辐照食品的安全性及其国际利用动向

【日本《原子能视野》2003年5月刊报道】 前言 对食品及农作物进行射线照射的技术叫做食品辐照,用射线照射过的食品叫做辐照食品。进行食品辐照的目的是抑制发芽、推迟成熟、杀虫、杀菌等(见表1)。用于食品照射的电离射线只限于钴-60和铯-137的 g射线,以及能量在10 MeV以下的电子射线和能量在5 MeV以下的X射线。这样限定是为了防止被照射食品感生放射性,使用上面规定的射线就不用担心辐照食品会带有放射性。 辐照食品的健全性 必须深入探究辐照食品的安全性。实际上,研究人员所探究的有关辐照食品给人们健康带来的影响,与其说是针对其安…     

漯河辐照加速器控制系统研制

漯河辐照加速器是1台用于食品杀菌与保鲜等的8MeV电子直线加速器。文章从硬件组成、软件设计及辐照剂量控制等方面介绍漯河辐照加速器控制系统。近9个月的连续运行表明，该控制系统操作简便、运行稳定可靠。     

国外工业辐照加速器的应用及其进展

用于工业辐照的加速器绝大多数是电子加速器,其能量在0.15MeV到10MeV之间。近年来工业辐照技术发展很快,全世界用于射线辐照的总功率已超过15MW,其中,电子射线的功率14MW,~(60)Coγ射线的功率仅1MW。到1985年,全世界电子加速器消毒装置有十多台;用于工业辐照的电子加速器超过400台,其中,美国有265台、日本85台、苏联50台、欧洲其它国家10台。     

CCD在不同注量率电子辐照下的辐射效应研究

对TCD1209线阵CCD进行能量为11MeV的电子辐照试验,采用两种不同的注量率辐照后,对器件进行常温退火试验,在辐照与退火过程中考察CCD的光响应灵敏度、暗电流、参考电平、功耗电流等特性参数的变化规律。结果表明,CCD受电子辐照后主要产生电离总剂量损伤,在不同注量率电子辐照下的辐射损伤效应类似于MOS器件的时间相关效应。     

质子辐照对RADFETs的γ辐照剂量响应的影响研究

针对辐射敏感晶体管(Radiation Sensitive Field-Effect Transistors,RADFETs)在地面标定使用60Co γ射线源而实际空间应用时存在的质子电子辐射环境的差异性问题,进行了10 MeV质子和60Coγ射线的对比辐照与协和辐照试验.采用中带电压法(Mid-gap Techniq...     

世界食品辐照现状

【日本《原子力工业》1995年9月号第19页报道】 1980年以前,只有日本、荷兰、南非采用了食品辐照保藏技术。80年代以来,实施食品辐照处理的国家不断增加,迄今至少有28个国家拥有食品辐照设施,年处理量约50万吨。 1.在美洲地区,美国从1984年开始对干菜、调味品进行辐照处理,全部用于食品工业。佛罗里达州和衣阿华州,各建有一座供科研用的10MeV大型电子射线辐照设施。佛罗里达州的设施主要进行柑桔类水果     

脊型谐振腔镀铜工艺的研究

正电子辐射加工技术产业是一种高效的、生态的、安全的高新技术,随着辐照加工产业的不断发展,电子辐照加速器已被广泛应用于工业、农业、医疗卫生等领域。工业辐照领域0.5 MeV以下的低能加速器,机型技术以直流高压型为主,主要用于涂层固化、薄膜和片材的辐照加工;0.5～     

Ar离子辐照PET膜引起的表面结构和组分变化研究

用35MeV/u的Ar离子室温下辐照多层堆叠的半晶质的聚酯（PET）膜,采用X射线衍射技术和X射线光电子谱仪分析研究了辐照引起的表面结构和组分的变化。结果表明：Ar离子辐照PET膜引起了明显的非晶化转变和化学键断裂、断裂主要发生在甲氧基和羰基功能团上,并使这两个功能团中的C和O的比分相对减少。非晶化效应和化学键断裂同时依赖于离子的照射剂量和离子在样品表面的电子能量损失、剂量越高,表面电子能量损失越大,效应就明显。同时定性地讨论了结果。     

空气中两种辐照场下聚碳硅烷先驱丝的辐照不熔化效应

采用⁶⁰Co产生的γ射线与10MeV电子加速器产生的电子束在空气中辐照聚碳硅烷先驱丝。利用凝胶含量测定、红外光谱分析、凝胶渗透色谱分析、热重分析等手段研究了经两种辐照场辐照后聚碳硅烷先驱丝的凝胶含量、化学结构、分子量分布及其热分解特性的变化。结果表明：两种辐照场下能满足聚碳硅烷先驱丝不熔化处理的剂量分别为3、6.5MGy,两种辐照场下聚碳硅烷先驱丝的辐照不熔化机理一致,均通过形成Si—C—Si、Si—O—Si桥联结构而实现不熔化处理;在相同吸收剂量下,γ射线辐照不熔化效果较电子束辐照的好;γ射线辐照的聚碳硅烷先驱丝陶瓷产率也较电子束辐照的高。     

多能量双束线电子直线加速器研制

<正>研制了可输出电子能量为7.5、10、12 MeV的电子直线加速器,7.5 MeV电子束打靶产生的X射线用于食品辐照技术研究,10 MeV电子束用于科研教学和中试生产研究,12 MeV电子束主要应用于半导体材料辐照改性研究,多能量双束线电子直线加速器主体结构如图1所示。该电子直线加速器布置采用上下两层结构,电子枪、加速管、速调管、微波系统和脉冲变压器等置于第2层     

Gamma irradiation of PolyEthyleneTerephthalate and PolyEthyleneNaphthalate

The effect of gamma irradiation in air is investigated in two thermoplastic polyesters (PET and PEN), in order to evaluate the influence of aromatic density and the role of oxygen on radiation resistance. EPR measurements were carried out to detect radical stability against oxygen permeation and to provide radical characterization. Viscometric data reveal a different behaviour between films and thick samples. Positron annihilation spectra show a decrease of ortho-positronium intensity, which is more marked in film samples. ortho-positronium lifetime does not depend on the radiation dose.     

Void swelling and irradiation creep relationships

Recent analytical and theoretical work on swelling enhanced irradiation creep and stress effects on swelling is reviewed. A proposed explanation for swelling enhanced irradiation creep involves consideration of the role of vacancy loops. Theoretical work leads to the development of a new relationship for swelling enhanced creep which predicts larger irradiation creep rates at high levels of swelling (>5%) than the original formulation. Consideration is given to an additional effect of stress on swelling which involves a stress effect on the incubation dose. A constitutive equation is presented to describe this phenomenon. Design related illustrations are presented for these high fluence irradiation induced phenomena.     

辐射加工过程中错步辐照的判别及影响程度估算

为探讨判断动态步进辐射加工过程中错步对辐照产品吸收剂量的影响程度,通过不同辐照位影响的实验研究了44个辐照位对模拟产品瓦楞纸的吸收剂量贡献率。结果显示,个别辐照位对模拟产品的吸收剂量贡献极其明显,错步辐照在关键辐照位对吸收剂量影响较大。文章结合工艺特点分析了错步辐照的成因、核查错步辐照的判别条件和预防措施,并给出吸收剂量影响程度的测算公式。     

Evolution of the nanostructure of VVER-1000 RPV materials under neutron irradiation and post irradiation annealing

A high nickel VVER-1000 (15Kh2NMFAA) base metal (1.34 wt% Ni, 0.47% Mn, 0.29% Si and 0.05% Cu), and a high nickel (12Kh2N2MAA) weld metal (1.77 wt% Ni, 0.74% Mn, 0.26% Si and 0.07% Cu) have been characterized by atom probe tomography to determine the changes in the microstructure during neutron irradiation to high fluences. The base metal was studied in the unirradiated condition and after neutron irradiation to fluences between 2.4 and 14.9 × 10²³ m⁻² (E > 0.5 MeV), and the weld metal was studied in the unirradiated condition and after neutron irradiation to fluences between 2.4 and 11.5 × 10²³ m⁻² (E > 0.5 MeV). High number densities of ∼2-nm-diameter Ni-, Si- and Mn-enriched nanoclusters were found in the neutron irradiated base and weld metals. No significant copper enrichment was associated with these nanoclusters and no copper-enriched precipitates were observed. The number densities of these nanoclusters correlate with the shifts in the ΔT_{41 J} ductile-to-brittle transition temperature. These nanoclusters were present after a post irradiation anneal of 2 h at 450 °C, but had dissolved into the matrix after 24 h at 450 °C. Phosphorus, nickel, silicon and to a lesser extent manganese were found to be segregated to the dislocations.     

Biofilms and their modifications by laser irradiation

Biofilms are grown on different materials with various surface morphology and are investigated by light and scanning force microscopy. The growth patterns, coverage and adherence of the biofilm are shown to depend on the type of the substrate and its roughness as well as on the type of micro-organisms. Here we present investigations of Eschericia coli bacterial biofilms grown on the polymer material polyetheretherketone and also on titanium films on glass substrates. A Monte Carlo simulation of the growth process is developed which takes into account the aspect ratio of the micro-organisms and the diffusion of nutrient over the surface to feed them.

A pulsed nitrogen laser has been applied to the samples and the interaction of the laser beam with the biofilm and the underlying substrate has been studied. Because of the inhomogeneity of the biofilms the ablated areas are different. With increasing number of laser pulses more biofilm material is removed but there appears also damage of the substrate. The threshold energy fluence for the biofilm ablation is estimated and depends on the sticking power of the bacteria. Ablation rates for the removal of the biofilms are also obtained.     

抗菌素和柑桔的快中子辐射育种

辐射育种在国内外已进行了多年,但国内辐射育种过去大多用X射线、γ射线、电子束和激光束等射线源,以快中子作为辐射育种的一种手段时间不长,国内以复旦大学和广东测试分析所等单位开展得较早,并取得了较好的成果。从1979年开始,我们应用快中子射线源为抗菌素和浙江柑桔等开展辐射育种工作,经过几年的努力取得了一点效果。     

Production behavior of irradiation defects in vitreous silica under ion beam irradiation

The production behavior of irradiation defects in vitreous silica was studied by an in situ luminescence measurement technique under ion beam irradiation of H⁺ and He⁺. No apparent difference was observed in the luminescence spectra of specimens of different OH contents. The temperature dependence of the luminescence intensity at 280 and 460 nm was measured, and analyzed by considering the production mechanisms and kinetics of the irradiation defects of oxygen deficiency centers.