First Experiments at the CIGMA Facility for Investigations

FIRST EXPERIMENTS AT THE CIGMA FACILITY FOR INVESTIGATIONS OF LWR CONTAINMENT THERMAL HYDRAULICS

Yasuteru SIBAMOTO, Satoshi ABE, Masahiro ISHIGAKI, Taisuke YONOMOTO Nuclear Safety Research Center, Japan Atomic Energy Agency

2-4 Shirakata Shirane, Tokai, Ibaraki, 319-1195, Japan [email protected]

ABSTRACT There has been an extensive reorientation of the light water

reactor (LWR) research in Japan since the Fukushima Dai-ichi nuclear power station (NPS) accident, which focuses on severe accidents and accident managements. The Japan Atomic Energy Agency (JAEA) initiated the ROSA-SA project in 2013 for the purpose of studying thermal hydraulics relevant to over-temperature containment damage, hydrogen risk, and fission product transport. For this purpose, the JAEA newly constructed the Containment InteGral Measurement Apparatus (CIGMA) in 2015 for the experiments addressing containment responses, separate effects, and accident managements. Recently, we successfully conducted first experiments using CIGMA to characterize the facility under typical experimental conditions investigating basic phenomena such as buildup of pressure by steam injection, containment cooling and depressurization by internal or external cooling, and density stratified layer mixing by impinging jet. This paper provides an overview of the research programs, the brief description of the facility specification and the outcomes obtained from the first experiments.

INTRODUCTION The nuclear regulation in Japan has been strengthened

concerning prevention and mitigation of severe accident on the basis of experience and knowledge acquired from the Fukushima-Daiichi NPS accident in 2011. The importance of severe accident research, therefore, is reemphasized to predict the accident progression, develop the accident management measures, and establish technical basis for the regulation. From

this background and requirement, the JAEA has started the new research project named ROSA-SA since 2013 for the investigation on thermal-hydraulic phenomena related to over-temperature containment damage, hydrogen risk and aerosol transport which are considered key issues in terms of mechanisms for the containment damage and source term transport [1]. The first two topics are related to the containment failure during the Fukushima NPS accident in which it is presumed that the seal material of top flange was damaged by high temperature and it resulted in hydrogen leakage and explosion in the reactor building. That is the strong motivation of our group to investigate the containment thermal hydraulics.

As the experimental approach for these issues, we constructed a new facility called CIGMA (Containment InteGral Measurement Apparatus). The CIGMA facility has a large-scale test section of cylindrical vessel and high capacity steam supply system to investigate three dimensional behaviors of high temperature gas distribution including hydrogen mixing and steam condensation. The facility is equipped with external and internal cooling system to simulate the temperature and concentration distribution of gas mixture in severe accident condition. The first stage experiments, including shakedown tests, using CIGMA have been successfully completed in 2015. The experiments consist of simple containment pressurization by steam injection, containment depressurization by internal and external cooling system, and hydrogen mixing using helium as simulant. We could acquire the data on fundamental characteristics of facility through these experiments. The facility outline and the brief results of experiment are presented in this paper.

Proceedings of the 2016 24th International Conference on Nuclear Engineering ICONE24

June 26-30, 2016, Charlotte, North Carolina

ICONE24-60515

1 Copyright © 2016 by ASME

THE CIGMA FACILITY

Test Section The objective of CIGMA is to support modelling and

validation of prediction methods for lumped parameter (LP) code and computational fluid dynamics (CFD) code by providing experimental data. Since the thermal-hydraulic behavior related to hydrogen risk has been extensively

investigated in research projects using test facilities such as PANDA [2], MISTRA [3], and THAI [4], the characteristics of those existing facilities were carefully investigated for the design of the CIGMA facility to avoid redundant experiments and obtain new technical findings.

The CIGMA facility is not designed to model any real plants, but it is designed to simulate particular phenomena that will be observed in severe accident. The phenomena include individual and combined thermal hydraulics of gas phase with steam condensation in containment vessel. The modeling of thermal hydraulic phenomena is one of the key factors to evaluate containment integrity. From those considerations, the CIGMA facility is characterized by the capability of conducting high-temperature experiments as well as those on hydrogen risk with CFD-grade instrumentation of high spatial resolution. Table 1 summarizes the design specification of CIGMA and Figure 1 shows the test section vessel. The test section of the CIGMA facility has a cylindrical geometry with 2.5m in diameter and 11m in height with nozzles for fluid injection and discharge, and glass windows for optical measurement. The injection nozzle of steam and gas to the test section allows high temperature gas injection up to 700 °C, of which pressure boundary can withstand up to 300 °C and 1.5MPa. These temperature and pressures conditions seem to be much higher than those of the existing database on containment thermal hydraulic behavior [5].

The upper head and cylindrical wall of the test section vessel have the external cooling section in which the containment is cooled on the outer surface through wall by supplied coolant water. The cooling sections are divided into three parts; upper pool on head, and middle jacket and lower jacket surrounding cylindrical wall. The volume of pool is ~ 7m3 and the gap of jacket flow section is ~ 50 mm. The upper pool and the middle jacket can be connected by removing the bottom plate of pool. It is considered that the external cooling is one of the effective measures of containment vessel cooling because an injection rate is not affected by an internal pressure

Figure 1 Test Section of CIGMA

Table 1 Design specifications of CIGMA Test section Height: 11m

Inner diameter : 2.5m Total volume: 51m3 (including nozzle volume)

Operating specification for pressure vessels

Up to1.5 MPa and 300 °C for vessel boundary wall Up to 700 °C at main steam injection nozzle

Power 200 kW steam generator 120 kW steam superheater 15 KW noncondensable gas superheater

Cooling system Internal water spray External water pool and jacket

Supply system Steam from boiler: up to 260 kg/h Air from compressor: up to 250nm3/h at 0.83MPa Helium from cylinder bundle: up to 1.0MPa

Instrumentation in test section ∼800 sensors: temperature, pressure, flow rate, levels, etc.

PIV (Particle Image Velocimetry: 2-dimensional velocity fields Mass spectrometry: air, steam, and helium gas concentration (~100 sampling tubes and two analyzers)


of containment. In fact, in the review of current regulation process in Japan, water supply into a reactor well (reactor vault) is proposed from several BWR plants as one of the accident management measures to prevent over-temperature containment failure. It is expected that the CIGMA experiments provide a valuable database for these evaluation.

To collect condensed water on inner wall surface, three gutters are horizontally placed along the inner wall at different elevations as shown in Figure 1. The elevations of top and middle gutter correspond to the bottom heights of middle and lower jacket, respectively. The bottom gutter is placed at the boundary line of cylinder and lower head sections. An internal spray cooling system is also operational from the top of the vessel. The water sprayed from the internal nozzle and condensed in the bulk volume of the vessel will fall down and be collected in the sump section. The collected water in this way is delivered to reservoirs and the condensation rates are estimated by the level rise in each tank (See Figure 2 for the flow diagram of the facility).

The instrumentation locations of longitudinal section across the vessel axis are indicated in Figure 1 by small dots. The continuous gas sampling is for the measurement of molar fraction of a gas component using quadrupole mass spectrometer (QMS). The vessel is equipped with ten heated glass windows for the optical measurement using Particle Image Velocimetry (PIV). Five pairs of windows, one is to deliver laser light sheet (LLS) and the other for camera, are distributed over the vessel height allowing for a completed

coverage of region in interest. The window sizes were designed to capture a large field of view (FOV) in around one meter square.

External Supply and Discharge System

Figure 2 shows the flow diagram of the system. Steam and noncondensable gas (helium and air) can be injected through the high capacity superheater that is able to produce superheated gas up to 700 °C in temperature. The main injection pipe is placed at vessel central axis for vertical fluid release. The line has about 14 diameters straight length and contract section to achieve fully developed flow at pipe exit. The pipe wall is made of double-wall to minimize the heat transfer between superheated steam flowing inside the pipe and ambient steam environment. Additional injection line of noncondensable gas is connected to the vessel upper part to create helium rich stratified layer. The gas line is equipped with an individual heater and it will be heated before mixing with steam to avoid undesired steam condensation.

As previously described, four water supply lines are built for internal spray and external cooling system. The flow-regulated coolant can be separately supplied to upper pool and each jacket. The cooling system is once-through, discharging the water after cooling to a drain. The upper pool and jackets are connected to atmosphere through an exhaust pipe line.

Two venting lines are available for depressurization, one is the vent from the vessel top and the other from the vessel lower part, whose downstream are open to atmosphere through a

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Figure 2 Schematic of the CIGMA flow diagram


pressure-tight exhaust silencer. The discharge gas flow rate can be controlled by valve opening and measured in each line. The lower vent line allows to keep a constant pressure without disturbing gas distribution in the vessel. In addition, the vessel has some vacuum breakers to avoid damages due to negative pressure.

Instrumentation

Table 2 gives the instrumentation set up in the containment vessel. The measurements in CIGMA are related to: pressure, temperature (wall and fluid), steam and gas composition, velocity, and condensed water volume. Most of them, except for gas composition and velocity, will be simultaneously recorded in a data acquisition system. Thermocouples and gas sampling tubes are supported by frames made of thin plates and rods which are removable. All these sensors are arrayed with high spatial resolution, the maximum distance between two sensors is shorter than 0.93 m axially and 0.45 m radially.

For gas and steam composition measurement, the system similar to that in the PANDA facility is applied in our system [6]. Several tens of capillary pipes are set up inside the containment, and connected to two outside switching valves to sequentially deliver sampled gas to the QMS connected to each of the two switching valves. The composition is successively analyzed by the QMS for air, helium, and steam. The analyzer must be preliminarily calibrated in the different test loop using mixture gas of known components made by mass flow controller for air/helium and by a dew point sensor for steam. All the pipes (length less than 20 meters) outside the vessel are insulated and heated to prevent undesired condensation. Two analysis systems are installed for about 100 samplings. The

minimum 6 seconds are required for one channel analysis, so that a cycle of 50 samplings and analysis takes about 5 minutes. The specification of the PIV system (for example, the exact region that was mapped) will be presented later in the description of experiment.

FACILITY CHARACTERIZATION TESTS First series experiments were conducted primarily to

characterize the facility under typical experimental conditions including preparation phases. Table 3 summarizes the type of experiments including; simple pressurization up to the maximum operational pressure by steam injection, containment depressurization by internal or external cooling, and density stratified layer erosion by impinging jet. The feasibilities of the measurements for distribution of gas concentration and velocity are carefully checked through these experiments. The outlines of each experiment are briefly described in this section.

Simple pressurization test (PR-SJ series) The test vessel initially filled with atmospheric air was

pressurized by steam injection in this series. The following three experiments were conducted;

- PR-SJ-01: saturated steam injection

Figure 3 Test section pressure for PR-SJ

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cylindrical section sump Wall inner surface Wall outer surface

~20 ~350 ~10 ~120 ~120

Gas composition Sequential sampling then analysis by mass spectrometry

Test Vessel ~100

Condensed water Level swell by differential pressure Three gutters and sump 4

Table 3 Experiment Type

Run ID Description PR-SJ simple pressurization by steam injection CC-SP Depressurization by internal spray CC-PL depressurization by external pool ME-QMS feasibility of gas component measurement by QMS at

high pressure AR-AJ PIV measurement of vertical free jet SE-AJ Helium-rich layer erosion by impinging air jet SE-NJ Helium-rich layer erosion by molecular diffusion


- PR-SJ-02: superheated steam injection (superheating is around 80 K)

- PR-SJ-PL-01: saturated steam injection during external pool cooling (pool water is stagnant).

For all the cases, the steam flow reached the maximum flow rate produced from 200-kW boiler at 1200 s after the injection. The vessel pressure history is shown in Figure 3. The dashed line is the calculation result for PR-SJ-01 by using the HOTCB code [7] which is a lumped parameter code based on mass and energy balances in a vessel. Since the HOTCB has a capacity to consider heat structures (heat capacities and heat transfer to fluid), the vessel wall made of stainless steel was considered in this calculation. Uchida correlation is applied to the heat transfer rate of wall condensation with natural circulation heat transfer by Churchill-Chu. Around 25000s (~7 hours) is required to achieve 1300 kPa of pressure. It is important to know this time because experiment plan is strongly affected by preparation time to establish predetermined initial condition.

Figure 4 shows the fluid temperature distribution in vertical direction along vessel center axis. The sensor locations are presented by small red circles in the vertical cross sectional view of test section in this figure. The legend in the graph represents the designation, positions and types of instrumentations; that is 1st digit means the overall location in vessel, 2nd + 3rd digit the measured quantity, 4th+5th digit the elevation in unit of dm, 6th digit the key of polar angle, 7th to 9th digit the radial distance from vessel axis in unit of mm. For example, CTF75X000 measures fluid temperature (TF) of cylindrical section (C) at 7.5 m height and vessel center (X000). This coding system is similar to that of the THAI facility [4]. The reference height (zero elevation) was placed at the boundary of lower head and sump section. The gas temperatures became the saturation temperature (indicated by black line) from top to bottom, but the temperatures in the bottom sump section, labeled by "BTF", remained subcooled until the end of the experiment. This means that air initially filled in vessel was replaced by injected steam from the top, moved downwardly, and then finally accumulated in the sump section. The result indicates, if pure steam environment is desired as an initial condition, it can be achieved by injecting steam and purging accumulated air from the bottom drain line.

Depressurization test by vessel cooling (CC-SP and CC-PL series)

The purpose of the depressurization test series is to understand the cooling characteristics of internal spray and external pool cooling by water supply. The test vessel was initially filled with steam or steam-air mixture in the pressure of 450 kPa and then water was supplied to the vessel for depressurization. The initial test conditions for each run are summarized in Table 4. Water was injected from the spray nozzle located at the top of vessel in CC-SP, and was poured to the vessel top from outside in CC-PL. The nozzle type B3/4-HMFP-SS9084 (Spraying System Co., Japan), that creates a full cone spray, was used for spray cooling tests. The primary specification of the nozzle was measured by using different apparatus prior to the present experiment. The droplet size was also measured at about 1 m downstream from nozzle exit in this test by using laser diffraction technique. The spread

Figure 4 Temperature distribution for PR-SJ-01

Table 4 Parameters of depressurization tests by cooling Run ID Initial condition

Internal spray

External water supply to pool

Pressure (kPa)

Temp. (C)

gas composition(%)

CC-SP-03 CC-PL-01 CC-PL-03 CC-PL-SJ-01

450 ~150 steam-100

CC-SP-04 CC-PL-04 450 ~150 steam-78+air-22CC-SP-02 CC-PL-02 450 ~170 steam-78+air-22


angle of spray is 90-deg and the Suter mean diameter is 0.15 to 0.4 mm for the flow rate of 2.5 to 3.0 m/h.

The flow rate of spray, depending on vessel internal pressure, increased gradually and approached ~ 2.7 m3/h in the final, while it was 10 m3/h from the beginning for the external cooling tests. The external cooling test with low supply rate of 2.7 m3/h was also conducted in CC-PL-03 for their comparison. CC-PL-SJ-01 was the experiment with the vessel outer surface cooling and steam injection.

Figure 5 compares temperature transient for base case tests with internal spray cooling (CC-SP-03) and external pool cooling (CC-PL-01). There is only steam and no noncondensable gas in the vessel for both cases. The temperature is homogeneous and saturation in CC-SP-03 probably because the steam was well mixed and the vessel wall was directly cooled all over the body by spreading flow of spray. The wall temperatures for spray cooling indicated similar trend to Figure 5 except for the vessel top dome located above the spray nozzle elevation. Meanwhile, the steam temperature for CC-PL-01 initially decreased along the saturation temperature line, while the steam superheating was initiated from 500s after the cooling start. In the CC-PL

experiments, the water poured to the upper pool formed falling liquid film along the wall surface and fell down to the bottom of middle jacket. Hence, the wall beneath the lower jacket elevation, shown in Figure 1, was not cooled significantly by water flow and the wall temperature in lower part remained higher than the saturation. Since the wall temperature drop rate was slower than the vessel depressurization rate due probably to its large heat capacity, it would cause the steam superheat. The inhomogeneous temperature distribution as shown in Figure 5 implies weak natural circulation in the vessel. After the time when the pressure is lower than atmospheric pressure, the top vent valve opened to avoid the damage due to negative pressure. For further investigation on the effects of heat capacity and heat transfer of wall, parametric experiment is necessary combined with numerical analysis.

The pressure transients for all the cases are compared in Figure 6. The time zero of elapsed time is corrected to the onset time when cooling water is supplied. It can be seen overall through the comparison that the depressurization rate is slower for the internal spray cooling case and for the initially air mixing case. Some of spray injection tests showed the pressure increase at first and turn into a decrease at times dependent on test conditions. The pipe connecting the spray nozzle penetrates thick top hatch that must heat up water before

Figure 5 Comparison of steam temperatures between base case tests of internal and external cooling

Figure 6 Comparison of pressure transient among

depressurization tests of internal and external cooling

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injection due to its heat capacity. It is not surprising that the direct cooling by spray resulted in slower depressurization because the spray cooled homogeneously the contents of vessel including wall that has large heat capacity. Indeed, the thermocouples on the wall beneath the spray nozzle indicate the same temperature as saturation although it is not shown here.

It is clearly shown in Figure 6 that the presence of air mixed in steam affects the depressurization rate due to the degradation of condensation by noncondensable gas. We measured gas concentration in the external cooling tests by the present sampling system, although the QMS was not used for the internal spray tests because spray droplets would be sucked into the gas sampling line. The time changes of the vertical

distribution of steam fraction are shown in Figure 7 for the base case test of CC-PL-04. In this experiment, we could use limited sampling tubes placed at the upper half of vessel, so that there is only information of sensors placed above 5000 mm elevation. To make the initial condition, the pure steam environment was established at first by purging air accumulated in the bottom as mentioned above, and then air was injected upward through the main injection nozzle. The partial pressure of air was set at 100 kPa for the total pressure of 450 kPa. The distribution at time -310 s in Figure 7 indicates an initial distribution of steam fraction before cooling. Two graphs in this figure show the vertical distribution along central axis and near wall of vessel. We can easily estimate air fraction from the graph because this is binary system of air and steam. As shown in this figures, the injected air do not reach the vessel top and the upper half is initially filled with steam more than 90 %. After the external cooling start, the steam contents decrease due to condensation and become almost zero no later than 6000 s. The decrease rate becomes smaller with time corresponding to the pressure history shown in Figure 6. The pressure approaches final asymptotic state of 100 kPa which is air partial pressure initially stuffed.

Erosion of helium rich layer by impinging air jet (AR-AJ and SE-AJ series)

Noncondensable gases of air and helium are used as stratified layer material. A helium rich layer is formed in air environment at the upper part of test vessel through helium injection line connected to vessel top. An air jet is injected about 2 m ( / 12.5) below the stratified layer interface through 159.2 mm inside diameter nozzle along the test section centerline. Prior to the erosion test, the velocity distribution of air free-jet was measured by using the present PIV system. The horizontal profiles with different injection velocity (u0) were extracted from the time-averaged PIV images as shown in

Figure 7 Vertical distribution of steam fraction

for CC-PL-04

Figure 8 Horizontal velocity profile of vertical free jet

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Figure 8. These profiles are obtained at 2.0 m downstream from the nozzle exit. In general, the velocity distribution of fully-developed turbulent free jet was given by

exp

where umax is the peak velocity and x, y are axial and radial direction of the center of round jet [8]. The constant value of c ranged from 85 to 94 depending on literature. The close agreement between the data and theory suggests the confidence of current injection nozzle design and PIV measurement accuracy. We can see slight deviations from the above equation. That may be caused by jet disturbance because jet hits thin internal structures to support thermocouples and capillaries.

The optical setup of PIV is shown in Figure 9. Helium-rich layer was initially formed at upper part of vessel and the second windows from top were used for PIV camera and LLS. The camera setup including lens choice and focus adjustment was performed to obtain wide field-of-view (FOV) than 1m width. The initial density of stratified layer and the vertical jet velocity were selected considering densimetric Froude number [9] is nearly equal to 1.0. During the experiment, the pressure was kept constant at atmospheric pressure by venting from the vessel bottom. A pair of images straddling a frame for PIV was recorded with an acquisition rate of 2-3 Hz in the vicinity of the jet stagnation point at during the transient.

The QMS with gas sampling was also used to measure the erosion progression. Figure 10 presents a time history of helium

Figure 9 Optical setup for PIV

Figure 10 Helium concentration evolution of SE-AJ-03

(a) time=3110s after jet injection start

(b) time=7190s after jet injection start Figure 11 Averaged velocity field (left) and root mean

square (right) by PIV measurement (SE-AJ-03)

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concentration vertical distribution along vessel center and near wall. It can be seen in this figure that the initial concentration of helium in stratified layer is about 46 % and the initial gradient zone height is comparatively thick about 1.5 to 2 m. The density gradient of interface becomes steeper than that of initial shape during first 1 hour due to the erosion by impinging jet. After that, the interface moves upward with keeping its profile. The erosion speed is a linear characteristic beyond this time that is approximately 250 mm/h. There is no distinct difference of profile between vessel center and periphery, but the helium fraction near the wall is slightly lager at the lower end of distribution below 8000 mm. This suggests that the eroded helium at the jet impinging region is delivered from center to the periphery and it turns into downward flow along the wall. The interaction of jet and interface was clearly observed from PIV analysis as shown in Figure 11. The color images present the averaged velocity field (left-hand-side) and its root mean square (right-hand-side) for 3110 s and 7190 s after the jet injection start. The FOVs are the same for both cases, but the scale of color bars is changed for clear visualization. The vector diagram is superimposed on a snapshot of original image for PIV. The oil mist of Di-Ethyl-Hexyl-Sebacat (DEHS) used for visualization appears in the image as a continuous region of white mist. The layer erosion process by impinging jet is characterized by upward flow at center, jet stagnation at interface, and bounded downward flow around jet as observed in the similar experiments previously conducted [10]. The propagation of internal waves at the density interface can be observed from an instantaneous vector field although it is not shown here.

CONCLUSION The large-scale containment experimental facility CIGMA

was constructed at JAEA to investigate thermal hydraulics in the containment during severe accident. CIGMA is characterized by the capability of conducting high temperature and high pressure experiments with CFD grade instrumentation with high spatial resolution. The first series of characterization experiments were systematically conducted to investigate the facility characteristics and instrumentation performance. On the whole, the performance of the CIGMA facility was found to be as specified in design. After resolving some minor problems identified in the experiments, the next phase of the experiments will be conducted for the ROSA-SA program that focuses on thermal-hydraulics relevant to the over-temperature damage of the containment, hydrogen risks and the FP transport during severe accidents.

NOMENCLATURE CIGMA: Containment InteGral Measurement Apparatus PIV: Particle Image Velocimetry LLS: Laser Light Sheet FOV: Field-Of View

QMS: Quadrupole Mass Spectrometry

ACKNOWLEDGMENTS The construction of CIGMA and the experiment in this

work were conducted under the auspices of the Nuclear Regulation Authority, Japan. The authors are also grateful to all staff members involved in the facility design and the performing the current experiments.

REFERENCES [1] Yonomoto, T., Sibamoto, Y., Takeda, T., Sato, A., Ishigaki,

M., Abe, S., Okagaki, Y., Sun, H., Tochio, D.: Thermal hydraulic safety research at JAEA after the Fukushima Dai-Ichi nuclear power station accident, Proc. of NURETH16-13838, 5341-5352, 2015.

[2] Paladino, D. and Dreier, J., PANDA: A Multipurpose Integral Test Facility for LWR Safety Investigations, Science and Technology of Nuclear Installations, ID:239319, 2012.

[3] Caron-Charles, M., Quillico, J.J.: Steam Condensation experiments by the MISTRA Facility for field containment code validation, ICONE10-22661, 2002.

[4] OECD/NEA THAI Project Final Report; Hydrogen and Fission Product Issues relevant for Containment Safety Assessment under Sever Accident Conditions, NEA/CSNI/R(2010)3, 2010.

[5] OECD/SETH-2 Project PANDA and MISTRA Experiments Final Summary Report; Investigation of key issues for the simulation of thermal-hydraulic conditions in water reactor containment, NEA/CSNI/R(2012)5, 2012.

[6] Auban, O., Malet, J., Brun, P., Brinster, J., Quillico, J.J., Studer, E.: Implementation of gas concentration measurement systems using mass spectrometry in containment thermal-hydraulics test facilities: different approaches for calibration and measurement with steam/air/helium mixture, Proc. of NURETH10, 2003.

[7] Sibamoto, Y., Morimaya, K., Maruyama, Y., and Yonomoto, T.: A simple mass and heat balance model for estimating plant conditions during the Fukushima Dai-ichi NPP accident, J. of Nucl. Sci. Technol., 49, 768-781, 2012.

[8] Shakouchi, T.: Jet Flow Engineering –Fundamentals and Application -, Morikita Shuppan, 34, 2004 (in Japanese).

[9] Studera,E, Brinsterb, J., Tkatschenkob, I., Mignotc, G., Paladinoc, D., Andreanic, M.:, Interaction of a light gas stratified layer with an air jet coming from below: Large scale experiments and scaling issues, Nucl. Eng. Des., 253, 406-412, 2012.

[10] Kelm, S., Kapulla, R., Allelein, H.J.: Erosion of a confined stratified layer by a vertical jet – detailed assessment of a CFD approach against the OECD/NEA PSI benchmark, Proc. of NURETH16-13079, 4462-4475, 2015.


Documents

First Experiments at the CIGMA Facility for Investigations