ABSTRACT
Objective:To investigate radionuclide deposition in the systems related to the primary loop during the overhaul and refueling at a nuclear power plant.Methods:The radionuclides deposited in the main piping system, the primary loop coolant purification system, the volume and boron control system, the waste heat export system, and the inner wall of pipe in boron-containing water system were measured by using the low and medium radiation field high-purity germanium (HPGe) in-situ γ source term measurement system, the strong radiation field cadmium zinc telluride (CZT) in- situ γ source term measurement system, and the portable radiation monitoring instrument Radiagem-2000. Results:The result had shown that the major radionuclides deposited in the systems related to primary loop were mainly 58Co, 60Co, 95Nb, 95Zr, 51Cr, 124Sb, 54Mn, 110Ag *, 59Fe, and those with higher deposition were 60Co, 58Co, 124Sb, 95Zr. Of them, the largest deposition was 60Co up to 21 200 Bq/cm 2 in extra strong pipe below the safety valve, 58Co up to 8 480 Bq/cm 2 in the pipeline of hot section in the state of full water in the main pipeline. 124Sb was 4 910 Bq/cm 2 in pipeline before the filter of the primary loop purification system and 4 680 Bq/cm 2 in the chemical capacity drainage pipeline, respectively, and 95 Zr was 2 500 Bq/cm 2 in the pipeline of hot section in the state of full water in the main pipeline. The radionuclides deposited, after the filter of the purification system, in the pipe upstream of the boron-containing pump were significantly lower than those in other systems. Conclusions:The types of radionuclides in the systems associated with primary loop at a nuclear power plant are basically identical, but their amount deposited varies greatly. Attention should be paid to the removal of radionuclides in primary loop through the filter of purification system.
ABSTRACT
RESUMEN Los balnearios de aguas termales procedentes de capas geológicas profundas se han identificado como escenarios típicos de exposición a radiaciones de origen natural, tanto para los pacientes que se someten a los tratamientos como para los trabajadores de estas instalaciones, debido a la permanencia en lugares con niveles incrementados de radiación. Por ello se realizan en estos balnearios estudios de caracterización dirigidos a evaluar el impacto radiológico que producen sobre estas categorías poblacionales. El balneario de Elguea, ubicado en la costa norte de Villa Clara, está equipado para brindar servicios que emplean las aguas termales y los lodos en la zona del balneario. Las aguas de este balneario contienen niveles significativos de radón. En este trabajo se presentan las estimaciones de dosis realizadas a partir de la caracterización radiológica del balneario y su entorno, tanto para los trabajadores como para los pacientes que reciben tratamientos. Los valores de dosis estimados se encontraron en el intervalo de 1,01 a 180 μSv/año para los trabajadores, que resultó ser el grupo más irradiado, y no indicaron la necesidad de adoptar medidas o regulaciones especiales de protección.
ABSTRACT The use of hot spring waters from deep geologic layers in spas has been identified as typical scenarios of exposure to natural radiation. These scenarios can affect the patients under treatment, as well as the workers of these facilities. Therefore, characterization studies are being undertaken in these spas in order to evaluate the radiological impact they produce on these categories of population. The Elguea Spa, located on the northern coast of Villa Clara, Cuba, is equipped to provide services by using hot spring waters and mud existing in the zone of the spa. Its waters contain significant levels of radon. Present paper shows the dose estimates made from the radiological characterization of the spa and its surroundings, both for workers and the patients receiving treatment. The dose values are in the range of 1,01 to 180 μSv/year for workers, the most irradiated group, and these results suggest that there is no need for special protection measures or regulations.