Building a nuclear power plant, Manoir Industries expertise defined the stainless steel primary loops

Pressurized water reactors are today the most common functioning nuclear powerplants. They are designed with three successive coolant loops. The primary loop drives the heat extracted from the nuclear reaction towards steam generators. The steam generated within secondary loop then drives steam turbines that generate electricity. The coolant water within primary loop circulates within the reactor. It is highly pressurized at around 150 bar to remain liquid at high temperatures (350°C). The primary loop is a critical component that requires an extremely high level of control/quality/homogeneity.

The primary loop is an assembly of tubes, elbows and nozzles of about 1 m diameter and 5-20 tons each. Manoir Industries developed the fabrication of these parts by foundry in the late seventies in collaboration with Framatome (later AREVA) and EDF (French Electricity company). The chosen material was a low carbon austeno-ferritic stainless steel (20Cr- 9Ni) for its great stability over time and the large shared experience on this type of alloy.

Together with their colleagues from Framatome and EDF, Manoir Industries’ staff (metallurgists, founders, controllers, etc) have set all the requirements linked to the specificities of foundry metallurgy and of the required quality for safety. These requirements were later to become a large part of the French nuclear code RCC-M.

Manoir Industries built up its expertise over the 350 parts fabricated since, which are still in service today. We keep on improving our methods and metallurgy for the ongoing project of primary loop fabrication with AREVA. This continuous commitment enables to meet the growing demands towards higher and higher quality and safety.

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