CN111175803A

CN111175803A - Borehole core facility retired waste radioactive multi-parameter detection system and method

Info

Publication number: CN111175803A
Application number: CN202010029015.6A
Authority: CN
Inventors: 刘志毅; 刘军涛; 钱湘萍
Original assignee: Lanzhou University
Current assignee: Lanzhou University
Priority date: 2020-01-12
Filing date: 2020-01-12
Publication date: 2020-05-19
Anticipated expiration: 2040-01-12
Also published as: WO2021139020A1; CN111175803B

Abstract

The invention discloses a system and a method for detecting radioactive multi-parameter of retired waste of a drilled core facility, and relates to the field of source item investigation in the retirement process of the core facility. The system comprises a computer, a front-end machine, an array detection unit and a connecting unit, wherein the array detection unit comprises a position sensitive scintillator detector unit, an independent semiconductor detection array unit and a semiconductor detector and position sensitive detector mixed detection unit, the position sensitive scintillator detector unit, the independent semiconductor detection array unit and the semiconductor detector and position sensitive detector mixed detection unit respectively comprise a communication acquisition module, and the communication acquisition module is used for signal pre-amplification, forming, acquisition and communication with the front-end machine; the sensitive scintillator detector unit further comprises a position sensitive scintillator detector, the independent semiconductor detection array unit further comprises a semiconductor detector array, and the semiconductor detector and position sensitive detector mixed detection unit further comprises a position sensitive scintillator detector and a semiconductor detector.

Description

Borehole core facility retired waste radioactive multi-parameter detection system and method

Technical Field

The invention relates to the field of source item investigation in the decommissioning process of nuclear facilities, in particular to a radioactive multi-parameter detection system and method for decommissioned waste of a drilled nuclear facility.

Background

Nuclear facility decommissioning is a very important ring in efficient and safe utilization of nuclear science technology. The design, construction, operation and decommissioning of nuclear and radiation facilities are the rules of necessity.

Source item investigation and monitoring is one of the important parts throughout the entire nuclear facility decommissioning process. The method is not only an item foundation, but also a guarantee for realizing high-efficiency, safe and low-cost retirement, and is also an important basis for completion acceptance. The complexity of the source items in nuclear plant decommissioning is high and its cost needs to be enforced by making optimal, scientific schemes to achieve cost-effective goals. Large nuclear facilities such as nuclear power reactors mainly use bulk concrete as a shielding material, and are irradiated to different degrees in the operation process of the nuclear facilities, so that the large nuclear facilities have certain radioactivity. In the decommissioning process, bulk concrete as the main radioactive waste greatly affects the technical scheme and cost of decommissioning according to the aim of waste minimization. Therefore, the method has important practical significance for accurate source item investigation of bulk concrete. However, the currently used solution is to obtain samples of concrete at different depths by drilling, and send the samples to an off-site laboratory for measurement and evaluation, and has the disadvantages of high cost, long period, off-site measurement, labor intensity, and lack of real-time performance.

In addition, in the decommissioning process of the nuclear facilities used in the field, the residual radioactive contamination in the nuclear facilities needs to be measured first, so that the amount of radioactive waste to be managed is minimized. At present, radionuclide species and activity monitoring in waste such as concrete and the like in the decommissioned site of nuclear facilities mainly uses a high-resolution HPGe detector for radioactivity measurement and radionuclide species identification. There are major problems: the measured activity value is the comprehensive contribution value of the whole object to be measured (such as concrete). The continuous depth radioactivity monitoring inside large shielding materials such as concrete can not be carried out, which is contrary to the principle of minimizing the amount of radioactive wastes. Generally, the nuclide activity of the activated concrete is higher near the core (or other radioactive sources); the activated nuclide of concrete far away from the reactor core (or other radioactive sources) has low activity, and if only one comprehensive contribution limit is measured by using the prior art, the classification treatment of the activity level of the concrete waste is not facilitated, so that the amount of the radioactive waste to be treated is increased, and the decommissioning cost of the nuclear facility is obviously increased.

Disclosure of Invention

The invention aims to overcome the defects and provides a radioactive multi-parameter detection system and method for retired waste of an in-hole nuclear facility, which provide guidance for classification treatment of radioactive waste through continuous deep radioactive activity measurement in a large nuclear retired facility such as concrete.

The invention specifically adopts the following technical scheme:

a borehole core facility retired waste radioactive multi-parameter detection system comprises a computer, a front-end machine, an array detection unit and a connection unit, wherein the array detection unit comprises a position sensitive scintillator detector unit, an independent semiconductor detection array unit and a semiconductor detector and position sensitive detector mixed detection unit, the position sensitive scintillator detector unit, the independent semiconductor detection array unit and the semiconductor detector and position sensitive detector mixed detection unit respectively comprise a communication acquisition module, and the communication acquisition module is used for signal pre-amplification, forming, acquisition and communication with the front-end machine;

the sensitive scintillator detector unit also comprises a position sensitive scintillator detector which evaluates the radioactivity in the drill hole by measuring gamma ray count;

the independent semiconductor detection array unit also comprises a semiconductor detector array, and the semiconductor detector is used for carrying out nuclide screening by measuring a gamma ray energy spectrum and measuring nuclides which do not release gamma rays in the alpha and beta ray evaluation decay process;

the semiconductor detector and position sensitive detector mixed detection unit comprises a position sensitive scintillator detector and a semiconductor detector, wherein the position sensitive scintillator detector evaluates the radioactivity in a drill hole by measuring gamma ray count, and simultaneously measures alpha and beta rays to evaluate nuclides which do not release gamma rays in the decay process.

A borehole core facility retired waste radioactive multi-parameter detection method adopts the borehole core facility retired waste radioactive multi-parameter detection system, and specifically comprises the following steps:

a. drilling large concrete holes in a nuclear facility decommissioning scene by adopting a drilling tool;

b. inserting a borehole core retired waste radioactive multi-parameter detection system into a borehole obtained by drilling;

c. the instrument is graduated before measurement, radioactivity activity at a corresponding position of a radioactivity graduated sleeve moving in the axial direction of a detector array can be monitored in acquisition software, and the radioactivity graduated sleeve contains a plurality of standard radioactive sources lower than an exemption level;

d. connecting a power supply and a signal wire, and carrying out field measurement data acquisition;

e. according to the embedded data processing algorithm, performing on-site original data preprocessing and analysis;

d. an activity measurement and a nuclide identification species are given.

The invention has the following beneficial effects:

by the system and the method, the radioactivity measurement and the nuclide discrimination of continuous depth in the large concrete body are realized, and reference data are provided for classification processing of radioactive wastes and reduction of the amount of the radioactive wastes.

Drawings

FIG. 1 is a schematic view of a borehole core facility decommissioned waste radioactive multi-parameter detection system;

in fig. 1, 1 is a computer, 2 is a front-end machine, 3 is gamma rays, 4 is a connection unit, 5 is a detector array unit, 6 is a borehole, and 7 is a mass concrete body with retirement;

FIG. 2 is a schematic diagram of three types of detection units of a borehole core facility decommissioned waste radioactive multi-parameter detection system;

in fig. 2, 1 is a communication acquisition module, 2 is a position sensitive scintillator detector, 3 is an independent semiconductor detector array, and 4 is a mixed array of a semiconductor detector and a position sensitive scintillator detector;

FIG. 3 is a schematic scale view of a radioactive multi-parameter detection system for retired waste in a core facility of a borehole;

in fig. 3, 1 is a computer, 2 is a front-end machine, 3 is an instrument support, 4 is a radioactive source scale sleeve, 5 is a connecting unit, and 6 is a detector array subunit.

FIG. 4 is a schematic diagram of a borehole core facility retired waste radioactive multi-parameter detection method;

FIG. 5 is radioactivity monitoring measured alpha spectrum data of continuous depth inside bulk concrete.

Detailed Description

The following description of the embodiments of the present invention will be made with reference to the accompanying drawings:

a borehole core facility retired waste radioactive multi-parameter detection system comprises a computer, a front-end machine, an array detection unit (mainly comprising gamma, Alpha and Beta particle detection units) and a connection unit, wherein the array detection unit comprises a position sensitive scintillator detector unit, an independent semiconductor detection array unit and a semiconductor detector and position sensitive detector mixed detection unit, as shown in figure 2, the position sensitive scintillator detector unit, the independent semiconductor detection array unit and the semiconductor detector and position sensitive detector mixed detection unit respectively comprise a communication acquisition module, and the communication acquisition module is used for signal pre-amplification, shaping and acquisition and communication with the front-end machine;

the semiconductor detector and position sensitive detector mixed detection unit comprises a position sensitive scintillator detector and a semiconductor detector 4, wherein the position sensitive scintillator detector evaluates the radioactivity in a drill hole by measuring gamma ray counting, and simultaneously measures alpha rays and beta rays to evaluate nuclides which do not release gamma rays in the decay process.

a. a drilling tool is adopted to drill the large concrete in the nuclear facility decommissioning scene, the diameter of the drilled hole can be smaller than 5cm, and the drilling difficulty is reduced;

b. inserting a borehole core retired waste radioactive multi-parameter detection system into a borehole obtained by drilling, wherein a schematic diagram is shown in FIG. 1;

c. before measurement, the instrument is calibrated, the radioactivity activity of the corresponding position of a radioactivity calibration sleeve moving in the axial direction of a detector array can be monitored in acquisition software, and the radioactivity calibration sleeve contains a plurality of exempt standard radioactive sources such as Am-241(alpha source), Co-60 (gamma source) and the like, as shown in figure 3;

d. giving an activity measurement result and nuclide identification species, and the specific steps are shown in fig. 4;

fig. 5 is an alpha energy spectrum of internal different depth points obtained by measurement after drilling of a large block of concrete, nuclide identification of different internal depth points can be obtained by measuring characteristic energy analysis of alpha particles, and the species of the nuclides of different depth points obtained in the example are shown in table 1.

TABLE 1

As can be seen from the table 1, the method can well realize the radionuclide identification of the continuous depth in the nuclear decommissioned bulk concrete, and provides an important technical support for the classification treatment of the later radioactive concrete and the minimization of radioactive wastes.

It is to be understood that the above description is not intended to limit the present invention, and the present invention is not limited to the above examples, and those skilled in the art may make modifications, alterations, additions or substitutions within the spirit and scope of the present invention.

Claims

1. A borehole core facility retired waste radioactive multi-parameter detection system is characterized by comprising a computer, a front-end machine, an array detection unit and a connection unit, wherein the array detection unit comprises a position sensitive scintillator detector unit, an independent semiconductor detection array unit and a semiconductor detector and position sensitive detector mixed detection unit, the position sensitive scintillator detector unit, the independent semiconductor detection array unit and the semiconductor detector and position sensitive detector mixed detection unit respectively comprise a communication acquisition module, and the communication acquisition module is used for signal pre-amplification, forming, acquisition and communication with the front-end machine;

2. The borehole core facility retired waste radioactive multi-parameter detection method is characterized in that the borehole core facility retired waste radioactive multi-parameter detection system of claim 1 is adopted, and the method specifically comprises the following steps:

a. drilling the large concrete under the nuclear facility decommissioning scene by adopting a drilling tool;

b. inserting a borehole core retired waste radioactive multi-parameter detection system into the borehole obtained by drilling;

d. an activity measurement and a nuclide identification species are given.