钠冷快中子增殖堆给水流量控制系统方案研究

钠冷快中子增殖反应堆采用三回路系统和直流蒸汽发生器设计,其给水流量控制系统对整个反应堆的安全稳定运行起到了非常重要的作用。根据系统控制要求,分析运行特性,提出了基于钠出口温度不变为主控制量,并采用给水流量需求值作为前馈的串级PI控制方案来调节给水调节阀开度,以及维持给水调节阀前后压力不变来调节给水泵转速。瞬态工况仿真试验验证结果表明,给水流量控制系统能够迅速控制瞬态扰动引起的系统参数变化,满足维持钠出口温度不变和出口蒸汽压力稳定的控制要求。     

蒸汽发生器稳态及瞬态热工特性计算方法探析

为获得华龙一号核电机组ZH-65型蒸汽发生器在瞬态工况下的热工水力参数的变化规律,对立式倒U形管式自然循环型蒸汽发生器的动态特性计算方法进行了研究。经过合理的简化和假设,建立了蒸汽发生器一次侧和二次侧的计算分析理论模型,二次侧两相流采用考虑汽相和液相速度滑移的均相流模型。针对建立的模型给出了数值求解过程,并选择ZH-65型蒸汽发生器10%阶跃降负荷这一典型的瞬态工况进行求解。求解结果与CATIA2等具有成熟工程使用经验的程序计算结果相比吻合较好,表明了本文理论模型和计算方法的正确性,用于工程计算分析是可行的。     

WWER1000堆型卧式蒸汽发生器解体检修辐射防护实践

田湾核电站1、2号机组蒸汽发生器为WWER1000堆型卧式蒸汽发生器,它由容器、传热面、一回路冷却剂集流管、主给水分配装置、应急给水分配装置、蒸汽分离孔板和水下均汽板等部件组成。文章重点对WWER1000堆型蒸汽发生器解体检修的辐射防护实践进行介绍,对田湾核电站历次大修现场辐射水平及集体剂量情况进行分析,并提出后续的优化方向。     

RELAP5应用于PRS系统蒸汽管道隔离阀常关对自然循环建立时间的影响分析

田湾核电厂5&6号机组作为M310改进机型,新增了蒸汽发生器二次侧非能动冷却系统(PRS)作为严重事故预防与缓解措施。蒸汽发生器二次侧非能动冷却系统的蒸汽管道与主蒸汽管道相连,凝水管道与辅助给水系统管道相连。在开展布置工作时发现,发现蒸汽管线非常长,若PRS系统蒸汽管线与主蒸汽管线之间的隔离阀常开,会对PRS系统的正常运行造成影响,因此考虑将PRS系统蒸汽隔离阀的状态由常开变换为常关。本文使用RELAP5热工水力计算程序对PRS系统蒸汽隔离阀常关状态下PRS系统压力平衡时间开展工作,并分析了蒸汽隔离阀常关对自然循环的影响。     

PRS系统蒸汽管道隔离阀冷凝计算分析

蒸汽发生器二次侧非能动冷却系统(PRS)用以应对全厂断电叠加辅助给水系统失效的工况。PRS系统利用高处的冷凝水箱将蒸汽发生器的余热带出,最终通过冷凝水箱中水的蒸发将热量带入大气中。在机组正常运行期间,PRS系统蒸汽管线隔离阀前为高温高压水蒸气,阀后为低温低压的空气。若将PRS蒸汽管线隔离法机组运行期间,蒸汽在蒸汽管道隔离阀阀瓣处冷凝成水,如果这部分水回流到主蒸汽管道中,则会增大汽轮机入口的蒸汽湿度。本文计算分析了PRS系统蒸汽管道产生的凝结水,并评价了其对蒸汽发生器含湿量的影响。     

直流式蒸汽发生器数值模拟

以中国实验快堆(CEFR)40%功率下的蒸汽发生器为原型,基于相似模化原理建立了蒸汽发生器简化物理模型。采用两流体模型及热弹性力学基本关系式分别描述气液两相流沸腾相变过程和热应力变化规律。利用CFX对二、三回路侧流体流动传热及与传热管的耦合换热过程进行了数值模拟,并在ANSYS WORKBENCH中实现了流体温度场载荷向结构的传递,进而对传热管进行稳态热分析和热应力分析。研究结果为CEFR蒸汽发生器的安全运行提供了一定的理论支撑。     

核电厂蒸发器性能监测探讨

本文介绍了核电厂蒸发器性能监测的方法及应用,通过比较热功率、蒸汽压力、一次侧平均温度、污垢热阻及堵管率五个指标对蒸汽发生器进行评定,根据分析评定结果对蒸汽发生器热性能进行评定,并对蒸发器的未来运行状态进行预测,为蒸发器的运行和维修提供建议。     

对凝汽器钛管泄漏的认识

凝汽器作为二回路的一个重要设备,它对汽轮机的正常经济运行起着至关重要的作用。秦山二期的凝汽器有5800根钛管,在长期的运行中一旦其中某些钛管破损,就有可能使海水泄露入凝汽器,随之带入SG(蒸汽发生器)二次侧,使二次侧水质变差,钠、氯离子浓度高会导致蒸汽发生器传热管腐蚀,引起蒸汽发生器破管,后果十分严重。所以,控制好凝汽器钛管的运行,对机组的稳定运行和电厂经济效益显得非常重要。     

降功率过程中主给水调节阀卡涩处理

本文首先阐述了压水堆核电站主给水的功能及蒸汽发生器(SG)水位控制的基本原理,分析了主给水调节阀可能卡涩的原因,最后针对降功率过程中的调节阀卡涩提出相应的处理方法,并对处理的方法进行总结。     

PRS系统蒸汽管道隔离阀泄漏率计算分析

田湾核电厂5&6号机组作为M310改进机型,新增了蒸汽发生器二次侧非能动冷却系统(PRS)作为严重事故预防与缓解措施。蒸汽发生器二次侧非能动冷却系统的蒸汽管道与主蒸汽管道相连,凝水管道与辅助给水系统管道相连。在开展布置工作时发现,发现蒸汽管线非常长,若PRS系统蒸汽管线与主蒸汽管线之间的隔离阀常开,会对PRS系统的正常运行造成影响,因此考虑将PRS系统蒸汽隔离阀的状态由常开变换为常关。将PRS系统蒸汽隔离阀更改为常关后,需要考虑蒸汽隔离阀的质量泄漏率以此对后续的隔离阀后定期排水做出要求。     

商会自治的基石——商会自治规范研究

在现代法律秩序中,商会自治规范是制定法的基础和必要的补充,甚至在某些方面替代了制定法;商会自治规范主要包括商会组织规范、行为规范、惩罚规范以及争端解决规范等;其效力仅及于其内部成员;商会自治规范和制定法之间存在冲突,但也存在整合的基础。     

癸氧喹酯干混悬剂含量测定的改进

采用高效液相色谱法测定癸氧喹酯干混悬剂的含量,在2-250μg/mL范围内,峰面积的常用对数与进样量浓度的常用对数呈良好的线性关系,R^2=1(n=5),平均回收率为99.24%~99.51%,RSD在0.05%~0.28%。此方法分析时间短,样品前处理简便、定量结果准确,重现性好,结果满意,为其质量控制提供了依据。     

猪毛色遗传的研究进展

本文概述了猪的毛色类型、猪的毛色遗传模式,着重综述了猪毛色基因分子基础的研究进展,指出存在问题并就未来发展方向做了思考。     

Comparison of 2 methods of centesis of the bursa of the biceps brachii tendon of horses

REASONS FOR PERFORMING STUDY: Centesis of the bicipital bursa using an 8.9 cm long spinal needle has been reported but the alternative of employing a 3.8 cm long hypodermic needle requires validation. OBJECTIVE: To compare the efficacy of 2 different methods of centesis of the bicipital bursa and to evaluate the usefulness of ultrasonographic imaging to determine the location of solution administered when centesis of the bursa is attempted. METHODS: For Trial 1, 6 clinicians, who had no previous experience of centesis of the bicipital bursa, attempted to inject a solution composed of an aqueous radiopaque contrast medium and physiological saline solution (PSS) into the bicipital bursae of 2/12 horses using the previously described distal approach to inject one bursa and a proximal approach to inject the contralateral bursa. The bicipital tendon and bursa were examined ultrasonographically before and after injection; and both shoulders were examined radiographically to identify the location of the medium. In Trial 2, another 6 clinicians, also with no previous experience of centesis, repeated Trial 1, using 6 horses, but the radiopaque contrast medium was mixed with air instead of PSS. RESULTS: Accuracy of centesis using the proximal approach was 39% and that of the distal approach 28%. Ultrasonographic examination of the shoulder allowed the location of solution and air to be accurately predicted in all 12 shoulders examined. CONCLUSIONS: Clinicians who have had no previous experience performing centesis of the bicipital bursa are unlikely to be successful in centesis using either approach. Radiographic examination after injecting a radiopaque contrast medium may be necessary to assess the success of centesis especially if bursal fluid is not obtained during centesis. Injecting air along with the radiopaque contrast medium provides more accurate ultrasonographic confirmation of centesis and better radiographic definition than does injection without air.     

不同样本商品蜂蜜中硒含量的测定

用硝酸和高氯酸消化蜂蜜,使硒游离出来,在微酸性环境下,硒和2,3-二氨基萘(DAN)生成有较强荧光的物质,用环己烷萃取,在激发波长378nm,荧光波长518nm处测定其荧光强度。蜂蜜中硒含量范围:0.10～0.82μg/g。表明:蜂蜜应视为天然富硒营养品。     

乳酸杆菌益生作用机制的研究进展

乳酸杆菌作为益生菌广泛用于人和动物。本文综述了乳酸杆菌改善宿主健康的机制。乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道。文章重点讨论了乳酸杆菌表面成分（表面蛋白、脂磷壁酸和肽聚糖）与肠道受体（Ｃ型凝集素受体、Ｔｏｌｌ样受体和 Ｎｏｄ样受体）,阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制。     

Effects of size of ingestively masticated fragments of plant tissues on kinetics of digestion of NDF

Ingestively masticated fragments were collected and sized via sieving. Different sizes of esophageal masticate and ruminal digesta fragments, and ground fragments of larger masticated pieces were incubated in vitro, and undigested NDF remaining at intervals of up to 168 h of incubation was determined. The ruminal age-dependent time delay (tau) for onset of digestion of NDF was positively correlated (P < 0.004) with the mean sieve aperture estimated to retain 50% of the fragments between successive sieve apertures (MRA). Degradation rate of potentially degradable NDF (PDF) and level of indigestible NDF were not related (P > 0.10) to MRA of masticated and ground fragments. Estimates of tau were positively related to MRA, with slopes of bermudagrass < corn silage < ruminal fragments of corn silage. It was concluded that fragment size-, and consequently, ruminal age-dependent onset of PDF degradation of a mixture of different fragment sizes results in an age-dependent rate of degradation of the more rapidly degrading of two subentities of PDF. Models are proposed that assume a tau before onset of simultaneous degradation of PDF from two pools characterized as having gamma-modeled age-dependency and age-constant rates. The ruminal age-dependent pool seems to be associated with the faster-degrading pool, and its rate parameter increases with range in MRA in the population of fragments. Conceptually, the ruminal age-dependent rate parameter for PDF degradation seems to represent a composite of several effects: 1) effects of the size-dependent tau; 2) range in MRA of the population of ingestively masticated fragments; and 3) subentities of PDF that degrade via more rapid age-dependent rates compared with subentities of PDF that degrade via age-constant rates. The estimated fractional rates of ruminative comminution of ingestively masticated fragments (0.060 to 0.075/h) were of a magnitude similar to the mean fractional rates of PDF digestion (0.030 to 0.085/h), which implies that ruminative comminution may be first-limiting to fractional rate of PDF digestion. The in vivo roles of ingestive and ruminative mastication of fragments on PDF degradation must be considered in any kinetic system for estimating PDF digestion in the rumen. These results and others in the literature suggest that the rate of surface area exposure rather than intrinsic chemical attributes of PDF may be first-limiting to degradation rate of PDF in vivo.     

Mechanism of Action of Probiotic Function of Lactobacilli

乳酸杆菌作为益生菌广泛用于人和动物.本文综述了乳酸杆菌改善宿主健康的机制.乳酸杆菌可通过产生抗菌物质如乳酸、过氧化氢、细菌素,或者通过竞争营养或肠道黏附位点来抑制致病菌;通过诱导黏附素的分泌或阻止细胞凋亡而增强肠道的屏障功能,从而保护肠道.文章重点讨论了乳酸杆菌表面成分(表面蛋白、脂磷壁酸和肽聚糖)与肠道受体(C型凝集素受体、Toll样受体和Nod样受体),阐述了他们结合后启动免疫调节信号,调控肠道免疫功能以发挥改善健康作用的机制.     

中华人民共和国农业部公告 第267号

为贯彻落实《兽药生产质量管理规范》(简称《兽药GMP》),进一步推动兽药GMP实施进程,我部制定了《兽药生产质量管理规范检查验收办法》,现予公告。本公告自2003年6月1日起施行。附件:兽药生产质量管理规范检查验收办法二○○三年四月十日第一章 总则 第一条 为推动《兽药生产质量管理规范》(以下简称兽药GMP)的实施,规范兽药GMP检查验收工作,制定本办法。 第二条 农业部负责全国兽药GMP管理和检查验收工作;负责制修订兽药GMP检查验收管理规定;负责兽药GMP检查员队伍建设和监督管理工作,负责国际兽药贸易中GMP互认工作。 …