铀尾矿废渣回填治理区植物中铀放射性水平调查

为了解北方某铀矿尾渣回填区内放射性核素铀在植物体中富集情况,为进一步探讨利用植物修复技术对铀矿区进行土壤修复的可行性,以及寻找放射性核素污染土壤治理的方法提供理论依据,采集矿区内堆浸工位与矿区外尾渣回填治理区常见植物样本,采用ICP-MS测定植物和土壤中放射性铀水平,针对植物对铀的耐受性和富集能力进行评估,筛选出富集能力较强的植物,进一步探索利用植物修复技术对放射性废物治理。结果表明,经对采集的植物中铀含量检测发现植物的地下部分铀含量高于地上部分,铀主要集中在根部,植物各部位铀含量由高到低分别为根、叶、茎。矿区内堆浸工位处的大籽蒿根部铀活度为 64.26 Bq/kg;在矿区外尾渣回填区同一植物根部铀活度为0.86 Bq/kg。所调查的北方某铀矿尾渣回填区内所采集的植物中铀含量极低,远小于矿区内堆浸工位所采植物样品中铀含量。深埋回填铀矿尾渣是切实有效可行的。     

~(131)I在甲状腺中活性和剂量的分布

众所周知,~(131)I 是核爆炸后早期落下灰中对人体危害较大的一种核素~[1,2],同时也是临床医学应用最广泛的一种放射性同位素~[8]。过去,在放射性碘的生物效应研究中,对甲状腺受照剂量的估算,是基于放射性碘在腺体中呈均匀分布,根据有关参数采用经典剂显公式计算的。这种方法计算的剂量与实际受照剂量有多大差别,还不十分清楚。为此,本文研究了~(131)I 在狗甲状腺中活性的分布情况,用 LiF 剂量元件测量了~(131)I 均匀分布的甲状腺水模型(以下简称甲状腺模型)中的剂量和狗食入~(131)I 后甲状腺的受照剂量,通过数学处理和分析,找出~(131)I 在狗甲状腺中的分布特点,建立了~(131)I 在甲状腺模型中的剂量分布函数,以描述剂量的空间分布,导出了计算甲状腺实际受照剂量的公式和甲状腺体的等剂量曲面方程,为~(131)I 的剂量与效应的研究提供参考性资料。     

Numerical analyses on liquid-metal magnetohydrodynamic flow in sudden channel contraction

Three-dimensional numerical calculations have been performed on the magnetohydrodynamic (MHD) flows through a rectangular channel with sudden contraction, particularly in order to estimate the pressure drop through the sudden contraction. The sudden contraction is in the directions both perpendicular and parallel to the applied magnetic field. The Hartmann number, the Reynolds number, and the magnetic Reynolds number were set to ～100, ～1000, and ～0.001, respectively, in simulating laboratory conditions. The continuity equation, the momentum equation, and the induction equation were solved numerically. In the sudden contraction in the direction perpendicular to applied magnetic field, the loss coefficient takes a positive value in all the cases performed in this study, contrary to the expectation. This result is in contrast to that in the sudden expansion in the direction perpendicular to applied magnetic field, where the loss coefficient generally takes a negative value due to the MHD effect. In the sudden contraction in the direction of applied magnetic field, the loss coefficient takes a positive and large value in all the cases performed in this study. The loss coefficient generally becomes larger than that in the case of corresponding channel expansion in the direction of applied magnetic field.     

重庆市氡浓度水平调查

对重庆市主城区环境空气、房地产建筑工程场地、伴生放射性矿堆场和宾馆室内空气氡浓度进行了调查。调查结果表明:主城区在12个区24个测点的环境空气中氡浓度年均值为10.8Bq/m3;房地产建筑工程场地土壤中的氡浓度按6个工地统计均值为1193Bq/m3;不同伴生矿的矿堆场周围空气中氡浓度水平差异很大,其中萤石矿最大,其次是铅锌矿;堆场周围空气中氡浓度水平按10类被调查的矿种统计平均值为65.2Bq/m3,萤石矿堆场周围空气中氡浓度平均值369Bq/m3,约是全市区域环境空气中氡浓度的35倍;8家宾馆109个客房室内氡浓度年均值为32.9Bq/m3。     

Resonance Treatment Based on Ultra-fine-group Spectrum Calculation in the AEGIS Code

The resonance calculation method using the ultra-fine-group spectrum calculations in the AEGIS code is explained in detail. By a simple benchmark problem, it is verified that the effect of anisotropic scattering on effective cross-sections is not very large and the isotropic scattering source approximation is adequate in practical resonance calculations in LWRs. Furthermore, some efficient numerical algorithms in the ultra-fine-group calculations to reduce the computation time without large degeneration of accuracy are presented. In addition, the SPH method for energy collapsing of cross-sections is adopted in the AEGIS code to reduce the error of energy collapsing.

Through the comparison with continuous-energy Monte-Calro calculation in the pin-cell geometry, the validity of the resonance treatment in the AEGIS code is verified.     

秦山,大亚湾核电站周围地区土壤盆栽水稻对^137Cs的吸收规律

对秦山、大亚湾核电站周围地区５种水稻田土,在苗期分别施入等量（３７０Ｂｑ／ｇ土）＾１３７Ｃｓ溶液盆栽水稻,分期成熟后取样;对秦山地区的官堂水稻田土盆栽的水稻,在苗期、孕穗期和灌浆期分别施入等量（３７０Ｂｑ／ｇ土）的＾１３７Ｃｓ溶液,成熟后取样及苗期施入等量（３７０Ｂｑ／ｇ土）＾１３７Ｃｓ溶液分３个生育期取样;对相同土壤盆栽的水稻,在苗期分别施入０．３７、３．７、３７和３７０Ｂｑ／ｇ土＾１３７Ｃｓ溶     

Uranium (IV)-(VI) Electron Exchange Reactions in Anion Exchange Resin,Tri-n-Octyl Amine and Tri-Butyl Phosphate

A study has been made of the U(IV)-U(VI) electron exchange reactions taking place between natural U(IV) and depleted U(VI) in anion exchange resin, as well as in TnOA/benzene and TBP/benzene systems.

The exchange rate in the anion exchange resin was smaller than the corresponding rates in 8–10 M HCl, which might be explained by considering that the diffusion of the exchangeable species is much slower in the anion exchange resin than in 8–10 M HCl.

The exchange rates in TnOA/benzene and in TBP/benzene were accelerated by decreasing the concentration of TnOA or TBP in benzene. The reason may be that TnOA and TBP, including the exchangeable species, is more easily diffused in dilute than in concentrated solution.

Based on activation energy values, the mechanism of exchange in the anion exchange resin was estimated to be similar to that in 8–10 M HCl solution, and the corresponding mechanism for TBP/benzene similar to that for the cation exchange resin. In the case of TnOA/benzene, the exchange process was presumed to resemble that of the anion exchange resin, judging from the similarity of ionic species extracted thereinto.     

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.     

5－羟色胺对小剂量辐射小鼠脾细胞免疫功能的影响

应用培养雄性昆明系小鼠脾细胞技术，观察５－ＨＴ对７５ｍＧｙＸ射线体内和体外照射脾细胞免疫功能的影响。结果发现，５－ＨＴ明显抑制正常脾细胞自发增殖能力，但对正常脾细胞ＣｏｎＡ反应性影响不明显；当５－ＨＴ在一定浓度时，７５ｍＧｙ体内和体外照射的脾细胞对ＣｏｎＡ反应性均增强。提示，５－ＨＴ可抑制正常脾细胞免疫功能，并在一定程度上参与小剂量辐射的免疫刺激作用；但一定浓度５－ＨＴ对体内和体外照射脾细胞增殖能力的影响不同，体内照射时增强，体外照射时抑制，推测与体内脾细胞微环境改变有关     

Reactions between SiC and SrO at High Temperatures

A mixture of SiC and SrO was heated in air, in Ar and in vacuum, and the reaction products were determined by powder X-ray diffraction. The reaction began above 1,000°C and the products varied, depending on the oxygen content in the heating atmosphere. For example, in the case of a mixture of 1:1 in atomic ratio, SrO·SiO₂ formed in air, while in oxygen-free atomsphere, SrC₂ and Sr were produced besides SrO·SiO₂. It was also found that the powder X-ray diffraction pattern of SrO·SiO₂ obtained in the present experiment differed in part from O'Daniel's data. It is concluded that study of the microstructural changes in the SiC coating layer at high temperatures should be most important for assuring the retainment of the fission products Sr and Ba in coated particle fuels.     

Progress in JT-60 Experiments

The Japan Atomic Energy Research Institute completed in April 1985 the construction of the large tokamak JT-60, which constitutes a focus of the Second Phase of the Japanese fusion development program under the Atomic Energy Commission started in 1975. Initial experiments of JT-60 were carried out in hydrogen plasma after the completion of the device. Full installation and testing of the heating devices was completed in July 1986 and subsequently the heating experiment was initiated. The target parameters were achieved in deuterium-equivalent values in September 1987 by high power heating of high density hydrogen plasmas at high plasma current. JT-60 has entered the phase of advanced experiments in 1988.     

富铬酵母细胞的DNA、RNA和蛋白质结合铬的测定

使用中子活化分析方法测定了富铬酵母与普通酵母的ＤＮＡ、ＲＮＡ和蛋白质中铬的含量。研究铬与ＤＮＡ、ＲＮＡ和蛋白质的结合情况。结果发现,两种酵母的ＤＮＡ、ＲＮＡ和蛋白质提取率和浓度无明显差异,但富铬酵母中ＤＮＡ、ＲＮＡ和蛋白质的铬含量高于普通酵母,而且铬与ＤＮＡ的结合量明显高于ＲＮＡ和蛋白质,说明酵母细胞在含铬的培养基中培养时,铬进入细胞体内产生生物转化,并与酶母细胞的ＤＮＡ、ＲＮＡ和蛋白质发生了结合     

体外照射RBC对SeGSHPx活性的影响

本文以大小鼠RBC为模型观察了不同剂量体外照射对SeGSHPx活性的影响,以探讨全身照射时RBC SeGSHPx活性降低的原因、RBC体外照射SeGSHPx活性变化特点以及SeGSHPx在抗辐射脂质过氧化中的作用。结果是,RBC悬液和全血体外照射SeGSHPx活性都不降低,温育可使受照RBCSeGSHPx活性增高,与受照RBC K~+渗漏和溶血程度的变化规律相一致;VE对体外照射RBC的脂质过氧化损伤无保护作用,但对体外照射SeGSHPx受抑制的RBC则显示保护作用。     

固化氛围对丙烯酸酯紫外光固化材料表面性能的影响

在空气或氮气氛围下对同样配方的光敏树脂进行紫外光固化,固化膜的表面能测定表明,空气中固化材料的表面能大于氮气中固化材料.固化膜的元素分析和衰减全反射-傅立叶变换红外光谱(Attenuated total reflectance-Fourier transform infrared spectroscopy,ATR-FTIR)分析表明,氧阻聚反应并未导致空气下固化的材料中氧含量的明显变化,其红外谱图中未见有过氧基团的吸收峰,但其表面富集有较多的吸电子基团;而氮气下固化的材料表面存在较多的碳碳单键.X射线光电子能谱(X-ray photoelectron spectroscopy,XPS)分析表明,不同的固化氛围使材料表面C1s和O1s原子结合能产生差异.说明固化氛围影响固化速率,使固化过程中固化膜组成分布或聚集态密度产生差异,最终使固化层的表面化学组成乃至表面能存在差别.     

Thermodynamic Calculation on the Vaporization of Fission-Produced Noble Metal System in Vacuum and Oxidative Atmosphere at High Temperatures

The vaporization behavior of fission-produced noble metal system (Mo-Ru-Pd, Mo-Ru-Rh and Mo-Tc-Pd) in vacuum and oxidative atmosphere at high temperatures was investigated by the thermodynamic calculation on the basis of the regular solution model and the available experimental data. The palladium and rhodium in the allyoys, and molybdenum and ruthenium in the alloys vaporize preferentially at high temperature in vacuum and in ari, respectively. At low temperature below 385K in air, ruthenium and technetium in the alloys vaporize predominantly by oxidation.     

Safety Analysis of ITER EDA Design by GEMSAFE

General Methodology of Safety Analysis and Evaluation for Fusion Systems (GEMSAFE) was applied to the International Thermonuclear Experimental Reactor (ITER) design in the stage of Engineering Design Activities (EDA) to identify Design Basis Events (DBEs) and the related safety features, which were compared with those of the ITER design in the stage of Conceptual Design Activities (CDA). As a result, 18 DBEs for the EDA design were selected in comparison with 25 DBEs for the CDA design. DBEs related to the fuel area were categorized in higher event category than those of the CDA design due to the increase of the mobile tritium contained in some components. It was necessary to reduce the inventory of the tritium absorbed in the tokamak dust in the EDA design as well as in the CDA design. Some measures were recommended to reduce mobile tritium dissolved in the coolant in the single cooling loop due to the increase of this estimated inventory.     

Molecular dynamics study of acoustic velocity in silicate glass under irradiation

The development of a molecular dynamics method simulating the propagation of acoustic waves allowed their propagation velocities to be measured in borosilicate glasses. The qualitative results obtained in glass irradiated by heavy ions correctly reproduces the experimental results, i.e. a reduction in the acoustic wave propagation velocity in irradiated glass. These changes in the mechanical properties were correlated with structural changes, in particular increased disorder in the glass. The greater disorder results in broadening of the characteristic distributions of the glass: distances, angles, and ring sizes. Similarities were clearly observed between the effects of irradiation and the effects of higher quenching rates on the acoustic wave propagation velocities. An additional study of glass artificially expanded by homothetic volume transformation shows that a reduction in acoustic velocity is not necessarily associated with swelling. The artificial volume change combined with increased stresses in the glass results in higher acoustic velocities.     

Carry-chain propagation delay impacts on resolution of FPGA-based TDC

The architecture of carry chains in Field-Programmable Gate Array （FPGA） is introduced in this paper. The propagation delay time of the rising and falling edges in the carry chains are calculated according to the archi- tecture and they are predicted not equal in most cases. Tests show that the measuring results of the propagation delay time in EP3C 120F484C8N series FPGA of Altera are in line with the inference. The difference of propa- gation delay time results in different accuracies of Time-to-Digital Converter （TDC）. This phenomenon shall be considered in the design of TDC implemented in FPGA. It can ensure better accuracy.     

Measurement of Local Power Peaking Factors in Heavy-Water Moderated Plutonium Lattices

Local power peaking factors (LPF) in the heavy-water moderated plutonium lattices were measured by a new method of γ-scanning of fuel pins using the calculated power correction factor of which accuracy was evaluated with the aid of foil activation method. Accuracy in measurement of the LPF was evaluated to be within 1%.

By this measurement, behaviors of the LPF have been made clear concerning the differences in fuel materials, coolant materials and arrangement in fuel enrichments. Depression of the thermal power in the fuel cluster makes LPF in the plutonium fuel lattice larger than in the uranium lattice. This tendency is more remarkable in air coolant lattice than in H₂O coolant lattice. The value of LPF for the plutonium fuel cluster of different enrichments is smaller than that of a uniformly enriched fuel cluster. The reduction of LPF is smaller in H₂O coolant than in air coolant lattice.

The values of LPF by WIMS-D code based on the transport theory and by METHUSELAH-II code based on the diffusion theory are in agreement with the measured ones, within 1.5 and 2.4% respectively.     

Application of DBD and DBCD in SO2 Removal

The dielectric barrier corona discharge(DBCD) in a wire-cylinder configuration and the dielectric barrier discharge(DBD) in a coaxial cylinder configuration are studied. The discharge current in DBD has a higher pulse amplitude than in DBCD. The dissipated power and the gas-gap voltage are calculated by analyzing the measured Lissajous figure. With the increasing applied voltage, the energy utilization factor for SO2 removal increases in DBCD but decreases in DBD because of the difference in their electric field distribution. Experiments of SO2 removal show that in the absence of NH3 the energy utilization factor can reach 31 g/kWh in DBCD and 39 g/kWh in DBD.