BW990042, Forwards Braidwood Station,Unit 1 Post Accident Monitoring Rept for Reactor Vessel Level Indication Sys (Rvlis),Due to Facility Train B RVLIS Being Restored to Operable Status After 7-day Completion Time,Per TS 3.3.3 & 5.6.7
| ML20210A883 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 07/16/1999 |
| From: | Tulon T COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| BW990042, NUDOCS 9907220230 | |
| Download: ML20210A883 (3) | |
Text
Cnmmonw cah h i dison Compan) liraid wom! Generating Station 0
Itoute al, llox 8 6 lirates ille, IL (d00-9619 Tri 815-458 2H01 July 16,1999 Bw990042 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
Post Accident Monitoring Report for Reactor Vesse: >.e"el Indication System Requirements
References:
Letter from T. J. Tulon (Comed) to U. S. NRC, "Pne+ Accident Monitoring Report for Reactor Vessel Level Indication System Req'irements," dated January 27,1999 The reference letter transmitted the Post Accident Monitoring Report for the Braidwood Station, Unit 1, Train A Reactor Vessel LevelIndication System (RVLIS) failed probe. As discussed in that report, the replacement of the failed probe is currently scheduled for May 2000. Subsequent to that report, Braidwood Station, Unit 1, Train B RVLIS was declared inoperable. However, the Braidwood Station, Unit 1, Train B RVLIS was restored to OPERABLE status after the 7-day Completion Time for restoration had been exceeded. As a result, Technical Specifications (TS) 3.3.3, " Post Accident Monitoring (PAM)
Instrumentation, " and TS 5.6.7, " Post Accident Monitoring Report," require the submittal of a Post Accident Monitoring Report. The report provides Braidwood Station's plans for attemate methods of monitoring the reactor vessel level, and the plans and schedule for restoring the system to OPERABLE status.
If you have any questions conceming this matter, please contact Mr. T. W. Simpkin at (815) 458-2801, extension 2980.
Respectfully,,
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T. J. Tulon Vice President I
Braidwood Nuclear Station iX <
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220013 TJT/DC/dah
Attachment:
Braidwood Station, Unit 1, Post Accident Monitoring Report for Reactor Vessel level Indication System (RVLIS)
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NRC Project Manager-NRR - Braidwood and Byron Stations Nicholas Reynolds-Winston & Strawn Office of Nuclear Facility Safety-IDNS Site Vice President - Braidwood Station Regulatory Assurance Manager-Braidwood Station Director, Licensing and Compliance - Braidwood and Byron Stations Comed document Control Desk Licensing (Hard Copy)
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BRAIDWOOD STATION, UNIT 1 POST ACCIDENT MONITORING REPORT FOR REACTOR VESSEL LEVEL INDICATION SYSTEM (RVLIS)
Cause of Inoperability Braidwood Station, Unit 1, Train B Reactor Vessel Level Indication System (RVLIS) was declared inoperable on June 25,1999, due to erratic indications for reactor vessel level.
Resistance checks were conducted of wiring to the Train B RVLIS probe with satisfactory readings. Additional testing by the vendor confirmed that Train B RVLIS probe did not experience a similar failure as the Train A RVLIS probe previously reported in the letter from T.J. Tulon (Comed) to U.S. NRC, " Post Accident Monitoring Report for Reactor Vessel Level Indication System Requirements," dated January 27,1999. Braidwood Station personnel, with vendor assistance, determined that the problem was in the electronics. Replacement of printed circuit boards in tho electronics restored the Train B RVLIS Thermal Couple (TC) readings to normal. On July 9,1999, Train B RVLIS was declared OPERABLE and Technical Specification 3.3.3, " Post Accident Monitoring (PAM) Instrumentation," Condition E, was exited, leaving only Train A RVLIS inoperable. During the period Train B RVLIS was inoperable the alternate methods used for rnonitoring were the same as those identified and still being used for Train A RVLIS.
Alternate Methods of Monitorina NUREG-0696, " Functional Criteria for Emergency Response Facilities," is the basis for the selection of parameters for the Safety Parameter Display System (SPDS) which facilitates an operator's assessment of plant status. Appendix E of the Braidwood Station Updated Final Safety Analysis Report (UFSAR), Table E.17-3, identifies RVLIS as one of several SPDS parameters used to monitor Reactor Coolant System (RCS) inventory. This table compares the SPDS safety functions and parameters with NUREG-0696, NUREG-0737, " Clarification of TMI Action Plan Requirements," Supplement 1, and Westinghouse Critical Safety Functions.
RVLIS, in conjunction with other parameters, e.g., pressurizer level, net charging / letdown flow and containment floor drain sump level, adequately monitors RCS inventory.
RVLIS is used in the Braidwood Emergency Operating Procedures (EOPs) to support three functions. These functions are: (1) to confirm that voids are not present in the Reactor Vessel Upper Head region and, therefore, that the reactor vessel is full, (2) to determine that the bulk liquid level is greater thar the top of the hot legs, and (3) to determine that the bulk liquid level is greater than the top o; the active fuel region. The Braidwood Station EOP network also includes BwEP ES-0.4 " Natural Circulation Cooldown with Steam Void in Vessel without RVLIS," to address nuural circulation cooldown when RVLIS is unavailable. In addition, with RVLIS unavailable, C ore Exit Thermocouples and RCS subcooling are used to determine that the core is covered.
Plans and Schedule Train B RVLIS was returned to service on July 9,1999.