dry filter method (dfm) containmentdry filter method (dfm ...aerosol filter (deep bed metal fiber...

© 2012 Westinghouse Electric Company LLC. All Rights Reserved.Westinghouse Proprietary Class 3

Dry Filter Method (DFM) ContainmentDry Filter Method (DFM) Containment Venting System

Presentation to U.S. NRC, Washington DCOctober 11, 2012

Daniel FreisDaniel Freis

Westinghouse Electric Company

[email protected]

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Presentation OverviewPresentation Overview

1 Dry Filtered Method Description1. Dry Filtered Method Description

2. Design Characteristics

3. Qualification

4 Advantages of the Dry Filter Method4. Advantages of the Dry Filter Method

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Dry Filter Method ApplicationDry Filter Method Application Outlet Duct Inlet Piping

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Filtered Venting of the ContainmentThe Dry Filter MethodThe Dry Filter Method

Two major passive filter components:● Aerosol Filter (deep bed metal fiber filter)

removal of solid particles (aerosols) – e.g., CsI, CsOH● Iodine Sorption Filter (molecular sieve)

R l f l t l i di I Removal of elemental iodine – I2 Removal of organic iodine – CH3I

T i t f th d filt th d h b lifi d fTwo variants of the dry filter method have been qualified for use in Germany:● Iodine Sorption filter is always outside of the containment (short lived I-131)

A l filt i id t i t● Aerosol filter inside containment -OR-

● Aerosol filter outside containment (combined aerosol and iodine filter)

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References and History of the DFMReferences and History of the DFMThe DFM was the first methodology for filtered venting of the containment of aerosols and elemental / organic iodine developed in Germany by YIT, with participation of Karlsruhe Institute of Technology and RWE (Utility):

● DFM with aerosol filter inside containment installed in PWRs: – Biblis A (RWE)( )– Biblis B (RWE)– Mülheim-Kärlich (RWE)

● DFM with aerosol filter outside containment installed in PWRs:● DFM with aerosol filter outside containment installed in PWRs: – Brokdorf (E.ON)– Grohnde (E.ON)– Unterweser (E.ON)( )– Stade (E.ON)

Westinghouse and YIT have an exclusive cooperation agreement for supply of DFM systems worldwide

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systems worldwide.


Dry Filter Method Aerosol Filter inside ContainmentAerosol Filter inside Containment

Valves

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Dry Filter Method Aerosol Filter inside ContainmentAerosol Filter inside Containment

Deep Bed Metal Fiber filter (aerosol filter located in the containment)

Aerosol Filter Unit

1 D l t t1 Droplet seperator2, 3 Pre Filter Stage4 Aerosol Filter

Stage5 Exhaust Pipe6 Inlet

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6 Inlet


The Dry Filter Method Aerosol Filter inside ContainmentAerosol Filter inside Containment

Iodine filter (molecular sieve filter located outside containment)

Iodine Filter Unit

1 Inlet Duct 2, 3 Inlet Chamber4 Iodine Filter Stage5 Exhaust Duct

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The Dry Filter Method Aerosol Filter outside ContainmentAerosol Filter outside Containment

Flow Control Valves

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Dry Filter Method Aerosol Filter outside ContainmentAerosol Filter outside Containment

Combined Filter consists of several modules

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3. Qualification


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DFM Working Principle / Aerosol FilterDFM Working Principle / Aerosol Filter

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Loading and Melting Test with CsOH at Mallersdorf (performed by WEC)at Mallersdorf (performed by WEC)

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DFM Working Principle / Aerosol FilterDFM Working Principle / Aerosol Filter

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Design Aspects of Aerosol FilterParticle Filter PrinciplesParticle Filter Principles

BLOCKINGFl

INTERCEPTION

Particle Trajectory

Flow Streamline

FIBRE

Flow Streamline

Particle Trajectory

FIBRE

FIBREParticle

Trajectory

IMPACTIONBROWNIAN DIFFUSIONFlow

Streamline

Particle

Particle Trajectory

Flow Streamline

Particle Size

FIBRETrajectoryFIBRE

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Design Aspects - Aerosol FilterDesign Aspects - Aerosol Filter● The aerosol filters are sized to allow required mass flow during the whole

venting process to preclude clogging with large marginventing process to preclude clogging with large margin.

● The effective filter area of the aerosol filter is designed for the specified aerosol loading.

● The aerosol filters are designed to meet the decay heat loading of the filtered material.

● Design for aerosol retention efficiency > 99 99 % or DF >10 000 for particles● Design for aerosol retention efficiency > 99.99 % or DF >10,000 for particles with AMMD of ~ 0.15 µm

● The designed retention efficiency of the aerosol filter is > 99.99 % for the h l ti (St t / E d f ti )whole venting process (Start / End of venting).

● Each filter is tested in the manufacturing by independent third party.

● Best estimate efficiency for aerosol retention is > 99 9999 % or DF > 1E06

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● Best estimate efficiency for aerosol retention is > 99.9999 % or DF > 1E06.


The Dry Filter Method Manufacturing Tests of Aerosol FiltersManufacturing Tests of Aerosol Filters

Test of removal efficiency with Uranine by Third Party (TÜV) at YIT test facility

Production Control tests with UranineProduction Control tests with UranineUse of Uranineconservative

results*

* „NAUA“ aerosol: a similar particulate size distribution isparticulate size distribution is anticipated in core meltdown accidents (result of computations made at FZK (KIT))

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Design Aspects – Enhancements since Application in German ReactorsApplication in German Reactors

● Passive natural convection cooling tubes have been added to increase decay heat removal capability significantlyincrease decay heat removal capability significantly

● Separation of pre-filter stages from 2 to 4 to improve heat removal by heat conduction and radiation (individual filter pads are thinner y ( pnow and have increased surface area)

● Use of ceramic tube wall coating to improve heat transport by heat ( )radiation (increased emissivity)

● A passive orifice to reduce pressure and increase superheat of vent flow entering the iodine filter has replaced an active valveflow entering the iodine filter has replaced an active valve

● Actuation and process control are completely passive and robust and don´t need any supporting systems or media

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Improved Decay Heat RemovalAerosol Filter Module Top ViewAerosol Filter Module Top View

Cooling tubeCooling tube

Increased number of pre-filter stages (4 instead of 2)• Thinner filter pads• More surface available for heat removal• More cooling tubes available

Fine filter is integrated in central module

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Dry Filter Method - Decay Heat Removal with Passive Natural Convectionwith Passive Natural Convection

● Use of passive natural convection cooling tubes

● Decreased bed depth and increased surface area by separation of filter stages

● Increased emissivity of tube walls

● All single effects have been tested and an integral full scale test● All single effects have been tested and an integral full scale test has been performed

● Also confirmed temperature resistance of materials under severe● Also confirmed temperature resistance of materials under severe accident conditions

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DFM for Filtered Venting of the ContainmentWorking Principle Iodine Filter

Zeolite of the iodine filter: Basic structure of zeolite:

Working Principle – Iodine Filter

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Design Aspects / Organic Iodine FilterDesign Aspects / Organic Iodine Filter

● Zeolite is doped with silver. Silver reacts with elemental and organic iodine to silver iodide.

● Retention efficiency is dependent on the residence time and the distance to the dew pointdistance to the dew point

● The effective filter area and bed depth of the zeolite are designed to meet the retention requirements for elemental and organic q giodine during the whole venting process

● The iodine filter is designed to meet the decay heat requirements

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Iodine Retention Efficiencies for CH3I / Function of Residence Time and Dew Point Distanceof Residence Time and Dew Point Distance

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DFM Working Principle / Adiabatic Expansion (constant enthalpy)Expansion (constant enthalpy)

Gas mixturePressure: 5 barabsTemperature: 133.5 °CExpansion to: 1.05 barabsSteam: 60 % of volume

(h = const.)

Т = 133.5 °C

Ppartial = 3.3 bar

x = 1x 1

(h ~ constant, heat losseshave to be considered)

Ent

halp

y

Т = 121.4 °C

Ppartial = 0.63 bar

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gas mixture issuperheated with 34 K

Entropy


DFM - OperationDFM - Operation ● Always standby and ready for immediate use, no action needed

f fbefore actuation of venting ● Air cooled by natural convection ● Sized to be passive for extended period● Sized to be passive for extended period● No operator action required● No supporting systems needed● No electricity needed● No chemicals or water supply needed

St id ti f t d d ti i d● Storage consideration for extended time period

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DFM - Completely Passive OperationDFM - Completely Passive Operation

• Passive actuation with rupture disc possiblePassive actuation with rupture disc possible

• Passive process control via expansion orifice

• Controls flow rateControls flow rate

• Controls dew point distance

• Controls iodine filter efficiency• Controls iodine filter efficiency

• No active components

• No auxiliary systems• No auxiliary systems

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Completely Passive OperationRobust Process ControlRobust Process Control

Decreasing dew point distance and decreasing mass flow compensateeach other. The efficiency stays constant during the whole venting process.eac ot e e e c e cy stays co sta t du g t e o e e t g p ocess

Filter efficiency (without dimension)

Dew point distance (without dimension)

Residence time (without dimension)

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Containment pressure (bar abs)





3. Qualification


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The Dry Filter Method - Qualification of the DFM -- Qualification of the DFM -

● Test of removal efficiency with Uranine (AMMD ~ 0.15 µm) as test laerosol

(each filter is tested)

● Loading tests with SnO2 as test aerosol at Battelle Europe, Frankfurt

● Loading tests with BaSO4 micro and other test aerosols at Nuclear Research Center Karlsruhe (today KIT)Research Center Karlsruhe (today KIT)

● Loading and removal efficiency tests with CsOH as test aerosol at Cadarache

● Loading and melting tests with CsOH performed by WEC and YIT

● ACE test (international reference test for venting systems)

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● Removal efficiency test of the molecular sieve “zeolite” by KfK(KIT) TÜV E h d ti b t h i t t d(KIT) or TÜV. Each production batch is tested.

● The function of the filtering technique was confirmed by repeated testing in the individual NPPs where they are installed. There is no degradation.

● Zeolite was tested successfully in PHEBUS FB tests in Cadarache.

R di ti t t f ll f d t KfK d S h● Radiation tests were successfully performed at KfK and Savannah River Laboratories.

● In addition, startup, aging and recombination tests were p g gsuccessfully performed in extensive studies.

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International ACE TestMetal fibre filter performanceMetal fibre filter performance

Decontamination Factors – 40 % Steam● Cs (CsOH & CsI): 1 6 E6 (Best test result)● Cs (CsOH & CsI): 1.6 E6 (Best test result)● I (CsI): 3.0 E5 (Second best test result*)● Mn (MnO): > 2.0 E6 (Best test result)

Decontamination Factors – Non Condensable Gas● Cs (CsOH & CsI): > 3.0 E6 (Best test result)● I (CsI): 6.0 E4 (Second best test result*)● Mn (MnO): > 8.0 E5 (Best test result)

Decontamination Factors – DOP/DOS Tests● Flow rate 0.044 m³/s DF 50,000 (Best test result)● Flow rate 0.088 m³/s DF 50,000 (Best test result)

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, ( )

* A small fraction of CsI decomposed to elemental iodine. Since only the aerosol filter without iodine filter was tested, this affected the total filter performance for iodine.


DFM Prevention of CloggingDFM – Prevention of Clogging

● Filter sizing is based on severe accident analysis (conservative determination of expected aerosol load)

● Filter dimensioning is based on experimental results with different ti t t lconservative test aerosols

● Sized with substantial margin to clogging

– Large margin between expected pressure drop and mechanically acceptable pressure drop

– Large margin between expected aerosol load and tested aerosol loadLarge margin between expected aerosol load and tested aerosol load

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Loading tests with SnO2 at Battelle Europe (I t i t d i )(In-containment design)

Use of SnO2 ticonservative

results

Mechanicallyec a ca yallowed pressuredrop is far higher(outside of diagram)Design area

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Radiation Resistance of ZeoliteRadiation Resistance of Zeolite● Radiation tests at Nuclear Research Center Karlsruhe (former KfK today

KIT)KIT) – Material was radiated and filter efficiency was tested afterwards– Resistance to extremely high radiation dose (no degradation or othe

effects were observed)effects were observed)– No effect on performance– Tests were performed with up to 8.6 E06 Gray (8.6 E08 Rad)

● Radiation tests at Savannah River Laboratory (U.S.)– Filter was tested for efficiency during high dose rate radiation– Radiation dose rate: 2.6 E05 Gray/h (2.6 E07 Rad/hr)Radiation dose rate: 2.6 E05 Gray/h (2.6 E07 Rad/hr)– Total radiation dose: 1.6 E06 Gray (1.6 E08 Rad) – Filter efficiency for 2.5 cm test bed: 99.97 %

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Iodine Filter Adsorption MaterialIodine Filter Adsorption Material● Zeolite is doped with silver. Iodine is filtered by chemical sorption.

● Zeolite efficiency tests are always performed under steam atmosphere atelevated temperatures (representative conditions).

● Long-term treatment under

– H2 atmosphere

– Steam atmosphere

– High temperature

● Cl2 from cable burning will not replace AgI but I2 will replace AgCl.

● Silver chloride is used as adsorption material in some filter designs● Silver chloride is used as adsorption material in some filter designs

● Amount of silver is several orders of magnitude higher as would berequired to bind the iodine.

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● Applied zeolite does not show catalytic effects.


Design Aspects – Enhancements since Qualification for German ReactorsQualification for German Reactors● Additional qualification testing has been performed by WEC and YIT in 2011

and 2012, for example:, p

– Heat conductivity measurement of zeolite

– Heat conductivity measurement of metal fiber material

E i i it t f li t b ll– Emissivity measurement of cooling tube walls

– Heat removal capacity testing of cooling tubes (natural convection)

– Full scale integral test on heat removal capacity– Long term heating and performance test of zeolite material (test of temperature

resistance under representative conditions)

– Long term steam treatment and H2-treatment test on zeolite materialg 2

– Long term heating test of metal fiber material (test of temperature resistance under representative conditions)

– Test of effect of melting and crystallization of CsOH on pressure drop behavior

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Test of effect of melting and crystallization of CsOH on pressure drop behavior


Heat Conductivity of Metal Fibersand Zeolite Materialand Zeolite Material

Third partytifi t f h tcertificate for heat

conductivity testingof metal fibre filter

Measured heatconductivity ofconductivity ofzeolite

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Testing of Heat Removal CapacityTesting of Heat Removal CapacityFull scale integral t t tMeasured temperature evolution test set-upMeasured temperature evolution

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3. Qualification


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Advantages of the DFM● Ability for long term operation in a fully passive manner:

Advantages of the DFM

– Decay heat is removed passively by natural convectiono No makeup water neededo No chemical supply needed for pH controlo No chemical supply needed for pH controlNo need during and after venting for:

o emergency AC and DC power org y po auxiliary systems

Passive process control by fixed expansion orifice– Passive actuation by use of a rupture diskNo operator action needed for long-term venting process

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Advantages of the DFMAdvantages of the DFM● Outstanding filter efficiency with permanent retention of aerosols,

l t l d i i dielemental and organic iodine

– DF for aerosols: > 1.0 E6 (see ACE tests)

Typical DF for elemental iodine: > 1 000– Typical DF for elemental iodine: > 1,000

– Typical DF for organic iodine: > 40

– DF for gaseous iodine can be increased, if requiredDF for gaseous iodine can be increased, if required

● Large margin against filter clogging of the aerosol filter

● Adaptable to any seismic requirements due to simple and robust p y q pdesign

● Extremely high radiation resistance of zeolite

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Advantages of the DFM● No significant source of condensation for steam-inerted gas

mixtures during start-up phase


mixtures during start up phase – No de-inerting in piping– No de-inerting in metal fibre filter (inside containment)– Zeolite heated up by exothermal adsorption of condensed

waterDFM compares favorably to unheated scrubber systems with p y y

respect to potential hydrogen deflagration

Installation of the aerosol filters inside the containmentInstallation of the aerosol filters inside the containment offers additional advantages:● Long-lived radioactive aerosols remain in the containment

N d hi ldi d d

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● No secondary measures, e.g. shielding, are needed


Advantages of the DFM● Limited periodic testing requirements:

L k f fil ( 4 )


– Leak tests of filter (~ 4 years)– Functional tests of valves

● Flexibility of installation due to modular design:Flexibility of installation due to modular design:– Aerosol filter inside or outside containment– All filter modules can be flexibly adapted to site specific

t t l ti d t i tstructural properties and constraints– Installation in existing rooms and buildings possible in a flexible

way– Installation of all filter units outside in new building or standard

container possible– Small construction volume, easy assembly

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Small construction volume, easy assembly


Advantages of the DFM● Essentially free of maintenance:

No chemistry control needed


– No chemistry control needed– No water makeup systems needed– No heating systems needed– Only nitrogen inertion is provided during stand-by

● Short delivery lead times:F f i f l fil d fil h i (fi– Fast manufacturing of aerosol filter and filter housings (first venting filter in Germany was delivered within 10 days from order to delivery)

– Fabrication of zeolite for iodine filter within few months● All installed DFM systems have passed the German and

European stress tests without any remarks.

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p y





3. Qualification


5. Back-up slides

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Inspection Tests and MaintenanceInspection, Tests and Maintenance

Maintenance: ● Replacement of nitrogen bottles

P i di t tPeriodic tests: Actuation: ● Isolation valves so at o a es● Rupture disc (if used) Filter Unit: ● Leak tests every 4 years● Pressure tests during installation and commissioning

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Dry Filter Method Aerosol Filter outside ContainmentAerosol Filter outside Containment

Combined Filter (metal fiber & iodine filter module located outside containment)containment)

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Dimensioning of Iodine FilterDimensioning of Iodine Filter

● The performance of the iodine filter is designed to the requirements.

● Typical retention efficiencies of the existing systems are 99.9 % (DF 1000) for elemental iodine and 97.5 % (DF 40) for methyl iodine.

● The main design parameter is the residence time in the zeolite bed.

● The residence time is proportional to the zeolite volume.

● Each zeolite production batch is performance tested under representative conditions by independent third partiesrepresentative conditions by independent third parties.

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International ACE reference test (best system tested)

Test with DOP (dioctylpthalate) and realistic test aerosol was done in the USA

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Loading tests with SnO2 at Battelle Europe ( t t i t d i )(out-containment design)

Use of SnO2conservative

ltresults

Design area

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dry filter method (dfm) containmentdry filter method (dfm ...aerosol filter (deep bed metal fiber...

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