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AREVA offers the most comprehensive manufacturing portfolio for nuclear power plant components and equipment. We have designed and manufactured primary circuit components for over hundred reactors in the world. Or are still in the process of doing so. What is more, we supply replacement components for the primary circuit to nuclear power plants all over the globe on time. And spare parts for main coolant pumps.
- Heavy components: Steam generator, pressurizer, reactor pressure vessel and reactor pressure vessel head, reactor pressure vessel internals and supporting structures – all key components for nuclear steam generation
- Mobile equipment: Main coolant pumps (including spare parts such as motors, shafts, gaskets and hydraulic components) for circulating the primary coolant and control rod drive mechanismen for regulating the reactor output
- Large forged, molded and processed parts: they are used in the fabrication of heavy components for the primary circuit of nuclear power plants and in the petrochemical industry
Heavy component factories in Europe
Major components in the primary circuit of reactors
Reactor pressure vessel and internals
The reactor pressure vessel (RPV) is the main component of the primary circuit of a nuclear power plant. It hermetically encloses the reactor core consisting of the fuel assemblies. The reactor internals – a complex network of supports, plates, guide tubes, shielding and baffle plates – form a solid infrastructure for the reactor core protecting it against vibration. The thick walls of the RPV consisting of non-alloyed steel (20 to 30 cm thick and lined with stainless steel) safely enclose the radioactive primary coolant under high pressure.
Some data on RPV in EPR nuclear power plants:
- height: 13 meters (including RPV head)
- diameter: 5.4 meters
- weight: 526 metric tons (including RPV head)
- wall thickness: more than 30 centimeters
AREVA has extensive experience in the fabrication of RPV and their internals: To date, we have delivered 81 RPVs for pressurized water reactors and over 80 internals and a large number of components for new reactors.
Reactor pressure vessel heads
The reactor pressure vessel (RPV) heads are lined with stainless steel and weigh between 60 and 100 metric tons. They must be constructed in a way that ensures the efficiency of the pressure boundary: The RPV heads contain precisely manufactured openings allowing the control rods to be operated to control the chain reaction.
AREVA as an OEM has delivered around 80 RPV heads to date. Our factory Châlon/Saint-Marcel in France has a yearly manufacturing capacity for 10 to 15 heads.
We were the first company in the world to design services for replacing RPV heads already in 1992. Since we have replaced over 64 RPV heads in Europe, Asia and the US, including disassembly, reassembly and testing.
An efficient primary cooling system is crucial to the energy conversion process in a nuclear power plant. The pressurizer is a key component: It ensures that the coolant, which transports the heat, is kept under constant pressure.
The pressurizer is a cylindrical, vertical steel container which is equipped with electrical heating rods. They help regulate the water pressure in the primary circuit. The system keeps the pressure in the primary circuit constantly at 155 bars to prevent the water from vaporizing and ensuring optimal heat absorption.
Some data on pressurizers in EPR reactors:
- weight: 113 metric tons
- height: over 13 meters
- diameter: nearly 3 meters
Our factory Chalon/Saint-Marcel in France has manufactured and delivered 73 pressurizers for pressurized water reactors to date.
Replacing a pressurizer is economically advantageous compared to overhauling: Because the replacement eliminates problems in terms of stress corrosion and cracks discovered at the heating rod sleeves made of Alloy 600 or at bimetallic butt welds. For this reason, numerous nuclear power plants in the world are planning to replace their Alloy-600 components with new Alloy-690 parts. In the US in 2008, we replaced the pressurizer in the nuclear power plant Sainte Lucie with a new pressurizer from AREVA – an operation that was unparalleled in the world.
In this component of a pressurized water reactor heated, pressurized water transfers the heat procuded in the reactor core to the secondary system. The steam generated there drives the turbine blades. Maintaining the relevant characteristics in the steam generator, especially for the tube bundle, is crucial to the safety and performance of a nuclear power plant.
Some size data:
- steam generators in EPR reactors weigh over 500 metric tons
- steam generators in EPR reactors have a height of 24 meters
- the steam generator in the US nuclear power plant Saint-Lucie has 18,000 bores
- a single steam generator in EPR reactors accommodates 140 kilometers of tubing.
AREVA as an OEM has delivered around 330 steam generators to date. Our product range is very varied in terms of capacity, weight and the number of tubes: So our steam generators are suitable for any nuclear power plant design.
If the tube bundles suffer from excessive corrosion, replacing the steam generator is often the most economic solution to restore or even increase the performance and to extend the lifetime of the nuclear power plant.
We have installed more than 86 replacement steam generators since 1998. In the US, AREVA won half of all steam generator replacement projects. We also provide support in terms of design and approval issues.
Vessels and supports
The most important auxiliary components that contribute to the safety of nuclear power plants include: accumulators, boron injection vessels, supports for horizontal and vertical steam generators, pumps and the reactor pressure vessel (RPV), lifting beams for the RPV head and RPV internals, the RPV support ring and deflection protectors at main coolant lines etc.
AREVA manufactures each of these components:
- in compliance with international and national standards and guidelines, using state-of-the-art machining, welding and assembly processes
- and subjected to stringent pressure tests and/or stress tests in the factory prior to being installed in the power plant.
The boron injection vessel is the most important vessel in this group. Its main function is to inject a concentrated boron solution into the primary circuit under abnormal operating conditions, for instance after bursts of the live steam pipe or the feedwater pipe. Each injection vessel features a separate boron injection pump. Boron absorbs the free neutrons, which sustain the nuclear fission process, thus disrupting the chain reaction.
AREVA has manufactured more than 50 boron injection vessels. The boron concentration required to disrupt the chain reaction could be decreased owing to technical advancements.
The accumulators, too, contain boron-treated water. It flows out once the pressure inside the reactor falls below the normal value, causing additional coolant to enter the primary circuit. The accumulators made of stainless steel or with stainless steel cladding we manufacture weigh between 32 and 38 metric tons.
Steam generator heating rod supports
These stainless steel supports hold the tubes in the steam generators, thereby preventing pipe bundle vibrations or increased action during external impact (for example, earthquakes). AREVA's supporting constructions are extremely durable
Reactor coolant pumps and motors
Cooling water plays a decisive role both in the primary and the secondary circuit: In pressurized water reactors it dissipates the thermal energy from the reactor pressure vessel and transfers it to the feedwater of the secondary circuit in the steam generator. For the coolant to circulate efficiently and reliably in the reactor cooling circuit, reliable pumps and motors are needed.
AREVA is world leader in the design of reactor coolant pumps, primary sealing systems and associated services. To date, we have manufactured and supplied more than 400 reactor coolant pumps around the world.
Our JSPM plant designs and manufactures all reactor coolant pump components (motors, pumps, hydraulic sections, and shaft seals) and manages every aspect of their operation, from installation to servicing checks.
JSPM specializes in the replacement of reactor coolant pump components and provides a range of associated services:
- modernization of components and integration of modifications
- supplying of a wide range of replacement parts
- fast delivery of components
- modernization of motors on site or in the workshop.
AREVA teams are fully committed to improving the reliability of power plants and reducing disruption associated with plant shutdowns. Since 1994, AREVA has successfully dismantled or fitted:
- 160 motors
- 140 pumps and hydraulic systems.
Control rod drive mechanism
In order to control the chain reaction, it must be ensured that the control rods, which consist of neutron-absorbing material, assume their positions at exactly the right moment. The control rod drive mechanism are responsible for this; the control rods are connected to their bottom end: by moving the control rods in the reactor core up or down and keeping them at the desired position. The control rods are moved in discrete single steps.
A control rod drive mechanism comprises a 6.5 meter high, pressure-proof cylinder which retains the coolant and accommodates the drive mechanics. The drive mechanism includes a ratchet drive with grippers for moving or keeping the drive rod in position, a set of electromagnetic coils as step motor and the drive rod.
We have replaced control rod drives since 1994. AREVA has completed over 100 of such operations so far. They can be scheduled. Or they can be executed in emergencies, for example, when a control rod drive mechanism malfunctions or the gasket of the cover leaks.
Our teams can be mobilized upon shortest notice: 72 hours in Europe, five days in the US and approximately one week in China.
In the heart of an EPR reactor steam generator (3D animation)
Steam generators are essential components in the primary system of a pressurized water reactor. They transfer the heat procuded in the reactor core to the secondary system. The steam generated there drives the turbine blades. Visit the heart of a steam generator.
Design and operation of a reactor coolant pump (3D animation)
For the coolant to circulate efficiently and reliably in the reactor cooling circuit, pumps and motors are needed. This 3D animation shows the design and operating principle of a main coolant pump.
How does a control rod drive work? (3D animation)
The chain reaction during the fission of the U-235 uranium isotopes must be controlled reliably – by the control rods taking their position at the exact time. This is managed by the control rod drives.