ML20010B499

LER 78-097/03X-1:on 780917,loud Noises Heard Emitting from Vacuum Pump on post-accident Radiation Monitor.Caused by Cracked Diaphragm Inside Pump Discharge Solenoid Valve, Possibly Due to High Ambient Temps

ML20010B499
Person / Time
Site:	Davis Besse
Issue date:	08/04/1981
From:	Schwenning L TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML17275B377	List: ML17275B376 ML20010B493 ML20010B495 ML20010B497 ML20010B499 ML20010B500 ML20010B501 ML20010B503 ML20010B504
References
LER-78-097-03X, LER-78-97-3X, NUDOCS 8108170105
Download: ML20010B499 (2)

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LICENSFE EVENT REPORT (PLE ASE PRINT OR TYPE ALL REQUIRED INFORMATIONI CONTROL BLOCK

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7 8 60 61 DOCKET NUVB E R EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h

(o12]] (NP-33-78-115) At 2220 hours0.0257 days <br />0.617 hours <br />0.00367 weeks <br />8.4471e-4 months <br /> on September 17, 1978, loud noises were heard emitting i i c I 3 J l fr m the vacuum pump on post-accident radiation monitor RE 5030. The radiation monitor l j

gg,,, gwas rem 6ved from service. There was no danger to the health and safety of the public gg,,, , or to station persor nel. The other post-accident radiation monitor RE 5029 was opera- l l

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, , ybelieved.that this failure was caused by high ambient temperatures inside the radiation]

monitor cabinet. A new diaphragm was installed in the solenoid valve. At 1805 hours0.0209 days <br />0.501 hours <br />0.00298 weeks <br />6.868025e-4 months <br /> l

,y on September 18, 1978, RE 5030 was declared operable. FCR 78-521, which reduces the l y

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speed of the pumps in RE 5029 and RE 5030, has been implemented. _

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TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORMATION FOR LER NP-33-78-115 O

DATE OF EVENT: September 17, 1978 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Post-Accident Radiation Monit or RE 5030 inoperable.

Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT)

= 2772, and Load (MWE) = 920.

Description of Occurrence: At 2220 hours0.0257 days <br />0.617 hours <br />0.00367 weeks <br />8.4471e-4 months <br /> on September 17, 1978, Ioud noises were heard emitting from the vacuum pump on Post-Accident Radia-tion Monitor RE 5030. The radiation monitor was removed from service.

This placed the unit in the Action Statement of Technical Specification 3.3.3.6, which requires that the monitor be repaired within 30 days. The Technical Specification requires the operability of both post-accident radiation monitors while the unit is in Modes 1, 2 or 3.

Designation of Apparent Cause of Occurrence: The apparent cause of the 1 occurrence is attributed to component failure. A diaphragm inside the pump discharge solenoid valve was found to have cracked. It is believed that this failure was caused by high ambient temperatures inside the 1 radiation monitor cel:inet.

Analysis of Occurrence: There was no danger to the health and safety of the public or to unit personnel. The other Post-Accident Radiation Monitor, RE 5029, was operable during the period that RE 5030 was inoper-able.

Corrective Action: Under Maintenance Work Order 78-2178 and I&C Work Order 78-536, a new diaphragm was installed in the solenoid valve. After completion of Surveillance Test ST 5032.dl, " Monthly Functional Test of Radiation Monitoring System", at 1805 hours0.0209 days <br />0.501 hours <br />0.00298 weeks <br />6.868025e-4 months <br /> on September 18, RE 5030 was declared operable. The unit was then removed from the Action Statement of Technical Specification 3.3.3.6.

Facility Change Request (FCR)78-521 has been implemented to reduce the 1 speed of the pumps in RE 5029 and RE 5030. This change will reduce the motor load and consequently decrease the pump wear and internal heating.

Failure Data: This is a repetitive occurrence. Previous failures of post-accident radiation monitors due to high ambient temperatures have been reported in Licensee Event Reports NP-33-78-30, NP-33-78-77, NP-33-78-105, NP-33-78-111.

LER #78-097

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