ERMSAR 2012, Cologne March 21 – 23, 2012 Experiments of the LACOMECO Project at KIT A. M IASSOEDOV...

ERMSAR 2012, Cologne March 21 – 23, 2012

Experiments of the LACOMECO Project at KIT

A. MIASSOEDOV 1, M. KUZNETSOV 1, M. STEINBRÜCK 1, S. KUDRIAKOV 2

Z. HÓZER 3, I. KLJENAK 4, R. MEIGNEN 5, J.M. SEILER 6, A. TEODORCZYK 7

1 KIT, Karlsruhe (DE) 2 CEA, Saclay (FR) 3 AEKI, Budapest (HU)4 JSI, Ljubljana (SI) 5 IRSN, Fontenay-aux-Roses (FR)6 CEA, Grenoble (FR) 7 WUT, Warsaw (PL)

ERMSAR 2012, Cologne, Germany, March 21 – 23, 2012

Background

Four KIT large-scale experimental facilities QUENCH, LIVE, DISCO, and HYKA are offered to EU partners through the Transnational Access to Large Research Infrastructures (TALI) Project of the 7th EU FWP: 1 experiment in QUENCH 1 experiment in LIVE 1 experiment in DISCO 3 experiments in HYKA

Investigation of accident scenarios from core degradation to melt formation and relocation in the vessel, melt dispersion to the reactor cavity, and hydrogen related phenomena in severe accidents

LACOMECO activities are strongly coupled to SARNET2

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Selected LACOMECO experiments

QUENCH: QUENCH-16: Slow oxidation of fuel rod bundles in air atmosphere (KFKI / AEKI, Budapest, Hungary together with INRNE Sofia, Bulgaria)

LIVE: LIVE-CERAM: Dissolution kinetics of a pure KNO3 crust by a KNO3/NaNO3 melt (CEA, Grenoble, France)

DISCO: DISCO-FCI: Ex-vessel fuel coolant interaction experiment in the DISCO facility (IRSN, Fontenay-aux-Roses, France)

HYKA:

• UFPE: Upward flame propagation experiment in air-steam-hydrogen atmosphere (JSI, Ljubljana, Slovenia)

• DETHYD: Detonations in partially confined layers of hydrogen-air mixtures (WUT, Warsaw, Poland)

• HYGRADE: Hydrogen concentration gradients effects understanding and modelling with data from experiments at HYKA(CEA, Saclay, France)

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QUENCH facility

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Bundle with 21-31 fuel rod simulators of ~2.5 m length

Electrically heated length: ~1 m; max. power ~70 kW

Fuel simulated by ZrO2 pellets

Quenching (from the bottom) with water or saturated steam

Gas analysis by massspectrometry (H2, steam …)

Fully instrumented to measureT, p, flow rates, water level, etc.

Corner rods removable during tests


QUENCH-16 bundle test on air ingress

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Consequences of possible air ingress into overheated fuel assembly after damaging of RPV or spent fuel container:

acceleration in the cladding oxidation

fuel rod degradation

the release of some fission products, most notable ruthenium

Previous integral air ingress experiments:

CODEX-AIT-1 and CODEX-AIT-2 tests were performed at AEKI in 1998 and 1999 with small bundles

QUENCH-10 performed 2004 at KIT: strong pre-oxidised bundle

PARAMETER SF4 performed 2009 at LUCH/Podolsk: very high temperatures on reflood initiation

Objectives of the QUENCH-16 test

• air oxidation after moderate preoxidation in steam

• slow transition in high temperature air with following temperature excursion

• role of nitrogen under oxygen-starved conditions

• hydrogen and nitrogen production during reflood


QUENCH-16: gas consumption during air ingress and gas release during reflood

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O2 starvation

N2 consumption

reflood

air ingress


QUENCH-16 summary

Compared to QUENCH-10, the QUENCH-16 test was performed with lower pre-oxidation, longer oxygen starvation during air ingress and reflood initiation at lower temperatures

Maximal clad oxide thickness before air ingression 130 µm

Oxygen starvation duration 835 s on the end of air ingress

Temperature escalation from 1800 K to 2420 K upon reflood initiation

Release of 24 g nitrogen during reflood compared to 29 g consumed during oxygen starvation period

Significant hydrogen release during reflood: 128 g

Solidified partially oxidised melt between 300 and 500 mm, relocated from upper elevations 500 – 800 mm

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LIVE facility

1:5 scaled RPV, Ø1 m, wall thickness ~30 mm cooling vessel to allow cooling by water or air heating furnace of ~220 l volume volumetric heating system maximum temperatures of up to 1100 °C central and non-central melt relocation

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Instrumentation thermocouples boundary layer temperature measurements video (optical and IR) cameras recording of the power input extraction of melt sample

Pouring spouts


Background Design of refractory liners for core catchers and for protection of concrete walls

(applications for LWRs and for LMFBRs).

Development of model calculations for corium – refractory material interaction

Few data on corium-refractory material interaction

No detailed transient data available for the corium-refractory material interaction for 2D geometry

The objective is to simulate ablation process of a high-melting temperature refractory material by low-melting temperature corium KNO3 as refractory material (melting temperature ~334 °C) and a KNO3+NaNO3

melt at, initially, the eutectic composition (melting temperature ~220 °C) as corium

Provide data for transient corium-refractory material interaction

– Evolution of boundary layer temperature during ablation transient

– Evolution of melt pool temperature during ablation transient

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Background and objectives ofLIVE-CERAM experiment


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Polar angle, °

Crus

t thi

ckne

ss, m

m

before ablation

Ablation 1, 7 kW

Ablation 2, 15 kW

Crust thickness profile evolutionin LIVE-CERAM

Ablation phase 1: 7 kW dissolved KNO3: 39 kg KNO3 in melt:

– original melt: 51%– final melt: 60%

Ablation phase 2: 15 kW dissolved KNO3: 24 kg KNO3 in melt:

– original melt: 58.2%– final melt: 62%

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8 cm thick KNO3 refractory wall was created by lifting the heating coils 63 mm higher power density in the

lower part of the vessel


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Time, s

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pera

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max. melt temp

Interface temp

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Time, sTe

mpe

ratu

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max. melt temp

Interface temp

LIVE-CERAM: progression of melt temperatures and interface temperatures

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Ablation phase 1 Ablation phase 2


DISCO-FCI background and objectives

Experiment similar to those made for DCH, but with water in the pit data for the validation of the codes in geometrical situationcloser to the reactor ones than all other available data

– Bridges the gap between DCH and ex-vessel FCI issues

Valuable information for several SARNET2 WPs

– Melt fragmentation processes for high velocity melt jets obtained by a precise analysis of the size of the debris found (WP7.1, WP5.3)

– Pressurization of the pit and containment during the mixing (WP7.1)

– Debris bed characteristics important for coolability:shape, porosity, debris size distribution (WP5.3)

– Melt and water dispersion out of the pit during the process:initial conditions for MCCI (WP6)

– Oxidation of the iron to be compared with cases without water:impact of water on DCH (WP7.1)

– Hydrogen production and potential impact of water for combustion (WP7.2)

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Design of the DISCO-FCI experiment

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Vmelt = 0.0026 m³

Vwater = 0.125 m³

Vw/Vm = 48


DISCO-FCI: Main results

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Particle Size

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Mas

s [g

]

Pressures in the cavity

Containment temperatures

Particle size distribution

MC3D analysis at IRSN


HYKA facilities for hydrogen research

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Analysis of H2 distribution and combustion processes in severe PWR accidents and BWR incidents

Provision of an adequate scientific basis for reliable hydrogen risk reduction in NPPsA3

A1

A6

Parameters of the test vessels A1: 110 m3, 100 bar A3: 30 m3, 60 bar A6: 23 m3, 40 bar


UFPE: Upward flame propagation experiment in hydrogen-air-steam atmosphere

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Objectives: Scaling of H2 combustion in NPP containments for code validationsMethod: To compare dynamics of the combustion process with similar THAI testsObjects for scaling: PWR HYKA-A2 THAIBlind numerical calculations will be performed within SARNET2

PWR THAIHYKA-A2

Volume: 125000 m3 (SF=2100) 220 m3 (SF=3.7) 60 m3 (SF=1)Diameter: 50 m (SF=16) 6 m (SF=1.9) 3.2 m (SF=1) Height: 63 m (SF=7) 9.1 m (SF=1) 9 m (SF=1) H/D: 1.3 1.5 2.8 Aspect Ratio

Scaling Factor (SF)

ERMSAR 2012, Cologne, Germany, March 21 – 23, 2012 17

Initial conditions: pressure p = 1.5 bar temperature t = 90 oC steam concentration 25 vol. % hydrogen concentration 10 vol. %

Integral characteristics to be compared:Max. pressure: pmax = 5 bar ???Max. temperature: tmax = 900 oC ???Time of combustion: tc = 4.5 s ???

THAI HYKA-A2

Scientific questions: (1) if two experiments are performed in similar facilities of different volumes, with similar experimental conditions, what are the observed qualitative and quantitative differences?

(2) how can experimental results obtained in scaled-down experimental facilities be extrapolated to NPP containments

hidden before blind calculations will be finished

UFPE: Upward flame propagation experiment in hydrogen-air-steam atmosphere


HYGRADE: Hydrogen concentration gradients effects

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Objectives: (1) Flame acceleration and quenching experiments with concentration gradients in obstructed geometry in large scale offered by HYKA-A3 vessel

(2) To provide high quality experimental data on overpressures and flame propagation velocities required for numerical code validationsMethod: to register dynamics of the combustion process, to measure energy

(heat) losses (by pressure measurements)Facility: HYKA-A3 (V=33 m3, H=8 m, D=2.35 m)

A3 vessel Internal obstacles Hydrogen injection systen

Ignition


HYGRADE: Hydrogen concentration gradients effects

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Current state: (1) Ten combustion experiments were performed (2) Data processing is in progress (3) Numerical simulations to be started

Main results: (1) Hydrogen distribution experiments were performed in order to create a relatively stable vertical hydrogen concentration gradients from 4 to 13%H2 and from 13 to 4% H2

(2) Flame propagation experiments for upper and lower ignitions with positive and negative hydrogen concentration gradients showed that no quenching phenomena in large scale occurred

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H2 / %

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12.01.2012 (2) +13.01.2012 H2

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H2 / %

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09.01.2012 + 10.01.2012H2

positive

H2-concentration gradients

negative gradient 12 – 6 %

Pressure and temperature records

negative

Flame trajectory

Ignition

t, s

h, m7.576.565.55

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44.5


DETHYD: Detonation in partially confined layers of hydrogen-air mixtures

Objectives: To find experimentally the critical conditions for DDT and detonation propagation in partially confined layers of hydrogen-air mixtures To provide high quality experimental data on overpressures and flame

propagation velocities required for numerical code validationsMethod: To register dynamics of the detonation process, records of soot tracks (l), max. pressure (PCJ)Facility: HYKA-A1 (V=100 m3, L=12 m, D=3.3 m) in a box of 9x3x0.6 m

Experimental set-up:

Uniform mixture (30%H2-air) Stratified mixtures (20-35%H2 at the top and 0- 4%H2 in air at the bottom)

Test layer 30 cm


DETHYD: Detonation in partially confined layers of hydrogen-air mixtures

Current state: (1) Ten detonation experiments are performed (2) Data processing is completed and report is issued

Main results: The critical layer thickness for detonation propagation in a semi-open, uniform, stoichiometric hydrogen-air mixture is greater than approximately h* > 3 cm. This critical value corresponds to the ratio do detonation cell size λ as h* ≈ 3λ.

The critical hydrogen concentration for steady-state detonation propagation in a stratified layer of H2-air mixture was measured of about 16.6 %. It also requires h*=8.5-14 cm of layer thickness or ~3-4 detonation cells across the layer.

High speed movie

Uniform mixture (30%H2-air) Stratified mixtures (20-35%H2 at the top and 0- 4%H2 in air at the bottom)

Pressure-time history

Detonation cell structure

H2-concentration gradient Maximum pressure vs. distance

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31%H2

27%H2

26%H2

25%H2

Maximum hydrogen concentration

Detonation cell structure


Acknowledgements

The authors gratefully acknowledge funding by Euratom to support the work within LACOMECO project

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… and finally

Thank you for your attention!

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ERMSAR 2012, Cologne March 21 – 23, 2012 Experiments of the LACOMECO Project at KIT A. M IASSOEDOV...

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Transcript of ERMSAR 2012, Cologne March 21 – 23, 2012 Experiments of the LACOMECO Project at KIT A. M IASSOEDOV...