Fukushima Three Mile Island Reactor Accidents: Recovery ......Fukushima & Three Mile Island Reactor...

Fukushima & Three Mile Island Reactor Accidents: Recovery, Cleanup, Lessons, & Future

Foundation For Nuclear Studies

Congressional BriefingMay 18, 2012

Lake H. [email protected]

Disclaimer: Fukushima Information is preliminary especially regarding interpretation of events; opinions expressed are mine and mine alone. Most

Photos Courtesy of TEPCO1L. Barrett Consulting LLC

Energy & Human Societal Evolution• Mankind

– Huts to Modern Cities

• Energy– Simple Fire to Fossil Electricity to Nuclear Electricity

• Energy Density– Diffuse/Intermittent to Concentrated/Continuous

2L. Barrett Consulting LLC

Constant Evolutionary Societal Benefit/Risk Tradeoffs

• No Energy Source is Free From Risk or Cost


Oil Rig Fire Gas Pipeline Explosion Wind Mill Collapse

Coal Mine Accident

Solar Panel Roof FallsCoal Ash Dam Break

Hydro Power Floods2000 Killed 1963

Nuclear Power PlantHigh Density Energy Reactor Core Boils Water


Three Mile Island Units 1 &2March 28, 1979


Three Mile Island Unit‐2 AccidentMarch 28, 1979

6

Relief Valve fails to close

650,000 gallons of highly radioactive water collects

Core is uncovered Fuel overheats/fails/~50% Melt

Operators Believe Reactor

Overfilled and Turn Off Injection Pumps

L. Barrett Consulting LLC

PORV

TMI Core Damage Sequence


Three Mile IslandMarch 28, 1979

Hydrogen Deflagration28psig 13:00

~3M deep water1000R/hr


Offsite Releases Variable & Confused Readings 3/28‐30


Public Confusion Due To Lackof Information & Distrust

10

Company Not BelievedGovernment DistrustedBut NRC Single SpokesmanDenton Made Progress


TMI Precautionary Evacuation• Minimal Releases‐But Great Uncertainty Then

– Mostly Noble Gases, Minor Iodine (<15Ci),

– No detectable Cs release

– Maximum Dose <<1msv, ave ~10 μsv (<1mr) over 2M

• Advisory Evacuation for Pregnant Women & Children on 3/30/79

• ~140,000 People Left for Less than a Week– Cost $71M Paid by Owner Insurance

L. Barrett Consulting LLC 11

PA Evacuation Sites


President Carter ArrivesApril 1

13

Carter, Denton & PA Governor ThornburgPresident Carter In Control Room


Initial Plant Stabilization• Core Cooling Established: 6 Hours

• Cold (<100C) Passive Shutdown:1 Month

• All Accident Water Retained

• Pre‐accident Water Processed and Released to Make Room For Accident Water

• Accident Water Never Released to River

• Airborne Iodine Releases From Auxiliary Building Mitigated


Recovery Cleanup Actions


Building Remediation to Gain Core Access (Barrett Entry)

Phased Unique Air and Water Cleanup Systems Created Based on Best Available

Technology

TMI Damaged Core Removal~1985‐1990


TMI Defueling Sequence


Core Bore Machine Defuel Can Loading Can Transfers

Core Debris StorageTransportShipping Cask

TMI Unit 1 Restarted• Restarted September 18, 1985

– Six and Half Year Process

– Extensive Operator Training

– Plant Modifications

– Extensive Public Regulatory Hearing Process

• One of Best Operating Reactors Today in US


Three Mile Island History• Reactor Scram: 04:00 3/28/79• Core melt and relocation: ~ 05:00 – 07:30 3/28/79• Hydrogen Deflagration: 13:00 3/28/79 • Recirculation Cooling: Late 3/28/79• Phased Water Processing: 1979‐1993:Removed ~1.2MCi Cs137• Containment Venting 43KCi Kr‐85: July 1980• Containment Entry: July 1980• Reactor Head removed and core melt found: July 1984• Start Defuel: October 1985• Shipping Spent Fuel: 1988‐1990• Finish Defuel: Jan 1990• Evaporate ~10 M Liters Processed Water: 1991‐93• Cost: ~$1 Billion (YOE)


Peace On The RiverMost Painful Experiences Are the Most Teachable

We Learned & We Changed

20

20081978

Most Stress is Gone- All are WiserNuclear Power is SaferNuclear Power is More Productive


Fukushima Daiichi Nuclear Power Station

21

Units 5 &6

Dry SNF Storage

CommonSpent Fuel Pool

Units 1‐4


Event Initiation

March 11, 2011•About 14:46, a 9.0 magnitude earthquake struck (Plant design basis earthquake: 8.2)‐ Plant safety systems reportedly function satisfactorily.

•Units 1,2 & 3 Scram & Unit 4 has 100 day old core offloaded into Unit 4 Spent Fuel Pool

•~ 15:45, Seven tsunami waves up to 14 meters high inundated the site, whose design basis was 5.7 meters – the reactors and backup diesel power sit roughly 10 to 13 meters above sea level

•The tsunami & earthquake impacts up and down the northeast coast resulted in tragic loss of 20,000+ lives, damage, and destruction of infrastructure.

22L. Barrett Numark Assoc

Subduction Fault

No Known Seismic Safety DamageDespite Huge Earthquake, Seismic Loads Close to Design

Safety Systems Appeared Functional


Tsunami Waves


Incoming Wave Behind Reactor Building 15:42


Wave Behind Reactor Building 15:43:26






Wave Behind Reactor Building 15:47


Tank Top 15M


Tsunami Size: Main Safety Factor 3/11 15:45


GE Mark I Reactor Building

Spent Fuel Pool

Reactor Vessel

Suppression Pool (Torus)

Primary Containment

Steel Containment Vessel

Secondary Containment

Boiling Water Reactor DesignAt Fukushima Daiichi

Refueling Floor


Browns Ferry Primary Containment


Post Tsunami U 1‐4 Conditions (~15:45)

• No AC Power

• No Unit 1 & 2 DC & Partial Unit 3 DC Power

• No Control room Lighting (flashlights)

• Salt Water Flooded EDGs & Switchgear

• Salt Water Destroyed Service Water Pumps & Switchgear

• Unit 1 Isolation Condenser Valve Problems

• Spotty Instrumentation ReadingsL. Barrett Numark Assoc 34

Battery Power Control of Steam‐Driven Reactor Core Isolation Cooling System In Units 2 &3 (Unit 1 Had

Isolation Condenser which Operators Stopped)

Slide 35

3/11 15:45 to ~ 3/11 24:00 JST

CST?


Unit 1 Isolation Condenser

Actions to Extend DC Power For Control


Scavenged Truck Batteries To Maintain Reactor Instrumentation

Control Room Operator During Black Out

Battery Power Exhausted

Slide 37

Suppression pool (wet well) becomes saturated

3/12 ~02:00 JST

Core Uncovers and starts to overheat


Venting Primary Containment Filter Refueling

Bay

3/12 ~05:30 U1 3/13 ~ 00:00 U23/13 ~ 08:40 U3

Primary Containment Pressure~ ~90psia @02:00 3/12

Uncertain Command & Control Actions & Unit 1 Vent Valve Operability

Core Overheated

H2 & Steam

H2 & Steam

H2 & Steam ?


Hydrogen Leakage Paths


Electrical Penetrations

Hatch Seals

Dry Head Seals

Unit 1 Reactor Building Explosion 3/12 15:31


Unit 3 Reactor Building Explosion3/14 11:15


Unit 1 Reactor Building



43

Before After


Fukushima: Reactor Vessel‐Primary‐Secondary Containment Sequence

Core Over Heats‐Clad Burst ~900C‐Clad Oxidize ~1200C‐H2 Release‐Partial Melt~1800C‐2700C‐Primary Coolant System Overpressure

Vent from Primary Coolant Sys to Primary Containment‐ H2, Steam, & Fission Products (Xe, Kr, I, Cs etc)

No Primary Containment Cooling therefore Primary Containment Overpressure‐Vent to Secondary Containment

44

Primary Coolant System Primary Containment Secondary Containment


Cores Melted, Slumped Into Lower Head& Likely Failed Some CRD Penetrations


Melted Core dropped

Original Core

RPV ThermalFailures

Unit 1 Melt: 3/11~19:00 RPV Fails ~3/12 ~15:00Unit 2 Melt: 3/14 ~20:00Unit 3 Melt: 3/13 ~09:00

Unit 1 RPV Failed Grossly and Units 2&3 Partially

Core on Floor

Unit 2 & 3 Core MeltMostly Retained In Vessel?


Minor Concrete Penetration (if any) due to low Melted Core Mass and Flooded Drywell Floor

Longer Core Cooling With Turbine Driven Pumps Resulted in Less Aggressive Core Melting

Projected Vessel Breach with some Melted core on the floor

U 2 Water Level is 60cm deep with Very High Gamma Levels (~7000R/hr or 70Sv/hr) Likely exposed Melted Fuel 3/12


Unit 1 Core Melt to the FloorLoss of Isolation Condenser Cooling: Early Core Melt & Significant Vessel Penetration & Likely Core Drop

Unit 1 Corium Penetrated ~70cm (30%) of the 260cm thick floor concrete Above the 4cm steel liner plate.

There is 7M of base mat concrete belowthe liner plate

7M Thick

Core Cooling Established With Fire Truck Sea Water Injection


Bleed & Feed Core Cooling Established Seawater Injection Started Using Fire Engine Pump

Shift to Fresh Water Injection: To Dissolve Possible Salt Cakes

Tank

Vapor Venting

Boric Acid

49

Water Core InjectionSeawater Fresh Rate Rate (1/12)

(gpm) (gpm‐tpd)

U1 3/12 20:20 3/25 20 36‐156U3 3/13 13:10 3/25 50 87‐240U2 3/14 16:30 3/26 30 78‐216

Leakage to Reactor Building‐Turbine Bldg‐Intake Structure

Condensation/WaterL. Barrett Consulting LLC

Immediately After Unit 3 Explosion 3/14/11 ~10:00AM JST


Spent Fuel Pool in Reactor Building


~350,000 Gal U4:1331 Assemblies SF ~100 day oldU3:514 Assy SF~ 200 Days oldU2: 587 Assy SF ~120 Days Old

Unit 4 Pool



Unit 4 Spent Fuel Pool Water Sampling

53

Boom Inserting Probe~11‐04‐11

400ml Sample Probe~11‐04‐11L. Barrett Consulting LLC

Unit 4 Spent Fuel Pool


Sampling Indicates Little If Any Fuel DamageLow Cesium Levels in 90Bq/mlWater Level Lowered For Seismic Safety

Unit 4 Explosion: H2 From Unit 3


Unit 4

Unit 3

56

Dry Storage Cask Facility

air inlet

overhead travelling crane

storage cask

transport vehicle

cask trolley

RelativeLow Elevation

57

Body: γ-ray shield (carbon steel)

outer shellprimary lid

secondary lid

basket(borated-aluminum alloy)

cask frame

neutron shield(boron-added resin)

bottom plate

Main featuresCylindrical forged carbon-steel casksSimilarity with transport casks5-115T 52 Assy Casks & 4-96T 37 Assy CasksHelium filledSteel for γ-ray shield/ resin for neutron shieldBorated-aluminum alloy basket for sub-criticality

Storage Only Metal Cask

Dry Storage Facility Was Flooded But All 9 Casks Intact


Fukushima Stabilized

• Established Recirculation Core Cooling– Damaged Pressure Vessel(s) & Containments

• Mitigating Airborne Releases

• Mitigating Water Releases

• Gaining Building Access to Start Recovery Activities

• Managing Solid Wastes

• Maintain Personnel Safety: High Rad Areas

• Addressing Evacuation Zone Situation L. Barrett Consulting LLC 59

Units 1‐4 After U4 Building Explosion 3/16


Unit 4 Fuel Pool‐Side


Unit 3 & Unit 4


Water Spray to Unit 3 Pool Area


Unit 4 Reactor Building Water Injection Boom To Spent Fuel Pool


Release Periods Based On Site Gamma Levels


U2 Internal Explosion?

U3 Gray Smoke?

U3 White Smoke?

uSv/h @Gate @ 1Km

U1 Explosion?

U4 Building Explosion?

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Fukushima Three Mile Island Reactor Accidents: Recovery ......Fukushima & Three Mile Island Reactor...

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