Presentation on theme: "ANGRA 1 E 2 ANGRA 3 NOVAS USINAS Session V Overview of Fukushima Response Plan by ELETRONUCLEAR Paulo Carneiro Technical Advisor Technical Directorate."— Presentation transcript:
ANGRA 1 E 2 ANGRA 3 NOVAS USINAS Session V Overview of Fukushima Response Plan by ELETRONUCLEAR Paulo Carneiro Technical Advisor Technical Directorate
2 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) ANGRA 1 ANGRA 2 RADIOACTIVE WASTE STORAGE CENTER 500kV Switchyard
3 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.
Full Integration with Nuclear Industry Initiatives Brazilian 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
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)
Protection from Hazard Events - Results Earthquakes Low seismicity site Largest earthquake 5.2 m b 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 Angra 1 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 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.
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% MG 2x MG MG 4x MG EDE–3/4 EAS–1A/1BULB–D2 UBP–D1 SE 500kV SE 138kV A2 A1 Cachoeira Paulista São José Zona Oeste Santa Cruz 2,5h4,0h “Off-Site Power” MG 2x MG MGMG MG MGMG MG 4x MG MGMG MG MG MGMG EDE–3/4 EAS–1A/1BULB–D2 UBP–D1 Angra 2Angra 1 SE 500kV SE 138kV A2 A1 Cachoeira Paulista São José Zona Oeste Santa Cruz 2,5h4,0h “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) 1 st Emergency Power System 2 nd Emergency Power System Favorable power supply conditions in Angra 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 m 3 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) 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 Cooling Alternatives 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 UnitPlant conditionTime until start boiling Time until fuel element exposure Angra 1 Power Operation18 h190 h Refueling (*)9 h63 h Angra 2 Power Operation23 h155 h Refueling (*)5 h35 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).
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