ML20097B400

Final Deficiency Rept,Item 116 Re Potential Design Deficiency by Allowing Freezing of Buried Pipe Sys.Initially Reported on 840131.New Pipe Lines Installed Below Frost Line

ML20097B400
Person / Time
Site:	Fermi
Issue date:	08/23/1984
From:	Jens W DETROIT EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
116, EF2-69698, NUDOCS 8409140016
Download: ML20097B400 (3)

Text

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%=tu*vaeu August 23, 1984 EF2-69698 ,

' Mr. James G. Keppler Regional Administrator Region III' O. S. Nuclear Regulatory Commission 799 Roosevelt Road '

Glen Ellyn, Illinois 60137

Reference:

(1) Fermi 2 NRC Docket No. 50-341

.(2:) Letter, D. A. Wells to J. G. Keppler, February 29, 1984, QA-84-326

Subject:

Final Report of 10CFR50.55(e) Item 116

" 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, and subsequently documented in Reference (2) .

Description of Deficiency During severe cold weather in January 1984, the supply line for the Division I fire protection system in the Residual lleat Removal (RilR) complex was found to be frozen. This item was originally identified as a potential design defic-iency for buried piping systems because the review to deter-mine the scope of the problem also included safety related, buried lines that enter the RilR complex. Upon engineering review, the scope of the reportable deficiency was deter-mined to be limited to potential freezing of the RilR complex fire protection system supply line.

The supply line for the Division I fire protection system froze in the area where it is routed into the RilR complex.

The pipe is routed from below ground level to the first floor of the building by embedding it inside the building's concrete foundation wall. This wall is exposed to outside 84091400168408b3 g DR ADOCM 05000 t gh4 PDR ' )

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Mr. James G. Keppler August 23, 1984 EF2-69698 Page 2 ambient temperatures on both sides. There is no source of heat in the wall to prevent the line from freezing. The remaining sections of the supply line will not freeze since they are buried six feet or more below grade which is below the frost line, or located inside of the building which is heated to at least 60*F.

The design of the fire protection supply lines into the RilR complex, for both Divisions I and II, are identical. They are routed into the building at different locations, however they both have the same potential to freeze in the winter.

Analysis of Safety Implications In the event that the Ri!R complex fire protection system was rendered inoperable, due to freezing of a supply line, safety related equipment could potentially become inoperable or damaged during a fire. The safety related equipment in the RilR complex which could be affected are the Emergency Diesel Generators, the safety related service water pumps, and the mechanical draft cooling towers.

Corrective Action After the Division I system was reported as inoperable, the emergency cross tie valve which connects Division I and II was opened which made the system operable again. The Division I line was later cleared of ice. To prevent any additional f reezing of these lines, water was passed through the supply lines for both Division I and II once a shift while the potential for freezing existed.

To eliminate future incidents of freezing of the supply lines for both Division I and II, new lines will be installed which bypass the section of the line currently embedded inside the building foundation wall. The new lines will be routed from the base of the building, below the frost line, into the building vertical pipe runs. The remainder of the piping will be run through the building's interior and pipe chases.

The engineering for this project is scheduled to be com-pleted by mid-September, 1984. Upon completion of engi-neering, the installation schedule will be determined. If the installation cannot be completed prior to winter (approximately mid-November), the new lines will not be connected to the existing system and a temporary sclution will be used for the 1984-1985 winter. The temporary L

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.Mr." James G. Keppler August 23, 1984 EF2-69698 Page 3 solution'will require a continuous flow of water through both of the existing supply lines during the winter. The required flow rate has been determined to be 1 GPM. A temporary administrative procedure will. require visual _ l inspections'for flow during. normal; rounds of the operator to the RilR complex. InLaddition, the flow-rate through the temporary lines will be checked every two weeks to verify the flow is 1 GPM or greater.

This is. Detroit Edison's final ~ report of this item. If you have questions concerning this matter, please contact Mr. Lewis P. Bregni, (313) 586-5083.

Sincerely, 4

cc: Mr. P. M. Byron -'

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M r. R. C. DeYoung Mr. R. C. Knop