JPS6042429B2 - Ionization chamber type survey meter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an ionization chamber type survey meter.

Various types of ion chamber type survey meters have been proposed and used in the past.

For example, in the case of a device in which the measurement part and the ionization chamber are combined together, the ionization chamber, which is the detection side, and the measurement part side, which has the ammeter, are close to each other, so there is a safety issue regarding exposure to high radiation doses. Therefore, it is desirable to have a structure that isolates the ionization chamber and the measuring section. However, in order to equip the measurement unit with an ionization chamber at a remote location, it is necessary to improve the structure to make it easier to use for measurement, and the background cannot be ignored in order to perform accurate measurements. Improvements are needed to properly erase the indicated value due to background even when the sensor is far from the measuring section.
Currently, there is no survey meter that satisfactorily solves these problems.

Therefore, in this invention, we have obtained an ionization chamber-type survey meter that can solve all of the above problems even if the ionization chamber is installed at a remote location for the measurement section. On the other hand, a circuit is provided in which an ionization chamber is installed at a remote location via a retractable wiring cover pipe, and the indicated value due to the background is erased by a short circuit in a part of the electric circuit on the side near the ionization chamber. It is characterized in that the circuit for erasure can be opened and closed remotely on the measurement unit side.

Next, embodiments of the present invention will be illustrated below with reference to the drawings.

In FIG. 1, reference numeral 10 denotes a measuring section equipped with an ammeter A, which is covered with a casing 12 having a grippable handle 11.

Reference numeral 20 denotes an ionization chamber, which is installed at a remote position from the measuring section 10 via a telescopic wiring cover vibrator 30.

A curl cord (not shown) is installed inside the wiring cover vibrator 30, and the measuring section 10 and the ionization chamber 20 are connected by wiring so that the distance between them can be expanded and contracted. In the illustrated case, the wiring cover vibrator 30 has a diameter of 550 mm as an example.
- 11,607wL is shown as an example that can be expanded and contracted from the position of the three-stage tightening adjustment part 31. It is removably connected to the casing 12 of the measurement unit 10 with the same structure, and when it is desired to move the ionization chamber 20 to a position further away than the allowable expansion/contraction range of the vibrator 30. In this case, the vibrator 30 can be detached from any of the connecting parts and used by connecting another electric wire. Further, reference numeral 32 in the figure is a support leg provided on the wiring cover vibrator 30, which can be raised freely, and provides good stability when placed during use.

Further, in FIG. 3, which shows an example of a circuit in which the ammeter A of the measuring section 10 and the ionization chamber 20 are connected by wiring, the ionization chamber 2
The circuit for amplifying the current from the collector electrode 21 in the ion chamber 20 and reaching the ammeter A is no different from a conventional non-remote type survey meter.

However, in the above circuit diagram, if the switch SWl is set to the resistor R side, the ionizing current flows through the resistor R, and the voltage generated across the resistor R is measured to calculate the dose rate (radiation intensity). It becomes a differential circuit that can be measured. On the other hand, switch S
When Wl is placed on the side of the capacitor C, the ionization current is accumulated in the capacitor C, and the voltage across the capacitor C is measured, forming an integrating circuit that can measure the radiation dose.

Furthermore, when switch SW2 is closed, current flows through the coil of relay RL, the relay contact is closed, and resistor R or capacitor C is short-circuited. In this state, the indicator is adjusted to ROJ (
By performing zero adjustment), it is possible to prevent bias from being applied due to the background. Furthermore, the integrator can be reset by short-circuiting the charge in the capacitor C.

In other words, the indication value based on the background in the claims also includes the case of a measurement value that has been measured once. The switch SW2 for erasing is provided on the measuring section 10 side and can be remotely operated from the hand side. Various structures can be used for the relay RL, but as shown in Fig. 4, enameled wires, etc. are multiplexed around a winding frame D placed around a narrow glass container G filled with nitrogen gas. It is also preferable to use a coil wound around the coil, since the contacts will not be oxidized by the inert gas such as nitrogen gas.

This invention is constructed as described above, and when in use, the position of the ionization chamber 20 on the detection side can be adjusted by expanding and contracting the wiring cover vibrator 30, and the ionization chamber 20 can be placed at a remote position relative to the measurement section 10. With this equipment, the measuring section 10 can be moved far away from the ionization chamber 20 even when measuring a high radiation dose, allowing safe use without exposure to radiation.

Further, the wiring cover vibrator 30 can be disconnected from the measuring section 10 or the ionization chamber 20 and connected with another electric wire to enable further remote measurement.

Further, in this invention, a circuit is provided near the ionization chamber 20 to erase the indicated value due to the background by shorting a part of the electric circuit, and the opening and closing of the erasing circuit is controlled by the relay RL.
Since it is provided so that it can be remotely controlled by a switching operation on the measuring part 10 side, the indicated value due to the background is erased at a point close to the ionization chamber 20, and the ammeter A
After adjusting the instruction to zero, the radiation dose rate or radiation dose on the ionization chamber 20 side can be measured without errors due to background.

Moreover, since the circuit for erasing the indicated value due to background can be opened and closed freely on the measurement unit 10 side, the ionization chamber 2
This eliminates all the inconvenience and difficulty of use caused by the 0 being installed at a remote location with respect to the measurement unit 10. Therefore, an ionization chamber type survey meter that can perform accurate measurements and is easy to use can be provided at a low price.

[Brief explanation of the drawing]

The figures illustrate embodiments of the present invention, and Fig. 1 is a perspective view, Fig. 2 is a partial sectional view, Fig. 3 is a circuit diagram, and Fig. 4 is a relay used in the circuit shown in the previous figure. FIG. DESCRIPTION OF SYMBOLS 10... Measuring part, 20... Ionization chamber, 30... Vibrator for wiring cover, 31... Tightening adjustment part, R... Resistor, C... Capacitor, RL... Relay, A...Ammeter.

Claims (1)

[Claims] 1. An ionization chamber is installed at a remote location to the measurement unit via a retractable wiring cover pipe, and the indicated value due to the background is measured by shortening a part of the electric circuit on the side near the ionization chamber. 1. An ionization chamber-type survey meter, characterized in that it is provided with a circuit for erasing data by means of radiation, and that opening and closing of the circuit for erasing can be remotely installed on the measurement unit side. 2. The ionization chamber type survey meter according to claim 1, wherein a circuit for erasing the background by shortening a part of the electric circuit near the ionization chamber can be opened and closed by a relay. 3. The ionization chamber-type survey meter according to claim 1, wherein the measuring section and the ionization chamber are wire-connected to each other by a curled cord in a wiring cover pipe such that the distance between them can be expanded and contracted. 4. The ionization chamber type survey meter according to claim 1, wherein the wiring cover pipe is attached so as to be separable from either the measuring section side or the ionization chamber side.