JP4584288B2 - Method for measuring helium content in metal materials - Google Patents

Description

  The present invention provides an improved method for measuring the helium content in a metal, more specifically, does not require a large-scale heating device or the like, and releases helium from a metal material with a simple device and process. It is related with the measuring method of helium content in the metal which can measure the helium content of metal easily and reliably.

Helium contained about 1ppm in air (the He) (concentration ^{10 14} / cc), the inside solid contains only a small amount. By the way, in the semiconductor field, an attempt has been made to improve the purity of the Si base by positively bombarding He with He ion implantation to accumulate impurities in holes formed in the Si.

  On the other hand, in the structure in the nuclear reactor, He is generated by the (n, α) reaction in the material irradiated with neutrons, causing the deterioration of the structural material due to the accumulation of a large amount of He. Has occurred.

  The He generated in the metal can be measured for the amount of accumulated neutrons at the installation position by measuring the amount of He in the metal after the metal piece is installed in the reactor for an appropriate period of time. Quantity measurement is used to estimate the amount of accumulated neutrons on the spot (see Non-Patent Documents 1-6).

  In order to measure the amount of helium in the metal, there is a technique based on elastic recoil detection (ERDA) using a MeV heavy ion beam. According to this method, it is possible to measure the depth distribution of the helium density from the solid surface (see Non-Patent Documents 7-9).

  However, in such a measurement method, since the measurable depth depends on the range of the incident ion beam, it is impossible to measure helium in a plate-like solid of mm order. Further, since the measurement range in the sample surface is determined by the spot size of the incident ion beam (usually about 1 mm in diameter), there is a problem that a large error occurs in the calculation of the total number of helium contained in the solid.

  As another helium measurement method, a method of processing a solid into thin pieces and observing with a transmission electron microscope is also used (see Non-Patent Document 10). According to this method, helium bubbles (He-bubble: like a He gas tank) and void structures from which He is removed can be visually measured. This is a method used to study the dynamics of He.

  However, such a measuring method has a problem that the number of He contained in the solid cannot be measured.

  Furthermore, as another helium measurement method, a method (heating / mass spectrometry) of measuring He gas emitted by heating / evaporating a solid with a high-performance mass analyzer is used. In this method, He is quantified by absolute calibration of a mass spectrometer using a standard gas prepared by diluting He gas of known purity.

  However, according to this measurement method, first, the metal is melted in order to release He gas from the metal. At this time, the required heating temperature differs depending on the metal containing He. For example, when the metal is copper (Cu), it is 1300 ° C. or higher. A high temperature is generated, and dissolved metal gas, outgas from the vacuum vessel wall, and the like are generated.

Therefore, in order to solve these problems, He to be measured is not exhausted, but a large vacuum exhaust device (Ti getter pump or the like) and advanced vacuum technology for exhausting other unnecessary gases are required. There's a problem.
H. Farra IV, WNMcelroy and EPLippincott: Nucl. Technol., 25 (1975) 305. DW Kneff and H. Farra: J. Nucl. Mater., 85 & 96 (1979) 479. DW Kneff, BMOliver and H. Farra IV: Nucl. Sci. Eng, 92 (1986) 491. H. FarraIV and BMOliver: J. Vac. Sci. Technol., A4 (1986) 1740. T. Fukahori, Y. Kanada, H. Tobimatsu, Y. Maeda, K. Yamada, T. Nakamura and Y. Ikeda: J. Nucl. Sci. Technol., 23 (1986) 91. Y. Takao and Y. Kanda: Rev. Sci. Instrum., 67 (1996) 198. M.Ogawa, M. Nakajima, K. Kurimoto and K. Hashimoto: J. Nucl. Mater. 179-181 (1991) 449. P. Haussalo, J. Keinonen, U.-M. Jaske and J. Sievinen: J. Appl. Phys. 75 (1995) 7770. M. Ogura, N. Yamaji, T. Higuchi, M. Imai, A. Itoh, N. Imanishi and K. Nakata: Nucl. Instr. And Meth. B136-138 (1998) 483. CHZhang, KQChen, YSWang and JGSun: Nucl. Instr. And Meth. B135 (1998) 256.

  The present invention has been made in view of the above-described problems in the conventional method for measuring the content of helium, and does not require a large-scale heating device or the like. It is an object of the present invention to provide a method for measuring the helium content in a metal that can easily and reliably measure the amount of He in the metal by releasing helium from the metal.

  Means employed by the present inventor for solving the above-described problems will be described with reference to the accompanying drawings.

That is, the present invention is a method for measuring the amount of helium contained in the metal material 1,
While the metal material 1 and the aqueous solution 2 for dissolution formed by dissolving an acid or alkali in water are housed and sealed in a container 3 capable of housing them independently in a non-contact state,
After the inside of the container 3 is evacuated, it is filled with a carrier gas,
The metal material 1 is immersed in the aqueous solution 2, the metal component 11 of the metal material 1 is completely dissolved, and the gas component 12 generated from the metal material 1 is collected.
The method for measuring the helium content in a metal material was completed by adopting technical means of ionizing the ions of the gas component 12 and detecting helium ions by accelerating the ions.

  Further, in order to solve the above-mentioned problems, the present invention uses an H-type reaction tube in which two pipe members 31 and 31 are connected at the middle part as the container 3 in addition to the above means as necessary. The technical means of accommodating the metal material 1 in one tube member and housing the aqueous solution 2 in the other tube member was employed.

  Furthermore, in order to solve the above-mentioned problems, the present invention punctures the needle of the syringe 6 into the soft resin sealing member 32 disposed at the side end of the container 3 in addition to the above means as necessary. The technical means of collecting the generated gas component 12 was adopted.

  Furthermore, in order to solve the above-described problems, the present invention employs technical means of using nitrogen gas as a carrier gas in addition to the above means as necessary.

  Furthermore, in order to solve the above-described problems, the present invention employs technical means in which a strong acid or a strong alkali is used as the solute of the aqueous solution 2 for dissolution in addition to the above means as necessary.

  Furthermore, in order to solve the above-described problems, the present invention employs technical means in which a nitric acid aqueous solution is used for the aqueous solution 2 for dissolution in addition to the above-described means as necessary.

  Furthermore, in order to solve the above-described problems, the present invention employs technical means that the concentration of the aqueous solution 2 for dissolution is 20% in addition to the above means as necessary.

  In the present invention, a metal material and an aqueous solution for dissolving an acid or alkali in water are housed in a container that can be independently housed in a non-contact state and sealed. Once the inside is evacuated, it is filled with a carrier gas, the metal material is immersed in an aqueous solution, the metal component of the metal material is completely dissolved, and the gas component generated from the metal material is collected, The helium content in the metal material can be measured by ionizing the gas component ions and detecting the helium ions by accelerating the ions.

  Therefore, according to the measurement method of the present invention, by utilizing the characteristic that helium has a very low solubility in a liquid, a large-scale heating device or the like is not required, and a simple device and process can be used to remove metal material. By releasing helium, the amount of He in the metal can be measured easily and reliably, and the total amount can be estimated from the sample piece. Therefore, the practical utility value in a nuclear power generation facility is very high. Yeah.

  BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out the present invention will be described in more detail with reference to the drawings specifically shown as follows.

  An embodiment of the present invention will be described with reference to FIGS. First, helium (He) to be measured will be described. Since helium contained in air at about 1 ppm is an extremely stable atom (the ground state has a closed shell structure consisting of two electrons in 1 s and has the smallest mass). Inactive elements), do not chemically bond with other atoms and molecules.

  In addition, the He that is present (or generated) in the solid due to the (n, α) reaction by neutron irradiation, etc., is shot in He using an ion manufacturing apparatus, alloy production process, and constitutes a solid (metal, semiconductor, insulator) It exists in a metastable state as an interstitial-atom without chemically bonding to the element that performs.

  If the number of He in the solid increases, spherical helium bubbles (such as a He-bubble: He gas tank) are formed. This solid representative is most metal solids, for example, in the case of aluminum Al up to 300 ° C., in the case of copper Cu up to 600 ° C., in the case of vanadium V up to 900 ° C. He taken in is not released from the metal (the melting points of Al, Cu and V are ˜660 ° C., ˜1085 ° C. and ˜1890 ° C., respectively).

  Depending on the temperature of the solid, He in the bubble may be released from the solid, and a helium void (He-void) from which He is removed may be formed in the solid. This solid example is semiconductor silicon (Si), and after irradiation with a large amount of He by ion implantation, helium voids are formed in Si under an appropriate temperature condition.

  Helium bubbles are formed when the number of He generated in the solid is large. When a small number (for example, one) of He is assumed, there are many sites (for field) where He can exist in the solid. When the solid is a single crystal, the above-mentioned interstitial site is added, and when the solid is a polycrystal, the interface between crystal grains is added. Whether He is released from the solid or stays in the solid is determined by the kinetic energy of He and the magnitude of the energy potential of He, so the type of solid and the solid temperature (kinetic energy of He in the solid) Depends on.

In order to measure the amount of He in a solid, it is necessary to release He from the solid by some method. In this embodiment, the metal is dissolved in an acid (or alkali) aqueous solution in a 1 atm N ₂ atmosphere by chemical treatment. This method is used.

  Since He does not chemically bond with other elements, the solubility of He in the liquid layer is extremely low, and He released into the aqueous solution is released from the liquid phase into the gas phase (He is the most soluble in water). A small gas). The present invention takes advantage of this characteristic.

  An experimental layout of He-containing metal piece melting in this embodiment is shown in FIG. The used container 3 uses an H-shaped reaction tube made of glass in which two pipe members 31 and 31 are connected at the middle abdomen, and has an inner diameter of ˜6 mm and a volume of ˜9 mL or ˜35 mL. The H-type reaction tube is sealed with a silicon lid and two rotatable glass caps.

In the drawing, GV _{1 to} GV ₃ are gate valves (Gate-Valve), and perform full opening or full closing of the valves. Further, GP ₁ and GP ₂ are glass-made sealable cocks. A pipe having a diameter of ˜3 mm is formed in the pipe corresponding to GP ₂ of the container 3, and the exhaust in the reaction tube and the gas introduction into the tube can be performed by the rotation of the cock. In the following description, “rotate GP ₂ to open” means a state where gas can freely enter and exit the container 3, and “rotate GP ₂ to close” means that the container 3 is sealed. Means.

Next, the measurement method of this embodiment will be described. In this embodiment, first, as a premise for preparing the sample gas, a Cu piece (metal material 1) containing an appropriate amount of He is prepared by an ion implantation method. For the metal piece, copper (Cu) having a width of 4 mm, a length of 8 mm, a thickness of 0.2 mm, and a weight of 0.029 g was used, and the He injection amount was 10 ¹⁶ to 10 ¹⁷ per sample.

The N ₂ gas server 4 uses an aluminum bag (made by GL Science, maximum volume 5L) with an area of ~ 34cm x 22.5cm and a surface that freely expands and contracts. After exhausting the server chamber to a vacuum, the purity is 99.999% Packed with ~ 4000cc N ₂ gas.

  Here, Cu proceeds vigorously in concentrated nitric acid with high purity and dissolves within a short time. Considering the ease of handling, we examined how much nitric acid concentration should be used. First, an aqueous nitric acid solution having a concentration of 60% was used. Cu reacted vigorously in the solution and dissolved in 1-2 minutes. When nitric acid aqueous solutions having a concentration of 30% and a concentration of 20% were used, the time required for dissolution of Cu was -10 minutes and ˜45 minutes, respectively. In the nitric acid aqueous solution having a concentration of 10%, the Cu pieces were not completely dissolved even after 2 hours. All Cu dissolution tests were performed at room temperature. From the above test results, an aqueous nitric acid solution having a concentration of 20% is used.

In the present embodiment, if the following conditions are satisfied in the relationship between usable solids (including metals, semiconductors, and insulators) and the aqueous solution used, the method of the present invention can determine the amount of He in the solids. Applicable to measurement.
“Condition 1” A solid that can be dissolved in an acid (or alkali) aqueous solution.
“Condition 2” A container (for example, an H-type reaction tube) that does not dissolve in the aqueous solution can be produced.

  That is, the method of the present invention has an advantage that it can be applied as long as it is dissolved in an acid (or alkali) aqueous solution, no matter how high the melting point, when compared with a high temperature heating (melting) method in a vacuum atmosphere.

The specific experimental procedure is as follows.
[Step 1]
A He-containing Cu piece is inserted into one tube member 31 of a container 3 (H-type reaction tube) cleaned with acetone, and 0.5 cc of 20% nitric acid aqueous solution is inserted into the other tube member 31, and caps GP ₁ and GP ₂ are attached.

[Step 2]
Rotate GP ₂ to open, open GV ₁ and GV ₂ , and exhaust with a pump for an appropriate time. At this time, GV ₃ is closed. When exhausted with a normal rotary pump, the aqueous solution 2 may boil. For the vacuum pump of this embodiment, Chemical-Duty-Vacuum-Pump (manufactured by MILLIPORE) used for chemical experiments for exhausting the atmospheric pressure of the system in which the liquid layer exists was used.

[Step 3]
After evacuating the inside of the H-type reaction tube, GV ₁ and GV ₂ are closed, GV ₁ and GV ₃ are quickly opened, and the inside of the container 3 (H-type reaction tube) is set to 1 atm.

[Step 4]
The GV ₃ is closed, the GV ₂ is opened, and the inside of the container and piping is evacuated by the pump 5 for an appropriate time.

[Step 5]
GV ₂ is closed again, GV ₃ is opened, and the inside of the container is brought to 1 atm.

[Step 6]
After evacuating the inside of the reaction tube and making an atmosphere of 1 atm is repeated about 10 times, GP ₂ is closed. This operation was performed for the purpose of preventing 1 ppm He existing in the air from being mixed into the analysis gas. As can be seen in the GC / MS analysis described later, in the He analysis using about 10 ¹⁵ pieces of He-implanted Cu pieces, if the above operation is performed once, the effect of He in the air is It was a negligible level.

[Step 7]
The container 3 (H-type reaction tube) is tilted and the nitric acid aqueous solution 2 is poured into a small piece of the metal material 1.

[Step 8]
The metal component 12 (Cu) is completely melted in the nitric acid aqueous solution 2. (It completely melts in about 45 minutes)

[Step 9]
The needle of the syringe 6 is inserted into a soft resin (silicon) sealing member 32 disposed at the side end of the container 3 to collect an appropriate amount of the gaseous component 12 containing He after the reaction.

<About the analysis of “gas component 12”>
A certain amount of the gas component 12 (hereinafter also referred to as “sample gas”) collected in this manner is injected into a GC / MS apparatus described later, and He in the sample gas is analyzed. In addition, when the gas before tilting the H-type reaction tube (before the melting reaction) is collected with a syringe from the silicon lid, and introduced into the GC / MS device, no significant He signal appears. Check it.

  In this embodiment, a high-resolution mass spectrometer (JEOL: JMS-700 MStation) is used, and the high-resolution mass spectrometer is shown in the conceptual diagram shown in FIG. Etc. will be explained.

  This apparatus is usually called a gas chromatography / mass spectrometer (abbreviated as Gas / Chromatography / Mass-Spectrometer, (GC / MS)). The GC / MS apparatus includes a gas chromatography section (GC section), a gas ionization section, a mass analysis section, and an ion detection section. Then, the sample gas to be measured is mixed into the carrier gas, and the trace gas contained in the sample gas is analyzed.

In a normal analysis using the GC / MS apparatus, since various molecules such as a polymer are included, in order to facilitate the analysis, He is used as a carrier gas. Since this He is a measurement object, nitrogen gas (N ₂ ) is used as a carrier gas.

  The analysis process of the GC / MS apparatus will be described in accordance with the He analysis performed here. As described above, as the sample gas for analysis, a gas prepared by dissolving a Cu small piece into which He was shot by ion implantation with a nitric acid aqueous solution in a nitrogen atmosphere was used.

In this embodiment, high-purity N ₂ gas is used as the carrier gas, and the gas flow rate is 0.3 mL / min. The sample gas is introduced into the carrier gas with a syringe, and measurement of the ion detector is started.

  The sample gas mixed in the carrier gas is guided to the gas ionization chamber after passing through the column (separation tube). The column used was a capillary tube having a diameter of 0.25 mm and a length of 50 m (inner film-thickness, 0.25 um, Column No 351175). At this time, the temperature in the gas chromatography section in which the capillary tube was installed was set to 150 ° C. In the ionization chamber, the gas is ionized by electron beam irradiation. The acceleration energy of the electron beam was 70 eV, the ionization current was 300 μA, and the ionization chamber was 200 oC.

  The ions ionized in the sample gas are accelerated by a potential of 10 kV and are incident on the analysis chamber. The incident ions are separated in an electric field and a magnetic field based on energy and mass, and only ions to be measured are incident on the detection unit. In the present embodiment, since the purpose is to measure He in the sample gas, the magnetic field and the electric field strength are determined so that the output signal of 10 keV He ions is maximized.

The time change of the He signal was recorded from the time when the sample gas was introduced into the carrier gas. At this time, the voltage for electron multiplication in the ion detector was set to 1 kV. Further, throughout this measurement, the gas ionization chamber had a vacuum degree of ˜3 × 10 ⁻⁴ Pa and the analysis chamber had a vacuum degree of ˜3 × 10 ⁻⁵ Pa.

  An example of the output signal of the ion detector obtained by this embodiment is shown in FIG. The vertical axis is the detector output signal intensity (unit is arbitrary), and the horizontal axis is the time when the sample gas is introduced into the GC / MS. In addition, even if no sample gas is introduced, there may be a case where a signal due to He having a mass number of 4 that is almost constant in time is detected, but this is caused by He remaining in the container of the GC / MS apparatus. it is conceivable that.

  According to FIG. 3, the He signal intensity rapidly increases about 5 minutes after the introduction of the sample gas, and reaches a maximum after about 6 minutes. The output intensity decreases considerably after about 7 minutes, then gradually decreases, and after about 10 minutes becomes the intensity before the introduction of the sample gas. Since the signal resulting from the sample gas is pulsed, it is referred to herein as a pulse signal. It can be seen that the signal intensity increases stepwise from the rise of the pulse signal to the maximum value. This is because a dispenser was attached to the syringe from which the sample gas was collected, and a method of introducing 0.05 cc into the GC / MS 10 times at 5 second intervals (total of 0.5 cc) was adopted.

  In this embodiment, sample gas introduction into the GC / MS by a syringe is performed manually. The reason why the Dispenser is used in this way is to avoid as much as possible that the indeterminate factor of the gas introduction speed affects the measurement result.

  A value corresponding to the amount of He introduced into the GC / MS apparatus is proportional to a value obtained by temporally integrating the pulse signal. The analysis results of the He gas mixed gas in FIGS. 4 and 5 are plotted by plotting the time integration value as the He intensity.

  In the present embodiment, after the sample gas is passed through the GC section, part of the gas is ionized (weakly ionized plasma) in the ionization chamber, and mass spectrometry is performed after acceleration at 10 kV. At this time, the GC unit is not always necessary, but as shown in FIG. 3, when the GC unit is used, a signal due to the introduced He is observed more clearly.

  Regardless of whether or not the GC unit is used, the particles that enter the ion detector are limited to ions with an energy of 10 keV and a mass number of 4, so any other element or molecule is included in the analysis gas, which is ionized. Even if accelerated, it does not enter the detector when set in the present embodiment.

  Next, in this embodiment, the possibility of the influence of other product gas generated during the dissolution reaction will be described.

  If a high-sensitivity gas analyzer similar to a mass analyzer is used, He having an atomic mass number of 4 can be distinguished from other elements. Therefore, the He in the gas can be analyzed regardless of the gas of any other component contained in the gas from which He has been released.

Practical issues should be taken into account, for example, the ease of handling of aqueous solutions and contamination of equipment in analytical measuring instruments by gases other than He, but it is fatal because the amount of gas required for measurement is small. It doesn't matter. In this embodiment, HCl and H ₂ SO ₄ were not used because of the influence on the analyzer used.

As is well known, when concentrated nitric acid is added to Cu, a reaction represented by the following formula occurs, Cu is dissolved, and nitrogen dioxide NO ₂ is generated.
Cu + 4HNO → Cu (NO ₃ ) ₂ + 2NO ₂ + 2H ₂ O
Further, Cu is dissolved by dilute nitric acid and the following formula to generate Cu and NO is generated.
3Cu + 8HNO → 3Cu (NO ₃ ) ₂ + 2NO + 4H ₂ O
NO is a gas that is difficult to dissolve in colorless water, and is easily oxidized in the air to become reddish brown NO ₂ .

In this embodiment, a 20% nitric acid aqueous solution was used for melting Cu. Sample gas produced is to be done at 1 atm N ₂ atmosphere, most of the sample gas is N _2. Molecules (or elements) other than He to be measured are H ₂ O, NO, NO _{2 and the} like. Compared with He, these molecules are delayed more and pass through the gas chromatography part (GC part), and then reach the ionization chamber, so that the signals can be distinguished in terms of time. However, as described above, other than the 10 keV He ions are not incident on the ion detector without using the GC unit. In this embodiment, there was no influence of oxidizing gas derived from HNO ₃ such as NO, NO ₂ , N ₂ O ₄ .

Next, calibration of the mass spectrometer used in this embodiment will be described. The volume VO of the reaction tube can be measured by a gravimetric method. Cork VP ₁ , VP ₂ and seal member 32 (silicon lid) are attached to the Hg type reaction tube, and the weight m ₁ is measured. Next, the inside of the reaction tube is filled with distilled water, VP ₂ is closed, and the weight m ₂ is measured. At that time, it is confirmed that there is no space not filled with water such as bubbles in the reaction tube. _Then, it is the volume VO of the reaction tube _(m 2 -m _1).

The volumes of the two reaction tubes (containers 3) used in this embodiment were (1) VO ₁ = 8.71 cc and (2) VO ₂ = 35.15 cc. Volume of aqueous solution used (20% nitric acid aqueous solution 0.5 cc) and volume of metal material 1 solid piece (Cu piece used in the test has an area of 4 x 8 mm and a thickness of 0.2 mm [weight, 0.029 g]) Is known, the volume Vh of the space from which He is released is known.

Assuming that all of He in Cu injected with 1 × 10 ¹⁶ He is released into the gas layer by dissolution, the He concentration n _He in the gas in the reaction tube of VO ₁ is n _He ≈1.2 ×. 10 ¹⁵ / cc, and a to 2.9 × ^{10 14} pieces / cc in a reaction tube of VO _2, when He number of pieces _{^{1 × 10 17, n He ≒}} 1.2 × 10 16 pieces / cc (VO ₁ reaction tube) and ˜2.9 × 10 ¹⁵ pieces / cc (VO ₂ reaction tube). Therefore, a standard sample gas having a He concentration of n _He ≈3 × 10 ¹⁴ cells / cc to 1.0 × 10 ¹⁶ cells / cc is prepared, and the same amount of gas as in this embodiment is introduced into the GC / MS to detect ions. By using the value obtained by integrating the signals, absolute calibration of the GC / MS apparatus with respect to He in this embodiment is possible.

Production of a standard sample gas for absolute calibration of the GC / MS apparatus will be described with reference to FIG. The equipment for producing this standard sample gas is a small vacuum vessel A, a slightly larger vacuum vessel B, an exhaust device (turbomolecular pump TP, rotary pump RP), high purity He gas, high purity N ₂ gas, and each connected. Gate valves GV _{1 to} GV ₆ are configured. The vacuum vessel A has a relatively simple cylindrical shape, and the volume V ₁ is known in a state where GV ₁ and GV ₂ are closed. The entire container is installed in a temperature controlled laboratory, and the container temperature is always constant.

The operation procedure for preparing the standard sample gas is shown below.
1) Evacuate the vacuum vessel to a high vacuum. (Bake at an appropriate temperature)
2) Open GV ₁ and enclose an appropriate amount of high-purity He gas in the container 1, and set the pressure at that time to P ₁ . The pressure is measured with a Macland vacuum gauge.
3) With GV ₃ , GV ₄ , and GV ₆ closed, GV ₂ is opened and pressure P ₂ is measured.
4) The volume V ₂ in which He is enclosed is determined from [V ₁ · P ₁ / P ₂ ], and the He concentration n _He is calculated.
5) N ₂ gas is introduced into the system until the pressure becomes 1 atm from GV ₃ to prepare a standard sample gas.

  Then, gas is collected from the silicon film window using a syringe in the same manner as described above, and then introduced into the GC / MS and integrated with the pulse signal, and the absolute calibration for the He sensitivity is completed.

<About analysis results>
FIG. 4 shows the results of GC / MS analysis of He-mixed gas using an H-type reaction tube having a volume of 8.71 cc. The amount of He ion implantation into the used Cu is
1) to 1.01 × 10 ¹⁶ pieces 2) to 2.00 × 10 ¹⁶ pieces 3) to 3.99 × 10 ¹⁶ pieces 4) to 7.97 × 10 ¹⁶ pieces 5) to 1.61 × 10 ¹⁷ pieces 6) to 1.61 × 10 ¹⁷ pieces 7) to 3.22 × 10 ¹⁷ pieces.

The output signal of GC / MS shows good linearity when the number of injections is from 1 × 10 ¹⁶ to ˜8 × 10 ¹⁶ . When a large amount of He is implanted into the metal by ion implantation, the helium formed in the metal is ruptured, so that the output signal does not increase proportionally when the number of implanted ions is ˜8 × 10 ¹⁶ or more.

FIG. 5 shows the result of GC / MS analysis of He-containing gas using a 35.15 cc H-type reaction tube. The number of He injections of the sample used was
1) to 1.01 × 10 ¹⁶ pieces 2) to 1.95 × 10 ¹⁶ pieces 3) to 3.98 × 10 ¹⁶ pieces 4) to 8.03 × 10 ¹⁶ pieces 5) to 1.58 × 10 ¹⁷ pieces 6) to 3.25 × 10 ¹⁷ pieces.

Similarly to FIG. 4, even when a reaction tube having a volume about 4 times is used, the output signal of GC / MS shows good linearity when the number of injections is from 1 × 10 ¹⁶ to ˜8 × 10 ^16. . Similarly, when the injection amount is large, the output signal of the GC / MS does not increase proportionally.

  In the present embodiment, high-accuracy absolute calibration is not performed for the GC / MS He used. This is because a commercially available He gas having a known purity is diluted to produce a standard He gas, and the GC / MS can be calibrated under the same experimental conditions as the He measurement in metal.

  The present invention is generally configured as described above. However, the present invention is not limited to the illustrated embodiment, and various modifications can be made within the scope of the claims. For example, The combination of the metal sample and the aqueous solution used in this example is copper and nitric acid, but there are an enormous number of combinations of the aqueous solution-melting solid as another combination. Examples of solids and aqueous solutions for dissolution are shown in the table below.

[Table 1]
Type of solid Symbol Aqueous solution "Metal example"
Copper Cu Nitrate Aluminum Al Sodium hydroxide, Vanadium fluoride V Iron nitrate Fe Diluted nitrate Zinc Zn Nitrate Lead Pb Nitric acid "Semiconductor example"
Silicon Si Nitric acid (HNO ₃ ) + Fluoric acid (HF) + Acetic acid (CH ₃ COOH)
"Example of insulation"
Silicon oxide SiO ₂ Fluoric acid

  Thus, the amount of He can also be measured by a combination of different materials, and any of these belong to the technical scope of the present invention.

It is the schematic showing the experimental apparatus of embodiment of this invention. It is the schematic showing the GC / MS apparatus of embodiment of this invention. It is the schematic showing the example of GC / MS analysis of the embodiment of the present invention. It is a graph showing the analysis result in embodiment of this invention. It is a graph showing the analysis result in embodiment of this invention. It is the schematic showing the standard He gas preparation test for a calibration of embodiment of this invention.

Explanation of symbols

1 Metal material 2 Aqueous solution 3 Container
31 Pipe members
32 Sealing member 4 Gas server 5 Exhaust pump 6 Syringe

Claims (7)

A method for measuring the amount of helium contained in a metal material 1,
While the metal material 1 and the aqueous solution 2 for dissolution formed by dissolving an acid or alkali in water are housed and sealed in a container 3 capable of housing them independently in a non-contact state,
After the inside of the container 3 is evacuated, it is filled with a carrier gas,
The metal material 1 is immersed in the aqueous solution 2, the metal component 11 of the metal material 1 is completely dissolved, and the gas component 12 generated from the metal material 1 is collected.
A method for measuring a helium content in a metal material, characterized in that helium ions are detected by ionizing ions of the gas component 12 and accelerating the ions.   As the container 3, an H-type reaction tube in which two tube members 31 and 31 are connected at the middle part is used. The metal material 1 is accommodated in one tube member, while the aqueous solution 2 is accommodated in the other tube member. The method for measuring a helium content in a metal material according to claim 1.   3. The metal material according to claim 1, wherein the generated gas component 12 is collected by puncturing a needle of a syringe 6 into a soft resin sealing member 32 disposed at a side end of the container 3. Helium content measurement method.   Nitrogen gas is used as carrier gas, The helium content measurement method in the metal material as described in any one of Claims 1-3 characterized by the above-mentioned.   The method for measuring the helium content in a metal material according to any one of claims 1 to 4, wherein a strong acid or a strong alkali is used as a solute of the aqueous solution 2 for dissolution.   The method for measuring the helium content in a metal material according to any one of claims 1 to 5, wherein an aqueous nitric acid solution is used as the aqueous solution 2 for dissolution.   The method for measuring the helium content in a metal material according to any one of claims 1 to 6, wherein the concentration of the aqueous solution 2 for dissolution is 20%.

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