Training reactor VR-1

Dosimetry and environmental monitoring

From the radiation protection point of view, the monitoring of the reactor is performed by:

  • RMS radiation monitoring system,
  • thermoluminescent dosimeters placed at eight selected locations,
  • portable devices for measurement of equivalent dose rates and surface activities.

RMS radiation monitoring system is a stationary dosimetric system providing continuous monitoring of reactor workplace and its surroundings. It is based on monitoring of dose rates of gamma and neutron radiation and of radioactive aerosols concentration. System is controlled by the central computer providing communication and data collecting and archiving from the particular probes. Particular probes are placed at selected locations of reactor workplace. System works continuously; at ordinary situation the data are recorded in the interval of one hour; if warning or emergency level are exceeded, in the interval of six seconds. The exceeding of warning or emergency level is indicated by acoustic and optical signals. In case of power loss, the system is fed by standby batteries.

RMS radiation monitoring system

RMS radiation monitoring system

Monitoring of persons serves for personal doses determination through monitoring, measuring and evaluation of individual outer and inner irradiation of particular persons. Usually, it is performed by personal dosimeters. The reactor staff is equipped with film dosimeters and DIS1 dosimeters, depending on type of work also with electronical direct-reading dosimeters. During the education at the reactor, each student is equipped with a DIS1 dosimeter, depending on type of education also with an electronical direct-reading dosimeter. During technical visits to the reactor, each third to fifth visitor in the group is equipped with thermoluminescent dosimeter. If needed, the person has also an electronical direct-reading dosimeter or a pen-type dosimeter. Leaving the reactor hall the staff, students and visitors have to undergo check of hands' and foots' contamination.

Potential radioactive waste could encompass used laboratory calibration emitters or etalons. Irradiated samples, irradiated activation foils, used ions exchangers, filters, activated construction materials, and eventually also in-use low burned-up nuclear fuel could belong to this category.. Due to the nature of reactor operation and the power levels being achieved, the amount of radionuclides being introduced into the environment is very low; in majority of cases it is under the detection limits of measuring devices being used. During ordinary reactor operation, no liquid radioactive waste is created. Sewage water from the reactor is led into the emergency collector. From the collector it is repumped into the sewage disposal station; the station serves for all laboratories working with activity. It contains two collecting reservoirs and discharge reservoir. Before the discharge into the sewer system, samples are taken and their activity is measured. Reactor area (i.e. reactor hall and the area above the vessels) is equipped with air conditioning containing output filters for radioactive aerosols filtration. Dosimetric checking of aerosols is carried out through a pair of alpha-beta detectors. During the reactor operation no gas radioactive waste is created

Monitoring of reactor environment and surrounding laboratories is accomplished through monitoring, measuring, evaluating and recording of dose rates, activities, volume activities, and mass activities. It serves for checking of following the limits of allowed discharges, and for early detection and evaluation of eventual releases, their consequences to the population in workplace's surrounding and to the environment. During ordinary operation it serves for proving of operation safeness in the relationship to the environment. Monitoring of environment is achieved via a net of pre-selected observation locations and paths, in which the quantity and distribution of effective doses and their loads are determined. The determination is based on measurement of dose equivalents from outer irradiation and on samples taking and determination of radionuclide contents in air, water and in selected components of the environment and in food

© DNR FNSPE CTU in Prague, 2017