Pfeiffer W C, Penna-Franca E, Ribeiro C C, Nogueira A R, Londres H, Oliveira A E
An Acad Bras Cienc. 1981 Dec;53(4):683-91.
Two types of portable instruments were developed by the former Health and Safety Laboratory of the U.S. Atomic Energy Commission to characterize external gamma radiation fields and to estimate individual exposure dose rates from major natural or fission radionuclides distributed in the soil: a pressurized ionization chamber and a NaI(T1) gamma-ray spectrometer. The two instruments were used to measure environmental radiation exposure rates at three distinct geological areas of Brazil: - in the towns of Guarapari and Meaípe located on the monazite sand belt, ES. - on the vicinities of the uranium mine of Poços de Caldas, MG. - around the site of the Brazilian first nuclear power plant, in Angra dos Reis, RJ. The radiometric survey demonstrated once more the usefulness and versatility of the two instruments used. The measurements around the nuclear installations of Poços de Caldas and Angra dos Reis, allowed a rapid assessment of the local radiation background and its variability, as well as the selection of stations for the routine monitoring program. Radioactive anomalies were detected and characterized previously to the start of plant operations. The survey in Guarapari and Meaípe confirmed the results obtained by Roser and Cullen in 1958 and 1962, except on sites where considerable changes took place since then. The spectrometric measurements gave estimations of the relative proportion of 40K, 238U and 232Th series in the ground and also indications on the homogeneity of their distribution in the soil.
美国原子能委员会前健康与安全实验室开发了两种便携式仪器，用于表征外部伽马辐射场，并估算土壤中分布的主要天然或裂变放射性核素所致的个人照射剂量率：一种是加压电离室，另一种是碘化钠（铊）伽马射线能谱仪。这两种仪器被用于测量巴西三个不同地质区域的环境辐射照射率：——位于圣埃斯皮里图州独居石砂带的瓜拉帕里和梅阿佩镇；——米纳斯吉拉斯州波苏斯卡尔达斯铀矿附近；——里约热内卢州安格拉杜斯雷斯巴西第一座核电站厂址周围。辐射测量再次证明了所使用的这两种仪器的实用性和多功能性。在波苏斯卡尔达斯和安格拉杜斯雷斯的核设施周围进行的测量，有助于快速评估当地的辐射本底及其变化情况，以及为常规监测计划选择监测站。在核电站运行开始之前就检测到并表征了放射性异常情况。在瓜拉帕里和梅阿佩进行的调查证实了罗泽和卡伦在1958年和1962年所获得的结果，但自那时以来发生了重大变化的地点除外。能谱测量给出了地面中40K、238U和232Th系列相对比例的估算值，还给出了它们在土壤中分布均匀性的指示。
