水力驱动控制棒极限落棒热态原理实验

针对控制棒水力驱动系统在摩擦力卡棒和倒置等极限工况下的停堆问题 ,根据控制棒水力驱动系统的工作原理 ,提出了步进缸内腔卸压的解决方法 ,并在 2 0 0MW低温核供热堆控制棒水力驱动系统的 1∶1实验台架上进行了这种方法的热态实验。结果表明 :控制棒的落棒速度明显提高 ,棒外与棒内差压在卸压一定时间后能够达到较高的数值。说明水力驱动控制棒在热态摩擦力卡棒和倒置等极限条件下 ,能够克服一定量的摩擦阻力或能够克服重力插入堆芯。为控制棒水力驱动系统在摩擦力卡棒和倒置等极限工况下的停堆提供了一种可选择的方案     

水力驱动控制棒冷态极限落棒能力分析

为了验证控制棒水力驱动系统在卡棒和倒置等极限工况下的停堆可靠性，在200MW低温核供热堆控制棒水力驱动系统的1：1实验台架上进行了冷态极限落棒实验，通过对实验结果的分析。得到了在发生卡棒事故时控制棒的落棒能力，揭示了落棒机理，建立了正置时控制棒插入堆芯的模型，并用实验数据验证了该模型的正确性，建立了倒置时控制棒插入堆芯的模型，获得了倒置时控制棒的插棒能力。     

控制棒水力驱动系统不产生弹棒事故的实验研究

控制棒水力驱动系统是一种新型的控制棒驱动机构，它整体封装入压力人与堆习 体化结构设计。本文介绍了由压力筒、水力步进缸、加热器、泵及其设备组成的实验因路和测量系统在高温、高压条件睛压力筒失夺时控制棒的棒位测量实验。实验结果表明，控制棒水力驱动在压力壳失压工况下不产生弹棒事故，系统具有固有安全特性。     

水力控制棒驱动系统失压工况的实验研究

利用200MW低温核供热堆水力控制棒驱动系统的1：1实验台架模拟系统失压况，进行控制棒步升，步降，开阀落棒及关泵开阀落棒实验，并与正常工况下的提棒，落棒的实验结果进行比较，实验结果表明：在系统失压工况下，控制棒能正常提棒，落棒系统失压工况下的弹棒，系统压力与压力壳压力具有瞬时跟随特性，未出现控制棒弹棒事故，对实验的失压速率和事故分析得到的失压速率进行了比较，验证了系统具有良好的安全性和可靠性。     

控制棒水压驱动系统落棒减速部件三维流场分析

控制棒水压驱动系统是清华大学为低温核供热堆研制的新型内置式控制棒驱动技术,控制棒水力减速部件是水压驱动系统的关键部件之一,在保证落棒时间的前提下,通过其对落棒过程进行减速,降低控制棒快速落棒过程的冲击力,避免控制棒十字翼的变形和损坏。本文分析了控制棒水压驱动系统落棒减速机理,利用CFD软件FLUENT对驱动系统水力减速箱流道进行了三维流场数值分析,并分析了对应不同落棒位置水力减速箱流道在不同边界条件下的流场分布特性。在流场分析结果的基础上计算得到了水力减速箱侧壁孔流道和底部缓冲腔流道流量系数随落棒位移的变化,将该结果与驱动系统落棒减速理论模型联立,获得了控制棒落棒位移曲线,理论计算结果同冷态落棒性能实验结果符合得很好,从而验证了流场分析结果的正确性,在此基础上分析了落棒过程减速箱内外差压和落棒速度与水力减速箱流量系数的关系,为控制棒水压驱动系统落棒减速部件的设计和优化提供了指导。     

高温气冷堆控制棒驱动机构冷态落棒试验研究

高温气冷堆控制棒驱动机构是执行反应堆功率调节、紧急停堆的重要核安全设备,具有固有安全特性,当断电后,控制棒能够靠重力快速下落实现停堆。为验证控制棒驱动机构的可靠性,必须对其进行设计分析和试验验证。本文建立了全尺寸的冷态试验台架,并采用1:1的控制棒驱动机构样机,对高温气冷堆控制棒驱动机构的落棒功能进行了验证和分析。进行多次全行程及不同高度的落棒实验,验证落棒过程的稳定性,测定控制棒在冷态条件下的落棒时间、落棒速度,试验结果满足规定的限值。对落棒过程进行分析,建立落棒运动方程式,进而得到控制棒运行速度的解析解。理论及试验的结果符合较好,均表明本文研究的控制棒驱动机构落棒可靠具有固有安全特性,为商用高温气冷堆中的实践应用提供了理论依据。     

控制棒水压驱动系统落棒减速性能实验研究

控制棒水压驱动系统是清华大学为低温核供热堆发明的新型的内置式控制棒驱动技术,控制棒水力减速部件是水压驱动系统的关键部件之一,通过其对控制棒落棒过程进行减速,在保证落棒时间的前提下,降低控制棒快速落棒过程的冲击力。分析了水力减速部件组成和工作原理,确定了水力减速箱侧壁开孔方案,完成了不同开孔方案工况下控制棒水压驱动系统冷态落棒减速性能实验,在实验结果的基础上对比和分析了不同方案下的落棒减速机理和落棒过程特征参数随开孔方案的变化规律。分析结果表明:随开孔面积的增大,落棒时间逐渐减小,落棒峰值速度逐渐增大。在开孔面积大于0.004 m~2时,随开孔面积的增大,落棒峰值速度增大过程趋于平缓,落棒稳定速度和落棒延迟时间变化不大,控制棒触碰碟簧速度缓慢增大。实验研究成果为控制棒水压驱动系统落棒减速部件的理论建模和设计优化提供了基础。     

上置式水力驱动控制棒

为提高200MW低温核供热堆经济性，对控制棒结构进行优化设计。在新的控制棒方案中，将控制棒驱动缸移到堆芯活化区以上，控制棒由浮动式活塞带动上下移动。由于驱动缸移出堆芯，燃料组件排布不再缺角，减小了堆的水铀比和堆内的中子吸收，增加了堆的运行时间。适当地加大驱动缸的直径和壁厚，有效降低了制造难度，提高了控制棒运行的可靠性。通过数值计算，分析了上置式水力驱动控制棒的落棒时间。     

CARR控制棒驱动机构堆外调试试验

中国先进研究堆（CARR）控制棒由磁力驱动。为进行CARR控制棒堆外调试试验,建造了模拟CARR热工水力条件的试验回路。试验中发现驱动机构存在一些问题,提出改进建议,得到CARR工程部和设计者认可。对驱动机构进行了一些改进,试验测量了线圈温度、落棒时间、极限流量和极限载荷等重要参数,试验证明经改进的控制棒驱动机构达到了设计要求。     

200MW核供热堆控制棒水力驱动系统安全特性

２００ＭＷ核供热堆采用控制棒水力驱动系统作为控制棒驱动机构。该系统是以非能动系统为基础设计的，并实现了传动、导向一体化。通过时系统自身固有安全特性及设计安全特性、失压事故下控制棒不发生弹棒的机理以及系统引水管破断冷印剂总丧失量不会导致堆芯裸露的计算结果的分析，表明该系统具有良好的安全特性，在任何失效事故下都能保证反应堆的安全停堆，为具有固有安全特点的２００ＭＷ核供热堆提供了重要的技术支持。     

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.     

The role of AGFA high-energy CR in the calibration and quality control of multileaf collimators （MLC）

Linear accelerators equipped with multileaf collimators （MLC） are becoming more common and are widely used in the intensity-modulated radiotherapy （IMRT）. There is an imperative need to ensure the commissioning specification of the linear accelerators for the sake of quality assurance （QA） and quality control （QC）. This paper is aimed to investigate the role of AGFA high-energy CR （Computed Radiography） in calibrating dynamic multileaf collimators and evaluating the accuracy of the leaf position. The result shows that AGFA high-energy CR can easily and conveniently be used to calibrate MLC and verify its position. Hence, the application of AGFA high-energy CR is proved to be an accurate and time-saving method for routine MLC QC, especially when MLC calibration adjustments are required.