NON-TRACER GAS METHODS TO EVALUATE ISOLATION DAMPER LEAKAGE Peter Lagus, Ph.D., CIH Lagus Applied...
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Transcript of NON-TRACER GAS METHODS TO EVALUATE ISOLATION DAMPER LEAKAGE Peter Lagus, Ph.D., CIH Lagus Applied...
NON-TRACER GAS METHODS TO EVALUATE ISOLATION DAMPER
LEAKAGE
Peter Lagus, Ph.D., CIHLagus Applied Technology, Inc
Joe BendykExelon Limerick Station
NHUGChicago, 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
LAGUS APPLIED TECHNOLOGY, INCORPORATED
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
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
LAGUS APPLIED TECHNOLOGY, INCORPORATED
Damper
Qleak
DAMPER PAIR LEAKAGE TESTDamper
Interval Volume, V
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
LAGUS APPLIED TECHNOLOGY, INCORPORATED LAGUS APPLIED TECHNOLOGY, INCORPORATED
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
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
(0.075)dtR
V
T
P
T
PQ
Af
f
i
iAVG
LAGUS APPLIED TECHNOLOGY, INCORPORATED
LEAK RATE vs TIME for PRESSURE DECAY TEST (10 in. wg to 2 in. wg)(Interval Volume in Parenthesis)
0.01
0.10
1.00
10.00
0 2 4 6 8 10 12 14 16 18 20
DECAY TIME (min)
LE
AK
RA
TE
(S
CF
M)
(100 Cu Ft)
(50 Cu Ft)
(75 Cu Ft)
(25 Cu Ft)
(10 Cu Ft)
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
LAGUS APPLIED TECHNOLOGY, INCORPORATED
DAMPER
Qleak
SINGLE DAMPER LEAKAGE TEST
SOURCE
SAMPLE
LAGUS APPLIED TECHNOLOGY, INCORPORATED
LAGUS APPLIED TECHNOLOGY, INCORPORATED
LAGUS APPLIED TECHNOLOGY, INCORPORATED
LIGHT SOURCE FOR GE BORESCOPE
LAGUS APPLIED TECHNOLOGY, INCORPORATED
SMOKE GENERATOR FOR DAMPER TEST
LAGUS APPLIED TECHNOLOGY, INCORPORATED
LAGUS APPLIED TECHNOLOGY, INCORPORATED
AEROSOL GENERATORS
LAGUS APPLIED TECHNOLOGY, INCORPORATED
LASKIN NOZZLE AEROSOL GENERATOR
LAGUS APPLIED TECHNOLOGY, INCORPORATED LAGUS APPLIED TECHNOLOGY, INCORPORATED
VISIBLE LIGHT PHOTOMETER
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LED LIGHT SOURCE
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
LAGUS APPLIED TECHNOLOGY, INCORPORATED
ULTRA SONIC PROBE IN USE
LAGUS APPLIED TECHNOLOGY, INCORPORATED
ULTRA SONIC PROBE
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
LAGUS APPLIED TECHNOLOGY, INCORPORATED
HOT WIRE TRAVERSE TEST
DUCT
VENT LOK WITH SWAGE THERMOCOUPLE FITTING
LAGUS APPLIED TECHNOLOGY, INCORPORATED
HOT WIRE ANEMOMETERS
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 ([email protected]) at Limerick--ask about borescope and smoke test
Email Kevin Fleming ([email protected])--ask for details about DOP + L. S. Photometer test
LAGUS APPLIED TECHNOLOGY, INCORPORATED