Onet Technologies also carried out two maintenance operations involving its divers on unit 4 at Cruas.

^1st operation: Removing a spacer from the Upper Internal Elements (EIS)

EDF has identified a damaged spacer (or staple) on a thermocouple pipe located on the periphery of the Plaque Supérieure des Tubes Guides (PSTG).

Onet Technologies, retained by EDF, successfully carried out this removal operation thanks to the underwater intervention of its divers. Onet Technologies provides this type of service on a recurring basis. The scenario, drawn up in advance, defines the route to be taken by the diver, and the technical resources required to extract the clip.

2nd operation: Underwater decontamination by diver of the BR side transfer compartment

The transfer tube is a channel used to transfer fuel assemblies from the BK pool to the BR pool and vice versa. EDF commissioned Onet Technologies to carry out this underwater decontamination. The decontamination is labile, with the aim of identifying and removing any hot spots that may be present.

Carried out over several dives, this service is performed in two main stages. Firstly, a high-pressure cleaning lance is used to loosen contamination. This is followed by sanitizing work using a suction hose connected to a pump. The contamination thus extracted is collected in a filter deposited in a concrete shell for disposal as waste, with decontamination targets that have proved satisfactory to the CNPE.

The advantages of underwater work are numerous:

• Limiting water movement
• Replace remote tooling development and management from the surface
• Reactivity
• Highly adaptable to the environment