ML13014A100

Sprinkler Clogging LaSalle Exelon - Presentation During September 2011 NEI Fire Protection Information Forum

ML13014A100
Person / Time
Site:	LaSalle
Issue date:	09/12/2011
From:	Keller W Exelon Generation Co, Nuclear Energy Institute
To:	Office of Nuclear Reactor Regulation
References
Download: ML13014A100 (13)

Text

Chemistry Lab Pre-action System Clogging Wes Keller September 12, 2011 Background*Chemistry LabDrop CeilingLab Below Ceiling Cables Over Ceiling (Crowded)

Ionization Smoke Detection Above Ceiling Pre-action Spray System (Tray Dedicated)

Pressurized with Air (Standby) 18 Month Surveillance for Flow TestingTested through a single, very accessible nozzleNo specification as to which nozzle(s) to flow test through35 Branch Lines283 Spray Nozzles (250º F Nozzles)

BackgroundAfter Test CompletionThe nozzle is reinstalledSystem is re-pressurized with compressed air. This causes an oxygen-dense environment. The piping in the Overlab System is galvanized, but the high-oxygen atmosphere combined with trapped water is a potentially corrosive environment.

System LayoutFP Water from Deluge ValveBL 19BL 17BL 15BL 13BL 11BL 9BL 7BL 5BL 3BL 2BL 1BL 4BL 16BL 14BL 18BL 20BL 22BL 6BL 8BL 10BL 12BL 29BL 31BL 33BL 30BL 32BL 34BL 24BL 26BL 28BL 21BL 23BL 25BL 27BL 35 Main Header Issue DescriptionOn October 1 st, 2010 at approximately 00:55 Preaction Spray System Function Test in the Chemistry Overlab A Mud like substance blocked all flow through the 1/2" ball valve attached to the hose that routes water to the floor drain during the testSystem was declared inoperable and associated time clocks and compensatory measures were established. A comprehensive investigation was performed for above the lab area and all 35 Branch Lines (BLs) were flushed. BLs 2 and 5 were found to have blockage. A mud like substance was found in BL 2 and a rag was found in BL 5. As an extent of condition Unit 1 and Unit 2 Cable Spreading Rooms and Unit 1 and Unit 2 D/G Corridors were immediately tested in accordance with procedure since they have similar pre-action spray system. No similar issues were found.Equipment Apparent Cause Evaluation (EACE) Performed Issue Description Issue Description Issue Description Sample of Mud-Like SubstanceA sample of the sediment was collected and sent to Powerlabs in Wilmington, IL for elemental

analysis. Powerlabs stated that elemental analysis can be used to determine if the sediment is internal to the

piping system (corrosion) or external to the piping

system (sediment/silt/soil).

Substance FoundNearly a 50/50 split of Zinc Oxide and Iron Oxide Sample of Mud-Like Substance Immediate Corrective ActionsProcedural & PM ChangesEngineering: Provide necessary guidance for system flush plan on a periodic basis to operations department

to revise the procedureProvided a method of performing an entire system flush IAW NFPA 13A Section 5-4.2Method includes flushing the most remote locations in each of the 35 Branch Lines on a periodicity that essentially flushes the entire systemOperations: Revise the procedure as appropriate following guidance given from EngineeringRevision in progress. It is to be implemented prior to the next performance Future ActionsSystem ModificationsLow Point DrainsPressurize the Overlab System with Nitrogen instead of airCompressed air causes a higher Oxygen content to exist in the pipe, leading to accelerated corrosion in the presence of raw waterGuidance from Nexus Engineering suggests that going to Nitrogen will eliminate the need for low point drains and potentially eliminate the need for extensive flushing as prescribed by the EACE Corrective Actions Overlab Flushing Questions?