高放废液中~(93)Zr的放化分离

本工作建立了以硅胶吸附法为主的与TBP萃取相结合的从高放废液中分离93Zr的放化流程。该流程对γ核素137Cs2、41Am1、54Eu的去污因子均大于105,对137Cs的去污因子大于108,通过低本底液闪谱仪和MC-ICP-MS对样品的测量,没有发现90Sr-90Y和Pu的高能峰及151Sm的质量峰,证实得到了放化纯的93Zr样品。整个流程的化学回收率稳定在70%左右。     

从高放废液中系统分离~(79)Se、~(93)Zr、~(107)Pd的方法

本工作以75Se、95Zr、109Pd为指示剂,试验并建立了以1 mol/L HNO3为上柱液介质和洗涤液,在DMG色层柱、硅胶柱、Bis-Ⅱ色层柱上分别选择性吸附Pd、Zr、Se,然后分别解吸的系统分离流程。该流程对Se的回收率接近90%,对Zr、Pd的回收率均大于90%,对90Sr、137Cs、152Eu等核素的去污因子均高于103。     

核反应堆中高能中子份额的测量

开展了铀、镎及裂变产物在阴离子交换树脂和TBP萃淋树脂上的吸附行为研究,建立了大量铀中微量镎的去除方法。该流程铀的化学收率约90%;对Np、Ce、Ba、La的去污因子大于1×104,对Nd、Ru的去污因子为1×103,对Zr、Nb的去污因子约为1×102。应用该放射化学分离流程,分别利用238U(n,2n)237U反应,测量了堆中高能中子(6 MeV)的注量率;利用238U(n,γ)239U反应,测量了堆中热中子的注量率,得到了反应堆中高能中子(6 MeV)所占的份额。     

秦山、大亚湾核电厂周围地区土壤对~(137)Cs吸收的研究

进行了三种不同的~(137)CS溶液分别通过秦山、大亚湾核电厂周围七个地区农业土壤耕作层(0～20cm)的试验,这三种~(137)Cs溶液为:(1)同体积(40mL),同比活度(3.7×10~4Bq/L)~(137)Cs溶液;(2)同体积(40mL),不同比活度(3.7×10~3,3.7×10~4,3.7×10~5Bq/L)~(137)Cs溶液;(3)不同体积(40,80,120mL),同比活度(3.7×10~4Bq/L)~(137)Cs溶液。结果表明:土柱上层1cm的比活度和~(137)Cs溶液比活度之间符合y=A·x~B关系;~(137)Cs溶液体积之间符合y=A Bx关系。上层1cm的土壤对~(137)Cs滞留量一般在90％～95％以上,上层5cm的土壤对~(137)Cs滞留量均为100％,滤液为本底水平。可以认为:在土壤受到溶液态~(137)Cs污染条件下,采取铲除表层的方法可有效减轻或消除污染。     

样品厚度对实验室无源效率刻度技术测定~(137)Cs和~(210)Pb的影响

为评价样品厚度对实验室无源效率刻度(LabSOCS)测定环境放射性核素的影响,用LabSOCS技术对不同黄土样品厚度进行了模拟计算和实际测定对比。模拟计算的137Cs和210Pb的探测效率均随样品厚度呈对数函数关系下降(P0.001),当样品厚度从5 mm增至80 mm时,对137Cs和210Pb的探测效率分别减少68%和83%。样品厚度对LabSOCS技术测定137Cs和210Pb比活度的影响均不明显,但对137Cs的分析误差有明显的影响,对210Pb分析误差的影响较小,15 mm是影响LabSOCS技术测定137Cs和210Pb分析误差的临界样品厚度。这一结论对于提高LabSOCS技术测定土壤样品中137Cs和210Pb的分析精度具有指导意义。     

一种快速放化分离~(72)Ga的方法

以Fe(OH)3沉淀和异丙醚萃取为主要分离方法,建立了一种简单、有效的快速放化分离微量72 Ga的流程。流程对Ga的化学回收率大于90%,对裂变产物元素的去污因子均大于103,对土壤基体的去污因子为4.1×103,分离时间小于50min,可以满足快速放化分离72 Ga的需求。     

环境水体中~(90)Sr和~(137)Cs的监测方法

以国家标准为基础,对环境水体中~(90)Sr和~(137)Cs的监测方法进行了技术改进:增大采样量(50~100L),选择高效沉淀剂和低水平探测器。采用改进后的方法测定了50~100L水中~(90)Sr和~(137)Cs,结果显示:~(90)Sr和~(137)Cs的浓集效率分别为(91.3±2.8)%和(97.2±1.4)%;~(90)Sr的全程回收率为81.5%±2.8%;~(90)Sr和~(137)Cs的探测下限分别为8.6×10~(-4) Bq/L和9.8×10~(-4) Bq/L。50L水中~(90)Sr的比对结果显示,4家实验室测定值与标称值的相对偏差均小于11%。以上结果表明,该方法适用于环境水中微量~(90)Sr和~(137)Cs的监测,可满足环境本底调查和环境监测的要求。     

CuFC吸附-微滤工艺处理含~(137)Cs废水

采用单级亚铁氰化铜(CuFC)吸附-微滤工艺去除实验模拟废水中的~(137)Cs,研究废水中~(137)Cs初始活度浓度(C0)、吸附时间、pH值、竞争离子以及CuFC投加量对去污因子的影响。分别用去离子水、地表水和海水配制模拟废水,当模拟废水中~(137)Cs的初始活度浓度分别为4.24×10~5、2.84×10~5、2.84×10~5 Bq/L,吸附时间为90min,pH值为7,CuFC投加量为80 mg/L,不投加竞争离子时,本工艺的去污因子分别达到2.06×10~4、1.62×10~4和9.36×10~1,说明CuFC吸附-微滤工艺是一种高效的含~(137)Cs废水处理工艺,且具有可观的应用前景。     

~(137)Cs在水稻体内及土壤中动移、累积与分布

~(137)Cs溶液污染水稻试验表明:苗期至孕穗期水稻对~(137)Cs吸收速度最快,抽穗期趋于平缓,灌浆期又有回升。~(137)Cs沿着水稻的地下器官向地上器官,营养器官向生殖器官转移。水稻中~(137)Cs比活度和土壤污染量之间存在一定正相关,但只有当土壤污染量提高到370Bq/g土时,水稻中~(137)Cs比活度才极显著上升。不同土壤栽培的水稻对~(137)Cs吸收能力不同,仅有深圳土壤栽培的水稻对~(137)Cs吸收能力极显著高于其它四个地区土壤。污染期不同,水稻对~(137)Cs吸收量也不同,灌浆期~(137)Cs溶液污染对水稻的影响极显著高于其它时期。     

固相萃取片法分析土壤样品中的~(239)Pu

为了对核设施及周边环境的放射性污染水平进行有效监测,需要对土壤样品中的~(239)Pu进行分析。本研究考察了静态吸附中介质酸度、接触时间以及温度对~(239)Pu在固相萃取片上的吸附影响,确定最佳吸附条件;采用柱实验进行验证,以固相萃取片法为分离纯化手段,采用高酸上柱,低酸条件下还原解吸,以低本底液闪谱仪为放射性测量手段,建立快速分析土壤中~(239)Pu的方法。该方法可测土壤样品量为10g,使用8mol/L HNO_3浸取灰化后的模拟污染土壤样品,模拟土壤样品中~(239)Pu的化学回收率为78.9%,比活度探测下限为3.7 Bq/kg,全流程分析时间小于3h,对核素~(137)Cs、~(90)Sr-~(90)Y、天然铀、~(241)Am、~(99)Tc去污效果良好,该方法可广泛应用于环境土壤样品的~(239)Pu分析。     

靶向CD93分子探针制备及其生物学实验研究

CD93分子作为一种新型新生血管生成激活剂,有可能成为肿瘤监测的重要分子靶点,因此制备125I标记抗CD93单抗(125I-anti-CD93 mAb),研究其在荷瘤鼠体内生物学分布及磷屏显像特点,探讨其对A549肺癌靶向性及CD93阳性肿瘤监测的可行性。本文制备125I-anti-CD93 mAb及125I-IgG并进行鉴定;建立A549肺癌荷瘤小鼠模型,经尾静脉注射125I标记抗CD93单抗,并设125I-IgG为对照组,注药后不同时间进行生物学分布及磷屏放射自显影;肿瘤组织行HE染色及CD93免疫组织化学染色;采用统计软件对定量数据(x+s)进行统计学处理,组间数据用t检验,P<0.05为差异有统计学意义。结果表明,125I-anti-CD93 mAb及125I-IgG标记率、放射性比活度、放化纯度分别为91.37%和90.24%,1096.44 MBq/mg和1082.88 MBq/mg,96.49%和94.82%,放置72 h后两标记物的稳定性仍>90%,两者间无统计学差异(生理盐水组P=0.93,t=0.09,血清组P=0.13,t=1.90)。荷瘤鼠生物学分布结果显示125I-anti-CD93 mAb主要经肝肾代谢,注射后48 h时肿瘤组织放射性摄取率为(6.42±0.71)%ID/g,T/NT(瘤/对侧肌肉)摄取比值为4.45±0.86,显著高于对照组125I-IgG组(2.45±0.33/1.71±0.24),P<0.05,t=3.07和P<0.01,t=5.10。动态全身磷屏自显影结果可见,24 h两组小鼠轮廓清楚,48 h时实验组肿瘤显像最清晰,肿瘤放射性摄取比(肿瘤/对侧肌肉)为3.34±0.18,明显高于对照组(1.62±0.19),P<0.01,t=6.52。免疫组化染色结果证实肿瘤高表达CD93。125I-anti-CD93 mAb制备简便,对A549肺癌组织靶向性好,有望成为CD93阳性肿瘤监测的新型分子探针。     

Transmutation of Zirconium-93 in High-flux Blanket of Fusion Neutron Source

Amongst fission products discharged from a fission reactor, mainly iodine and technetium are considered as of primary concern. Their transmutation has been of high priority to reduce the long-term consequences of nuclear energy generation. So far little attention was given to radioactive ⁹³Zr, but its hazard appears to be rather substantial. The importance of ⁹³Zr transmutation is emphasized in the present paper. It is demonstrated that the fusion driven neutron source with high-flux blanket can be applied to transmute ⁹³Zr sufficiently and resolve the problem of its accumulation within the time period of several decades.     

Method for Decision of Nuclear Reaction Model Parameters

Application to decontamination is proposed of microwave discharge plasma in carbon tetrafluoride and oxygen mixture at atmospheric pressure. Preliminary cold experiments were conducted using cobalt oxide deposited on stainless steel plate. Fluorine atoms proved to be generated in high concentration in the plasma, which fluorinated the deposited metal oxide into volatile gaseous form. Upon plasma irradiation during about 200 s, the cobalt oxide deposit was removed to 100% from plate surface. Thermodynamic equilibrium calculations on CF₄-O₂ systems containing cobalt served to elucidate the mechanism of metal oxide removal by microwave discharge plasma, and similar calculations on systems containing actinides (U, Pu etc.) and lanthanides (La, Gd etc.) indicated that the process should be applicable also to the removal of these radioactive elements. It is concluded from the experimental and calculated results that decontamination is basically feasible with the proposed method of using microwave discharge plasma in a CF₄-O₂ system at atmospheric pressure.     

Measurement of keV-Neutron Capture Cross Section of 96Zr

The neutron capture cross section of ⁹⁶Zr at incident neutron energies from 15 to 100 keV has been measured by the time-of-flight method. Capture γ-rays were detected with an anti-Compton NaI(Tl) spectrometer, and the pulse-height weighting technique was applied to derive the neutron capture cross section. The present measurement provided the capture cross section as a function of incident neutron energy in the keV region. The results were compared with previous measurements and cross section data in the evaluated nuclear data libraries, JENDL-4.0, JENDL-3.3, ENDF/B-VII.0, and ENDF/B-VI.8. The present results revealed considerable underestimation of the evaluated cross sections in the high-energy region of 35–100 keV.     

Measurement of Neutron Capture Cross Sections with Fe-Filtered Beam

The neutron capture cross sections of ⁹³Nb, ¹¹⁵In, ¹²⁷I, ¹⁶⁵Ho, ¹⁸¹Ta, ²³²Th and ²³⁸U were measured using the Fe-filtered beam. A 15-cm thick Fe filter was placed in the neutron beam produced by the KUR 46-MeV electron Linac and capture prays were detected by two C₆F₆ scintillation detectors located at an 11.7 m-flight path. The pulse-height weighting technique was used to determine the relative capture pray detection efficiency. The neutron flux was measured by the same detectors, whose detection efficiency for the 480-keV pray from the ¹⁰B(n, α₁) reaction was calibrated by the saturated resonance capture in Ag at 5.2-eV. Self-shielding and multiple scattering corrections were applied to the data. The results of 24-keV capture cross sections are 340, 770, 780, 1,280, 880, 520 and 520 mb for ⁹³Nb, ¹¹⁵In, ¹²⁷I, ¹⁶⁵Ho, ¹⁸¹Ta, ²³²Th and ²³⁸U, respectively. Total errors are 5 to 8%, with an estimated systematic error of 4%. The discrepancy between the present results and other data measured recently is within 10%.     

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.