ML19340C287

LER 80-077/03L-0:on 801013,nine of 20 Control Room Normal Ventilation Dampers Did Not Close within 10-s Limit.Caused by Insufficient Bleedoff Capacity for Control Air Header Which Feeds & Bleeds 10 Dampers Per Header

ML19340C287
Person / Time
Site:	Davis Besse
Issue date:	11/10/1980
From:	Isley T, Melstad K TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19340C286	List: ML19340C285 ML19340C287
References
LER-80-077-03L, LER-80-77-3L, NUDOCS 8011140432
Download: ML19340C287 (2)

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NRC FORM 3M U. S. NUCLE AR REGULATORY CoMMISGIOZ (7 771 LICENSEE EVENT REPORT

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Io 12'l l (NP-M-80-96) On 10/13/80 at 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br /> durinz the performance of the Safety Features l go;3i ; Actuation System Response Time Test, it was observed that 9 of the 20 control room l o 4 l normal ventilation dampers would not close within their 10 second limit for the con- l go,3g;tainment high radiation actuation. Being in Mode 5, the station did not enter the l i

1016 l l action statement of T.S. 3.7.6.1. There was no danger to the health and safety of the1

[ o l 7 l l public or station personnel. The valves did actually close but then allowable stroke l

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g,iollThe cause was insufficient bleedoff capacity for the control air header which feeds and) g,gi;g leeds b 10 dampers per header. FCR 80-244 added a bleedoff solenoid valve to each contrb1

,,,g gair damper header. This improved the response time of the dampers. ST 5031.06 was l lsuccessfully performed. The control room normal ventilation system was declared operai

,, ,,,i ble at 1305 hours0.0151 days <br />0.363 hours <br />0.00216 weeks <br />4.965525e-4 months <br /> on 10/20/80. 1 7 8 9 80 STA S  % POWER oTHER STA TUS OlSCO RY DISCOVERY DESCRIPTION y lH l@ l 0 l 0 l 0 l@l NA l l B l@l SuTvei11ance Test ST 5031.06 l ACTIVITY CO TENT RELEASE AMOUNT OF ACTIVITY LoCATICN OF RELEASE l,1_[6] [Z_] @D OF RELEASE (_Z_j@l NA I l NA I F a 9 10 tt 44 45 80 PERSONNEL f XPOSURES NUVBE R TYPE DESCRIPTION i 7 101010 l@LZJ@l N^ l PERSONNEL INr HIES NUYBER DESCRipilON I TTI3 9101010 l@l 7 11 12 NA 80 l

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DAVIS-BESSE NUCLEAR POWER STATION UhIT ONE l SUPPLEMENTAL INFORMATION FOR LER_NP-33-80-96 4

DATE OF EVENT

October 13, 1980 t

FACILITY

Davis-Besse Unit 1 IDENTIFICATIbN OF OCCURRENCE: Control room normal ventilation dampers failed to iso-late within the 10 second time limit for containment high radiation actuation j

Conditions Prior to Occurrence: The unit was in Mode 5 with Power (MWT) = 0 and Load (Gross MWF) = 0.

I j Description of Occurrence: At 1300 hours0.015 days <br />0.361 hours <br />0.00215 weeks <br />4.9465e-4 months <br /> on October 13, 1980 during the performance 4

of the Safety Features Actuation Syster (SFAS) Overall Response Time Test ST 5031.06, the following control room normal ventilation isolation dampers HV5301A, 5301B, 5301E, 1

5361A, 5362A, 5362B, 5311A, 5311B and 5311E exceeded the required actuation time of

{ 10 seconds for containment high radiation actuation. Being in Mode 5, the station did

! not enter the actidn statement of Technical Specification 3.7.6.1. The Technical Speci-fication requires the two control room emergency ventilation systems to be operable in

! Modes 1, 2, 3, and 4. This event is being reported to document the failure of techni-cal specification equipment to meet all of its operating criteria. .

4 Designation of Apparent Cause of Occurrence: The cause has been 2rmined to be a

design error. The problem was an insuf ficient bleedoff rate of tu control air header.

There are two control room normal ventilation trains. There are ten dampers on each

, train. The control for the ten dampers in each train is from one control air header -

with one solenoid control valve feeding and bleeding the header. Feeding the header i

has not been a probles since the dampers are normally open. However, the bleedoff rate has been too restrictive and the closing times for the dampers have always been near the limit. Normal wear and any dust buildup or slight corrosion is enough to cause the damper to fail its closing response time requirement. Therefore, it was

. necessary to increase the bleedoff rate. '

l Analysis of Occurrence: There was no danger to the health and safety of the public or

! to station personnel. The dampers failed the acceptance criteria by less than one

second each. They were operable in all other aspects.

C'orrective Acticn: Facility Change Request 80-244 was implemented which added a bleed-off solenoid valve to each control air header. The added bleedoff capacity has improved the damper closing times such that all dampers close within the required time.

ST 5031.06 was successfully performed at 1305 hours0.0151 days <br />0.363 hours <br />0.00216 weeks <br />4.965525e-4 months <br /> on October 20, 1980, and the control room normal ventilation system declared operable.

i Failure Data: A failure due to insufficient bleedoff was reported in Licensee Event Report NP-32-79-10 (LER 79-084).

LER #80-077 i

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