F4E’s safety assessment of the Test Blanket Systems delivered to ITER IO
Joelle Vallory together with the rest of the F4E TBM Project Team preparing F4E's contribution to the Task Force on the TBM Programme Safety Demonstration.
Safety is an integral aspect of ITER and a top priority for ITER Organization, F4E and all the ITER Domestic Agencies. Because ITER is located in France, it must follow French safety rules and the French Safety Authority (ASN) has required ITER Organization to integrate the Test Blanket Systems (TBSs) into the safety demonstration (a compilation of documentation and analysis which demonstrates the safety of ITER). An international Task Force, encompassing ITER IO and the ITER Parties developing TBSs (F4E is developing two TBSs and the ITER Domestic Agencies of China, India, Japan and Korea are each developing one TBS), was established at the beginning of 2016 in order to deliver the technical documentation needed to integrate the TBSs into the larger ITER safety demonstration. After one year of intensive work this technical documentation which will be used by ITER IO to answer to the ASN request has now been delivered.
The TBSs consist of in-vessel and outer-vessel components or systems. The in-vessel components are the TBMs (Test Blanket Modules) which are test versions of the Breeding Blankets modules and will be tested in ITER in order to assess their technical potential. The Breeding Blanket modules, an integral part of the future DEMO machine, will produce tritium in-situ, the fuel needed for the fusion process to occur. It will also transform the energy of the neutrons produced in the plasma into heat with the objective of ensuring that this heat can be recovered and transformed into electricity. The outer-vessel systems connected to the TBMs ensure key functions for the TBMs to operate: cooling, coolant purification and tritium extraction.
Joelle Vallory, the nominated member representing F4E in the Task Force, worked together with each involved ITER Party representative, experts and safety officers in numerous workshops in order to ensure consistency in the methodology adopted by all involved ITER Parties and allow for each involved Domestic Agency to deliver technical data to be used for ITER IO to answer ASN. Together in the Task Force, they evaluated key data such as tritium production, tritium modelling (the way tritium will is transported within the TBSs), neutronics (analysing the effects of neutrons on the TBMs and on other ITER components), and accident analysis (describing possible accident scenarios, their consequence and analysis on how to prevent or mitigate them) in order to present one solution to ITER IO.
"The ITER IO Central Team dedicated to safety matters created a series of templates of exhaustive checklists that we used as a basis for our work when producing the necessary technical documentation", explains Joelle Vallory. "We went through every issue in a methodical and thorough manner in order to reach an acceptable consensus and all participants clearly showed their will to progress in this very demanding task."
In total, the technical documentation provided by F4E consisted in 13 checklists for the two TBSs that Europe is responsible for. "As safety is a top priority for F4E, we have put a lot of effort in being proactive in this Task Force. In total, we have dedicated 1.6 man years. The documentation that we delivered to ITER IO corresponds to the weight of a newborn baby", says Joelle Vallory. The TBS technical documentation from all involved Domestic Agencies is currently being reviewed by ITER IO with the objective of harmonising its content with the overall safety demonstration file which will be submitted to the French Safety Authority during the first half of 2018.