Fundamental Study of the Sulfide Reprocessing Process for Oxide Fuel (I) Study on the Pu,MA and FP Tracer-Doped U3O8

For the recovery of fuel materials from spent nuclear fuel, a novel reprocessing process based on the selective sulfurization of fission products (FP) has been proposed, where FP and minor actinides (MA) are first sulfurized by CS₂ gas, and then, dissolved by a dilute nitric acid solution. Consequently, the fuel elements are recovered as UO₂ and PuO₂. As a basic research of this new concept, the sulfurization and dissolution behaviors of U, Pu, Np, Am, Eu, Cs, and Sr were investigated by γ-ray and α spectrometries in this paper using ²³⁶Pu-, ²³⁷Np-, ²⁴¹Am-, ¹⁵²Eu-, ¹³⁷Cs-, and ⁸⁵Sr-doped U₃O₈ samples. The dependence of the dissolution ratio of each element on the sulfurization temperature was studied and reasonably explained by combining the information of the sulfide phase analysis and the chemical thermodynamics of the dissolution reaction. The sulfurization temperature ranging from 350 to 450°C seems to be promising for the separation of FP and MA from U and Pu, since a clear difference in the dissolution ratio between FP and U was derived by the sulfurization treatment in this temperature range.     

Np在北山花岗岩裂隙填充物上的吸附行为

采用批式实验法在低氧条件下研究Np(Ⅴ)在北山花岗岩裂隙填充物上的吸附行为,探讨地下水pH、CO₃^2-、腐殖酸及裂隙填充物各组分等因素对吸附的影响。实验结果表明：裂隙填充物对Np(Ⅴ)有较强的吸附能力,吸附分配比K_d为843 mL/g;K_d随pH先增大后减小,当有CO₃^2-和腐殖酸存在时K_d减小;绿泥石和长石是北山花岗岩裂隙填充物吸附Np(Ⅴ)的主要贡献者。     

237Np、238Pu、241Am和90Sr在水泥、变质水泥固化块和水泥砂浆粉-土壤中迁移的野外试验研究

本文介绍了237Np、238Pu、241Am和90Sr在水泥、变质水泥和水泥砂浆粉-土壤体系的野外迁移试验方法和结果.将以石英砂为载体的四种核素的示踪源层,铺放在普通水泥试块和变质水泥试块内,以及以水泥砂浆粉为载体的四种核素的示踪源层,埋置在黄土包气带试验坑50 cm深处进行实验.在喷淋降水(5 mm/h×3 h/d)和天然降水两种条件下,核素在普通水泥试块、变质水泥试块和水泥砂浆粉中,三年的野外迁移试验结果显示,四种核素均看不出明显迁移.经过1 100多天,每种示踪剂迁移距离都在1 mm范围内.每种示踪剂从源层迁移到试块内的量只占源层投放量的5%左右,95%左右的核素仍存留在示踪源层内.尽管埋置后的变质水泥试块性能明显不如普通水泥试块,但核素在两种水泥试块中的迁移规律并未发现明显差异.核素在水泥砂浆粉中近1 100天野外实验期间迁移不到1 mm,说明水泥砂浆粉对核素迁移有很强的阻滞作用.     

Thermodynamic analysis of the gas phase composition over uranium-plutonium carbonitride irradiated with fast neutrons

A thermodynamic analysis of the gas phase composition over uranium-plutonium carbonitride U_0.8Pu_0.2(C_0.5N_0.5)_0.995 irradiated with fast neutrons was carried out with respect to temperature and burnout. In the temperature range of 900–2500 K, accumulation of fission products in fuel resulted in the formation of a multicomponent gas phase containing the following basic elements and compounds: volatile (Cs, Sr, Ba, Se, Te, I, Pd, CsI, Cs₂I₂, BaI, SrI, BaI₂, SrI₂, LaSe, TeSe, and LaTe), nitrogen-containing components (N₂, N, CN, CN₂, C₂N₂, UN, UN₂, PuN₂, CsN, CeN, LaN, YN, MoN, and ZrN), carbon-containing components (C, UC, UC₂, UC₄, PuC, PuC₂, PuC₄, ZrC, ZrC₂, YC₂, CeC₂, LaC₂, and NdC₂), and hardly volatile metals (U, Pu, Ru, Rh, Pd, Y, Ce, La, Nd, Tc, Mo, and Zr). The partial pressures of the said gas phase components over carbonitride fuel were calculated with respect to temperature and burnout (up to 18%).     

Growth paths for the sulfurization of Cu-rich Cu/In thin films

In-situ energy-dispersive X-ray diffraction performed at the BESSY and HASY-LAB synchrotron facilities was used to observe sulfur pressure dependent growth paths for the formation of CuInS₂ thin films from Cu-rich metallic precursors. CuInS₂ can form directly from the intermetallic phases, through binary sulfides or via CuIn₅S₈. Particular attention is given to the latter reaction sequence, typical of rapid thermal processing (RTP), with complementary EDS and SEM analysis.     

Adhesion of proton beam written high aspect ratio hydrogen silsesquioxane (HSQ) nanostructures on different metallic substrates

Hydrogen silsesquioxane (HSQ) behaves as a negative resist under MeV proton beam exposure. HSQ is a high-resolution resist suitable for production of tall (<1.5 μm) high aspect ratio nanostructures with dimensions down to 22 nm. High aspect ratio HSQ structures can be used in many applications, e.g. nanofluidics, biomedical research, etc. Isolated HSQ nanostructures, however, tend to detach from substrates during the development process due to the weak adhesive forces between the resist and the substrate material. Larger proton fluences were observed to promote the adhesion. To determine an optimal substrate material and the proton irradiation doses for HSQ structures, a series of 2 μm long and 60-600 nm wide free-standing lines were written with varying fluences of 2 MeV protons in 1.2 μm thick HSQ resist spun on Ti/Si, Cr/Si and Au/Cr/Si substrates. The results indicate that the Ti/Si substrate is superior in terms of adhesion, while Au/Si is the worst. Cr/Si is not suitable as a substrate for HSQ resist because debris was formed around the structures, presumably due to a chemical reaction between the resist and Cr.     

N-甲基甲异羟肟酸的合成及其与Np(Ⅳ)、Pu(Ⅳ)配合物稳定常数的测定

以甲酸乙酯和N-甲基盐酸羟胺为主要原料,在乙醇-水体系中合成N-甲基甲异羟肟酸（NMFHA）,并通过元素分析、红外光谱、质谱分析和核磁共振波谱等方法对其结构进行表征。TTA萃取法测定结果表明,在1.0mol/LHNO₃体系中,Np(Ⅳ)、Pu(Ⅳ)与NMFHA形成稳定的1∶2的配合物,其累积稳定常数分别为：β₁(Np(Ⅳ))＝8.83×10⁹,β₂(Np(Ⅳ))＝1.01×10¹⁹;β₁(Pu(Ⅳ))=7.78×10¹⁰,β₂(Pu(Ⅳ))＝5.80×10¹⁹。     

'99 237 Np放射性标准溶液的活度测量比对

本文总结了1999年国内组织的237Np放射性标准溶液活度测量比对的各个实验室的测量结果,共有3种不同的装置参与了测量,获得了6个测量数据,比对最后结果的算术平均值:(1704±16.4)Bq·g-1.     

食品中~(237)Np 和~(239)Pu 的同时测定

本文给出了食品中~(237)Np 和~(239)pu 的同时分析方法,该方法用草酸钙浓集,用三正辛胺(TOA)从8N 盐酸体系中萃取,然后电沉积制源,在低本底α谱仪上测定。本方法对~(237)7Np 和~(239)Pu 的全程回收率分别为(80.1±9.6)%、(75.2±7.8)%;灵敏度分别为6.0×10~(-16)、6.1×10~(-16)Ci/g(灰)。本文还给出了五种食品中~(237)Np 和~(239)Pu 的分析结果。