草酸偏二甲肼洗涤PUREX流程污溶

在PUREX流程萃取过程中,高产额裂变产物元素Zr与TBP降解产物HDBP,H2MBP等生成配合物是导致产生界面污物的主要因素。在探讨污溶剂中Zr和HDBP洗涤去污机理的基础上,采用草酸偏二甲肼为洗涤剂,以配制的30%TBP/OK-Zr,30%TBP/OK-HDBP两种模拟污溶剂为研究物,以X射线荧光光谱法测定有机相中的Zr含量,自动电位滴定法测定有机相中HDBP的含量。研究了洗涤温度、相比、洗涤剂浓度等因素对洗涤效果的影响;对比了草酸偏二甲肼和碳酸钠对Zr和HDBP洗涤效果。草酸偏二甲肼水溶液洗涤30%TBP/OK中Zr和HDBP时,适宜条件为:温度40～60℃,相比V(o)/V(a)=1,草酸偏二甲肼浓度为0.4～0.6mol/L,为提高对HDBP的洗涤效果,在加入少量偏二甲肼,使溶液中游离偏二甲肼浓度为0.2～0.3 mol/L时,草酸偏二甲肼洗涤Zr的效果略优于碳酸钠,DF(Zr)可达143;洗涤HDBP的效果与碳酸钠相当,DF(HDBP)可达100以上。     

21 特殊有机高放废液中HDBP和H2MBP的分析

特殊有机高放废液成分复杂。作为TBP的降解产物HDBP和H2MBP，可能是构成特殊有机高放废液的主要成分。对此，须测定特殊有机高放废液中HDBP和H2MBP的含量，以为其处理提供依据。     

硝酸溶液中锆在硅胶上吸附的容量研究

在乏燃料后处理Purex流程中,裂变产物元素锆可与TBP的降解产物生成化合物,进而形成聚合物,产生界面污物,形成第三相,阻碍萃取过程的正常进行。用硅胶吸附的方法可除去锆,并具有良好的选择性。     

硝酸溶液中铌的溶剂萃取研究 Ⅲ.辐照的TBP萃取铌

研究了辐照的TBP从不同水相溶液中萃取铌的行为和对有机相中铌的洗涤效果。TBP的辐照剂量为1×10~3～7.5×10~5Gy。观测了钼、铀和F~-等对辐照的TBP萃取铌的影响。初步探讨了界面污物与D_(Nb)的关系及其对~(95)Nb的吸附。结果表明:辐照的TBP萃取铌时,D_(Nb)增加的主要原因是HDBP的作用。TBP和HDBP间的反协同效应使辐照的TBP萃取铌受到抑制。钼会明显地削弱TBP和HDBP的反协同效应,因而使辐照的TBP萃取铌时D_(Nb)显著增加。     

锆在HNO_3-HDBP-煤油体系中的萃取行为

一、前言为了了解锆在Purex流程中的行为,进行了HDBP萃取~(95)Zr的初步研究。在Purex流程中,所采用的萃取剂是30%TBP-煤油。由于放射性辐照及酸等因素的影响,导致了TBP-煤油的降解。其降解产物有HDBP、H_2MBP、气体产物以及高分子聚合物。此外辐照剂量大时也可产生H_3PO_4、少量丁醇乙醚等异羟肟酸、各种醛、肟羧酸、羟胺、有机硝酸酯、有机硝基化合物、有机亚硝基化合物等。HDBP在工艺流程中与金属     

TBP辐解产物对U(Ⅳ)-肼和乙异羟肟酸反萃Pu(Ⅳ)的影响

研究了磷酸三丁酯(TBP)辐解产物磷酸二丁酯(HDBP)和磷酸一丁酯(H2 MBP)对U(Ⅳ)-肼以及乙异羟肟酸(AHA)反萃Pu(Ⅳ)的影响,考察了相接触时间、相比(o:a)、还原剂浓度、HNO3浓度、肼浓度、TBP辐解产物HDBP和H2 MBP浓度等条件对含有HDBP或H2 MBP的30％(体积分数)TBP/煤油中...     

硝酸中铌的溶剂萃取行为

本文论述了硝酸中溶剂萃取铌的行为。试验过的萃取剂包括TBP、HDBP、H_2MBP辐照的TBP、HDEHP、TTA以及7402季铵盐等。文章较详细地叙述了钼和锆对溶萃取铌的特殊影响及辐照的TBP萃取铌的行为。同时提到水相中存在氟和铀对萃取铌的影响。实验观察到界面污物与D_(Nb)无直接关系,但对~(94)Nb有吸附。还讨论了可萃取铌的状态和萃取机理,以及~(95)Nb进入有机相的原因。最后,还就提高对~(95)Nb的去污系数提出了建议。     

在Na2CO3溶液中季铵盐萃取Zr机理的研究

用红外光谱分析和季铵盐萃取研究了Zr—DBP界面物在碳酸钠溶液中的溶解机理。结果表明,Zr—DBP界面物在碳酸钠溶液中生成了能溶于水的配合阴离子Zr(CO3)4^4-或ZrO(CO3)3^4-,Zr—DBP界面物溶解前后与纯HDBP的红外谱图相比,溶解液中DBP的P—O键的特征峰与纯HDBP的更为接近。说明界面物在溶解Na2CO3过程中,破坏了原有界面物的配合,DBP不再与Zr配合,而以自由离子形式存在。     

H_2MEHP水溶液的γ辐解

前言萃取剂磷酸三丁酯(TBP)和二(2-乙基己基)磷酸酯(H_2MEHP)的降解产物(如HDBP、H_2MBP和H_2MEHP)的水溶液的辐解情况很少报道。仅在五十年代,有人报道过几种单烷基磷酸酯水溶液的辐解情况,发现除了产生H_3PO_4外,还生成不稳定的酰基磷酸酯;后来,有人报道HDBP、H_2MEHP等在同水相搅拌或溶于水的情况下辐     

热解燃烧废TBP/OK料液配制

采用热解燃烧法处理放射性废磷酸三丁脂/煤油(TBP/OK)溶剂时,为避免热解产生的磷酸腐蚀以及使其充分热解,需在TBP／OK溶剂中加八固磷剂和表面活性剂,并配成均匀、稳定料液。本工作研究配制TBP／OK乳状液和TBP主要降解产物磷酸二丁脂(DBP)对乳状液配制的影响。利用放射性废TBP／OK溶剂进行了热解燃烧废TBP/OK料液配制的配方验证，并推荐了一种能够满足工业规模处理放射性废TBP／OK的料液配方。     

Crud in Solvent Washing Process for Nuclear Fuel Reprocessing

In a solvent washing process for nuclear fuel reprocessing, one of the important problems is a formation of stable emulsions between organic and aqueous phases. These emulsions are called interfacial “crud”. Crud is defined as an emulsion stabilized by finely dispersed solids. These stable emulsions lead to decreased washing efficiency, lower phase separation, disturbance of the interfacial control at the settler of the extractor, and so on. Cruds formed by precipitates of Zr and tributyl phosphate (TBP) degradation products, such as di-n-butyl phosphate (HDBP), mono-n-butyl phosphate (H₂MBP), and phosphoric acid (H₃P0₄) are studied by experiments using a sodium carbonate solution as a washing reagent. Experimental results show that not only pH value of the washing reagent, but also phosphate and zirconium mole ratio (P/Zr) are important in crud formation. Moreover, it is shown that the complex of Zr and HDBP, or Zr and H₂MBP has a significant role in stabilizing emulsions. However, the complex of Zr and H₃P04 is not effective in stabilizing cruds.     

“The Third Phase” of Extraction Processes in Fuel Reprocessing, (I)

Formation conditions, compositions and structures of precipitates or “the third phase” were systematically examined in the systems of Zr and radiation depleted products of TBP, such as HDBP, H₂MBP, H₃PO₄, by means of elemental analysis, X-ray diffraction, infrared spectra and ¹H-NMR. It was confirmed that one of the most important origins for the third phase is a complexation between Zr ion and the depleted products of TBP. Followings were also elucidated:

(1) When the depleted products co-exist with each other, the cooperative effects on the precipitate formation appear in low acid solutions.

(2) Precipitate formation depends on the mole ratio of HDBP/Zr. The amount of precipitate reaches the maximum at the mole ratio of approximately 2 and decreases with increasing concentration of HDBP and finally disappears at approximately 10.

(3) Precipitate formed at the mole ratio of approximately 2 has the chemical formula, Zr (NO₃)₂ (HDBP)₂ (OH)₂.

(4) Precipitates of the Zr-H₂MBP system begin to appear at the concentration of H₂MBP in one order of magnitude smaller than that of HDBP in Zr-HDBP system.

(5) Precipitates of Zr-H₂MBP system have no NO₃ ion and a basic structure of Zr-(HMBP)₂(OH)₂ with an interlayer distance of 16 Å.     

锆与H2MBP生成萃取界面污物的行为研究

观察了ＴＢＰ的降解产物磷酸一丁酯（Ｈ２ＭＢＰ）与锆在３０％ＴＢＰ正十二烷／ＨＮＯ３体系中产生界面污物的现象；进行了锆浓度，Ｈ２ＭＢＰ浓度以及硝酸浓度对界面污物生成的影响，并对界面污物固体进行了红外光谱分析和Ｘ射线荧光分析。     

Removal of Fission Products and Their Complexing Agents from Degraded Solvent by Ion Exchange Method

Removal of fission products and their complexing agents from chemically degraded TBP/kerosene and particularly from the kerosene diluent, was studied. With the use of column technique with mixed anion and cation exchange resins, more than 80% of the fission products and their complexing agents were removed. The carboxylic acids, which constitute one of the degradation products bringing about decrease of uranium extractability, were completely removed together with the complexing agents thereof by anion exchange resin. Removal was also obtained of monobutyl and dibutyl phosphoric acids (H₂MBP and HDBP), which can retain fission products and which in actual practice are liable to be formed by hydrolysis of TBP under intensive irradiation with concentrated nitric acid and/or at the elevated temperatures.     

过氧化氢湿法氧化模拟有机污物的研究

用过氧化氢湿法氧化处理有机污物,研究了过氧化氢的投加量和投加方式,催化剂以及pH值等对反应的影响。结果表明,为提高H2O2的利用率,H2O2应以间歇式投加,选取Fe^2 作催化剂,体系pH值为1～2。为保证反应快速启动和平稳进行,反应时将催化剂总投加量的1／3提前与要分解氧化的物质混合一段时间,剩余2／3在反应进行中连续定量滴加,并于反应结束前半小时投加完毕。正交试验表明,分解2．00g界面污物的最佳实验条件为：pII-1．10mL30％H2O2溶液,10mL 0．1mol／L Fe^2 溶液。反应结束时,反应釜底部的白色残余物经红外分析和元素分析表明主要是磷酸盐。H2O2湿法氧化能够有效分解TBP／OK,HDBP／OK溶液和界面物。     

Separation of Precipitate-forming Elements during High Level Waste Treatment Using Acidic Zirconium Salt of Dibutyl Phosphoric Acid

Iron extraction and the limits of iron dibutyl phosphate precipitation were investigated for use in TPE/RE recovery and partitioning with the use of the acidic Zr salt of dibutyl phosphoric acid (ZS HDBP, Zr:HDBP = 1:9), dissolved in 30% TBP with Isopar-L. The presence of Mo and the solvent loading with RE affected the Fe extraction in the opposite ways. Slow kinetics and process irreversibility were found for the Fe extraction with the ZS HDBP solution. To increase acceptable Fe concentration in a HLW, reduction of Fe(III) by ascorbic acid (AA) was studied to be carried out continuously in the feed flow, just before entering the head contactor of the partitioning extraction cycle. The Mo extraction is of the same order as that of TPE and RE; so its selective stripping prior to the TPE/RE separation is required. This can be done using the DTPA or H₂O₂ solution in diluted nitric acid. The effectiveness of the process was verified by laboratory scale trials on the centrifugal contactor rig using simulated HLW. The Zr-to-HDBP ratio of 1:6 was found to be useful to decrease the Fe and Mo extractability for their better backwashing with complexants.     

30%TBP-煤油循环使用过程中的辐解行为

为了了解溶剂在乏燃料后处理真实使用过程的辐解稳定性,对比研究了30%TBP-煤油-HNO3体系在γ和α的静态累积辐照和动态循环辐照情况下的辐解行为。研究结果表明:静态累积辐照所引起的溶剂辐解产物生成量、钚保留和钌保留等性能的变化比动态循环辐照明显;当辐照吸收剂量达到1.0×105 Gy(相当于动态循环辐照20次)时,静态累积辐照引起的溶剂钚保留值10倍于动态循环辐照,证实了在乏燃料后处理工艺过程中,通过溶剂的酸碱洗涤,去除HDBP、H2MBP等主要辐解产物,可提高溶剂的循环使用寿命。同时研究结果显示,溶剂的α辐照损伤大于γ辐照。     

亚硝酸分配比测定及其初步模拟计算

Purex流程的计算机模拟研究有助于流程的优化和改进。HNO2不可避免地存在于Purex流程中,影响许多重要核素的萃取,因此需要建立HNO2的分配比模型,以完善Purex流程计算机模拟程序。采用酸碱滴定法和重氮偶联法同时测定了平衡水相和有机相中HNO3和HNO2的浓度,进而获得分配比数据。在研究范围内,水相HNO2浓度对HNO2和HNO3的分配比影响不明显。水相HNO3浓度升高,HNO2的分配比下降,而HNO3的分配比先升高后下降。有机相中TBP浓度升高,HNO2和HNO3的分配比均增加。初步建立了HNO2分配比与水相酸度和自由TBP的关联式,计算结果与实验值比较吻合。     

Modified TRUEX Process for the Treatment of High-Level Liquid Waste

The TRUEX process has been examined to recover Am and Cm from the high-level liquid waste of Purex reprocessing plant. Continuous counter current extraction and back-extraction experiments were carried out by a mixersettler using simulated waste solution for three process flowsheets, i.e. a process flowsheet developed by Argonne National Laboratory and other two process flowsheets which were modified in the scrub stage. The result indicates that the process flowsheet of Argonne National Laboratory cannot be applied for the high-level liquid waste containing high concentrations of lanthanide and actinide elements because of the formation of insoluble salts of these elements with oxalic acid, which is added to restrict the extraction of fission products such as Mo and Zr. A modified process flowsheet, which had only one scrub stage with high concentration of nitric acid, was found to be the best of three process flowsheets examined, where Nd as a simulated element of Am and Cm was sufficiently recovered and any precipitation of oxalate salt was not observed.     

锆与HDBP形成萃取界面污物的行为研究

研究了锆与ＨＤＢＰ形成界面污物的行为，分析了Ｚｒ－ＤＢＰ界面污物的基本构成，并就观察到的ＨＤＢＰ与锆形成界面污物过程出现的“异常”现象进行了探讨，提出了产生这种现象的可能机理。