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French Safety AuthorityNuclear Power Plants Department

M. Romain PIERRE

SAFETY REQUIREMENTS IN FRANCE FOR THE PROTECTION AGAINST EXTREME

EARTHQUAKES

IEM3 IAEA

Radioprotection and Nuclear Safety InstituteIRSN/PRP-DGE/SCAN/BERSSIN

M. David BAUMONT

International Experts Meetingon Protection against Extreme Earthquakes and Tsuna mis

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Content

1. The nuclear safety approach in France to determin e the seismic loadings

1. Deterministic approach2. Complementary methods (PSA, SMA, Earthquake-event

approach)

2. Conclusions of the complementary safety assessmen t relative to earthquake

3. National crisis drill « nuclear and seismic »1. Crisis organization2. Drill Scenario

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French Safety AuthorityNuclear Power Plants Department

Nuclear safety approach in France to determine the seismic loadings

IEM3 IAEA

RFS 2001-01

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Safety approach in France

• The nuclear safety approach in France is based on:– The prime responsibility of the licensee for the safety of its facilities;– Continuous improvement of nuclear safety and radiation protection.

• ASN defines safety objectives• The licensee realises the demonstration of the safety with methods

of his choice

• ASN guides and safety rules (RFS) produced by ASN with the technical support of IRSN:– Texts that are not legally binding– These are recommendations which :

• imply an interpretation of positive law ;• clarify the safety objectives and describe practices that ASN considers

to be satisfactory to reach the objectives set by the regulatory texts.– These rules can be made legally binding by a formal decision

• French regulation is globally deterministic.

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French regulatory recommendations applicable to NPP’s

Seismic ground motion

RFS 2001-01 (2001)

Soil characteristics

RFS 1.3.c (1984)

Earthquake design

Guide ASN/2/01 (2006)

Instrumentation

RFS 1.3.b (1984)

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1981 : Regulation devoted to the SHA for nuclear installations : « French Safety Rule »

1997- 2000 : Revision motivated by the improvement in :

- Characterization of active faults

- Estimation of the magnitude of historical events

- GMPE based on numerous recent accelerometric data recorded in Europe

- Experience feedback on the importance of site effects following important

earthquakes (Mexico 1985, Loma-Prieta 1989, Northridge 1994, Kobe 1995 …)

2001 : New safety rule, named RFS 2001-01

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Regulatory requirements for Seismic Hazard for French NPPs

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RFS 2001-01 – Requirements for Seismic Hazard for French NPPs

SCOPE OF RFS 2001-01

�Safety-related functions must be maintained during and following plausible earthquakes that could affect nuclear installations.

�Define an acceptable method for determining the vibratory ground motions that are to be taken into account in the seismic design.

BASICS OF RFS 2001-01

�In this French deterministic approach , we assume that EQ analog to past events can happen in the future in a penalizing location for the facilities.

�Definition of the characteristics of "Maximum Historically Probable Earthquakes" (SMHV) considered to be the most penalizing earthquakes liable to occur over a period comparable to the historical period (~ 1 000 yrs).

�Definition of a "Safe Shutdown Earthquakes“ (SMS) to account for uncertainty on the definition of MPHE, which may be completed by paleoseismological evidences.

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Step 1 - Characterizing Seismic Source Zones & Potentially Active Faults

In France, tectonic deformation rate and

seismic activity are low . EQ are often difficult to relate to

a specific fault.

The RFS 2001-01 recommends to define seismotectonic zones

where the seismogenic potential is assumed to be

homogeneous.

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Example of IRSN seismotectonic zoning

scheme (Baize et al., 2012).

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Step 2 - Defining Reference Earthquakes for NPP sites

Historically known EQ can occur in the future at any point of their

seismotectonic zone.

The most penalizing location for the NPP (in terms of intensity) is retained (i.e. closest distance to

site).

"Maximum Historically Probable Earthquakes“ - SMHV

ID, distance, predicted intensity at site

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Example for Paluel NPP

IRSN scheme

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Step 2 - Defining Reference Earthquakes for NPP sites

Historical seismicity data are hindered by a lack of precision concerning both the

accuracy of the facts and the assessment of macroseismic intensity levels.

Information collected in an updated macroseismic data base (www.sisfrance.net)

"Maximum Historically Probable Earthquakes“ - SMHV

ID, distance to site, magnitude and depth, predicted intensity at site

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Example for the 1775 Caen EQ

IRSN scheme

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Step 3 - Defining the Safe Shutdown Earthquake

In order to take account of uncertainties inherent in the determination of the SMHV characteristics, a fixed safety margin is defi ned as follows.

For each SMHV, we define a "Safe Shutdown Earthquake" (SMS), deduced from the SMHV by increasing the intensity at site by one unit :

I SMS = ISMHV +1

“Safe Shutdown EQ“ – SMS

A one-degree increase in intensity corresponds to an increase in magnitude conventionally set at 0.5.

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Step 4 - Accounting for Paleoseismic Evidences

Active faults are considered in the regulation only in the presence of paleoseismic evidences

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Step 5 - Calculation of Seismic Ground Motion

Seismic motion is defined by the response spectra of the horizontal and vertical

components of the motion on the surface of the site ground. This definition can be supplemented by other parameters.

Input parameters = Surface-waves magnitude, hypocentral distance and soil

conditions

Median value of GMPE for SMHV, SMS and paleoEQ

A minimum fixed spectrum anchored at a PGA of 0.1 g is applied

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0.01

0.1

1

0.1 1 10 100

Fréquence (Hz)

Pse

ud

o-a

ccé

léra

tio

n (

g)

SMS Sédiments M=5.3 Distance= 10 km - EDF 1 12 1769

Minimal forfaitaire 0,1 g sédiment

EDF 0,2 g

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Deterministic and probabilistic approaches

The demonstration of the safety of these installations is based

firstly on a deterministic approach.

This approach is supplemented by probabilistic safety

assessments (PSA), which needs to be feed with PSHA.

PSAs are to be used as a complement to deterministic

studies and not as a substitute for them.

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Low frequency content =

Large EQ on the Cévennes fault

High frequency content=

Local moderate EQ translated below the NPP

Baumont & Scotti (2008)

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Complementary methods (2/2)

• Seismic Margin Assessment (SMA):– Aims: Study the robustness of the facility to an earthquake larger

than the design-basis earthquake.– Deterministic study of the strength of equipment, systems and

structures necessary for shutdown of the unit to a safe state, considering as standard a small RCS break and a loss of offsite power

– Identification of the points which, if improved, would reinforce the robustness (construction measures, protection, relocation of equipment and so on)

– ASN asked EDF to include this topic in the forthcoming periodic reactor safety reviews

• Earthquake event approach– Aim: prevent damage to an equipment item necessary in the

event of an earthquake by an item or structure not seismic-classified.

– Approach implemented on the occasion of the periodic safety review.

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PSR Process

Design

Every 10 yearsCompliance exam

reassessment

Laws impose PSR Opinion of ASN after

licensee reportMost recent safety

objectives taken into account

ASN policy : improvement of the safety level (former

design vs. new safety standards)

Seismic PSR

•Ground motion•Rules for earthquake-resistant construction•Resistance studies, reinforcement•Margin studies (SMA), seismic PSA, Event-earthquake approach•Non conformity, incident, inspection•OEF (French and worldwide)•Modifications (equipment, seismic qualification)•Maintenance

Periodic Safety Reviews and Seismic Reinforcements

Seismic reinforcements

Strengthening concrete structures using fibre composite material

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French Safety AuthorityNuclear Power Plants Department

Conclusions of the complementary safety assessment

IEM3 IAEA

Earthquakes

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Complementary Safety Assessments

• Specific inspections – 2 - 3 days per NPP– Fukushima-related topics– 38 inspections (June-Oct. 2011), 116 days of

inspection

• Stress Tests requested by the European Council and the French Prime Minister– Based on Europeans stress tests Specifications– 150 nuclear installations, 21 Licensees– Includes Human and Organizational Factors

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Conclusions - Earthquakes

• Seismic margins on the nuclear reactors and the more recent fuel cycle facilities are sufficient to prevent cliff-edge effects from occurring in the event of a limited overshoot of the current baseline safety requirements

• However, ASN identified several areas in which safety could be improved, related to the robustness of the facilities to earthquakes and it will be asking for:

– Protection against fire for equipment used to control the basic safety functions;– Greater awareness and assimilation of the seismic risk by the operators in the day-to-

day operation of the facilities, by strengthening operator training, improving the awareness of the "event-earthquake1", ensuring compliance with the basic safety rule concerning seismic instrumentation (maintenance, operator familiarity with the equipment, calibration);

– For some facilities, study analysing the seismic robustness of the dykes and other structures designed to protect the facilities against flooding and to present the consequences of a failure of these structures.

• Hardened safety core: beyond basis design � this level of robustness beyond basis design will be integrated into French regulation.

• ASN has decided to review the methodology for assessing the effects of earthquake on nuclear facilities, to take account of experience feedback from the Fukushima accident, the most recent data and the best international practices

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French Safety AuthorityNuclear Power Plants Department

National crisis drill « nuclear and seismic »

IEM3 IAEA

Cadarache Site – January 17th, 2012

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Crisis organization

• Public authorities– Government

– Prefet• Off-site emergency plan: PPI

– Emergency services

– Nuclear Authorities

– IRSN

• Licencees– On-site emergency plan: PUI

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Scenario

• Simulation of a realistic event in terms of earthquake and consequences :

– M = 5.5– P = 5 km– 12 km from Cadarache

• Simulation of a nuclear accident induced by an earthquake having affected a large territory around the site

• The damage to the nuclear site and the vicinity were assessed from the earthquake scenario and from the already known vulnerability of the structures and equipment.

• Outside the centre:- More than 10 000 homeless;- 90 fatalities;- 45 persons under rubbles;- 110 severely injured people;- 600 slightly injured persons;- 200 destroyed buildings;- 1000 partially destroyed buildings;- 2500 cracked buildings.

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Scenario – In the CEA

Contaminated wounded personsContamination of the staff

Rescue opérations

No seismic replica during the drill

Loss of power supply on the site

Earthquake

Control and decontaminationManagement of the events on the installations

T0 T0 + 3 min

Radioactive emission

First major eventon a nuclearinstallation

T0 + 1 h30

Loss of telecommunications

Radioactive emission

T0 + 4 h T0 + 4 h 30

Second major event on another

installation

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The drill

• The licensee simulated a diagnostics and put the installation in a safe state

• Evacuation of workers if needed

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The drill – In the CEA

• The licensee called external specialized services (specialized firemen, decontamination services, clearing services)– Specialized firemen simulated to rescue people.

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The drill – Inside the centre

• The licensee simulated to call external emergency services (firemen, clearing services, decontamination services)

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The drill – In the CEA

• Robots of INTRA

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The drill – Ouside the centre

• Rescue to population

• Evacuation

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The drill – Outside the centre

• Radioactivity measures

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Learned Lessons

• The aims of this drill were reached

• Experience feedback:– Sheltering procedure are not adapted in case of an earthquake

and a nuclear crisis (dammages of buildings)– Importance of means of emergency (robots, radioactive

measures, telecommunications) and of external services (specialized firemen, clearing services and decontamination services)

• 4 prefets (zone prefet + region prefet) � need for a single center of command

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A movie on this drill

• French and English versions

http://www.asn.fr/index.php/S-informer/Videos-de-l- ASN/Exercice-de-crise-a-Cadarache

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Questions ?