GE’s ESBWR

by T. G. Theofanous

ESBWR SA Containment Highlights

BiMACNot to scale

UDW

LDW

+PCCS no LT failure

EVE

ESBWR SA Complexion

CDF~10-8

I 90.2 %

III 1.3%

IV 0.6%

DCH

EVE

BMPRR

I Low Pressure SequencesII Very Late Core DamageIII High Pressure SequencesIV ATWS; 71% No RPV FailureV Containment Bypass

III E/S 1%

N/AN/A

L/NS 78%

I L 27%H: 0.9%, M : 0.1%, L: 99%

L/NS Late Melt, Sprays FailL/S Late Melt, Sprays AvailableE/S Early Melt, Sprays Available

II 7.9%

V 1%

L/S 2%E/S 20%

V, 71% of IV, and RRTreated in L-3 PRARR Residual Risk

V 1%

SA Threats and Failure Modes

• Direct Containment Heating (DCH) Energetic Failure of UDW, Liner (thermal) Failure

• Ex-Vessel Explosions (EVE) Pedestal/Liner Failure, BiMAC-Pipes Crushing

• Basemat Melt Penetration (BMP) BiMAC Thermal Failure (Burnout, Dryout, Melt Impingement)

Direct Containment Heating (DCH)

Representative butnot to scale

DCH: Key features of the geometry

Highly non-uniformgas flow

PSTF Vent Clearing Model

IET CLCH Model

1:1 Scale

DCH in suppression pool containments: model verification basis

and 1:40 scale

Validation Basis: IET DCH Tests… GE PSTF Vent Clearing

CLCH model. Complete transient

Actual blowdowns used as inputs for comparison

PSTF

IET

Comparison to PSTF data

Comparison to IET-1RR and -8 data

Comparison to IET-1 data

Quantification of Loads

0 1 2 3 4 5

2

4

6

8

10

12

Time,s

Pre

ssur

e, b

ar

Upper drywellLower drywellWetwell

0 5 10 15 201

2

3

4

5

6

Time,s

Pre

ssur

e, b

ar

Upper drywellLower drywellWetwell

Regime IHYPOTHETICAL

Regime IICreep Rupture, Bounding

Case F

Case G

More DynamicsRegime III

More sensitivities run on condensation and gas-cooling efficiency, oxidation efficiency, composition of DW atmosphere, etc…

Minimum (bounding) Margins to Energetic DCH Failure

Upper Bound Load

Fragility

Ex-Vessel Explosions (EVE) Pedestal/Liner Failure, BiMAC-Pipes Crushing

Sample SE calculations

• ~ 1 ton/s melt release• 1, 2, 5 m deep pools• Saturated and subcooled water• ~100 kPa s on the floor• 40-150 kPa s on the side walls

Pedestal model in DYNA3D

Verified extensively in High Explosive work

Pedestal damage in DYNA 3D

600 kPa s loading

Pedestal Failure Margins to EVE1 to 2 m Subcooled Pools

Upper Bound Load

Lower Bound Fragility

Significant upwards revision of previously used failure criteria on pedestal walls

BiMAC Structural Configuration

Ie Schedule 80 pipes

DYNA3D model of BiMAC

BiMAC damage in DYNA3D

200 kPa s loading

BiMAC Failure Margins Due to EVE

1-2 m subcooled pools

Upper Bound LoadSaturated Low Level

Upper Bound LoadSubcooled 1-2 m

Lower Drywell

BiMAC Detail

BiMAC Flow Path

Natural convection patterns

The Peaking at the Edge of Near-Edge Channels is the most Limiting

Case No. qup qdn qs qup / qdn qmax / qdn or s

A 63 30 N/A 2.1 1.25

B 120 54 N/A 2.2 1.25

C 178 80 N/A 2.2 1.25

C-3D 238 68 N/A 3.5 1.2

M-3D 286 85 280 3.4 3.0 / 1.4

M 255 125 330 2.0 3.0 / 1.4

N 238 126 340 1.9 3.0 / 1.2

O 168 83 245 2.0 3.0 / 1.2

Summary of Power Split and Peaking Factor Results from the Direct Numerical Simulations (all fluxes in kW/m2 )

The 3D results were confirmed with further calculations that included refined meshes, and a 10-fold increase in viscosity due to addition of the sacrificial concrete.

Sample calculations of turbulent natural convection

Local peaking mechanism

Bounding estimates of thermal loads

Central Channels:

Near-Edge Channels:

2max, /125 mkwq dn 2/100 mkwqdn

2/100 mkwqdn 2max, /300 mkwq dn

2/320 mkwqv 2max, /450 mkwq v

The ULPU facility

Coolability Limits for BiMACApplicability based on similarity of geometries and

flow/heating regimes

Thermal Loads against Coolability Limits in BiMAC Channels

Thermal Margins for BiMACLocal Burnout

1qqCHF

Natural convection boiling in inclined channels: the SULTAN facility

•Vertical and 10 degrees inclination•Characteristic length: 3 and 15 cm•Channel length: 4 m•Pressure: 0.5 MPa•Power levels 100 to 500 kw/m2•Detailed pressure drop data•Top-heated plate, 15 cm wide

Boiling in inclined channels:Sample comparisons for inclinationo10

Natural convection in BiMAC: stable, self-adjusting flow

Thermal Margins for BiMACno-Dryout due to water depletion or flow starvation

Conclusion (3): Summary of containment threats and mitigative mechanisms or systems in place for responding

to them

Threat Failure Mode MitigationDCH Energetic DW Failure Pressure Suppression Vents

Reinforced Concrete Support

UDW Liner Thermal Failure Liner Anchoring System

LDW Liner Thermal Failure Reinforced Concrete BarrierGap Separation from UDW

EVE Pedestal/Liner Failure Dimensions and Reinforcement

BiMAC Failure Pipe Size and ThicknessPipes Embedded into Concrete

BMP&CCI

BiMAC Activation Failure Sensing & Actuation InstrumentationDiverse/Passive Valve Action

Local Burnout Natural Circulation

Water Depletion Natural Circulation

Local Melt-Through Refractory Protective Layer