CN104035118A - Uranium content detection method - Google Patents
Uranium content detection method Download PDFInfo
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- CN104035118A CN104035118A CN201410290201.XA CN201410290201A CN104035118A CN 104035118 A CN104035118 A CN 104035118A CN 201410290201 A CN201410290201 A CN 201410290201A CN 104035118 A CN104035118 A CN 104035118A
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Abstract
The invention relates to a quantitative measuring method of a radioactive substance, provides an uranium content detection method, and aims at solving the problems that the calculated data of delayed neutron are lost due to high uranium content in a sample during measuring the uranium content by the existing delayed neutron delay technique, or the measuring result of the uranium content is large in deviation due to insufficient calculating and statistics of the delayed neutron caused by excessively small uranium content in the sample, and ensuring the measuring speed and accuracy. The uranium content detection method comprises the following steps: 1, acquiring the time-based variation of calculating rate of the delayed neutron after the sample with known uranium content is irradiated; 2, performing curve fitting; 3, normalizing to obtain a standard delay curve of the delayed neutron; 4, measuring the time-based variation of the calculating rate of the delayed neutron in the sample to be detected; 5, performing quantitative analysis for the uranium content of the sample to be detected by the relative comparison method. With the adoption of the detection method, the problem that the measurement result of the uranium content is large in deviation due to high uranium content of the sample and insufficient calculating and statistics of the delayed neutron can be solved.
Description
Technical field
The present invention relates to a kind of method for quantitative measuring of radiomaterial, particularly a kind of assay method of uranium content.
Background technology
Uranium is a kind of basic resource very important in nuclear industry, and especially for the development and utilization of nuclear energy, raw material is absolutely necessary.In nuclear energy uses and whole nuclear fuel cycle, the mensuration of uranium content is very important all the time.Have now the method for many measure uranium content, as mass spectrophotometry, spectral analysis, fluorescence analysis and chemical analysis etc., but they need to carry out pre-service to sample mostly, and analytical cycle is long.
Fissionable nucleus (as
235u) in the time accepting a thermal neutron, producing fission, can there is β decay in part fission product, generates the daughter nucleus of Feng Zhongzi compared with its stable isotope.In the time that the excitation energy of daughter nucleus is greater than neutron binding energy, just and then a neutron is launched in β decay, and this neutron can be described as delayed neutron for the prompt neutron of fission reaction generation.Pioneer's core of delayed neutron is a lot, and by be classified as one group close half life period, the half life period of delayed neutron group is between 0.2 second to 56 seconds.And by neutron, fissionable nucleus is carried out to irradiation, and the analysis of fissionable material being carried out according to the situation of the delayed neutron counting rate of fissionable nucleus transmitting, can be called as delayed-neutron damping technology.Utilize delayed-neutron damping technology can realize uranium content sensitive, quick, harmless, measure accurately, the time of conventionally analyzing a uranium sample is less than 3 minutes, is applicable to a lot of sample analysis of sample size such as extensive uranium ore resource generaI investigation.
The document great majority that can find are at present to utilize
235the decay feature of the delayed neutron that U fission reaction produces, fixing exposure time (being generally 60 seconds), die-away time (being generally 30 seconds) and Measuring Time (being generally 60 seconds), measure uranium content.For example: " GEOLOGICAL AND GEOCHEMICAL " 57-59 page disclosed " measuring the content of uranium thorium with delay fission neutron technique " that publish in February, 1989; The 2nd phase of Nuclear Technology magazine disclosed " surveying the measurement mechanism of uranium by delayed neutron counting method for one " of publishing for 1985, in these documents, all adopt delayed-neutron damping technology to realize the measurement of Uranium In Geological Samples content.
In " the Delayed-neutron activation analysis at NIST " of " Journal of Radioanalytical Nuclear Chemistry " the 298th volume 1819-1822 page of publishing for 2013, introduce with the measurement of delayed neutron counting method
235the method of U content, the method has also only related to the measurement of uranium content in the little standard substance such as geology, environment of uranium content.
But in the time that unknown sample uranium content is higher, in fixing Measuring Time, delayed neutron measurement system, because counting rate is too high, causes system to reach capacity, therefore can cause delayed neutron counting to lose, make the measurement result of uranium content produce relatively large deviation.If by shortening irradiation time, lengthening the problem of losing to solve delayed neutron counting cool time, owing to relating to hot operation, therefore, in the time that a large amount of samples are measured, will have a strong impact on measuring speed.
In addition, in the time that unknown sample uranium content is too low, adopt existing delayed-neutron damping technology to measure and will cause delayed neutron counting statistics not enough uranium content, can cause equally the measurement result of uranium content to produce relatively large deviation.
Summary of the invention
Cause delayed neutron counting to lose at sample uranium content compared with Gao Shihui for solving existing delayed-neutron damping technology uranium content measurement, or in the time that sample uranium content is too low, cause delayed neutron counting statistics not enough, make the measurement result of uranium content produce the problem of relatively large deviation, and guarantee measuring speed and accuracy, the invention provides a kind of assay method of uranium content.The method comprises the following steps:
One, under certain reactor irradiation condition, utilize the sample certain hour of the known uranium content of pile neutron irradiation, then measure and record delayed neutron counting rate over time;
Two, the sample delayed neutron counting rate of known uranium content after irradiation is carried out to matching over time, obtain delayed neutron die-away curve in time;
Three, the delayed neutron according to the quality of uranium in the sample of known uranium content, step 2 being obtained die-away curve is in time normalized, and obtains the delayed neutron standard attenuation curve of unit interval unit mass;
Four, employing reactor irradiation condition and the exposure time identical with step 1, utilizes pile neutron irradiation testing sample, then measures and record testing sample delayed neutron counting rate over time;
The delayed neutron standard attenuation curve of the unit interval unit mass five, obtaining according to step 3 and testing sample delayed neutron counting rate that step 4 obtains over time, are carried out quantitative test to the uranium content of testing sample by method relatively.
Wherein, the operation of step 1 and step 4 can be carried out simultaneously; The die-away curve in time of delayed neutron described in step 2 can adopt exponential form.
Assay method of the present invention is by introducing the delayed neutron standard attenuation curve of unit interval unit mass, solve on the one hand the measurement of delayed-neutron damping technology uranium content and in the time that sample uranium content is higher, caused delayed neutron counting to lose, made the measurement result of uranium content produce the problem of relatively large deviation; On the other hand, in the time that sample uranium content is lower, same owing to having introduced the delayed neutron standard attenuation curve of unit interval unit mass, therefore also solve due to the not enough larger problem of uranium content measurement result deviation causing of delayed neutron counting statistics.In addition, because data processing section can be carried out fast by computing machine, therefore assay method of the present invention can be realized quick, the accurate analysis of testing sample uranium content.
Embodiment
Below in conjunction with embodiment, embodiments of the present invention are described further.
Embodiment 1
Use concentrated
235u content is respectively the sample 1 of 26.43 micrograms and the unknown of U content, and the vertical channel of squeezing into 30kW micro reactor irradiates 60s, and sample is sent back in delayed neutron detector and measures delayed neutron 120 seconds.Delayed neutron detector is
3he proportional counter, multiple tracks adopts DSA-1000 digital spectrum instrument, is operated in multi channel scaling (MCS) pattern, and MCS is made as 1s interval time.
With exponential function pair
235u content be 26.43 microgram samples delayed neutron counting with
235u content carries out matching, and the fitting function that normalization obtains is f (x)=308.1*exp (0.2132*x)+147.5*exp (0.03065*x).It is very large that sample 1 has just gone out to pile delayed neutron counting rate, exceedes the counting rate that detection system is held, and has counting loss, and after 27 seconds, delayed neutron is by exponential damping.Choose 27-100 second as delayed neutron live time, typical curve, sample 1 are respectively 1924,397493 at counting during this period of time, so in sample 1
235u content is 397493/1924=206.60 microgram.
Embodiment 2
Use concentrated
235u content is respectively the sample 2 of 26.43 micrograms and the unknown of U content, and the vertical channel of squeezing into 30kW micro reactor irradiates 60s, and sample is sent back in delayed neutron detector and measures delayed neutron 120 seconds.Delayed neutron detector is
3he proportional counter, multiple tracks adopts DSA-1000 digital spectrum instrument, is operated in multi channel scaling (MCS) pattern, and MCS is made as 1s interval time.
With exponential function pair
235u content be 26.43 microgram samples delayed neutron counting with
235u content carries out matching, and the fitting function that normalization obtains is f (x)=308.1*exp (0.2132*x)+147.5*exp (0.03065*x).After sample 2 goes out heap, delayed neutron counting rate is 1677 to the maximum, and the counting rate holding far below detection system, counts exponential damping in time.Choose 2-70 second as delayed neutron live time, typical curve, sample 2 are respectively 5076,25579 at counting during this period of time, so in sample 2
235u content is 25579/5076=5.04 microgram.
Claims (3)
1. an assay method for uranium content, is characterized in that the method comprises the following steps:
One, under certain reactor irradiation condition, utilize the sample certain hour of the known uranium content of pile neutron irradiation, then measure and record delayed neutron counting rate over time;
Two, the sample delayed neutron counting rate of known uranium content after irradiation is carried out to matching over time, obtain delayed neutron die-away curve in time;
Three, the delayed neutron according to the quality of uranium in the sample of known uranium content, step 2 being obtained die-away curve is in time normalized, and obtains the delayed neutron standard attenuation curve of unit interval unit mass;
Four, employing reactor irradiation condition and the exposure time identical with step 1, utilizes pile neutron irradiation testing sample, then measures and record testing sample delayed neutron counting rate over time;
The delayed neutron standard attenuation curve of the unit interval unit mass five, obtaining according to step 3 and testing sample delayed neutron counting rate that step 4 obtains over time, are carried out quantitative test to the uranium content of testing sample by method relatively.
2. the assay method of uranium content as claimed in claim 1, is characterized in that: the operation of step 1 and step 4 is carried out simultaneously.
3. the assay method of uranium content as claimed in claim 1, is characterized in that: the die-away curve in time of delayed neutron described in step 2 adopts exponential form.
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108645880A (en) * | 2018-05-11 | 2018-10-12 | 南京航空航天大学 | A kind of power spectrum analytic method of bulk sample |
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| CN102445428A (en) * | 2011-09-19 | 2012-05-09 | 中国原子能科学研究院 | Analytical method of tetravalent uranium |
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| CN103424767A (en) * | 2012-05-22 | 2013-12-04 | 中国原子能科学研究院 | Method for measuring content of 235U and 239Pu in U-Pu mixture |
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Patent Citations (4)
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| CN102445428A (en) * | 2011-09-19 | 2012-05-09 | 中国原子能科学研究院 | Analytical method of tetravalent uranium |
| CN103257148A (en) * | 2012-02-17 | 2013-08-21 | 中国原子能科学研究院 | Analysis method of uranium concentration |
| CN103257147A (en) * | 2012-02-17 | 2013-08-21 | 中国原子能科学研究院 | 232Method for measuring U |
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| 袁国军等: "铀钚混合物的缓发中子测量技术研究", 《第十三届全国活化分析技术学术交流会 会议论文摘要集》 * |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN108645880A (en) * | 2018-05-11 | 2018-10-12 | 南京航空航天大学 | A kind of power spectrum analytic method of bulk sample |
| CN108645880B (en) * | 2018-05-11 | 2021-02-02 | 南京航空航天大学 | Energy spectrum analysis method for large-volume sample |
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Application publication date: 20140910 |