Boliden Aktiebolag

Krister Kristiansson

Erik L Malmqvist

Method for indicating concealed deposits

The invention relates to a method and apparatus for measuring at least one of the parameters flow rate, flow velocity, concentration and quantity of radon and/or radon daughters in the ground. The method is characterized by collecting gas arriving from the ground in a first chamber which is gas-permeable at the bottom thereof, at least the downwardly extending boundaries of the chamber being in contact with the ground, so that atmospheric gas is prevented from passing into the chamber. At least one detector which measures alpha-radiation from the decomposition of radon and radon daughters is placed in a second chamber communicating with the first chamber. Positioning of the second chamber and the detector is selected so that the detector can continuously be observed and utilized for the measuring operation. The gas is allowed to pass continuously. through the chambers over a given period of time, to expose the detector to the gas. Subsequent to this exposure, the measuring result registered on the detector is evaluated. The method can be modified for measuring radon departure from the surface of the ground, the gas-permeable first chamber being arranged over the surface of the ground to be analyzed. The detector is placed in a second chamber communicating with the first chamber. For the purpose of measuring the flow rate and velocity of radon passing through the ground there is provided a first chamber beneath the level of the ground, at a desired depth. This first chamber is connected with a gas-impermeable passage to a second chamber which can be readily reached from the level of the ground and which is sealed against penetration of atmospheric air. The detector is placed in the second chamber.

Method and apparatus for measuring radon beneath and above the level of

The invention relates to a method of measuring the concentration of radon and radon daughters in the ground, particularly at great depth and/or below the ground-water level. In accordance with the invention a detector is freely suspended from a wire and placed in a container intended for collecting gas rising up from the ground. The container is buried at a desired depth beneath the surface of the ground and the detector is exposed to the gas in the container over a given period of time. Subsequent to this exposure period, the detector is drawn up by means of the wire, together with a sleeve, protecting the detector from contact with surrounding ground, through the roof of the container and up through the ground, to a location so selected that the registered contents of radon and radon daughters can then be determined on the basis of the data registered on the detector. The invention also relates to preferred apparatus for carrying out the method.

Method and apparatus for measuring radon in the ground

The invention relates to a method for detecting and measuring alpha-emitting substances, such as radon and/or daughter products of radon, by registering nuclear tracks on a detector. By conducting away during measuring any electrostatic field which may have built-up on the detector, there is eliminated the risk of erroneous information being obtained with respect to the dosage of radiation received. A device in the form of a dosimeter for carrying out the detecting and measuring method is also provided in accordance with the invention. Arranged on or in the immediate vicinity of the registering surface (1) of the detector is an electrically conductive material (2) which at least partially covers the registering surface. In a preferred embodiment, the dosimeter may include at least one absorber (4) arranged between the registering surface and the electrically conductive material. The electrically conductive layer suitably has a constant potential and may be connected to the ground or to a source of electric voltage (FIG. 4).

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Lund, Sweden

Krister Kristiansson