One effort to protect the environment from the increasing of potentially environmental radiation hazards as an impact of radiation discharge around nuclear facilities is by a continuous monitoring of the environmental radiation in real time It is important to disclose the dose rate information to public or authorities for radiological protection. In this research, we have designed a nuclear preparedness early warning system around the Serpong nuclear facility. The design is based on Arduino program, general packet radio service (GPRS) shield, and radio frequencies technology to transmit environmental radiation result of the measurement and meteorological data. Data was collected at a certain location at The Center for Informatics and Nuclear Strategic Zone Utilization BATAN Serpong. The system consistency models are defined by the quality of data and the level of radiation exposure in the deployed environment. Online users can access the website which displays the radiation dose on the environment marked on Google Map. This system is capable to issue an early warning emergency when the dose reaches three times of the background radiation exposure value, 250 nSv/hour.