Search

Significant concerns after Fukushima disaster were raised on the potential of radioactive release from Spent Fuel Pool accidents. In case of CANDU type reactors a set of factors, such as the low discharge burnup of the spent fuel and the pool configuration with trays and racks placed on the bottom of the pool, contributes to the reducing of this potential. In this paper a peculiar state is analysed in relation with the refurbishment process, when a full core is added into the spent fuel pool, in a shorter time then the normal refuelling discharge. A prolonged loss of cooling is postulated in order to boil and evaporate the water. The claddings of the fuel bundles accidently entered in the air will be progressively heated and then degraded. Fission products will be released into the atmosphere of the spent fuel pool and, possibly, into the environment through the existing junctions. The paper investigates the source term formation at the level of the environment considering a prolonged accident without any interventions. The simulation is structured into three phases: de-watering of the pool, fuel degradation, transport of the radioisotopes to the environment. In order to estimate the maximum potential of the accident, three scenarios for the discharge of the core were considered, all of them requiring an enlarged cooling capacity in comparison with the normal refuelling, aiming a reduction of the duration of the refurbishment process to reduce the economic penalties. [ABSTRACT FROM AUTHOR]

In March 2011, severe nuclear accident happened at the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) after the gigantic earthquake and following huge tsunami wave. A lot of investigations to assess environmental and radiological impacts of released radionuclides have been conducted by domestic and international organizations. Environmental radioactivity research related to the FDNPP accident has spread widely over different scientific fields due to specific features of the accident, and specifically its impact on the marine environment. The present paper summarizes major lessons learned from the environmental investigations of the FDNPP accident. Environmental radioactivity studies have typical interdisciplinary character; especially physics and chemistry are fundamental as a base of process studies in the environment. In this sight, we review chemical aspects regarding FDNPP-derived radiocesium transfer within and between compartments (atmosphere, ocean and land). We also discuss future trends in investigations of behavior of anthropogenic radionuclides in the environment, important not only for a better understanding of impacts of the FDNPP accident on the environment, but also for improving our general knowledge of the total environment in the Anthropocene era and its protection for the future. • 10 years after the FDNPP accident, the environment has been contaminated mainly by Cs-137. • Understanding of Cs-transfer within and between compartments has considerably improved. • Chemical processes are a key factor of Cs-transfer between aquatic and solid phases. • Migration of Cs-137 in terrestrial and marine ecosystems will dominate in future studies. [ABSTRACT FROM AUTHOR]