05000346/LER-1980-018-03, /03L-0:on 800226,safety Features Actuation Sys Channel 3 Borated Water Storatge Tank Level Indication Was Discovered Reading Four Feet Higher than Other Three Channels.Caused by Inadequate Design of Freeze Protection

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/03L-0:on 800226,safety Features Actuation Sys Channel 3 Borated Water Storatge Tank Level Indication Was Discovered Reading Four Feet Higher than Other Three Channels.Caused by Inadequate Design of Freeze Protection
ML19305C429
Person / Time
Site: Davis Besse 
Issue date: 03/25/1980
From: Hill B
TOLEDO EDISON CO.
To:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19305C408 List:
References
LER-80-018-03L, LER-80-18-3L, NUDOCS 8003280538
Download: ML19305C429 (3)
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LER-1980-018, /03L-0:on 800226,safety Features Actuation Sys Channel 3 Borated Water Storatge Tank Level Indication Was Discovered Reading Four Feet Higher than Other Three Channels.Caused by Inadequate Design of Freeze Protection
Event date:
Report date:
3461980018R03 - NRC Website
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text

U. S. NUCLE AR HEGULATOHY CG.M11SSION FJRC FORT.10GG (7 77) ~

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  • ET NU*>aER bd bJ EVENT OATE 74 75 REPORT OATE HO EVENT CESCRIPTION AND PRODAOLE CONSECUENCES h I o l 2 l MNP-33-80-25)

On 2/26/80 at 0317 hours0.00367 days <br />0.0881 hours <br />5.241402e-4 weeks <br />1.206185e-4 months <br />, it was noted by operations personnel that g

[o l31 l Safety Features Actuation System (SFAS) Channel 3 Borated Water Storage Tank (BWST) g l o 14 l l level indication was reading four feet higher than the other three channels. The chanj lnel was declared inoperable at 0411 hours0.00476 days <br />0.114 hours <br />6.795635e-4 weeks <br />1.563855e-4 months <br /> and placed in the tripped condition.

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O s j o ls l l 2/29/80 at 0750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br /> the same indication failed again.

It was declared inoperable atg In each case, the action statement of l a l; l l 0819 hours0.00948 days <br />0.228 hours <br />0.00135 weeks <br />3.116295e-4 months <br /> and placed in the tripped condition.

g g a ;a l lT.S. 3.3.2.1 was satisfied. The remaining three channels were operable.

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, 7 ITv l L26,1980 with the construction of a heavier windbreak. The second event was the resulp

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It was corrected at 1845 hours0.0214 days <br />0.513 hours <br />0.00305 weeks <br />7.020225e-4 months <br /> on 2/29/80.

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NAME OF PREPARER sm n/a

e TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLE > ENTAL INFORMATION FOR LER NP-33-80-25 DATE OF EVENT:

February 26, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE:

Borated Water Storage Tank (BWST) Level Indication in Safety Features Actuation System (SFAS) Channel 3 inoperable Cinditions Prior to Occurrence: The unit was in Mode 1, with Power (MWT) = 2533, end Load (Gross MWE) = 852.

Dtscription of Occurrence: On February 26, 1980 at 0317 hours0.00367 days <br />0.0881 hours <br />5.241402e-4 weeks <br />1.206185e-4 months <br />, it was noted by opera-tions personnel that the SEAS Channel 3 BWST level indication was reading approximately fcur feet higher than the other three BWST level indications.

The channel was declared inoperable by operations personnel at 0411 hours0.00476 days <br />0.114 hours <br />6.795635e-4 weeks <br />1.563855e-4 months <br /> and was placed in the tripped condition.

This occurrenc( placed the unit in Action Statement 9 of Technical Specification 3.3.2.1.

This technical specification states that BWST level instrument strings shall be opera-ble in Modes 1, 2, and 3.

Action Statement 9 states that with one channel inoperable, operation may proceed provided (a) the inoperable unit is placed in the tripped condi-tion within one hour, and (b) the remaining three channels are operable.

On February 29, 1980 at 0750 hours0.00868 days <br />0.208 hours <br />0.00124 weeks <br />2.85375e-4 months <br />, it was noted that SFAS Channel 3 BWST level indica-tion had failed again. The channel was declared inoperable and placed in the tripped condition at 0819 hours0.00948 days <br />0.228 hours <br />0.00135 weeks <br />3.116295e-4 months <br /> in accordance with the action statement of Technical Specifica-tion 3.3.2.1.

The remaining three channels were operable.

Dxsignation of Apparent Cause of Occur ence: The cause of the occurrence is the inade-quacy of the design of the freeze prot m which presently has to be supplemented L

'with a temporary windbreak.

High winds / ntroyed the windbreak (made out of laminated plastic sheets) and blew out the flame to the portable propcane heater that was inside the windbreak.

Extreme cold temperatures then caused the sensing line of the level transmitter (LT 1525C) to begin to freeze up.

The second occurrence was due to the portable propane heater running out of fuel.

Extreme cold temperatures then caused the sensing line of the level transmitter to freeze.

E cility Change Request 79-123 (implemented December 13, 1979) which installed new gnclosures around the level transmitters and relocated heat trace temperature sensors to worst case locations was insufficient to protect against freezing during high wind canditions.

Analysis of Occurrence: There was no danger to the health and safety of the public or to station personnel. The remaining three BWST level instrument strings were opera-

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ble during the period in which the SEAS Channel 3 BWST level instrument was inoperable, i

LER #80-018 t

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT CNE SUPPLEMENTAL INFORMATION FOR LER NP-33-80-25 PAGE 2

Corrective Action

On February 26, 1980, a temporary windbreak was constructed out of canvas and placed -around the BWST level transmitter and a portable propane heater was:placed inside the windbreak. Within a short period of time, after the application of additional heating, LT 1525C indication returned to normal.

Surveillance Test ST 5099.01 was performed and at 0922 hours0.0107 days <br />0.256 hours <br />0.00152 weeks <br />3.50821e-4 months <br /> on February 26, 1980, LT 1525C was declared cperable. This removed. the unit from the action statement.

The second occurrence _was corrected by replacing the propane tank with a full one.

Once heat was applied, BWST Channel 3 level indication returned to normal. At 1845 hours0.0214 days <br />0.513 hours <br />0.00305 weeks <br />7.020225e-4 months <br /> on February 29,1980, LT 1525C was declared operable by the criteria of

- ST 5099.01. A program has been established to check the propane tanks to ensure an adequate supply of fuel to keep the heaters operating.

There have been no subsequent problem.a. Toledo Edison is investigating further improvements to the freeze protection.

Failure Data: Previous incidents have occurred concerning BWST level indication failures due to freezing, see Licensee Event Reports NP-33-77-107, NP-33-78-01 (78-001),

NP-33-80-23 (80-017), NP-33-79-32 (79-028), and NP-33-78-142 (78-121)

LER #80-018 i

l

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