WELCOME AND INTRODUCTORY REMARKS

Transcription

1 WELCOME AND INTRODUCTORY REMARKS Robust Power Workshop , Per Lamell, F

2 SAFETY FIRST Please note where the nearest emergency exits, fire extinguishers, gathering place and defibrillators are. 2

3 AGENDA The Office Nuclear Power in Sweden Forsmark NPP Major event at Forsmark NPP OPC event at F3 May 30, 2013 Fukushima The future for Forsmark NPP An introductory conclusion 3

4 PARTICIPANT FROM FKA NEEA OFFICE NEE Electrical Engineering 50 employed 46 consultants NEEA Electrical Analysis and Plant Engineering (Portfolio investment) Johan Berg NEES System Design Engineering Electrical NEEE Component Design and Documentation Electrical 1 NEEI Component Design and Documentation Electrical 2 Project Sponsor Electrical Analysis Coordination of Electrical Design Maintenance with Electrical Design 4

5 HISTORY OF NUCLEAR POWER IN SWEDEN Research and education (Heavy water, Swedish nuclear weapon program) R1 started July located at KTH 27 meter down in bedrock 300 kw -> 1 MW (AB Atomenergi) R0 Studvik when critical 1959 was a so-called zero-power reactor R2 in Studvik started 1960 (-2005) 1963 first electricity produced R3 in Ågesta (to -73), provided the suburb Farsta (Stockholm) with district heating (Vattenfall and AB Atomenergi) R4 in Marviken outside Norrköping (no operation, oil power plant) 1972 operation of Sweden's first commercial nuclear power plant, Oskarshamn 1 (ASEA-Atom - Merger of the Asea nuclear power department and AB Atomenergi's technical department) 5

6 HISTORY OF NUCLEAR POWER IN SWEDEN CONT. NET POWER Ringhals NPP RAB (Main owner: Vattenfall AB) R1 (BWR, 865 MW, in op. 1976, planning to close 2020) R2 (PWR, 865 MW, in op. 1975, planning to close 2019) R3 (PWR, 1064 MW, in op. 1981) R4 (PWR, 1130 MW, in op. 1983) Forsmark NPP FKA (Main owner: Vattenfall AB) F1 (BWR, 984 MW, in op. 1980) F2 (BWR 1120 MW, in op. 1981) F3 (BWR, 1167 MW, in op. 1985) Oskarshamn NPP OKG (main owner: Uniper/EON) O1 (BWR, 473 MW, in op. 1972, shut down 2017) O2 (BWR, 638 MW, in op. 1974, shut down 2015) O3 (BWR, 1400 MW, in op. 1985) Barsebäck NPP (main owner: Uniper/EON) B1 (BWR, 600 MW, in op. 1975, shut down 1999 in decom.) B2 (BWR, 600 MW, in op. 1977, shut down 2005 in decom.) 6

7 FORSMARK PLANT AND VILLAGE 7

8 FORSMARK SITE Forsmark 1 Forsmark 2 Forsmark 3 Gasturbine 70 kv Switchyard: FT kv for F3 Switchyard: FT kv for F1 and F2 Switchyard: ÄT66-70kV 8

9 MAJOR EVENTS IN FORSMARK Loss of external power and loss of power supply from 2 of 4 diesel generators Forsmark 1 (July 25, 2006) Lightning strike tripped all eight main circulation pumps at Forsmark 2 (June 13, 2008) Lightning strike causing voltage transient in station AC net Forsmark 3, (July 13, 2012 ) Loss of two phases of the external grid during outage shutdown with loss of decay heat removal (May ) 9

10 LOSS OF EXTERNAL POWER AND LOSS OF POWER SUPPLY FROM 2 OF 4 DIESEL GENERATORS FORSMARK 1 (JULY 25, 2006) Unit breaker open X 400 kv 13:20:20 -> 13:42:01 70 kv M Gas turbine X Plant generator 6 kv 500 V A XM Diesel 654A V AC C M Diesel 654A V AC R101.A11 656T101.A11 655R101.A11 656T101.A11 Turbine 655B R102 K1 K1 T1 T8 Blocking XX Blocking X Blocking 655R B101 T8 655R R T1 4 Q29 Q29 T9 656T kva 0,5/0,5 kv T9 656T kva 0,5/0,5 kv Q2 Q2 500 V 655R102.A23 656A T101.A V AC 655R102.A23 656A T101.A V AC

11 LIGHTNING STRIKE TRIPPED ALL EIGHT MAIN CIRCULATION PUMPS AT FORSMARK 2 (JUNE 13, 2008) Normal operation Voltage disrupt DC busbar ESF MCP (Main Circulation Pump) (Energy storage Flywheel) I max 11

12 LIGHTNING STRIKE CAUSING VOLTAGE TRANSIENT IN 662.WD1 STATION AC NET FORSMARK 3, (JULY 13, 2012 ) 677.TD1.A TD1.T1 677.TD1.A UD11.U1 671.BD11.B1.B4 677.UD1 677.UD2.A11.A11 System boarder Safety 677.UD1.U1 643.WD1 660 V AC 671.WA1 677.UD2.U1 671.UD12.U1 677.TD2.T1 677.TD2.A TD2.A11 Non-safety 677.TD1.A UD1 677.UD2.A TD2.A22.A WD1.W1 677.WD2.W1 380 V AC loaded loaded unloaded unloaded A-sub: Unaffected 677UC1 677UB2 Faulty Degraded thyristor module thyristor module 677UD1 och 677UD2 Faulty thyristor module 12

13 LOSS OF TWO PHASES OF THE EXTERNAL GRID DURING OUTAGE SHUTDOWN WITH LOSS OF DECAY HEAT REMOVAL (MAY ) Connected to F2 70 kv switchyard was disconnected Outage for about 10 days 400 kv Residual heat removal pumps trip Phase unbalance protection trip motors - Byron 2 January Byron 1 February 28 Unit breaker: T31-D400-S open (maintenance) T31-E400-S initial closed Important! The generator step-up transformer has a Y0-Δ (400 kv/20.5 kv) coupling. EDG failed to start Simulating of the fault case U L1-L2= 102%, L2-L3= 57% och L3-L1= 78% which gives a mean value of 79%. L1 L2 L3 13

14 TESTING OF THE VOLTAGE REGULATOR SETTINGS AND LIMITER Voltage and current signal to the voltage regulator and limiter 2013 the second year of using of the testing procedure 2012 connected to standby power 70 kv Three phase testing equipment connected 30 May 2013 Connection terminals for an updated testing procedure Current signal to the overload 14 and negative sequence protection

15 RELAY PROTECTION THAT ACTIVATED THE OPENING OF THE UNIT BREAKER AT 400 KV SWITCHYARD AVR Trip Overload Trip signal to open the generator breaker (already open) Trip Negative sequence Step 1. Trip signal to open the unit breaker Trip Negative sequence Step 2. Trip signal to open the generator 15 breaker (already open)

16 MAIN CONTROL ROOM First impression of the event at the control room: The light in the control room was lower Operators heard sounds that was identified as typical of motors running on unbalance voltage. Unit breaker at the 400 kv switchyard signaled both on and off position. Several alarms occurred both from: the switchyard from objects that had tripped due to phase unbalance (rectifiers and induction machines driven objects) residual heat removal pump stopped 16

17 RESTORE OF THE POWER SYSTEM Start EDG and start loading objects in B-train 10:15 Reset of Overload protection (phase unbalance protection) on pumps RHR restored in one train after 17 min Start EDG and start loading objects in A-train 10:18 Start EDG and start loading objects in C-train 10:26 Start EDG and start loading objects in D-train 10:36 All safety trains restored after 35 min Restoration of offsite power 10:44 The offsite power restored 22:00 The parallel 400 kv unit breaker was restored and EDG stopped Compensatory measure 03:07 following day One EDG running on it s own train 17

18 FUKUSHIMA DAIICHI ACCIDENT, MARCH 11,

19 A TOOL BOX OF MITIGATING ACTIONS Design Process Integral testing Electric separation Unbalance protection Transient overvoltage protection (surge arresters) Analysis (simulation) of postulated disturbances V&V Transient registration Supervision Compensatory measures during operation Island operation of DG during lightning and electrical maintenance No major electrical work until the lid is off (decay heat, availability of water) Specific plan during challenging plant modifications Classic approach Analysis of disturbances Reverse approach What 19 can we withstand?

20 ELECTRIC SEPARATION TOOL BOX Feed of one or two trains from standby network Both non-safety and safety busbar Only safety busbar Active protection trigger happy Feed from different locations in the grid (only applicable in some plants) Filter MG-set (or static) Separate between safety and non-safety Separate sensitive equipment (UPS) Electronic switch to be or not to be? Rectifier as a barrier Breaker before rectifier w or w/o automatic restart Cooperation with vendors How to specify at procurement? 20

21 FORMARK PLANNING HORIZON Our mission - Ensure safe and stable long-term operation Investments (target approx MEUR) More focus on maintenance 21

22 AN INTRODUCTORY CONCLUSION Robust power supply system is one of the most essential aspects for safety at nuclear power plants worldwide. This workshop shall discuss the recent progress in achieving a better understanding of "new" electrical phenomena that occurred recently, like Open Phase Conditions. This understanding will lead to improved countermeasures and to an upgraded defence-in-depthconcept. The results of our meeting shall contribute to the progress for a more reliable power supply system in the near future. Welcome! 22

23 QUESTIONS? 23

24 THANKS 24