华南某预选低中放废物处置场岩土层渗透性能综合研究

采用渗水、注水、压水、抽水及室内渗透试验等多种测试方法,对我国华南某一预选低中放废物处置场内各岩土层的渗透特性进行分层测试,通过多种方法的综合研究得出处置场地内各岩土层的渗透系数,并基于计算结果评价各岩土层的渗透性能,指出区内微风化花岗岩可作为低中放废物的处置底板,中等风化花岗岩可作为备选处置底板,而冲积黏土则是处置单...     

Evaluation of nuclide release scenarios for a hypothetical LILW repository

A program for the safety assessment and performance evaluation of a low- and intermediate-level radioactive waste (LILW) repository system has been developed. Utilizing GoldSim (2006), the program evaluates nuclide release and transport into the geosphere and biosphere under various disruptive natural and manmade events and scenarios that can occur after a waste package failure. We envisaged and illustrated these events and scenarios as occurring after the closure of a hypothetical LILW repository, and they included the degradation of various manmade barriers, pumping well drilling, and natural disruptions such as the sudden formation of a preferential flow pathway in the far-field area of the repository. Possible enhancement of nuclide transport facilitated by colloids or chelating agents is also dealt with. We used the newly-developed GoldSim template program, which is capable of various nuclide release scenarios and is greatly suited for simulating a potential repository given the geological circumstances in Korea, to create the detailed source-term and near-field release scheme, various nuclide transport modes in the far-field geosphere area, and the biosphere transfer. Even though all parameter values applied to the hypothetical repository were assumed, the illustrative results, particularly the probabilistic calculations and sensitivity studies, may be informative under various scenarios. (GoldSim, LILW, Nuclide transport, Safety assessment, Scenario).     

论低中放废物近地表处置岩土工程勘察的几个问题

针对低中放废物近地表处置中岩土工程勘察目的不明确、勘察内容界定不明、实际应用难以操作等问题,论述了低中放废物近地表处置场岩土工程勘察的目的、性质、勘察内容的拓展以及勘察过程中基于环境影响评价的考虑和对预选场地水文地质条件的着重认识等问题,并运用实际案例进行了佐证。结果表明由于预选场地勘察的主要目的之一在于为其环境影响评价提供数据支撑,因此勘察性质表现出"环境岩土"的特征,勘察内容较常规岩土工程勘察在水文地质、水文地球化学、各种原位和室内试验以及现场监测等方面均存在较大拓展,更加注重对预选场地环境影响评价内容的考虑和水文地质条件的全面和量化认识。     

Dynamic assessments on high-level waste and low- and intermediate-level waste generation from open and closed nuclear fuel cycles in Republic of Korea

We estimated the generation of low- and intermediate-level waste (LILW) and high-level waste (HLW) from open and closed nuclear fuel cycles. The closed fuel cycle reflects the development and deployment of fast reactors and pyroprocessing from 2013 to 2100, while the open fuel cycle only considers pressurized water reactors. The closed fuel cycle hardly affects short-term spent fuel management but can save nearly 60% space of interim storage compared with the open fuel cycle. Compared with the open fuel cycle, the accumulated volume of HLW can be significantly reduced in the closed fuel cycle up to over 95% in 2100. For this volume reduction, high heat generating fission products should be separated from transuranic waste in pyroprocessing and stored in decay storages for a few hundred years. Mining and milling waste in the closed fuel cycle decreases by about 31%. In contrast, the closed fuel cycle generates 3.0%–4.5% more LILW than the open fuel cycle because fast reactors and pyroprocessing produce more LILW and conversion, enrichment, and fabrication produce less LILW. In the closed fuel cycle, operation and decommissioning wastes from reactor and pyroprocessing, respectively, contribute to 74% and 8% of LILW excluding mining and milling waste.     

中低放废物近地表处置库源项释放模式及模拟计算结果

为了计算中低放废物近地表处置库源项释放速率，本文以某核电站处置场的概念设计为例，建立了一个简单而比较完整的源项释放模式。它包括水入渗模式、处置库混凝土顶盖的破损模式，金属桶腐蚀模式、核素从水泥固化体中的浸出释放模式及浸出核素在回填材料的中的迁移模式。     

模拟低中放废物水泥固化体在地下水中浸出性能的研究

本文采用国家标准方法 ,对硝酸钠、偏硼酸钠和阳离子交换树脂三种模拟低中放废物水泥固化体在浅地层处置环境地下水中的浸出性能进行了实验研究。实验结果表明 ,浸出实验第 42天时 ,硝酸钠、偏硼酸钠和阳离子交换树脂三种模拟废物水泥固化体中 90 Sr的浸出率分别为 1 .5× 1 0 - 6、8.9× 1 0 - 6和 6 .5× 1 0 - 6cm/d,1 37Cs的浸出率分别为 4.5× 1 0 - 6、1 .3× 1 0 - 6和 1 .4× 1 0 - 5cm/d,均优于标准要求。按浸出结果计算了三种模拟废物固化体中 90 Sr和 1 37Cs的扩散系数 ,可作为低中放废物浅地层处置安全评价研究的源项参数     

低、中水平放射性废物水泥固化体性能检验的讨论

放射性废物固化体的性能检验是保障放射性废物安全处置的有效措施之一.对于低、中水平放射性废物水泥固化体性能要求和性能检测,有关的国家标准中有明确规定.本文根据我国放射性废物水泥固化工作的实际需要,从引用的标准、抗压强度、抗浸出性和耐γ辐照性4个方面对现行国家标准<低、中水平放射性废物固化体性能要求水泥固化体>需要修订和更新的部分内容进行初步讨论.     

Analysis of Leaching Behavior of Simulated LILW Glasses by Using the MCC-1 Test Method

Glasses developed for the treatment of low- and intermediate-level radioactive waste (LILW) from nuclear power plants were evaluated by using the Material Characterization Center-1 (MCC-1) leaching method. Tests were conducted at temperatures of 40, 70, and 90°C for three weeks in pH buffer solutions spanning the range from pH 4 to pH 11. Normalized mass losses and forward dissolution rates of major glass elements (B, Na, Al, Si, Co, Cs) were analyzed under each leaching condition. From these data, the forward rate equations depending on pH and temperature were defined using a nonlinear regression method. This equation provided an overall diagram of the leach rate with these parameters (i.e., pH and temperature). The forward dissolution rates of the glasses were found to have a V-shaped pH dependence. The glasses in the pH ranges were found to have a forward dissolution rate below 10 g/m²·d, when the temperatures were between 40 and 90°C and the leachant condition was pH 4–11. Except for the DG2 glass, the minimum forward dissolution rate (0.01–1 g/m²·d) was obtained at approximately pH 7–8. Compared with previously reported results, the developed glasses showed relatively high forward dissolution rates at the neutral region, while showing similar or lower rates compared with other glasses and ceramic waste forms at both extremes of pH.     

用于中低放废物浅地层处置安全评价的PRESDSA程序

ＰＲＥＳＤＳＡ程序是以本院野外试验场为假想处置库而开发的中低放废物浅地层处置安全评价计算机程序。该程序涉及源项释放，核素在地下水、地质介质及大气中的迁移，核素在食物链中的转移，以及剂量估算。评价方法采用目前应用较广泛的景象－后果分析方法；根据场址特征，选用了浸出和闯入两种释放景象。该程序采用了文件方式输入参数，用优化方法调整参数。根据实验现场资料，用国外同类程序与现场实验结果验证本程序的核素在地下水中迁移部分的计算结果，用计算方法验证了源项释放、食物链转移及剂量估算的结果。验证结果表明，本程序的计算结果准确、可靠