先進(jìn)反應(yīng)堆精確活化計(jì)算方法及關(guān)鍵技術(shù)研究
發(fā)布時(shí)間：2019-02-22 13:13
【摘要】：在反應(yīng)堆運(yùn)行過程中,堆芯內(nèi)部產(chǎn)生的大量中子對(duì)回路中的腐蝕產(chǎn)物和堆內(nèi)的結(jié)構(gòu)部件有很強(qiáng)的活化作用,所形成的活化產(chǎn)物是反應(yīng)堆運(yùn)行與檢修人員職業(yè)照射的主要來源。因此精確的活化計(jì)算對(duì)反應(yīng)堆檢修、換料、退役過程中工作方案的制定和人員的輻照安全有著重要意義。隨著先進(jìn)反應(yīng)堆技術(shù)的發(fā)展,堆芯的結(jié)構(gòu)材料與中子能譜愈發(fā)復(fù)雜,導(dǎo)致在活化計(jì)算中將會(huì)涉及到大量的短壽命核素、激發(fā)態(tài)核素等,且反應(yīng)路徑繁多,為精確和高效的活化計(jì)算帶來挑戰(zhàn)。圍繞上述問題,本文基于超級(jí)蒙卡核模擬軟件系統(tǒng)SuperMC,開展了先進(jìn)反應(yīng)堆的精確活化計(jì)算方法研究。本課題研究了一種基于指數(shù)變換的切比雪夫有理逼近方法(CRAM)的點(diǎn)活化計(jì)算方法,提高了 CRAM在計(jì)算核素長(zhǎng)衰變問題時(shí)的求解精度。在采用精細(xì)反應(yīng)鏈模型的基礎(chǔ)上,考慮了 2231種核素的活化物理過程,共計(jì)66256種核反應(yīng)。并進(jìn)一步考慮了輕核素產(chǎn)額、短壽命核素和激發(fā)態(tài)核素對(duì)活化計(jì)算結(jié)果正確性的影響,支持活度、余熱、潛在生物危害、劑量率和清潔因子等活化特征量的計(jì)算。本文的創(chuàng)新之處包括:(1)發(fā)展了基于深度優(yōu)先搜索的嬗變鏈動(dòng)態(tài)構(gòu)建方法。反應(yīng)堆中核素種類眾多且轉(zhuǎn)換關(guān)系復(fù)雜,嬗變鏈的精細(xì)程度直接影響活化計(jì)算的精度。本文提出的嬗變鏈動(dòng)態(tài)構(gòu)建方法從核素的反應(yīng)截面信息和衰變信息出發(fā),結(jié)合初始計(jì)算核素搜索添加活化產(chǎn)物并構(gòu)建嬗變鏈,并考慮了輕核素產(chǎn)額,搜索精度高、擴(kuò)展性強(qiáng)。(2)發(fā)展了基于大規(guī)模矩陣自適應(yīng)降階的加速方法。在利用CRAM對(duì)活化方程進(jìn)行數(shù)值求解時(shí),大量的短壽命核素會(huì)導(dǎo)致系數(shù)矩陣規(guī)模大,剛性強(qiáng),影響數(shù)值求解的效率。該加速方法能夠結(jié)合實(shí)際的輻照條件,采用矩陣重構(gòu)的方式,有效地降低系數(shù)矩陣的規(guī)模和剛性,從而提高活化計(jì)算的求解效率。以國(guó)際活化基準(zhǔn)例題為例,在保證計(jì)算結(jié)果正確的前提下,使用該加速方法后的求解效率提高了 2倍以上。為了驗(yàn)證本文所發(fā)展的活化計(jì)算方法的正確性和有效性,首先選取了活化計(jì)算中常見的β-、β+等衰變反應(yīng)進(jìn)行測(cè)試,計(jì)算結(jié)果與參考程序的計(jì)算值吻合良好。然后選取了天然核素例題進(jìn)行測(cè)試,計(jì)算了從H到Th共計(jì)90種天然核素在輻照方案下的核素密度及活化特征量的變化情況,計(jì)算結(jié)果與參考程序的結(jié)果符合良好。此外,從裂變和聚變兩個(gè)方面選取了壓水堆燃料包殼例題和IAEA-ACB國(guó)際活化基準(zhǔn)例題進(jìn)行了驗(yàn)證。測(cè)試結(jié)果分別與參考程序的計(jì)算值和基準(zhǔn)值的相對(duì)偏差均在0.5%左右,證明了本方法的正確性和有效性,可用于先進(jìn)反應(yīng)堆的精確活化計(jì)算中。
[Abstract]:During the operation of the reactor, a large number of neutrons produced in the reactor core can activate the corrosion products in the loop and the structural components in the reactor, and the activated products are the main sources of occupational irradiation for the reactor operators and overseers. Therefore, the accurate activation calculation is of great significance to the design of the work plan and the radiation safety of the personnel during the reactor maintenance, reloading and decommissioning. With the development of advanced reactor technology, the structural materials and neutron spectra of the reactor core become more and more complex, which leads to a large number of short-lived nuclides, excited state nuclides and so on, which will be involved in the activation calculation, and the reaction paths are various. It poses a challenge for accurate and efficient activation calculation. In order to solve the above problems, the accurate activation calculation method of advanced reactor is studied based on the super Monka nuclear simulation software system SuperMC,. In this paper, a Chebyshev rational approximation method (CRAM) based on exponential transformation is studied, which improves the accuracy of CRAM in solving the long decay problem of nuclides. On the basis of fine reaction chain model, the activation physical processes of 2231 nuclides were considered, a total of 66256 nuclear reactions were considered. Furthermore, the effects of light nuclide yield, short-lived nuclides and excited nuclides on the correctness of activation calculation results were further considered, supporting the calculation of activation characteristics such as activity, residual heat, potential biological hazard, dose rate and cleaning factor. The innovations of this paper are as follows: (1) the dynamic construction method of transmutation chain based on depth first search is developed. There are many kinds of nuclides in the reactor and the conversion relationship is complex. The precision of transmutation chain directly affects the accuracy of activation calculation. The method proposed in this paper is based on the reaction cross section and decay information of nuclides, combined with the initial calculation of radionuclide search to add activation products and construct the transmutation chain, considering the yield of light nuclides, the search accuracy is high. (2) A method of adaptive order reduction based on large-scale matrix is developed. When the activation equation is solved numerically by CRAM, a large number of short-lived nuclides will result in large scale of coefficient matrix and strong rigidity, which will affect the efficiency of numerical solution. The acceleration method can effectively reduce the scale and rigidity of the coefficient matrix and improve the efficiency of the activation calculation by using the matrix reconstruction method combined with the actual irradiation conditions. Taking the example of international activation datum as an example, the solving efficiency of the accelerated method is improved by more than 2 times under the premise that the calculation results are correct. In order to verify the correctness and validity of the activation calculation method developed in this paper, the 尾 -, 尾 iso-decay reactions commonly used in the activation calculation are first tested, and the calculated results are in good agreement with the calculated values of the reference program. Then, the natural nuclides were selected for test, and the densities and activation characteristics of 90 natural nuclides from H to Th were calculated. The calculated results are in good agreement with the results of the reference program. In addition, the fuel cladding of PWR and the IAEA-ACB International Activation benchmark are selected for verification from fission and fusion. The relative deviation between the test results and the calculated values and the reference values of the reference program is about 0.5%, which proves the correctness and validity of this method and can be used in the accurate activation calculation of advanced reactors.
【學(xué)位授予單位】：中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TL329
本文編號(hào)：2428263
[Abstract]:During the operation of the reactor, a large number of neutrons produced in the reactor core can activate the corrosion products in the loop and the structural components in the reactor, and the activated products are the main sources of occupational irradiation for the reactor operators and overseers. Therefore, the accurate activation calculation is of great significance to the design of the work plan and the radiation safety of the personnel during the reactor maintenance, reloading and decommissioning. With the development of advanced reactor technology, the structural materials and neutron spectra of the reactor core become more and more complex, which leads to a large number of short-lived nuclides, excited state nuclides and so on, which will be involved in the activation calculation, and the reaction paths are various. It poses a challenge for accurate and efficient activation calculation. In order to solve the above problems, the accurate activation calculation method of advanced reactor is studied based on the super Monka nuclear simulation software system SuperMC,. In this paper, a Chebyshev rational approximation method (CRAM) based on exponential transformation is studied, which improves the accuracy of CRAM in solving the long decay problem of nuclides. On the basis of fine reaction chain model, the activation physical processes of 2231 nuclides were considered, a total of 66256 nuclear reactions were considered. Furthermore, the effects of light nuclide yield, short-lived nuclides and excited nuclides on the correctness of activation calculation results were further considered, supporting the calculation of activation characteristics such as activity, residual heat, potential biological hazard, dose rate and cleaning factor. The innovations of this paper are as follows: (1) the dynamic construction method of transmutation chain based on depth first search is developed. There are many kinds of nuclides in the reactor and the conversion relationship is complex. The precision of transmutation chain directly affects the accuracy of activation calculation. The method proposed in this paper is based on the reaction cross section and decay information of nuclides, combined with the initial calculation of radionuclide search to add activation products and construct the transmutation chain, considering the yield of light nuclides, the search accuracy is high. (2) A method of adaptive order reduction based on large-scale matrix is developed. When the activation equation is solved numerically by CRAM, a large number of short-lived nuclides will result in large scale of coefficient matrix and strong rigidity, which will affect the efficiency of numerical solution. The acceleration method can effectively reduce the scale and rigidity of the coefficient matrix and improve the efficiency of the activation calculation by using the matrix reconstruction method combined with the actual irradiation conditions. Taking the example of international activation datum as an example, the solving efficiency of the accelerated method is improved by more than 2 times under the premise that the calculation results are correct. In order to verify the correctness and validity of the activation calculation method developed in this paper, the 尾 -, 尾 iso-decay reactions commonly used in the activation calculation are first tested, and the calculated results are in good agreement with the calculated values of the reference program. Then, the natural nuclides were selected for test, and the densities and activation characteristics of 90 natural nuclides from H to Th were calculated. The calculated results are in good agreement with the results of the reference program. In addition, the fuel cladding of PWR and the IAEA-ACB International Activation benchmark are selected for verification from fission and fusion. The relative deviation between the test results and the calculated values and the reference values of the reference program is about 0.5%, which proves the correctness and validity of this method and can be used in the accurate activation calculation of advanced reactors.
【學(xué)位授予單位】：中國(guó)科學(xué)技術(shù)大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2017
【分類號(hào)】：TL329
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