1.1 本试验方法描述了测量反应堆容器和支撑结构监测暴露期间诱发的核反应在辐射监测器（RMs）中产生的放射性核素的比活度的程序。中确定的单独标准中提供了单个RMs的更详细程序 2.1 参考文献中 ( 1- 5. ) . 2. 测量结果可用于定义相应的中子诱导反应速率，进而用于表征反应堆容器和支撑结构的辐照环境。主要测量技术是高分辨率伽马射线- 射线光谱法，尽管X射线光子光谱法和β粒子计数在较小程度上用于特定的均方根值 ( 1- 29 ). 1.1.1 测量程序包括探测器背景辐射校正、随机和真实符合求和损耗、校准源标准和均方根值之间的几何差异、均方根值对辐射的自吸收、其他吸收效应、放射性衰变校正和相关核素的烧损 ( 6- 26 ). 1.1.2 通过考虑计数持续时间、计数开始和辐照结束之间的经过时间、半衰期、RM中目标核素的质量以及相关辐射的分支强度来计算比活度。 利用适当的半衰期和已知的辐照条件，可以将特定的活性转化为相应的反应速率 ( 2- 5. , 28- 30 ) . 1.1.3 包括根据放射性测量和辐照功率时间历程计算反应速率的程序。可以使用适当的积分截面和有效辐照时间值将反应速率转换为中子注量率和注量，并且可以通过使用适当的计算机程序使用其他反应速率来定义中子谱 ( 2- 5. , 28- 30 ) . 1.1.4 使用基准中子场校准均方根值可以显著减少或消除系统误差，因为计算绝对反应速率所需的许多参数及其各自的不确定性对于基准测量和测试测量都是常见的，因此是自抵消的。测试环境的基准等效注量率可以通过两个环境中测量的饱和放射性活度与经认证的基准注量率的正比来计算 ( 2- 5. , 28- 30 ) . 1.2 本试验方法拟与ASTM指南一起使用 E844 以及直接参与反应堆容器和支撑结构监督测量的物理剂量学评估的现有或拟议ASTM实践、指南和测试方法。 1.3 本试验方法中的程序适用于以均方根表示的放射性测量，均方根满足其分析的特定约束和条件。有关单个RM监控器的更详细程序，请参见 2.1 参考文献中 1- 5. （参见 表1 ). 1.4 本试验方法以及单个RM监测器标准方法旨在供熟悉程序、设备和技术的知识丰富的人员使用，以实现放射性测量的高精度和准确性。 1.5 以国际单位制表示的数值应视为标准值。本标准不包括其他测量单位，但基于电子伏、千电子伏和兆电子伏的能量单位以及时间单位:分钟（min）、小时（h）、天（d）和年（a）除外。 1.6 本标准并非旨在解决与其使用相关的所有安全问题（如有）。本标准的用户有责任在使用前制定适当的安全、健康和环境实践，并确定监管限制的适用性。 1.7 本国际标准是根据世界贸易组织技术性贸易壁垒（TBT）委员会发布的《关于制定国际标准、指南和建议的原则的决定》中确立的国际公认标准化原则制定的。 ====意义和用途====== 5.1 辐射监测器应提供经验证的被动剂量测定技术，用于确定各种中子场中的中子注量率（通量密度）、注量和频谱。需要这些数据来评估和估计核反应堆结构材料（如反应堆压力容器及其支撑结构中使用的钢）可能受到的长期辐射损伤。 5.2 许多辐射监测器、其相应的中子活化反应和放射性反应产物以及这些RMs和产物的一些相关核参数列于 表1 . 表2 提供数据 ( 37 ) 关于重要裂变监测器的累积和独立裂变产额。这些表中不包括对光裂变产额的贡献，这对非裂变核素可能特别重要 ( 2- 5. , 27- 29 , 38- 41 ) . （A） 所有产量数据均以百分比形式给出，相关不确定性以1σ水平的百分比形式给出。 （B） 用于裂变产额评估 ( 37 ) “Fast”表明，数据是从广泛的基于反应堆的裂变中子谱中提取的，其特征是平均能量约为0。 4兆电子伏。U-238和Th-232的几乎所有裂变反应都发生在有效阈值能量约1mev以上，而Np-237的裂变反应发生在有效阈值能量约0.2mev以上。

1.1 This test method describes procedures for measuring the specific activities of radioactive nuclides produced in radiometric monitors (RMs) by nuclear reactions induced during surveillance exposures for reactor vessels and support structures. More detailed procedures for individual RMs are provided in separate standards identified in 2.1 and in Refs ( 1- 5 ) . 2 The measurement results can be used to define corresponding neutron induced reaction rates that can in turn be used to characterize the irradiation environment of the reactor vessel and support structure. The principal measurement technique is high resolution gamma-ray spectrometry, although X-ray photon spectrometry and Beta particle counting are used to a lesser degree for specific RMs ( 1- 29 ). 1.1.1 The measurement procedures include corrections for detector background radiation, random and true coincidence summing losses, differences in geometry between calibration source standards and the RMs, self absorption of radiation by the RM, other absorption effects, radioactive decay corrections, and burn out of the nuclide of interest ( 6- 26 ). 1.1.2 Specific activities are calculated by taking into account the time duration of the count, the elapsed time between start of count and the end of the irradiation, the half life, the mass of the target nuclide in the RM, and the branching intensities of the radiation of interest. Using the appropriate half life and known conditions of the irradiation, the specific activities may be converted into corresponding reaction rates ( 2- 5 , 28- 30 ) . 1.1.3 Procedures for calculation of reaction rates from the radioactivity measurements and the irradiation power time history are included. A reaction rate can be converted to neutron fluence rate and fluence using the appropriate integral cross section and effective irradiation time values, and, with other reaction rates can be used to define the neutron spectrum through the use of suitable computer programs ( 2- 5 , 28- 30 ) . 1.1.4 The use of benchmark neutron fields for calibration of RMs can reduce significantly or eliminate systematic errors since many parameters, and their respective uncertainties, required for calculation of absolute reaction rates are common to both the benchmark and test measurements and therefore are self canceling. The benchmark equivalent fluence rates, for the environment tested, can be calculated from a direct ratio of the measured saturated activities in the two environments and the certified benchmark fluence rate ( 2- 5 , 28- 30 ) . 1.2 This test method is intended to be used in conjunction with ASTM Guide E844 and existing or proposed ASTM practices, guides, and test methods that are also directly involved in the physics-dosimetry evaluation of reactor vessel and support structure surveillance measurements. 1.3 The procedures in this test method are applicable to the measurement of radioactivity in RMs that satisfy the specific constraints and conditions imposed for their analysis. More detailed procedures for individual RM monitors are identified in 2.1 and in Refs 1- 5 (see Table 1 ). 1.4 This test method, along with the individual RM monitor standard methods, are intended for use by knowledgeable persons who are intimately familiar with the procedures, equipment, and techniques necessary to achieve high precision and accuracy in radioactivity measurements. 1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard, except for the energy units based on the electron volt, keV and MeV, and the time units: minute (min), hour (h), day (d), and year (a). 1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.7 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. ====== Significance And Use ====== 5.1 Radiometric monitors shall provide a proven passive dosimetry technique for the determination of neutron fluence rate (flux density), fluence, and spectrum in a diverse variety of neutron fields. These data are required to evaluate and estimate probable long-term radiation-induced damage to nuclear reactor structural materials such as the steel used in reactor pressure vessels and their support structures. 5.2 A number of radiometric monitors, their corresponding neutron activation reactions, and radioactive reaction products and some of the pertinent nuclear parameters of these RMs and products are listed in Table 1 . Table 2 provides data ( 37 ) on the cumulative and independent fission yields of the important fission monitors. Not included in these tables are contributions to the yields from photo-fission, which can be especially significant for non-fissile nuclides ( 2- 5 , 27- 29 , 38- 41 ) . (A) All yield data are given as a percentage with associated uncertainties given as percentages of the percentage at the 1σ level. (B) For this fission yield evaluation ( 37 ) , “Fast” indicates that the data was extracted from a wide range of reactor-based fission neutron spectra that can be characterized as having an average energy of ~0.4 MeV. Almost all of the fission reactions for U-238 and Th-232 occur above an effective threshold energy of ~1 MeV and, for Np-237, above ~0.2 MeV.