Engineering analysis of pumping cold deep nutrient-rich seawater for mariculture and nuclear power plant cooling

The engineering feasibility of pumping deep seawater has been achieved by using a simplified mathematical model. It was proved that the pumping power required to draw seawater from deep sea is always less than 100 kW (134 h.p.) for pipe diameters below 15 cm and mass flowrate lower than 100 tons/hr, which is suitable for mariculture farmings, and the replacement of warm surface seawater by cold deep seawater as nuclear power plant coolant is technically feasible for pipes with diameters larger than 150 cm and intake levels below 600 m. This model can be further extended to study the performance of the Ocean Thermal Energy Conversion (OTEC) system onshore.Continuation of this study should be the design of deep seawater prototype pumping system, the construction of pilot plants of cooling applications and mariculture experiments, and the feasibility analysis of the Ocean Thermal Energy Conversion power plants.     

基于Landsat-8数据的田湾核电站温排水分布研究

为研究潮汐变化对连云港田湾核电站邻近海域温排水时空分布与变化规律的影响,利用Landsat-8热红外数据,构建基于劈窗算法的温度反演模型,结合潮汐数据分析田湾核电站邻近海域的温排水分布规律。得出结论:基于Landsat-8数据的劈窗算法温度反演模型应用在田湾核电站邻近海域温排水的监测效果较好;潮汐运动直接影响田湾核电站温排水的时空分布与扩散方向,并呈现一定的规律性。本文的研究方法为核电站温排水常规性监测提供了一定的技术参考。     

江苏省洋口港风暴潮数据分析

主要对江苏如东燃气电厂厂址(如东县长沙港海堤外)所在洋口港进行了风暴潮数据分析及对厂址影响评价。通过对风暴潮影响规律和历史强风暴潮过程灾情分析,仔细研究了相关特征潮位与潮位重现期和波浪爬高计算,确定了厂址区域的警戒潮位。研究认为:现有的堤防工程能够抵御重现期为200a一遇的风暴潮过程的堤防设计标准要求。     

Geotechnical sealing material for coastal disposal facility for soils and wastes contaminated by radioactive cesium

Safe disposal of wastes produced due to the process of decontamination in and around Fukushima No. 1 nuclear power plant is an urgent requirement. The purpose of this study was to develop a sealing material which can be used as an engineered barrier for a final disposal facility for the soils and wastes contaminated by radioactive cesium. The analyses conducted based on 4-m-thick sealing layer revealed that the hydraulic conductivity of the sealing material needs to be kept below 5.0?×?10^?10?m/s to avoid the seepage of contaminants below the environmentally safe limits. Sealing material was developed using marine clay–bentonite mixture and the engineering characteristics were examined. The results of laboratory experiments showed that, with the addition of bentonite, the hydraulic conductivity equal to or less than 5.0?×?10^?10?m/s was achieved when the effective consolidation stress is equal to or more than 27?kPa. From the tests for adsorption properties for cesium, it was found that the sealing material showed the significant capacity of adsorption for cesium in seawater. It was concluded that the construction of waste disposal facility on the sandy seafloor is feasible using the sealing layer proposed in this study.     

近岸海域大型水母来源与迁移路径分析——以红沿河电厂海域为例

近岸海域水母暴发可导致滨海火/核电厂取水口堵塞,对电厂安全运行造成潜在威胁。寻找水母源地及其迁移路径是水母治理的基础。本文基于拉格朗日质点追踪方法(LTRANS)建立反向追踪模型,并结合水母生态学特性对2015年6—9月聚集在红沿河电厂海域的大型水母进行溯源,获得水母源地及迁移路径,可以为螅状体栖息地寻找和水母拦截打捞提供依据,对近岸海域水母灾害防治具有重要指导意义。溯源结果表明:(1)红沿河电厂及其邻近海域的水母可能来自多个不同源区,辽东湾西部、北部及电厂南北两侧等海域的水母均有可能迁移至电厂附近;(2)受水温和环流影响,6—9月期间到达电厂附近的水母主要源区及迁移路径不同,早期出现在电厂海域的水母很可能是局地产生的,而7—9月持续的高风险水母灾害则主要取决于渤海不同源区水母的物理聚集;(3)根据水母的主要迁移路径,建议在电厂取水口约15km的海域设置一条封闭监测断面,对水母进行实时监测;在距离取水口约30km的外侧海域设置一条调查断面,于7月初至8月中旬,每5天进行一次定点拖网调查。此外,在距离电厂取水口15—20km的西南方向上,对水母进行拦截打捞可大大降低水母入侵风险。     

Specific power optimization of closed-cycle OTEC plants

The specific power of a simple irreversible closed-cycle OTEC power plant is analyzed and optimized. The plant uses a working fluid such as ammonia to produce power. Specific power is the net output per unit total heat exchanger surface area. Net output generated by the working fluid is obtained in terms of the rate of heat added to the working fluid from the warm surface ocean water, less the rate of heat removed from the working fluid to the cold deep ocean water. A time factor is added to iimulate the heat exchanges between the OTEC plant and its surroundings. A mathematical expression is derived for the specific power output of the irreversible OTEC heat engine. It is found that there is a bound on the specific power output. This bound provides the basis for a practical engineering effort towards maximizing the per unit time and per unit total heat exchanger area production of work in power plants whose heat transfer area is constrained by economic consideration.     

海上浮式核电站温排水对海洋生态环境的影响

开发海上浮式核电站,可以有效地解决海洋工业的用能需求,符合国家能源发展战略。海上核电冷却循环系统产生的温排水会对海洋环境本体及其生态系统产生一定的负面影响,是环评工作关注的重点。论述了海上核电站温排水的特点,分析了其对受纳海域水文条件、海水水质、生态环境、生物群落组成与结构等方面产生的影响,提出了温排水的热污染控制对策。     

福清核电站邻近潮间带大型底栖生物数量分布与群落结构

于2006年2、4、7和10月在福清核电厂运行前对其邻近潮间带不同底质断面的大型底栖生物进行采样,以了解该潮间带大型底栖生物的种类及资源分布.结果表明,该核电站附近潮间带大型底栖生物总共为146种,以多毛类、软体动物和甲壳动物为主.以季节和底质为因素对取样获得物种数进行双因素方差分析显示:种类获得数的季节变化无显著差异,底质间呈边缘性显著.4季的大型底栖生物平均生物量为1 446.11 g/m2、平均栖息密度为972个/m2.大型底栖生物生物量平均值为春季＞夏季＞冬季＞秋季,栖息密度平均值为夏季＞春季＞冬季＞秋季.以季节和底质为因素的双因素方差分析显示:大型底栖生物生物量和栖息密度季节间无显著差异但底质间差异极显著.底质和季节间大型底栖动物的Shannon-Weiner指数、Margalef种类丰度、Pielou均匀度和Simpson优势度指数均无显著差异.利用Bray-Curtis相似性聚类对福清核电站邻近潮间带大型底栖生物进行分析后得出,该潮间带大型底栖生物可划分为两个群落:岩礁群落和泥沙滩群落.分析表明,底质是影响大型底栖生物分布的主要环境因子,季节对大型底栖生物分布的影响不显著.     

Dispersion and accumulation of radionuclide in sediment of Urazoko Bay-II

Further studies on the transport in sea water and accumulation in marine sediment of the radionuclides, released from a nuclear power plant, on Urazoko Bay, Fukui Prefecture were reported.The partition of radionuclides among the particle size fractions of a sediment sample indicated that the accumulation of⁶⁰Co,¹³⁷Cs and⁵⁴Mn in the sediment were dominated substantially by the sorption on the particle surface in sea water, and the patterns of their sorption were considerably similar to each other.In regard to the⁶⁰Co contamination of marine sediments in an area of about 13 km² around the nuclear power plant, 60% of the⁶⁰Co contamination were retained in Urazoko Bay, which occupies only 7% of the bottom surface of the region.It is clear that a part of⁶⁰Co accumulated in the sediment of Urazoko Bay gradually moved to the outerward.     

针对红沿河核电站冷源取水海冰堵塞风险的数值模拟预警设计初探

由于经验和技术缺失,我国冰区滨海核电站的冷源取水安全受到海冰的威胁。数值模拟预警是建立和完善核电冷源取水安全保障系的关键部分。本文以辽东湾东岸的红沿河核电站为例,介绍了 3 种主要的核电冷源安全海冰致险模式,给出了 不同致险模式的数值模拟预警流程,并对数值模拟范围的选取进行重点阐述。结果表明,满足 24 h 预警需求的海冰数值模拟范围面积在数百甚至数千平方公里以上,较大的模拟范围与高网格分辨率对运算能力提出了较高的要求,是目前该数值模拟预警需要解决的突出问题。     

Radioecological studies of activation products released from a nuclear power plant into the marine environment

The seaweeds Fucus vesiculosus, Fucus serratus, Ascophyllum nodosum and Cladophora glomerata and crustaceans of the Idothea and Gammarus families have proven to be excellent bioindicators for radioactive corrosion products released from a nuclear power plant into the marine environment. These bioindicators have been used to map the spatial and temporal distribution of the released radioactivity. The activity has been followed up to 150 km from the power plant, and the decrease in activity concentration C(z) in the bioindicators with distance z can be expressed by a power function C(z) = α. z^?1·4 where α is a constant.The variation with time of activity concentration very well reflects the amount of activity discharged from the power plant, with surprisingly good resolution in time.The bioindicators exhibit different uptake patterns of the radionuclides detected, and variations from summer to winter for the crustaceans Idothea, when compared to Fucus, has been found.     

湛江湾电厂脱硫酸性废水排放对海洋叶绿素影响研究

为了清晰理解湛江湾内某电厂脱硫酸性废水排放引起海水pH的变化分布及其对叶绿素浓度的影响,在野外调查及实验室模拟的基础上建立叶绿素浓度对pH的响应模式,并基于ECOMSED海洋模式和水质模型预测湛江湾叶绿素浓度的变化率和影响范围。实验室模拟结果表明,叶绿素浓度受pH影响较大,比较适宜叶绿素合成的pH区间为7.5~8.5,叶绿素浓度对pH的响应模式可以用二次多项式函数表达。预测结果表明,电厂脱硫酸性废水排放导致湛江湾叶绿素浓度下降超过1.0%的全潮极端影响面积为16.10 km2,而引起叶绿素浓度增加超过1.0%的全潮极端影响面积为2.18 km2,分别占湛江湾海域面积的8.47%和1.15%。     

XX核电厂附近海域生态环境及潜在致灾生物研究

为了了解XX核电厂周边海域的生态环境状况,筛选潜在威胁核电厂冷源安全的致灾生物,分析影响致灾生物时空分布的主要环境因素,本研究于2018年进行了四个季节的生态调查。结果表明,研究海域浮游植物密度秋季最高,春季优势种为东海原甲藻,其他季节优势种为中肋骨条藻等硅藻。浮游动物密度夏季最高,以桡足类为主,春、夏季优势种还包括球型侧腕水母和薮枝螅水母。底栖动物的密度和生物量在秋季最高,优势种主要为豆形短眼蟹、长吻沙蚕和丝异须虫。浮游植物、浮游动物和底栖动物群落均在夏季最为稳定,群落多样性水平和物种丰度较高,且分布较为均匀。浮游植物群落的细胞丰度与悬浮物和磷酸盐的浓度正相关性最高。浮游动物的密度受温度和盐度的影响较大。底栖动物的群落分布主要受悬浮物和无机营养盐的浓度影响。本研究共筛选出17种威胁XX核电厂冷源安全的潜在致灾生物。海地瓜、棘刺锚参、海葵和球型侧腕水母的风险等级较高,其分布主要受温度和盐度的影响。后续工作中,XX核电厂应根据潜在致灾生物与环境因子的关系加强暴发机制研究、提升监测预警能力,并优化驱赶消杀技术和干扰体系,为核电厂冷源安全提供理论和技术保障。     

一种基于滨海核电站海上γ辐射剂量率的智能化自动监测系统研究与设计

基于滨海核电站海上γ辐射剂量率的智能化自动监测系统是一种无人值守的辐射监测装备,可全天候、长时间、在线组网、连续自动测量水面和空气中的γ剂量率、获取水中γ能谱数据并进行核素识别和计算活度浓度,并实时地将监测数据通过无线通信链路和北斗短报文两种形式上传至地面数据服务中心。在非事故情况下,该系统是对核电厂监督性监测系统的重要补充和完善;在发生重大核安全事故或放射性物质泄漏的情况下,能够有效解决传统的派船巡测时方法不标准、数据不及时不连续、人员受照风险大、船只易受污染和行动代价高等问题;在恶劣的极端气象条件下,无人值守的自动监测系统能够为核电站提供实时有效的水体和空气中的γ剂量率、气象、海水温度等监测数据,有效地提升了核电站在极端气象条件下的监测能力,对滨海核电站整体的安全性和可靠性具有一定积极意义。     

Fouling assemblages on offshore wind power plants and adjacent substrata

A significant expansion of offshore wind power is expected in the near future, with thousands of turbines in coastal waters, and various aspects of how this may influence the coastal ecology including disturbance effects from noise, shadows, electromagnetic fields, and changed hydrological conditions are accordingly of concern. Further, wind power plants constitute habitats for a number of organisms, and may locally alter assemblage composition and biomass of invertebrates, algae and fish. In this study, fouling assemblages on offshore wind turbines were compared to adjacent hard substrate. Influences of the structures on the seabed were also investigated. The turbines differed significantly from adjacent boulders in terms of assemblage composition of epibiota and motile invertebrates. Species number and Shannon–Wiener diversity were, also, significantly lower on the wind power plants. It was also indicated that the turbines might have affected assemblages of invertebrates and algae on adjacent boulders. Off shore wind power plant offer atypical substrates for fouling assemblages in terms of orientation, depth range, structure, and surface texture. Some potential ecological implications of the addition of these non-natural habitats for coastal ecology are discussed.     

Effects of fluctuations in water level and growth of Lagarosiphon major on the aquatic vascular plants in Lake Rotoma, 1973–80

Fluctuations in water level and the growth of the introduced exotic Lagarosiphon major (Ridley) Moss have significantly influenced the submerged vegetation of Lake Rotoma over the period 1973–80. Low lake levels temporarily reduced the proportion of native vascular plants by removing available shallow‐water habitats through erosion, siltation, or desiccation. High lake levels have allowed native vascular plants to re‐establish from seed and rhizomes. Fluctuations in water level appear to have reduced the long‐term replacement of native species by L. major, which has none the less spread progressively around the lake. Water‐level fluctuations enhanced its rate of fragmentation, and thus its dispersal and establishment. The annual increase in the proportion of L. major has been primarily at the expense of the shallow‐water characean algae, but also partly by competitive displacement of native vascular plants. The southwest inlet of Lake Rotoma had an exceptionally high plant density, with up to 3518 g/m² dry weight of L. major (believed to be a world record for submerged plant biomass); this is attributed to local enrichment and protection from wave exposure.     

Dispersion and accumulation of radionuclides in sediment of Urazoko Bay (I)

Contents of⁹⁰Sr,¹³⁷Cs and⁶⁰Co in surface sediments were investigated in and around Urazoko Bay, Fukui Prefecture, where a nuclear power plant has been operating since 1969 and the waste effluent has been released into the sea. The main source of⁹⁰Sr and¹³⁷Cs was recognized to be radioactive fallout, whereas⁶⁰Co was considered to originate from the nuclear power plant. Using the¹³⁷Cs concentration as an indicator of sorption capacity of the sediment, the behaviour of⁶⁰Co was investigated. No seasonal variation was observed in the distribution pattern of⁶⁰Co/¹³⁷Cs ratio and the retention of the heavy initial discharge in 1969 was considered to dominate the radionuclide level in the sediment. Correlation of⁶⁰Co/¹³⁷Cs ratio in the sediment and the distance from the discharge outlet was expressed by a simple exponential function of the distance. It was suggested that the contamination is spreading out gradually to the outer region of Urazoko Bay.     

Salt marsh plants (Juncus maritimus and Scirpus maritimus) as sources of strong complexing ligands

This work aimed to evaluate, in vitro, the capability of roots of salt marsh plants to release strong Cu-complexing ligands and to ascertain whether Cu contamination would stimulate ligands' exudation or not. The sea rush Juncus maritimus and the sea-club rush Scirpus maritimus, both from the lower Douro river estuary (NW Portugal), were used. Plants were collected seasonally, four times a year in 2004, during low tide. After sampling, plant roots were washed for removal of adherent particles and immersed for 2 h in a solution that matched salinity (3) and pH (7.5) of the pore water from the same location and spiked with Cu²⁺ in the range 0–1600 nM to obtain plant exudates. In the final solutions as well as in sediment pore water total dissolved Zn and Cu, Cu-complexing ligand concentrations and the respective conditional stability constants (K_CuL^′) values were determined by voltammetry. This study demonstrated that plants are able to release, in a short period of time, relatively high amounts of strong Cu-complexing ligands (56–265 nmol g_root⁻¹), which differed among plants and sampling site but were independent of the season. Cu contamination did not stimulate exudation of Cu-complexing ligands. On the other hand, in media contaminated with Cu both plants accumulated relatively high amounts (29–83%) of the initially dissolved Cu, indicating that they have alternative internal mechanisms for Cu detoxification. Cu exchange between roots and medium (either accumulation in contaminated medium or release in the absence of Cu) was more intense for S. maritimus than for J. maritimus. It was observed that exudate solutions obtained in the absence of added Cu and sediment pore water (the densities of roots observed inside the salt marsh where comparable to those used in the in vitro experiments), displayed similarities in terms of total dissolved metals, Cu-complexing ligands concentrations, values of K_CuL^′ (12 < log K_CuL^′ < 14), as well as patterns of variation among seasons (only observed for Zn). These results are novel and point out that salt marsh plants may be the source at least partially of the strong organic ligands found in the sediment pore water in shallow marginal areas. The capability of salt marsh plants to release strong organic ligands into the environment, conjugated with their known capacity to oxidize anaerobic sediment around roots, indicate that these plants can play a role in controlling metal speciation in the water/sediment interface.     

Stochastic modelling in wave power-equipment optimization: maximum energy production versus maximum profit

The paper presents an optimization study for the mechanical and electrical equipment of an oscillating-water-column (OWC) wave power plant of fixed shoreline or nearshore type, equipped with an air turbine. The plant’s structure geometry is assumed to be given and the corresponding hydrodynamic coefficients are known as functions of wave frequency. A stochastic model is adopted for the energy conversion process from wave to air turbine, it being assumed that the system is linear. The optimization concerns the turbine size, represented by its rotor diameter D. Two alternative criteria are used: (i) maximization of the produced electrical energy, (ii) maximization of the annual profit. An example calculation is presented, based on the hydrodynamic coefficients of the OWC on the island of Pico, Azores, and on the aerodynamic performance curves of its Wells turbine. The influence of the following parameters upon optimized turbine size and rated power output is analyzed: wave climate, capital costs of mechanical and electrical equipment, operation and maintenance costs, discount rate, equipment lifetime and price of electrical energy supplied to the grid.     

Comparison of bulk and compound-specific δC analyses and determination of carbon sources to salt marsh sediments using n-alkane distributions (Maine,USA)

Sources of sedimentary organic matter to a Morse River, Maine (USA) salt marsh over the last 3390 ± 60 RCYBP (Radiocarbon Years Before Present) are determined using distribution patterns of n-alkanes, bulk carbon isotopic analysis, and compound-specific carbon isotopic analysis. Marsh foraminiferal counts suggest a ubiquitous presence of high marsh and higher-high marsh deposits (dominated by Trochammina macrescens forma macrescens, Trochammina comprimata, and Trochammina inflata), implying deposition from ∼0.2 m to 0.5 m above mean high water. Distributions of n-alkanes show a primary contribution from higher plants, confirmed by an average chain length value of 27.5 for the core sediments, and carbon preference index values all >3. Many sample depths are dominated by the C₂₅ alkane. Salicornia depressa and Ruppia maritima have similar n-alkane distributions to many of the salt marsh sediments, and we suggest that one or both of these plants is either an important source to the biomass of the marsh through time, or that another unidentified higher plant source is contributing heavily to the sediment pool. Bacterial degradation or algal inputs to the marsh sediments appear to be minor. Compound-specific carbon isotopic analyses of the C₂₇ alkane are on average 7.2‰ depleted relative to bulk values, but the two records are strongly correlated (R² = 0.89), suggesting that marsh plants dominate the bulk carbon isotopic signal. Our study underscores the importance of using caution when applying mixing models of plant species to salt marsh sediments, especially when relatively few plants are included in the model.