SU1474461A1 - Method of measuring thickness - Google Patents

Abstract

The invention relates to non-destructive testing of products using ionizing radiation, and specifically to thickness gauges of objects made of lightweight materials. The aim of the invention is to improve the accuracy of measuring the thickness of the shells in hard-to-reach places by using a secondary radiation source as the main source. In a hollow object, the wall thickness of which is to be determined, an elastic balloon with a point-on element is inserted. The zone in which the element is turned on is irradiated with photons of the primary source. The flux of x-ray fluorescent radiation excited by these photons is measured at fixed distances from the outer surface of the test object. 1 il.

Description

one

The invention relates to non-destructive testing of products using ionizing radiation, namely to thickness gauges of objects made of lightweight materials.

The purpose of the invention is to improve the accuracy of measuring the thickness of the shells in hard-to-reach places by using a secondary radiation source as the main one.

The drawing shows the scheme for measuring the thickness of the proposed method.

The method is carried out as follows.

In the hollow object 1, whose wall thickness h needs to be determined, an elastic balloon 2 is introduced with a point connection of 3 elements. An overpressure is created in the cylinder. The zone in which the 3 elements are included is irradiated with photons of source 4 with energy E0, less or more energy E ", in order to ensure that the inclusion radiation and photons formed in the object of control due to Compton scattered radiation source. Energy Ea is determined from the ratio

E "E41--1b - () G (1)

4 1

4b 4b

OE

where mC is the electron's rest energy;

E „9 is the energy of x-ray fluorescence of point inclusion; scattering angle for recorded compton photons of the scattered radiation of the source.

Expression (1) for E "is obtained by converting a relation to determine the ES energy of a scattered photon

2+

Еп SE (1-cos0)

ЈA

The flux of X-ray fluorescent radiation excited by these photons is measured at a fixed distance of 20 L and K from the outer surface of the object 1. The obtained values of N and Na are compared and the result of the comparison is judged on the wall thickness of the object in the zone of inclusion 3. Graduated The curve is obtained experimentally using a balloon with a wall thickness that can be varied according to a certain law (for example, by increasing it with additional flexible plates 30 of known thickness), or theoretically. In the latter case, based on the fact that the photon flux through a single site as the

the focal distance decreases by quad; the control object presses the film

ratification law can be written

with a point inclusion of an element that is not present in the control object material in the control zone and in the film material, the primary photons from the ionizing radiation source with the energy Eh determined from the ratio I

N,

N.

Li + h

L, + h

-)

(3)

(four)

From here, get the equation of the calibration curve

, Li-

h lsh

lR - 1

When an object 1 is received by photons of a radionuclide source, for example, from americium-241, photons of Compton scattered radiation of the source and thuli x-ray florescence photons propagate in the 5-direction of registration. If we ensure the fulfillment of condition (1), namely, if we direct source 4 to object 1 so that the value 6 lies within 150-160 °, Compton scattered photons will have energy (48.9-49.2) keV. X-ray fluorescence photons of point inclusions, for example, from thuli possess

0

five

0 5 0

energy of 59.1; 57.5; 57.3; 50.7 and 49.8 keV.

The instrument spectrum of the detected radiation, which characterizes the distribution of the number N of detector pulses over their amplitudes And, contains a peak of x-ray fluorescence photons and a peak of Compton scattered photons. Measurement of ionizing radiation fluxes is carried out using known means containing a spectrometric detector, an amplitude pulse selection unit and a pulse number recorder for a given period of time.

Claims (1)

Invention Formula The method of measuring the thickness, which consists in directing the primary photons from the ionizing radiation source to the object to be monitored, measuring the flow of ionizing radiation at two different distances from the object to be monitored, and determining their thickness according to their magnitude and ratio in order to improve the accuracy of measuring the thickness of the shells in hard-to-reach places, before the direction of the primary photons from the ionizing radiation source to the inner side 0 with a point inclusion of an element which is absent in the material of the control object in the control zone and in the film material, the primary photons from the ionizing radiation source with energy Eh determined from ratio I five Еп Ек ШС (1-cos at) where TC is the electron's rest energy; E is the energy of X-ray fluorescent radiation of the point inclusion of the element; 8 is the scattering angle for detected photons of Compton scattered radiation from a source, and measured at two distances from the test object, the X-ray fluorescence radiation of the point-on element.