阅读说明：本技术 一种在线啜吸鉴定燃料组件破损的方法 (Method for identifying fuel assembly damage by on-line sipping ) 是由 胡鑫涛 陶子航 于 2020-06-09 设计创作，主要内容包括：本发明公开了一种在线啜吸鉴定燃料组件破损的方法,包括如下步骤：在核电厂卸料期间,在线啜吸进行破损组件检查的过程中,设置报警值,汇总步序与相应组件的微分平均微分计数形成图表,并拟合出组件平均微分计数的趋势线；通过某组组件的平均微分计数与报警值的对比,判定该组件是否破损；如果组件的平均微分计数未超过报警值,则判定其是否是波动图中趋势反弹点以及后续的9组组件；所有组件判定完毕,提交判定结果。本发明的有益效果在于：对在线啜吸测得的燃料组件计数整体进行分析,实现对破口燃料组件的检测识别和提高破损组件的甄别效率。(The invention discloses a method for identifying fuel assembly damage by on-line sipping, which comprises the following steps: during unloading of the nuclear power plant, setting an alarm value in the process of carrying out damaged component inspection by line sipping, summarizing a step sequence and forming a chart with the differential average differential count of the corresponding component, and fitting a trend line of the component average differential count; judging whether the assembly is damaged or not by comparing the average differential count of a certain group of assemblies with an alarm value; if the average differential count of the component does not exceed the alarm value, judging whether the component is a trend bounce point in a fluctuation graph or not and 9 subsequent groups of components; and after all the components are judged, submitting judgment results. The invention has the beneficial effects that: and the fuel assembly counting whole measured by on-line sipping is analyzed, so that the detection and identification of the crevasse fuel assembly are realized, and the discrimination efficiency of the damaged assembly is improved.)

1. A method for in-line sipping certification of fuel assembly breakage, comprising the steps of:

the method comprises the following steps: during unloading of the nuclear power plant, setting an alarm value in the process of carrying out damaged component inspection by line sipping, summarizing a step sequence and forming a chart with the differential average differential count of the corresponding component, and fitting a trend line of the component average differential count;

step two: judging whether the assembly is damaged or not by comparing the average differential count of a certain group of assemblies with an alarm value;

step three: if the average differential count of the component does not exceed the alarm value, judging whether the component is a trend bounce point in a fluctuation graph or not and 9 subsequent groups of components;

step four: and after all the components are judged, submitting judgment results.

2. The method of claim 1, wherein the at least one of the at least one fuel assembly and the at least one fuel assembly is a fuel assembly, and wherein: the alarm value in the first step is three times of the background count.

3. The method of claim 1, wherein the at least one of the at least one fuel assembly and the at least one fuel assembly is a fuel assembly, and wherein: the fitting in step one is accurate to at least 6 degree polynomial.

4. The method of claim 1, wherein the at least one of the at least one fuel assembly and the at least one fuel assembly is a fuel assembly, and wherein: and in the second step, the average differential count of the component exceeds an alarm value, and the component is judged to be damaged.

5. The method of claim 1, wherein the at least one of the at least one fuel assembly and the at least one fuel assembly is a fuel assembly, and wherein: and in the second step, the average differential count of the component is lower than the alarm value, and the third step is executed.

6. The method of claim 1, wherein the at least one of the at least one fuel assembly and the at least one fuel assembly is a fuel assembly, and wherein: and if the determination in the third step is successful, determining that the group of components is suspected to be damaged components.

7. The method of claim 1, wherein the at least one of the at least one fuel assembly and the at least one fuel assembly is a fuel assembly, and wherein: and judging whether the assembly is an undamaged assembly or not in the third step.

Technical Field

The invention belongs to a nuclear fuel assembly integrity inspection method, and particularly relates to a method for on-line sipping and identifying fuel assembly damage.

Background

The reliability of the nuclear fuel assembly is crucial to the safe and stable operation of the nuclear power plant unit, the radioactivity of characteristic nuclide in the nuclear power plant unit is sampled and analyzed through a main reactor system during the power operation of the nuclear power plant, the reliability index of the fuel assembly is calculated, and once the integrity of the certified reactor core assembly is damaged, each group of reactor core assemblies needs to be detected by using an on-line sipping device during the overhaul unloading period. The working principle of the online sipping is as follows: during the unloading process, when the damaged assembly is lifted to the fixing part of the loading and unloading machineWhen the sleeve is fixed, the external pressure applied to the fission gas in the fuel rod is reduced due to the height change of the fuel assembly in the reactor core and the refueling water pool, and if the fuel rod is damaged, the fission gas is accelerated¹³³Xe is released from the damaged fuel element cladding outwards, clean compressed air is injected from the bottom of the sleeve through an air blowing pipe of the on-line sipping system at the same time, fission gas is taken out, the air pumping pipe at the upper part pumps the part of the gas into a gamma activity measuring chamber of the on-line sipping device, and the gamma activity measuring chamber is used for measuring the gas¹³³And judging whether the component is damaged or not according to the Xe counting rate.

At present, the nuclear power plant usually uses sipping factor f to determine the damage condition of the detected fuel assembly, where the sipping factor f is¹³³The ratio of the gamma counting rate of Xe to the background counting rate is represented by the formula: f ═¹³³The method for judging the damaged fuel assembly commonly used in the nuclear power plant at present comprises the following steps: when f is>3, judging that the fuel assembly is damaged; when 3 is>f>And 1.3, judging that the fuel assembly is suspected to be damaged. When it is determined that the fuel assembly is suspected to be broken, it is necessary to take a more accurate detection method for determining the fuel assembly.

This method is only a judgment from the perspective of a single set of components (small area components) and does not consider the unloading process¹³³The influence of the Xe continuous decay and the reduction of the reactor core components on the on-line sipping is not analyzed, and the overall change of the measurement data of all the components of the reactor core is not analyzed, so that when the single set of fuel component sipping data is not obvious, the sipping factor of all the fuel components of the reactor core on the on-line sipping detection is less than 1.3, the judgment can not be given according to the sipping factor, and a large amount of suspected damaged components are generated. The condition can increase the personnel and time cost for accurately judging the damaged components in the follow-up process of the power station and the irradiation dose of the personnel, and even influences the overall overhaul progress of the nuclear power station.

Disclosure of Invention

The invention aims to provide a method for identifying fuel assembly damage by on-line sipping, which adopts the integral analysis of a reactor core assembly¹³³And the gamma counting rate of Xe realizes the damage identification of the fuel assembly.

The technical scheme of the invention is as follows: a method for in-line sipping certification of fuel assembly breakage, comprising the steps of:

the method comprises the following steps: during unloading of the nuclear power plant, setting an alarm value in the process of carrying out damaged component inspection by line sipping, summarizing a step sequence and forming a chart with the differential average differential count of the corresponding component, and fitting a trend line of the component average differential count;

step two: judging whether the assembly is damaged or not by comparing the average differential count of a certain group of assemblies with an alarm value;

step three: if the average differential count of the component does not exceed the alarm value, judging whether the component is a trend bounce point in a fluctuation graph or not and 9 subsequent groups of components;

step four: and after all the components are judged, submitting judgment results.

The alarm value in the first step is three times of the background count.

The fitting in step one is accurate to at least 6 degree polynomial.

And in the second step, the average differential count of the component exceeds an alarm value, and the component is judged to be damaged.

And in the second step, the average differential count of the component is lower than the alarm value, and the third step is executed.

And if the determination in the third step is successful, determining that the group of components is suspected to be damaged components.

And judging whether the assembly is an undamaged assembly or not in the third step.

The invention has the beneficial effects that: and the fuel assembly counting whole measured by on-line sipping is analyzed, so that the detection and identification of the crevasse fuel assembly are realized, and the discrimination efficiency of the damaged assembly is improved.

Drawings

Fig. 1 is a flowchart of a method for identifying fuel assembly damage by on-line sipping according to the present invention.

Detailed Description

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

The invention belongs to the field of nuclear power plants, and particularly relates to a method for processing and analyzing measurement data when a fuel assembly is detected by an on-line sipping technology in a nuclear power plant so as to identify the integrity of the fuel assembly.

The invention provides a method for authenticating fuel assembly damage by on-line sipping, which is based on differential counting of reactor core assemblies detected by on-line sipping and is based on a data conclusion obtained by sampling and analyzing a reactor main system during power operation of a nuclear power plant.

During power operation of the nuclear power station, the radioactivity of characteristic nuclides in a reactor main system is sampled and analyzed, the reliability index of fuel assemblies is calculated, once the index is abnormal, the reactor core is considered to have assemblies damaged, and the number of the assemblies which are possibly damaged is given. More accurate detection is performed by sip on line during unloading.

If the core assemblies are not damaged, the number of the core assemblies is reduced and the number of the core assemblies is reduced along with the time during the unloading process¹³³Assemblies for continuous decay, in-line sipping of Xe¹³³The Xe differential count decreases with the discharge progress trend line, and if a broken component is present, the set of components measures¹³³Differential Xe counting and subsequently measured fuel assemblies¹³³The Xe differential count will be large, undermining the tendency of the component differential count to drop during normal discharge. Thus, by fitting the core assembly¹³³Of Xe differential counting assemblies and individual components¹³³Analyzing the differential Xe counts for the assembly¹³³The Xe differential count trend lines are mathematically fitted to identify damaged fuel assemblies and suspected damaged fuel assemblies.

The specific identification principle is as follows:

a fuel assembly breakage

When measured by a group of components¹³³And the Xe average differential count value is greater than the alarm value of the line sipping device, and the component is determined to be damaged.

Suspected breakage of fuel assembly

Processing differential counts of all components of the reactor core along with the unloading sequence to generate a chart, mathematically fitting a trend line on the step sequence and the average differential count through program software, and taking the components with the changed descending trend and the subsequent 9 groups of components as suspected damaged components.

c non-breakage of fuel assembly

Determining the component other than the conditions a and b as an undamaged component

According to the identification method and principle, as shown in fig. 1, a method for identifying fuel assembly damage by on-line sipping includes the following steps:

the method comprises the following steps: during unloading of the nuclear power plant, setting an alarm value to be three times of background count in the process of carrying out damaged component inspection by line sipping, forming a chart by a summary step and differential average differential count of a corresponding component, and fitting a trend line of the component average differential count (the fitting accuracy of the trend line at least reaches 6-order polynomial);

step two: if the average differential count of a certain group of components exceeds the alarm value, identifying that the group of components is damaged, otherwise, performing the next judgment;

step three: if the average differential count of the component does not exceed the alarm value, judging whether the component is a trend bounce point in a fluctuation chart and 9 subsequent groups of components, if the judgment is successful, judging the group of components as suspected damaged components, judging the group of components as not damaged components, and identifying the group of components as undamaged components.

Step four: and after all the components are judged, submitting judgment results.

The technical method of the present invention will be described in detail with reference to the accompanying drawings and specific examples.

According to the method, the radioactivity of the characteristic nuclide in the reactor main system is sampled and analyzed during the power operation of the nuclear power station, the reliability index of the fuel assembly is calculated, once the index is abnormal, the reactor core is considered to have the assembly breakage, and the number of the assembly breakage possibly occurring is given. And performing core assembly on-line sipping measurement on each group of assemblies during unloading¹³³Xe differential counting, identifying broken components by bulk analysis of core component differential counts.

The identification principle is as follows:

a fuel assembly breakage

When measured by a group of components¹³³And the Xe average differential count value is greater than the alarm value of the line sipping device, and the component is determined to be damaged.

Suspected breakage of fuel assembly

Processing differential counts of all components of the reactor core along with the unloading sequence to generate a chart, mathematically fitting a trend line on the step sequence and the average differential count through program software, and taking the components with the changed descending trend and the subsequent 9 groups of components as suspected damaged components.

c non-breakage of fuel assembly

Determining the component other than the conditions a and b as an undamaged component

The implementation steps are as follows:

(1) during unloading of the nuclear power plant, in the process of carrying out damaged component inspection by line sipping, setting an alarm value to be three times of background count, forming a chart by the summary step and the differential average differential count of the corresponding component, and fitting a trend line of the component average differential count (the fitting accuracy of the trend line is at least up to 6-order polynomial).

(2) Example 1: and (3) major repair of a certain power station, sending an alarm by the online sipping alarm device in step 90, wherein the average differential count of the group is 3247, and determining that the component is damaged. FIG. 1 is a graph of core assembly differential count rate as a function of assembly. After subsequent off-line sipping confirmation, the component is indeed damaged and is consistent with the judgment result of the method.

(3) Example 2: and (3) carrying out machine overhaul on a certain power station No. 4, processing differential counts of all assemblies of the reactor core along with the unloading sequence to generate a chart, carrying out mathematical fitting on the step sequence and the average differential counts by program software to obtain assemblies with changed descending trend and subsequent 9 groups of assemblies as suspected damaged assemblies. And (3) implementing the change of the reactor core component differential count rate along with the component in a certain power station, and judging that the selected area trend line rebounds in step 69 and the subsequent steps 70-78 to be suspicious components, namely judging that 10 groups of components in steps 69-78 are suspected to be damaged components. After a later off-line sipping, 77 th group of fuel assembly damages are successfully detected in the suspected damaged assembly.

The damaged fuel assembly, the damaged suspicious assembly area and the rest of the fuel assemblies can be judged to be not damaged by mathematically fitting the change of the trend line to the step order and the average differential counting of the line sipping. The corresponding results of the two overhaul offline sipping tests also prove the reliability of the method.