The influence of the working conditions on the equilibrium factor F and the unattached fraction fp

We report on the influence of the working conditions on the dose estimation. Especially the equilibrium factor and the unattached fraction are influenced by the working conditions. For instance in a cabinet-maker’s shop the radon concentration is strongly influenced by the ventilation system. The factor F is influenced by dust-producing work processes. For a better knowledge of the radon dosimetry it is also necessary to measure continuously and separately the unattached fraction of the radon progeny. We present first results obtained with a SARAD EQF 3020 monitor which contains three alpha detector microsystems measuring radon in the air, attached radon daughters and unattached radon daughters. The three components are measured quasicontinuously with a temporal resolution of 2 hours. The measuring range is 1 to 10 MBq/m3 at a low detection limit of 0.1 Bq/m3 equivalent radon concentration. The system was tested in buildings, caves, mines, waterworks and other places. By using silicon microsystems with alpha detector, ADC, memory and logics—which are integrated on few chips—the costs for the production of equipment are far lower than if produced by means of assembled individual components

EPOS- a multiparameter measuring system to earthquake research

El estudio de la predicción de sismos por medio de datos geofísicos, geoquímicos e hidrológicos requiere de información tomada con equipos en tiempo real, así como el modelado de los datos estadísticos. En este artículo se presentan avances en este campo, mediante el desarrollo de un nuevo sistema versátil de medición EPOS, por sus siglas en inglés (Sistema de Observación de Precursores de Sismos), el cual está basado en experiencias y resultados recientes de diferentes grupos. EPOS es una estación de medición de multiparámetros, que puede continuamente registrar, en función del tiempo, hasta 17 parámetros geoquímicos y geofísicos apropiados para la investigación de seísmos. Un sistema micro computarizado dentro de EPOS procesa transferencia, control y almacenamiento de datos desde un sistema modular de sensores. El número de módulos con sensores puede ser también seleccionado de acuerdo con las necesidades del sitio de medición. Se presentan pruebas exitosas de los resultados de EPOS trabajando durante dos años en la estación de Dos Arroyos, México, en la costa del Pacífico. doi: https://doi.org/10.22201/igeof.00167169p.2002.41.3.34

An electronic radon dosimeter as a new multipurpose device – a bridge between dosimetry and monitoring

Un dosímetro electrónico para medir radón basado en el depósito de sus productos de decaimiento en un detector semicon- ductor acoplado a un espectómetro á, ofrece algunas ventajas con respecto a los dosímetros pasivos. La dosis y la concentración de radón se calculan y sus valores aparecen en la carátula durante la exposición y los límites de dosis preestablecidos pueden verse a través de una función de alerta. Los cambios rápidos en la concentración de radón pueden detectarse y la dosis correspondiente se mide, así como su distribución temporal. El tratamiento de datos por computadora permite cambiar las medidas de enlace como conversión de dosis o factor de equilibrio. Una interface permite la comunicación con la PC. El dosímetro electrónico de radón es fácil de manejar y capaz de responder en condiciones de trabajo rudo. Una segunda aplicación del dosímetro es la determinación de radón en objetos o áreas. La posibilidad de medir radón en el suelo o en agua permite al usuario resolver problemas de riesgo de radón, así como tópicos en geología, prospección de uranio o protección ambiental. doi: https://doi.org/10.22201/igeof.00167169p.2002.41.3.34

Radon leakage assessment in a controlled radon laboratory

Como parte de las actividades para tener un laboratorio calibrado de radón en México, se utilizaron detectores DOSEman, Alpha GUARD y de Germanio para medir la concentración de radón en una cámara fuente de radón. Los primeros dos detectores se usaron también para determinar la concentración de radón durante la operación normal de la cámara y en un experimento controlado de fuga de radón. La concentración de radón en la cámara se determinó con el detector de Germanio midiendo la emisión ã de los productos de decaimiento 214Bi y 214Pb. El error en la actividad fue del 3.5%. La diferencia de esa medida con los DOSEman fue del 3%. La curva experimental de decaimiento del radón, determinada con el detector alpha GUARD, difiere 2% del valor esperado. La cámara de radón está en un laboratorio licenciado de 280 m3 de volumen. Esta se dejó abierta durante un fin de semana para investigar el incremento de la concentración de radón en el laboratorio en un caso extremo de fuga. El incremento de la concentración de radón fue del 60% encima del fondo, lo cual muestra que no existe riesgo para el personal en el peor caso de fuga del radón. doi: https://doi.org/10.22201/igeof.00167169p.2002.41.3.34

Smart card for detection of alpha radiation

A microsystem for measuring alpha radiation and processing radiation dose is presented. The radiation sensor is built on a PIN diode. The measurement results are transmitted wirelessly to a host computer. Under defined measurement conditions the peak spectrum of the radiation can be exactly calculated. In real-world environments sources of alpha radiation can be detected

Diurnal variations of radon and thoron activity concentrations and effective doses in dwellings in Niska Banja, Serbia

In NiUka Banja, a spa town in a radon-prone area in southern Serbia, radon (Rn-222) and thoron (Rn-220) activity concentrations were measured continuously for one day in indoor air of 10 dwellings with a SARAD RTM 2010-2 Radon/Thoron Monitor, and equilibrium factor between radon and its decay products and the fraction of unattached radon decay products with a SARAD EQF 3020-2 Equilibrium Factor Monitor. Radon concentration in winter time ranged from 26 to 73 100 Bq m(3) and that of thoron, from 10 to 8650 Bq m(3). In the same period, equilibrium factor and the unattached fraction varied in the range of 0.08 to 0.90 and 0.01 to 0.27, respectively. One-day effective doses were calculated and were in winter conditions from 4 to 2599 Sv d(1) for radon and from 0.2 to 73 Sv d(1) for thoron

Monitoring of earthquake precursors by multi-parameter stations in Eskisehir region (Turkey)

The objective of this study was to investigate the geochemical and hydrogeological effects of earthquakes on fluids in aquifers, particularly in a seismically active area such as Eskisehir (Turkey) where the Thrace–Eskisehir Fault Zone stretches over the region. The study area is also close to the North Anatolian Fault Zone generating devastating earthquakes such as the ones experienced in 1999, reactivating the Thrace–Eskisehir Fault. In the studied area, Rn and CO2 gas concentrations, redox potential, electrical conductivity, pH, water level, water temperature, and the climatic parameters were continuously measured in five stations for about a year. Based on the gathered data from the stations, some ambiguous anomalies in geochemical parameters and Rn concentration of groundwater were observed as precursors several days prior to an earthquake. According to the mid-term observations of this study, well-water level changes were found to be a good indicator for seismic estimations in the area, as it comprises naturally filtered anomalies reflecting only the changes due to earthquakes. Also, the results obtained from this study suggest that both the changes in well-water level and gas–water chemistry need to be interpretated together for more accurate estimations. Valid for the studied area, it can be said that shallow earthquakes with epicentral distances of <30 km from the observation stations have more influence on hydrochemical parameters of groundwater and well-water level changes. Although some hydrochemical anomalies were observed in the area, it requires further observations in order to be able to identify them as precursors

Radiolysis via radioactivity is not responsible for rapid methane oxidation in subterranean air.

Atmospheric methane is rapidly lost when it enters humid subterranean critical and vadose zones (e.g., air in soils and caves). Because methane is a source of carbon and energy, it can be consumed by methanotrophic methane-oxidizing bacteria. As an additional subterranean sink, it has been hypothesized that methane is oxidized by natural radioactivity-induced radiolysis that produces energetic ions and radicals, which then trigger abiotic oxidation and consumption of methane within a few hours. Using controlled laboratory experiments, we tested whether radiolysis could rapidly oxidize methane in sealed air with different relative humidities while being exposed to elevated levels of radiation (more than 535 kBq m-3) from radon isotopes 222Rn and 220Rn (i.e., thoron). We found no evidence that radiolysis contributed to methane oxidation. In contrast, we observed the rapid loss of methane when moist soil was added to the same apparatus in the absence of elevated radon abundance. Together, our findings are consistent with the view that methane oxidizing bacteria are responsible for the widespread observations of methane depletion in subterranean environments. Further studies are needed on the ability of microbes to consume trace amounts of methane in poorly ventilated caves, even though the trophic and energetic benefits become marginal at very low partial pressures of methane