重水堆核电厂在线测氚系统抽气方式的改进

重水堆核电厂利用电离室分析技术进行氚浓度监测。为解决其在线实时氚测量系统不能连续对多个区域进行测量的不足，提高测氚系统可靠性，对测氚系统抽气方式进行了改进。在线按序测氚改进后的测量结果，提高了氚浓度测量的准确性和实时性，为核电厂反应堆厂房内的氚泄漏定位和人员辐射防护提供了重要依据。      

红外吸收光谱法测定高浓度重水

本文建立了高浓度重水分析方法,其具有快速、简便、用量少、样品无需处理可直接测定的优点。本方法精密度高,测定浓度为99.80%时,相对标准偏差小于0.001%;在浓度范围为99.92%～99.67%时,线性相关系数R=0.999 9。高浓度重水的红外吸收光谱法已用于研究堆重水监测,能准确快速反映系统的重水浓度,为重水反应堆的安全运行提供重要参数。     

堆芯热工水力参数测量

在研究性重水反应堆改建中,为提高热工分析的准确度,以保证反应堆安全运行,在工程启动和试运行中,进行了反应堆压力室流量分配测量、惯性流量测量和元件表面温度测量。     

傅里叶变换红外光谱法测定重水含量

高浓重水既是反应堆的冷却剂又是减速剂，为确保反应堆的安全运行，必须严格监控重水浓度。在反应堆运行期间，净化系统中树脂的氘化、脱氘工艺的控制分析以及重水电解浓缩工艺的控制分析，均需测定D2O浓度。     

研究性重水反应堆冷却回路~(16)N的测量和计算

一、前言重水反应堆运行时,由于重水本身受快中子的辐照,产生强放射性的~(16)N,它发射高能γ,是冷却回路γ放射性的主要来源。在设计冷却回路生物屏蔽层时,其厚度主要决定于~(16)N的γ源强。此外,国外很多动力堆还利用~(16)N的γ放射性强度来监测反应堆的热功率,它具有响应时间快、不引起通量畸变等优点。因此,确切地给出冷却回路重水中~(16)N的放射性强度,无论从为堆的安全运行提供辐射剂量数据,或是为冷却回路屏蔽设计提供经验均是很有意义的。本文叙述了在我国研究性重水堆上所采用的测量和计算冷却回路重水中~(16)N浓度的方法和结果。     

间隔分布法测量反应堆动态参数

本文介绍了反应堆中子计数统计学中的间隔分布方法的简单原理和数据处理方法。给出了测量系统的方块图和在DF—3零功率反应堆、高浓铀重水零功率反应堆上测量动态参数的结果,并与其他方法测量结果进行了比较。     

红外光谱法在线测量高浓度重水

为了准确、快速、安全定量工艺系统中的高浓度重水,采用离线式傅里叶变换红外光谱仪,以空光路状态下的单光束谱为背景光谱,得到不同浓度标准重水样品的红外吸收光谱,对3 410 cm~(-1)处重水浓度与吸光度进行线性拟合,建立红外光谱法测量高浓度重水的工作曲线。在此基础上,设计重水在线测量方案,实现高浓度重水在线测量。结果表明,测量浓度为99.85%的重水时,相对标准偏差优于0.01%。重水浓度范围为99.06%～99.98%时,线性相关系数R~2=0.999 9。该测量方法准确、快速、无损样品、无放射性辐照等,可拓展到其他浓度段重水在线测量。     

红外光谱法在线测量高浓度重水

为了准确、快速、安全定量工艺系统中的高浓度重水，采用离线式傅里叶变换红外光谱仪，以空光路状态下的单光束谱为背景光谱，得到不同浓度标准重水样品的红外吸收光谱，对3410cm^-1处重水浓度与吸光度进行线性拟合，建立红外光谱法测量高浓度重水的工作曲线。在此基础上，设计重水在线测量方案，实现高浓度重水在线测量。结果表明，测量浓度为99.85%的重水时，相对标准偏差优于0.01%。重水浓度范围为99.06%~99.98%时，线性相关系数R²=0.999 9。该测量方法准确、快速、无损样品、无放射性辐照等，可拓展到其他浓度段重水在线测量。     

热态反应性实时监测及重水堆光激中子本底源的确定

在反应堆运行过程中,实时监测堆内反应性的大小,对于保证反应堆的安全具有十分重要的意义。为此,我们发展了一用于实时监测热态反应性大小的FORTRAN程序,并在重水研究性反应堆(HWRR)上进行了实验。实验证明该程序能够实现热态反应性的实时监测。此外,我们还从对正常运行状态下的实时反应性值的统计分析得到了光激中子源本底的大小,为确定重水堆光激中子源大小提供了一个新的方法。实验结果表明,在正常闭环运行状态(11000kW)下,重水研究性反应堆(HWRR)的光激中子源本底的反应性当量为 1.09×10~(-3)＄。     

重水浓度与吸光度关系曲线类型研究

重水作为反应堆的慢化材料，其浓度直接影响反应堆的安全和性能。为研究其重水浓度与吸光度间的关系曲线类型，基于朗伯-比尔定律，从理论上推导出液态重水中某种水分子的红外吸收峰分别与0~2种其他水分子的红外吸收峰发生重叠时重水浓度与吸光度间的关系式，分情况对二者之间的关系曲线类型进行讨论。采用傅里叶变换红外光谱仪，测得浓度为0.015%~99.98%（摩尔比）的重水标准样品吸收光谱，对重水浓度和吸光度间的关系曲线类型进行验证，理论推导与实际吻合。研究表明，一般情况下，宽浓度范围内，重水浓度与吸光度间的关系曲线类型为二次曲线；窄浓度范围内，关系曲线类型为线性。特殊情况下，吸光度为定值或关系曲线类型为线性。     

反应堆重水系统干燥试验

为彻底干燥反应堆重水系统管道和设备,解决阀门阀体底部蓄水、干燥设备吹扫死角等干燥试验技术难点,采用干空气吹扫与抽真空结合的干燥方法、加热干空气和设备局部加热等措施,通过监测系统出口处空气露点变化和系统整体保真空试验,准确测定并确保了系统干燥程度达到要求.适量重水充入系统后,浓度微降0.02%,说明干燥有效、彻底.     

含氚重水脱氚方法

CANDU6核电站慢化剂重水中的氚浓度随反应堆运行而增加,含氚重水以气态或者液态向反应堆厂房及环境中泄漏,将造成运行人员辐射剂量及环境污染。如何有效将慢化剂重水中的氚脱除受到国际上广泛的关注。本文调研国内外重水脱氚技术,对各种现有脱氚技术进行了系统的比较与分析,总结了各工艺的优缺点及经济性。     

Experimental determination of the boron concentration distribution in the primary circuit of a PWR after a postulated cold leg small break loss-of-coolant-accident with cold leg safety injection

It is known that under-borated coolant can accumulate in the loops and that it can be transported towards the reactor core during a loss-of-coolant-accident. Therefore, the mixing of weakly borated water inside the reactor pressure vessel was investigated using the ROCOM test facility. Wire-mesh sensors based on electrical conductivity measurement are used to measure in detail the spreading of a tracer solution in the facility. The mixing in the downcomer was observed with a measuring grid of 64 azimuthal and 32 vertical positions. The resulting distribution of the boron concentration at the core inlet was measured with a sensor integrated into the lower core support plate providing one measurement position at the entry into each fuel assembly.

The boundary conditions for this mixing experiment are taken from an experiment at the thermal hydraulic test facility PKL operated by AREVA Germany. The slugs, which have a lower density, accumulate in the upper part of the downcomer after entering the vessel. The ECC water injected into the reactor pressure vessel falls almost straight down through this weakly borated water layer and accelerates as it drops over the height of the downcomer. On the outer sides of the ECC streak, lower borated coolant admixes and flows together with the ECC water downwards. This has been found to be the only mechanism of transporting the lower borated water into the lower plenum. In the core inlet plane, a reduced boron concentration is detected only in the outer reaches of the core inlet. The minimum instantaneous boron concentration that was measured at a single fuel element inlet was found to be 66.3% of the initial 2500 ppm.     

Structural Material Anomaly Detection System Using Water Chemistry Data, (VII)

Abstract

A method to detect small changes in water quality and diagnose their causes by analyzing on-line conductivity and pH data was proposed. Laboratory tests showed that effective noise reduction of measured on-line data could be got by using a median filter to detect small changes of conductivity; a relative change of 0.001 μS/cm was distinguishable. By simulating the changes of pH and conductivity in the reactor water against a small concentration change of sodium ion or sulfate ion in the feedwater, it was found that an adequate elapsed time for the diagnosis was 4 h from the start of the concentration change. A conductivity difference of 0.001 μS/cm in the reactor water made it theoretically possible to distinguish between a sodium ion concentration change of 4.6 ppt and a sulfate ion concentration change of 9.6 ppt in the feedwater.     

Computed Tritium Concentration in a Heavy-Water Reactor

The solutions of a system of equations governing the accumulation of tritium and helium in the heavy water of a reactor are presented for arbitrary initial conditions. The solutions are presented as functions of heavy-water exchange and helium extraction. The concentration change is illustrated for typical values of the thermal-neutron flux density. __________ Translated from Atomnaya Energiya, Vol. 99, No. 3, pp. 210–214, September, 2005.     

Transient behaviors of heavy water reflector system during postulated initiating events (PIEs)

This study investigates the transient thermal-hydraulic behaviors of a heavy water reflector system during various postulated initiating events (PIEs). The following events are considered in the analysis: (1) loss of heavy water system (HWS) flow, (2) heavy water leakage, (3) loss of secondary cooling flow, and (4) dilution of heavy water. The sequence of each event is described, and thermal-hydraulic parameters such as the heavy water temperature, system pressure, flow rate, and heavy water level are monitored. To regulate the HWS, the heavy water temperature at the outlet of the heavy water vessel, the heavy water level in the expansion tank, and the flow rate in the HWS are used as the reactor regulating system (RRS) setbacks. In the event of loss of HWS flow, the standby pump kicks off to recover it, and none of the RRS setback signals are triggered. In the event of heavy water leakage, a low-level RRS setback signal trips the reactor, and the temperature rise in the HWS is not significant. The total amount of heavy water leakage with a break at the outlet of the heat exchanger is approximately 550 L. In the event of loss of secondary cooling flow, a high-temperature RRS setback signal trips the reactor. In the event of heavy water dilution, a low-level RRS setback signal trips the reactor. In the case of a pipe rupture at the highest point in the HWS inside the pool, the RRS setback signal is triggered at 83.9 s from the initiation. At the instant of the reactor trip, the reactor power increases to 150% of full power because of the degraded purity of the heavy water––95.7%. For the event of heavy water dilution, a reactor protection system (RPS) setback such as the reactor power difference between a neutron detector and a gamma detector should be used to trip the reactor.     

Sliding mode observer design for a PWR to estimate the xenon concentration & delayed neutrons precursor density based on the two point nuclear reactor model

One of the important operations in nuclear power plants is load-following in which imbalance of axial power distribution induces xenon oscillations. These oscillations must be maintained within acceptable limits otherwise the nuclear power plant could become unstable. Therefore, bounded xenon oscillation considered to be a constraint for the load-following operation. In other hands, precursors produce delayed neutrons which are most important in control of nuclear reactor, but xenon concentration & precursor density cannot be measured directly. In this paper, non-linear sliding mode observer which has the robust characteristics facing the parameters uncertainties and disturbances is proposed based on the two point nuclear reactor model to estimate the xenon concentration & delayed neutron precursor density of the Pressurized-Water Nuclear Reactor (PWR) using reactor power measurement. The stability analysis is given by means Lyapunov approach, thus the system is guaranteed to be stable within a large range. The employed method is easy to implement in practical applications. This estimation is done taking into account the effects of reactivity feedback due to temperature and xenon concentration. Simulation results clearly show that the sliding mode observer follows the actual system variables accurately and is satisfactory in the presence of the parameters uncertainties & disturbances.