Session V
Overview of Fukushima Response Plan
by ELETRONUCLEAR
Paulo Carneiro
Technical Advisor
ANGRA 1 E 2
Technical Directorate
NOVAS USINAS
ANGRA 3
Angra Nuclear Power Station
ANGRA 1 PWR
Power: 640 MW
Technology: Westinghouse
Operation start: Jan. 1985
ANGRA 2 PWR
Power: 1,350 MW
Technology: KWU/ Siemens
Operation start: Jan. 2001
ANGRA 3 PWR
Power: 1,405 MW
Technology: KWU/ Siemens/ Areva
Under construction
Planned start of operation: June 2018
(illustrative view)
RADIOACTIVE
WASTE STORAGE
CENTER
500kV Switchyard
ANGRA 2
ANGRA 1
2
Organizational Approach to Fukushima
Working groups of specialists under guidance of a
Fukushima Response Management Committee;
o gathering and evaluation of information about the accident
onset, development and consequences;
o identification of lessons learned applicable to Brazilian
NPPs;
o safety assessments;
o establishment and management of an executive plan
(studies and projects consolidated in the
ELETRONUCLEAR Fukushima Response Plan);
o participation in national and international discussion forums
about the lessons learned and safety initiatives.
3
Full Integration with Nuclear Industry Initiatives
Brazilian Nuclear Authority
Response to Fukushima – Main Documents
Fukushima Response Plan
(submitted to CNEN in December, 2011)
5-years
Executive Plan
56 Initiatives,
Studies and
Design
Modifications
Estimated US$
150 million
Investments
Performance of
Stress Test
Response to Fukushima – Main Documents
STRESS TEST
submitted to CNEN in
April, 2012
Basis: WENRA
Specification for
Stress Test Report
Response to Fukushima – Main Safety Goals
7
Protection from Hazard Events
External Events
Earthquakes;
Rainfalls;
Landslides;
Tidal Waves;
Tornadoes.
Updating of data basis;
Reevaluation by up-to-date
methodologies;
Probabilistic approach;
Verification of safety margins.
Internal Events
Fire;
Internal Flooding.
Reevaluation considering
up-to-date safety requirements;
Identification of design gaps.
(overall safety evaluation by extended PSA under
development for Angra 1, 2 and 3)
8
Protection from Hazard Events - Results
Earthquakes
Low seismicity site
Largest earthquake 5.2 mb at
250 km (PGA 0.002g at site)
Design PGA 0.10g (p< 10-4/yr)
• preliminary seismic reevaluation
according to EPRI Report
1025287;
• Angra characteirzed as “low
seismicity site”; no special
requirement for further evaluations;
• estimated safety margins of 2.5 for
Angra 1 and 3.0 for Angra 2;
• ongoing extensive updating of
geological and seismological
database (three-years program);
• preliminary GMRS determined for
consideration in the Seismic PSA
(results up to end 2015).
Protection from Hazard Events - Results
Rainfalls and Landslides
Studies considering heavy rains
and seismic induced
landslides concluded; extreme
case of full rupture of slope
covering material evaluated.
Switchyard and discharge
channels may be affected
however no impact on Plants
buildings;
Slopes very steep around the site
Residual and colluvial soils
High rainfall rates
Station protected by slope stabilization
works and slope monitoring system
Recommendation for
enlargement of slope drainage
system and reinforcement of
some stabilization works
(implementation planned to
start until end of 2014);
Protection from Hazard Events - Results
Rainfalls and External Flooding
plant construction level
access to safety
buildings
Angra
1 and 2
+ 5.15m + 5.60m
0 CNG
Reevaluation of flooding level under more severe conditions concluded
(rainfall rate higher than 10,000 years rainfall, blockage of site drainage
channels and circulating water discharge tunnel due to landslides);
Current design flooding level includes sufficient safety margin (up to 75.000
years rainfall); checking and reinforcement of existing flooding
barriers.
11
Protection from Hazard Events - Results
Tidal Waves
• calculation of tidal waves for severe metereological
conditions at Ilha Grande Bay;
• evaluation of jetty stability through physical model;
• expected recommendation of jetty strucutral reinforcement.
Angra NP
Station
Ilha Grande Bay
Bay area, natural protection
from Atlantic Ocean
Protection from Hazard Events - Results
Tornadoes
Tornadoes were not originally considered for
Angra 1 and 2 due to low probability
(~10-7/y);
Tornado hazard study developed for Angra 3;
Impact on Angra 1 and 2 evaluated and
actions plans issued for further evaluation
and/or protection of selected structures and
components.
Internal Fire
Fire Hazard of Angra 1 revised by EPR
(risk based evaluation); design
modification packages under evaluation.
Internal
Flooding
Reevaluation of Angra 1 design against
internal flloding; final report expected for
September 2014.
13
Reevaluation of Cooling Capacity under BDBE
STRESS TEST REPORT
(deterministic approach, no
credit given to special
design features or conditions
at Angra site)
Event Initial Conditions
• Loss of Offsite and Onsite Power (SBO) and Loss of Ultimate Heat Sink (LUHS)
• no possibility of external support within 72h after the accident onset;
Plant in Power Operation
• 100% reactor power;
Plant at Refueling (worst condition for fuel pool temperature)
• full core transferred to fuel pool;
• full utilization of fuel pool storage racks;
14
Evaluation of Station Blackout Scenarios (SBO)
Favorable power supply
conditions in
Angra 1 and Angra 2
Very conservative approach of
considering loss of all AC power
normal design condition
(2 diesel groups per
reactor)
special design conditions for
Angra 1 and 2 (12 diesel
groups for 2 reactors !!!)
Cachoeira
Paulista
São
José
SE
500kV
A2 A1
Angra 2
Angra 1
4 x 50%
2 x 100%
4x
M G
2x
M G
UBP – D1
EDE – 3/4
4x
M G
2x
2x
M G
ULB – D2
EAS – 1A/1B
2,5h
4,0h
Zona
Oeste
Santa
Cruz
SE
“Off-Site
138kV Power”
A2 A1
1st Emergency
Power System
2nd Emergency
Power System
both meet NRC
requirements for
exclusion of SBO
Evaluation of Station Blackout Scenarios (SBO)
•
possibility of SG feeding through mechanically driven pumps (Auxiliary
Feedwater Turbine Pump AF-2 in Angra 1 and Diesel Driven
Emergency Feedwater Pumps LAS in Angra 2);
•
at least 20 hours in Angra 1 and 33 hours in Angra 2 of feeding from,
respectively, Auxiliary Feedwater Tank - AFT and Demineralized Water
Pools - DWP;
•
possibility of AFT and DWP refilling from Fire Fighting Water Supply
System - FFWS (5,000 m3 reservoir, located on an elevation 110 m
above the site grade);
•
possibility of full passive secondary B&F from the FFWS reservoir
(connection before SG becomes empty, in case AF-2 or LAS pump
fails, about 50 minutes).
Evaluation of Loss of Heat Sink Condition
Very conservative approach:
• water intake structures in area of protected sea water (Ilha Grande
Bay);
• water intake structures protected by jetty 8.0 m high above average
seawater level;
• very low probability of water intake blockage to the extent of
impairing minimum flow for residual heat removal;
Main implications for the plants:
• failure of both Emergency Supply Diesel Generator Systems in
Angra 1 (bunkered Emergency Feedwater Diesels in Angra 2 not
dependent on Service Water);
• impossibility of operating the RHR chain.
Overview of Additional Emergency Supply Alternatives
RF435: Mobile DG
(Emergency Power
Supply for essential
Safety Systems)
RF431: Interconnection of
Emergency Power Busbars Angra 1
and 2 (use of DG reserve capacity)
RF435: Mobile DG
(Emergency Power
Supply for essential
Safety Systems)
RF411: Cross-tie of Emergency
Power Busbars
RF421: Interconnection of Diesel
Systems D1 and D2
RF413: alternative
cooling chain for
Emergency Power DG
ANGRA 2
RF422: Mobile DG
(extension of
batteries autonomy)
under evaluation
RF433: Small Hidropower Unit at
Mambucaba River
ANGRA 1
RF412: Mobile DG
(extension of
batteries autonomy)
Additional Alternatives for Reactor Cooling
Alternatives for Reactor Cooling Via Steam Generators
• Design Criteria (based on FLEXapproach);
• Description of Cooling
Alternatives;
• Basic Design.
Additional Alternatives for Reactor Cooling
Mobile Pumps for SG Feeding
Mobile Pumps for Refilling Water
Reservoirs
Mobile Ar
Compressor
for Remote
Valve
Actuation
(Angra 1)
Fire Hoses
Loss of Fuel Pool Cooling
Fuel Pool Temperature Increase after Loss of Cooling
Unit
Angra 1
Angra 2
Plant condition
Time until start
boiling
Time until fuel
element exposure
Power Operation
18 h
190 h
Refueling (*)
9h
63 h
Power Operation
23 h
155 h
Refueling (*)
5h
35 h
(*) limit condition, full core unloaded and full occupation of pool racks
Improvements in design phase:
• Angra 1: external mobile cooling unit
(Westinghouse solution for similar plants);
• Angra 2: fuel pool cooling and restoring of
RHR chain using fire fighting water (AREVA
solution for similar plants)
Mitigation of Radiological Consequences
Containment Protection:
passive H2 catalytic recombiners
already installed in Angra 1 and 2
filtered containment venting under
design for Angra 1 and 2
Severe Accident Management Guidelines (SAMGs):
•pre-Fukushima WOG SAMGs are in the final process of validation, integration with
the Emergency planning procedures and training in Angra 1;
• post-Fukushima AREVA SAMGs in the final process of validation, integration with
the Emergency planning procedures and training in Angra 2;
(other improvements in the infrastructure for emergency planning are being
planned and performed).
22
Thanks for the attention!!!
paucar@eletronuclear.gov.br