Nuclear Power Dept. I
Nuclear Power Department I is the distributor of Framatome, the world's largest manufacturer of nuclear reactors, and provides maintenance, services, and consultations for nuclear power plants in Japan. Also, the Department I is the agent and distributor for Siemens Energy, a major manufacturer from Germany, and manages outages and large components replacement projects such as their steam turbines for Japanese nuclear power plants.
In the event of a severe accident(accident with core damage), the "Filtered Containment Venting System" is an emergency ventilation system to reduce pressure and temperature inside of the containment vessel and to mitigate the release of radioactive materials to the atmosphere.
Filters are installed in a tank located outside of the reactor building, where the containment vessel is located. The vent gas drawn from the containment vessel through the pipe is passed through chemicals and metal fiber filters in the tank to reduce radioactive iodine and cesium levels lower than 1/1000 to 1/10000 before the gas is released to the atmosphere.
We have delivered this system designed by Framatome to approximately half of the nuclear power stations in Japan.
During design basis and severe accidents large quantities of combustible gases like hydrogen and carbon monoxide are released to the atmosphere. In case of uncontrolled combustion, the resulting loads can endanger the containment integrity. The containment integrity as last barrier preventing radioactive releases has to be ensured under all circumstances.
Passive Autocatalytic Recombiner(PAR) is a device to deal with such incidents, reducing the hydrogen concentration in the containment by reaction of hydrogen with oxygen by means of catalysts(platinum and palladium).
We have delivered German Framatome products to approximately a half of nuclear power plants in Japan.
During severe accident situations in nuclear power plants(NPPs) significant amounts of radioactive isotopes might be released from the containment, either through containment leakages or by intentional containment venting. Most of them, like iodine or cesium, can be filtered by proven technology. Only radioactive noble gases, mainly Xenon and Krypton(especially Xe-133 and Kr-85) are difficult to retain because of their low chemical activity. For the staff working inside main control rooms, emergency control rooms or emergency response centers in the plant, fresh air supply without radioactive noble gases is required. Common heating, ventilation and air-conditioning(HVAC) systems would flush Xenon and Krypton into these locations and expose the staff to the radiation of these isotopes.
The Control Room Accident Filtration(CRAFT) system, developed by Framatome, is a dedicated filtration system to protect the environment in the control rooms and emergency response centers from airborne radioactivity releases during accidents. CRAFT features both filtration capabilities for airborne substances and noble gas retention(based on dynamic adsorption of noble gases). Its innovative design, with the use of special activated carbon beds, ensures the availability of safe and breathable air for control room staff and emergency personnel. The filtration system automatically regenerates its carbon beds when saturated and enables the system to be used for the entire duration of the emergency.
Removing radioactive oxide layers in the system, such as in piping and components, reduces the dose rate, improving the working environment and dose exposure significantly in nuclear power plants. The CORD process is developed by Framatome, and consistently shows high DF(Decontamination Factor) and less waste(spent resins), verified by hundreds of application references in Japan and other countries.
To meet Nuclear Power Plant's underwater examination needs, we have developed a specific and advanced Submarine System for Inspections(SUSI). SUSI can be outfitted with a large range of tools including cameras, UT transducers, and retrieval of foreign objects(FOSAR) tools. In the water, SUSI is neutrally buoyant and is the most stable delivery submarine system in the industry. Four independent degrees of freedom make SUSI the most maneuverable submarine in the industry to provide the examination without compromising quality. SUSI is easily adapted and reconﬁgured for the changing needs of the nuclear industry. The system is easily set up and removed from containment to minimize impact to the overall outage.
Siemens Energy Turbines have been developed with state of the art analysis and design tools. This has enabled them to achieve improved efficiency and reliability with highly efficient turbine rotors, leading to reduction of fossil fuel consumption and CO2 emissions. Siemens Energy turbines are used in many thermal and nuclear power stations around the world.
We replaced the Condenser Tube Bundles with titanium tubes, leading to improved reliability. This led to improved thermal efficiency by optimizing the tube layout.
PCI Sureflow ® strainer was developed to prevent emergency core cooling system and containment recirculation system blockages. It has been installed in many nuclear power plants in the United States and Japan.