Post Fukushima actions in India. Mukesh Singhal, Chief Engineer, Reactor Safety & Analysis Directorate NPCIL

Transcription

1 Post Fukushima actions in India Mukesh Singhal, Chief Engineer, Reactor Safety & Analysis Directorate NPCIL 14 th Meeting of IAEA-TWG on advance technologies, IAEA, Vienna, June 18-20, 2013

2 Presentation Outline Approach Strengthening of DID Reactor Shutdown Seismic trip Decay heat removal Hook-up provisions Water Sources Power Sources Containment Safety Measures Review of EOPs Operator training SAMG Hydrogen management- Passive hydrogen recombiners Containment Filtered venting System Emergency control centre

3 Approach Review by six task forces Stress tests Detailed engineering, analysis by dedicated working group Regulatory review Implementation by stations

4 Safaty Review : Approach Stress test carried out for all NPPs this indicated that margins exist over designed seismic and flood levels Need identified to incorporate automatic reactor trip in all NPPs for seismic event strengthen provisions for beyond design basis accidents addition of water for core/fuel cooling and spent fuel cooling have means for augmentation of on site water supplies have smaller DG sets for charging batteries and running small capacity pumps incorporate provisions for containment safety formalize and implement severe accident management guidelines

5 Shutdown - on seismic event Alarm based on seismic activity are available at all stations for manual shutdown of the plant. Automatic Reactor Trip on sensing seismic event is under implementation at all NPPs (Exist at two stations) Early Tsunami warning system is made available at all coastal sites.

6 Decay Heat Removal Decay heat removal is through Natural circulation in primary side and SGs acting as heat sinks in secondary side. Diesel driven fire water system is available, which injects water directly to SGs and other components in all NPPs. Deaerator inventory can cater to decay heat removal for more than initial 24 hrs.

7 Decay Heat Removal Hook-up Provisions Hook-up systems are provided which is accessed from outside of the reactor building. All the hook-up provisions are progressively implemented in available biennial shutdown. Steam Generator End Shield Calandria Calandria Vault Primary Heat Transport System ECCS Spent fuel storage bay

8 Spent Fuel Storage Bays The time to reach the minimum shielding height of the pool is minimum of 7 days. Hook-up system for SFSB water make-up have been installed at all sites on priority. Strengthening the provisions for monitoring of pool level, bay water temperature and area radiation monitors.

9 Water sources SSE qualified water inventory is ensured for 7 days for all NPPs. Bore wells and surrounding water sources like lake, river etc have been identified.

10 Power Sources Additional air cooled and trolley mounted DGs are being made available at all the stations. Loads identified for post accident scenario : Emergency Lighting, Monitoring of important plant parameters, Pump, Battery Charging, etc. Some stations have been provided with solar powered lighting as an additional measure for emergency lighting. Battery operated devices are provided to monitor critical parameters(core status, containment status and spent fuel pool status) at all stations as part of SBO kit.

11 Containment Safety Measures Hydrogen Management in Containment Hydrogen Mitigation: Passive auto-catalytic re-combiners will be used. Number & Location of PARs is worked out Testing: Testing facility for PARs is available at the R&D Centre.

12 Containment Filtered Venting System Designed to depressurize the containment and preclude its failure due to over pressurization during severe accident. Reduces ground level release. Controlled and filtered release through scrubber tank. Layouts: Plant wise layouts for the system is completed

13 Revision of EOPs & Training of Operators All the plants have emergency operating procedures for including handling of SBO event. The EOPs were revisited to incorporate appropriate modifications in the procedures, in line with the proposed measures for strengthening decay heat removal for extended periods. The station black out EOPs for all stations were revised to cater to the requirements arising out of an extended unavailability of power supplies. EOPs related to natural events like Seismic event, flooding,tsunami etc are also revisited. Required training to operators has been imparted and is a continuous process.

14 Severe Accident Management Guideline (SAMG) Analysis performed for severe accidents initiating from both LOCA and SBO for all IPHWRs. Document made available to all NPPs giving guidelines for utilizing systems incorporated to handle beyond design basis accidents and completion of comprehensive SAMG document is accelerated. Transition from EOP to SAMG and entry criterion and guidelines for systems to be used during BDBA situation; are part of SAMG document. Station specific SAMG document will be prepared based on generic SAMG document.

15 Emergency Control Center Facility Augmenting facilities and capabilities of on-site emergency control centre at all NPPs. ECCF to have adequate space with resting facilities for a period of seven days without any external support. Proposed to use ECCF during plant/site/off site emergency exercises also Accident sequence of LOCA with loss of ECCS and loss of moderator cooling is considered as the governing accident for design of ECCF. ECCF is proposed to be designed to withstand SSE for the site. Finished grade level of the lowest floor of ECCF should be kept above the latest approved design basis flood level for the site. ECCF should have Off site power supply as well as air cooled DG set capable for operating continuously for seven days

16 SUMMARY The envisaged safety enhancements are progressively implemented with regulatory review and concurrence The modifications are incorporated in such a way that actions can be taken from outside plant buildings to supply cooling water to core, auxiliary and support systems, and spent fuel pools All preventive and mitigating measures are qualified for maximum anticipated flood and earthquake at NPP site. Completing implementation of all the recommended safety enhancements (both preventive and mitigating) at all NPPs progressively in their respective biennial shutdowns.

17 Thank You!!