生产堆元件燃耗测定中试样的溶解

研究了生产堆元件燃耗测定中试样切片的溶解。建立了HCl溶解—HNO_3氧化和Hg(NO_3)_2催化—HNO_3溶解两种方法。溶解了一块辐照元件的两组对称片,所得溶解液能满足燃耗测定中分析工作对料液的要求。     

用马尿酸-丁醇作萃取剂从钇族希土中分离钇

(1)用0.04M的马尿酸-丁醇溶液作萃取剂萃取希土,在pH?6时,钇位于轻镧元素部分的钕与钐之间,其萃取率低于其他钇族希土元素.可借此性质自钇族希土中分离钇. (2)经过三级萃取,可自含70.5%Y_2O_3的钇族希土原料中,获得纯度为90.8—93.6%的Y_2O_3,收率约35%.当用二次循环萃取方式时,收率大约提高至55%. (3)研究了氨水添加量、萃取级数、溶液中希土浓度、水相与有机相的体积比等因素对萃取分离钇的影响。     

以水杨酸-丁醇作萃取剂从钇族希土元素中分离钇

我们测定了水杨酸-丁醇萃取钍和十一个希土元素的萃取率,观察到在pH=5.5—7时钇的萃取率位于轻镧采元素的钕与钐之间,在同一pH值下,钇的萃取率较重镧系元素低,因此有可能从钇族希土元素中分离钇.这样,我们在半逆流连续萃取装置中进行了从钇族希土元素中分离钇的研究.系统地做了氨水加入量、水杨酸浓度、希土溶液浓度等条件试验.在适当的条件下经一次萃取,Y_2O_3纯度可从70%提高到95—98%,收率为57%左右.钇的交叉部分经二次循环,可得纯度大于95%的Y_2O_3,总收率为68%.因而证实了上面的推断是正确的,同时提出了一个成本便宜、操作简便,能连续、快速分离出纯度为95—98%的Y_2O_3的新方法.     

用磷酸二丁酯萃取希土元素和钍

1.測定了在不同硝酸酸度下La,Ce(Ⅲ、Ⅳ),Pr,Nd,Sm,Gd,Dy,Ho,Y,Er,Yb,Th(Ⅳ)等的0.05M硝酸盐溶液被1MHDBP-CCl_4萃取时的萃取率和上述各对希土元素間的分离因数。2.三价希土元素的萃取率均随硝酸酸度的增加(从0至6N)而下降;而四价铈的萃取率較高,并随硝酸酸度的增加(从1至11N HNO_3)而緩慢地上升;钍在0.2至9.1N HNO_3范围內均全部被萃取。3.在不同硝酸酸度下的萃取率-原子序图属轉折变化,卽萃取率随原子序的增大而增大,在增大的过程中发生較明显而突出的轉折。钇位于重镧系元素部分的Ho和Er之間。4.大部分元素对之間的分离因数(β)均随硝酸酸度的增大而下降。在較低的酸度下,有些分离因数比用磷酸三丁酯时还高一些,故有可能在較低的酸度下利用HDBP作萃取剂自铈族希土中分离四价铈和钍,或用于分离β值較大的几对希土元素,或将希土分为铈族和钇族。实驗表明,經一次萃取,在水相中可获得几乎不含钇族希土的铈族希土。5.为了探求分离铈的条件,較系統地研究了用HDBP-CCl_4萃取Ce(Ⅲ、Ⅳ)时HDBP浓度,Ce(Ⅲ、Ⅳ)浓度,在硝酸、硫酸或两者的混合酸介貭中等不同因素对萃取的影响。結果表明,当酸度为3.59N HNO_3时,HDBP-CCl_4浓度在0.5—1M內Ce(Ⅲ)的萃取率約为零,而Ce(Ⅳ)的萃取率仍很高,故在此HDBP浓度范围內有可能使Ce(Ⅲ)和Ce(Ⅳ)彼此分离。在硝酸介貭中(3.59NHNO_3)萃取时,Ce(Ⅳ)的飽和浓度約为83克CeO_2/升1M HDBP-CCl_4(27℃);而在混合酸介貭中(3.8N HNO_3+H_2SO_4,当量比HNO_3/H_2SO_4=1)約为60克CeO_2/升1M HDBP-CCl_4(26℃)。从硫酸介貭中萃取Ce(Ⅳ)时,加入少量硝酸可显著改善分层情况。     

同位素稀释法测定希土元素的研究——(Ⅱ)微量希土总量的测定

本文研究了利用~(144)Ce-~(144)Pr作为示踪剂,用均匀沉淀分离并与铀试剂Ⅰ分光光度法结合的同位素稀释测定微量希土总量的方法。9倍于希土含量的Cu、Al、VO_3~-、Cr~(3 ),20倍的Ca、Zr、Ti、Fe和90倍的Zn、Pb对本法测定希土无干扰。在1g铀样中希土含量约100μg时,测定误差不超过10%。本法有可能用于工业生产中铀产品的微量希土总量的测定。     

鈾中痕量希土元素的紙条反相分配层析法的分离及測定(TNNA-NaNO_3体系)

近年来发展了一种无机紙上反相分配色层分离法。此法是将有机萃取剂涂在滤紙上作固定相,以无机酸或盐的水溶液为流动相。关于这种方法近来陆續有所报导,它能在不同程度上分离希土元素和許多性貭相近的金属离子。鉴于以镧或钇作富集剂,从大量鈾中分离和检出中子截面較大的希土元素如钐、铕、钆等,这方法是有一定实际意义的。本实驗在以往工作的基础上,进一步探討了以上元素在三正壬胺-硝酸鈉(TNNA-NaNO_3)体系中的行为。实驗結果指出,希土元素之間彼此不能分离,而希土元素与鈾分离良好,可从10毫克鈾中检出1微克希土元素,或从7毫克鈾中析离1微克希土元素。此外,用微量絡合滴定法测定了紙斑上的希土。     

用质谱法测定堆元件燃耗监测核素~(148)Nd的丰度和含量

用质谱法测定了堆元件燃耗监测核素~(148)Nd的丰度和含量。用测得的~(148)Nd的丰度、含量值及其他参数,计算出堆元件的燃耗值。测定的~(148)Nd的丰度和含量沿元件棒轴向分布与理论曲线相一致。测得的元件燃耗值与用重同位素比值法和放化法测得的燃耗值分别在4.0％和2.8％的误差范围内相符。     

用质谱法测定堆元件燃耗监测核素~(148)Nd的丰度和含量

用质谱法测定了堆元件燃耗监测核素~(148)Nd的丰度和含量。用测得的~(148)Nd的丰度、含量值及其他参数,计算出堆元件的燃耗值。测定的~(148)Nd的丰度和含量沿元件棒轴向分布与理论曲线相一致。测得的元件燃耗值与用重同位素比值法和放化法测得的燃耗值分别在4.0％和2.8％的误差范围内相符。     

阴离子交换分离控制电位库仑法测定辐照后核燃料元件溶解液中的钚

本文提供了一个阴离子交换分离,控制电位库仑法测定辐照后核燃料元件溶解液大量铀中小量钚的方法。钚(Ⅳ)在7.5 NNO_3介质中吸附在711型树脂床上,用7.5N HNO_3洗涤铀、裂变产物和其它杂质元素后,用0.5N HNO_3-0.02M NH_2OH·HCI洗涤钚,最后以1 NHN0_3为支持电解质,金丝网作工作电极进行库仑测定。测定范围为1—4 mg钚。用化学校正方法,对辐照后核燃料元件溶解液样品7次平行测定的相对标准偏差为±0.33%。     

石墨中痕量总希土的分光光度测定

本工作改进了希土-偶氮胂酸Ⅲ有色络合物的显色及其测定条件,提高了测定方法的灵敏度;用增加掩蔽剂磺基水杨酸和抗坏血酸的浓度的办法来提高干扰元素的允许量。从而拟定了不必经过分离而直接测定核纯石墨中痕量总希土的方法。此外,为了测定纯度较差的石墨中的总希土,亦研究了应用8-羟基喹啉-氯仿溶液萃取分离其他杂质的条件。此两种方法均较准确、快速,全部分析手续可在3—4小时内完成。控制试验表明,总希土的平均回收率分别为98%和93%。按取样量为1克计算,方法的测定下限为1×10~(-5)%。     

Preparation of Zn/TiO2 powder and its photocatalytic performance for oxidation of P-nitrophenol

Zn-doped TiO2 catalysts were prepared using a sol-gel method and characterized by XPS,UV-Vis, BET, XRD in this study. Under the irradiation of simulant sunlight, the photocatalytic activity for the degradation of p-nitrophenol was studied too. After irradiation for 2.5 h, the degradation percentage of p-nitrophenol could rise to more than 80 %. The results showed that the spectrum absorption band edge of Zn/TiO2 powder does not broaden obviously comparing with pure TiO2 powder. Zinc exists as Zn （11）. When calcined at 973 K, there is a new phase as ZnTiO3 in Zn/TiO2 catalyst. The order of photocatalytic activity of Zn/TiO2 catalysts calcined at different temperatures for p-nitrophenol is 773 K 〉 673 K 〉 873 K 〉 573 K 〉 973 K and the photocatalytic activity of Zn/TiO2 catalyst calcined at 773 K is better than TiO2 catalysts heated at the same temperature, and outclasses that of commercial TiO2 catalyst. It also showed that the photocatalytic degradation of p-nitrophenol follows first-order kinetics under the irradiation of simulant sunlight.     

Current status of radiation therapy for prostate cancer

Radiotherapy for the treatment of prostate cancer has been extensively explored in the past. Along with the comprehensive understanding of the biology of prostate cancer and rapid advances in terms of technology, the out- come of treatment for the patients with prostate cancer has improved. The authors review radiotherapy as the primary treatment for the disease, with particular emphasis on the technological advances from both the radiobiological and radiophysics aspects. Nonconventional fractionated irradiation like hyper- or hypo-fractionation has been imple- mented in the clinic, the final results still need to be confirmed in the future. Technological advances like IMRT, IGRT, in the last two decades have significantly improved the delivery of external radiotherapy to the prostate. This has re- sulted in an overall increase in the total dose that can be safely delivered to the prostate, which has led to modest im- provements in the biochemical outcome. However, establishing the standard therapy for prostate cancer remains con- troversial. It is hoped that the next decades will bring continued advances in the development of biologicals that will further improve current clinical outcomes.     

The control system for SSRF injection and extraction

This paper introduces the injection and extraction control system design for SSRF,which is a distributed control system aimed at stability and reliability of the pulse power supplies,PPS(Personnel Protection System)and MPS(Machine Protection System).The hardware environment is mainly based on PLC(Programmable Logic Con- troller),and ARM(Advanced RISC Machine)is also applied for studying stability of the power supplies.WinCC and EPICS(Experimental Physics and Industrial Control System)have been selected as the platforms of SCADA(Super- visory Control and Data Acquisition).For unifying the interfacing to the control computer,all front-end equipments are connected via Industrial Ethemet.     

水平管内含空气蒸汽强制对流冷凝换热模型研究

为研究含空气蒸汽在水平管内强制对流冷凝换热特性,基于对传热传质过程的分析,建立了管内为环状流与波状流条件下的流动冷凝换热模型。从潜热、显热和液膜3个环节对整个换热过程进行建模,最终得到计算局部冷凝换热系数的理论关系式。模型预测结果与实验数据的对比表明,二者相对偏差在±20%以内,验证了该换热模型的准确性与适用性。通过进一步的研究发现：从换热管入口至出口,随着冷凝的进行,管内换热主要热阻由液膜热阻向气液界面的凝结热阻转变;主流气体对流换热过程基本可忽略。     

Investigations on landmine detection by BF3 detector

Experiments were carried out to investigate the possible use of neutron backscattering for the detection of polyethylene (PE) sample buried in the soil. In detection of landmine by neutrons, the neutron detector and its shield play an important role. In this paper, the effects of graphite, heavy water, polyethylene and boric acid moderators on the flux of back scattered neutrons were investigated. We have also experimentally verified the effect of BF3 detector shield and obtained good agreement with theory.     

Web Services interface of SSRF archive data analysis system

Accelerator database stores various static parameters and real-time data of accelerator. SSRF (Shanghai Synchrotron Radiation Facility) adopts relational database to save the data. We developed a data retrieval system based on XML Web Services for accessing the archive data. It includes a bottom layer interface and an interface applicable for accelerator physics. Client samples exemplifying how to consume the interface are given. The users can browse, retrieve and plot data by the client samples. Also, we give a method to test its stability. The test result and performance are described.     

有效探测面积大于1000 cm2的正比计数器测量系统性能测试

为对自制的活性面积高达1 000 cm²的大面积源进行表面发射率定值,同时作为现有2πα、2πβ表面发射率标准装置能力的扩充,研制了一套内置式大面积2π多丝正比计数器测量系统,并利用活性区直径为8 mm的²⁴¹Am点源及活性区面积为10 cm×15 cm的大面积²⁴¹Am和⁹⁰Sr-⁹⁰Y源对其进行计量学性能测试。结果表明：计数器内计数响应均匀性优于±0.4%,有效探测面积达1 400 cm²;所得²⁴¹Am源高压坪曲线的坪长为1 400 V,坪斜为0.27%/100 V,坪区内计数变化为0.87%;⁹⁰Sr-⁹⁰Y源高压坪曲线的坪长为300 V,坪斜为0.75%/100 V,坪区内计数变化为0.80%;10次测量重复性好于0.4%,8 h内短期稳定性好于0.3%,1 a内长期稳定性好于0.8%。     

Assessment of radioactivity levels in some oil samples from the western desert, Egypt

Distributions of natural gamma-emitting radionuclides were determined in 93 oil samples collected from some petroleum fields in the western desert of Egypt. The radioisotope activities in the area under investigation lay in the range of (21 ± 4) to (38 ± 13) Bq?L-1 for 226Ra, (9 ± 2) to (15 ± 5) Bq?L-1 for 232Th, and (154 ± 28) to (303 ± 54) Bq?L-1 for 40K. The mean values were 27, 12, and 201 Bq?L-1, respectively. Among oils, variations in radionuclide ac- tivities could be on account of differences in TDS, HCO3, and Ba, with high or low pH. In this environment, oil prop- erties differently affected the mobilization of natural radionuclides. The range of 226Ra variation had been compared with available data from other countries. The calculated absorbed dose rate ranged from 22.33 to 32.66 nGy?h-1 in lo- cation (B) and (E) respectively, which was less than the accepted value.     

Preparation and properties of 117m Sn(IV)-TTHMP in in-vitro and in small animals

In this work,TTHMP was synthesized and labelled with 117m Sn.The preparation conditions,stability and lipophilicity of 117m Sn(IV)-TTHMP were investigated.Biodistribution of the complex in rabbits and mice was studied.It was found that the quantity of TTHMP and pH value of the prepararion solution had vital effects on the labeling yield of 117m Sn(IV)-TTHMP.It was also found that 117m Sn(IV)-TTHMP was hydrophilic and stable at room temperature and 37℃ in open air 117m Sn(IV)-TTHMP showed unexpectedly high bone uptake and bone-to-blood ratio in the animals.This made it potentially useful as an reagent for skeletal scintigraphy and radiotherapy of bone tumors.     

Gamma radiation levels in the ambient environment of the QNPP Base

Monitoring results of gamma dose rate level in 1992～2004 in the ambient environment of the Qinshan Nuclear Power Plants(QNPP)Base,the northeast of Zhejiang Province,are reported in this paper.It is shown that the gamma dose rate of five monitoring sites of 2.5 km to QNPP Base is 84～113 nGy/h,with an average of 96 nGy/h in the 13 years.The average value is close to the background level of 93 nGy/h prior to operation of the QNPP Base,and is lower than the monitoring result of 101 nGy/h at the reference site in Hangzhou City.Within 50 km from the QNPP Base,the cumulative dose rate of the thermoluminescent dosimeter(TLD)is 90 nGy/h,which is lower than the back- ground level of 111 nGy/h.