阅读说明：本技术 一种高温气冷堆堆芯装料达临界的方法 (Method for achieving criticality of reactor core charge of high-temperature gas cooled reactor ) 是由 姚尧 武方杰 康祯 祁沛垚 韩传高 常重喜 李志容 赵峰 于德 赵敬锴 梁舒婷 于 2021-09-18 设计创作，主要内容包括：本发明公开了一种高温气冷堆堆芯装料达临界的方法,包括以下步骤：1)进行准备工作；2)向堆芯中装入三分之一理论临界装载量的混合燃料；3)向堆芯装入理论临界装载量与当前已装入混合燃料装载量之间差值的三分之一的混合燃料；4)确定下一步的装载量,再进行堆芯的装载,然后转至步骤3),直至最小外推临界装载量与当前装载量之间的差值小于N个混合燃料,然后转至步骤5)；5)下插一组控制棒至Mmm高度处,再在上一次外推临界装载量的基础上增加K个混合燃料,然后送入堆芯；待所有混合燃料装入堆芯后,逐步提起已经下插的一组控制棒,直到堆芯外核测仪表显示反应堆达到临界状态为止,该方法能够使得高温气冷堆堆芯装料达临界。(The invention discloses a method for achieving criticality of reactor core loading of a high-temperature gas cooled reactor, which comprises the following steps of: 1) carrying out preparation work; 2) filling one third of mixed fuel with theoretical critical loading capacity into a reactor core; 3) loading mixed fuel with one third of difference between the theoretical critical loading capacity and the current loaded mixed fuel loading capacity into the reactor core; 4) determining the next loading capacity, loading the reactor core, then turning to the step 3) until the difference between the minimum extrapolated critical loading capacity and the current loading capacity is less than N mixed fuels, and then turning to the step 5); 5) inserting a group of control rods downwards to Mmm height, adding K mixed fuels on the basis of the last extrapolation critical loading amount, and then feeding the K mixed fuels into a reactor core; after all mixed fuel is loaded into the reactor core, the group of control rods inserted downwards are gradually lifted until the nuclear gauge outside the reactor core displays that the reactor reaches a critical state, and the method can enable the reactor core of the high-temperature gas cooled reactor to reach the critical state.)

1. A method for achieving criticality of a core charge of a high-temperature gas cooled reactor is characterized by comprising the following steps:

1) carrying out preparation work;

2) filling one third of mixed fuel with theoretical critical loading into the reactor core, and recording the neutron counting rate of the reactor core outer nuclear measuring instrument;

3) loading mixed fuel with one third of difference between the theoretical critical loading capacity and the current loaded mixed fuel loading capacity into the reactor core, and recording the neutron counting rate of the reactor core outer nuclear measuring instrument;

4) calculating an extrapolated critical load according to the neutron count rate of the incore nuclear measuring instrument recorded in the step 3) and the neutron count rate of the incore nuclear measuring instrument recorded in the step 2), taking the smaller value between the extrapolated critical load and the theoretical critical load, performing difference with the current mixed fuel load, taking one third of the difference result as the load of the next step, performing loading of the incore, turning to the step 3) until the difference between the minimum extrapolated critical load and the current load is less than N mixed fuels, and turning to the step 5);

5) inserting a group of control rods downwards to Mmm height, adding K mixed fuels on the basis of the last extrapolation critical loading amount, and then feeding the K mixed fuels into a reactor core;

after all the mixed fuel is loaded into the reactor core, the control rods inserted downwards are gradually lifted until the nuclear gauge outside the reactor core displays that the reactor reaches a critical state.

2. The method of claim 1, wherein N is 800.

3. The method of claim 1, wherein M is 6000.

4. The method of claim 1, wherein K is 450.

5. The method for achieving criticality of the core charge of the high temperature gas cooled reactor according to claim 1, wherein the specific operation process of the step 1) is as follows:

when the reactor core of the pebble-bed high-temperature gas cooled reactor reaches critical process, all the absorption spheres are blown into a sphere storage tank at the upper part of the reactor core, all the control rods are lifted to the upper limit position at the top of the reactor core, the reactor core is at normal pressure, and the primary loop of the reactor core is in air atmosphere.

6. The method for achieving criticality of the core charge of the high temperature gas cooled reactor of claim 1, wherein all control rods comprise a shutdown rod, a regulating rod and a compensation rod.

7. The method of claim 1, wherein the mixed fuel comprises 4.2% fuel elements and graphite nodules, and a ratio of 4.2% fuel elements to graphite nodules is 7: 8.

Technical Field

The invention belongs to the field of high-temperature gas cooled reactors, and particularly relates to a method for achieving criticality of reactor core loading of a high-temperature gas cooled reactor.

Background

At present, water-cooled reactors such as pressurized water reactors, boiling water reactors, heavy water reactors and the like rely on the lifting of a control rod group to carry out reactor core criticality. The reactor core of the pebble-bed high-temperature gas cooled reactor has a structure completely different from that of a water-cooled reactor, and fuel elements are graphite-coated particle spherical fuel elements, so that the reactor core can be operated critically only after a certain number of the fuel elements are loaded. If the pebble-bed high-temperature gas cooled reactor is critical in the initial reactor core loading stage through lifting control rods, certain risks exist: firstly, no fission poison exists in a reactor core at the initial loading stage of the reactor, the residual reactivity of fuel is high, the reactivity introduced by a control rod is promoted quickly, and the safety of the reactor is not facilitated; secondly, the reactor control rod is not calibrated for reactivity value, so that the calculation possibility of critical extrapolation has obvious difference from the actual critical rod position, and uncertainty risk is brought to the critical operation of the reactor.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method for achieving the criticality of the core charge of the high-temperature gas-cooled reactor, which can enable the core charge of the high-temperature gas-cooled reactor to achieve the criticality and has higher safety.

In order to achieve the above purpose, the method for achieving criticality of the core charge of the high temperature gas cooled reactor comprises the following steps:

1) carrying out preparation work;

2) filling one third of mixed fuel with theoretical critical loading into the reactor core, and recording the neutron counting rate of the reactor core outer nuclear measuring instrument;

3) loading mixed fuel with one third of difference between the theoretical critical loading capacity and the current loaded mixed fuel loading capacity into the reactor core, and recording the neutron counting rate of the reactor core outer nuclear measuring instrument;

4) calculating an extrapolated critical load according to the neutron count rate of the incore nuclear measuring instrument recorded in the step 3) and the neutron count rate of the incore nuclear measuring instrument recorded in the step 2), taking the smaller value between the extrapolated critical load and the theoretical critical load, performing difference with the current mixed fuel load, taking one third of the difference result as the load of the next step, performing loading of the incore, turning to the step 3) until the difference between the minimum extrapolated critical load and the current load is less than N mixed fuels, and turning to the step 5);

5) inserting a group of control rods downwards to Mmm height, adding K mixed fuels on the basis of the last extrapolation critical loading amount, and then feeding the K mixed fuels into a reactor core;

after all the mixed fuel is loaded into the reactor core, the control rods inserted downwards are gradually lifted until the nuclear gauge outside the reactor core displays that the reactor reaches a critical state.

N＝800。

M＝6000。

K＝450。

The specific operation process of the step 1) is as follows:

when the reactor core of the pebble-bed high-temperature gas cooled reactor reaches critical process, all the absorption spheres are blown into a sphere storage tank at the upper part of the reactor core, all the control rods are lifted to the upper limit position at the top of the reactor core, the reactor core is at normal pressure, and the primary loop of the reactor core is in air atmosphere.

All control rods include shutdown rods, regulating rods and compensating rods.

The mixed fuel comprises fuel elements with the enrichment degree of 4.2% and graphite nodules, wherein the part ratio of the fuel elements with the enrichment degree of 4.2% to the graphite nodules is 7: 8.

The invention has the following beneficial effects:

the method for achieving the criticality of the reactor core loading of the high-temperature gas cooled reactor is characterized in that when the method is specifically operated, mixed fuel is wiped to replace a traditional fuel ball, the residual reactivity of the reactor core fuel is smaller, the reactor core fuel is easier to control, meanwhile, a gradual filling mode is adopted, when the difference value between the minimum extrapolated critical loading capacity and the current loading capacity is smaller than N mixed fuels, a group of control rods are inserted downwards, K mixed fuels are added on the basis of the last extrapolated critical loading capacity, and then the mixed fuels are sent into the reactor core; after all the mixed fuel is loaded into the reactor core, the group of control rods inserted downwards is gradually lifted until the nuclear gauge outside the reactor core displays that the reactor reaches a critical state, so that the reactor core of the high-temperature gas cooled reactor reaches the critical state, and the safety is high.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification, illustrate exemplary embodiments of the invention and together with the description serve to explain the invention and not to limit the invention. In the drawings:

FIG. 1 is a flow chart of the present invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It should be noted that the terms "first," "second," and the like in the description and claims of the present invention and in the drawings described above are used for distinguishing between similar elements and not necessarily for describing a particular sequential or chronological order. It is to be understood that the data so used is interchangeable under appropriate circumstances such that the embodiments of the invention described herein are capable of operation in sequences other than those illustrated or described herein. Furthermore, the terms "comprises," "comprising," and "having," and any variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, system, article, or apparatus that comprises a list of steps or elements is not necessarily limited to those steps or elements expressly listed, but may include other steps or elements not expressly listed or inherent to such process, method, article, or apparatus.

The invention is described in further detail below with reference to the accompanying drawings:

referring to fig. 1, the method for loading the core of the high temperature gas cooled reactor to reach the critical state includes the following steps:

1) when the reactor core of the pebble-bed high-temperature gas cooled reactor reaches critical process, all the absorption spheres are blown into a sphere storage tank at the upper part of the reactor core, all the control rods are lifted to the upper limit position at the top of the reactor core, the reactor core is at normal pressure, and a primary loop of the reactor core is in air atmosphere;

2) filling one third of mixed fuel with theoretical critical loading into the reactor core, and recording the neutron counting rate of the reactor core outer nuclear measuring instrument;

3) loading mixed fuel with one third of difference between the theoretical critical loading capacity and the current loaded mixed fuel loading capacity into the reactor core, and recording the neutron counting rate of the reactor core outer nuclear measuring instrument;

4) calculating an extrapolated critical load according to the neutron count rate of the incore nuclear measuring instrument recorded in the step 3) and the neutron count rate of the incore nuclear measuring instrument recorded in the step 2), taking the smaller value between the extrapolated critical load and the theoretical critical load, performing difference with the current mixed fuel load, taking one third of the difference result as the load of the next step, performing loading of the incore, turning to the step 3) until the difference between the minimum extrapolated critical load and the current load is less than 800 mixed fuels, and turning to the step 5);

5) inserting a group of control rods downwards to 6000mm of height, adding 450 mixed fuels on the basis of the last extrapolation critical loading amount, and then feeding the mixed fuels into a reactor core; after all the mixed fuel is loaded into the reactor core, the control rods inserted downwards are gradually lifted until the nuclear gauge outside the reactor core displays that the reactor reaches a critical state.

Example one

The specific process of this embodiment is as follows:

1) blowing all the absorption balls in the absorption ball shutdown system into a ball storage tank at the upper part of the reactor core, lifting all control rods (shutdown rods, regulating rods and compensating rods) to the upper limit position of the top of the reactor core, keeping the reactor core at normal pressure and keeping a primary loop in an air atmosphere;

2) the reactor core is filled with mixed fuel with one third of theoretical critical loading, the neutron counting rate of a reactor core outer nuclear measuring instrument is recorded, the ratio of fuel elements to graphite nodules in the mixed fuel is 7:8, namely, 7 parts of fuel elements with 4.2% enrichment: 8 parts of graphite nodules;

3) then, mixed fuel with one third of the difference between the theoretical critical loading capacity and the current loaded mixed fuel loading capacity is loaded into the reactor core, and the neutron counting rate of the reactor core outer nuclear measuring instrument is recorded;

4) calculating an extrapolated critical load according to the neutron counting rate of the excore nuclear measuring instrument recorded in the step 2) and the neutron counting rate of the excore nuclear measuring instrument recorded in the step 3);

5) selecting the minimum value of the theoretical critical loading capacity and the extrapolated critical loading capacity, and taking one third of the difference result between the theoretical critical loading capacity and the extrapolated critical loading capacity and the current mixed fuel loading capacity as the loading capacity of the next step;

6) loading the reactor core according to the loading capacity determined in the step 5), and then turning to the step 5) until the difference between the minimum extrapolated critical loading capacity and the current loading capacity is less than 800 mixed fuels, and then turning to the step 7);

7) inserting a group of control rods downwards to the position of 6000mm of the reactor core;

8) loading the mixed fuel with the last minimum extrapolated critical loading plus 450 times into the core;

9) and gradually lifting the group of control rods inserted downwards until the reactor reaches a critical state as monitored by an extra-core nuclear measuring instrument.

Finally, it should be noted that: the above embodiments are only for illustrating the technical solutions of the present invention and not for limiting the same, and although the present invention is described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications and equivalents may be made to the embodiments of the invention without departing from the spirit and scope of the invention, which is to be covered by the claims.