INNOvative tools FOR dismantling of GRAPHite moderated nuclear reactors

Project Information

INNO4GRAPH

Grant agreement ID: 945273

DOI

10.3030/945273

Project closed

EC signature date 22 May 2020

Start date 1 September 2020

End date 31 October 2023

Funded under

• Euratom

Total cost

€ 3 848 553,01

EU contribution

€ 3 011 061,38

Coordinated by

ELECTRICITE DE FRANCE
France

Periodic Reporting for period 2 - INNO4GRAPH (INNOvative tools FOR dismantling of GRAPHite moderated nuclear reactors)

Reporting period: 2022-03-01 to 2023-10-31

Summary of the context and overall objectives of the project

Decommissioning is a normal stage in the life of a graphite-moderated nuclear power plant (NPP). However, considerable industrial and technical challenges related to the dimension and complexity of the structure as well as costs for decommissioning require novel, more performant, safer and cost-efficient solutions for dismantling operations.
The three-year EU-funded project INNO4GRAPH was a first step to address the huge challenge of dismantling these graphite-moderated nuclear reactors with such imposing dimensions. Decommissioning these reactors is essential to leave a cleaner and safer world for the next generations. To face the challenge, INNO4GRAPH managed to achieve its research objectives built around 5 main topics:
- Putting together a database of existing physical properties and radiological inventory on graphite, development of technology or methodology to improve knowledge of the graphite core state in terms on cracks and corrosion.
- Sharing the existing dismantling scenarios of NPP operators of the consortium. Building of and sharing a multicriteria analysis grid for NPP operator scenarios including regulatory requirements.
- Performing 3D simulations of dismantling scenarios.
- Formulation of innovative tools for dismantling of these reactors and design of a representative mock-up of graphite stack of Chinon A2 NPP.
- Defining a training programme in areas of interest for graphite reactor decommissioning.

Work performed from the beginning of the project to the end of the period covered by the report and main results achieved so far

During the first part of the project, technical and environmental dismantling requirements of the European operators were shared. This provided a good overview of the graphite reactor decommissioning situation as well as an understanding of similarities and differences. It also allowed to identify discrepancies to be considered in R&I during and after the INNO4GRAPH lifetime and to build a common development roadmap for future developments.
Besides, developments, evaluation of tools and methodologies in laboratory or representative environments were carried out during the second part of the project: 3D modelling and physical demonstrations using the graphite mock up designed and built during the first part of the project. Knowledge of graphite properties were further improved by novel techniques of graphite properties prediction.
From the technical specifications defined on in-situ crack detections, a prototype was set up and tested. From the established state of the art and with data collected from NPP operators, several Non-Destructive Tools to measure corrosion were identified on reactor cases.
The representative mock-up of the graphite stack was designed, manufactured and installed at the EDF Industrial Demonstrator. It was used to perform tests on the operational graphite retrieval tools and the way to remotely operate them.
From the test methodology defined to assess the risk of bulk-oxidation of the graphite during cutting operations, data about the oxidation behaviour of different graphite samples was collected.
Innovative tools were developed with the aim to make them available during the dismantling operations.
In particular, a proper coating painting was investigated in order to reduce the contamination risk during graphite extraction and handling and coated samples tested in order to assess structural, thermal and mechanical properties.
Laser cutting tests were carried out on graphite samples to study the applicability and assess the technical feasibility of laser cutting technology on graphite blocks.
Studies regarding the specific needs for the multi-joint manipulator in graphite reactors were performed to select, model in a virtual environment and test characteristics for a future development.
A deployment system was designed during the project for graphite retrieval tools. Its aim is to deploy and operate the different tools necessary to dismantle the graphite stack from a mobile dismantling platform set up above the reactor. The system designed will then be manufactured and later tested in the Industrial Demonstrator beyond the Project.
Using DEMplus® software, 3D simulations were used during the tool developments to better understand the physical environment and constraints. 3D simulations of graphite bricks retrieval were also performed allowing to evaluate feasibility of operations, in terms of accessibility, cost, duration, collective dose and wastes generated.
By developing tools that provide more in-depth information about the graphite mechanical properties and tools that decrease the risk of handling radioactive material, the safety and cost-efficiency of the dismantling operations can be increased.
Moreover, the development of new techniques and the expertise gained within the project has already generated knowledge. A training programme was defined based on areas of learning and lessons learned for graphite reactor decommissioning. An innovative module using interactive viewer was developed as an example of training module.
All along the project, the consortium has been active in conferences, disseminating the project results to the stakeholders of the graphite decommissioning field. 4 publications were published: https://shorturl.at/kmBS6. Synergies could also be initiated thanks to the EU support and its EURATOM Programme with projects such as LD safe (https://ldsafe.eu/) or CLEANDEM (https://shorturl.at/mrwAQ).
On Oct. 2023, the project ended with an international event (https://shorturl.at/ILPZ2) showcasing the following outcomes:
- The graphite reactor data gathering and comparison
- The design of tools and deployment systems for investigations and dismantling
- The testing of innovative solutions, such as laser cutting
- The 3D simulations of scenarios of thousands of graphite brick removal.

Progress beyond the state of the art and expected potential impact (including the socio-economic impact and the wider societal implications of the project so far)

INNO4GRAPH is a first step towards mutualisation of methodologies, tools and cost-effective decision in terms of strategy. It has an economic impact both through the development of common tools that can be used more than once and by more than one operator and by allowing new tools and methods that will be more effective, in line with operators’ needs.
As foreseen, the project has so far allowed the graphite reactor dismantling to benefit of various innovations that will increase safety/security and will optimise waste management and cost mastering, e.g.
- The potential for adoption by the operators of the graphite retrieval tools developed into their dismantling projects is strong.
- The sharing of common methodologies and dismantling tools has progressed: The graphite mock up installed in the EDF Industrial Demonstrator can be adapted to different projects and the need to use robotic tools is now commonly adopted.
- The physical and digital risk mitigation strategy using the graphite mock up carried out in the EDF full scale demonstrator is on the way.
- The international sharing of feedback and knowledge (e.g. regulatory constraints, etc.) has led to a common understanding of the technical challenges.
- The laser cutting tests of the graphite demonstrate the absence of inflammatory or explosion risks.
- The provided graphite mechanical properties give information for the design of adequate scenarios and tooling.
- The digital tools used allowed to lead a cost-benefice analysis.
A roadmap was also delivered during the last part of the project to include tools and methodologies available to define new or alternative dismantling scenarios, but also further possible developments beyond the project.

Graphite core reactor DEMplus® 3D models (a)Ignalina,(b)Vandellos I,(c)Latina,(d)Chinon A2 and G1

EDF Industrial Demonstrator

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