ML19169A059
| ML19169A059 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 06/13/2019 |
| From: | Laura Smith Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML19169A059 (2) | |
Text
~
- / Exelon Generation June 13, 2019 U.S. Nuclear Regulatory Commission ATIN: Document Control Desk Washington, DC 20555 Calvert Cliffs Nuclear Power Plant, Unit No. 2 Renewed Facility Operating License No. DPR-69 NRC Docket No. 50-318 Larry D. Smith Regulatory Assurance Manager Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, MD 20657 410 495 5219 Office 410 610 9729 Mobile www.exeloncorp.com larry.srnith2@exeloncorp.com TS 3.3.10 and 5.6.7
Subject:
Reactor Vessel Level Monitoring System Special Report, Rev. 1 This revised special report is submitted in accordance with Calvert Cliffs Nuclear Power Plant Technical Specification 3.3.10. The report is required due to the Unit 2 Reactor Vessel Level Monitoring System having less than the required minimum number of operable channels. The initial letter was sent on June 12, 2019.
ACTION TAKEN On May 1, 2019 at 00:10 am the CCNPP Unit 2 Reactor Vessel Water Level Monitoring System {RVLMS),
Channel A experienced a total loss of cabinet power. Calvert Cliffs Technical Specification "Post-Accident Monitoring (PAMS) Instrumentation," section 3.3.10-1 functions 5 and 10 requiring two channels of PAMS to be operable. Because of the subject failure, CCNPP entered Technical Specification 3.3.10, Condition A.
This failure resulted in Channel A being declared inoperable. When the Completion Time of Condition A expired, CCNPP entered Technical Specification 3.3.10, Condition B.l, which requires submission of this report in accordance with Technical Specification 5.6.7.
Functions:
- 10. Pressurizer Pressure (wide range)
PREPLANNED ALTERNATE METHOD OF MONITORING The Reactor Vessel Water Level Monitoring System instrumentation is designated for post-accident monitoring use. It provides the plant operator with information to assess void formation in the reactor vessel head region and the trend of liquid level in the reactor vessel plenum. The Reactor Vessel Water Level Monitoring System consists of two redundant channels. Reactor Vessel Water Level Monitoring Channel B remains operable with all eight of its sensors functioning normally. The removal of Channel A from operable status eliminates a means of redundant indication. Pressurizer Pressures are not developed by the PAMS and serve as inputs into PAMS. PAMS Channel B Pressurizer Pressure input
Document Control Desk June 13, 2019 Page 2 remains operable and alternate Pressurizer Pressure indications are available on the control panels and remote shutdown panels. The alternate methods of monitoring for core and Reactor Coolant System voiding, using pressurizer level, Reactor Coolant System subcooling, hot and cold leg temperature, and core exit thermocouple instrumentation, have been initiated as required by plant procedures.
CAUSES OF INOPERABILITV The cause of inoperability is the failure of channel A RVLMS line filter and bulk 300 VDC power distribution modules. The most probable cause of these failures is age related due to being a run to maintenance system.
PLANS AND SCHEDULES FOR RESTORING THE SYSTEM TO OPERABLE STATUS Calvert Cliffs Nuclear Power Plant performed troubleshooting and determined a blown fuse interrupted the source power to the RVLMS cabinet A. The source power was tagged out and additional troubleshooting with temporary power was performed locally at the cabinet. The HMI computer powered up properly, but each time the power supply chassis was energized it immediately tripped the breaker.
This indicates the line filter and bulk 300 vdc power distribution modules are the cause of the failure. The parts are ordered and expected to be received by June 28, 2019. Repairs will take place once the parts are received.
There are no regulatory commitments contained in this correspondence.
Should you have questions regarding this matter, please contact me at (410) 495-5219.
Respectfully, Regulatory Assurance Manager LDS/MJF/lmd cc:
NRC Project Manager, Calvert Cliffs NRC Regional Administrator, Region I NRC Resident Inspector, Calvert Cliffs D. Tancabel, MD-DNR