3.1 OECD/GAMA (Funding: VYR, VTT)
VTT’s participation in the OECD/NEA/CSNI Working Group on the Analysis and Management of Accidents (GAMA) is done within the project. The annual volume of work covers participation in 1-2 working group meetings and informing of them within Finland as travel reports.
3.2 OECD/PSB-VVER (Funding: VYR, VTT)
PSB_VVER is a four-year project launched in 2003. Within the project, five experiments will be carried out with PSB-VVER facility. The project supports validation of t/h codes and safety assessment of VVER-1000 reactors. Follow-up of the project covers participation in the meetings.
3.3 USNRC/CAMP (Funding: VYR, VTT)
The task covers VTT's participation in the USNRC's Thermal-Hydraulic Code Applications and Maintenance Program (CAMP). Participants will receive the latest versions of NRC codes (RELAP5, TRACE, PARCS etc.), as well as assessment results and experience and information gained in CAMP. The annual volume of work covers participation in two meetings. The participation fee of CAMP is included in the project costs
3.4 OECD/ROSA (Funding: VYR, VTT)
The OECD ROSA Project is to resolve issues in thermal-hydraulics analyses relevant to LWR safety using the ROSA/LSTF facility of JAEA. In particular, it intends to focus on the validation of simulation models and methods for complex phenomena (thermal stratification during emergency core cooling injection; unstable phenomena such as water hammer; high power natural circulation; natural circulation with superheated steam; primary cooling through secondary depressurisation). Phenomena coupled with multi-dimensional mixing, stratification, parallel flows, oscillatory flows and non-condensable gas flows are to be investigated.
This subtask covers participation in project meetings and reporting of the project to Finnish organisations.
3.5 OECD/SETH2 (Funding: VYR, VTT)
OECD/SETH2 project will study steam/gas mixing and distribution with new well instrumented experiments in PANDA and MISTRA test facilities in 2007-2010. The subtask covers the annual fee of the OECD project and participation in project meetings.
3.6 Northnet (Funding: Fortum, VTT)
Northnet is a Nordic network for thermal-hydraulics and nuclear safety research. The idea of the network is to combine the resources of different research teams in order to carry out more ambitious and extensive research programs than would be possible for the individual teams. At the moment, most of the Finnish and Swedish organisations are involved in the activities of the network, either as research units or as end users of the results.
This subtask covers the coordination of the network in Finland and preparation of EU project proposal together with other Nordic partners.
4 Project coordination (Funding: VYR, VTT)
Project coordination is done within the task. The task also covers travelling expenses to scientific conferences etc., which can not directly be assigned to any other sub-project.
5 NURESIM (Funding: EU, VTT)
In 2007, VTT will continue work on condensation and simulate a chosen steam blow-down experiment performed in LUT. The simulations are made with the NEPTUNE code, and the purpose of the calculation is testing of the code.
NEPTUNE is the thermal hydraulics tool of NURESIM. NEPTUNE is designed to simulate two-phase flow in all of the situations encountered in nuclear reactor power plants. The code uses 0D and 1D models for the system scale simulations; 3D porous medium model for simulating large-scale 3D phenomena; CFD module for finer resolution, and finally direct numerical simulations for micro scale. For the system scale, NEPTUNE stems from the codes
previously developed by CEA and EDF (including CATHARE, FLICA, GENEPI, THYC, and ASTRID). Two-phase CFD module of NEPTUNE is developed by CEA and EDF under the co- sponsorship of Framatome-ANP and IRSN. The TRIO-U code for direct numerical simulation is developed by CEA.
The task is closely related to ECE and CONDEX projects, and will be performed in close co- operation with Lappeenranta University of Technology.
Deliverables
Task Deliverable
1. Report of APROS calculation of ROSA test 6.2.
Report of APROS calculation of the second ROSA test.
Report of LBLOCA calculation of PSB-VVER experiment with APROS.
Report of PWR-PACTEL calculation with APROS Report on APROS validation strategy
2. Report of Fluent simulation of SARNET PAR benchmark calculations.
Report of Fluent simulation of SARNET wall condensation benchmark.
3. Travel reports & other relevant information of the ongoing programmes 5. Report of NEPTUNE simulation of blow-down experiment
Applications
APROS capability to simulate various transients and tested models for vertical steam generator are needed in evaluation of the safety of OL3.
The validated Fluent models to describe wall and bulk condensation and PAR affects can be used to simulate situations, where steam condensation influences hydrogen distribution/mixing in containment.
Through participation in NURESIM, experience is gained in the thermal hydraulic simulation tool NEPTUNE. Having experience of the code helps to evaluate capabilities of the code, and to review results obtained with it. This is important if, as planned, the NEPTUNE code in future gains a status of widely used European code.
Education of experts
Young scientists and a trainee will elaborate their skills with APROS-software.
Liite 2a SAFIR2010 27.10.2006 RESEARCH PLAN for 2007/version 1
The integration of thermal-hydraulics (CFD) and structural analyses (FEA) computer codes in liquid and solid mechanics (MULTIPHYSICS)
Termohydrauliikka- ja rakenneanalyysikoodien linkittäminen neste-rakenne -systeemissä Duration 2007
Project manager Ville Lestinen
Volume and funding 2006 0.55 person-years 82 k€
Funding sources (k€) 2006 Tekes 41 k€, Fortum 41 k€
Objectives
The objective of the project is to improve the numerical modeling capabilities of physical systems including fluid-structure-interaction (FSI), which is a relevant phenomenon in many economically and technically important industrial applications. The practical objective of the project is to develop a useful method for coupling of the computational fluid dynamics (CFD) and the finite element stress and strain analysis (FEA) codes. The developed method is used for applications in which the pressure field is transferred from CFD to FEA code and the resulting structure deformations are returned from FEA to CFD. The codes used for development and simulations are for CFD calculations STAR-CD and FLUENT and for FEA ABAQUS.
Coupling can be made using some general codes, but the code vendors are also developing code specific solutions. In addition to CFD-FEA linking the possibilities to use 1-D system codes with CFD for boundary condition calculations in multiphase cases are studied. Finally calculations will be validated against experiments. The objective of the project for year 2007 is to validate the developed FSI-simulation method for LBLOCA analysis.
Background
FSI problems are very common in industry, which has created a need to develop simulation tools for these problems. One important application in nuclear reactor safety is the structural integrity of core internals in Design Basis Accident (DBA) situations like Large Break Loss of Coolant Accident (LBLOCA). To solve the problem in detail both the CFD and the FEA analyses are needed.
At the beginning of the MULTIPHYSICS project the aim was to study the possibility to develop a common numerical model for system geometry with suitable meshing for all physical analysis disciplines, including both CFD and FEA modeling. However, quite soon it was realised that this kind of common model would decrease the quality of both analyses. Therefore it is more reasonable to concentrate on finding out a method, which could link separate CFD and FEA calculations. This way both calculations can be made using an optimal mesh and maximum available accuracy can be reached in both calculations.
During the last few years also code developers in the areas of CFD and FEA have started to concentrate on the code coupling. Two CFD codes, STAR-CD and FLUENT have been used so far in this project. STAR-CD has its own ES-FSI model for coupling with FEA. ES-FSI uses FEA code as a "subprogram", which means that all calculations are made in STAR-CD. Another alternative is to use an external commercial interpolation code. In this project the MpCCI interpolation code is used to transfer data between CFD and FEA in case of both CFD codes (STAR-CD and FLUENT). This kind of coupling method means that both CFD and FEA code makes calculations autonomously. Another method, which has been used in the project is the coupled acoustic-structural method of ABAQUS. In this approach water is modeled as an acoustic
medium and the acoustic and structural domains are coupled. It is very useful to compare coupled calculations made with different ideologies.
The boundary condition for CFD calculations is the sudden pipe break. In this kind of case the phase change phenomena are important. Due to this 1-D system codes APROS and TMOC are used for boundary condition calculations.
The two-way couples calculations were started during the year 2005 and continued 2006. The chosen application, LBLOCA in the Pressure Water Reactor (PWR), was defined so that the cold leg pipe breaks near the pressure vessel, which is the worst case scenario for reactor internals. The CFD codes and the internal method of ABAQUS were used to calculate the propagation of the pressure wave into the reactor. All of the coupled calculation methods work also in practice.
However, MpCCI seems to be more flexible of the two CFD-FEA coupling methods and it will be used in the further calculations with both CFD codes. Calculations have been made also concerning the pressure drop in the pipe break, which is the relevant factor for defining the boundary conditions of the LBLOCA simulations. These calculations have been made using the system codes APROS and TMOC. The final step in the project is validation of the calculated results. Calculation method can't be used for practical calculations before the validation is performed. In the validation the calculations are compared with experimental results. Validation will be made during the year 2007.
Specific Goals in 2007
1 Validation of coupled CFD - FEA calculations
Work for coupling of CFD codes FLUENT and STAR-CD with FEA code ABAQUS started in 2005. In 2006 the method is further developed so that a tool for real analyses is achieved. In 2007 the coupled calculations will be validated. This work task will be divided in two subtasks:
1.1 Validation of STAR-CD - ABAQUS calculations (Funding: Tekes)
The CFD code STAR-CD has been linked to FEA code ABAQUS by using internal ES-FSI model and an external "agent" code MpCCI. Development of the coupled calculation tools were tested during the year 2005 and 2006. In 2007 coupled calculations will be validated against the experimental data.
VTT has a large amount of original data from HDR experiments carried out in Germany. These experiments are well suited for validation in this case since in the experiments LBLOCA was studied with a facility having realistic dimensions. The test material will be studied and some experiments will be chosen for validation. These experiments will be calculated using STAR-CD - ABAQUS coupling and the results will be compared with experimental results. To this subtask is included also the internal coupled acoustic-structural method of ABAQUS, which will be validated in parallel with the STAR-CD - ABAQUS calculation.
1.2 Validation of FLUENT - ABAQUS calculations (Funding: FNS)
The CFD code FLUENT is linked to FEA code ABAQUS using an external "agent" code MpCCI.
The coupled calculations were carried out during the year 2005 and 2006. In 2007 the coupled calculations will be validated against the experimental similarly with STAR-CD - ABAQUS calculations.
2 Validation of boudary condition calculations with 1-D system codes
Boundary condition calculations have been made by using 1-D system codes APROS and TMOC.
These codes are validated against the Marviken experiments. However, HDR experiments descibe the calculated case better and therefore also system code calculations will be further validated.
2.1 Estimation of the thermal-hydraulic phenomena in the pipe break point and inside the reactor after the LBLOCA (Funding: Tekes)
In this subtask APROS fluid models (Moody, basic model) will be tested and compared.
Submodels of the basic model are possibly modified. In addition alternative model of critical flow will be tested and possibly implemented in to the code. These models and previous calculations with APROS and TMOC codes will be validated against the HDR experiments.
Deliverables
Task Deliverable 1.1
1.2 2.1
Validation of coupled CFD - FEA calculations and system code boundary condition analyses.
Applications
The results of the MULTIPHYSICS project will benefit the whole nuclear industry in Finland.
However, due to the generality of the coupling method the results of the project will be applicable to many kind of industry. Technical problems, which could be analysed using CFD-FEA code coupling are very common in many kind of industrial applications. Practical examples are for example water hammer phenomenon in the pipe lines and vibration problems. Also boundary condition calculations in multi-phase flow situations using system codes will be more and more important in the future. This project generates methods to develop new tools to solve these problems and also helps to take benefit of new features of the commercial codes in this sector.
Another important point is the opportunity to sustain and develop knowledge in this area. The content of this research project have been planned in co-ordination with FNS and VTT.
Education of experts
The project employs PhD student (Antti Timperi from VTT) and several young research scientists, who are younger than the average of the industry.
Liite 2a SAFIR2010 24.01.2007 RESEARCH PLAN for 2007/version 2
Participation in Development of European Calculation Environment (ECE) Osallistuminen eurooppalaiseen laskentaympäristön kehitystyöhön
Duration 2005 – 2007
Project manager Heikki Purhonen, Lappeenranta University of Technology Volume and funding 2007 0.7 + 0.9 person years 24,209 k€ + 25 k€*
Funding sources (k€) 2007 VYR 24,209 k€, EU 25 k€*
* EU Funding for NURESIM EU Project Objectives
The goal of the ECE project is to take part in the development and validation process of the new Common European Standard Software Platform for the simulations of next-generation nuclear reactors. A key activity of the project is also to maintain good relations and increase contact intensity to the European nuclear research community. The participation ensures the access to use the new platform and new simulation tools. The project gives a possibility to increase educational competence and to acquire readiness to use new two-phase flow simulation tools.
Concrete objectives of ECE are as follows:
- To select, evaluate and convert suitable steam blowdown experiment data from the condensation pool test series carried out in SAFIR/POOLEX project.
- To use these selected experiment results for development and validation of new simulation tools.
The experiment results must be investigated thoroughly to ensure the suitability, quality and accuracy of the results for validation purposes. The new simulation tools will be installed and tested to the SALOME platform for the validation purposes of the CFD modeling. SALOME is an open source platform for numerical simulation integration and supported by Linux operating system.
Background
Lappeenranta University of Technology (LUT) as well as Technical Research Center of Finland (VTT) are participating in the Nuclear Reactor Simulations (NURESIM) Integrated Project (IP) in the Sixth Framework Programme (FP) of EU. The aim of the NURESIM project is to take the initial steps towards a common European standard software platform for modelling, recording, and recovering computer data for the next-generation nuclear reactors simulations. The specified participation of LUT and VTT focus on the thermal hydraulic part of the project, which is one of the six sub projects of NURESIM. The VTT part continues in the proposed SAFIR2010/THARE project. The funding share from EU is limited, but it is strategically important to stay involved in NURESIM. The national SAFIR2010 funding in the ECE project enhances possibilities of LUT to be involved both in the calculation work and in the preparation of the experimental data. The ECE project was started already in SAFIR programme simultaneously with the initiation of the NURESIM project and is planned to last as long as NURESIM, i.e. three years from 2005 to 2007.
Specific Goals in 2007