Atmea1 Reactor


Figure 1 ATMEA Nuclear Power Plant Simulation [3]

     Turkey was agreed with ATMEA company on 03.05.2013 for the nuclear power plant planned to be built in Sinop. The selected reactor type for the plant to be built in Sinop is ATMEA Pressurizer Water Reactor (PWR). This reactor which has active and passive safety system, is a Generation III reactor design. Japanese Itochu and Mitsubishi and French GDF Suez set up partner enterprise group and they undertake this project. Project investment predict between 20-25 billion dollars for the power plan. The first unit of the nuclear power plant construction planned to start in 2017and it will be start operation in 2023.

    ATMEA is a jointly established company by AREVA (AREVA NP) and Mitsubishi Heavy Industries, Ltd. (MHI) in 2007. Purposes of establishment are marketing, selling and design a PWRs which producing 1100-1150 MWe, have innovative and proven nuclear technologies, top security systems, high thermal efficiency. This company has 40 years PWRs experiences, they built more than 130 reactors and provides service in more than 350 reactors.

Introduction of ATMEA1 Reactor

Table 1 ATMEA1 Technical Data

General Plant Data
Full Name ATMEA1
Reactor Type PWR
Coolant Light Water (H2O)
Moderator Light Water (H2O)
Neutron Spectrum Thermal Neutron
Thermal Capacity 3150.00 MWth
Electrical Capacity (max.) 1150.00 MWe
Power Plant Efficiency, Net 36 %
Plant Design Life 60 Years
Plant Availability Target 92 %

Safety Goals
Core Damage Frequency 1x106/Reactor-Year
Occupational Radiation
0.5 Person Sv/RY
Nuclear Steam Supply System,
Steam Pressure 7.2 MPa

Reactor Coolant System
Primary Coolant Flow Rate 6889 kg/s
Reactor Operating Pressure 15.5 MPa
Core Coolant İnlet Temperature 291 °C
Core Coolant Outlet
326 °C

Reactor Core
Fuel Material UO2 and MOX
Cladding Material Zirconium Alloy
Rod Array of a Fuel Assembly 17x17
Number of Fuel Assemblies 157
Enrichment of Reload Fuel at Equilibrium Core 5.0 wt%
Fuel Cycle Length 24 Months
Control Rod Absorber Material AlC/B4C
Soluble Neutron Absorber H3BO3

Reactor Pressure Vessel
Inner Diameter of Cylindrical
4250 mm
Base Material Low Alloy Steel

Steam Generator
Type U-Tubes with axial Economizer
Total Tube Outside Surface
8000 m2
Tube Outside Diameter 19 mm
Tube Material TT690 Alloy
Reactor Coolant Pump Flow at Rated Conditions 6.89 m3/s
Pressurizer Total Volume 65 m3

       ATMEA1 which is a 1100MWe class PWR, including most modern, proven technologies developed by AREVA and MHI, operated, licensed and certified systems and components. It has basic common design features that can be adapted to the regulatory and commercial requirements of the country to be built. It is a three-loop reactor with 3150 MWth power for 60 years life. The primary system is similar to the standard PWRs for the loop configuration and main components.

      ATMEA1 has basic safety features such as resistant containment building for aircraft hazard, three emergency cooling systems, core pool for serious accident like a melting core.

         The following features of ATMEA1 provide examples of the most modern, proven technologies:

· Steam generators with axial economizer,

· Advanced accumulators,

· Reactor internals with Heavy Neutron Reflector,

· Digital Instrumentation and Control (I&C),

· Top mounted instrumentation.

Design Features

      Reactor Cooling System (RCS) includes:

· A Reactor Pressure Vessel (RPV) that contains the fuel assemblies,

· A Pressurizer (PZR) including control systems to maintain system pressure,

· One Reactor Coolant Pump (RCP) per loop,

· One Steam Generator (SG) per loop,


Figure 2 Nuclear Power Plant Containment Building Simulation [5]

      Containment building is made of concrete and steel lining. This structure is resistant to any aircraft attack can cause the danger and explosion.

    Inside the containment and below the RPV is a dedicated spreading area called “Core Catcher” for molten core material following a postulated worst-case severe accident.

     The fuel pool is located in a private building outside the containment building to make easier fuel transportation at the time of operation. This building has three different cooling systems.

      The core consists of 157 fuel assemblies. Core has the radial heavy neutron reflector is designed:

• to improve neutron utilization, thus reducing the fuel consumption,

• to reduce the RPV irradiation,

      Fuel cycle length is between 12 and 24 months. Each fuel assemblies consist 17x17 fuel rods which are square array and each fuel assemblies include 24 control rods. These control rods have a neutron absorbing material in a stainless-steel tube. The fuel rods contain enriched uranium dioxide or MOX pellets, some of which may contain uranium dioxide pellets blended with Gadolinium.

      A 16-days are required for refueling. This time is very short compared to another reactor. Power plant maintenance is done when power plant is in operation so, the cost of shutdown is zero during maintenance. Operation, maintenance and accident management are made easier so, the risk of human error has decreased. Owing to the 12 to 24 months fuel cycle options, it allows you to plan for disruption and provides the lowest fuel cost per MW/hr.


  Design Philosophy

     The ATMEA1 reactor has three main design philosophies. These are:

• Reduced core damage frequency (CDF),

• Mitigation of severe accidents,

• Protection of critical systems from external events (e.g. airplane crash) [5].

Licensing Status

    ATMEA1 is based on technologies developed by AREVA and MHI. The ATMEA1 reactor abide by international regulatory requirements, codes and standards. Design is based on licensed and proven technologies, tried and tested components.

Figure 3 ATMEA Nuclear Power Plant Simulation

       For ATMEA1, active and passive systems are optimized for reliability and economic purposes. Three independent top-level security systems are completely different from operational systems and protect against external threats. One example of passive safety systems is advanced batteries.

       Depression resistant construction design which proved to be based on high seismic activity, has reliable equipment.

      The plant is prevented from falling into flood waters by the platform up-rise and dry-site concept. I&C equipment are located on the upper floors and all buildings related to security are protected by waterproof walls and doors are provided additional safety margin.

     Reinforced concrete armor or equipment spread over the site are provided all the equipment needed to keep the plant in a safe condition without any off-site support. Each reactor is a closed system designed to protect the cold shutdown conditions that can be brought to a safe shutdown condition by itself.


[1] ATMEA1 Brochure,                Date of access: September 2017

[2],            Date of access: September 2017

[3] Status report 99 - ATMEA1 (ATMEA1)                Date of access: September 2017

[4],                Date of access: September 2017

[5] 2012-01 ASN report CODEP-DCN-2011-0700548 Atmea safety option review synthesis,                 Date of access: September 2017