JP2012225663A - Quantitative analysis method of plutonium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide Pu (plutonium) quantitative analysis method capable of quantitatively analyzing Pu by using radiation measurement such as α-ray spectrometry even in an analysis target sample solution containing much impurity elements such as Ca interrupting α-ray measurement.SOLUTION: The Pu quantitative analysis method for quantitatively analyzing Pu in an analysis target sample solution 10 includes: an iron hydroxide coprecipitation step S101 for generating iron hydroxide coprecipitate 12 containing a rare earth element by adding rare earth compound and iron compound to the analysis target sample solution 10; a rare earth fluoride coprecipitation step S104 for generating rare earth fluoride coprecipitate 15 by adding fluoride to an iron hydroxide coprecipitate solution 13 obtained by dissolving the iron hydroxide coprecipitate 12; and a radiation measurement step S107 for quantitatively analyzing Pu by radiation measurement of a measuring sample 16 prepared from the rare earth fluoride coprecipitate 15.

Description

  The present invention relates to a Pu (plutonium) quantitative analysis method, and more particularly to a Pu quantitative analysis method in which the amount of Pu in a sample collected from the environment is quantitatively analyzed by radiation measurement such as α-ray spectrometry.

Plutonium (Pu) is mainly produced from uranium 238 ( ²³⁸ U) contained in fuel for nuclear power generation.

  Pu is designated as one of the target nuclides for safety evaluation when radioactive waste is buried. For this reason, Pu concentration analysis is performed on environmental samples such as soil and water near the buried disposal site.

Conventionally, a coprecipitation method is known as one of Pu concentration analysis methods. In the coprecipitation method, for example, a rare earth element such as lanthanum (La) or neodymium (Nd) is added to an analysis target sample solution containing Pu prepared from an environmental sample, and further hydrogen fluoride (HF) is added. Quantitative analysis of Pu in rare earth fluoride coprecipitates after taking Pu in the sample solution to be analyzed into coprecipitates with rare earth fluorides (rare earth fluoride coprecipitates) and then performing radiation measurements such as alpha-ray spectrometry To do. Pu to be analyzed is, for example, ²³⁸ Pu, ²³⁹ Pu, ²⁴⁰ Pu, or the like.

In the coprecipitation method, it is preferable to evaluate the recovery rate of Pu as accurately as possible in order to improve analysis accuracy. Here, the recovery rate of Pu is the ratio of the amount of Pu in the rare earth fluoride coprecipitate to the amount of Pu in the sample solution to be analyzed. In order to evaluate the recovery rate of Pu as accurately as possible, ²⁴² Pu is usually mixed as a tracer in the sample solution to be analyzed for Pu concentration analysis.

^{Since 242} Pu is a Pu isotope, its chemical behavior is equivalent to that of nuclides such as ²³⁸ Pu, ²³⁹ Pu, ²⁴⁰ Pu and the like to be measured, and the amount contained in ordinary environmental samples is very small. For this reason, even if ²⁴² Pu is added as a tracer to the analysis target sample solution prepared from the environmental sample, there is little possibility of adversely affecting the measured amount of ²⁴² Pu.

Specifically, normal environmental samples for content of ^{242 Pu} is very small, also accurately calculate the recovery of ^{242 Pu} by adding ^{242 Pu} tracer analysis sample solution prepared from the environmental samples Cheap.

Further, the recovery rate of the ²⁴² Pu tracer itself can be regarded as substantially the same as the recovery rate of Pu isotopes such as ²³⁸ Pu, ²³⁹ Pu, and ²⁴⁰ Pu that have chemical behavior equivalent to that of ²⁴² Pu.
Therefore, ²⁴² Pu is suitable as a tracer for quantitative analysis of Pu.

Thus, when radiation measurement such as α-ray spectrometry is performed on a measurement sample prepared from a rare earth fluoride coprecipitate including a Pu tracer such as ²⁴² Pu, Pu such as ²³⁸ Pu, ²³⁹ Pu, and ²⁴⁰ Pu Quantitative analysis of isotopes becomes possible.

JP 2006-317290 A

  By the way, when the environmental sample is collected in a radioactive waste buried environment, the environmental sample may contain a large amount of calcium (Ca) eluted from the cement in the buried environment.

When the analysis target sample solution prepared from the environmental sample having a high Ca concentration is analyzed by the coprecipitation method, a large amount of CaF ₂ is generated when HF is added to the analysis target sample solution and is taken into the rare earth fluoride coprecipitate. , A rare earth fluoride coprecipitate containing a large amount of CaF ₂ is produced.

However, since CaF ₂ interferes with radiation measurement such as α-ray measurement, Pu is quantitatively analyzed using radiation measurement such as α-ray spectrometry in such rare earth fluoride coprecipitates containing a large amount of CaF _2. There was a problem that it was difficult.

Further, when ²⁴² Pu, which is a radionuclide, is used as a tracer, the place of analysis operation for Pu quantitative analysis is limited within the radiation control area. Therefore, when ²⁴² Pu is used as a tracer, there is a problem that the efficiency of Pu quantitative analysis is deteriorated.

  The present invention has been made in consideration of the above-described circumstances, and uses radiation measurement such as α-ray spectrometry even for a sample solution to be analyzed containing a large amount of impurity elements that interfere with α-ray measurement such as Ca. An object of the present invention is to provide a Pu quantitative analysis method capable of quantitatively analyzing Pu.

The present invention has been made in consideration of the above-described circumstances, and provides a Pu quantitative analysis method capable of quantitatively analyzing Pu without using a tracer made of Pu isotopes such as ²⁴² Pu. With the goal.

  In the present invention, iron (Fe) is added to a sample solution to be analyzed to produce an iron coprecipitate containing Pu, and radiation measurement of the iron coprecipitate containing Pu and Ca contained in the filtrate is performed. By separating the interfering impurities, it is possible to produce rare earth fluoride coprecipitates that are substantially free of contaminating elements such as Ca, and quantitative analysis of Pu by radiation measurement such as α-ray spectrometry. It has been completed by finding what is possible.

In the present invention, Sm is used as a rare earth element for producing a rare earth fluoride coprecipitate, and the natural radioisotope ¹⁴⁷ Sm in this Sm is used in place of a tracer made of Pu isotope such as ²⁴² Pu. For example, it was completed by finding that the recovery rate of ¹⁴⁷ Sm can be evaluated as the recovery rate of Pu.

  That is, the Pu quantitative analysis method of the present invention is for solving the above-described problems. In the Pu quantitative analysis method for quantitatively analyzing Pu in an analysis target sample solution, a rare earth compound and an iron compound are added to the analysis target solution. And adding a fluoride to the iron hydroxide coprecipitation step for producing the iron hydroxide coprecipitate containing the rare earth element, and the iron hydroxide coprecipitate solution in which the iron hydroxide coprecipitate is dissolved. A rare earth fluoride coprecipitation step for producing a rare earth fluoride coprecipitate, and a radiation measurement step for quantitatively analyzing Pu by performing radiation measurement on a measurement sample prepared from the rare earth fluoride coprecipitate. Features.

  According to the Pu quantitative analysis method of the present invention, it is possible to perform Pu quantitative analysis by radiation measurement such as α-ray spectrometry even for a sample solution to be analyzed that contains a large amount of impurity elements that interfere with radiation measurement such as Ca.

Further, according to the Pu quantitative analysis method of the present invention, since a rare earth element such as ¹⁴⁷ Sm is used as a tracer without using a radioactive substance such as ²⁴² Pu, Pu by radiation measurement such as α-ray spectrometry outside the radiation control area. Quantitative analysis becomes possible.

It is a figure which shows the operation procedure of the Pu quantitative analysis method of the 1st Embodiment of this invention. It is a figure which shows the operation procedure of the Pu quantitative analysis method of the 2nd Embodiment of this invention. FIG. 3 is a diagram showing an operation procedure of the Pu quantitative analysis method of Example 1. 2 is a graph showing an α-ray spectrum of Example 1. FIG. 6 is a diagram showing an operation procedure of the Pu quantitative analysis method of Example 2. It is a figure which shows the operation procedure of the Pu quantitative analysis method of the comparative example 1.

[Pu quantitative analysis method]
The Pu quantitative analysis method of the present invention is a Pu quantitative analysis method for quantitatively analyzing Pu in a sample solution to be analyzed. An iron hydroxide containing the rare earth element by adding a rare earth compound and an iron compound to the sample solution to be analyzed. An iron hydroxide coprecipitation step for forming a coprecipitate, and a rare earth fluoride for forming a rare earth fluoride coprecipitate by adding fluoride to the iron hydroxide coprecipitate solution in which the iron hydroxide coprecipitate is dissolved. A chemical coprecipitation step, and a radiation measurement step in which a measurement sample prepared from the rare earth fluoride coprecipitate is subjected to radiation measurement to quantitatively analyze Pu.
The Pu quantitative analysis method of the present invention will be described with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing an operation procedure 1 of the Pu quantitative analysis method according to the first embodiment of the present invention.

<Preparation of sample solution for analysis>
In the Pu quantitative analysis method of the first embodiment, first, an analysis target sample solution 10 is prepared. Examples of the analysis target sample solution 10 used in the Pu quantitative analysis method of the first embodiment include an aqueous solution prepared from an environmental sample. When the environmental sample is a liquid sample such as water or an aqueous solution, the environmental sample may be used as it is as the sample solution 10 to be analyzed.

  Examples of the environmental sample include fallout in the atmosphere, seawater, soil near the buried disposal site, and inland water near the buried disposal site.

  Note that the soil and inland water in the vicinity of the landfill site are likely to contain many alkaline earth metals such as calcium (Ca) eluted from the cement at the landfill site as impurities. Alkaline earth metals such as Ca may be a contaminating element that interferes with radiation measurement such as α-ray spectrometry.

For example, when the sample solution 10 containing a large amount of Ca is analyzed by the conventional coprecipitation method, a large amount of CaF ₂ that interferes with radiation measurement such as α-ray spectrometry is generated when HF35 is added to the sample solution to be analyzed. This CaF ₂ is taken into the rare earth fluoride coprecipitate. For this reason, it has been difficult for the conventional coprecipitation method to quantitatively analyze Pu by radiation measurement such as α-ray spectrometry.

  On the other hand, the Pu quantitative analysis method according to the first embodiment of the present invention includes a step of removing Ca from the analysis target sample solution 10, so even the analysis target sample solution 10 containing a large amount of Ca is co-precipitated. Thus, it is possible to quantitatively analyze Pu by radiation measurement such as α-ray spectrometry.

The sample solution 10 to be analyzed may contain, for example, Ca (OH) ₂ of 0.5 g / L or more, preferably 1.0 g / L or more, more preferably 1.5 g / L or more. More preferably, it may be a saturated aqueous solution of Ca (OH) ₂ .

<Iron hydroxide coprecipitation process>
The iron hydroxide coprecipitation step S101 is a step of adding the rare earth compound 41 and the iron compound 32 to the sample solution 10 to be analyzed to generate the iron hydroxide coprecipitate 12 containing the rare earth element.

The rare earth compound 41 added to the analysis target sample solution 10 in the iron hydroxide coprecipitation step S101 includes, for example, a rare earth element compound including a radioisotope, and more specifically, the natural radioisotope ¹⁴⁷ Sm is added. A compound of samarium (Sm) is included. If the rare earth element constituting the rare earth compound 41 contains a radioisotope, the radioisotope 42 of the rare earth element can be identified and quantified and Pu can be identified simultaneously and accurately in the radiation measurement step S107. preferable.

Examples of the samarium (Sm) compound include water-soluble samarium (Sm) compounds such as samarium nitrate (Sm (NO ₃ ) ₃ ) 41 and samarium.

The samarium (Sm) compound is similar to the behavior of ¹⁴⁷ Sm in the rare earth fluoride coprecipitation of Pu contained in Sm as a natural radioisotope, and ¹⁴⁷ Sm is a natural radioisotope. Because radiation measurement is possible, Sm can be used as a tracer for Pu, which is preferable. For example, by using ¹⁴⁷ Sm in samarium (Sm) as a Pu tracer, the recovery rate of ¹⁴⁷ Sm in coprecipitation can be regarded as the recovery rate of Pu in coprecipitation.

Examples of the iron compound 32 added to the analysis target sample solution 10 in the iron hydroxide coprecipitation step S101 include water-soluble iron (Fe) compounds such as iron nitrate (Fe (NO ₃ ) ₃ ) 32. When iron ions are generated in the sample solution 10 to be analyzed due to dissolution of the water-soluble iron (Fe) compound, iron hydroxide (Fe (OH) ₃ is added by adding a pH adjuster 33 that makes the sample solution 10 to be alkaline. ) Precipitate.

In addition, since rare earth elements such as samarium or ions thereof are present in the sample solution 10 to be analyzed, rare earth elements such as samarium are samarium hydroxide or the like during precipitation of iron hydroxide (Fe (OH) ₃ ). By coprecipitation as a rare earth hydroxide, an iron hydroxide coprecipitate 12 containing a rare earth element is generated. Moreover, when the sample solution 10 to be analyzed contains Pu, the iron hydroxide coprecipitate 12 containing the rare earth element further contains Pu.

  On the other hand, the impurity element 23 made of an alkaline earth metal such as calcium (Ca) in the sample solution to be analyzed does not substantially precipitate and is therefore hardly included in the iron hydroxide coprecipitate 12 containing the rare earth element.

  For this reason, by filtering the liquid 11 in which the iron hydroxide coprecipitate 12 containing rare earth elements is produced, the iron hydroxide coprecipitate 12 containing rare earth elements obtained as filter cake and the filtrate 22 are obtained. The aqueous solution containing the impurity element 23 such as calcium (Ca) can be separated. Further, when the sample solution 10 to be analyzed contains Pu, since Pu is contained in the iron hydroxide coprecipitate 12 containing the rare earth element, Pu and the rare earth element and the impurity element 23 such as calcium (Ca) are included. Can be separated.

As the pH adjusting agent 33 added to the sample solution 10 to be analyzed, for example, a pH adjusting agent composed of at least one of NaOH aqueous solution, NH ₃ aqueous solution and KOH aqueous solution is used.

  These pH adjusting agents are added to the analysis target sample solution 10 until the analysis target sample solution 10 is adjusted to a pH of usually 10 or higher, preferably pH 10.5 or higher, more preferably pH 11 or higher. Thereby, an iron hydroxide coprecipitate 12 is generated in the sample solution 10 to be analyzed.

  In this step, it is preferable that the sample solution 10 to be analyzed is previously acidified by adding the acid 31 before adding the rare earth compound 41 and the pH adjuster 33. If the sample solution 10 to be analyzed is acidified in advance, precipitation in the sample solution 10 to be analyzed does not easily occur before the pH adjuster 33 is added, so that the accuracy of quantitative analysis of Pu is increased. Examples of the acid 31 added in advance to the sample solution 10 to be analyzed before adding the rare earth compound 41 and the pH adjusting agent 33 include an acid composed of at least one of hydrochloric acid and nitric acid.

<Filtration and iron hydroxide coprecipitate recovery process>
The filtration / iron hydroxide coprecipitate recovery step S102 collects the iron hydroxide coprecipitate 12 by filtering the liquid 11 produced by the iron hydroxide coprecipitate 12 containing the rare earth element, and calcium (Ca This is a step of separating the filtrate 22 containing the contaminating element 23 such as) from the iron hydroxide coprecipitate 12 containing the rare earth element.

As the filtration method in this step, for example, a filtration method using a filter paper such as a membrane filter having a pore size of usually 0.3 μm or more, preferably 0.4 μm or more, more preferably 0.45 μm or more is used.
The filtration method is preferably suction filtration because the filtration rate is high.

  In the filtration method using filter paper, iron hydroxide coprecipitate 12 containing rare earth elements is obtained as filter cake, and an aqueous solution containing impurities 23 such as calcium (Ca) is obtained as filtrate 22.

<Iron hydroxide coprecipitate dissolution process>
The iron hydroxide coprecipitate dissolving step S103 is a step of preparing the iron hydroxide coprecipitate solution 13 by dissolving the recovered iron hydroxide coprecipitate 12 containing the rare earth element with the acid 34.
Examples of the acid 34 that dissolves the iron hydroxide coprecipitate 12 containing a rare earth element include an acid composed of at least one of hydrochloric acid and nitric acid.

  The iron hydroxide coprecipitate solution 13 containing rare earth elements contains at least rare earth element ions in addition to iron ions. Further, when the analysis target sample solution 10 contains Pu, the iron hydroxide coprecipitate solution 13 further contains Pu.

<Rare earth fluoride coprecipitation process>
In the rare earth fluoride coprecipitation step S104, the fluoride 35 is added to the iron hydroxide coprecipitate solution 13 in which the iron hydroxide coprecipitate 12 containing the rare earth element is dissolved to generate the rare earth fluoride coprecipitate 15. It is a process.

When the fluoride 35 is added to the iron hydroxide coprecipitate solution 13, the rare earth element ions and fluoride ions in the iron hydroxide coprecipitate solution 13 react to precipitate the rare earth fluoride in the solution 14. Produces. For example, if the rare earth element is samarium, a precipitate of samarium fluoride (SmF ₃ ) is generated.

  When the sample solution 10 to be analyzed contains Pu, the rare earth fluoride precipitate becomes a rare earth fluoride coprecipitate 15 containing Pu.

  When the rare earth fluoride coprecipitate 15 containing Pu is produced, the rare earth fluoride coprecipitate 15 with respect to the amount of rare earth elements in the iron hydroxide coprecipitate solution 13 before the rare earth fluoride coprecipitate 15 is produced. Rare earth fluoride coprecipitation with respect to the ratio of the amount of rare earth elements in the rare earth fluoride coprecipitate 15 after the formation of the rare earth fluoride and the amount of Pu in the iron hydroxide coprecipitate solution 13 before the formation of the rare earth fluoride coprecipitate 15 The ratio of the amount of Pu in the rare earth fluoride coprecipitate 15 after the production of the product 15 is similar.

In particular, when the rare earth element is samarium, the samarium after the formation of the samarium fluoride coprecipitate 15 with respect to the amount of ¹⁴⁷ Sm in the iron hydroxide coprecipitate solution 13 before the formation of the samarium fluoride coprecipitate 15 is obtained. Production of samarium fluoride coprecipitate 15 with respect to the ratio of the amount of ¹⁴⁷ Sm in fluoride coprecipitate 15 and the amount of Pu in iron hydroxide coprecipitate solution 13 before the formation of samarium fluoride coprecipitate 15 The ratio of the amount of Pu in the subsequent samarium fluoride coprecipitate 15 is almost the same.

Therefore, if the rare earth element is samarium, the recovery rate of the amount of ¹⁴⁷ Sm in the samarium fluoride coprecipitate 15 relative to the amount of ¹⁴⁷ Sm added to the sample solution 10 to be analyzed, that is, the recovery rate of ¹⁴⁷ Sm, and the analysis target It can be evaluated that the recovery rate of Pu in the samarium fluoride coprecipitate 15 with respect to the amount of Pu contained in the sample solution 10, that is, the recovery rate of Pu is almost the same.

As a result, the natural radioisotope ¹⁴⁷ Sm contained in samarium can be used as a tracer for Pu in the coprecipitation method.

The recovery rate of the amount of ¹⁴⁷ Sm in the samarium fluoride coprecipitate 15 is calculated by measuring the amount of ¹⁴⁷ Sm in the measurement sample 16 in the radiation measurement step S107.

<Filtration and rare earth fluoride coprecipitate recovery process>
The filtration / rare earth fluoride coprecipitate recovery step S105 is a step of recovering the rare earth fluoride coprecipitate 15 by filtering the liquid 14 produced by the rare earth fluoride coprecipitate 15.

As the filtration method in this step, for example, a filtration method using a filter paper such as a membrane filter having a pore diameter of 0.1 μm is used.
The filtration method is preferably suction filtration because the filtration rate is high.

<Drying process>
The drying step S106 is a step of drying the rare earth fluoride coprecipitate 15. When the rare earth fluoride coprecipitate 15 is dried, a measurement sample 16 used in the radiation measurement process is obtained.

  As a drying method of the rare earth fluoride coprecipitate 15, for example, a method of placing the rare earth fluoride coprecipitate 15 together with the filter paper in a high temperature dryer, or the rare earth fluoride coprecipitate 15 together with the filter paper at room temperature at room temperature. A method of leaving it, for example, air drying is mentioned.

<Radiation measurement process>
The radiation measurement step S107 is a step in which the measurement sample 16 produced from the rare earth fluoride coprecipitate 15 is subjected to radiation measurement to quantitatively analyze Pu.
Here, as a radiation measurement method, for example, α-ray spectrometry is used.

When radiation measurement such as α-ray spectrometry is performed on the measurement sample 16, the radionuclide in the measurement sample 16 can be identified and quantified. Therefore, a rare earth element such as ¹⁴⁷ Sm in the measurement sample 16 The radioisotope 42 can be identified and quantified, and Pu can be identified.

Next, the recovery rate of the radioisotope 42 of the rare earth element is calculated from the quantitative result of the radioisotope 42 of the rare earth element and the amount of the radioisotope 42 of the rare earth element in the sample solution 10 to be analyzed. For example, when the radioisotope 42 of the rare earth element is ¹⁴⁷ Sm ^{is 147} recovery of Sm is the ¹⁴⁷ Sm content in the measurement sample 16, by dividing by ¹⁴⁷ Sm amount added to the analysis sample solution 10 Is calculated by

  Further, the recovery rate of the radioisotope 42 of the rare earth element was evaluated to be the same value as the recovery rate of each Pu isotope, and the counter value of the radioisotope 42 of the rare earth element by radiation measurement such as α-ray spectrometry Quantitative analysis of each Pu isotope becomes possible by proportionally calculating the counter value of each Pu isotope.

For example, when the radioisotope 42 of the rare earth element is ¹⁴⁷ Sm, the recovery rate of ¹⁴⁷ Sm is evaluated to be the same value as the recovery rate of each Pu isotope, and then is measured by radiation measurement such as α-ray spectrometry. By proportionally calculating the counter value of ¹⁴⁷ Sm and the counter value of each Pu isotope, quantitative analysis of each Pu isotope becomes possible.

  Here, it is possible to evaluate the recovery rate of the radioisotope 42 of the rare earth element as the recovery rate of Pu amount, as described above, dissolution of the iron hydroxide coprecipitate before the formation of the rare earth fluoride coprecipitate 15. The ratio of the amount of the radioisotope 42 of the rare earth element in the rare earth fluoride coprecipitate 15 after the production of the rare earth fluoride coprecipitate 15 to the amount of the radioisotope 42 of the rare earth element in the liquid 13, The ratio of the amount of Pu in the rare earth fluoride coprecipitate 15 after the formation of the rare earth fluoride coprecipitate 15 to the amount of Pu in the iron hydroxide coprecipitate solution 13 before the formation of the precipitate 15 is similar. Because it does.

In particular, when the radioisotope 42 of the rare earth element is ¹⁴⁷ Sm, the samarium fluoride coprecipitate with respect to the amount of ¹⁴⁷ Sm42 in the iron hydroxide coprecipitate solution 13 before the samarium fluoride coprecipitate 15 is formed. Samarium fluoride relative to the ratio of the amount of ¹⁴⁷ Sm42 in the samarium fluoride coprecipitate 15 after the formation of 15 and the amount of Pu in the iron hydroxide coprecipitate solution 13 before the formation of the samarium fluoride coprecipitate 15 The ratio of the amount of Pu in the samarium fluoride coprecipitate 15 after the formation of the coprecipitate 15 is substantially the same.

  As described above, in the first embodiment of the present invention, the radioisotope of the rare earth element in the rare earth fluoride coprecipitate 15 with respect to the radioisotope 42 of the rare earth element in the rare earth element compound 41 added to the sample solution 10 to be analyzed. The recovery rate of the body 42, that is, the recovery rate of the radioisotope 42 of the rare earth element is evaluated as the recovery rate of Pu in the rare earth fluoride coprecipitate 15 relative to the amount of Pu in the sample solution 10 to be analyzed, that is, the recovery rate of Pu. can do.

<Effect of the first embodiment>
According to Pu quantitative analysis method of the first embodiment of the present invention, as a tracer of ^Pu, in place of the addition or ²⁴² Pu tracer ²⁴² Pu ^tracer, the use of radioactive isotopes 42 rare earth elements such as ¹⁴⁷ Sm Thus, the recovery rate of Pu and the quantitative analysis of Pu become possible.

That is, according to the Pu quantitative analysis method of the first embodiment of the present invention, the radioisotope 42 of a rare earth element such as ¹⁴⁷ Sm in the Sm compound 41 added to the sample solution 10 to be analyzed is recovered in the amount of Pu. By using it as a tracer for evaluating ²⁴² Pu recovery rate can be evaluated without using a ²⁴² Pu tracer.

(Second Embodiment)
FIG. 2 is a diagram showing an operation procedure 1A of the Pu quantitative analysis method according to the second embodiment of the present invention.
The operation procedure 1A of the Pu quantitative analysis method of the second embodiment is different from the operation procedure 1 of the Pu quantitative analysis method shown as the first embodiment in FIG. Instead of the iron oxide coprecipitation step S101, the iron hydroxide coprecipitation step S201, which is an operation of further adding the purified ²⁴² Pu tracer 43 to the sample solution 10 to be analyzed, and the radiation measurement of the operation procedure 1 of the Pu quantitative analysis method It differs from step S107 in that radiation measurement step S207, which is an operation for further measuring ²⁴² Pu44, is performed, and the other points are substantially the same.

  For this reason, the operation procedure 1A of the Pu quantitative analysis method shown as the second embodiment in FIG. 2 and the operation procedure 1 of the Pu quantitative analysis method shown as the first embodiment in FIG. The same reference numerals are given, and the description of the reference numerals and operations is omitted or simplified.

  The preparation of the sample solution to be analyzed in the operation procedure 1A of the Pu quantitative analysis method shown as the second embodiment in FIG. 2 is the same as the analysis target of the operation procedure 1 in the Pu quantitative analysis method shown in FIG. 1 as the first embodiment. Since it is the same as the preparation of the sample solution, the description is omitted.

<Iron hydroxide coprecipitation process>
In the iron hydroxide coprecipitation step S201, the rare earth compound 41 and the iron compound 32, and the purified ²⁴² Pu tracer 43 are added to the sample solution 10 to be analyzed, and the iron hydroxide coprecipitate including the rare earth element and the purified ²⁴² Pu tracer 43 is added. This is a step of generating 12A.

The iron hydroxide coprecipitation step S201 is the first implementation in FIG. 1 except that the refined ²⁴² Pu tracer 43 is added to produce the iron hydroxide coprecipitate 12A including the rare earth element and the refined ²⁴² Pu tracer 43. Since it is the same as the iron hydroxide coprecipitation step S101 of the operation procedure 1 of the Pu quantitative analysis method shown as the form, description and action are omitted.

As the purified ²⁴² Pu tracer 43 added to the sample solution 10 to be analyzed, a purified ²⁴² Pu tracer that is usually used in Pu quantitative analysis by the coprecipitation method is used.

Since the purified ²⁴² Pu tracer 43 added to the sample solution 10 to be analyzed coprecipitates with iron hydroxide (Fe (OH) ₃ ) and rare earth hydroxide, the resulting iron hydroxide coprecipitate 12A is hydroxylated. It becomes a coprecipitate containing refined ²⁴² Pu tracer 43 in addition to iron and rare earth elements.

In the iron hydroxide coprecipitation step S101 of the operation procedure 1 of the Pu quantitative analysis method shown as the first embodiment in FIG. 1, a liquid 11 in which an iron hydroxide coprecipitate 12 containing a rare earth element is generated is obtained. In the iron hydroxide coprecipitation step S201 shown in FIG. 2, a liquid 11A in which the iron hydroxide coprecipitate 12A including the rare earth element and the refined ²⁴² Pu tracer 43 is generated is obtained.

<Filtration and iron hydroxide coprecipitate recovery process>
The filtration / iron hydroxide coprecipitate recovery step S202 recovers the iron hydroxide coprecipitate 12A by filtering the liquid 11A produced by the iron hydroxide coprecipitate 12A including the rare earth element and the purified ²⁴² Pu tracer 43. At the same time, the filtrate 22 containing the impurity element 23 such as calcium (Ca) is separated from the iron hydroxide coprecipitate 12A containing the rare earth element and the purified ²⁴² Pu tracer 43.

In the filtration / iron hydroxide coprecipitate recovery step S202, instead of recovering the iron hydroxide coprecipitate 12 by filtering the liquid 11 produced by the iron hydroxide coprecipitate 12 containing the rare earth element, the rare earth 1 except that the iron hydroxide coprecipitate 12A is recovered by filtering the liquid 11A produced by the iron hydroxide coprecipitate 12A including the element and refined ²⁴² Pu tracer 43. Further, since it is the same as the filtration / iron hydroxide coprecipitate recovery step S102 in the operation procedure 1 of the Pu quantitative analysis method, description and action are omitted.

<Iron hydroxide coprecipitate dissolution process>
Iron coprecipitate dissolution step hydroxide S203 is recovered rare earth elements and purification ²⁴² Pu tracer 43 iron coprecipitate hydroxide dissolved iron hydroxide coprecipitate 12A with acid 34 containing the purified ²⁴² Pu tracer 43 comprising This is a step of preparing the dissolving liquid 13A.

In the iron hydroxide coprecipitate dissolution step S203, instead of preparing the iron hydroxide coprecipitate solution 13 by dissolving the iron hydroxide coprecipitate 12 containing the rare earth element with the acid 34, the rare earth element and the refinement are obtained. Except that the iron hydroxide coprecipitate 12A containing the ²⁴² Pu tracer 43 is dissolved with the acid 34 to produce the purified iron hydroxide coprecipitate solution 13A containing the purified ²⁴² Pu tracer 43, FIG. Since it is the same as the iron hydroxide coprecipitate dissolution step S103 of the operation procedure 1 of the Pu quantitative analysis method shown as the form, description and action are omitted.

<Rare earth fluoride coprecipitation process>
In the rare earth fluoride coprecipitation step S204, the fluoride 35 is added to the iron hydroxide coprecipitate solution 13A including the purified ²⁴² Pu tracer 43 in which the iron hydroxide coprecipitate 12A including the rare earth element and the purified ²⁴² Pu tracer 43 is dissolved. Is added to produce the rare earth fluoride coprecipitate 15A including the purified ²⁴² Pu tracer 43.

The rare earth fluoride coprecipitation step S204 replaces the iron hydroxide coprecipitate solution 13 in which the iron hydroxide coprecipitate 12 containing the rare earth element is dissolved, instead of the iron hydroxide coprecipitate containing the rare earth element and the purified ²⁴² Pu tracer 43. that it uses iron hydroxide coprecipitate solution 13A containing purified ²⁴² Pu tracer 43 containing dissolved precipitate 12A, and instead of the rare earth fluoride coprecipitate 15, rare earth fluoride coprecipitation containing purified ²⁴² Pu tracer 43 Since it is the same as the rare earth fluoride coprecipitation step S104 of the operation procedure 1 of the Pu quantitative analysis method shown as the first embodiment in FIG. 1 except that the product 15A is generated, description and action are omitted.

<Filtration and rare earth fluoride coprecipitate recovery process>
In the filtration / rare earth fluoride coprecipitate recovery step S205, the liquid 14A produced by the rare earth fluoride coprecipitate 15A including the purified ²⁴² Pu tracer 43 is filtered to thereby filter the rare earth fluoride coprecipitate including the purified ²⁴² Pu tracer 43. This is a step of collecting the object 15A.

The filtration / rare earth fluoride coprecipitate recovery step S205 replaces the liquid 14 containing the rare earth fluoride coprecipitate 15 with the liquid produced by the rare earth fluoride coprecipitate 15A containing the purified ²⁴² Pu tracer 43. The first implementation is shown in FIG. 1 except that 14A is filtered and the rare earth fluoride coprecipitate 15A including the purified ²⁴² Pu tracer 43 is recovered instead of collecting the rare earth fluoride coprecipitate 15. Since it is the same as the filtration / rare earth fluoride coprecipitate recovery step S105 of the operation procedure 1 of the Pu quantitative analysis method shown as the form, the description and the action are omitted.

<Drying process>
The drying step S206 is a step of drying the rare earth fluoride coprecipitate 15A including the purified ²⁴² Pu tracer 43.
When the rare earth fluoride coprecipitate 15A including the purified ²⁴² Pu tracer 43 is dried, a measurement sample 16A including ²⁴² Pu44 used in the radiation measurement step is obtained.

In the drying step S206, instead of drying the rare earth fluoride coprecipitate 15 to obtain the measurement sample 16, the rare earth fluoride coprecipitate 15A including the purified ²⁴² Pu tracer 43 is dried and measurement including ²⁴² Pu44 is performed. Since it is the same as the drying step S106 in the operation procedure 1 of the Pu quantitative analysis method shown as the first embodiment in FIG.

<Radiation measurement process>
The radiation measurement step S207 is a step in which the measurement sample 16A including ²⁴² Pu44 produced from the rare earth fluoride coprecipitate 15A including the purified ²⁴² Pu tracer 43 is subjected to radiation measurement and Pu is quantitatively analyzed.

The radiation measurement step S207 includes ²⁴² Pu44 produced from the rare earth fluoride coprecipitate 15A including the purified ²⁴² Pu tracer 43 instead of performing radiation measurement on the measurement sample 16 produced from the rare earth fluoride coprecipitate 15. Since the measurement sample 16A is the same as the radiation measurement step S107 in the operation procedure 1 of the Pu quantitative analysis method shown as the first embodiment in FIG. 1 except that the measurement sample 16A is subjected to radiation measurement, description and action thereof are omitted.

^When radiation measurement such as α-ray spectrometry is performed on the measurement sample 16A containing ²⁴² Pu44, the radionuclide in the measurement sample 16A can be identified and quantified, so ¹⁴⁷ Sm in the measurement sample 16A. Identification and quantification of the radioisotopes 42 and ²⁴² Pu44 of rare earth elements such as

That is, the recovery rate of ²⁴² Pu44 is calculated from the quantification result of ²⁴² Pu44 in the measurement sample 16A and the amount of ²⁴² Pu44 contained in the purified ²⁴² Pu tracer 43 in the analysis target sample solution 10A. For ^example, the recovery rate of 242 Pu44 is a ²⁴² Pu44 amount in the measurement sample 16A, is calculated by dividing the ²⁴² Pu44 amount contained in the purified ²⁴² Pu tracer 43 which is added to the analysis sample solution 10.

In addition, after evaluating the recovery rate of ²⁴² Pu44 to be the same value as the recovery rate of each Pu isotope, the counter value of ²⁴² Pu44 by the radiation measurement such as α-ray spectrometry, the counter value of each Pu isotope, Can be quantitatively analyzed for each Pu isotope.

On the other hand, the recovery rate of the radioisotope 42 of the rare earth element is calculated from the quantitative result of the radioisotope 42 of the rare earth element in the measurement sample 16A and the amount of the radioisotope 42 of the rare earth element in the sample solution 10 to be analyzed. . For example, when the radioisotope 42 of the rare earth element is ¹⁴⁷ Sm ^{is 147} recovery of Sm is the ¹⁴⁷ Sm content in the measurement sample 16A, dividing by ¹⁴⁷ Sm amount added to the analysis sample solution 10 Is calculated by

And recovery of radioactive isotopes 42 rare earth element ¹⁴⁷ Sm or the like measured in this ^way, compared with the recovery rate of 242 ^Pu44, the recovery of radioactive isotopes 42 rare earth elements such as ^{147 Sm,} 242 Pu44 Multiply or add an appropriate correction coefficient that eliminates the deviation from the recovery rate.

When the recovery rate of the rare earth element radioisotope 42 corrected by the correction coefficient is calculated in this way, the corrected recovery rate of the rare earth element radioisotope 42 can be evaluated as the recovery rate of Pu. That is, thereafter, by adding the radioisotope 42 of rare earth elements such as ¹⁴⁷ Sm without adding the purified ²⁴² Pu tracer 43 to the sample solution 10 to be analyzed, the recovery rate of Pu and the quantitative analysis of Pu are possible. become.

<Effects of Second Embodiment>
According to the Pu quantitative analysis method of the second embodiment of the present invention, in addition to the same effects as the Pu quantitative analysis method of the first embodiment of the present invention, the recovery rate of the radioisotope 42 of the rare earth element, and Pu Since the deviation from the recovery rate is corrected, more accurate quantitative analysis of Pu becomes possible.

  Examples are shown below, but the present invention is not construed as being limited thereto.

Example 1
[Preparation of α-ray measurement sample]
FIG. 3 is a diagram illustrating an operation procedure 1B of the Pu quantitative analysis method according to the first embodiment.
The operation procedure 1B of the Pu quantitative analysis method shown in FIG. 3 differs from the operation procedure 1 of the Pu quantitative analysis method shown as the first embodiment in FIG. The difference is that 10A of saturated Ca (OH) ₂ aqueous solution is used, and the other points are the same.

  For this reason, in the operation procedure 1B of the Pu quantitative analysis method of Example 1 shown in FIG. 3 and the operation procedure 1 of the Pu quantitative analysis method shown as the first embodiment in FIG. The description of the reference numerals and actions is omitted or simplified.

Note that the saturated Ca (OH) ₂ aqueous solution 10A at 25 ° C. was prepared by imitating the sample solution 10 to be analyzed that does not contain Pu in order to observe the behavior of ¹⁴⁷ Sm. This saturated Ca (OH) ₂ aqueous solution 10A at 25 ° C. is used in the following Example 2 and Comparative Example 1 for the same reason as in Example 1.

100 ml of saturated Ca (OH) ₂ aqueous solution 10A at 25 ° C. was prepared, and 1 ml of 35% HCl was added to this saturated Ca (OH) ₂ aqueous solution 10A to make the solution acidic, and 0.2 mg in terms of Sm. Sm (NO ₃ ) ₃ was added.

Next, 10 ml of an Fe (NO ₃ ) ₃ aqueous solution with an Fe concentration of 1000 ppm was added to this solution, and then a 1 mol / L NaOH aqueous solution was gradually added to make the solution alkaline with pH> 10. (OH) ₃ precipitate (iron coprecipitate) was formed.

The resulting precipitate was filtered with a filter having a pore size of 0.45 μm, and the filter cake was recovered. This filter cake was dissolved in 15 ml of a 6 mol / L aqueous HCl solution (hydrochloric acid), and then 2.5 ml of 46% HF (hydrofluoric acid) was added dropwise to the solution. As a result, SmF ₃ precipitation (both rare earth fluorides) Sediment) was formed.
The resulting precipitate was filtered through a filter having a pore size of 0.1 μm, and the filter cake was collected and dried.

[Α-ray measurement]
The dried filter cake was subjected to α ray measurement (80000 sec) by α ray spectrometry.
The obtained α-ray spectrum is shown in FIG. As shown in FIG. 4, since a clear peak of ¹⁴⁷ Sm can be confirmed, it was confirmed that the influence of Ca can be eliminated in the α-ray spectrometry according to this method.

(Example 2)
[Preparation of α-ray measurement sample]
FIG. 5 is a diagram illustrating an operation procedure 1C of the Pu quantitative analysis method according to the second embodiment.
The operation procedure 1C of the Pu quantitative analysis method shown in FIG. 5 is compared with the operation procedure 1A of the Pu quantitative analysis method shown as the second embodiment in FIG. OH) ₂ aqueous solution 10A is used, and the other points are the same.

  Therefore, in the operation procedure 1C of the Pu quantitative analysis method of Example 2 shown in FIG. 5 and the operation procedure 1A of the Pu quantitative analysis method shown as the second embodiment in FIG. The description of the reference numerals and actions is omitted or simplified.

100 ml of a saturated Ca (OH) ₂ aqueous solution 10A at 25 ° C. was prepared, and 1 ml of 35% HCl was added to the saturated Ca (OH) ₂ aqueous solution 10A to make the solution acidic, and further 0.08 Bq of ²⁴² Pu, 0.2 mg of Sm (NO ₃ ) _{3 in} terms of Sm was added.

Next, 10 ml of an Fe (NO ₃ ) ₃ aqueous solution with an Fe concentration of 1000 ppm was added to this solution, and then a 1 mol / L NaOH aqueous solution was gradually added to make the solution alkaline with pH> 10. (OH) ₃ precipitate (iron coprecipitate) was formed.

The resulting precipitate was filtered with a filter having a pore size of 0.45 μm, and the filter cake was recovered. This filter cake was dissolved in 15 ml of a 6 mol / L aqueous HCl solution (hydrochloric acid), and then 2.5 ml of 46% HF (hydrofluoric acid) was added dropwise to the solution. As a result, SmF ₃ precipitation (both rare earth fluorides) Sediment) was formed.
The resulting precipitate was filtered through a filter having a pore size of 0.1 μm, and the filter cake was collected and dried.

[Α-ray measurement]
The dried filter cake was subjected to α ray measurement (75000 sec) by α ray spectrometry.
In the obtained α-ray spectrum, clear peaks of ²⁴² Pu and ¹⁴⁷ Sm were confirmed.

Next, ²⁴² Pu and ¹⁴⁷ Sm were quantified from the number of counts of the obtained α-ray spectrum. Further, the recovery rates of ²⁴² Pu and ¹⁴⁷ Sm were calculated from the quantification result of ²⁴² Pu and ¹⁴⁷ Sm, the amount of ²⁴² Pu added to the saturated Ca (OH) ₂ aqueous solution 10A and the amount of ¹⁴⁷ Sm in Sm, respectively.
Further, the yield ratio ( ²⁴² Pu / ¹⁴⁷ Sm) was calculated by dividing the recovery rate of ²⁴² Pu by the recovery rate of ¹⁴⁷ Sm.

The above [preparation of α-ray measurement sample] and [α-ray measurement] tests were taken as one set, and this test was repeated for a total of 6 sets.
Recovery of ²⁴² Pu and ¹⁴⁷ Sm when performing 6 set ^test, the recovery rate of ²⁴² Pu is 90.1 ± ^5.9%, the recovery rate of ¹⁴⁷ Sm was 86.4 ± 4.9% . In addition, the yield ratio ( ²⁴² Pu / ¹⁴⁷ Sm) when six tests were performed was 1.04 ± 0.02%.
From these results, it was found that the recovery rate of ¹⁴⁷ Sm can be evaluated with an accuracy of an error of ± 10% or less with respect to the recovery rate of ²⁴² Pu.

(Comparative Example 1)
[Preparation of α-ray measurement sample]
FIG. 6 is a diagram showing an operation procedure 5 of the Pu quantitative analysis method of Comparative Example 1.
Operation procedure 5 of the Pu quantitative analysis method shown in FIG. 6 is a comparative example in which the iron hydroxide coprecipitation step S101 or S201 is not performed.

100 ml of a saturated Ca (OH) ₂ aqueous solution 10A at 25 ° C. was prepared, and 1 ml of 35% HCl (reference numeral 71) was added to the saturated Ca (OH) ₂ aqueous solution 10A to make the solution acidic, and in terms of Sm. 0.2 mg of Sm (NO ₃ ) ₃ (symbol 41) was added.

Next, when 2.5 ml of 46% HF (hydrofluoric acid, code 72) was dropped into this liquid, SmF ₃ precipitate (rare earth fluoride coprecipitate, code 52) was formed in the liquid 51. .
The obtained precipitate (reference numeral 52) was filtered through a filter having a pore size of 0.1 μm, and the filter cake was collected and dried (air-dried). Since the SmF ₃ precipitate contains a large amount of CaF ₂ , the filter cake on the filter became very thick with a thickness of about 1 mm.

[Α-ray measurement]
The dried filter cake (symbol 53) was subjected to α ray measurement (80000 sec) by α ray spectrometry.
For braze dried slag containing large amounts of CaF _2, a large self-absorption of α-rays, clear α-ray spectrum of ^{147 Sm (reference} numeral 42) was obtained.

  In addition, although several embodiment of this invention was described, these embodiment is shown as an example and is not intending limiting the range of invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1, 1A, 1B, 1C, 5 Pu quantitative analysis flow 10 Analysis target sample solution 10A Saturated Ca (OH) ₂ aqueous solution 11 Fe (OH) ₃ coprecipitate produced liquid (iron hydroxide coprecipitate containing rare earth elements) Liquid produced by
Liquid in which 11A Fe (OH) ₃ coprecipitate was generated (liquid in which iron hydroxide coprecipitate including rare earth elements and refined ²⁴² Pu tracer was generated)
12 Fe (OH) ₃ coprecipitate (iron hydroxide coprecipitate containing rare earth elements)
12A Fe (OH) ₃ coprecipitate (iron hydroxide coprecipitate containing rare earth elements and refined ²⁴² Pu tracer)
13 Fe (OH) ₃ coprecipitate solution (iron hydroxide coprecipitate solution)
13A Fe (OH) ₃ coprecipitate solution (iron hydroxide coprecipitate solution containing purified ²⁴² Pu tracer)
14, 51 SmF ₃ coprecipitate generated liquid 14A Purified ²⁴² SmF ₃ coprecipitate generated including Pu tracer 15, 52 SmF ₃ coprecipitate (rare earth fluoride coprecipitate)
15A SmF ₃ coprecipitate (rare earth fluoride coprecipitate including purified ²⁴² Pu tracer)
16, 53 Dry SmF ₃ coprecipitate (sample for measurement, sample for α-ray measurement)
16A SmF ₃ coprecipitate containing dried and purified ²⁴² Pu tracer (sample for measurement, sample for α-ray measurement)
Filtrate containing 22 Ca (contamination element) 23 Ca (contamination element)
31, 34, 71 HCl (acid)
32 Fe (NO ₃ ) ₃ (iron compound)
33 NaOH (pH adjuster)
35, 72 HF (fluoride)
41 Sm (NO ₃ ) ₃ (rare earth compound)
42 Sm-147 ( ¹⁴⁷ Sm)
43 Purified Pu-242 Tracer ( ²⁴² Pu Tracer)
44 Pu-242 ( ²⁴² Pu)
S101, S201 Fe (OH) ₃ coprecipitation step (iron hydroxide coprecipitation step)
S102, S202 Filtration / precipitation recovery process (filtration / iron hydroxide coprecipitate recovery process)
S103, S203 dissolution process (iron hydroxide coprecipitate dissolution process)
S104, S204 SmF ₃ coprecipitation process (rare earth fluoride coprecipitation process)
S105, S205 Filtration process (filtration and rare earth fluoride coprecipitate recovery process)
S106, S206 Drying step S107, S207 α ray measurement step (radiation measurement step)

Claims (13)

In a Pu quantitative analysis method for quantitatively analyzing Pu in a sample solution to be analyzed,
An iron hydroxide coprecipitation step of adding a rare earth compound and an iron compound to the sample solution to be analyzed to produce an iron hydroxide coprecipitate containing the rare earth element;
A rare earth fluoride coprecipitation step of generating a rare earth fluoride coprecipitate by adding fluoride to the iron hydroxide coprecipitate solution in which the iron hydroxide coprecipitate is dissolved;
And a radiation measurement step of performing radiation measurement on the measurement sample prepared from the rare earth fluoride coprecipitate to quantitatively analyze Pu. The Pu quantitative analysis method according to claim 1, wherein the radiation measurement method performed in the radiation measurement step is α-ray spectrometry. The method for quantitative analysis of Pu according to claim 1 or 2, wherein the sample solution to be analyzed contains a contaminating element that interferes with α-ray spectrometry. The Pu quantitative analysis method according to claim 3, wherein the impurity element is an alkaline earth metal. The Pu quantitative analysis method according to claim 4, wherein the alkaline earth metal is Ca. The method for quantitative analysis of Pu according to claim 5, wherein the sample solution to be analyzed contains 0.5 g / L or more of Ca (OH) ₂ . The Pu quantitative analysis method according to claim 1, wherein the rare earth compound is an Sm compound, and the rare earth element is Sm. The iron hydroxide coprecipitation step is a step of adding the pH adjuster comprising at least one of NaOH aqueous solution, NH ₃ aqueous solution and KOH aqueous solution to the sample solution to be analyzed to produce the iron hydroxide coprecipitate. The method for quantitative analysis of Pu according to any one of claims 1 to 7, wherein: 9. The Pu quantitative analysis according to claim 8, wherein the iron hydroxide coprecipitation step is a step of generating the iron hydroxide coprecipitate by adjusting the pH of the sample solution to be analyzed to pH 10 or more. Method. After the iron hydroxide coprecipitation step, the method further comprises an iron hydroxide coprecipitate dissolution step of dissolving the iron hydroxide coprecipitate with an acid to prepare an iron hydroxide coprecipitate solution. The Pu quantitative analysis method according to any one of claims 1 to 9. 11. The Pu quantitative analysis method according to claim 10, wherein the acid is an acid composed of at least one of hydrochloric acid and nitric acid. The recovery rate of the amount of ¹⁴⁷ Sm in the rare earth fluoride coprecipitate amount relative to the amount of ¹⁴⁷ Sm in the Sm compound added to the analysis target sample solution is expressed as the amount of Pu in the analysis target sample solution in the rare earth fluoride coprecipitate. The Pu quantitative analysis method according to any one of claims 7 to 11, wherein the Pu amount recovery rate is evaluated. The ¹⁴⁷ Sm in the Sm compound added to the sample solution to be analyzed is used as a tracer for evaluating the recovery rate of the Pu amount, thereby evaluating the Pu recovery rate without using the ²⁴² Pu tracer. The Pu quantitative analysis method according to any one of 7 to 12.

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