用于铀微粒年龄测量的铀钍氧化物混合微粒SIMS测量研究

放射性材料的年龄信息是一项重要的溯源指纹特征,铀微粒年龄测量研究对于核取证技术应用具有重要意义。本工作通过使用二次离子质谱（SIMS）、电感耦合等离子体质谱（ICP-MS）测量自制单分散铀钍氧化物混合微粒获得了单个微米级微粒中铀钍比值的相对灵敏度因子（RSF_Th/U）,结合扫描电子显微镜（SEM）等常规分析技术,确定了最佳测量条件,探索了微米级铀钍混合微粒的SIMS测量方法。测量结果表明,对于粒径为2~3 μm的混合微粒,不同微粒间²³²Th/²³⁸U比值的相对标准偏差小于3%(n=12),平均RSF_Th/U为1.259±0.032。通过测量年龄已知的铀同位素固体标准物质CRM970对RSF_Th/U进行了验证。结果表明,对于粒径为5~10 μm的CRM970铀粉末样品,年龄测量结果准确,相对标准偏差为3%(n=16)。该方法受干扰信号影响较小,测量结果稳定,可用于微米级铀微粒年龄的测量。     

人体内铀、钍和铯含量的检测

采用电感耦合等离子质谱法,检测了正常成年人体内铀、钍和铯的含量,分析方法用参考物质进行比对。结果表明,浓度值存在地区性差异,组织中铀、钍浓度,皆以河北省为最低,而铯浓度以山西省为最低。与国外相比,除了肾铀浓度明显偏低和肺钍浓度偏高外,其他数值基本相当。     

二（2—乙基己基）亚砜和磷酸三丁酯萃取铀,钍性能的比较

对二(2-乙基己基)亚砜(DEHSO)和磷酸三丁酯(TBP)萃取Th、U的性能进行了比较,研究了水相HNO_3浓度、萃取剂浓度、温度等因素对萃取Th、U的影响。DEHSO与U、Th和HNO_3形成的萃合物为UO_2(NO_3)_2·2DEHSO,Th(NO_3)_4·2DEHSO和HNO_3·DEHSO。在本实验浓度条件下测得萃取U、Th及NHO_3反应的平衡常数为14.9、0.027、0.13,U、Th萃取反应的热焓为-44.30和-42.50kJ/mol。同时试验了有机相中U(Ⅵ)和Th(Ⅳ)的反萃。     

两种测定铀、钍含量方法的比较

用中子活化分析和厚源α－计数两种方法测定了５１个唐三彩马的铀和钍含量，并对结果进行了比较。在采用厚源α－计数法技术来决定铀和钍对标本提供的年辐射剂量时，可以用总α－计数率来计算。     

EFFECT OF THE RATIO Th/U ON TL DATING ACCURACY

ＥＦＦＥＣＴＯＦＴＨＥＲＡＴＩＯＴｈ／ＵＯＮＴＬＤＡＴＩＮＧＡＣＣＵＲＡＣＹ￥Ｐ．Ｌ．Ｌｅｕｎｇ（梁宝鎏）；ＭｉｃｈａｅｌＪ．Ｓｔｏｋｅｓ（ＤｅｐａｒｔｍｅｎｔｏｆＰｈｙｓｉｃｓａｎｄＭａｔｅｒｉａｌｓＳｃｉｅｎｃｅ，ＣｉｔｙＰｏｌｙｔｅｃｈｎｉｃｏ...     

用厚源α计数测定TL和ESR年代中的钍、铀年剂量

本文叙述了用厚源α计数技术测定TL和ESR年代中钍系和铀系年剂量的原理和方法。该方法主要优点是测定α年剂量时,可将计数率直接代入生龄公式,不需要计算钍、铀含量和剂量率转换因子。但在估算β和γ年剂量时,必须假定样品中的钍、铀放射性是相同的,或者用“对”技术来确定钍、铀含量。     

SYSTEMATIC ERROR FROM Th/U RATIO IN LUMINESCENCE AND ESR DATING

ＳＹＳＴＥＭＡＴＩＣＥＲＲＯＲＦＲＯＭＴｈ／ＵＲＡＴＩＯＩＮＬＵＭＩＮＥＳＣＥＮＣＥＡＮＤＥＳＲＤＡＴＩＮＧＬｉＳｈｅｎｇｈｕａａｎｄＭａｎ－ＹｉｎＷｏｎｇＴｓｏ（ＲａｄｉｏｉｓｏｔｏｐｅＵｎｉｔ，ＵｎｉｖｅｒｓｉｔｙｏｆＨｏｎｇＫｏｎｇ，ＨｏｎｇＫ...     

Preliminary study of the tight lattice pressured heavy water reactor loaded with Pu／U and Th／U mixed fuels

To improve nuclear fuel utilization efficiency and prolong fuel cycle burn-up,a tight ptich lattice pressured heavy water reactor was investigated as an alternative of next generation of power reactors.It is shown that the high conversion ratio and negative coolant void reactivity coefficient are challenges in the reactor core physics designs.Various techniques were proposed to solve these problems.In this work.a tight pitch lattice and mixed fuel assemblies pressured heavy water reactor concept was investigated.BY utilizing numerical simulation technique,it is demonstrated that reactor core mixed with Pu/U and Th/U assemblies can achieve high conversion ratio(0.98) ,long burn-up(60GWD/t)and negative void reactivity coefficients.     

用α能谱法测定样品中~(233)U和~(232)U的相对含量

钍是一种潜在的核燃料。据国际原子能机构估计,目前已探明有开采价值的钍资源大致和铀相等。钍的充分利用可以大大丰富核能资源,增加核燃料储备。 钍铀核燃料循环的一个主要技术问题是钍在反应堆中受中子照射后,除生成有用的核燃料~(233)U外,还会产生~(232)U,一般化学方法不能使它与~(233)U分开。由于~(232)U的衰变子体放出能量     

238U and 232Th concentrations measured in different medical drugs by using solid-state nuclear track detectors and resulting radiation doses to the skin of patients

Urban populations in Morocco receive free medical drugs as prescribed by doctors in district health centres.To explore the exposure pathway of ~(238)U and~(232)Th and their decay products on the skin of patients,these radionuclides were measured in various medical drugs by using solid-state nuclear track detectors(SSNTDs).The measured concentrations range of ~(238)U and ~(232)Th in the medical drug samples of interest vary from(4.3±0.3) to(11.1±0.7) mBq 1~(-1) and(0.49±0.03) to(1.3±0.1)mBq 1~(-1),respectively.A new dosimetric model,based on the concept of specific alpha-dose and alpha-particle residual energy,was developed for evaluating radiation doses to skin following the application of different medical drugs by patients.The maximum total equivalent effective dose to skin due to the ~(238)U and ~(232)Th series from cutaneous application of different medical drugs by patients was found to be 2.8 mSv year~(-1) cm~(-2).     

稳态计算法分析Purex流程中U/Pu分离工艺铀酸分布

研究了Purex流程中U／Pu分离段还原剂从一端加入时铀酸分布的稳态计算方法。计算结果与串级实验结果吻合较好。在所选几种工艺条件下，对铀酸分布进行了计算，并根据计算结果对Purex流程中采用水溶性还原剂时U／Pu分离工艺条件进行了分析。     

N,N-二甲基羟胺用于铀钚分离多级反萃实验研究和相应的计算机程序

建立了多级混合澄清槽稳态趋近数学模型 ,并在此基础上编写了计算机模拟程序MIXEX2。进行了N ,N 二甲基羟胺 (DMHAN)作为 1B槽还原反萃剂微型槽实验和MIXEX2计算程序的验证实验。结果表明 :以DMHAN为反萃剂的 1B槽 ,在设定工艺条件下能够有效地实现铀钚分离 ,钚中去铀的分离系数和铀中去钚的分离系数高达 1 0 4 以上 ;程序计算的酸、铀和钚的浓度剖面与实验浓度剖面符合良好 ,表明计算机模拟程序MIXEX2可以很好地预期萃取器的运行结果     

Measurement of the 232Th(n,f)cross section in the 1-200 MeV range at the CSNS Back-n

The 232Th(n,f)cross section is very important in basic nuclear physics and applications based on the Th/U fuel cycle.Using the time-of-flight method and a multi-cell fast-fission ionization chamber,a novel measurement of the 232Th(n,f)cross sec-tion relative to 235U in the 1-200 MeV range was performed at the China Spallation Neutron Source Back-n white neutron source(Back-n).The fission event-neutron energy spectra of 232Th and 235U fission cells were measured in the single-bunch mode.Corrected 232Th/235U fission cross-sectional ratios were obtained,and the measurement uncertainties were 2.5-3.7％for energies in the 2-20 MeV range and 3.6-6.2％for energies in the 20-200 MeV range.The 232Th(n,f)cross section was obtained by introducing the standard cross section of 235U(n,f).The results were compared with those of previous theoreti-cal calculations,measurements,and evaluations.The measured 232Th fission cross section agreed with the main evaluation results in terms of the experimental uncertainty,and 232Th fission resonances were observed in the 1-3 MeV range.The present results provide 232Th(n,f)cross-sectional data for the evaluation and design of Th/U cycle nuclear systems.