ML20034G158
| ML20034G158 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 03/03/1993 |
| From: | Gates W OMAHA PUBLIC POWER DISTRICT |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| LIC-93-052, LIC-93-52, NUDOCS 9303090137 | |
| Download: ML20034G158 (3) | |
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Omaha Public Power District P.O. Box 399 Hwy.75-North of Pt.Calhoun Fort Calhoun, NE 680234399 402/636-2000 March 3, 1993 LIC-93-052 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station P1-137 Washington, DC 20555
Reference:
Docket No. 50-285
Subject:
Special Report on Inoperability of Post-Accident Monitoring Instrumentation Gentlemen:
The Omaha Public Power District (OPPD), holder of Operating License DPR-40, submits this report pursuant to the requirements of Fort Calhoun Station Technical Specification (TS) 2.21 " Post-Accident Monitoring Instrumentation."
Technical Specification 2.21, Table 2-10, item 8, note (i) specifies that if the number of operable Core Exit Thermocouples (CETs) is less than four CETs per quadrant as required by NUREG-0737, either restore to at least four CETs per quadrant within seven days or prepare and submit a special report to the Commission pursuant to Technical Specification 5.9.3 within 30 days, outlining the actions taken, the cause of the inoperability and the plans for restoring the CETs to operable status.
The actual number of CETs per quadrant for each channel is shown in Figure 1 of the attachment.
Technical Specification 2.21, Table 2-10, item 9, note (k) specifies that if the number of operaisle Heated Junction Thermocouple (HJTC) channels is one less than the minimum operable channels requirement (two HJTC channels), then OPPD must either restore the inoperable channel to operable status within seven days of discovery of loss of operability if repairs are feasible during power operation (Mode 1), or prepare and submit a special report to the Commission pursuant to Technical Specification 5.9.3 within 30 days outlining the actions taken, the cause of the inoperability and the plans for restoring the HJTC channel to operable status.
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Document Control Desk LIC-93-052 i
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On February 2, 1993, at 0625 hours0.00723 days <br />0.174 hours <br />0.00103 weeks <br />2.378125e-4 months <br /> the channel A Qualified Safety Parameter Display) System (QSPDS) was taken out of service (Channel B QSPDS remained in service for the installation of modification MR-FC-89-082, "QSPDS Communication Priority Change." Thus, the CETs shown for QSPDS Channel A in Figure 1 and one channel of HJTCs were out of service, invoking notes (i) and (k) of TS Table 2-10.
During the post-modification testing on February 4, 1993, eleven thermocouples (ten CETs and one unheated HJTC) did not indicate as expected. As a result of the failure, the system was not able to be restored to service within the TS specified seven days.
To ensure that the modified configuration was not the cause of the unexpected indications, the system was returned to the pre-modification condition. The eleven thermocouples continued to indicate incorrectly. Further troubleshooting revealed a failed communication card, which had a firmware change as part of the modification, was the cause of the erroneous indication. Extreme care was taken I
to prevent static discharge damage to the circuit cards and system power transients (cycling of system power) were kept to a minimum during the l
modification. However, OPPD suspects that the card was operable up to the time i
of the modification and failed as a result of either a static discharge or a power transient during the modification.
The circuit card was replaced and the modification reinstalled. Post-modification testing was completed with satisfactory results. The system was j
declared operable on February 12, 1993 at 1858 hours0.0215 days <br />0.516 hours <br />0.00307 weeks <br />7.06969e-4 months <br />. The seven days specified in notes (i) and (k) of Table 2-10 of the Technical Specifications were exceeded by four days thus requiring this report.
i If you have any questions, do not hesitate to contact me or my staff.
Sincerely,
&5 W. G. Gates Vice President WGG/cfs c:
LeBoeuf, Lamb, Leiby & MacRae S. D. Bloom, NRC Project Manager J. L. Milhoan, NRC Regional Administrator, Region IV R. P. Mullikin, NRC Senior Resident Inspector
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Document Control Desk LIC-93-052 Attachment i
Number of Core Exit Thermocouples Installed in QSPDS Channels A &
B l
i CETs CETs CETs CETs Quadrant 1 Quadrant 2 Quadrant 1 Quadrant 2 4
3 3
4 CETs CETs CETs CETs Quadrant 4 Quadrant 3 Quadrant 4 Quadrant 3 i
3 4
4 3
l i
QSPDS Channel A QSPDS Channel B i
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