Mitsubishi Nuclear Energy Systems, Inc
6210 Ardrey Kell Road, Suite 350 , Charlotte, North Carolina, United States

Mitsubishi Nuclear Energy Systems (MNES) was founded in 2006 as the U.S. nuclear operations office for Mitsubishi Heavy Industries, Inc. (MHI).  From its headquarters in Charlotte, NC, MNES is leading the way for safer and more reliable nuclear energy.

Services & Technologies 

MNES offers some of the worlds most advanced services, technologies and components to the United States for use in operating nuclear stations.  MNES provides replacement reactor vessel closure heads, reactor coolant pumps, steam generators, and pressurizers, as well as robotic and non-destructive examination (NDE) systems.

Our design philosophy is “safety-first”, and that philosophy is reflected in all of our operations and designs.  The US-APWR incorporates the principles that were built into Mitsubishis twenty-four pressurized water reactors (PWRs) in Japan, which have operated safely for the past 40 years. The US-APWR also institutes new levels of safety and security by incorporating decades of nuclear operating experience and state-of-the-art safety systems.  The US-APWR achieves this new level of safety by incorporating a hybrid design that combines independent active safety systems with passive safety systems. These systems are state-of-the-art, each system is built upon nuclear industry principles of defense-in-depth, fail-safe operation, and backup redundancies.  The US-APWR also has a larger battery bank than existing reactors, allowing the plant to operate much longer without power. And, like our gas turbines, these batteries are protected from seismic damage and water damage by 21st century construction techniques.

Nuclear Services

Mitsubishi has a diverse portfolio and strong history of nuclear service work around the world.  In the U.S., those services have primarily been focused on component replacement.  MNES is bringing unique state-of-the-art services to the U.S. nuclear industry that provide proven operations management solutions in the areas of asset management and long-term viability.

The US Advanced Pressurized Water Reactor

The US-APWR grew out of the expertise gained by Mitsubishis design and construction of 24 PWRs in Japan.  This new design, specifically engineered for the United States, achieves superior safety, reliability, economy and compatibility with the environment.    Improvements in the US-APWR over earlier designs include a thermal efficiency of 39%, the highest in the industry; a 20% reduction in plant building volume; and greater economy by increasing power generation capacity to 1,700 megawatts.  Because safety is the most important requirement of a nuclear power plant, the US-APWR incorporates numerous technical improvements to further enhance its safety features. The design philosophy of “independency and redundancy” is applied to the emergency core cooling system. The probabilistic safety analysis (PSA) technique has been applied to minimize the risk of accidents of all levels of severity and verify plant safety if an accident does occur.  Mitsubishi manufactures the heavy components of the primary system for the US-APWR in its Kobe Shipyard, which is uniquely capable of the task. The remaining 70% of the plant (such as compressors, small pumps, tanks, valves, process sensors, cranes, hoists, and HVAC), are comprised of items made in the US.  Based on extensive experience spanning over 50 years, Mitsubishi has provided reliable products and services for PWRs, nuclear fuels, advanced reactors and the nuclear fuel cycle.

Benefits of the US-APWR

The US-APWR design replaces the 2-train emergency core cooling system used in conventional plants with a 4-train system with no header or connecting piping. This simplified design enhances the redundancy and independency of the system. The refueling water storage tank, a component placed outside the containment vessel in conventional plants, is located inside the containment vessel in the US-APWR in order to avoid the switchover operation from ECCS injection to recirculation during loss-of-coolant accidents.  A new high-performance accumulator system is introduced to regulate the emergency core cooling system design. It incorporates the functions of both traditional accumulators and low-pressure injection pumps.  The US-APWR replaces the traditional diesel generators with more reliable, air-cooled, fast-start gas turbine generators. This ensures immediate backup power will be supplied to the safety and cooling systems in the case of a station blackout event or other serious accidents.   All of systems have been extensively tested and verified in operating plants in Japan. Safety is Mitsubishis first priority.