Proven Technology

Proven Technology


The ATMEA1 reactor brings together the very best of EDF Group’s EPR and MHI’s APWR technologies in one medium-powered pressurized water (PWR) reactor. By integrating only operated, licensed and verified systems and components, the ATMEA1 design reflects our top two priorities: safety and reliability.

Greater certainty for operators

Safety authorities, suppliers and operators are familiar with the ATMEA1 reactor’s proven systems, which deliver the following benefits:

  • Reduced licensing risk
  • Secure construction schedule and smooth operation

Tested and operated systems to ensure optimal safety and reliability

The ATMEA1 reactor integrates the following systems and components that are currently used in EDF Group and MHI pressurized water reactors:

  • Steam generators with axial economizer and 690 TT tubes

Steam generators are fitted with an axial economizer that directs and re-circulates feed water throughout the tube bundle, thereby enhancing heat exchange efficiency and increasing steam pressure compared to a boiler-type steam generator with the same tube surface. The tubes are made of alloy 690 TT material, which is highly resistant to corrosion and currently in use worldwide.

  • Advanced accumulators

Passive advanced accumulators enhance safety and reduce costs. In the unlikely case of a primary loop rupture or breach triggering a LOCA, steam generators must be refilled immediately. The advanced passive accumulators provide water in the initial seconds, first at a high flow rate and then at a lower flow rate. Low-head injection pumps are therefore no longer necessary. The accumulator self-activates by detecting the hydrostatic pressure difference.

  • Reactor pressure vessel internals with heavy neutron reflector

The reactor pressure vessel (RPV) internals integrate recent innovations, including a flow-distribution device at the core inlet and a heavy neutron reflector to replace the conventional baffling structure. The heavy neutron reflector is designed to:

- Limit neutrons escaping from the core to improve fuel use and cost,

- Reduce neutron irradiation, which causes the RPV inner wall to become brittle,

- Reduce inspection work by removing bolts from high neutron fluence area,

- Ensure RPV lifespan for more than 60 years.

  • Digital Instrumentation and Control

Optimized digital instrumentation and control (I&C) systems limit susceptibility to failure and human error.

If a design-base event occurs, the Reactor Protection System (RPS) is the reactor’s main I&C line of defense. This system performs all automatic safety-related functions to bring the plant to a controlled state. Located in dedicated cabinets in the nuclear island, the RPS is equipped with three redundant safety trains, as well as an additional backup train. The RPS is functionally independent of all other I&C automation systems.

  • Top-mounted instrumentation

Bottom-mounted penetrations for in-core instrumentation were removed from the reactor pressure vessel and now penetrate from the top. Fewer welds and improved weld geometry improve the manufacturing process and in-service inspection options.

  • Fully tested and validated components

A number of components were developed to simplify system design and enhance reliability to a 60-year service life. These components are fully tested and validated, and most have already been manufactured and constructed.

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