ML20027A374

LER 77-089/03L-1:on 771107,radiation Monitor RIS 2007 Was Showing Erratic Readings.Caused by Victoreen Low Range Amplifier Board 847-1-20 Failure.Board Replaced

ML20027A374
Person / Time
Site:	Davis Besse
Issue date:	12/01/1978
From:	Nelson J TOLEDO EDISON CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML20027A371	List: ML20027A370 ML20027A373 ML20027A374 ML20027A375
References
LER-77-089-03L, LER-77-89-3L, NUDOCS 7811210379
Download: ML20027A374 (3)

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Io l 21 l On November 7,1977, at 0130 hours0.0015 days <br />0.0361 hours <br />2.149471e-4 weeks <br />4.9465e-5 months <br /> Radiation Monitor RIS 2007 was discovered shovig This placed the station in the Action i m l erratic readings by Operations personnel. '

The channel was tripped at 0137 I 'l go g4; j Statement of Technical Specification (TS) 3.3.2.1.

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847-1-20. The Low Range Amo11fier Board 847-1-20 within g ; Low Range A=plifier Board I

g g the detector, Victoreen 847-1, was found inoperable and replaced.

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TOLEDO EDISON COMPANY DAVIS-BESSE UNIT ONE NUCLEAR POWER STATION SUPPLEMENTAL INFORv.ATION FOR LER NP-33-77-89 t.

DATE OF FVENT: November 7,1977 ,

e FACILITY: Davis-Besse Unit 1 IDENTIFICATION OF OCCURRENCE: Failure of Radiation Monitor RIS 2007'in Safety Features Actuation System (SFAS) Channel 4 Containment Radiation.

L Conditions Prior to Occurrence: The plant was in Mode 1, with Power (MWT) = 700 and Load (MhT.) = 240.

Description of Occurrence: On November 7, 1977 at 0130 hours0.0015 days <br />0.0361 hours <br />2.149471e-4 weeks <br />4.9465e-5 months <br />, Radiation Monitor RIS 2007 was discovered showing erratte readings by Operations personnel. Opera-tions personnel performed Surveillance Test ST 5099.01, " Miscellaneous Instru-ment Shif t Check", and declared SFAS Channel 4 Containment Radiation inoperable.

This placed the station in the Action Statement of Technical Specification 3.3.2.1.

The channel was tripped at 0137 hours0.00159 days <br />0.0381 hours <br />2.265212e-4 weeks <br />5.21285e-5 months <br /> on November 7,1977 per Technical Specifica-tion 3.3.2.1, Action B. The other three SFAS channels for Containment Radiation were operable at time of incident. .

Designation of Anoarent Cause of Occurrence: The cause of this occurrence was due to a component f ailure, specifically Victoreen Low Range Amplifier Board 847-1-20.

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

or to station personnel. No other systems besides SFAS Channel 4 Containment Rad-Lation was affected except it was then a one out of three trip.

l Corrective Action: Corrective action com=enced on November 7, 1977 at 1200 hours0.0139 days <br />0.333 hours <br />0.00198 weeks <br />4.566e-4 months <br />.

The Low Range Amplifier Board No. 847-1-20 within the detector, Victoreen 847-1 was found inoperable and replaced. RIS 2007 was then calibrated per Surveillance Test ST 5031.04, " Containment Radiation Levels Inputs to SFAS Channel Calibration".

Operations personnel performed ST 5031.01, " Safety Features Monthly Test" at 1100 hours0.0127 days <br />0.306 hours <br />0.00182 weeks <br />4.1855e-4 months <br /> on November 8,1977 and declared the SFAS channel operable, thus removing the station from the Action Statement of Technical Specification 3.3.2.1.

To prevent recurrence and since failure has been inherent to the Low Range Ampli-fier Board in RIS 2007, it was decided to replace the complete detector 847-1.

Upon receiving the new detector from Victoreen on November 10, 1977 at 0000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br />, SFAS Channel 4 Centainment Radiation was tripped per Technical Specification 3.3.2.1 Action 9 to install the new detector. The detector for Radiation Monitor RIS 2007 was replaced and recalibrated per ST 5031.04 t

TOLEDO EDISON COMPANY DAVIS-BESSE C;IT ONE NL' CLEAR POWER STATION SUPPLEIE;TAL INFOPJ!ATION FOR LER NP-33-77-89 PAGE 2 At 1105 hours0.0128 days <br />0.307 hours <br />0.00183 weeks <br />4.204525e-4 months <br /> on November 10, 1977, Operations personnel performed ST 5031.01 and declared SFAS Channel 4 Containment Radiation operable which removed the I station from the Action Statement of Technical Specification 3.3.2.1.

Both the detector and Low Range Amplifier Board were sent to Victoreen.

Analysis revealed excessive voltage leakage on capacitor's C8 and C10. In 1 addition to replacement of both capacitors, a newly designed solid state system has been installed to replace the reed drive system for improved relia-bility.

- 1 Failure Data: Previous incidents occurred on June 7,1977 and October 28, 1977, where the Low Range Amplifier Board had failed on RIS 2007.

1 1

Pav. 1, October, 1978

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