阅读说明：本技术 一种核燃料后处理中溶液贮罐的临界安全控制方法 (Critical safety control method for solution storage tank in nuclear fuel post-treatment ) 是由 李云龙 易璇 邵增 霍小东 杨海峰 于 2019-09-23 设计创作，主要内容包括：本发明属于核安全控制技术领域,涉及一种核燃料后处理中溶液贮罐的临界安全控制方法。所述的控制方法是在所述的溶液贮罐中分多层隔开水平布置中子毒物板,并在每层中子毒物板上开孔,以保证所述的溶液贮罐中的溶液可以正常流通。利用本发明的核燃料后处理中溶液贮罐的临界安全控制方法,能够利用中子毒物更好的进行核燃料后处理中溶液贮罐的临界安全控制,并使该方法具有一定的可扩展性。(The invention belongs to the technical field of nuclear safety control, and relates to a critical safety control method of a solution storage tank in nuclear fuel post-treatment, which is characterized in that neutron poison plates are horizontally arranged in the solution storage tank in a multi-layer separated mode, and holes are formed in each layer of the neutron poison plates to ensure that the solution in the solution storage tank can normally circulate.)

The critical safety control method for solution storage tank in the nuclear fuel after-treatment of 1, kinds is characterized by that in the described solution storage tank several layers of horizontally-spaced neutron poison plates are set, and every layer of neutron poison plate is equipped with a hole so as to ensure that the solution in the described solution storage tank can be normally flowed.

2. The control method according to claim 1, characterized in that: the solution storage tank is cylindrical, cubic or hexagonal.

3. The control method according to claim 1, characterized in that: the cross section of each layer of neutron poison plate is the same as that of the solution storage tank, and the cross section area is slightly smaller.

4. The control method according to claim 1, characterized in that: the neutron poison plate is made of neutron absorbing material selected from B₄Boron-containing polyethylene with 5-40% of C by mass and B₄ or more of boron-aluminum alloy, gadolinium and cadmium with the C content of 15-35 percent by mass.

5. The control method according to claim 1, characterized in that: the diameter range of the open holes on each layer of neutron poison plate is 1-8cm, and the distance between the open holes is 15-35 cm.

6. The control method according to claim 1, characterized in that: the center distance between two adjacent layers of the neutron poison plates is 1-20 cm.

7. The control method according to claim 1, characterized in that: the corresponding openings of each layer of neutron poison plate are aligned along the vertical direction.

8. The control method according to claim 1, characterized in that: the corresponding holes of each layer of neutron poison plate are staggered along the vertical direction.

9. The control method as set forth in claim 1, wherein said solution tank is further provided with thin neutron poisons on an outer wall thereof.

Technical Field

The invention belongs to the technical field of nuclear safety control, and relates to a critical safety control method for a solution storage tank in the post-treatment of nuclear fuels.

Background

The nuclear fuel after-treatment is an important component of closed nuclear fuel circulation in China, the process mainly comprises first-stage shearing and dissolving treatment, co-decontamination and separation treatment, and plutonium line and uranium line treatment processes, wherein the co-decontamination and separation, plutonium line and uranium line treatment processes mainly extract valuable nuclides from spent fuel dissolving liquid.

At present, when the amount of the solution for storing high-concentration uranium plutonium is small, a ring groove is mostly adopted, but the ring groove has the defects of large volume, low storage capacity and the like, and cannot meet the requirement of high processing capacity.

Regarding critical safety control by using neutron poison, reports exist in the prior art, for example, chinese patent application 201410271524.4 discloses a critical safety control method of a dissolver in which annular solid neutron poisons are arranged in a partitioned manner, chinese patent application 201410271775.2 discloses a critical safety control method of a dissolver in which discrete solid neutron poisons are arranged, and chinese patent application 201410323481.X discloses an arrangement structure of neutron poisons in solution storage tanks, but they do not relate to a critical safety control method of a solution storage tank in nuclear fuel reprocessing.

Disclosure of Invention

The invention aims to provide a critical safety control method for solution storage tanks in nuclear fuel post-treatment, which can better utilize neutron poison to carry out critical safety control on the solution storage tanks in the nuclear fuel post-treatment and has the expandability of .

In order to achieve the purpose, in a basic embodiment, the invention provides a critical safety control method of nuclear fuel post-treatment solution storage tanks, wherein the control method is that neutron poison plates are horizontally arranged in the solution storage tanks in a plurality of layers in a separated mode, and holes are formed in each layer of the neutron poison plates so as to ensure that the solution in the solution storage tanks can normally flow.

The invention arranges plate neutron poison in the solution storage tank, which makes the distribution of the neutron poison in the storage tank more uniform, increases the neutron absorption effect of the neutron poison, opens holes in the neutron poison plate to make the solution flow normally, meanwhile, arranges thin-layer neutron poison outside the storage tank to reduce the reactivity of the storage tank, can adjust the position of the opening hole in the neutron poison plate, makes the opening holes of different neutron poison plates not aligned in the storage tank, and is more beneficial to critical safety.

In preferred embodiments, the present invention provides a method for critical safety control of nuclear fuel reprocessing solution storage tanks wherein said solution storage tanks are cylindrical, cubic or hexagonal prismatic in shape.

In preferred embodiments, the present invention provides a method for critical safety control of solution tanks in the reprocessing of nuclear fuels of species wherein each of said neutron poison plates has a cross-sectional shape that is the same as the cross-sectional shape of said solution tank and a slightly smaller cross-sectional area.

In preferred embodiments, the present invention provides a method for critical safety control of solution tanks in the reprocessing of nuclear fuels of species, wherein said neutron poison plate is made of a neutron absorbing material selected from the group consisting of B₄Boron-containing polyethylene with 5-40% of C by mass and B₄ or more of boron-aluminum alloy, gadolinium, cadmium and other materials with the C content of 15-35 percent by mass.

In preferred embodiments, the present invention provides a method for critical safety control of solution tanks in the reprocessing of nuclear fuels of species wherein the openings in each neutron poison plate have a diameter in the range of 1 to 8cm and an interpore distance in the range of 15 to 35 cm.

In preferred embodiments, the present invention provides a method for critical safety control of solution tanks in the reprocessing of nuclear fuels of species, wherein the center-to-center spacing between adjacent neutron poison plates is between 1 and 20 cm.

In preferred embodiments, the present invention provides a method for critical safety control of solution tanks in the reprocessing of nuclear fuels of species in which the corresponding openings in the neutron poison plates of each layer are vertically aligned.

In preferred embodiments, the present invention provides a method for critical safety control of solution tanks in the reprocessing of nuclear fuels of species in which the corresponding openings in the neutron poison plates of each layer are vertically offset.

In preferred embodiments, the present invention provides a method for critical safety control of nuclear fuel reprocessing solution storage tanks wherein said solution storage tanks are further provided with a thin layer neutron poison on the outside wall thereof.

The method has the advantages that by using the method for controlling the critical safety of the solution storage tank in the nuclear fuel post-treatment, the critical safety control of the solution storage tank in the nuclear fuel post-treatment can be better performed by using neutron poison, and the method has the expandability of .

By adopting the technical scheme of the invention, the solution storage tank in nuclear fuel post-treatment can store uranium plutonium solution with higher concentration under the condition of ensuring the critical safety requirement according to the arrangement condition, the opening size and the neutron poison type of the neutron poison plate, and meanwhile, the critical control method can be expanded according to different storage tank shapes.

Drawings

FIG. 1 is a perspective view of an exemplary neutron poison plate used in the critical safety control method for solution tanks in nuclear fuel reprocessing according to the present invention.

Fig. 2 is an axial sectional view of fig. 1.

FIG. 3 is a longitudinal cross-sectional view of a solution tank for nuclear fuel reprocessing in which the corresponding openings in each of the neutron poison plates are vertically aligned according to an embodiment.

FIG. 4 is a longitudinal cross-sectional view of a solution tank for nuclear fuel reprocessing according to an embodiment wherein the corresponding openings in each of the neutron poison plates are vertically offset.

Detailed Description

A further embodiment of the present invention is described below with reference to the drawings.

As shown in fig. 3 and 4, a cylindrical tank is taken as an example, wherein neutron poison plates 1 are horizontally arranged at intervals in multiple layers (the neutron poison plates 1 are arranged in the tank at intervals of ), a gap 3 is formed between the neutron poison plates 1 and the outer wall 4 of the tank, a solution 2 is arranged between the neutron poison plates 1 and in the gap 3, and a tank outer layer neutron poison layer 5 is arranged outside the outer wall 4 of the tank, the ratio of the thickness of the neutron poison plate 1 to the distance between the centers of two adjacent neutron poison plates 1 can be 0.3 at minimum, the distance of the gap 3 is 0.1-6cm, and the thickness of the outer layer neutron poison layer 5 is 0.1-1 cm.

The neutron poison plate 1 is made of a neutron absorbing material selected from B₄Boron-containing polyethylene with 5-40% of C by mass and B₄ or more of boron-aluminum alloy, gadolinium and cadmium with the C content of 15-35% by mass, if the neutron absorption material has poor corrosion resistance, the neutron poison plate 1 can be coated in the form of an additional cladding.

The neutron poison layer 5 in the outer layer has a reducing effect on effective multiplication factors of the storage tank, and the neutron leakage rate of the storage tank can be reduced in the aspect of .

The structure of the disc-shaped neutron poison plate 1 is shown in figures 1 and 2, a plurality of openings 6 are arranged on each layer of the neutron poison plate 1, the diameter range of each opening 6 is 1-8cm, the distance between the openings is 15-35cm, so that the solution 2 in a solution storage tank can normally circulate, the diameter and the distance between the openings are mainly related to the components of the stored feed liquid, the used neutron poison material and the center distance between two adjacent layers of the neutron poison, when the concentration of the stored feed liquid is low or the absorption capacity of the neutron poison is strong or the center distance between two adjacent layers of the neutron poison is short, the diameter of the opening can be increased, the distance between the openings can be decreased, otherwise, the diameter of the openings is decreased, and the distance between the openings is increased. In fig. 3, the corresponding openings 6 of each layer of neutron poison plate 1 are aligned in the vertical direction; in fig. 4, the corresponding openings 6 of each layer of neutron poison plate 1 are vertically offset.

The present example takes a cylindrical tank as an example, and the tank profile and the shape of the neutron poison plate 1 can be modified for a cubic, hexagonal prismatic tank, while the other dimensions are unchanged. Meanwhile, the size of the storage tank is not limited, and when the radial distance of the storage tank is increased, only the radial size of the neutron poison plate 1 needs to be increased; when the axial distance of the storage tank is increased, the number of the neutron poison plates 1 is increased, and the neutron poison plates 1 are arranged in the axial direction at the same interval.

Through the design of the critical safety control of the high-concentration uranium plutonium solution storage tank, the upper limit of the uranium plutonium concentration of the storable feed liquid can be obviously improved. When the neutron poison plate 1 is set to be B3 cm thick₄The boron-containing polyethylene with the C content of 20 percent has the opening 6 with the diameter of 5cm, the distance between the centers of two adjacent openings 6 is 22cm, the distance between the centers of two adjacent neutron poison plates 1 is 10cm, the gap 3 is 5cm, and the thickness of the neutron poison layer 5 on the outer layer is 0.5cm, so that the storable feed liquid volume accounts for about 75 percent of the volume of the storage tank, the ratio is higher, and meanwhile, the maximum plutonium concentration can reach 100g/L when the plutonium nitrate feed liquid is stored. Therefore, under the critical safety control design of the storage tank, neutron poison is distributed uniformly, the neutron poison is utilized sufficiently, the neutron absorption effect is obvious, the material liquid accounts for a high proportion, and the storable uranium plutonium has high concentration.

The above only describes the arrangement form of the neutron poison plate 1, and the changes such as providing the support member, appropriately changing the poison structure to meet the arrangement form, and inclining the tank outer wall to provide the step for placing the neutron poison plate, etc. adopted to realize the arrangement form do not depart from the essence of the present invention and should be within the protection scope of the present invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is intended to include such modifications and variations. The above-described embodiments are merely illustrative of the present invention, and the present invention may be embodied in other specific forms or other specific forms without departing from the spirit or essential characteristics thereof. The described embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. The scope of the invention should be indicated by the appended claims, and any changes that are equivalent to the intent and scope of the claims should be construed to be included therein.