ansi n13.1 stack sampling system design...

ANSI N13.1Stack Sampling System

Design Comparison2014 RETS/REMP Workshop

Brian AsamotoHI-Q Environmental Products Company, Inc.

June 23-26, 2014

Nuclear Facility Licensing Requirements

• 10CFR50 – Domestic Licensing of Productionand Utilization Facilities

• Exception to 10CFR50 Applies to USGovernment Production or Utilization Facilities

PROPRIETARY INFORMATION

Air Emissions vs. Effluent ReleaseRequirements

• 10CFR50 – Commercial Nuclear Power Plant Licensing Standard

• 40CFR61 – Hazardous Air Pollution Standard

• ANSI N13.1 - Sampling and Monitoring Releases of AirborneRadioactive Substances from Stacks and Ducts

– ANSI N13.1-1999/2011 applies to government DOD/DOEfacilities

– The NRC has not required operating commercial nuclear powerplants to upgrade to 1999/2011. New construction may berequired to comply with the 1999/2011 version.


Comparison 1969 vs. 1999• 1969 standard defined method of meeting

standard– Defines sampling location

– Requires specific number of sample nozzles

– Defines how to obtain samples representative of theduct particulate distribution

– Little guidance on calculating sample transport systemparticulate deposition

– Recommends verification of fully developed flow andcomplete mixing at sample location


Comparison 1969 vs. 1999• 1999 standard defined performance criteria for

meeting standard– Defines characteristics of the sampling location

• Velocity Profile

• Angle of Velocity Vector

• Tracer Gas Concentration Profile

• Maximum and Minimum Tracer Gas Concentration

• Aerosol Particle Concentration Profile

• Scale model testing can be used in lieu of in-situtesting


Comparison 1969 vs. 1999• 1999 standard provided recommendation for

particle transport efficiency• 1999 standard discourages the use of isokinetic

sampling arrays– Constant cross-section sample nozzles have

significant loss of particles

– Large number of small diameter nozzles increases theparticle losses in the sampling arrays

• 1999 standard suggests the use of a single pointprobe at a representative sample location


Example of Shrouded Probe


Sample Characteristics of a ShroudedProbe


Isokinetic Sampling Array vs.Shrouded Probe

• Constant cross-section isokinetic nozzle hassignificant wall losses

• Validation testing of isokinetic sampling arraysare recommended

• Shrouded probe has an aerosol transmissionratio within the range of 0.80 to 1.30 ductoperating flow rate


Isokinetic Sampling Array vs.Shrouded Probe

• Shrouded probes perform satisfactorily forvariations in stack conditions:– Velocity– Flow rate– Free stream turbulence– Angle between the free stream and nozzle entrance

• Both require stack sample location testing


Stack/Duct Design Considerations

• Stack/duct design has critical affect on samplerepresentativeness

• Locating representative sample extraction planeis not always intuitive

• All current acceptance criteria may not be easilymet at the selected sample extraction plane

• Gas mixing techniques may improverepresentativeness


Examples of Tested Stack/duct Designs

• Department of Energy Facility Exhaust Stack• Columbia Generating Station Elevated Vent• AP1000 Plant Vent• AP1000 Control Room Ventilation Duct


Test Methodology

• Velocity profile test• Swirl angle test• Tracer gas concentration profile test• Maximum and minimum tracer gas concentration

evaluation• Aerosol particle concentration profile test


DOE Facility Qualified Sample Location


Columbia Generating Station

• Energy Northwest• Richland, WA• General Electric Boiling

Water Reactor• Mark II Containment• 3,486 MWt


Key Elements of the ElevatedVent Stack Design

• Normal operation – Reactor Building HVAC Duct• Post-accident operation – Standby Gas

Treatment (SGTS) Duct• Existing stack sampling system

– Flow straightener section– Self-averaging pitot tube array– Correction of flow rate to standard conditions– Multipoint isokinetic sampling array

• SGTS Air Exhausts Through Internal Duct


Stack Sampling System Design Basis• ANSI N13.1-1969 used for original design criteria• Normal and post-accident flow rates will be used

for ANSI N13.1-1999 test criteria• Test was conducted on scale model of the stack

and inlet ducts• Testing was conducted with and without flow

straightener• Replace multi-point sample array with shrouded

probe• Eliminate flow straightener


Elevated Vent Stack Configuration


72” Reactor Building HVAC Duct

671’2”4’ X 10’ Elevated Release

2 x 18” SGTS Ducts

ReactorBuilding

TurbineBuilding

4’

582’7”

648’8”Flow Conditioning,Measurement and StackSampling Station

595’8”606’10”

SGTS Duct Configuration


72” Reactor BuildingHVAC Duct

606’10”20” X 20” StackOpen at both ends

2 x 18” SGTS Ducts

582’7”

Scale Model Configuration


Scale Model


SGTS Stack


Test Performance

• Minimum Reactor Building HVAC Duct flow rate• Maximum Reactor Building HVAC Duct flow rate• Minimum SGTS Duct flow rate (Two ducts)• Maximum SGTS Duct flow rate (Two ducts)• Tests repeated without flow straightener


Test Results

• Test results for normal operation• Test results for post-accident operation• Test results without flow straightener• Particle uniformity test was not repeated for post-

accident operation without flow straightener


Normal Operation Velocity Profile


With Flow Straightener Without Flow Straightener

COV=9.3% COV=9.1%fpm = feet per minute

x,1

x,2

x,3

x,4

150016001700180019002000210022002300

1,y 2,y 3,y 4,y

fpm

Flow Direction x,1

x,2

x,3

x,4

160017001800190020002100220023002400

1,y 2,y 3,y 4,y

fpm

Flow Direction

Normal Operation Tracer Gas Uniformity



COV=10.1% COV=8.2%

ppm = parts per million

x,1

x,2

x,3

x,4

0.900.951.001.051.101.151.201.251.30

1,y 2,y 3,y 4,y

ppm

Flow Direction x,1

x,2

x,3

x,4

3.5

3.7

3.9

4.1

4.3

4.5

4.7

4.9

1,y 2,y 3,y 4,y

ppm

Flow Direction

Normal Operation Particle Uniformity



COV=11.4% COV=5.4%cpm = counts per minute

x,1

x,2

x,3

x,4

260280300320340360380400420

1,y 2,y 3,y 4,y

cpm

Flow Direction x,1

x,2

x,3

x,4

300

310

320

330

340

350

360

370

1,y 2,y 3,y 4,y

cpm

Flow Direction

Post-accident OperationVelocity Profile



COV=19.1% COV=38.3%fpm = feet per minute

x,1

x,2

x,3

x,4

0

20

40

60

80

100

1,y 2,y 3,y 4,y

fpm

Flow Direction x,1

x,2

x,3

x,4

40

60

80

100

120

140

1,y 2,y 3,y 4,y

fpm

Flow Direction

Post-accident OperationTracer Gas Uniformity



COV=11.5% COV=6.4%ppm = parts per million

x,1

x,2

x,3

x,4

0.6

0.7

0.8

0.9

1.0

1.1

1,y 2,y 3,y 4,y

ppm

Flow Direction x,1

x,2

x,3

x,4

1.0

1.1

1.2

1.3

1.4

1,y 2,y 3,y 4,y

ppm

Flow Direction

Post-accident OperationParticle Uniformity


With Flow Straightener

COV=4.7%

x,1

x,2

x,3

x,4

1.001.051.101.151.201.251.301.351.40

1,y 2,y 3,y 4,y

cpm

Flow Direction

cpm = counts per minute

AP1000 Nuclear Power Plant

• Westinghouse Electric• Vogtle 3 and 4• V. C. Summer 2 and 3• Generation III+ Reactor• Passive Reactor Design• 3,415 MWt• 1,110 MWe


Plant Vent Design• Normal Operation

– Aux/Annex Building Exhaust (2 sources)– Fuel Handling Area Exhaust (2 sources)– Containment Air Filtration Exhaust– Health Physics & Hot Machine Shop Exhaust– Radwaste Building Exhaust

• Post-accident Operation – Containment AirFiltration Exhaust

• Stack Sampling System– Normal operation sampling by shrouded probe– Post-accident operation sampling by single isokinetic

nozzle


Plant Vent Scale Model Configuration


Scale Model Design

• Model scale is 1:5• Plant vent and four inlet ducts were modeled• Five fans controlled the air flow through the four

inlet ducts• Correct flow rates required balancing each fan’s

output


Scale Model


Turning Vanes


Test Results

• Velocity Profile COV – Pass• Swirl Angle - Pass• Tracer Gas Concentration COV – Pass• Maximum Variation from Tracer Gas Mean

Concentration – Pass• Aerosol Particle Concentration Profile COV - Pass


Control Room Ventilation DuctScale Model Configuration


Scale Model Design

• Model scale is 1:2.33• Tracer gas and aerosol particle injected at fan

outlet• Turning Vanes• Balancing Damper• Gas blender was required to pass velocity profile

COV


Scale Model


Balancing Damper


Gas Blender


Test Results


• Velocity Profile COV – Fail (without gas blender)• Swirl Angle - Pass• Tracer Gas Concentration COV – Pass• Maximum Variation from Tracer Gas Mean

Concentration – Pass• Aerosol Particle Concentration Profile COV - Pass

Conclusions

• Vent stacks should be designed for mixing andflow uniformity at sampling location

• Longer straight run improves mixing and flowunifority

• High probability for successful test results withnon-ideal stack/duct designs


Conclusions

• Mixing and flow uniformity problems havesolutions

• Reasonable representativeness possible withANSI N13.1-1969 design

• Compliance with ANSI N13.1-1999 enhances therepresentativeness of the particulate sample


ansi n13.1 stack sampling system design...

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