ANGRA 1 E 2ANGRA 3

NOVAS USINASNOVAS USINAS

Session V

Overview of Fukushima Response Planby ELETRONUCLEAR

Paulo CarneiroTechnical AdvisorTechnical Directorate

2

Angra Nuclear Power Station

ANGRA 1 PWRPower: 640 MWTechnology: Westinghouse Operation start: Jan. 1985

ANGRA 2 PWRPower: 1,350 MWTechnology: KWU/ Siemens Operation start: Jan. 2001

ANGRA 3 PWRPower: 1,405 MWTechnology: KWU/ Siemens/ Areva Under constructionPlanned start of operation: June 2018

(illustrative view)

ANGRA 1

ANGRA 2

RADIOACTIVE WASTE STORAGE CENTER

500kV Switchyard

3

Organizational Approach to Fukushima

Working groups of specialists under guidance of aFukushima 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.

Full Integration with Nuclear Industry InitiativesBrazilian Nuclear Authority

Fukushima Response Plan(submitted to CNEN in December, 2011)

56 Initiatives, Studies and Design Modifications

Estimated US$ 150 million Investments

Performance of Stress Test

Response to Fukushima – Main Documents

5-years Executive Plan

submitted to CNEN in April, 2012

STRESS TEST

Response to Fukushima – Main Documents

Basis: WENRA Specification for

Stress Test Report

7

Response to Fukushima – Main Safety Goals

8

Protection from Hazard EventsExternal 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)

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).

Slopes very steep around the site

Residual and colluvial soils

High rainfall rates

Station protected by slope stabilization works and slope monitoring system

Rainfalls and Landslides

Protection from Hazard Events - Results

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);

11

Rainfalls and External Flooding

0 CNG

Angra1 and 2

+ 5.15m + 5.60m

access to safety buildings

plant construction level

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.

Protection from Hazard Events - Results

Tidal Waves

Protection from Hazard Events - Results

• 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.

Ilha Grande Bay

Angra NP Station

Bay area, natural protection from Atlantic Ocean

13

Tornadoes

Protection from Hazard Events - Results

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 FireFire 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.

14

Reevaluation of Cooling Capacity under BDBE

STRESS TEST REPORT

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;

(deterministic approach, no credit given to special

design features or conditions at Angra site)

4 x 50% 2 x 100%

M G

2x

M G

2x

M G

4x

M G

4x

EDE – 3/4

EAS – 1A/1BULB – D2

UBP – D1

SE500kV

SE138kV

A2 A1 A2 A1

CachoeiraPaulista

SãoJosé

ZonaOeste

SantaCruz

2,5h 4,0h

“Off-Site Power”

M G

2x

M GM GM G

2x

2x

M GM GM G

2x

M G

4x

M GM GM G

4x

M G

4x

M GM GM G

4x

EDE – 3/4

EAS – 1A/1BULB – D2

UBP – D1

Angra 2 Angra 1

SE500kV

SE138kV

A2 A1 A2 A1

CachoeiraPaulista

SãoJosé

ZonaOeste

SantaCruz

2,5h 4,0h

“Off-Site Power”

4 x 50% 2 x 100%

Evaluation of Station Blackout Scenarios (SBO)

special design conditions for Angra 1 and 2 (12 diesel groups for 2 reactors !!!)

normal design condition(2 diesel groups per reactor)

1st Emergency Power System

2nd Emergency Power System

Favorable power supply conditions inAngra 1 and Angra 2

both meet NRC requirements for exclusion of SBO

Very conservative approach of considering loss of all AC power

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).

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.

Evaluation of Loss of Heat Sink Condition

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

ANGRA 2 ANGRA 1

RF433: Small Hidropower Unit at Mambucaba River

under evaluation

RF413: alternative cooling chain for

Emergency Power DG

RF422: Mobile DG (extension of

batteries autonomy)

RF412: Mobile DG (extension of

batteries autonomy)

Additional Alternatives for Reactor CoolingAlternatives for Reactor Cooling Via Steam Generators

• Design Criteria (based on FLEX-approach);

• Description of Cooling Alternatives;

• Basic Design.

Mobile Ar Compressor for Remote

Valve Actuation (Angra 1)

Mobile Pumps for SG Feeding Mobile Pumps for Refilling Water Reservoirs

Fire Hoses

Additional Alternatives for Reactor Cooling

Loss of Fuel Pool Cooling

Unit Plant condition Time until start boiling

Time until fuel element exposure

Angra 1

Power Operation 18 h 190 h

Refueling (*) 9 h 63 h

Angra 2

Power Operation 23 h 155 h

Refueling (*) 5 h 35 h

(*) limit condition, full core unloaded and full occupation of pool racks

Fuel Pool Temperature Increase after Loss of Cooling

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).

Thanks for the attention!!!

paucar@eletronuclear.gov.br