KIT – University of the State of Baden-Württemberg andNational Large-scale Research Center of the Helmholtz Association

Institute for Nuclear and Energy Technologies

www.kit.edu

LIVE‐CERAM experiment: Objectives and status of preparation

A. Miassoedov, X. Gaus-Liu, J. Foit, T. Cron, T. Wenz, S. Schmidt-Stiefel

Karlsruhe Institute of Technology, Germany

17th QUENCH Workshop , KIT Germany, November 22-24, 2011 2

Outline

Objectives of LIVE-CERAM experiment

Difficulties in creating a 8 cm crust layer

Meeting of CEA and KIT and proposal of methods

Performance of three pre-tests (VV1, VV2 and VV3) for the formation of a refractory layer

Summary of the pre-tests

Ongoing activities

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Background and Objectives of LIVE-CERAM experiment

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 temperature during ablation transient Evolution of melt pool temperature during ablation transient

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Expected Behaviour

The initial pure KNO3 layer acts as thermal barrier. The melt will heat up. The KNO3 material can be dissolved by the melt below the melting temperature of pure KNO3.

In the end state, the residual thickness of KNO3 will be compatible with conduction heat transfer and the final power dissipation. The melt will be enriched in KNO3.

The interface temperature between the melt and the residual KNO3 liner should, in the final steady state, reach the liquidus temperature of the actual, final, melt composition.

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LIVE 3D facility

vesse l coo ling

wall inner and outer therm ocouples

m elt pouring

cam era observation crust detection system

heating system

3D 1:5 scaled RPV of a typical German PWR

Surrounded by a cooling vessel to cool the test vessel by water or air

Volumetric heating system Central and non-central melt

pouring Measurements and Instrumentation

- Melt temperature: 60 thermocouples and crust detection lance

- Heat flux: 17 pairs wall temperature. - Crust growth: thermal couples trees in

the melt near the wall- Video cameras and infrared camera- Melt mass and crust mass: weighting

cells- Melt sampling

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Difficulties to generate refractory layer

A 8 cm KNO3 crust layer should be generated at the vessel wall.

8 heating elements

crust crust: 8 cm

crust profile in a volumetrically heated pool: thin and non-uniformly

desired crust profile in the LIVE-CERAM: thick and uniformly

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Solution: elevating the heating elements

Preferred methods: multi-step melt extraction or one-step melt extraction and heterogeneous heating

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Other agreements at the CEA/KIT meeting Geometries: height of refractory line: 435mm, height of ablation pool

385mm Measurements:

Evolution of melt pool temperature: 36 thermocouples Evolution of the interface temperature

Four thermocouple trees for crust temperature and interface temperature (new),

two positions for crust detection lance (new)

Initial ablation conditions: pouring temperature 260°C, maximum melt temperature 330°C, heating power 7kW in the liquid pool, vessel wall externally cooled by water

Steady-state criteria: steady melt temperature and crust temperature at polar angle 52° and 66°

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Pre-test 1 (VV1) : Multi-Step Melt Extraction

0 5000 10000 15000 20000 25000

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100000 5000 10000 15000 20000 25000

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total power

tota

l hea

ting

pow

er [W

]

Time [s]

S1

cooling water flow out

S7

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S3S4

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mass of melt

mas

s of

mel

t [kg

]

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Pre-test 1 (VV1) : Multi-Step Melt Extraction

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polar angle (°)

crus

t thi

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ss (m

m)

azimuth 247.5°

azimuth 67.5°

gap

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Pretest 2 (VV2) : Smoothing the Crust of VV1 and Filling the Gap

Total heating power: 3300W at lower pool

Crust thickness: 6.5cm at top, maximum 14cm

VV1 profileVV2 profile

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Pretest 3 (VV3) : Heterogeneous Heating

Total heating power: 6200W, heterogeneous heating

Crust thickness: 6cm at top, 10cm at middle part and 11cm at bottom

VV3 profile

VV2 profile

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Summary of the Pre-tests The method of pre-test 3 (VV3) gives the best result. A gap is formed between crust and wall due to crust shrinkage

The gap has a width about 1cm. Most of the wall inner temperature thermocouples were destroyed during

crust shrinkage. The heat flux determination based on wall inner temperature will be not

exact. During ablation test, hot melt might penetrate through the crust to the gap

and fill in the gap, so that the local heat transfer condition afterwards will be changed.

By filling the gap before the ablation test can decrease the width of the gap, but not completely get rid of it.

The plug temperatures at the wall can be used instead of the wall inner temperatures for the heat flux determination.

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Ongoing Activities Instrumentation of 4 crust-temperature thermocouple trees,

totally 63 pieces, looking for the possibility of the second position for the

melt/crust boundary temperature measurement with crust detection lance,

Waiting for the reply from CEA about Confirmation of the method to create the refractory layer; Confirmation of the instrumentations; Opinion about the gap filling before the ablation test; Confirmation of the participation of the test and the date of the test

performance. The suitable date for KIT is November 28- December 09, 2011.

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Thanks for your attention