EP1418593A1 - Neutron shielding material for subcritical maintenance and its production and applications - Google Patents

Abstract

A material, for neutron protection and maintenance of sub-criticality, comprises a vinylester resin-based matrix, one or more polyamides and an inorganic filler capable of slowing and absorbing neutrons. An Independent claim is included for a package for the transport, storage and or stocking of radioactive products comprising one or more screens formed from the above material.

Description

TECHNICAL AREA

The present invention relates to a neutron shielding and retaining material subcriticality, as well as a process for preparing this material and to the applications of said material.

The material according to the invention has the particularity of having a remarkable ability to slow down and absorb neutrons while having a particularly low density.

It is therefore likely to represent a material of choice for making screens neutrons in transport packaging, storage and / or storage of materials radioactive, and in particular assemblies of new nuclear fuels, i.e. not yet irradiated, like those composed of oxides based on plutonium, which emit more neutrons than gamma radiation.

STATE OF THE PRIOR ART

Materials intended to constitute neutron screens in packaging for the transport, storage and / or storage of nuclear fuels, must have some number of properties.

First, they should be able to slow down and capture very effectively neutrons, especially to be able to maintain subcriticality within these packages, that is to say to avoid that the neutrons which are formed there do not cause a nuclear chain reaction.

They must also present good resistance to aging at relatively high temperatures because the presence of nuclear fuels in packaging generates significant temperatures (from 150 ° C under normal conditions of transport).

They must also have a conductivity low thermal, but nevertheless sufficient to be able to dissipate the heat given off by nuclear fuels in packaging.

They must still have a good resistance to fire, which supposes that they are self-extinguishing, that is, they stop burning as soon as the flames are extinguished.

Finally, it is desirable that these materials have a relatively low density so that that their presence in packaging contributes to less possible to weigh them down.

So that materials are suitable for slow down and capture the neutrons it should they are highly hydrogenated and that they contain a inorganic compound, for example boron-based, clean to ensure neutron capture.

• FR-A-2 546 331 [1] propose un matériau de blindage neutronique qui comprend des billes de polyéthylène ou de polypropylène retenues dans un liant composé d'une résine polyester ou d'un ciment alumineux, d'un hydrate stable tel que du trihydrate d'alumine, et d'un composé boré (colémanite ou carbure de bore).
• EP-A-0 628 968 [2] décrit un matériau de blindage neutronique obtenu à partir d'un mélange entre une résine thermodurcissable et une charge inorganique de haute densité. La résine thermodurcissable peut être une résine phénol, époxy, crésol, xylène, urée ou encore polyester insaturé, tandis que la charge inorganique peut être un métal lourd (plomb, tungstène, ...) , un lanthanide (europium, gadolinium, ...) ou de l'uranium.
• GB-A-1 049 890 [3] décrit des articles moulés et des revêtements de protection neutronique qui sont obtenus à partir d'un mélange copolymérisable d'un polyester insaturé et d'un monomère éthylénique, dans lequel, soit la partie acide du polyester est en partie dérivée de l'acide borique, soit le monomère éthylénique est en partie un ester d'acide borique, soit encore le polyester insaturé et/ou le monomère éthylénique contiennent de l'hydrure de bore ou du chlorure de bore.

So, for example:

• FR-A-2 546 331 [1] provides a neutron shielding material which comprises polyethylene or polypropylene beads retained in a binder composed of a polyester resin or an aluminous cement, of a stable hydrate such as alumina trihydrate, and a boron compound (colemanite or boron carbide).
• EP-A-0 628 968 [2] describes a neutron shielding material obtained from a mixture between a thermosetting resin and an inorganic filler of high density. The thermosetting resin can be a phenol, epoxy, cresol, xylene, urea or even unsaturated polyester resin, while the inorganic filler can be a heavy metal (lead, tungsten, etc.), a lanthanide (europium, gadolinium, etc.). .) or uranium.
• GB-A-1 049 890 [3] describes molded articles and neutron protection coatings which are obtained from a copolymerizable mixture of an unsaturated polyester and an ethylenic monomer, in which either the acid part of the polyester is partly derived from boric acid, or the ethylenic monomer is partly an ester of boric acid, or else the unsaturated polyester and / or the ethylenic monomer contain boron hydride or boron chloride.

These materials do not give entirely satisfaction. In particular, they have an outfit insufficient thermal aging due to the nature of the hydrogenated polymers which constitute them, and their density is too high.

So, for example, the material described in EP-A-0 628 968 has a density at least equal to 2.

STATEMENT OF THE INVENTION

As part of his research, the Applicant has been led to develop a material which combines excellent shielding properties neutronics and maintaining subcriticality, with self-extinguishing and thermal properties very satisfactory, especially in terms of resistance to thermal aging.

This material includes a matrix based a vinylester resin such as a resin of the type novolak, in which are dispersed, on the one hand, a hydrogenated inorganic compound capable of slowing down neutrons like alumina hydrate, and, on the other hand, an inorganic boron compound capable of capturing them like zinc borate.

Its remarkable properties can be explained in particular by the fact that vinylester resins, in addition to to be rich in hydrogen and therefore able to very effectively slow down neutrons, have a low thermal conductivity, doubled with excellent thermal stability.

However, it has a density at least equal to 1.6 and which is generally between 1.65 and 1.9.

The Inventors have therefore set themselves the goal to provide a material which, while presenting properties comparable to those of this base material a vinylester resin, has a lower density than him.

This object is achieved by the invention which offers a neutron shielding material and maintenance of subcriticality, which material includes a matrix based on a vinyl ester resin, at least one polyamide and an inorganic filler capable of slowing and absorb the neutrons.

The inventors have, in fact, found that by incorporating, in a matrix based on a resin vinylester, a compound chosen from the family of polyamides - most of which represent have both a relatively high content of hydrogen, low density (on the order of 1 to 1.2 according to polyamides) and a melting temperature high - in conjunction with an inorganic load able to slow down and absorb neutrons it is possible to obtain a material that has properties just as interesting as those of said material based on a vinylester resin, or even superior in terms of neutron shielding and maintenance of subcriticality, but whose density is is between 1.3 and 1.6.

Within the meaning of the present invention, the term “polyamide” denotes both a homopolyamide resulting from the reaction between amine and acid groups belonging to the same molecule, as well as a copolyamide resulting from the reaction between amine and acid groups belonging to different molecules.

According to the invention, the polyamide can also be an aliphatic, semi-aromatic polyamide and aromatic.

However, it is preferred to use a polyamide aliphatic, the aliphatic polyamides being, in richer in hydrogen than polyamides semi-aromatic and aromatic and therefore more even contribute to the slowing down of neutrons by the material.

Preferably, the polyamide is chosen from the group consisting of polyamides 11 (C ₁₁ H ₂₁ ON), polyamides 12 (C ₁₂ H ₂₃ ON) and polyamides 6-12 (C ₁₂ H ₂₂ O ₂ N ₂ ), which have a density respectively equal to 1.04, 1.02 and 1.07 and a melting temperature respectively equal to 187, 178 and 212 ° C.

These polyamides are available in the form powders of different particle sizes, for example with the company ATOFINA which markets them under Rilsan® D (polyamide 11) and Orgasol® brands (polyamides 6, 12, 6-12).

Also, according to the invention, the choice of polyamide is not only guided by its composition chemical (this conditioning its content hydrogen), its density and its melting temperature, but also by its particle size as a function of conditions for using the material, and in particular of the viscosity that we want to give to this material before polymerization of the vinylester resin.

So, for example, Rilsan® polyamides D80, which are in the form of fine powders (Ø = 75-85 µm) allow to obtain mixtures of lower viscosity than those obtained using Orgasol®, which are ultra-fine powders (Ø = 5-60 µm), and which are therefore easier to pour into a mold.

The vinylester resin entering the constitution of the material can be of different types.

Preferably, a resin is used vinylester resulting from the addition reaction of a carboxylic acid with an epoxy resin.

This carboxylic acid can in particular be acrylic acid or methacrylic acid, the latter being preferred, since richer in hydrogen, while that the epoxy resin can have a pattern bisphenol A or type macromolecular novolak.

So the vinylester resin is preferably chosen from the group consisting of epoxyacrylate and epoxymethacrylate resins from bisphenol A type, epoxyacrylate resins and novolak type methacrylates and resins epoxyacrylates and epoxymethacrylates based on bisphenol A halogenated.

dans laquelle R représente un atome d'hydrogène ou un groupe méthyle.The epoxyacrylate and epoxymethacrylate resins of bisphenol A type correspond to the following formula (I):

in which R represents a hydrogen atom or a methyl group.

dans laquelle R représente un atome d'hydrogène ou un groupe méthyle.The novolak type epoxyacrylate or epoxymethacrylate resins correspond to the following formula (II):

in which R represents a hydrogen atom or a methyl group.

dans laquelle R représente un atome d'hydrogène ou un groupe méthyle.As for the halogenated bisphenol A epoxyacrylate or epoxymethacrylate resins, they correspond, for example, to the following formula (III):

in which R represents a hydrogen atom or a methyl group.

dans laquelle R représente un atome d'hydrogène ou un groupe méthyle, tandis que U représente un groupe uréthanne.As a variant, it is also possible to use, in a material according to the invention, a non-epoxy vinyl ester resin, obtained from an isophthalic polyester and a urethane and corresponding, for example, to the following formula (IV):

wherein R represents a hydrogen atom or a methyl group, while U represents a urethane group.

Preferably, the vinyl ester resin is a epoxyacrylate or epoxymethacrylate type resin novolak.

According to the invention, the material also includes an inorganic filler which is able to slow down and absorb neutrons.

This inorganic charge includes, preferably at least one hydrogenated inorganic compound and at least one inorganic boron compound.

Advantageously, the hydrogenated inorganic compound is chosen from the group consisting of alumina hydrates and magnesium hydroxide (Mg (OH) ₂ ), while the inorganic boron compound is chosen from the group consisting of boric acid (H ₃ BO ₃ ), colemanite (Ca ₂ O ₁₄ B ₆ H ₁₀ ), zinc borates (Zn ₂ O _14.5 H ₇ B ₆ , Zn ₄ O ₈ B ₂ H ₂ , Zn ₂ O ₁₁ B ₆ ), boron carbide (B ₄ C), boron nitride (BN) and boron oxide (B ₂ O ₃ ).

Preferably, the hydrogenated inorganic compound is the alumina hydrate of formula Al ₂ O ₃ , while the inorganic boron compound is zinc borate of formula Zn ₂ O _14.5 H ₇ B ₆ or boron carbide .

The material according to the invention can further understand an anti-removal agent such as a poly (vinyl acetate) suitable for preventing it from shrink during polymerization of the resin vinylester.

He can still understand a charge hydrogenated organic such as melamine, for strengthen its self-extinguishing properties.

In accordance with the invention, the quantity of hydrogenated inorganic compound is chosen so that, taking into account the quantities of hydrogen also provided by the vinylester resin and the polyamide, the material preferably has an atomic hydrogen concentration of between approximately 4,5.10 ²² and 6,5.10 ²² at / cm ³ .

Similarly, the amount of inorganic boron compound is chosen so that the material preferably has an atomic boron concentration of between about 8.10 ²⁰ and 3.10 ²¹ at / cm ³ .

Very satisfactory materials have been obtained from mixtures in which the resin vinylester and polyamide respectively represent from 30 to 45% and from 10 to 30% by mass of the total mass constituted by this resin, this polyamide and the filler inorganic capable of slowing down and absorbing neutrons.

The material according to the invention can be prepared by curing a mixture containing its different constituents, this hardening resulting from polymerization of the vinyl ester resin.

• mélanger la résine vinylester, le polyamide, la charge inorganique capable de ralentir et d'absorber les neutrons, avec au moins un accélérateur de polymérisation de la résine,
• ajouter à ce mélange au moins un catalyseur de polymérisation de la résine,
• dégazer le mélange sous vide,
• couler le mélange obtenu dans un moule, et
• le laisser durcir dans le moule.

Also, the subject of the invention is also a process for preparing this material, which comprises the following steps:

• mixing the vinyl ester resin, the polyamide, the inorganic filler capable of slowing down and absorbing the neutrons, with at least one accelerator for polymerizing the resin,
• add to this mixture at least one catalyst for polymerizing the resin,
• degas the mixture under vacuum,
• pour the mixture obtained into a mold, and
• let it harden in the mold.

Commercially available vinylesters available are in the form of solutions, including the solvent is a vinyl solvent, and the amount of solvent present in these resins is usually sufficient for the mixture of different components of the material is easy to make and has a suitable consistency.

However, it is possible to add, if necessary, vinyl solvent when mixing of said constituents.

As examples of vinyl solvents likely to be used, there may be mentioned styrene, vinyltoluene, divinylbenzene, methylstyrene, methyl acrylate, methyl methacrylate or a allylic derivative such as diallyl phthalate.

Preferably, the same solvent is used than that of vinylester resin, and in particular the styrene, this solvent being, in fact, the most frequently used in the preparation of resins vinylester.

The accelerators and catalysts of polymerization are chosen from the compounds usually used to obtain polymerization vinyl ester resins.

The accelerators can be, in in particular, divalent cobalt salts such as naphthenate or cobalt octoate, and amines aromatic tertiary such as dimethylaniline, dimethylparatoluidine and diethylaniline.

• des peroxydes dérivés de cétone comme le peroxyde de méthyléthylcétone, le peroxyde d'acétylacétone, le peroxyde de méthylisobutylcétone, le peroxyde de cyclohexanone et l'hydroperoxyde de cumène ;
• des peroxydes de diacyle, par exemple le peroxyde de benzoyle éventuellement en combinaison avec des amines tertiaires aromatiques telles que la diméthylaniline, la diéthylaniline et la diméthylparatoluidine ; et
• des peroxydes de dialkyle tels que le peroxyde de dicumyle et le peroxyde de ditertiobutyle.

The catalysts can be, in particular, organic peroxides, for example:

• peroxides derived from ketone such as methyl ethyl ketone peroxide, acetylacetone peroxide, methyl isobutyl ketone peroxide, cyclohexanone peroxide and cumene hydroperoxide;
• diacyl peroxides, for example benzoyl peroxide optionally in combination with aromatic tertiary amines such as dimethylaniline, diethylaniline and dimethylparatoluidine; and
• dialkyl peroxides such as dicumyl peroxide and ditertiobutyl peroxide.

You can also add one or more several additives such as an inhibitor of polymerization of the resin, a surfactant or an anti-removal agent.

As examples of inhibitors of usable polymerization, there may be mentioned acetylacetone and tertiobutylcathecol.

The method according to the invention can be implemented implemented in the following manner.

Vinylester resin, polyamide, inorganic charge capable of slowing down and absorbing neutrons (for example, inorganic compounds hydrogenated and borated) and the polymerization accelerator are mixed at room temperature until obtaining a perfectly homogeneous mixture.

The polymerization catalyst is added and, after homogenization, the resulting mixture is subjected to vacuum degassing (less than 0.01 MPa).

Ideally, the viscosity of this mixture does not must not exceed 300 Poises, so that it is easy to pour into a mold.

After degassing, the mixture is poured into the desired mold where it hardens, polymerization of the vinylester resin, and transforms into an insoluble material. This polymerization is of the radical type and it is strongly exothermic. Curing time can vary according to the casting conditions (temperature, rate of catalyst, accelerator, ...). So the time gel can be adjusted by varying the percentages of catalyst and accelerator. Time gel ranges from 20 minutes to 2 hours.

According to the invention, the mold used for the hardening of the mixture can consist of a compartment for transport, storage packaging and / or storage of radioactive products. This packaging may in particular include a plurality of peripheral compartments in which the mixed.

The invention also relates to a transport, storage and / or storage packaging of radioactive material which includes at least one screen formed of the material as previously described.

Preferably, this packaging is intended for transport new nuclear fuel such as fuel composed of a plutonium-based oxide.

Other features and benefits of the invention will appear better on reading the description which follows, which relates to an example of production of a material according to the invention and demonstration of its properties, and which is given to illustrative and non-limiting title, with reference to attached drawing.

BRIEF DESCRIPTION OF THE DRAWING

Figure 1 shows the evolution during of the time of mass loss (expressed in percentages) of a material according to the invention when this is maintained at 160 ° C (curve A) and at 170 ° C (curve B), as well as that observed for a material of reference maintained at 160 ° C (curve C).

DETAILED PRESENTATION OF AN EMBODIMENT OF A MATERIAL ACCORDING TO THE INVENTION

• 40% en masse, rapportée à la masse de ce mélange, d'une résine de type novolaque (Derakane Momentum® D470-300 - DOW CHEMICAL) ;

• 20% en masse, rapportée à la masse de ce mélange, d'un polyamide 11 (Rilsan® D 80 - ATOFINA) ;

• 38% en masse, rapportée à la masse de ce mélange, d'un hydrate d'alumine Al₂O₃ (SH 150/01 - PECHINEY) ;

• 2% en masse, rapportée à la masse de ce mélange, d'un carbure de bore de granulométrie égale comprise entre 45 et 75 µm (WACKER) ; et

• 1% en masse, rapportée à la masse du mélange, d'un accélérateur de polymérisation (NL 49P - AKZO).

A mixture is prepared comprising:

• 40% by mass, based on the mass of this mixture, of a novolak type resin (Derakane Momentum® D470-300 - DOW CHEMICAL);

• 20% by mass, based on the mass of this mixture, of a polyamide 11 (Rilsan® D 80 - ATOFINA);

• 38% by mass, based on the mass of this mixture, of an alumina hydrate Al ₂ O ₃ (SH 150/01 - PECHINEY);

• 2% by mass, based on the mass of this mixture, of a boron carbide of equal particle size between 45 and 75 μm (WACKER); and

• 1% by mass, based on the mass of the mixture, of a polymerization accelerator (NL 49P - AKZO).

1% by mass is added to this mixture, based on the mass of the mixture, of a catalyst polymerization (Butanox® M50 - AKZO).

Vacuum degassing is then carried out of the mixture for 3 minutes, then we pour this mixture in a mold consisting of a packaging compartment used to transport nuclear fuels.

The gel time is 25 minutes at 20 ° C.

• la densité de ce matériau selon la technique classique de pesée dans l'air/pesée dans l'eau,

• ses teneurs en hydrogène et en bore,

• sa température de transition vitreuse (Tg) par analyse enthalpique différentielle (DSC 30 - METTLER), en utilisant une montée en température de 10°C/min,

• son coefficient de dilatation thermique (α) par TMA 40 (METTLER), en utilisant une montée en température de 10°C/min,

• sa chaleur spécifique (Cp) par calorimétrie, pour des températures allant de 40 à 180°C, et

• sa conductivité thermique (λ) pour des températures comprises entre 20 et 170°C.

We measure:

• the density of this material according to the conventional technique of weighing in air / weighing in water,

• its hydrogen and boron contents,

• its glass transition temperature (Tg) by differential enthalpy analysis (DSC 30 - METTLER), using a temperature rise of 10 ° C / min,

• its coefficient of thermal expansion (α) by TMA 40 (METTLER), using a temperature rise of 10 ° C / min,

• its specific heat (Cp) by calorimetry, for temperatures ranging from 40 to 180 ° C, and

• its thermal conductivity (λ) for temperatures between 20 and 170 ° C.

The results of these measurements are presented in Table 1.

• 32% en masse, rapportée à la masse de ce mélange, de la résine vinylester de type novolaque Derakane Momentum® 470-300,

• 62% en masse, rapportée à la masse de ce mélange, de l'hydrate d'alumine SH 150/01, et

• 6% en masse, rapportée à la masse de ce mélange, d'un borate de zinc Zn₂O_14,5H₇B₆ (Firebrake ZB-BORAX),

auquel ont été ajoutés 0,9% en masse, par rapport à la masse de la résine, de l'accélérateur NL 49P et 1,5% en masse, par rapport à la masse de la résine, du catalyseur Butanox® M50. Matériaux Matériau de l'invention Matériau de référence Densité 1,43 1,79 Teneur en hydrogène • % massique 6,80 4,80 • [C] atomique (at/cm³) 5,47.10²² 5,1.10²² Teneur en bore • % massique 1,45 0,89 • [C] atomique (at/cm³) 1,21.10²¹ 8,92.10²⁰ Tg (°C) 131 130 α (K^-1) • avant Tg 131.10^-6 37.10^-6 • après Tg ND 109.10^-6 Cp (J/g.K) • minimale 1,37 1,07 • maximale 2,15 1,65 λ (W/m. K) • minimale 0,47 0,80 • maximale 0,58 0,85 This Table 1 also presents, for comparison, the density, the hydrogen and boron contents, the glass transition temperature (Tg), the coefficient of thermal expansion (α), the specific heat (Cp) and the thermal conductivity ( λ) of a material hereinafter called "reference material" and resulting from hardening (25 minutes at 20 ° C) of a mixture comprising:

• 32% by mass, based on the mass of this mixture, of the vinyl ester resin of the Novolak type Derakane Momentum® 470-300,

62% by mass, based on the mass of this mixture, of alumina hydrate SH 150/01, and

• 6% by mass, based on the mass of this mixture, of a zinc borate Zn ₂ O _14.5 H ₇ B ₆ (Firebrake ZB-BORAX),

to which were added 0.9% by mass, relative to the mass of the resin, of the NL 49P accelerator and 1.5% by mass, relative to the mass of the resin, of the Butanox® M50 catalyst. Materials Material of the invention Reference material Density 1.43 1.79 Hydrogen content •% by mass 6.80 4.80 • [C] atomic (at / cm ³ ) 5.47.10 ²² 5.1.10 ²² Boron content •% by mass 1.45 0.89 • [C] atomic (at / cm ³ ) 1.21.10 ²¹ 8.92.10 ²⁰ Tg (° C) 131 130 α (K ^-1 ) • before Tg 131.10 ^-6 37.10 ^-6 • after Tg ND 109.10 ^-6 Cp (J / gK) • minimal 1.37 1.07 • maximum 2.15 1.65 λ (W / m. K) • minimal 0.47 0.80 • maximum 0.58 0.85

Table 1 shows that the material according to the invention has a density significantly lower than that of the reference material which does not contain polyamide (1.43 versus 1.79).

It also has contents in hydrogen and boron significantly higher than those of the reference material.

So, although lighter, its performance in terms of neutron shielding and maintaining subcriticality are superior.

Tests of thermal aging of the material according to the invention are also carried out by maintaining samples of this material measuring 35 × 25 × 95 mm ³ in two ovens heated to 160 ° C. and 170 ° C. respectively for 5 months and monitoring the loss of mass of these materials. samples over time.

The results of these tests are given in FIG. 1 (curves A and B) whose ordinate axis represents the loss of mass of the material, expressed in percentages, while the abscissa axis represents time, expressed in days. Also shown in this figure is the change in mass loss observed over time by maintaining samples of the reference material, also measuring 35 × 25 × 95 mm ³ in an oven heated to 160 ° C. (curve C).

FIG. 1 shows that the material according to the invention undergoes a significantly less mass loss over time than the reference material, even when it is maintained at a higher temperature (170 ° C. versus 160 ° C.) . Its thermal stability is therefore greater than that of the latter.

We conduct behavior tests at fire by placing blocks for half an hour material according to the invention 240 mm in diameter on 60 mm thick, either directly in contact with the flame of a torch having a temperature of 800 ° C, i.e. in contact with a 1 mm steel sheet thick which is brought into contact with the flame of the blowtorch.

In both cases, the self-extinguishing material according to the invention is immediate after removal of the torch.

BIBLIOGRAPHY

[1] FR-A-2 546 331

[2] EP-A-0 628 968

[3] GB-A-1 049 890

Claims (18)

Neutron protection material and maintenance of subcriticality including a matrix with base of a vinylester resin, at least one polyamide and an inorganic charge capable of slowing down and absorb neutrons. Material according to claim 1, in which the polyamide is an aliphatic polyamide. Material according to claim 1 or the claim 2, in which the polyamide is chosen among polyamides 11, polyamides 12, polyamides 6-12 and their mixtures. Material according to any one of previous claims, wherein the resin vinylester is chosen from epoxyacrylate resins and bisphenol A type epoxymethacrylates, the resins epoxyacrylates and epoxymethacrylates of the novolak type, epoxyacrylate and epoxymethacrylate resins based of halogenated bisphenol A and the resins obtained from an isophthalic polyester and a urethane. Material according to any one of previous claims, wherein the resin vinylester is an epoxyacrylate resin or novolak type epoxymethacrylate. Material according to any one of previous claims, in which the charge inorganic capable of slowing down and absorbing neutrons includes at least one inorganic compound hydrogenated and at least one inorganic boron compound. Material according to claim 6, in which the hydrogenated inorganic compound is selected from the group consisting of alumina hydrates and magnesium hydroxide. Material according to claim 6 or the claim 7, wherein the inorganic compound of boron is selected from the group consisting of acid boric, colemanite, zinc borates, carbide boron, boron nitride and boron oxide. Material according to any one of claims 6 to 8, in which the hydrogenated inorganic compound is alumina hydrate of formula Al ₂ O ₃ . Material according to any one of claims 6 to 9, in which the inorganic boron compound is zinc borate of formula Zn ₂ O _14.5 H ₇ B ₆ or boron carbide. Material according to any one of claims 6 to 10, having an atomic hydrogen concentration is between approximately 4.5 × ^{10 22} and 6.5 × ^{10 22} at / cm ³ . Material according to any one of claims 6 to 11, having an atomic concentration of boron is between approximately 8.10 ²⁰ and 3.10 ²¹ at / cm ³ . Material according to any one of previous claims, wherein the resin vinylester represents from 30 to 45% by mass of the mass total constituted by this resin, the polyamide and the inorganic charge capable of slowing down and absorbing neutrons. Material according to any one of previous claims, wherein the polyamide represents from 10 to 30% by mass of the total mass constituted by the vinylester resin, this polyamide and the inorganic charge capable of slowing down and absorbing neutrons. Material according to any one of previous claims having a density between 1.3 and 1.6. Process for the preparation of a material as defined in any one of Claims 1 to 15, comprising the following steps: mixing the vinyl ester resin, the polyamide, the inorganic filler capable of slowing down and absorbing the neutrons, with at least one accelerator for polymerizing the resin, add to this mixture at least one catalyst for polymerizing the resin, degas the mixture under vacuum, pour the mixture obtained into a mold, and let it harden in the mold. Method according to claim 16, in which the mold consists of a compartment of a transport, storage and / or storage packaging radioactive products. Transport and storage packaging and / or radioactive material storage, including at least one screen formed from the material as defined in any one of claims 1 to 15.

Images