Retrofitting Severe Accident HardwareGeneration III Safety Targets for Generation II Designs

Filtered Containment Venting SystemsGeneral Overview and Applicability to CANDU Plants

Presentation to US Nuclear Regulatory Commission (NRC)July 12, 2012

Follow-up from CNSC/NRC Bilateral Meetings and Site Visit to Point Lepreau

The AREVA Technology is protected by patent and copyright law and this presentation is provided for information purposes only.

Presentation Outline

1. Severe Accident Fundamentals & Safety Targets

2. Filtered Containment Venting Overview

3. Qualification of Process

4. Fukushima Implications

5. Application to CANDU Plants

6. Installation at Point Lepreau

7. Status of FCVS at CANDU Plants

8. Regulatory Approval History at other CANDU Plants

9. Summary & Discussion

July 12, 2012 – NRC p.2 Patent Protected

� IAEA safety standards establish fundamental safety principles, requirements and measures.

Severe Accident Fundamentals

� Main Principles:

� In view of the uncertainties involved in severe accidents, severe accident management guidance should be developed for all physically identifiable challenges, irrespective of predicted frequencies of occurrence of the challenge.

� For example, venting the containment, if necessary to protect the structural integrity of the ultimate fission product barrier, should be initiated at a time and at a containment pressure level that gives confidence that the structural integrity of the containment will not be lost.

July 12, 2012 – NRC p.3 Patent Protected

� The US NRC requirement for calculated core damage frequency < 1x10-4.

� Current plants have about 5x10-5.

� Generation III plants are about ten times better than this.

� The IAEA safety target for future plants is < 1x10-5. Calculated large release frequency (for radioactivity) is generally about ten times less than CDF (1x10-6).

Severe Accident Safety Targets

July 12, 2012 – NRC p.4 Patent Protected

Severe Accident Safety Statistics

5 Cores Damage and 4 Large Releases

� Three Mile Island - 1979

� Chernobyl - 1986

� Fukushima - 2011

Total Reactor Operating Years ~ 15,000 for Global Fleet

Actual Core Damage is happening an order of magnitude more often that Probabilistic Risk Assessment (PRA) calculations.

Highlights IAEA safety fundamental to address “all physically identifiable challenges irrespective of predicted frequencies”.

July 12, 2012 – NRC p.5 Patent Protected

1988 OECD/NEI Committee

� Assembled world specialists post Chernobyl:

� International exchange of Information on technical aspects of FCVS.

� Evaluated Technologies being deployed.� Germany, France and Sweden all installing

FCVS for capture of fission products.• General concept of “Install Hardware”

independent of probability for:• Filtered Containment Venting• Passive Hydrogen Recombiners• Main Control Room Ventilation Filtering• Independent off-grid Power Supply

� CANDU Plants did not address:• Considered outside Design Basis.• Moderator the “Ultimate Heat-Sink”.

July 12, 2012 – NRC p.6 Patent Protected

CNSI Specialist’s Findings in 1988Fukushima Implications

DF > 10,000Efficiency 99.99%

0 < DF < 100NRC Accepted DF = 5

Efficiency 80%

AREVA CFVS capture efficiency is > 2000 times better than GE Mark 1 Suppression Pool with Unfiltered Venting.

July 12, 2012 – NRC p.7 Patent Protected

Preventable Radiation Impact

CFVS could essentially have eliminated all off-site long-term

Dose issues.

� At a 2000 �DF over 70 years:� 4 Sv reduced to 2 mSv� 400 rem reduced to 200 mrem

July 12, 2012 – NRC p.8 Patent Protected

Pre-Fukushima CNSC Initiative

July 12, 2012 – NRC p.9 Patent Protected

Post-Fukushima - CNSC Task ForceSection 6.4.2.1 Containment Venting

� A system has been installed at Point Lepreau; it is manually actuated, does not require an external source of power and is used to relieve containment pressure for the conditions that could be present in a severe accident.

� ECFV uses a high-efficiency scrubber and filtration unit to filter out the vast majority of fission products so radiation exposure to the public would be limited to acceptable levels in the event of a release.

� Similar venting provisions need to be considered for all other Canadian NPPs to provide a means to minimize the release of radioactivity while protecting the containment integrity.

July 12, 2012 – NRC p.10 Patent Protected

New Build Requirements – Canada Complementary Design Feature

� DEFINITION: “A design feature outside of the design basis envelope that is introduced to cope with beyond design basis accidents, including severe accidents.”

� 7.3.4 Beyond Design Basis Accidents� Complementary design features are considered with

the goal of preventing identified BDBA scenarios, and mitigating their consequences if they do occur.

� Complementary design features are based on a combination of phenomenological models, engineering judgments, and probabilistic methods.

� The design identifies the rules and practices that have been applied to the complementary design features.

� These rules and practices do not necessarily need toincorporate the same degree of conservatism as those applied to the design basis.

July 12, 2012 – NRC p.11 Patent Protected

Filtered Containment Venting Overview

Containment ProtectedCommunity Protected

July 12, 2012 – NRC p.12 Patent Protected

AREVA FCVS OverviewWET PROCESS DESIGN

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AREVA FCVS OverviewWET PROCESS DESIGN

� Low H2 Detonation Risk

� N2 inert environment in poised state.

� Steam inert during operation due to wet saturated conditions in Vessel.

July 12, 2012 – NRC p.14 Patent Protected

AREVA FCVS Overview� Specific Applicability of WET PROCESS to CANDU Design

� Low Pressure operation required due to low Containment Design Pressure versus PWR/BWR.

� Large amounts of water inside containment that create wet steam.

July 12, 2012 – NRC p.15 Patent Protected

AREVA FCVS Overview

� Do not use flammable/combustible Additives

� Additive salts lower pH during operation to acid levels that significantly diminish the overall Decontamination Factor as well are flammable at low temperature and combustible at Severe Accident Temperatures.

July 12, 2012 – NRC p.16 Patent Protected

Filtered Containment Venting Overview

� System Basics

� The CFVS operates by passing the vented vapors from the containment atmosphere through a scrubber/filter vessel to remove high activity isotopes and aerosols to contain the radioactive releases.

� Process suitable for high radiation, high temperature and high moisture, unlike Dry Systems or HEPA Filter-Charcoal Systems.

July 12, 2012 – NRC p.17 Patent Protected

Scrubber Vessel

� The Scrubber Vessel consists of a pressure vessel housing Venturi Nozzles and integrated Metal Fiber Filters.

July 12, 2012 – NRC p.18 Patent Protected

Venturi Nozzles

The high velocity between the scrubbing solution and the gas forms fine droplets which effectively entrain the aerosols.

The scrubbing water provides large mass transfer surfaces inside the throat of the nozzle, which permit effective absorption of iodine.

July 12, 2012 – NRC p.19 Patent Protected

Venturi Nozzle Factory Testing

July 12, 2012 – NRC p.20 Patent Protected

Metal Fiber Filters

� Following the venturi phase, the gas enters the metal fibre filter stage where the micro aerosols still contained in the gas are retained in the filter material.

July 12, 2012 – NRC p.21 Patent Protected

Fiber Filters Factory Testing

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Qualification Testing

� Retention Efficiencies and Aerosol Load Capacity based on National Process Verification Tests at the Iodine and Aerosol Retention Rate Test Facility (JAVA)

� Retention Efficiencies and Aerosol Load Capacity based on International Process Verification Tests performed within the Advanced Containment Experiment (ACE) Test Program

July 12, 2012 – NRC p.23 Patent Protected

Process QualificationContainment Venting / JAVA Test Facility

July 12, 2012 – NRC p.24 Patent Protected

JAVA – Test Results

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JAVA – Test Results

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ACE - Filter Tests at Battelle Northwest

July 12, 2012 – NRC p.27 Patent Protected

ACE - Filter Tests at Battelle NorthwestResults: AREVA´s Combined Venturi Scrubber

AREVA NPJuly 12, 2012 – NRC p.28 Patent Protected

1990 ACE - Filter Tests at Battelle NorthwestTest vessel dimensions ( equal flow rates )

AREVA’s size advantage and higher decontamination factors made it the only technology to be installed past the Post-Chernobyl installations back in the late 1980’s and early 1990’s.

July 12, 2012 – NRC p.29 Patent Protected

Application to CANDU Plants

� Analysis has shown that over-pressurization of the containment structure does occur during severe accidents.

July 12, 2012 – NRC p.30 Patent Protected

Impact of PSA on CANDU Plants

Point Lepreau Refurbishment Project Level 2 PSA results for internal and external events.

� Level 1 and Level 2 PSA for internal events was undertaken to estimate the SCDF and LRF of PLGS after the plant refurbishment.

� The results of the Level 1 analysis identified the representative scenarios for which severe accident progression analysis was performed using MAAP4-CANDU.

� The Level 2 PSA results considering a new emergency filtered venting system for containment and make-up to the calandriavault are also below the safety limit of 1E-05/y for LRF. LRF estimates are also below the safety goal of 1E-06/y.

� The new emergency filtered venting system was the greatest individual contributor (> E-02) to the improvement.

AECL recommended to NB Power to implement AREVA’s CFVS Technology at Point Lepreau to meet the Level 2 PSA.

July 12, 2012 – NRC p.31 Patent Protected

CANDU Severe Accident Progression

In the severe accident, releases of high temperature steam and non-condensable gases occur into an intact containment due to failures of fuel channels, calandria vessel, and eventually the calandria vault.

� This would cause the containment pressure to increase beyond the concrete cracking pressure.

� Periodic filtered venting is required to keep the containment pressure under control, and thus keep the containment intact.

July 12, 2012 – NRC p.32 Patent Protected

CANDU Severe Accident Progression

Uncovered channels deform into contact with first submerged channel row

Weight of suspended debris is supported by first submerged channel row

Liquid level in calandria slowly drops with boil-off

Calandria Vessel

Reactor Vault Water

Calandria Vessel Rupture Disc

REF: AECL “Severe Core Damage Progression within a CANDU 6 Calandria Vessel”, ERMSAR 2008, 23-25 September 2008, Nesseber, Bulgaria

July 12, 2012 – NRC p.33 Patent Protected

CANDU Severe Accident Progression

REF: AECL “Severe Core Damage Progression within a CANDU 6 Calandria Vessel”, ERMSAR 2008, 23-25 September 2008, Nesseber, Bulgaria

Core collapses into residual water pool in calandria vessel

Porous terminal debris bed quenches

Residual water pool boil-off continues

Reactor vault water subcooled at this point

Calandria Vessel

Calandria Vessel Rupture Disc

July 12, 2012 – NRC p.34 Patent Protected

CANDU Severe Accident Progression

REF: AECL “Severe Core Damage Progression within a CANDU 6 Calandria Vessel”, ERMSAR 2008, 23-25 September 2008, Nesseber, Bulgaria

Heat is radiated to the walls of the calandria vessel

Crust is formed on the surface of the pool as heat radiated from the pool surface

Nucleate boiling occurs at the calandria vessel surface and vapour follows the contour of the lower vessel in a two phase flow.

Molten pool is formed and bounded on all sides by a corium crust

Molten corium can penetrate into porous crust where it eventually freezes

Calandria Vessel Wall

Nucleate boiling

July 12, 2012 – NRC p.35 Patent Protected

Calandria Vault MakeupOption

July 12, 2012 – NRC p.36 Patent Protected

With Calandria Make-up Option and FCVS it eliminates short term time requirement to get back Station Power .

Equipment Location(CANDU6 Standard Design)

The CANDU6’s all have similar:� Source Term� Containment Design� Plant Location & Layout

Standard Design was developed for Point Lepreau and is the basis for the other CANDU6 NPPs.

July 12, 2012 – NRC p.37 Patent Protected

Process Flow Diagram(CANDU6 Standard Design)

July 12, 2012 – NRC p.38 Patent Protected

Building CAD 3-D

Point Lepreau

July 12, 2012 – NRC p.39 Patent Protected

Drill Rig with Caisson

July 12, 2012 – NRC p.40 Patent Protected

Rebar Pile Cages

July 12, 2012 – NRC p.41 Patent Protected

Rebar and Pipe Hanger Embedment

July 12, 2012 – NRC p.42 Patent Protected

Rebar completed and Slab Poured

July 12, 2012 – NRC p.43 Patent Protected

Shielding Wall was Set, Formed and Poured

July 12, 2012 – NRC p.44 Patent Protected

Vessel Supports

July 12, 2012 – NRC p.45 Patent Protected

Scrubber Vessel Delivered to Site

July 12, 2012 – NRC p.46 Patent Protected

Scrubber Set on Supports

July 12, 2012 – NRC p.47 Patent Protected

Stack Upper Bracket Installed

July 12, 2012 – NRC p.48 Patent Protected

Stack Mid Bracket Installed

July 12, 2012 – NRC p.49 Patent Protected

Stack Installed in Four Sections

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Stack Installed in Four Sections

July 12, 2012 – NRC p.51 Patent Protected

Superstructure Steel Erected

July 12, 2012 – NRC p.52 Patent Protected

Roof and Siding Installed

July 12, 2012 – NRC p.53 Patent Protected

Piping Installation

July 12, 2012 – NRC p.54 Patent Protected

Remote Operating Station

July 12, 2012 – NRC p.55 Patent Protected

Construction Complete

July 12, 2012 – NRC p.56 Patent Protected

Proven Regulatory Approval History

Standard CANDU6 FCVS fully analyzed, benchmarked, sensitivity studied and Regulator reviewed & approved.

July 12, 2012 – NRC p.57 Patent Protected

Status - CANDU Containment Filtered Venting (CFVS)

� CANDU6

� Installed and commissioned at Point Lepreau.

� Design & Procurement completed for Gentilly.

� Installation underway for Cernavoda Units 1&2.

� Contract awarded for Wolsong Unit #1

� RFI stage for Embalse.

� Discussions initiated with Qinshan.

Multi Units

� Conceptual design completed for Darlington.

Only accepted technology by CNSC.

Recommended by CNSC Post-Fukushima Task Force for all Canadian Plants.

Recommended by Reactor OEM (AECL/CEI).

July 12, 2012 – NRC p.58 Patent Protected

AREVA CFVS Reference List

Latest CANDU Contracts: Cernavoda Units 1&2 & Wolsong Unit 1

� It was being Installed for Severe Accident Mitigation and PSA (including SBO) prior to Fukushima

July 12, 2012 – NRC p.59 Patent Protected

AREVA FCVS General Summary

� AREVA has nearly 60 reference installations in PWR, BWR, VVER and CANDU NPPs meeting the requirements of various national qualifications and Regulatory Authority in multiple Countries.

� Will not plug due to non-limiting aerosol loading capability.

� Can handle temperature and pressure excursions from potential in-containment hydrogen burns.

� Operational Flexibility - decay heat removal not limited and has ability to adapt to “unknowns” such as adding water if Severe Accident exceeds original analysis assumptions.

� Passive and Robust.

� Essentially no Maintenance.

� +10 year inspection cycle.

July 12, 2012 – NRC p.60 Patent Protected

Discussion