National Report of the Slovak Republic - Radiation and Nuclear Safety , September 1998

4.6.2 Radiation Monitoring by Operator


  1. Radiation Monitoring at SE, a.s.' Nuclear Installations

  2. The radiation monitoring system at nuclear installations and their surrounding areas is a very consequent, good-quality and reliable process. It has two parts:

    Radiation monitoring at nuclear installations represents a set of organizational and technical measures. The aim is to provide information the radiation status within the nuclear power plant, the quality of the technological process of the power plant (tightness of equipment, radiation accumulation at the plant, etc.), assessment, directing and planning of personal doses for NPP employees, including the evaluation of internal contamination of persons and contamination of equipment surfaces. Data from the monitoring network are also made available to certain neighboring countries.

    Protection of nuclear installations employees against the harmful ionizing radiation is based on continuous surveillance of the working conditions along with monitoring of dose load and medical monitoring of the health condition.

    Radiation status in the working place is monitored using stable dosimeters and monitors of gamma radiation, volume activity of airborne particles and gases, and the same parameters are additionally measured using portable devices. Personal doses are evaluated, directed and planned according to the basic principles of protection against harmful radiation so as any activity which results in persons being exposed to radiation has to be justified, optimized and limited. Personal doses are monitored using film dosimeters, thermoluminescence dosimeters and signaling dosimeters which enable flexible evaluation of personal doses. Also, examination of internal contamination is a part of employees monitoring. Fig. 4.6.1 illustrates the development of average collective dose equivalent per one SE-EBO unit.

    Fig. 4.6.1: Average collective dose equivalent per one SE-EBO unit

  3. Atmospheric and Hydrospheric Emission Control Systems
  4. Fig. 4.6.2 Rare gas emissions from V-1

    Fig. 4.6.3 Rare gas emissions from V-2

    Atmospheric emissions are continuously monitored by measuring equipment attached to ventilation stacks. The devices continuously monitor the activity of gases, airborne particles and iodine. Moreover, there is a system for continuous airborne particles sampling for gamma-spectrometric analyses and alpha-nuclide and Sr 90 contents.

    Hydrospheric emissions are continuously controlled for identification of deviations from normal conditions. Continuous sampling of effluent waters serve balancing purposes of total activity beta radionuclides activity, tritium, gamma spectrum and Sr 90 and Pu monitoring.

  5. Monitoring of Environmental Impacts
  6. Radiation monitoring systems at nuclear installations also include assessment of NPP operation impact on the surroundings. Assessment of environmental impact of NPP operation starts by pre-operation radiation monitoring at the construction site and within its surroundings. The obtained set of data serves for actual comparison of environmental impacts of nuclear power plants operation.

    Environmental impacts of nuclear power installations are monitored and documented by External Dosimetry Laboratories. The scope of the controls is determined by a monitoring program which sets mandatory minimum numbers and types of environmental components to be monitored. From the aspect of the potential environmental impact of nuclear power installations, the components of the environment monitored include air, water, soil and related agricultural products as a part of the food chain. More than 1,150 samples are taken from the environment annually.

    A teledosimetric system has been set up to improve the control quality of the impact of nuclear installations and their surrounding. The teledosimetric system is computer-controlled, and enables sampling of airborne particles, radioiodine, dosimetric quantities within the given site as well as meteorological data. Selected results of teledosimetric monitoring are on-line transmitted to the KKC ÚJD.

    Results of direct measurements by stable monitoring stations as well as the results of environmental sample analyses indicate that the operation of NPP Bohunice units has no impact on the surroundings.

    In the view of the very small amounts of atmospheric and hydrospheric emissions from NPP Bohunice, exposure doses of the general population are analyzed to assess the impact of NPP Bohunice operation. This analysis is based on actual discharges and efficiency of radioactive substances for the individual years, accounting for the actual meteorological situation as recorded by the SHMÚ meteorological station at Jaslovské Bohunice.

    This analysis is conducted using standardized software RDEBO to calculate individual dose equivalent (IDE). The calculations have shown that the area with the highest level of effective doses is that located along the prevailing wind direction, i.e. SE of NPP Bohunice, at a distance of approx. 3 - 5 km; the critical age group are infants. Table 4.6.3.3. presents the results of the calculations.

    Year

    IDE [Sv]

    infants

    adults

    1990

    2,618E-5

    5,439E-6

    1991

    1,358E-5

    2,581E-6

    1992

    1,241E-6

    3,642E-7

    1993

    5,038E-7

    2,018E-7

    1994

    4,034E-7

    1,410E-7

    1995

    1,541E-7

    5,939E-8

    1996

    4,64E-7

    1,91E-7

    1997

    3,71E-7

    1,55E-7

    The IDE values shown are substantially smaller than those received by the population from the natural background. At the NPP Bohunice area, individual dose equivalent from natural background is 100 - 10,000 times higher than values shown in the Table.

    In addition to monitoring by the operator, monitoring of the environmental impact is performed by the Regulatory body (ŠZÚ).

    The Slovak Center of Radiation Monitoring Network as well as the Regulatory Authority monitors integral doses intensities within a system of monitoring points in nuclear installation surroundings using TLD method. It also discontinually measures dose within a system of monitoring points in nuclear installation surroundings, monitors the activity of fission products in emissions, airborne particles, drinking water, surface and ground waters, soils, sediments, agricultural products and food products produced around nuclear installation, conducts random parallel analyses of aerosols and samples from collection tanks of waste waters before their discharge.

    Slovak Center of Radiation Monitoring Network (SÚRMS) is a permanent executive unit of the Slovak Government's Commission for Radiation Accidents. It is responsible for methodological preparation of the components of the monitoring network and for their standard procedures in monitoring the radiation status.

    SÚRMS has been established at the Institute of Preventive and Clinical Medicine, Bratislava, as its integral part. The head of SÚRMS is appointed by the Commission Chairman at the suggestion of the Slovak minister of health.

    In times when it has not to deal with any specific radiation accident, SÚRMS reports to the minister of health.

    SÚRMS comprises the following constituents which participate in the monitoring of the radiation situation in Slovakia:


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