ML19329B311

LER 77-082/03L-0:on 771019,discharge & Recirculation Dampers of Emergency Ventilation Sys 2 Failed to Open When Fan Started.Caused by Loose & Dirty Controller Contacts.Module Removed & Reinserted, & Contacts Cleaned

ML19329B311
Person / Time
Site:	Davis Besse
Issue date:	11/14/1977
From:	Alton W TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19329B289	List: ML19329B288 ML19329B311
References
LER-77-082-03L, LER-77-82-3L, NUDOCS 8002040734
Download: ML19329B311 (3)

Text

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LICENSEE EVENT REPORT q ,

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? 8 60 61 QQCKET NUM8ER EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h lol2l l At 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> on October 19, 1977, it was found that the discharge and recirculation [

lo l3 l l dampers of the #2 Emergency Ventilation System (EVS) were not opening when the fan [

o;4i lvas started. This caused the #2 EVS Fan to run without air flow causing a low dif- l l o I s t l ferential pressure across the filter. This disabled #2 EVS Train placing the station g g

t o le I f in the Action Statement of Technical Specification 3.6.5.1 which requires two opera-l o } 7 I I ble EVS Trains in Mode 1. OIP-33-77-82) [

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EVENT YEA R REPORT No. CODE TYPE NO.

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AIRE A 47 J3 34 35 36 27 40 43 i CAUSE OESCRIPTION AND CORRECTIVE ACT!ONS h l The aoparent cause was g g iThe exact cause of the malfunction has not been determined. l

[i 1i l l that the controller centacts were loose or were dirtv. The removal and re-insertien f

,, i2; I of the module and the cleaning of the field contacts restored good electrical contact.!

i;3; ] A modification will be made to the monthly Surve.illance Test, ST 5067.01, to check l i i i .s i i the operation of these damners. 80 I

7 8 9 STA 'E f'CWER oTHER STATUS 1 RY DISCOVERY DESCRIPTION l l l1 15 l l3 l@ l 0 l 0 l 0 l@l NA l 3 l@l NA ACTtVITY CO TENT RELEASE AMOUNT CF ACTIVITY LOCATION OF RELEASE l1 l s j j El @D OF RELEASE NA l Z lgl l l NA l 44 45 60 7 4 9 10 11 PERSONNEL EXPOSURES s

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NAME CF PREPARER

TOLEDO EDISON COMPANY

. DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION

) SUPPLEMENTAL INFORMATION FOR LER NP-33-77-82 J

DATE OF EVENT: October 19, 1977 FACILITY: Davis-Besse Unit 1 Emergency Ventilation System Train 2 Dampers f~ ailed

~

IDENT 5ICATION OF OCCURRENCE:

.to. modulate _ correctly. ,

Conditions Prior to Occurrence: The plant was in Mode 1, with Power (MWT) = 190 and Load (MRE) = 0.

Description of Occurrence: On October 18, 1977, during review of tha data from Surveillanca Test, ST 5067.01, " Emergency Ventilation System Monthly Test", per-formed on October 17, 1977, it was noted that the filter differentials across

1. 2 Emergency Ventilation System (EVS) filters were excessively low. A work order was issued to investigate the problem and to find out if we had a low flow problem or gauge calibration problems.

On October 19, 1977 at 1500 hours0.0174 days <br />0.417 hours <br />0.00248 weeks <br />5.7075e-4 months <br /> while running the EVS Train 2 to investigate the lew differential pressure problems, it was discovered that the discharge and

[,,_j recirculation dampers (CV 5014A and B) were not opening Sincewhen the fan the EVS started Train could not y ,j which caused the EVS Fan to run without air flow.

serve its intended safety function, the EVS Train 2 was declared inoperable.

This placed the station in the Action State =ent of Technical Specification 3.6.5.1 which requires two operable EVS Trains in Mode 1. Further investigation revealed that the breakers supplying the discharge and recirculation dampers had been opened.

After the breakers were closed, the system was restarted and the recirculation damper opened to approxi=stely 50% i= mediately after start of the fan which did not allow the EVS Fan to draw down the annulus to -0.75 inches of water (the fan's. safety function. after. a Loss of Coolant Accident) . The system was left in ~

the inoperable ' status and the breakers ' for the fan and dampers were opened.

EVS Train 1-1 was tested and functioned properly.

Designation of Apoarent Cause of Occurrence: During investigation of the problem, the fan was run numercus times and even though the system would not draw down the annulus and the da=pers would not operate correctly, the system did not respond the

! same during re-tests. Calibration was checked on the damper actuators (CV 5014A and B), and the actuators were not out of calibration. The pressure differential transmitter (PT 5014) was functionally checked and was satisfactory. The pressure differential controller (PDC 5014) was then removed and a bench check was performed.

V _

s TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION PAGE 2 C) SUPPLEMENTAL INFORMATION'FOR LER NP-33-77-82 The controller functioned properly in the shop where it had not in the field.

Upon reinstallation of the controller, a retest was performed and the system functioned properly with the recire damper staying closed until the setpoint pressure of -0.75 inches of water was reached and then it modulated open only enough to maintain the setpoint pressure. Even though the exact cause has not been determined, the apparent causa of the- controller malfunction was that the contacts on the back of the controller were either loose or had some small dirt accumulation that was removed by the five times that the module was plugged in during the process'of the checkout or the cleaning that was done on the field contacts.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The system was inoperable; however, it would not affect the operation of the EVS Train 1-1 which would still draw down the annulus to the -0.75 inches of water setpoint.

Corrective Action: A modification will be turned in to =odify the Monthly Surveillance Test, ST 5067.01, to check operation of these dampers.

(O)%d Failure Data: No previous similar events have occurred.

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