ML20210S390

Special Rept:On 860624,performance of Surveillance Test on Triaxial Response Spectrum Analyzer (Trsa) Indicated That Unit Inoperable.Caused by 240-ohm Resistors Overheating. Defective Amplifier Replaced.Related Correspondence

ML20210S390
Person / Time
Site:	Limerick
Issue date:	09/29/1986
From:	Leitch G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC
To:	Murley T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
CON-#486-0995, CON-#486-995 OL, NUDOCS 8610080118
Download: ML20210S390 (4)

Text

- - - - . - - -

e .. -.

yww.cofatsPONDENCt PHILADELPHIA ELECTRIC COMPAgCKETED 2301 MARKET STREET USNRC P.O. BOX 8699 PHILADELPHI A. PA.19101 '86 T -6 P1 :19 42 m a4 w ooo ' Sep rg 29, 198p 00CKEliNG A U PiiCF gocket nee A 50-352/313'#p J

Dr. Thomas E. Murley, Administrator Region I E.

U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 19406

SUBJECT:

Special Reporting Requirement for Inoperable Seismic Monitoring at Limerick Generating Station Supplemental Report

REFERENCE:

Technical Specification 3.3.7.2 and 6.9.2

Dear Dr. Murley:

This supplemental report is being submitted to provide additional information concerning the Cause of Event and Corrective Actions of the Special Report which was submitted on

!. July 11, 1986.

The special report was submitted pursuant to the requirements of Limerick Technical Specifications 3.3.7.2 and 6.9.2 which state:

SEISMIC MONITORING INSTRUMENTATION:

3.3.7.2 The seismic monitoring instrumentation shown in

!- table 3.3.7.2-l* shall be OPERABLE.

APPLICABILITY: At all times.

ACTION:

a. With one or more of the above required seismic monitoring instruments inoperable for more than 30 days, prepare and submit a Special Report to the Commission pursuant to Specification 6.9.2 within 228 860929 gj00gOCK05000352 S

[ 3 03

_ _ _ - _ - ------- . - . I

(- .

Dr._ Thomas E. Murley September 29, 1986 Page 2

, the next 10 days outlining the cause of the malfunction and the plans for restoring the instrument (s) to OPERABLE status.

I SPECIAL REPORTS 6.9.2 Special reports shall be submitted to the Regional Administrator of the Regional Office of the NRC within the time period specified for each report.

DESCRIPTION OF EVENT:

. On June 24, 1986 with the unit at power, the semi-annual surveillance test for the Triaxial Response Spectrum Analyzer (TRSA) was performed. The TRSA analyzes data from Triaxial Time-

• History Accelerographs and provides acceleration values for a range of frequencies (0-33.5 HZ). The surveillance test revealed that the unit was inoperable. The TRSA is a Model No. 505N1 manufactured by M/ RAD Corporation.

i CONSEQUENCES OF THE EVENT:

The consequences of this condition are minimal. The control room will continue to receive notification of a seismic event because the control room annunciators receive signals from components of the seismic monitoring system which are operable. The function of the TRSA is to analyze the recorded accelerations from various plant locations and generate a peak acceleration versus frequency

! curve. With the TRSA inoperable, the acceleration data, which is recorded on magnetic tape, can be sent off-site for analysis by another TRSA.

CAUSE OF EVENT:

The manufacturer of the TRSA, M/ RAD Corporation, determined that the failure of the TRSA was the result of the 240-ohm resistors overheating and excessive voltage offset in an amplifier.  :

CORRECTIVE ACTION:

The TRSA was sent to the manufacturer for inspection and analysis, The manufacturer removed the 240-ohm resistors and relocated them in order to provide for more adequate ventilation so that the heat radiating from the resistors could be better dissipated. The defective amplifier was replaced and the TRSA

Dr. Thom:0 E. Murley September 29, 1986 Page 3 was re-calibrated. The TRSA was re-installed and declared operable on September 22, 1986.

PREVIOUS SIMILAR OCCURRENCES:

A revised special report concerning inoperable seismic monitoring equipment (TRSA), resulting from a different cause, was submitted on July 15, 1985.

Should you require additional information, please do not hesitate to contact us.

V y tru) yours, a

G. M. Leitch Superintendent Nuclear Generation Division cc: E. M. Kelly, LGS Resident Site Inspector See Attached Service List I

i l

l l

l l

l

_ _ .- ~_ n

cc: Troy B. Conner, Jr., Esq.

Benjamin H. Vogler, Esq.

Mr. Frank R. Romano Mr. Robert L. Anthony Ms. Maureen Mulligan Charles W. Elliott, Esq.

Barry M. Hartman, Esq.

Mr. Thomas Gerusky Director, Penna. Emergency Management Agency Angus Love, Esq.

David Wersan, Esq.

Robert J. Sugarman, Fsq.

Kathryn S. Lewis, Esq.

Spence W. Perry, Esq.

Jay M. Gutierrez, Esq.

Atomic Safety & Licensing Appeal Board Atomic Safety & Licensing Board Panel Docket & Service Section (3 Copies)

E. M. Kelly Timothy R. S. Campbell July 21, 1986 l

l t _ _ _