Two meetings were organized in the WP7 “Containment” in the past six months. One took place in Aachen (Germany), on February 8-9, 2011, and was hosted by Forschungszentrum Jülich. The following tasks were discussed: modelling of containment sprays, modelling of hydrogen combustion, modelling of steam condensation, hydrogen combustion during Direct Containment Heating, and development of a generic containment model. The other meeting, on the topic of ex-vessel fuel-coolant interaction, took place at Fontenay-aux-Roses (France) on February 11, 2011, within the OECD SERENA2 meeting, and was hosted by IRSN.

Ex-vessel fuel-coolant interaction
At the latest meeting, the status of current actions was discussed. Conclusions were drawn regarding the exercise of comparison of MC3D and IDEMO codes regarding steam explosion strength in 1D situation (analytical exercise). On the overall, the strengths are not so different but both codes show some trends which needs clarification. A report is to be issued soon. The exercise is to be continued to 2D/3D situations. Regarding reactor applications, an exercise of pre- and post calculations of the future LACOMECO DISCO-FCI test has been launched. The test is scheduled for the 3rd quarter of 2011. Finally, it can be noted that, in the frame of WP 5-3 (ex-vessel coolability), an exercise of calculation of some DEFOR experiments (KTH) was launched. The results are of interest to WP7-1 (a strong link exists between the two work-packages).

Modelling of containment sprays
After the successful completion of the first phase of the spray benchmark, the open question is now how to proceed for the second phase. Jeanne Malet (IRSN), who leads the task, presented experiments on containment sprays, performed in the CALIST facility at IRSN, which will be used. As many participants of the first phase expressed a strong interest, this exercise will probably also be successful.

Modelling of hydrogen combustion
In this task, the open question is also how to continue the hydrogen combustion benchmark after the successful completion of the first phase. Ahmed Bentaib (IRSN), who leads the task, presented the two possible options: 

• Further simulation of experiments, performed in the ENACCEF facility in CNRS/Orléans (France);
• Simulation of AECL-EACL (Canada) experiments, performed in the Large Scale Vented Combustion Test Facility (LSVCTF).

Modelling of steam condensation
After the first phase of the steam condensation benchmark was successfully completed, the second phase will consider experiments with lower flow velocities. Walter Ambrosini (UNIPI), who leads the task, presented the modifications of the CONAN experimental facility (UNIPI) that are being carried out with this purpose. The second phase of the benchmark will start as soon as the facility is ready and the necessary experiments are performed.

Hydrogen combustion during Direct Containment Heating
Results of the first experiments on hydrogen combustion at DCH conditions, which were performed in the HYKA A2 experimental facility (KIT), were presented by Giancarlo Albrecht (KIT). The main conclusions of the 9 performed experiments so far are:

• No scaling effect was found in the simple geometry;
• Replacement of nitrogen by steam does not reveal any noticeable differences;
• Only a fraction of available pre-existing hydrogen burned.

Also, Thomas Jordan (KIT) will lead this task from now on, as Leonhard Meyer (KIT) has moved to the International Atomic Energy Agency in Vienna (Austria).

Development of a generic containment model
The first phase of the benchmark on generic containment was successfully completed. The model of the generic containment is based on German 4-loop PWR (see figure below).

Model of generic containment

Stephan Kelm (FZJ), who organised the benchmark, summarized the results. The benchmark has clearly shown the usefulness of such an exercise, as it allows the comparison of lumped-parameter codes without the influence of different simplifications of the same actual containment due to different code users. The benchmark will continue with the second phase, whose specification was also presented at the meeting. The simulated transient will include injections of H₂, CO and CO₂, as well as energy sources which represent fission products decay release and other heat sources. However, hydrogen combustion will not be simulated. Simulations will still be performed using lumped-parameter codes. The possible modelling of non-homogeneous atmosphere using these codes may also be performed as an additional option.

Contact: Ivo Kljenak
ivo.kljenak@ijs.si