ML20198C860

Amended Final Deficiency Rept,Item 116 Re Potential Design Defect Which Allowed Freezing of Buried Piping Sys.Initially Reported on 840131.Constant Flow of 0.1 Gpm Through Affected Fire Protection Lines Will Be Maintained

ML20198C860
Person / Time
Site:	Fermi
Issue date:	10/23/1985
From:	Jens W, Jens W DETROIT EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
116, DRFR-8510123, DRFR-851023, VP-85-0204, VP-85-204, NUDOCS 8511120200
Download: ML20198C860 (2)

Text

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n,y n u.c w n e w vommo VP-85-0204 Mr. James G. Keppler Regional Administrator Region III U. S. Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, Illinois 60137

Reference:

(1)

Fermi 2 NRC Docket No. 50-341 URC License No. NPP-43 (2)

Letter, D. A. Uells to J. G. Keppler, February 29, 1984, QA-84-326 (3)

Letter, W. H. Jens to J. G. Keppler, August 23, 1984, EF2-69698 (4)

Letter, W. H. Jens to J. G. Keppler, november 30, 1984, EF2-70220

Subject:

Amendeo Tinal Report of 10CFR50.55(e),

Item.ll6

" Potential. Design Deficiency by Allowing Freezing of Buried Piping Systems" This is-Detroit Edison's final report of' Item 116,

" Potential-Design Deficiency'by Allowing Freezing of Buried Piping Systems."

Item 116 was originally reported as a potential design deficiency on January 31, 1984, an6 subsequently documented in Reference 2.

A final report, Reference 3, was issued which indicated that Edicoa would reroute the fire lines to avoid the embedded pipe area where the freezing occurred.

The next report,' Reference'4, states.

that instead of rerouting, Edison would insulate the outside wall adjacent to the embedded pipe, monitor the temperatures, and continuously flow water through the lines to prevent freezingLuntil the design was verified by the nonitoring program and accepted.

As stated in Reference 4, the outside wallRof the RHR Complex was insulated with six. inches of insulation that extended.from the first floor-level to three feet below grade.

A continuous flow of water was maintained through lthe:line.

Detroit Edison Engineering Research Department developed a finite-difference heat balance model of the wall with the embedded fire-line to predict.the internal wall

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Mr. Jcmss G. Keppler VP-85-0204 October 23, 1985 Page 2 temperatures for the worst case ambient conditions.

Data was collected every three hours during the winter season with thermocouples measuring the air, reservoir water and wall temperatures at various points.

This data was used to substantiate the model and to evaluate the proposed solution.

Results of the Evaluation The mathematical model was used to predict the temperatures atthecenterofthewallcontainingtheembegdedfireline for a steady state outdoor temperature of -25 P.

Assuming no flow in the line, the model indicates that the added insulation alone may not be adequate to prevent freezing of the fire lines under these conditions. Based on this, maintaining a small flow (0.1 gpm) through the lines is required to prevent freezing of these fire lines.

Final Correqtiy.e_AgtioE Detroit Edison will maintain a constant flow of at least 0.1 gpm through the affected fire protection lines throughout the winter season.

Observation of this flow will be included in the operators' shift rounds when the potential for freezing exists during the winter season.

This is Detroit Edison's final report on this item.

If you have questions concerning this matter, please contact Mr.

Joseph E. Conen (313) 586-5083.

Sincerely

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P. M. Byron

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J. M. Taylor V

G. C. Wright USNRC Document Control Desk Washington, D.C. 20555 N

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