Mitsubishi Heavy Industries (MHI) recently launched the SRZ-1200 advanced pressurized water reactor (PWR) design. The SRZ-1200 was developed in collaboration with four Japanese utilities. It is designed to meet Japan’s enhanced regulatory safety standards.
     MHI stated that the SRZ-1200 has additional safety features when compared with conventional pressurized light water reactors. Its design implements enhanced Japanese regulatory safety standards which incorporate lessons learned from the March 2011 disaster at the Fukushima Daiichi nuclear power plant. MHI claimed that the design will ensure the regulatory requirements of “strengthening safety equipment” and “resistance to natural disaster and security against terrorism and unforeseen event” are fulfilled.
     Low probability postulated events are still accounted for in the reactor design to ensure plant and public safety according to MHI. These new safety mechanisms include an advanced accumulator design and systems which effectively reduce the probability of radioactivity release in the event of a postulated accident. Efforts of this nature and the resulting SRZ-1200 design features will limit any impact to the public and plant site.
     In addition, the SRZ-1200 design is also intended to enhance operational flexibility. This will effectively allow for improved electrical power delivery alongside variable electrical power sources such as renewables.
     MHI said, “The ability to adapt the SRZ-1200 for hydrogen production will also be studied to ensure that all potential uses of energy generated from this plant are efficiently and proactively applied for all of societal needs.” It noted that the name of the reactor is derived from ‘S’ for supreme safety and Sustainability, ‘R’ for resilience and ‘Z’ for zero-carbon emissions.”
     The SRZ-1200 has been designed in collaboration with Hokkaido Electric Power Company, Kansai Electric Power Company, Kyushu Electric Power Company and Shikoku Electric Power Company. All of these utilities have experience in operating PWR nuclear power plants.
     MHI has been involved in the construction and maintenance of all of the twenty-four existing PWR nuclear power reactors in Japan. This has led to the efforts to restart and ensure the safe operation of the existing nuclear power plants.
     MHI said that it intends “to take the SRZ-1200 conceptual design and proceed with basic design efforts”. It aims to bring the new design to market “as early as possible” to “ensure new innovative nuclear technologies are available toward a stable energy supply for Japan”.
     MHI said, “Taking into account the Fukushima Daiichi accident, MHI Group strives to continuously enhance safety through the restart of existing nuclear power plants as well as the safe and stable operation upon restart. This is part of our contribution to society and we intend to continue this contribution through the development of advanced light water reactors which achieve the world’s highest level of safety.”
     MHI’s 2021 Medium-Term Business Plan was published in October of 2020. In the plan, MHI said that it planned to develop new reactor designs. It said it was working on a “next generation” light water reactor that will feature safety improvements such as a core catcher and a radiation leak prevention system. MHI said that such a reactor with a generating capacity of up to twelve hundred megawatts will improve compatibility with renewables by increasing “output adjustment capability”. MHI said that it was targeting commercialization of the new reactor design in the mid-2030s.