Nuclear power post-Fukushima65655/Dr_Selena_Ng__AREVA_.pdf · Source: *US Geological Society,...

Nuclear powerpost-Fukushima

Dr Selena NgRegional Director, South-East Asia & OceaniaSIEW Electricity Roundtable – Singapore – November 2011

Copyright AREVA 2011 – All rights reservedAny reproduction, alteration, or transmission to any third party of any part of this document or its content is strictly prohibited except with AREVA's prior written consent

S.Ng – Singapore – November 2011 – p.3 Copyright AREVA 2011 – All rights reserved

Our response

International response

The Fukushima

accident


Our current understanding of the events at Fukushima

Initiating events: earthquake and tsunami beyond design basis

AC power loss and consequential damage to cooling capability

H2Hydrogen generation & explosions

Reactor used fuel pools

Accident management: monitoring & control, emergency response

Radioactive release to the environment

External hazard

Damage to cooling

capability

Severe accident Loss of fuel integrity & containment breach


Tōhoku earthquake*(Great East Japan Earthquake) on March 11, 2011 (14:46 JST)

Magnitude 9.0

Underwater depth 32km

177km from Fukushima

Most powerful known earthquake to hit Japan; 4th largest earthquake in the world since modern record-keeping began in 1900

Tsunami** wave height estimated at approximately +15 meters (O.P.: Onahama Port base tide level )

Source: *US Geological Society, **TEPCO

Initiating events: combination of natural hazards of exceptional magnitude


Source: NISA, JNES, TEPCO

Beyond design basis earthquake

Measured accelerations up to 26% higherthan earthquake design basis values

Automatic shutdown of all operating reactor units (1-3) occurred within seconds


Beyond design basis tsunami

Source: TEPCO


► An accident at a unit should not impact the surrounding units

► On-site emergency means must be able to cope with several units

A multi-unit accident

Source: TEPCO

Hydrogen explosion at Unit 3 may have disabled some fire pumps used for seawater injection at Unit 2

TEPCO found evidence that the March 15 explosion at Unit 4 was caused by hydrogen that had flown from Unit 3


► Loss of off-site power due to earthquake

► Emergency Diesel Generators (DGs) started and worked properly

► Tsunami 55 minutes later rendered DGsinoperable

► Station blackout: all motor-operated pumps rendered inoperable

► Batteries in units 1-2 unavailable (water-damaged) as located under ground level

Source: NISA, TEPCO, IAEA

1

2

3

4

4 lines off-site power supply 13 Diesel Generators (D/G)12 Residual Heat Removal (RHR) Sea Water Systems

(Heat Sink)

5

Loss of power and consequential damage to cooling capability


Source: TEPCO

Damage to cooling capability

Power was secured in Unit 6 only (Unit 6 air-cooled diesel generator): combination of diversity in cooling technology (vs water-cooled), location (higher than water-cooled DGs) and hardened power distribution


Other sites hit by the tsunami

Source: JAIF, IAEA

► Site ground level (13.8m) above tsunami local height

► Some external power supply lines and seawater pumps remained operational

► Site ground level (8m) above tsunami local height

► One of two bays (upgraded) and an emergency diesel generator remained operational

► External power maintained


All assemblies were in Unit 4’s reactor pool on March 11 due to core shroud replacement

Pool water temperature of 84°C on 14 March

Fires on March 15 & 16

No confirmation of fuel damage today

Reactor used fuel pools

Source: NISA

►Need for pool monitoring and make-up water systems (NRC)

►Used fuel should be moved to dry storage as quickly as possible (MIT)

►Used-fuel pools could be housed in containment-like structures separate from the reactor building (MIT)

►The pools might have been fuller without the site central pool, making the situation more problematic


Accident management:monitoring & control capabilities

Source: TEPCO

“As there was no power, work inside the building

was conducted in complete darkness, and temporary

instrument power had to be installed separately for

each instrument.”

Station blackout and DC power loss resulted in:

► Shutdown of instruments and control equipment

► Loss of main control room monitoring and operation functions (including communication)


“During the initial response, there were several aftershocks, and work was conducted in extremely poor conditions, with uncovered manholes and cracks and depressions in the ground. There were also many obstacles blocking access routes.”

Source: TEPCO

Accident management:emergency response

No on-site mobile generators available

No containment venting procedures

Complete loss of power not tackled

Delays in implementation of alternate cooling functions caused a “cliff-edge”effect leading to the severe accident


H2

Hydrogen generation & explosions

Source: RGB

► Include reliable hardened vent in BWR Mark I and Mark II containments (NRC)

►Risks and implications of hydrogen explosions should be revisited and necessary mitigating systems should be implemented (IAEA)

Mark I and Mark II type containments and modified versions of these BWR plants in Japan use inerted containment and wetwell for mitigation of Hydrogen hazards during normal operations

Vents were installed on Japanese BWR plant following Three Mile Island

Source: IAEA


Exposure of more than 10,000 workers measured*

9 workers over emergency exposure dose limit of 250 mSv

500+ workers over 100 mSv

No radiation-induced casualty

Casualties at the Fukushima site were caused by the earthquake and tsunami

Fukushima Daiichi dose rate measurements (IAEA)

Radiation dose of workers

*Internal and external as of September 2011

Source: JAIF


Reference radiation doses

Source: TEPCO


Accident revised to Level 7(INES scale) on 12 April based on the “people and environment” criteria, as a result of radioactivity release estimation

Total release of radioactive material 300-600 PBq Iodine 131-equivalent – one tenth of the Chernobyl accident

Evacuation area of 20km radius on 12 March, with recommended evacuation within 30km radius and in “hot spots” beyond 30km north-west of the plant site

Environmental damage:volatile radioactive release

Source: IRSN


Fukushima (IRSN)

2000Rare gas (Xe133)

Radiation impact:Fukushima versus Chernobyl

PBq(1015 Bq)

Iodine 131

Tellurium 132

Cesium 134

Cesium 137

Ruthenium, BariumStrontium

Chernobyl(UNSCEAR*)

Source: IRSN *United Nations Scientific Committee on the Effects of Atomic Radiation 2000 Report

90

60

10

10

<1

7000

1500

1100

60

85

>100


On-site Water Contamination Sea Water

Environmental damage:water contamination

Source: TEPCO, WNA Source: NISA

About 110,000m3 of contaminated water

Most contamination from Unit 2 (20 MBq/cm3) versus Units 1 and 3 (0.4 MBq/cm3)


Status as of October 27:containment breach and fuel melt

Source: JAIF

Progressive understanding and control of situation

except for core integrity*

*Extent of core melt and core vessel damage still under investigation


Our response


The Fukushima

accident

Our immediateresponse


Emergency aid and relief supply

Mobilisation and supply of key equipment in record time due to our logistical capabilities

Protective equipment

Radioactivity measurement equipment

Shipment of all aid (including that provided by EDF and German utilities) using the world’s largest cargo aircraft, the Antonov

One million euro donation to Japan Red Cross


TEPCO and Japanese government

call on 27 March

Experts dispatched only 48 hours later

Up to 200 people mobilized non-stop

Interdisciplinary skills

Decontamination of effluents

Radiation protection

Used fuel management

Clean up

20 experts dispatched to Japan within one week

Only a few hours to mobilise expertise from our international network

Immediate technical support to TEPCO


Construction in radioactive waste building (TEPCO © Copyright)

Our decontamination facility for highly radioactive water was essential in mitigating the crisis at Fukushima

No contaminated water overflow to the ocean

80,000 tons of highly radioactive water decontaminated by mid-September

Closed-circuit cooling of the reactors with decontaminated water made possible

A solution for water decontamination in operation in 2 months


Rapid development & deployment of two food monitoring systems

Supply of whole body counters to TEPCO, Fukushima prefecture and hospitals

FoodScreenTM

Radiological Food Screening System

Radiological emergency response and environmental monitoring

FoodSpecTM

Radiological Food Analysis System


Our response


The Fukushima

accident

Our continuedresponse


A rough idea of reactor generations

Generation I

Generation II

Generation III

Generation III+

Annual increment of nuclear power world wide


Three major events influenced the design of our new reactor range

1979 - Three Mile Island :Accident with core melting1979 - Three Mile Island :Accident with core melting

1986 - Chernobyl : Radioactive dispersal1986 - Chernobyl : Radioactive dispersal

Reduce the probability of a severe accident

with core melting

Reduce the impact on the population

in case of asevere accident

Reinforcethe resistance to

any external attack(commercial airplanes)

A B C

2001 – 9/11: Terrorist attackwith commercial airplane2001 – 9/11: Terrorist attackwith commercial airplane


Three major events influenced the design of our new reactor range

Reduce the impact on the population in case of

severe accident

Reinforce the resistance to any external attack

(commercial airplanes)

Physical separationRedundancy of critical

components for maintenance and diversity

Core catcherAnnulus and filtration

Airplane-crash-resistantcontainment

(double shell + liner)

A

B

C

Reduce the probability of a severe accident with core

melting

*no emergency evacuation beyond the industrial site, and no long-term relocation

Whatever happens inside or outside the nuclear power plant, no impact on the surroundings*

Main Goals Main Goals AREVA technical options AREVA technical options


The defence-in-depth concept…

First line of defence

Second line of defence

Third line of defence


…as applied to design safety

Prevention of abnormal

operation and failure

Control of abnormal

operation and detection

of failures

Control of accidents

within the design basis

Control of severe accidents

Mitigation of the

consequences of severe accidents


An accident is a complex series of events…

Redundancy

against single failureComplementarity

using both active and passive systems

Diversity

against common cause failure

Emergency power sources

Four safeguard divisions

1

23 4

Core catcher &Containment spray

…so the design must provide the means to remain in control whatever happens


These safety objectives werealready largely adopted worldwide

Safety Authorities

France, Finland, UK

WENRA

Utility requirements

EUR

Safety Authority

NRC

Utility requirements

URD

Political decision to move toward Gen III

Gen III requirements

Norms to set up, but political will for Gen III

No official position regarding Gen II or Gen III

Transition towards Gen III

Source: AREVA analysis


Our vision of safety post-Fukushima

“What happens to the plant if there is an exceptional natural event?”

“Nuclear plants don’t just shut down. Can you ensure that the plant will continue to cool down?”

“If all else fails, can you guarantee our safety in the short- and long-term?”

ROBUSTNESS OF

COOLING

CAPABILITY

PREVENTION OF

ENVIRONMENTAL

DAMAGE

Imperative 2Imperative 3

RESISTANCE TO

MAJOR

HAZARDS

Imperative 1 But If..But If..


Our response

The Fukushima

accident



2011 2012 2013

Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4

Further lessons learnedUpdate of regulations

Preliminary inspectionsShort-term measures

Analysis of first lessons learnedSafety checks

Typical scheduleTypical schedule

~9-12 months

x years

~3-6 months

Short-term measures are necessarybut lessons-learned process may last over ten years

Regulatory authorities worldwide launched three kinds of measures


Assessments undertaken by European operators before June 1, 2011

Process concerns 14 countries and 143 nuclear power reactors

Scope covers extreme natural hazards (earthquakes, flooding…) and their consequences

June 1 Sep 15

National progress reports

June 2012

EC consolidatedreport to Council

Dec 31

National final reports

Dec 9

EC progressreport to Council

Peer reviewson reports

April 30

A European framework…but safety remains a national prerogative

European agreement on safety checks


ASN

STUK

RSK

HSE/ONR

Germany

France

UK

Finland

Status of safety checks in Europe

Results from complementary safety evaluations were sent to the ASN on 15 Sep for report to the government by the end of 2011

Final ONR report published on 11 October, pointing 38 areas where lessons can be learned, but revealing no fundamental safety weaknesses

Preliminary report issued 16 May concluded that there were no new threats nor gaps needing immediate upgrades although some issues requiring further surveys were identified; final report issued end of June

Report issued on 18 May concluded that the operating plants have a “high degree of robustness”, but a political decision was still taken to phase out all nuclear by 2022


Status of safety checks in the US

First inspections of 104 operating plants issued 20 May concluded that “every plant has the capability” to respond to severe accidents

Near-term review issued 13 July gave 12 “overarching”recommendations and 35 detailed recommendations for near-term and longer-term actions associated with seismic and flooding events, station black out, beyond-design basis events

18-month review due to report at the end of 2012 based on the NRC’sfirst recommendations for development of a new regulatory framework

Recent natural disasters led to successful real-scale exercises

Fort Calhoun (flood), Brown Ferry (tornado) & North Anna (earthquake)

NRC


NISA

AERB

Rostekh-nadzor

NNSA

Russia

Japan

China

India

Status of safety checks in Asia and Russia

Merging of NISA with NSC by April 2012; new “comprehensive safety assessments” based on European methodology to be achieved by the end of 2011

Initial survey of plants in operation and under construction completed on 5 August with results and proposed improvements to be made public by mid-2012

Decision taken to create an independent safety authority; a high-level committee report submitted to AERB on 31 August currently under review

Declared the “absence of gaps” following the audit of the Russian fleet on April 18


ASN

STUK

NRC

HSE/ONR

US

France

UK

Finland

Position of safety authorities to date on EPR™ design and new build

Construction of Flamanville 3 ongoing during safety check with conclusions from ASN expected 15 November

UK EPRTM design certification ongoing with final design acceptance expected by end of 2012

No shortcomings have been identified on Olkiluoto 3’s resistance to extreme external hazards, and construction is proceeding normally

U.S. EPR™ design certification ongoing

NNSAChina

Approval of new reactor projects suspended since March but construction of Taishan 1&2 ongoing


Safety regulation trends: more cooperation & more independence

Safety checks methodology adopted in various parts of the world EU approach adopted by 7 neighbouring countries, Japan, Brazil

International harmonisation to be enhanced IAEA to play a central role

Inspection missions & peer reviews will be further developed WANO to conduct peer reviews of safety in all NPPs within 3 years

Growing independence of safety authorities Positive recent evolution in Japan, South Korea, India

But the effectiveness of the IAEA depends on resources and political will: strengthened international oversight was refused by its board at the September 2011 conference


Nuclear program / projects confirmed

New Build program frozen / construction halted

Decision to gradually exit nuclear power /New Build program cancelled

Most countries have not rushed decisions...


…but public confidence must be regained

To earn and keep public confidence, there must be no compromise on safety and an imperative forcontinuous improvement


Focus on South-East Asia

Source: Map from NIE website


Our response


The Fukushima

accident

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