CN103162998A - Manufacturing method of uranium dioxide-gadolinium oxide pellet standard substance - Google Patents

Abstract

Belonging to a manufacturing method of a standard substance, the invention particularly relates to a manufacturing method of a uranium dioxide-gadolinium oxide pellet standard substance. The method comprises the steps of: (1) determining the content of gadolinium oxide; (2) conducting uncertainty evaluation; (3) synthesizing standard uncertainty; and (4) expanding uncertainty. The invention has the advantages that wavelength dispersive X ray fluorescence spectroscopy is employed in the present invention to establish the testing method for gadolinium oxide in gadolinium-containing pellets, and at the same time, the law of propagation of uncertainty is adopted to evaluate the uncertainty of a measurement result so as to ensure an accurate and reliable standard substance certified value. With the standard substance, an analysis method is evaluated and the analytical instrument is calibrated, the reliability of quality control in analytical measurement is improved, and the long-term use requirement in the future is satisfied.

Description

A kind of uranium dioxide-gadolinium oxide pellet standard substance manufacture method

Technical field

The invention belongs to a kind of standard substance manufacture method, be specifically related to a kind of uranium dioxide-gadolinium oxide pellet standard substance manufacturing.

Background technology

Domestic do not have a relevant standard substance.

Uranium dioxide-gadolinium oxide pellet (hereinafter referred to as containing the gadolinium pellet) standard substance is to be raw material by the pure grade powder of uranium dioxide of core and high-purity gadolinium oxide powder, adopt the existing manufacturing process that contains the gadolinium pellet be prepared into every quality approximately 1g contain gadolinium sintering pellet.

What the development that contains gadolinium pellet standard substance sample was different from the existing manufacturing process that contains the gadolinium uranium dioxide pellet is: the quality that contains the gadolinium uranium dioxide pellet of existing technique preparation is 7 grams approximately, and the quality that contains gadolinium uranium dioxide pellet standard substance sample is 1 gram approximately.Therefore, compacting is different with the parameter of sintering.

In addition, for standard substance, uniformity requirement is higher, and therefore, the gadolinium oxide powder before gadolinium oxide powder and powder of uranium dioxide mixing is through drying and processing.

Summary of the invention

The purpose of this invention is to provide a kind of uranium dioxide-gadolinium oxide pellet standard substance manufacture method, this standard substance can satisfy the demand of the quality assurance of high burnup assembly manufacturing.

The present invention is achieved in that a kind of uranium dioxide-gadolinium oxide pellet standard substance manufacture method, comprises the steps:

(1) measure gadolinium oxide content;

(2) uncertainty evaluation;

(3) combined standard uncertainty;

(4) expanded uncertainty.

Described step (1) is the uranyl nitrate solution that contains gadolinium of preparation 100ml, uses X-fluorescence spectrometer measurement gadolinium oxide massfraction w (Gd ₂O ₃).

Described step (2) is

1) measuring repeatability standard uncertainty u (f);

2) the uncertainty component u (G) of sample quality;

3) volume uncertainty component u (V);

4) the uncertainty u[ρ (Gd of the measurement result of gadolinium oxide content in sample solution ₂O ₃)].

Described step 1) comprise,

Sample to two kinds of gadolinium concentrations levels carries out respectively n replicate determination, represents experimental standard deviation with s, and n can choose as required for measuring number of times, and n is integer, and the standard uncertainty u (f) of measurement result is:

$u\left(f\right)=\frac{s}{\sqrt{n}}---\left(2\right)$

Described step 2) comprise,

The uncertainty of sample quality of weighing with scale mainly contains 2 components: readable u ₁(G), calibration u ₂(G),

1. readable uncertainty component u ₁(G)

The standard uncertainty u of readable part ₁(m) with in minimum calibration interval, estimate by the rectangular distribution,

$u_1\left(G\right)=\frac{a}{2\sqrt{3}}---\left(3\right)$

In formula, a is the scale division value of balance;

2. examine and determine or calibration uncertainty component u ₂(G)

The general rectangular distribution that adopts is converted into standard uncertainty with linear component

$u_2\left(G\right)=\frac{b}{\sqrt{3}}---\left(4\right)$

In formula, b is the linear value of balance.

Described step 3) comprise,

The uncertainty of volume comprises 2 components: calibration u ₁(V), temperature u ₂(V)

1. calculating uncertainty is triangle distribution,

$u_1\left(V\right)=\frac{c}{\sqrt{6}}---\left(5\right)$

In formula, the volumetric errors value when c is calibration,

2. temperature affects the uncertainty component:

When calculating standard uncertainty, the assumed temperature variation is rectangular distribution,

$u_2\left(V\right)=\frac{d}{\sqrt{3}}---\left(6\right)$

In formula, the volumetric errors of d during for the different temperatures in when calibration,

3. volume calculated uncertainty component u (V)

: $u\left(V\right)=\sqrt{u_1{\left(V\right)}^2+u_2{\left(V\right)}^2}---\left(7\right)$

Described step 4) comprise,

1. the uncertainty of working stamndard solution

$u^2{[\mathrm{\ρ}}_{\mathrm{ref}}\left({\mathrm{Gd}}_2{O}_3\right)]={\left[\frac{\∂\mathrm{\ρ}}{\∂m}\right]}^2{u}^2\left(m\right)+{\left[\frac{\∂\mathrm{\ρ}}{\∂P}\right]}^2{u}^2\left(P\right)+{\left[\frac{\∂\mathrm{\ρ}}{{\∂V}_2}\right]}^2{u}^2\left(V_2\right)={\left[\frac{p}{v_2}u\left(m\right)\right]}^2+{\left[\frac{m}{v_2}u\left(P\right)\right]}^2+{\left[\frac{\mathrm{mp}}{v_2^2}u\left(V_2\right)\right]}^2---\left(8\right)$

In formula: m (Gd ₂O ₃) be the sample weighting amount of gadolinium oxide, P is the purity of gadolinium oxide, V ₂Be the volumetric flask volume,

2. the uncertainty u of calibration curve ₁[ρ (Gd ₂O ₃)]

Obtained the uncertainty u of calibration curve by the standard deviation of linear regression ₁[ρ (Gd ₂O ₃)], use respectively u ₁, u ₂, u ₃, u ₄, u ₅The standard uncertainty of 5 points of expression typical curve.

$u_1\left[\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\right]=\frac{\sqrt{{u_1}^2\left(\mathrm{\ρ}\right)+{u_2}^2\left(\mathrm{\ρ}\right)+{u_3}^2\left(\mathrm{\ρ}\right)+{u_4}^2\left(\mathrm{\ρ}\right)+{u_5}^2\left(\mathrm{\ρ}\right)}}{5}---\left(9\right)$

The uncertainty component u[ρ (Gd of gadolinium oxide measurement result in sample solution ₂O ₃)] by the uncertainty u[ρ of working stamndard solution _ref(Gd ₂O ₃)] and the uncertainty u of calibration curve ₁[ρ (Gd ₂O ₃)] synthetic obtaining:

$u\left[\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\right]=\sqrt{u^2\left[{\mathrm{\ρ}}_{\mathrm{ref}}\left({\mathrm{Gd}}_2{O}_3\right)\right]+{u_1}^2\left[\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\right]}---\left(10\right)$

Described step (3) comprises, all standard uncertainties synthesized obtain combined standard uncertainty:

$u\left[w\left({\mathrm{Gd}}_2{O}_3\right)\right]=\sqrt{u^2\left(G\right)+u^2\left[p\left({\mathrm{Gd}}_2{O}_3\right)\right]+u^2\left(V\right)+u^2\left(f\right)}---\left(11\right)$

Described step (4) comprises,

When confidence level is 95%, coverage factor-k=2 o'clock,

$U=(w_{{\mathrm{Gd}}_2{O}_3}\%)=2u\left[w\left({\mathrm{Gd}}_2{O}_3\right)\right]---\left(12\right)$

Advantage of the present invention is, adopts in the present invention wavelength dispersion X ray fluorescence spectra technology, set up the method for testing that contains gadolinium oxide in the gadolinium pellet.Simultaneously, adopt uncertainty to propagate rule the uncertainty of measurement result is evaluated, guarantee this standard substance definite value accurately and reliably.This standard substance has been estimated analytical approach and has been calibrated analytical instrument, has improved the reliability of analysis to measure quality control, and can satisfy the long-term requirement of using from now on.Now be applied to the manufacturing of high burnup assembly, guaranteed product quality.Can guarantee high burnup subassembly product quality, improve its reliability of operation and security operation in heap.

Embodiment

The present invention is described in detail below in conjunction with specific embodiment:

A kind of uranium dioxide-gadolinium oxide pellet standard substance manufacture method comprises the steps:

(1) measure gadolinium oxide content;

The uranyl nitrate solution that contains gadolinium of preparation 100ml is used X-fluorescence spectrometer measurement gadolinium oxide massfraction w (Gd ₂O ₃).

(2) uncertainty evaluation

The massfraction that contains gadolinium oxide in the gadolinium uranium dioxide pellet can be expressed as:

$w\left({\mathrm{Gd}}_2{O}_3\right)=\frac{\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\×V_1}{(G-\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\×V_1)\×0.96200+\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\×V_1}\×100\%---\left(1\right)$

In formula: w (Gd ₂O ₃) for containing the mass percent of gadolinium oxide in the gadolinium uranium dioxide pellet, ρ (Gd ₂O ₃) be the mass concentration of gadolinium oxide in sample solution, the mg/mL of unit, G take the quality that contains the gadolinium triuranium octoxide, and the mg of unit, V are the liquor capacity of sample solution, Unit/mL, 0.96200 is U ₃O ₈Be converted into UO ₂Reduction coefficient.

The standard uncertainty component that affects X-fluorescence spectroscopy measurements gadolinium oxide content mainly contains: the standard uncertainty u (f) of measuring repeatability; Take the standard uncertainty u (G) that contains gadolinium triuranium octoxide quality; The standard uncertainty u (V) of the constant volume of sample solution; The standard uncertainty u[ρ (Gd2O3) of gadolinium concentrations measurement result in sample solution]: the standard uncertainty u[ρ ref (Gd2O3) that comprises working stamndard solution] and the standard uncertainty u1[ρ (Gd2O3) of calibration curve].

1) measuring repeatability standard uncertainty u (f)

Sample to two kinds of gadolinium concentrations levels carries out respectively n replicate determination, represents experimental standard deviation with s, and n can choose as required for measuring number of times, and n is integer, and the standard uncertainty u (f) of measurement result is:

$u\left(f\right)=\frac{s}{\sqrt{n}}---\left(2\right)$

2) the uncertainty component u (G) of sample quality

The uncertainty of sample quality of weighing with scale mainly contains 2 components: readable u ₁(G), calibrating or calibration u ₂(G).

1. readable uncertainty component u ₁(G)

The standard uncertainty u of readable part ₁(m) with in minimum calibration interval, estimate by the rectangular distribution.

$u_1\left(G\right)=\frac{a}{2\sqrt{3}}---\left(3\right)$

In formula, a is the scale division value of balance;

2. examine and determine or calibration uncertainty component u ₂(G)

The general rectangular distribution that adopts is converted into standard uncertainty with linear component

$u_2\left(G\right)=\frac{b}{\sqrt{3}}---\left(4\right)$

In formula, b is the linear value of balance,

3) volume uncertainty component u (V)

The uncertainty of volume comprises 2 components: calibration u ₁(V), temperature u ₂(V).

1. calculating uncertainty is triangle distribution,

$u_1\left(V\right)=\frac{c}{\sqrt{6}}---\left(5\right)$

In formula, the volumetric errors value when c is calibration,

2. temperature affects the uncertainty component:

When calculating standard uncertainty, the assumed temperature variation is rectangular distribution:

$u_2\left(V\right)=\frac{d}{\sqrt{3}}---\left(6\right)$

In formula, the volumetric errors of d during for the different temperatures in when calibration,

3. volume calculated uncertainty component u (V)

: $u\left(V\right)=\sqrt{u_1{\left(V\right)}^2+u_2{\left(V\right)}^2}---\left(7\right)$

4) the uncertainty u[ρ (Gd of the measurement result of gadolinium oxide content in sample solution ₂O ₃)]

1. the uncertainty of working stamndard solution

$u^2{[\mathrm{\ρ}}_{\mathrm{ref}}\left({\mathrm{Gd}}_2{O}_3\right)]={\left[\frac{\∂\mathrm{\ρ}}{\∂m}\right]}^2{u}^2\left(m\right)+{\left[\frac{\∂\mathrm{\ρ}}{\∂P}\right]}^2{u}^2\left(P\right)+{\left[\frac{\∂\mathrm{\ρ}}{{\∂V}_2}\right]}^2{u}^2\left(V_2\right)={\left[\frac{p}{v_2}u\left(m\right)\right]}^2+{\left[\frac{m}{v_2}u\left(P\right)\right]}^2+{\left[\frac{\mathrm{mp}}{v_2^2}u\left(V_2\right)\right]}^2---\left(8\right)$

In formula: m (Gd ₂O ₃) be the sample weighting amount of gadolinium oxide, P is the purity of gadolinium oxide, V ₂Be the volumetric flask volume.

2. the uncertainty u of calibration curve ₁[ρ (Gd ₂O ₃)]

Obtained the uncertainty u of calibration curve by the standard deviation of linear regression ₁[ρ (Gd ₂O ₃)].Use respectively u ₁, u ₂, u ₃, u ₄, u ₅The standard uncertainty of 5 points of expression typical curve.

$u_1\left[\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\right]=\frac{\sqrt{{u_1}^2\left(\mathrm{\ρ}\right)+{u_2}^2\left(\mathrm{\ρ}\right)+{u_3}^2\left(\mathrm{\ρ}\right)+{u_4}^2\left(\mathrm{\ρ}\right)+{u_5}^2\left(\mathrm{\ρ}\right)}}{5}---\left(9\right)$

The uncertainty component u[ρ (Gd of gadolinium oxide measurement result in sample solution ₂O ₃)] by the uncertainty u[ρ of working stamndard solution _ref(Gd ₂O ₃)] and the uncertainty u of calibration curve ₁[ρ (Gd ₂O ₃)] synthetic obtaining:

$u\left[\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\right]=\sqrt{u^2\left[{\mathrm{\ρ}}_{\mathrm{ref}}\left({\mathrm{Gd}}_2{O}_3\right)\right]+{u_1}^2\left[\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\right]}---\left(10\right)$

(3) combined standard uncertainty

All standard uncertainties are synthesized obtain combined standard uncertainty:

$u\left[w\left({\mathrm{Gd}}_2{O}_3\right)\right]=\sqrt{u^2\left(G\right)+u^2\left[p\left({\mathrm{Gd}}_2{O}_3\right)\right]+u^2\left(V\right)+u^2\left(f\right)}---\left(11\right)$

(4) expanded uncertainty

When confidence level is 95%, coverage factor-k=2 o'clock,

$U=(w_{{\mathrm{Gd}}_2{O}_3}\%)=2u\left[w\left({\mathrm{Gd}}_2{O}_3\right)\right]---\left(12\right)$

Embodiment 1

To contain the gadolinium uranium dioxide pellet is sintered in muffle furnace and contains gadolinium triuranium octoxide sample, take sample 1.0g, be accurate to 0.0001g, be placed in the 100mL quartz beaker, add the 4mL red fuming nitric acid (RFNA) along wall of cup, cover surface plate, in the electric hot plate heating, sample is dissolved fully, and steam to the Chinese red crystal, be cooled to room temperature, add the salpeter solution dissolving of 15mL0.5mol/L.Sample solution is changed in the 25mL volumetric flask, clean beaker 4 times with the salpeter solution of 0.5mol/L, each cleaning fluid is changed in volumetric flask, constant volume, shake up.Under selected instrument condition of work, working stamndard solution, sample solution are introduced the X-fluorescence spectrometer successively measure, then the massfraction of gadolinium oxide in calculation sample.

The massfraction that contains gadolinium oxide in the gadolinium uranium dioxide pellet can be expressed as:

$w\left({\mathrm{Gd}}_2{O}_3\right)=\frac{\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\×V_1}{(G-\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\×V_1)\×0.96200+\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\×V_1}\×100\%$

Uncertainty evaluation

Uncertainty comprises category-A uncertainty and category-B uncertainty.The uncertainty component that affects X-fluorescence spectroscopy measurements gadolinium oxide content mainly contains: the uncertainty u[ρ (Gd that takes gadolinium concentrations measurement result in the uncertainty u (G) that contains gadolinium triuranium octoxide quality, sample solution ₂O ₃)], comprise the uncertainty u[ρ of working stamndard solution _ref(Gd ₂O ₃)] and the uncertainty u of calibration curve ₁[ρ (Gd ₂O ₃)], the uncertainty u (V) of the constant volume of sample solution and the uncertainty u (f) (category-A uncertainty) of measuring repeatability

The evaluation of standard uncertainty component

1) measuring repeatability standard uncertainty u (f)

By the analytical procedure of analytical approach regulation, the sample of two kinds of gadolinium concentrations levels is carried out respectively 45 replicate determinations, the sample analysis result is w (Gd ₂O ₃)=3.881%, s=0.027%; W (Gd ₂O ₃)=8.000%, s=0.021%, with the experimental standard deviation of the mean value standard uncertainty as measurement result: $u(f4\%)=\frac{s}{\sqrt{n}}=\frac{0.027\%}{\sqrt{45}}=0.0041\%$

$u(f8\%)=\frac{s}{\sqrt{n}}=\frac{0.021\%}{\sqrt{45}}=0.0032\%$

2) the uncertainty component u (G) of sample quality

The uncertainty of sample quality of weighing with scale mainly contains 2 components: readable u ₁(G), calibrating or calibration u ₂(G).Repeatability uncertainty component is considered in total repeated uncertainty.

3) readable uncertainty component u ₁(G)

Because weighing balance used is ten thousand/balance, can be accurate to 0.1mg.The standard uncertainty u of readable part ₁(m) with in minimum calibration interval, estimate by the rectangular distribution.

$u_1\left(G\right)=\frac{0.1\mathrm{mg}}{2\sqrt{3}}=0.029\mathrm{mg}$

4) calibrating or calibration uncertainty component u ₂(G)

The balance calibration certificate indicates that its linearity is ± 0.15mg generally to adopt rectangular distribution that linear component is converted into standard uncertainty.

$u_2\left(G\right)=\frac{0.15\mathrm{mg}}{\sqrt{3}}=0.087\mathrm{mg}$

5) volume uncertainty component u (V)

The uncertainty of volume comprises 2 components: calibration u ₁(V), temperature u ₂(V).

The volume of the volumetric flask that is provided by manufacturer in the time of 20 ℃ is V=(25 ± 0.06) mL, and the calculating uncertainty is triangle distribution: $u_1\left(V\right)=\frac{0.06}{\sqrt{6}}=0.02\mathrm{mL}.$

Temperature affects the uncertainty component:

Generally calibration in the time of 20 ℃ of volumetric flask, laboratory temperature changes in ± 4 ℃ of scopes.The expansion coefficient of considering water is 2.1 * 10-4 ℃-1, the volume change that therefore produces be V=± (25 * 4 * 2.1 * 10-4)=0.021mL, when calculating standard uncertainty, to change be rectangular distribution to assumed temperature:

$u_2\left(V\right)=\frac{0.021}{\sqrt{3}}=0.012\mathrm{mL};$

$u\left(V_1\right)=\sqrt{{0.02}^2+{0.012}^2+{0.004}^2}=0.023\mathrm{mL}$

$u\left(V_2\right)=\sqrt{{0.04}^2+{0.024}^2+{0.006}^2}=0.047\mathrm{mL}$

: $u\left(V\right)=\sqrt{u_1{\left(V\right)}^2+u_2{\left(V\right)}^2}$

6) the uncertainty u[ρ (Gd of the measurement result of gadolinium oxide content in sample solution ₂O ₃)]

The uncertainty component u[ρ (Gd of gadolinium oxide measurement result in sample solution ₂O ₃)] by the uncertainty u[ρ of working stamndard solution _ref(Gd ₂O ₃)] and the uncertainty u of calibration curve ₁[ρ (Gd ₂O ₃)] synthetic obtaining:

$u\left[\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\right]=\sqrt{u^2\left[{\mathrm{\ρ}}_{\mathrm{ref}}\left({\mathrm{Gd}}_2{O}_3\right)\right]+{u_1}^2\left[\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\right]}$

$=\sqrt{{0.0020}^2+{0.0095}^2}$

$=0.010\mathrm{mg}/\mathrm{mL}$

Combined standard uncertainty

Uncertainty is synthesized obtains combined standard uncertainty:

$u\left(w\right)=\sqrt{{\left(\frac{1}{Q^2}\right)}^2{u}^2\left(Q\right)}=0.025\%$

Combined standard uncertainty is assessed as:

$u[w\left({\mathrm{Gd}}_2{O}_3\right)=\sqrt{{(0.025\%)}^2+{(0.0041\%)}^2}=0.026\%$

Expanded uncertainty

When confidence level is 95%, coverage factor-k=2 o'clock,

$U(w_{{\mathrm{Gd}}_2{O}_3}\%)=0.026\%\×2=0.052\%$

Claims (9)

1. uranium dioxide-gadolinium oxide pellet standard substance manufacture method, is characterized in that: comprise the steps:

(1) measure gadolinium oxide content;

(2) uncertainty evaluation;

(3) combined standard uncertainty;

(4) expanded uncertainty.

2. a kind of uranium dioxide as claimed in claim 1-gadolinium oxide pellet standard substance manufacture method, it is characterized in that: described step (1) is the uranyl nitrate solution that contains gadolinium of preparation 100ml, uses X-fluorescence spectrometer measurement gadolinium oxide massfraction w (Gd ₂O ₃).

3. a kind of uranium dioxide as claimed in claim 1-gadolinium oxide pellet standard substance manufacture method, it is characterized in that: described step (2) is

1) measuring repeatability standard uncertainty u (f);

2) the uncertainty component u (G) of sample quality;

3) volume uncertainty component u (V);

4) the uncertainty u[ρ (Gd of the measurement result of gadolinium oxide content in sample solution ₂O ₃)].

4. a kind of uranium dioxide as claimed in claim 3-gadolinium oxide pellet standard substance manufacture method is characterized in that: described step 1) comprises,

Sample to two kinds of gadolinium concentrations levels carries out respectively n replicate determination, represents experimental standard deviation with s, and n can choose as required for measuring number of times, and n is integer, and the standard uncertainty u (f) of measurement result is:

$u\left(f\right)=\frac{s}{\sqrt{n}}---\left(2\right)$

5. a kind of uranium dioxide as claimed in claim 3-gadolinium oxide pellet standard substance manufacture method is characterized in that: described step 2) comprises,

The uncertainty of sample quality of weighing with scale mainly contains 2 components: readable u ₁(G), calibration u ₂(G),

1. readable uncertainty component u ₁(G)

The standard uncertainty u of readable part ₁(m) with in minimum calibration interval, estimate by the rectangular distribution,

$u_1\left(G\right)=\frac{a}{2\sqrt{3}}---\left(3\right)$

In formula, a is the scale division value of balance;

2. examine and determine or calibration uncertainty component u ₂(G)

The general rectangular distribution that adopts is converted into standard uncertainty with linear component

$u_2\left(G\right)=\frac{b}{\sqrt{3}}---\left(4\right)$

In formula, b is the linear value of balance.

6. a kind of uranium dioxide as claimed in claim 3-gadolinium oxide pellet standard substance manufacture method is characterized in that: described step 3) comprises,

The uncertainty of volume comprises 2 components: calibration u ₁(V), temperature u ₂(V)

1. calculating uncertainty is triangle distribution,

$u_1\left(V\right)=\frac{c}{\sqrt{6}}---\left(5\right)$

In formula, the volumetric errors value when c is calibration.

2. temperature affects the uncertainty component:

When calculating standard uncertainty, the assumed temperature variation is rectangular distribution,

$u_2\left(V\right)=\frac{d}{\sqrt{3}}---\left(6\right)$

In formula, the volumetric errors of d during for the different temperatures in when calibration,

3. volume calculated uncertainty component u (V)

: $u\left(V\right)=\sqrt{u_1{\left(V\right)}^2+u_2{\left(V\right)}^2}---\left(7\right)$

7. a kind of uranium dioxide as claimed in claim 3-gadolinium oxide pellet standard substance manufacture method is characterized in that: described step 4) comprises,

1. the uncertainty of working stamndard solution

$u^2{[\mathrm{\ρ}}_{\mathrm{ref}}\left({\mathrm{Gd}}_2{O}_3\right)]={\left[\frac{\∂\mathrm{\ρ}}{\∂m}\right]}^2{u}^2\left(m\right)+{\left[\frac{\∂\mathrm{\ρ}}{\∂P}\right]}^2{u}^2\left(P\right)+{\left[\frac{\∂\mathrm{\ρ}}{{\∂V}_2}\right]}^2{u}^2\left(V_2\right)={\left[\frac{p}{v_2}u\left(m\right)\right]}^2+{\left[\frac{m}{v_2}u\left(P\right)\right]}^2+{\left[\frac{\mathrm{mp}}{v_2^2}u\left(V_2\right)\right]}^2---\left(8\right)$

In formula: m (Gd ₂O ₃) be the sample weighting amount of gadolinium oxide, P is the purity of gadolinium oxide, V ₂Be the volumetric flask volume.

2. the uncertainty u of calibration curve ₁[ρ (Gd ₂O ₃)]

Obtained the uncertainty u of calibration curve by the standard deviation of linear regression ₁[ρ (Gd ₂O ₃)], use respectively u ₁, u ₂, u ₃, u ₄, u ₅The standard uncertainty of 5 points of expression typical curve.

$u_1\left[\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\right]=\frac{\sqrt{{u_1}^2\left(\mathrm{\ρ}\right)+{u_2}^2\left(\mathrm{\ρ}\right)+{u_3}^2\left(\mathrm{\ρ}\right)+{u_4}^2\left(\mathrm{\ρ}\right)+{u_5}^2\left(\mathrm{\ρ}\right)}}{5}---\left(9\right)$

The uncertainty component u[ρ (Gd of gadolinium oxide measurement result in sample solution ₂O ₃)] by the uncertainty u[ρ of working stamndard solution _ref(Gd ₂O ₃)] and the uncertainty u of calibration curve ₁[ρ (Gd ₂O ₃)] synthetic obtaining:

$u\left[\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\right]=\sqrt{u^2\left[{\mathrm{\ρ}}_{\mathrm{ref}}\left({\mathrm{Gd}}_2{O}_3\right)\right]+{u_1}^2\left[\mathrm{\ρ}\left({\mathrm{Gd}}_2{O}_3\right)\right]}---\left(10\right).$

8. a kind of uranium dioxide as claimed in claim 1-gadolinium oxide pellet standard substance manufacture method is characterized in that: described step (3) comprises, all standard uncertainties synthesized obtain combined standard uncertainty:

$u\left[w\left({\mathrm{Gd}}_2{O}_3\right)\right]=\sqrt{u^2\left(G\right)+u^2\left[p\left({\mathrm{Gd}}_2{O}_3\right)\right]+u^2\left(V\right)+u^2\left(f\right)}---\left(11\right)$

9. a kind of uranium dioxide as claimed in claim 1-gadolinium oxide pellet standard substance manufacture method is characterized in that: described step (4) comprises,

When confidence level is 95%, coverage factor-k=2 o'clock,

$U=(w_{{\mathrm{Gd}}_2{O}_3}\%)=2u\left[w\left({\mathrm{Gd}}_2{O}_3\right)\right]---\left(12\right)$