Radioactivity monitoring network





the emblem of the BSH
   
 

Radioactivity monitoring network

   
 
 

Integrated Measuring and Information System for Environmental Radioactivity Monitoring (IMIS)


Within the framework of the Strahlenschutzvorsorgegesetz (StrVG - Act on the Precautionary Protection of the Population against Radiation), the BSH routinely monitors radioactivity in the North Sea and Baltic Sea including the coastal waters. Its function is that of a control station for the Federal monitoring network operated within the "Integrated Measuring and Information System  for Environmental Radioactivity Monitoring"  (IMIS) of   The Federal Environment Ministry (BMU). Radioactivity monitoring covers the following three areas:
  • direct monitoring of accident-related high radioactivity concentrations in sea water by means of the radioactivity monitoring network
  • determination of specific radionuclides in sea water, suspended particulate matter and sediment based on extensive sampling and analyses (including trace analysis) within routine monitoring programmes, and
  • drift forecasts after incidents.

Within the radioactivity monitoring network, which consists of seven offshore stations, six coastal stations, and three mobile ship stations, the total gamma radiation is measured directly in sea water using NaI detectors. The limit of detection of the monitoring measurements is about 1 Bq/l (related to K40 gamma), depending on conditions at the monitoring station. The data are transmitted hourly, via satellite or telephone modem, from the fixed monitoring stations to the BSH's monitoring network computer at Hamburg or Rostock.

The offshore stationsare operated in connection with the oceanographic monitoring network of the BSH. They are installed on unmanned equipment carriers (light-vessel replacement systems, buoy, lighthouse, measuring pile).

The coastal stations are installed on coastal facilities (harbour pier, gauge station, promenade pier, sea water sampling station). In case of an alarm, samples are taken by the personnel on duty.

Because of variable water depths at the coastal stations the measuring instruments used include pressure sensors enabling the influence of cosmic radiation, which varies in dependence on the thickness of the water layer above the measuring instrument, to be compensated in the evaluation of results. Besides, the stations have been fitted with a novel monitoring instrument developed and tested by the BSH which, in addition to the total gamma radiation measurements carried out so far, is capable of determining the activity of individual nuclides by means of gamma-ray spectroscopy. Even small increases in artificial radioactivity within the variable spectrum of natural gamma radiation can be detected in this way, which considerably improves the detection sensitivity of the instrumentation.

Also three vessels of the BSH, as mobile stations, have been equipped with radioactivity monitoring instruments. In case of incidents the ships can detect and measure hot spots of elevated radioactivity or sources of radioactivity in the sea.

The control station computers at the BSH collect the data from the monitoring network stations and evaluate them automatically. An in-house alarm is triggered if the data meet certain pre-set alarm criteria. In case elevated radioactivity levels are confirmed by analyses of the sample that has triggered the alarm, an urgent message is sent to the responsible IMIS office at the Federal Office for Radiation Protection (BfS)(-->"The Ministry" --> "Federal Office for Radiation Protection").

All monitoring data received are routinely checked and evaluated for IMIS.

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 © 2016 Bundesamt für Seeschifffahrt und Hydrographie Last Update: Apr 19, 2013 6:02:28 PM  
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