SAFETY REQUIREMENTS IN FRANCE FOR THE …gnssn.iaea.org/actionplan/Shared Documents/Action 01 -...
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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.
______________________
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
______________________
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
______________________
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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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