Pierre Cortes

Lessons learnt from ITER safety & licensing for DEMO and future nuclear fusion facilities

Abstract One of the strong motivations for pursuing the development of fusion energy is its potentially low environmental impact and very good safety performance. But this safety and environmental potential can only be fully realized by careful design choices. For DEMO and other fusion facilities that will require nuclear licensing, S&E objectives and criteria should be set at an early stage and taken into account when choosing basic design options and throughout the design process. Studies in recent decades of the safety of fusion power plant concepts give a useful basis on which to build the S&E approach and to assess the impact of design choices. The experience of licensing ITER is of particular value, even though there are some important differences between ITER and DEMO. The ITER project has developed a safety case, produced a preliminary safety report and had it examined by the French nuclear safety authorities, leading to the licence to construct the facility. The key technical issues that arose during this process are recalled, particularly those that may also have an impact on DEMO safety. These include issues related to postulated accident scenarios, environmental releases during operation, occupational radiation exposure, and radioactive waste.

Progress in the Safety and Licensing of ITER

Abstract The safety documentation for ITER, including the Preliminary Safety Report, was submitted to the French nuclear safety authorities in March 2010 as part of the procedure for licensing the facility as a basic nuclear installation in France. The documents were then examined by the authorities and their technical advisors, with substantial interaction between specialists from the ITER Organization and the nuclear regulator. Finally the examination has concluded with a positive advice to grant the decree to permit the creation of ITER, and to proceed to the next stage of licensing, during which a number of ongoing commitments will have to be fulfilled. In the course of the examination of the ITER safety files, a number of technical issues were visited. These concerned the provisions in the design to mitigate potential hazards by the implementation of two safety functions: confinement of radioactive material and limitation of exposure to ionizing radiation. The robustness of the confinement systems that protect radioactive inventories had to be justified and their adequacy in all situations had to be demonstrated. Potential challenges to the confinement, even in events regarded as extremely unlikely, had to be fully analyzed. It also had to be shown that radioactive waste generated by the operation of ITER has a viable path for its safe storage and ultimate disposal. In this paper some of the key technical issues that form part of the ITER safety case are outlined, in the light of the discussions held during the regulatory examination of the files. Some of the issues outlined are the subject of ongoing actions to reach a final conclusion.

Sensitivity Studies on the Accidental Impact of 1 G of Tritium for ITER Site Specific Characteristics

Abstract One of the safety issues related to ITER concerns the potential impact of Tritium that could be released to the environment in a postulated accident. As the final site located at the vicinity of Cadarache nuclear facilities in France is known, some calculations have been made to assess the effect of the nominal release of 1 g of tritium for ITER site specific characteristics. Sensitivity studies have been performed according to these characteristics, but also to assumptions related on the way the tritium could be accidentally released (chemical form, height of the releases...). The results being used for demonstrating the low impact of tritium accident releases, care has been considered on the selection of the most penalizing assumptions in terms of results. The results have shown that, whatever are the assumptions, the consequences of 1 g of tritium that could be accidentally released into the environment is extremely low, in the domain of low doses. In spite of this very low impact, many safety provisions are undertaken with regards to defence in depth principles in order to further reduce both the likelihood of an accident involving tritium and its consequences.

Creation of ISO Standards Related to the Confinement Systems in Tritium Facilities

Abstract This paper gives the rationale for creating through International Standard Organization a standard for confinement systems in Tritium facilities under the frame of the working group dealing with confinement, ventilation and shielding issues in the radiation protection subcommittee of the nuclear energy technical committee (ISO TC85/SC2/WG23).

Progress of ISO Standards on the Confinement Systems in Fusion Facilities Using Tritium

Abstract This technical note presents progress of a standard developed under the frame of the working group dealing with confinement, ventilation and shielding issues. The current standard ISO 17873 was created for nuclear facility application for which tritium does not represent the main source term. In order to guide guidance to the designers, two criteria based on contamination source term are proposed to classify systems dealing with aerosols or gaseous issues, and technologies in this field are outlined.

The Role of Operational Feedback and R&D in ITER Safety

This paper presents an overview of the safety-related operating feedback taken into account in the ITER baseline design and of the previously completed and ongoing research and development (R&D) activities in support of ITER safety analyses. Operating feedback relevant to ITER mostly comes from previous and currently existing fusion devices and from the operation of tritium laboratories. Regarding the safety-related R&D, since the early times of the ITER project, an extensive program has been devoted to understanding the issues, gathering data on source terms, modeling underlying phenomena, and developing analytical tools for safety analysis.

Safety related R&D for the ITER baseline design

This paper presents an overview of the safety related operating feedback taken into account in the ITER baseline design, and of the previously completed and ongoing Research and Development (R&D) activities in support of ITER safety analyses. Operating feedback relevant to ITER mostly comes from previous and currently existing fusion devices, and from the operation of tritium laboratories. Regarding the safety related R&D, since the early times of the ITER project, an extensive program has been devoted to understanding the issues, gathering data on source terms, modeling underlying phenomena, and developing analytical tools for safety analysis.