Statistical Characterization of Cable Electrical Failure Temperatures Due to Fire for Nuclear Power Plant Risk Applications

Single-value failure temperatures for fire loss of electrical cable functionality have been the norm for Fire Probabilistic Risk Assessments since the publication in 2005 of NUREG/CR-6850. If the calculated exposure temperature matches or exceeds the cable failure temperature, electrical failure is always assumed; if not, no failure is assumed. While this can be relaxed somewhat if a distribution for the exposure temperature is estimated, use of a distribution on the cable failure temperature itself more readily enables such relaxation and, therefore, a more realistic assessment. This paper develops probability distributions for different generic cable types (based on insulation) using data from the US Nuclear Regulatory Commission tests. Results indicate mean failure temperatures considerably higher than those used deterministically, 252°C, 421°C and 383°C, respectively for thermoplastic, thermoset and Kerite-FR^®. This suggests considerable relaxation from the conservatism inherent using the deterministic failure temperatures could be achieved. The paper then postulates two hypothetical distributions on the exposure temperature from applying a fire phenomenological model in a statistical way to estimate the possible relaxation using the distributed cable failure temperatures to enhance the realism of the assessment. Examples show that use of probabilistically-distributed cable failure temperatures (in conjunction with similar for exposure temperatures) can reduce the probability of electrical failure for a normally-distributed exposure temperature with a mean of 350°C and standard deviation of 58.3°C by factors of approximately three and eight for Kerite-FR^® and thermoset cables, respectively. The reduction would be less pronounced for thermoplastic cables, although larger reductions would be possible here as well for lower exposure temperatures (e.g., a factor of two).     

A Comparison of a Statistical and Computational Fluid Dynamics Approach to Estimate Heat Release Rate in Road Tunnel Fires

Computational tools such as one-dimensional models or Computational Fluid Dynamics (CFD) have been used for the fire safety design of road tunnels. However, most of these analyses are performed using a specified fire source where the heat release rate (HRR) in the tunnel is fixed by the user and the influences of ventilation conditions and tunnel geometry are not considered. For a more realistic estimate, models need to incorporate these factors in their input. This paper discusses the use of a statistical approach previously developed by other researchers (Carvel and Beard, The handbook of tunnel fire safety. Thomas Telford Publishing, pp 184–197, 2005) and the use of a CFD approach to estimate the HRR in a road tunnel fire. As an application example, fire scenarios in which a light goods vehicle carrying wooden pallets are used to compare the estimation of the HRR using these two methods.     

Electrical Power Cord Damage from Radiant Heat and Fire Exposure

Nine SPT-1 and SPT-2 type two conductor energized appliance power cords were exposed to radiant heat and to flames in the presence and absence of combustible materials. The power cords consisted of integral and non-integral insulated multistranded 18 AWG copper conductors. The objectives of exposing these power cords to radiant heat and flame are to: evaluate the performance of the power cords in fire environments, and characterize the electrical activity and material damage sustained by the power cords. Data was recorded for 713 power cords tested under six different conditions. Not all of the power cords tested showed evidence of electrical fault activity. However, each power cord exposed to a radiant heat flux of 40 kW/m² in the presence of combustible material exhibited signs of electrical fault activity. Damage to the copper conductors varied from localized fusing to complete severance. Power cords exposed to a radiant heat flux of 40 kW/m² in the absence of combustibles did not always exhibit signs of electrical fault activity. Test data did not show any significant correlations among types of power cord damage/electrical activity and fire conditions.     

方家山核电工程核仪表系统改进

核仪表系统(RPN)是核电站重要的安全系统。秦山核电厂扩建项目(方家山核电工程)核仪表系统采用了基于Rolls-Royce Civil Nuclear的SPINLINE 3的数字化技术。与参考电站核仪表系统采用的模拟技术相比,数字技术从一定程度上精简了设备配置,简化了系统内、外部接口设计,提高了设备的在线自诊断能力,缩短了检修和维护时间,相应地提高了核电厂的可靠性和经济性。     

热电厂余热回收利用的初步探讨

根据低碳供暖的理念,以热电联产为平台,采用热泵技术开发多种低温能源用于供热。在供热系统末端,将暖气片用户和地暖用户串联供热,实现热能的梯级利用。依据供暖期各阶段的热负荷变化进行供热调节,同时,在非采暖季,开发非采暖季热力产品,实现热电多产。结合实例,与传统供暖方式进行比较分析,说明该供热系统在经济、节能环保等方面的优越性。     

核电厂建设用地的合理规划

由于核电站的建设需要占用大量的土地资源,因此,核电厂工程建设用地的规划必须认真贯彻国家节约和集约用地的基本国策.文章在项目的选址、设计和建造的各个阶段,对工程的建设用地做到科学规划,严格执行用地指标,节约集约用地,提高土地利用率方面分别进行了论述.     

浅谈核电厂生产待命管理模式

核电厂生产待命是指在非正常工作时间,当机组发生运行瞬态或任何其他异常事件后,技术人员随时准备向运行值班人员提供支持的一种状态。生产待命管理是运行核电厂的一项非常重要的工作,关系到应急状态下电厂技术人员能否立即提供支持的问题,甚至关系到核安全。因此,对该课题的研究具有一定的现实意义。     

台山核电搅拌站片冰输送系统

介绍了台山核电搅拌站片冰输送系统的特点,冰的存储与运输,生产高质量冰的技术保证和冰输送控制系统。     

水源热泵回收电厂冷却水废热供热工程实例

介绍了利用水源热泵回收电厂冷却水废热进行集中供热的工程实例,分析了经济环保效益.     

核电厂中排水隧道的二次衬砌施工技术

目前,大部分隧道常用的一次衬砌形式已无法满足核电工程对结构强度及安全性的要求,因此需对已建隧道再浇筑二次衬砌来满足隧道在核电领域的特殊使用要求.以秦山核电厂扩建项目（方家山核电工程）排水隧道及排放口工程为背景,阐述了在一端封闭的盾构隧道内利用针梁式模板台车施工全圆内衬的施工技术,取得了良好的施工成效,可供类似工程参考.     

滨海核电厂地基处理方法综述

滨海核电厂的建设场地通常需进行开挖山体、填海造陆。通过对海底淤泥处理、场地推填、夯实、局部特殊区域处理的介绍,结合宁德核电厂的具体应用实例对适用于滨海核电厂的地基处理方案进行了总结,为同类工程提供借鉴。     

核电厂土石方量计算影响因素分析

场地平整土石方为一动态平衡过程,其受设计输入、设计和施工等多方面因素的影响。论文分析了7个因素对土石方量计算的影响,进行了综合评价,并对部分因素提出了控制方案。     

热电厂首站换热器配置节电研究

针对某热电厂首站采用立式全焊板壳式换热器代替卧式管壳式热网加热器,对4种换热器与循环泵配置方案下的供热参数及循环泵功率进行了比较。采用2台立式全焊板壳式换热器与1台循环泵的小流量高温差运行不仅可满足供热要求,还可降低循环泵耗电量。     

田湾核电站安全壳预应力管道施工技术

田湾核电站3号、4号机组采用VVER堆型,由俄罗斯圣彼得堡设计院负责总体设计,属于三代技术核电项目.3号、4号机组反应堆厂房内壳采用VSL NC6-55预应力系统,管道施工具有管道孔径大、倒U形布置、钢梯布置密集等特点,通过对预应力管道施工技术的研究,为该类堆型预应力施工积累宝贵经验.     

核电站标准预埋件选型设计

核电站核岛厂房标准预埋件要求安全可靠、形式简单、选用方便,其受力多为空间的拉弯剪状态,现行的国标预埋件设计方法难以满足使用专业的选型要求,论文根据CPR、EPR核电项目核岛预埋件设计经验,结合国标的相关要求,提供了一种新的预埋件设计思路,灵活运用相关规范,计算得出便于使用的预埋件选型图表。     

核电站安全阀结构抗震性能分析及评定

安全阀是确保核电站安全运行的重要设施。因此,在设计和使用中必须考虑安全阀结构在正常运行、重大事故和地震作用下的工作性能,从而保证安全阀结构在各种可能的荷载作用下不受损坏。本文采用大型通用有限元程序ANSYS,对安全阀结构有限元模型进行了模态分析、时程分析和谱分析,并通过对各工况计算结果的处理,验证了安全阀结构在各种工况作用下其应力水平和动态响应能够满足我国核电相关规范的规定,该结构安全可靠,具备良好的抗震性能。     

岭澳核电站核岛厂房地下防水施工及质量控制

介绍地下防水施工选用的必坚定３０００自粘性防水卷材的性能、铺贴方法及各道工序的质量控制要求。