RU2297073C1 - Gas-filled ionization chamber - Google Patents

Abstract

FIELD: recording nuclear radiation (neutrons) in nuclear reactor control and protection system.

SUBSTANCE: proposed gas-filled ionization chamber has sealed enclosure that can be used as electromagnetic field shield or as guard electrode in its pulsed or current mode of operation, sealed insulated leads, electrodes, and ceramic insulators. Electrodes are made of equal-length tubes; each electrode is assembled of set of tubes coaxially disposed one within another and joined together at ends by means of jumpers; tubes have notches to receive jumpers of adjacent electrode.

EFFECT: enhanced sensitivity, reduced size, ability of using any number of electrodes, enhanced reliability and vibration stability.

1 cl, 1 dwg

Description

The technical field to which the invention relates is the registration of nuclear radiation, mainly the registration of neutrons in control systems and protection of nuclear reactors (CPS).

Known ionization chamber (RF Patent No. 2215343) with electrode systems in the housing, having one or more sealed volumes with pumping tubes and electrical leads from each electrode of the electrode systems. The electrode system of the chamber is formed by pairs of coaxial cylinders, which does not allow to obtain the largest surface of the electrodes, since between the cylinders of the electrodes themselves, as well as the cylinders and the body, there is a space that is not filled with electrodes.

As a prototype, a KNT-31 type camera was chosen, which has a two-electrode system formed by a set of coaxial thin-walled cylinders with outer diameters of 10, 18, 26, and 32 mm. The three inner cylinders are clamped with a central pillar between two conical ceramic insulators. A cylinder with a diameter of 32 mm is a chamber body, the ends of which are hermetically closed by flanges (A.B.Dmitriev, E.K. Malyshev. Neutron ionization chambers for reactor technology. - M .: Atomizdat, 1975, p. 61).

The disadvantages of the prototype are: firstly, unsatisfactory vibration resistance, since due to the use of conical insulators and cylinders of electrodes of different lengths, only one cylinder is clamped between the insulators, and the other two are obtained with a gap; secondly, the possibility of deformation of the clamped cylinder during assembly, since all the tightening forces fall only on it; thirdly, a decrease in the total surface of the coated electrodes due to the difference in the lengths of the electrodes; fourthly, in this design, to increase the surface of the coating, the camera body is used as an electrode, which does not allow it to be used directly to shield the electrodes from external electromagnetic fields or as a guard electrode. A guard electrode is a structural element having a potential close to the potential of the collecting electrode, designed to exclude the influence of the current through the insulators on the current in the circuit of the collecting electrode.

The technical result achieved by the implementation of the proposed device is to increase the sensitivity by increasing the surface of the coated electrodes with the effective use of the internal volume of the chamber, to reduce the size of the structure due to the possibility of using a set of electrode tubes with small diameters (for example, 4, 8, 12, 16, 20, 24 mm), in the possibility of using any number of electrodes due to the formation of such an electrode design, in increasing the reliability and vibration resistance due to hard unity tubes webs held together by welding, the ability to use the camera shell as a screen against external electromagnetic fields or guard electrode when the camera or in a pulsed current mode due to the camera shell which is electrically insulated from the electrodes.

The specified technical result is achieved due to the fact that in a gas-filled ionization chamber, which includes a sealed enclosure, sealed electrical insulated leads, electrodes, ceramic insulators, electrodes made of tubes of equal length, each of the electrodes consists of a set of tubes that enter one another, coaxially located relative to each other and united at both ends by jumpers, which provides mechanical fastening of the electrode tubes and the exclusion of rotation of the electrodes relative to other from another, an electrical connection between the electrode tubes and the terminal, the tubes having cutouts for passing jumpers of the adjacent electrode, and the jumpers are made of electrically conductive material and are connected by the same name to the tubes.

The proposed camera is shown in the drawing.

The gas-filled ionization chamber contains a sealed shell 1, sealed electrically insulated leads 2, two electrodes 3, 4 (maybe more), ceramic insulators 5 and jumpers 6, 7.

The operation of the gas-filled ionization chamber is as follows. The output of one of the electrodes of the electrode system is connected to a constant voltage source "+". The output of the other electrode through the input resistance of the secondary equipment is electrically connected to the grounded body of the ionization chamber and the “-” output of the constant voltage source. When a neutron flux acts on the ionization chamber, ionizing particles fly out of the electrode coating into the interelectrode space, as a result of which the gas is ionized in the interelectrode gap and an electric current arises, the value of which is a measure of the neutron flux density.

At present, a gas-filled ionization chamber is used in control and protection systems of the RBMK type reactor at KuNPP and LNPP.

Claims (1)

Gas-filled ionization chamber, including a sealed enclosure, sealed electrical insulated leads, electrodes, ceramic insulators, characterized in that the electrodes are made of tubes of equal length, each of the electrodes consists of a set of tubes that enter one another, coaxially located relative to each other and combined at both ends with jumpers, and the tubes have cutouts for passing the jumpers of the adjacent electrode.