachment to:

EF2-56,037 CHANUEL BOX DEFLECTION PROGRAM The following general guidelines are exercised to mitigate the consequences of channel bowing.

a. Records are kept of channel location and exposure for each operating cycle.

b. Channels should not reside in the outer row of the core for more than two operating cycles.

c. At the beginning of each fuel cycle, the combined outer row residence time for any two channels in any control rod cell should not exceed four peripheral cycles.

Prior to beginning a new operating cycle, control rod drive friction tests shall be performed for those control rod cells exceeding the above general guide-lines or containing fuel channels with exposures greater than 30,000 MWD /STU (associated fuel bundle exposures).

In lieu of friction testing, fuel channel deflection measurements may be used to justify use of fuel chan-nels exceeding 30,000 MWD /STU exposure for a maximum of four additional operating cycles.

In the future, analytical channel lifetime prediction methods, benchmarked and backed up by periodic deflec-tion measurements of a sample of the highest duty fuel channels, may be used to ensure clearance between control rod blades and fuel channels without addi-tional testing.