RU2716002C1 - Device for radiation and temperature monitoring of decommissioned uranium-graphite reactor - Google Patents

Abstract

FIELD: monitoring and verification technologies.

SUBSTANCE: device for radiation and temperature monitoring of a decommissioned uranium-graphite reactor comprises a sealed housing with a flange and a sealed passage, in which direct-charge neutron detectors and cable-type thermoelectric converters are provided, as well as detector attachment elements. Housing consists of links and is made in the form of elongated collecting pipe, one end of which is plugged and on external part of which there is a thread for installation of collimator and / or protective shield. On the other side the flat flange is screwed, on which eye-bolts are installed. On top, a cover is installed on the flange through the gasket, in which holes are provided for passage of wires from the thermal converter and the gamma-radiation detecting unit, which are installed in the guides located in the lower part of the elongated mounting pipe and connected to it by means of a welded joint.

EFFECT: invention makes it possible to increase efficiency of using known devices owing to possibility of arrangement of the device in inspection channels of various geometry and curvature.

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Description

The invention relates to monitoring and verification technology and can be used to measure radiation intensity and temperature inside a decommissioned uranium-graphite reactor and / or a radioactive waste storage, disposal or disposal site created in its place.

Known suspension of neutron detectors [RU 2186430, IPC G21C 17/108, G21C 17/00, publ. July 27, 2002], selected as an analogue. The specified device consists of neutron detectors located at different heights, and a communication line with a high-frequency connector at the end. Additionally, the suspension contains a snap ring. Between the measuring part of the suspension and the communication line with the high-frequency connector, a coupling and an additional high-frequency connector are introduced at the end. In this case, a high-frequency connector connects the output of the neutron detectors with a communication line.

The disadvantages of this device:

- limited use due to the ability to control only one selected parameter (neutron flux);

- low efficiency of the device, due to the need for additional operations for installation and connection of the device when placed in a sleeve;

- the need to use a set of sleeves placed at the measurement site and not subsequently removed. This reduces the functionality of the device.

A known sensor for controlling energy release in the fuel assembly of a nuclear reactor [RU 2190888, IPC G21C 17/00, G21C 17/10, publ. 10.10.2002], selected as an analogue. The specified device contains an extended detector of ionizing radiation and its communication line with the findings of the connector for connection to secondary equipment. At the same time, the sensor is supplemented with at least two local detectors of ionizing radiation located outside the core and mutually offset along its axis and communication lines of these detectors with other terminals of the connector.

The specified device has disadvantages:

- the need to use additional detectors located outside the active zone along the entire length of the sensor, which leads to the complexity of its design;

- limited use due to the ability to control only one selected parameter;

- the difficulty in synchronizing the operation of the detector located inside the sensor and detectors located outside the active zone.

Known assembly of detectors of the reactor monitoring system [RU 2140105, IPC G21C 17/00, G01T 3/00, H01J 49/00, publ. 20.10.1999], selected as a prototype. The specified device includes a sealed enclosure filled with an inert gas, with a flange and a sealed penetration, in which direct charge neutron detectors and cable-type thermoelectric converters are located. These direct charge neutron detectors are provided with cables. In this case, all cables are passed through the penetration. Detector mounting elements are additionally introduced into the tunneling, including a plate, an elongated tube, and clamps containing solder. The tube through which the detector cables pass is located between the penetration and the plate and connected to them.

The known device has the following disadvantages:

- the use of inert gases in a sealed enclosure leads to the accumulation of long-lived radionuclides, which are sources of gamma radiation and secondary neutrons. This reduces the accuracy of measuring the magnitude of the flux density of ionizing radiation;

- the use of additional detectors mounting elements complicates the assembly design, increases its mass and dimensions. This reduces its functionality and creates the complexity of monitoring the status of channel reactors (including shut down and / or decommissioned).

The technical result of the invention is to increase the efficiency of using known devices and expand their functionality.

To achieve the indicated technical result, an assembly of detectors of the on-reactor monitoring system can be used, which consists of a sealed housing with a flange and a tight penetration, in which direct-charge neutron detectors and cable-type thermoelectric converters equipped with cables are located, as well as from detector mountings including a plate , elongated tube and retainers containing solder. According to the invention, the device consists of an elongated typesetting pipe, consisting of links, one end of which is plugged, and on the other hand a flat flange is screwed in. Eye bolts are installed on the flat flange, and a cover is mounted on top of it through the gasket, which is fastened with bolts. The cover has openings for the passage of wires from the thermal converter and the gamma radiation detection unit. In this case, the gamma radiation detection unit and the thermal converter are installed in guides located in the lower part of the elongated stacked pipe and connected to it by means of a welded joint. A thread is provided on the outer part of the elongated type-fitting pipe for mounting a collimator and / or a protective shield made in the form of a sleeve.

The specified technical result is achieved due to the fact that for the radiation and temperature control of the decommissioned uranium-graphite reactor and transferred to the facility for the conservation, placement or disposal of radioactive waste, an elongated stacked pipe is used, which consists of units that are placed in specially installed inspection (control) channels. The length of the elongated stacked pipe is regulated by changing the number of links, and the curvature of the inspection (control) channels is compensated by replacing at least one link with a corrugated flexible pipe. Transportation and movement of an elongated typesetting pipe is carried out by attaching it to the eyebolts mounted on the flange, a standard lifting gear or a mobile crane. The temperature inside the decommissioned uranium-graphite reactor is measured using a thermal converter installed in the guides. This makes it possible to replace it during long-term operation due to radiation damage. Radiation monitoring is performed using a gamma radiation detection unit, which is also installed in the guides to replace it with damage to an identical unit or a neutron detection unit. Reduction of the radiation background is provided by a protective shield made in the form of a sleeve, which is fixed on the outer part of the elongated stacked pipe by means of a threaded connection. Measurement of radiation background in the selected area is provided by installing a collimator on the outer part of the elongated typesetting pipe.

In FIG. 1 shows the appearance of a radiation and temperature control device for a decommissioned uranium-graphite reactor.

In FIG. Figure 2 shows the appearance of a radiation and temperature control device for a decommissioned uranium-graphite reactor with a protective screen.

In FIG. Figure 3 shows the appearance of a radiation and temperature control device for a decommissioned uranium-graphite reactor with a collimator.

The proposed device for radiation and temperature control of decommissioned uranium-graphite reactor consists of an elongated stacked pipe 1, consisting of links connected by a threaded connection, one end of which is drowned by a massive tip 2, and the flat flange 3 is screwed in (Fig. 1) . In the flat flange 3, holes are provided for fastening, by means of bolted connections, of additional devices, for example, for a centering device in the inspection (control) channel. At the same time, eyebolts 4 are installed on the flat flange 3 for transporting and moving the elongated type-fitting pipe 1, and a cover with holes 5 is installed on top of the gasket for the passage of wires 6, which is fixed with bolts. The gamma radiation detecting unit 7 and the thermal converter 8 are connected to the converter and the signal analyzer (not shown in FIGS. 1, 2, 3) using wires 6.

The gamma radiation detecting unit 7 and the thermal converter 8 are installed in the guides 9 located in the lower part of the elongated type-fitting pipe 1 and connected with it by means of a welded joint, and also fixed in the grooves of the massive tip 2. In this case, the massive tip 2 is inserted into the grooves of the elongated type-fitting pipe 1.

On the outer part of the elongated type-fitting pipe 1, a thread is provided in the area of the gamma-ray detecting unit 7 and the thermal converter 8. In this region of the elongated type-fitting pipe 1, a protective shield 10 is mounted by means of a threaded connection, capable of attenuating the intensity of gamma radiation (Fig. 2) or a collimator 11 in which an inlet 12 is provided (Fig. 3).

The device operates as follows.

After selecting the area of radiation and temperature control of the decommissioned uranium-graphite reactor and transferred to the point of conservation, storage or disposal of radioactive waste, an elongated stacked pipe 1 is selected, consisting of units connected by means of a threaded connection. The length of the elongated stacked pipe 1 is adjusted by changing the number and length of the links, while it is possible to replace some links with corrugated flexible pipes. The device moves to the measurement site in the inspection (control) channels by attaching to the eyebolts 4 mounted on the flange 3, a regular lifting mechanism or a mobile crane. If it is necessary to measure the parameters in the selected area, a collimator 11 (Fig. 3) is used, which is connected to the lower part of the elongated stacked pipe 1 by means of a threaded connection.

The radiation and temperature control device for decommissioned uranium-graphite reactor is lowered to the required depth of the inspection (control) channel, where the radiation background (equivalent dose rate of gamma radiation) and temperature are measured using the gamma radiation detection unit 7 (for example, BDS- 07P) and thermal converter 8 (for example, ТСМУ-055), which are installed in the guides 9. It is possible to measure radiation and temperature fields by continuously raising and lowering the elongated th lamella pipe 1. Analog signals recorded by the detecting unit 7, the gamma radiation and thermal converter 8 via wires 6 are transmitted to the transducer (e.g., BTS-1tp) and the analyzer.

With an increased level of background gamma radiation, an elongated stacked pipe 1, comprising a gamma radiation detection unit 7 and a thermal converter 8, is removed from the inspection (control) channel. A protective shield 10 is installed on the outer part of the elongated type-fitting pipe 1, capable of attenuating the intensity of gamma radiation (Fig. 2), and the sequence of operations is repeated again.

In the event of failure of the gamma radiation detection unit 7 and / or the thermal converter 8, the tip 2 is removed from the slots of the elongated type-fitting pipe 1. The gamma radiation detection unit 7 and / or the thermal converter 8 are removed from the guides 9 and replaced with new ones. The tip 2 is installed back into the slots of the elongated type-fitting pipe 1. In this case, if necessary, the gamma radiation detection unit 7 can be replaced by a detection unit of another radiation (for example, neutron).

Thus, the proposed device design allows you to increase the efficiency of known devices through the use of a replaceable detection unit and a thermal converter, which allow you to simultaneously control several parameters, both in the selected area and in the whole area as a whole at different radiation intensities. The functionality is expanded through the use of a system of links of various sizes, including flexible links, which makes it possible to place the device in inspection (control) channels of various geometry and curvature.

Claims (3)

1. A radiation and temperature control device for a decommissioned uranium-graphite reactor, comprising a sealed housing with a flange and a hermetic penetration, in which direct-charge neutron detectors and cable-type thermoelectric converters equipped with cables are located, as well as detector fasteners, including an elongated plate tube and clamps containing solder, characterized in that the housing consists of links and is made in the form of an elongated stacked pipe, one end of which is plugged and n and on the external part of which there is a thread for installing the collimator and / or a protective screen, and on the other hand a flat flange is screwed on to which the eyebolts are installed, and on top of it through the gasket there is a cover that is fastened with bolts and in which holes are provided for the passage of wires from the thermal converter and the gamma radiation detection unit installed in the guides located in the lower part of the elongated typesetting pipe and connected with it by means of a welded joint. 2. The device according to p. 1, characterized in that the corrugated flexible pipe is used as intermediate links of the elongated typesetting pipe. 3. The device according to claim 1, characterized in that a collimator or a protective screen made in the form of a sleeve is installed on the outer part of the elongated typesetting pipe in the area of the gamma radiation detection unit and the thermal converter by means of a threaded connection.

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