阅读说明：本技术 一种mox燃料包壳管重利用方法 (MOX fuel cladding tube recycling method ) 是由 田志强 张万德 马绍州 屠振华 郭亮 杨廷贵 张顺孝 刘家礼 朱桐宇 于永龙 邵 于 2020-03-24 设计创作，主要内容包括：本发明涉及核燃料元件制备技术领域,具体公开了一种MOX燃料包壳管重利用方法,将组焊件上的下端塞切掉后,重新加工下端塞,并确保重新加工后的下端塞与切割后的包壳管装配并焊接后,组焊件总长度不变。本发明通过对下端塞焊接失败后的MOX燃料包壳管进行切割,采用端塞加长保证燃料棒总长不变的方式,提高了包壳管的利用率。(The invention relates to the technical field of nuclear fuel element preparation, and particularly discloses a recycling method of an MOX fuel cladding tube. According to the invention, the MOX fuel cladding tube after the lower end plug fails to be welded is cut, and the utilization rate of the cladding tube is improved by adopting a mode of lengthening the end plug to ensure that the total length of the fuel rod is not changed.)

1. A method of recycling a MOX fuel cladding tube, comprising: the method comprises the following steps:

the method comprises the following steps: measuring the original length a of the cladding tube and the lower end plug assembly weldment which fail to be welded, measuring a certain length from the end head of the lower end plug on the cladding tube and the lower end plug assembly weldment which fail to be welded, and marking, wherein the length range covers the welding line and the pressing section part of the lower end plug;

step two: cutting off a lower end plug on the assembly and welding piece, wherein the cutting position is the mark of the first step;

step three: measuring the length b of the cut cladding tube, and calculating the length c of the end plug needing compensation, wherein c is a-b;

step four: the lower end plug is machined again to ensure that the total length of the assembly and welding piece is unchanged after the machined lower end plug is assembled and welded with the cut cladding tube;

step five: pressing the lengthened lower end plug into the cladding tube;

step six: finishing the welding of the cladding tube and the lower end plug;

step seven: and (4) performing weld joint over-gauge inspection and nondestructive testing on the welded cladding tube and the lower end plug assembly weldment, wherein the assembly weldment can be used in the subsequent fuel rod manufacturing process if the assembly weldment is qualified, and the assembly weldment is scrapped if the assembly weldment is not qualified.

2. A MOX fuel cladding tube recycling method as set forth in claim 1, wherein: in the fourth step, the sizes of the press-in section and the extension section of the lower end plug after being reprocessed are unchanged, and the sizes of the step sections are correspondingly lengthened.

3. A MOX fuel cladding tube recycling method as set forth in claim 1, wherein: and seventhly, performing nondestructive testing including visual testing.

4. A MOX fuel cladding tube recycling method as set forth in claim 3, wherein: the visual inspection requires that there are no following defects in the weld zone: missed welding, unfused, cladding tube weld-through, cracks, air holes and sand holes, cladding tube undercut at the edge of the welding seam area, crater at the edge of the welding seam area.

5. A MOX fuel cladding tube recycling method as set forth in claim 1, wherein: the non-destructive testing comprises X-ray testing.

6. A MOX fuel cladding tube recycling method as claimed in claim 5, wherein: the X-ray detection requires that under the condition of two phi 0.25 holes of a visible stepped hole image quality meter, no air holes, gas expansion, cracks, inclusions and incomplete penetration defects exist in a welding seam area.

7. A MOX fuel cladding tube recycling method as set forth in claim 1, wherein: and in the second step, cutting off the lower end plugs on the assembly and welding pieces, and then carrying out deburring treatment on the cladding tube by using a triangular pyramid.

8. A MOX fuel cladding tube recycling method as set forth in claim 1, wherein: and in the second step, cutting off the lower end plug on the assembly welding piece in a turning mode.

9. A MOX fuel cladding tube recycling method as set forth in claim 1, wherein: in the first step, the length is measured by a steel plate ruler.

10. A MOX fuel cladding tube recycling method as set forth in claim 1, wherein: the raw materials are MOX fuel stainless steel cladding tube and stainless steel lower end plug assembly weldment which fail to be welded.

Technical Field

The invention belongs to the technical field of nuclear fuel element preparation, and particularly relates to a recycling method of an MOX fuel cladding tube.

Background

MOX fuel rod manufacturing involves multiple processes, each of which may produce rejects, especially during welding of the upper and lower end plugs to the cladding tube with the highest probability of producing rejects. Because cladding pipe and end plug material are the special material of special development for fast reactor fuel assembly structure spare, its production manufacturing technical degree of difficulty is big and purchasing cost is high, and the cladding pipe is directly scrapped and is handled neither economical nor reasonable after lower end plug welding fails. Therefore, the cladding tube needs to be reused, and material waste is avoided.

At present, after the welding of the lower end plug of the pressurized water reactor nuclear fuel cladding tube fails, the lower end plug is generally removed by turning, and the cladding tube is reused for formal fuel rod manufacturing. However, the fast reactor test assembly fuel rods require precise control of the cladding tube length, so that the cut cladding tube is no longer suitable for official fuel rod manufacture.

How to reuse the abandoned cladding tube to improve the utilization rate of the cladding tube becomes a problem which needs to be solved urgently at present.

Disclosure of Invention

The invention aims to provide a recycling method of an MOX fuel cladding tube, which aims to solve the problem of recycling of the cladding tube.

The technical scheme of the invention is as follows:

a method of recycling a MOX fuel cladding tube comprising the steps of:

the method comprises the following steps: measuring the original length a of the cladding tube and the lower end plug assembly weldment which fail to be welded, measuring a certain length from the end head of the lower end plug on the cladding tube and the lower end plug assembly weldment which fail to be welded, and marking, wherein the length range covers the welding line and the pressing section part of the lower end plug;

step two: cutting off a lower end plug on the assembly and welding piece, wherein the cutting position is the mark of the first step;

step three: measuring the length b of the cut cladding tube, and calculating the length c of the end plug needing compensation, wherein c is a-b;

step four: the lower end plug is machined again to ensure that the total length of the assembly and welding piece is unchanged after the machined lower end plug is assembled and welded with the cut cladding tube;

step five: pressing the lengthened lower end plug into the cladding tube;

step six: finishing the welding of the cladding tube and the lower end plug;

step seven: and (4) performing weld joint over-gauge inspection and nondestructive testing on the welded cladding tube and the lower end plug assembly weldment, wherein the assembly weldment can be used in the subsequent fuel rod manufacturing process if the assembly weldment is qualified, and the assembly weldment is scrapped if the assembly weldment is not qualified.

In the fourth step, the sizes of the press-in section and the extension section of the lower end plug after being reprocessed are unchanged, and the sizes of the step sections are correspondingly lengthened.

And seventhly, performing nondestructive testing including visual testing.

The visual inspection requires that there are no following defects in the weld zone: missed welding, unfused, cladding tube weld-through, cracks, air holes and sand holes, cladding tube undercut at the edge of the welding seam area, crater at the edge of the welding seam area.

The non-destructive testing comprises X-ray testing.

The X-ray detection requires that under the condition of two phi 0.25 holes of a visible stepped hole image quality meter, no air holes, gas expansion, cracks, inclusions and incomplete penetration defects exist in a welding seam area.

And in the second step, cutting off the lower end plugs on the assembly and welding pieces, and then carrying out deburring treatment on the cladding tube by using a triangular pyramid.

And in the second step, cutting off the lower end plug on the assembly welding piece in a turning mode.

In the first step, the length is measured by a steel plate ruler.

The raw materials are MOX fuel stainless steel cladding tube and stainless steel lower end plug assembly weldment which fail to be welded.

The invention has the following remarkable effects:

(1) according to the invention, the MOX fuel cladding tube after the lower end plug fails to be welded is cut, and the utilization rate of the cladding tube is improved by adopting a mode of lengthening the end plug to ensure that the total length of the fuel rod is not changed.

(2) The cladding tube reuse test verifies that the cladding tube reuse rate obtained by the method reaches over 90 percent, can meet the requirements of MOX simulation assemblies on fuel rods during manufacturing, and can also meet the requirements of formal fuel rods during manufacturing.

(3) The method is also suitable for the treatment process of other nuclear fuel rods, has good treatment effect and high reliability, and meets the requirements of process stability and qualification rate.

Drawings

FIG. 1 is a schematic view of a lower end plug;

fig. 2 is a schematic view of the lower end plug after the step is lengthened.

In the figure: 1. a press-in section; 2. a stage of stage; 3. a protruding section.

Detailed Description

The invention is described in further detail below with reference to the figures and the embodiments.

A method of recycling a MOX fuel cladding tube for recycling the cladding tube after failure of welding the MOX fuel cladding tube to a bottom end plug, comprising the steps of:

the method comprises the following steps: measuring the original length a of the cladding tube and the lower end plug assembly weldment which are failed to be welded by using a length measuring tool, measuring a certain length from the end head of the lower end plug on the cladding tube and the lower end plug assembly weldment which are failed to be welded, and marking, wherein the length range covers the welding line and the pressing section part of the lower end plug;

step two: cutting off a lower end plug on the assembly and welding piece in a turning machining or other machining modes, wherein the cutting position is the mark of the first step;

step three: measuring the length b of the cut cladding tube, and calculating the length c of the end plug needing compensation, wherein c is a-b;

step four: re-processing the lower end plug, wherein the sizes of the press-in section and the extension section of the lower end plug are unchanged, and the size of the step section is correspondingly lengthened, so as to ensure that the total length of the assembly and welding piece is unchanged after the re-processed lower end plug is assembled and welded with the cut cladding tube, as shown in the lower end plug structure in the figures 1 and 2;

step five: pressing the lengthened lower end plug into the cladding tube;

step six: setting relevant welding process parameters such as welding current and the like, and finishing the welding of the cladding tube and the lower end plug;

step seven: and (4) carrying out over-gauge inspection, visual inspection, X-ray inspection and other nondestructive tests on the welded welding seam between the cladding tube and the lower end plug assembly weldment, wherein if the welding seam is qualified, the assembly weldment can be used in the subsequent fuel rod manufacturing process, and if the welding seam is not qualified, the assembly weldment is scrapped.