ML19209D160

LER 79-028/03L-1:on 790217,high Level Fail Alarm Received for Borated Water Storage Tank Level on Safety Features Actuation Sys Channel 1.Caused by Inadequate Insulation of Instrument Piping & Poor Location of Heat Trace Temp Sensor

ML19209D160
Person / Time
Site:	Davis Besse
Issue date:	03/15/1979
From:	Naylor R TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19209D152	List: ML19209D151 ML19209D156 ML19209D160 ML19209D164 ML19209D171
References
LER-79-028-03L, LER-79-28-3L, NUDOCS 7910190476
Download: ML19209D160 (3)

Text

{{#Wiki_filter:% 'dRC F oRM 366 , U. S. NUCLE AR REGULATORY COMMISSION

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LICENSEE EVENT REPORT CONTROL BLOCK: l l l l l l (PLE ASE PRINT OR TYPE ALL REQUIRED INFORMATION) 1 6 og !OllllDlBlSj1l@l0l0 14 15 0 0 l N l P l F l- l 0 l 3 25l@l 264 1 LICENSE LICENSE NUMdER 1 l1 1 1 @l T Y 'E JO 51 C A T bd l@ 8 9 LICEP.SEE CODE OON7 o REPo" 3 nC g6 5 l 0 l - l 0 l 3 l 4 l 663@l630 l 2EVENT 7 l 7 l 9 74l@ 75 0 ] 3REPORT [ 1 lDATE l 1l 51 7 l 980l@ D ATE 3 60 61 DOCKET NUYBER EVENT DESCRIPTION AND PRO 8ABLE CONSEQUENCES h o 2 lOn 2/17/79 at 0655 hours, a high level fail alarm was received for the Borated Water l o 3  ; Storage Tank (BWST) level on Safety Features Actuation System (SFAS) Channel 1. This l At 0720 hours on 2/17/79, I o 4 lplaced the unit in the Action Statement of T.S. 3.3.2.1. l o s BWST Channel 1 level transmitter was placed in the tripped candition. There was no l

 .o    c      l danger to the he 11th and safety of the public or to unit personnel. The remaining                                                                                 l 0  7      I three SFAS BWST level channels were operating properly and wOuld have transf erred the l 3 g,        decay heat and containment spray suctions if a loss of coolant accident had occurred. !

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CAUSE DESCRIPIlON AND CORRECTIVE ACTIONS h ii o l The apparent cause of the occurrence was inadequate in_sulation cm a portion of the 1 ii i j instrument piping and poor location of the heat trace temocrature sensor. Tho froa7 , ii 7 l ing condition which subsequently occurred resulted in the inoperability of SFAS thnved, th e trnnsmittor une f-- 1

  ,i    3 l Ch'annel'l'BWST level indication. The line una l tionally tested and declared operational. removing the unit frnm the Action Srnromont.

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  /        8 9             TO DVR 79-037                                                       Richard Naylor                                                          419-259-5000, Ext. 252 o NAVE OF PPEPARER                                                                                 PHONE:                                                    $      l

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33--79-32 c DATE OF EVENT: February 17, 1979 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Saf ety Features Actuation System (SFAS) Channel 1 Borated Water Storage Tank (BWST) level transmitter inoperabic Conditions Prior to Occurrence: The unit was in Mode 1, with Power (mbt) = 2435, and Load (Gross MWE) = 812. De_ scripti on of Occurrence: On February 17, 1979 at 0655This hours, a high level fail placed the unit in alarm was received for the BWST level on SFAS Channel 1. the Action Statement 9 of Technical Specification 3.3.2.1 which requires that all channels be operational in Modes 1, 2, and 3. The Action Statement requires that operation may continue providing the inoperable channel is placed in the tripped condition within one hour. BWST Channel 1 level transmitter was placed in the tripped condition at 0720 hours on February 17, 1979. Designation of Apparent Cause of Occurrence: The apparent cause of the occuitence was inadequate insulation on a portion of the BWST level instrument piping and poor , 1l location of the beat trace temperature sensor. A four inch section of the source line where it penetrates the protective box around the level instrument did not have adequate insulation. Normal insulation thickness would be lh", actual thickness was b" of insulation. The line is heat traced but the temperature sensor was located so as to be unrepresentative. Due to this fact, no alarm or indication of the freezing condition which occurred was received until the instrument failed high. The fuel supply ran out for the temporary windbreak enclosure heater which could have also prevented the freezing condition. Analysis of Occurrence: There was no danger to the health and safety of the public or to unit personnel. The remaining three SFAS BWST level channels were operating properly and would have transferred the decay heat and containment spray suctions to the emergency sump if a loss of coolant accident had occurred. Corrective Action: The fuel tanks: for the temporary heaters were replaced, the 1 affected instrument lines thawed, and the system operation checked by Surveillance Test ST 5099.01, " Miscellaneous Instrument Shift Check". The transmitter was returned to operability ct 2000 hours on February 17, 1979, removing the unit from the Action Statement of Technical Specification 3.3.2.1. - LER #79-028 1174 059

TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER S'TATION UNIT ONE PAGE 2 SUPPLEMENTAL INFORMATION FOR LER NP-33-79-32 Under Maintenance Work Order (MWO) 79-1603, an investigation of existing permanent heat trace was conducted. MWO 79-1640 was written to correct insulation discre-pancies found. Design problems are being corrected under Facility Change Requests 79-123 and 78-022. Failure Data: There has been one previously reported occurrence of freezing of the BWST level transmitter sensing lines, see Licensee Event Report NP-33-78-01. - LER #79-028 e e e 1174 060}}