Heat-producing element monitoring method

FIELD: power industry.

SUBSTANCE: invention relates to control devices of heat-producing elements (fuel elements). The method includes determination of helium pressure under the shell (11) of the heat-producing element after its sealing at which the heat-producing element (1) is sustained at the measurement position, the local pulse heating of the heat-producing element is performed in the field of the compensation volume (8), the time dependence of temperature of shell sections in the place of heating (10) is registered and on the opposite side of the shell, it is used for estimation of helium pressure and the state of the heat-producing element.. Before local heating the heat-producing element is held until equalization of its temperature with ambient temperature, and after completion of monitoring the ambient temperature below 0°C is formed, before the local heating the heat-producing element is held until equalization of its temperature with new ambient temperature, then the cycle heating-measurement is repeated and the obtained time dependences of pressure at different temperatures are compared with calibration dependences for different helium pressure and different levels of the content of air in it.

EFFECT: providing additional possibility of non-destructive control of heat-producing elements.

1 dwg

 

The technical field to which the invention relates.

The invention relates to nuclear power engineering, in particular to control fuel elements (Fuel rods), and can be used, for example, during their manufacture.

In the process of manufacturing of Fuel elements on its shell, filled tablets of uranium dioxide and filled with helium under pressure, performing the role of a coolant, install the plug and seal flash-butt welding.

One measure of the reliability of a fuel Rod is stable helium pressure under the shell, which is ensured thanks to its tightness. The pressure drop of helium as a rule, characterizes the fuel rod is not as tight. Also critical is the presence of residual air in the Fuel element.

In this regard, the control pressure and the presence of air is very important to ensure the quality of Fuel rods.

The level of technology.

Common method of control is process control-pressure helium gas supplied to the fuel rod prior to final sealing. However, the possible leakage of helium from leaking of Fuel or crashing fill Fuel rod helium require control of helium in the finally assembled the Fuel rods. In addition, technological controls will not provide detection of leakage of the shell, "pollution" helium air, negatively in�yumega the operational characteristics of the Fuel element.

Known destructive inspection method, in which from a certain party selected fuel rod, and the pressure of helium in it is measured through a puncture in the shell. The disadvantage of sampling is that it is some unreliability and costs associated with the destruction of the finished Fuel element. In addition, like the previous method, it does not identify the "contamination" helium air (both ways, see "the Development, production and operation of fuel cell power reactors", book 2, ed. by F. G. Reshetnikov. - M.: Energoatomizdat, 1995, pp. 286-288).

The most used non-destructive ultrasonic and thermal control methods of the helium pressure under the fuel Rod cladding.

Known invention "Method of detecting leaking Fuel elements, an application for a patent of the Russian Federation No. 94037398 from 29.09.1994 G., publ. 27.10.1996 G. the Method involves ultrasound scanning of Fuel rods in the test volume, filled with water, registration of ultrasonic signals reflected from dry and wet borders of the inner surface of the cladding. Before scanning increase the pressure in the test volume to a value not exceeding the maximum pressure in the reactor. In addition, scanning is carried out before and after increasing the pressure and the difference of the detected signals to determine the leakage of the Fuel element.

With�allows persons when used to increase the efficiency of detection of defective Fuel rods, to reduce the duration of the verification process, but does not provide identification of the "pollution" of helium with air.

The closest is a set of attributes and the results obtained to the claimed invention is a method presented in the invention titled "Method of control and grading of fuel elements and device for its implementation". For invention issued by the patent RF №2261498, IPC G21C 17/06, G21C 17/02, published 27.09.2005 (application No. 2003132030/06 from 31.10.2003).

This method is chosen as the prototype of the claimed invention.

Prototype method includes controlling the pressure of helium supplied into the fuel element prior to final sealing, and the definition of thermal method of the helium pressure under concentric tube after sealing. For this fuel element at the position of measurement is fixed by the sensor, the signal of which it is clamped and held during the entire monitoring time. Next, perform a local pulsed heating of the fuel element in the area of compensation volume, record the temperature change sections of the sheath of the fuel element when it is rotated 180° at the beginning and end of time intervals after heating and rotation (record the time dependence of the temperature). The transfer of thermal energy�AI using helium inside the fuel element causes a temperature difference in areas of the fuel element sheath, proportional to the pressure of helium in the fuel element.

Prototype method provides improving the quality of manufacturing of Fuel elements due to the timely detection and isolation with the leaking Fuel rod cladding and the reliability of their operation in a nuclear reactor, but does not allow to identify the "contamination" helium air, adversely affecting the operational characteristics of the Fuel elements.

The aim of the invention is to provide a method of control, to detect the presence of air under the fuel cladding.

Disclosure of the invention.

The invention consists in that in the method of control of fuel elements, including the definition of the helium pressure under the fuel cladding after its sealing, which hold the fuel element in position measurement during the entire time monitoring, local pulsed heating of the fuel element in the area of compensation volume, record the time dependence of the temperature plots of the shell in the place of heating and on the opposite side of the shell during the whole time monitoring, it is judged on the condition of the heat-generating element according to the invention, the local heating of the fuel element can withstand up to align its temperature so�eratures his environment, and after the completion of control create the ambient temperature is below 0°C, before the local heating of the fuel element can withstand up to align its temperature with the new ambient temperature, repeat the heating cycle-measuring and comparing the obtained time dependence of pressure at different temperatures with calibration dependences for different helium pressures and different levels of air content in it.

The technical result, which provides the solution of this problem is as follows. Intrathecal cooling medium if it contains air, becomes depending on the amount present in varying degrees, less thermally conductive. The influence of different air effect when the temperature of the gaseous medium above and below 0°C. the Identification of reducing thermal conductivity through incorporation of temperature on opposite sides of the shell under different heating conditions and the identification of changes due to this pressure under the shell allows you to judge what is in intrathecal environment contains air.

In addition, the invention expands the Arsenal of tools for such appointment.

The presence of signs "before the local heating of the fuel element can withstand up to align its temperature with the temperature of its environment, and after completing�ia control create the ambient temperature is below 0°C, the local heating of the fuel element can withstand up to align its temperature with the new ambient temperature, repeat the heating cycle-measuring and comparing the obtained time dependence of pressure at different temperatures with calibration dependences for different helium pressures and different levels of air in it" suggests that the claimed invention meets the condition of patentability "novelty".

In the prior art is not identified technical solutions that have the features that distinguish the claimed invention from the prototype and allows you to retrieve the specified technical result. Thus, according to the applicant, the invention meets the condition of patentability "inventive step".

Brief description of the drawings.

Fig.1 shows a diagram of a device for controlling fuel element.

The implementation of the invention.

Installation for control of a fuel Rod 1 comprises a chamber 2 with the cradle 3, intended for placement of a fuel Rod 1. The installation also contains a heater (coil) with 4 generator 5 of the induction heating devices 6 and 7 for contactless temperature measurement, e.g. pyrometers.

Controlled compensation volume 8 of the Fuel element 1.

For warmed up in the process of assembling the fuel rod 1 size�through in camera 2 on the cradle 3. Stand the rod 1 within the time required for equalizing its temperature with the temperature of its environment 9 in the chamber 2, and carry out local pulsed heating of section 10 of the shell 11 of a fuel Rod 1 in the area of compensation volume 8 heater (inductor) from the generator 4 5 induction heating. Further, within a predetermined time (several tens seconds) simultaneously measured with the device 6, the temperature of the heating section 10 of the shell 11 and by means of the device 7 - section 12 opposite the heating section 10, i.e. from the opposite side, and register it.

Next, the ambient temperature is reduced to 9 negative, for example to minus 50°C. As in the first stage of control, the fuel rod 1 is maintained until the equalization of the temperature with the ambient temperature 9 and local pulsed heating of section 10 of the shell 11 of the Fuel element 3 in the area of compensation volume 8 heater (inductor) from the generator 4 5 induction negreau Forth within a predetermined time (several tens seconds) simultaneously measured with the device 6, the temperature of the heating section 10 of the shell 11 and by means of the device 7 - section 12 opposite the heating section 10, i.e. from the opposite side.

Compare the temporal dependences obtained at different temperatures, with the previously obtained calibration dependences� for different helium pressures inside the Fuel elements and different levels of air in it, determine the pressure of helium and air in it.

Thus, the presented data confirm that the implementation of the following set of conditions:

- method of control of fuel elements, which laid the basis for the claimed invention, allows the detection of the presence of air under the fuel Rod cladding;

- for the claimed invention in the form in which it was characterized in the claims, confirmed the possibility of its implementation using the technical solutions described in the application and become known before the invention was made.

Therefore, the claimed invention meets the condition of “industrial applicability”.

Method of control of fuel elements, including the definition of the helium pressure under the fuel cladding after its sealing, which hold the fuel element in position measurement during the entire time monitoring, local pulsed heating of the fuel element in the area of compensation volume, record the time dependence of the temperature plots of the shell in the place of heating and on the opposite side of the shell during the whole time monitoring, it is judged on the helium pressure and the condition of the fuel element, characterized in that the local heating of the fuel elements� stand to equalize its temperature with the ambient temperature, and after the completion of control create the ambient temperature is below 0°C, before the local heating of the fuel element can withstand up to align its temperature with the new ambient temperature, repeat the heating cycle-measuring and comparing the obtained time dependence of pressure at different temperatures with calibration dependences for different helium pressures and different levels of air content in it.



 

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