CN106342216B - Energy-dispersive X-ray fluorescence (EDXRF) analytical system - Google Patents

Abstract

The invention belongs to the determination techniques of element under radioactive environment, be specifically related to the pre-diffraction energy dispersion of a kind of graphite crystal X-ray fluorescence analyzing system, be made up of X-ray tube activating system, graphite crystal optical diffraction, Si (Li) detector diversity system, computer spectrogram treatment system, wherein X-ray tube activating system is made up of X-ray tube and corresponding circuit and shield; Graphite crystal optical diffraction comprises optical filter, sample box and graphite diffractometer, and graphite diffractometer is in cylindric graphite body, to place shield, mark or scattering Internal standard correction methods measured intensity in this energy-dispersive X-ray fluorescence (EDXRF) analytical system adopts; X-ray tube activating system adopts the low dissipative X ray generator of 150～350W; Shield in graphite diffractometer is cylindric. This system focal spot is short to sample distance, compact conformation; Shield in graphite diffractometer is simple in structure, and detection limit is lower, and sampling amount is few.

Description

Energy-dispersive X-ray fluorescence (EDXRF) analytical system

Technical field

The invention belongs to the determination techniques of element under radioactive environment, be specifically related to a kind of graphite waferThe pre-diffraction energy dispersion of body X-ray fluorescence analyzing system.

Background technology

The power reactor spent fuel element average burn-up degree of depth exceedes 3300MWd/t, its radioactive intensityFor producing the decades of times of heap fuel element. Circulate the advanced person two who processes power reactor spent fuel elementIn aftertreatment technology flow process, the specific radioactivity of 1AW waste liquid is up to 10¹²～10¹³Bq/L，Therefore, the analysis of micro-actinium series and fission product in 1AW is had to very large technical difficulty.But the uranium neptunium molybdenum content in 1AW relates to the rate of recovery, the trend of neptunium and the decontamination of the sliver system of uraniumNumber, therefore must analyze. So, development can directly measure uranium in 1AW, neptunium,The instrumentation that zirconium, the isocyatic non-destructive of molybdenum are directly measured is very necessary.

Conventionally, the control analysis method of micro-actinides in 1AW, adopts sampling rear advancedThe Radiochemical Separation that row is strict, then carry out the survey of individual element by laser fluorescence or α counting method respectivelyAmount, this analytical model can not carry out analytical work in time, meanwhile, operating personnel's workAmount greatly. Last century late nineteen seventies, the people such as Russian the Institute of Radium Berdikov are to oftenRule energy-dispersive X-ray fluorescence (EDXRF) analyses (hereinafter to be referred as EDXRF) are transformed, creativenessIt is preselected that using mineral carbon crystal pre-diffraction in ground carries out energy, successfully solved solution example intrinsicHigh scattering background (accounting for the more than 99% of tale) and strong gamma active severe jamming thisOne technical barrier. The pre-diffraction EDXRF of graphite crystal technology why can be very high at scattering background,Under the very strong mal-condition of radioactivity, realize the non-of micro-actinium series and fission product in high activity liquid wasteDestroy directly and measure, this is the result of the various general principles of comprehensive utilization X ray spectroscopy,As selective exitation principle, monochromatization excitation principle, " band is logical " (band-pass) diffraction principle,Scattering principle of internal standard etc.

At document Journal of Radioanalytical Chemistry, Vol.58 (1980)In 123-131, the people such as Berdikov discloses the pre-diffraction EDXRF of a kind of graphite crystal system.This system is mainly made up of four parts: X-ray tube activating system, graphite crystal optical diffraction, Si(Li) detector diversity system, computer spectrogram treatment system. In this system, graphite waferShielding core in body diffractometer is tungsten metal, is olive shape, and two is taper, and centre is cylinderShape is outward graphite crystal at columniform tungsten metal. Comparatively speaking, the shielding core of this structureProcessing is got up more difficult. In x-ray fluorescence analysis, for the influence of fluctuations that effectively rectifies an instrumentAnd matrix effect, it is very necessary and effective that measured intensity is proofreaied and correct. BecauseThe K of Se_βHeat input is 12.50keV, relatively approaches the energy 13.613keV of uranium, neptunium, logicalCrossing diffractometer has again certain transmitance, so the people such as Berdikov take to add Se in light pathSimple substance is do the external standard fluctuation that rectifies an instrument. Because Se is added in elementary light path, can only rectify an instrumentFluctuation, can not correction of matrix effect. Meanwhile, Se quality is crisp, is difficult for fixing. In addition, passSystem sample box is made the sample cell of end window with Mylar film, be difficult to ensure the peace of highly radioactive solution operationEntirely.

Summary of the invention

The detection limit of the pre-diffraction EDXRF of graphite crystal system to U, depends on to a great extentThe length of light path, the height of transmitance, sampling amount number, and whether the structure of system compact.The object of the invention is the pre-diffraction EDXRF of the graphite crystal system disclosing people such as BerdikovOn the basis of system, provide a kind of structure compacter, detection limit is lower, the graphite that sampling amount is fewThe pre-diffraction energy dispersion of crystal X-ray fluorescence analyzing system.

Energy-dispersive X-ray fluorescence (EDXRF) analytical system of the present invention is by X-ray tube activating system, stone(or it is many to be called Si (Li) detector for smoky quartz body optical diffraction, si detector diversity systemRoad system), computer spectrogram treatment system composition, wherein X-ray tube activating system by X-ray tube,High pressure generator and shield composition; Graphite crystal optical diffraction comprise optical filter, sample box andGraphite diffractometer, graphite diffractometer is in cylindric graphite body, to place shield, this energy dispersionMark or scattering Internal standard correction methods measured intensity in X-ray fluorescence analyzing system adopts; X-ray tube excitesSystem adopts the low dissipative X ray generator of 150～350W; Shield in graphite diffractometer isCylindric.

To the correction of Matrix absorption effect, the present invention proofreaies and correct Matrix absorption effect by scattered rays internal standard methodShould. Due to the namely Matrix Composition Z of effective atomic number of sample^*To specific U analytical lineWith the impact of Ag scattered rays, can estimate by following formula:

I_U∝(Z^*)^-4

I_Age∝(Z^*)^-(3-2)

Two formulas are divided by,

$\frac{I_U}{I_{Agc}}\∝{\left(Z^{*}\right)}^{-(1-2)}$

As can be seen here, effective atomic number Z^*RightImpact and it is to I_UImpact littleMany.

In addition, technical scheme provided by the present invention, focal spot is short to sample distance, compact conformation.Shield in graphite diffractometer is simple in structure, easily processing.

Brief description of the drawings

Fig. 1 is that Ag target X-ray tube is measured fluid sample typical case spectrogram.

Fig. 2 is the structural representation of energy-dispersive X-ray fluorescence (EDXRF) analytical system.

Fig. 3 is graphite diffractometer structural representation.

Fig. 4 is the structural representation of sample box.

In figure, 1.X light pipe 2. optical filter 3. sample box 4. shield 5. graphite body 6.Si(Li) detector 7. preamplifier 8.IAE312 linear amplifier 9. cache interfaces 10.Microcomputer 11. stainless steel sleeve 12. graphite crystal 13. inner sleeve 14. outer tube 15,16. marksChi

Detailed description of the invention

Below in conjunction with accompanying drawing, the technical program is described further.

Embodiment 1

The pre-diffraction EDXRF of a kind of graphite crystal system, by X-ray tube activating system, graphite waferBody optical diffraction, Si (Li) detector diversity system, computer spectrogram treatment system composition.

Wherein X-ray tube activating system adopts 250W low-power high pressure generator, operating voltage,Electric current is respectively 50kV, 5mA. Adopt low-power generator tool to have the following advantages: circuit letterSingle, be convenient to maintenance, use safety, low to environmental requirement. The employing low-power matching with itAg target X-ray tube 1. In order to obtain large solid angle and intensity, make X-ray tube focal spot and sampleProduct distance is near as much as possible, and therefore the diameter of X-ray tube 1 is 34mm, and focal spot is Φ 2mm,The close together of sample and focal spot, approximately 17～20mm.

Graphite crystal optical diffraction mainly comprises optical filter 2, sample box 3, graphite diffractometer etc.Part. Optical filter 2 is Ag 200 μ m optical filters. Obtaining the highly sensitive while, consideringBe the high activity liquid waste in nuclear fuel aftertreatment technology to analytic target, must first guarantee operation peaceEntirely, therefore, fluid sample box 3 is box-like, formed by polypropylene material compacting, and base thickness 0.6mm,The sample box 3 of this structure is easy and simple to handle, can stop that end window breaks, radioactive sample solutionThe generation of the accidents such as leakage, guarantees the safety of operating personnel and instrument and equipment. Graphite diffractometer isAt the interior placement shield 5 of cylindric graphite body 4. The internal layer of graphite body 4 is graphite crystal 12,For the graphite cylinder of Φ 18 × 41, skin is stainless steel sleeve 11. In stainless steel sleeve 11 is connected toOn sleeve pipe 13, and can be in axial sliding along inner sleeve 13, inner sleeve 13 peripheral hardware outer tubes14, between inner sleeve 13 and outer tube 14, also can relatively be in axial sliding, and at inner sleeve13 with outer tube 14 on be respectively equipped with scale, can regulate easily the length of light path, reachAn object that diffractometer is multiplex. In order to improve the shield effectiveness of shield 5, shield 5 is straightFootpath is 6mm, with highdensity ferro-tungsten making, to shield energetic gamma rays.

Si (Li) detector 6 is KeVex company of U.S. product, 45 ° of inclination probes, crystalline substanceBody active area 30mm², the energy resolution (FWHM) to 5.9keV X ray is 165EV. Spectrometer plug-in unit is the product of China Atomic Energy Science Research Institute, comprises Model 304NIMPower supply, IAE 303 high voltage sourcies (0～3kV), IAE 312 linear amplifiers 8 etc., pass throughCache interface 9 is connected with microcomputer 10. Composition Si (Li)-MCA-PC analytical system.

When measurement, directly adopt Ag target line scattering Internal standard correction methods measured intensity.

The pre-diffraction EDXRF of this graphite crystal system light path is short, and transmitance is high, compact conformation,Sampling amount is few, can regulate light path length to be suitable for measuring different elements simultaneously.

For example, with the pre-diffraction EDXRF of graphite crystal provided by the invention system measurement one beThe uranium sample of row concentration known, result is as shown in table 1 below, and error is all in 10%. SampleProduct sampling amount is 0.3～0.5mL, far below the 4.6mL reporting in document.

Table 1 sample determination value and given value comparison

In addition, at following condition determination: optical path length is that 132mm (now sees through UL αRate maximum); Ag target X-ray tube excites, 50kV-5mA; 0.5mL sampling amount 200 μ mAgOptical filter, each element detection limit (MDL) is as shown in table 2, satisfies the demand.

The each element detection limit of table 2 (MDL)

Embodiment 2

As described in Example 1, difference is that X-ray tube activating system adopts 150W to this systemOr 350W low-power high pressure generator. The interior mark of correcting measuring intensity adopts Pb or Y in addition.

Claims (9)

1. an energy-dispersive X-ray fluorescence (EDXRF) analytical system, by X-ray tube activating system, stoneSmoky quartz body optical diffraction, si detector diversity system, computer spectrogram treatment system composition,Wherein X-ray tube activating system is made up of X-ray tube (1), high pressure generator and shield; StoneSmoky quartz body optical diffraction comprises optical filter (2), sample box (3) and graphite diffractometer, graphiteDiffractometer is in cylindric graphite body (5), to place shield (4), it is characterized in that: adoptInterior mark or scattering Internal standard correction methods measured intensity; X-ray tube activating system employing 150～350W's is lowPower high pressure generator; Shield in graphite diffractometer is cylindric.

2. energy-dispersive X-ray fluorescence (EDXRF) analytical system as claimed in claim 1, its featureBe: adopt Ag target line scattering Internal standard correction methods measured intensity.

3. energy-dispersive X-ray fluorescence (EDXRF) analytical system as claimed in claim 1, its featureBe: adopt Pb or Y to make Internal standard correction methods measured intensity.

4. the energy-dispersive X-ray fluorescence (EDXRF) analytical system as described in claim 1 or 2 or 3,It is characterized in that: X-ray tube activating system adopts 250W low-power high pressure generator.

5. energy-dispersive X-ray fluorescence (EDXRF) analytical system as claimed in claim 1 or 2, itsBe characterised in that: optical filter (2) is Ag 200 μ m optical filters.

6. the energy-dispersive X-ray fluorescence (EDXRF) analytical system as described in claim 1 or 2 or 3,It is characterized in that: sample box (3) becomes box-like shape by polypropylene material direct pressing.

7. the energy-dispersive X-ray fluorescence (EDXRF) analytical system as described in claim 1 or 2 or 3,It is characterized in that: the internal layer of described graphite body (5) is graphite crystal (12), outer for notRust steel bushing (11), it is upper that stainless steel sleeve (11) is connected to inner sleeve (13), and can be along interiorSleeve pipe (13) is in axial sliding; Inner sleeve (13) peripheral hardware outer tube (14), inner sleeve (13)And outer tube also can be in axial sliding between (14) relatively.

8. energy-dispersive X-ray fluorescence (EDXRF) analytical system as claimed in claim 7, its featureBe: on inner sleeve (13) and outer tube (14), be respectively equipped with scale (15,16).

9. energy-dispersive X-ray fluorescence (EDXRF) analytical system as claimed in claim 8, its featureBe: the material of shield (4) is ferro-tungsten.