05000346/LER-1979-082-03, /03L-0 on 790720:discovered That Containment post-accident Radiation Monitor Re 5030 Had Tripped.Caused by Sufficient Pump Wear Resulting in Low Flow Setpoint Being Reached.Pump Bypass Valve Adjusted

/03L-0 on 790720:discovered That Containment post-accident Radiation Monitor Re 5030 Had Tripped.Caused by Sufficient Pump Wear Resulting in Low Flow Setpoint Being Reached.Pump Bypass Valve Adjusted

ML19249A242
Person / Time
Site:	Davis Besse
Issue date:	08/16/1979
From:	Adams J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19249A241	List: 05000346/LER-1979-082, Forwards LER 79-082/03L-0 05000346/LER-1979-082-03, /03L-0 on 790720:discovered That Containment post-accident Radiation Monitor Re 5030 Had Tripped.Caused by Sufficient Pump Wear Resulting in Low Flow Setpoint Being Reached.Pump Bypass Valve Adjusted
References
LER-79-082-03L, LER-79-82-3L, NUDOCS 7908210439
Download: ML19249A242 (2)

LER-1979-082, /03L-0 on 790720:discovered That Containment post-accident Radiation Monitor Re 5030 Had Tripped.Caused by Sufficient Pump Wear Resulting in Low Flow Setpoint Being Reached.Pump Bypass Valve Adjusted

Event date:
Report date:
3461979082R03 - NRC Website

text

U. S. NUCLEAR REGULATORY COMMISSION NRC FORM 3GG (7 77)

LICENSEE EVENT REPORT CONTROL BLOCK:

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$1 DOCKET NuvuER 68 69 EVENT DATE 14 76 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h 10121 l on 7/20/79 at 0815 hours0.00943 days <br />0.226 hours <br />0.00135 weeks <br />3.101075e-4 months <br /> it was found that Containment Post-Accident Radiation Vanitor The redundant monitor, RE 5029, was in standby and not operating j g iT2 5030 had tripped.

RE 3U.5U l This occurrence placed the unit in the Action Statement of T. S. 3.4.6.1.

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4 iOlsi lhad been onernrine at 0715 honra nn 7/70/74. There was no danger to the health and O

6 IsafetV of the public or unit personnel. The radiation monitors do not control any I 0 l 7 I ( equpment but are used for monitoring purposes only.

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33 30 31 40 41 42 43 44 47 CAUSE StSCRIPTION AND CORRECTIVE ACTIONS lRE 5029 and RE 5030 were started when discovered off. The cause was sufficient pump i

O i wear to result in the low flow setpoint being reached. This de-energized the pumps lij3j gmotor.

In performing Surveillance Test ST 5032.01, the pump bypass valve was adjusted l to provide suf ficient flow to successfully complete the monthly functional test.

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DVR 79-117 James D. Adams PHONE:

NAME OF PREPARER

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-79-96 DATE OF EVENT: July 20, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Both Containment Post-Accident Radiation Monitors RE 5029 and RE 5030 found not operating 73 Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT) = 2744, and Load (Gross MWE) = 915 Description of Occurrence: On July 20, 1979 at 0815 hours0.00943 days <br />0.226 hours <br />0.00135 weeks <br />3.101075e-4 months <br />, Radiation Monitor RE 5030 was discovered off during a routine shif t check. This made the containment atmosphere radioactivity monitoring system inoperable since the redundant radiation monitor RE 5029 was also off, having been secured in the off position for standby use.

RE 5030 and RE 5029 were immediately started which removed the unit from the Action Statement of Technical Specification 3.4.6.1.

The Action Statement requires that with both gaseous and particulate monitoring systems inoperable, the unit must be in hot standby within six hours and be in cold shutdown within the following thirty hours. The pump had previously been reported operable at 0715 hours0.00828 days <br />0.199 hours <br />0.00118 weeks <br />2.720575e-4 months <br /> on July 20, 1979, and therefore, the maximum length of tLne the pump could have been inoperable was one hour.

Designation of Apparent Cause of Occurrence: The cause of the occurrence was the carbon vanes of the RE 5030 pump wearing sufficiently to result in the low flow setpoint to be reached. This causes the low flow motor interlock tc de-energize the pump motor.

Analysis of Occurrence:

There was no danger to the health and safety of the public or to station personnel. This system is not involved in monitoring releases to the environment. These monitors are intended to detect any Reactor Coolant System leak which would increase the gaseous and particulate radioactivity of containment atmosphere. There were no leaks during the hour that RE 5030 was off as there were no increases in the monitor levels when they were returned to service.

Corrective Action

Immediately upon discovery at 0815 hours0.00943 days <br />0.226 hours <br />0.00135 weeks <br />3.101075e-4 months <br /> on July 20, 1979, KE 5030 and RE 5029 were restarted which removed the unit from the Action Statement of Technical Specification 3.4.6.1.

In performing ST 5032.01, Monthly Functional Test on RE 5030, the pumps bypass valve was adjusted to provide sufficient flowrate to successfully complete the test at 1010 hours0.0117 days <br />0.281 hours <br />0.00167 weeks <br />3.84305e-4 months <br /> on July 20, 1979. At 1945 hours0.0225 days <br />0.54 hours <br />0.00322 weeks <br />7.400725e-4 months <br /> on July 20, 1979, RE 5029 was also successfully tested under ST 5032.01.

Operations personnel will now be operating both radiation monitors for inmediate detection if either one stops operating.

Failure Data: Although there have been numerous failures of these radiation moni-g *; {)

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tors, none were similar to this one, O)/

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LER #79-082

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