This paper describes a radiation sensor network system that can remotely monitor accidental area covered by high radiation in nuclear facilities. Each radiation sensor node is designed with radiation detector, radiation hardened readout circuit, microcontroller, and wireless communication module. In this paper, we will discuss sensor and circuit design configurations as well as initial radiation test results of a commercial wireless sensor module to verify how it works with the increase of irradiation doses. The measured data will be used to design a radiation hardened wireless communication system that can provide the most important information of monitoring radiation dose in accident nuclear sites where they are leaked in unseen area to mitigate such a severe accident situation in the very early stage. According to the initial measured result, the power consumption of some wireless modules were increased around 5.5 kGy and the others were increased around 7.2 kGy depending on various control factors while a module of PER was started to decrease around 1 kGy. The tests were performed with various configurations such as distance, frequency, transmitting power, and shielding material at the gamma irradiation facility containing cobalt 60 ? ray with high level activity of 490 kCi in KAERI. The measured data would be useful for researchers not only to find weak parts of the wireless module but also come up with radiation hardening methodologies for a common digital communication system. At the conference, more analyzed and collected data will be shared to discuss which part of the wireless communication system is weak and should be radiation hardened for exploiting specific applications, for example, severe accident monitoring system and unmanned system for nuclear decommissioning.