05000327/LER-1980-205-03, /03L-0:on 801229 & 810105,two Ice Condenser Intermediate Deck Doors Below AHU-3A Found Frozen Closed. Caused by Overflow from Drip Pan Freezing Around Doors.Ice Removed

/03L-0:on 801229 & 810105,two Ice Condenser Intermediate Deck Doors Below AHU-3A Found Frozen Closed. Caused by Overflow from Drip Pan Freezing Around Doors.Ice Removed

ML19341B538
Person / Time
Site:	Sequoyah
Issue date:	01/26/1981
From:	Mcgriff J TENNESSEE VALLEY AUTHORITY
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19341B536	List: 05000327/LER-1980-205, Forwards LER 80-205/03L-0 05000327/LER-1980-205-03, /03L-0:on 801229 & 810105,two Ice Condenser Intermediate Deck Doors Below AHU-3A Found Frozen Closed. Caused by Overflow from Drip Pan Freezing Around Doors.Ice Removed
References
LER-80-205-03L, LER-80-205-3L, NUDOCS 8102020483
Download: ML19341B538 (2)

LER-1980-205, /03L-0:on 801229 & 810105,two Ice Condenser Intermediate Deck Doors Below AHU-3A Found Frozen Closed. Caused by Overflow from Drip Pan Freezing Around Doors.Ice Removed

Event date:
Report date:
3271980205R03 - NRC Website

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?S RtPORfDAft to EVEt47 DESCRIPTION AND PROS A8LE CONSEQUENCES Q l o 12 l l Unit in Mode 1 at 86% reactor power. On 12-29-80 and again on 1-5-81. two ice i

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l o l a 1 l was entered on both occasions. There was no effect upon public health or safety.

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Tennessee Valley Authority Sequoyah Nuclear Plant LER SUPPI.EMENTAL INFORMATION SQRO-50-327/80205 Technical Specification Involved:

3.6.5.3 Reported Under Technical Specification:

6.9.1.13.b Date of Occurrences:

12-29-80, 1-5-81 Time of occurrences: 0118 CST, 1815 CST Identification and Description of Occurrences:

During routine inspection of ice condenser on 12-29-80, and again on 1-5-81, two ice condenser intermediate deck doors under AHU-3A were found frozen closed daring each inspection.

4 Conditions Prior to Occurrence:

Unit 1 in Mode 1 at 86% reactor power on 12-29-80 and at 90% reactor power on 1-5-81.

Apparent Cause of Occurrence:

j Water froze in AHU-3A defrost drain line blocking flow during subsequent Water spilled from drip defrost cycles and caustry drain line :o rupture.

pan onto doors and froze.

I Analysis of Occurrence:

On the first occurrence (12-29-80), water had frozen in the defrost drain line of AHU-3A causing both flow blockage and the drain line to rupture.

On 1-2-81, insulation was removed Water epilled from drip pan onto doors.

from the drain line, heat tracing removed, and a temporary heat tape installed so that the line could be repaired. The second occurrence (1-5-81) can be First, water spilling over drip pan during defrost attributed to two causes.

12-29-80 and 1-2-81.

Second, water from melting ice in drain cycles between line.. af ter installation of temporary heat tape, dripping from rupture in drain line.

Corrective Action

The ice was removed from the doors on both occasions within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.

Ruptured drain line was repaired by.1-6-81.

An investigation has begun to determine why the drain line has been freezing.

Failure Data:

None