聚丙烯的辐射效应

本文研究了在室温下,真空,氮气或空气存在时,γ射线对聚丙烯毡和薄膜性能的影响(包括粘均分子量、等规度、机械强度和结晶度)。测定了辐照时产生的气体,并计算了它们的G值,分别为G_(H2)=2.52～3.56,G_(CH4)=0.11～0.21,G_(C2H4)=0.01～0.02,G_(C3H6)=0.13～0.21,G_(C4H8)=0.26～0.24 实验结果表明,剂量率在2.78×10~2rad/s时,辐照剂量小于5×10~5rad,材料性能几乎没有变化,剂量继续增加,物理和机械性能逐渐下降,辐照剂量超过5×10~6rad后,就产生大量低分子碳氢化合物,辐照剂量达到3×10~7rad时,试样受到极大破坏,甚至可成粉末。 ESR光谱测定结果指出,在真空辐照时产生的陷落自由基,一旦暴露空气就转变成过氧化自由基,并可引起自氧化降解反应,使试样进一步裂解。因此,我们认为要提高聚丙烯的辐射稳定性,可添加某些抗氧剂或做成多组份共聚物。     

聚氟乙烯辐射效应研究

本文通过特性粘度、红外光谱和失重的测定,研究了聚氟乙烯的辐射效应。结果表明,聚氟乙烯的特性粘度和分子量随辐照剂量增加而下降、在辐照剂量1×10~4Gy以上时,红外光谱有明显的变化,先后在1750cm~(-1)、1640cm~(-1)、1845cm~(-1)和3440cm~(-1)处有新峰出现,在热处理后1750cm~(-1)和1845cm~(-1)峰减弱,1640cm~(-1)峰加强。测得了羰基峰和羧基峰强度与辐射剂量的关系。聚氟乙烯辐照后先有增重现象,随后开始失重,最终恒定,失重程度与辐照剂量和温度有关。     

氢在中子辐照硅单晶中的特性

我们采用样品熔融-气体色谱分析方法测得氢气氛区熔的硅单硅中含氢量为1—1.5×10~(17)cm~3,将这种硅单晶放在反应堆内辐照到2×10~(17)n/cm~2的中子剂量,然后作等时和等温退火,测量电阻率、正电子湮没寿命谱。     

聚甲基丙烯酸甲酯体系研究Ⅲ.聚甲基丙烯酸甲酯辐射裂解

本文研究了聚甲基丙烯酸甲酯的辐射裂解效应。线型结构聚甲基丙烯酸甲酯在室温空气中辐照,1×10~6～1×10~8rad范围内,聚合物分子量随剂量增高而下降的关系呈线性,G_(s)=1.0。交联网状结构聚甲基丙烯酸甲酯在室温空气中辐照后,凝胶溶胶分配变化和M_c随剂量增高而上升的效应,确认发生了裂解变化。     

萃取剂的辐射稳定性研究(Ⅹ) 苯对磷酸三丁酯的辐射保护效应

磷酸三丁酯-苯混合体系经~(60)Co-γ射线辐照,气体产物为H_2,CH_4,C_2H_2,C_2H_4,C_3H_8和n-C_4H_(10),液体产物为磷酸二丁酯、磷酸一丁酯、正丁醇、环己烯、正辛烷和聚合物等。体系的辐解产物随苯浓度改变而有差异,且不遵守加和规律,表明苯抑制了磷酸三丁酯的辐射降解。这种保护作用除自由基清除效应外,激发能转移也为重要原因。比较了磷酸三丁酯-苯混合体系的分子间能量转移与苯基膦酸二丁酯的分子内能量转移效应。     

Study of Non-Thermal DC Arc Plasma of CH_4/Ar at Atmospheric Pressure Using Optical Emission Spectroscopy and Mass Spectrometry

Non-thermal C/H/Ar plasmas are widely applied to carbonaceous material production and processing.In this work,plasma parameters and gaseous species of the atmospheric non-thermal C/H/Ar plasmas produced by an atmospheric-pressure DC arc discharge generator in CH_4/Ar were investigated.The voltage-current characteristics were measured for different CH_4/Ar ratios.Optical emission spectroscopy was employed to analyze the electron excitation temperature,gas temperature and electron density under various discharge conditions.The hydrocarbon molecules produced in the CH_4/Ar plasmas were detected with photoionization mass spectrometry.The optical spectral results demonstrated that the electron excitation temperature was 0.4-1 eV,the gas temperature was 2800-4200 K and the electron density was in the range of(5-20)×10~(15) cm~(-3).The mass spectrum indicated that a variety of unsaturated hydrocarbons(C_2H_4,C_3H_6,C_6H_6,etc.) and several highly unsaturated hydrocarbons(C_4H_2,C_5H_6,etc.) were produced in the non-thermal arc plasmas.     

水与三甲基硅烷醇羟基的氢同位素交换反应的理论研究

以(CH_3)_3SiOH羟基模拟Li_4SiO_4陶瓷表面羟基,研究了H_2O与(CH_3)_3SiOH羟基H的氢交换反应机理.采用HF, MP2方法,在3-21G和6-311G++H~(**)水平上优化了(CH_3)_3SiOH, H_2O, (CH_3)_3SiOH-H_2O复合物及氢交换反应过渡态的结构.计算了生成(CH_3)_3SiOH-H_2O复合物的反应热,探讨了氢交换反应的路径.结果表明,可以形成2种形式的(CH_3)_3SiOH-H_2O复合物,一种是H_2O的O原子与(CH_3)_3SiOH羟基的H原子作用形成的复合物,另一种是H_2O的H原子与(CH_3)_3SiOH羟基的O原子作用形成的复合物.MP2/6-311G++~(**)水平上,对基组重叠能(BSSE)进行校正后,上述2种复合物的反应热分别为20.046 5 kJ/mol和21.630 7 kJ/mol.有利的氢交换反应路径为:H_2O的H原子与(CH_3)_3SiOH羟基的O原子作用形成的复合物,然后H2O提供1个H原子、1个O原子,(CH_3)_3SiOH提供1个O原子、1个Si原子形成由O, H, O, Si 4个原子构成的四元环过渡态,最后H_2O的O原子与(CH_3)_3SiOH 的Si原子成键形成新的(CH_3)_3SiOH,而(CH_3)_3SiOH的Si-O键断裂,由(CH_3)_3SiOH的羟基和H_2O的1个H原子形成新的H_2O分子,MP2/6-311G++~(**)水平上,BSSE校正后,此路径的反应活化能为186.898 4 kJ/mol.     

γ射线辐照下,磷酸三丁酯聚合体及脱氢磷酸三丁酯的形成机理

γ射线辐照TBP,TBP的激发单态分解导致形成不饱和TBP(脱氢TBP),其G_(双键)=1.01±0.1,H_2O与O_2的存在可抑制不饱和TBP的生成。TBP的第二种激发态(三重态)可导致形成TBP聚合体,O_2的存在可抑制TBP聚合体的形成,但使DBP的G值增大。     

RAFM钢中H+辐照空位型缺陷的慢正电子束研究

为研究低活化铁素体/马氏体(Reduced Activation Ferritic/Martensitic,RAFM)钢的辐照损伤机理,利用慢正电子技术研究了H~+辐照RAFM钢时所产生的空位型缺陷及其对于材料微观结构的影响。H~+能量和剂量分别为100 keV和1×10~(15)cm~(-2)、1×10~(16) cm~(-2)、1×10~(17)cm~(-2)。慢正电子束多普勒展宽测量结果可得,S参数随着剂量的增大而增大,W参数呈现正相反的趋势。样品中主要辐照区域为142～348 nm,此范围内有大量缺陷产生,辐照产生的主要为空位型缺陷,其中多为氢-空位复合体缺陷,辐照缺陷的浓度随着H~+剂量的增大而增加。空位型缺陷的尺寸大小也随着辐照剂量的增大而有所变化,辐照剂量达到10~(17)cm~(-2)时,S-W曲线斜率发生变化,故辐照缺陷类型发生明显变化,有较大尺寸的缺陷产生。     

UO_2(HCOO)_2·H_2O在290K-10K的红外光谱及~(235)U-~(238)U同位素位移的研究

本文通过测定甲酸铀酰[UO_2(HCOO)_2·H_2O]在290K-10K的红外光谱,确定了该化合物铀酰基团(O-U-O)v_(as)振动峰位,研究了温度对峰宽、峰位的影响,并采用差减及峰内标法估算了甲酸铀酰在290K-10K的同位素位移值。测得290K,77K及10K时~(238)U的v_(as)值分别为931.90cm~(-1),930.82cm~(-1)和930.74cm~(-1),~(235)U-~(238)U同位素位移△v分别为0.63cm~(-1),0.67±0.18cm~(-1)和0.71±0.21cm~(-1),位移值与理论计算值接近。     

C注入GaN光致发光和微区拉曼散射的研究

使用光致发光谱和微区拉曼散射谱的测量,研究了C离子注入原生无黄光发射的GaN。C离子的注入剂量范围为1013-1017cm-2。发光谱的研究表明,C注入的GaN经950℃高温退火后出现了黄光发射,而近带边发射峰的峰位则由于C注入产生的某种缺陷而发生了蓝移。拉曼谱的测量表明,GaN薄膜的应力不随C注入而改变。当注入剂量增加至1015cm-2时,出现了与无序激活拉曼散射相关的300cm-1峰,但随着注入剂量进一步增加,300cm-1峰减弱并未消失,这被归因于注入束流强度随注入剂量增大。     

氯代有机污染物辐照脱氯的研究进展

本工作对电离辐射引发的典型氯代有机污染物的脱氯降解机理进行了综述,重点回顾了氯酚、多氯联苯、三氯乙烯和四氯乙烯辐照脱氯降解的研究现状.氯酚在氧化条件下与羟基自由基(·OH)反应首先形成·OH加成物,然后逐步脱氯;在还原条件下水合电子(e-aq)与氯酚直接发生选择性反应脱氯,生成苯酚和氯离子.多氯联苯在有机溶剂中的辐照降...     

Radiation-chemical stability of TBP in solutions of hydrocarbons

The radiolysis of binary mixtures containing tributyl phosphate (TBP) and ali-phatic or aromatic hydrocarbons is discussed. The radiation-chemical stability of the irradiated systems was measured according to the yields of the acid esters (di- and monobutyl phosphate) and gaseous products, as welI as according to the change in the distribution coef ficients of plutonium and zirconium between the irradiated organic phase and an aqueous solution containing 2M nitric acid and the nitrates of these metals.The concentration dependence of the radiation chemical yields of gaseous and acid radiolysis products gives evidence of a deviation from the additivity rule and of a transfer of energy from the aliphatic hydrocarbon to TBP. As a result of replacement of the aliphatic hydrocarbon by an aromatic hydrocarbon, the yields of the radiolysis products are sharply reduced. The influence of aromatic hydrocarbons upon the radiation-chemical stability of TBP is confirmed by data on the distribution coefficients of plutonium and zirconium, the values of which are determined to a considerable degree by the content of dibutyl phosphate-the basic product of the radiolysis of TBP.Translated from Atomnaya Énergiya, Vol. 21, No. 4, pp. 281–285, 1966.     

基于三极管的CFBR-Ⅱ堆辐射损伤常数测定

为获取CFBR-II堆与其他装置建立辐射损伤等效系数的实验依据,在CFBR-II堆稳态工况下开展典型三极管的辐射损伤常数测定工作。结果表明,硅三极管的辐射损伤常数在4×10-16～6×10-16 cm2之间;对于直流增益与中子注量的线性关系的适用范围,集电极注入电流可以拓展到300 mA。     

水溶液辐射分解产物对金属材料腐蚀的影响

实验研究了水辐射分解作用对高放废物深地质处置容器材料的影响。在高放废物深地质处置库附近的地下水,受辐射线作用后分解出氧、氢和氧化产物(例如H_2O_2等),于是在高放废物容器周围形成一个氧化场,导致高放废物中的某些重要放射性核素(例如U,Np和Tc)易溶于水,并向远域迁移。本实验中的含FeSO_4(0.13 mol/L)水溶液在吸收剂量为0、20、60、180、500kGy的射线作用下,其氧化还原电位(Eh)值由+357mV增至+414 mV;在不同吸收剂量的射线作用下,金属Cu、金属Al、0.357 mv金属Fe和不锈钢(后者是我国拟采用的高放废物包装容器材料),在水溶液中的氧化侵蚀强度,分别比在无辐射情况下的大0.2-6.1倍。     

电子束辐照聚二甲基硅烷的结构分析

在室温、真空条件下,利用加速器产生的高能电子束辐照聚二甲基硅烷（PDMS）试样,研究吸收剂量对其结构的影响。通过气相色谱质谱联用分析可知,辐照过程中产生了少量H₂和CH₄,且H₂的产率高于CH₄。FT-IR、激光拉曼光谱以及XRD分析结果表明,经超高剂量（MGy级）辐照后,聚二甲基硅烷的化学结构未发生明显变化,其晶态结构也未遭破坏。这些结果说明,PDMS具有异乎寻常的耐辐射性能,这可能归因于其主链上规整Si—Si键的σ电子离域运动所形成的σ共轭体系的特殊结构。     

Gaseous products generated by radiation degradation of N,N-diethylhydroxylamine aqueous solution

In this paper, gaseous products generated by radiation degradation of N,N-diethylhydroxylamine (DEHA)in aqueous solution are studied. The results show that by 10～1000 kGy irradiation of the solution in DEHA volume fraction of hydrogen did not change much with different concentrations of DEHA. The volume fraction of methane and ethane decreased, but that of ethene increased, with increasing DEHA concentration. The volume fraction of hydrogen, methane and ethane increased with the dose. The relationship of the volume fraction of ethene with the dose had something to do with the DEHA concentration.     

三辛基氧化膦辐解乳化性质的研究

为了探讨三烷基氧化膦（TRPO）辐射乳化的原因及解决的办法,以三辛基氧化磷（TOPO）为TRPO的模型,对TOPO的γ辐解进行了研究。被辐照样品溶于环已烷后,用5％的Na2CO3和三蒸水萃取分离TOPO的辐解产物。在水萃过程中出现了乳化现象。乳化程度与体系的吸收剂量pH值有关,随吸收剂量的增大而增大。辐解产物的总G值随吸收剂量的增大而减小。同时,对乳化物的结构分析表明,引起乳化的物质可能主要为TOPO与次瞵酸及其酯组成的寡聚物。     

PARIS project: Radiolytic oxidation of molecular iodine in containment during a nuclear reactor severe accident: Part 2. Formation and destruction of iodine oxides compounds under irradiation - Experimental results modelling

In the case of a severe accident in a nuclear Light Water Reactor (LWR), the high radiation fields reached in the reactor containment building due to the release of fission products from the reactor core would induce air radiolysis. The air radiolysis products (ARP) could, in turn, oxidise gaseous molecular iodine (I₂) into aerosol-borne iodine-oxygen-nitrogen compounds, abbreviated as iodine oxides (IO_x). These reactions involve the conversion of a gaseous iodine compound resulting in a change of the iodine depletion rate from the containment atmosphere. Kinetic data were produced within the first part of PARIS project on the air radiolysis products formation and destruction. The second part of the PARIS project as presented in this paper deals with the impact of the ARP on the conversion of I₂ into IO_x. The objective was to provide a database to develop new or to validate existing kinetic models of formation and destruction of iodine oxides.The iodine tests of the PARIS project, performed at very low, realistic iodine concentrations, constitute an important database to further develop or validate empirical and mechanistic models on radiolytic I₂ oxidation. In the presence of painted surface areas or silver aerosol surface areas, radiolytic I₂ oxidation is negligible compared to I₂ adsorption on these surfaces for the conditions examined. However, radiolytic I₂ oxidation remains very efficient if surface areas are small or if they are made of the relatively non-reactive stainless steel.     

PARIS project: Radiolytic oxidation of molecular iodine in containment during a nuclear reactor severe accident: Part 1. Formation and destruction of air radiolysis products—Experimental results and modelling

In case of a hypothetical severe accident in a nuclear LWR (light water reactor), the high radiation fields reached in the reactor containment building due to the release of fission products from the reactor core could induce air radiolysis. The air radiolysis products could, in turn, oxidise gaseous molecular iodine into aerosol-borne iodine-oxygen-nitrogen compounds. Thereby, this reaction involves a change of iodine speciation and a decrease of iodine volatility in the reactor containment atmosphere. Kinetic data were produced within the PARIS project on the air radiolysis products formation and destruction, and on their reaction with molecular iodine, with the objective of developing and validating existing kinetic models.The current paper includes the non-iodine tests of the PARIS project whose objective was to determine the rates of formation and destruction of air radiolysis products in the presence of both structural containment surfaces (decontamination coating (“paint”) and stainless steel), aerosol particles such as silver rich particles (issued from the control rods) in boundary conditions representative for LWR or PHEBUS facility containments.It is found that the air radiolysis products concentration increases with dose and tend to approach saturation levels at doses higher than about 1 kGy. This behaviour is more evident in oxygen/steam atmospheres, producing ozone, than in air/30% (v/v) steam atmospheres, the latter favouring the model-predicted on-going production of nitrogen dioxide even at very high doses. No significant effect of temperature, dose rate and hydrogen addition (4%, v/v) was observed. Furthermore, the inserted surfaces do not exhibit significant effects on the air radiolysis concentrations. However, these “non-noticeable influence” could be due to a masking of small effects by the appreciable scattering of the experimental air radiolysis product concentrations.The PARIS results are then analysed using two different kinetic models, an empirical and a mechanistic one. The kinetic constants within an empirical model including formation and destruction of air radiolysis products, derived from PARIS results, are in reasonable agreement with those determined previously for lower steam fractions.From the mechanistic model IODAIR-IRSN, it is concluded that ozone is the predominant air radiolysis product at low doses in air/steam atmospheres. At doses higher than 1 kGy, nitrogen dioxide becomes increasingly important, both due to an increase in its concentration and due to a simultaneous decrease in ozone concentration.