Effect of Solute Titanium on Void Swelling in 316 Stainless Steel

To investigate the solute Ti effect on void swelling in stainless steels, the well-annealed 316 stainless steels modified with various amounts of Ti were electron-irradiated in a high voltage electron microscope (HVEM). It was found that the swelling decreased dramatically with increasing Ti content up to 0.25w/0. This strong dependence of swelling on Ti content arises mainly from the changes in void number density, although the void growth rate also decreases with increase in Ti content. The dependence of the void number density on Ti content is interpreted in terms of the vacancy trapping effect of Ti, which decreases the steady state free vacancy concentration and results in the effective suppression of the void nucleation rate.     

用正电子湮没寿命技术研究塑性变形纯Ni的回复过程

本文用正电子湮没寿命方法研究了塑性变形镍(含0.01％杂质)的回复过程的特点及杂质在缺陷回复过程的作用和影响,计算了形变为10％的试样中的位错密度及形成空位团的有效空位浓度。     

利用D-T聚变中子源转化长寿命裂变产物的中子学可行性研究

从中子学角度研究长寿命裂变产物在Tokamak型D-T聚变堆包层中转化的可行性.提出了用可裂变Pu增殖中子的混合包层转化方案,研制了相应的燃耗计算程序及数据库,并对所提方案进行了计算和分析.结果表明,在可预见的聚变堆芯技术条件下,所研究的概念性包层可对长寿命裂变产物进行有效转化.     

One-electron capture and target-ionization in He-neutral-atom collisions

One-electron capture and target-ionization cross-sections in collisions of He⁺ ions with neutral atoms: He⁺ + A → He + A⁺ and He⁺ + A → He⁺ + A⁺ + e, A = H, He(1s², 1s2s), Ne, Ar, Kr, Xe, are calculated and compared with available experimental data over the broad energy range E = 0.1 keV/u–10 MeV/u of He⁺ ions. The role of the metastable states of neutral helium atoms in such collisions, which are of importance in plasma physics applications, is briefly discussed. The recommended cross-section data for these processes are presented in a closed analytical form (nine-order polynomials) which can be used for a plasma modeling and diagnostics.     

氦对低活性Fe-Cr-Mn(W,V)合金辐照损伤影响

采用低能离子加速器和超高压电镜相连接复合辐照装置,研究注入He后经电子束辐照,观察低放射性Fe-Cr-Mn（W,V）合金的辐照损伤特征;研究He对辐照过程中产生二次缺陷,空洞肿胀,诱起晶界偏析的影响。实验结果证明He的存在,增加辐照初期位错密度,促进空洞核心形成及空洞肿胀增加,抑制晶界近旁溶质元素偏析。     

Neutron Irradiation Effect on Isotopically Tailored 11B4C

The present investigation was carried out to elucidate the effects of neutron irradiation on the dimensional change and thermal conductivity of isotopically tailored ¹¹B₄C. The specimens used in the present investigation are 99% ¹¹B-enriched ¹¹B₄C, 91% ¹⁰B-enriched ¹⁰B₄C, and β-SiC. ¹⁰B₄C was sampled from an irradiated material used as a neutron absorber in a “JOYO” MK-II control rod. The ¹¹B₄C and SiC specimens were irradiated in the experimental fast reactor “JOYO” to fluences of 1:94 × 10²⁶ n/m² (E > 0:1 MeV) at 530°C and 3:12 × 10²⁶ n/m² (E > 0:1 MeV) for ¹⁰B₄C, with a ¹⁰B burnup of 47:3 × 10²⁶ cap/m³. Measurements on changes in dimensions and thermal conductivity, as well as postirradiation annealing up to 1400°C, were carried out. The results of such measurements indicated that the changes in the dimensions and thermal conductivity of neutron-irradiated ¹¹B₄C were substantially smaller than those of ¹⁰B₄C and SiC. Postirradiation annealing measurements for ¹¹B₄C showed that the thermal conductivity was almost completely recovered at 1400°C. The changes in thermal conductivity by annealing were analyzed in terms ofphonon scattering theory. The onset of recovery of the thermal conductivity of ¹¹B₄C agreed well withirradiation temperature; however, the recovery of length did not coincide with irradiation temperature.     

非能动先进压水堆核电厂严重事故下裂变产物行为研究

非能动先进压水堆核电厂在严重事故下,安全壳可能发生失效,导致大量放射性物质向环境释放。本文针对非能动先进压水堆核电厂可能发生的早期失效、中期失效、晚期失效三种释放类别,建立百万千瓦级非能动先进压水堆的事故分析模型,分别针对自动卸压系统第二级卸压阀误开启,DVI管线上发生当量直径为4英寸的破口,以及热管段发生当量直径为2英寸的破口的典型严重事故序列,在研究事故进程的基础上,分析事故下裂变产物释放和迁移的特性,重点关注惰性气体、挥发性裂变产物和非挥发性裂变产物在核电厂的分布,最终计算释入环境的裂变产物源项。本文分析结果可为严重事故管理以及厂外放射性后果评价提供支持。     

High-dose neutron induced radiation swelling simulated by heavy ion irradiation and its microscopic study with positron annihilation technique

1IntroductionStainlesssteel(SS)isanimportantreactorstructuralmaterial.SSusedinreactorsexperiencesneutronirradiationandtheaccumulateddosemayreach1022-23n'cm--2alleryearsofreactoroperation.Consequently,severeradiationeffectsoccurinSSandwouldleadtoareactorbreakdownorevenaccident.RadiationsWellingisamajorradiationeffectinSSwhichshouldbetakenintoaccountinreactordesignandoperation.Severeswellinggenerallyoccursatneutrondosesof2102on'cm--2.Thelackofneutronproducingson-rsesofsuchhighdoseshampersits…     

Development of thermodynamic databases in the system U–Zr–Ce–Cs–Fe–B–C–I–O–H for application to simulating phase equilibria in severe nuclear accidents

In case of severe nuclear accidents involving melt down of nuclear fuels at high temperatures, it is of considerable importance to accurately evaluate the highly-volatizing behavior of fission products (FPs) over multicomponent debris. Particularly, cesium (Cs)- and iodine (I)- bearing chemical species are regarded as notable FPs. In the present work, the authors have generated original thermodynamic databases for the system U–Zr–Ce–Cs–Fe–B–C–I–O–H featuring Cs- as well as I-bearing subsystems, which are contained in oxide, iodide, and metal (including borides and carbides) sub-databases. It has been confirmed that the phase diagrams calculated by the present set of the databases reproduce the corresponding literature data well in various kinds of subsystems of the above multicomponent system. The present set of databases has subsequently been applied to simulate phase equilibria and volatizing behavior of Cs- and I-including species, respectively, in multicomponent debris under specific temperature and atmospheric conditions corresponding to severe nuclear accidents.     

氦对Fe-Cr-Ni合金和Fe-Cr-Mn合金辐照损伤的影响

利用超高压电镜与高能离子加速器连接装置 ,研究了氦 (He)对Fe Cr Ni和Fe Cr Mn两类奥氏体型合金辐照损伤行为的影响。观察了辐照过程中二次点缺陷的演变、空洞的形成以及辐照诱导晶界处溶质元素浓度的变化。实验结果表明 :He能促进两类合金空洞核心的增加 ,但空洞尺寸和密度不同 ;He能有效抑制辐照诱起晶界元素偏析 ,但对不同原子尺寸的溶质原子抑制效果不同。该差别是由于He的注入提高空位移动激活能和改变点缺陷与溶质原子相互作用的效果     

Ion irradiation induced order-to-disorder transformations in δ-phase Sc4−xZr3+xO12+x/2

The purpose of this study is to investigate the role of stoichiometry on crystal structure transformations in derivative fluorite compounds known as delta (δ) phase. In this study, polycrystalline δ-phase ceramic pellets were prepared with stoichiometries given by Sc_4−xZr_3+xO_12+x/2 (x = 0, 0.77 and 1.20)_. The pressed and polished pellets were then irradiated under cryogenic conditions with 200 keV Ne⁺ ions to fluences ranging from 1-5 × 10¹⁴ Ne/cm². An order-to-disorder (O-D) transformation was observed for all compositions, as determined using grazing incidence X-ray diffraction (GIXRD). However, the transformation threshold dose was found to systematically decrease with increasing ZrO₂ content: ∼0.2, ∼0.16, and ∼0.08 dpa for Sc_4−xZr_3+xO_12+x/2 with x = 0, 0.77, and 1.20, respectively. These irradiation-induced phase transformation results are discussed in terms of the crystal structure of the δ-phase.     

基于WIMS-D库燃耗数据的更新与基准验证

随着AP1000等新一代压水堆的发展,燃耗深度在不断提高,平均卸料燃耗深度提高到60 GW d·t-1。然而,传统使用的WIMS69群和XMAS172群WIMS-D格式多群常数库,其能群结构存在共振峰重叠,核素种类较少,裂变产物产额的偏差较大,并且伪裂变产物中包含的核素种类较多而导致152Gd、160Gd、159Tb、160Tb等重要核素无法得到精确处理等问题。因此,本文主要针对AP1000等新一代反应堆的设计以及运行特点,基于ENDF/B-VII.1库,并且在现有基础上针对WIMS-D库中的伪裂变产物、裂变产物燃耗链以及裂变产物产额等燃耗数据进行更新,再通过NJOY程序开发了SHEM281群WIMS-D格式多群常数库。通过DRAGON程序挂载该WIMSD281库,对其进行临界和燃耗两方面基准验证。计算结果表明,该数据库的计算结果与基准值符合较好,精度较高,结果可靠,可初步用于压水堆的相关计算。     

Effect of Fast Neutron Irradiation on the Properties of Boron Carbide Pellet

Boron carbide pellets were irradiated in the experimental fast reactor “JOYO” to ¹⁰B burnup of up to 170x10²⁶cap/m³, fluences of 2x10²⁶/m²(E>0.1MeV), and maximum temperatures of about 1,200°C. Post irradiation examinations were made of microstructural changes, helium release, swelling, and thermal conductivity.

Boron carbide pellets irradiated to high burnups developed extensive cracking. Helium release from the pellets was initially low, but enhanced helium release was observed at high burnups and high temperatures. The swelling linearly increased with burnup, and when boron carbide was irradiated at high temperatures, the swelling rate began to decrease corresponding to the beginning of enhanced helium release. The correlation between swelling and the helium release was studied and the swelling was interpreted in terms of accumulation of helium in the boron carbide pellet. The thermal conductivity of the boron carbide pellets decreased rapidly by neutron irradiation accompanied with loss of temperature dependence.     

Recovery of Electrical Resistivity in Neutron Irradiated Uranium Monocarbides

An experimental study was performed on the heat transfer to a turbulent water film which is falling down the outside surface of a heated vertical tube. The test section was made of stainless steel tube 13 mm in outside diameter and 1,500 mm long. It was found that a nearly constant heat transfer coefficient was obtained for the lower half of the test section covering a length of about 1 m, which was direct-heated by electric current. The resulting values of the Nusselt number in this region were correlated to the Reynolds number, and the plots fell in a region intermediate between those given by Wilke and by McAdams. An analytical model taking account of the undulation on the film surface is proposed. The predictions from the model give fairly good agreement with the experimental data.     

钚及其裂变产物钯、银、镉、锡、锑、锆的系统分离方法

描述了钚及其6种裂变产物钯、银、镉、锡、锑、锆的系统分离方法：在强碱性阴离子交换树脂柱上将盐酸介质的辐照靶溶解液中的这些元素分为5组,然后再针对各组目标元素进行分离和纯化,可简便快速地从同一份靶溶解液中分离以上7种元素。采用辐照铀靶对分离方法进行了验证,结果表明,分离流程对6种裂变产物的化学回收率均大于70%,对γ谱仪测量干扰的主要核素去污因子均大于1.0×10³,可满足²³⁹Pu裂变谷区核素裂变产额测量对化学分离的要求。     

钚及其裂变产物钯 、银 、镉 、锡 、锑 、锆的系统分离方法

描述了钚及其6种裂变产物钯、银、镉、锡、锑、锆的系统分离方法：在强碱性阴离子交换树脂柱上将盐酸介质的辐照靶溶解液中的这些元素分为5组,然后再针对各组目标元素进行分离和纯化,可简便快速地从同一份靶溶解液中分离以上7种元素。采用辐照铀靶对分离方法进行了验证,结果表明,分离流程对6种裂变产物的化学回收率均大于70%,对γ谱仪测量干扰的主要核素去污因子均大于1.0×10³,可满足²³⁹Pu裂变谷区核素裂变产额测量对化学分离的要求。     

裂变产物活度计算通用程序开发

按照衰变规律,推导了裂变产物活度计算的通用公式。以PowerBuilder 10.0为工具,建立了裂变产物的独立产额、衰变路径和衰变信息数据库,开发了一用于计算裂变产物活度的通用程序。利用该程序计算了8种气体裂变产物的原子核数随时间的变化,结果与文献数据基本一致。本程序为与核裂变相关的裂变产物预先评估提供了一个便利的工具。     

核燃料裂变产物对临界影响研究

本文针对钐、钕、钆和银等4种裂变产物在中试厂核临界安全实验装置上开展了临界实验研究。堆芯的易裂变材料为固液两相存在,固体燃料为二氧化铀,液体燃料为硝酸铀酰。固体燃料棒采用六角形方式排布,浸泡在硝酸铀酰溶液中。将临界实验测量结果与蒙特卡罗程序MONK的理论计算结果进行比较。结果表明：理论计算结果与临界实验测量结果符合较好;裂变产物样品引入的负反应性价值非常可观,能谱变化显示裂变产物样品对中子的吸收在热能点以下能区起决定性作用。     

双束同时辐照对低活性Fe-Cr-Mn(W,V)合金相稳定性影响

采用电子束 /He+ ion束同时复合辐照方式 ,研究了低活性Fe Cr Mn(W ,V)合金高温长时时效后组织稳定性 ,评价了He对辐照相稳定性影响。结果表明 ,单独电子辐照 ( 10a-1 )只引起相界面低密度空洞形成。而双束同时辐照对组织损伤具有协同效果 ,加剧相稳定性发生变化 ,如 :促进相间溶质原子扩散 ,导致析出相长大 ;新相的形成 ;发生结构无序化 ,促进析出相改性。从He原子与晶体辐照点缺陷与溶质原子相互作用和扩散等机制 ,讨论了辐照相稳定性发生变化的原因。