Comparison and Evaluation of Domestic and Foreign Radiation Environmental Standards for Nuclear Power Plants

With the development of the nuclear energy industry and the increasing demand for environmental protection, the impact of nuclear power plant radiation on the environment has gradually entered the public view. This article combs the nuclear power plant radiation environmental management systems of several countries, takes the domestic and foreign management of radioactive effluent discharge from nuclear power plants as a starting point, analyses and compares the laws and standards related to radioactive effluents from nuclear power plants in France, the United States, China, and South Korea. In this paper, the management improvement of radioactive effluent discharge system of Chinese nuclear power plants has been discussed.

Characteristics of Radioactive Effluent Releases from Pressurized Water Reactors after Permanent Shutdown

In order to expand our understanding of the characteristics of radioactive effluent from nuclear power plants under decommissioning, which have not been systematically investigated, a series of source term models of radioactive effluent after permanent shutdown has been established based upon theoretical reasoning on the design and operation features of plants and derived in terms of fifteen arguments. Comprehensive radioactive effluent data have been collected and profiled from twenty-eight decommissioning pressurized water reactors, and annual trends of effluent from each plant have been quantitatively analyzed using Mann-Kendall statistical test. In addition, the characteristics of collected effluent data have been qualitatively interpreted based upon arguments newly proposed in this study. Furthermore, potential decreasing of dilution factor for liquid effluent and its safety implications are identified. The source term models and verified characteristics of radioactive effluent after permanent shutdown developed in this study can be used for establishing more efficient discharge monitoring program for decommissioning authorization.

Radiological dose assessment due to hypothetical nuclear power plant operation in Mersing, Johor, Malaysia

Malaysia has considered for some time to adopt nuclear power to cater to the increasing demand of electricity following other developed Asian countries such as Japan, Korea, and China. In implementing a nuclear power plant, strict regulations and guidelines by the International Atomic Energy Agency (IAEA) and International Commission on Radiological Protection (ICRP) must be fulfilled before any construction license is given for a new nuclear power program. One of the assessments include the estimation of potential radiological risks to both humans and environment from routine and accidental release of radioactive effluent from the nuclear power plant (NPP). In this work, simulations of radionuclide dispersion from a hypothetical NPP site in Mersing, Johor will be presented. The simulation was performed based on the Lagrangian atmospheric dispersion model using the HYSPLIT software. The radioactive effluent release rate was approximated to the value found in the Fukushima Dai-ichi accident in 2011. Meteorological data of 2017 were utilized in this study. Simulation results showed that the dispersion of radioactive effluent from the hypothetical NPP can potentially affect areas around Johor Bahru district, Singapore, and even some areas in Indonesia.

Experimental Study on Bioclogging in Porous Media during the Radioactive Effluent Percolation

The sand columns inoculated with the indigenous microorganism (Aspergillus niger) were used to investigate the effect of bioclogging during the radioactive effluent percolation. The hydraulic gradient, volumetric flow rate, and uranyl ions concentration were monitored over time. The sand columns were operated with continuous radioactive effluent of uranium tailings reservoir. After 68 days, the hydraulic conductivity of the sand columns decreased more than 72%, and the adsorption rate of uranyl ions by Aspergillus niger reached more than 90%. Environmental scanning electron microscope imaging confirmed the biofilm covering the surface of sand particles and connecting sand particles together, which resulted in a reduction of hydraulic conductivity. The results indicated that the propagation of Aspergillus niger can clog the seepage channel and effectively adsorb the uranyl ions of radioactive effluent in the porous media, which provides a suitable measure for controlling the migration of radioactive effluent of uranium tailings reservoir into the subsurface environment.