ML19340B540

LER 80-075/03L-0:on 801008,steam Generator Level Instrument to Steam & Feedwater Rupture Control Sys Cabinet Channel 3 Maintained 15-inch Error Over Entire Scale.Caused by Zero Shift in Transmitter.Transmitter Being Monitored

ML19340B540
Person / Time
Site:	Davis Besse
Issue date:	11/05/1980
From:	Trautman D TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19340B536	List: ML19340B535 ML19340B540
References
LER-80-075-03L, LER-80-75-3L, NUDOCS 8011110258
Download: ML19340B540 (3)

Text

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D ATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES h Io 12 ] l (NP-33-80-97) On 10/8/80 it was determined by Inctrument and Control personnel that l

[o la l l the Number 1 Steam Generator Level Instrument to Steam and Feedwater Rupture Control l j o 14 l l System (SFRCS) Cabinet Channel 3 maintained a 15 inch error ove r its entire scale. l loIsl l This would have prevented the low level bistable from actuating at the required level.l 1 o is l l The level instrument cabinet channel 3 output was placed in the tripped condition. l Q W lThe station entered the action statement of T.S. 3.3.2.2. There was no danger to the l 6 o la 1 l public or station personnel. The other three channels were operable at the time. I 7 8 9 80 C OE CODE SL8C E COMPONENT CODE SL8C DE SU Q

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CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h lijollThe cause was a zero shift in the transmitter. This caused the entire scale to shift I i 11I lan equivalent 15 inches in level. The cause of this shift is unknown. The transnitted I i 7 I I was checked under WO IC-697-80 and recalibrated under ST 5031.06. The channel was 1 1 [3l l declared operable on October 8,1980 at 2240 hours0.0259 days <br />0.622 hours <br />0.0037 weeks <br />8.5232e-4 months <br />. The transmitter is being moni- 1 U_LJ l tored by ST 5099.01 to detect any further shift. l 7 3 9 gn STA 5  % POWE R oTHER STATUS ISCO Rr OtSCoVERY DESCRtPTION QQ) W@ l0 l 0 l 0 l@l NA l lB l@lSurveillanceTest ST 5099.01 l ACTIVITY CONTENT RELEASED OF RELE ASE AMOUNT of ACTIVITY LOCATION OF RELEASE QW 7 8*9 @ lZ l@l NA 10 11 44 l l NA 45 l

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEYENTAL INFORMATION FOR LER NP-33-80-97 DATE OF EVENT: October 8, 1980 FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: LTSP9B9, level indication for Steam and Feedwater Rup- ,

ture Control System (SFRCS)/ steam generator level instrument cabinet channel 3 read-ing high Conditions Prior to Occurrence: The unit was in Mode 3 with Power (MWT) = 0 and Load (Gross MWE) = 0.

Description of Occurrence: On October 6, 1980 at 1915 hours0.0222 days <br />0.532 hours <br />0.00317 weeks <br />7.286575e-4 months <br /> during the performance of ST 5099.01, Miscellaneous Instrument Shift Checks, operations personnel noted that the Number 1 Steam Generator Level Instrument to SFRCS/ Steam Generator Level Instrument Cabinet Channel 3 was reading high out 'f tolerance at 250 inches. The remaining three SFRCS/ Steam Generator Level Indications for Number 1 Steam Generator indicated 235 inches, 234 inches and 240 inches. On October 8, 1980 at 1535 hours0.0178 days <br />0.426 hours <br />0.00254 weeks <br />5.840675e-4 months <br />, Instrument and Control personnel determined that the signal from level transmitter LTSP9B9 was errone-ous when compared to the remaining three channels and was higher than the signal re-presenting the actual steam generator level. This would have made the steam generator level low level bistable for SFRCS trip at a much lower than desired value if the level indication was correspondingly-high throughout its range of indication. A cali-bration check of the above mentioned transmitter has shown that for an applied differ-ential pressure that ar,,roximately 15 inches of error did exist.

On October 8, 1980 at 1535 hours0.0178 days <br />0.426 hours <br />0.00254 weeks <br />5.840675e-4 months <br /> after determination that the signal from the steam generator level transmitter was shown to maintain a 15 inch error over the entire scale, the SFRCS steam generctor level instrument cabinet channel 3 output was placed in the tripped condition. The station had entered the action statement of Technical Specification 3.3.2.2 which required the inoperable channel to be placed in the tripped condition within one hour af ter the determination. The requirements were met.

l Designation of Apparent Cause of Occurrence: There was a zero shift in the transmitter.

This meant that the entire scalc shifted an equivalent of 15 inches in level. The exact-cause of the zero shift is unknown. -The transmitter is being monitored by observing the four channels and comparing the indicated levels as recorded in ST 5099.01, Miscel-

,laneous Instrument Shift Check.

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Analysis of Occurrence: There was no danger to the health and safety of the public or  !

to station personnel. Three other channels were operable at the time of the occurrence.  !.-

h-I, LER# 80-075 i

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TOLEDO EDISON COMPANY DAVIS-BESSE NUCLEAR POWER STATION UNIT ONE SUPPLEMENTAL INFORMATION FOR LER NP-33-80 PAGE 2 Corrective Action: The transmitter was' checked under Maintenance Work Order IC-697-80 and found to.be out of tolerance. The transmitter was recalibrated under ST 5031.06, Stesa re s.ator Level to SFRCS Refueling Calibration within specification and placed back in service. The channel was declared operable on October 8 at 2240 hours0.0259 days <br />0.622 hours <br />0.0037 weeks <br />8.5232e-4 months <br />. The transmitter is being monitored by ST 5099.01 to detect any further shift.

Failure Data: One previous failure of this type is reported in Licensee Event Report NP-33-80-46 (80-037).

'LER# 80-075 i

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