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Safety Measures at Nuclear Power Plants

Nuclear power plants in Japan have multiple safety measures, which are designed on the assumption that they must ensure the safety of the neighboring communities so that there will be no adverse impacts on their health.

Nuclear power plants are designed to prevent abnormal incidents from occurring. Even if abnormal incidents occur, nuclear plants are also designed to prevent the potential spreading of abnormal incidents and leakage of radioactive materials around plants, which may cause adverse impacts on the surrounding environment.

 Japanese power plants utilize redundant safety measures to keep residential communities around them safe at all times. Measures to be put into action in order to ensure safety during unusual events can be summarized in the following three points:

1. To shut down operating reactors

2. To cool down reactors so as to remove heat from nuclear fuel

3. To contain radioactive materials

Aseismic Measures

Several safety measures against earthquakes are taken at all stages of design, construction of nuclear power plants.

Environmental Radiation Monitoring

Nuclear operators monitor environmental radiation around their facility and radioactivity in environmental samples in order to confi rm that there is no harmful effect on the surrounding environment.

Local governments as well as utilities independently measure radiation dose in the air by radiation monitoring systems around nuclear power plants. In addition, they periodically collect seawater, soil and agricultural as well as sea products to measure and analyze them for radioactive material content and to ensure that power plants have no adverse impact on the surrounding environment.

Safety Assurance Measures implemented after the Fukushima Daiichi Accident

Recognizing the severity of the accident at the Fukushima Daiichi nuclear power station where all power sources for units 1, 2, 3 and 4 failed due to the tsunami, the electric power companies in Japan have committed to reinforcing safety assurance measures at their nuclear power plants focusing on measures against tsunami.

Determined to avoid a repeat of this accident, the electric power companies have been taking both tangible and intangible measures since immediately after the accident, starting with emergency safety measures including the installation of additional emergency power source vehicles and fire engines, as well as upgrading procedure manuals and conducting drills.

The electric power companies have taken diverse measures to ensure that these measures are effective, such as reinforcing the on-site communication system and preparing high-dose resistant protective clothing to allow necessary actions to be taken even in case of a severe accident. The companies are also taking medium- to long-term measures which include installing additional permanent emergency power supply units on high ground, constructing coastal levees, modifying watertight facilities, and large-capacity temporary seawater pumps, in case of a station blackout and loss of sea water cooling systems, and to increase their safety margin.

To enable these efforts to be constantly and objectively evaluated, the Japan Nuclear Safety Institute (JANSI), evaluating the safety improvement activities of electric power companies and giving them technical advice, and the Nuclear Risk Research Center (NRRC), using Probabilistic Risk Assessment (PRA) and proposing solutions based on R&D, were established. The electric power companies take to heart the evaluations and recommendations and are striving to achieve the highest safety level in the world.

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