312063H, Reactor, Hydraulic Proportioners, Repair-Parts, US English
Reactor Thermal Hydraulic design
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Transcript of Reactor Thermal Hydraulic design
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UNENE Graduate CourseReactor Thermal-Hydraulics Design
McMaster University
WhitbyMay 5-6, May 26-27,
June 9-10, June 23,2012
1. BWR Reactors - Fukushima
Dr. Nik Popov
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 1
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The Fukushima Daiichi IncidentPlant Design
nucleartourist.com
Building structure Concrete Building Steel-framed Service
Floor
" Containmentu Pear-shaped Dry-Wellu Torus-shaped Wet-Well
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 2
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The Fukushima Daiichi IncidentPlant Design
"
Service Floor
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 3
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The Fukushima Daiichi IncidentPlant Design
"Lifting the Containmentclosure head
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 4
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The Fukushima Daiichi IncidentPlant Design
" Reactor Service Floor(Steel Construction)
" Concrete Reactor Building(secondary Containment)
" Reactor Core" Reactor Pressure Vessel" Containment (Dry well)" Containment (Wet Well) /
Condensation Chamber
Spend Fuel Pool
Fresh Steam lineMain Feedwater
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 5
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The Fukushima Daiichi IncidentAccident progression
" 11.3.2011 14:46 - Earthquakeu Magnitude 9u Power grid in northern Japan failsu Reactors itself are mainly
undamaged
" SCRAMu Power generation due to Fission
of Uranium stops
u Heat generation due to radioactiveDecay of Fission Products
After Scram ~6%After 1 Day ~1%After 5 Days ~0.5%
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 6
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" Containment Isolationu Closing of all non-safety related
Penetrations of the containment
u Cuts off Machine hallu If containment isolation succeeds,
a large early release of fission
products is highly unlikely
" Diesel generators startu Emergency Core cooling systems
are supplied
" Plant is in a stable save state
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 7
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" 11.3. 15:41 Tsunami hits the plantu Plant Design for Tsunami height of
up to 6.5m
uActual Tsunami height >7mu Flooding of
Diesel Generators and/orEssential service water
building cooling the
generators
" Station Blackoutu Common cause failure of thepower supplyu Only Batteries are still availableu Failure of all but one Emergency
core cooling systems
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 8
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" Reactor Core Isolation Pump stillavailableu Steam from the Reactor drives a
Turbine
u Steam gets condensed in theWet-Well
u Turbine drives a Pumpu Water from the Wet-Well gets
pumped in Reactor
u Necessary:Battery powerTemperature in the wet-well
must be below 100C
" As there is no heat removal fromthe building, the Core isolation
pump cant work infinitely
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 9
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" Reactor Isolation pump stopsu 11.3. 16:36 in Unit 1
(Batteries empty)
u 14.3. 13:25 in Unit 2(Pump failure)
u 13.3. 2:44 in Unit 3(Batteries empty)
" Decay Heat produces still steam inReactor pressure Vessel
u Pressure rising" Opening the steam relieve valves
u Discharge Steam into the Wet-Well" Descending of the Liquid Level in
the Reactor pressure vessel
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 10
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" Reactor Isolation pump stopsu 11.3. 16:36 in Unit 1
(Batteries empty)
u 14.3. 13:25 in Unit 2(Pump failure)
u 13.3. 2:44 in Unit 3(Batteries empty)
" Decay Heat produces still steam inReactor pressure Vessel
u Pressure rising" Opening the steam relieve valves
u Discharge Steam into the Wet-Well" Descending of the Liquid Level in
the Reactor pressure vessel
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 11
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" Reactor Isolation pump stopsu 11.3. 16:36 in Unit 1
(Batteries empty)
u 14.3. 13:25 in Unit 2(Pump failure)
u 13.3. 2:44 in Unit 3(Batteries empty)
" Decay Heat produces still steam inReactor pressure Vessel
u Pressure rising" Opening the steam relieve valves
u Discharge Steam into the Wet-Well" Descending of the Liquid Level in
the Reactor pressure vessel
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 12
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" Reactor Isolation pump stopsu 11.3. 16:36 in Unit 1
(Batteries empty)
u 14.3. 13:25 in Unit 2(Pump failure)
u 13.3. 2:44 in Unit 3(Batteries empty)
" Decay Heat produces still steam inReactor pressure Vessel
u Pressure rising
" Opening the steam relieve valvesu Discharge Steam into the Wet-Well
" Descending of the Liquid Level inthe Reactor pressure vessel
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 13
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" Reactor Isolation pump stopsu 11.3. 16:36 in Unit 1
(Batteries empty)
u 14.3. 13:25 in Unit 2(Pump failure)
u 13.3. 2:44 in Unit 3(Batteries empty)
" Decay Heat produces still steam inReactor pressure Vessel
u Pressure rising
" Opening the steam relieve valvesu Discharge Steam into the Wet-Well
" Descending of the Liquid Level inthe Reactor pressure vessel
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 14
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" Measured, and here referencedLiquid level is the collapsed level.The actual liquid level lies higherdue to the steam bubbles in the
liquid
" ~50% of the core exposedu Cladding temperatures rise, but still
no significant core damage
" ~2/3 of the core exposedu Cladding temperature
exceeds ~900C
u Balooning / Breaking of thecladding
u Release of fission products formthe fuel rod gaps
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 15
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" ~3/4 of the core exposedu Cladding exceeds ~1200Cu Zirconium in the cladding starts to
burn under Steam atmosphere
u Zr + 2H20 ->ZrO2 + 2H2u Exothermal reaction further
heats the core
u Generation of hydrogenUnit 1: 300-600kgUnit 2/3: 300-1000kg
uHydrogen gets pushed via thewet-well, the wet-well vacuum
breakers into the dry-well
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 16
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" at ~1800C [Unit 1,2,3]u Melting of the Claddingu Melting of the steel structures
" at ~2500C [Block 1,2]u Breaking of the fuel rodsu debris bed inside the core
" at ~2700C [Block 1]u Melting of Uranium-Zirconium
eutectics
" Restoration of the water supplystops accident in all 3 Units
u Unit 1: 12.3. 20:20 (27h w.o. water)u Unit 2: 14.3. 20:33 (7h w.o. water)u Unit 3: 13.3. 9:38 (7h w.o. water)
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 17
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"Release of fission products duringmelt down
u Xenon, Cesium, Iodine,u Uranium/Plutonium remain in coreu Fission products condensate to
airborne Aerosols
" Discharge through valves into waterof the condensation chamber
u Pool scrubbing binds a fraction ofAerosols in the water
" Xenon and remaining aerosolsenter the Dry-Well
u Deposition of aerosols on surfacesfurther decontaminates air
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 18
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" Containmentu Last barrier between Fission
Products and Environment
u Wall thickness ~3cmu Design Pressure 4-5bar
" Actual pressure up to 8 barsu Normal inert gas filling (Nitrogen)u Hydrogen from core oxidationu Boiling condensation chamber
(like a pressure cooker)
" Depressurization of thecontainment
u Unit 1: 12.3. 4:00u Unit 2: 13.3 00:00u Unit 3: 13.3. 8.41
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 19
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" Positive und negative Aspects ofdepressurizing the containment
u Removes Energy from the Reactorbuilding (only way left)
u Reducing the pressure to ~4 baru Release of small amounts ofAerosols (Iodine, Cesium ~0.1%)u Release of all noble gasesu Release of Hydrogen
" Gas is released into the reactorservice floor
u Hydrogen is flammable
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 20
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" Unit 1 und 3u Hydrogen burn inside the reactor
service floor
u Destruction of the steel-frame roofu Reinforced concrete reactor
building seems undamaged
u Spectacular but minor safetyrelevant
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 21
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" Unit 2u Hydrogen burn inside the reactor
building
u Probably damage to thecondensation chamber
(highly contaminated water)
u Uncontrolled release of gas fromthe containmentu Release of fission productsu Temporal evacuation of the plantu High local dose rates on the plant
site due to wreckage hinder further
recovery work
" No clear information's why Unit 2behaved differently
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 22
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" Current status of the Reactorsu Core Damage in Unit 1,2, 3u Building damage due to various
burns Unit 1-4
u Reactor pressure vessels floodedin all Units with mobile pumps
uAt least containment in Unit 1flooded
" Further cooling of the Reactors byreleasing steam to the atmosphere
" Only small further releases offission products can be expected
The Fukushima Daiichi IncidentAccident progression
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 23
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" Spend fuel stored in Pool onReactor service floor
u Due to maintenance in Unit 4 entirecore stored in Fuel pool
u Dry-out of the poolsUnit 4: in 10 daysUnit 1-3,5,6 in few weeks
u Leakage of the pools due toEarthquake?
" Consequencesu Core melt on fresh air u Nearly no retention of fission
products
u Large release
The Fukushima Daiichi IncidentSpent fuel pools
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 24
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" Spend fuel stored in Pool onReactor service floor
u Due to maintenance in Unit 4 entirecore stored in Fuel pool
u Dry-out of the poolsUnit 4: in 10 daysUnit 1-3,5,6 in few weeks
u Leakage of the pools due toEarthquake?
" Consequencesu Core melt on fresh air u Nearly no retention of fission
products
u Large release
The Fukushima Daiichi IncidentSpent fuel pools
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 25
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" Spend fuel stored in Pool onReactor service floor
u Due to maintenance in Unit 4 entirecore stored in Fuel pool
u Dry-out of the poolsUnit 4: in 10 daysUnit 1-3,5,6 in few weeks
u Leakage of the pools due toEarthquake?
" Consequencesu
Core melt on fresh air
u Nearly no retention of fissionproducts
u Large release" It is currently unclear if release from
fuel pool already happened
The Fukushima Daiichi IncidentSpent fuel pools
May-June 2012 UNENE - UN804: TH Design BWR Fukushima Dr Nik Popov 26
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Questions?
M J 2012 UNENE UN804: TH Design BWR Fukushima Dr Nik Popov 27