法國(guó)阿海琺公司對(duì)福島核事故的評(píng)價(jià)PPT課件

1、The Fukushima Daiichi Incident 1. Plant Design Fukushima Daiichi (Plant I) Unit I - GE Mark I BWR (439 MW), Operating since 1971 Unit II-IV - GE Mark I BWR (760 MW), Operating since 1974第1頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 1. Plant D Building structure Concrete Building Steel-framed Service FloorC

2、ontainmentuPear-shaped Dry-WelluTorus-shaped Wet-Well第2頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 1. Plant DesignService Floor第3頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 1. Plant DesignLifting the Containment closure head第4頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 1. Plant DesignReactor Service Floor(Steel Construc

3、tion)Concrete Reactor Building(secondary Containment)Reactor CoreReactor Pressure VesselContainment (Dry well)Containment (Wet Well) / Condensation Chamber Spend Fuel PoolFresh Steam lineMain Feedwater第5頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progression14:46 - EarthquakeuMagnitude 9uPower

4、grid in northern Japan failsuReactors itself are mainly undamagedSCRAMuPower generation due to Fission of Uranium stopsuHeat generation due to radioactive Decay of Fission Products After Scram 6% After 1 Day 1% After 5 Days 0.5%第6頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionContainmen

5、t IsolationuClosing of all non-safety related Penetrations of the containmentuCuts off Machine halluIf containment isolation succeeds, a large early release of fission products is highly unlikelyDiesel generators startuEmergency Core cooling systems are suppliedPlant is in a stable save state第7頁(yè)/共32

6、頁(yè)The Fukushima Daiichi Incident 2. Accident progression11.3. 15:41 Tsunami hits the plantuPlant Design for Tsunami height of up to 6.5muActual Tsunami height 7muFlooding of Diesel Generators and/or Essential service water building cooling the generatorsStation BlackoutuCommon cause failure of the po

7、wer supplyuOnly Batteries are still availableuFailure of all but one Emergency core cooling systems 第8頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionReactor Core Isolation Pump still availableuSteam from the Reactor drives a TurbineuSteam gets condensed in the Wet-WelluTurbine drives a

8、PumpuWater from the Wet-Well gets pumped in ReactoruNecessary: Battery power Temperature in the wet-well must be below 100CAs there is no heat removal from the building, the Core isolation pump cant work infinitely第9頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionReactor Isolation pump s

9、topsu11.3. 16:36 in Unit 1 (Batteries empty)u14.3. 13:25 in Unit 2(Pump failure)u13.3. 2:44 in Unit 3 (Batteries empty)Decay Heat produces still steam in Reactor pressure VesseluPressure risingOpening the steam relieve valvesuDischarge Steam into the Wet-WellDescending of the Liquid Level in the Rea

10、ctor pressure vessel第10頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionReactor Isolation pump stopsu11.3. 16:36 in Unit 1 (Batteries empty)u14.3. 13:25 in Unit 2(Pump failure)u13.3. 2:44 in Unit 3 (Batteries empty)Decay Heat produces still steam in Reactor pressure VesseluPressure rising

11、Opening the steam relieve valvesuDischarge Steam into the Wet-WellDescending of the Liquid Level in the Reactor pressure vessel第11頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionReactor Isolation pump stopsu11.3. 16:36 in Unit 1 (Batteries empty)u14.3. 13:25 in Unit 2(Pump failure)u13.3.

12、 2:44 in Unit 3 (Batteries empty)Decay Heat produces still steam in Reactor pressure VesseluPressure risingOpening the steam relieve valvesuDischarge Steam into the Wet-WellDescending of the Liquid Level in the Reactor pressure vessel第12頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionRea

13、ctor Isolation pump stopsu11.3. 16:36 in Unit 1 (Batteries empty)u14.3. 13:25 in Unit 2(Pump failure)u13.3. 2:44 in Unit 3 (Batteries empty)Decay Heat produces still steam in Reactor pressure VesseluPressure risingOpening the steam relieve valvesuDischarge Steam into the Wet-WellDescending of the Li

14、quid Level in the Reactor pressure vessel第13頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionReactor Isolation pump stopsu11.3. 16:36 in Unit 1 (Batteries empty)u14.3. 13:25 in Unit 2(Pump failure)u13.3. 2:44 in Unit 3 (Batteries empty)Decay Heat produces still steam in Reactor pressure V

15、esseluPressure risingOpening the steam relieve valvesuDischarge Steam into the Wet-WellDescending of the Liquid Level in the Reactor pressure vessel第14頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionMeasured, and here referenced Liquid level is the collapsed level. The actual liquid leve

16、l lies higher due to the steam bubbles in the liquid50% of the core exposeduCladding temperatures rise, but still no significant core damage2/3 of the core exposeduCladding temperature exceeds 900CuBalooning / Breaking of the claddinguRelease of fission products form the fuel rod gaps第15頁(yè)/共32頁(yè)The Fu

17、kushima Daiichi Incident 2. Accident progression3/4 of the core exposeduCladding exceeds 1200CuZirconium in the cladding starts to burn under Steam atmosphereuZr + 2H20 -ZrO2 + 2H2uExothermal reaction furtherheats the coreuGeneration of hydrogen Unit 1: 300-600kg Unit 2/3: 300-1000kguHydrogen gets p

18、ushed via the wet-well, the wet-well vacuum breakers into the dry-well 第16頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionat 1800CUnit 1,2,3uMelting of the CladdinguMelting of the steel structuresat 2500CBlock 1,2uBreaking of the fuel rodsudebris bed inside the coreat 2700CBlock 1uMeltin

19、g of Uranium-Zirconium eutecticsRestoration of the water supply stops accident in all 3 UnitsuUnit 1: 12.3. 20:20 (27h w.o. water)uUnit 2: 14.3. 20:33 (7h w.o. water)uUnit 3: 13.3. 9:38 (7h w.o. water)第17頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionRelease of fission products during m

20、elt downuXenon, Cesium, Iodine,uUranium/Plutonium remain in coreuFission products condensate to airborne AerosolsDischarge through valves into water of the condensation chamberuPool scrubbing binds a fraction of Aerosols in the waterXenon and remaining aerosols enter the Dry-WelluDeposition of aeros

21、ols on surfaces further decontaminates air第18頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionContainment uLast barrier between Fission Products and EnvironmentuWall thickness 3cmuDesign Pressure 4-5barActual pressure up to 8 barsuNormal inert gas filling (Nitrogen) uHydrogen from core ox

22、idationuBoiling condensation chamber(like a pressure cooker)Depressurization of the containmentuUnit 1: 12.3. 4:00uUnit 2: 13.3 00:00uUnit 3: 13.3. 8.41第19頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionPositive und negative Aspects of depressurizing the containmentuRemoves Energy from t

23、he Reactor building (only way left)uReducing the pressure to 4 baruRelease of small amounts of Aerosols (Iodine, Cesium 0.1%)uRelease of all noble gasesuRelease of HydrogenGas is released into the reactor service flooruHydrogen is flammable第20頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progress

24、ionUnit 1 und 3uHydrogen burn inside the reactor service flooruDestruction of the steel-frame roofuReinforced concrete reactor building seems undamageduSpectacular but minor safety relevant第21頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionUnit 2uHydrogen burn inside the reactor building

25、uProbably damage to the condensation chamber(highly contaminated water)uUncontrolled release of gas from the containmentuRelease of fission productsuTemporal evacuation of the plantuHigh local dose rates on the plant site due to wreckage hinder further recovery workNo clear informations why Unit 2 b

26、ehaved differently第22頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 2. Accident progressionCurrent status of the ReactorsuCore Damage in Unit 1,2, 3uBuilding damage due to various burns Unit 1-4uReactor pressure vessels flooded in all Units with mobile pumpsuAt least containment in Unit 1 floodedFurther cooli

27、ng of the Reactors by releasing steam to the atmosphereOnly small further releases of fission products can be expected第23頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 3. Radiological releasesDirectly on the plant siteuBefore Explosion in Unit Block 2 Below 2mSv / h Mainly due to released radioactive noble ga

28、ses Measuring posts on west side. Maybe too small values measured due to winduAfter Explosion in Unit 2 (Damage of the Containment) Temporal peak values 12mSv / h (Origin not entirely clear) Local peak values on site up to 400mSv /h (wreckage / fragments?) Currently stable dose on site at 5mSv /h In

29、side the buildings a lot moreuLimiting time of exposure of the workers necessary第24頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 3. Radiological releases第25頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 3. Radiological releasesOutside the Plant siteuAs reactor building mostly intact = reduced release of Aerosols (not

30、Chernobyl-like)uFission product release in steam = fast Aerosol grows, large fraction falls down in the proximity of the plantuMain contribution to the radioactive dose outside plant are the radioactive noble gasesuCarried / distributed by the wind, decreasing dose with timeuNo Fall-out“ of the nobl

31、e gases, so no local high contamination of soil20km around the plantuEvacuations were adequateuMeasured dose up to 0.3mSv/h for short times uMaybe destruction of crops / dairy products this yearuProbably no permanent evacuation of land necessary第26頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 3. Radiological

32、 releasesGRS.de50km around the plantuControl of Crop / Dairy productsuUsage of Iodine pills(Caution, pills can interfere with heart medicine)第27頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 4. Spend fuel poolsSpend fuel stored in Pool on Reactor service flooruDue to maintenance in Unit 4 entire core stored i

33、n Fuel pooluDry-out of the pools Unit 4: in 10 days Unit 1-3,5,6 in few weeksuLeakage of the pools due to Earthquake?ConsequencesuCore melt on fresh air “uNearly no retention of fission productsuLarge release第28頁(yè)/共32頁(yè)The Fukushima Daiichi Incident 4. Spend fuel poolsSpend fuel stored in Pool on Reactor service flooruDue to maintenance in Un