The Beishan underground research laboratory for geological disposal of high-level radioactive waste in China:Planning, site selection,site characterization and in situ tests

With the rapid development of nuclear power in China, the disposal of high-level radioactive waste（HLW） has become an important issue for nuclear safety and environmental protection. Deep geological disposal is internationally accepted as a feasible and safe way to dispose of HLW, and underground research laboratories（URLs） play an important and multi-faceted role in the development of HLW repositories. This paper introduces the overall planning and the latest progress for China＇s URL. On the basis of the proposed strategy to build an area-specific URL in combination with a comprehensive evaluation of the site selection results obtained during the last 33 years, the Xinchang site in the Beishan area,located in Gansu Province of northwestern China, has been selected as the final site for China＇s first URL built in granite. In the process of characterizing the Xinchang URL site, a series of investigations,including borehole drilling,geological mapping, geophysical surveying,hydraulic testing and in situ stress measurements, has been conducted. The investigation results indicate that the geological,hydrogeological, engineering geological and geochemical conditions of the Xinchang site are very suitable for URL construction. Meanwhile, to validate and develop construction technologies for the Beishan URL, the Beishan exploration tunnel（BET）, which is a 50-m-deep facility in the Jiujing sub-area, has been constructed and several in situ tests, such as drill-and-blast tests, characterization of the excavation damaged zone（EDZ）, and long-term deformation monitoring of surrounding rocks, have been performed in the BET. The methodologies and technologies established in the BET will serve for URL construction.According to the achievements of the characterization of the URL site, a preliminary design of the URL with a maximum depth of 560 m is proposed and necessary in situ tests in the URL are planned.

Sediment Oxygen Demand of a Leachate Pond at an Offshore Municipal Solid Waste Disposal Site 2 Years after the Site Was Closed

Various water quality parameters of a leachate pond at an offshore municipal solid waste disposal site were monitored. The pH, dissolved oxygen (DO), and water temperature at the bottom of the leachate pond were measured during Sep. (the 1st period) and Nov.-Dec. (the 2nd period) of 2011. The results suggested that the stratification of water temperature in the pond had gradually broken down due to convection occurring between the end of the 1st period and the 2nd period. The pH was almost constant at 10 - 11 during the 1st period and was approximately 11.5 during the 2nd period. The DO was almost zero during both periods. An anaerobic batch experiment with sampled sediment was undertaken to elucidate the mechanism of material leaching from the sediment. DO decreased under all experimental conditions. With respect to oxidation reduction potential (ORP) and total sulfide in addition to DO, the condition most closely mimicking that of the site became the most anaerobic. The average sediment oxygen demand, SODave, was calculated using a brief numerical model based on batch experiment data. The SODave was 1114.7 mg/m2/d, indicating that at least 434 g/d of oxygen must be supplied to the leachate pond to maintain the DO.

An Appraisal of Spatial Distribution of Solid Waste Disposal Sites in Kano Metropolis, Nigeria

This paper describes a research project that has been conducted as part of the Kano Municipal waste management strategy. The aim is to quantify and to identify the existing locations of waste disposal sites by mapping their spatial distribution within the metropolitan Kano. QUICKBIRD satellite imageries;locations of existing waste disposal sites collected using Global Positioning System (GPS);and topographical map (1:5000 scale) of Kano metropolis were used to generate data for the study. The data were prepared and analysed using ArcMap 10.2.1 and Erdas Imagine 11 software to produce the spatial distribution maps for solid waste disposal sites within the metropolis. The result shows that out of the 300 existing waste disposal sites assessed, the city has fairly well-distributed waste disposal sites. Conversely, the disposal sites are more clustered in the centre of the metropolis than the outskirts. However, about 80 percent of the sites are either located very close to roads, settlements or water bodies. Also, while about 92 percent of the existing waste disposal locations are open space, only about 7 percent are containers (closed dumping sites). Correspondingly, about 89 percent are authorised dumping sites and only about 11 percent are unauthorised illegal. The study recommends that policymakers should intervene and relocate the existing unauthorized dump sites to more suitable areas.

Spatial Identification of Potential Dump Disposal Sites for Effective Waste Management in the Sunyani Municipality, Ghana

One daunting task faced by waste managers is to appropriately identify safe sites for waste disposal and this study combined expert knowledge, field observations and GIS-based modelbuilder to model and identify suitable dumpsites. Overview of the study area confirmed the random siting of dumpsites that poses threat to environmental safety. Land use and land cover classification produced an overall accuracy of 81.97% with kappa coefficient = 0.78, which was employed in the suitability search criteria. Other key derived parameters vital for safe dumpsite locations were distances to catchment > 100 m, distances to water bodies > 100 m, soil characteristics—clayey, topology (slope of 2 and 4) and geology—Granitoids. The weightings (%) obtained for the key parameters were: water = 32, connection to catchment area = 28, topology = 23, soil = 10 and geology = 7. The exclusion criteria and suitability analysis, based on assigned suitable values from the key weighted parameters in the modelbuilder, produced a map of potential waste disposal sites rating them as most suitable, suitable and less suitable for the Sunyani Municipality. The model for the site identification could be used as a guideline to provide first and quick impression on potential waste disposal sites for stakeholders in waste management. The suitable sites give an indicator for sites with the least possible environmental impact. The study however recommends that for specific locations, further in-depth research be done to suit site-specific conditions in order to improve accuracy.

Heavy Metals in Dust Deposition in the Vicinity of Coal Ash Disposal Site Divkovici Ⅱ

DD （Dust deposition） was monitored over a 6-month period （April to September, 2011） at four sites located in villages near CADDⅡ（coal ash disposal site Divkovici Ⅱ）, one inside recultivated CADDⅠ （coal ash disposal site Divkovici Ⅰ） and at one in the middle of forest barrier as control site. The main aim of this paper is to perform monitoring of air dust pollution in the area by measuring of dust deposition, different metals associated with it, and probable adverse effects on human health. Concentrations of metals were measured by using Perkin-Elmer model Inductively Coupled Plasma and statistically evaluated with SPSS 17.0 statistical program. There was a correlation between some metals （Mn, Mo and Pb） and DD distribution. The daily limit values for concentration of DD proposed by national ＂Regulations on air quality＂ （200 mg/m^2d average annual value and 350 mg/m^2d high value） exceed at three measuring sites. The average maximum content of DD was 684.8 mg/m^2d downwind of CADDII, and the average minimum was 46.8 mg/m^2d at measuring site F. Concentrations of pollutants hazardous to the environment as Ni, Cr, Cu, Mo, Mn and Pb vary from one site to another.

High-level radioactive waste disposal in China: update 2010

For geological disposal of high-level radioactive waste （HLW）, the Chinese policy is that the spent nuclear fuel （SNF） should be reprocessed first, followed by vitrification and final disposal. The preliminary repository concept is a shaft-tunnel model, located in saturated zones in granite, while the final waste form for disposal is vitrified high-level radioactive waste. In 2006, the government published a long-term research and development （R＆D） plan for geological disposal of high-level radioactive waste. The program consists of three steps： （1） laboratory studies and site selection for a HLW repository （2006-2020）; （2） underground in-situ tests （2021-2040）; and （3） repository construction （2041-2050） followed by operation. With the support of China Atomic Energy Authority, comprehensive studies are underway and some progresses are made. The site characterization, including deep borehole drilling, has been performed at the most potential Beishan site in Gansu Province, Northwestern China. The data from geological and hydrogeological investigations, in-situ stress and permeability measurements of rock mass are presented in this paper. Engineered barrier studies are concentrated on the Gaomiaozi bentonite. A mock-up facility, which is used to study the thermo-hydro-mechano-chemical （THMC） properties of the bentonite, is under construction. Several projects on mechanical properties of Beishan granite are also underway. The key scientific challenges faced with HLW disposal are also discussed.

High Level Radioactive Waste Disposal in China

The Chinese government has decided that the installed capacity of nuclear power plants(NPP)will reach 40 GW by the year of 2020,while other 18 GW under construction,and the electricity produced by NPPs will make up 4%of the whole installed capacity. In such case,the spent fuel generated from those NPPs will reach 82630 tons by 2050.The Chinese policy is that,the spent fuel from light water reactors will be reprocessed first,followed by verification and

Medium-Deep or Very Deep Disposal of Highly Radioactive Waste？

Commonly proposed concepts, like KBS-3V, for disposal of highly radioactive waste imply construction at medium depth （400-600 m） in granitic rock, which is excellent for constructing a stable repository. VDH （very deep boreholes） represent an altemative concept with the advantage that the rock is much less permeable and that the very salt, heavy groundwater is stagnant. Both require engineered barriers in the form of canisters and waste-embedding clay but for somewhat different purposes. Canisters are the most important waste-isolating barriers for KBS-3V but are less important for VDH. The waste-embedding clay is needed for preserving the KBS-3V canisters by being tight and ductile, but plays a minor role for the VDH. The backfilled deposition tunnels in a KBS-3V repository provide very limited hindrance of radionuclides to move to the biosphere while the clay seals of VDH effectively prevent possibly released radionuclides to reach up to the biosphere. Comparison of the KBS-3V and VDH concepts indicates that the last mentioned one has several advantages but that certain issues remain to be worked on for becoming a number one candidate.

Reduced Disposal Area Performance Utilizing Secondary-Treated Effluent in Profile-Limiting Soils

Onsite wastewater systems dispose of primary treated effluent by utilizing the soil for final recycling and renovation of wastewater into the environment. Soil and site limitations have become a challenge to design a wastewater system and dispose of onsite wastewater using a conventional pipe and gravel design. Using secondary-treated effluent from an advanced treatment unit applied to a reduced disposal area offers an additional alternative when developing an onsite wastewater system. The objective of this study was to determine the feasibility of hydraulically loading limiting soils with secondary-treated effluent in a reduced disposal area. A reduced disposal area was constructed at six existing residences within the same subdivision that had shallow redoximorphic features that precluded using a conventional pipe and gravel wastewater design. Each residence had an existing advanced treatment unit with a surface discharge of secondary-treated effluent. Flows were diverted from the surface discharge to the reduced disposal area. Wastewater flows were recorded at regular intervals, along with ponding depths in the disposal area and fluctuations in the seasonal water table over a 12-month period (March 2017 to March 2018). The disposal areas were hydraulically loaded at 2 to 3.8 times the rate recommended for secondary-treated effluent. Wastewater effluent was sampled throughout the study and resulted in a mean of -1 total suspended solids, -1 biochemical oxygen demand, and >6.3 mg·L-1 dissolved oxygen, all of which met or exceeded the minimum water quality criteria for surface discharges of secondary-treated effluent. Three of the six sites showed ponding depths between 0 and 4 cm in the trenches during the study period. The remaining three sites showed ponding between 0 and 35 cm in the trenches during the study period. Based on the results of this study, a reduced disposal area utilizing secondary-treated effluent appears to be a feasible option to surface discharging.

Assessment of plastic degradation by indigenous bacteria from waste disposal sites

The present study focuses on the isolation of bacterial pathogens from waste disposal sites,and examination of their efficiencies for degrading various plastics.Seven bacterial isolates such as E.coli,Corynebacterium spp.,Micrococcus spp.,Azotobacter spp.,Pseudomonas spp.,Staphylococcus spp.,and Bacillus spp.were identified.Bacillus spp.exhibited the highest percentage reduction in black plastic weight(47.46%),while Corynebacterium spp.,and E.coli achieved a maximum reduction of 45.76 and 46.42%for pink plastic respectively.Pseudomonas spp.and Micrococcus spp.demonstrated notable reductions of 46.43%and 56.60%in white and Canteen Stores Department(CSD)biodegradable plastics,respectively.Optical density(OD)measurements revealed that bacterial isolates achieved maximum OD values with CSD plastics,emphasizing their proficiency in plastic degradation.Fourier Transform Infrared Spectroscopy(FTIR)confirmed the degradation process,with a decrease in the peak value from 2916 to 2914 cm^(-1) for pink plastic,signifying alkane,and alkene presence.Three new peaks at 1398,1371,and 1361 cm^(-1) in the FTIR spectrum of CSD plastic indicated presence of alcohol.Scanning Electron Microscopic(SEM)micrographs illustrated bacterial colonization,cracks,and spots on plastic surfaces,while Xray Diffraction(XRD)spectra showed peaks at 4.083,3.705,3.020,and 1.909,suggesting plastic degradation.In conclusion,soil of waste disposal site harbored diverse microbial species,and have highlighted their effectiveness in mitigating environmental pollution by degrading hazardous plastic waste.

我国高放废物地质处置新突破

2019年5月6日,国家原子能机构批复了我国高放废物地质处置地下实验室建设工程立项建议书。2021年6月17日,地下实验室工程正式开工建设,标志着我国高放废物地质处置进入一个新的阶段——地下实验室阶段,实现了新的突破。本文介绍近五年(2019-2024)来我国高放废物地质处置在法律法规、技术标准、场址评价、缓冲材料、工程技术、岩石力学、放射性核素迁移和安全评价等方面取得的新进展,重点介绍北山地下实验室工程建设及研究开发的新进展。

弃土场原位与弃土斜坡水分运动特征对比分析

降雨入渗会改变斜坡原有的平衡状态,为探究弃土场原位与弃土斜坡降雨入渗过程的水分运动特征。以某弃土场为研究对象重复开展染色示踪试验,对比分析原位与弃土斜坡垂直方向上土壤剖面的染色面积比和渗流前后水分运动特征的差异。结果表明(1)原位斜坡水分入渗以基质流为主,少量优先流动由生物通道引发;0~50 cm深度水分垂直均匀入渗程度高,随深度增大,表现出沿容重小一侧非均匀流动;50 cm深度以下,平均染色面积比与深度呈负相关;(2)无植被发育弃土斜坡无优先流动,沿斜坡土体表层水平扩散流动程度高,平均染色面积比在20 cm深度以下保持为0,无染色特征;植被发育弃土斜坡水分沿植物根茎优先入渗,垂直入渗较活跃;(3)染色面积比及湿润带特征能很好的捕捉斜坡水分渗流的非均匀信息;同时,根系会改变土体的孔隙发育程度,形成内部交织的网状结构,降低土壤容重,增加水分入渗,有利于增强表层土壤含水率,降低水分深层渗流,增强斜坡稳定性;加强弃土场植被生态恢复有利于增加斜坡的固土保水能力及稳定性。

构筑AuNRs/MoS_(2)/Silica gel薄层色谱板结合SERS技术对复杂水体中苯并芘的点阵列式检测

苯并芘(Bap)是环境中典型的有机污染物,通过生物循环途径在人体内富集,会对机体造成慢性损伤。为了快速痕量分析复杂环境中的苯并芘,本工作将薄层色谱板(TLC)与表面增强拉曼散射(SERS)技术相结合,构建了一种新型AuNRs/MoS_(2)/Silica gel薄层色谱板,并将其应用于Bap的痕量检测。该方法具有灵敏度高、操作简便等优点,可以完成对毒物的现场快速分析检测,有效克服了目前苯并芘检测方法中检出限高、仪器设备昂贵等问题,具有一定的实际意义。

山区铁路隧道洞渣处置及对策研究

我国山区铁路隧道工程占比高、洞渣数量多。科学处置隧道洞渣是推进铁路高质量发展的具体举措。从隧道洞渣综合利用、隧道弃渣场选址、隧道弃渣场生态修复研究和隧道弃渣场安全研究4个维度系统梳理总结既有山区铁路隧道洞渣处置实践成果及存在问题,并提出对策建议,旨在为后续洞渣科学处置、规章建制等提供参考。

地震和降雨工况下露天边坡排土场稳定性分析

为研究降雨和地震对露天矿边坡变形的影响,本文基于刚体极限平衡法,利用GeoStudio软件进行不同工况条件下的稳定性分析。结果表明:在自重+地下水、自重+降雨、自重+地震三种工况下对排土场边坡进行稳定性计算,排土场最危险滑面是圆弧形,计算结果均满足规范要求,边坡整体稳定性较好。研究成果可为该类边坡的灾害防控提供理论支撑。

基于快速通道公路的施工现场处置关键技术分析

公路快速路在施工过程中,面临的各方面限制均较大。尤其是在工程多、交叉作业多的路段,会在施工过程中产生需要临时处置的情况。但怎么合理利用现场和周边有利的条件去避免增高过大的造价,从而获得较好的施工获益,是施工现场处理所希望达到的目标。本文以南三岛某快速的东西向通道为例,由于该施工路线长,交通运输条件较差,对施工进度完成较多需要现场处理的路段,通过结合施工所处的环境,提出较为合理经济性的处理方案。最终结果证明,在施工完成后,该路段运营良好。拟为相关类似工程提供参考。

某排土场在不同工况下边坡稳定性研究

为研究某排土场边坡稳定性,结合排土场所在位置工程地质概况,利用GeoStudio软件,采用三种不同的极限平衡法对排土场最不利滑动面进行分析,计算其在自然、强降雨及地震工况的最小边坡安全系数,为排土场边坡稳定性提供数据支撑。

环北部湾广西水资源配置工程水土保持方案弃渣场设计

介绍了生产建设项目水土保持方案管理办法出台的背景。在梳理相关水土保持方案编制要求的基础上,分析环北部湾广西水资源配置工程水土保持方案弃渣场设计的具体内容,提出减少工程弃渣及综合利用、弃渣场选址与防护等方案。

山区高速公路弃渣场选址及设计——以渝赤叙高速(重庆段)为例

山区高速公路建设会产生大量弃渣,受地形限制,弃渣场选址及设计均存在较大困难,如果选址过于随意,后续容易产生极大风险隐患,不利于生态环境恢复。文中以渝赤叙高速公路弃渣场为例,对山区高速公路弃渣场选址及设计进行分析,可为类似工程项目提供借鉴。

浅析排渣场扬尘控制技术研究

排渣场的扬尘是排渣场环境污染的主要形式之一,该污染源会给矿区及周边生态环境造成非常大的影响,因此,有必要对排渣场的扬尘污染环境问题进行研究,降低或减少扬尘,消除扬尘危害,改善矿山生态环境,建设环境友好型矿山。本文对排渣场扬尘产生的影响因素及机理进行分析,列举了相应的扬尘控制技术,从而为能更好地改善排渣场扬尘污染问题提供了理论依据和技术支持。