Examination of 131I and 137Cs releases during late phase of Fukushima Daiichi NPP accident by using 131I/137Cs ratio of source terms evaluated reversely by WSPEEDI code with environmental monitoring data

To investigate what happened in reality during the Fukushima Daiichi Nuclear Power Plant accident, the phenomena within reactor pressure vessel and the discussion of ties with the environmental monitoring measurement are very important. However, the previous study that treats phenomena of the both has not necessarily advanced up to the present time. The source terms predicted by simulation codes such as MELCOR has not yet been consistent with the reverse estimation by WSPEEDI code using environmental measurement data. This study investigated ¹³¹I and ¹³⁷Cs release behaviors during the late phase of the accident to contribute to such examination using the ¹³¹I/¹³⁷Cs ratio of the new source terms predicted by Katata. The ¹³¹I release by the gas–liquid partition from the contaminated water in the 1F2 and 1F3 reactor buildings which was pointed out in the previous study was reevaluated using the new source terms. In addition, paying attention to the similarity of the core conditions between the Fukushima accident and the Phébus FPT3 experiment using the B₄C control rods, the release of organic iodine (CH₃I) during the 1F3 suppression pool venting, formation of CsBO₂ and its release behavior were examined which have not yet been sufficiently studied so far.     

Vaiidition of ORIGEN Computer Code by Measurements on Nuclear Fuels of JPDR-1

The depletion and production amounts of U, Pu, transplutonium nuclides and fission products (FPs) measured on the fuel of JPDR-1 were corrected to take account of the performance history of irradiation and cooling using the results of three-dimensional nuclear-thermo-hydrodynamic and nuclide depletion and production calculations. Except a few nuclides, the corrected values proved to agree well with the values calculated by the ORIGEN computer code. Further enhancement of calculational accuracy calls for systematic re-evaluation of neutron cross sections on the basis of neutron spectrum in nuclear fuel.     

放射性铯在沸石中的吸附与迁移的研究

研究了~(134)Cs在沸石中的吸附与迁移行为.用间歇法测定了~(134)Cs(作为~(137)Cs的示踪剂)在斜发沸石和丝光沸石等4组地质样品上的吸附比(R_d);研究了接触时间、沸石颗粒度、固液比、pH值和核素浓度对吸附比的影响,测定了吸附等温线和铯的吸附容量.用柱实验法研究了~(134)Cs在沸石柱中的吸附与迁移行为,测定了~(134)Cs在柱中的迁移分布.结果表明,沸石对Cs的吸附能力很强,对Cs而言,沸石是核废物处置的很好的回填材料.     

Cs(I) and Sr(II) Sorption onto Graphene Oxide

This article demonstrates the efficacy of graphene oxide (GO) for Cs(I) and Sr(II) removal from aqueous solutions in the presence of competing cations. The interaction mechanisms of Cs(I) and Sr(II) with GO were studied at varying pHs, ionic strengths, and solution compositions. Thermal treatment was studied as a possible approach to minimize the volume of secondary radioactive waste, and cumulative pre-concentration factors were recorded for both cations.     

焦磷锆钛的合成及其对铯离子的吸附性能

利用溶胶-凝胶法合成了4价双金属酸盐-焦磷锆钛（ZTPP）,采用扫描电镜(SEM)、傅里叶红外光谱（FT-IR）、比表面积及孔结构分析（BET）、热重-差热分析（TG-DTA）等手段对材料进行了分析和表征,结果表明焦磷锆钛是一种具有发达比表面积的无定形多孔材料,且具有很好的稳定性。吸附实验证明,焦磷锆钛随溶液中铯离子初始浓度增高,吸附容量增大,可达1.4 mmol/g;在不同酸度溶液和竞争阳离子存在的情况下可稳定有效的吸附铯离子,吸附容量稳定;通过调整材料用量,其对铯离子的去除率可接近100%。     

负载型Cs2.5H0.5PW12O40醚化催化剂的制备与催化性能

制备了负载型磷钨酸铯(Cs_2.5H_0.5PW₁₂O₄₀)催化剂，考察了载体种类、载体性质、制备方法和制备条件对催化剂性能的影响,对制备的催化剂进行了表征，并考察了负载型Cs_2.5H _0.5PW₁₂O₄₀作为醚化催化剂的催化活性.结果表明,大孔硅胶是Cs_2.5H_0.5PW₁₂O₄₀的适宜载体，硅胶的钠含量越低制备的Cs_2.5H_0.5PW₁₂O₄₀/SiO₂催化剂的活性越高.采用一步法和二步法制备的Cs_2.5H_0.5PW₁₂O₄₀/SiO₂催化剂均具有较强的酸性、催化活性以及良好的稳定性,可以替代液体酸和阳离子交换树脂,成为一种环境友好的固体酸催化剂.     

Thermal Degradation of the Solvent Employed in the Next-Generation Caustic-Side Solvent Extraction Process and its Effect on the Extraction,Scrubbing, and Stripping of Cesium

As part of the ongoing development of the Next-Generation Caustic-Side Solvent Extraction (NG-CSSX) process, the thermal stability of its process solvent, the Next-Generation Caustic-Side Solvent (NGS) was investigated and shown to be adequate for industrial application. The solvent was thermally treated at 35°C over a period of 13 months whilst in dynamic contact with each of the aqueous phases of the current NG-CSSX process, namely SRS?15 (a highly caustic waste simulant), sodium hydroxide scrub solution (0.025 M), and boric acid strip solution (0.01 M). The effect of thermal treatment was evaluated by assessing batch extract/scrub/strip performance as a function of time, by monitoring the sodium extraction capacity of the solvent, and by analysis of the solvent using electrospray mass spectrometry. Current studies indicate that the NGS should be thermally robust without replenishment for a period of 7 months in the Modular Caustic-Side Solvent Extraction Unit (MCU), which has been treating waste using NG-CSSX since early 2014 at the Savannah River Site. The guanidine suppressor appears to be the solvent component most significantly impacted by thermal treatment of the solvent, showing significant degradation over extended operation.     

用于分离酸性废液中铯的连续性循环系统

针对核工业回收U、Pu过程所产生的放射性废液中Cs⁺的分离与富集,设计了连续电渗析富集分离技术(CEEST)。在不同温度下通过水热法合成一系列的多金属氧酸盐Na[Co₉-POM],通过SEM、XRD等方法对其进行了表征,并评价Na[Co₉-POM]材料的Cs⁺分离性能。探究不同的恒定电流、溶液pH值和共存离子存在下对分离Cs⁺过程的影响。实验结果表明,120℃下合成的材料Na[Co₉-POM]-120具有最佳的Cs⁺分离和回收能力,在恒定电流为0.03 A且pH<1的高酸性环境中,Cs⁺的分离率在150 min左右可达到96%以上。其共存离子对分离过程的影响较小,分离率仍可达到70%以上。为此提出了一种综合性连续循环的Cs⁺分离系统,成功实现了高酸放射性废液中Cs⁺的分离,并分析其在工业上的应用前景。     

Effect of water vapor on proton conduction of cesium dihydrogen phosphateand application to intermediate temperature fuel cells

The proton conduction and superionic phase transition of cesium dihydrogen phosphate, CsH₂PO₄ (CDP), were investigated under various humid conditions to evaluate the applicability of a CsH₂PO₄ solid electrolyte to an intermediate temperature fuel cell operating between 230 °C and 300 °C. The phase stability, superionic phase transition, and reversibility of dehydration of CsH₂PO₄ were evaluated under different ambient water vapor concentrations, from 0 to 90 mol%, through the measurements of conductivity. The dependence of conductivity on the water vapor concentration and the demonstrated reversibility of dehydration clearly showed the range in which CsH₂PO₄ is applicable to the intermediate temperature fuel cell. Additionally, we evaluated the protonic transport number of CsH₂PO₄, which was almost unity, and demonstrated fuel cell operation at 250 °C using a single cell fabricated with the CsH₂PO₄ electrolyte.