Conceptual Strategy for Mitigating the Risk of Hydrogen as an Internal Hazard in Case of Severe Accidents at Nuclear Power Plant Considering Existing Risks and Uncertainties Associated with the Use of Traditional Strategies

Hydrogen challenge mitigation stands as one of the main objectives in the management of severe accidents at Nuclear Power Plants (NPPs). Key strategies for hydrogen control include atmospheric inertization and hydrogen removal with Passive Autocatalytic Recombiners (PARs) being a commonly accepted approach. However, an examination of PAR operation specificity reveals potential inefficiencies and reliability issues in certain severe accident scenarios. Moreover, during the in-vessel stage of severe accident development, in some severe accident scenarios PARs can unexpectedly become a source of hydrogen detonation. The effectiveness of hydrogen removal systems depends on various factors, including the chosen strategies, severe accident scenarios, reactor building design, and other influencing factors. Consequently, a comprehensive hydrogen mitigation strategy must effectively incorporate a combination of strategies rather than be based on one strategy, taking into consideration the probabilistic risks and uncertainties associated with the implementation of PARs or other traditional methods. In response to these considerations, within the framework of this research it has been suggested a conceptual strategy to mitigate the hydrogen challenge during the in-vessel stage of severe accident development.

Effects of inter-culture, arabinogalactan proteins, and hydrogen peroxide on the plant regeneration of wheat immature embryos

The regeneration rate of wheat immature embryo varies among genotypes, howbeit many elite agriculture wheat varieties have low regeneration rates. Optimization of tissue culture conditions and attempts of adding signal molecules are effective ways to increase plant regeneration rate. Inter-culture is one of ways that have not been investigated in plant tissue culture. Moreover, the use of arabinogalactan proteins （AGPs） and hydrogen peroxide （H202） have been reported to increase regeneration rate in a few plant species other than wheat. The current research pioneeringly uses inter-culture of immature embryos of different wheat genotypes, and also investigates impacts of AGP and H2O2 on the induction of embryogenic calli and plant regeneration. As a result, high-frequency regeneration wheat cultivars Kenong 199 （KN 199） and Xinchun 9 （XC9）, together with low-frequency regeneration wheat line Chinese Spring （CS）, presented striking increase in the induction of embryogenic calli and plant regeneration rate of CS through inter-culture strategy, up to 52.19 and 67.98%, respectively. Adding 50 to 200 mg L-1 AGP or 0.005 to 0.01‰ H2O2 to the callus induction medium, enhanced growth of embryogenic calli and plant regeneration rate in quite a few wheat genotypes. At 50 mg L-1 AGP application level in callus induction medium plant regeneration rates of 8.49,409.06 and 283.16% were achieved for Jimai 22 （JM22）, Jingdong 18 （JD18） and Yangmai 18 （YM18）, respectively; whereas at 100 mg L-1 AGP level, CS （105.44%）, Chuannong 16 （CN16） （80.60%） and Ningchun 4 （NC4） （62.87%） acted the best. Moreover CS （79.05%）, JM22 （7.55%）, CN16 （101.87%）, YM18 （365.56%）, Yangmai 20 （YM20） （10.48%）, and CB301 （187.40%） were more responsive to 0.005 %o of H2O2, and NC4 （35.37%） obtained the highest shoot regeneration rates at 0.01%o of H2O2. Overall, these two methods, inter-culture and AGP （or H2O2） application, can be further applied to wheat transgenic research.

Improvements to hydrogen depleting and monitoring system for Chinese Pressurized Reactor 1000

We evaluate the hydrogen depletion ability of the hydrogen depletion system for Chinese Pressurized Reactor 1000(CPR1000), which has been applied in nuclear power plants with pressurized water reactors;moreover, we introduce a new device that can continuously monitor hydrogen concentration inside the CPR1000 containment building. Experimental studies show that a moveable hydrogen autocatalytic recombiner alone can sufficiently deplete hydrogen under the condition of a design-basis accident, and 33 passive autocatalytic recombiners placed in the areas of high hydrogen concentration satisfy the hydrogen depletion requirements under the condition of a beyond-design-basis accident.Meanwhile, the hydrogen concentration monitoring system is designed and installed based on the approach of detecting the temperature increase caused by the catalytic reaction of hydrogen. In conclusion, the hydrogen depletion capacity of the CPR1000 meets the requirements, and the system's safety can be enhanced by the improved hydrogen concentration monitoring system.

Plant water use strategies in the Shapotou artificial sand-fixed vegetation of the southeastern margin of the Tengger Desert, northwestern China

Stable oxygen and hydrogen isotopic compositions(δ^(18)O and δD) of plant xylem water and its potential water sources can provide new information for studying water sources, competitive interactions and water use patterns of plants. The contributions of different water sources to three plants, Hedysarum scoparium(HS), Caragana Korshinskii(CK) and Artemisia ordosica(AO), were investigated in the artificial sand-fixed vegetation of Shapotou, the southeastern margin of the Tengger Desert of northwestern China, based on meteorological data and δ^(18)O and δD values of precipitation, groundwater, soil water and xylem water of HS, CK and AO. Our results indicated that soil water infiltration through precipitation was the main water source of the artificial sand-fixed vegetation. Obvious differences in soil water content and in δ^(18)O of soil water and xylem water were found among different seasons. No relationship was found between the δ^(18)O in plant xylem water and in soil water in January. The same water use patterns were found in CK, HS and AO in May, suggesting they have the same water sources. The different water sources of CK, HS and AO in August indicate that water competition occurred. In addition, the main water sources of CK, HS and AO in August mainly come from shallow soil water, while they use relatively deep soil water in May. This phenomenon is related to the differences of soil water content throughout soil profile, precipitation, transpiration and water competition under different growth periods. The water use patterns of CK, HS and AO respond to soil water content throughout the soil profile and their competition balance for water uptake during different growth season. The results indicate that these sandfixed plants have developed into a relatively stable stage and they are able to regulate their water use behavior as a response to the environmental conditions, which reinforces the effectiveness of plantation of native shrubs without irrigation in degraded areas.

Stable isotope techniques in plant water sources:a review

The stable hydrogen and oxygen isotopes widely exist in various kinds of natural water.Plants have to cope with various water sources:rainwater,soil water,groundwater,sea water,and mixtures.These are usually characterized by different isotopic signatures (18O/16O and D/H ratios).Because there are relative abundance variations in water,and plant roots do not discriminate against specific water isotopes during water uptake,hydrogen and oxygen stable isotope ratios of water within plants provide new information on water sources,interactions between plant species and water use patterns under natural conditions.At present,the measurement of δD,δ18O composition of various potential water sources and stem water has become significant means to identify plant water sources.Based on previous studies,this review highlights recent advances such as theory basis,methodology,as well as different spatial and temporal scales,and existed questions and prospects.Stable isotope techniques for estimating plant water sources have provided valuable tools for conducting basic and applied research.Future studies emphasize the modification of preparing methods,isotope technique combined with other measurements,and aerial organs of plant water source should be en-couraged.

含碳捕集电厂与氢能多元利用的综合能源系统低碳经济调度

随着中国“碳达峰·碳中和”战略的不断推进,综合能源系统的绿色低碳转型迫在眉睫。针对传统碳捕集电厂灵活性较差、风电并网难以消纳等问题,提出一种含碳捕集电厂与氢能多元利用的综合能源系统低碳经济调度模型。首先,引入储液罐对传统碳捕集电厂进行改造,提高电厂应对风电波动的运行灵活性;其次,构建含两段式电转气、氢燃料电池、储氢罐和掺氢热电联产在内的氢能多元利用结构,以充分挖掘氢能利用与碳捕集电厂的协同运行潜力。在此基础上,引入阶梯碳交易机制,建立以碳交易、碳封存、燃煤及购气成本之和最小为优化目标的低碳经济调度模型。算例结果表明,文中模型能够有效提高系统的风电消纳水平和能源利用效率,具有显著的低碳经济效益。此外,碳交易基准价格的合理设定能够引导系统提高碳捕集水平。

制氢厂房氢泄漏激光检测光路布置优化研究

氢气扩散能力强、燃烧速度快、可燃范围广的特点使其泄漏易发生爆炸事故。对比基于可调谐半导体激光吸收光谱技术的激光传感器布置方式,以降低对氢泄漏的检测时间,获得最佳光路布置间距和角度。利用数值模拟研究了氢气在制氢厂房内的泄漏逸散规律,通过光学仿真确定了激光传感器的最短布置距离,分析了相邻光路间距及光路投影角度两种因素对氢泄漏检测的影响,得到了检测时间短、经济成本相对较低的布置方式。结果表明:相邻光路间距为0.4 m、光路与地面夹角为45°时,检测氢气泄漏时间优于其他方式并且所需激光传感器数量最少。

Hydrogen Smart-Grids: Smart Metering of Electricity from Hydrogen Fuel Cells

In the last decade, increasing applications of information technology (IT) within power industry has become a significant reality. As distributed power networks are gaining importance and renewables are getting a bigger ratio within energy production, Smart Grid applications have become essential, especially due to the intermittent nature of renewable energy resources. Smart Grid is a sustainable energy system that measures, checks, and controls the generation, transmission, and consumption of electrical energy in grids on all voltage levels. Smart Grid experts are driving forward the development of effective communication and information technologies for the build-up of intelligent power supply networks. Examples of these are control systems for the realization of virtual power plants, intelligent consumer data acquisition systems, and smart distribution management systems. Fuel cell-based hydrogen electricity, in comparison to other renewable energy sources, is more stable and predictable. Yet hydrogen power and smart-grids have many application points, mainly as means of energy storage. This study claims that hydrogen energy and smart-grids could also engage through an appliance of IT managed metering of hydrogen power production. Smart metering and management of hydrogen fuel cells would enable advanced planning of short-to-mid-term power productions and thus foster use of hydrogen power within distributed networks, as local community or industrial applications.

Catalytic Cracking Characteristics of Plant Oil for Producing Light Olefins and Light Aromatics

Catalyst containing shape selective zeolite is used to investigate the catalytic cracking characteristics of palm oil and three types of hydrocarbon VGOs on a fixed fluidized bed(FFB) unit. The advantage of producing light olefins and light aromatics by catalytic cracking of plant oil is discussed. Results indicate that the hydrocarbyl group of the plant oil molecule is quite readily crackable; the C_6—C_8 aromatics yield is well above and the light olefins yield is about the same with the hydrocarbon feeds, while the yields of low value products are lower; the hydrocarbyl group of the plant oil molecule has strong tendency of aromatization, and can enter the zeolite pores to selectively form C_6—C_8 aromatics; during catalytic cracking of plant oil and fatty acids, a portion of the oxygen is removed in the form of water through hydrogen transfer reaction, while olefins are prevented from being saturated, which can ensure proper yields of both low-carbon olefins and light aromatics.

基于动态掺氢策略的综合能源系统低碳经济调度

针对现有综合能源系统中传统碳捕集电厂灵活性较差,电负荷系数、管道长度和管道运维成本等因素对计及气网掺氢的综合能源系统调度的影响尚未明确等问题,提出了一种基于动态掺氢策略的综合能源系统低碳经济调度模型。首先,建立综合灵活碳捕集电厂模型,对二氧化碳的吸收与再生环节进行解耦;其次,建立基于动态掺氢的管道运维成本模型,实现掺氢比的动态调整,提高系统调度的灵活性;然后,引入阶梯式碳交易机制,构建考虑气网掺氢管道运维成本的综合能源系统低碳经济调度模型,利用McCormick松弛方法将非线性问题转化为线性问题,并进行求解。最后,算例仿真结果表明:气网各节点处管道运维成本系数与气体体积、输送距离等因素相关,应综合考虑上述因素对气体定价;在综合能源系统调度中综合考虑电负荷系数、气网管道长度等因素合理选择气网掺氢比上限、制定动态掺氢策略,系统的经济效益与环境效益分别提高了44.1%、47.8%。

计及跨领域氢需求的电源低碳规划

大规模多领域的氢能应用会对电力负荷的规模、结构及分布等产生影响,进而对电源规划带来新的挑战。为此,文中提出一种考虑跨领域氢负荷的电源低碳规划模型。首先,计及工业、交通和供热领域的氢负荷,构建包含常规火电机组、碳捕集机组、新能源机组以及氢能系统的电-氢系统结构,并基于系统动力学理论对多领域的氢需求进行预测;其次,引入阶梯碳交易机制,在满足系统常规约束和氢能设备约束的前提下,考虑电、氢负荷需求,建立以投资、运行、碳交易以及弃电成本之和最小为优化目标的电源低碳规划模型;最后,以中国西北某地区的实际数据为例进行算例分析。结果表明,引入氢负荷和碳捕集电厂后的电源低碳规划模型能够优化电源结构、提高能源利用效率、降低系统碳排放量。

循环氢压缩机K701A入口管线腐蚀状况与分析

循环氢压缩机作为加氢装置中的关键设备,其运行的安全可靠性对保障整个装置的安全生产和经济效益有着重要意义。近日,某石化公司煤油加氢装置循环氢压缩机K701A入口管线的局部处(焊缝)发生了开裂泄漏。通过对母材和焊接处的材质、金相、电镜分析,研究了管线的腐蚀原因,结果表明:管线焊缝处的泄漏是由管线振动(交变载荷)、局部应力集中(焊缝)和管线内介质腐蚀等因素共同作用,导致管路发生腐蚀疲劳开裂。

多组合虚拟电厂中氢储能低碳经济配置与优化

提出蓄电池-氢混合储能虚拟电厂优化运行方案,首先分析各运行单元的特性并建立协同运行优化模型,然后在虚拟电厂应用蓄电池的基础上,增加由电解槽、储氢罐和燃料电池组成的氢能系统,以实现蓄电池与氢能系统混合储能。考虑电价型需求响应和阶梯型碳交易理论,较分析5种不同方案的虚拟电厂的优化运行成本及收益,实例证明蓄电池-氢混合储能的风光虚拟电厂方案具有更好的经济性和低碳性。

考虑P2G及碳捕集的热电联产虚拟电厂低碳优化调度

在碳达峰碳中和的政策方针背景下,北方地区的冬季由于需要供热,使得热电联产机组(combined heat and power,CHP)强迫出力,限制了新能源的消纳与碳减排的能力。利用碳捕集与封存(carbon capture and storage,CCS)技术将热电联产机组产生的CO_(2)捕捉并封存,将新能源发电通过电转气(power to gas,P2G)产生氢能并与捕集到的CO_(2)反应生成CH_(4),热电联产的燃气轮机使用合成的CH_(4)并掺入一定比例的H_(2)进行燃烧,循环使用CO_(2),减少碳排放并增加收益,进一步提高虚拟电厂参与电力市场的经济性与低碳性,促进新能源消纳,并保障北方冬季的供热量。建立了考虑P2G及碳捕集的热电联产虚拟电厂的数学模型,并通过MATLAB调用CPLEX求解器进行求解,仿真结果验证了所建模型的有效性。

基于低碳需求响应的含煤制氢与碳捕集电厂的综合能源系统优化调度

为了提高综合能源系统的低碳性与经济性,提出了煤制氢与碳捕集电厂联合运行模式下考虑低碳需求响应机制的综合能源系统优化调度。对煤制氢与富氧燃烧类型碳捕集电厂进行建模,并引入储碳罐、电转气装置以提高捕碳灵活性,降低制氧、制氢成本;将低碳需求响应机制引入综合能源系统调度模型中,并分析其减排能力;以运行成本最小为目标函数建立了综合能源系统的低碳经济调度模型。通过算例对所提策略进行验证,结果表明该策略能够提高风电消纳水平,降低整体系统的碳排放量,提升系统经济性。

1.5 t/d氢液化装置的研制与运行

国内首套自主研发、设计、集成并运行的1.5 t/d氢液化装置,采用了逆布雷顿制冷循环技术,标志着我国在民用氢液化技术领域的重要突破。介绍了该装置的系统组成、工艺流程及性能指标,并对其实际运行和性能测试结果进行了数据分析。通过远程监控获得了关于氢液化装置的关键性能数据,包括液化率、仲氢含量、液氮消耗量、压缩机电耗以及比能耗等。在满负荷工况下,该装置的液化率达到了1.59 t/d,比功耗为15.1 kW·h/kg,产品液氢中的仲氢含量高达98.5%,这些实测数据均优于设计指标。这套装置的研制成功,对于大型氢液化器的自主研发、集成和运行具有重要的理论和工程价值。

氢液化装置防固氧累积及安全消除固氧的流程优化

氢液化过程中氧含量超标可能导致固氧累积并导致氢氧爆炸风险。分析了由此引发的爆炸事故,并阐述了预防固氧累积的重要性。综述了近年来防止固氧累积的研究成果,包括使用超纯氢作为原料气、增加固氧洗涤器、将固氧累积调整为固空累积等,这些方法在一定程度上增加了成本或能耗。提出了一种新的解决方案,通过安装两道节流阀来防止固氧累积并安全地消除累积的固氧。通过流程模拟计算,证明了这种优化流程更易获得过冷液氢。该优化流程方案在实际应用中不会增加额外设备和能耗,具有广泛的适用性。

湛江湖光岩玛珥湖沿岸植物正构烷烃分布特征及其H同位素组成

从湛江湖光岩玛珥湖沿岸随机采集主要的草本和木本植物,分析其叶蜡正构烷烃分布特征及单体H同位素(δ^(2)H)。结果表明,湖光岩玛珥湖沿岸植物叶蜡正构烷烃主要由长链烷烃(n-C29~n-C31)组成,具有明显的奇偶优势;平均碳链长度(ACL值)与碳优势指数(CPI值)呈负相关关系;不同种类植物之间的正构烷烃δ^(2)H值差异明显,木本植物正构烷烃的δ^(2)H值(-247‰~-107‰)比草本植物(-222‰~-94‰)低,可能与它们的内在特性和所利用的土壤水深度有关。通过对比不同生境下低、中、高纬度地区湖泊沿岸植物叶蜡正构烷烃δ^(2)H值发现,低纬度热带、亚热带地区的植物叶蜡正构烷烃具有更长的链长和更高的δ^(2)H值,但植物与降水之间的δ^(2)H分馏值随纬度变化相对恒定(约-120‰),说明湖泊生境沉积叶蜡正构烷烃单体δ^(2)H值是具有较大潜力的古水文代用指标。

滨海火电厂循环水管道硫化氢气体的产生、危害及预防措施

滨海火电厂循环水管道中硫化氢等有毒有害气体的积累不仅会影响冷却系统的正常运行,还会对周边环境及现场作业人员的健康造成严重危害,是困扰火电厂安全运行的重大难题.因此,研究火电厂循环水管道中硫化氢的产生机制并针对性提出防控措施,是火电厂亟需解决的科学问题.基于此,本文从滨海火电厂循环水管道中如何产生硫化氢及防治的科学问题出发,介绍了硫化氢对环境、设备和人员的严重危害,综述了不同自然环境中硫化氢产生的机制,指出了微生物介导硫酸盐还原作用是循环水管道中硫化氢产生的关键,并根据国内外研究进展对硫化氢的防治策略进行了展望.本文对于科学防控火电厂循环水管道产生硫化氢等有毒有害气体的风险具有重要的指导意义.

煤制氢装置黑水沉降系统在线交出及操作优化

煤制氢气化装置黑水沉降系统发生故障后,出现了系统灰水水质变差的问题,影响装置平稳运行。为此,对沉降系统进行在线切换和交出。简述了某煤制氢气化装置系统水循环流程,介绍了黑水沉降系统的流程优化、黑水切换操作的优化和沉降槽排空操作的优化,针对操作中出现的真空闪蒸罐底部阀门卡涩、气化灰水浊度升高和激冷水过滤器压差升高的问题,采取了相应的措施,确保了气化炉的长周期稳定运行。