基于TMSR-PNS装置0.008~0.1 eV能区Th的全截面测量  

Measurement of Neutron Total Cross Section of Th in 0.008-0.1 eV at TMSR-PNS

作　　者：胡继峰[1,2] 王小鹤 姜炳[1,2,3] 韩建龙 陈金根[1,2,3] 蔡翔舟 HU Jifeng;WANG Xiaohe;JIANG Bing;HAN Jianlong;CHEN Jingen;CAI Xiangzhou(Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Shanghai 201800,China;CAS Innovative Academies in TMSR Energy System,Shanghai 201800,China;University of Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]中国科学院上海应用物理研究所,上海201800 [2]中国科学院先进核能创新研究院,上海201800 [3]中国科学院大学,北京100049

出　　处：《原子能科学技术》2022年第1期61-67,共7页Atomic Energy Science and Technology

基　　金：中国科学院TMSR先导专项(XDA02010000);中国科学院前沿科学重点研究项目(QYZDY-SSW-JSC016);国家自然科学基金(11790321)。

摘　　要：Th是Th-U燃料循环的起始核素,其核数据精度关系到Th-U转换性能。基于TMSR-PNS中子源采用透射法对高纯ThO_(2)样品进行测量,得到ThO_(2)的全截面实验数据。利用ENDF/B-Ⅶ.1库中氧的评价数据,扣除氧的全截面,得到Th的全截面。测量结果显示,Th的全截面在0.02~0.1 eV能量范围测量数据的不确定度为3.25%~4.51%,与ENDF/B-Ⅶ.1库评价数据差异在实验误差范围内。中子能量小于0.02 eV时Th的全截面实验数据出现了布拉格散射结构,其与ENDF/B-Ⅶ.1库UO_(2)的U热中子散射截面类似。The nuclear data of Th is primary interest for the thorium-uranium(Th-U)fuel cycle,and its nuclear data accuracy is related to the conversion performance of Th-U fuel cycle.Based on the photo-neutron source for the thorium molten salt reactor(TMSR-PNS),the total cross section(TCS)of ThO_(2)was measured by the transmission method for the high purity thorium oxide(ThO_(2))samples.ThO_(2)samples which the thicknesses were respectively 0.9 cm and 0.608 cm were made by pressing and sintering process at 1800℃.Based on the different pulse shapes of neutrons andγ-rays(n/γ)signal from the lithium iodide(LiI)scintillator detector used for the time-of-flight(TOF)calculation,γ-rays were identified by pulse shape discrimination(PSD)method to reduce the interference of the measured cross section.Combined with the trough position of TOF spectrum and its corresponding energy for the calibration targets of Ag,In and Cd,the flight distance was fitted to be 5.899 m,so as to convert TOF spectrum of neutrons into energy spectrum.Energy spectrum of 10 cm thickness boracic polythene sample was measured to deduct the influence of the scattering neutron from the background.According to the measured neutron leakage spectrum with or without ThO_(2)sample,experimental data of TCS for ThO_(2)were obtained.TCS of ^(16)O from ENDF/B-Ⅶ.1 was deducted from TCS of ThO_(2)and TCS of Th was obtained.Combined with error of the sample purity and thickness,the fitting flight distance,relative standard deviation of TCS for ^(16)O from ENDF/B-Ⅶ.1,and experimental statistical error,the uncertainty of experimental data were calculeted to be 3.25%-4.51%in the energy range from 0.02 to 0.1 eV.The results show that the measured data of TCS of Th are good agreement with the evaluated data of ENDF/B-Ⅶ.1 in the energy range from 0.02 to 0.1 eV.In the thermal energy range(E<0.02 eV),thermal neutron scattering(TNS)effect of Th in ThO_(2),which is characterized by Bragg-edges,is evident and similar for U in UO 2 in ENDF/B-Ⅶ.1.

关 键 词：TMSR-PNS 全截面 ThO_(2) 透射法 

分 类 号：TL329[核科学技术—核技术及应用]