lessons learned from 1999 blayais flood : overview of edf ... - NRC

NRC – Regulatory Information Conference – 11 March 2010 - Page 1
RIC 2010
External Flood and
Extreme Precipitation
Ha Hazard ard Anal Analysis sis for
Nuclear Plant Safety
Session
LESSONS LEARNED FROM
1999 BLAYAIS FLOOD :
OVERVIEW OF EDF FLOOD RISK
MANAGEMENT PLAN
Eric de FRAGUIER
EDF Nuclear N l Engineering
E i i
Division
11 th MARCH 2010

NRC – Regulatory Information Conference – 11 March 2010 - Page 2
SUMMARY
1. EDF NPP LOCATION
2. DECEMBER 1999 BLAYAIS FLOOD
3. A COMPREHENSIVE REVIEW OF THE
FLOOD RISKS :
11. OUTLINE OF THE MANAGEMENT
PLAN
2. EXAMPLES OF MODIFICATIONS
IMPLEMENTED
4. OVERALL SCHEDULE OF THE REVIEW
PROCESS
5. CONCLUSION : LESSONS LEARNED

1. EDF NUCLEAR POWER PLANTS LOCATION
NRC – Regulatory Information Conference – 11 March 2010 - Page 3
location of NPPs
14 riverside site
4 seaside site
1 estuary site
58 units in
operation
1 under
construction

“LE BLAYAIS” NPP FLOODING in 1999
2. DECEMBER 1999 BLAYAIS FLOOD
1999 Storm
« Le Blayais »
NPP partial
flooding
INES le level el 2
80.000m 3
Nuclear
Island
Safety
Eqpt
NRC – Regulatory Information Conference – 11 March 2010 - Page 4
Workshop IAEA on External Flooding , Jan 2010, KALPAKKAM – Presentation IRSN 1
High water level in the river GGironde
:
high tide + storm surge (+2m)
and waves (2m) generated by the wind
on the estuary (200 km/h )
Waves came over the dyke and
caused flooding on site and in units 1
and 2
On-site Emergency plan (36 hours)

Protection of French NPPs against external flooding
before Blayais y flood
(Safety Rule RFS I.2.e – Issued 1984)
Maximum design flood level to be assessed considering :
River flood
Dam rupture
Littoral flood (tide + storm surge)
Estuary sites
Protection is ensured by :
Nuclear Island Platform level ≥ maximum design flood level
Below the platform: closure of all possible pathways to the
rooms containing equipment required for safe shutdown .
NRC – Regulatory Information Conference – 11 March 2010 - Page 5

BLAYAIS (1999) : Examples of damages
Door deformation f Failure of fCCable
opening
NRC – Regulatory Information Conference – 11 March 2010 - Page 6

Flooding
hazards
considered in the
design
Protective
measures
defined by design
f ti
Feedback Analysis of Blayais flood
Severe storm-driven waves coinciding with high estuary
level exceeded the worst-case « design scenario »
•Insufficient height and inadequate shape of the dykes
•Insufficient protection of the underground rooms
containing safety equipment
•Difficulty to detect water in affected rooms
I d t i t
•All 4 units concerned, on-site organizational difficulties
for operation •Inadequate warning system
Effects of the
storm on the
NPP’s support
functions and
surroundings
NRC – Regulatory Information Conference – 11 March 2010 - Page 7
•Temporary site inaccessibility (blocked roadways,
phone communication,…)
•Partial temporary loss of offsite power supplies
•Clogging-up Clogging up of filters of water intake

3. A COMPREHENSIVE REVIEW OF THE
FLOOD RISKS : OUTLINE OF THE
MANAGEMENT PLAN
Flooding
hhazards d
Protective
measures
Flooding effects
on NPP’s
support
functions and
surroundings
NRC – Regulatory Information Conference – 11 March 2010 - Page 8
•Identification of all phenomena, which can result in
a flood at any of the 19 French NPP
•Re-assessment of flood hazards / impacts at each site
•Identification Id tifi ti of f equipment i t tto be b protected t t d
•Review of the existing protective measures
(structures, devices, procedures, organization)
•Modifications Modifications or improvements where required
•Specific Flood procedures developed as necessary
•Analysis of the risks : site inaccessibility ,loss of offsite
power supplies ,heat sink behaviour, communications…
•Means Means defined to avoid them or to cope with them

IDENTIFICATION OF PHENOMENA
Flooding
hazards
PPrior i t to “L “Le Blayais” Bl i ” event t : application li ti of f th the BBasic i SSafety f t
Rule RFS I.2.e
(1)River flood, (2) Dam failure, (3) Tide, (4) Storm surge, (5) Tsunami
New methodology : 8 “additional” phenomena taken into account
(6) Wind-waves on sea
(7) Wind-waves on river or channel
(8) Swelling due to operation of valves or pumps
(9) Water retaining structures (other than dams) deterioration
(10)Circuits or equipment failure
(11) Rainfall on site site, brief and intense
(12) Rainfall on site, regular and continuous
(13) Groundwater rise
+ RRealistic li i
combinations of
phenomena
(1) (2) (3)
NRC – Regulatory Information Conference – 11 March 2010 - Page 9
(6) (7)
(11)
(9)
(13)
(12)
(10)
(8)

Protective
measures
Water
llevell PROTECTION OF EQUIPMENT (1/2)
Set up of a compact “watertight area”
Additional flood hazards
(rainfalls, groundwater rising…)
At all NPPs, protection against water ingress of the
substructures of the buildings containing equipment to be
protected (plugging of openings, reinforced doors,…)
NRC – Regulatory Information Conference – 11 March 2010 - Page 10
Workshop IAEA on External Flooding , Jan 2010, KALPAKKAM – Presentation IRSN 1
Qualified Q lifi d material t i l to t
plug the waterpaths and
openings

Protective
measures
PROTECTION OF NI AND PUMPING
STATION PLATFORMS (2/2) ( )
Protection of structures/devices reviewed :type, height, margins,
settling, stability, safety classification, seismic resistance, powersupply
supply, maintenance maintenance… Improvements where required
Dykes/walls raised or extended or reinforced at some sites
NRC – Regulatory Information Conference – 11 March 2010 - Page 11

Protective
measures
Warning based for
predictable hazards,
Procedures adapted to
site vulnerability
(platform submersion submersion, site
isolation, loss of the
external power supplies,
heat sink filtration
affected by flooding)
FLOODING PROCEDURES
T0
T0 +12h 12h
T0 + 24h
Stand-by phase
Flooding effects
on NPP’s support
functions and
surroundings
Vigilance phase (early actions)
Early warning phase (site
protection preparedness)
Alert phase ( safe state)
At most sites, sites implementation of “flooding” flooding procedures :
Prepare site protection during the warning phases (closure of
paths/openings through dykes and “watertight area”, tanks filling-up,…)
Bring the plants to safe shutdown state if required
NRC – Regulatory Information Conference – 11 March 2010 - Page 12

1999
Le Blayais
flooding
4. OVERALL SCHEDULE OF THE REVIEW
PROCESS
New Design rules set
up by EDF and
reviewed by IRSN
Dec 2001
Advisory
Committee
Re-assessment of flood impact
+ Implementation of upgraded
protection on the 19 NPPs Sites
March 2007
Advisory
Committee
99/12/2 99/12/27 2000 2001
2002 2005 2006 2007 2008
Site Specific
protections
Flooding hazards
Blayais
NRC – Regulatory Information Conference – 11 March 2010 - Page 13
Warning systems
SSubstructures b t t protection t ti
Bugey
Fessenheim
Belleville
St Alban
….
Tricastin
Cruas

5. CONCLUSION : LESSONS LEARNED
1. LE BLAYAIS EVENT USED AS AN OPPORTUNITY TO REASSESS
DESIGN RULES AND IMPROVE NPP PROTECTION AGAINST
EXTERNAL FLOODING
Updated design rules approved by French Safety Authority,
2. A COMPREHENSIVE REVIEW, CARRIED OUT OVER 7 YEARS
INVOLVING VARIOUS SKILLS :R&D, ENGINEERING, OPERATION
3. UPGRADED PROTECTION OF MOST NPP AGAINST FLOOD (about
110 M€ expenses) AND SET UP OF SITE SPECIFIC FLOODING
PROCEDURES
4. A CLIMATE SURVEY PUT IN PLACE IN ORDER TO PERIODICALLY
REASSESS THE NEED FOR ANY ADDITIONAL MEASURES
(basically on a 10 year time frame)
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NRC – Regulatory Information Conference – 11 March 2010 - Page 15
Th Thank k you !