NON-TRACER GAS METHODS TO EVALUATE ISOLATION DAMPER LEAKAGE Peter Lagus, Ph.D., CIH Lagus Applied Technology, Inc Joe Bendyk Exelon Limerick Station NHUG Chicago, Illinois July 2008 LAGUS APPLIED TECHNOLOGY, INCORPORATED

ALTERNATIVE TEST(S) FOR ISOLATION DAMPER LEAKAGE For reconnaissance test we want “simple” go/no-go test Want less expensive and less procedurally intensive test than a tracer gas test Ideally, test to be performed by plant personnel For reconnaissance test, need not have the precision and accuracy needed during inleakage testing. LAGUS APPLIED TECHNOLOGY, INCORPORATED

CRH ISOLATION DAMPERS Occur singly or in pairs within a given ventilation train Provide isolation from unfiltered or normal OS Air intakes Provide isolation of CREVS from adjacent (non-safety) systems Can contribute significant unfiltered inleakage LAGUS APPLIED TECHNOLOGY, INCORPORATED

MAJOR TYPES OF CRH ISOLATION DAMPERS Butterfly Parallel Blade Opposed Blade Expandable Bladder LAGUS APPLIED TECHNOLOGY, INCORPORATED

DAMPER LEAK RATES Bubble-tight damper spec (ANSI N510) implies 0.011 SCFM allowable leakage A 0.01 inch opening between two flat 24 inch damper blades will leak roughly 3-4 SCFM with a 5 in. w.g. differential pressure LAGUS APPLIED TECHNOLOGY, INCORPORATED

DAMPER PAIR LEAKAGE TEST Qleak Interval Volume, V LAGUS APPLIED TECHNOLOGY, INCORPORATED

DAMPER PAIR LEAKAGE TEST Close both dampers and use volume between them as a test chamber Methods based on ANSI N510 Direct Flow Rate Measurement Pressure Decay Measurement Caveat: Testing both dampers simultaneously may INOP the CREVS/CRE. Depends on system design and plant specs LAGUS APPLIED TECHNOLOGY, INCORPORATED

DIRECT FLOW RATE MEASUREMENT Provide measured flow rate at appropriate (low) delivery pressure (usually the System Design dP) Flow for 10 minutes Record flow rate every 30 seconds Compute average flow rate. Required components Compressed air source Delivery regulator Low pressure (pancake) regulator Flow Meter LAGUS APPLIED TECHNOLOGY, INCORPORATED

PRESSURE DECAY METHOD Pressurize volume to 1.25x System Design Pressure Measure pressure decay at 1 minute intervals for 15 min (or until pressure decays to 75% of design value) Measure gas temperature in volume at beginning and end VERY Sensitive to Temperature Changes 1 Deg F dT can cause approx 10% change in calculated flow!! Calculate leakage rate Required components Compressed air source Temperature sensor Pressure sensor Absolute pressure readings are better Pressure readings should be corrected for barometric drift LAGUS APPLIED TECHNOLOGY, INCORPORATED LAGUS APPLIED TECHNOLOGY, INCORPORATED

LEAK RATE CALCULATION Qav=Average Leak Rate (SCFM) Pi,Pf=Initial and Final Pressures (lb/ft2) Ti,Tf=Initial and Final temperatures (Deg R) RA=Gas Constant 53.35 ft-lb/(lb Deg R) dt = time interval (min) LAGUS APPLIED TECHNOLOGY, INCORPORATED

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WHAT ABOUT A SINGLE ISOLATION DAMPER? Previous tests use two dampers to create test volume Works great if neither damper leaks If either damper leaks then need a method to measure flow across each separately Infrequently isolation can be provided by a single damper Very rare Test can be qualitative or semi-quantitative test Use simple test gear No major intrusion into ductwork/damper area Short duration test(s) LAGUS APPLIED TECHNOLOGY, INCORPORATED

SINGLE DAMPER LEAKAGE TESTS Source and Receptor Tests Use smoke, aerosol, visible light as source Use appropriate sensing equipment/element Traverse Tests Use flow through damper opening to detect leak Measure flow directly or measure another characteristic of the flow Feeler Gauge along Sealing Surfaces Need access May affect dP conditions LAGUS APPLIED TECHNOLOGY, INCORPORATED

CAVEATS No warranty implied or expressed Some of the following test techniques/test equipment have not been used in the nuclear industry Some of these test techniques/test equipment are used in other industries to find leakage sites Other test equipment may be more useful or usable than the equipment shown in the following Theoretically all of the following test techniques should be capable of finding a leaking damper LAGUS APPLIED TECHNOLOGY, INCORPORATED

SINGLE DAMPER LEAKAGE TESTS (SOURCE & RECEPTOR TESTS) Smoke Generator plus Borescope (+ light source) DOP Generator plus Light Scattering Photometer Light Source plus Photometer LAGUS APPLIED TECHNOLOGY, INCORPORATED

SINGLE DAMPER LEAKAGE TEST SAMPLE Qleak SOURCE LAGUS APPLIED TECHNOLOGY, INCORPORATED

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LIGHT SOURCE FOR GE BORESCOPE LAGUS APPLIED TECHNOLOGY, INCORPORATED

SMOKE GENERATOR FOR DAMPER TEST LAGUS APPLIED TECHNOLOGY, INCORPORATED

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AEROSOL GENERATORS LAGUS APPLIED TECHNOLOGY, INCORPORATED

LASKIN NOZZLE AEROSOL GENERATOR LAGUS APPLIED TECHNOLOGY, INCORPORATED

VISIBLE LIGHT PHOTOMETER LAGUS APPLIED TECHNOLOGY, INCORPORATED LAGUS APPLIED TECHNOLOGY, INCORPORATED

LED LIGHT SOURCE LAGUS APPLIED TECHNOLOGY, INCORPORATED

SINGLE DAMPER LEAKAGE TESTS (TRAVERSE TESTS) Ultrasonic Probe At 5 in. w.g. differential across at a 24 inch long by 0.01 inch crack the flow velocity is several thousand FPM Probe is “tuned” for air leak frequencies Hot Wire Anemometer Flow Traverse MUST hold anemometer probe perfectly still!! Measurement uncertainty is large, but because of the high sensitivity the measurement shows which damper(s) leaks LAGUS APPLIED TECHNOLOGY, INCORPORATED

ULTRA SONIC PROBE IN USE LAGUS APPLIED TECHNOLOGY, INCORPORATED

ULTRA SONIC PROBE LAGUS APPLIED TECHNOLOGY, INCORPORATED

HOT WIRE TRAVERSE Measure flow at several traverse points Any indication of flow indicates a leak if the probe is stationary Probe MUST be stationary Use Vent Lok with Thermocouple fitting to clamp the probe Hot Wire anemometer exhibits sensitivity as low as 5 FPM. In a 1 ft2 duct this is 5 CFM! LAGUS APPLIED TECHNOLOGY, INCORPORATED

HOT WIRE TRAVERSE TEST VENT LOK WITH SWAGE THERMOCOUPLE FITTING DUCT LAGUS APPLIED TECHNOLOGY, INCORPORATED

HOT WIRE ANEMOMETERS LAGUS APPLIED TECHNOLOGY, INCORPORATED

RECOMMENDATIONS If possible, test dampers pair-wise Careful NOT to INOP System If leakage is unacceptable, then use single damper tests to find out which one (or both) is leaking Single damper tests need not be quantitative since a leak indication is all you are looking for If you find a “leaker” you gotta bite the bullet and fix it. Email Joe Bendyk (joseph.bendyk@exelon.com) at Limerick--ask about borescope and smoke test Email Kevin Fleming (kfleming@ncsc.com)--ask for details about DOP + L. S. Photometer test LAGUS APPLIED TECHNOLOGY, INCORPORATED