Astuto A, Fernandes S S, Patrão K C S, Fonseca E S, Pereira W W, Lopes R T
Universidade Federal do Rio de Janeiro-COPPE/UFRJ. Av. Horácio Macedo, 2030, Bloco G/Sala 206-Centro de Tecnologia-Cidade Universitária, Ilha do Fundão, Rio de Janeiro, RJ, Brasil.
Fundação Técnico Educacional Souza Marques-FTESM. Av. Ernani Cardoso, 335, Cascadura, Rio de Janeiro, RJ, Brasil.
Radiat Prot Dosimetry. 2018 Aug 1;180(1-4):56-61. doi: 10.1093/rpd/ncy028.
The standard thermal neutron flux unit, TNF2, in the Brazilian National Ionizing Radiation Metrology Laboratory was rebuilt. Fluence is still achieved by moderating of four 241Am-Be sources with 0.6 TBq each. The facility was again simulated and redesigned with graphite core and paraffin added graphite blocks surrounding it. Simulations using the MCNPX code on different geometric arrangements of moderator materials and neutron sources were performed. The resulting neutron fluence quality in terms of intensity, spectrum and cadmium ratio was evaluated. After this step, the system was assembled based on the results obtained from the simulations and measurements were performed with equipment existing in LNMRI/IRD and by simulated equipment. This work focuses on the characterization of a central chamber point and external points around the TNF2 in terms of neutron spectrum, fluence and ambient dose equivalent, H*(10). This system was validated with spectra measurements, fluence and H*(10) to ensure traceability.
巴西国家电离辐射计量实验室的标准热中子通量装置TNF2进行了重建。通量仍然通过对四个活度均为0.6 TBq的241Am-Be源进行慢化来实现。该设施再次进行了模拟，并重新设计为石墨芯，并在其周围添加了石蜡石墨块。使用MCNPX代码对慢化剂材料和中子源的不同几何排列进行了模拟。评估了所得中子通量在强度、能谱和镉比方面的质量。在此步骤之后，根据模拟结果组装系统，并使用LNMRI/IRD现有的设备和模拟设备进行测量。这项工作重点在于对TNF2中心腔点和周围外部点在中子能谱、通量和环境剂量当量H*(10)方面进行表征。该系统通过能谱测量、通量和H*(10)进行了验证，以确保可追溯性。
