1.1 本试验方法描述了通过活化反应测量反应速率的程序 93 Nb（n，n ′ ) 930万 注意。 1.2 该活化反应对于监测能量高于约0.5 MeV的中子以及高达48年（三个半衰期）的辐照时间非常有用，前提是实际中描述的分析方法 E261 遵循。 1.3 通过适当的技术，可以在快中子注量大于10%的情况下确定能量分布类似于裂变中子的中子的快中子反应速率 16 厘米 −2. . 在存在高热中子注量率（>10）的情况下 12 厘米 −2. · s −1. )的嬗变 930万 应调查中子俘获引起的Nb。在高能中子谱（如与聚变和散裂源相关的高能中子谱）存在的情况下，中子的嬗变 930万 Nb可能发生（n，2n）等反应，应进行研究。 1.4 实践中参考了其他快中子监测器的程序 E261 . 1.5 如果适当的横截面信息可满足精度要求，则可以根据反应速率确定快中子注量率。 1.6 以国际单位制表示的数值应视为标准值。本标准不包括其他计量单位。 1.7 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。 1.8 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 参考实践 E261 关于用阈值探测器测定衰变率、反应率和中子注量率的一般性讨论 ( 1- 29 ) . 3. 参考实践 E1006年 实践 E185 和指南 E1018 用于使用和应用本试验方法获得的结果。 ( 30- 32 ) 5.2 的半衰期 930万 Nb为16.1（2） 4. 年 5. ( 34 ) 每次衰变的X射线发射概率为0.11442±3.356% ( 35 ) . K α 和K β 铌的X射线分别为16.521–16.615和18.607–18.9852 keV ( 35 ) . 推荐的 93 Nb（n，n ′ ) 930万 Nb横截面来自国际反应堆剂量测定和聚变文件（IRDFF版本1.05，横截面概要 ( 36 ) ，如所示 图1 . 该核数据评估是俄罗斯反应堆剂量测定文件（RRDF）横截面评估的一部分 ( 37 ) . 此处引用的核衰变数据并非来自最新的剂量测定推荐数据库 ( 33 ) 但选择与推荐IRDFF评估中使用的核数据一致。 图1 RRDF/IRDFF-1.05横截面与能量的关系 93 Nb（n，n ′ ) 930万 铌反应 5.3 化学溶解辐照铌以产生单位面积极低质量的源是获得一致结果的有效途径。只要采用适当的方法和解释，箔或导线的直接计数可以产生令人满意的结果。如果放射性物质可以均匀地保存在溶液中，并且可以对干扰活动进行适当校正，则可以使用液体闪烁法测量铌放射性。 5.4 测量的反应速率可用于关联中子暴露，与计算的反应速率进行比较，并确定中子注量。 由于横截面与能量形状的当前不确定性，可以比通量率更精确地确定反应速率。 5.5 这个 93 Nb（n，n ′ ) 930万 铌反应具有监测与核设施结构部件中子损伤相关的中子暴露的理想特性。它具有与钢的损伤功能相对应的能量响应范围，并且具有足够长的半衰期，以允许其在非常长的暴露（高达48年）下使用。监测长期暴露有助于确定长期风险- 核设施部件的术语完整性。

1.1 This test method describes procedures for measuring reaction rates by the activation reaction 93 Nb(n,n ′ ) 93m Nb. 1.2 This activation reaction is useful for monitoring neutrons with energies above approximately 0.5 MeV and for irradiation times up to about 48 years (three half-lives), provided that the analysis methods described in Practice E261 are followed. 1.3 With suitable techniques, fast-neutron reaction rates for neutrons with energy distribution similar to fission neutrons can be determined in fast-neutron fluences above about 10 16 cm −2 . In the presence of high thermal-neutron fluence rates (>10 12 cm −2 · s −1 ), the transmutation of 93m Nb due to neutron capture should be investigated. In the presence of high-energy neutron spectra such as are associated with fusion and spallation sources, the transmutation of 93m Nb by reactions such as (n,2n) may occur and should be investigated. 1.4 Procedures for other fast-neutron monitors are referenced in Practice E261 . 1.5 Fast-neutron fluence rates can be determined from the reaction rates provided that the appropriate cross section information is available to meet the accuracy requirements. 1.6 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.7 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. 1.8 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 Refer to Practice E261 for a general discussion of the determination of decay rates, reaction rates, and neutron fluence rates with threshold detectors ( 1- 29 ) . 3 Refer to Practice E1006 , Practice E185 and Guide E1018 for the use and application of results obtained by this test method. ( 30- 32 ) 5.2 The half-life of 93m Nb is 16.1 (2) 4 years 5 ( 34 ) and has a K X-ray emission probability of 0.11442 ± 3.356 % per decay ( 35 ) . The K α and K β X-rays of niobium are at 16.521–16.615 and 18.607–18.9852 keV, respectively ( 35 ) . The recommended 93 Nb(n,n ′ ) 93m Nb cross section comes from the International Reactor Dosimetry and Fusion File (IRDFF version 1.05, cross section compendium ( 36 ) , and is shown in Fig. 1 . This nuclear data evaluation is part of the Russian Reactor Dosimetry File (RRDF), cross section evaluations ( 37 ) . The nuclear decay data referenced here are not taken from the latest dosimetry recommended database ( 33 ) but are selected to be consistent with the nuclear data used in the recommended IRDFF evaluation. FIG. 1 RRDF/IRDFF-1.05 Cross Section Versus Energy for the 93 Nb(n,n ′ ) 93m Nb Reaction 5.3 Chemical dissolution of the irradiated niobium to produce very low mass-per-unit area sources is an effective way to obtain consistent results. The direct counting of foils or wires can produce satisfactory results provided appropriate methods and interpretations are employed. It is possible to use liquid scintillation methods to measure the niobium activity provided the radioactive material can be kept uniformly in solution and appropriate corrections can be made for interfering activities. 5.4 The measured reaction rates can be used to correlate neutron exposures, provide comparison with calculated reaction rates, and determine neutron fluences. Reaction rates can be determined with greater accuracy than fluence rates because of the current uncertainty in the cross section versus energy shape. 5.5 The 93 Nb(n,n ′ ) 93m Nb reaction has the desirable properties of monitoring neutron exposures related to neutron damage of nuclear facility structural components. It has an energy response range corresponding to the damage function of steel and has a half-life sufficiently long to allow its use in very long exposures (up to about 48 years). Monitoring long exposures is useful in determining the long-term integrity of nuclear facility components.