RU1805359C - Method of determining the content of the mixture of spontaneously disintegrating nuclides - Google Patents

Abstract

Application: control of spent nuclear fuel reprocessing facilities. SUMMARY OF THE INVENTION a container system through which a medium containing a mixture of spontaneously decaying nuclides is passed, the intrinsic neutron radiation intensity of the medium and the intensity of the external gamma radiation transmitted through the layer of the medium are measured. Similar measurements are made for reference media. The obtained calibration coefficients and the results of intensity measurements are used to determine the desired mixture content in all tanks of the system. V) c

Description

The invention relates to the field of measuring the composition of a medium and can be used to determine the content of a mixture of spontaneously decaying nuclides (RNCs) in a medium, for example, in an aqueous solution, according to its own neutron radiation (SNR).

The aim of the invention is to increase the accuracy of determining the content of the RNC mixture in media passing through a container system when the nuclide composition of the mixture changes.

This goal is achieved by the fact that at the entrance to the system of containers, the gamma radiation intensity (GI) from an external gamma source is additionally measured after the GI passes through the layer of the medium under study and the layer of the reference medium sample, and the desired mixture content in the medium is calculated using calibration coefficients.

The invention is carried out as follows. Let it be necessary to control the content of the RNC mixture in the system from n series-connected containers through which the solution with RNS is transferred. A neutron sensor is mounted on each vessel to detect neutron radiation. At the entrance to the capacitance system, a neutron sensor and a gamma-absorber are installed, including a GI source for transmission of the solution with RNS and a sensor for recording GI after passing through the solution. Preliminarily, a reference solution with RNC of known nuclide composition and with a known content of RNC (Ca) mixture is fed to the entrance to the system of containers, it is run through all containers, the readings of the sensors at the inlet (NH and Nr) are measured, and the readings of the sensors at each tank of the system ( NHi) and the coefficients Kn, Kr, K) are determined by the formulas

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about eating

Cj

ate h

Kn Mn / (Se; oe), Kg Nr / Se: KI - NHi / (C3.q3)

for the known Ce, Pe, where de is the specific neutron yield from the solution of the NRC mixture. As the results of studies have shown, these coefficients are practically independent of the composition and content of the RNC mixture in solution.

In order to determine the content of the RNC mixture in each vessel when changing the nuclide composition of the RNS mixture in the solution entering the capacity system, it is necessary to measure the readings of the neutron sensor (NH) and gamma absorber (Mg) at the entrance to the system of capacities and the readings of neutron sensors on each tank (NHi). The content of the mixture in the i-th tank is calculated using the obtained calibration coefficients according to the dependence

N „1

NHI

,, Rr NH

  RH Nr

The control of the content of the RNC mixture in this way can be carried out if in the tank system the composition of the RNC mixture in the solution that enters the system is not changed further in the tank system, however, it can change at the system inlet. The content of the RNC mixture can also change in the tank system, for example, as a result of dilution, concentration, and precipitation of it.

If the nuclide composition of the NRC mixture changes in the container chain, in this case the container chain is divided into sections at which the composition of the NRC mixture is constant. At each entrance to such a section, it is necessary to measure the intensity of the SNR from the solution and gamma radiation from the gamma radiation source after the radiation has passed through the layer. solution with NRC.

Experimental verification of the invention under the conditions of radiochemical production during the reprocessing of spent nuclear fuel of reactors on a mixture of NRC (alpha-radiation

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scuttling and spontaneously fissioning nuclides) plutonium confirmed that it allows to increase the accuracy of determining the content of CHP from the SNR of the medium in the tank system when changing the nuclide composition of the CHP in the solution entering the system using existing neutron control systems by organizing additional control only at individual points in the process chain.

The wider the range in which the specific neutron yield from the NRC mixture at the entrance to the controlled system of containers can change, the greater the accuracy of determining the content of the NRC mixture in the tank system can be achieved, and the greater the positive effect of the invention. It allows you to automatically correct the readings of neutron control devices from counters installed on the tanks, according to the measurements of the gamma-absorber-meter and neutron control devices installed at the entrance to the tank system, and to carry out remote neutron monitoring of the content of the SRN mixture in the tank x

Formula A method for determining the content of a mixture of spontaneously decaying nuclides in a medium, which consists in measuring the intensity of intrinsic neutron radiation of the medium in a capacitance and establishing the content of a mixture of spontaneously decaying nuclides in a medium according to the results of measuring reference samples medium, characterized in that, in order to increase the accuracy of determining the content of the mixture in the media passing through the system of containers, when changing the nuclide composition of the mixture, at the entrance to the system of containers the intensity of gamma radiation from an external gamma source after passing gamma radiation through a layer of the test medium and a layer of a reference sample of the medium, and the desired mixture content in the medium is calculated using the obtained calibration coefficients.

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