Protection of Safety Critical Electric Circuits in NPP through Understanding of RFID and Wireless Communication Technology 서경호

Table of Contents Introduction RFID, Wireless LAN, and other wireless technologies Maxwell’s equations and wavenumber Conclusion and further study

Intorduction In the maintenance of NPP, the importance of ubiquitous network technology is growing. Ubiquitous network technology is composed of wireless communication, RFID, and so on. RFID industry (Radio Frequency Identification) is emerging as the key industry in the ubiquitous network society. All the technologies concerning RFID is based on the wireless technology. When we use RFID in NPP, safety issues should be considered mainly, because the electromagnetic wave used by RFID system can cause harmful effects on the electric circuits in NPP. Wireless technology is governed by the Maxwell’s equations. To understand the safety problem in using RFID and wireless technology, we should analyze the Maxwell’s equation.

RFID

Wireless LAN

Other wireless technology Zigbee (IEEE ) Frequency : 2.4 GHz ~ GHz Maximum data rate : 0.25 Mbps Range : 30 m Power consumption : 5~20 mW Bandwidth : 83.5 MHz Bluetooth (IEEE ) Frequency : 2.4 GHz ~ GHz Maximum data rate : 1 MBps Range : 10 m Power consumption : 40~100 mW Bandwidth : 83.5 MHz

Maxwell’s Equations To understand the electromagnetic phenomena, we need to know only electric field(E) and magnetic field(H) – 2 unknowns. But the Maxwell’s equation is composed of 4 equations. Does this mean mathematical contradiction?

Ampere’s Law + Gauss’ Law Continuity Equations Ampere’s Law Therefore, the 2 nd law of Maxwell’s equation already contains the 3 rd law !

Faraday’s Law + Magnetic Gauss’ Law Continuity Equations Faraday’s Law Therefore, the 1 st law of Maxwell’s equation already contains the 4 th law !

Protection of electric circuits in NPP All the electromagnetic phenomena can be explained by only two equations – Faraday’s law and Ampere’s law. The effect of RFID and wireless communication can be also explained by Faraday’s law and Ampere’s law. Therefore, to guarantee the safety when we use RFID and wireless communication technology in NPP, we should understand deeply the Maxwell’s equations.

Protection of electric circuits in NPP EM wave generally attenuates in reality. Therefore if we can control the intensity of the attenuation of EM wave, we can protect safety critical electric circuits in NPP from EM wave.

Wavenumber k To understand the attenuation of EM wave, we should understand the wave number k. In general physics, wave number k is defined as below. This definition means the wave number is a real number. But, actually the wave number k is not a real number – it is a complex number. Imaginary part of the wavenumber determines the attenuation of EM wave. Therefore if we want to understand the safety problem, we should analyze the wavenumber.

The Reason why k is a complex number The reason why k is a complex number is a complex number. New convention for k

Why k should be complex? Source free (charge density and current density are zero) version of Maxwell’s equation

Why k should be complex? Applying the curl operation, we get

Why k should be complex? If we substitute the complex wavenumber to the previous solution, we get As the EM wave propagate in the z-direction, z increases. Then decreases, and therefore the EM wave attenuates. For the heavy attenuation of EM wave to protect safety critical electrical circuits, we should increase the imaginary part of wavenumber – kappa.

Calculation of wavenumber New definition of wavenumber Complex wavenumber Complex electric permittivity

Calculation of wavenumber From the calculated kappa, we can find that the attenuation is governed by frequency, electrical permittivity, and electrical conductivity.

Derivation of the formula The minimum thickness “d” to guarantee the safety of electric circuits in NPP is as follows  Where r may be set by KINS or MOST…  r : amplitude attenuation ratio of EM wave  d : minimum thickness

Derivation of the formula Given “d”, whether the circuit is safe or not is determined by “s”. If “s” is positive, then the circuit is safe. If “s” is negative, then the circuit is not safe.

Conclusion & Further Study To guarantee the safety of electric circuits in NPP, we need heavy attenuation of EM wave used by RFID or wireless technologies. Attenuation of EM wave is governed by Maxwell’s equations. Application of previous formula to the real NPP should be studied further.