Radiation Situation Monitoring System
Radiological situation at KhNPP site, its sanitary protection zone and radiation surveillance zone is monitored in line with KhNPP Radiation Control Regulations approved by sanitary and epidemiological surveillance authorities in Khmelnitsky region and the State Nuclear Regulatory In-spectorate of Ukraine.
Automated Radiation Situation Monitoring System (ARSMS) has been implemented to operate in parallel with the existing radiation monitoring system, which was carried out within the framework of KhNPP-2 start-up and implementation of Programme for Upgrade of Ukrainian WWER-1000 NPPs.
ARSMS is intended to improve monitoring of NPP radiological parameters by computerizing their measurement, acquisition, processing, display, archiving and storage.
ARSMS purpose is to:
• Continuously monitor radiological situation at NPP site, its sanitary protection zone and radiation surveillance zone under all NPP operating modes (normal operation, design-basis and beyond de-sign-basis accidents, and decommissioning activities) in the scope that is sufficient to decide promptly if radiological situation meets or does not meet regulatory requirements that define NPP radiological safety measures and procedure;
• Provide reliable information about radiological situation and predict its time-related changes, also for obtaining information needed to measure activity and define composition of radioactive nu-clides that spread beyond NPP site;
• Provide recommendations to assist in decision-making for eliminating/mitigating radiological ac-cident consequences.
ARSMS main functions include:
• Automatic acquisition and processing of radiological parameters;
• Automatic acquisition and processing of meteorological and other non-radiological parameters;;
• Verification of data reliability, alarm in case set-points are exceeded;
• Data storage in the long-term archive;
• Display of current and retrospective ARSMS parameters;
• Communication of ARSMS data to other interfacing systems.
ARSMS collects real-time data, ensures their long-term storage and provides current and retrospective data about meteorological parameters and radiological situation in the established monitoring points. Such amount of information is sufficient to make a conclusion whether permissible levels established for NPP staff and members of the public at NPP site, its sanitary protection zone and radiation surveillance zone and specified in Radiation Safety Norms of Ukraine are exceeded or not.
ARSMS includes 15 container type monitoring stations, four of which are located on the NPP site, while the rest are within the 30-kilometer zone. Besides, there are 14 on-site sensor-based points that monitor gamma dose rate. Data collected from all these facilities are transferred to data acquisition station, which is part of central monitoring station and located in the off-site Radiation Monitoring Laboratory, and to two data acquisition stations located on-site. The information is transferred via cable communication lines and radio links (to the monitoring stations located in the sanitary protection zone and radiation surveillance zone). ARSMS provides automatic measurement of the following radiological and meteorological parameters:
• Gamma dose rate;
• Volumetric activity of aerosols and volumetric activity of radioactive iodine in the air;
• Volumetric activity of radioactive nuclides in water;
• Wind velocity and direction;
• Atmospheric pressure;
• Relative air humidity;
• Radiation balance and total solar irradiance;
• Atmospheric stability class.
Equipment of monitoring stations is located inside stationary container type stations equipped with intrusion and fire alarm systems, and also temperature control systems.
ARMS functions in two modes – monitoring of normal radiation situation, and monitoring of emergency radiation situation. Basic mode of normal radiation situation monitoring corresponds to normal operating mode of Khmelnitsky NPP. ARMS switches over to monitoring of emergency radiation situation automatically or by command of duty engineer given the increase of level of equivalent dose rate or in cases specified in “Radiation Monitoring Regulations at KhNPP”. Personnel of ARMS laboratory controls the system hardware and software functioning round the clock.
Radiological data and meteorological parameters are sampled every 2 minutes.
Meteorological parameters and gamma background in KhNPP area are provided on-line to KhNPP official website.