ML020520179
| ML020520179 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 02/15/2002 |
| From: | Katz P Constellation Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML020520179 (3) | |
Text
Peter E. Katz Plant General Manager 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 410 495-4101 Constellation I
Nuclear Calvert Cliffs Nuclear Power Plant A Member of the Constellation Energy Group February 15, 2002 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
SUBJECT:
Document Control Desk Calvert Cliffs Nuclear Power Plant Unit No. 2; Docket No. 50-3 18 Special Report - Unit 2 Reactor Vessel Level Monitoring System The attached special report is submitted in accordance with Calvert Cliffs Nuclear Power Plant Technical Specification 3.3.10. The report is required due to the inoperability of both Channels A and B of the Unit 2 Reactor Vessel Level Monitoring System for a period in excess of seven days.
Should you have questions regarding this matter, we will be pleased to discuss them with you.
Very truly yourS, PEK/MJY/bjd
Attachment:
(1) Unit 2 Reactor Vessel Level Monitoring System Special Report cc:
R. S. Fleishman, Esquire J. E. Silberg, Esquire Director, Project Directorate I-1, NRC D. M. Skay, NRC H. J. Miller, NRC Resident Inspector, NRC R. I. McLean, DNR
ATTACHMENT (1)
UNIT 2 REACTOR VESSEL LEVEL MONITORING SYSTEM SPECIAL REPORT Calvert Cliffs Nuclear Power Plant, Inc.
February 15, 2002
ATTACHMENT (1)
UNIT 2 REACTOR VESSEL LEVEL MONITORING SYSTEM SPECIAL REPORT Calvert Cliffs Nuclear Power Plant, Inc. (CCNPP) submits this special report concerning the inoperable Channels A and B of the Unit 2 Reactor Vessel Level Monitoring System (RVLMS). This special report is required by Technical Specification 3.3.10, Condition G, Required Action G. 1.
ACTION TAKEN On January 29, 2002, at approximately 0200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br />, the CCNPP Unit 2 RVLMS Channel B experienced a failure of the 29-inch and 71-inch level sensors. This failure, coupled with a previous failure of the 10-inch level sensor resulted in Channel B being declared inoperable due to insufficient sensor positions available in the lower (plenum) region.
Calvert Cliffs Updated Final Safety Analysis Report, Section 7.5.9.2, "Reactor Vessel Level Monitoring System," requires one of the upper three (vessel head region) and three of the lower five (plenum region) sensors for operability of each RVLMS Channel.
Since Channel A had been previously declared inoperable in November of 2001, CCNPP immediately entered Technical Specification 3.3.10, Condition G.
EFFECT ON OPERATION The RVLMS is post-accident monitoring instrumentation.
It provides plant operators with the information needed to assess void formation in the reactor vessel head region and trend data for liquid level in the reactor vessel plenum.
However, alternate methods of monitoring for core and Reactor Coolant System voiding, using pressurizer level, Reactor Cooling System subcooling, hot leg and cold leg temperature, and core exit thermocouple instrumentation, have been initiated as required by plant procedures.
CAUSES OF INOPERABILITY The cause of inoperability is the failure of three heated junction levels in the lower five sensors. A Root Cause Analysis (RCA) is currently in progress. The entire RVLMS is under examination as a result of the RCA, including signal processing equipment.
PLANS AND SCHEDULES FOR RESTORING THE SYSTEM TO OPERABLE STATUS Multiple corrective action activities are underway to confirm and/or resolve the possible causes identified in the RCA.
A program of refurbishments and modifications is in place with vendor support (Westinghouse) to enhance signal conditioning and noise suppression. The Unit 2 RVLMS Channel B will be repaired or replaced prior to entering Mode 3 following the Unit 2 2003 Refueling Outage.
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