05000346/LER-1979-084, Revised LER 79-084/01T-1:on 790806,containment Air Coolers Svc Water Outlet Valves Failed to Meet Response Time.Caused by Undersized Air Opening on Pneumatic Actuators.Valves Forced Full Open.Actuating Mechanisms Redesigned

Revised LER 79-084/01T-1:on 790806,containment Air Coolers Svc Water Outlet Valves Failed to Meet Response Time.Caused by Undersized Air Opening on Pneumatic Actuators.Valves Forced Full Open.Actuating Mechanisms Redesigned

ML19330A589
Person / Time
Site:	Davis Besse
Issue date:	08/17/1979
From:	Rudolph J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19330A581	List:
References
LER-79-084-01T, LER-79-84-1T, NUDOCS 8007280622
Download: ML19330A589 (2)

LER-1979-084, Revised LER 79-084/01T-1:on 790806,containment Air Coolers Svc Water Outlet Valves Failed to Meet Response Time.Caused by Undersized Air Opening on Pneumatic Actuators.Valves Forced Full Open.Actuating Mechanisms Redesigned

Event date:
Report date:
3461979084R00 - NRC Website

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U.S. NUCLEAR REGULATORY COMMISSION K F SRM 366 I) /'

LICENSEE EVENT REPORT

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OOCKET NUMBER 68 69 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h lDuring a review of Facility Change Request 79-259, it was determined that a reportable l ol2l 1 i3; l event may have occurred. The containment air coolers service water outlet valves l

lo i, i l failed to meet the response time specified in T.S. Table 3.3-5.

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times have been closed j

oisl l automatically regulated by inlet air temperature they may at lETin i enough to preclude operation within the specified time.

The coolers were functional; I l$TTI I only the service water outlet valve may have been affected. Also, the redundant con-l

tainment spray systems were fully operable. There was no effect on public or personnel l

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40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h The valves pneumatic

• actuators were designed with an undersized air opening. The valvjes 11O I l have now been forced full open by changing controller setpoints from 120 to 50 F.

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The valve actuating mechanisms redesign will be implemented to correct the stroke time.

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419-259-5000, Ext. 299 James P. Rudolph PHONE:

VR 79-126 NAME OF PREPARER

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-79-10 DATE OF EVENT. August 6, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE:

Slou response on containment air cooler service water outlet valves Conditions Prior to Occurrence:

The unit was in Mode 1, with Power (MWT) = 2772, cnd Load (Gross MWE) = 920.

Description of Occurrence: During a review of Facility Change Request 79-259, it was determined that a reportable event may have occurred in that the containment air coolers service water outlet isolation valves failed to meet the response time re-

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quirements of 45 seconds from Table 3.3-5 of Technical Specifications. Technical Specification 3.6.2.2 requires two operable coolers in Modes 1, 2, and 3.

Since the valves in question are automatically regulated by the cooler inlet air tempera-ture, the valves may have been throttled to the extent that at times they would not have opened within the allowable thne. Therefore, this incident is being reported as per Technical Specification 6.9.1.8.1.

Designation of Apparent Cause of Occurrence:

The valve actuating circuit has a design deficiency. The long response time of the valves is due to the slow bleedoff of air from the valve's pneumatic actuator.

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Analysis of Occurrence: There was no danger to the health and safety of the public cr to station personnel. The containment air coolers were functional in all modes cf operation; only the response tima of the service water valves may have been gamewhat degraded.

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Corrective Action

Facility Change Request (FCR)79-259 had been previously written end Dnplemented on June 25, 1979 to change the setpoints on the air cooler service 0

water outlet valve controllers from 1200F to 50 F.

This forces the valves to remain in a full open position thereby eliminating the response time requirement.

i FCR 79-280 was initiated to modify the valve actuating apparatus on SW 1356, 1357, and 1358 to bring their response times within the required limits.

D Failure Data: There have been no previous similar reportable occurrences.

LER #79-084