For the past several days, work teams from EDF and Baudin Châteauneuf have been working on the structural steelwork located in the upper part of the enclosures housing the steam generators. What does this work consist of? Nearly 240 rupture disks are being fitted so that the hot-testing phase can begin. Explanations:
In preparation for the hot-testing phase, a large number of activities are being carried out inside the reactor building. One of these activities is being performed on the floor located in the upper part of the enclosures housing the steam generators. Work teams from EDF and Baudin Châteauneuf are fitting nearly 240 rupture risks to the structural steelwork.
These disks, which comprise thin plates each containing a diaphragm, are designed to keep the rooms leak-tight and to resist the pressure differences caused by the ventilation systems operating in this building.
The installation of these disks is essential whilst preparing for the hot-testing phase. These disks must be able to fulfil their function during the next set of functional tests on the reactor building’s ventilation system. The purpose of these tests is also to verify the “two rooms” concept.
"Two rooms" – an innovative concept specific to the EPR.
From as far back as the EPR conceptual design phase, the reactor building was split into two separate areas: the building’s annulus or service area and the equipment area housing the main nuclear systems. This segregation is maintained by static containment structures (walls, neutron-shielded doors, etc.) and by a dynamic containment system (a ventilation system which, by means of depressurisation, circulates air from the service area to the equipment area).
This "two rooms" concept means that the service area can be accessed while the reactor is in operation. It will be possible to prepare for reactor shut-downs (early maintenance on equipment), thereby reducing outage lengths and increasing the EPR’s availability to the grid.