基于Geant4的铀裂变瞬发中子测井铀定量及修正方法  

Geant4-based Uranium Quantification and Correction Method for Uranium Fission Transient Neutron Logging

作　　者：冉吉发 RAN Jifa(East China University of Technology,Jiangxi Engineering and Technology Research Center for Nuclear Radiation Detection and Application,Nanchang 330013,China;East China University of Technology,School of Nuclear Science and Engineering,Nanchang 330013,China)

机构地区：[1]东华理工大学江西省核辐射探测及应用工程技术研究中心,南昌330013 [2]东华理工大学核科学与工程学院,南昌330013

出　　处：《能源研究与管理》2025年第1期179-186,共8页Energy Research and Management

基　　金：国家自然科学基金(12275050),铀裂变瞬发中子与中子寿命同步测井技术研究,江西省高层次高技能领军人才培养工程项目资助(赣财社指[2023]37号)。

摘　　要：为提高中子测井数据利用效率,降低中子管使用成本,利用Geant4模拟不同铀元素质量分数的Nu系列砂岩型铀矿模型井,钻孔直径90 mm,探测器居中测量,获取长源距和短源距的超热中子时间谱与热中子时间谱,利用超热中子与热中子比值计算铀元素质量分数,再拟合的中子平均消逝时间对测井结果进行中子时间谱修正。结果表明:长源距与短源距中子探测器所得超热中子时间谱图整体趋势为先上升后下降的指数变化,热中子时间谱图为指数衰减趋势,在对数坐标轴下呈现为直线,符合地层中子衰减规律;3种标准模型井初始时铀元素质量分数(0.01%)分别为2.81、6.85和9.83的标准井初始模拟铀元素质量分数(0.01%)分别为2.833、6.941和9.759,相对误差分别为0.818%、1.328%和0.722%;超热中子时间谱负指数拟合R2最低为0.9907,热中子时间谱负指数拟合R2最低为0.9173,拟合结果良好;经过中子时间谱修正之后模拟铀元素质量分数(0.01%)分别为2.832、6.939和9.760,相对误差分别降低为0.813%、1.295%和0.712%。时间谱修正能提高铀裂变瞬发中子测井数据的准确性,该方法可进一步用于铀裂变瞬发中子测井系统。In order to improve the utilization efficiency of neutron logging data and reduce the use cost of neutron tube,Geant4 was used to simulate Nu series sandstone type uranium mine model wells with different uranium element mass fractions.The borehole diameter was 90 mm,and the detectors were centered in the center of the wells to obtain the hyperthermal and thermal neutron time spectra for both the long-source and short-source distances,and then the ratio of hyperthermal and thermal neutrons was used to calculate the uranium content,and then the fitted neutron mean time of elapsed time was used to correct the time spectra of the wells.The results show that:the overall trend of the epithermal neutron time spectra obtained from the long-source distance and short-source distance neutron detectors is an exponential change of increasing and then decreasing,and the thermal neutron time spectra have an exponential decay trend,which is presented as a straight line under the logarithmic axis,which is in accordance with the neutron decay law of the stratum;the three kinds of initial simulated uranium contents of standard wells with initial uranium content(0.01%)of 2.81,6.85,and 9.83,respectively,and the three kinds of standard wells with initial simulated uranium contents of 2.81,6.85 and 9.83,respectively,are shown in the results of the neutron time spectrum correction(0.01%)are 2.833,6.941 and 9.759,respectively,with relative errors of 0.818%,1.328%and 0.722%,respectively;the negative exponent fit R2 of epithermal neutron time spectra is as low as 0.9907,and that of thermal neutron time spectra is as low as 0.9173,which is a good fit;after correction of the neutron time spectra,the simulated uranium content(0.01%)are 2.832,6.939 and 9.760,and the relative errors are reduced to 0.813%,1.295%and 0.712%,respectively.The time spectrum correction improves the accuracy of uranium fission transient neutron logging data.

关 键 词：铀裂变瞬发中子测井 铀定量 GEANT4 超热中子 热中子 

分 类 号：P619.14[天文地球—矿床学] P631.81[天文地球—地质学]