IOSR Journal of Computer Engineering (IOSR-JCE) e-ISSN: 2278-0661,p-ISSN: 2278-8727, Volume 17, Issue 4, Ver. II (July – Aug. 2015), PP 29-35 www.iosrjournals.org DOI: 10.9790/0661-17422935 www.iosrjournals.org 29 | Page Performance Analysis of Three Hop Reliability Model for Wireless Sensor Networks in Nuclear Power Plants S.Lavanya 1 , Dr. S. Prakasam 2 1 (Research Scholar, Dept of CSA, SCSVMV University, Kancheepuram, India 2 (Asst.Professor and Head, Dept. of CSA, SCSVMV University, Kancheepuram, India) Abstract: Wireless sensor networks(WSN) are a good choice for Nuclear Power Plants because of low cost and flexibility. Reliability is a crucial factor for WSN in Nuclear Power Plants since all the data collected are time critical information that should be delivered on time otherwise a huge loss could incur in terms of money, resource or even human lives. So it is a challenging task to design a routing protocol for sensor used in such harsh environments. In Three hop reliability model (3H-ACK), three copies of the same data are maintained without imposing extra cost on the network. This model works best using zone routing protocol .Compared to the models used earlier, this 3H-ACK performs well in terms of delivery ratio, throughput and avoids packet loss as far as possible. Keywords: Acknowledgment, Nuclear Power Plants, Reliability, Sensor Networks, I. Introduction Wireless Sensor Networks (WSN) are used nowadays in Nuclear Power Plants (NPP). Sensors can be used to monitor the current state of the plant including emission of radioactive particles to air and water. Other parameters include neutron flux, monitoring pressure, temperature and water levels in circuits. If these levels exceed a particular threshold levels alarm is raised and information is passed on to the alerting unit whenever necessary. Daily more than 7, 00,000 data are to be collected and send to the base station. Manual maintenance of such data is a tedious task. The challenges posed by WSN in NPP are EMI/RFI, compatibility of WSN in harsh nuclear environment, energy concerns, security and reliability. From authors[1-4] it has been proven that WSN does not pose a threat to EMI/RFI. Moreover suitable test from [1] shows that WSN can withstand harsh conditions in nuclear environments. Fig. 1 Technical Components used in Nuclear Power Stations There are lots of factors that are to be considered when deploying a WSN for a Nuclear Power Plant [4]. First it is necessary to understand the measurement requirement. The purpose for which sensors are used should be known very clearly. Secondly appropriate wireless protocol such as IEEE 802.11 or IEEE 802.15 should be chosen. The chosen protocol must co-exist with other protocols. Finally, deployment of sensor nodes is yet another important issue that is to be considered properly. In this paper, Section II explains the reliability issues in Sensor Networks. Hop- by-Hop and 2H-ACK models are described. Section III explains 3H-ACK model. The architecture and algorithms are used explained. Section IV explains the simulation parameters and section V gives the conclusion. II. Reliability In Sensor Networks Reliability is a key aspect in wireless sensor networks. Reliability is the ratio of number of bits in error to the total number of bits transmitted. Bit error rate should be minimal in such applications. It has been shown that Transport Control Protocol does not work very well with sensors since the three -way handshake procedure causes overhead. TCP relies on end – end acknowledgment whereas wireless sensor networks use multi-hop Alarm Systems Central Database (Sink) Communication Server Nuclear Power Plant Client systems