System configuration and operation
Internal reactor instrumentation

The thermowells are not rigid enough to hold vertically in the core without external support. They can therefore only be inserted after loading, when the fuel assemblies are in place.

Before and during the first loading, the reactor pool is full: to prevent water from flowing into the instrumentation room, the manual isolation valve is closed, obstructing the passage through which glove fingers can be inserted.

The automatic isolation valves and the connecting tubes between them and the control units are not yet installed, leaving easy access to the sealing nozzle inlet.

Once the core is loaded, the thermowells are presented in front of the sealing nozzle, then inserted and pushed...