阅读说明：本技术 用于长寿命的低到高水平放射性废弃物的容器 (Container for long-life low to high level radioactive waste ) 是由 帕特里斯·斯唐热尔 于 2018-04-05 设计创作，主要内容包括：本发明包括用于放射性废弃物的容器,该容器包括：钢制外壁；钢制内壁；位于两个钢制壁之间的铅层；钢制基部；钢制盖；位于容器内部的一定体积的石英砂；至少部分地被一定体积的石英砂涂覆/围绕/覆盖的至少一个内部接收器/匣子/盒；以及位于接收器内部的放射性废弃物。内部容器可以由钢制成,并且可以包含低水平放射性废弃物。替代性地,接收器可以由陶瓷材料制成,并且可以包含高水平放射性废弃物。在一个优选的实施方式中,容器包括内部搁架,内部接收器被放置在该内部搁架中。(The invention comprises a container for radioactive waste, comprising: a steel outer wall; a steel inner wall; a lead layer located between the two steel walls; a steel base; a steel cover; a volume of quartz sand located inside the vessel; at least one internal receiver/cartridge/box at least partially coated/surrounded/covered by a volume of quartz sand; and radioactive waste located inside the receiver. The inner container may be made of steel and may contain low levels of radioactive waste. Alternatively, the receiver may be made of a ceramic material and may contain high levels of radioactive waste. In a preferred embodiment, the container includes an internal shelf in which the internal receiver is placed.)

1. A container for radioactive waste, comprising:

steel outer wall

Inner wall made of steel

Lead layer between two steel walls

Steel bottom

Steel cap

A volume of quartz sand inside the container

At least one inner vessel at least partially coated with quartz sand

And radioactive waste, the radioactive waste being inside the vessel.

2. The container according to claim 1, characterized in that the thickness of the quartz sand layer between the vessel and the inner steel wall is at least 2 cm.

3. A container according to claim 1 or 2, wherein the outer wall comprises a pressure relief valve.

4. The container according to one of claims 1 to 3, wherein the inner vessel is made of stainless steel.

5. The container of claim 4, wherein the inner vessel contains a low level of radioactive waste.

6. Container according to one of claims 1 to 3, characterized in that the inner vessel is ceramic.

7. The container of claim 6, wherein the inner vessel contains highly radioactive waste.

8. Container according to one of the preceding claims, characterized in that the cover comprises an outer steel wall, an inner steel wall and a layer of lead between the two steel walls.

9. Container according to one of the preceding claims, characterized in that the bottom comprises an outer steel wall, an inner steel wall and a layer of lead between the two steel walls

10. The container of one of claims 1 to 3, wherein the inner vessel comprises a removable cap.

11. The container according to one of the preceding claims, characterized in that it comprises an internal shelf comprising one or more compartments in which one or more vessels are arranged.

12. The container of claim 11, wherein the internal shelf includes one or more doors that provide access to the compartment.

13. A container according to claim 11 or 12, wherein the internal shelf comprises one or more centering means and/or one or more gripping means.

14. The container according to one of claims 11 to 13, characterized in that the internal shelf has one or more holes.

15. Container according to one of the preceding claims, wherein the steel is stainless steel, preferably 316L-section steel.

16. The container of at least one of the preceding claims, further comprising a plastic layer covering the radioactive waste in the inner container.

17. The container of one of the preceding claims, further comprising a rubber enclosure covering the outer wall.

Technical Field

The present invention relates to the field of storage of long-lived radioactive waste. More particularly, the invention relates to containers for storing radioactive waste of low to high levels and long life.

Background

Radioactive waste is any radioactive material that can no longer be recovered or reused by humans.

Nuclear waste has very different sources and properties. These nuclear wastes are, for example, elements contained in spent fuel of nuclear power plants other than uranium and plutonium contained therein, radioactive elements for medical or industrial use, or substances with which radioactive elements have come into contact.

Two parameters make it possible to understand the risks they present:

radioactivity reflects the toxicity of the waste, including its potential impact on humans and the environment.

Lifetime helps to define the duration of a potential hazard.

90% of the radioactive waste is low level of short-lived radioactive waste. The selection and management was made decades ago by building industrial-scale surface storage centers.

For the remaining 10% — medium to high level of long-lived radioactive waste, no choice has been made for long-term management. Currently, industry stores them safely and for decades on the earth's surface in specially constructed buildings at their production site.

Waste management is defined as follows:

advanced separation and conversion of wastes, the purpose of which is to sort and convert certain long-lived wastes into other less toxic and shorter-lived wastes. This reduces the long-term hazard of waste.

Storage in deep geological formations, the purpose of which is to develop underground storage facilities and techniques, focusing on concepts that allow reversibility.

The long-term surface and underground packaging and storage processes, the purpose of which is to develop the radioactive waste package and its long-term storage conditions, ensure the protection of human beings and the environment with a solution complementary to the one already existing, making it possible to further protect the waste.

Radioactive waste is classified according to two criteria.

a) Their activity, which is the number of nuclear decays that occur inside them per second. For a material with a mass of 1kg, the activity is measured in beckler (beckerel, becker) (1Bq ═ 1 decay per second).

There are some examples here:

1kg of rainwater: about 1Bq (natural radioactivity)

1kg of granite soil: about 10,000Bq (natural radioactivity)

1kg of uranium ore: about 10⁵Bq (Natural radioactivity)

1kg of freshly discharged spent fuel: about 10¹⁴Bq。

Activity decreased with time. After 10 years, the fuel activity decreased by about 6 times.

b) Their radioactive decay cycle, or simply their "cycle", is by definition the time required for the activity of a substance to halve.

The half-life does not depend on the quality of the material under consideration. Each pure radionuclide has a well-known cycle with values that can range from less than a thousandth of a second (e.g., polonium 214: 0.16ms) through all intermediate values (iodine 131: 5 days, cesium 137: 30 years, plutonium 239: 24,000 years, uranium 235: 700 trillions, etc.) to billions of years (e.g., uranium 238: 45 billions).

If the substance is mixed, the longest of all the radionuclides present is taken as the value for the radioactive cycle.

The radionuclide is converted into another nucleus by decay, called "offspring"; the mother nucleus is either stable, or is also radioactive and decays again.

The initial short-lived core is likely to have long-lived offspring. This long-lived offspring is then the cycle of those we retain.

According to both the "activity" and "period" criteria, the classification following activity reflects the technical precautions that must be taken in terms of radioprotection; ranking according to period reflects duration of hazard

With respect to the activity criteria, it can be said that the waste has:

"very low activity" if its activity level is lower than one hundred beckler per gram (of the order of natural radioactivity)

"low activity" if its activity level is between several tens of beckler per gram and several hundreds of thousands of beckler per gram and its content of radionuclides is sufficiently low that protection is not required during ordinary handling and transport operations.

"average activity" if its activity level is about one million to one billion becker per gram (at 1MBq/gr to GBq/gr).

"high activity", if its activity level is about several billion beckler per gram (GB/gr), for which the specific power is about one watt per kilogram, hence the name "hot" waste.

With respect to the cycle criteria, it can be said that the waste has:

"very short life", if its cycle is less than 100 days, (this allows its management by radioactive disintegration, which after a few years is disposed of as a common industrial waste).

"short life" if its radioactivity comes mainly from radionuclides with a period of less than 31 years (this ensures that it disappears on a historical scale of centuries)

"long life" if it contains a large amount of radionuclides with a period greater than 31 years (this requires containment and dilution management compatible with geological time scales)

Typically, after ten times the half-life of the radionuclide, its activity has been divided by 1024, which enables it to progress from one active class to another. Thus, after 310 years, the "medium level short life" waste became at most the "low level short life" waste and it was going to fall into the "very low activity" category for three more centuries.

Other classification criteria relate to the chemical risk and physicochemical properties of the waste. Radioisotopes are more dangerous because they are highly radioactive, chemically toxic and easily transferred to the environment.

Radioactive waste requiring detailed and specific safeguards is high-level long-lived (HLLL waste). If you remain exposed to such waste for too long, the waste is often active enough to cause burns.

HLLL waste is primarily derived from spent fuel from nuclear power plants.

For convenience, and due to the severity of the consequences of high levels of waste on humans, it is now imperative to build radiation protection of such high levels of waste on the basis of geological containment devices, according to preventive principles. This radioactive waste will be stored in deep geological layers and in a permanent manner. However, despite its radioactivity remaining significant for hundreds of thousands or even millions of years, it will be the case, independently of the fact, that such waste will over time transform into "low-level long-life" waste, and therefore no longer impose such precautions. Furthermore, to date, nothing has been available to ensure the sealing of the container, whatever it is, and rock stability over such long periods. As a result, the radioactivity will inevitably rise to the surface by uncontrolled contamination of important elements (water, soil, etc.) over a very large area.

The alternative option of storing HLLL waste "underground", i.e. at a depth of, for example, no more than 5m underground, and at a monitored location, allows easy access to the waste in case of future recycling.

In an alternative option for long-term storage underground, the risk that natural elements may pose to the storage means used must be taken into account.

Fire is a very destructive natural element and the means of storing HLLL waste underground must be able to withstand fire, at least temporarily.

Document WO 2011/026976 discloses a radioactive waste package comprising two layers covering the waste. The package comprises: an outer layer comprising a mixture of liquefied micronized plastic and micronized iron oxide powder; an inner layer of ceramic material. The outer layer is 2-3 mm. The outer layer absorbs radiation from the outside. The package may also include an additional plastic coating to protect against water. The outer layer is radiation and heat resistant, but it must not be fire resistant.

Steel storage tanks are also well known and widely available on the market in various forms. A can, which is commonly used for long-term storage, comprises a bottom, an outer wall and a lid, and means for closing the lid on the outer wall. The inner lead wall blocks some of the gamma rays from the waste. However, such cans do not withstand high temperatures.

Subject matter of the invention

The object of the present invention is to increase the safety of radioactive waste containers, and more particularly their resistance to high temperatures, in preparation for their storage on the surface or underground and for the associated fire risks.

Disclosure of Invention

According to the invention, this object is achieved by a radioactive waste container comprising: a steel outer wall; a steel inner wall; a lead layer located between the two steel walls; a steel bottom; a steel cover; a volume of quartz sand located inside the vessel; at least one inner vessel/cartridge/inner box at least partially covered, coated, surrounded, covered by a volume of quartz sand; and radioactive waste located inside the container.

Fire safety products must demonstrate reaction to a fire (non-flammable) and fire resistance (stable over a period of time). The steel does not ignite and the fire resistance of the steel wall increases with its thickness. In the present invention, the container includes an outer wall and a lead layer, as in the case of the existing can. It is characterized by that its internal steel wall is contacted with lead layer on one side and is contacted with quartz sand layer on another side, and the quartz sand layer is contacted with vessel wall. Confining the lead in the space between the double steel walls ensures good radiation protection even at temperatures above the melting point of lead.

The quartz sand layer and the lead layer will increase the resistance to high temperatures and will ensure the integrity of the container even at very high temperatures.

This surprising effect comes from the fact that: the lead and quartz sand sandwiched between the outer and inner steel walls and between the inner wall and the wall of the vessel will slowly melt, absorbing a large supply of heat energy. The temperature of the layer of lead, respectively the sand, which is partly in the molten state, partly in the solid state, does not rise above the melting temperature of the lead, respectively the quartz sand, as long as it remains in the solid state. There will be two temperature levels, the first at the lead melting temperature and the second at the silica sand melting temperature.

As a result, even at very high temperatures, the lead layer and the quartz sand layer will increase the temperature resistance over time and will ensure the integrity of the container.

Depending on the purity of the lead, the lead has a melting temperature of about 320 ℃ and a boiling temperature of about 1700 ℃. The silica sand has a melting temperature of 1300-1600 c and a boiling temperature of about 2000 c depending on the purity of the silica sand.

According to an advantageous mode of the invention, the thickness of the lead layer is between 25mm and 50 mm. The layer of quartz sand between the vessel and the inner steel wall preferably has a thickness of at least 2cm, preferably at least 3 cm. The maximum thickness of the sand layer is preferably less than 10cm, more preferably less than 8cm, and in particular less than 6 cm.

According to an advantageous embodiment, the outer wall comprises a pressure relief valve. The valve will allow evacuation of gas from the melting/boiling of lead contained in the space between the double steel walls.

The inner vessel is preferably stainless steel. The stainless steel inner vessel will not melt until a melting temperature of 1535 c is reached.

The stainless steel inner container may contain low levels of radioactive waste.

According to another preferred embodiment, the inner vessel is ceramic. Ceramic inner vessels are of great interest due to their resistance at temperatures of 1400 ℃.

The ceramic inner vessel may contain low levels of radioactive waste.

According to an advantageous embodiment, the cover comprises an outer steel wall, an inner steel wall and a layer of lead contained between the two steel walls. According to an embodiment, the bottom comprises an outer steel wall, an inner steel wall and a layer of lead contained between the two steel walls. The cover and base so manufactured can, if desired, block a portion of the gamma radiation waste.

The inner vessel may comprise a removable cap. The inner vessel with the cap will completely isolate the radioactive waste.

The container may include an internal shelf having one or more compartments in which one or more vessels are positioned. The rack facilitates the arrangement of several vessels within the container. The interior shelf may include one or more doors that provide easy access to the compartment.

The internal shelf preferably comprises one or more centering means and/or one or more gripping means. Additionally, the internal rack may include one or more holes to allow sand to fill the space between the vessel and the rack.

According to another preferred embodiment, the steel is stainless steel, preferably 316L steel. Alternatively, the composition of the stainless steel may be a composition of other stainless steels used in the nuclear industry or in another industry, for example in the marine field or in the field of safety domestic closures.

According to an advantageous embodiment, the container further comprises a plastic layer covering the radioactive waste in the inner container. The plastic layer blocks an additional portion of the radioactive radiation.

The container preferably includes an outer rubber capsule covering the outer wall.

Drawings

Further characteristics and features of the present invention will become apparent from the following detailed description of some advantageous embodiments, which is presented by way of example with reference to the accompanying drawings. These figures show:

FIG. 1: is a cross-sectional view of a container according to the invention and in a first embodiment.

FIG. 2: is a cross-sectional view of a container according to the invention and in a second embodiment.

Detailed Description

Fig. 1 illustrates a container 10 for radioactive waste according to a first embodiment of the present invention. The container 10 for radioactive waste comprises: a steel outer wall 12; a steel inner wall 14; a lead layer 16 contained between the two steel walls 12 and 14; a steel bottom 18; a steel cover 20; a volume of quartz sand 22 located inside the vessel; and at least one inner vessel/cartridge/inner box 24 at least partially covered, coated, surrounded, covered by a volume of quartz sand 22 (indicated by a cross in the image)₁And 24₂. Radioactive waste 26 is located inside the vessel 24.

The inner wall 14, bottom 18 and lid 20 of the container 10 mean that, once assembled, the inner wall, bottom 18 and lid 20 of the container form the inner enclosure of the waste barrier 26. The inner enclosure defines a vessel 24₁And 24₂An inner space in which the waste 26 and the silica sand 22 are accommodated.

The steel base 18 is the wall that receives the vessel, and the outer wall 12 and inner wall 14 extending from the base 18 to the lid 20 surround the container 24₁And 24₂. The bottom forms a circular profile, which may alternatively form an oval, square or any polygonal shape. The outer and inner peripheral walls and the cover may have corresponding shapes or different shapes.

The inner wall 14 and the outer wall 12 may be made, for example, by welding two pre-rounded steel plates. The inner wall 14 and the outer wall 12 are welded at their lower edges to a steel bottom 18. Then, molten lead or lead alloy is poured in advance between the inner wall and the outer wall to form the lead layer 16. In the case of melting, the lead layer 16 does not diffuse within the container. Further, the base 18 may be flat or may include a particular shape, such as for the container 24₁And 24₂Positioning of the container/containers.

The outer wall has a circular cross-section with an outer diameter between 500mm and 1000 mm. The height of the container is between 800mm and 1500mm, depending on the height between the bottom and the lid.

The thickness of the inner wall 14 and the outer wall 12 is between 3mm and 10mm and the thickness of the lead layer 16 is between 25mm and 50 mm.

The thickness of the steel base 18 and the steel cover may be equal to more than twice, for example three times, the value of the thickness of the inner wall 14 and the outer wall 12.

The container 10 includes a ring 19 for securing and attaching a steel cover 20 to the upper ends of the outer wall 12 and the inner wall 14. The fixing ring 19 comprises holes for receiving bolts for fixing the cover through corresponding holes in the steel cover 20.

Quartz sand refers to silica sand with trace amounts of different elements such as Al, Li, B, Fe, Mg, Ca, Ti, Rb, Na, OH. The silica sand has a vitrification characteristic of being melted and then hardened. Quartz sand with a low melting point will be chosen. The volume of glass so formed may also block some of the radioactive radiation (e.g., using a pre-mix of quartz sand and a radiation absorbing material).

The outer wall 12 includes a pressure relief valve 40. To evacuate the gases that are discharged in the event of melting of the layer of lead 16.

The container 10 also comprises a shelving unit 50 or shelf/display comprising means for receiving two vessels 24₁And 24₂One or more stacked compartments 52₁And 52₂. Each compartment includes a door (not shown) that allows easy access to the interior of the compartment.

The internal shelf 50 includes: a bottom wall 53 in contact with the bottom 18 of the container 10; an upper wall 54; a cylindrical wall 56 extending between the lower wall 53 and the upper wall 54; and an intermediate wall 58 forming a support between the lower wall 52 and the upper wall 54.

First container 24₁Positioned on the bottom wall 52 of the internal shelf 50. Second container 24₂Resting on the intermediate wall 58. The side wall 56 includes a number of holes or apertures 60.

The internal shelf 50 is positioned inside the container prior to the quartz sand. Apertures 60 in the side walls 56 of the internal shelf 50 allow quartz sand to be transferred to the compartment 52₁And 52₁In order to surround and access the deviceDish 24₁And 24₂. Depending on the arrangement of the holes in the internal shelf 50, the sand may also cover the vessel 24₁And 24₂. It should be noted that the sand may also be pre-placed in the container 24₁Below (c). Alternatively, the internal shelf 50 may include vertical/horizontal/diagonal mounts and brackets connected to the mounts; thus, the quartz sand may surround/cover the vessel by passing through the mount and the carrier.

The internal shelf 50 is made of stainless steel. The internal shelf 50 includes a second upper wall 54 'and a plumbing plate 70 positioned between the two upper walls 54 and 54'.

Inner vessel 24₁And 24₂Including a removable cap 28₁And 28₂And for connecting 30₁And 30₂Securing/flanging/clamping/screwing from removable cap to vessel 24₁And 24₂The apparatus of (1).

Inner vessel 24₁And 24₂Including centering means and/or one or more means for gripping/hooking/affixing an eyelet (not shown), for example, on the cover 20.

In this first embodiment, the container 10 comprises two ceramic inner vessels 24₁And 24₂Preferably made of ACA997 type ceramics, more preferably of the special ceramic ACS 99,8LS 172. With its cap 28₁And 28₂Vessel 24 of₁And 24₂Is between 250mm and 300 mm. Vessel 24₁And 24₂Is between 10L and 20L and withstands temperatures up to 1400 ℃.

Is placed in a vessel 24₁And 24₂The waste 26 in (a) is highly radioactive. In particular, such an embodiment is intended for the storage of long-lived medium to high level radioactive wastes, and in particular for the storage of non-recoverable final wastes containing fission products and minor actinides, nuclear fuel ashes.

Further, the container 10 includes an outer rubber/plastic/silicone capsule 80 covering the outer wall 12. The outer rubber capsule 80 is shown partially at the lower region of the container 10 on the image. The outer rubber capsule 80 is made by immersing the container 10 in a bath of liquefied rubber. The outer capsule 80 will prevent the container from being degraded by water.

Fig. 2 illustrates a second embodiment of the container 10 seen in connection with fig. 1. They will have in common the features described in connection with the first embodiment of fig. 1. The reference numerals of fig. 2 are used for corresponding elements in fig. 1, but for the second embodiment illustrated in fig. 2, these numbers are increased by 100. Specific reference numerals are used for specific elements, and these numbers are between 100 and 200.

In this second embodiment, the container comprises a single inner vessel 124. The inner vessel 124 is placed in a single compartment 152 of the inner rack 150. The inner vessel 124 is made of stainless steel. The height of the inner vessel 124 with its lid 128 is between 500mm and 1000 mm. The inner vessel 124 has a capacity of between 50L and 350L.

Waste 126 located in the inner vessel 124 is weakly radioactive. For example, waste consists of and has a half-life of less than 100 days: the metallic structure of the fuel elements resulting from the operation of the reactor; a used glove; protective clothing; an irradiated tool; a housing; a connector; radioactive mining residues, which can cause chemical toxicity problems if uranium is present with other additional toxic products such as lead, arsenic, mercury, etc.; radioactive waste from the medical sector.

In the embodiment of the invention presented herein, the container 100 further comprises a plastic layer 190, preferably a low density polymer, covering the radioactive waste in the inner container 124. The plastic may be pre-liquefied and mixed with the load and/or may be derived from several low/high density polymers.

Illustration of the drawings

10. 100 container

12. 112 steel outer wall

14. 114 steel inner wall

16. 116 lead layer

18. 118 bottom

19. 119 Ring

20. 120 cover

22. 122 volume of quartz sand

24₁、24₂124 inner vessel

26. 126 radioactive waste

28₁、28₂128 removable cap

30₁、30₂130 connecting device

40. 140 pressure relief valve

50. 150 internal resting means

52₁、52₂152 compartment

53. 153 lower wall

54. 154 upper wall

54', 154' second upper wall

56. 156 cylindrical wall

58 intermediate wall

60. 160 holes

70. 170 lead plate

80. 180 outer envelope