Concept & Approach
To start with, graphite NPP operators in the consortium will share data to establish a common knowledge base which will allow the partners to take into account the differences in terms of local context between each project (e.g. regulatory requirements). Operators will also share their scenarios to be able to compare and challenge them. All these conditions are necessary in order to be able to build common decision-making tools and also a common development roadmap for future developments. During this phase, the radiological and physical inventory available for all reactors will be collected.
This work will be useful since numerous tools developed in the project aim to help operators to better characterize any facility before the actual dismantling operations. It will help in identifying the gaps and fitting the developments to manage them. These data are also necessary to ensure that the evaluation tools match the needs and specificities of all partners. For example, it will guarantee that mock-ups built during the project are representative of all the reactors for which tests and evaluations have to be performed thanks to these mock-ups. They will also be used to feed both numerical modelling and cost estimation tools based on dismantling scenarios. A significant effort will be made, not only on operational tools development but also on digital tools, dedicated to the evaluation of feasibility, risk assessment, cost evaluation of the operations. The added value of these tools will be evaluated at least on one reactor depending on the tool considered (digital twins will be developed for all reactors, allowing to test the new tools concept on all of them).
Operational dismantling tools will be validated at partners’ facilities and by comparison with data coming from the reactors that are available. If necessary, the industrial demonstrator will be used after the project, in addition with the implementation of the development road map, to fine-tune the tools and make them more robust. All along the project, the focus will be on the feasibility and the added value evaluation (cost, risk and schedule) of each developed technique. Indeed, the main aim of all these developments is to inform and optimise the global dismantling scenario.
Examples of tools to be developed in the project to be used before the actual dismantling operations
Inspection tool for in situ crack detection
INNO4GRAPH will develop a specific inspection tool for in-situ crack detection, taking into account the reactor core constraints and the technology performance evaluations. The tool will be tested and validated on a real reactor case (Latina NPP).
Representative mock-up of a part of the graphite stack (full scale)
INNO4GRAPH will develop a full scale mock-up of a part of the graphite stack. This mock-up will be dedicated to performing tests on the operational graphite retrieval tools and the way to remotely operate them.
Graphite brick retrieval simulation
Today, no 3D digital tool allowing the specific study of bricks retrieval, considering the friction (during retrieval), is available on the market. To fill this gap, a new module using a simplified model will be added to the current collision module of DEMplus®. This module will be used as input to the information generated by the code_Aster, such as the contact pressure between bricks, etc.
Examples of tools to be developed in the project to be used during dismantling
Deployment system for graphite retrieval tools
The aim of this system is to deploy and operate the different tools necessary to dismantle the graphite stack from the mobile dismantling platform (in green in figure above).
Typical dismantling laser cutting technology
A typical dismantling laser cutting technology is composed of a commercially available laser source with its cooling system, installed in a shelter located in a non-nuclear area, two optical cable fibres to transport the laser beam, a fibre-fibre coupler to separate the operational nuclear area and the non-nuclear one, a specific laser cutting tool design for nuclear dismantling operations, a control system, located in the operators control room and a remotely controlled robotic arm. INNO4GRAPH will confirm that laser cutting technology can be used for graphite retrieval.