ANGRA 1 E 2

1
Session V Overview of Fukushima Response Plan by
ELETRONUCLEAR Paulo Carneiro Technical
Advisor Technical Directorate
NOVAS USINAS
NOVAS USINAS
ANGRA 1 E 2
ANGRA 3
2
Angra Nuclear Power Station
(illustrative view)
RADIOACTIVE WASTE STORAGE CENTER
500kV Switchyard
ANGRA 2
ANGRA 1
3
Organizational Approach to Fukushima

• Working groups of specialists under guidance of a
• Fukushima Response Management Committee
• gathering and evaluation of information about the
  accident onset, development and consequences
• identification of lessons learned applicable to
  Brazilian NPPs
• safety assessments
• establishment and management of an executive plan
  (studies and projects consolidated in the
  ELETRONUCLEAR Fukushima Response Plan)
• participation in national and international
  discussion forums about the lessons learned and
  safety initiatives.

4
Full Integration with Nuclear Industry Initiatives
Brazilian Nuclear Authority
5
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
6
Response to Fukushima Main Documents
STRESS TEST
submitted to CNEN in April, 2012
Basis WENRA Specification for Stress Test Report
7
Response to Fukushima Main Safety Goals
8
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)
9
Protection from Hazard Events - Results
Earthquakes

• 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).

Low seismicity site Largest earthquake 5.2 mb at
250 km (PGA 0.002g at site) Design PGA 0.10g
(plt 10-4/yr)
10
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 Recommendation for enlargement of
slope drainage system and reinforcement of some
stabilization works (implementation planned to
start until end of 2014)
Slopes very steep around the site Residual and
colluvial soils High rainfall rates Station
protected by slope stabilization works and slope
monitoring system
11
Protection from Hazard Events - Results
Rainfalls and External Flooding
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.
12
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.

13
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.
Fire Hazard of Angra 1 revised by EPR (risk based
evaluation) design modification packages under
evaluation.
Internal Fire
Internal Flooding
Reevaluation of Angra 1 design against internal
flloding final report expected for September
2014.
14
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

15
Evaluation of Station Blackout Scenarios (SBO)
Favorable power supply conditions in Angra 1 and
Angra 2
Cachoeira
São
Zona
Santa
Cachoeira
São
Zona
Santa
Paulista
Jos
é
Oeste
Cruz
Paulista
Jos
é
Oeste
Cruz
SE
SE
SE
SE

Off
-
Site

Off
-
Site
500kV
138kV
500kV
138kV
Power

Power

Very conservative approach of considering loss of
all AC power
A2 A1
A2 A1
A2 A1
A2 A1
Angra 2
Angra 1
2 x 100
2 x 100
4 x 50
4 x 50
normal design condition(2 diesel groups per
reactor)
2x
2x
4x
4x
1st Emergency Power System
M
G
M
G
M
G
M
G
EDE

3/4
EDE

3/4
UBP

D1
UBP

D1
special design conditions for Angra 1 and 2 (12
diesel groups for 2 reactors !!!)
4x
4x
2x
2x
2nd Emergency Power System
M
G
M
G
M
G
M
G
EAS

1A/1B
ULB

D2
EAS

1A/1B
ULB

D2
both meet NRC requirements for exclusion of SBO
2,5h
4,0h
2,5h
4,0h
16
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 BF from
  the FFWS reservoir (connection before SG becomes
  empty, in case AF-2 or LAS pump fails, about 50
  minutes).

17
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.

18
Overview of Additional Emergency Supply
Alternatives
RF435 Mobile DG (Emergency Power Supply for
essential Safety Systems)
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)
RF411 Cross-tie of Emergency Power Busbars
RF421 Interconnection of Diesel Systems D1 and
D2
RF413 alternative cooling chain for Emergency
Power DG
ANGRA 1
ANGRA 2
RF422 Mobile DG (extension of batteries autonomy)
RF412 Mobile DG (extension of batteries autonomy)
under evaluation
RF433 Small Hidropower Unit at Mambucaba River
19
Additional Alternatives for Reactor Cooling
Alternatives for Reactor Cooling Via Steam
Generators

• Design Criteria (based on FLEX-approach)
• Description of Cooling Alternatives
• Basic Design.

20
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
21
Loss of Fuel Pool Cooling
Fuel Pool Temperature Increase after Loss of
Cooling
Unit Plant condition Time until start boiling Time until fuel element exposure
Angra 1 Power Operation 18 h 190 h
Angra 1 Refueling () 9 h 63 h
Angra 2 Power Operation 23 h 155 h
Angra 2 Refueling () 5 h 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)

22
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).
23
Thanks for the attention!!!
paucar_at_eletronuclear.gov.br