•  At the nuclear power plant, the gaseous radioactive waste which is exhausted in ventilation of the facility or generated in the power plant is emitted from the exhaust stack after filtering out the radioactive materials.
   The gaseous radioactive waste emitted in the power plant facility is stored in the delay tank for a certain period to weaken radioactivity, and then, being filtered and confirmed that radioactivity concentration is lower enough than the specified standard, released in the atmosphere.
   Exhaust stack monitor is the equipment that monitors the atmospheric radioactive materials continually by sampling the gas released from the exhaust stack.
  
•  The exhaust stacks are divided into two types depending on the facilities of the nuclear power plant; one is the type that ventilates by the system of each, and the other is the type that ventilates all together.
  

 A measured value of the exhaust stack monitor is expressed with the number of radiations that the detector measured in a unit time and is expressed in unit of cps (count per second).
 As a detecting unit of exhaust stack monitor (plastic scintillation detector, NaI Scintillation detector) senses the radiation that natural radioactive nuclides contained in the surrounding wall material or the material of detecting unit itself emit, it detects the value within certain range(background value) even if radioactive waste is not released from the exhaust track.
 Also, for the periodical inspection, the detecting unit of exhaust stack monitor and a waiting spare detector are used in turn. As the background value of the detecting unit is specific to the detector, when the detector is exchanged, a difference may occur for the data before and after the exchange.

In this site, the exhaust stack monitor data of the nuclear power plant is displayed as below

• Web Map Display･･･Exhaust stack monitor data appears in the balloon, which is displayed by pointing the icon of the power plant displayed in the web map by the mouse. The data is displayed as latest 10 minutes data.
• Fixed Map Display･･･Exhaust stack monitor data of each power plant is displayed on the map of “Near area around the power plant”. The data is displayed as latest 10 minutes data.
• Trend Graph Display･･･It is displayed as the time-series graph from past data to the current time for each power plant. 10 minutes data, one hour data, 4 hours data, and one day data are provided.
• Listed Display･･･Latest exhaust stack monitor data of all power plants is displayed in 10 minutes data.

 Each exhaust stack has the different name by its operating facility, and its number is different according to the power plant. This site provides the data of exhaust stack monitors listed below