Performance supervision sample tree for neutron absorber of quadrilateral spent fuel storage grillwork

Abstract

The invention belongs to the technical field of nuclear power plant aging life extension, and particularly relates to a performance supervision sample tree for a neutron absorber of a quadrilateral spent fuel storage grillwork. An upper pipe seat is arranged at the upper end of the quadrangular main body, a lower pipe seat is arranged at the lower end of the quadrangular main body, sample plate shelves are arranged on four sides of the quadrangular main body, 16 groups of sample plates are respectively placed on two groups of opposite sides, eight boron-aluminum plate sample plates are placed on eight groups on one side of each group of opposite sides, and eight groups of boron-aluminum coated sample plates are placed on the other side of each group of opposite sides; meanwhile, water-permeable holes are formed in the lower part of the sample plate shelf. The aging condition of a spent fuel storage grillwork neutron absorber material in a spent fuel pool is monitored, the actual performance of the neutron absorber material is evaluated, and the neutron absorber sample plate is put into a spent fuel storage grillwork and can be taken out regularly for detection.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of nuclear power plant aging and life extension, and particularly relates to a quadrilateral spent fuel storage rack neutron absorber performance supervision sample tree. BACKGROUND

[0002] In order to ensure that the spent fuel assembly meets the subcritical requirement, the spent fuel storage rack of the nuclear power plant uses a neutron absorber material. The neutron absorber material is affected by the spent fuel pool environment and the irradiation of the spent fuel assembly, and has aging effects such as corrosion, bubbling, and neutron absorption capacity decline. In order to master the aging condition of the neutron absorber material in the spent fuel pool of the spent fuel storage rack and monitor the actual performance of the neutron absorber material, the absorber material sample needs to be placed in the spent fuel pool and taken out regularly for testing and evaluation. The GALL report issued by the NRC and the IGALL report issued by the IAEA both propose a method of placing a neutron absorber sample plate and regularly testing and evaluating the actual performance of the neutron absorber material.

[0003] The M310 type spent fuel storage rack is quadrilateral. For the performance supervision of the neutron absorber material of the M310 quadrilateral spent fuel storage rack, a sample tree needs to be designed and manufactured, which can reliably place the neutron absorber sample in the spent fuel storage rack and can be taken out regularly for detection. The structure and size of the sample tree are adapted to the quadrilateral spent fuel storage rack to ensure that it can be placed in the rack and easily taken out. The sample tree should be made of high-quality materials, has excellent corrosion resistance, radiation resistance, and structural stability, does not deform or break during the entire service life of the unit, does not have adverse reactions with the medium and various structural parts in the spent pool, and does not release substances that adversely affect water quality; the sample tree and the sample plate do not produce adverse additional loads on the spent fuel storage rack and do not affect the original design performance of the rack, and do not pose other risks to the unit; it should be able to place the required number of sample plates, and the sample plates should not fall off, be easy to take out, and the position of the sample plates in the sample tree should be able to ensure that the sample plates are representative of the irradiation to ensure the supervision effect. SUMMARY

[0004] The purpose of the present application is to provide a quadrilateral spent fuel storage rack neutron absorber performance supervision sample tree, which can monitor the aging condition of the neutron absorber material in the spent fuel pool of the spent fuel storage rack, evaluate the actual performance of the neutron absorber material, and place the neutron absorber sample plate in the spent fuel storage rack and take it out regularly for detection.

[0005] To achieve the above purpose, the technical solution adopted by the present application is as follows:

[0006] The utility model relates to a kind of quadrilateral spent fuel storage grid neutron absorber performance supervision sample trees, four-pronged main body upper end is equipped with upper tube seat, four-pronged main body lower end is equipped with lower tube seat, four-pronged main body four sides are all provided with sample plate shelf, two groups of opposite sides are placed 16 groups of sample plates respectively, one side of each group of opposite sides 8 groups is placed 8 boron-aluminum plate sample plates, and the other side is placed 8 groups of boron-aluminum coated sample plates, four-pronged main body and lower tube seat are all opened through hole, and the lower part of sample plate shelf is processed water hole simultaneously.

[0007] Upper tube seat has interface matched with fuel assembly grab, and sample tree is grabbed using fuel assembly grab.

[0008] One side of each group of opposite sides 8 groups is placed 8 boron-aluminum plate sample plates of 120×180mm.

[0009] The other side is placed 8 groups of 120×180mm boron-aluminum coated sample plates.

[0010] Sample plate shelf adopts anti-loosening jackscrew design, and shelf is installed on four-pronged main body through jackscrew and jackscrew fixing sleeve.

[0011] Sample tree material adopts 304L austenitic stainless steel 022Cr19Ni10.

[0012] Sample tree metal surface is pickled and passivated.

[0013] Step 1: complete initial test of sample plate, and reserve data to compare with subsequent sample plate test data;Step 2: sample tree is placed in horizontal state, sample plate is installed in sample plate shelf, jackscrew of sample plate shelf is screwed, and sample plate number and installation position are recorded;Step 3: sample tree is transported to fuel plant, and sample tree is turned from horizontal to vertical state;Step 4: using auxiliary crane of fuel plant, short handle grab is used to grab sample tree and place in new fuel elevator;Step 5: using fuel assembly long handle grab on fuel plant bridge crane, sample tree is placed into target spent fuel storage grid, and sample tree installation process is finished;Step 6: when sampling, using fuel assembly long handle grab on fuel plant bridge crane, sample tree is placed into new fuel elevator;Step 7: when sampling, using auxiliary crane of fuel plant, short handle grab is used to grab sample tree and place into new fuel elevator;Step 8: when sampling, using auxiliary crane of fuel plant, short handle grab is used to grab sample tree and place into sampling operation site;Step 9: the number of sample plate taken out is determined, sample plate shelf is determined according to record, jackscrew of sample plate shelf is loosened, and sample plate is taken out;Step 10: steps 3-5 are repeated, and sample tree is placed back into target spent fuel storage grid, and sampling process is finished.

[0014] The utility model has the beneficial effects that:

[0015] The application can realize reliable placement and rapid extraction of the neutron absorber sample plate, is used for evaluating the performance of the neutron absorber material in the quadrilateral spent fuel storage rack, provides data for the aging management and future life extension of the spent fuel storage rack, and is suitable for the performance supervision of the neutron absorber material in the quadrilateral spent fuel rack of different types of domestic units. The sample tree completely matched with the quadrilateral spent fuel rack and the field conditions is designed, the sample tree has sufficient structural strength and reliability, and meets the performance supervision requirements of the neutron absorber material; a sufficient number of sample plate racks are designed to meet the sample plate quantity requirements in the entire service life; a separate rack is designed to ensure firm placement of the sample plate, avoid the formation of foreign matter by the falling of parts, and facilitate the extraction of the sample plate; the sample tree adopts an integrated welding structure design, the material is 304L stainless steel, and the material is subjected to pickling and passivation treatment, is compatible with the medium environment, is stable and corrosion-resistant, and can meet the placement requirements in the entire service life; the upper and lower tube seats are designed according to the full size of the fuel assembly, completely simulate the structural characteristics of the fuel assembly, can ensure that the sample tree is hoisted by using the existing lifting tool, can be well adapted to the rack, ensures easy placement and extraction, and the operation process is stable, safe and reliable. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 It is a structure diagram of a quadrilateral spent fuel storage rack neutron absorber performance supervision sample tree.

[0017] Figure 2 It is a structure diagram of a sample plate rack.

[0018] In the figure: 1-upper tube seat; 2-quadrilateral main body; 3-through hole; 4-boron aluminum coated sample plate; 5-sample plate rack; 6-boron aluminum plate sample plate; 7-lower tube seat; 8-sample plate; 9-top screw; 10-rack; 11-top screw fixing sleeve. DETAILED DESCRIPTION

[0019] The application will be described in detail below in combination with the drawings and specific embodiments.

[0020] The sample tree main body structure is divided into an upper tube seat, a lower tube seat, a four-edge main body and a sample plate shelf, and the overall design is a quadrilateral structure, and the size is adaptable to the spent fuel storage rack. The upper end of the four-edge main body 2 is provided with the upper tube seat 1, and the lower end of the four-edge main body 2 is provided with the lower tube seat 7. The upper tube seat has an interface matched with the fuel assembly grab, and the fuel assembly grab can be used to grab the sample tree. The four-edge main body 2 is provided with the sample plate shelf 5 on four edges, and two groups of opposite edges can respectively place 16 groups of sample plates 8. One of the two groups of opposite edges places 8 groups of 120*180mm boron aluminum plate sample plates 6, and the other places 8 groups of 120*180mm boron aluminum coated sample plates 4. The four-edge main body 2 and the lower tube seat 7 are both provided with through holes 3, so as to ensure that the sample tree is not affected by the water resistance when being placed in the spent fuel storage rack. The sample plate shelf 5 is designed with an anti-loosening jack screw, the shelf 10 is installed on the four-edge main body 2 through the jack screw 9 and the jack screw fixing sleeve 11, which can ensure that the sample is stored firmly and reliably, and can also avoid the screw from falling off to form a foreign matter in the spent pool. At the same time, the lower part of the sample plate shelf 5 is processed with a water permeable hole, so as to avoid a large amount of water remaining when the sample tree is lifted out of the spent pool, which will adversely affect the safe operation.

[0021] The main components of the sample tree are made of 304L austenitic stainless steel (022Cr19Ni10), the metal surface of the sample tree is acid pickling and passivated, so as to have excellent corrosion resistance, radiation resistance and structural stability, and will not deform, crack, react with the medium in the spent pool and various structural parts, and will not release substances that will adversely affect the water quality during the entire service life of the unit. The sample tree and the sample plate do not produce adverse additional load on the spent fuel storage rack, do not affect the original design performance of the rack, and do not produce other risks to the unit.

[0022] Step 1: Complete the initial test of the sample plate and retain the data for comparison with the subsequent test data after removing the sample plate; Step 2: Place the sample tree in a horizontal position, install the sample plate in the sample plate shelf, tighten the top screw of the sample plate shelf, and record the sample plate number and installation position; Step 3: Transport the sample tree to the fuel plant and flip the sample tree from a horizontal position to an upright position; Step 4: Using the auxiliary crane in the fuel plant, use a short-handled gripper to grab the sample tree and place it in the new fuel elevator; Step 5: Using the long-handled gripper of the fuel assembly on the man-bridge crane in the fuel plant, grab the sample tree and place it in the target spent fuel storage rack. The sample tree installation process is complete. Step 6: During sampling, use the long-handled gripper on the fuel assembly on the fuel plant's overhead crane to grab the sample tree and place it into the new fuel elevator; Step 7: During sampling, use the auxiliary crane in the fuel plant, in conjunction with the short-handled gripper, to grab the sample tree and place it into the new fuel elevator; Step 8: During sampling, use the auxiliary crane in the fuel plant and the short-handled gripper to grab the sample tree to the sampling work area; Step 9: Determine the sample plate number, locate the sample plate shelf according to the record, loosen the top screw of the sample plate shelf, and remove the sample plate; Step 10: Repeat steps 3 to 5 to place the sample tree back into the target spent fuel storage rack, and the sampling process is complete.

Claims

1. A quadrilateral spent fuel storage rack neutron absorber performance surveillance test specimen tree characterized by: The upper end of the quadrangular body is provided with an upper tube seat, the lower end of the quadrangular body is provided with a lower tube seat, the four edges of the quadrangular body are provided with sample plate shelves, 16 groups of sample plates are placed on two groups of opposite edges, 8 groups of 8 boron-aluminum plate sample plates are placed on one of the edges of each group of opposite edges, and 8 groups of boron-aluminum coated sample plates are placed on the other edge.

2. The quadrilateral spent fuel storage rack neutron absorber performance surveillance test sample tree of claim 1, wherein: The upper tube seat has an interface matched with a fuel assembly grab, and the sample tree is grabbed by the fuel assembly grab.

3. The quadrilateral spent fuel storage rack neutron absorber performance surveillance sample tree of claim 1, wherein: 8 groups of 8 boron-aluminum plate sample plates with a size of 120*180mm are placed on one of the edges of each group of opposite edges.

4. The quadrilateral spent fuel storage rack neutron absorber performance surveillance sample tree of claim 1, wherein: 8 groups of 120*180mm boron-aluminum coated sample plates are placed on the other edge.

5. The quadrilateral spent fuel storage rack neutron absorber performance surveillance sample tree of claim 1, wherein: The sample plate shelf is designed with an anti-loosening jack screw, and the shelf is installed on the quadrangular body through the jack screw and a jack screw fixing sleeve.

6. The quadrilateral spent fuel storage rack neutron absorber performance surveillance sample tree of claim 1, wherein: The sample tree material is 304L austenitic stainless steel 022Cr19Ni10.

7. The quadrilateral spent fuel storage rack neutron absorber performance surveillance sample tree of claim 1 wherein: The metal surface of the sample tree is subjected to pickling and passivation treatment.

8. The quadrilateral spent fuel storage rack neutron absorber performance surveillance sample tree of claim 5, wherein: Step 1: complete the initial test of the sample plate, and retain the data for comparison with the subsequent removed sample plate test data; Step 2: place the sample tree in a horizontal state, install the sample plate in the sample plate shelf, tighten the sample plate shelf jack screw, and record the sample plate number and installation position; Step 3: transport the sample tree to the fuel plant, and turn the sample tree from horizontal to vertical; Step 4: use the auxiliary crane in the fuel plant, and use the short handle grab to grab the sample tree and place it in the new fuel elevator; Step 5: use the fuel assembly long handle grab on the fuel plant bridge crane to grab the sample tree and place it in the target spent fuel storage rack, and the sample tree installation process is completed; Step 6: when sampling, use the fuel assembly long handle grab on the fuel plant bridge crane to grab the sample tree and place it in the new fuel elevator; Step 7: when sampling, use the auxiliary crane in the fuel plant to cooperate with the short handle grab to grab the sample tree and place it in the new fuel elevator; Step 8: when sampling, use the auxiliary crane in the fuel plant to use the short handle grab to grab the sample tree to the sampling operation site; Step 9: determine the removed sample plate number, determine the sample plate shelf according to the record, loosen the sample plate shelf jack screw, and remove the sample plate; Step 10: repeat steps 3-5 to place the sample tree back into the target spent fuel storage rack, and the sampling process is completed.

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