05000346/LER-1979-061-03, /03L-0 on 790518:control Room Emergency Damper HV5311A Stuck in Open Position During Surveillance Testing. Caused by Humidity Corroding Brass Bushings of Shaft.Damper Repaired & Humidifiers Relocated

/03L-0 on 790518:control Room Emergency Damper HV5311A Stuck in Open Position During Surveillance Testing. Caused by Humidity Corroding Brass Bushings of Shaft.Damper Repaired & Humidifiers Relocated

ML19270H030
Person / Time
Site:	Davis Besse
Issue date:	06/14/1979
From:	Rudolph J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19270H028	List: 05000346/LER-1979-061, Forwards LER 79-061/03L-0 05000346/LER-1979-061-03, /03L-0 on 790518:control Room Emergency Damper HV5311A Stuck in Open Position During Surveillance Testing. Caused by Humidity Corroding Brass Bushings of Shaft.Damper Repaired & Humidifiers Relocated
References
LER-79-061-03L, LER-79-61-3L, NUDOCS 7906220389
Download: ML19270H030 (3)

LER-1979-061, /03L-0 on 790518:control Room Emergency Damper HV5311A Stuck in Open Position During Surveillance Testing. Caused by Humidity Corroding Brass Bushings of Shaft.Damper Repaired & Humidifiers Relocated

Event date:
Report date:
3461979061R03 - NRC Website

text

U.S. NUCLE AH HECULATORY COMMISSION NGC FORM 366 (7-77)

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63 EVENT DATE 14 lb HEPOHT DATE 80 EVENT DESCRIPTION AND PROR ABLE CONSEQUENCES h l O J 2 ) [ On 5/18/79, Control Room Emergency Ventilation Damper llV5311A stuck in the open posi-This is one of the two dampers l

l tion during the performance of surveillance testing.

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l that sends air f rom the normal air system to the Control Cabinet Room 502. With the l

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[ station in Mode 5, no action statement was entered.

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l o is l l Lo document a component f ailure. There was no danger to the health and safety of the j l public or sta tion personnel. The redundant damper was operable.

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CAUSE

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40 41 42 43 44 47 CAUSE DESCRIPTION AND CORHECTIVE ACTIONS l The damper shaf t was binding in the brass bushings. Appa cutly, moisture from the l

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l normal air humidifiers located above the damper is speeding corrosion of the~ ennper l3 ji j l shafts creating interference with the bushings.

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this occurrence to relocate the j

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. POWER OTHEH ST ATUS ISC V Y DISCOVEHY DESCHIPTION ST S

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-62 DATE OF EVENT: May 18,1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Control Room Isolation Damper HV5311B found to be inoperable Conditions Prior to occurrence: The unit was in Mode 5, with Power (MWT) = 0, and Load (Gross MWE) = 0. Description of occurrence: At 1400 hours on May 18, 1979, Control Room Emergency Ventilation Damper HV5311A stuck in the open position during the performance of Sur-veillance Test ST 5032.01, " Radiation Monitoring System Functional Test". This is one of the two dampers that sends air from the normal air system to the Control Cabinet Room 502. With the station in Mode 5, no action statement was entered. This occurrence is being reported to document a component failure. Designation of Apparent Cause of Occurrence: One of the damper shafts (dual blade damper) was binding in the brass bushings. Apparently, moisture from the normal air humidifiers located above the damper is speeding corrosion of the damper shaf ts creating interference with the bushings. Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. This damper is redundant in the normal air system which is isolated when the Control Room Emergency Ventilation System is actuated. The unit was in Mode 5 when the f ailure occurred, and neither Emergency Ventilation System train was required.

Corrective Action

This damper is one of four Control Room Isolation Dampers (HV5301A-B, 5311A-B) located below the normal air humidifiers. Facility Change Request 79-199 was issued to change the se damper shaf ts to stainless steel, which will prolong damper shaf t bushing life. Dampers HV5301A, 5301B and 5311B were re-moved f rom service and reconditioned under the manuf acturer's representative super-vision per Maintenance Work Orders 79-2075, 79-2074 and 79-2071, respectively. Stain-less steel shafts were utilized at this time. Damper HV5311A was reconditioned approxi-mately May 1, 1979 (Licensee Even; Report NP-33-79-54). All of the above dampers are installed and were tested for response time per ST 5076.03, " Control Room Emergency 2347 304 LER #79-061

TOLEDO EDIS0!! COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE PAGE 2 SUPPLEMENT /sb INFORMATION FOR LER NP-33-79-62 Ventilation System Refueling Test" before returning to service. Facility Change Request 79-093 was initiated previous to this occurrence to relocate the humidifiers away from the isolation dampers. Failure Data: There have been previous failures of Control Room Emergency Ventilation System Dc.pers; see Licensee Event Reports NP-33-77-95, NP-33-78-123 and NP-33-79-54. LER #79-061 2347 105 }}