NES Infotag 2014

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1

Paul Scherrer Institut, Switzerland

NES Infotag, 27.03.2014

H.-M. Prasser

Laboratory of Thermal Hydraulics

NES Infotag 2014

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NES Infotag, 27.03.2014 2

Scope and strategy of LTH

• Model development & validation for reactor and plant Thermal Hydraulics

• Containment Thermal Hydraulics

• Passive safety systems

• Severe accidents, aerosols, iodine, accident management methods

• Innovative fluid dynamic instrumentation

• Support and integrate education (Master in Nuclear Engineering)

Laboratory of Thermal Hydraulics

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• Solution of the Navier-Stokes equation (1D, 2D, 3D, steady-state, transient)

 Velocity field in (very) complex geometries, forces acting on structures + Energy conservation, heat sources

 Temperature fields in fluid and walls, temperature fluctuations + Two-fluid model

 Two-phase flow, phase transition

+ Transport equations for additional fluid components

 Complex mixing cases + Chemical reactions

 Reactive flows, e.g. combustion, cladding oxidation, severe accidents + Transport equations for particles

 Aerosol flow fields, deposition, re-mobilization + Transport equations for gas-liquid interfaces

 Fundamental studies of boiling, condensation, two-phase flow structure

Theoretical methods

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• Fluid-dynamic models (small, medium, large scale)

 Containment models

 Fuel rod bundle models (adiabatic, heated), steam generator bundles

 Testing of Filtered Containment Venting System

 Simplified reactor models (e.g. for mixing studies)

 Component models (e.g. steam generators, t-junctions) + Media supply (steam, gas, water)

+ Aerosol generators

+ Advanced fluid dynamic instrumentation (+ standard instruments, of course)

 Wire-mesh sensors, neutron imaging, film sensors, infrared techniques, gas sampling techniques with mass spectrometer, special local sensors

+ Aerosol/particle sensors and measuring techniques + Chemical sensors for specific components

+ Fast neutrons for imaging and special measurements

Experimental methods

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VEFITA DRAGON

DRAGON – LINX - VEFITA

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DRAGON – aerosol generator

DRAGON 1

SnO

₂

– plasma torch

DRAGON 2

TiO

₂

, SiO

₂

, Cu – fluidized bed Latex, SiO

₂

, DEHS

¹

– atomizer

+ Steam generator + Mixing chamber

 Model fluid of the containment atmo-

sphere under severe accident conditions

1DEHS = Di-Ethyl-Hexyl-Sebacat

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PANDA – large containment test

ESBWR PANDA

Focus: Gen-III reactors and passive safety systems

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Complex mixing experiments

• Containment cooler performance under presence of hydrogen

• HT blockage

• Local H₂ conc.

• Effect of cooler position

PANDA

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ETH MiniPanda Benchmark on the

‚Erosion of a Stratified Layer‘

Duration: July 2012 – March 2013

Purpose: CFD code validation applied to hydrogen management in NPP Participants: ANSYS, GRS, KIT, FZ Jülich/RWTH Aachen (Germany),

IBRAE (Russia), PSI (Switzerland), U.S.NRC (USA)

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Mixing Tee / low side flow

mixing pipe

side branch

J. Kickhofel

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Mixing in reactors

Two pumps running

⇒ Ability to measure mixing in any geometry (e.g. PWR downcomer...) Flat generic model of a boiling water reactor

• Validation of CFX - TRACE coupling (with LRS)

• Cold lake formation and erosion in lower plenum of BWR

• Demonstration for a full 3D BWR model

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Complex mixing, theoretical (1)

FLUENT simulation of ECC injection into PWR reactor pressure vessel

Flow field + temperature field

Feedback of density effects to flow field taken into account

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Complex mixing, theoretical (2)

ThyssenKrupp-Uhde Bio-reactor, 80 – 800 m³ FLUENT (ANSYS)

>1 million cells

Stirrer: sliding mesh

Velocity field Bacteria feedstock

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Particle flows

CFD Euler-Lagrange: Aerosol settling Discrete Particle Tracking

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Aerosol transport and deposition

Flow field Human respiratory tract

Aerosol particle tracking

CFD, Euler-Lagrange particle tracking

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TRISTAN

6 m

Wire-mesh sensor 120x120

1280 Hz

Universal experiment for two-phase flows in pools and bundles (Aerosol scrubbing in SG bundles, suppression pools, FCVS…)

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Strömung im Brennelement

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Advanced instrumentation

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SUBFLOW Loop – fuel rod bundle studies

Single and two-phase flow in a 4x4 rod bundle

• Dynamic gas-liquid interface

• Mixing and cross-flows between sub-channels

• Spacer studies

• Code validation

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Spacer effect on bubbly flow

Upstream of spacer

50 mm

downstream

250 mm downstream

J_L = 0.8 m/s, J_G = 0.008 m/s

Arto Ylönen

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Spacer effect on bubbly flow

Upstream of spacer

50 mm

downstream

250 mm downstream

450 mm downstream

650 mm downstream

J_L = 0.8 m/s, J_G = 0.008 m/s

Arto Ylönen

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Condensate films on containment walls

Julien Dupont (PhD student)

Near IR Film sensor

Far IR camera

→ film temperature

Innovative: Simultaneous contactless film thickness and temperature measurement Contract with nuclear regulators

(ENSI, IRSN)

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Surface temperature

Thickness sensitive element: 100 nm of platinum

Micro-fabricated thermo-resistive elements (clean room) Substrate: glass / aluminum / silicon

2 linear arrays of sensors

→ Profiles + cross-correlation

Size: 500 x 500 µm

P. D’Aleo

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Gas mixing in HTGR

PIV and LIF of He/N₂ mixing (ρ_N2/ρ_He = 7) – contribution to THINS (EU project)

Height, m

Velocity, m/s Turbulent kinetic energy, m²/s² Lines: RANS by FLUENT Points: PIV

He N₂

x = 15 mm

x = 700 mm

x = 15 mm x = 700 mm

Benedikt Krohn (PhD student)

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NES Infotag, 27.03.2014 25

Boiling - High Performance Computing

LES + Interface tracking + super computing T

_L

= T

_S

T

_L

< T

_S

ve rtic al w all

Dr. Bojan Niceno, Dr. Yohei Sato, Hassan Badreddine (PhD student)

adiabatic, multi-scale

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Imaging with fast neutrons

Output 1.5^.10⁷ n/s (planned 10⁸ n/s) D-D plasma neutron source

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OECD/NEA Sponsored CFD Benchmark Exercise:

Erosion of a Stratified Layer by a Buoyant Jet in a Large Volume

NES Infotag 2014

Paul Scherrer Institut, Switzerland

H.-M. Prasser

Laboratory of Thermal Hydraulics

NES Infotag 2014

Scope and strategy of LTH

Laboratory of Thermal Hydraulics

Theoretical methods

Experimental methods

VEFITA DRAGON

DRAGON – LINX - VEFITA

DRAGON – aerosol generator

DRAGON 1

SnO

– plasma torch

DRAGON 2

TiO

, SiO

, Cu – fluidized bed Latex, SiO

, DEHS

– atomizer

+ Steam generator + Mixing chamber

 Model fluid of the containment atmo-

sphere under severe accident conditions

PANDA – large containment test

Focus: Gen-III reactors and passive safety systems

Complex mixing experiments

PANDA

ETH MiniPanda Benchmark on the

‚Erosion of a Stratified Layer‘

Mixing Tee / low side flow

Mixing in reactors

Complex mixing, theoretical (1)

Complex mixing, theoretical (2)

Particle flows

Aerosol transport and deposition

TRISTAN

6 m

Wire-mesh sensor 120x120

1280 Hz

Strömung im Brennelement

Advanced instrumentation

SUBFLOW Loop – fuel rod bundle studies

Spacer effect on bubbly flow

Spacer effect on bubbly flow

Condensate films on containment walls

Near IR Film sensor

Innovative: Simultaneous contactless film thickness and temperature measurement Contract with nuclear regulators

(ENSI, IRSN)

Surface temperature

Micro-fabricated thermo-resistive elements (clean room) Substrate: glass / aluminum / silicon

Gas mixing in HTGR

Boiling - High Performance Computing

LES + Interface tracking + super computing T

= T

T

< T

ve rtic al w all

adiabatic, multi-scale

Imaging with fast neutrons

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