05000346/LER-1979-034-01, /01T-0 on 790103:HPI Pump 1-1 Was Stopped Due to Low Recirculation Flow Indication.Caused by Inability of Heat Trace to Maintain HPI Pump Recirculation Line Temp Above Freezing.Heat Increased

/01T-0 on 790103:HPI Pump 1-1 Was Stopped Due to Low Recirculation Flow Indication.Caused by Inability of Heat Trace to Maintain HPI Pump Recirculation Line Temp Above Freezing.Heat Increased

ML19263D383
Person / Time
Site:	Davis Besse
Issue date:	03/23/1979
From:	David Brown TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19263D379	List: 05000346/LER-1979-034, Forwards LER 79-034/01T-0 05000346/LER-1979-034-01, /01T-0 on 790103:HPI Pump 1-1 Was Stopped Due to Low Recirculation Flow Indication.Caused by Inability of Heat Trace to Maintain HPI Pump Recirculation Line Temp Above Freezing.Heat Increased
References
LER-79-034-01T, LER-79-34-1T, NUDOCS 7903290124
Download: ML19263D383 (4)

LER-1979-034, /01T-0 on 790103:HPI Pump 1-1 Was Stopped Due to Low Recirculation Flow Indication.Caused by Inability of Heat Trace to Maintain HPI Pump Recirculation Line Temp Above Freezing.Heat Increased

Event date:
Report date:
3461979034R01 - NRC Website

text

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EVENT DATE 74 75 REPORT DATE 8J EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h 1400 hours0.0162 days <br />0.389 hours <br />0.00231 weeks <br />5.327e-4 months <br /> on 1/3/79, High Pressure Injection (HPI) Pump 1-1 was started per "Emer-j o 2 l At ST 5051.01. At 1406 hours0.0163 days <br />0.391 hours <br />0.00232 weeks <br />5.34983e-4 months <br />, HPI g

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t i g,;7; l pump recirculation line heat trace was increased and a temporary heated enclosure was l built around it.

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DVR 79-048 NAME OF PREPARER PHON E :

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR PCWER STATION U'IIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-32-79-03 DATE OF EVENT: January 3, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE:

Inoperability of High Pressure Injection Pumps 1-1 and 1-2 due to minimum recirculation line freezing Conditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT) = 2384, and Load (Gross MWE) = 763.

Description of Occurrence: At 1400 hours0.0162 days <br />0.389 hours <br />0.00231 weeks <br />5.327e-4 months <br /> on January 3,1979, High Pressure Injection (HPI) Pump 1-1 was started per " Emergency Core Cooling System Subsystem Monthly Test",

ST 5051.01. At 1406 hours0.0163 days <br />0.391 hours <br />0.00232 weeks <br />5.34983e-4 months <br />, HPI Pump 1-1 was stopped due to a low ficw indication on the HPI pump to the Borated Water Storage Tank (BWST) minimum recirculation line (3" HCC-91).

Further investigation discovered that this line had frozen outside somewhere between the BWST Pipe Tunnel and the top of the LUST. Maintenance personnel were immediately notified.

Maintcaance personnel increased the thermostat setting for the HPI pump minimum re-circulation line heat trace and built a temporary heated enclosure around the exposed line. The recirculation line was thawed and ST 5051.01 was successfully completed for HPI Pump 1 I at 1105 hours0.0128 days <br />0.307 hours <br />0.00183 weeks <br />4.204525e-4 months <br /> on January 5, 1979.

At the time of the incident, an analysis of the frozen recirculation line by the station indicated that the minimum flow rate required for pump cooling would flow through the injection line if the HPI pumps were started during a loss of coolant accident. As a result, both HPI Pump 1-1 and HPI Pump 1-2 were considered operable, and the unit was not in violation of any Technical Specifications.

On March 12, 1979 in a discussion between station personnel and TECo Power Engineer-ing personnel, Power Engineering personnel stated that they had done an analysis of a previous IFI initiation event (see Licensee Event Report NP-32-77-16 dated Septem-ber 24, 1977) which indicates that the minimum required HPI flow may not have existed if the recirculation line was plugged. As a result of this analysis, both HPI pumps must now be considered to have been inoperable between 1406 hours0.0163 days <br />0.391 hours <br />0.00232 weeks <br />5.34983e-4 months <br /> on January 3,1979 and 1105 hours0.0128 days <br />0.307 hours <br />0.00183 weeks <br />4.204525e-4 months <br /> on January 5, 1979.

The inoperability of the HPI pumps placed the unit in violation of Technical Speci-fication 3.5.2 which requires that two independent Emergency Core Cooling System subsystems shall be operable with each subsystem comprised of cac operable HPI pump, one operable Low Pressurc Injection Pump, one operable Decay Heat Cooler, and one operable flowpath capable of taking suction from the BUST.

Decignation of Apparent Cause of Occurrence: This incident was caused by the inabi-lity of the heat trace on the HPI pump to BWST minimum recirculation line, 3" HCC-91, to maintain a pipe temperature above freezing. As a result, this line froze during sub-zero weather and rendered the HPI pumps inoperable.

LER #79-034

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE PAGE 2 SUPPLEMENTAL INFORMATION FOR LER NP-32-79-03 Analysis of Occurrence:

There was no danger to the health and safety of the public or unit personnel. No event requiring the actuation of the HPI pumps occurred.

The only situation where the HPI pitmps could have been damaged would be a small sized Reactor Coolant System leak with Reactor Coolant System pressure being main-tained slightly above the HPI pumps shutoff head.

Corrective Action

Maintenance personnel increased the thermostat setting for the HPI pump to BWST minimum recirculation line heat trace and built a temporary heated enclosure around it.

The recirculation line was thawed and ST 5051.01 was success-fylly completed for HP1 Pump 1-1 at 1105 hours0.0128 days <br />0.307 hours <br />0.00183 weeks <br />4.204525e-4 months <br /> on January 5, 1979.

TECo Power Engineering is continuing its analysis on HPI pump "no flow" conditions.

Station personnel are conducting further investigation into the inability of the recirculation line heat trace to maintain the line temperature above freezing and will initiate Facility Change Requests and/or maintenance work orders to correct the problem.

Failure Data: There have not been any previous reportable occurrences with the HPI pumps recirculation line.

LER #79-034