正常运行工况下核电厂气态流出物中~(85)Kr与~(133)Xe的关系

核电厂正常运行工况下,气态流出物中惰性气体监测结果一般均低于探测限。如按标准以探测限的1/2统计,可能会过高统计年排放量。本文通过确定气态流出物中85Kr与133Xe活度浓度的关系,当惰性气体源项中半衰期最大的85Kr低于探测限时,间接估算其活度浓度,以便能准确地对85Kr进行年排放量统计。     

我国核电厂气态流出物中惰性气体监测现状

核电厂流出物尤其是气态流出物中的放射性惰性气体监测多为低水平放射性核素,我国运行核电厂的环境监测结果均低于探测限,无法计算照射剂量.探测能力决定了放射性惰性气体排放评价的结果.本文分析了我国各运行核电厂流出物放射性惰性气体监测和排放评价的现状,比较欧盟的相关建议,研究我国核电厂流出物放射性惰性气体监测能力存在的问题,并提出了建议.     

M310改进型核电厂放射性流出物排放监测

核电厂放射性气态流出物是通过核电厂烟囱向环境排放,放射性废水通过核电厂废水排放渠向受纳水体(如大海、河流、湖泊)排放,此外还可能通过车辆或人员从核电厂带出少量污染物。为对上述排向环境的废物进行严格管理和控制,设计了核电厂放射性流出物监测设备。M310改进型核电厂对放射性物质向环境的释放管理和控制是严格的,安全的。     

~(85)Kr气体液闪测量方法研究

采用反康普顿γ谱仪对~(85)Kr样品进行活度标定作为工作参考,通过自行设计的Kr气体收集装置和液闪制样装置,建立了一种~(85)Kr气体样品的液闪测量方法。结果表明:以甲苯为溶剂、1,4-双-2-(4-甲基-5-苯基噁唑基)(POPOP)和2,5-2苯基噁唑(PPO)为溶质的闪烁液,当体积为20mL,硅胶加入质量为1.0g时,能够完全溶解0.5m~3空气中的Kr气,且样品液闪测量无需进行淬灭校正;对于~(85)Kr活度小于1Bq的样品,液闪测量相对偏差绝对值小于7%;制备的样品放置20h以内计数率稳定。该方法适用于环境大气中~(85)Kr放射性水平的测量。     

核电厂气态流出物监测样品分析中的核素衰变校正应用探讨

在放射性样品分析工作中,样品测量阶段、闲置阶段、采样阶段都涉及到核素衰变校正。根据放射性核素的衰变规律,阐明了这三种类型的衰变校正方法原理及其系数的计算。针对核电厂气态流出物中短半衰期的放射性惰性气体和碘核素的监测分析工作,研究了对监测样品分析结果进行衰变校正的必要性。基于实验测量结果,探讨了衰变校正对γ能谱分析法中核素的活度浓度探测下限的影响。介绍并分析了核电厂气态流出物监测样品分析工作中的衰变校正方案,对于短半衰期放射性惰性气体和碘核素,采用合理保守的衰变校正方案,可减少监测分析中的偏差,同时又可保证统计排放量的偏保守性。     

美国内陆核电厂液态放射性流出物排放环境辐射监测与评估

系统分析了2005—2012年美国38个内陆核电厂液态放射性流出物在受纳水体介质中的活度浓度水平,包括沉积物、地表水、饮用水和水生生物。结果表明,除个别核电厂受纳水体(地表水)中的氚活度浓度较高外,其它受纳水体介质(包括沉积物和鱼类)中来自核电厂排放的放射性物质的活度浓度一般处于正常水平。个别内陆核电厂由于受纳水体环境条件的限制,氚的活度浓度水平偏高,但均低于美国环保署(EPA)规定的饮用水中氚的指导水平。核电厂受纳水体排放放射性核素对公众造成的辐射剂量评估表明,美国内陆核电厂运行因液态放射性流出物排放对公众造成的辐射剂量很小。通过分析美国核管会(NRC)规定的监测探测下限和报告水平的要求和内陆核电厂2005—2012年间监测结果,反映了NRC认可的美国内陆核电厂受纳水体受到核电厂液态放射性流出物排放的影响很小。     

核设施环境评价软件包(NGLAR)

介绍了基于微机的核设施环境评价软件包(NGLAR)的主要内容、设计原则和特点。该软件包包括:核设施气态流出物常规和事故释放环境评价程序(NGAS和NACC)、核设施液态流出物常规和事故释放环境评价程序(NLIQ)以及核设施环境数据库(NRED)。核设施气态流出物常规和事故释放环境评价程序,用于大气弥散计算和公众剂量估算,给出核设施周围放射性核素的空气浓度、地面沉积浓度和动植物产品中的浓度,并进而估算核设施周围的集体剂量和关键居民组剂量。核设施液态流出物常规和事故释放环境评价程序适合于流出物向非潮汐河流排放情况,用于计算河水中的放射性核素的浓度和与河水有关的公众剂量。该套软件可以在IBM及其兼容386以上微机运行,具有中、英文两种版本,功能齐全,适合于核工业基层单位使用。     

秦山核电厂气态流出物气溶胶粒径分布测量

对秦山核电基地烟囱流出物的粒径分布谱进行了实验测量,结果表明:气态流出物中的气溶胶粒径大多在1 μm以下,但总粒子数浓度随机组类型不同而不同。测量结果为评估核电厂气态流出物监测系统采样的有效性提供了参考。     

核设施环境评价软件包(NGLAR)

介绍了基于微机的核设施环境评价软件包(NGLAR)的主要内容、设计原则和特点。该软件包包括:核设施气态流出物常规和事故释放环境评价程序(NGAS和NACC)、核设施液态流出物常规和事故释放环境评价程序(NLIQ)以及核设施环境数据库(NRED)。核设施气态流出物常规和事故释放环境评价程序,用于大气弥散计算和公众剂量估算,给出核设施周围放射性核素的空气浓度、地面沉积浓度和动植物产品中的浓度,并进而估算核     

燃煤发电厂气态流出物辐射环境影响研究

目前,燃煤发电厂对环境和公众产生的辐射影响引起了广泛关注。本文选择长江沿岸具有代表性的三家燃煤发电厂为研究对象,基于电厂气态流出物中主要放射性核素的年排放量,采用烟囱直接排放和沉降进入水体两种途径的评价方法,评估燃煤发电厂气态流出物对周围环境造成的辐射影响。结果表明:三家燃煤发电厂气态流出物排放造成80km范围内辐射影响很小,归一化最大个人年有效剂量分别为3.02×10~(-4)、4.32×10~(-5)、8.50×10~(-5 )Sv/GW;辐射剂量主要来自~(210)Po和~(210)Pb直接排放通过食入照射途径的贡献,远大于其进入水体及222Rn排放对剂量的贡献。由于210Pb具有相对较长的半衰期,导致其在土壤中的比活度增加;基于文中210Pb沉积浓度的分析,建议相关研究关注燃煤发电厂下风向30km范围内210Pb的长期辐射影响。本研究结果可为类似厂址的辐射影响评价提供技术支持,为内陆核电建设中公众沟通和技术研究工作提供基础数据,也为政府相关部门的决策提供参考。     

内陆AP1000核电项目低放废液排放的主要污染物及其处理技术

AP1000核电站是我国未来短期内陆核电建设的主力堆型,其低放废液的排放与管理是水资源管理部门所关心的重要内容之一。氚、除氚外核素和硼是内陆AP1000核电站低放废液排放的主要污染物,本文对这些污染物的处理技术进行了总结。     

三代核电气、液态流出物计算及在内陆厂址条件下环境影响优化

内陆核电是我国将来核电发展的一个重要选择,与滨海厂址相比内陆厂址的环境条件有着自己的特点。本文介绍了以华龙一号和AP1000为代表的三代核电气、液态流出物的计算流程和典型计算结果,阐述了流出物环境影响的分析过程,对比分析了内陆核电厂址和滨海核电厂址在大气扩散条件和受纳水体条件的差异和法规标准的不同要求,总结了现行法规和国家标准对内陆厂址气、液态流出物的特殊监管要求。在此基础上,基于合理可行尽可能低的原则,从工艺设备、排放策略、排放方案等方面提出了三代核电在内陆厂址条件下减少气、液态流出物排放总量、降低环境影响和适应缺少受纳水体厂址的方法。     

内陆核电厂液态流出物排放口设计及环境影响评价初探

对美国内陆核电厂液态流出物的扩散器工程实践进行了概括和总结,根据《核动力厂环境辐射防护规定》(GB 6249—2011)的要求,在分析我国内陆核电厂液态氚排放面临较高的排放要求的基础上,对我国内陆核电厂液态流出物的排放设计及环境影响模拟进行了归纳和总结,并提出建议。成果可为内陆核电厂的扩散器研究提供参考。     

核电厂放射性流出物监督性监测工作的一些探讨

简要概述了国内核电厂放射性流出物现行有效的法规、标准和要求,结合我省多年来对核电厂环境监测的实际经验,分析了环境保护主管部门监督性监测工作中存在的问题,并提出尽快制订放射性流出物监督性监测技术导则和流出物浓度排放标准,建设放射性流出物监测实验室、海水连续监测系统等建议,进而规范核电厂放射性流出物监督性监测工作,为政府监督和环境管理提供技术支持,保障核电厂厂址周边环境和公众安全。     

1992～1994年秦山核电厂周围环境辐射监测结果和初步分析

本文介绍１９９２～１９９４年本站对秦山核电厂周围环境辐射监测的方案（监测项目，频率和范围）方法及其结果和初步分析，监测结果表明，秦山核电厂周围环境的γ辐射水平和各种介质中的主要放射性核素浓度在本底水平波动，说明秦山核电厂自１９９１年投入运行以来，未对周围环境产生可觉察到的影响。     

Storage of Krypton-85 by Adsorption Method

Several fundamental experiments were performed on adsorption process of ⁸⁶Kr storage at the ordinary condition of temperature and pressure. A long-term test for storage was then performed with radioactive ⁸⁵Kr and the safety was confirmed by hot run of 38 days. Of many adsorbents adopted in preliminary experiments, the largest amount of adsorbed Kr was AW-500 (16.4 cc STP/g) among molecular sieves and Tsurumi HC-30E (33.2 cc STP/g) among charcoals. The amount of adsorbed Kr decreased slightly with the addition of Rb and with the irradiation of the order of 10⁵ Mrad. It was found that adsorption rate is effected larger by Xe than by air. In ⁸⁵Kr storage test of 100 Ci, the pressure in storage vessel varied in the range of about ±4%, and the ⁸⁵Kr leak rate from the vessel was the order of 10^?12cc·atm/s. It was found that there is no considerable temperature rise due to β disintegration. From these results, the adsorption process may be useful for storage of ⁸⁵Kr for long-term.     

RELAP5/MOD3.2 investigation of a VVER-1000 MCP switching on Benchmark problem

This paper provides comparisons between experimental data of Kozloduy NPP “MCP switching on when the other three MCP are in operation”, with Relap5 calculations. The investigated thermal-hydraulic driven transient is characterized by spatially dependant non-symmetric processes. RELAP5/MOD3.2 computer code has been used to simulate the investigated transient. Operational data from Kozloduy NPP have been used for the purpose of assessing how the RELAP5 model compares against plant data. During the plant-commissioning phase at Kozloduy NPP Unit 6 a number of experiments have been performed. One of them is switching on MCP when the other three MCPs are in operation. The event is characterized by rapid increase in the flow through the core resulting in a coolant temperature decrease, which leads to insertion of positive reactivity due to the modeled feedback mechanisms. The main purpose of this investigation was to improve the discrepancy between the calculations and the plant data. The sensitivity calculation investigates the mixing in reactor vessel and influence of heat structure on the hot legs temperature. The areas of improvements to the Relap5 model are:

• •The non-symmetrical mixing in downcomer and reactor vessel annular exit.
• •The influence of heat structure temperature on the time delay for equipments measurements.
• •Investigation of pressurizer water level – using the hot legs temperature correction.

The RELAP5/MOD3.2 model of Kozloduy NPP VVER-1000 for investigation of operational occurrences, abnormal events, and design basis scenarios have been developed and validated in the Institute for Nuclear Research and Nuclear Energy – Bulgarian Academy of Sciences (INRNE-BAS) Sofia, and Kozloduy NPP. The model provides a significant analytical capability for the specialists working in the field of NPP safety.This investigation is a process that compares the analytical results obtained by the RELAP5 computer model of the VVER-1000 against the experimental transient data received from the Kozloduy NPP Unit 6. The comparisons indicate good agreement between the RELAP5 results and the experimental data. The sensitivity investigation improves the discrepancy between the calculation and the plant data.This investigation was possible through the participation of leading specialists from Kozloduy NPP and with the support of Argonne National Laboratory, under the International Nuclear Safety Program (INSP) of the United States Department of Energy.     

压水堆核电厂常规岛液态流出物排放管理探讨

本文根据《核电厂放射性液态流出物排放技术要求》(GB 14587—2011)的基本要求,提出基于核电厂蒸汽发生器排污水放射性控制进行常规岛液态流出物排放管理的思路,并针对M310/CPR1000、WWER、AP1000和EPR四种堆型工程设计及存在的问题,通过研究提出我国压水堆核电厂常规岛液态流出物的排放管理改进建议,可供核安全监管和核电厂设计、运行管理参考。     

空气中85Kr的分离与监测技术

概述了国际上通用的空气中^85Kr分离浓集和监测方法。重点比较了各种^85Kr分离浓集技术的特点，表明低温冷冻变温（或结合变压）处理方法是目前空气中^85Kr最好的浓集方式，而液闪测定是最为灵敏的探测手段。     

RELAP5/MOD3.2 sensitivity calculations of loss-of-feed water (LOFW) transient at Unit 6 of Kozloduy NPP

This paper provides a comparison between the real plant data obtained by Unit 6 of Kozloduy nuclear power plant (NPP) during the loss-of-feed water (LOFW) transient and the calculation results received by RELAP5/MOD3.2 computer model of the same NPP unit.RELAP5/MOD3.2 computer model of the VVER-1000 has been developed at the Institute for Nuclear Research and Nuclear Energy-Bulgarian Academy of Sciences (INRNE-BAS) based on Unit 6 of Kozloduy NPP. This model has been used for simulation the behavior of the real VVER-1000 NPP during the LOFW transient. Several calculations have been provided to describe how the different boundary conditions reflect on the prediction of real plant parameters.This paper discusses the results of the thermal–hydraulic sensitivity calculations of loss-of-feed water transient for VVER-1000 reactor design. The report also contains a brief summary of the main NPP systems included in the RELAP5 VVER model and the LOFW transient sequences.This report was possible through the participation of leading specialists from Kozloduy NPP and with the assistance of Argonne National Laboratory (ANL) for the United States Department of Energy (US DOE), International Nuclear Safety Program (INSP).