Environmental Radiation Protection, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
Health Phys. 2013 Aug;105(2 Suppl 2):S176-81. doi: 10.1097/HP.0b013e31829366b8.
Gaussian plume models, such as CAP88, are used regularly for estimating downwind concentrations from stack emissions. At many facilities, the U.S. Environmental Protection Agency (U.S. EPA) requires that CAP88 be used to demonstrate compliance with air quality regulations for public protection from emissions of radionuclides. Gaussian plume models have the advantage of being relatively simple and their use pragmatic; however, these models are based on simplifying assumptions and generally they are not capable of incorporating dynamic meteorological conditions or complex topography. These limitations encourage validation tests to understand the capabilities and limitations of the model for the specific application. Los Alamos National Laboratory (LANL) has complex topography but is required to use CAP88 for compliance with the Clean Air Act Subpart H. The purpose of this study was to test the accuracy of the CAP88 predictions against ambient air measurements using released tritium as a tracer. Stack emissions of tritium from two LANL stacks were measured and the dispersion modeled with CAP88 using local meteorology. Ambient air measurements of tritium were made at various distances and directions from the stacks. Model predictions and ambient air measurements were compared over the course of a full year's data. Comparative results were consistent with other studies and showed the CAP88 predictions of downwind tritium concentrations were on average about three times higher than those measured, and the accuracy of the model predictions were generally more consistent for annual averages than for bi-weekly data.
高斯烟羽模型，如 CAP88，常用于估算烟囱排放物下风处的浓度。在美国的许多设施中，美国环保署（U.S. EPA）要求使用 CAP88 来证明遵守空气质量法规，以保护公众免受放射性核素排放的影响。高斯烟羽模型的优点是相对简单，使用起来务实；然而，这些模型基于简化的假设，通常不能纳入动态气象条件或复杂的地形。这些局限性鼓励进行验证测试，以了解模型在特定应用中的能力和局限性。洛斯阿拉莫斯国家实验室（LANL）地形复杂，但由于需要遵守《清洁空气法案》第 H 款，因此必须使用 CAP88。本研究的目的是使用释放的氚作为示踪剂，通过环境空气测量来测试 CAP88 预测的准确性。使用 CAP88 对来自两个 LANL 烟囱的氚排放进行了测量，并使用当地气象数据对其进行了扩散建模。在烟囱的各个距离和方向上进行了氚的环境空气测量。在一整年的数据中，对模型预测和环境空气测量进行了比较。比较结果与其他研究一致，表明 CAP88 预测的下风处氚浓度平均比测量值高约三倍，并且模型预测的准确性通常更一致，适用于年平均值，而不是两周平均值。
