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TLD Territorial Network

The territorial network of thermoluminescent dosemeters (TLD) (Figure 1) is one of the most important components of the Czech Radiation Monitoring Network. It was started in 1989 to measure ambient dose equivalent H*(10) [µSv] in the environment on the republic's territory. Most of the measuring points have been placed outdoors where the dosemeters are exposed in free space geometry; however, some of them have also been installed in adjoining buildings with the intention to obtain information about the shielding effectiveness of inhabitants in case of a radiation accident. At present, the number of monitoring points is 180.

 

Figure 1: Territorial TLD Network

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The dosemeter has form of a card containing 4 thermoluminescent detectors inserted in a cover with incorporated different filters (Figure 2). The thermoluminescent material used is LiF:Mg,Cu,P. The dosemeters are measured by means of automatic TLD Harshaw 6600 reader (Figure 3).

Figure 2: Parts of the thermoluminescent dosemeter

tldDosimeter.jpg

Figure 3: Automatic TLD system Harshaw 6600

System Harshaw

 

In case of a normal radiation situation, the measurements are performed quarterly. The output is mean value of ambient dose equivalent rate H*(10) [nSv/h] calculated for each monitoring point. Distribution of results is shown in Figure 4. The values of H*(10) [nSv/h] usually do not exceed the range from 70 nSv/h to 250 nSv/h. These results represent values of the natural radiation background in the environment of the Czech Republic.

Figure 4: Distribution of mean values of H*(10) [nSv/h] measured on the territory of the Czech Republic in 2017

Distribution of mean values of Hx

Regions in the Czech Republic

Praha - Prague, STČ - Central Bohemia, JČ - South Bohemia, ZČ - West Bohemia, SČ - North Bohemia, VČ - East Bohemia, JM - South Moravia, SM - North Moravia