Development and use of SAMGs in the Krško NPP

Transcription

1 REPUBLIC OF SLOVENIA Development and use of SAMGs in the Krško NPP Tomaž Nemec Slovenian Nuclear Safety Administration IAEA TM on the Verification and Validation of SAMGs, Vienna, December 2016

2 CONTENTS Development of Krško NPP plant specific SAMG (2000) Verification and validation of Krško SAMG (2000) SAMG review by IAEA RAMP mission (2001) Post-Fukushima improvements mobile equipment (2011) ENSREG stress tests (2011), Slovenian national action plan (2012) Review of SAMG in Krško NPP Periodic Safety Review (2013) Installation of PAR and PCFVS (2013) SAMG for shutdown modes and spent fuel pool accidents (2014) SAMG description added to Safety analysis report (2016) Validation of SAMG in Krško NPP emergency exercises with use of full scope plant simulator for severe accidents simulation 2

3 Development of Krško SAMG Plant specific analysis Individual Plant Examination, IPE level 1, IPE level 2, IPEEE Containment fragility analysis, deterministic analysis by MAAP Krško NPP specific full scope simulator (based on MAAP) 2000 Plant specific SAMG developed based on WOG generic guidelines: 1. Generic strategies - WOG 2. Plant background documentation 3. Plant specific SAMG setpoints and computational aids (CA) 4. Transitions EOP to SAMG 5. Plant specific procedures 3

4 Krško NPP simulator MAAP used in IPE MAAP integrated into plant specific full scope simulator For normal, abnormal, emergency operation and for severe accidents in real time All the data available in TSC (via SPIS) Simulator used for SAMG validation and in other emergency exercises Progression of the accident depends on actions performed by MCR (TSC) Real time response 4

5 Verification and validation of SAMG Verification to review Krško SAMG consistence with generic WOG SAMG Westinghouse report on verification Validation in 2001 (5 days) - Training and integral exercise for MCR and TSC, Westinghouse report Validation scope Verify SAMG usability in realistic environment Ensure SAMG strategies can be used as planned To identify conflicts/problems prior to formal implementation Hands-on training on SAMG usage for MCR and TSC personnel Transition EOP to SACRG-1 (MCR) to SACRG-2 (TSC command) TSC usage: diagnostic tools (DFC, SCST), guidelines (SAG, SCG), CA Westinghouse recommendation to develop procedure SAMG evaluation and decision making responsibilities 5

6 Validation scenarios Scenarios run on simulator (MAAP code) prior to validation exercise to determine initial conditions, time to reach SAG/SCG entry conditions, time for equipment recovery Validation scenarios: TSC - SBO TSC SBO + cavity flooding line plugged MCR LOCA + failure of safety injection Integrated exercise total loss of FW, failure of PORV opening, failure of containment spray Integrated exercise LOCA + failure of containment integrity Plant FS simulator for severe accidents: core melt, reactor vessel failure, MCCI, containment failure, RM response 6

7 SAMG review by IAEA RAMP mission Conducted in 2001, 5 days, pilot mission IAEA standards NS-R-1, SRS-32 (draft) RAMP objectives: Accident analysis, Development of SAMG, Verification and validation of SAMG, etc. Recommendations regarding SAMG (examples): Assess possible adverse effects of cavity flooding strategy Survivability of NSR equipment considered in SAMG strategies Assess effect of several SAG performed simultaneously Upgrade SAMG also for shutdown states RAMP mission report published on SNSA web site /en/info/reports/reports_of_eu_and_expert_missions/ 7

8 Fukushima accident 11 March

9 Post-Fukushima actions mobile equipment Implemented by June 2011 mechanical and electrical modifications, 32 pcs mobile equipment SAME stored onsite (DEC earthquake and flooding resisting building) with quick connection points to primary system, steam generators, for containment flooding, to river Power sources (mobile DGs, transformers, cables) Compressors (valves control) Transport vehicles EOP Appendices for usage of mobile equipment, also SAMG 9

10 ENSREG stress tests 2011 National report: Accident management measures subsequent to a loss of the core cooling function Accident management measures and installation design features for protecting containment integrity after occurrence of fuel damage Peer review - strong points: SAMG validation by simulator, implementation of RAMP recommendations, SAMG for SFP and shutdown states, emergency exercises using simulator for SA 10

11 Slovenian Post-Fukushima National Action Plan Invite a RAMP mission (after completion of Safety Upgrade Program) to again properly and independently validate the SAMG SAMGs were reviewed after the Fukushima accident, additional equipment was acquired to account for extreme external hazards and harsh working environment immediately after Fukushima SAMGs were revised to include additional scenarios, like significantly damaged infrastructure, prolonged SBO, These scenarios were already tested within the regular exercises with a full scope plant specific simulator The extension of existing SAMGs to all plant states (full and lowpower, shutdown), including accidents initiated in SFPs implemented in

12 Review of SAMG in Periodic Safety Review 2013 Second Periodic Safety Review, Safety factor 4.3 Procedures Review of compliance with Slovenian legislation, WENRA Reference levels, IAEA standards SAMG PSR findings: Contradictory entrance to EOP FR-C.1 and SAMG SACRG-1 SAMG writers guide procedure SAG-8, Negative impacts of flooding the containment SAMG in shutdown modes 12

13 Krško SUP - Installation of PAR and PCFVS Design analysis of severe accident by MAAP (extended SBO, 24 hours without use of DEC and mobile equipment), core melt, reactor vessel failure, MCCI, passive filtered venting 22 PAR installed in containment at different elevations Westinghouse dry filtered venting system, aerosol filters inside containment, iodine filter outside containment Update of SAMG no use of electrical recombiners, passive venting of containment, new setpoints Upgrade of plant simulator, emergency exercise 13

14 SAMG for shutdown modes & SFP accidents 2014 Direct Entry to SAMG from AOP allowed: SAMG at shutdown states: No CET measurements of fuel conditions Containment radiation level criteria in AOP PRI-5, PRI-6 and REF-1 (loss of RH cooling during refueling, LOCA at shutdown) SAMG for spent fuel pool accidents: NEW guidelines SAG-9 Refill the spent fuel pool and SCG-5 Recover Spent Fuel Pool Level Revision of guidelines SAG-5 and SCG-1 - Mitigate fuel handling building releases For guidelines SAG-5, SAG-9, SCG-1 and SCG-5 new rules of usage outside SAMG command to allow TSC to mitigate only SFP accident when reactor core is not damaged 14

15 SAMG description in Safety analysis report 2013 Chapter 20 for Design Extension Conditions and Severe accidents prevention and mitigation DEC systems: PAR, PCFVS Severe accident analysis (MAAP) New Chapter 19.1 Probabilistic Risk Assessment New Chapter 19.2 Severe accident evaluation: Accident management Procedures ARP, AOP, FRP, EOP, EIP (chapter 13), SAMG Severe accident phenomenology (IPE level 2) 15

16 Krško NPP emergency exercises Validation of SAMGs in Krško NPP emergency exercises with use of full scope plant simulator for severe accidents simulation by MAAP 2011 Fukushima scenario earthquake, extended SBO, loss of steam driven AF, exercising use of mobile equipment by new EOP appendices and SAMG 2014 two-day exercise, loss of SFP level, radioactive release 2016 INEX exercise: severe ice storm, continuous loss of all AC power, loss of steam driven AF pump, filtered release to atmosphere via PCFVS SNSA participation in exercises ERDS with more than 1000 plant parameters (from SPIS), NPP also reporting via MKSID information portal 16

17 CONCLUSIONS SAMG development, verification and validation: Krško NPP developed SAMG in 2000 based on PSA level 2 analysis SAMGs verification and validation in 2001, Westinghouse Independent review of SAMG by RAMP mission in 2001 Safety review of SAMG In 2011 ENSREG stress tests, review of SAMG In 2012 Slovenian national action plan In 2013 review of SAMG in the Periodic Safety Review Upgrade of SAMG In 2011 SAMG upgrade with use of mobile equipment In 2013 installation of PAR and PCFVS, included in SAMG In 2014 SAMG upgrade for shutdown states and spent fuel pool accidents Application of SAMG in Krško NPP emergency exercises SA 17

18 Current and future SAM activities in Slovenia SNSA - Licensing the application for a new chapter in SAR on the severe accidents evaluation and the SAMG SNSA - NEW regulations based on WENRA 2014, which introduces requirements for Design extension for existing reactors as well as for Natural hazards Krško NPP Safety upgrade program with impact on SAMG new Emergency control room, Technical support center and upgrade of Operational support center, New DEC train of A-SI, A-RHR, A-AF and heat exchangers Third DG and safety bus and DC batteries are already installed NEW Dry storage facility for spent fuel at Krško NPP Slovenian action plan for post-fukushima improvements Recommendations regarding SAMG from the PSR 18

19 Krško NPP SAMG SACRG-1 Severe Accident Control Room Guideline Initial Response SACRG-2 Severe Accident Control Room Guideline for Transients After The TSC is Functional DFC TSC Diagnostic Flow Chart SAG-1 Inject into the Steam Generators SAG-2 Depressurize the RCS SAG-3 Inject into the RCS SAG-4 Inject into Containment SAG-5 Reduce Fission Product Releases SAG-6 Control Containment Conditions SAG-7* Reduce Containment Hydrogen SAG-8 Flood Containment SAG-9 Refill the Spent Fuel Pool SCST TSC Severe Challenge Status Tree SCG-1 Mitigate Fission Product Releases SCG-2 Depressurize Containment SCG-3 Control Hydrogen Flammability SCG-4 Control Containment Vacuum SCG-5 Recover Spent Fuel Pool Level SAEG-1 TSC Long Term Monitoring SAEG-2 SAMG Termination CA 1 to 8 - Computational Aids 19

20 REFERENCES I. Bašić, Severe Accident Management Program Parts 1 and 2, Regional Workshop on Defence in Depth and Severe Accident: Lessons from Fukushima, Dubrovnik (2012) Krško Individual Plant Examination Level 2, Summary report (1996) SAG Severe accident management guidelines (SAMG) Krško SAMG Validation Report (2001) IAEA Report of the RAMP Mission to the Krško NPP (2001) ENSREG stress tests: Slovenian national report (2011), Country peer review of Slovenia (2012) Slovenian Post-Fukushima National Action Plan (2012) Krško NPP second PSR: PSR2-NEK-4.3 Procedures (2013) 20

21 Thank you for your attention QUESTIONS? 21