IAEA GIF Design Extension in Post Fukushima Scenario

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1 IAEA GIF Design Extension in Post Fukushima Scenario PrabhatKumar Chairman & Managing Director, BHAVINI Distinguished Scientist Department of atomic energy of India 1

2 Costal Earthquake of higher magnitude Beyond Design and Comprehension?? Extended SBO Common cause failure Multi unit 2

3 Communication Management s dilemma Approach Operators dilemma Observations External support Commercial interest Delay in Decision Hydrogen explosion 3

4 Consequences of Fukishima Water level in RPV decreased core got un-covered Containment could not sustain the high temperature and high pressure Hydrogen, noble gases and volatile fission products leaked out Fuel got un-covered Leading to fire RADIAN IN PUBLIC DOMAIN 4

5 Initiating event was BDB earthquake resulting into Higher than design tsunami Exposure to public cold have been avoided if containment was not breached Design extension 100% systems amenable to ISI Core cooling to be augmented S/D and maintenance of S/D etc. etc. as known today etc. etc. 5

6 Major goals has to be: Condition Monitoring during accidents Operator knows what to do to quench the accident and equipped for this and is trained on simulator to handle accidents Avoid exposure to environment R&D must be enhance in this direction. World has not paid enough attention and not spent much time and money for R&D in this direction 6

7 Tsunami Incidents Forced us to think Extension of design Incidents beyond design parameters Encountering situations in un chartered terrains Decision making and Emergency handling in BDBA scenario Site Emergency Offsite Emergency 7

8 Beyond Design Basis Design Basis Design extension Further design extension???? 8

9 Fukushima Incident Forced us to think beyond design basis scenario and also scenarios beyond conceived situations Common cause failure in multiple systems Multi unit failure Loss of external support Operators dilemma Management s dilemma 9

10 Design extension in PFBR Post Dec 26,2004 Tsunami Post Fukushima 10

11 Lessons from Fukushima to Prevent Severe Accident 1. Earthquakes and tsunamis; 2. Power supplies; 3. Reactor core cooling; 4. Cooling of the spent fuel pool; 5. Accident management for preventing a severe accident; 6. Multiple units accident; 7. Support to operators/ Decision making; 8. water tightness of safety related facilities. 11

12 Safety feature of SFRs need to be readdressed the in wake of lessons from Fukushima The extremely significant earthquake and 15m high tsunami at Dai-ichi NPS exceeded the design consideration Beyond design basis situations are to be considered appropriately 12

13 Safety feature of SFRs need to be readdressed the in wake of lessons from Fukushima Exceeding design limits and unexpected events need to be addressed carefully. Magnitude of the consequence have to be appropriately considered; safety goal may have to be redefined Enhnancement of Defense in Depth philosophy is essential of SFR safety Whether Inherently Safe??? Core melt down? 13

14 Safety Assessment of PFBR in wake of Fukushima incident Scope of Stress Test to determine design extension: Capability of Reactor shut down, maintaining shut down condition and core cooling. Capability to maintain containment integrity under credible BDBA conditions. Condition monitoring in all conditions Affect on storage facilities of spent fuel and fresh fuel assemblies Issue related to storage of large quantity of Sodium. Radiological impact at site and public domain. 14

15 Safety Assessment of PFBR in wake of Fukushima Safety incident Assessment of PFBR Accident Management strategy and Emergency Preparedness. Availability of DG beyond design basis scenario. Possibility of hooking up back up supply in the event of DG not available. Adequacy of approach to plant to handle emergency scenario following DBA. Formation of emergency crew to handle emergency situations and the training. 15

16 Reactor trip on seismic event:» PFBR Site Seismic Values:» OBE : (Horizontal direction)» : (Vertical direction)» SSE : (Horizontal direction)» (Vertical direction) 16

17 Reactor trip on seismic event (contd.):» Existing Seismic Instrumentation at PFBR : The following instrumentation has been provided in the design of PFBR for sensing, recording and controlling functions for seismic events. i) Free Field Sensors (3 nos.) II) Tri-axial Accelerometers (5 nos.) 17

18 Actions after 2004 Tsunami Decision on sea water affected concrete Sea shore protection Engineered outfall Tsunami wall Engineered compound wall Plantation on the beach Rise of FGL of NIB 18

19 INTERGRATED STRUCTURE - STUDIES Studies carried out earlier: Analysis for Layout of the integrated structure of outfall channel for the combined flow of PFBR & MAPS & protection works Wave flume studies for the design of shore protection works Desk studies for design of Outfall channel Desk studies for design of Tsunami protection work Graphical Representation of Integrated Structure Bund m Outfall Channel Sea wall Core m m HWL+ 6.7 m Pitching 19

20 SHORE PROTECTION WORKS - CROSS SECTION Top elevation = RL 9.37m Slope 1:5 20

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23 Outfall Channel/Tsunami bund/shore Protection Tsunami bund Shore protection Outfall Channel 23 23

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25 05/11/09 25

26 Tsunami bund 26

27 KalpakkamTownship TSUNAMI Protection wall 27

28 KalpakkamTownship TSUNAMI Protection wall 28

29 SEA SHORE CASURINA WALL SUBAPUL CASHEW COCONUT Engineered sand dune Proposed Coastal plantation for Kalpakkam as per M. S. Swaminathan Foundation 29

30 Reduction of Tsunami Energy Tree plantation 30

31 Post Fukushima Flooding Review and Design Extension Increased tsunami height Increased tsunami wall Increased size of storm water drains Non return gates in storm water drains Wall around fore bay and sea water pump house Sealing of NIB penetrations for a higher tsunami Alternative approach road NICB elevation Perpendicular to coast line 31

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33 Site Drainage Cyclone/ Excessive precipitation (243mm/hr) considering 1000yr return period; time of concentration-30 minutes Storm water drainage system Breakage of raw water reservoir Water to remain below power island FGLK Drainage of water Tsunami Impermeable tsunami wall Non return water gates in storm water drains 33

34 Different level of rise at different places at site Surge and wave run-up are function of: Beach profile Bathemetry Flow blockages near estuary Wave strike on the beach 34

35 Tsunami water entry routes Through Tsunami wall Above tsunami wall Storm water drains Sea water pump house Tunnel and trenches 35

36 Water entry through Intake tunnel High level in fore bay High level in SWPH Reactor trip FGL at power island is 2.5 meter below NIB FGL Raise fore bay level by 2.5m Construct 2.5m wall around SWPH 36

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39 Actions Cable entry points raised and sealed Cable and pipe tunnel covers were sealed Manhole cover levels increased Elevation of ventilation openings for outdoor trenches and tunnels raised Instrumentation to identify flooding Adequate training to operators for emergency scenarios Communication equipment elevation and adequacy Contingency plan to be reviewed yearly Gate and flood level design strengthened Weed flushing 39

40 Over all Night View PFBR the pride of nation 40