INORGANIC COMPOSITION AND FIBERS AND FLAKES THEREOF

Abstract

[Object] Provided are inorganic fibers or inorganic flakes having excellent neutron shielding properties.

[Solution] When a formulation including: a base component containing SiO.sub.2 and Al.sub.2O.sub.3 as main components (provided that the mass ratio occupied by the sum total of SiO.sub.2 and Al.sub.2O.sub.3 in the base component is 0.60 or more); and a neutron shielding component composed of at least one of gadolinium, gadolinium oxide, samarium, samarium oxide, cadmium, or cadmium oxide, are blended at the proportions of 50 to 90 parts by mass of the base component and 10 to 50 parts by mass of the neutron shielding component and melted, satisfactory amorphous inorganic fibers and inorganic flakes were obtained.

Claims

1. An inorganic composition in an amorphous state, the inorganic composition comprising: i) 50% to 90% by mass of a glass-forming component containing SiO.sub.2 and Al.sub.2O.sub.3 as main components; and ii) 10% to 50% by mass of a neutron shielding component including gadolinium simple substance, gadolinium oxide (Gd.sub.2O.sub.3), samarium simple substance, samarium oxide (Sm.sub.2O.sub.3), cadmium simple substance, cadmium oxide (CdO), or a mixture thereof, wherein iii) a mass ratio occupied by a sum total of SiO.sub.2 and Al.sub.2O.sub.3 in the glass-forming component is 0.50 or more.

2. The inorganic composition according to claim 1, wherein a proportion occupied by the neutron shielding component in the inorganic composition is 20% by mass or more, and a mass ratio occupied by Fe.sub.2O.sub.3 in the glass-forming component is 0.25 or less.

3. The inorganic composition according to claim 1, wherein a proportion occupied by the neutron shielding component in the inorganic composition is more than 35% by mass, and a mass ratio occupied by Fe.sub.2O.sub.3 in the glass-forming component is less than 0.15.

4. The inorganic composition according to claim 1, wherein the glass-forming component contains fly ash, clinker ash, or basalt.

5. The inorganic composition according to claim 4, wherein the glass-forming component is fly ash.

6. Fibers of the inorganic composition according to claim 1.

7. Flakes of the inorganic composition according to claim 1.

8. A material filled with the fibers according to claim 6.

9. The material according to claim 8, being a fiber-reinforced resin.

10. The material according to claim 8, being a fiber-reinforced cement.

11. A coating material comprising the flakes according to claim 7 as an admixture.

12. A neutron shielding member formed from the material according to claim 8.

13. A neutron shielding member coated with the coating material according to claim 11.

14. An inorganic fiber bundle obtained by attaching a sizing agent to the inorganic fibers according to claim 6, wherein the sizing agent is any one of the following: i) paraffin wax, ii) microcrystalline wax, iii) polyethylene or an ethylene copolymer mainly based on ethylene, and iv) polypropylene.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0094] FIG. 1 is a diagram illustrating an outline of a fiberization test;

[0095] FIG. 2 is a diagram illustrating an outline of a flaking test;

[0096] FIG. 3 is XRD spectra of Example 10 and Comparative Example 2;

[0097] FIG. 4 is a schematic diagram of an apparatus used for positron lifetime measurement;

[0098] FIG. 5 is a comparison diagram of positron lifetime spectra before and after irradiation of the inorganic composition of Example 19 with radiation;

[0099] FIG. 6 is a comparison diagram of positron lifetime spectra before and after irradiation of the inorganic composition of Comparative Example 6 with radiation;

[0100] FIG. 7 is a graph showing the relationship between the content of neutron shielding elements in the composition and the resistance to radiation deterioration; and

[0101] FIG. 8 is a comparison photograph of neutron radiography of the inorganic fibers of the invention and the inorganic fibers of the prior art.

MODE(S) FOR CARRYING OUT THE INVENTION

[0102] Hereinafter, the contents of the invention will be specifically described in Test Examples.

[0103] In the following Test Examples (Examples and Comparative Examples), the following reagents and raw materials were used.

[0104] Fly ash: FA1, FA2, FA4, FA5 (obtained domestically and abroad. The components (% by mass) are described in Table 1). [0105] Copper slag: CS (obtained domestically. The components (% by mass) are described in Table 1). [0106] Volcanic rock: BA (obtained in Japan. The components (% by mass) are described in Table 1). [0107] Silica: SiO.sub.2 (reagent, powder) [0108] Alumina: Al.sub.2O.sub.3 (reagent, powder) [0109] Calcium oxide: CaO (reagent, powder) [0110] Calcium carbonate: CaCO.sub.3 (reagent, powder) [0111] Iron (III) oxide: Fe.sub.2O.sub.3 (reagent, powder) [0112] Magnesium oxide: MgO (reagent, powder) [0113] Titanium oxide: TiO.sub.2 (reagent, powder) [0114] Potassium carbonate: K.sub.2CO.sub.3 (reagent, powder) [0115] Boric acid: H.sub.3BO.sub.3 (reagent, powder)

[0116] Gadolinium (simple substance): Gd (reagent, powder) [0117] Gadolinium oxide: Gd.sub.2O.sub.3 (reagent, powder) [0118] Samarium (simple substance): Sm (reagent, powder) [0119] Samarium oxide: Sm.sub.2O.sub.3 (reagent, powder) [0120] Cadmium (simple substance): Cd (reagent, powder)

TABLE-US-00001 TABLE 1 Component FA1 FA2 FA4 FA5 BA CS Fe.sub.2O.sub.3 (F) 13 9 9 11 19 55 SiO.sub.2 (S) 57 54 62 59 46 35 Al.sub.2O.sub.3 (A) 17 11 18 18 11 5 Cao (C) 6 17 3 4 17 2 Others 7 9 8 8 7 3 Remarks Fly ash Volcanic Copper rock slag

[0121] Incidentally, the component analysis of FA1, FA2, FA4, FA5, CS, and BA was carried out by a fluorescent X-ray analysis method.

[0122] The raw materials for the glass-forming component and the reagents for the neutron shielding component are weighed at predetermined proportions and mixed in a mortar to prepare a powdered raw material formulation.

[0123] For the raw material formulation, the melt spinnability thereof is evaluated by the following procedure. An outline of the test is shown in FIG. 1. In FIG. 1, an electric furnace (11) has a height (H) of 60 cm and an outer diameter (D) of 50 cm and has an opening part (14) with a diameter (d) of 10 cm at the center. On the other hand, 30 g of the formulation is charged into a Tammann tube (12) having an inner diameter () of 2.1 cm and a length of 10 cm. Incidentally, a hole with a diameter of 2 mm is opened at the center of the bottom part of the Tammann tube (12). During a melting test, the Tammann tube (12) is held at a predetermined position within the opening part (14) of the electric furnace by a hanging rod (13).

[0124] The temperature in the electric furnace is raised by a predetermined temperature increase program, and the maximum reach temperature of the temperature inside furnace is set to 1450 C. At this time, it has been confirmed in advance that the temperature inside the Tammann tube (molten material) follows the temperature profile inside the furnace at a temperature lower by approximately 50 C. When the raw material formulation is melted by heating, the raw material formulation flows and falls down from the bottom part of the Tammann tube due to its own weight and solidifies upon contact with the outside air.

[0125] In the invention, as an index for the evaluation of melt-spinnability, when the raw material formulation melts before the temperature inside the furnace reaches 1450 C., and the molten material flows and falls down to form a thread, that is, when the melting temperature of the raw material formulation is 1400 C. or lower, and the molten material has a melt viscosity appropriate for forming a thread, it was considered as an acceptable level. The melting behavior of the raw material formulation as a sample is roughly classified into the following groups A to C.

[0126] A: Forms a thread.

[0127] B: The sample does not melt, or the viscosity of the molten material is so high that the molten material does not fall down by its own weight, and the sample does not form a thread.

[0128] C: The sample melts; however, the viscosity of the molten material is too low, and the sample becomes liquid droplets to drip down and does not form a thread.

[0129] The raw material formulation is submitted to a flaking test (evaluation of flake processability) by the following procedure. An outline of the test is shown in FIG. 2.

[0130] The raw material formulation is melted according to the procedure of the following steps 1 to 4, and flaking of the molten material is attempted.

[0131] Step 1: About 60 grams of the raw material formulation (fp) is charged into a crucible (21) having a diameter (D1) of 20 mm. Separately, a Tammann tube (22) having a diameter (D2) of 10 mm is prepared. The Tammann tube (22) has an opening part (221) with a hole diameter () of 2 mm at the bottom part (upper row of FIG. 2).

[0132] Step 2: The crucible (21) charged with the formulation (fp) is heated in the electric furnace (23) (left side in the middle row of FIG. 2). The temperature of the electric furnace is raised by a predetermined temperature increase program. The maximum reach temperature of the temperature inside the furnace is set to 1450 C. It has been checked in advance that the temperature inside the crucible (21) and the molten material (fm) follows the temperature profile inside the furnace at a temperature lower by approximately 50 C.

[0133] Step 3: The crucible (21) after the temperature increase is immediately taken out from the electric furnace (23), and the Tammann tube (22) is downwardly pressed down from the top of the crucible (21). The inorganic composition molten material (fm) inside the crucible (21) enters into the Tammann tube (22) through the opening part (221) (right side in the middle row of FIG. 2).

[0134] Step 4: Next, the Tammann tube (22) storing the molten material (fm) is taken out from the crucible (21), and immediately air is blown at a pressure of about 10 MPa through the mouth part (222) of the tube (left side in the lower row of FIG. 2). When the molten material (fm) has appropriate viscosity, the molten material swells and forms a hollow thin-walled balloon (fb) (right side in the lower row of FIG. 2). The balloon is crushed to obtain flakes.

[0135] Based on the results of a flaking test based on the above-described procedure, flake processability is rated as a, b, and c as follows.

[0136] a: After going through Step 1 to Step 4, a balloon is formed.

[0137] b: Since the formulation (fp) does not start melting or the viscosity of the molten material is high even after reaching Step 2, the molten material does not enter into the Tammann tube (22) through the opening part (221) in Step 3.

[0138] c: Although Step 1 to Step 3 are reached, since the viscosity of the molten material is low, in Step 4, the molten material (fm) contained in the Tammann tube (22) drips down from the mouth part (222), and a balloon is not formed.

Example 1

[0139] 30 parts by mass of FA1, 10 parts by mass of FA4, 20 parts by mass of CS, and 30 parts by mass of BA as the glass-forming component, and 10 parts by mass of gadolinium (simple substance) as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0140] The components included in the present raw material formulation include gadolinium: 10% by mass, SiO.sub.2: 44% by mass, Al.sub.2O.sub.3: 11% by mass, CaO: 8% by mass, Fe.sub.2O.sub.3: 22% by mass, and others: 5% by mass. The masses of SiO.sub.2, Al.sub.2O.sub.3, CaO, Fe.sub.2O.sub.3, and other components in the glass-forming components as calculated from the blending ratio of each raw material, as well as the total mass ratio occupied by SiO.sub.2 and Al.sub.2O.sub.3 in the glass-forming components, the mass ratio of SiO.sub.2 with respect to the sum total of SiO.sub.2 and Al.sub.2O.sub.3 in the glass-forming components, the mass ratio occupied by Fe.sub.2O.sub.3 in the glass-forming components, and the total mass ratio occupied by SiO.sub.2 and Al.sub.2O.sub.3 in the final composition (inorganic fibers or inorganic flakes) are shown together in Table 2. Incidentally, in the subsequent tables, abbreviated names [S], [A], [C], and [F] will also be used for SiO.sub.2, Al.sub.2O.sub.3, CaO, and Fe.sub.2O.sub.3, respectively.

[0141] A fiberization test was carried out for this raw material formulation, and as a result, a yarn having a diameter of about 10 m was obtained. The obtained yarn had such a strength that the yarn would not be easily cut even when pulled by hand. Incidentally, in the following description, the term fiber may be used instead of yarn; however, they have the same meaning.

[0142] Furthermore, a flake processing test was carried out for this raw material formulation, and as a result, a balloon having a film thickness of about 800 nm was obtained. The balloon was crushed to obtain flakes.

[0143] No crystalline peaks are recognized in the X-ray diffraction (XRD) spectra of the fibers and the flakes, and the fibers and the flakes are amorphous. The above-described results are shown in Table 2. Incidentally, in the evaluation of amorphousness in the subsequent tables, the reference symbol A indicates that the sample is amorphous, and the reference symbol B indicates that crystalline peaks are recognized.

[0144] Furthermore, the abundance ratios (mol %) of elements were determined based on the component ratios (% by mass) of the final composition, and the values of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) were calculated (bottom row in Table 2).

Example 2

[0145] A raw material formulation was prepared in the same manner as in Example 1, except that samarium (simple substance) was used as the neutron shielding component, and a melt-spinning test and a flake processing test were carried out. The results are shown in Table 2. Satisfactory fibers and flakes were formed from the raw material formulation. Furthermore, the fibers and the flakes were amorphous. The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 2).

Example 3

[0146] A raw material formulation was prepared in the same manner as in Example 1, except that cadmium (simple substance) was used as the neutron shielding component, and a melt-spinning test and a flake processing test were carried out. The results are shown in Table 2. Satisfactory fibers and flakes were formed from the raw material formulation. Furthermore, both the fibers and flakes were amorphous. The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 2).

Comparative Example 1

[0147] 14 parts by mass of FA2, 44 parts by mass of FA5, 22 parts by mass of CS, and 20 parts by mass of BA as the glass-forming component were weighed, and a raw material formulation was prepared.

[0148] The components included in the present raw material formulation are SiO.sub.2: 51% by mass, Al.sub.2O.sub.3: 13% by mass, CaO: 8% by mass, Fe.sub.2O.sub.3: 22% by mass, and others: 7% by mass.

[0149] A melt-spinning test and a flake processing test were carried out for this raw material formulation. The results are shown in Table 2. Satisfactory fibers and flakes were formed from this raw material formulation. Furthermore, both the fibers and the flakes were amorphous.

[0150] Incidentally, since the obtained fibers and flakes do not include neutron shielding components, the relative neutron shielding rate with respect to lead has a very low value such as 3 (bottom row in Table 2).

TABLE-US-00002 TABLE 2 Reference Example Comparative Composition Abbreviated name, Name (lead) Example 1 Example 2 Example 3 Example 1 Raw material Glass-forming FA1 30 blending component FA2 14 ratio [parts by mass] FA4 10 FA5 44 CS 20 22 BA 30 20 Neutron Gd simple substance 10 radiation Sm simple substance 10 shielding Cd simple substance 10 component [parts by mass] Sum total [parts by mass] 100 Components Glass-forming SiO.sub.2 [S] 44 51 of final component Al.sub.2O.sub.3 [A] 11 13 composition [% by mass] Cao [C] 8 8 Fe.sub.2O.sub.3 [F] 22 22 Others 5 7 Subtotal [WG] 90 100 Neutron Gd element 10 radiation Sm element 10 0 shielding Cd element 10 component [% by mass] Mass ratio occupied by [S] + [A] in glass- 0.62 0.63 forming component Mass ratio of [S] with respect to [S] + [A] 0.80 0.80 in glass-forming component Mass ratio occupied by [F] in glass-forming 0.24 0.22 component Mass ratio occupied by [S] + [A] in final 0.55 0.63 composition Characteristics Spinnability A A A A Flake processability a a a Amorphousness Relative neutron radiation shielding rate 1 489 62 37 3 compared to lead (N/N.sub.Pb)

Example 4

[0151] 33 parts by mass of FA1, 11 parts by mass of FA2, 6 parts by mass of FA4, 22 parts by mass of CS, and 11 parts by mass of BA as the glass-forming component, and 17 parts by mass of gadolinium (simple substance) as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0152] The components included in the present raw material formulation are gadolinium: 17% by mass, SiO.sub.2: 41% by mass, Al.sub.2O.sub.3: 10% by mass, CaO: 6% by mass, Fe.sub.2O.sub.3: 20% by mass, and others: 6% by mass.

[0153] A melt-spinning test and a flake processing test were carried out for this raw material formulation. The results are shown in Table 3. Satisfactory fibers and flakes were formed from the raw material formulation. Furthermore, both the fibers and flakes were amorphous.

[0154] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 3).

Example 5

[0155] 70 parts by mass of FA5 as the glass-forming component and 30 parts by mass of gadolinium (simple substance) as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0156] The components included in the present raw material formulation are gadolinium: 30% by mass, SiO.sub.2: 42% by mass, Al.sub.2O.sub.3: 13% by mass, CaO: 3% by mass, Fe.sub.2O.sub.3: 8% by mass, and others: 6% by mass.

[0157] A melt-spinning test and a flake processing test were carried out for this raw material formulation. The results are shown in Table 3. Satisfactory fibers and flakes were formed from the raw material formulation. Furthermore, both the fibers and the flakes were amorphous.

[0158] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 3).

Example 6

[0159] 65 parts by mass of FA5 as the glass-forming component and 35 parts by mass of gadolinium (simple substance) as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0160] The components included in the present raw material formulation are gadolinium: 35% by mass, SiO.sub.2: 39% by mass, Al.sub.2O.sub.3: 12% by mass, CaO: 2% by mass, Fe.sub.2O.sub.3: 7% by mass, and others: 5% by mass.

[0161] A melt-spinning test and a flake processing test were carried out for this raw material formulation. The results are shown in Table 3. Satisfactory fibers and flakes were formed from the raw material formulation. Furthermore, both the fibers and the flakes were amorphous.

Example 7

[0162] 30 parts by mass of FA1, 10 parts by mass of FA2, 5 parts by mass of FA4, 20 parts by mass of CS, and 10 parts by mass of BA as the glass-forming component, and 25 parts by mass of gadolinium oxide (Gd.sub.2O.sub.3) as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0163] The components included in the present raw material formulation are gadolinium oxide: 25% by mass, SiO.sub.2: 37% by mass, Al.sub.2O.sub.3: 9% by mass, CaO: 6% by mass, Fe.sub.2O.sub.3: 18% by mass, and others: 4% by mass.

[0164] A melt-spinning test and a flake processing test were carried out for this raw material formulation. The results are shown in Table 3. Satisfactory fibers and flakes were formed from the raw material formulation. Furthermore, both the fibers and flakes were amorphous.

[0165] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 3).

Example 8

[0166] A raw material formulation was prepared in the same manner as in Example 7, except that 15 parts by mass of CS was used, and 30 parts by mass of gadolinium oxide (Gd.sub.2O.sub.3) was used.

[0167] The components included in the present raw material formulation are gadolinium oxide: 30% by mass, SiO.sub.2: 36% by mass, Al.sub.2O.sub.3: 9% by mass, CaO: 6% by mass, Fe.sub.2O.sub.3: 16% by mass, and others: 5% by mass.

[0168] A melt-spinning test and a flake processing test were carried out for this raw material formulation. The results are shown in Table 3. Satisfactory fibers and flakes were formed from the raw material formulation. Furthermore, both the fibers and flakes were amorphous.

[0169] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 3).

Example 9

[0170] 35 parts by mass of FA1, 5 parts by mass of FA2, 20 parts by mass of CS, and 5 parts by mass of BA as the glass-forming component, and 35 parts by mass of gadolinium oxide as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0171] The components included in the present raw material formulation are gadolinium oxide: 35% by mass, SiO.sub.2: 32% by mass, Al.sub.2O.sub.3: 8% by mass, CaO: 4% by mass, Fe.sub.2O.sub.3: 17% by mass, and others: 4% by mass.

[0172] A melt-spinning test and a flake processing test were carried out for this raw material formulation. The results are shown in Table 3. Satisfactory fibers and flakes were formed from the raw material formulation. Furthermore, both the fibers and flakes were amorphous.

[0173] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 3).

TABLE-US-00003 TABLE 3 Composition Abbreviated name Example 4 Example 5 Example 6 Example 7 Example 8 Example 9 Raw material Glass-forming FA1 33 30 30 35 blending component FA2 11 10 10 5 ratio [parts by mass] FA4 6 5 5 FA5 70 65 CS 22 20 15 20 BA 11 10 10 5 Neutron Gd simple substance 17 30 35 radiation Gd.sub.2O.sub.3 25 30 35 shielding component [parts by mass] Sum total [parts by mass] 100 100 100 100 100 100 Components Glass-forming SiO.sub.2 [S] 41 42 39 37 36 32 of final component Al.sub.2O.sub.3 [A] 10 13 12 9 9 8 composition [% by mass] Cao [C] 6 3 2 6 6 4 Fe.sub.2O.sub.3 [F] 20 8 7 18 16 17 Others 6 6 5 5 4 4 Subtotal [WG] 83 70 65 75 70 65 Neutron Gd simple substance 17 30 35 radiation Gd.sub.2O.sub.3 0.77 25 30 35 shielding component [% by mass] Mass ratio occupied by [S] + [A] in glass- 0.62 0.62 0.63 0.62 forming component Mass ratio of [S] with respect to [S] + [A] in 0.80 0.77 0.80 0.80 0.80 glass-forming component Mass ratio occupied by [F] in glass-forming 0.24 0.11 0.11 0.24 0.22 0.26 component Mass ratio occupied by [S] + [A] in final 0.51 0.54 0.51 0.46 0.44 0.40 composition Characteristics Spinnability A A A A A A Flake processability a a a a a a Amorphousness Relative neutron radiation shielding rate 863 1566 1883 1253 1561 1963 compared to lead (N/N.sub.Pb)

Example 10

[0174] 60 parts by mass of FA5 as the glass-forming component, and 40 parts by mass of gadolinium (simple substance) as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0175] The components included in the present raw material formulation are gadolinium: 40% by mass, SiO.sub.2: 36% by mass, Al.sub.2O.sub.3: 11% by mass, CaO: 2% by mass, Fe.sub.2O.sub.3: 6% by mass, and others: 5% by mass. Incidentally, the ratio (mass ratio) occupied by Fe.sub.2O.sub.3 in the glass-forming component is 0.11.

[0176] A melt-spinning test and a flake processing test were carried out for this raw material formulation. The results are shown in Table 4. Satisfactory yarns and flakes were formed from the raw material formulation. Furthermore, both the fibers and flakes were amorphous. The XRD spectrum is shown in FIG. 3.

[0177] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 4).

Comparative Example 2

[0178] A raw material formulation was prepared in the same manner as in Example 10, except that FA1: 30 parts by mass, FA4: 10 parts by mass, and BA: 20 parts by mass were used as the glass-forming component instead of FA5: 60 parts by mass.

[0179] The components included in the present raw material formulation are gadolinium: 40% by mass, SiO.sub.2: 33% by mass, Al.sub.2O.sub.3: 9% by mass, CaO: 5% by mass, Fe.sub.2O.sub.3: 9% by mass, and others: 4% by mass. Incidentally, the ratio (mass ratio) occupied by Fe.sub.2O.sub.3 in the glass-forming component is 0.15.

[0180] A melt-spinning test and a flake processing test were carried out for this raw material formulation. The results are shown in Table 4. Since the molten material of the present raw material formulation had low melt viscosity, a yarn could not be formed in the melt-spinning test. Similarly, also in the flake processing test, the melt viscosity of the molten material was too low, and a balloon could not be formed. Incidentally, in the XRD spectrum of the molten and solidified material, peaks originating from a crystalline phase were recognized (FIG. 3).

[0181] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 4).

Example 11

[0182] A raw material formulation was prepared in the same manner as in Example 10, except that gadolinium oxide: 40 parts by mass was used as the neutron shielding component instead of gadolinium simple substance: 40 parts by mass.

[0183] The components included in the present raw material formulation are gadolinium oxide: 40% by mass, SiO.sub.2: 36% by mass, Al.sub.2O.sub.3: 11% by mass, CaO: 2% by mass, Fe.sub.2O.sub.3: 6% by mass, and others: 5% by mass. Incidentally, the ratio (mass ratio) occupied by Fe.sub.2O.sub.3 in the glass-forming component is 0.11.

[0184] A melt-spinning test and a flake processing test were carried out for this raw material formulation. The results are shown in Table 4. Satisfactory fibers and flakes were formed from the raw material formulation. Furthermore, both the fibers and flakes were amorphous.

[0185] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 4).

Comparative Example 3

[0186] A raw material formulation was prepared in the same manner as in Example 10, except that FA1: 35 parts by mass, FA2: 5 parts by mass, CS: 13 parts by mass, and BA: 8 parts by mass were used as the glass-forming component instead of FA5: 60 parts by mass.

[0187] The components included in the present raw material formulation are gadolinium oxide: 40% by mass, SiO.sub.2: 31% by mass, Al.sub.2O.sub.3: 8% by mass, CaO: 4% by mass, Fe.sub.2O.sub.3: 14% by mass, and others: 3% by mass. Incidentally, the ratio (mass ratio) occupied by Fe.sub.2O.sub.3 in the glass-forming component is 0.23.

[0188] A melt-spinning test and a flake processing test were carried out for this raw material formulation. The results are shown in Table 4. Since the molten material of the present raw material formulation had low melt viscosity, a yarn could not be formed in the melt-spinning test. Similarly, also in the flake processing test, the melt viscosity of the molten material was too low, and a balloon could not be formed. Incidentally, from the XRD analysis, it was found that the molten material included a crystalline component.

[0189] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 4).

Example 12

[0190] 55 parts by mass of FA5 as the glass-forming component and 45 parts by mass of gadolinium oxide as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0191] The components included in the present raw material formulation are gadolinium oxide: 40% by mass, SiO.sub.2: 33% by mass, Al.sub.2O.sub.3: 10% by mass, CaO: 2% by mass, Fe.sub.2O.sub.3: 6% by mass, and others: 5% by mass. Incidentally, the ratio (mass ratio) occupied by Fe.sub.2O.sub.3 in the glass-forming component is 0.11.

[0192] A melt-spinning test and a flake processing test were carried out for this raw material formulation. The results are shown in Table 4. Satisfactory fibers and flakes were formed from the raw material formulation. Furthermore, both the fibers and flakes were amorphous.

[0193] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 4).

Comparative Example 4

[0194] 40 parts by mass of FA5 as the glass-forming component and 60 parts by mass of gadolinium oxide as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0195] The components included in the present raw material formulation are gadolinium oxide: 60% by mass, SiO.sub.2: 24% by mass, Al.sub.2O.sub.3: 7% by mass, CaO: 1% by mass, Fe.sub.2O.sub.3: 4% by mass, and others: 3% by mass. Incidentally, the ratio (mass ratio) occupied by Fe.sub.2O.sub.3 in the glass-forming component is 0.11.

[0196] A melt-spinning test and a flake processing test were carried out for this raw material formulation. The results are shown in Table 4. Since the molten material of the present raw material formulation had low melt viscosity, a yarn could not be formed in the melt-spinning test. Similarly, also in the flake processing test, the melt viscosity of the molten material was too low, and a balloon could not be formed. Incidentally, from the XRD analysis, it was found that the molten material included a crystalline component.

[0197] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 4).

TABLE-US-00004 TABLE 4 Comparative Comparative Comparative Composition Abbreviated name Example 10 Example 2 Example 11 Example 3 Example 12 Example 4 Raw material Glass-forming FA1 30 35 blending component FA2 5 ratio [parts by FA4 10 mass] FA5 60 60 55 40 CS 13 BA 20 8 Neutron Gd simple substance 40 40 radiation shielding component Gd.sub.2O.sub.3 40 40 45 60 [parts by mass] Sum total [parts by mass] 100 100 100 100 100 100 Components Glass-forming SiO.sub.2 [S] 36 33 36 31 33 24 of final component Al.sub.2O.sub.3 [A] 11 9 11 8 10 7 composition [% by mass] Cao [C] 2 5 2 4 2 1 Fe.sub.2O.sub.3 [F] 6 9 6 14 6 4 Others 5 4 5 3 5 3 Subtotal [WG] 60 60 60 60 55 40 Neutron Gd simple substance 40 40 0 0 0 0 radiation Gd.sub.2O.sub.3 0 0 40 40 45 60 shielding component [% by mass] Mass ratio occupied by [S] + [A] in glass- 0.77 0.69 0.77 0.65 0.77 0.77 forming component Mass ratio of [S] with respect to [S] + [A] 0.77 0.78 0.77 0.80 0.77 0.77 in glass-forming component Mass ratio occupied by [F] in glass-forming 0.11 0.15 0.11 0.23 0.11 0.11 component Mass ratio occupied by [S] + [A] in final 0.46 0.42 0.46 0.39 0.43 0.31 composition Characteristics Spinnability A C A C A C Flake processability a c a c a c Amorphousness X X X Relative neutron radiation shielding rate 2221 2214 2239 2321 2672 4359 compared to lead (N/N.sub.Pb)

[0198] From a comparison of Example 10 and Comparative Example 2 and a comparison of Example 11 and Comparative Example 3, in a case where the content of the neutron shielding component is more than 35% by mass, neither fibers nor flakes are obtained from the inorganic composition when the mass ratio occupied by Fe.sub.2O.sub.3 in the glass-forming component is 0.15 or more. In addition, in a case where the content occupied by the neutron shielding component in the composition is more than 50% by mass, it is already clear that neither fibers nor flakes can be obtained even when the mass ratio occupied by Fe.sub.2O.sub.3 in the glass-forming component is less than 0.15.

Examples 13 to 17 and Comparative Example 5

[0199] Similar tests were carried out using samarium simple substance and samarium oxide (Sm.sub.2O.sub.3) as the neutron shielding component. The results are shown together with the blending composition of the raw materials and the component composition of the final composition (Table 5).

[0200] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (bottom row in Table 5). In the same manner as in the case of using gadolinium simple substance and gadolinium oxide, satisfactory fibers and flakes were obtained even when samarium simple substance and samarium oxide were used (Examples 13 to 17). However, similarly to the case seen in Comparative Example 4, neither fibers nor flakes were obtained from the composition of Comparative Example 5 in which the content occupied by the neutron shielding component (samarium oxide) in the composition was more than 50% by mass.

TABLE-US-00005 TABLE 5 Comparative Composition Abbreviated name Example 13 Example 14 Example 15 Example 16 Example 17 Example 5 Raw material Glass- FA1 30 40 blending forming FA2 10 ratio component FA4 10 [parts by FA5 70 60 50 40 mass] CS 20 BA 30 30 Neutron Sm simple substance 10 20 radiation shielding component Sm.sub.2O.sub.3 30 40 50 60 [parts by mass] Sum total [parts by mass] 100 100 100 100 100 100 Components Glass- SiO.sub.2 [S] 44 42 42 36 30 24 of final forming Al.sub.2O.sub.3 [A] 11 11 13 11 9 7 composition component Cao [C] 8 9 3 2 2 1 [% by mass] Fe.sub.2O.sub.3 [F] 22 12 8 6 5 4 Others 5 6 6 5 4 3 Subtotal [WG] 90 80 70 60 50 40 Neutron Sm simple substance 10 20 radiation Sm.sub.2O.sub.3 30 40 50 60 shielding component [% by mass] Mass ratio occupied by [S] + [A] in 0.62 0.67 0.77 glass-forming component Mass ratio of [S] with respect to [S] + 0.80 0.79 0.77 [A] in glass-forming component Mass ratio occupied by [F] in glass- 0.24 0.15 0.11 forming component Mass ratio occupied by [S] + [A] in 0.55 0.53 0.54 0.46 0.39 0.31 final composition Characteristics Spinnability A A A A A C Flake processability a a a a a c Amorphousness X Relative neutron radiation shielding 62 121 184 272 383 525 rate compared to lead (N/N.sub.Pb)

[0201] In Examples 18 and 19 and Comparative Examples 6 to 9 shown below, the resistance to radiation deterioration was also evaluated for each of the compositions in addition to the evaluation of spinnability of the composition. The evaluation of the resistance to radiation deterioration was carried out by Positron Annihilation Lifetime Spectroscopy (PALS).

Example 19

[0202] 40 parts by mass of FA1, 10 parts by mass of FA2, 30 parts by mass of BA, and 5 parts by mass of CaCO.sub.3 (reagent) as the glass-forming component, and 15 parts by mass of gadolinium oxide as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0203] The components included in the present raw material formulation are gadolinium oxide: 15% by mass, SiO.sub.2: 35% by mass, Al.sub.2O.sub.3: 9% by mass, CaO: 18% by mass, Fe.sub.2O.sub.3: 9% by mass, and others: 14% by mass.

[0204] A melt-spinning test was carried out for this raw material formulation. The results are shown in Table 6. Satisfactory fibers were obtained from the raw material formulation. Furthermore, the fibers were amorphous.

[0205] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (Table 6).

[0206] Next, a molten and solidified material of the raw material formulation was finely pulverized, and the fine pulverization product was divided into a sample for radiation irradiation and a non-radiation-irradiated sample.

[0207] The sample for radiation irradiation was irradiated with radiation of about 1.45 gigagray (GGy) using an electron beam as a radiation source to obtain a radiation-irradiated sample.

[0208] Positron lifetime measurement was carried out for each of the radiation-irradiated sample and the non-radiation-irradiated sample obtained in this manner, by using the apparatus shown in FIG. 4. Sodium chloride in which a portion of sodium was substituted with an isotope of sodium, .sup.22Na, was used as a positron beam source. In FIG. 4, the positron beam source (31) has a flat plate shape that measures 10 mm on each of the four sides and is wrapped with a titanium foil (not shown in the diagram). A first scintillator (32a) for measuring gamma rays is provided below the positron beam source (31), and a first photomultiplier tube (33a) is connected to the first scintillator (32a). A first pulse height discriminator (34a) is connected to the first photomultiplier tube (33a). The signal caught by the first scintillator (32a) passes through the first photomultiplier tube (33a) and the first pulse height discriminator (34a) is inputted to a data processor (35) through a first channel (36a). The data processing unit (35) includes a digital oscilloscope (37). Here, the first pulse height discriminator (34a) transmits a signal to the data processing unit (35) when the first pulse height discriminator (34a) detects a -ray of 1.28 MeV, which is emitted when .sup.22Na undergoes -plus decay. By setting the digital oscilloscope (37), when a signal is inputted from the first channel (36a), the data processing unit (35) records the time (t0) and initiates time measurement at the same time.

[0209] A sample (S) to be submitted to the measurement of positron lifetime is accommodated in a sample support container (not shown in the diagram) holding a predetermined amount of a powder sample. A second scintillator (32b) is installed above the positron beam source (31) on which the sample (S) is placed. A second photomultiplier tube (33b) is connected to the second scintillator (32b). A second pulse height discriminator (34b) is connected to the second photomultiplier tube (33b). The signal caught by the second scintillator (32b) passes through the second photomultiplier tube (33b) and the second pulse height discriminator (34b) and is set to the data processor (35) through a second channel (36b). Here, the second pulse height discriminator (34b) sends a signal to the data processing unit (35) when the second pulse height discriminator (34b) detects a -ray of 0.511 MeV, which is emitted upon electron pair annihilation. The data processing unit (35) records the time of input from the second channel (36b).

[0210] The above-described measurement was continued for about 24 hours, the number of counts of the -ray of 0.511 MeV was accumulated with respect to time, and a positron lifetime spectrum (PALS spectrum) was obtained (FIG. 5). Since this annihilation time spreads due to the difference in the travel distances of positrons, the time spectrum has a peak top at the measurement initiation time (t0), and the number of counts gradually decreases with the passage of time. Here, the time at which the number of counts became 10.sup.3 with respect to the number of counts of the scintillator at the peak top time (t0) (normalized value: 1), was designated as the representative value (t1) of the annihilation time of the sample (hereinafter, the expression of the representative value of the annihilation time will be simply briefly referred to as annihilation time).

[0211] Similar measurement was also carried out for the radiation-irradiated sample, and the PALS spectrum was obtained. The normalized PALS spectrum almost overlapped with the PALS spectrum of the non-radiation-irradiated sample. Therefore, the ratio (t1/t1) of the annihilation time (t1) of the radiation-irradiated sample and the annihilation time (t1) of the non-radiation-irradiated sample is 1.0.

[0212] The test results in which the PALS spectra almost overlap even when the sample is irradiated with radiation and the value of t1/t1 is 1.0, indicate that the microstructure of the present inorganic composition almost hardly changes before and after irradiation with radiation, that is, the present inorganic composition has excellent resistance to radiation deterioration.

Example 18

[0213] 75 parts by mass of FA5 and 15 parts by mass of CaCO.sub.3 (reagent) as the glass-forming component, and 10 parts by mass of gadolinium oxide as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0214] The components included in the present raw material formulation are gadolinium oxide: 10% by mass, SiO.sub.2: 44% by mass, Al.sub.2O.sub.3: 14% by mass, CaO: 11% by mass, Fe.sub.2O.sub.3: 8% by mass, and others: 7% by mass.

[0215] A melt-spinning test was carried out for this raw material formulation. The results are shown in Table 6. Satisfactory fibers were obtained from the raw material formulation. Furthermore, the fibers were amorphous.

Example 19

[0216] 40 parts by mass of FA1, 10 parts by mass of FA2, 30 parts by mass of BA, and 5 parts by mass of CaCO.sub.3 (reagent) as the glass-forming component, and 15 parts by mass of gadolinium oxide as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0217] The components included in the present raw material formulation are gadolinium oxide: 15% by mass, SiO.sub.2: 35% by mass, Al.sub.2O.sub.3: 9% by mass, CaO: 18% by mass, Fe.sub.2O.sub.3: 9% by mass, and others: 14% by mass.

[0218] A melt-spinning test was carried out for this raw material formulation. The results are shown in Table 6. Satisfactory fibers were obtained from the raw material formulation. Furthermore, the fibers were amorphous.

[0219] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated (Table 6) in the same manner as in Example 1.

[0220] For a molten and solidified material, the PALS spectra of a non-radiation-irradiated sample and a radiation-irradiated sample were determined by the PALS method in the same manner as in Example 18. As a result, the PALS spectra of the non-radiation-irradiated sample (sample before irradiation with radiation) and the radiation-irradiated sample (sample after irradiation with radiation) almost overlapped (FIG. 5). Therefore, the ratio (t1/t1) of the annihilation time (t1) of the radiation-irradiated sample and the annihilation time (t1) of the non-radiation-irradiated sample is 1.0.

Comparative Example 6

[0221] 16 parts by mass of SiO.sub.2 (reagent), 4 parts by mass of Al.sub.2O.sub.3 (reagent), 2 parts by mass of Fe.sub.2O.sub.3 (reagent), 8 parts by mass of CaO (reagent), 1 part by mass of MgO (reagent), 1 part by mass of TiO.sub.2 (reagent), and 1 part by mass of K.sub.2CO.sub.3 (reagent) were weighed, and a raw material formulation was prepared.

[0222] The components included in the present raw material formulation are SiO.sub.2: 50% by mass, Al.sub.2O.sub.3: 12% by mass, CaO: 26% by mass, Fe.sub.2O.sub.3: 5% by mass, and others: 6% by mass.

[0223] Melt-spinning was attempted for this raw material formulation, and as a result, a yarn was obtained (Table 6). Incidentally, the molten material was amorphous.

[0224] For a molten and solidified material, the PALS spectra of a non-radiation-irradiated sample and a radiation-irradiated sample were determined in the same manner as in Example 18. As a result, changes in the PALS spectra of the non-radiation-irradiated sample and the radiation-irradiated sample were recognized (FIG. 6). That is, the annihilation time (t1) of the radiation-irradiated sample was shorter than the annihilation time (t1) of the non-radiation-irradiated sample. Specifically, the value of t1/t1 was 0.6.

[0225] From the fact that changes occurred in the PALS spectra of the non-radiation-irradiated sample and the radiation-irradiated sample, it is speculated that certain changes occurred in the microstructure of the sample when irradiated with radiation.

Comparative Example 7

[0226] 75 parts by mass of FA5 and 18 parts by mass of CaCO.sub.3 (reagent) as the glass-forming component, and 7 parts by mass of gadolinium oxide as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0227] The components included in the present raw material formulation are gadolinium oxide: 7% by mass, SiO.sub.2: 44% by mass, Al.sub.2O.sub.3: 14% by mass, CaO: 13% by mass, Fe.sub.2O.sub.3: 8% by mass, and others: 14% by mass.

[0228] Melt-spinning was attempted for this raw material formulation, and as a result, a satisfactory yarn was obtained. The obtained fiber was amorphous.

[0229] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (Table 6).

[0230] For a molten and solidified material, the PALS spectra of a non-radiation-irradiated sample and a radiation-irradiated sample were determined in the same manner as in Example 18. As a result, changes in the PALS spectra of the non-radiation-irradiated sample and the radiation-irradiated sample were recognized, in the same manner as shown in Comparative Example 6. However, the degree of change thereof was smaller than the degree of change shown in Comparative Example 6. The value of t1/t1 was 0.7.

Comparative Example 8

[0231] Tests were carried out in the same manner as in Comparative Example 7, except that the amount of CaCO.sub.3 (reagent) was changed to 17 parts by mass, and the amount of gadolinium oxide was changed to 8 parts by mass. The results are shown in Table 6.

[0232] For a molten and solidified material, the PALS spectra of a non-radiation-irradiated sample and a radiation-irradiated sample were determined in the same manner as in Example 18. As a result, changes in the PALS spectra of the non-radiation-irradiated sample and the radiation-irradiated sample were recognized, in the same manner as shown in Comparative Example 6. However, the degree of change thereof was much smaller than the degree of change shown in Comparative Example 7. The value of t1/t1 was 0.8.

Comparative Example 9

[0233] 35 parts by mass of FA5 and 5 parts by mass of H.sub.3BO.sub.3 (reagent) as the glass-forming component, and 60 parts by mass of gadolinium oxide as the neutron shielding component were weighed, and a raw material formulation was prepared.

[0234] Melt-spinning was attempted for this raw material formulation; however, a molten material just dripped down, and no yarn was obtained (Table 6).

[0235] Incidentally, from the XRD analysis, it was found that the molten material included a crystalline component.

[0236] The value of the relative neutron shielding rate with respect to lead (N/N.sub.Pb) was calculated in the same manner as in Example 1 (Table 6).

[0237] No changes were recognized in the PALS spectra of the composition caused by irradiation with radiation. The value of t1/t1 was 1.0.

TABLE-US-00006 TABLE 6 Comparative Comparative Comparative Comparative Composition Abbreviated name, Name Example 6 Example 7 Example 8 Example 18 Example 19 Example 9 Raw Glass-forming FA1 40 material component FA2 10 blending [parts by mass] FA5 75 75 75 35 ratio BA 15 CaCO.sub.3 [Reagent] 18 17 15 20 SiO.sub.2 [Reagent] 16 Al.sub.2O.sub.3 [Reagent] 4 Fe.sub.2O.sub.3 [Reagent] 2 CaO [Reagent] 8 MgO [Reagent] 1 TiO.sub.2 [Reagent] 1 K.sub.2CO.sub.3 [Reagent] 1 H.sub.3BO.sub.3 [Reagent] 5 Neutron shielding Gd.sub.2O.sub.3 0 7 8 10 15 60 component [parts by mass] Sum total [parts by mass] 32 100 100 100 100 100 Components Glass-forming SiO.sub.2 [S] 50 44 44 44 35 21 of final component Al.sub.2O.sub.3 [A] 12 14 14 14 9 6 composition [% by mass] Cao [C] 26 13 12 11 18 1 Fe.sub.2O.sub.3 [F] 5 8 8 8 9 4 Others 6 14 14 7 14 8 Subtotal [WG] 100 93 92 84 85 40 Neutron shielding Gd.sub.2O.sub.3 0 7 8 10 15 60 component [% by mass] Mass ratio occupied by [S] + [A] in glass- 0.62 0.62 0.63 0.69 0.52 0.68 forming component Mass ratio of [S] with respect to [S] + [A] 0.80 0.77 0.77 0.77 0.79 0.77 Mass ratio occupied by [F] in glass-forming 0.05 0.09 0.09 0.10 0.11 0.09 component Mass ratio occupied by [S] + [A] in final 0.58 0.58 0.58 0.61 0.45 0.27 composition Characteristics Spinnability A A A A A C Amorphousness X Relative neutron radiation shielding rate 2 299 344 400 686 4815 compared to lead (N/N.sub.Pb) Resistance to radiation deterioration (t1/t1) 0.6 0.7 0.8 1.0 1.0 1.0

[0238] FIG. 7 is a graph showing the relationship between the gadolinium oxide content in the composition and the value of t1/t1 (dimensionless), which can be called an index of the resistance to radiation deterioration, based on the results of Table 6. In a series of tests performed in Comparative Examples 6, 7, and 8 as described above, there were observed indications of improvement in the resistance to radiation deterioration as the content of the gadolinium oxide added to impart neutron shielding properties to the composition increases; however, an unexpected effect that when the content reaches 10% by mass or more, the composition is critically and completely resistant to radiation, is recognized.

[0239] Inorganic fibers were produced (sample I) from the inorganic composition of Example 18 (gadolinium oxide content: 10% by mass) by using a mass production facility. Similarly, inorganic fibers were produced (sample II) from the inorganic composition of Comparative Example 6 (gadolinium oxide content: 0% by mass). In addition, commercially available basalt fibers (sample III) and glass fibers (sample IV) were also prepared for comparison.

[0240] The above-described fiber samples from I to IV were arranged side by side in order on a test bench, and neutron radiographs were taken. In FIG. 8, sample I (gadolinium oxide content: 10% by mass), sample II (gadolinium oxide content: 0% by mass), sample III (basalt fibers), and sample IV (glass fibers) are shown in order from the left side in the upper row. The lower row of FIG. 8 shows neutron radiograph images obtained by simultaneously irradiating these samples with neutrons without changing the positions of the samples. In the diagram, from the left, (I), (II), (III), and (IV) correspond to the fiber samples from I to IV, respectively. From this, it is clearly shown that the fibers of sample I (gadolinium oxide content: 10% by mass) shield neutrons, while all the other fibers transmit neutrons.

INDUSTRIAL APPLICABILITY

[0241] The inorganic composition of the invention has neutron shielding properties and is therefore useful as a material for members that are exposed to neutrons. Furthermore, the inorganic composition of the invention can be easily processed into fibers or flakes. Therefore, when the inorganic composition is compositized with resins, rubber, cement, and other materials, the inorganic composition can not only impart neutron shielding properties to these, but also function as a reinforcing material of the above-described materials due to the shape or flakes. Fibers are processed into chopped strands, rovings, and fiber sheets according to conventional methods.

[0242] As mentioned above, when flakes formed from the inorganic composition of the invention are added to a thermoplastic resin, the flakes are oriented in layers in the resin molded article due to the shear force generated in the injection molding process of the thermoplastic resin, and as a result, a neutron shielding effect is effectively exhibited. Similarly, when flakes formed from the inorganic composition of the invention are added to a coating material (lining material), due to the shear force applied to the coating material (lining material) in a coating process by a brush, a roller, or the like, the flakes in the coating film tend to be oriented in layers along the coating film surface. As a result, the neutron shielding effect per unit mass is excellent as compared with powdered or granular additives.

[0243] Since the inorganic composition of the invention is also excellent in terms of the resistance to radiation deterioration, even when a member to be exposed to neutrons is exposed to neutrons for a long time period, the fibers or flakes included in the member to be exposed to neutrons do not deteriorate, and therefore, there is an advantage that the function as a reinforcing material of the member is maintained for a long time period.

[0244] A material into which the inorganic composition of the invention, or fibers and flakes thereof are incorporated has excellent neutron shielding properties. Therefore, the material is suitable as a material constituting a member to be irradiated with neutron beams. Representative examples of parts to be irradiated with neutron beams include facilities, equipment, and members in each field of nuclear power, aerospace, and medicine.

[0245] Examples of facilities, equipment, and members in the field of nuclear power include: [0246] facilities, equipment, and members for nuclear power generation, [0247] facilities, equipment, and members that prevent critical reactions in operations related to the extraction and storage of debris (molten nuclear fuel), [0248] facilities, equipment, and members for mining and treatment of uranium ore, [0249] facilities, equipment, and member for secondary processing treatment of nuclear fuel (conversion, concentration, reconversion, molding processing, and MOX production of nuclear fuel), [0250] facilities, equipment, and members for storage, treatment, and retreatment of spent nuclear fuel, [0251] facilities, equipment, and members for storage, treatment, and disposal of neutron radiation-exposed wastes, [0252] transport equipment and members for uranium ore, second processed products of nuclear fuel, spent nuclear fuel, or neutron radiation-exposed wastes, and [0253] other nuclear-related facilities, equipment, and members.

[0254] More specific examples of the above-described facilities, equipment, and members for nuclear power generation include nuclear reactor buildings (including research reactors and test reactors), reactor containment vessels, piping in nuclear reactor facilities, and robots for decommissioning treatment.

[0255] Examples of the facilities, equipment, and members in the field of aerospace include: [0256] space base buildings, space stations, artificial satellites, planetary exploration satellites, and spacesuits.

[0257] Examples of the facilities, equipment, and members in the field of medicine include: [0258] medical apparatuses that utilize particle beams.

[0259] The above-described usage examples are given only for the purpose of demonstrating the usefulness of the inorganic composition of the invention and are not intended to limit the scope of the invention.

Explanations of Letters or Numerals

[0260] 11 ELECTRIC FURNACE [0261] 12 TAMMANN TUBE [0262] 13 HANGING ROD [0263] 14 OPENING PART [0264] 15 FIBER [0265] D OUTER DIAMETER OF ELECTRIC FURNACE [0266] H HEIGHT OF ELECTRIC FURNACE [0267] d DIAMETER OF ELECTRIC FURNACE OPENING PART [0268] 21 CRUCIBLE [0269] 22 TAMMANN TUBE [0270] 221 OPENING PART [0271] 222 MOUTH PART [0272] 23 ELECTRIC FURNACE [0273] D1 DIAMETER OF CRUCIBLE [0274] H1 HEIGHT OF CRUCIBLE [0275] D2 DIAMETER OF TAMMANN TUBE [0276] H2 HEIGHT OF TAMMANN TUBE [0277] DIAMETER OF OPENING PART [0278] fp RAW MATERIAL FORMULATION, INORGANIC OXIDE [0279] FORMULATION [0280] fm MOLTEN MATERIAL, INORGANIC OXIDE MOLTEN MATERIAL [0281] fb BALLOON [0282] P LOAD PRESSURE [0283] 31 POSITRON BEAM SOURCE [0284] 32a SCINTILLATOR [0285] 32b SCINTILLATOR [0286] 33a PHOTOMULTIPLIER TUBE [0287] 33b PHOTOMULTIPLIER TUBE [0288] 34a PULSE HEIGHT DISCRIMINATOR [0289] 34b PULSE HEIGHT DISCRIMINATOR [0290] 35 DATA PROCESSING UNIT [0291] 36a FIRST CHANNEL [0292] 36b SECOND CHANNEL [0293] 37 DIGITAL OSCILLOSCOPE [0294] S SAMPLE

INORGANIC COMPOSITION AND FIBERS AND FLAKES THEREOF

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Abstract

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