Projects / Programmes
Analysis of material damage and activation in large scale fusion reactors - application to the reactor JET
| Code |
Science |
Field |
Subfield |
| 2.04.00 |
Engineering sciences and technologies |
Materials science and technology |
|
| Code |
Science |
Field |
| T150 |
Technological sciences |
Material technology |
| Code |
Science |
Field |
| 2.05 |
Engineering and Technology |
Materials engineering |
Fusion, material damage, JET, the Joint European Torus, activation of materials, fusion reactor, low-carbon energy sources, sustainable energy sources, Monte Carlo neutron transport, Monte Carlo variance reduction
Researchers (15)
Organisations (2)
Abstract
The Joint European Torus - JET is currently the largest and most powerful magnetic containment fusion device to study nuclear fusion. JET can be operated with deuterium (DD) plasma or a plasma from a mixture of deuterium-tritium (DT). So far it has used DT plasma only during one experimental campaign, in 1998. A second DT campaign on JET is planned and the 14 MeV proposed neutron budget during the campaign will be nearly an order of magnitude higher than any previous DT campaign and much higher than practically achievable at existing 14 MeV irradiation facilities. This level of neutron flux/fluence will offer a unique opportunity to irradiate samples of functional materials used in ITER diagnostics, and of materials used in the manufacturing of the main in-vessel ITER components, to assess the degradation of the physical properties and the neutron induced activities, respectively. Additionally the activation of the components on the first wall and deeper in the torus material, the nuclear heating and radiation damage, will be studied.
The validation of neutronics codes will also be possible by experiments, which can be carried out with the fusion relevant conditions in JET. Especially important will be the comparison of the theoretical calculations of the above quantities with measurement results. The verification of these calculations will also pave the way for future safe operation of JET and consequently for that of ITER and DEMO.
The project is aimed at a comprehensive analysis of neutron material activation and radiation damage including nuclear heating in the case of the JET fusion reactor. During the future DT campaign insertion of samples into the torus for irradiation is planned, which will be backed up by calculations, pre and post irradiation.
The proposed project will focus on theoretical calculations of the activation of JET materials, neutron irradiation damage and nuclear heating. The main method of choice for both calculations will be the Monte Carlo transport, coupled with activation calculations. The necessary calculational tools will be studied and evaluated beforehand. The activation of specific components will be addressed and a general picture of the activation of the whole torus will be produced. Transport and activation codes will be coupled for this purpose. By a similar procedure, additionally, post-irradiation gamma doses will be calculated.
The ability to compare calculations with experimental results and the cooperation with experimenters in such a complex device, as the JET tokamak, is invaluable to acquire new skills which can not be obtained with theoretical work at the home institution. All results obtained on JET have an important role in the design of ITER since the same materials will mainly be used there. Improved calculations will lead also to a more precise knowledge on the activation of the reactor, which is important for the safe operation of JET, but it is also essential for the development of fusion, which may represent a major sustainable energy source in the future.
The applicant for the project leader have been for many years working with the group for neutron diagnostics at JET, and I have lead, or am leading, projects for Monte Carlo transport calculations for JET. The proposed project team has access to all relevant information at JET. The proposed project also includes all necessary topics for a comprehensive understanding of the neutron transport, activation and radiation damage of large tokamaks (like JET) for which all our experience, gained so far, will be used. We will choose and use appropriate methods for variance reduction, which will be verified through comparison with measurements. The results will be useful also for other tokamaks and similar devices. The knowledge and experience gained during this project will also be used to calculate neutron transport in fission reactors.
Significance for science
Knowledge of the activation and radiation damage is essential for a successful operation of the JET tokamak since its lifetime dependents on it, as well as the conditions of plasma operation. Successful data evaluation and calculations were, therefore, important both from a scientific as well as practical point of view. We confirmed the assumption that the damage rate of functional materials is about the same as expected in the planned ITER reactor at the location of the external vacuum port, where several diagnostic systems will be located. Materials, irradiated during the DT campaign at JET, will thus have a direct influence on the selection of materials for components to be used at ITER. We have developed a methodology for calculating the radiation damage in neutron and gamma fields of the JET reactor and evaluated various possible ways for these calculations. Determination of the activation of the JET torus after the DT campaign has practical and scientific value. We made a comparison between the different methods for calculating the activation. The findings will contribute to the planning of future work on JET and ITER. We have participated in various activities in connection with preparations for the DT campaign at JET; we actively participated in the calibration of neutron detectors with a DT neutron source. It was found that such calibration can be performed with a measurement error of less than 10%. These data will be particularly important in a similar calibration planned in ITER, which will be, due to the much higher fusion power, licensed under a more stringent regulations. The uncertainty of calibration, and with this the absolute fusion power, cannot exceed 10%. Different techniques for variance reduction were tested and we concluded that the use of energy-dependent weight windows is most suitable for such complex systems, as the JET torus. The most suitable is the FENDL 3.0 library. Comparisons of experimental and calculated values will serve as benchmark experiments in the areas of shielding and fusion neutronics.
Significance for the country
The offer to participate in such an important project is a recognition for Slovenian scientists and the successful completion did pave us the way to future projects and expansion of our work in the wider field of fusion. JET torus is currently the largest operational fusion experiment and during the work we constantly faced and cooperated with the most renowned experts in the field of neutronics for fusion reactors. The experience gained will be passed to the following generations of Slovenian researchers through lectures and mentoring. Through the successful cooperation we have paved the way for the acquisition of additional projects in the field of transport calculations for fusion reactors, primarily in the continuation of existing work on the largest project for JET so far, which was launched by the new organization EuroFusion, namely "Activities for the DT calibration for JET" for the years 2014-2018. Within the framework of the project we cover the same responsibilities, as we have so far, in addition our work has expanded. In this way, the presence of Slovenian researchers at JET continued and expanded. In 2014 two young researchers, whose mentors participated in the current project, visited jet and successfully joined the work. The project leader has, also on the basis of successful work for JET, in 2015 obtained the opportunity for work on the Radial Neutron Camera project for the future fusion reactor ITER; the scope of work is similar then for JET. International connections on such a level have a significant impact on the Slovenian scientist’s access to knowledge in the field of fusion reactor neutronics at the highest level. The focus of the current project were transport calculations for the purposes activation and neutron damage. A very similar problem is encountered also in the work for the fission reactor in the Krško Nuclear Power Plant. The possibilities for the implementation of experiments at NEK are very limited or non-existent, as it is a fully commercial type of reactor, unlike JET. Each experience acquired elsewhere is therefore welcome. The accomplished knowledge in the field of neutron diagnostics can be used in current and future projects for the Krško NPP, with which nuclear safety will increase. The choice of nuclear data libraries significantly contributes to the quality of each transport calculation. A collaborator on the project, Andrej Trkov is, also due to his successful cooperation at JET, holding a high position at the IAEA - Nuclear Data Section, as a trustee for some of the most important data libraries. Through this link, Slovenian researchers have a direct access to the latest libraries and high-quality advice on their use.
Most important scientific results
Annual report
2014,
2015,
final report
Most important socioeconomically and culturally relevant results
Annual report
2014,
2015,
final report
